Low level wind shear over Bomba airport

Significant climatological features based on 329 Low Level Wind Shear (LLWS) reports from 1985 to 1989 at Bombay airport are presented, The monsoon season has the highest frequency of occurrence of LLWS mainly due to thunderstorms and strong gusty winds, Other than monsoon season, occurrence of LLWS is related to sea and land breeze and nocturnal increase of surface temperature during night. The preferred time of occurrence of LLWS is between 0000 to 0600 IST and 1800 to 240J IST. The simultaneous occurrence of strong and severe LL WS, low cloud ceiling and very poor visibility has an adverse effect on aircraft operations at Bombay airport during landing and take-off.

The Reserve/Maximum Capacity of Melatonin’s Synthetic Function for the Potential Dimorphism of Melatonin Production and Its Biological Significance in Mammals

In this article, we attempt to classify a potential dimorphism of melatonin production. Thus, a new concept of “reserve or maximum capacity of melatonin synthetic function” is introduced to explain the subtle dimorphism of melatonin production in mammals. Considering ASMT/ASMTL genes in the pseudoautosomal region of sex chromosomes with high prevalence of mutation in males, as well as the sex bias of the mitochondria in which melatonin is synthesized, we hypothesize the existence of a dimorphism in melatonin production to favor females, which are assumed to possess a higher reserve capacity for melatonin synthesis than males. Under physiological conditions, this subtle dimorphism is masked by the fact that cells or tissues only need baseline melatonin production, which can be accomplished without exploiting the full potential of melatonin’s synthetic capacity. This capacity is believed to exceed the already remarkable nocturnal increase as observed within the circadian cycle. However, during aging or under stressful conditions, the reserve capacity of melatonin’s synthetic function is required to be activated to produce sufficiently high levels of melatonin for protective purposes. Females seem to possess a higher reserve/maximum capacity for producing more melatonin than males. Thus, this dimorphism of melatonin production becomes manifest and detectable under these conditions. The biological significance of the reserve/maximum capacity of melatonin’s synthetic function is to improve the recovery rate of organisms from injury, to increase resistance to pathogen infection, and even to enhance their chances of survival by maximizing melatonin production under stressful conditions. The higher reserve/maximum capacity of melatonin synthesis in females may also contribute to the dimorphism in longevity, favoring females in mammals.

Effect of Evening Bromazepam Administration on Blood Pressure and Heart Rate in Mild Hypertensive Patients

Aim: To assess the effects of chronic evening oral administration of bromazepam alone or in combination with propranolol on ambulatory blood pressure (BP) and heart rate (HR) in mild hypertensive subjects. Methods: Thirty-seven mild hypertensive patients after a 2-week placebo period were randomized to bromazepam 3 mg, propranolol 40 mg, bromazepam 3 mg plus propranolol 40 mg or placebo for 2 weeks according to a double-blind, double dummy, cross-over design. After each treatment period, 24-h BP and HR ambulatory monitoring was performed by using a non-invasive device. Results: Ambulatory monitoring showed that during night-time SBP and DBP values were unaffected by bromazepam as compared to placebo, whereas SBP was significantly reduced by propranolol both when taken alone and in combination with bromazepam. HR nocturnal values were significantly reduced by propranolol, whereas they were significantly increased by bromazepan both when taken alone (+11.5%, p < 0.05 vs. placebo) and in combination with propranolol (+12.8%, p < 0.05 vs. propranolol). No significant difference in day-time values of SBP, DBP and HR was observed among the 4 treatment groups. Conclusions: In mild hypertensive patients, evening consumption of bromazepam for a 2-week period did not affect BP, while it increased nocturnal HR. Such an increase was observed both when bromazepam was taken alone and in combination with propranolol, which suggests that it depends on a bromazepam mediated decrease in vagal tone. Whatever the mechanism, the HR nocturnal increase might be of clinical relevance, due to the role of high HR as cardiovascular risk factor, particularly in already at risk hypertensive subjects.

6-Sulfatoxymelatonin predicts treatment response to fluoxetine in major depressive disorder

Background: To date, no biomarker has been able to predict antidepressant response at an early blockade of norepinephrine or serotonin uptake. The transient nocturnal increase in plasma melatonin levels is upregulated by blocking these uptakes. The aim of this study was to test whether fluoxetine increase in urinary 6-sulfatoxymelatonin (aMT6s) is an indicator of serotonin uptake blockade. Methods: A total of 20 women (35–45 years of age) recruited from the community had a diagnosis of major depressive disorder confirmed by the Structured Clinical Interview for DSM-IV. Depressive symptoms were evaluated by the Beck Depression Inventory (BDI). Participants were instructed to take 20 mg of fluoxetine every morning. Every 4 weeks, the dose could be increased by 20 mg until symptom remission. The concentration of aMT6s was evaluated in overnight urine samples collected 1 day before and 1 day after the first fluoxetine dose. Results: An increase in aMT6s correlated to a decrease in BDI score evaluated on day 45 (ρ = −0.67, p = 0.024) was observed. Conclusions: Nocturnal increase in urinary aMT6s after the first day of medication use links the early mechanism of action of fluoxetine to its clinical output 45 days later. Thus, the relationship between urinary aMT6s excretion 1 day before/1 day after is a biomarker for predicting clinical output earlier, reducing illness burden and health care costs.

The effect of treatment for sleep apnoea on determinants of blood pressure control

Our aim was to assess the effect of continuous positive airway pressure (CPAP) on the nocturnal evolution of peripheral chemosensitivity, renin–angiotensin–aldosterone system activity, sympathetic tone and endothelial biomarkers in obstructive sleep apnoea (OSA) patients with isolated nocturnal hypertension (INH) or day–night sustained hypertension (D-NSH).In a crossover randomised trial, 32 OSA patients newly diagnosed with hypertension and without antihypertensive treatment were randomly assigned to 12 weeks of CPAP or sham CPAP. Peripheral chemosensitivity was evaluated before and after sleep using the hypoxic withdrawal test (%ΔVI).At baseline, D-NSH patients showed higher %ΔVI before sleep and higher levels of aldosterone and diurnal catecholamines. CPAP only reduced the nocturnal increase of %ΔVI in INH patients (6.9%, 95% CI 1.0–12.8%; p=0.026). CPAP-induced change from baseline in %ΔVI after sleep was 7.5% (95% CI 2.6–12.2%, p=0.005) in the INH group and 5.7% (95% CI 2.2–9.3%, p=0.004) in the D-NSH group. In contrast, %ΔVI before sleep only decreased with CPAP in the D-NSH patients (3.0%, 95% CI 0.5–5.6%; p=0.023).In conclusion, CPAP reduces the nocturnal increase of peripheral chemosensitivity experienced by INH patients and corrects the high daytime sensitivity of patients with D-NSH. Differences in response to CPAP between these patients can help better understand the mechanisms of perpetuation of hypertension in sleep apnoea.

Melatonin Regulates Daily Variations in Electric Behavior Arousal in Two Species of Weakly Electric Fish with Different Social Structures

Timing is crucial for social interactions. Animal behavior is synchronized with biotic and abiotic environment variables ensuring that the activity phase of conspecifics occurs during the same period of the day. As biological rhythms are embedded in the complex integrative control of the brain, it is fundamental to explore its interaction with environmental and social factors. This approach will unravel the link between external stimuli carrying information on environmental cycles and the neural commands for behavior, including social behavior, associated with precise phases of those cycles. Arousal in the solitary Gymnotus omarorum and in the gregarious Brachyhypopomus gauderio is characterized by a nocturnal increase in the basal discharge rate of electric behavior, which is mild and transient in G. omarorum and large and persistent in B. gauderio. In this study, we show that the major integrator of social behavior, AVT (arginine vasotocin), is not involved in the nocturnal increase of electric behavior basal rate in isolated animals of either species. On the other hand, endogenous melatonin, the major modulator of the circadian system, is responsible for the nocturnal increase in electric behavior in isolated individuals of both species.