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Biomedical subjects

A Nag

Publications and source records attributed to A Nag.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1991

Clinical manifestation of Clostridium difficile enteritis in Calcutta.

233 cases with acute diarrhoea investigated, Clostridium difficile was isolated as a sole pathogen from 17 (7.3%) cases. The Major clinical features of these cases were watery diarrhoea (82.4%), bloody stool (17.6%), vomiting (64.8%), fever (17.6%) and abdominal pain (2.5%). Fourteen (82.4%) of 17 C difficile isolates were found to produce cytotoxin as detected by Verocell assay.

Child↗
PubMed1990

Receptor interconversion model of hormone action. 3. Estrogen receptor mediated repression of reporter gene activity in A431 cells.

The chicken estrogen receptor exists in three interconvertible forms, two of which bind estradiol with high affinity and one which lacks the capacity to bind estradiol. Interconversion is regulated by reactions involving ATP/Mg2+. By cotransfecting into A431 cells estrogen receptor cDNA in an expression vector together with the pA2 (-821/-87) tk-CAT vitellogenin construct, we demonstrate that constitutive expression of chloramphenicol acetyltransferase (CAT) activity can be regulated either by selection of ligand or by modifying phosphorylation reactions in the recipient cells. In the presence of estrogen receptors, constitutive expression of CAT activity is inhibited in three situations: (i) in the absence of an estrogenic ligand; (ii) in the presence of an anti-estrogen; and (iii) in the presence of an estrogenic ligand together with 12-O-tetradecanoylphorbol 13-acetate (TPA). Estrogen receptor mediated repression of constitutive CAT activity is not observed with the pA2 (-331/-87) tk-CAT construct, indicating that DNA sequences required for repression are located between -821 and -331 base pairs upstream of the transcription initiation site.

Animals↗
PubMed1989

Amplification, rearrangement, and elevated expression of c-myc in the human prostatic carcinoma cell line LNCaP.

We have investigated the structure and expression of the c-myc proto-oncogene in DNA isolated from the immortal cell line LNCaP. This cell line was derived from a lymph node metastasis of human prostate cancer. Msp I digest of LNCaP DNA when hybridized to a human c-myc probe showed a 1.45 kb band of intensity about two-fold greater than that observed in normal lymphocytes. In addition, the LNCaP cells contain rearranged and amplified c-myc structures which are not present in normal lymphocytes. Quantitation of these bands by scanning densitometry is consistent with an approximately 10-fold amplification of c-myc. To determine whether this amplification was accompanied by increased expression, RNA was isolated from these cells and compared to RNA isolated from a control cell line in which c-myc was not amplified. Northern blot analysis showed that the RNA transcripts from LNCaP cells were approximately 50-fold higher. Although androgens modulate the cell growth of LNCaP, there was no change in the level of c-myc RNA transcripts in serum-free medium in the presence or absence of androgens. Further investigation to determine whether altered structure, amplification, and overexpression of c-myc constitute a common characteristic of metastatic human prostate cancer might prove profitable in understanding this disease.

DNA, Neoplasm↗
PubMed1987

Glucocorticoid effects on growth, and androgen receptor concentrations in DDT1MF-2 cell lines.

The DDT1MF-2 smooth muscle tumor cell line contains receptors for and is differentially sensitive to androgens and glucocorticoids. Androgens stimulate and glucocorticoids inhibit growth. We now confirm that the latter involves the induction of a block in the G1 phase of the cell cycle. We have developed and characterized in vitro and in vivo a glucocorticoid resistant variant of this cell line, the DDT1MF-2-GR. Glucocorticoids specifically inhibit androgen induced androgen receptor augmentation in DDT1MF-2 cells, but not in the GR variant suggesting that growth inhibition is related to inhibition of androgen receptor augmentation. However, under optimal conditions for cell proliferation, when glucocorticoid inhibited growth is relieved by the exogenous addition of platelet derived growth factor, androgen receptor augmentation is still suppressed. Thus, androgen induced elevation in androgen receptor concentrations is not a prerequisite for cell proliferation. These results imply that in androgen responsive cells, although androgen stimulation of growth can be blocked by antagonism of androgen receptor mediated events, the antagonism can be bypassed by supplying the cells with exogenous growth factors. These results provoke speculation on how cells, which are dependent upon androgens for growth, become autonomous.

Animals↗
PubMed1986

EMG analysis of sitting work postures in women.

Based on EMG analysis on six middle-aged women, seven sitting work postures were compared with reference to relaxed standing position. The muscles included in the investigation are pectoralis major, levator scapulae, deltoideus, latissimus dorsi, upper fibres of the trapezius, erector spinae, vastus medialis and lateralis, rectus femoris and gastrocnemius muscles. The commoner sitting postures examined were sitting on the floor with crossed legs, sitting on the floor with right leg bent at the knee, sitting on the floor with left leg bent at the knee, squatting with both legs bent at the knee without any back support, sitting on a plank of 10 cm height with both legs bent at the knee, sitting on the floor with legs extended, and sitting upright on a stool of 40 cm height. The relative load on the muscles was highest in the case of sitting on the floor with the right leg bent at the knee. However, less muscle activity was noted when sitting on the floor with the legs extended, a posture commonly adopted by women performing various domestic and other activities.

Journal Article↗
PubMed1986

Steroid regulation of receptor concentration and oncogene expression.

The DDT1MF-2 cell line was derived from an estrogen/androgen-induced tumor of the hamster ductus deferens. This cell line contains receptors for both androgens and glucocorticoids and its proliferation is differentially sensitive to these classes of steroids. Androgens stimulate cell growth dramatically and augment intracellular androgen receptors, whereas glucocorticoids inhibit growth and prevent androgen receptor augmentation. Androgen receptor augmentation occurs by an androgen-dependent increase in receptor half-life and an increase in the rate of synthesis. Glucocorticoids, in the presence of androgens, reduce both the half-life and the rate of synthesis of androgen receptors. For comparison purposes, a glucocorticoid-resistant mutant (DDT1MF-2-GR) of this cell line has been developed. Unlike the wild type, in this variant glucocorticoids neither arrest cell growth nor inhibit androgen receptor augmentation. Glucocorticoids block growth of the wild type in the G1-phase of the cell cycle. This event can be overcome either by addition of exogenous platelet-derived growth factor (PDGF) or by the addition of concentrated conditioned medium from nonglucocorticoid-treated cells, however, androgen receptor augmentation remains inhibited. The reduced production of PDGF-like growth factors in the presence of glucocorticoids appears to be the result of a decrease in production of mature mRNA with homology to v-sis (the viral oncogene coding for PDGF-like proteins). The level of regulation appears to be posttranscriptional and does not occur in the DDT1MF-2-GR cells. Thus glucocorticoids regulate the autocrine growth of the DDT1MF-2 cells by a mechanism that can be uncoupled from the regulation of androgen receptor augmentation.

Androgens↗
PubMed1985

Mechanism of the glucocorticoid regulation of growth of the androgen-sensitive prostate-derived R3327H-G8-A1 tumor cell line.

The R3327H-G8-A1 cell line derived from the Dunning rat prostate adenocarcinoma contains both androgen and glucocorticoid receptors. Following steroid deprivation, androgens specifically increase the concentration of their receptors in these cells by approximately 2-fold within 6 h and 3-4-fold in 24 h. In the presence of potent glucocorticoids, androgen receptor augmentation is reduced by 40-50% in the first 6 h and completely inhibited during the subsequent 24 h. This event, which is specific for glucocorticoids, appears to be due to an inhibition of androgen receptor synthesis. Furthermore, glucocorticoids inhibit proliferation of these cells by inhibiting the release of growth factors and arresting them in the G0 or A state of the cell cycle. This inhibition can be overcome by addition of low concentrations of either epidermal growth factor or platelet-derived growth factor; however, the inhibitory effect of the glucocorticoid on androgen receptor augmentation is not released. These results suggest that glucocorticoids arrest cellular proliferation by altering the autoregulation of growth and that this event is not dependent upon inhibition of androgen receptor augmentation.

Adenocarcinoma↗
PubMed1985

Comparative toxic effect of sumithion on rat and pigeon at the level of myelin.

Both rats and pigeons treated with sumithion, an organophosphorous pesticide, at a daily oral dose of one-tenth of the LD50, die after the 6th exposure. In spinal cord myelin of pigeon cerebroside, sulphatide and total protein contents decrease by 30, 15.7 and 40.8%, respectively, and cholesterol increases by 30% after 5 days of treatment; that of the rat shows none of these changes. Densitometric scannings of sodium dodecylsulphate-polyacrylamide gels of myelin proteins show a decrease in Wolfgram and proteolipid protein in rats and in pigeons up to 3 days; after 5 days this change continues only in pigeons, whereas rats show a normal pattern. The proteolipid protein and basic protein of both the species show increased mobility towards the anode up to 3 days, whereas after 5 days this trend continues in pigeons but not in rats.

Animals↗
PubMed1984

Sumithion induced neurotoxicity in pigeons: effect on lipid metabolism of spinal cord.

Sumithion, a well known organophosphorus pesticide, produces hind leg paralysis and ataxia in pigeons at a dose of 5 mg/kg for 5 days. Histochemical changes in the spinal cord showed demyelination in the anterior portion of the thoracic region. Decreases in cholesterol, cerebroside and sulphatide and increases in cholesterol ester suggest demyelination in pigeons as a consequence of the neurotoxic effect of sumithion.

Animals↗
PubMed1984

Replication timing of genes and middle repetitive sequences.

DNA replication in mammals is temporally bimodal. "Housekeeping" genes, which are active in all cells, replicate during the first half of the S phase of cell growth. Tissue-specific genes replicate early in those cells in which they are potentially expressed, and they usually replicate late in tissues in which they are not expressed. Replication during the first half of the S phase is, therefore, a necessary but not sufficient condition for gene transcription. A change in the replication timing of a tissue-specific gene appears to reflect the commitment of that gene to transcriptional competence or to quiescence during ontogeny. Most families of middle repetitive sequences replicate either early or late. These data are consistent with a model in which two functionally distinct genomes coexist in the nucleus.

Animals↗