Oxidative and osmotolerant effects in Salvator merianae (Squamata: Teiidae) red blood cells during hibernation / Efeitos de oxidação e osmotolerância dos eritrócitos de Salvator merianae (Squamata: Teiidae) durante a hibernação

Abstract Hibernation is a natural condition of animals that lives in the temperate zone, although some tropical lizards also experience hibernation annually, such as the lizard native from South America, Salvator merianae, or "tegu" lizard. Even though physiological and metabolic characteristic associated with hibernation have been extensively studied, possible alterations in the red blood cells (RBC) integrity during this period remains unclear. Dehydration and fasting are natural consequences of hibernating for several months and it could be related to some cellular modifications. In this study, we investigated if the osmotic tolerance of RBCs of tegu lizard under hibernation is different from the cells obtained from animals while normal activity. Additionally, we indirectly investigated if the RBCs membrane of hibernating tegus could be associated with oxidation by quantifying oxidized biomolecules and the activity of antioxidant enzymes. Our findings suggest that RBCs are more fragile during the hibernation period, although we did not find evidence of an oxidative stress scenario associated with the accentuated fragility. Even though we did not exclude the possibility of oxidative damage during hibernation, we suggested that an increased RBCs volume as a consequence of hypoosmotic blood during hibernation could also affect RBCs integrity as noted.

Resumo A hibernação é uma condição natural dos animais que vivem na zona temperada, embora alguns lagartos tropicais também experenciem hibernação anualmente, como é o caso do lagarto nativo da América do Sul, Salvator merianae ou "teiú". Embora as características fisiológicas e metabólicas associadas à hibernação tenham sido amplamente estudadas, possíveis alterações na integridade das hemácias durante esse período ainda permanecem obscuras. A desidratação e o jejum são consequências naturais da hibernação por vários meses e podem estar relacionadas a algumas modificações celulares. Neste estudo, investigamos se a tolerância osmótica de hemácias do lagarto teiú sob hibernação são diferentes das células obtidas de animais em atividade normal. Além disso, investigamos indiretamente por meio da quantificação de biomoléculas oxidadas e da atividade de enzimas antioxidantes se a membrana das hemácias dos teiús em hibernação poderia estar associada à oxidação. Nossos resultados sugerem que as hemácias possuem maior fragilidade durante o período de hibernação, embora não tenhamos encontrado evidências de um cenário de estresse oxidativo associado à essa fragilidade acentuada. Embora não tenhamos excluído a possibilidade de dano oxidativo durante a hibernação, sugerimos que um aumento no volume das hemácias como consequência de sangue hipoosmótico durante a hibernação também poderia afetar a integridade de hemácias, tal como foi observado.

Adult Stem Cells in Hibernation: Future Perspectives of Space Travel

Space traveling is imperative for mankind in the future. Expectedly, hibernation will become an option for space traveler to overcome the endless voyage. With regard to some of the studies pointed out that during hibernation, muscle will undergo atrophy and meantime neurogenesis will reduce, these obstacles were frequently related with stem cell regeneration. Thus, investigation on whether hibernation will lead to dysfunction of stem cell becomes an important issue. By going through four main systems in this article, such as, hematopoietic system, skeletal muscle system, central nervous system and orthopedic system, we are expecting that stem cells regeneration capacity will be affected by hibernation. To date, these researches are majorly the read-out from short term or seasonal hibernating mammals. Proposing and creating a simulated long-term hibernation animal model is turning essential for the further investigation on the effect of longer period of hibernation to human stem cells.

Effects of 17β-E2 on growth and gonad development of overwintering Whitmania pigra / 中国中药杂志

The present study was conducted to explores the effects of short-term addition of 17β-E2 on the growth,gonad development and internal quality of overwintering Whitmania pigra. Before overwintering,0. 0,1. 0,10. 0,25. 0,50. 0,100. 0 μg·L~(-1) of 17β-E2 were added to the aquaculture water for 6 weeks and then hibernated for 60 days. The changes of growth performance,gonad index,morphological structure of spermary( ovary),endogenous steroid hormones level and internal quality were measured. The results showed that the body weight,weight gain rate,specific growth rate,female gonad index,oocyte development and endogenous estrogen level of the leech increased first and then decreased with the increase of the concentration of exogenous 17β-E2,which were higher than those of the control group. The body weight,weight gain rate and specific growth rate of the leech at the concentration of 25 μg·L~(-1)17β-E2 were significantly higher than those of the other groups( P<0. 05),oocyte development and endogenous estrogen levels were significantly higher than those of other groups at the concentration of 50 μg·L~(-1)( P<0. 05). When the concentration of exogenous 17β-E2 was higher than 50 μg·L~(-1),the levels of male gonad index,spermatocyte development,endogenous androgen and progesterone were significantly inhibited( P< 0. 05). There was no significant difference in endogenous corticosteroid levels among the groups. In conclusion,short-term addition of exogenous 17β-E2 of 10-25 μg·L~(-1) could promote the growth of overwintering leeches,oocyte development and antithrombin activity without inhibiting the development of male gonads.

Isquemia miocárdica: conceptos básicos, diagnóstico e implicaciones clínicas. Tercera parte / Myocardial ischemia: basic concepts, diagnosis and clinical implications. Part three

Resumen El término «cardiopatía isquémica¼ se refiere a la disfunción del ventrículo izquierdo secundaria a infarto del miocardio, miocardio isquémico viable o enfermedad coronaria severa documentada por arteriografía coronaria, la cual tiene un pobre pronóstico, con una supervivencia del 45% a 5 años. El tratamiento de la cardiopatía isquémica involucra la estimación de la viabilidad en el miocardio afectado para determinar si la revascularización puede generar una remodelación positiva que mejore la función del ventrículo izquierdo. Existen cuatro modalidades básicas usadas en la práctica clínica para calcular la viabilidad miocárdica: tomografía de emisión simple de positrones, tomografía por emisión de positrones, ecocardiograma estrés y resonancia magnética cardiaca. Hoy en día hay estudios que demuestran que la terapia médica mejora la función del ventrículo izquierdo en la cardiopatía isquémica, independiente de la presencia o no de viabilidad o de la revascularización miocárdica; por tanto es posible que otros factores como la cantidad de remodelado, los volúmenes del ventrículo izquierdo, la insuficiencia mitral y la fracción de eyección puedan afectar también los desenlaces. Se requiere definir de manera clara los estadios del remodelado ventricular izquierdo en los cuales la presencia de viabilidad es benéfica y las etapas en las que el remodelado es reversible con la revascularización miocárdica. En cuanto a los métodos para determinar la viabilidad, la resonancia magnética parece dar más respuestas al respecto, ya que puede aportar información adicional relacionada con dimensiones del ventrículo izquierdo, fracción de eyección, fibrosis miocárdica y anormalidades valvulares.

Abstract The term myocardial ischemia refers to a left ventricular dysfunction secondary to a myocardial infarction, viable ischemic myocardium or sever coronary disease documented by means of a coronary angiography, which has a poor prognosis, with five-year survival rate of 45%. Management of myocardial ischemia involves estimating viability of the affected myocardium in order to determine whether revascularization can generate a positive remodelling that improves left ventricle functioning. Four different basic modalities are used in clinical practice to assess myocardial viability: single-photon emission computed tomography, positron emission tomography, stress echocardiogram and cardiac magnetic resonance. Nowadays there are studies that have shown medical therapy improves left ventricle function in ischemic heart disease, regardless of the presence or not of the viability or the myocardial revascularization; therefore, it is possible that other factors such as the amount of remodelling, the left ventricle volumes, mitral insufficiency and ejection fraction could also afffect the outcomes. A clear definition of the left ventricle remodelling states where the presence of viability is beneficial and the stages where the remodelling is reversible with myocardial revascularization is required. With regards to methods for assessing viability, magnetic resonance seems to provide more answers, as it can give additional information related to the dimensions of the left ventricle, ejection fraction, myocardial fibrosis and valvular abnormalities.

Isquemia miocárdica: conceptos básicos, diagnóstico e implicaciones clínicas. Segunda parte / Myocardial ischemia: basic concepts, diagnosis and clinical implications. Part two

Resumen La isquemia miocárdica puede ser irreversible o reversible dependiendo de diferentes factores moleculares y fisiológicos. En la isquemia miocárdica irreversible se presentan tres tipos de muerte celular a nivel miocárdico: la necrosis, la apoptosis y la autofagia; mientras en la isquemia reversible la restauración de la función de los miocitos está determinada por factores como el restablecimiento temprano del flujo sanguíneo coronario y fenómenos de pre y posacondicionamiento isquémico. Conceptos como el miocardio aturdido (disfunción mecánica temporal luego de una lesión isquémica pero con flujo sanguíneo normal en ausencia de cualquier lesión irreversible) y el miocardio hibernante (región miocárdica viable, sin contractilidad) son formas quiescentes de la función cardiaca y explican un poco la capacidad del miocardio de restablecer su funcionamiento normal luego de un episodio de isquemia.

Abstract Myocardial ischemia can be irreversible or reversible depending on multiple molecular and physiological factors. In irreversible myocardial ischemia there are three types of cell death on a myocardial level: necrosis, apoptosis and autophagy; whereas in reversible ischemia the restoration of the myocytes is determined by factors such as early recovery of coronary blood flow and pre- and postischemic conditioning phenomena. Concepts such as stunned myocardium (temporary mechanical dysfunction following an ischemic episode but with normal blood flow and without irreversible damage) and hibernating myocardium (viable myocardial region without contractility) are quiescent forms of the cardiac function and explain the ability of the myocardium to resume its normal functioning after an ischemic episode.

Temporal distribution of tuberculosis in the State of Amazonas, Brazil

Tuberculosis (TB) is one of the infectious diseases that contributes most to the morbidity and mortality of millions of people worldwide. Brazil is one of 22 countries that accounts for 80% of the tuberculosis global burden. The highest incidence rates in Brazil occur in the States of Amazonas and Rio de Janeiro. The aim of this study was to describe the temporal distribution of TB in the State of Amazonas. Between 2001 and 2011, 28,198 cases of tuberculosis were reported in Amazonas, distributed among 62 municipalities, with the capital Manaus reporting the highest (68.7%) concentration of cases. Tuberculosis was more prevalent among males (59.3%) aged 15 to 34 years old (45.5%), whose race/color was predominantly pardo (64.7%) and who had pulmonary TB (84.3%). During this period, 81 cases of multidrug-resistant TB were registered, of which the highest concentration was reported from 2008 onward (p = 0.002). The municipalities with the largest numbers of indigenous individuals affected were São Gabriel da Cachoeira (93%), Itamarati (78.1%), and Santa Isabel do Rio Negro (70.1%). The future outlook for this region includes strengthening the TB control at the primary care level, by expanding diagnostic capabilities, access to treatment, research projects developed in collaboration with the Dr. Heitor Vieira Dourado Tropical Medicine Foundation .;Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD).; and financing institutions, such as the project for the expansion of the Clinical Research Center and the creation of a hospital ward for individuals with transmissible respiratory diseases, including TB.

Biochemical adaptations of mammalian hibernation: exploring squirrels as a perspective model for naturally induced reversible insulin resistance

An important disease among human metabolic disorders is type 2 diabetes mellitus. This disorder involves multiple physiological defects that result from high blood glucose content and eventually lead to the onset of insulin resistance. The combination of insulin resistance, increased glucose production, and decreased insulin secretion creates a diabetic metabolic environment that leads to a lifetime of management. Appropriate models are critical for the success of research. As such, a unique model providing insight into the mechanisms of reversible insulin resistance is mammalian hibernation. Hibernators, such as ground squirrels and bats, are excellent examples of animals exhibiting reversible insulin resistance, for which a rapid increase in body weight is required prior to entry into dormancy. Hibernator studies have shown differential regulation of specific molecular pathways involved in reversible resistance to insulin. The present review focuses on this growing area of research and the molecular mechanisms that regulate glucose homeostasis, and explores the roles of the Akt signaling pathway during hibernation. Here, we propose a link between hibernation, a well-documented response to periods of environmental stress, and reversible insulin resistance, potentially facilitated by key alterations in the Akt signaling network, PPAR-γ/PGC-1α regulation, and non-coding RNA expression. Coincidentally, many of the same pathways are frequently found to be dysregulated during insulin resistance in human type 2 diabetes. Hence, the molecular networks that may regulate reversible insulin resistance in hibernating mammals represent a novel approach by providing insight into medical treatment of insulin resistance in humans.

Argentaffine Cells in the Digestive Tract of Hibernating and Non-hibernating in Chinese Fire-bellied Newt (Cynops orientalis) / Celulas Argentafines en el Tracto Digestivo del Tritón de Vientre de Fuego Chino (Cynops orientalis) en Periódos de Hibernación y No Hibernación

In order to further studying the relationship between the gastrointestinal endocrine cells and the hibernation of Chinese fire-bellied newt, histological techniques were used in this study to explore the distributed density and morphology of argentaffine cells in the digestive tract during hibernation and non-hibernation. The argentaffine cells could be observed throughout the digestive tract of Chinese fire-bellied newt during hibernation and non-hibernation and mainly distributed in the acinar epithelial cells, epithelial cells and intrinsic membrane. They had appeared in the shape of goblet, pyramid, ellipse, round, cone-shaped, spindle-shaped. The cytoplasm contains secretory granules at the basal regions with spherical nuclei in the basal regions. Most of them had processes in different directions, suggesting that the argentaffine cells have combined the function of endocrine and exocrine. The distribution density curves of argentaffine cells were generally wavelike during the two periods. It was highest in the body of stomach in hibernation, while in non-hibernation it was highest in the pyloric. Totally the density of argentaffine cells was higher in hibernation period than that in non-hibernation period. The results showed that the activity of the digestive tract was expectedly weakened during the hibernation, but the function of endocrine was actually strengthened.

Con el fin de promover el estudio de la relación entre las células endocrinas gastrointestinales y la hibernación del tritón vientre de fuego chino, fueron utilizados técnicas histológicas para explorar la densidad de distribuición y la morfología de las células argentafines en el tracto digestivo durante la hibernación y la no hibernación. Las células argentafines pudieron ser observadas en todo el tracto digestivo de tritón vientre de fuego chino durante la hibernación y no hibernación, y se distribuyeron principalmente en las células epiteliales acinares, células epiteliales y la membrana intrínseca. Aparecieron de forma caliciforme, piramidal, elíptica, redonda, cónica y de huso. El citoplasma contenía gránulos de secreción en las regiones basales con núcleos esféricos en esa región. La mayoría de ellos tenía procesos en diferentes direcciones, lo que sugiere que las células argentafines combinaron la función del sistema endocrino y exocrino. Las curvas de densidad de distribución de las células argentafines fueron generalmente ondulante durante los dos períodos. Esta fue más alta en el cuerpo del estómago en estado de hibernación, mientras que en la no hibernación fue mayor en el píloro. En total, la densidad de las células argentafines era mayor en el periodo de hibernación. Los resultados mostraron que la actividad del tracto digestivo se debilitó, como era de esperar, durante la hibernación, pero la función del sistema endocrino se fortaleció.

Winter prevalence of obligate aphid pathogen Pandora neoaphidis mycosis in the host Myzus persicae populations in southern China: modeling description and biocontrol implication

Pandora neoaphidis overwintering had been investigated by monitoring its prevalence in Myzus persicae populations in open fields. Cabbage plants in field plots were weekly taken after mycosis initiation, to count and examine the living and dead aphids infected by P. neoaphidis. Based on the field data, infection levels (I) varied with field temperature (T), relative humidity (RH) and aphid count (numbers of living aphids per plant, N) over days (D), fitting well to the modified logistic equation I=0.91/[1+exp(8.5+(2.0H T H RH-20.2NI0)D)] (r²=0.897), where H T indicated daily hours of low temperature (<4°C), H RH daily hours of high air humidity (>90% RH) and I0 primary infection level. The model demonstrated the abiotic and biotic factors influencing P. neoaphidis mycosis development in winter, and also verifies the fungal overwintering by infecting available host aphids without a resting stage. Ultimately, P. neoaphidis mycosis reduced 81.4% of aphid populations, presenting great potential for biocontrol.

Bone marrow stem cell mobilization to the peripheral blood and tumor necrosis factor-alpha expression in ischemic myocardium in rabbit models of hibernating myocardium / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the changes in peripheral blood bone marrow stem cells and tumor necrosis factor-alpha gene expression in the ischemic myocardium in rabbit models of hibernating myocardium.</p><p><b>METHODS</b>Twenty-four male Japanese white rabbits were randomized into 4 groups, including a sham-operated group and 3 model groups with hibernating myocardium induced by partial ligation of the left anterior descending coronary artery. The percentage of CD34-positive cells in the peripheral blood was evaluated by flow cytometry, and TNF-alpha mRNA expression in the ischemic myocardium was determined by real-time RT-PCR in the 3 model groups (at 3, 7, or 28 days after the operation) and in the sham-operated group.</p><p><b>RESULTS</b>In rabbits with partial ligation of the left anterior descending coronary artery, the percentage of CD34-positive cells in the peripheral blood and myocardial TNF-alpha mRNA expression were significantly increased at 3 and 7 days after the operation in comparison with those in the sham-operated group and those at 28 days postoperatively (P<0.01). No significant differences were found in the percentage of CD34 positive cells or myocardial TNF-alpha mRNA expression between the sham-operated group and the rabbits 28 days after the coronary artery ligation (P>0.05).</p><p><b>CONCLUSION</b>Bone marrow stem cell can be mobilized into the peripheral blood in rabbit hibernating myocardium model possibly by increasing TNF-alpha gene expression in the ischemic myocardium.</p>

Effects of Zinc and Hypothermic Process during the Light and Dark Adaptation of Vertebrate Retina

PURPOSE: The purpose of this study was to clarify the effects of zinc treatment and hypothermia on visual adaptation and visual sensitivity in bullfrogs (Rana catesbeiana), which are poikilothermal animals capable of adjusting quickly to environmental temperature changes. METHODS: The effects of both zinc treatment and hypothermia on visual sensitivity were studied by using electroretinogram (ERG) recording and absorption spectra scanning before and after zinc and TSQ (N-[6-methoxy-8-quinolyl]-p-toluene sulfonamide) treatment, with or without temperature changes. RESULTS: In spite of malnutrition due to hibernation, the optimal zinc concentration effect was obtained at 10-4 M (10-2 M 200 microliter ZnCl2 in 20 microliter Ringer's solution) according to ERG recording. After zinc treatment and hypothermia induction, increments of all ERG components and thresholds were taken by ERG recording. These results showed that both zinc treatment and hypothermia may increase visual sensitivity during visual adaptation. In spectral scans, the absorbance increment due to zinc treatment and hypothermia was shown over the whole spectral range (400~750 nm), and it was especially prominent at alpha-peak (about 500 nm). In addition, there was a decrease in absorption differences between dark adaptation and light adaptation after zinc treatment. Furthermore, according to the visual sensitivity decrement using TSQ as a zinc specific chelator, this visual sensitivity increase was shown to be caused by zinc. CONCLUSIONS: As the results suggest, both zinc treatment and hypothermic effects may improve visual sensitivity by promoting rhodopsin regeneration and inhibiting rhodopsin bleaching induced by light illumination. Zinc may activate the enzyme activity of retinol dehydrogenase and phosphodiesterase, while hypothermic effects may improve precursor transport, which is required for rhodopsin regeneration, by tightening membrane adhesion between retinas and retinal pigment epithelia. In addition, we believe that zinc treatment and hypothermic effects may work synergistically to accelerate visual sensitivity during visual adaptation.

Seasonal abundance and mortality of Oebalus poecilus (Dallas) (Hemiptera: Pentatomidae) in a hibernation refuge

Oebalus poecilus (Dallas) é praga importante do arroz irrigado no Rio Grande do Sul, Brasil. Este inseto hiberna durante os meses mais frios em refúgios como o folhedo de bambu. Este estudo objetivou elucidar a hibernação de O. poecilus e determinar as causas de mortalidade durante este período. O estudo foi realizado em um bambuzal com cerca de 140 m2, situado em área orizícola, em Eldorado do Sul (30° 02’ S e 51° 23’ W), RS. De junho/2000 à abril/2002, foram realizadas 63 amostragens de folhedo, em intervalos semanais ou quinzenais e o número de percevejos registrado em laboratório. A entrada no refúgio de hibernação (folhedo de bambu) iniciou na primeira semana de março, completando-se no início de maio. O. poecilus abandonou o refúgio da metade de outubro até o final de dezembro. O parasitismo por mosca (taquinídeos) e o fungo Beauveria bassiana (Bals.) Vuill. foram os principais fatores de mortalidade.

Assessment of Myocardial Viability Using PET / 대한핵의학회잡지

The potential for recovery of left ventricular dysfunction after myocardial revascularization represents a practical clinical definition for myocardial viability. The evaluation of viable myocardium in patients with severe global left ventricular dysfunction due to coronary artery disease and with regional dysfunction after acute myocardial infarction is an important issue whether left ventricular dysfunction may be reversible or irreversible after therapy. If the dysfunction is due to stunning or hibernation, functional improvement is observed. but stunned myocardium may recover of dysfunction with no revascularization. Hibernation is chronic process due to chronic reduction in the resting myocardial blood flow. There are two types of myocardial hibernation: "functional hibernation" with preserved contractile reserve and "structural hibernation" without contractile reserve in segments with preserved glucose metabolism. This review focus on the application of F-18 FDG and other radionuclides to evaluate myocardial viability. In addition the factors influencing predictive value of FDG imaging for evaluating viability and the different criteria for viability are also reviewed.

Glycoconjugates of the Duodenal Mucosa in Cold-treated Chipmunks / 체질인류학회지

To investigate changes of glycoconjugates (GC) on the duodenal mucosa of Korean chipmunks (Tamias sibiricus) after cold-treatment, chipmunks were maintained in cold conditions (6 C) for 3, 5 or 9 months in an attempt to mimic conditions occurring during seasonal hibernation. Most chipmunks were active as before until 3 months in the cold room and since then were hibernated. Although there was significant decrease in neutral GC in cold-treated chipmunks compared with warm chipmunks, acid GC changed little. As for histochemical properties of acid GC in the duodenum, the cold-treated chipmunk showed some differences, such as appearance of villus goblet cells which contained the mixture of sulfated and nonsulfated GC. The affinities for all lectins used in this study were shown in the columnar cells of the duodenal villus and crypt, more intensive DBA, SBA, PNA, BSL-1, RCA-1 and sWGA affinities were demonstrated in the Golgi zone of columnar cells. These affinities decreased in the cold-treated groups, especially in the Golgi zone of columnar cells. The affinities with DBA, RCA-1, sWGA and BSL-1 was demonstrated in the goblet cells of the duodenum, but these affinities except DBA decreased in the cold-treated chipmunks. All lectin affinities except UEA-1 detected in duodenal gland, but cold-treatment induced a decrease of these affinities. The changes in amount and properties of GC in the present experimental model for hibernation may be due to the different intestinal environment associated with food intake. However, the present experimental model for hibernation, especially 9 months cold-treated chipmunks, stills need to be demonstrated during seasonal hibernation in the wild.

Characterization of the imaginal reproductive diapause of Oebalus poecilus (Dallas) (Hemiptera: Pentatomidae)

The state of development of the internal reproductive organs of male and female Oebalus poecilus (Dallas) as well as the body fat amount in the abdominal cavity during hibernation, of individuals sampled in bamboo litter in Eldorado do Sul (30º02'S and 51º23'W), RS, Brazil was investigated. Females and males showed the abdominal cavity filled with body fat in the beginning of the hibernation phase. The decrease in fat reserve level occurred from August on for males and from October on for females. Ovaries and testis doubled in length and tripled in width from immature to the reproductive phase. Male sexual maturation occurred in the hibernation sites while for females it occurred later on outside of the sites. Reproductive organ immaturity and abdominal body fat hypertrophy characterized the diapause of O. poecilus.

Effect of temperature on the heart function of the five-strip eyebrow squirrel / 生物医学工程学杂志

This is an in vitro study designed to assess the effect of temperature variation on the heart function of the five-strip eyebrow squirrel--amammal of the hibernating kind. A heart model of exsomatizing action and for determining the physiological parameters with four physiological recorders was used to measure the LVSP, LVEDP and (+/- dP/dtmax), respectively. It was found that the curves of the squirrel's heart mechanics property in relation to temperature variation are similar to the curves of the non-hibernating animals'. But, the squirrels' heart contraction function changes with in a much wider range, suggesting that their hearts are more tolerant of temperature variation.

Comparative study for some physiological parameters in the three species of the snakes from different regions of Egypt during the hibernation

The aim of this study was to compare some physiological parameters in three species of snakes [Psammophis schokari aegyptius [from Aswan], Psammophis schokari schokari [from Al-Wahat] and Psammophis sibilans sibilans [from Mansoura]] during the winter. Physiological parameters including thyroid hormones [T3 and T4], thyroid stimulating hormone [TSH], insulin hormone, calcium, iron, sodium, potassium and cholesterol, were recorded in the three species of the snakes. The results showed that serum TSH, T4, insulin hormones and iron were lower in the serum of Psammophis schokari aegyptius than the other two species. Conversely, all other parameters, i.e. T3, Na, K and calcium increased significantly in the serum of Psammophis schokari aegyptius than in the other species. On the other hand, a higher level of cholesterol was found in the serum of Psammophis schokari schokari than that in the other two species. Level of cholesterol in the serum of Psammophis sibilans sibilans was lower than the other two species

Heart rate and body weight alterations in juvenile specimens of the tropical land snail Megalobulimus sanctipauli during dormancy

The time course of heart rate and body weight alterations during the natural period of dormancy were determined in active feeding and dormant juvenile specimens of Megalobulimus sanctipauli. In both groups, heart rate markedly decreased during the first 40 days of dormancy, tending to stabilize thereafter. This time period coincided with the decrease in environmental temperature during autumn-winter. At the end of the dormancy period, surviving active feeding and dormant snails showed a significant decrease in heart rate which, however, was significantly greater in the latter group. Total body weight decreased concomitantly with heart rate in dormant snails but remained constant in active feeding snails. Body hydration induced significant increases in weight and heart rate in surviving dormant snails. Feeding following hydration promoted a new significant increase in heart rate but not in weight. These results indicate that the decrease in heart rate observed in juvenile specimens of M. sanctipauli during dormancy may be due to at least three factors: 1) decrease in environmental temperature during autumn-winter, 2) starvation which leads to the depletion of endogenous fuel reserves and to a probable decrease in hemolymph nutrient levels, and 3) dehydration which leads to a probable decrease in hemolymph volume and venous return and/or to an increase in hemolymph osmolarity