Regulation of oxygen consumption and body temperature during torpor in a hummingbird, Eulampis jugularis.

The West Indian hummingbird, Eulampis jugularis, maintained its body temperature in torpor at 18 degrees to 20 degrees C over an ambient temperature range of 2.5 degrees to 18 degrees C. At ambient below 18 degrees C oxygen consumption during torpor increased linearly with decreasing temperature. Thermal conductances were the same for resting and torpid Eulampis regulating their body temperatures at 40 degrees and 18 degrees C, respectively.

Energetics of foraging: rate and efficiency of nectar extraction by hummingbirds.

The efficiency with which several species of hummingbirds extract nectar was estimated by converting the rate of extraction of nectar volumes to the energy expended and the energy obtained from the nectar. The extraction rates depend on corolla and bill morphologies, and the extraction efficiencies depend, in addition, on the bird weight and nectar concentration. Differential extraction efficiencies can be exploited by plants to increase pollinator specificity.

Stability and diversity at three trophic levels in terrestrial successional ecosystems.

An ecosystem perturbation experiment in which inorganic fertilizer was added to two successional old fields of different ages indicated that stability, expressed as resistance to modification by enrichment, increased during succession only at the primary trophic level. The perturbation was propagated throughout the arthropod herbivores and carnivores. Both herbivores and carnivores were less stable in the older field. In contrast to current ecological theory, greater diversity at a trophic level was accompanied by lower stability at the next higher level.

Spatial learning as an adaptation in hummingbirds.

An ecological approach based on food distribution suggests that humming birds should more easily learn to visit a flower in a new location than to learn to return to a flower in a position just visited, for a food reward. Experimental results support this hypothesis as well as the general view that differences in learning within and among species represent adaptations.

A prospective study identifying risk factors for discontinuance of insulin pump therapy.

OBJECTIVE: To identify characteristics of adult patients at baseline associated with duration of subsequent, continuous, subcutaneous infusion of insulin treatment (pump therapy) of type I diabetes. RESEARCH DESIGN AND METHODS: For 6 wk, patients followed a standardized conventional therapy and kept a record of insulin dosages, capillary blood glucose concentrations, and symptomatic hypoglycemia. They were then hospitalized. Additional baseline data were obtained and pump therapy was started. Survival analysis was used to determine the relationship between baseline independent variables or risk factors and duration of pump therapy, which is the dependent variable. RESULTS: Of the 68 participants, 33 (49%) terminated pump therapy after an average of 9.9 mo of treatment. Two models (each P < 0.00005) were developed that exhibited a high degree of consistency. Of the 6 variables, 5 were common to both models (HbA1, autonomic neuropathy, mean amplitude of glycemic excursions, frequency of symptoms of hypoglycemia when blood glucose was < 70 mg/dl, and erythema at injection sites). The sixth variable in model 1 (insulin dosage) was replaced in model 2 by a variable, Adult Self-Efficacy for Diabetes, which was obtained on the 33 more recently enrolled patients; this variable related to patient perceptions of self-care behaviors. CONCLUSIONS: We found that, at baseline, the presence of a high concentration of HbA1 and a low estimation by the patient of their ability to treat the disease portend failure of insulin pump therapy as evidenced by its discontinuation. This effect is accentuated when clinical evidence of autonomic neuropathy is observed. These findings offer guidance in selecting patients with type I diabetes for insulin pump therapy.

Environmental risk factors for oesophageal cancer in Malawi: A case-control study.

AIM: There is a high burden of oesophageal cancer in Malawi with dismal outcomes. It is not known whether environmental factors are associated with oesophageal cancer. Without knowing this critical information, prevention interventions are not possible. The purpose of this analysis was to explore environmental factors associated with oesophageal cancer in the Malawian context. METHODS: A hospital-based case-control study of the association between environmental risk factors and oesophageal cancer was conducted at Kamuzu Central Hospital in Lilongwe, Malawi and Queen Elizabeth Central Hospital in Blantyre, Malawi. Ninety-six persons with squamous cell carcinoma and 180 controls were enrolled and analyzed. These two groups were compared for a range of environmental risk factors, using logistic regression models. Unadjusted and adjusted odds ratios and 95% confidence intervals (CI) were calculated. RESULTS: Firewood cooking, cigarette smoking, and use of white maize flour all had strong associations with squamous cell carcinoma of the oesophagus, with adjusted odds ratios of 12.6 (95% CI: 4.2-37.7), 5.4 (95% CI: 2.0-15.2) and 6.6 (95% CI: 2.3-19.3), respectively. CONCLUSIONS: Several modifiable risk factors were found to be strongly associated with squamous cell carcinoma. Research is needed to confirm these associations and then determine how to intervene on these modifiable risk factors in the Malawian context.

Quality of life activities associated with adherence to insulin infusion pump therapy in the treatment of insulin dependent diabetes mellitus.

The impact of continuous subcutaneous insulin infusion (CSII) pump therapy on patients' activities of daily living and the prevalence of acute complications were examined in order to characterize patients' experience while on CSII, and to ascertain whether any of these factors could be associated with continued use of CSII. Fifty-one of 55 patients (93%) identified as initiating CSII in our medical center patient population completed retrospective surveys; 37 individuals (73%) were still using pumps and 14 individuals (27%) had discontinued pump use. CSII appeared to affect the quality of daily activities only modestly, neither improving nor interfering with many activities to any great degree. Activities associated with greatest improvements were eating, working, traveling, sleeping, and exercising. Results of logit analyses adjusting for duration of pump therapy indicated that the prevalence of six different acute complications (skin infections at the needle site, mild insulin reactions, more severe insulin reactions requiring assistance, hypoglycemic coma, asymptomatic hypoglycemia, and ketoacidosis) was not statistically associated with patients' decisions to continue or to stop CSII. In contrast, significant differences (p less than 0.05) between the groups continuing and discontinuing CSII were found in 11 of 18 activities of daily living. In general, patients continuing CSII, in contrast to those discontinuing CSII, found that many of their activities were improved significantly during pump therapy. There were few differences between groups in the degree to which CSII was perceived to interfere with daily activities. However, those continuing CSII found it significantly less necessary to take the pump off while doing some activities than did those discontinuing CSII.(ABSTRACT TRUNCATED AT 250 WORDS)

Dysmenorrhea.

Dysmenorrhea is a common complaint that causes considerable disruption in a woman's life. Accurate diagnosis of primary and secondary causes with appropriate therapeutic intervention leads to significant improvements in quality of life.

Peripheral neuropathy associated with the hypereosinophilic syndrome.

This case report documents the natural history of the peripheral polyneuropathy associated with persistent hypereosinophilia after treatment with corticosteroids. The neuropathy was documented by nerve conduction studies which revealed reduced amplitude of the sensory and motor evoked responses and slowed conduction velocities that were consistent with axon loss. Sural nerve biopsy revealed mild axonal loss distally without eosinophilic infiltration. The patient was treated with high-dose corticosteroids with a rapid normalization of his eosinophil count. Neurologic examination six months later revealed a slight improvement in his motor strength and reflexes but no change in sensory functions. Follow-up electromyographic evaluation demonstrated an average 89% improvement in evoked potential amplitudes and a slight improvement in distal latencies and conduction velocities. These findings suggest that the neuropathy associated with hypereosinophilia is axonal in nature and that there is a temporal relationship between reduction in the absolute eosinophil count and the improvement of the neuropathy.

Genetic architecture of a wing size measure in Drosophila hibisci from two populations in eastern Australia.

Two models of evolutionary change invoke either additive genetic contributions to phenotypic traits (Fisher) or epistatic as well as additive effects (Wright). An earlier study of the flower-breeding Drosophila hibisci from two sites in eastern Australia reported additive and epistatic genetic effects as well as environmental effects on ovariole number. The present study of the same flies examines the genetic architecture of wing width, a trait that is correlated phenotypically with ovariole number and body size. A generation means analysis of flies reared at 25 degrees C indicated additive and epistatic genetic effects, but no consistent maternal effects, whereas for flies reared at three temperatures (18 degrees C, 21.5 degrees C, and 25 degrees C) linear and nonlinear environmental effects interacted with additive genetic effects. The genetic correlation matrix for ovariole number and wing width suggested negative genetic correlations between additive effects on one trait and epistatic effects on the other. Both traits provide evidence of genetic effects consistent with assumptions of Wright's shifting balance theory of evolution.

Reproductive characteristics of the flower-breeding Drosophila hibisci Bock (Drosophilidae) in eastern Australia: within-population genetic determinants of ovariole number.

Genetic variation for ovariole number in the flower-breeding Drosophila hibisci was studied within populations obtained from three separate sites in the centre of the species distribution along the east coast of Australia. Heritability for ovariole number (adjusted for body size), derived from isofemale lines from each site, was estimated to be h2+/-SE = 0.564+/-0.160. The variance of ovariole number within sites (sigma2(within) = 2.039) was comparable to the variance between sites (sigma2(between) = 2.048) obtained from an earlier study of populations sampled over 14 degrees of latitude. Two isofemale lines (from within one site) that differed by an average of 4.6 ovarioles were used to generate F1, F2 and backcross generations. Analysis of mean ovariole number for these generations showed that only additive gene effects were important and that dominance, digenic epistasis and maternal effects were not significant. This within-population result contrasted with earlier results between populations that revealed additive and digenic epistasis for the same trait. High heritability within populations and the relatively large within-population variation for ovariole number suggest that substantial microhabitat variation is influencing this fitness-related trait.