Effects of chloride replacement and chloride transport blockade on the tonic tension of frog atrial trabeculae

The effects of a chloride-poor medium (methanesulfonate substituted) and a chloride transport inhibitor (SITS) on the outward delayed current and the tonic tension were studied on frog atrial trabeculae under voltage-clamp conditions. The outward delayed current decreased in low-chloride medium (10.5 mmol/l) or in the presence of SITS (2 mmol/l). The tonic tension increased in chloride-poor solution and decreased following SITS. The replacement of chloride by methanesulfonate enhanced the transient increase of tonic tension induced by low external sodium concentration while SITS reduced it. In the same conditions, the effect of the chloride-poor medium was abolished in the presence of SITS. The results showing an increase in Na-Ca exchange in low-chloride medium and a decrease by SITS are discussed assuming that changes in the inner negative charge density influenced the Na-Ca exchange mechanism; the influence of pHi variation are also considered.     

Patterns of female dominance in Propithecus diadema edwardsi of Ranomafana National Park, Madagascar

Many lemur species are characterized by some form of female dominance, ranging from female feeding priority to complete female dominance, although this is a rare trait in primates and other mammals. The status of the Milne-Edwards' sifaka (Propithecus diadema edwardsi), a diurnal lemur, is ambiguous. Some short-term studies have found little or no aggression. The aim of the current, long-term study was to quantify the intersexual-dominance patterns of this sifaka. The distribution, outcome, and context of aggressive interactions were studied in four groups of wild sifakas. The majority of intersexual aggressive interactions were decided, with the loser expressing submissive behavior. Intersexual aggressive interactions occurred in all social contexts, and within all social contexts the females won the vast majority (92.7-96.0%) of aggressive interactions. While aggression rates were low (0.22/hr), this evidence suggests female dominance. We propose that female dominance exists because it provides a fitness advantage to both males and females.     

Fruiting phenology is linked to rainfall variability in a tropical rain forest

As the influence of climate change on tropical forests becomes apparent, more studies are needed to understand how changes in climatic variables such as rainfall are likely to affect tree phenology. Using a twelve‐year dataset (2005–2016), we studied the impact of seasonal rainfall patterns on the fruiting phenology of 69 tree species in the rain forest of southeastern Madagascar. We found that average annual rainfall in this region has increased by >800 mm (23%) during this period relative to that recorded for the previous 40 years and was highly variable both within and between years. Higher monthly measures of fruiting richness and the intensity of fruiting in our sample community were associated with significantly higher levels of rainfall. We also found that less rainfall during the dry season, but not the wet season, was associated with a significant shift toward later timing of peak richness and peak intensity of fruiting in the subsequent 12 months; however, this pattern was driven primarily by an extreme drought event that occurred during the study period. Longer time scales of phenology data are needed to see whether this pattern is consistent. Madagascar is expected to experience more extremes in rainfall and drought with increasing climate change. Thus, the linkages between variable precipitation and the fruiting phenology of forest trees will have important consequences for understanding plant reproduction and the ability of Madagascar's wildlife to cope with a changing climate.     

Antihypertensive effects of Dorstenia psilurus extract in fructose-fed hyperinsulinemic, hypertensive rats.

We examined the effect of methanol/methylene chloride extract of Dorstenia psilurus given by gastric intubation on systolic blood pressure, plasma glucose, insulin, cholesterol, triglycerides and creatinine in rats with fructose-induced hypertension. Male Wistar rats in groups of 6 animals each were fed fructose-rich diets or standard chow for 3 weeks and treated with 100 mg/kg/day or 200 mg/kg/day of plant extract or vehicle for 3 subsequent weeks. Systolic blood pressure was measured every three days using the indirect tail cuff method. Systolic blood pressure was higher in fructose-fed rats (142+/-2 mm Hg, p < 0.01) compared with the controls (112+/-2 mm Hg), and was lower in Dorstenia psilurus-treated groups (127+/-2 and 119+/-1 mm Hg for the dose of 100 and 200 mg/kg, respectively) compared with the fructose-fed rats. Plasma insulin, cholesterol and triglycerides were higher on the fructose-rich diet compared with the controls. Plasma insulin and cholesterol were lower in the Dorstenia psilurus-treated groups. These results suggest that, Dorstenia psilurus treatment could prevent and reverse high blood pressure induced by a diet rich in fructose probably by improvement of plasma insulin levels. The plant extract might prove useful in the treatment and/or prevention of hypertension.     

Spatial Analysis of Pulmonary Tuberculosis in Antananarivo Madagascar: Tuberculosis-Related Knowledge,Attitude and Practice

Introduction

Tuberculosis infection may remain latent, but the disease is nevertheless a serious public health issue. Various epidemiological studies on pulmonary tuberculosis have considered the spatial component and taken it into account, revealing the tendency of this disease to cluster in particular locations. The aim was to assess the contribution of Knowledge Attitude and Practice (KAP) to the distribution of tuberculosis and to provide information for the improvement of the National Tuberculosis Program.

Methods

We investigated the role of KAP to distribution patterns of pulmonary tuberculosis in Antananarivo. First, we performed spatial scanning of tuberculosis aggregation among permanent cases resident in Antananarivo Urban Township using the Kulldorff method, and then we carried out a quantitative study on KAP, involving TB patients. The KAP study in the population was based on qualitative methods with focus groups.

Results

The disease still clusters in the same districts identified in the previous study. The principal cluster covered 22 neighborhoods. Most of them are part of the first district. A secondary cluster was found, involving 18 neighborhoods in the sixth district and two neighborhoods in the fifth. The relative risk was respectively 1.7 (p<10⁻⁶) in the principal cluster and 1.6 (p<10⁻³) in the secondary cluster. Our study showed that more was known about TB symptoms than about the duration of the disease or free treatment. Knowledge about TB was limited to that acquired at school or from relatives with TB. The attitude and practices of patients and the population in general indicated that there is still a stigma attached to tuberculosis.

Conclusion

This type of survey can be conducted in remote zones where the tuberculosis-related KAP of the TB patients and the general population is less known or not documented; the findings could be used to adapt control measures to the local particularities.     

Effect of Season and Age on the Gonadosomatic Index of Milne-Edwards' Sifakas (Propithecus diadema edwardsi) in Ranomafana National Park,Madagascar

Aiming to explain individual variation in gonadosomatic index (testicular volume per body weight), we examined the relationship between gonadosomatic index (GI), age, and season in a wild, seasonally breeding lemur—the Milne-Edwards' sifaka (Propithecus diadema edwardsi). Between 1987 and 2000, we captured and measured male lemurs from Ranomafana National Park in Madagascar 69 times. We used linear and polynomial regressions and residuals to examine the effect of season on GI and the effect of age on GI, after accounting for the effect caused by season among males of breeding age. As the breeding season approached, GI increased significantly, and all individuals measured in both the breeding and nonbreeding season had larger GI values in the breeding season. Among males of breeding age, we found no relationship between age and GI, after accounting for seasonal effects. Age, season and body weight fail to explain the variation remaining in GI. We discuss sperm competition, breeding-group composition, and the presence of parents as additional sources of variation in GI.     

Patterns of male scent-marking in Propithecus edwardsi of Ranomafana National Park, Madagascar

Scent-marking behavior has been well documented in many primate species. Three common functions attributed to scent-marking in males of multi-male/multi-female lemur species include: 1) advertisement of individual identity, 2) territorial defense, and 3) reproductive suppression. We examined the average number of scent-marks per hour exhibited daily by adult male sifakas (Propithecus edwardsi) and found that patterns of scent-marking changed with season, natal status, and dominance status. Males in single-male groups scent-marked at the highest rate, followed by dominant males, males of equal status, and subordinate males. Non-natal males generally scent-marked at higher rates than natal males, and adult males living in a natal group without a parent marked at higher rates than males living with a parent. All males scent-marked at higher rates in the migration season compared to the other seasons. These patterns were consistent with territorial defense and advertisement to females, and the suggestion that these chemical signals impart information concerning status. Since scent-marking behavior tracked seasons and varied with both dominance and natal status, it may serve multiple functions in males.     

Gathering Local Knowledge in Madagascar Results in a Major Increase in the Known Range and Number of Sites for Critically Endangered Greater Bamboo Lemurs (Prolemur simus)

Greater bamboo lemurs (Prolemur simus) are endemic to Madagascar and are the only recognized species within their genus. The IUCN lists the species as critically endangered, with very few confirmed distribution records and <200 individuals known in the wild. With the aim of contributing to its conservation, we attempted to find previously unknown sites containing the species. Working closely with local communities, and basing our methodology on the gathering of local knowledge, we surveyed 44 sites in and around the Ankeniheny-Zahamena Corridor. We found evidence of the presence of Prolemur simus at 18 sites. We made direct sightings at 6 sites, of a total of 65 confirmed individuals, and identified their characteristic feeding remains at the other sites. Twelve of the sites are located in midaltitude rain forest within the corridor, and 6 lie in isolated and degraded lowland areas outside the corridor. These discoveries more than double the number of sites where the species is known to occur, and extend its known range 85 km further north. We identified numerous threats to the newly discovered sites, including hunting pressure, habitat destruction, habitat disturbance, and habitat fragmentation. Demographic factors related to small population sizes and population isolation may also impact the viability of the populations. Our results illustrate the benefits of systematic gathering of local knowledge when searching for rare or secretive primates.     

Hypotensive effects of a methanol extract of Bidens pilosa Linn on hypertensive rats

Bidens pilosa Linn is highly regarded in some parts of Cameroon in traditional folk medical practices. The hypotensive effects of the leaf methanol extract from Bidens pilosa Linn (Asteraceae) were evaluated in spontaneously hypertensive rats (SHR), salt-loading hypertensive rats (SLHR) and normotensive Wistar rats (NTR) using the indirect (tail-cuff) method. Acute changes in urine volume and urinary excretion of Na+ and K+ were also studied. The hypotensive effect of the extract was more remarkable in hypertensive than in normotensive rats. Bidens pilosa did not provoke significant changes in the heart rate and urine volume. Urinary excretion of Na+ was decreased by 36% in spontaneously hypertensive rats and the excretion of K+ increased by 35% in normotensive rats but the effects were not statistically significant. These results suggest that the extract is a useful antihypertensive drug which has no effect on the heart frequency. The hypotensive effects of the extract may be induced by vasodilation.