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Case report An 18-month-old Charolais steer was presented with lameness and fluctuant swelling of the right stifle joint, which yielded neutrophils on fine-needle aspiration. A diagnosis of bacterial proliferative tenosynovitis and arthritis was made on postmortem and histological examination. Culture and 16S rRNA sequencing identified a Nocardia sp. with 99% homology with the corresponding DNA fragment of N. mexicana DSM 44952. Antimicrobial susceptibility testing revealed the isolate was susceptible to co-trimoxazole and third-generation cephalosporins. Conclusion We report the first case, both in Australia and internationally, of proliferative tenosynovitis and arthritis caused by Nocardia spp. infection in a bovine and the first report of pathology attributed to N. mexicana in a veterinary patient. Given the limited susceptibility of the bacteria, the poor antimicrobial penetration that would be expected and the morphological changes that had taken place in the joint; the steer would have required protracted antimicrobial treatment in addition to invasive debridement of the lesion. This case emphasises the importance of routinely performing cytology and extended incubation of cultures in cases of arthritis in order to make ethical and economically viable treatment decisions. [ABSTRACT FROM AUTHOR]

The impact of cold stress on feedlot cattle has received limited investigation in temperate climates. However, cold stress has been found to impact cattle welfare and production in temperate climatic conditions, where ambient temperature (T A ), precipitation, relative humidity (RH), wind speed (WS) and solar radiation (SR) all influencing apparent temperature. While there are many indices to quantify cold stress in cattle, there are limited indices that directly relate to cattle and account for all the interactions between climatic variables. This makes cold stress difficult to quantify, with on-cattle measures such as core body temperature and shivering difficult metrics to obtain in feedlot cattle. Moreover, individual cattle will react differently to cold conditions based on their production, age, sex, coat characteristics (colour and type), breed and nutrition. While cold stress can be difficult to measure, the production status, behavioural and physiological effects of cold stress have been identified, but generally under what could be considered as extreme cold stress events. Similarly, while mitigation strategies such as shelter, bedding and windbreaks have been investigated, limited information is available surrounding their usefulness in temperate climates. Further research is needed to fully investigate the effects of cold stress and how to mitigate those effects in feedlot cattle under conditions, such as those found in Australia., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Heat wave intensity, frequency, and duration are increasing in many regions of the world, including locations where highly productive livestock are raised. There are animal health and welfare, as well as economic impacts from these events. In this study, the physiological responses of grain-fed steers during a high heat load challenge through to recovery in climate-controlled rooms ( CCR ) were intensively evaluated. Two cohorts of 12 Black Angus steers (BW, 615.4 ± 40.1 kg) sequentially underwent a simulated heatwave event that consisted of 3 phases in the CCR: PreChallenge (5 d duration and temperature humidity index ( THI ) range of 65 to 71), Challenge (7-d duration and THI 66 to 95 with diurnal cycling), and Recovery (5 d duration and THI 65 to 70). The Challenge period was modeled on a severe heat wave, characterized by 3 very hot days. Individual rumen temperature ( RumT , °C) was collected every 10 min, and respiration rate ( RR , breaths per minute), panting score ( PS ), and water usage (L·steer -1 ·day -1 ) were obtained at multiple time points daily, by trained observers. Individual animal daily DMI was also determined. Morning (0700 hours) rectal temperature ( RecT , °C) was measured on days 3, 5, 7 to 13, 15, and 17. Not unexpectedly, RumT, RecT, RR, and PS rose during Challenge and fell rapidly as conditions eased. Conversely, DMI was reduced during Challenge. During the transition between PreChallenge and Challenge, there were abrupt increases in RumT, and RR. It was also very apparent that during Recovery the steers did not return to the baseline PreChallenge state. Compared to PreChallenge, Recovery was characterized by persistent lowered daily mean RumT ( P  = 0.0010), RecT ( P  = 0.0922), RR ( P  = 0.0257), PS ( P  ≤ 0.0001), and DMI ( P  ≤ 0.0001). These results provide evidence that these steers have undergone an allostatic response in response to high heat load, and the new adjusted physiological state post-heat event may not be transient., Competing Interests: None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science.)

This review makes an attempt to characterize the physical attributes of heat tolerance, thermal equilibrium and thermal stress thresholds for dairy cows living in tropical environments, with a particular emphasis on pasture-based systems. Under such circumstances, the radiant heat load is the principal climatic factor that determines rates of heat and mass exchanges between cows and the environment. This fact may explain why simple mechanistic models based on air temperature and humidity are not adequately predicting thermal stress thresholds for cattle in tropical regions. To overcome this limitation, the Index of Thermal Stress for Cows (ITSC) and Index for the time spent in shade (ITS), which account for various sources of thermal radiation, were proposed to predict autonomous and behavioral thermoregulation of cows. Overall, the evolutionary adaptation of cattle in tropics favored animals that have cutaneous surface with a skin well protected against penetration of ultraviolet solar radiation (UV), covered by a coat surface with high thermal conductivity. For Holstein breed, although predominantly black animals absorb greater levels of short-wave solar radiation, they may present better protection of skin than white ones. However, dark-colored cows in tropical pastures have potential to absorb as much as 640 W m -2 of thermal radiation. This amount of heat load would require close to 1,300 g h -1 of cutaneous evaporative water loss through sweating to prevent increases to body temperature, where cows do not have access to shade. Cows are motivated to reduce time spent grazing and to seek shade when solar irradiance exceeds 550 W m -2 , levels that in equatorial latitudes are likely to occur between 08:00 and 16:00h. This information may help producers improve the welfare of cows, as they can determine more comfortable hours for them to graze, for example, by employing nocturnal grazing. Over the daytime, cows should have access to areas with shade and this could include shade provided via solar panels, which has the potential to improve thermal comfort and sustainability of dairy production in tropical areas., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Santos, Saraiva, Gonzaga Neto, Maia, Lees, Sejian, Maia, Medeiros and Fonsêca.)

It has been well-established that dark cutting (DC) is a multifactorial issue that is associated with numerous animal and management factors. However, there is limited understanding of the feedlot-based factors that contribute to the influence of DC. The aim of this study was to evaluate the effect of climate, animal, and feedlot factors on the incidence of pH non-compliance in Australian grain-fed cattle. For this study, feedlot and abattoir records from 142,228 individual cattle over a 1-year period were investigated. These data incorporated records from seven feedlots that consigned cattle to three abattoirs. The average incidence of DC in these carcasses was 2.8%. The production factors that were associated with increased risk of DC included feedlot, sex, hormone growth promotants (HGP), cattle health, and days on feed (DOF). Additionally, DC also increased by reduced solar radiation (SR, W/m 2 ), lower wind speeds (WS, m/s), increased ambient temperature (T A , °C), higher rainfall, a higher average temperature-humidity index (THI), and increased duration of time above heat-load-index threshold of 86 (HLI ≥ 86) during the 7 days prior to feedlot departure. This study identified the feedlot factors that increase the risk of DC from a feedlot-management perspective.

The objective of this study was to evaluate the influence of supplementing lactating dairy cows with Saccharomyces cerevisiae on milk production and composition, cow behavior, and physiological responses during summer. Twenty primiparous cows were used and two treatments were imposed: (1) control (CON); and (2) probiotic supplementation (PRO; S. cerevisiae, providing 10 10 colony forming units (CFU) per day). Rumen temperature (T RUM , °C) and pH were obtained via rumen boluses. Rumen temperatures were obtained from all cows (n = 20) at 10-min intervals and ruminal pH were obtained from five cow pairs (n = 10) at 10-min intervals. Ambient temperature (T A ; °C), relative humidity (RH; %), wind speed (WS; m/s), and solar radiation (SR; W/m 2 ) were recorded at 10-min intervals. The temperature humidity index (THI) was calculated using T A and RH. Cows were milked twice daily. Milk fat (%), protein (%), lactose (%), and somatic cell count (SCC, '000) were evaluated on 16 occasions. Cows were observed three times (0800 h; 1200 h; and 1400 h) daily for panting score (PS); respiration rate (RR); posture (standing/lying); shade utilization; and cow activity (eating/drinking/ruminating). Individual PS were used to calculate a mean panting score (MPS) for CON and PRO treatments for each observation. S. cerevisiae did not influence milk yield (P = 0.87), fat (P = 0.82), protein (P = 0.26) or SCC (P = 0.19), although there was a tendency for PRO cows to have higher lactose (P = 0.06). Probiotics did not influence the proportion of cows utilizing shade (P = 0.42); standing (P = 0.41); ruminating (P = 0.72); or drinking (P = 0.40). All cows exhibited an increase in RR (> 24 bpm) at 1200 h and RR showed a steady increase as THI increased (P < 0.0001), regardless of treatment (P = 0.96). Both CON (35.8%) and PRO (40.2%) exhibited an increase in MPS as THI increased from thermoneutral (THI ≤ 74) to very hot (THI ≥ 84.1; P < 0.001). However, PRO cows had lower (2.19 ± 0.09; P < 0.0001) MPS compared with CON (2.54 ± 0.22) cows when THI was categorized as very hot (THI ≥ 84.1). Rumen pH were not influenced by treatment (P = 0.38), however T RUM of PRO cows were 0.2 °C lower across days (P < 0.0001) and hours (P < 0.0001). These results suggest that supplementing cows with S. cerevisiae may support thermoregulation via decreased T RUM and MPS; however, further studies are required., (© 2021. ISB.)

Numerous climatic indices have been utilized to predict the effect of hot, and cold, climatic conditions on animal production and welfare. To date, the dairy industry has relied extensively on the Temperature Humidity Index (THI) to predict adverse climatic conditions; however, neither solar radiation nor air movement is accounted for in the THI equation. The Dairy Heat Load Index (DHLI) was initially developed as an alternative climate index. In its current format, the DHLI does not account for the effects of heat load mitigation strategies, such as shade, which decreases the negative effects of hot climatic conditions on lactating cows. Therefore, this experiment aimed to determine the effectiveness of the DHLI as a predictor of heat load responses in both shaded and unshaded cows, as compared with the THI. Forty lactating Holstein Friesian (n = 40) cows were selected and paired based on live weight, milk yield, and days in milk. One cow from each pair was randomly allocated to one of two treatments: shaded (n = 20) or unshaded (n = 20). Cows were given 7 days to acclimate prior to the commencement of data collection. After 28 days, cows were transitioned into the alternate treatment in a crossover design and given 7 days to acclimate prior to data collection. Behavioral observations (0800, 1200, 1400, and 1800 h daily), daily milk yield (kg), milk composition (various days), and vaginal temperature (T VAG , °C; 5 pairs/week, over a 4-week rotation) were recorded. Overall, data from this experiment indicated that the DHLI was a better predictor of standing and feeding behaviors in unshaded cows and drinking behaviors in shaded cows. Conversely, the THI was a better predictor of standing behavior and shade usage in shaded cows. Furthermore, the THI was a better predictor of mean panting score (MPS) in shaded cows, whereas the DHLI performed better in unshaded cows. Additionally the DHLI was a better predictor of T VAG in these cows. Finally, when evaluating the 7-day average of each climatic index, the DHLI was a better predictor of change in milk yield. Incorporation of additional animal and management factors is required if the DHLI is to become an effective heat load management tool., (© 2021. ISB.)

The objective of this study was to investigate the effect of acute and chronic heat load events on scrotal temperature (ST), body temperature (BT) and bull behaviour, and to examine the interrelationship between these parameters; the underlying hypothesis was that adverse heat treatments delivered in a temperature controlled environment will lead to thermoregulatory dysfunction of the bull scrotum. Six sexually mature Wagyu bulls were used in this study with data loggers surgically implanted into the abdominal cavity and scrotum. Body temperate and ST were recorded at 30-min intervals for the duration of the study. There were two housing locations used throughout the study, outdoor pens and climate control rooms. The study was designed as a four-phase crossover design with two heat treatments: (1) a 5-day acute challenge, and (2) a 14-day chronic challenge. The study was also blocked by phase to control for systematic change between phases with a thermoneutral (TN) phase in outdoor pens between each heat challenge. Observations within the climate rooms were conducted at 1-h intervals and data on panting scores (PS), respiration rate (RR), posture (standing or lying) and general behaviours (feeding, drinking, ruminating) recorded. Ambient temperature (AT, °C) and relative humidity (RH, %) were obtained at 10-min intervals and used to calculate the temperature humidity index (THI). Multiple models were conducted using a linear mixed effects model that contained different permutations of date and time factors and interactions as well as inclusion of an autoregressive parameter. The strongest model based on Akaike's information criterion (AIC) was selected and further analysed. Ambient conditions during heat treatments were consistent with heat load and bulls showed typical physiological symptoms of the same. Maximum ST for acute and chronic treatments occurred once AT had exceeded 34 °C for at least 3 h (acute 35.59 °C at 1500 h; chronic 35.18 °C at 1400 h), whereas during TN conditions, maximum ST was at 2100 h. All phases showed variation in ST throughout the day. There were strong cross correlations between ST and RR during the heat treatments (acute r = 0.918, P < 0.0001; chronic r = 0.916, P < 0.0001), but not during TN (r = 0.411, P < 0.05). Our results confirmed that the ST of the bulls used in this study was not held at a constant temperature and that there was a possible connection between ST and RR. We have shown that during a period of heat load, the thermoregulatory mechanisms thought responsible for maintaining bovine ST appear to breakdown., (© 2021. ISB.)

This study conducted a retrospective analysis of historical Meat Standard Australia (MSA) carcass data in combination with Bureau of Meteorology (BOM) weather data, to evaluate the relationship between climatic conditions prior to feedlot departure on the incidence of dark cutting grain-fed beef. Data records for 2,795,754 carcasses from 17 commercial feedlots over a 6-year period were evaluated within this study. Carcasses were consigned to 16 abattoirs. Weather data from BOM were recorded at 30-min intervals and were obtained from weather stations with the closest proximity to each feedlot. These data were used to calculate the Temperature Humidity Index (THI). Climatic data were amalgamated into daily observations and a series of predictors including ambient temperature (T A , °C), relative humidity (RH, %), wind speed (WS, m/s), rainfall (mm) and THI. In addition, lag interactions from 24 h out to 28 days prior to exiting the feedlot were generated. The incidence of dark cutting was determined as percentage per cohort with an ultimate pH > 5.7. Data were analysed using three models: model 1 included feedlot, abattoir, hormone growth promotant status and sex as fixed effects. Model 2 incorporated the fixed effects within model 1 and minimum, maximum and standard deviation (SD) of T A and RH, daily range in T A , average WS and rainfall as random effects. Model 3 incorporated minimum, maximum, range and SD of THI, average WS and rainfall as random effects in addition to the fixed effects of model 1. The incidence of dark cutting within feedlot had a 10.1% range in estimated means with the lowest incidence was observed at feedlot 17 (0%) and highest incidence at feedlot 10 (10.1%). The inclusion of the climatic variables in model 2 and model 3 accounted for an additional 0.1 to 0.2% of the incidence of dark cutting carcasses. Higher maximum T A , RH and THI in the 3 to 28 days prior to consignment were all associated with an increased incidence of dark cutting (P < 0.05), but not in the 48 h preceding consignment (P > 0.05). Low minimum T A and low THI were also associated with an increase the incidence of dark cutting across all lag periods (P < 0.05). Increased variation in THI and T A in the 48 h prior to consignment increased dark cutting (P < 0.05) while increased standard deviation (SD) of temperature and THI range also increased dark cutting in the 14 and 28 day prior to feedlot exit (P < 0.05). Smaller minimum ranges in T A in the 28 days prior to consignment also reduced dark cutting (P < 0.05). Climatic conditions accounted for a further 0.1 to 0.2% of the incidence of dark cutting, whereas animal management factors, feedlot and abattoir were able to account for 21% of dark cutting. These data suggest that climatic conditions appear to have an inherent role in the incidence of dark cutting, albeit a small impact. Regardless, understanding the influence of climatic conditions on dark cutting allows for the implementation of management strategies within the supply chain to further reduce the impact of climatic conditions on grain-fed cattle., (© 2021. ISB.)

The aim of this study was to evaluate the effect of carcass traits, lairage time and weather conditions during lairage and abattoir factors that impact the incidence of dark cutting in 142,228 grain-fed carcasses, as defined by Meat Standards Australia (MSA) guidelines. This study was conducted over a 12-month period analysing data from cattle that were supplied from seven feedlots and processed at three abattoirs. Abattoir data indicated that the average incidence of dark cutting within the study was 2.8%. Increased wind speeds (WSs) and rain during lairage at the abattoir was associated with an increased risk of dark cutting, whereas variation in ambient temperature and/or relative humidity did not influence dark cutting. Heavier carcasses with whiter fat, larger hump heights, more rib fat, higher marble scores and lower ossification had lower incidences of dark cutting. The factors abattoir, time in lairage, time to grading and grader within Abattoir had significant effects on the incidence of dark cutting. The results from this study suggest that reducing the time in lairage and increasing the time between slaughter and grading are the two major ways to reduce dark cutting in MSA carcasses.

Globally, the poultry industry is gaining significant importance among the agricultural and its allied sectors. However, heat stress was found to negatively affect the poultry production particularly in the tropical regions. This review is therefore an attempt to generate information pertaining to the impacts of heat stress on poultry production and its amelioration. Heat stress reduces the growth, reproductive performance, and egg production in poultry birds. The reduction in productive potential of poultry birds on exposure to heat stress may be attributed to the deviation of energy resources from production to adaptation pathway. There are different approaches pertaining to relieving the adverse impacts of heat stress on poultry production. These approaches can be broadly categorized under genetic, management, and nutritional strategies. These approaches may reduce the negative effects of heat stress and enhance the productive performance of poultry birds. The management strategies include appropriate shelter design, providing shade, using sprinklers, implementing cooling devices, and using fans and ventilation systems. The recommended floor space for mature birds weighing 1.7 kg is 0.06 m 2 /bird while it is 0.13 m 2 /bird for the birds weighing 3.5 kg with 27.8 kg/m 2 bird density in either case. The nutritional interventions comprise ration balancing and providing essential micronutrients to improve the productive and reproductive performance in poultry birds. Fat, antioxidants, yeast, and electrolyte supplementations are some of the most commonly used nutritional strategies to ensure optimum production in the poultry industry. Furthermore, providing adequate water supply and disease surveillance measures may help to ensure optimum meat and egg production in the birds. The advanced biotechnological tools may aid to identify suitable genetic markers in poultry birds which might help in developing new strains of higher thermo-tolerance by designing suitable breeding program involving marker-assisted selection. These strategies may help to optimize and sustain poultry production in the changing climate scenario.

The study was aimed at assessing heat load-related risk of clinical mastitis (CM) in dairy cows. Records of CM for the years 2014 and 2015 were obtained from a large conventional dairy farm milking about 1,200 Holstein cows in central Italy. A case of CM was defined by the presence of clinical signs and veterinary confirmation. Quarter milk samples were collected and bacteriological investigated for each CM. Etiological agents were identified and classified as environmental or contagious pathogens. Hourly weather data from the nearest weather station were used to calculate heat load index (HLI). Upper and lower thresholds of HLI, at which the animal accumulates or dissipates heat, were settled and used to measure heat load balance through the accumulated heat load (AHL) model. Zero and positive values of AHL indicate periods of thermo-neutral and heat accumulation, respectively. Each case of CM was associated with HLI-AHL values recorded 5 d before the event. The risk of CM was evaluated using a case-crossover design. A conditional logistic regression model was used to calculate the odds ratio and 95% confidence intervals of CM recorded in thermo-neutral (AHL = 0) or heat load (AHL > 0) days, pooled or stratified for pathogen type (environmental or contagious). Classes of AHL as low (<6.5), medium (6.6-34.9), and high (>35) were included in the model. Other variables included in the model were milk yield as liters (<20, 20-30, and >30), days in milk (<60, 60-150, and >150), and parity (1, 2-3, and >3). A total of 1,086 CM cases were identified from 677 cows. Escherichia coli, Streptococcus spp., and Streptococcus uberis were the environmental pathogens isolated with the highest frequency; Staphylococcus aureus prevailed within contagious species. The analysis of pooled data indicated a significant effect of heat load on the occurrence of CM in the contagious pathogen stratum. Higher milk yield, middle and late stage of lactation, and older parity increased the risk of CM under heat load conditions. However, the association between pathogen type and these factors was not clear because the model provided significant odds ratios within all pathogen categories. The present study provided the first evidence of an association between HLI and CM in dairy cattle and suggested the ability of the AHL model to assess the risk of mastitis associated with heat load., (Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Previous studies have indicated that cattle with more excitable temperaments exhibit an increased stress response. The objective of this study was to investigate the relationship between temperament traits, handling, and stress-induced hyperthermia (SIH) in beef cattle. Rectal temperatures (T REC , °C) of 60 purebred Angus cattle (30 heifers, 30 steers; 235.2 ± 5.11 kg) were recorded at 20 s intervals from 30 min prior to handling until two hours post handling. All cattle were exposed to a standardized handling procedure consisting of (i) being restrained in a weighing box for 30 s; (ii) being held within the crush for 30 s; and then (iii) being restrained in a head bail for 60 s. Cattle temperaments were evaluated via three traits: (1) agitometer score (AG); (2) crush score (CS); and (3) flight speed (FS) during the handling procedure. Agitometer scores and FS measures were used to describe an AG category (AG CAT ) and an FS category (FS CAT ) that were used to classify animals into three temperament categories: 1, calm; 2, intermediate; and 3, temperamental. Pearson's correlation coefficients were used to evaluate the associations between (i) AG, CS, FS, and T REC 30 min prior to entry into the weighing box (T-30) and then at 1 min intervals between time of entry into the weighing box (T0) until 10 min post-weighing (T10); and (ii) the relationship between AG, CS, and FS. The relationship between T REC and temperament traits over the 2.5 h were modeled by using a first-order autoregressive repeated measures model. Flight speed had strong to moderate associations with T REC at T-30 (r ≥ 0.37; p ≤ 0.006) and between T0 and T10 (r ≥ 0.36; p ≤ 0.01). There were moderate associations amongst T REC between T0 and T10 and CS (r ≥ 0.31; p ≤ 0.01). A weak relationship existed with CS (r = 0.16; p = 0.16). There were no associations between AG and T REC at T-30 (r ≥ -0.15; p = 0.84) or between T0 and T10 (r ≤ 0.04; p ≥ 0.4). Rectal temperature, irrespective of sex and temperament traits, was influenced by time ( p < 0.0001), and maximum T REC (39.3 ± 0.04 °C) occurred between 4 and 5.7 min after entry into the weighing box. In addition, CS ( p = 0.007) influenced T REC in these cattle. There were also time × temperament trait × sex interactions with the CS ( p = 0.0003) and FS CAT ( p = 0.043) categories; however, time × temperament trait interactions were not statistically significant. Results from this study suggest that cattle with excitable temperaments, as evaluated by FS and CS, have a greater increase in T REC . In addition, these results suggest that a relationship exists between basal T REC and FS and CS. Together, these results highlight that temperament, as assessed by FS and CS, influences both basal T REC and the peak temperature recorded following handling but does not influence the magnitude of change in T REC post handling.

Animal biometeorology (insects excluded) has been part of the International Journal of Biometeorology since its inception in 1958. Over the first 60 years of the journal, 480 animal biometeorology papers were published. Thus, approximately 14% of published papers dealt with animals. Over the first 60 years, data from more than 50 animal species was presented, with the lead authors coming from 48 countries. The two most common species used in animal papers between 1957 and 2016 were cattle (109 papers: 22.7% of all animal papers) and rats (96 papers: 20.0% of all animal papers). Although cattle and rats dominated, the species in the most cited paper (240 citations) was chickens, followed by bird migration (155 citations), and general livestock (118 citations). Overall, five papers exceeded 100 citations, and a further two exceeded 200 citations. In the last decade, 126 animal papers were published (26% of all animal papers). Many of these papers had a focus on livestock production in developing countries especially Brazil.

Heat stress is well documented to have a negative influence on livestock productivity and these impacts may be exacerbated by climate change. Dairy cattle can be more vulnerable to the negative effects of heat stress as these adverse impacts may be more profound during pregnancy and lactation. New emerging diseases are usually linked to a positive relationship with climate change and the survival of microrganisms and/or their vectors. These diseases may exaggerate the immune suppression associated with the immune suppressive effect of heat stress that is mediated by the hypothalamic-pituitary-adrenal (HPA) and the sympathetic-adrenal-medullary (SAM) axes. It has been established that heat stress has a negative impact on the immune system via cell mediated and humoral immune responses. Heat stress activates the HPA axis and increases peripheral levels of glucocorticoids subsequently suppressing the synthesis and release of cytokines. Heat stress has been reported to induce increased blood cortisol concentrations which have been shown to inhibit the production of cytokines such as interleukin-4 (IL-4), IL-5, IL-6, IL-12, interferon γ (IFNγ), and tumor necrosis factor-α (TNF- α). The impact of heat stress on the immune responses of dairy cows could be mediated by developing appropriate amelioration strategies through nutritional interventions and cooling management. In addition, improving current animal selection methods and the development of climate resilient breeds may support the sustainability of livestock production systems into the future., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Livestock industries have an important role in ensuring global food security. This review discusses the importance of quantifying the heat stress response of ruminants, with an emphasis on identifying thermo-tolerant breeds. There are numerous heat stress prediction models that have attempted to quantify the response of ruminant livestock to hot climatic conditions. This review highlights the importance of investigating prediction models beyond the temperature-humidity index (THI). Furthermore, this review highlights the importance of incorporating other climatic variables when developing prediction indices to ensure the accurate prediction of heat stress in ruminants. Prediction models, particularly the heat load index (HLI) were developed to overcome the limitations of the THI by incorporating ambient temperature (AT), relative humidity (RH), solar radiation (SR) and wind speed (WS). Furthermore refinements to existing prediction models have been undertaken to account for the interactions between climatic variables and physiological traits of livestock. Specifically, studies have investigated the relationships between coat characteristics, respiration rate (RR), body temperature (BT), sweating rate, vasodilation, body weight (BW), body condition score (BCS), fatness and feed intake with climatic conditions. While advancements in prediction models have been occurring, there has also been substantial advancement in the methodologies used to quantify animal responses to heat stress. The most recent development in this field is the application of radio frequency identification (RFID) technology to record animal behaviour and various physiological responses. Rumen temperature measurements using rumen boluses and skin temperature recording using infrared thermography (IRT) are making inroads to redefine the quantification of the heat stress response of ruminants. Further, this review describes several advanced biotechnological tools that can be used to identify climate resilient breeds of ruminant livestock.

When exposed to hot conditions, heat dissipation via an increase in respiration rate (RR) is an important thermoregulatory mechanism for sheep. However, evaluating RR under field conditions is difficult. In cattle, a viable alternative has been to assess panting score (PS); therefore, the objective of this study was to evaluate the relationship between RR and PS to determine if a PS index can be used to evaluate heat load in sheep. One hundred and forty-four Merino wethers (44.02 ± 0.32 kg) were used within a climate-controlled study. The study was replicated twice over 29 days, where each replicate consisted of two treatments: (1) thermoneutral (TN) and (2) hot (HOT). Ambient temperature (T A ) and relative humidity (RH) were maintained between 18 and 20 °C and 60 and 70% respectively for the TN treatment. For the HOT treatment, heat load increased steadily over the 29 days. Minimum T A was 22.5 °C and maximum was 38.5 °C, while RH decreased (60 to 30%) as T A increased in the HOT treatment. A comprehensive PS classification was developed by enhancing the current sheep PS index and aligning the descriptors with the current PS index utilized in beef cattle studies. Respiration rate and PS were obtained for each animal at 3-h intervals between 0800 h and 1700 h daily. These data were used to determine the mean RR for each PS, across the study and within the TN and HOT treatments. The relationship between PS and RR was evaluated using a Pearson's correlation coefficient. Data were also analyzed using a general linear model to determine the impact of PS, posture and animal identification (animal ID) on RR within each PS. Unsurprisingly, RR increased as PS increased, and PS, 0 and RR, 2.5 were 30.7 ± 0.59 and 246.8 ± 12.20 bpm respectively. There was a strong relationship between RR and PS (r = 0.71; P < 0.0001). As RR increased, sheep were more likely to be observed standing (P < 0.001). Mean PS of sheep within the HOT treatment (1.49 ± 0.02) were greater (P = 0.0085) when compared to the TN (1.17 ± 0.02) sheep. Individual animal ID accounted for approximately 7-37% of the variation observed for RR across PS, indicating that animal ID and climatic conditions were influencing RR and PS. These results suggest that the comprehensive PS index described here can be used as a visual appraisal of the heat load status of sheep.

This study was conducted to determine the relationship between rectal temperature (T REC ) and rumen temperature (T RUM ) and to assess if T RUM could be used as a proxy measure of core body temperature (T CORE ) in feedlot cattle. Eighty Angus steers (388.8 ± 2.1 kg) were orally administered with rumen temperature boluses. Rumen temperatures were recorded at 10-min intervals over 128 days from all 80 steers. To define the suitability of T RUM as an estimation of T CORE , T REC were obtained from all steers at 7-day intervals (n = 16). Eight feedlot pens were used where there were 10 steers per pen (162 m 2 ). Shade was available in each pen (1.8 m 2 /animal; 90% solar block). Climatic data were recorded at 30-min intervals, including ambient temperature (T A ; °C); relative humidity (RH; %); wind speed (WS; m/s) and direction; solar radiation (SR; W/m 2 ); and black globe temperature (BGT; °C). Rainfall (mm) was recorded daily at 0900 h. From these data, temperature humidity index (THI), heat load index (HLI) and accumulated heat load (AHL) were calculated. Individual 10-min T RUM data were converted to an individual hourly average. Pooled mean hourly T RUM data from the 128-day data were used to establish the diurnal rhythm of T RUM where the mean minimum (39.19 ± 0.01 °C) and mean maximum (40.04 ± 0.01 °C) were observed at 0800 h and 2000 h respectively. A partial correlation coefficient indicated that there were moderate to strong relationships between T RUM and T REC using both real-time (r = 0.55; P < 0.001) and hourly mean (r = 0.51; P < 0.001) T RUM data. The mean difference between T REC and T RUM was small using both real-time (0.16 ± 0.02 °C) and hourly mean T RUM (0.13 ± 0.02 °C) data. Data from this study supports the hypothesis that T RUM can be used as an estimate of T CORE , suggesting that T RUM can be used to measure and quantify heat load in feedlot cattle.

Heat stress and cold stress have a negative influence on cattle welfare and productivity. There have been some studies investigating the influence of cold stress on cattle, however the emphasis within this review is the influence of heat stress on cattle. The impact of hot weather on cattle is of increasing importance due to the changing global environment. Heat stress is a worldwide phenomenon that is associated with reduced animal productivity and welfare, particularly during the summer months. Animal responses to their thermal environment are extremely varied, however, it is clear that the thermal environment influences the health, productivity, and welfare of cattle. Whilst knowledge continues to be developed, managing livestock to reduce the negative impact of hot climatic conditions remains somewhat challenging. This review provides an overview of the impact of heat stress on production and reproduction in bovines.

This study evaluated the relationship between rectal temperature (T REC , °C) and vaginal temperature (T VAG , °C) in grazing Bos taurus heifers, to develop an understanding of the reliability of these measures as estimates of core body temperature. Nineteen Angus heifers (BW = 232.2 ± 6.91 kg) were implanted with intra-rectal and intra-vaginal data loggers. Rectal temperature and T VAG were simultaneously recorded at 20 s intervals over 18.5 h. Heifers were housed as a singular cohort on grazing pastures for the duration of the study. A strong linear relationship (R² = 0.72, p < 0.0001) between the measurement sites was identified. The mean difference between T REC and T VAG was small, in which T VAG was on average 0.22 ± 0.01 °C lower than T REC . Individual twenty second T REC and T VAG data were used to determine the pooled mean T REC and T VAG and then to highlight the within measure variation over time. The coefficient of variation was, on average, lower ( p < 0.001) for T VAG (0.38%) than T REC (0.44%), indicating that T VAG exhibited less variation. Overall, the results from the current study suggest that a strong relationship exists between T REC and T VAG, and that T VAG may be a more reliable estimate of core body temperature than T REC in grazing Bos taurus heifers.

Thirty-six steers (12 of each Angus, Charolais, and Brahman) with an initial BW of 318.5 ± 6.7 kg were used in a 130-day study. Two treatments were imposed: un-shaded and shaded (3 m 2 /animal; 90% solar block shade cloth). On day 1, steers were administered with rumen temperature boluses. Rumen temperatures (T RUM ) were obtained at 10 min intervals over the duration of the study to determine differences in T RUM between Bos indicus and Bos taurus cattle. Six feedlot pens (162 m 2 ) were used with six steers (2/breed) per pen with three pens/treatment. Ambient dry bulb temperature (T A ; °C), relative humidity (RH; %), wind speed (WS; m/s) and direction, and solar radiation (SR; W/m 2 ) were recorded at 10 min intervals. Rainfall (mm) was collected daily at 0900 h. From these data, black globe temperature (BGT; °C), temperature humidity index (THI), heat load index (HLI), and accumulated heat load (AHL) were calculated. Individual T RUM were converted to an hourly average and then mean hourly T RUM were converted to a mean within hour T RUM across the 130 days. Rumen temperatures were analyzed using an autoregressive repeated measures model. The model analyzed the effect of breed (P < 0.0002), treatment (P = 0.3543), time of day (hour, h; P < 0.0001), breed × treatment (P < 0.3683), breed × h (P < 0.0001), treatment × h (P < 0.0001), breed × treatment × h (P = 0.0029), pen within treatment (P = 0.0195), and animal × breed × treatment within pen (P = 0.1041). Furthermore, there were breed × treatment × hour differences in T RUM (P = 0.0036), indicating that Bos indicus and Bos taurus regulate T RUM differently.

Thirty-six Black Angus steers were used in a replicated study; three replicates of 12 steers/replicate. Steers had an initial non-fasted BW of 392.3 ± 5.1, 427.5 ± 6.3, and 392.7 ± 3.7 kg for each replicate, respectively. Steers were housed outside in individual animal pens (10 m × 3.4 m). Each replicate was conducted over a 6-day period where infrared thermography (IRT) images were collected at 3-h intervals, commencing at 0600 h on day 1 and concluding at 0600 h on day 6. Rumen temperatures (T RUM ) were measured at 10-min intervals for the duration of each replicate using a radio-frequency identification (RFID) rumen bolus. These data were used to determine the relationship with surface temperature of the cattle, which was determined using IRT. Individual T RUM were converted to an hourly average. The relationship between T RUM and surface temperature was determined using Pearson's correlation coefficient. There were no linear trends between mean hourly T RUM and mean surface temperature. Pearson's correlation coefficient indicated that there were weak associations (r ≤ 0.1; P < 0.003) between T RUM and body surface temperature. These data suggest that there was little relationship between the surface temperature and T RUM .

The bull's scrotum and scrotal cord vasculature has traditionally been regarded as a thermoregulatory device for maintaining optimal testicular temperature for normal spermatogenesis. This assumption has mostly been derived from discrete measurements using thermocouples with limited data correlating continuous scrotal temperature (ST) to body temperature (BT). From mid-summer to early autumn, four Wagyu bulls (9-18 months) were surgically implanted with two data loggers (DL) logging at 30 min intervals: one on the right hand side flank and the other was attached to the visceral vaginal tunic of the mid-testis. Bulls were firstly housed in a paddock (PK) for 13 days and then moved to individual pens (IP), again for 13 days. Repeated measures analysis modelled the long-term and diurnal trends in BT and ST. While both day and time of day (TOD) were significant effects for ST at both housing locations (P < 0.005), only TOD showed significance for BT at both locations (P < 0.0001). Significant effects were seen between bulls with ST (F = 167.2, P < 0.001) but not BT (F = 0.03, P = 0.863), suggestive of variation in individual bull thermoregulatory capacity. Dual peaks were observed in ST at 0500 and 2130 h when housed in PK but not IP, suggesting ST may be influenced by external stimuli such as postural or behavioural changes. Reporting concurrent and continuous BT and ST will allow further investigation into factors influencing bovine ST and should be useful in selecting bulls with high degrees of thermoregulation capacity.

The title complexes, catena-poly[[[diaquadiethanolmanganese(II)]-mu-1,4-bis(diphenylphosphinoyl)butane-kappa(2)O:O'] dinitrate 1,4-bis(diphenylphosphinoyl)butane solvate], {[Mn(C(2)H(6)O)(2)(C(28)H(28)O(2)P(2))(H(2)O)(2)](NO(3))(2).C(28)H(28)O(2)P(2)}(n), (I), and catena-poly[[[diaquadiethanolcobalt(II)]-mu-1,4-bis(diphenylphosphinoyl)butane-kappa(2)O:O'] dinitrate 1,4-bis(diphenylphosphinoyl)butane solvate], {[Co(C(2)H(6)O)(2)(C(28)H(28)O(2)P(2))(H(2)O)(2)](NO(3))(2).C(28)H(28)O(2)P(2)}(n), (II), are isostructural and centrosymmetric, with the M(II) ions at centres of inversion. The coordination geometry is octahedral, with each metal ion coordinated by two trans ethanol molecules, two trans water molecules and two bridging 1,4-bis(diphenylphosphinoyl)butane ligands which link the coordination centres to form one-dimensional polymeric chains. Parallel chains are linked by hydrogen bonds to uncoordinated 1,4-bis(diphenylphosphinoyl)butane molecules, which are bisected by a centre of inversion. Further hydrogen bonds, weak C-H...O interactions to nitrate anions, and weak C-H...pi interactions serve to stabilize the structure. This study reports a development of the coordination chemistry of bis(diphenylphosphinoyl)alkanes, with the first reported structures of complexes of the first-row transition metals with 1,4-bis(diphenylphosphinoyl)butane.

The structure of the title complex, [Cu(NO(3))(2)(C(27)H(26)O(2)P(2))](n), consists of polymeric chains formed by propane-1,3-diylbis(diphenylphosphine oxide) ligands bridging between metal centres. The Cu atom lies on a twofold rotation axis and a further symmetry centre bisects the bridging bisphosphine dioxide ligand. The CuO(6) coordination geometry is a distorted octahedron, with the bidentate chelating nitrate groups adopting a cis configuration.

Prolonged retention of LDL in focal, atherosclerosis-prone areas of arteries is a primary event in atherogenesis. To determine whether unrecognized LDL-binding proteins participate in this process, we generated a cDNA expression library from deendothelialized rabbit aorta, a model for early atherosclerosis that shows striking focal LDL retention in healing lesions. Library screening identified a previously unknown, highly conserved, 56kDa LDL-binding protein that we call atherin. Confocal microscopy of human arteries shows that atherin is present only in atherosclerotic lesions, not in normal intima. Within lesions, atherin is found both in the extracellular compartment and within foam cells. Essentially all extracellular atherin, as well as atherin within foam cells, co-localizes with LDL across the entire spectrum of human disease, from early lesions to advanced plaques. Our results suggest that focal arterial LDL accumulation may be initiated and maintained by binding between LDL and atherin, and that atherin may play a central role in atherogenesis by immobilizing LDL in the arterial wall.

The reactions of lanthanide nitrates, Ln(NO(3))(3), with bis(diphenylphosphino)methane dioxide, Ph(2)P(O)CH(2)P(O)Ph(2) (L), lead to complexes with three distinct classes of structure. At low ratios of Ln:L (<1:1.5) in acetonitrile the ionic complexes [Ln(NO(3))(2)L(2)](+)[Ln(NO(3))(4)L](-) (Ln = Pr, Eu) have been isolated. When carried out with a 1:2 or higher ratio in ethanol the reaction yields Ln(NO(3))(3)L(2) (Ln = La,Ce) and [Ln(NO(3))(2)L(2)H(2)O](+)[NO(3)](-) (Ln = Nd, Gd, Ho). Geometrical isomerism is found for the cations [Ln(NO(3))(2)L(2)H(2)O](+) and is attributed to the extent of hydrogen bonding to the coordinated water. Ligand redistribution occurs on heating in the solid state giving yellow solids in all cases. Crystallization of these materials from ethanol or acetonitrile gives [Ln(NO(3))L(3)](2+).2[NO(3)](-), which have been structurally characterized for Ln = Gd and Yb. Electrospray mass spectra indicate that extensive ligand exchange reactions occur in solution.

In previous in vivo animal studies, we showed that low density lipoprotein (LDL) accumulated irreversibly at the edges of healing arterial lesions rather than being internalized and degraded. To see if similar LDL accumulation occurs in vitro, fibroblasts from normal and homozygous familial hypercholesterolemic (FH) subjects were incubated at 37 degrees C with 125I-LDL and 125I-methyl LDL; the latter is not recognized by any known LDL receptor. Normal fibroblast accumulation of LDL and methyl LDL (5 microg/ml) plateaued within 1 h at 200 and 100 ng/mg, respectively. With FH cells, both LDL and methyl LDL accumulation plateaued at 100 ng/mg. Lipoprotein accumulation by both cell types rose steeply at concentrations up to 15-25 microg/ml, and less so at higher concentrations. Except for degradation of LDL by normal cells, degradation was minimal, which indicated that much of the lipoprotein accumulation was unaccompanied by internalization. The accumulation of both lipoproteins by both cell types was greater at 37 degrees C than at 4 degrees C, and was inhibited between 43 and 75% by homologous unlabeled lipoprotein. To see if any accumulation was irreversible, cells were incubated with radiolabeled lipoproteins for 3 h (pulse), then with homologous unlabeled lipoproteins for up to 20 h (chase). About 50% of intact radiolabeled lipoprotein rapidly dissociated from cells into the medium in the first 4 h of the chase period. In contrast, between 4 and 20 h, most of the remaining intact LDL and methyl LDL appeared to be irreversibly bound, because it was released at a rate of only 0-1%/h. Thus, we conclude that, under the conditions studied, both reversible and irreversible non-internalized LDL binding play a major role in LDL accumulation by cultured cells.

In the past year, new data have appeared on the long-term benefits of low-density lipoprotein apheresis in severely hypercholesterolemic patients who are refractory to lipid-lowering drug therapy. Such data are critical for clinical decision-making, because they confirm the hypothesis that the dramatic reduction in low-density lipoprotein made possible by this technique produces clear-cut clinical benefits. Because of its efficacy and low incidence of side-effects, apheresis for severe drug-refractory hypercholesterolemia has superseded surgical approaches, such as liver transplantation or ileal bypass.

I-125 labeled SP4 is a synthetic oligopeptide derived from apolipoprotein B of low-density lipoprotein that has been shown to localized in atherosclerotic plaques in experimental animals. However, its biodistribution and mechanism of localization need to be further elucidated. Twenty-four cholesterol-fed (CF) and 20 normal (NL) New Zealand White rabbits were injected with I-125-SP4 and killed 15 to 30 min (6 NL; 6 CF) or 2 h (14 NL; 18 CF) later. We obtained aortic autoradiograms and activity concentrations (% injected dose/gm) in aortic segments and other tissues. The uptake of I-125-SP4 was higher in CF than in NL rabbits in all aortic segments (p < 0.05). I-125-SP4 was cleared rapidly in both CF and NL rabbits with 60 to 70% of the injected dose cleared from the blood by 1 h. No statistically significant differences in radiotracer biodistribution were observed between NL and CF rabbits although activity tended to be higher in the liver, gallbladder, and intestine in NL rabbits and in the kidney and spleen in CF rabbits. Silver grains were distributed mainly on foam cells of the fatty streaks in aortic microautoradiograms from two additional rabbits that had been injected with I-125-SP4. There were 23,518 plus minus 15,878 (SD) grains/mm(2) in fatty plaques but only 14,669 plus minus 11,035 grains/mm(2) in media muscle (p < 0.0001 [9 sections, 17 areas evaluated] in an atherosclerotic animal) in injected animals and 13,439 plus minus 5,565 grains/mm(2) in media muscle (two sections, four areas) in the normal control animals (NS versus media of atherosclerotic animal). I-125-SP4 specifically localizes in aortic atherosclerotic plaques in CF rabbits. There is no significant difference in tissue distribution between normal and CF rabbits except in the aorta. Preliminarily, it appears that the site of tracer uptake is on foam cells and this suggests the possibility of relative specificity for fatty plaque.

Familial hypercholesterolemia (FH) can cause early disability and death from premature atherosclerotic cardiovascular disease. Patients homozygous for the disease have very high plasma cholesterol, extensive xanthomatosis, and die from atherosclerosis in childhood or early adulthood. Past attempts to improve the prognosis included removal of cholesterol from the circulation by ileal bypass or biliary diversion. Neither treatment was successful. Direct removal by plasmapheresis of low-density lipoprotein (LDL), the primary carrier of cholesterol in plasma, was first performed on an FH homozygous patient in 1966. The treatment was well tolerated and led to rapid diminution of xanthomas. Other experimental treatments included selective LDL apheresis with monoclonal or polyclonal antibody affinity columns. A method for selective LDL apheresis was developed in 1983 by Armstrong, Seidel, and colleagues based on heparin precipitation of LDL at low pH. This method, called HELP, removes all apolipoprotein B-containing lipoproteins including LDL and lipoprotein (a), as well as some fibrinogen. LDL apheresis by HELP is well tolerated; the incidence of side effects is low, and the treatment has been associated with regression of cardiovascular disease. LDL apheresis, rather than liver transplantation, is the treatment of choice for patients with severe, life-threatening hypercholesterolemia which does not respond to diet and drug therapy.

We have previously shown that after administration of (123)I-SP-4 (a synthetic ApoB peptide fragment) to Watanabe heritable hyperlipidemic (WHHL) rabbits that foci of tracer uptake can be identified by external gamma camera imaging which correspond to regions of the aortas found to contain abundant atherosclerotic lesions at postmortem evaluation. Because (99m)Tc is preferred over (123)I for scintigraphic imaging, we prepared a (99m)Tc-labeled form of the SP-4 peptide, designated (99m)Tc-P199. To assess the feasibility of detecting atherosclerotic lesions using (99m)Tc-P199 and to compare the relative uptake of the (99m)Tc-labeled and radioiodinated peptides by such lesions, an admixture of (99m)Tc-199 and (125)I-SP-4 was administered to 11 WHHL and 2 normal rabbits. These animals were imaged for up to 3 h and were sacrificed 3--4 h after injection. The extent of aortic lesion involvement and radiotracer uptake were quantitatively compared by planimetric analysis of photographs of the endothelial surface, (99m)Tc-P199 ex vivo images and (125)I-SP-4 autoradiograms of the excised aortas. Pairwise correlation coefficients for planimetric analysis were as follows: photographs versus ex vivo images, r = 0.83, p = 0.003; photographs versus autoradiograms, r = 0.87, p = 0.001; ex vivo images versus autoradiograms, r = 0.83, p = 0.003. (99m)Tc-199 in vivo gamma camera images revealed relatively weak focal aortic uptake in 8 of 11 WHHL rabbits manifesting aortic lesions, and focal carotid artery uptake in 4 of 6 WHHL rabbits manifesting carotid lesions. Neither aortic nor carotid foci were visualized in the normal rabbits. We conclude that (99m)Tc-199 localizes specifically in atherosclerotic lesions and may be useful for external imaging of atherosclerosis.

The oligopeptide fragment of apolipoprotein B, SP-4, has demonstrated pronounced uptake in the healing edges of balloon-injured rabbit aortic endothelium. To assess 123I-labeled SP-4 for identification of atherosclerotic plaques by gamma camera imaging, 14 Watanabe heritable hyperlipidemic (WHHL) and 5 normal rabbits were imaged 5 minutes and 12 and 24 hours after intravenous injection of 123I-SP-4. In addition, two WHHL and two normal rabbits were injected with 125I-SP-4 for autoradiography. Twelve of the 14 WHHL, but none of the normal, rabbits had visually apparent focal radioiodine accumulation in the region of the aorta. Focus-to-lung and focus-to-heart count ratios were 2.4 +/- 1.3 and 1.0 +/- 0.4, respectively. Five of the visually positive WHHL rabbits were reimaged 4 and 8 weeks later with 123I-NaI and 123I-SP-2 (an apo E peptide), respectively, as negative controls. Perceptible, but faint, aortic localization of 123I-NaI and of 123I-SP-2 was seen in only one animal each. The distributions of atherosclerotic lesions on photographs of the opened WHHL aortas and of film blackening on 125I-SP-4 autoradiograms were identical. In contrast, the two normal rabbit aortas did not exhibit plaques on photographs or film blackening on autoradiograms. Thus, in an animal model closely simulating human atherosclerotic disease, SP-4 localizes specifically in aortic atherosclerotic lesions.

Chemically or enzymatically modified low-density lipoproteins (LDL), with and without changes in surface charge, were studied in vivo in the healing, balloon catheter-deendothelialized rabbit aorta to determine the effect of LDL modification on its accumulation in arterial lesions. In this model, in which healing (reendothelialization) proceeds radially outward from individual aortic branch arteries, it was previously shown by autoradiography that two kinetically distinct compartments accumulated 125I-labeled LDL. In aortic regions which were still deendothelialized, accumulation was diffuse and labile. In contrast, at the edges of the islands of regenerating endothelium, LDL accumulation was intensely focal, as it is in human atherosclerotic lesions, and persisted for at least 40 h after injection in spite of falling levels of radiolabeled LDL in plasma [Chang, M. Y., et al. (1992) Arterioscler. Thromb. 12, 1088-1098]. In the present study, modified LDLs with gradations in charge change were prepared to clarify the role of changes in surface charge on focal aortic LDL accumulation. Oxidized LDL (weakly anionized), desialated LDL (weakly cationized), and reductively methylated LDL (no change in net charge) all accumulated focally. Focal accumulation of native LDL also occurred in ballooned rabbits fed probucol to inhibit LDL oxidation. Strongly anionized succinylated and diazobenzenearsonylated LDL and strongly cationized dimethylpropanediamine LDL did not accumulate focally. The results support the concept that focal sequestration of LDL in arterial lesions is mediated by specific, oxidation-independent patterns of charge and polarity on LDL which are disrupted by major changes in LDL surface charge.

The conformational and surface-binding properties of a synthetic peptide corresponding to Tyr-apolipoprotein B-100(1000-1016) amide, SP-4, which was previously shown to mimic the focal accumulation pattern of LDL on the healing de-endothelialized rabbit aorta [Shih et al. (1990) Proc. Natl. Acad. Sci. USA 87, 1436-1440], have been investigated. SP-4 behaves as an amphiphilic alpha-helical peptide at the air-water interface and bound to siliconized quartz slides. However, its N alpha-acetylated analogue formed beta-sheet structures at the air-water interface. Nonhomologous peptide models of SP-4 also exhibited mixed alpha-helical and beta-sheet surface-binding behavior. Peptides corresponding to the cationic apolipoprotein (apo) B/E receptor binding regions of apoE (SP-2) and apoB (SP-11) were also studied. SP-2 behaved as an amphiphilic alpha helix, but, surprisingly, SP-11 formed surface-induced beta-sheets. These results demonstrate that all of the peptides studied have surface-binding properties, and suggest further that either alpha-helical or beta-sheet peptide structures may determine the binding of LDL to the arterial wall or the apoB/E receptor.

We previously showed by qualitative en face autoradiography that after 24 hours of circulation, 125I-labeled low density lipoprotein (LDL) injected in tracer amounts accumulated focally at the edges of regenerating endothelial islands in the balloon catheter-deendothelialized aorta of the normocholesterolemic rabbit. In the present study with the same animal model, we have used quantitative autoradiography to examine 125I-LDL accumulation in the healing aorta as a function of LDL circulation time from 2.5 to 40 hours. The results demonstrated that 125I-LDL accumulation in the healing aorta occurred in two kinetically and biochemically distinct compartments, one of which was in equilibrium with plasma and one of which sequestered LDL. LDL accumulation in the still-deendothelialized aorta (DEA) was diffuse and only moderately intense on autoradiography. It peaked 4 hours after injection; over the following 36 hours the disappearance of 125I-LDL from DEA paralleled the disappearance of 125I-LDL from plasma. In contrast, accumulation of 125I-LDL at the edges of regenerating endothelial islands was focal and intense. LDL accumulation in this compartment also peaked 4 hours after injection but remained elevated even at 40 hours, despite falling plasma levels of LDL. At 24 hours, edge LDL accumulation per unit area was more than five times greater than DEA accumulation. The data indicate that LDL accumulation in specific compartments of the functionally modified arterial wall occurs independently of either acute or chronic hypercholesterolemia. The contrast between labile LDL accumulation in DEA and persistent accumulation at the edges of healing aortic islands indicates that LDL accumulation in the two areas must involve different processes within the arterial wall itself.

The functions of surface-accessible domains of apolipoprotein (apo) B, the protein moiety of low density lipoprotein (LDL), are unknown, aside from the LDL receptor-binding domain, which lies toward the carboxyl-terminal end of apoB. Since LDL accumulation in arterial lesions does not depend on recognition of LDLs by a cell-surface receptor, we synthesized an oligopeptide with the sequence of the trypsin-accessible domain of apoB that lies closest to the amino-terminal end of the protein and compared its biological activity to that of another synthetic oligopeptide with the sequence of the heparin- and apoB/apoE receptor-binding domains of apoE. (Tyrosine was added at the amino-terminal end of each peptide to facilitate radiolabeling.) The 18-amino acid apoB-based peptide included residues 1000-1016 of apoB, for which no function has been previously described. In radioautographs, the 125I-labeled peptide accumulated focally at the healing edges of regenerating endothelial islands in the balloon-catheter deendothelialized rabbit aorta. In contrast, the 21-residue apoE-based peptide, which included residues 129-148 of apoE, accumulated diffusely and uniformly throughout the deendothelialized areas of the aorta. The data show that focal binding of the apoB-based peptide can delineate arterial lesions and suggest that this arterial wall-binding domain of apoB mediates accumulation of LDLs in arterial lesions.

A previous study of low density lipoprotein metabolism by cultured cells focused on the metabolism of normal lipoproteins in vitro by fibroblasts isolated from diabetic patients. No abnormalities were found. We have followed the opposite approach. Using normal human fibroblasts as test cells we compared the metabolism in vitro of low density lipoproteins isolated from diabetic patients before and after metabolic control. We found a significant decrease (p less than 0.02) in internalization and degradation of low density lipoproteins isolated from diabetic patients before metabolic control when compared with those isolated from normal control subjects or from the same patients after metabolic control. The observed changes were mainly apparent in intracellular degradation. To evaluate whether the observed differences in low density lipoprotein behaviour were correlated with lipid or apolipoprotein composition, we measured cholesterol, triglyceride, apolipoprotein B and total protein levels in the low density lipoproteins tested. A significant decrease (p less than 0.05) of the triglyceride/protein ratio was found in post-control low density lipoproteins suggesting that a high triglyceride content may interfere with low density lipoprotein metabolism. The present study represents the first observation that metabolic control in diabetes mellitus can alter low density lipoprotein-cell interaction and suggests a possible mechanism for the enhanced incidence of atherosclerosis in diabetic patients.

Three major characteristics of cell surface low density lipoprotein (LDL) receptor activity in fibroblasts or lymphocytes are high-affinity LDL binding or degradation, specificity for LDL, and "inducibility"--that is, the ability to increase when cells are cultured in the absence of lipoproteins. Cells from patients with receptor-negative homozygous familial hypercholesterolemia (FH) have been reported to express none of these characteristics, and the patients are thought to have a genetic absence of LDL receptors. We found that, although induced receptor-negative lymphocytes degraded less LDL than did normal lymphocytes, the curves for LDL degradation versus LDL concentration were biphasic, with greater concentration-dependence at LDL concentrations less than 60 micrograms/ml, indicating high-affinity LDL degradation. The percentage of specific LDL degradation by induced receptor-negative lymphocytes was two-thirds of normal with LDL at 10 micrograms/ml and increased to normal at 50 micrograms/ml, an LDL concentration still within the range of high-affinity degradation. Receptor-negative lymphocytes could be induced by incubation in the absence of lipoproteins to degrade twice as much LDL as they did when freshly isolated. Freshly isolated cells from abetalipoproteinemic patients and one receptor-negative patient degraded as much LDL as did fresh normal cells. The findings indicate that receptor-negative lymphocytes have a mechanism for facilitated uptake of LDL that resembles that of normal lymphocytes, although it is not as efficient.

Primates are among the most threatened taxa, with more than half of all species in jeopardy. In this paper we develop population models to use the kind of data on wild primates that primatologists actually collect. Our survey of recentprimate journals suggests that the average field study uses 1.5 years of data from 50 animals The models are based on the simple Leslie-Lefkovitch matrix. They suggest a simple method that allows assessment from a few years'data, of whether a population is collapsing and requires intervention To a good approximation, populations will collapse when adult survival, per inter-birth interval, is less than 70 percent. Modifications of the basic model incorporate more realistic assumptions about social organization and densitydependent resource limitation. These allow us to identify population densities at which potential Allee effects operate, and permit more precise estimates of the minimum population sizes and compositions required for successful reintroductions to the wild The most important result is that populations of primates that live in small family groups may be more prone to "demographic" extinction than are more promiscuous species that live in more extended groups.