31 results on '"Hamo M"'
Search Results
2. Metabolomic Biomarkers Measured at Patient Discharge Predict Long-Term Physical Function in Survivors of Acute Respiratory Failure
- Author
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Shaw, T., primary, Grant, K., additional, Gandotra, S., additional, Hartsell, E., additional, Daly, G.T., additional, Purcell, L.D., additional, Hamo, M., additional, Gillespie, M.N., additional, Files, D.C., additional, Morris, P.E., additional, and Langley, R.J., additional
- Published
- 2022
- Full Text
- View/download PDF
3. Quantitation and Characterization of Cell-Free Mitochondrial DNA in Plasma by Deep Sequencing
- Author
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Matthew E. Kutcher, Jon D. Simmons, Hamo M, V.M. Pastukh, Hank W. Bass, Zachary M. Turpin, S.C. Groark, Mark N. Gillespie, Yong B. Tan, C.M. Francis, G. Daly, Hartsell Em, Raymond J. Langley, C.Z. Aggen, C. Edwards, and Dinwiddie Dl
- Subjects
Mitochondrial DNA ,Biochemistry ,Chemistry ,Cell free ,Deep sequencing - Abstract
The presence in plasma of mitochondrial DNA (mtDNA) fragments, a proinflammatory damage-associated molecular pattern (DAMP), is positively associated with outcomes of multiple human disorders. Because mtDNA comprises only a small percentage of the total DNA in plasma, qPCR is typically employed as an analytic strategy. However, this method provides little insight into sequence origins or other characteristics of circulating mtDNA fragments. Here we found that target bait-capture applied to plasma mtDNA derived from severely injured patients enriched recovery by ≈ 1400-fold, thus affording depth sufficient for NextGen sequence analysis. Our method excluded nuclear mitochondrial insertions (NUMTs) using a stringent alignment and filtering strategy which calls and quantifies both NUMT in the reference genome and polymorphic NUMTs. After enrichment, we sequenced 2,000–60,000x mean coverage over the mtDNA genome. Normalization of mtDNA abundance to NUMT coverage reduced batch variability. Two massively-transfused trauma patients and two non-transfused patients displayed time-dependent increases in mtDNA DAMP coverage and decreases in the mean fragment length, which were more pronounced in massively transfused patients. Finally, our approach enabled detection of low-frequency heteroplasmic variants. Collectively, these findings suggest that our target bait-capture, deep sequencing and attendant analytic protocols could provide unprecedented characterization of cell-free plasma mtDNA and NUMTs.
- Published
- 2021
4. Waking to drink: rates of evaporative water loss determine arousal frequency in hibernating bats.
- Author
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Ben-Hamo, M. and Pinshow, B.
- Subjects
- *
HIBERNATION , *BODY temperature , *ANIMAL wintering - Abstract
Hibernation is an adaptive strategy in bats that facilitates coping with low ambient temperatures (Ta) and scarce food during winter. The decline in metabolic rate (MR) and body temperature (Tb) of a bat during hibernation brings about a significant reduction in nutrients and water use, enhancing the probability of survival (Geiser and Koertner, 2010). However, hibernation is not a constant state of reduced Tb and MR, rather it comprises bouts of torpor interspersed with periods of arousal, when the animal returns to its normothermic Tb and MR (French, 1985). Although, bats arouse for only 5-10% of the time that they hibernate, arousals can account for over 85% of a hibernating bat's energy expenditure (Wang, 1978). Many different hypotheses attempting to explain periodic arousals have been proposed (Thomas and Geiser, 1997); all relate arousals to processes, such as metabolism and water loss, that vary in the same direction with Tb and Ta. Consequently, they give rise to the same prediction, namely that torpor bout length (TBL) is negatively correlated with Ta and Tb. This correlation alone cannot establish a causal link between arousal and the proposed processes, and, in addition, it introduces a difficulty in distinguishing between the hypotheses. We tested the "water balance" hypothesis, first proposed by Fisher and Manery (1967) that asserts that hibernating animals continuously lose water through evaporation while hibernating, and the ensuing dehydration initiates arousals, during which the animal rehydrates by drinking (Thomas and Geiser, 1997). We tested our hypothesis in groups of a small bat, Kuhl's pipistrelle (Pipistrellus kuhlii), that were all maintained at constant Ta and constant absolute humidity. We assumed that at constant Ta, bats have similar Tbs and MRs, and that water vapor density at the skin surface is saturated at skin temperature. We manipulated the difference in water vapor density (ew) between the skin surface (es) and the adjacent ambient air (ea) by changing ea, and measured water loss in Kuhl's pipistrelles in both dry and humid air, at constant Ta. We found that TBL and TEWL were significantly related in hibernating Kuhl's pipistrelles, independent of MR and/or Ta, supporting the water balance hypothesis, while distinguishing it from other hypotheses that relate processes correlated with MR, Ta, or both. We also found that arousal frequency during hibernation was positively related with the amount of body mass (mb) lost during this period, suggesting that bats with higher rates of TEWL that awoke more frequently lost more mb and thus end hibernation with smaller fat reserves. These results demonstrate the importance of TEWL in survival of overwintering bats. Most, if not all, temperate zone bats in both suborders, the Yangochiroptera and Yinpterochiroptera, are hibernators (Altringham, 2011). Therefore, due to the similarities in the ecological and behavioral characteristics of these animals, the possibility exists that what we found in P. kuhlii, a vespertilionid bat, may occur in other hibernating bat species of different families. [ABSTRACT FROM AUTHOR]
- Published
- 2013
5. Benefits of stereotactic radiosurgical anterior capsulotomy for obsessive-compulsive disorder: a meta-analysis.
- Author
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Gupta R, Chen JW, Hughes NC, Hamo M, Jean-Baptiste S, Paulo DL, Chanbour H, Fan R, Ye F, Vadali A, Cmelak A, and Bick SK
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- Humans, Treatment Outcome, Internal Capsule surgery, Radiosurgery methods, Radiosurgery adverse effects, Obsessive-Compulsive Disorder surgery
- Abstract
Objective: Anterior capsulotomy (AC) is a therapeutic option for patients with severe, treatment-resistant obsessive-compulsive disorder (OCD). The procedure can be performed via multiple techniques, with stereotactic radiosurgery (SRS) gaining popularity because of its minimally invasive nature. The risk-benefit profile of AC performed specifically with SRS has not been well characterized. Therefore, the primary objective of this study was to characterize outcomes following stereotactic radiosurgical AC in OCD patients., Methods: Studies assessing mean Yale-Brown Obsessive Compulsive Scale (Y-BOCS) scores before and after stereotactic radiosurgical AC for OCD were included in this analysis. Inverse-variance fixed-effect modeling was used for pooling, and random-effects estimate of the ratio of means and standard mean differences were calculated at 6 months, 12 months, and the last follow-up for Y-BOCS scores, as well as the last follow-up for the Beck Depression Inventory (BDI)/BDI-II scores. A generalized linear mixed model was used to generate fixed- and random-effects models for categorical outcomes. Univariate random-effects meta-regression was used to evaluate associations between postoperative Y-BOCS scores and study covariates. Adverse events were summed across studies. Publication bias was assessed with Begg's test., Results: Eleven studies with 180 patients were eligible for inclusion. The mean Y-BOCS score decreased from 33.28 to 17.45 at the last-follow up (p < 0.001). Sixty percent of patients were classified as responders and 10% as partial responders, 18% experienced remission, and 4% had worsened Y-BOCS scores. The degree of improvement in the Y-BOCS score correlated with time since surgery (p = 0.046). In the random-effects model, the mean BDI at the last follow-up was not significantly different from that preoperatively. However, in an analysis performed with available paired pre- and postoperative BDI/BDI-II scores, there was significant improvement in the BDI/BDI-II scores postoperatively. Adverse events numbered 235, with headaches, weight change, mood changes, worsened depression/anxiety, and apathy occurring most commonly., Conclusions: Stereotactic radiosurgical AC is an effective technique for treating OCD. Its efficacy is similar to that of AC performed via other lesioning techniques.
- Published
- 2024
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6. The circadian molecular clock in the suprachiasmatic nucleus is necessary but not sufficient for fear entrainment.
- Author
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Bussi IL, Ben-Hamo M, Salazar Leon LE, Casiraghi LP, Zhang VY, Neitz AF, Lee J, Takahashi JS, Kim JJ, and de la Iglesia HO
- Subjects
- Mice, Animals, Suprachiasmatic Nucleus, Circadian Rhythm, Fear, Circadian Clocks genetics
- Abstract
We show that nocturnal aversive stimuli presented to mice while they are eating and drinking outside of their safe nest can entrain circadian behaviors, leading to a shift toward daytime activity. We also show that the canonical molecular circadian clock is necessary for fear entrainment and that an intact molecular clockwork in the suprachiasmatic nucleus, the site of the central circadian pacemaker, is necessary but not sufficient to sustain fear entrainment of circadian rhythms. Our results demonstrate that entrainment of a circadian clock by cyclic fearful stimuli can lead to severely mistimed circadian behavior that persists even after the aversive stimulus is removed. Together, our findings support the interpretation that circadian and sleep symptoms associated with fear and anxiety disorders are, in part, the output of a fear-entrained clock, and provide a mechanistic insight into this clock., Competing Interests: Competing interests statement:The authors declare no competing interest.
- Published
- 2024
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7. Use of Fourier-transform infrared spectroscopy for real-time outbreak investigation of OXA-48-producing Escherichia coli.
- Author
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Kon H, Lurie-Weinberger MN, Lugassy C, Chen D, Schechner V, Schwaber MJ, Hussein K, Alon T, Tarabeia J, Hamo M, Firan I, Aboalhega W, Lomansov E, Mendelsohn S, Keren-Paz A, and Carmeli Y
- Subjects
- Humans, Multilocus Sequence Typing, Spectroscopy, Fourier Transform Infrared, Disease Outbreaks, beta-Lactamases genetics, Anti-Bacterial Agents pharmacology, Escherichia coli genetics, Escherichia coli Infections epidemiology
- Abstract
Background: Efficient infection control during carbapenem-resistant Enterobacterales outbreaks demands rapid and simple techniques for outbreak investigations. WGS, the current gold standard for outbreak identification, is expensive, time-consuming and requires a high level of expertise. Fourier-transform infrared (FTIR) spectroscopy (IR Biotyper) is a rapid typing method based on infrared radiation applied to samples, which provides a highly specific absorption spectrum., Objectives: To investigate an outbreak of OXA-48-producing Escherichia coli in real-time using FTIR and subsequently compare the results with WGS., Methods: Twenty-one isolates were collected during a nosocomial outbreak, and identification and antibiotic susceptibilities were confirmed by VITEK®2. FTIR was conducted for all isolates, and nine representative isolates were sequenced., Results: FTIR was able to correctly determine the clonal relatedness of the isolates and to identify the outbreak cluster, as confirmed by WGS. By WGS, isolates in the main FTIR cluster belonged to the same MLST type and core-genome MLST type, and they harboured similar plasmids and resistance genes, whereas the singletons external to the FTIR cluster had different genetic content., Conclusions: FTIR can operate as a rapid, efficient and reliable first-line tool for outbreak investigations during a real-time ongoing E. coli outbreak, which can contribute to limiting the spread of pathogens., (© The Author(s) 2023. Published by Oxford University Press on behalf of British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)
- Published
- 2024
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8. [EXCESS WEIGHT AND SOCIODEMOGRAPHIC RISK FACTORS FOR SARS-COV-2 INFECTION IN ISRAEL].
- Author
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Milloh Raz H, Ben-Hamo M, Minsky N, Zacay G, and Segal-Lieberman G
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- Male, Humans, Israel epidemiology, Cross-Sectional Studies, SARS-CoV-2, Weight Gain, Risk Factors, Obesity epidemiology, Body Weight, COVID-19 epidemiology
- Abstract
Background: Studies to date have demonstrated an increased prevalence of obesity and low socioeconomic status (SES( among people with confirmed cases of COVID-19, and low SES has been linked to obesity., Objectives: Our goal was to better understand the important relationship between body weight and sociodemographic variables affecting the COVID-19 burden., Methods: We conducted a cross-sectional study of subjects presenting to Israel's largest emergency department and their odds for positive SARS-CoV-2 virus PCR testing during the first wave of the pandemic., Results: We found that as BMI rises, as compared to normal weight, it is associated with increasing odds for testing positive, independently of age, gender, SES and population density (BMI 25-29.9 kg/m2: OR = 1.42, 95% CI 1.07 - 1.90; BMI 30-34.9 kg/m2: OR = 1.50, 95% CI 1.06 - 2.11; BMI ≥ 35 kg/m2: OR = 1.61, 95% CI 1.02 - 2.46). Furthermore, male gender, low SES and high population density are also associated with excess risk for positive test results independently of body weight., Conclusions: Understanding these risk factors for infection and how they might interplay can help the medical community develop approaches to protect at-risk groups from infection and severe disease secondary to seasonal and pandemic viral infections.
- Published
- 2023
9. The circadian molecular clock in the suprachiasmatic nucleus is necessary but not sufficient for fear entrainment in the mouse.
- Author
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Bussi IL, Ben-Hamo M, Leon LES, Casiraghi LP, Zhang VY, Neitz AF, Lee J, Takahashi JS, Kim JJ, and de la Iglesia HO
- Abstract
Nocturnal aversive stimuli presented to mice during eating and drinking outside of their safe nest can entrain circadian behaviors, leading to a shift toward daytime activity. We show that the canonical molecular circadian clock is necessary for fear entrainment and that an intact molecular clockwork in the suprachiasmatic nucleus (SCN), the site of the central circadian pacemaker, is necessary but not sufficient to sustain fear entrainment of circadian rhythms. Our results demonstrate that entrainment of a circadian clock by cyclic fearful stimuli can lead to severely mistimed circadian behavior that persists even after the aversive stimulus is removed. Together, our results support the interpretation that circadian and sleep symptoms associated with fear and anxiety disorders may represent the output of a fear-entrained clock., One-Sentence Summary: Cyclic fearful stimuli can entrain circadian rhythms in mice, and the molecular clock within the central circadian pacemaker is necessary but not sufficient for fear-entrainment.
- Published
- 2023
- Full Text
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10. Novel attributes of cell-free plasma mitochondrial DNA in traumatic injury.
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Daly GT, Pastukh VM, Tan YB, Francis CM, Aggen CZ, Groark SC, Edwards C, Mulekar MS, Hamo M, Simmons JD, Kutcher ME, Hartsell EM, Dinwiddie DL, Turpin ZM, Bass HW, Roberts JT, Gillespie MN, and Langley RJ
- Subjects
- DNA, Mitochondrial genetics, Mitochondria genetics, Plasma, Cell-Free Nucleic Acids genetics
- Published
- 2022
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11. Habitat aridity as a determinant of the trade-off between water conservation and evaporative heat loss in bats.
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Muñoz-Garcia A, Ben-Hamo M, Pilosof S, Williams JB, and Korine C
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- Animals, Body Temperature Regulation, Ecosystem, Water metabolism, Water Loss, Insensible physiology, Chiroptera physiology, Conservation of Water Resources
- Abstract
The maintenance of water balance in arid environments might represent a formidable challenge for Chiroptera, since they have high surface-to-volume ratios. In deserts, bats conserve water, for example, using daily torpor, but they also might experience episodic heat bouts, when they may need to increase total evaporative water loss (TEWL) to thermoregulate. We hypothesized that in bats, habitat aridity and its variability determine a trade-off between water conservation and thermoregulation via evaporative means. To test this hypothesis, we collated data from the literature of 22 species of bats on TEWL, body temperature and resting metabolic rate, in torpor and euthermy. We also collected data on ambient temperature (T
a ) and precipitation of the locations where bats were captured, calculated an aridity index, and built an index of variability of the environment. After correcting for phylogeny, we found that, as aridity and variability of the environment increased, bats had lower values of TEWL, but the rate at which TEWL increases with Ta was higher, supporting our hypothesis. These results suggest that at high Ta there is a trade-off between water conservation and evaporative heat loss in bats. The evolution of physiological mechanisms that allow water conservation and tolerance to conditions of high Ta without access to free water might thus be crucial to explain the distribution of desert bats., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)- Published
- 2022
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12. Lipid composition of the stratum corneum in different regions of the body of Kuhl's pipistrelle from the Negev Desert, Israel.
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Cockley A, Champagne AM, Ben-Hamo M, Pinshow B, Korine C, and Muñoz-Garcia A
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- Animals, Body Surface Area, Ceramides metabolism, Cerebrosides metabolism, Chiroptera anatomy & histology, Cholesterol metabolism, Chromatography, Reverse-Phase, Chromatography, Thin Layer, Female, Hot Temperature, Israel, Male, Mass Spectrometry, Permeability, Tail anatomy & histology, Wings, Animal anatomy & histology, Body Composition, Chiroptera metabolism, Desert Climate, Epidermis metabolism, Lipid Metabolism, Tail metabolism, Water Loss, Insensible, Wings, Animal metabolism
- Abstract
The most superficial epidermal layer in endotherms is the stratum corneum (SC), which is composed of dead corneocytes embedded in a lipid matrix with free fatty acids, cholesterol, ceramides, and cerebrosides; the lipid composition of the SC determines its permeability to water vapor. Lipids that are more polar, have longer hydrocarbon chains, and are less bulky are often packed in more ordered phase states to slow cutaneous evaporative water loss (CEWL); these lipids also resist transitions to more disordered phases at high ambient temperatures (T
a ). In bats, wing and tail membranes (wing patagia and tail uropatagium, respectively) allow powered flight, but increase surface area, and hence CEWL, with implications for survival in arid environments. We captured Pipistrellus kuhlii from an arid habitat and measured the lipid composition of the SC of the plagiopatagium in the wing, the uropatagium, and the non-membranous region (NMR) of the body using thin layer chromatography and reversed phase high performance liquid chromatography coupled with atmospheric pressure photoionization mass spectrometry. The patagia contained more cholesterol and shorter-chained ceramides, and fewer cerebrosides than the NMR, indicating that the lipid phase transition temperature in the patagia is lower than in the NMR. Thus, at moderate Ta the lipids in the SC in all body regions will remain in an ordered phase state, allowing water conservation; but as Ta increases, the lipids in the SC of the patagia will more easily transition into a disordered phase, resulting in increased CEWL from the patagia facilitating efficient heat dissipation in hot environments., (Copyright © 2021 Elsevier Inc. All rights reserved.)- Published
- 2021
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13. An exploratory pilot study of the effect of modified hygiene kits on handwashing with soap among internally displaced persons in Ethiopia.
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Thorseth AH, Heath T, Sisay A, Hamo M, and White S
- Abstract
Background: Internally displaced persons fleeing their homes due to conflict and drought are particularly at risk of morbidity and mortality from diarrhoeal diseases. Regular handwashing with soap (HWWS) could substantially reduce the risk of these infections, but the behaviour is challenging to practice while living in resource-poor, informal settlements. To mitigate these challenges, humanitarian aid organisations distribute hygiene kits, including soap and handwashing infrastructure. Our study aimed to assess the effect of modified hygiene kits on handwashing behaviours among internally displaced persons in Moyale, Ethiopia., Methods: The pilot study evaluated three interventions: providing liquid soap; scented soap bar; and the inclusion of a mirror in addition to the standard hygiene kit. The hygiene kits were distributed to four study arms. Three of the arms received one of the interventions in addition to the standard hygiene kit. Three to six weeks after distribution the change in behaviour and perceptions of the interventions were assessed through structured observations, surveys and focus group discussions., Results: HWWS was rare at critical times for all study arms. In the liquid soap arm, HWWS was observed for only 20% of critical times. This result was not indicated significantly different from the control arm which had a prevalence of 17% (p-value = 0.348). In the mirror and scented soap bar intervention arms, HWWS prevalence was 11 and 10%, respectively. This was indicated to be significantly different from the control arm. Participants in the focus group discussions indicated that liquid soap, scented soap bar and the mirror made handwashing more desirable. In contrast, participants did not consider the soap bar normally distributed in hygiene kits as nice to use., Conclusion: We found no evidence of an increased prevalence of handwashing with soap following distribution of the three modified hygiene kits. However, our study indicates the value in better understanding hygiene product preferences as this may contribute to increased acceptability and use among crisis-affected populations. The challenges of doing research in a conflict-affected region had considerable implications on this study's design and implementation., Trial Registration: The trial was registered at www.ClinicalTrials.gov 6 September 2019 (reg no: NCT04078633 ).
- Published
- 2021
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14. Managing Obesity in Lockdown: Survey of Health Behaviors and Telemedicine.
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Minsky NC, Pachter D, Zacay G, Chishlevitz N, Ben-Hamo M, Weiner D, and Segal-Lieberman G
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- Adult, Aged, Communicable Disease Control methods, Cross-Sectional Studies, Diet, Exercise, Female, Humans, Life Style, Male, Middle Aged, Obesity epidemiology, Obesity Management methods, SARS-CoV-2, Surveys and Questionnaires, Weight Gain, Weight Loss, COVID-19 epidemiology, Feeding Behavior, Health Behavior, Obesity therapy, Telemedicine methods
- Abstract
Since the outbreak of COVID-19, billions of people have gone into lockdown, facing pandemic related challenges that engender weight gain, especially in the obese. We report the results of an online survey, conducted during Israel's first quarantine, of 279 adults treated in hospital-based obesity clinics with counseling, medications, surgery, endoscopic procedures, or any combination of these for weight loss. In this study, we assessed the association between changes in dietary and lifestyle habits and body weight, and the benefits of receiving weight management care remotely through telemedicine during lockdown. Compared to patients not receiving obesity care via telemedicine, patients receiving this care were more likely to lose weight (OR, 2.79; p = 0.042) and also to increase participation in exercise (OR, 2.4; p = 0.022). While 40% of respondents reported consuming more sweet or salty processed snacks and 33% reported less vegetables and fruits, 65% reported more homemade foods. At the same time, 40% of respondents reported a reduction in exercise and 52% reported a decline in mood. Alterations in these eating patterns, as well as in exercise habits and mood, were significantly associated with weight changes. This study highlights that lockdown affects health behaviors associated with weight change, and advocates for the use of telemedicine to provide ongoing obesity care during future quarantines in order to promote weight loss and prevent weight gain.
- Published
- 2021
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15. Corrigendum to: Circadian regulation of sleep in a pre-clinical model of Dravet syndrome: dynamics of sleep stage and siesta re-entrainment.
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Sanchez REA, Bussi IL, Ben-Hamo M, Caldart CS, Catterall WA, and de la Iglesia HO
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- 2021
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16. Spatial and Temporal Dynamics of Mal Secco Disease Spread in Lemon Orchards in Israel.
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Ben-Hamo M, Ezra D, Krasnov H, and Blank L
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- Agriculture, Israel, Plant Diseases, Ascomycota, Citrus
- Abstract
Mal Secco is a severe disease of citrus in which the fungus Plenodomus tracheiphilus (formerly Phoma tracheiphila ) penetrates the vascular system of the host. In this study, we characterized the spatial dynamics of the disease in seven lemon orchards. A representative block of trees from each orchard was evaluated monthly during 3 consecutive years. In addition, scouts assessed disease severity in 75 orchards from three different geographical regions and tested for association between disease severity and measures of orchard management, environmental factors, cultural practices, and cultivar type. We assessed disease incidence and characteristics of spatial patterns using Ripley's K function and fitted logistic regression models for different neighboring tree structures followed by model selection methods to provide insight into the spatial and temporal dynamics of disease progress. We found different rates of disease spread in different orchards, which are most likely the result of differences in orchard management practices or less likely the result of differences in climatic conditions. There was an indication that agricultural tools contribute to spread of the disease within rows of trees. The results confirm that the lemon cultivar Interdonato is less susceptible compared with other citrus cultivars, and they suggest that the density of urban terrain surrounding each orchard is positively correlated with the severity of the disease. In contrast to our expectations, no correlation was found between the density of lemon orchards surrounding an orchard and the severity of the disease within it, which corroborates previous findings regarding the limited distribution of the disease.
- Published
- 2020
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17. Circadian regulation of sleep in a pre-clinical model of Dravet syndrome: dynamics of sleep stage and siesta re-entrainment.
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Sanchez REA, Bussi IL, Ben-Hamo M, Caldart CS, Catterall WA, and De La Iglesia HO
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- Animals, Circadian Clocks physiology, Electrocorticography methods, Epilepsies, Myoclonic genetics, Female, Jet Lag Syndrome genetics, Male, Mice, Mice, Inbred C57BL, Mice, Transgenic, NAV1.1 Voltage-Gated Sodium Channel genetics, Sleep Wake Disorders genetics, Circadian Rhythm physiology, Epilepsies, Myoclonic physiopathology, Jet Lag Syndrome physiopathology, Sleep Stages physiology, Sleep Wake Disorders physiopathology
- Abstract
Study Objectives: Sleep disturbances are common co-morbidities of epileptic disorders. Dravet syndrome (DS) is an intractable epilepsy accompanied by disturbed sleep. While there is evidence that daily sleep timing is disrupted in DS, the difficulty of chronically recording polysomnographic sleep from patients has left our understanding of the effect of DS on circadian sleep regulation incomplete. We aim to characterize circadian sleep regulation in a mouse model of DS., Methods: Here we exploit long-term electrocorticographic recordings of sleep in a mouse model of DS in which one copy of the Scn1a gene is deleted. This model both genocopies and phenocopies the disease in humans. We test the hypothesis that the deletion of Scn1a in DS mice is associated with impaired circadian regulation of sleep., Results: We find that DS mice show impairments in circadian sleep regulation, including a fragmented rhythm of non-rapid eye movement (NREM) sleep and an elongated circadian period of sleep. Next, we characterize re-entrainment of sleep stages and siesta following jet lag in the mouse. Strikingly, we find that re-entrainment of sleep following jet lag is normal in DS mice, in contrast to previous demonstrations of slowed re-entrainment of wheel-running activity. Finally, we report that DS mice are more likely to have an absent or altered daily "siesta"., Conclusions: Our findings support the hypothesis that the circadian regulation of sleep is altered in DS and highlight the value of long-term chronic polysomnographic recording in studying the role of the circadian clock on sleep/wake cycles in pre-clinical models of disease., (© Sleep Research Society 2019. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.)
- Published
- 2019
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18. Kisspeptin Neurons in the Arcuate Nucleus of the Hypothalamus Orchestrate Circadian Rhythms and Metabolism.
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Padilla SL, Perez JG, Ben-Hamo M, Johnson CW, Sanchez REA, Bussi IL, Palmiter RD, and de la Iglesia HO
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- Animals, Body Temperature physiology, Feeding Behavior physiology, Female, Locomotion physiology, Mice, Sleep physiology, Arcuate Nucleus of Hypothalamus physiology, Circadian Rhythm physiology, Kisspeptins metabolism, Neurons physiology
- Abstract
Successful reproduction in female mammals is precisely timed and must be able to withstand the metabolic demand of pregnancy and lactation. We show that kisspeptin-expressing neurons in the arcuate hypothalamus (Kiss1
ARH ) of female mice control the daily timing of food intake, along with the circadian regulation of locomotor activity, sleep, and core body temperature. Toxin-induced silencing of Kiss1ARH neurons shifts wakefulness and food consumption to the light phase and induces weight gain. Toxin-silenced mice are less physically active and have attenuated temperature rhythms. Because the rhythm of the master clock in the suprachiasmatic nucleus (SCN) appears to be intact, we hypothesize that Kiss1ARH neurons signal to neurons downstream of the master clock to modulate the output of the SCN. We conclude that, in addition to their well-established role in regulating fertility, Kiss1ARH neurons are a critical component of the hypothalamic circadian oscillator network that times overt rhythms of physiology and behavior., (Published by Elsevier Ltd.)- Published
- 2019
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19. Sleepmore in Seattle: Later school start times are associated with more sleep and better performance in high school students.
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Dunster GP, de la Iglesia L, Ben-Hamo M, Nave C, Fleischer JG, Panda S, and de la Iglesia HO
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- Analysis of Variance, Humans, Time Factors, Washington, Academic Performance, Schools, Sleep, Students
- Abstract
Most teenagers are chronically sleep deprived. One strategy proposed to lengthen adolescent sleep is to delay secondary school start times. This would allow students to wake up later without shifting their bedtime, which is biologically determined by the circadian clock, resulting in a net increase in sleep. So far, there is no objective quantitative data showing that a single intervention such as delaying the school start time significantly increases daily sleep. The Seattle School District delayed the secondary school start time by nearly an hour. We carried out a pre-/post-research study and show that there was an increase in the daily median sleep duration of 34 min, associated with a 4.5% increase in the median grades of the students and an improvement in attendance.
- Published
- 2018
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20. The Dorsal Medial Habenula Minimally Impacts Circadian Regulation of Locomotor Activity and Sleep.
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Hsu YA, Gile JJ, Perez JG, Morton G, Ben-Hamo M, Turner EE, and de la Iglesia HO
- Subjects
- Animals, Darkness, Depression, Habenula pathology, Light, Locomotion genetics, Mice, Period Circadian Proteins genetics, Period Circadian Proteins metabolism, Photoperiod, Sleep, Sleep, REM, Suprachiasmatic Nucleus physiology, Transcription Factor Brn-3A genetics, Transcription Factor Brn-3A metabolism, Circadian Rhythm genetics, Circadian Rhythm physiology, Habenula physiology, Motor Activity
- Abstract
In nocturnal rodents, voluntary wheel-running activity (WRA) represents a self-reinforcing behavior. We have previously demonstrated that WRA is markedly reduced in mice with a region-specific deletion of the transcription factor Pou4f1 (Brn3a), which leads to an ablation of the dorsal medial habenula (dMHb). The decrease in WRA in these dMHb-lesioned (dMHb
CKO ) mice suggests that the dMHb constitutes a critical center for conveying reinforcement by exercise. However, WRA also represents a prominent output of the circadian system, and the possibility remains that the dMHb is a source of input to the master circadian pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus. To test this hypothesis, we assessed the integrity of the circadian system in dMHbCKO mice. Here we show that the developmental lesion of the dMHb reduces WRA under both a light-dark cycle and constant darkness, increases the circadian period of WRA, but has no effect on the circadian amplitude or period of home cage activity or the daily amplitude of sleep stages, suggesting that the lengthening of period is a result of the decreased WRA in the mutant mice. Polysomnographic sleep recordings show that dMHbCKO mice have an overall unaltered daily amplitude of sleep stages but have fragmented sleep and an overall increase in total rapid eye movement (REM) sleep. Photoresponsiveness is intact in dMHbCKO mice, but compared with control animals, they reentrain faster to a 6-h abrupt phase delay protocol. Circadian changes in WRA of dMHbCKO mice do not appear to emerge within the central pacemaker, as circadian expression of the clock genes Per1 and Per2 within the SCN is normal. We do find some evidence for fragmented sleep and an overall increase in total REM sleep, supporting a model in which the dMHb is part of the neural circuitry encoding motivation and involved in the manifestation of some of the symptoms of depression.- Published
- 2017
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21. Circadian Forced Desynchrony of the Master Clock Leads to Phenotypic Manifestation of Depression in Rats.
- Author
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Ben-Hamo M, Larson TA, Duge LS, Sikkema C, Wilkinson CW, de la Iglesia HO, and González MM
- Subjects
- Animals, Circadian Clocks, Cohort Studies, Depressive Disorder physiopathology, Disease Models, Animal, Exploratory Behavior, Food Preferences, Male, Motor Activity, Phenotype, Rats, Wistar, Saccharin, Sexual Behavior, Animal, Sexual Dysfunctions, Psychological etiology, Swimming, Depressive Disorder etiology, Photoperiod
- Abstract
In mammals, a master circadian clock within the suprachiasmatic nucleus (SCN) of the hypothalamus maintains the phase coherence among a wide array of behavioral and physiological circadian rhythms. Affective disorders are typically associated with disruption of this fine-tuned "internal synchronization," but whether this internal misalignment is part of the physiopathology of mood disorders is not clear. To date, depressive-like behavior in animal models has been induced by methods that fail to specifically target the SCN regulation of internal synchronization as the mode to generate depression. In the rat, exposure to a 22-h light-dark cycle (LD22) leads to the uncoupling of two distinct populations of neuronal oscillators within the SCN. This genetically, neurally, and pharmacologically intact animal model represents a unique opportunity to assess the effect of a systematic challenge to the central circadian pacemaker on phenotypic manifestations of mood disorders. We show that LD22 circadian forced desynchrony in rats induces depressive-like phenotypes including anhedonia, sexual dysfunction, and increased immobility in the forced swim test (FST), as well as changes in the levels and turnover rates of monoamines within the prefrontal cortex. Desynchronized rats show increased FST immobility during the dark (active) phase but decreased immobility during the light (rest) phase, suggesting a decrease in the amplitude of the normal daily oscillation in this behavioral manifestation of depression. Our results support the notion that the prolonged internal misalignment of circadian rhythms induced by environmental challenge to the central circadian pacemaker may constitute part of the etiology of depression.
- Published
- 2017
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22. Differential effects of photoperiod length on depression- and anxiety-like behavior in female and male diurnal spiny mice.
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Ben-Hamo M, Tal K, Paz-Cohen R, Kronfeld-Schor N, and Einat H
- Subjects
- Animals, Choice Behavior physiology, Cohort Studies, Female, Male, Models, Animal, Motivation physiology, Motor Activity physiology, Random Allocation, Reward, Saccharin, Taste Perception physiology, Anxiety physiopathology, Circadian Rhythm physiology, Depression physiopathology, Murinae physiology, Photoperiod, Sex Characteristics
- Abstract
The relationships between biological rhythms and affective disorders are known but their underlying biology not clear. There is difficulty in studying circadian rhythms in humans and appropriate animal models are hard to identify or develop. Some studies show that diurnal rodents can be advantageous model animals for the study of interactions between biological rhythms and affective disorders but previous studies did not include females whereas in humans there are sex differences in affective disorders. The present study tested the effects of short photoperiods in both males and females of the diurnal golden spiny mouse (Acomys russatus). Adult, female and male spiny mice were housed in either neutral photoperiod (12:12 light/dark; NP), or short photoperiod (5:19 light/dark; SP) conditions. After 3weeks acclimatization, animals were tested for spontaneous activity in an open field, elevated plus maze (EPM), sweet solution preference (SSP) and the forced swim test (FST). Both sexes responded to the SP, but while SP males showed increased anxiety-like behavior in the EPM and depression-like behavior in the FST, females showed increased activity, reduced anxiety-like behavior in the EPM, depression-like response in the SSP and no effect in the FST. Differences between sexes were previously demonstrated in behavioral tests that followed a variety of manipulations, and were usually explained in the context of sex hormones. Yet, the current results cannot be compared with previous data from diurnal rodents and further testing of females from other diurnal rodents are needed to explore whether these differences are a general phenomenon or possibly unique to golden spiny mice., (Copyright © 2016 Elsevier Inc. All rights reserved.)
- Published
- 2016
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23. The cutaneous lipid composition of bat wing and tail membranes: a case of convergent evolution with birds.
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Ben-Hamo M, Muñoz-Garcia A, Larrain P, Pinshow B, Korine C, and Williams JB
- Subjects
- Animals, Biological Evolution, Water Loss, Insensible, Birds, Chiroptera, Epidermis chemistry, Lipids chemistry, Wings, Animal physiology
- Abstract
The water vapour permeability barrier of mammals and birds resides in the stratum corneum (SC), the outermost layer of the epidermis. The molar ratio and molecular arrangement of lipid classes in the SC determine the integrity of this barrier. Increased chain length and polarity of ceramides, the most abundant lipid class in mammalian SC, contribute to tighter packing and thus to reduced cutaneous evaporative water loss (CEWL). However, tighter lipid packing also causes low SC hydration, making it brittle, whereas high hydration softens the skin at the cost of increasing CEWL. Cerebrosides are not present in the mammalian SC; their pathological accumulation occurs in Gaucher's disease, which leads to a dramatic increase in CEWL. However, cerebrosides occur normally in the SC of birds. We tested the hypothesis that cerebrosides are also present in the SC of bats, because they are probably necessary to confer pliability to the skin, a quality needed for flight. We examined the SC lipid composition of four sympatric bat species and found that, as in birds, their SC has substantial cerebroside contents, not associated with a pathological state, indicating convergent evolution between bats and birds., (© 2016 The Author(s).)
- Published
- 2016
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24. Metabolic rate, evaporative water loss and thermoregulatory state in four species of bats in the Negev desert.
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Muñoz-Garcia A, Larraín P, Ben-Hamo M, Cruz-Neto A, Williams JB, Pinshow B, and Korine C
- Subjects
- Animals, Body Temperature, Body Weight, Ecosystem, Israel, Respiration, Species Specificity, Basal Metabolism physiology, Body Temperature Regulation physiology, Chiroptera physiology, Desert Climate, Water Loss, Insensible physiology
- Abstract
Life in deserts is challenging for bats because of their relatively high energy and water requirements; nevertheless bats thrive in desert environments. We postulated that bats from desert environments have lower metabolic rates (MR) and total evaporative water loss (TEWL) than their mesic counterparts. To test this idea, we measured MR and TEWL of four species of bats, which inhabit the Negev desert in Israel, one species mainly restricted to hyper-arid deserts (Otonycteris hemprichii), two species from semi-desert areas (Eptesicus bottae and Plecotus christii), and one widespread species (Pipistrellus kuhlii). We also measured separately, in the same individuals, the two components of TEWL, respiratory water loss (RWL) and cutaneous evaporative water loss (CEWL), using a mask. In all the species, MR and TEWL were significantly reduced during torpor, the latter being a consequence of reductions in both RWL and CEWL. Then, we evaluated whether MR and TEWL in bats differ according to their geographic distributions, and whether those rates change with Ta and the use of torpor. We did not find significant differences in MR among species, but we found that TEWL was lowest in the species restricted to desert habitats, intermediate in the semi-desert dwelling species, and highest in the widespread species, perhaps a consequence of adaptation to life in deserts. Our results were supported by a subsequent analysis of data collected from the literature on rates of TEWL for 35 bat species from desert and mesic habitats., (Copyright © 2015 Elsevier Inc. All rights reserved.)
- Published
- 2016
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25. Whole transcriptome profiling of the vernalization process in Lilium longiflorum (cultivar White Heaven) bulbs.
- Author
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Villacorta-Martin C, Núñez de Cáceres González FF, de Haan J, Huijben K, Passarinho P, Lugassi-Ben Hamo M, and Zaccai M
- Subjects
- Cold Temperature, Epigenesis, Genetic, Flowers genetics, Gene Expression Regulation, Developmental, Gene Expression Regulation, Plant, Gene Ontology, Lilium physiology, Molecular Sequence Annotation, Flowers growth & development, Gene Expression Profiling methods, Genes, Plant, Lilium genetics
- Abstract
Background: Vernalization is an obligatory requirement of extended exposure to low temperatures to induce flowering in certain plants. It is the most important factor affecting flowering time and quality in Easter lily (Lilium longiflorum). Exposing the bulbs to 4 °C gradually decreases flowering time up to 50% compared to non-vernalized plants. We aim to understand the molecular regulation of vernalization in Easter lily, for which we characterized the global expression in lily bulb meristems after 0, 2, 5, 7 and 9 weeks of incubation at 4 °C., Results: We assembled de-novo a transcriptome which, after filtering, yielded 121,572 transcripts and 42,430 genes which hold 15,414 annotated genes, with up to 3,657 GO terms. This extensive annotation was mapped to the more general GO slim plant with a total of 94 terms. The response to cold exposure was summarized in 6 expression clusters, providing useful patterns for dissecting the dynamics of vernalization in lily. The functional annotation (GO and GO slim plant) was used to group transcripts in gene sets. Analysis of these gene sets and profiles revealed that most of the enriched functions among genes up-regulated by cold exposure were related to epigenetic processes and chromatin remodeling. Candidate vernalization genes in lily were selected based on their sequence similarity to known regulators of flowering in other species., Conclusions: We present a detailed analysis of gene expression dynamics during vernalization in Lilium, covering several time points and accounting for biological variation by the use of replicates. The resulting collection of transcripts and novel isoforms provides a useful resource for studying the changes occurring during vernalization at a fine level. The selected potential candidate genes can shed light on the regulation of this process.
- Published
- 2015
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26. Characterization of expressed sequence tags from Lilium longiflorum in vernalized and non-vernalized bulbs.
- Author
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Lugassi-Ben Hamo M, Martin CV, and Zaccai M
- Subjects
- DNA, Complementary genetics, Flowers genetics, Flowers physiology, Gene Expression Profiling, Gene Expression Regulation, Plant, Lilium physiology, Meristem genetics, Meristem physiology, Molecular Sequence Annotation, Phylogeny, Plant Roots genetics, Plant Roots physiology, Plant Stems genetics, Plant Stems physiology, Sequence Analysis, DNA, Subtractive Hybridization Techniques, Expressed Sequence Tags, Lilium genetics, Plant Proteins genetics
- Abstract
In Lilium longiflorum, vernalization is both an obligatory requirement and the major factor affecting flowering time, however, little is known about the molecular regulation of this mechanism in Lilium and other flowering bulbs. Exposure of L. longiflorum bulbs to 9 weeks at 4°C greatly promoted stem elongation within the bulb, floral transition and flowering. Subtraction libraries of vernalized (V) and non-vernalized (NV) bulb meristems were constructed. 671 and 479 genes were sequenced, from which 72 and 82 proteins were inferred for the NV-V and the V-NV libraries, respectively. Much lower transcription levels and putative gene functions were recorded in the NV-V libraries compared the V-NV libraries. However, a large number of genes annotated to transposable elements (TEs), represented more than 20% of the sequenced cDNA were expressed in the NV-V libraries, as opposed to less than 2% in the V-NV libraries. The expression profile of several genes potentially involved in the vernalization pathway was assessed. Expression of LlSOC1, the lily homologue of SUPPRESSOR OF OVER-EXPRESSION OF CO1 (SOC1), an important flowering gene in several plant species, found in the V-NV library, was highly up-regulated during bulb meristem cold exposure. The subtraction libraries provided a fast tool for relevant gene isolation., (Copyright © 2014 Elsevier GmbH. All rights reserved.)
- Published
- 2015
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27. Ambient temperature and nutritional stress influence fatty acid composition of structural and fuel lipids in Japanese quail (Coturnix japonica) tissues.
- Author
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Ben-Hamo M, McCue MD, Khozin-Goldberg I, McWilliams SR, and Pinshow B
- Subjects
- Adipose Tissue metabolism, Animals, Lipid Metabolism, Malnutrition physiopathology, Myocardium metabolism, Organ Specificity, Phospholipids metabolism, Stress, Physiological, Coturnix metabolism, Fatty Acids metabolism, Malnutrition metabolism
- Abstract
In birds, fatty acids (FA) serve as the primary metabolic fuel during exercise and fasting, and their composition affects metabolic rate and thus energy requirements. To ascertain the relationship between FAs and metabolic rate, a distinction should be made between structural and fuel lipids. Indeed, increased unsaturation of structural lipid FAs brings about increased cell metabolism, and changes in the FA composition of fuel lipids affects metabolic rate through selective mobilization and increasing availability of specific FAs. We examined the effects of acclimation to a low ambient temperature (Ta: 12.7±3.0°C) and nutritional status (fed or unfed) on the FA composition of four tissues in Japanese quail, Coturnix japonica. Differentiating between neutral (triglycerides) and polar (phospholipids) lipids, we tested the hypothesis that both acclimation to low Ta and nutritional status modify FA composition of triglycerides and phospholipids. We found that both factors affect FA composition of triglycerides, but not the composition of phospholipids. We also found changes in liver triacylglyceride FA composition in the low-Ta acclimated quail, namely, the two FAs that differed, oleic acid (18:1) and arachidonic acid (20:4), were associated with thermoregulation. In addition, the FAs that changed with nutritional status were all reported to be involved in regulation of glucose metabolism, and thus we suggest that they also play a role in the response to fasting., (Copyright © 2013 Elsevier Inc. All rights reserved.)
- Published
- 2013
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28. Waking to drink: rates of evaporative water loss determine arousal frequency in hibernating bats.
- Author
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Ben-Hamo M, Muñoz-Garcia A, Williams JB, Korine C, and Pinshow B
- Subjects
- Animals, Female, Humidity, Time Factors, Weight Loss physiology, Chiroptera physiology, Drinking Behavior physiology, Hibernation physiology, Wakefulness physiology, Water Loss, Insensible physiology
- Abstract
Bats hibernate to cope with low ambient temperatures (T(a)) and low food availability during winter. However, hibernation is frequently interrupted by arousals, when bats increase body temperature (T(b)) and metabolic rate (MR) to normothermic levels. Arousals account for more than 85% of a bat's winter energy expenditure. This has been associated with variation in T(b), T(a) or both, leading to a single testable prediction, i.e. that torpor bout length (TBL) is negatively correlated with T(a) and T(b). T(a) and T(b) were both found to be correlated with TBL, but correlations alone cannot establish a causal link between arousal and T(b) or T(a). Because hydration state has also been implicated in arousals from hibernation, we hypothesized that water loss during hibernation creates the need in bats to arouse to drink. We measured TBL of bats (Pipistrellus kuhlii) at the same T(a) but under different conditions of humidity, and found an inverse relationship between TBL and total evaporative water loss, independent of metabolic rate, which directly supports the hypothesis that hydration state is a cue to arousal in bats.
- Published
- 2013
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29. The relationship between cutaneous water loss and thermoregulatory state in Kuhl's pipistrelle Pipistrellus kuhlii, a Vespertillionid bat.
- Author
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Muñoz-Garcia A, Ben-Hamo M, Pinshow B, Williams JB, and Korine C
- Subjects
- Animals, Basal Metabolism, Body Water metabolism, Israel, Oxygen Consumption, Chiroptera physiology, Hibernation, Water Loss, Insensible
- Abstract
Total evaporative water loss is the sum of respiratory water loss (RWL) and cutaneous water loss (CWL) and constitutes the main avenue of water loss in bats. Because bats fly and have large surface-to-volume ratios, they potentially have high rates of RWL and CWL. Most species of small insectivorous bats have the ability to reduce their body temperature (T(b)) at rest, which substantially reduces energy expenditure and water loss. We hypothesized that bats reduce evaporative water loss during bouts of deep hypothermia (torpor) by decreasing RWL and CWL. We measured T(b), RWL, CWL, and resting metabolic rate (RMR) in Kuhl's pipistrelle Pipistrellus kuhlii, a small insectivorous bat. In support of our hypothesis, we found that RWL decreased with decreasing RMR. We found that CWL was lower in torpid individuals than in normothermic bats; however, bats in deep torpor had similar or higher CWL than bats in shallow torpor, suggesting that they exert a less effective physiological control over CWL when in deep torpor. Because insectivorous bats spend most of their lives in torpor or hibernation, the regulation of CWL in different heterothermic states has relevant ecological and evolutionary consequences.
- Published
- 2012
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30. Dietary fatty acid composition influences tissue lipid profiles and regulation of body temperature in Japanese quail.
- Author
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Ben-Hamo M, McCue MD, McWilliams SR, and Pinshow B
- Subjects
- Animals, Arachidonic Acid pharmacology, Basal Metabolism drug effects, Circadian Rhythm drug effects, Coconut Oil, Coturnix, Fatty Acids pharmacology, Fatty Acids, Monounsaturated pharmacology, Female, Male, Oleic Acid physiology, Plant Oils pharmacology, Rapeseed Oil, Body Temperature Regulation drug effects, Dietary Fats pharmacology, Lipid Metabolism drug effects
- Abstract
Many avian species reduce their body temperature (T(b)) to conserve energy during periods of inactivity, and we recently characterized how ambient temperature (T(a)) and nutritional stress interact with one another to influence physiologically controlled hypothermic responses in Japanese quail (Coturnix japonica). In the present study, we examined how the fatty acid (FA) composition of the diet influences the FA composition of phospholipids in major organs and how these affect controlled hypothermic responses and metabolic rates in fasted birds. For 5 weeks prior to fasting, quail were fed a standard diet and gavaged each morning with 0.7 ml of water (control), or a vegetable oil comprising saturated fatty acids (SFA; coconut oil), or unsaturated fatty acids (UFA; canola oil). Birds were then fasted for 4 days at a T(a) of 15°C. We found that, while fasting, both photophase and scotophase T(b) decreased significantly more in the SFA treatment group than in the control group; apparently the former down-regulated their T(b) set point. This deeper hypothermic response was correlated with changes in the phospholipid composition of the skeletal muscle and liver, which contained significantly more oleic acid (18:1) and less arachidonic acid (20:4), respectively. Our data imply that these two FAs may be associated with thermoregulation.
- Published
- 2011
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31. Fasting triggers hypothermia, and ambient temperature modulates its depth in Japanese quail Coturnix japonica.
- Author
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Ben-Hamo M, Pinshow B, McCue MD, McWilliams SR, and Bauchinger U
- Subjects
- Animals, Bird Diseases etiology, Bird Diseases pathology, Bird Diseases physiopathology, Body Temperature Regulation physiology, Body Weight, Coturnix anatomy & histology, Energy Metabolism, Fasting physiology, Female, Hypothermia etiology, Hypothermia pathology, Hypothermia physiopathology, Hypothermia veterinary, Male, Models, Biological, Temperature, Coturnix physiology
- Abstract
We tested three hypotheses regarding the cues that elicit facultative hypothermia in Japanese quail (Coturnix japonica): H(1)) Ambient temperature (T(a)), alone, influences the onset and depth of hypothermia; H(2)) Fasting, alone, influences the onset and depth of hypothermia; H(3)) T(a) acts synergistically with fasting to shape the use of hypothermia. Eight quail were maintained within their thermoneutral zone (TNZ) at 32.6+/-0.2 degrees C, and eight below their lower critical temperature (T(lc)) at 12.7+/-3.0 degrees C. All quail entered hypothermia upon food deprivation, even quail kept within their TNZ. Body temperature (T(b)) decreased more (38.36+/-0.53 degrees C vs. 39.57+/-0.57 degrees C), body mass (m(b)) loss was greater (21.0+/-7.20 g vs.12.8+/-2.62g), and the energy saved by using hypothermia was greater (25.18-45.01% vs. 7.98-28.06%) in low the T(a) treatment than in TNZ treatment. Interestingly, the depth of hypothermia was positively correlated with m(b) loss in the low T(a) treatment, but not in TNZ treatment. Our data support H(3), that both thermoregulatory costs and body energy reserves are proximate cues for entry into hypothermia in quail. This outcome is not surprising below the T(lc). However, the quail kept at their TNZ also responded to food deprivation by entering hypothermia with no apparent dependence on m(b) loss. Therefore inputs, other than thermoregulatory costs and body condition, must serve as cues to enter hypothermia. Consequently, we address the role that tissue sparing may play in the physiological 'decision' to employ hypothermia., (Copyright 2009 Elsevier Inc. All rights reserved.)
- Published
- 2010
- Full Text
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