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Biomedical subjects

R N Kulkarni

Publications and source records attributed to R N Kulkarni.

13 recordsLinked to original sources
PubMed1992

Thermic effect of a meal. 3. Effect of dietary supplementation in chronically undernourished human subjects.

Five apparently healthy, chronically undernourished (UN) male volunteers aged between 18 and 30 years were studied before and after 12 weeks of dietary supplementation. The thermic effect of a meal (TEM) was measured over a period of 6 h using a ventilated-hood system. Results indicated a significant increase in body-weight after supplementation due to increases in body fat and fat-free mass (FFM) in the proportion of 69% and 31% respectively. The basal metabolic rates (BMR) measured post supplementation were significantly higher in absolute terms, with a trend towards higher values when adjusted for the changes in FFM. TEM responses measured after 12 weeks of supplementation were significantly lower when expressed either in absolute terms (presupplementation 227.0 kJ v. post supplementation 193.5 kJ), or as a percentage of the energy density of the meal (9.1% v. 7.7%). This lower TEM was reciprocal to the changes in the BMR (r -0.86). The post-meal total energy output (PMTEO) was, however, not significantly different after 12 weeks of dietary supplementation. The unchanged PMTEO would indicate an unaltered 'thermogenic capacity', following supplementation, in these chronically undernourished subjects. These results confirm our earlier conclusion that, in chronic undernutrition, the thermic response to a meal may not contribute to any energy saving.

Adolescent↗
PubMed1992

Energy supplementation reverses changes in the basal metabolic rates of chronically undernourished individuals.

The objective of the present study was to examine the influence of energy supplementation and its cessation thereafter on the basal metabolic rates (BMR) of chronically undernourished individuals. Seven apparently healthy males were supplemented daily with 3.35 MJ (15 g protein, 35 g fat, 105 g carbohydrate) for 12 weeks. The average gain in body-weight was 1.9 kg (body fat, 58%; fat-free mass (FFM), 42%). The rise in BMR exceeded that accounted for by the increases in FFM during the 12 weeks of supplementation and was attributed to increases in the amount and activity of the visceral tissue as well as to an added cost of lipogenesis. At 12 weeks after cessation of the supplement, body-weights and FFM had decreased to presupplementation levels. BMR at this stage were significantly lower than at the 12th week of supplementation, when expressed per kg FFM or when adjusted for FFM using an analysis of covariance. These results suggest an increase in the metabolic efficiency during this negative energy balance period. The study demonstrates that, in the chronically undernourished, the changes in BMR are reversible and, hence, physiologically important to the process of adaptation to low-energy intakes.

Adaptation, Physiological↗
PubMed1991

Variability in cardiovascular and plasma norepinephrine responses to head-up tilt in healthy human subjects.

Eight healthy, young adult males underwent three separate, 10-min 70 degrees head-up tilts (HUT) over a period of nine days, in order to assess the intra- and inter-individual variability of cardiovascular and plasma norepinephrine (NE) responses to the manoeuvre. Cardiovascular parameters and plasma NE were measured in the basal state and at 2-min intervals during the HUT. The results indicate that: (1) the intra-individual variability is a smaller component of the total variability of both cardiovascular and plasma NE responses to HUT; (2) the variability in cardiovascular parameters is smaller than that in plasma NE levels, both basal and in response to postural stress; (3) there does not appear to be any difference in variability when expressed either as the maximal or the mean response to HUT; and (4) there does not appear to be an increase in the variability of the measured parameters over the duration of the HUT.

Adult↗
PubMed1991

Thermogenic responses to noradrenaline are unaltered following energy supplementation in chronically energy-deficient human subjects.

A group of chronically undernourished labourers underwent a period of controlled supplementary feeding (3.35 MJ per day) over a period of 12 weeks. Thermogenic responses to Noradrenaline (NA) (0.15 microgram kg-1 fat-free mass per min) were assessed (1) before supplementation (2) during the 12th week of supplementation and (3) 12-16 weeks following the cessation of supplementation. There were significant changes in anthropometric indices and basal metabolic rates (BMR) during the three stages of the study; however, these were not accompanied by significant changes in the thermogenic responses to NA.

Adult↗
PubMed1991

The scalene tubercle.

One hundred and thirty right and 114 left first ribs from a random collection have been studied for the characters of the scalene tubercle and the related structures. The tubercle is not always present but the muscular impression for the insertion of the scalenus anterior muscle on the superior surface of the first rib is almost constant and it generally extends upto the medial third of this surface. The arterial groove, generally shallow, lies behind the tubercle or the muscular impression and generally extends only upto the medial 2/3 of the superior surface. Likewise, the venous groove, mostly shallow, lies in front of the tubercle or the muscular impression and extends, generally, only upto the medial 2/3 of the surface. Normally, there is no separate groove for the lower trunk of the brachial plexus.

Humans↗
PubMed1989

Repeated infusions of identical doses of norepinephrine show potentiation of metabolic responses in human subjects.

Thermogenic responses to similar doses of norepinephrine appear to be different when repeatedly administered. This hypothesis was tested by three consecutive 30-minute infusions of a fixed dose of norepinephrine separated by a rest period of one hour between infusions. There was a significant increase or potentiation of the metabolic response as measured by oxygen consumption to the third dose of norepinephrine, while the cardiovascular responses showed no change. It is therefore important to make allowances for this phenomenon when assessing intergroup differences in regulatory thermogenesis using dose-response protocols for norepinephrine administration.

Adult↗
PubMed1989

Thermogenic responses to graded doses of noradrenaline in undernourished Indian male subjects.

1. Seventeen male subjects with an energy intake of 10.6 (SD 1.7) MJ/d and ten male undernourished labourers with an energy intake of 8.0 (SD 1.2) MJ/d were studied. The controls were subdivided into ten underweight controls with a body mass index (weight/height2; BMI) less than 18 (17.2 (SD 0.9)) and seven normal-weight controls with a BMI greater than 20 (21.3 (SD 1.6)), while the undernourished labourers had a BMI less than 18 (16.8 (SD 1.2)). 2. Comparison of thermogenic responses to increasing doses of noradrenaline showed no overall significant inter-group differences when subjected to a nested analysis of variance (ANOVA). For the initial doses of 0.05 and 0.1 micrograms noradrenaline, significantly lower responses were seen in the undernourished subjects, while the highest dose showed comparable responses in all three groups. Thermogenic responses to the initial two doses, when corrected for fat-free mass (FFM) differences, were 40% lower in the undernourished group when compared with the underweight group with similar BMI and FFM values. However, this finding was not statistically significant. 3. The basal oxygen consumption of the undernourished group, expressed per unit FFM, was significantly higher than that of the controls.

Adult↗
PubMed1989

The influence of different methods on basal metabolic rate measurements in human subjects.

While collating basal metabolic rate (BMR) measurements made worldwide it becomes important to know how different instruments compare with each other and whether errors in methodology could account for the differences in BMRs measured. BMRs of 34 healthy individuals were measured by using five different instruments in various combinations. Results show that energy outputs were comparable between the oxylog. Hartmann and Braun Metabolator, ventilated tent and hood, and whole-body indirect calorimeter: small differences, if any, were not statistically significant. However, significant interactions existed between subjects with the ventilated tent and hood and calorimeter when measurements were taken in subjects who were unaccustomed to the apparatus. When converting O2-consumption measurements to energy output, some instruments make assumptions that introduce a variable error in the final result, which may lead to systematic errors during the compilation of large databases of human BMRs.

Adult↗
PubMed1989

Reduced thermoregulatory thermogenesis in undernutrition.

Adaptive responses to chronic energy deficiency could occur in one of the important components of energy expenditure ie, regulatory thermogenesis. We assessed the thermogenic responses to standardized noradrenaline (NA) infusions in undernourished labourers, as well as in normally nourished control subjects. There was a significant suppression (greater than 60 per cent) of NA-stimulated oxygen consumption in the undernourished, which remained statistically significant even when the responses were corrected for fat-free mass differences. This first report of a suppression in regulatory thermogenesis indicates its important role in the adaptive response to lower than required energy intakes in human subjects.

Adult↗
PubMed1988

Prediction of steady-state oxygen consumption during norepinephrine infusions in humans.

A method for predicting maximal oxygen consumption during norepinephrine infusion is described. Using the initial response and enzyme kinetics, predicted values of maximal oxygen consumption were compared with observed values and a coefficient of variation of 1.4% was obtained. This method is of use in situations where it may not be possible to achieve steady-state conditions, especially with high doses of norepinephrine, and it permits comparison of maximal oxygen consumption between groups.

Adult↗
PubMedDate not supplied

Net mechanical efficiency during stepping in chronically energy-deficient human subjects.

Mechanical efficiency during a step test was measured in chronically energy-deficient (CED) individuals and compared to well-nourished subjects using a whole-body indirect calorimeter. The CED group had significantly higher net mechanical efficiencies than the well nourished subjects. This was also evident in the 15% lower energy costs observed in the CED subjects when expressed as a percentage of the predicted data. Factors such as a higher proportion of slow muscle fibres as well as a greater ergonometric efficiency may contribute to the observed higher muscular efficiency aiding conservation of energy expenditure in these individuals.

Adolescent↗