Body Position,Age and Mass Effect of Adiposity on Adipose Tissue Red Cell Flux in Morbid Obesity

Objective: To measure red cell flux of adipose tissue in morbidly obese patients' pannus in the upright and supine position to determine factors which would render the lower pannus susceptible to ischemic necrosis. Design: A cohort study of morbidly obese subjects without ischemic necrosis. Setting: University teaching hospital. Patients: Twenty-three consecutive morbidly obese patients referred for gastroplasty. Measurements: Red cell flux, measured as RMS voltage by a laser Doppler velocimeter. An optical fiber with a tip diameter of 250μ was inserted into the upper and lower pannus and output recorded in the upright and supine positions. Other variables recorded were age, BMI, blood pressure and serum lipids. Results: Adipose tissue red cell flux demonstrates considerable spatial and temporal heterogeneity from subject to subject and in various locations in the pannus. No differences in red cell flux were detected in response to change in position. However, regression analysis demonstrated that the gradient between the upper and lower abdomen in the supine position was increasingly positive with age and in the upright position it was increasingly positive with increasing weight or BMI. Conclusions: These data suggest that red cell flux is heterogeneously distributed in the abdominal pannus and is not greatly influenced by body position. However, with increasing age and adiposity there is a gradient for decreased red cell flux to the lower portion of the pannus. This may be a factor in rendering this part of the pannus prone to ischemic fat necrosis.     

Dispersal and extra-territorial prospecting by slender-tailed meerkats (Suricata suricatta) in the south-western Kalahari

Dispersal in slender-tailed meerkats or suricates, Suricata suricatta, in the south-western Kalahari occurred mainly during the early breeding season, and was age- and sex-dependent. Among yearlings, more males than females were immigrants, but more females than males disappeared. There were no sex differences in dispersal among two-year-olds, but among animals aged three years or older, more males than females emigrated. Most dispersers moved into adjacent bands or joined other transients, and females apparently suffered higher rates of mortality than males. Kinship with the same-sex or opposite-sex breeder had no discernible effect on the likelihood of dispersing. Both males and females made prospecting forays to other groups, apparently to assess dispersal and breeding opportunities. Males made frequent and repeated forays, often in coalitions with other band members or transients, whereas prospecting by females was generally solitary, and they were not known to make multiple forays. Prospecting males successfully took over dominance of two bands, and attempted to take over bands on three other occasions. Animals attempting to join or follow a band ( trailers ) behaved submissively and were readily chased by residents, whereas those attempting a dominance takeover ( invaders ) scent-marked at a high rate and showed no submissive behaviours. Dispersing meerkats maximized reproductive success by increasing their mating opportunities, while animals which delayed dispersal received indirect benefits by helping to raise kin.     

Distribution of Pax6 protein during eye development suggests discrete roles in proliferative and differentiated visual cells

 Although Pax6 is required during eye development in rodents and humans, little is known about the precise role of the protein in this process. To aid in the interpretation of functional studies, we have determined the precise spatial and temporal distributions of the Pax6 protein in the eye. We find that Pax6 is initially distributed contiguously throughout a large domain of the anterior neural plate of zebrafish, including the presumptive eye fields and the dorsal diencephalon. After evagination of the optic vesicle, Pax6 becomes restricted to all proliferating cells of the pigment epithelial and neural layers of the retina. Pax6 is downregulated in most cells concomitant with differentiation. However, it remains present in several mature cell types of the eye including amacrine cells and the lens and corneal epithelia. This expression is conserved across diverse vertebrate species and suggests that Pax6 has additional conserved functions in the mature eye. Received: 27 August 1996 / Accepted: 21 October 1996     

Endocrine correlates of contrasting male mating strategies in the European badger (Meles meles)

In mammals, testosterone secretion is known to respond rapidly to changes in males' immediate social environment. However, such changes do not take testosterone levels below the baseline required to maintain spermatogenesis, and so do not usually affect males' fertility. In this paper, we show that individual males' patterns of testicular activity reflect their social roles in a group-living carnivore, the European badger ( Melcs metes ), leading to individual and population differences in the seasonal patterns of both testosterone secretion and, apparently, spermatogenesis. In one badger population, some males left their natal groups to become breeding males in neighbouring territories. These males had higher plasma testosterone levels, and appeared to sustain spermatogenesis for a longer period, than males which remained in their natal territories. In contrast, in a second (higher density) population, males rarely transferred away from their natal territories, and appeared not to defend access to groups of females. Instead, males made forays to mate with females in neighbouring territories. In this population males had a shorter period of testicular activity, and there were no differences in testicular activity between immigrant and natal males.     

Is There a Role for the Apex in Shoot Geotropism?

Experiments with horizontal etiolated sunflower (Helianthus annuus L.) seedlings supported centrally such that both apical and basal ends are free to react to geostimulus, revealed that the apical end commences curvature 1 to 2 hours earlier than the basal end. The later curvature in the basal region is a consequence of the absence of growth in the initial period rather than merely slower growth. A comparison of zonal growth rates in a vertical and a horizontal seedling confirmed that geostimulus induces a renewal of growth in a region where growth had ceased. Removing the apical half of the hypocotyl showed that the curvature resulting from this growth initiation in the basal region is dependent on attachment to the apical region. Evidence that this dependence is unlikely to be due to energy deficiency is adduced. The prior response of the apical end to geostimulus and the apically dependent later initiation of new growth in the basal region are compatible with the delay inherent in message transport from apex to base and are considered as evidence for apical involvement in the totality of the seedling's georesponse.     

Catecholamines in fetal pig plasma and the response to acute hypoxia and chronic fetal decapitation

Summary Dopamine, norepinephrine and epinephrine were measured by radioenzymatic assay in blood plasma samples drawn from the umbilical arteries of 30 anaesthetised Landrace pig fetuses. Just prior to term, the concentrations of dopamine (0.46±0.14 ng·ml^–1) and norepinephrine (1.74±0.60 ng·mg^–1) were lower than earlier in gestation, whereas epinephrine concentrations at term (0.80±0.31 ng·ml^–1) were similar to those at mid-gestation, intervening stages of gestation having higher levels of plasma epinephrine. Fetal hypoxia was induced by clamping the umbilical cord for 2 min and the catecholamines determined in arterial blood samples immediately thereafter, then again 3 min after removal of the clamp. Inconsistent effects of cord clamping on catecholamine levels were seen at 55 days, but thereafter, in all but one instance, the hormone levels were increased. Fetuses near term tended to respond less than fetuses at 75 and 96 days gestation (term=114±1 day). Catecholamines were also present in the circulation of fetuses decapitated at 42 days gestation and studied at 109±1 days. The average concentrations of dopamine (1.12±0.27 ng·ml^–1) and norepinephrine (8.23±3.04 ng·ml^–1) were greater than in intact fetuses, the plasma epinephrine levels being comparable to, or slightly higher than, those in intact fetuses. The results demonstrate that catecholamines are present in the circulation of the intact and decapitated pig fetus and that the actual concentrations and the type of response to umbilical cord clamping are dependent on gestation age.     

Arginine deprivation in KB cells: I. Effect on cell cycle progress

When exponentially growing KB cells were deprived of arginine, cell multiplication ceased after 12 h but viability was maintained throughout the experimental period (42-48 h). Although tritiated thymidine ([(3)H]TdR) incorporation into acid-insoluble material declined to 5 percent of the initial rate, the fraction of cells engaged in DNA synthesis, determined by autoradiography, remained constant throughout the starvation period and approximately equal to the synthesizing fraction in exponentially growing controls (40 percent). Continous [(3)H]TdR-labeling indicated that 80 percent of the arginine-starved cells incorporated (3)H at some time during a 48-h deprivation period. Thus, some cells ceased DNA synthesis, whereas some initially nonsynthesizing cells initiated DNA synthesis during starvation. Flow microfluorometric profiles of distribution of cellular DNA contents at the end of the starvation period indicated that essentially no cells had a 4c or G2 complement. If arginine was restored after 30 h of starvation, cultures resumed active, largely asynchronous division after a 16-h lag. Autoradiographs of metaphase figures from cultures continuously labeled with [(3)H]TdR after restoration indicated that all cells in the culture underwent DNA synthesis before dividing. It was concluded that the majority of cells in arginine-starved cultures are arrested in neither a normal G1 nor G2. It is proposed that for an exponential culture, i.e. from most positions in the cell cycle, inhibition of cell growth after arginine with withdrawal centers on the ability of cells to complete replication of their DNA.     

Physical dependence on physiologically released endogenous opiates

Mice which had been submitted to a chronic schedule of warm water swimming exhibited a naloxone precipiated withdrawal behaviour which was remarkably similar to that produced in mice following chronic morphine treatment. These results are consistent with the activation of endogenous opiates during swim stress in mice and present the possibility that opiate receptors are activated in a manner analogous to the repeated application of exogenous opiates, producing both tolerance and withdrawal-like behaviour.     

Effects of gaseous anaesthetics and inert gases on the phase transition in smectic mesophases of dipalmitoyl phosphatidylcholine

The phase transition in smectic mesophases of dipalmitoyl phosphatidylcholine was studied under high pressures of helium (340 atm), nitrogen (340 atm), nitrous oxide (43 atm), cyclopropane (4.4 atm) and $\text{n-}\text{propane}$ (8.2 atm), using a turbidimetric technique. Helium and nitrogen increased the transition temperature by 0.021 and 0.006°C/atm, respectively, compared with 0.024°C/atm for hydrostatic pressure. Nitrous oxide reduced the transition by 0.58°C/atm. The hydrocarbon gases spread the transition width and lowered the transition temperature with increasing effect at higher doses. Comparisons with other membrane probes are made and the concentration of gases in the bilayer which lower the transition temperature by 1°C are estimated, in mol%: He, 10.2; N₂, 13.2; N₂O, 9.04; $\text{n-}\text{C}{}_3\text{H}{}_8$, 6.3 and cyclopropane, 12.8.     

Some observations on habituation of the flexor reflex in the rat: the influence of strychnine, bicuculline, spinal transection, and decerebration

The involvement of inhibition in habituation of the flexor reflex was investigated in intact, spinal, and decerebrate rats. Strychnine and bicuculline were administered in order to determine the contribution of certain forms of central inhibition to the development of habituation. Both strychnine and bicuculline reduced habituation in the intact rat but did not do so in the spinal preparation. Strychnine, in fact, caused a facilitation of habituation in the spinal rat. The impairment of habituation by strychnine was related to the intensity of stimulation used to elicit the reflex. Thus, the effect of strychnine was only demonstrable when relatively high intensities were used. Flexor reflex habituation was shown to be more pronounced in the decerebrate than in the spinal preparation. This difference could be demonstrated only when stimuli of high intensity were given. It is concluded that, in the absence of supraspinal influences, habituation of the flexor reflex does not require inhibitory mechanisms. However, inhibition may play a role in habituation of the component of the reflex that utilizes descending influences.