Finally,a sense of closure? Animal models of human ventral body wall defects

Malformations concerning the ventral body wall constitute one of the leading categories of human birth defects and are present in about one out of every 2000 live births. Although the occurrence of these defects is relatively common, few detailed experimental studies exist on the development and closure of the ventral body wall in mouse and human. This field is further complicated by the array of theories on the pathogenesis of body wall defects and the likelihood that there is no single cause for these abnormalities. In this review, we summarize what is known concerning the mechanisms of normal ventral body wall closure in humans and mice. We then outline the theories that have been proposed concerning human body wall closure abnormalities and examine the growing number of mouse mutations that impact normal ventral body wall closure. Finally, we speculate how studies in animal models such as mouse and Drosophila are beginning to provide a much-needed mechanistic framework with which to identify and characterize the genes and tissues required for this vital aspect of human embryogenesis.     

Biomarkers of Alzheimer’s disease in body fluids

Various innovative diagnostic methods for Alzheimer’s disease (AD) have been developed in view of the increasing preva-lence and consequences of later-life dementia. Biomarkers in cerebrospinal fluid (CSF) and blood for AD are primarily based on the detection of components derived from amyloid plaques and neurofibrillary tangles (NFTs). Published reports on CSF and blood biomarkers in AD indicate that although biomarkers in body fluids may be utilized in the clinical diagnosis of AD, there are no specific markers that permit accurate and reliable diagnosis of early-stage AD or the monitoring of disease pro-gression.     

Individualising the exposure of −110 °C whole body cryotherapy: The effects of sex and body composition

The purpose of this study was to investigate the effects of whole body cryotherapy (WBC) on a range of thermoregulatory measures. We also sought to examine the influence of sex and body composition. A convenience sample of 18 healthy participants (10 males and 8 females) (27±6 yr) volunteered for this study. Temperature (core, tympanic, skin and mean body), heart rate, blood pressure, and thermal comfort and sensation were recorded pre- and post- (immediately and every 5 min until 35 min post) exposure to a single bout of WBC (30 s at −60 °C, 150 s at 110 °C). Anthropometric data (height, weight, body surface area, body mass index, fat mass and fat free mass) were also recorded. No significant differences in temperature (core, tympanic, skin and mean body), heart rate, blood pressure, or thermal comfort / sensation were observed between male and females at baseline. Immediately post WBC mean body (male:31.9±0.8 °C; female:31.0±0.9 °C; ∆ mean body temperature:0.9±0.1 °C; P≤0.05, d=0.64) and mean skin (male:22.1±2.2 °C; female:19.6±2.8 °C; ∆ mean skin temperature:−2.5±0.6 °C; d=0.99, P≤0.05) temperature was significantly different between sexes. Sex differences were also observed in regional skin temperature (male thigh, 20.8±1.1 °C; female thigh, 16.7±1.1 °C, ∆ mean thigh skin temperature:−4.1 °C; d=3.72; male calf, 20.5±1.1 °C; female calf, 18.2±1 °C, ∆ mean calf skin temperature:−2.3±0.1 °C; d=3.61; male arm, 21.7±1 °C; female arm, 19±0.4 °C, ∆ mean arm skin temperature: −2.7±0.3 °C; d=3.54; P≤0.05). Mean arterial pressure was significantly different over time (P≤0.001) and between sexes (male 0 mins:94±10 mmHg; female 0 mins:85±7 mmHg; male 35 mins:88±7 mmHg; female 35 mins:80±6 mmHg; P≤0.05). Combined data set indicated a strong negative relationship between skin temperature and body fat percentage 35 min’ post WBC (r=−0.749, P≤0.001) and for core temperature and body mass index in males only (r=0.726, P≤0.05) immediately after WBC. There were no significant differences between sexes in any other variables (heart rate, tympanic and perceptual variables). We observed sex differences in mean skin and mean body temperature following exposure to whole body cryotherapy. In an attempt to optimise treatment, these differences should be taken into account if whole body cryotherapy is prescribed.     

Crystalloid body, refractile body and virus-like particles in Apicomplexa: what is in there?

The phylum of Apicomplexa comprises parasitic protozoa that share distinctive features such as the apical complex, the apicoplast, specialized cytoskeletal components and secretory organelles. Other unique cytoplasmic inclusions sharing similar features have been described in some representatives of Apicomplexa, although under different denominations. These are the crystalloid body, present for example in Cryptosporidium, Plasmodium and Cystoisospora; the refractile body in Eimeria and Lankesterella; and virus-like particles, also present in Eimeria and Cryptosporidium. Yet, the specific role of these cytoplasmic inclusions in the cell cycle of these protozoa is still unknown. Here, we discuss their morphology, possible inter-relatedness and speculate upon their function to bring these organelles back to the attention of the scientific community and promote new interest towards original research on these elusive structures.     

Weight decline in body,carcass, organs,and “gut fill” of sheep during the long dry seasons of the sub-Saharan West Africa

Data were collected from 188 indigenous (92 Uda and 96 Yankasa) breeds of sheep slaughtered at Maiduguri abbatoir from November 1983 to May 1984 to study decline in weight of body, carcass, organs, and gut fill in animals during the long dry seasons of the sub-Saharan West Africa. There was a highly significant (P<0.001) decline in all traits, which was most rapid by March–May (the hottest season), which is also the end of the long dry spell. From December to May the skin suffered greatest decline (about 58%), followed by the intestine (about 48%), liver, and stomach (about 44% respectively), and the head (about 41%). Total decline was 32% and 30% for body and carcass weights respectively. The Uda, which is the larger breed, apparently suffered greater overall depreciation. Both the absolute and relative weights of the liver seem larger in tropical- than in temperate-type sheep. However, liveweight, empty body, carcass, skin weights obtained herein are comparable with data from lambs of only 2-to 16-week old temperate sheep. Also the highest gut fill (3.91 kg, about 11% of body weight) recorded for these adult tropical sheep was far inferior to the 6.58 kg or 17% of body weight recorded for 16-week old lambs of temperate sheep. These may be forms of physiological responses to warm tropical environments, or simply, a very good reflection of the nutritional differences existing between animals of the tropical world on one hand and those of the temperate countries on the other. Studies on these topics would prove invaluable for successful livestock improvement programmes here.     

The rhizoplast of chrysomonads, a basal body–nucleus connector that polarises the dividing spindle

Summary. An ultrastructure study of the rhizoplast in Synura petersenii, Mallomonas fastigiata, and M. insignis shows that it consists of 15–20 striated rootlets that form a claw or an incomplete cone over the nucleus. These rootlets course along one face of the nucleus between the nuclear membrane and the cis-face of the Golgi stack of cisternae. They converge and merge above the nucleus, forming a stub attached to the proximal section of the two basal bodies. These cross-striated rootlets are composed of closely packed longitudinal microfibrils. By immunofluorescence, the basal bodies and the rootlets forming the claw were decorated by the anti-centrin monoclonal antibody ICL19 raised against the Paramecium tetraurelia acidic centrin protein and by two antibodies raised against the striated parabasal and costal striated fibres of trichomonads. Only the anti-centrin monoclonal antibody 20H5 raised against Chlamydomonas reinhardtii centrin strongly labelled the 20–22 kDa protein bands from the extracted cytoskeleton of S. petersenii by immunoblotting. Electron micrographs of mitosis in S. petersenii cells revealed that the segregated pairs of basal bodies are linked by the striated rootlets of the rhizoplast to the poles of the mitotic spindle. The spindle microtubules arise perpendicularly from the striated rootlets of the basal body–nucleus connector forming the centrosome. In conclusion, in these cells there is a basal body–nucleus connector similar to that of C. reinhardtii and other chlorophytes. It contains centrin proteins, it is involved in the linkage of the basal bodies to the nucleus and is a component of the spindle pole body or centrosome in the dividing cell.Correspondence and reprints: Biologie des Protistes, Université Blaise Pascal de Clermont-Ferrand, Campus des Cézeaux, 63177 Aubière Cedex, France.Present address: Romagnat, France.Received February 7, 2003; accepted May 21, 2003; published online September 23, 2003     

Parameters of glucose and lipid metabolism in the male Göttingen minipig: influence of age, body weight, and breeding family

The pig is useful as a model for human physiology and pathophysiology and could be an important supplement to the many available rodent models of diabetes mellitus. Due to their small size, G?ttingen minipigs are especially suitable for long-term studies. The aim of the study reported here was to establish reference values for a range of glucose and lipid homeostasis parameters of interest that could be used to identify possible diabetes-prone male G?ttingen minipig individuals, families, or age groups. Plasma samples from nonfed animals were analyzed for glucose, leptin, fructosamine, insulin, C-peptide, triglyceride, free fatty acids, and total cholesterol values. Breeding family had significant effects only on plasma triglyceride concentrations (P < 0.001). Plasma concentrations of glucose (P = 0.012), fructosamine (P < 0.001) and triglycerides (P < 0.001) increased significantly with age, whereas total cholesterol concentration decreased significantly (P = 0.001) with age. Age did not influence other parameters. In conclusion, glycemia and insulinemia increased with age and body weight, possibly indicating a small deterioration in insulin sensitivity with age. It is, therefore, hypothesized that older, compared to younger animals may be more useful in the development of a model of type-2 diabetes mellitus. Furthermore, on the basis of decrease in cholesterol concentration with age, animals fed ad libitum with possibly a high calorie diet might be even more useful in the development of a type-2 diabetes mellitus model.     

Is bigger really bigger? Differential responses to temperature in measures of body size of the mosquito,Aedes albopictus

When confronted with variation in temperature, most ectotherms conform to a growth rule that "hotter is smaller". This phenomenon can have important implications on population dynamics, interactions with other species, and adaptation to new environments for arthropods. However, the impact of other environmental factors and genetics may affect that general rule. Furthermore, most studies measure a single body part, and do not examine how temperature and other factors alter the allometric relationship between measurements of growth. In this study, we test the hypothesis that temperature and nutrition, while strongly affecting growth, do not change the allometric relationship between body mass and wing length in the mosquito Aedes albopictus. We tested this hypothesis by growing larval mosquitoes from two populations at five temperatures with three food levels. Contrary to our hypothesis, we find that temperature has a profound effect on allometry, with higher temperatures resulting in mosquitoes with shorter wings and greater body mass, and that the effects of temperature are dependent upon available food and population origin. We therefore reject our hypothesis and propose several testable mechanisms that will provide greater insight into the relationship between temperature, food, and measures of growth.     

Plasticity of preferred body temperatures as means of coping with climate change?

Thermoregulatory behaviour represents an important component of ectotherm non-genetic adaptive capacity that mitigates the impact of ongoing climate change. The buffering role of behavioural thermoregulation has been attributed solely to the ability to maintain near optimal body temperature for sufficiently extended periods under altered thermal conditions. The widespread occurrence of plastic modification of target temperatures that an ectotherm aims to achieve (preferred body temperatures) has been largely overlooked. I argue that plasticity of target temperatures may significantly contribute to an ectotherm's adaptive capacity. Its contribution to population persistence depends on both the effectiveness of acute thermoregulatory adjustments (reactivity) in buffering selection pressures in a changing thermal environment, and the total costs of thermoregulation (i.e. reactivity and plasticity) in a given environment. The direction and magnitude of plastic shifts in preferred body temperatures can be incorporated into mechanistic models, to improve predictions of the impact of global climate change on ectotherm populations.     

Autoradiographic localization of α-bungarotoxin-binding sites in the carotid body of the rat

Summary Radioiodinated -bungarotoxin (-Bgt) was used to localize -Bgt-acetylcholine receptors in the carotid body of the rat. The gamma spectrometer analyses indicated a high uptake of [¹²⁵I] -Bgt in carotid bodies incubated in vitro (1.51 fmole per organ). Incorporation of the isotope was effectively blocked by pretreatment of carotid bodies with d-tubocurarine and unlabeled -Bgt, but not by atropine. Light microscopic autoradiography showed a heavy labeling of some parenchymal cells. Electron-microscopic autoradiography revealed that labeling was localized along the interface between parenchymal cells, especially where their cytoplasmic processes engage in complex interdigitations. The silver grain counts on electron-microscopic autoradiographs suggest that labelings are preferentially associated with the plasma membrane of certain Type I cells. It is suggested that these Type I cells in the rat's carotid body probably are provided with nicotinic acetylcholine receptors on their plasma membranes.This research was partly supported by a grant from the Edward G. Schleider Foundation of New Orleans.The authors extend appreciation to Drs. Akira Arimura, Dept. of Medicine, for supplying a part of the radioisotope and to James Fisher, Dept. of Pharmacology, Tulane Medical School, for use of the gamma spectrometer. Appreciation also is extended to Mrs. Lia Pedroza for technical assistance     

Patterns of body temperatures: Is lizard thermoregulation chaotic?

We surveyed body temperature (T_b) fluctuations of 23 species of thermoregulating lizards (9 families, 305 individuals) for pattern similarities. Here we report that the T_b time-series patterns of all species and almost all individuals met both qualitative criteria and quantitative criteria (positive Lyapunov exponent and capacity and/or correlation dimensions less than 5, and Hurst exponent not equal to 0.5) for deterministic chaos. Chaotic thermoregulation appears controlled, but at unpredictable times becomes disturbed and exhibits nonlinear behaviors before returning to control. This chaotic pattern of regulation is common to sufficiently diverse species to suggest that it is likely a primitive lacertilian, and perhaps reptilian, physiological characteristic.     

Examining predator–prey body size,trophic level and body mass across marine and terrestrial mammals

Predator–prey relationships and trophic levels are indicators of community structure, and are important for monitoring ecosystem changes. Mammals colonized the marine environment on seven separate occasions, which resulted in differences in species'' physiology, morphology and behaviour. It is likely that these changes have had a major effect upon predator–prey relationships and trophic position; however, the effect of environment is yet to be clarified. We compiled a dataset, based on the literature, to explore the relationship between body mass, trophic level and predator–prey ratio across terrestrial (n = 51) and marine (n = 56) mammals. We did not find the expected positive relationship between trophic level and body mass, but we did find that marine carnivores sit 1.3 trophic levels higher than terrestrial carnivores. Also, marine mammals are largely carnivorous and have significantly larger predator–prey ratios compared with their terrestrial counterparts. We propose that primary productivity, and its availability, is important for mammalian trophic structure and body size. Also, energy flow and community structure in the marine environment are influenced by differences in energy efficiency and increased food web stability. Enhancing our knowledge of feeding ecology in mammals has the potential to provide insights into the structure and functioning of marine and terrestrial communities.     

Comparison of BMI and the body mass/body surface ratio: is BMI a biased tool?

For decades we are used to judge our body composition by using the body mass index (BMI). Since the BMI denominator can be considered as a substitute for body surface area (BSA), the body mass/body surface ratio (BM/BSA) can be calculated. For a distribution of BM/BSA values comparable to the distribution of normal BMI values, the range 35.5-39.9 kg/m2 is chosen as normal, although it covers BM range 50 to 90 kg. The proposed normal BM/BSA range suggests that heavy adults with less than 2 m of height are not obese only if they are less than 90 kg. If the described limitations of the BM/BSA ratio are valid, then the BMI should be regarded as a biased tool, less applicable to individuals with body masses outside the 55 to 90 kg BM range. If we consider many health problems related to the increased body mass, it is possible that the BMI should be used with caution in heavy individuals.     

Agonist of the adenosine A3 receptor,IB-MECA,and inhibitor of cyclooxygenase-2, meloxicam,given alone or in a combination early after total body irradiation enhance survival of γ-irradiated mice

There exists a requirement for drugs which would be useful in therapy of an acute radiation damage of a mammalian organism. The aim of the study was to evaluate survival parameters in mice exposed to a lethal γ-ray dose of 8.5 Gy and treated with single doses of an adenosine A₃ receptor agonist, IB-MECA, or a cyclooxygenase-2 (COX-2) inhibitor, meloxicam, administered alone or in a combination early after irradiation, i.e., 0.5 and 1 h post-irradiation, respectively. The assessed parameters were the mean survival time (MST) and the cumulative percentage 30-day survival (CPS). Administrations of single intraperitoneal doses of either IB-MECA 0.5 h post-irradiation or meloxicam 1 h post-irradiation resulted in statistically significant increases of MST in comparison with the control irradiated mice. Combined administration of IB-MECA and meloxicam was found to be the only treatment statistically enhancing the parameter of CPS and to lead to the most expressive increase in MST of the experimental mice. The findings add new knowledge on the action of an adenosine A₃ receptor agonist and a COX-2 inhibitor in an irradiated mammalian organism and suggest the potential of both the investigated drugs in the treatment of the acute radiation damage.     

Post-continuous whole body exposure of rabbits to 650 MHz electromagnetic fields: effects on liver, spleen, and brain

This study deals with the effects of post (12 or 18 months) whole body continuous (2 years) exposure of rabbits to 650 MHz electromagnetic fields (EMF) that are characteristic of those produced by broadcasting stations, on body weight and body mass, on the morphology of liver, spleen and brain, and on apoptosis rates and glycogen distribution in the liver. Two groups of rabbits were continuously exposed for 2 years to EMF of 650 MHz followed by 12 months (group 1) or 18 months (group 2) of post-exposure; a third group (group 3) was sham exposed. It was shown that the changes in apoptosis rates were conditional during the time of exposure, but not on a specific organ and that the whole body continuous exposure gave rise to modifications whose types and intensities were related to the time of post-exposure (12 or 18 months, respectively), the type of organ, and the individual animal. A number of effects were observed only in group 1, and not in group 2, which suggests some kind of adaptive response or of long-term recovery in the rabbits following continuous exposure to 650 MHz EMF.     

“Irregular” visual receptive fields of neurons of the cat lateral geniculate body

Using point-to-point testing, the spatial organization of receptive fields (RF) of the neurons of the lateral geniculate body (LGB) was studied in cats with pretrigeminally transected brainstcm (without general anesthesia). In 60% of studied neurons (96 units of 160 examined), configuration of their RF considerably differed from round or ellipsoid. The shape of such RF was frequently rather complex, and they were qualified as irregular receptive fields (IRF). Presentation of the stable flickering spot throughout the entire surface of 60 IRF (63%) evoked qualitatively similar responses of a neuron, i.e., these IRF were homogeneous. In 29 cells the responses were of theon-off type, 22 neurons generatedoff responses, andon responses were observed in 9 cells. In the rest of the IRF (37%), it was possible to differentiate the subfields, whose stimulation evoked generation of different types of responses, i.e., these IRF were heterogeneous. In the case of moving stimuli, the neurons with homogeneous IRF showed no directional selectivity, while such selectivity was observed in most units with heterogeneous IRF.Neirofiziologiya/Neurophysiology, Vol. 28, No. 1, pp. 7–16, January–February, 1996.     

Thermal variability in body temperature in an ectotherm: Are cloacal temperatures good indicators of tortoise body temperature?

Historically, studies of reptilian thermal biology have compared ambient temperatures (T_a) to body temperatures (T_b) from the animal under study, with T_b usually taken from the cloaca and various instruments being used to measure T_b. The advent of surgically implanted miniature temperature loggers has offered the opportunity to test the efficacy of cloacal T_b as a measurement in thermoregulatory studies. We expected that there was a difference between skin, cloacal, and core T_b's. Temperatures were measured from various positions on leopard tortoises (Stigmochelys pardalis) using thermocouples and miniature temperature loggers, including surgically implanted temperature loggers. Measurements of temperature from various positions on and in the tortoise were significantly different from T_a. Cloacal T_b's were significantly lower than all other body temperatures measured, and core T_b's were significantly different from cloacal T_b, skin and carapace temperatures. In addition, significant differences were found between measures of temperature from other parts of the body. The variations between core T_b, cloacal T_b and other measures of T_b indicated that there are large thermal gradients within the body of a relatively large tortoise at any given time with cloacal T_b not an accurate measure of core T_b.