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The objective of this study was to evaluate the effects of two rumen-native microbial feed supplements (MFS) on milk production, milk composition, and feed efficiency. A total of 90 multiparous cows between 40 and 60 d in milk were enrolled in a randomized block design study. Within each block (baseline milk yield), cows were randomly assigned to: control (no microbial feed supplementation), MFS1 (0.33 g/kg total mixed ration [TMR] of an MFS containing a minimum of Clostridium beijerinckii at 2 × 106 CFU/g and Pichia kudriavzevii at 2 × 107 CFU/g), or MFS2 (0.33 g/kg TMR of a MFS containing a minimum of C. beijerinckii at 2 × 106 CFU/g, P. kudriavzevii at 2 × 107 CFU/g, Ruminococcus bovis at 2 × 107 CFU/g, and Butyrivibrio fibrisolvens at 2 × 107 CFU/g). Cows were housed in a single group and fed the study diets ad libitum for 270 d. Individual milk yield was recorded using electronic milk meters, and milk fat and protein were measured using optical in-line analyzers at each of two daily milkings. Treatment and treatment by time effects were assessed through multiple linear regression analyses. Treatment effects were observed for milk and energy-corrected milk (ECM) yields, milk fat and protein yields and concentrations, dry matter intake (DMI), and feed efficiency; those effects were conditional to time for milk yield, DMI, and feed efficiency. Overall, milk, ECM, fat, and protein yields were higher for MFS2 compared with control cows (+3.0, 3.7, 0.12, and 0.12 kg/d, respectively). Compared with MFS1, milk yield was higher and protein yield tended to be higher for MFS2 cows (+2.9 and 0.09 kg/d, respectively). In contrast, MFS1 cows produced 0.17 and 0.08 units of percentage per day more fat and protein than MFS2 cows, and 0.07 units of percentage per day more protein than control cows. Dry matter intake and feed efficiency were higher for MFS2 cows compared with MFS1 cows (+1.3 kg/d and 0.06, respectively), and feed efficiency was higher for MFS2 cows compared with control cows (+0.04). Where observed, treatment by time effects suggest that the effects of MFS2 were more evident as time progressed after supplementation was initiated. No effects of microbial supplementation were observed on body weight, body condition score, somatic cell count, or clinical mastitis case incidence. In conclusion, the supplementation of MFS2 effectively improved economically important outcomes such as milk yield, solids, and feed efficiency.This study evaluates the effects of two rumen-native microbial feed supplements (MFS) on milk yield, composition, and feed efficiency in lactating dairy cows. Ninety multiparous Holstein cows between 40 and 60 d in milk were assigned to control (no microbial feed supplementation), MFS1 (Clostridium beijerinckii and Pichia kudriavzevii), or MFS2 (C. beijerinckii, P. kudriavzevii, Ruminococcus bovis, and Butyrivibrio fibrisolvens) total mixed ration supplementation. Overall, MFS2 cows had higher milk and milk component yields than control and MFS1, while MFS1 cows had higher milk component concentrations than control and MFS2. Feed efficiency was higher for MFS2 compared with control and MFS1 cows. Microbial feed supplementation improved economically important outcomes such as milk yield, solids, and feed efficiency.

BackgroundDuring the first year of the COVID-19 pandemic, the most effective way to reduce transmission and to protect oneself was to reduce contact with others. However, it is unclear how behavior changed, despite numerous surveys about peoples’ attitudes and actions during the pandemic and public health efforts to influence behavior.MethodsWe used two sources of data to quantify changes in behavior at the county level during the first year of the pandemic in the United States: aggregated mobile device (smartphone) location data to approximate the fraction of people staying at home each day and digital invitation data to capture the number and size of social gatherings.ResultsBetween mid-March to early April 2020, the number of events fell and the fraction of devices staying at home peaked, independently of when states issued emergency orders or stay-at-home recommendations. Activity began to recover in May or June, with later rebounds in counties that suffered an early spring wave of reported COVID-19 cases. Counties with high incidence in the summer had more events, higher mobility, and less stringent state-level COVID-related restrictions the month before than counties with low incidence. Counties with high incidence in early fall stayed at home less and had less stringent state-level COVID-related restrictions in October, when cases began to rise in some parts of the US. During the early months of the pandemic, the number of events was inversely correlated with the fraction of devices staying at home, but after the fall of 2020 mobility appeared to stay constant as the number of events fell. Greater changes in behavior were observed in counties where a larger fraction voted for Biden in the 2020 US Presidential election. The number of people invited per event dropped gradually throughout the first year of the pandemic.ConclusionsThe mobility and events datasets uncovered different kinds of behavioral responses to the pandemic. Our results indicate that people did in fact change their behavior in ways that likely reduced COVID exposure and transmission, though the degree of change appeared to be affected by political views. Though the mobility data captured the initial massive behavior changes in the first months of the pandemic, the digital invitation data, presented here for the first time, continued to show large changes in behavior later in the first year of the pandemic.

The chromatographic performance (speed, efficiency, and gradient peak capacity for the same analysis time) of conical columns are investigated from fundamental and experimental viewpoints. A stainless steel, conically shaped column (2.1 mm i.d/4.2 mm i.d. × 15 cm long, 0.4° opening angle) was prepared in-house and packed with 5 μm XBridge-C18 fully porous particles. Its performance was compared to that of a conventional 3.0 mm × 15 cm cylindrical column packed with the same batch of particles. Both Giddings' theory of non-uniform columns and experiments agree and show that, irrespective of flow direction, the conical column is 15% less efficient than the conventional column. Remarkably, Blumberg's theory of band broadening in gradient elution mode predicts that conical columns may outperform conventional cylindrical columns if the ratio of their outlet i.d. to their inlet i.d. is 0.95 and 0.80 for small molecule and peptide mixtures, respectively. The maximum relative gain is marginal as it does not exceed a few percents. The theory reveals that the flow direction should be from the wide to the narrow end of the conical column in order to deliver the highest peak capacity. In agreement with the theory, the observed losses in absolute peak capacity for the same analysis time are 14.5% (narrow to wide end) and only 11.0% (wide to the narrow end) for small molecules (n-alkanophenones). They are 14.2% (narrow to wide end) and only 8.5% (wide to the narrow end) for peptide samples (bombesin). Additionally, conical columns reduce peak tailing with respect to standard columns. They are suitable column technology for ultra-fast gradient separations as they also minimize sample dispersion through the narrow i.d. outlet frit.

Background The aim of the paper is related to our experience defining the diagnostic accuracy of breast elastosonog-raphy.The aim of our study is therefore to define the diagnostic accuracy of breast elastosonography in the differential diagnosis of nodular breast neoformations to improve the characterization of the solid lesion and reduce the number of needle aspiration unnecessary for benign formations.A total of 88 patients were enrolled, who came to the Department with an ultrasound diagnosis of a breast lesion. Each lesion was subjected to mammography and B-mode ultrasonogra-phy with an evaluation of size, echogenicity, and vascularization pres-ence or absence. The use of the ultrasound machine and the respective probe has made it possible to make the measurements. All nodules were subjected to ultrasound-guided FNAC. These data were compared with the results of elastosonographic examination.FNAC results were as follows: CIN 1 in 18 nodules, CIN 2 in 22 nodules, CIN 3 in 36 nodules, CIN 4 in 6 nodules, and CIN 5 in 6 nodules. The sensitivity and specificity of elastosonography found in our case series reported values in line with data reported in the literature, confirming the method's high reliability.The elastosonography could become a complemen-tary technique to mammography and ultrasonography in the future, reducing the costs and risks of additional examinations. Therefore, we believe it is essential to contribute with this additional finding to increasingly accredit this pathway and reduce the discomfort to patients of more invasive methods.

The COVID-19 pandemic has created an urgent need for models that can project epidemic trends, explore intervention scenarios, and estimate resource needs. Here we describe the methodology of Covasim (COVID-19 Agent-based Simulator), an open-source model developed to help address these questions. Covasim includes country-specific demographic information on age structure and population size; realistic transmission networks in different social layers, including households, schools, workplaces, long-term care facilities, and communities; age-specific disease outcomes; and intrahost viral dynamics, including viral-load-based transmissibility. Covasim also supports an extensive set of interventions, including non-pharmaceutical interventions, such as physical distancing and protective equipment; pharmaceutical interventions, including vaccination; and testing interventions, such as symptomatic and asymptomatic testing, isolation, contact tracing, and quarantine. These interventions can incorporate the effects of delays, loss-to-follow-up, micro-targeting, and other factors. Implemented in pure Python, Covasim has been designed with equal emphasis on performance, ease of use, and flexibility: realistic and highly customized scenarios can be run on a standard laptop in under a minute. In collaboration with local health agencies and policymakers, Covasim has already been applied to examine epidemic dynamics and inform policy decisions in more than a dozen countries in Africa, Asia-Pacific, Europe, and North America., Author summary Mathematical models have played an important role in helping countries around the world decide how to best tackle the COVID-19 pandemic. In this paper, we describe a COVID-19 model, called Covasim (COVID-19 Agent-based Simulator), that we developed to help answer these questions. Covasim can be tailored to the local context by using detailed data on the population (such as the population age distribution and number of contacts between people) and the epidemic (such as diagnosed cases and reported deaths). While Covasim can be used to explore theoretical research questions or to make projections, its main purpose is to evaluate the effect of different interventions on the epidemic. These interventions include physical interventions (mobility restrictions and masks), diagnostic interventions (testing, contact tracing, and quarantine), and pharmaceutical interventions (vaccination). Covasim is open-source, written in Python, and comes with extensive documentation, tutorials, and a webapp to ensure it can be used as easily and broadly as possible. In partnership with local stakeholders, Covasim has been used to answer policy and research questions in more than a dozen countries, including India, the United States, Vietnam, and Australia.

Consistent differences in behavior between individuals, otherwise known as animal personalities, have become a staple in behavioral ecology due to their ability to explain a wide range of phenomena. Social organisms are especially serviceable to animal personality techniques because they can be used to explore behavioral variation at both the individual and group level. Despite the success of personality research in social organisms generally, and social Hymenoptera in particular, social wasps (Vespidae) have received little to no attention in the personality literature. In the present study, we test Polistes metricus (Vespidae; Polistinae) paper wasp queens for the presence of repeatable variation in, and correlations (“behavioral syndromes”) between, several commonly used personality metrics: boldness, aggressiveness, exploration, and activity. Our results indicate that P. metricus queens exhibit personalities for all measured traits and correlations between different behavioral measures. Given that paper wasps have served as a model organism for a wide range of phenomena such as kin selection, dominance hierarchies, mate choice, facial recognition, social parasitism, and chemical recognition, we hope that our results will motivate researchers to explore whether, or to what degree, queen personality is important in their research programs.

The founding individuals of a new group or lineage are uniquely poised to have long-lasting effects on their descendants. Here we explore how the behavioural traits of new foundresses influence their task allocation strategies and the downstream collective behaviour of their colonies. We collected individual paper wasp (Polistes metricus) queens from the wild and measured their boldness, aggressiveness, exploration, activity and time budgets in the laboratory. We then provided queens with food and nest materials and waited for their workers to eclose. We subsequently tested for links between queen behavioural traits (e.g. boldness, aggressiveness) and the collective aggressiveness of their colonies, as estimated by the number of workers that responded to and stung a model predator. We found that bolder queens (i.e. queens that were less likely to leave their nests after repeated exposure to an agonistic stimulus) spent more time nest guarding, reared more workers and produced groups that were less responsive to a model predator. Thus, there appears to be parent–offspring, or queen–worker, resemblance in the degree to which individuals remain on their nests in different social contexts (solitary queen versus queen + her worker group). To our knowledge this represents the first study to explicitly test for links between individual variation in foundress behaviour, worker production and intercolony collective behaviour; the results highlight the possibility that cross-contextual and transgenerational behavioural links could be a reasonably common and potentially important phenomenon in complex societies.

Individual-based models provide modularity and structural flexibility necessary for modeling of infectious diseases at the within-host and population levels, but are challenging to implement. Levels of complexity can exceed the capacity and timescales for students and trainees in most academic institutions. Here we describe the process and advantages of a multi-disease framework approach developed with formal software support. The epidemiological modeling software, EMOD, has undergone a decade of software development. It is structured so that a majority of code is shared across disease modeling including malaria, HIV, tuberculosis, dengue, polio and typhoid. In additional to implementation efficiency, the sharing increases code usage and testing. The freely available codebase also includes hundreds of regression tests, scientific feature tests and component tests to help verify functionality and avoid inadvertent changes to functionality during future development. Here we describe the levels of detail, flexible configurability and modularity enabled by EMOD and the role of software development principles and processes in its development., To address multi-scale questions in infectious disease transmission, a multi-disease modeling platform EMOD has been developed with modularity, code sharing across diseases, and formal software development and testing processes.

Sexually selected signals are theoretically expected to exhibit heightened condition dependence compared to non-signaling traits. This link to condition enables sexual signals to provide information regarding individual quality and also provides a mechanism that allows animals to develop signals that accurately reflect their abilities. Most previous work on sexual signal condition dependence has focused on signals that have clear developmental costs, while less is known about the development of other types of quality signals. Male Polistes dominulus paper wasps have yellow-on-black abdominal spots that are important signals during female choice and male–male competition. These signals lack obvious production costs, as males are covered in yellow and black patterns composed of the same pigments. Here, we assess signal condition dependence by testing whether larval diet has a stronger influence on the development of male spots than on the development of control traits composed of the same pigments. Males reared on ad libitum diets developed elliptical spots similar to those seen on dominant, attractive males, while males reared on restricted diets developed irregularly shaped spots similar to those seen on subordinate, unattractive males. Remarkably, the development of a control trait composed of the same yellow and black pigments was not influenced by larval diet. Therefore, sexually selected signals can be developmentally decoupled from traits comprised of the same pigments. Condition dependence of sexually selected signals is likely to be a widespread solution to the challenge of developing sexually selected signals that accurately convey information about individual quality.

Although sexually selected ornaments are common across diverse taxa, little is known about mate choice and sexually selected ornamentation in social insects. Polistes dominulus paper wasps are a good system to study sexual selection, as males have a lek-based mating system as well as sexually dimorphic abdominal spots. Here, we demonstrate that the abdominal spots of male P. dominulus paper wasps function as signals in both inter- and intrasexual selection. Males with smaller, elliptically shaped spots were more dominant over male rivals and were more preferred by females than males with larger, irregularly shaped spots. Furthermore, experimental manipulation of male spots demonstrates that spot morphology acts as a signal. Males with experimentally reduced abdominal spots won a greater proportion of fights and were preferred by females as mates over control males. These results demonstrate that male ornaments are an important mediator of mating dynamics in P. dominulus paper wasps. They also highlight the importance of additional research examining sexually selected ornamentation in social insects.

Timing of diapause termination has an important influence on individual reproductive success, but relatively little research has explored how individuals differ in their response to diapause termination cues. We tested individual variation in the timing of post-diapause activity in Polistes dominulus paper wasps. Wasps were overwintered in a temperature-controlled chamber. In the spring, ambient temperature was gradually increased and the time each foundress became active was recorded. Timing of post-diapause activity was most strongly associated with the facial patterns that function as a conventional signal of quality. Foundresses with facial patterns indicating high quality became active at lower temperatures than individuals with facial patterns indicating low quality. Early diapause termination is associated with dominance, so the relationship between diapause termination and facial patterns provides a mechanism linking facial patterns with dominance. Body weight and mating status did not influence timing of post-diapause activity. Juvenile hormone (JH) titer at the time of diapause termination was also measured in a subset of foundresses. There was no JH titer threshold for diapause termination. Instead, our results suggest that individuals may have different threshold responses to JH, as individuals that became active at a lower temperature had lower JH titers than individuals that became active at a higher temperature. Overall, there is substantial individual variation in response to diapause termination cues and the variation is likely to have important impacts on the fitness of nest-founding females.

During mate selection, females of most species encounter males sequentially and may use a variety of decision rules whereby the attractiveness of a current potential mate is affected by sampling of previous individuals. The perceived distribution of male quality might therefore affect female mate choice. Mate choice among closely related taxa may additionally be affected by a perceived rarity of conspecifics. Here we tested whether female mate choice in the field crickets Gryllus rubens and G. texensis is affected by prior experience with either conspecific or heterospecific males. Specifically, we tested whether female acceptance of conspecific or heterospecific males is influenced by prior exposure to a conspecific or heterospecific male. Our results indicate that there is a clear previous-male effect, but that it differs across species. When ‘high-quality’ (i.e. conspecific) males are common, females are predicted to prefer them. Gryllus texensis females matched this prediction by showing clear preferences for conspecific males after prior experience with them, but G. rubens females showed the opposite effect: they preferred heterospecific males after prior experience with conspecific males. When prior experience is manipulated such that ‘low-quality’ (i.e. heterospecific) males are encountered first, female choosiness should be relaxed. Females of both species fit this prediction and showed no preference for conspecific or heterospecific males after prior experience with a heterospecific male.

Although there is increasing interest in the evolution of endocrine systems, relatively little is known about the factors associated with natural endocrine variation in invertebrates. Here, we assess juvenile hormone (JH) titers among nest-founding queens of the wasp Polistes dominulus over 2 years. We allowed unfamiliar wasps to battle for dominance and examined the relationships between dominance rank, JH, ovarian development, and facial patterns. The relationship between JH-titer and dominance varied across years; there was a stronger relationship between JH-titer and dominance in 2006 than in 2008. Across years, wasps that won dominance contests had facial patterns with more broken black spots than wasps that lost dominance contests. There was no relationship between dominance rank and ovarian development. The individual characteristics associated with JH-titer were also tested; JH-titers were correlated with facial pattern brokenness and ovarian development. This study adds to previous work indicating that P. dominulus facial patterns function as a signal of fighting ability. Furthermore, the correlation between JH-titers and facial patterns parallels previous work on testosterone and vertebrate signals and suggests that links between signals of fighting ability and hormones that mediate fighting ability may be common across taxa. Overall, individual JH-titers vary, though they are typically associated with factors related to individual reproductive success, including dominance, fertility, and facial pattern brokenness. Future studies in additional contexts and taxa will be important to test how and why JH-titers vary.

Cuticular hydrocarbons (CHCs) are information-rich signals in social insects that coordinate behaviors within nests. However, in some taxa, the precise information conveyed by CHCs is poorly understood. In particular, there is a debate over whether CHCs convey information about their bearer's dominance or fertility. Distinguishing between dominance and fertility signaling is difficult because fertility and rank are frequently correlated within social insect colonies. This study disentangles those relationships by examining CHCs of Polistes dominulus paper wasps during the early nest-founding stage before dominance and fertility become correlated. First, we confirm that dominance and fertility are not associated in early spring foundresses. Then we show that CHCs are more strongly associated with fertility than dominance. There was no relationship between cuticular hydrocarbon profiles and a wasp’s ability to dominate rivals through aggression, suggesting that CHCs are unlikely to provide information about dominance. However, there was a significant correlation between ovarian development and the CHC profile, suggesting that CHCs could convey valuable information about their bearer's fertility. Furthermore, our data provide a potential mechanism for chemical signaling of fecundity, as there is a relationship between endogenous juvenile hormone titer (a gonadotropin), degree of ovarian development, and the CHC profile. Hormonal regulation of CHC profile expression offers a physiological mechanism to coordinate behavior, physical state, and signal expression.

Both radiotrace labeled and high specific activity 125I-labeled derivatives of secretin were prepared by direction iodination of the histidyl residue with chloramine T [( 125I]secretin) and by conjugation of a preiodinated Bolton-Hunter group (iodo-3-(4-hydroxyphenyl)propionate) to the free alpha-amino group at the N-terminus [( 125I]BH-secretin). Following purification, the biological, immunological and receptor binding properties of both secretin derivatives were compared. [125I]secretin and [125I]BH-secretin were equally effective in a sensitive radioimmunoassay that detected secretin and secretin (5-27) but not CCK-8, VIP and glucagon. Although both derivatives retained 60% of the biological potency of secretin as measured by cAMP accumulation in pancreatic acinar cells, only the directly iodinated peptide [( 125I]secretin) could be used to characterize specific binding sites on rat pancreatic membranes. The N-terminal blocked derivative [( 125I]BH-secretin) in contrast dissociated rapidly from pancreatic membranes reflecting an unstable hormone-receptor complex. These results suggest that a free alpha-amino group at the N-terminus may be essential for an optimal interaction of secretin with its pancreatic receptor.

Previous work with the cryptic sister species pair of Þeld crickets, Gryllus texensis Cade & Otte and Gryllus rubens Scudder, has implicated sexual selection in the speciation process. That study examined reproductive character displacement (RCD) in male song and female preference for song in G. texensis. No evidence of RCD was found. Here, we provide a similar analysis of RCD in G. rubens song and examine the songs of both species from areas of sympatry in an effort to document the species-speciÞcity of song in sympatry and to look for individuals with songs indicative of F1 hybrid status. We 1) Þnd no evidence for RCD in G. rubens song, 2) demonstrate the distinctness of song in sympatry, and 3) document the rarity of songs typical of F1 hybrids.

The characterization and evaluation of three novel 5-microm HPLC column packings, prepared using ethyl-bridged hybrid organic/inorganic materials, is described. These highly spherical hybrid particles, which vary in specific surface area (140, 187, and 270 m(2)/g) and average pore diameter (185, 148, and 108 A), were characterized by elemental analysis, SEM, and nitrogen sorption analysis and were chemically modified in a two-step process using octadecyltrichlorosilane and trimethylchlorosilane. The resultant bonded materials had an octadecyl surface concentration of 3.17-3.35 micromol/m(2), which is comparable to the coverage obtained for an identically bonded silica particle (3.44 micromol/m(2)) that had a surface area of 344 m(2)/g. These hybrid materials were shown to have sufficient mechanical strength under conditions normally employed for traditional reversed-phase HPLC applications, using a high-pressure column flow test. The chromatographic properties of the C(18) bonded hybrid phases were compared to a C(18) bonded silica using a variety of neutral and basic analytes under the same mobile-phase conditions. The hybrid phases exhibited similar selectivity to the silica-based column, yet had improved peak tailing factors for the basic analytes. Column retentivity increased with increasing particle surface area. Elevated pH aging studies of these hybrid materials showed dramatic improvement in chemical stability for both bonded and unbonded hybrid materials compared to the C(18) bonded silica phase, as determined by monitoring the loss in column efficiency through 140-h exposure to a pH 10 triethylamine mobile phase at 50 degrees C.

Despite over a century of interest, the function of zebra stripes has never been examined systematically. Here we match variation in striping of equid species and subspecies to geographic range overlap of environmental variables in multifactor models controlling for phylogeny to simultaneously test the five major explanations for this infamous colouration. For subspecies, there are significant associations between our proxy for tabanid biting fly annoyance and most striping measures (facial and neck stripe number, flank and rump striping, leg stripe intensity and shadow striping), and between belly stripe number and tsetse fly distribution, several of which are replicated at the species level. Conversely, there is no consistent support for camouflage, predator avoidance, heat management or social interaction hypotheses. Susceptibility to ectoparasite attack is discussed in relation to short coat hair, disease transmission and blood loss. A solution to the riddle of zebra stripes, discussed by Wallace and Darwin, is at hand.

To analyze clinical and laboratory findings in order to find variables predictive of severity of Biliary Peritonitis (BP). Patients and methods. Physical findings, course of illness, imaging and laboratory data were evaluated in 42 patients with BP, and statistically analysed to assess their prognostic significance.Serious illness and worse outcome were associated with: age ≥ 60 years (P=0.034), long time between onset of symptoms and treatment (P=0.025), fever38°C (P=0.009), WBC count17,000 cell/mm³ (P=0.043), diffuse abdominal pain (P=0.034), and infected bile (P=0.048).Most patients become severely ill due to supervening infection, while early bile drainage avoids serious complications. In addition, abdominal pain, fever and WBC count are also predictive of severity of BP.

In Brazil, solid waste landfills were managed from a sanitary engineering viewpoint, and engineers operating the landfills were generally mechanical or electrical engineers, more concerned with waste collection and transport logistics than in fact with waste disposal and its possible impacts on the environment. It was only after the Bandeirantes landfill accident (see Figure 1) that geotechnical engineers were in fact called to play a more important role in landfill projects and management. It should also be mentioned that in most cases, landfill accidents do not involve people and when they do, they affect lives in areas that do not have the ability to engage the media so that the incident is not news or very quickly forgotten. Figure 2 shows the Bandeirantes landfill in operation years after the accident.

We considered the role of two neutrophil chemotactic agents (interleukin-8 and leukotriene B4) and of myeloperoxidase (a neutrophil-associated enzyme) in the pathologic condition of Crohn's disease (CD). Serial biopsy samples were taken at different sites in the colon, washed in 0.02 M phosphate-saline buffer, homogenized, and then sonicated. Interleukin-8 levels were significantly increased throughout the colonic mucosa (>300 pg/mg protein) in patients with CD compared with control groups (< 40 pg/mg protein) (p ⩽ 0 0.01). A two-to six-fold increase in leukotriene B4 was also found in CD, whereas mucosal levels of myeloperoxidase were unchanged compared with control subjects. This study demonstrates that interleukin-8 and leukotriene B4 may have an immunologic role in the pathologic condition of CD.

SummaryMany animals use conventional signals of fighting ability to mediate aggressive conflict. Given the apparent benefits of signaling inaccurately high fighting ability, there is extensive interest in why animals communicate their abilities honestly [1]. One hypothesis is that inaccurate signalers receive social punishment that disfavors inaccuracy. Although the idea that social punishment can prevent dishonesty is appealing, questions about the evolutionary stability of this hypothesis remain [2]. For example, how do individuals know a rival is cheating? We independently manipulated a signal of fighting ability and agonistic behavior in Polistes dominulus wasps to test the behavioral mechanisms underlying social punishment. Remarkably, a mismatch between signal and behavior caused social punishment. Individuals with experimentally altered signals received more aggression from rivals. Individuals with experimentally altered behavior were less able to establish dominance relationships. In contrast, control individuals and those with experimentally altered signal and behavior suffered neither cost. They received little aggression and established stable dominance relationships. Therefore, individuals use information about the match between signal and behavior to assess the accuracy of rival signals. A mismatch produces costly social interactions. This simple behavioral mechanism provides a clear cost to signal inaccuracy that may maintain honest communication over evolutionary time.

There has been increasing interest in the mechanisms that mediate behavioral and physiological plasticity across individuals with similar genotypes. Some of the most dramatic plasticity is found within and between social insect castes. For example, Polistes wasp queens can nest alone, dominate a group of cooperative queens, or act as worker-like subordinates who rarely reproduce. Previous work suggests that condition-dependent endocrine responses may play a role in plasticity between castes in the hymenoptera. Here, we test whether condition-dependent endocrine responses influence plasticity within castes in the wasp Polistes dominulus. We experimentally manipulate juvenile hormone (JH) titers in nest-founding queens and assess whether JH mediates variation in behavior and physiology. JH generally increased dominance and fertility of queens, but JH's effects were not uniform across individuals. JH had a stronger effect on the dominance and fertility of large individuals and individuals with facial patterns advertising high quality than on the dominance and fertility of small individuals and those advertising low quality. These results demonstrate that JH has condition-dependent effects. As such, they clarify how JH can mediate different behaviors in well nourished queens and poorly nourished workers. Many Polistes queens nest cooperatively with other queens, so condition-dependent hormonal responses provide a mechanism for queens to adaptively allocate energy based on their probability of successfully becoming the dominant queen. Research on the endocrine basis of plasticity often focuses on variation in endocrine titers alone. However, differential endocrine responses are likely to be a widespread mechanism mediating behavioral and physiological plasticity.

We have prepared villous cells from the jejunum of the rat small intestine and studied the effects of divalent cations and bacitracin on the binding and internalization of VIP. Villous epithelial cells (4 x 10(6) cells/ml) were suspended in a Hepes-NaCl buffer with 1.0% BSA, (pH 7.4) and the cells were incubated for varying periods of time with 125I-VIP at 24 degrees C. Specific binding of radiolabeled VIP was maximal within 10 min (10%) and slowly declined to 9.0 percent after 30 min. In the presence of 1.0 mg/ml bacitracin, however, maximal specific binding of VIP was only 2.7 percent (P less than or equal to 0.001). The addition of CA2+ or Mg2+ to the buffer significantly decreased binding of VIP in a concentration dependent manner. At 8.0, 4.0, 2.0 and 1.0 mM Ca2+, binding of 125I-VIP decreased by 70, 60, 40 and 25 percent, whereas in the presence of the same concentrations of Mg2+ binding was decreased to 50, 38, 25 and 10 percent (P less than or equal to 0.01). To determine if epithelial cells internalize VIP, we bound 125I-VIP to villous cells and then differentiated surface-bound and internalized radioactivity by treating with trypsin (150 micrograms/ml). Surface bound radioligand was the same at both 24 and 4 degrees C (5.3%), while internalized 125I-VIP was 4.0% at 24 degrees C compared to only 1.0% at 4 degrees C (P less than or equal to 0.001). At 24 and 4 degrees C, both Ca2+ (4.0 mM) and Mg2+ (8.0 mM) decreased surface bound radioligand by 60 percent (P less than or equal to 0.01) and lowered internalized radioactivity. These data demonstrate that (1) bacitracin decreases the binding of VIP to small intestinal epithelial cells, (2) both Ca2+ and Mg2+ affect the binding of VIP to its surface receptor and (3) VIP is internalized into epithelial cells.

Human papillomaviruses (HPVs) are the cause of cervical intraepithelial neoplasia and invasive carcinomas of the uterine cervix. The distribution of specific HPV genotypes varies greatly across populations and HPV surveys have been performed in different geographical regions in order to apply appropriate vaccine strategies. The aim of this study was to determine the spectrum of HPV genotypes and HPV-16 variants among women with cervical lesions living in Ecuador. A total of 71 cases have been analyzed, including 32 chronic cervicitis, 29 cervical intraepithelial neoplasia grade 1, and 10 cervical intraepithelial neoplasia grade 2-3. HPV sequences were detected by broad spectrum consensus-primer-pairs MY09/MY11 and GP5+/GP6+-based polymerase chain reaction and characterized by nucleotide sequence analysis. Overall, 31 (43.7%) cases were HPV positive with prevalence rates of 37.5%, 44.8%, and 60% in patients with chronic cervicitis, cervical intraepithelial neoplasia grade 1 and cervical intraepithelial neoplasia grade 2-3, respectively. Among the positive cases, the most common genotypes were HPV 16 (64.5%) and HPV 81 (29%) followed by HPV 31, 53, 56, and 58, in descending order of prevalence. Seventeen (85%) HPV-16 isolates were classified as European and three (15%) as African-1 variant on the basis of nucleotide signature present within the MY09/MY11 L1 sequence. The results suggest that HPV 16 has a very high prevalence among women with cervical lesions in Ecuador; therefore, an effective HPV-16 based vaccine should prevent the development of cervical cancer in a large proportion of Ecuadorian women.

In this study we describe the synthesis and purification of biotinylated cholecystokinin-8 (Bio-CCK-8) and characterize its use as a probe for the pancreatic cholecystokinin receptor. CCK-8 (0.1 umoles) was reacted with either radiolabeled d-[8,9-3H]biotin succinimide ester (0.5 umoles) or N-hydroxysuccinimidyl-biotin in dimethylformamide and triethylamine, and purified by anion exchange chromatography. Concentrations of Bio-CCK-8 and CCK-8 needed for half-maximal inhibition of [l25]I-CCK-8 binding to pancreatic membranes were the same (1.0 and 1.3 nM). Bio-CCK-8 retained full biological activity as determined by stimulation of pancreatic protein secretion from rats, and the biotin group bound to CCK-8 retained its high sensitivity for avidin.

In this study we considered the effect of chloroquine on the processing and intracellular distribution of internalized secretin radioligand in acinar cells. Chloroquine (100 microM) had no effect on the total amount of 125I-secretin bound but had marked effects on the processing of this radioligand in acinar cells. After an initial 60 min of radioligand binding in the presence and absence of chloroquine, cells were washed free of unbound radioligand, resuspended and then processed for different times at 37 degrees C. During 60, 120 and 180 min of processing, the amount of internalized radioligand in the presence of 100 microM chloroquine was increased by 116, 194 and 273%, respectively, compared to untreated control samples. Chloroquine also increased the amount of intact 125I-secretin radioligand within the cell as measured by rebinding to pancreatic plasma membranes. After 120 and 180 min of processing, intact peptide within the acinar cell was 25 and 66% greater in the presence of this agent than in control samples (P less than or equal to 0.01). To determine if chloroquine affected intracellular localization of the secretin radioligand, we measured the amount of radioactivity in soluble and particulate fractions of cell homogenates. Chloroquine decreased radioactivity entering particulate fractions of the cell by greater than 35% after 120 and 180 min of processing (P less than or equal to 0.01). This study demonstrates that (1) chloroquine inhibits the intracellular degradation of secretin in acinar cells and (2) chloroquine alters intracellular localization of this peptide during processing.

Retinoids play an important role in the regulation of normal growth and development. Their biological action is mediated by a nuclear receptor that belongs to the steroid/thyroid hormone receptors superfamily. Retinoic acid has been shown to inhibit the secretion and synthesis of thyrotropin (TSH); however, little is known on the effects of retinoids on TSH secretion in normal human subjects. In the present study, we evaluated serum TSH concentration following both vitamin A (vit A) and the combined vit A and triiodothyronine (T(3)) administration. Basal and thyrotropin-releasing hormone (TRH)-stimulated TSH serum concentrations were measured in healthy young subjects in the following experimental conditions: (1) after 10 days of treatment with vit A orally administered as retinol at a dose of 50,000 IU/d; (2) after 10 days of oral placebo (PL) treatment; (3) after 1 hour from the administration of 40 mg T(3) at the end of 10 days of PL treatment; and (4) after 1 hour from the administration of 40 mg T(3) at the end of 10 days of vit A treatment. Serum TSH concentrations were also measured during vit A administration in healthy elderly subjects according to the following protocol: (1) after 10 days of treatment with PL; and (2) after 10 days of treatment with vit A at the same dose used for young subjects. In young subjects, basal serum TSH levels were found to be similar in the 4 different treatment conditions. In the same group of subjects, each of the 4 experimental conditions induced an increase in serum TSH, which rose from basal values of 1.80 +/- 0.31 to a peak of 11.92 +/- 1.75 microIU/mL (P

We compared nuclear matrix protein compositions (NMPS) in colonic tissue from three different patient groups: 1) normal controls; 2) ulcerative colitis (UC); and 3) ulcerative colitis with dysplasia (UC-dysplasia). NMPS were separated by two-dimensional electrophoresis using isoelectrofocusing and SDS-PAGE. Six specific NMPS (59,500 Kd, pI 6.6 and 6.3; 49,250 Kd, pI 7.4; 33,750 Kd, pI 7.5; 20,000 Kd, pI 7.5; and 19,000 Kd, pI 6.3) were identified in UC-dysplasia that were not found in normal controls nor in UC colonic tissue. These observations suggest that NMPS may serve as important biochemical markers of dysplasia in UC.

Twenty-one patients with uterine bleeding who failed to respond to pharmacological treatment underwent Nd-Yag endometrial photocoagulation following preparation with slow-release triptorelin. All patients were carefully selected after a complete clinical, echographic, hormonal, hysteroscopic and histological screening. Subjects with menometrorrhagia due to high-risk endometrial pathologies and various causes were excluded from the study. The technique uses a modified urological resectoscope which enables the Nd-Yag laser optic fibre to be inserted and to move the tip by 30 degrees. The entire endometrial cavity was treated using a power of between 40 and 60 watts and in all cases analogs were administered preparatively for 3 months prior to surgery (slow-release triptorelin). No complications arose during treatment. Operating times were between 40 and 90 minutes. Fourteen of the patients currently do not report cyclical bleeding; 7 have modified periodic bleeding (3 with algomenorrhea which is overcome using bland oral analgesics). In conclusion the authors affirm that the technique is of considerable value, but requires lengthy training for operators and undoubtedly a high initial cost of equipment which is only justified by multidisciplinary use.

This clinical study was carried out in our division on 106 patients undergoing surgery for various pathologies in the period from May to September 1991; the aim of this study was the evaluation of short-term antibiotic prophylaxis before and after surgery: either imipenem-cilastatin, or cephalosporin or no treatment. Imipenem-cilastatin was found to be the antibiotic of choice for short-term prophylaxis.

The internalization of [125I]secretin in pancreatic acinar cells was evaluated by differentiation of surface-bound and internalized radioligand with an acidified glycine buffer. The amount of surface-bound radioligand was 2-fold higher at 37 C than at 4 C between 15 and 60 min; internalized radioactivity was more than 10-fold greater at 37 C than at 4 C during the same time period. The effects of chloroquine, dithiothreitol (DTT), carbonyl cyanide m-chlorophenyl-hydrazone (CCCP), and dansylcadaverine on the binding and internalization of secretin were then evaluated. Chloroquine (0.1 mM), a lysosomotropic agent, did not affect secretin radioligand binding to its pancreatic receptor, while DTT, a sulfhydryl reducing agent, significantly lowered binding by more than 90% from 15-60 min. The metabolic inhibitor CCCP, however, significantly enhanced binding of the secretin radioligand in both the surface and the internalized pools. Surface binding was 1.6- to 3.3-fold greater from 15-60 min (P less than or equal to 0.01) in acinar cells exposed to CCCP than in untreated controls, while internalized radioactivity increased from 2.8- to 1.4-fold above the control value (P less than or equal to 0.01) at the same times. Dansylcadaverine, an inhibitor of receptor recycling, reduced internalized radioligand by 40% after 30 min of binding. The effects of these chemical agents on cAMP production were also considered. cAMP production was significantly reduced by DTT, CCCP, and dansylcadaverine at secretin concentrations of 0.1, 3.0, and 10 nM, respectively. This study demonstrates that 1) pancreatic acinar cells rapidly internalize [125I]secretin; 2) internalization of secretin does not enhance cAMP production; and 3) disulfide linkages are important for secretin receptor activity.

Immunoreactive cholecystokinin (CCK) levels in human and rat plasma are described using a radioimmunoassay specific for the biologically active sulfated end of CCK. This assay detected significant changes in plasma cholecystokinin levels during intrajejunal administration of amino acids and intravenous infusions of CCK-8 which were followed by increased pancreatic secretion. In humans, the concentration (pg/ml) of plasma cholecystokinin increased from 10.8 to 18.9 following intrajejunal amino acid instillation and from 15.4 to 31.1 during CCK infusion, while pancreatic trypsin secretion increased more than 15 fold. Ingestion of a test meal also caused a rapid and significant elevation ( P ) in both plasma CCK (14.5–21.7 pg/ml) and gastrin (50–160 pg/ml) levels. In the rat, an injection of 46 ng of CCK-8 produced a 300% increase in immunoreactive plasma CCK levels (2 min) and caused peak pancreatic protein secretion within 5 min; 4 fold lower doses (11.5 ng) elevated plasma CCK by 38% and pancreatic protein secretion to a small but significant extent. The ability of this assay to detect various forms of sulfated CCK in human plasma was also determined. Following gel chromatography on Sephadex G-50, at least three different immunoreactive peaks were found in plasma from fasted subjects and after intrajejunal amino acid stimulation. While the lower molecular weight CCK peptides (CCK-8 and CCK-12) were detected in plasma from both fasted and stimulated subjects, the larger form (CCK-33) was only present in measurable concentrations after amino acid infusion. The simultaneous measurement of increased plasma CCK levels and pancreatic secretion and the changes in the distribution of CCK peptides following amino acid infusion provides strong support that this assay detects physiologically relevant changes in biologically active CCK peptides.

The tolerance of 10% Travamulsion Intravenous Fat Emulsion (Travenol Laboratories, Inc., Deerfield, IL) was studied using beagle dogs. Physiological (0.9%) saline, USP, was used as the control, and Intralipid 10% Fat Emulsion (Vitrum, Sweden) as the reference article. The emulsions were administered intravenously to each of 10 animals for 91 days at a dosage of 40 ml (approximately 4 g)/kg of body weight/day. The saline was administered to 10 animals at 40 ml/kg/day. On day 92, 7 of the 10 animals in each group were necropsied. The remainder were observed and necropsied at approximately day 160. Toxicity was assessed on the basis of animal survival; changes in body weight, hematology, and serum chemistry; gross pathology; and histopathology. The results obtained for the Travenol emulsion correlated well with those for the Vitrum emulsion. The emulsions were well tolerated and they did not produce any major clinical signs of toxicity. All animals survived and gained weight. The Travenol emulsion administered provided about 45% of the total caloric requirement of the dog which is equal to an often used clinical dose. However, the emulsion was infused at six times the indicated clinical rate. Thus, in addition to demonstrating the similarity of Travenol and Vitrum emulsions, the results of this study indicate that the Travenol emulsion is safe for prolonged administration.

The tolerance of 20% Travamulsion intravenous fat emulsion (Travenol Laboratories, Inc., Deerfield, IL) was studied using male beagle dogs. Physiologic (0.9%) saline, USP, was used as the control, and 10% Travamulsion Intravenous fat emulsion (Travenol Laboratories) as the reference article. The 20 and 10% emulsions were administered intravenously to each of eight animals for 91 days at 20 and 40 ml/kg/day, respectively. These dosages were administered over 4 hr and they correspond to approximately 4 g of lipid as soybean oil per kilogram of body weight. The saline was administered to eight animals at 40 ml/kg/day. On day 92, one-half of the animals in each group were necropsied. The remaining dogs were observed and necropsied on day 122. Toxicity was assessed on animal survival; changes in body weight, urinalysis, and hematologic, and serum biochemical analyses; ophthalmologic examination; gross pathology; and histopathology. The results obtained for the 20% Travamulsion fat emulsion correlated well with those for the 10% Travamulsion fat emulsion. The emulsions were well tolerated and all animals survived and gained weight. The 20% Travamulsion fat emulsion administered provided about 45% of the total caloric requirement of the dog, which is equal to an often used clinical dose. However, caloric administration in the form of lipid emulsion in relation to total energy required was performed at three to six times the indicated clinical rate. In addition to demonstrating that it is safe for prolonged administration, the 20% Travamulsion fat emulsion offers an advantage over the 10% Travamulsion fat emulsion in providing the same amount of calories because it produces lower serum levels of phospholipid, cholesterol, and triglyceride, and the volume of emulsion required is reduced.

We have previously shown that the incubation of normal rat adipose tissue with sera from nondialyzed, nondiabetic uremic patients reduces the transport and metabolism of glucose, in the absence and presence of insulin. In this study insulin-stimulated glucose metabolism by normal rat adipocytes was used as a bioassay to identify the resistance activity, assess the effect of chemical modification on it, and the clinical states associated with its production. The resistance activity was trypsin-labile and had an apparent isoelectric point between 6 and 7, but was not retained by either protein A or concanavalin A columns. The insulin resistance activity was decreased by coincubation with the protein synthesis inhibitor, cycloheximide. Purification to greater than 200,000-fold was attained by heating (100 degrees C) uremic serum, subjecting the supernatant to Sephadex G-25 chromatography and subsequent adsorption to DEAE at pH 7.8 and elution at pH 6.5. The partially purified resistance activity was retained within dialysis tubing of 1,000-mol wt cutoff but not within 2,000-mol wt cutoff. Hemodialysis of patients over 1 wk to 18 mo reduced significantly the amount of resistance activity in their sera. The resistance activity, present in most uremic patients, was not found in the sera of individuals with normal renal function but who were either obese, fasted, elderly or had type II diabetes mellitus. Thus, a circulating small molecular weight peptide, unique to uremia, induced insulin resistance by a protein synthesis-dependent mechanism.

Man encounters the plasticizer di-(2-ethylhexyl) phthalate (DEHP) parenterally as a dilute complex formed in stored blood. Aqueous solutions stored in polyvinyl chloride (PVC) containers extract little DEHP. During development of newer container materials with fewer extractives the continued use of PVC requires realistic understanding of the toxic potential of DEHP. Earlier implications of possible toxicity resulted from the unusual neutral, lipophilic, and insoluble nature of the compound, but none of the investigations was performed with DEHP in the form received by man (diffusion complex). To characterize that form we formulated sheets of PVC identical to that used in blood bags, but containing [ 14 C]DEHP. Particle formation after contact with plasma was not related to DEHP accumulation. With careful technique, suspensions of DEHP in Polysorbate-80 or solutions in ethanol could be added to plasma with minimal particle formation. Extraction from PVC was not affected by the plasma lipid content, but was limited by total protein concentration. After iv injection of [ 14 C]DEHP in rats as the diffusion complex rather than a complex from Polysorbate-80 or ethanol, the second phase of 14 C half-life was shorter, liver retention was lower, and excretion was faster. In isolated perfused rat liver, 14 C of the diffusion complex was metabolized and excreted rapidly in bile. Thus, studies of potential toxicity should recognize that man receives DEHP in blood as a dilute, nonparticulate complex (relevant form). Other physical forms (designated “irrelevant”) are subject to different rates of disposition and metabolism and can produce misleading implications of toxicity.

Induction of insulin resistance in normal adipose tissue by uremic human serum. An incubation of uremic human serum with normal rat adipose tissue will make the subsequently isolated adipocytes less responsive to insulin. To examine the extent of insulin resistance, we obtained sera from nondiabetic, uremic patients, who had not undergone dialysis therapy. The sera were then dialyzed (3500 molecular-weight cutoff) for 18 hr against a defined culture medium to eliminate possible in vitro effects of altered levels of end-product metabolites, electrolytes, and metabolic substrates. After an incubation of epididymal fat tissue from normal rats, for 3 hr with the dialyzed sera (50% vol/vol), cells were isolated and washed. The insulin stimulation of 14 C-glucose (0.2 mM) incorporation to 14 CO 2 and total lipids was significantly reduced in the adipocytes pretreated with sera from 19 of the 29 uremic patients. Although elevated in the uremic patients, the sera levels of insulin, and parathyroid and growth hormones were not correlated to insulin resistant activity. Furthermore, incubation of adipose tissue for 3 hr with insulin, glucagon, or PTH did not produce resistance. The uremic sera reduced glucose utilization equally at 0.2 and 50 mM glucose, suggesting that the insulin resistance was induced additionally at a site distal to the glucose transport system. However, the concentration of insulin (22 µU/ml) required for half-maximal stimulation of glucose metabolism was not altered by pretreatment with uremic serum. Also, neither the isoproterenol-stimulated lipolysis nor the inhibition of this cellular event was influenced by pretreatment with uremic sera. Thus, the serum factor(s), which is not an end-product metabolite or a known glucoregulatory hormone, produces an insulin-resistant state similar in several aspects to that of tissue from uremic animals. Induction d'une resistance a l'insuline dans du tissu adipeux normal par du serum humain uremique. L'incubation de serum humain uremique avec du tissu adipeux de rat normal rendra les adipocytes isoles ensuite moins sensibles a l'insuline. Afin d'examiner l'importance de la resistance a l'insuline, nous avons obtenu des serums de malades uremiques, non diabetiques, n'ayant jamais ete en dialyse. Les serums ont ensuite ete dialyses (limite de poids moleculaire 3500) pendant 18 hr contre un milieu de culture defini pour eliminer les effets in vitro possibles des niveaux alteres des metabolites terminaux, de electrolytes, et des substrats metaboliques. Apres incubation de tissu graisseux epididymaire de rats normaux pendant 3 hr avec les serums dialyses (50% vol/vol), les cellules etaient isolees et lavees. La stimulation par l'insuline de l'incorporation de 14 C-glucose (0,2 mM) en 14 CO 2 et les lipides totaux etaient significativement reduits dans les adipocytes pre-traites avec les serums de 19 des 29 malades uremiques. Bien qu'eleves chez les uremiques, les niveaux seriques d'insuline, et d'hormone parathyroidienne et de croissance n'etaient pas correles a resistance a l'insuline. En outre, l'incubation de tissu adipeux pendant 3 hr avec de l'insuline, du glucagon ou de l'hormone parathyroidienne n'a pas entraine de resistance. Les serums uremiques ont reduit l'utilisation de glucose de facon egale pour 0,2 et 50 mM de glucose, suggerant que la resistance a l'insuline etait induite additionnellement a un site plus distal que le systeme de transport du glucose. Cependant, la concentration d'insuline (22 µU/ml) necessaire a la stimulation demi-maximale du metabolisme du glucose n'etait pas alteree par le pre-traitement avec du serum uremique. Egalement, ni la lipolyse stimulee par l'isoproterenol, ni l'inhibition de ce phenomene cellulaire n'etait influencees par le pretraitement avec les serums uremiques. Ainsi, ce(s) facteur(s) serique(s), qui n'est pas un metabolite terminal ni une hormone glycoregulatrice connue, produit un etat de resistance a l'insuline, identique par plusierus aspects a celui des tissus d'animaux uremiques.

Both radiotrace labeled and high specific activity 125I-labeled derivatives of secretin were prepared by direction iodination of the histidyl residue with chloramine T [( 125I]secretin) and by conjugation of a preiodinated Bolton-Hunter group (iodo-3-(4-hydroxyphenyl)propionate) to the free alpha-amino group at the N-terminus [( 125I]BH-secretin). Following purification, the biological, immunological and receptor binding properties of both secretin derivatives were compared. [125I]secretin and [125I]BH-secretin were equally effective in a sensitive radioimmunoassay that detected secretin and secretin (5-27) but not CCK-8, VIP and glucagon. Although both derivatives retained 60% of the biological potency of secretin as measured by cAMP accumulation in pancreatic acinar cells, only the directly iodinated peptide [( 125I]secretin) could be used to characterize specific binding sites on rat pancreatic membranes. The N-terminal blocked derivative [( 125I]BH-secretin) in contrast dissociated rapidly from pancreatic membranes reflecting an unstable hormone-receptor complex. These results suggest that a free alpha-amino group at the N-terminus may be essential for an optimal interaction of secretin with its pancreatic receptor.

In this study we have utilized a sensitive and specific radioimmunoassay for cholecystokinin (CCK) to determine the effects of a jejunal infusion (5 cc/min) of amino acids (44 g/liter), saline, and amino acids with intravenous atropine (20 micrograms X lg-1 X hr) on pancreatic exocrine secretion. Amino acids were found to stimulate pancreatic output of trypsin and release CCK, while a saline infusion at the same rate and osmolality (320 mosm/liter) failed to do so. In the presence of atropine, the amino acid infusion did not stimulate the pancreatic output of trypsin, despite an augmented CCK release. The total CCK released above baseline was greatest with the infusion of amino acids with atropine, while the total trypsin output above baseline was greatest with the infusion of amino acids. These results indicate that CCK release is not under cholinergic control and that cholinergic blockade inhibits pancreatic secretion by interrupting stimulating cholinergic fibers to the pancreas.

We measured cholecystokinin (CCK) in pancreatic duct secretions (PDS) after infusion of different amounts of CCK-8 (the C-terminal octapeptide of cholecystokinin) into rats. Injection of 23, 46, and 92 ng of CCK-8 increased immunoreactive cholecystokinin in PDS by 3-, 13-, and 28-fold above basal levels within 30 min. Continuous intravenous infusion of CCK-8 (50 ng/min) into rats for 30 min, followed by a 30-min rest period, and then a final infusion of peptide for another 30 min increased CCK in PDS only during the final period by 12-fold to 500 pg/30 min. Neither gastrin nor oxidized CCK-8 were detected in PDS after intravenous infusion of each peptide. Administration of proglumide (ip), a CCK receptor antagonist, during continuous CCK infusion significantly reduced immunoreactive CCK levels in PDS to 2% of the control group (P less than or equal to 0.01). CCK was also rapidly internalized into dispersed pancreatic acinar cells in a temperature-dependent fashion, and this process was inhibited by proglumide. The above data suggest that CCK in PDS reflects a peptide-specific process that is receptor mediated. We propose that circulating cholecystokinin binds to specific receptors on pancreatic acinar cells, is internalized, and is then secreted into pancreatic duct fluid.

The principal aim of this research is to solve problems of water-budget estimation in particularly indeterminate conditions, of the kind that are frequently encountered in the field, in which absence or insufficiency of hydrographic instrumentation prevents the adequate evaluation of runoff.

Pancreatic membrane receptors for cholecystokinin (CCK) in obese and nonobese Zucker rats were compared with the use of a biologically active [125I]iodo-CCK-8 radioprobe. Membrane homogenates from obese rats bound half the amount of radioligand in 2 h as did membranes from lean rats (specifically bound, 7.0% vs. 14.0%; P less than 0.001). The reduced binding in membranes from obese rats did not result from kinetic effects or radioligand degradation; similar rates of association and dissociation of [125I]iodo-CCK-8 were obtained in membrane preparations from both, and no differences were found in the extent of radioligand degradation in the two membrane preparations. These differences also did not reflect an effect of cell size, as pancreatic acinar cells from obese and nonobese rats had about the same perimeters (24.6 and 26.3 micron, respectively) and areas (30.1 and 34.2 micron 2, respectively). Scatchard-type plots of competitive displacement data for CCK-binding sites on pancreatic membranes from both genotypes were curvilinear and were analyzed by a two-site binding model. The Kd values for both the high (0.56 vs. 0.45 nM) and low (9.0 vs. 14 nM) affinity sites on membranes from nonobese and obese rats, respectively, were the same (P greater than 0.1), whereas the capacities for CCK in the high (365 vs. 165 fmol/mg protein) and low (1020 vs. 360 fmol/mg protein) affinity regions were significantly different (P less than 0.025). This difference in CCK receptor capacity was reflected by a reduced pancreatic protein secretory response in the obese rat. After injections of 40, 80, 160, and 320 ng CCK/kg BW, total pancreatic protein secretion in nonobese rats increased 5, 12, 19, and 21 times above basal levels, whereas the same doses caused 2-, 6-, 12-, and 13-fold increases in obese rats. Whereas the reduced secretion in the obese rat may reflect a difference in the intracellular machinery leading to protein secretion between the two genotypes, these data are more consistent with a direct mechanism, whereby reduced numbers of pancreatic receptors for CCK are responsible for reduced protein secretion.