PubMed Health⌕ Search

Biomedical subjects

P K Nag

Publications and source records attributed to P K Nag.

At least 19 recordsLinked to original sources
PubMed2003

Hand anthropometry of Indian women.

BACKGROUND & OBJECTIVES: Data on the physical dimension of the hand of Indian women are scanty. This information is necessary to ascertain human-machine compatibility in the design of manual systems for the bare and gloved hand, such as design and sizing of hand tools, controls, knobs and other applications in different kinds of precision and power grips. The present study was undertaken to generate hand anthropometric data of 95 women, working in informal industries (beedi, agarbatti and garment making). METHODS: Fifty one hand measurements of the right hand (lengths, breadths, circumferences, depths, spreads and clearances of hand and fingers) were taken, using anthropometric sliding and spreading calipers, measuring tape and handgrip strength dynamometer. The data were statistically analyzed to determine the normality of data and the percentile values of different hand dimensions, and simple and multiple regression analysis were done to determine better predictors of hand length and grip strength. RESULTS: The hand breadths, circumferences and depths were approximately normally distributed, with some deviation in case of the finger lengths. Hand length was significantly correlated with the fist, wrist and finger circumferences. The fist and wrist circumferences, in combination, were better predictors of hand length. The hand lengths, breadths and depths, including finger joints of the Indian women studied were smaller than those of American, British and West Indian women. The hand circumferences of the Indian women were also smaller than the American women. Grip strengths of Indian women (20.36 +/- 3.24 kg) were less than those of American, British and West Indian women. Grip strength was found to be statistically significant with hand dimensions, such as hand height perpendicular to wrist crease (digit 5), proximal interphalangeal joint breadth (digit 3) and hand spread across wedge 1. INTERPRETATION & CONCLUSION: The women who are forced to frequently use cutters, strippers and other tools, which are not optimally designed to their hand dimensions and strength range, might have higher prevalence of clinical symptoms and disorders of the hand. In view of the human hand-tool interface requirements, the present data on Indian women would be useful for ergo-design applications of hand tools and devices.

Adolescent↗
PubMed2001

Shiftwork in the hot environment.

The study examined the risks of heat induced workplace accidents (textile industry, N = 4125) and the heat tolerability of the rotating day (morning and afternoon, N = 16) and permanent night shift workers (N = 13) in hot-dry and hot-humid environment (34 to 49 degrees C, 50-80% RH; 31 to 42 degrees C ET, Basic). Accident prevalence was significantly high in the summer months (May-June) when the ambient temperature ranged between 42 and 48 degrees C (hot-dry). The influence of hot climate in accident causation was evident from the shift-wise variations in the occurrence of accidents. The longitudinal study showed that the night workers were more vulnerable and less tolerant to heat, the tolerance time being less by about 15% (31 degrees C ET) to 40% (39 degrees C ET), compared to the rotating day workers. The relationship of the segmental and compartmental temperatures (segmental triggering response) played a critical role in heat dissipation/accumulation mechanism, and reflected in the heat tolerability of the day and night workers.

Accidents, Occupational↗
PubMed1998

Efficacy of a water-cooled garment for auxiliary body cooling in heat.

The efficacy of a water-cooled jacket for auxiliary body cooling was examined under a simulated hot environment. The personal garment comprised of a water re-circulating three-layered vest of cotton fabric lined with 2 mm diameter latex tubing and inter-spaced coating of rubberized solution. Four subjects wearing the water-cooled jacket were tested in the environment chamber (30, 35 and 40 degrees C DB, 50-60% RH, air velocity 0.3, 0.6 and 0.9 m/s, with corresponding average effective temperature of 26 +/- 2.3, 33 +/- 1.1 and 36 +/- 1.5 degrees C). The inlet water temperature was maintained at 10-12 degrees C, with flow rates of 2.6 +/- 0.3, 4.3 +/- 0.3 and 5.1 +/- 0.3 l/h). At 30 degrees C DB, variation in water flow had marginal effect on microclimate, while at higher temperatures (35 and 40 degrees C DB), the re-circulating cooled water had noticeable effects in lowering microclimate, trunk and other skin temperatures, and maintaining the body core within 36.7 +/- 0.2 to 37.5 +/- 0.2 degrees C, over 2 h exposure at 35 and 40 degrees C DB. The observation indicates that the water-cooled jacket provided auxiliary cooling to maintain comfortable microclimate, skin and body core temperatures. This enabled subjects to sustain comfortable heat balance over 2 h heat exposure without any noticeable heat strain.

Adult↗
PubMed1997

Human heat tolerance in simulated environment.

The heat tolerance of 11 male volunteers were examined under seven climatic conditions in a climatic chamber. The conditions were 38 to 49 degrees C dry bulb temperature and 45 to 80 per cent relative humidity, i.e., 32.3 to 40 degrees C effective temperature-basic [ET(B)]. The ET(B) values were equated to other heat stress indices, e.g., WBGT (Wet-bulb Globe Temperature Index) and Oxford Index. The subjects did ergometric work at an intensity of 60 per cent VO2max. The exposure durations were decided by the cardiorespiratory, body temperature and sweating responses. Of the climatic conditions studied, at 35.4, 38, 39 and 40 degrees C ET(B), the body core temperature (Tcr) reached over 39 degrees C and heart rates attained 172 to 182 beats/min, which were taken as the tolerance limit. The total oxygen demand significantly varied with the increase in environmental warmth, i.e., increase or decrease of one litre of oxygen demand was equivalent to one minute change in tolerance time. The volunteers were not susceptible to heat; only in extreme hot situations beyond 35.4 degrees C ET(B), were unacceptable levels of physiological and psychophysical reactions seen. The study suggests the acceptable and tolerable limits for human exposure in heat: (i) acceptable at 38 to 38.2 degrees C Tcr for a tolerance time of 80 to 85 min; and (ii) the tolerable limit of short duration (40-45 min) at 39 degrees C Tcr that corresponded to 31.5 and 36.5 degrees C ET(B).

Adolescent↗
PubMed1996

Human work capacity under combined stress of work and heat.

The working capacity of young, healthy, unacclimatized men (N = 11) was studied under long-duration (8 to 9 days) exposure to combined work and heat (dry and humid). The dry (Gr A, N = 5) and humid (Gr B, N = 6) groups were exposed to 41.3 +/- 0.6 degrees C DB, 40-50% RH and 39.2 +/- 0.6 degrees C DB, 70-80% RH, respectively, for all days of exposure. The experimental protocol was divided into: (i) direct determination of maximal oxygen uptake (VO2max) by stepped increases in bicycle ergometry everyday in the morning in the initial hours before exposure to heat, after which the recovery process of oxygen debt contraction was examined; and (ii) exposure to heat in a climatic chamber for 2 h where the subjects performed two spells of ergometric work (10 to 12 min each) at a relative intensity of 50 +/- 12 to 69 +/- 11% VO2max. The average heat exposure time for Gr A was higher (108 +/- 12 min) as compared to Gr B (95 +/- 10 min), but Gr B sustained a high heat load as reflected from the high deep-body temperature maintained during the exposure. The high body temperature load of Gr B had a significant effect on the cardiorespiratory capacity, indicating an upward trend in VO2max. This was statistically significant (p < 0.05) for the first four days of exposure. Subjects of Gr B had a relatively higher working capacity compared to those in Gr A on all days. The VO2max and analysis of the fractions of oxygen debt contraction (fast and slow component) indicated that the subjects showed a better training/heat acclimatization effect under hot, humid conditions.

Adult↗
PubMed1995

Regulation of estrogen receptor and progesterone receptor messenger ribonucleic acid by estrogen in the brain of the whiptail lizard (Cnemidophorus uniparens).

Receptive behavior in females vertebrates is controlled by hormones, principally estrogen, secreted by the ovary. Estrogen influences behavior by interacting with a specific estrogen binding protein, or receptor, located in target cells in certain hypothalamic nuclei. To better understand the molecular mechanisms involved in the control of receptive behavior in whiptail lizards, we investigated the effects of exogenous estrogen on the regulation of estrogen receptor and progesterone receptor expression in several regions of the brains of Cnemidophorus uniparens. First we determined a dosage of 17 beta-estradiol 3-benzoate (0.5 micrograms) which reliably induced receptive behavior in ovariectomized C. uniparens. Then using in situ hybridization, we examined the effects of that dosage on the expression of estrogen receptor and progesterone receptor mRNA in the brain 24 h after injection. Estrogen treatment resulted in a significant up-regulation of estrogen receptor mRNA expression in the ventromedial nucleus of the hypothalamus and torus semicircularis, down-regulation of estrogen receptor mRNA expression in the lateral septum, and no change in the periventricular nuclei of the hypothalamus, the periventricular nucleus of the preoptic area, and the dorsal hypothalamus. The same dosage resulted in increased progesterone receptor mRNA expression in the ventromedial nucleus of the hypothalamus and the periventricular nucleus of the preoptic area; no significant changes in progesterone receptor mRNA expression were observed in the periventricular nuclei of the hypothalamus or the torus semicircularis, although the differences in progesterone receptor expression in the torus semicircularis approached statistical significance.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Species differences in estrogen receptor and progesterone receptor-mRNA expression in the brain of sexual and unisexual whiptail lizards.

Circulating concentrations of gonadal steroid hormones and reproductive behavior in female vertebrates vary as a function of ovarian state. Steroids secreted by the ovary, specifically estrogen and progesterone, influence the expression of behaviors associated with reproduction by intracellular sex steroid receptors located in specific regions of the brain. Using in situ hybridization, we analyzed estrogen receptor and progesterone receptor messenger RNA expression in several brain regions of ovariectomized, vitellogenic, and postovulatory individuals from two species of whiptail lizards (Cnemidophorus uniparens and C. inornatus). Although these species are genetically very similar, they differ in two aspects of their reproductive biology: (i) the unisexual C. uniparens alternate between expressing female-typical and male-like pseudosexual behaviors while female C. inornatus normally express only female receptive behavior, and (ii) circulating estradiol concentrations in reproductively active female C. uniparens are approximately five-fold lower than in reproductively active female C. inornatus. We found that the regulation of sex steroid receptor gene expression was region specific, with receptor-mRNA expression being increased, unchanged, or decreased during vitellogenesis depending on the area. Furthermore, several species differences in the amount of sex steroid receptor-mRNA were found that may be relevant to the species differences in circulating estrogen concentrations and sexual behavior.

Animals↗
PubMed1995

Species differences in behavioral and neural sensitivity to estrogen in whiptail lizards: correlation with hormone receptor messenger ribonucleic acid expression.

Cnemidophorus uniparens is a unisexual species of whiptail lizard of hybrid origin whereas C. inornatus is a sexual species and the maternal ancestor of C. uniparens. Together they represent an excellent model system for investigating the evolution of hormone-brain-behavior relationships. Normal circulating estradiol (E) concentrations in C. uniparens are approximately 5-fold lower than those of female C. inornatus in a similar reproductive state. Experiments were performed to determine whether (i) C. uniparens is more sensitive to E, and (ii) whether the difference in sensitivity is correlated with differences in estrogen receptor (ER)-mRNA expression in the brain. Dose-response curves reveal that ovariectomized C. uniparens are more responsive than ovariectomized C. inornatus to exogenous estradiol 17 beta-benzoate (EB). EB is more effective in C. uniparens at inducing receptive behavior and progesterone receptor (PR) gene expression in the ventromedial nucleus of the hypothalamus (VMH). In situ hybridization analysis of ER-mRNA expression revealed no species differences in ER-mRNA content in the VMH of ovariectomized animals. Treatment of ovariectomized animals with EB resulted in a greater induction of ER-mRNA expression in the VMH of C. uniparens compared to C. inornatus. These results indicate that the differences in behavioral sensitivity to E lie in the estrogen target neurons in the brain region controlling receptive behavior, the VMH, and that the difference in sensitivity cannot be explained by species differences in the basal rate of ER gene expression.

Animals↗
PubMed1993

Influence of air flow on skin temperature.

The skin temperature is fundamental to heat exchange between the human body and the environment. The convective and evaporative heat exchanges depend on the temperature gradient and the extent of air flow over the skin surface. An attempt was made to study the topographical differences in skin temperature (Tsk) under varied levels of air flow and to examine the possible body temperature regulatory mechanism. Five volunteers were examined in a climatic chamber at 30 and 36 degrees C DB at 55-60% RH (ambient vapour pressure of 2.58 and 3.53 kPa and air flow of 0.6, 1.4, 1.9, 2.1 m/s). The deep body temperature (Tc) and local Tsk were recorded at 5-min intervals during 10 min pre-exposure, 30 min exposure to heat and 15 min recovery period after air flow was withdrawn. The time taken to attain at the lowest Tsk in different air speeds varied from 30 to 45 min. The highest drop in Tsk (2.4 degrees C) was recorded for forehead at 30 degrees C DB and significant skin cooling was achieved at an air flow of 0.6 m/s for most body regions. The overall drop in local Tsk was more greater at a higher ambient temperature (36 degrees C) and the changes were significantly different (p < 0.05) to those recorded at the preexposure level. There was a consistent drop in Tsk with time, while no definite pattern of drop was noted with the magnitude of air flow. The Tc increased significantly with the continued air flow and following withdrawal of air flow the Tc tended to drop, suggesting heat gain by the body with a consequent increase in Tc.

Adult↗
PubMed1992

Heat stress of women doing manipulative work.

Six women were exposed to nine environmental conditions, ranging from 26.0 to 35.8 degrees C effective temperature (ET), in a climatic chamber. They were involved in manipulative work in a seated position for a duration of 3 hr. The O2 uptake, heart rate, deep body (Tc) and skin temperature (Tsk), sweat loss, and perception of thermal comfort were noted. The O2 uptake increased with the time of exposure at different heat levels. The work energy demand, which was 19% of VO2max at 26 degree C ET, increased to 35% of VO2max at 35.8 degrees C ET. However, the work output declined with the increase in ET. Thus, the elevated metabolic demands were the results of the thermal stimuli. The Tsk was greatly influenced by the environmental heat; the Tc changes were gradual. The highest mean Tsk attained was 37.3 degrees C at 33.8 degrees C ET when the gradient of Tc-Tsk was only 0.5 degrees C. The rate of change in mean Tsk for 31.6 to 33.8 degrees C ET was much faster compared to the range between 26.0 and 31.6 degrees C ET. From 32.1 degrees C ET onward the Tc and heart rates rose rapidly, while the sweating rate tended to fall, indicating some hindrance for evaporative cooling. Also, thermal sensations were noted as extremely hot for the conditions 32.1 to 35.8 degrees C ET with the increase in exposure duration.

Adult↗
PubMed1992

Work stress of women in sewing machine operation.

The study examined the work stresses of 107 women who were engaged in sewing machine operation in small garment manufacturing units. Of the three types of sewing machines (motor-operated, full and half shuttle foot-operated), 74% of the machines were foot-operated, where throttle action of the lower limb is required to move the shuttle of the machine. The motor-operated machines were faster than the foot-operated machines. The short cycle sewing work involves repetitive action of hand and feet. The women had to maintain a constant seated position on a stool without backrest and the body inclined forward. Long-term sewing work had a cumulative load on the musculo-skeletal structures, including the vertebral column and reflected in the form of high prevalence of discomfort and pain in different body parts. About 68% of the women complained of back pain, among whom 35% reported a persistent low back pain. Common sewing work accident is piercing of the needle through the fingers, particularly the right forefingers. Unsatisfactory man-machine incompatibility, work posture and fatigue, improper coordination of eye, leg and hand are the major problems of the operators. The design mis-match of the work place may be significantly improved by taking women's anthropometric dimensions in modifying the workplace, i.e. the seat surface, seat height, work height, backrest, etc.

Adult↗
PubMed1987

Maximal oxygen uptake of agricultural men and women in India.

The maximal oxygen uptake (VO2 max) of 228 men and 47 women from the Indian agricultural community was measured. The VO2 max in 20-24-year-old men was about 17% less than in the 25-29-year-old group. With advancing age, the VO2 declined gradually to the ages 55-59, excepting the 36-39-year-old group. The loss in VO2 max was 0.65 ml/kg.min per year between 25 and 39 years of age and 0.16 ml/kg.min per year between 40 and 59 years of age. However, 30-39-year-old women had 7% higher VO2 max than the 20-29-year-old age group; and the difference in VO2 max between the group 30-39 and the group 40-49 years of age was 32%. The 20-29-and 40-49-year-old women had VO2 max 24 and 30% less than those of men in the same age range.

Adolescent↗