Defensive use of a fecal thatch by a beetle larva (Hemisphaerota cyanea)

The larva of the tortoise beetle, Hemisphaerota cyanea (Chrysomelidae, Cassidinae), constructs a thatch from long filamentous fecal strands, beneath which it is totally concealed. The thatch is not discarded at molting but is enlarged by addition of strands as the larva grows. Thatch construction begins when the larva hatches from the egg. Pupation occurs beneath the thatch. Two predators, a coccinellid beetle larva (Cycloneda sanguinea) and a pentatomid bug (Stiretrus anchorago), were shown to be thwarted by the thatch. However, one predator, a carabid beetle (Calleida viridipennis), feeds on the larva by either forcing itself beneath the thatch or chewing its way into it. The attack behavior is stereotyped, suggesting that the beetle feeds on Hemisphaerota larvae as a matter of routine.     

Changes of pH affect calcium currents but not outward potassium currents in rat myometrial cells

Spontaneous contraction of uterine smooth muscle is enhanced by alkalinization and depressed by acidification. We have investigated the ionic currents responsible for this in single myometrial cells. Intracellular acidification (20 mM butyrate) at constant external pH depressed the magnitude of the calcium current to 58±6% of control, but had little effect on outward currents. Similar but slower effects were also observed when the extracellular pH was lowered to 6.9 (56±9% of control). Correspondingly, when the intracellular or extracelluar pH was elevated (20 mM NH₄Cl or pH 7.9 respectively) the calcium current magnitude increased (165±15 % in NH₄Cl; 136±2 % at pH 7.9) and there was, again, no effect on the outward currents. These observations are consistent with the effects of pH on spontaneous contractile activity being due to an effect on the membrane calcium current.     

Update on malignant mesothelioma

Mesotheliomas are uncommon in the United States, with an incidence of about 3,000 new cases per year (or a risk of about 11 per million Americans per year). Incidence and mortality, however, are probably underestimated. Most are associated with asbestos, although some have arisen in ports of prior radiation, and a reported association with simian virus (SV)40 remains controversial. About 85% of mesotheliomas arise in the pleura, about 91% in the peritoneum, and a small percentage in the pericardium or tunica vaginalis testis. The histology of about half of mesotheliomas is epithelial (tubular papillary), with the remainder sarcomatous or mixed. Multicystic mesotheliomas and well-differentiated papillary mesotheliomas are associated with long survival in the absence of treatment and should be excluded from clinical trials intended for the usual rapidly lethal histologic variants of the disease. The median survival is under a year, although longer median survivals for selected patients, particularly those with epithelial histology, have been reported in some combined-modality studies. Recent randomized trials have shown significant improvement in time to progression and survival for the addition of new antifolates to platinum-based chemotherapy.     

On the mode of action of difenoxin (R 15 403). Part 2: Studies on the perfused isolated colonic loop of the rat (author's transl)]

The effect of 1-(3-cyano-3,3-diphenylpropyl)-4-phenyl-isonipecotinic acid hydrochloride (difenoxin, R 15 403), a new antidiarrhoic agent, was studied in vivo in rats with an isolated colonic loop. Difenoxin had no effect on transport or absorption of fluid during perfusion experiments. When given i.p. it inhibited the motility of the coecum but not that of the colon. Difenoxin has apparently no effect on normal rat colon, although an effect may have been masked by the wide variation of parameters measured under identical conditions.     

Stability and instability of regulation of intracellular calcium

[Ca2+]i is used as a signal in many tissues. In this review we discuss the mechanisms that regulate [Ca2+]i and, importantly, what determines their stability. Brief mention is made of the effects of feedback gain and delays on stability. The control of cytoplasmic Ca concentration is shown to be generally stable as Ca pumping is essentially an instantaneous function of [Ca2+]i. In contrast, regulation of the Ca content of intracellular stores may be less stable. One example of this is instability in the control of sarcoplasmic reticulum (SR) Ca content in cardiac muscle. An increase of SR Ca content increases the systolic Ca transient amplitude. This in turn decreases Ca influx into the cell and increases efflux, thereby restoring SR Ca to control levels. This feedback system has an inherent delay and is potentially unstable if the gain is increased beyond a certain level. This instability produces Ca transients of alternating amplitude and may contribute to the clinical syndrome of pulsus alternans.     

Health-related quality of life in adult rhinitis: the role of perceived control of disease

BACKGROUND: Factors affecting health-related quality of life (HRQOL) in adult rhinitis have not been well described. OBJECTIVE: To understand how symptom severity, physical functioning, psychological distress, and perceived control of disease relate to HRQOL in a population-based sample of adults with rhinitis. METHODS: We conducted telephone interviews in 109 adults with rhinitis recruited via random digit dialing. We assessed HRQOL by using the Rhinosinusitis Disability Index, physical functioning by using the physical component score of the Short Form-12, and psychological distress by using the Center for Epidemiologic Studies Depression Scale. To evaluate the role of patient-perceived control of disease in rhinitis, we developed a new 8-item instrument, the Perceived Control of Rhinitis Questionnaire. RESULTS: Lower HRQOL correlated with greater symptom severity ( r=0.57), poorer physical functioning ( r=-0.41), greater psychological distress ( r=0.44), and less perceived control ( r=-0.53). In a multivariate model, symptom severity ( P < .001), psychological distress ( P <.001), and perceived control ( P <.001) were all independent predictors of HRQOL. Adding functional and psychosocial measures to a base model with demographics and disease severity explained an additional 26% of variance in HRQOL. CONCLUSIONS: Although disease severity is an important factor in HRQOL, psychosocial factors, such as perceived control of disease, explain a substantial amount of the variability in HRQOL among adults with rhinitis.     

Visual sensitivity across the menstrual cycle

This study was designed to evaluate the hypothesis that hormonal change can affect lower level light-adaptation processes, which are likely to be retinally based. Foveal visual sensitivities were measured across several menstrual cycles of four women not using hormonally acting medication and across several menstrual cycles of three women using a triphasic oral contraceptive. One woman, diagnosed with premenstrual syndrome (PMS), was a subject for both groups. Sensitivities were measured for a series of test wavelengths for 580-nm backgrounds of 2.0 and 4.0 log td. Of the six individuals tested, one had clear evidence of visual-adaptation changes occurring in phase with the menstrual cycle. Prior to using the oral contraceptive, this individual (the PMS subject) experienced changes of short-wavelength-sensitive (SWS)-cone-mediated sensitivities of up to about 1.4 log unit on the 4.0 log td background. Her SWS-cone-mediated sensitivities tended to be highest near ovulation and lowest premenstrually. Threshold-versus-illuminance (TVI) curves confirmed that the rate of sensitivity decrease with increasing background illuminance (i.e. the TVI slope) was greater premenstrually. The degree of background-induced desensitization within her middle-wavelength-sensitive (MWS)/long-wavelength-sensitive (LWS) cone pathways also appeared to vary cyclically, but the magnitude of the variation was smaller and the time course appeared to be different. When this subject began oral contraceptive use, the patterns of sensitivity change were all altered. None of the other five subjects experienced changes of SWS-cone-mediated vision that were cyclic and significantly adaptation-state dependent. However, there was evidence for a limited degree of cyclic adaptation change within the MWS/LWS cone pathways of at least one additional subject. We conclude that hormonal change can--for some unknown proportion of women--be linked to alterations of retinal function. However, the alterations are not the same for all visual pathways, and there are pronounced individual differences. The data also demonstrate that individuals' visual adaptation capabilities can vary substantially over periods of weeks.