Immunoglobulin profile in breastmilk during first six months of lactation.
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Adolescent↗
Biomedical subjects
T K Das
Publications and source records attributed to T K Das.
pH-induced conformational perturbation in horseradish peroxidase. Picosecond tryptophan fluorescence studies on native and cyanide-modified enzymes.
The fluorescence-decay characteristics of the single tryptophan present in horseradish peroxidase (HRP) have been studied using dye-laser pulses and single-photon counting techniques. The decay was found to be dominated by a picosecond-lifetime component, with small contributions from two other lifetime components in the nanosecond range. The distance of the tryptophan residue was estimated from the fluorescence-energy transfer to the heme moiety using Förster's theory. The tryptophan residue was found to be approximately 1.2 nm from the heme moiety at neutral pH. Detailed analysis of the fluorescence-decay profiles using the maximum-entropy method (MEM) has been carried out. The results of the MEM analysis also showed a maximum amplitude peak at approximately 45 ps (at pH approximately 7) with a very small (< 5%) contribution from two other components. Similar results were obtained with the cyanide derivative of the enzyme (HRPCN) where the major lifetime component was found to be 58 ps at neutral pH. The picosecond component of fluorescence lifetimes of native HRP as well as of HRPCN were found to increase with decrease in pH in the range pH 6-3.5. Moreover, the native enzyme showed significant increase in the magnitude of this fast lifetime component at pH above 8. Such increase in the major lifetime component possibly indicated a conformational perturbation caused by pH change in the enzyme. However, the pH dependence of HRPCN, which is devoid of alkaline transition, showed that the shortest lifetime component remains almost unchanged over the pH range 6-11. This result showed that the alkaline transition in native HRP is associated with a structural change in the distal region of the heme center, which is absent in the cyanide-ligated enzyme. The results have been discussed with respect to understanding the pH-induced effects associated with salt bridge and hydrogen-bonding network in HRP.
Cyanides↗
Transformation in Aspergillus ochraceus.
Mutants (lysine requiring) of Aspergillus ochraceus were kept under starvation conditions for 15 days and finally were treated with DNA of a 40-h-old culture of the wild strain. The donor DNA-treated mutant conidia were then grown on plates containing minimal medium at 28 degrees C for 4 days. The number of transformed cells was estimated by colony counting and hence percentage transformants. The transforming activity of the donor DNA was found to be inhibited by the action of heat and variation of pH, and also varied with the period of starvation and with the concentration of donor DNA.
Aspergillus ochraceus↗
Prognostic significance of circulating immune complexes in malignant tumours of head and neck.
Circulating immune complexes (CIC) were estimated in 31 cases of head and neck malignancies by polyethylene glycol (PEG) precipitation and latex agglutination inhibition (LAI) techniques. Results were compared with 25 age and sex-matched control volunteers. Seropositivity for CIC by PEG precipitation test was 54.83% compared to 61.29% by LAI test. No positive case was detected in control group. Seropositivity for CIC by combination of both test results was 67.74%. In stage I cancer seropositivity for CIC by both techniques was 33.33%. In stage II it was 36.36% by PEG precipitation test and 45.45% by LAI test. In stage III it was 64.28% by PEG precipitation test and 71.42% by LAI test. In stage IV all cases were seropositive by both techniques. LAI test was more sensitive in CIC detection in cancer stages II and III. PEG precipitation test had the advantage of detecting quantitative CIC levels by PEG index. Follow-up in 10 postoperative cases revealed significant decline in CIC levels by both tests (p < 0.01) after 3 months of surgery; 90% patients became seronegative for CIC by PEG precipitation technique while 80% became seronegative by LAI technique. However, 15 patients were followed up after 3 1/2 years of surgery; 75% patients remained seronegative while 25% patients became seropositive by both tests and manifested clinical recurrences.
Adult↗
Serum calcium, magnesium and inorganic phosphorous levels during various phases of menstrual cycle.
Serum Calcium (Ca), Magnesium (Mg) and Inorganic phosphorous (Pi) were investigated serially during menstrual, follicular, ovulatory and luteal phases of menstrual cycle in 25 healthy medical student volunteers. The result shows significant cyclic variations within physiological limits in all parameters. Ca level was highest during ovulation (P < 0.001) and lowest during luteal phase (P < 0.001) compared to other phases. Exactly opposite result was observed for Ca level. It is lowest during ovulation (P < 0.001) and highest during the luteal phase (P < 0.001). However, the highest level of Pi was seen during menstrual phase (P < 0.001) and lowest during the luteal phase (P < 0.001). These changes are probably brought about under the influence of cyclic variations of the ovarian hormones.
Adolescent↗
Conformational change due to reduction of cytochrome-c oxidase in lauryl maltoside: picosecond time-resolved tryptophan fluorescence studies on the native and heat modified enzyme.
Detailed fluorescence studies on bovine heart cytochrome-c oxidase (CcO) has been carried out in lauryl maltoside solution. Steady-state fluorescence of the tryptophan residues of the enzyme showed that the fluorophores are embedded deep inside the hydrophobic protein cavity. Time resolved studies of tryptophan fluorescence of native and heat treated CcO have been carried out in both reduced and oxidised forms using synchronously pumped pulsed picosecond dye laser and single photon counting technique. Decay of the tryptophan fluorescence have been fitted using discrete four exponential model. Amplitude distribution of lifetimes also showed four distinct regions in the analysis of the decay profiles by maximum entropy method (MEM). The results indicate that controlled heat treatment of CcO affects the conformation of the enzyme near the active centers which makes it incapable of active proton pumping while the electron transfer property is still conserved. Reduction of the native CcO is associated with a large conformation change in lauryl maltoside near the active centers which is not observed in case of CcO encapsulated in vesicles. Reduction of the heat treated enzyme was found to have a conformation different from the reduced native CcO.
Electron Transport Complex IV↗
Toxic effects of chronic fluoride ingestion on the upper gastrointestinal tract.
In a prospective case controlled study, we evaluated the adverse effects of long-term fluoride ingestion on the gastrointestinal tract. Ten patients with otosclerosis who were receiving sodium fluoride 30 mg/day for a period of 3-12 months, and 10 age- and sex-matched healthy volunteers were included. They were all evaluated clinically and subjected to a real time ultrasound examination, upper gastrointestinal endoscopy, and biopsies from the gastric antrum and duodenum. The biopsies were subjected to a rapid urease test as well as light and electron microscopic examinations. Ionic fluoride was estimated in the serum, urine, and drinking water using an ION 85 Ion Analyzer. Seven subjects (70%) ingesting fluoride had abdominal pain, vomiting, and nausea. Petechiae, erosions, and erythema were seen on endoscopy in all the subjects, but not in the controls. Histological examination of the gastric antral biopsy showed chronic atrophic gastritis in all the subjects but in only one (10%) healthy volunteer. Scanning electron microscopic examination showed "cracked-clay" appearance, scanty microvilli, surface abrasions, and desquamated epithelium in the subjects ingesting fluoride, but not in the controls. We conclude that long-term fluoride ingestion is associated with a high incidence of dyspeptic symptoms as well as histological and electron microscopic abnormalities.
Adolescent↗
Time-resolved study of tryptophan fluorescence in vesicle reconstituted cytochrome oxidase. Effect of redox transition.
Time-resolved study of fluorescence decay of the tryptophan residue in bovine cytochrome c oxidase in phospholipid vesicles is reported for the first time. The effect of the redox state of the protein on its conformation has been investigated using time-resolved decay of tryptophan fluorescence in the oxidised and reduced protein. The fluorescence decay was best fitted using a discrete three exponential model. Amplitude distribution of lifetimes also showed three distinct regions in the analysis of decay profiles by the maximum entropy method (MEM). Results of the time resolved studies showed that the amplitudes as well as the lifetimes of the tryptophan fluorescence remain the same for the oxidised and the reduced states of cytochrome c oxidase, indicating that the environment around tryptophan residues remains more or less unaltered on reduction of the protein. The results suggest that there is no global conformational change in the protein on electron transfer and support the possibility of the existence of local fluctuations in the protein during the redox cycle.
Animals↗
Effect of long-term administration of sodium fluoride on plasma calcium level in relation to intestinal absorption and urinary excretion in rabbits.
The present study was undertaken to determine the effect of chronic fluoride toxicity on calcium metabolism. Rabbits (n = 10) were orally administered an aqueous solution of 10 mg NaF/kg body wt daily for 18 months. Equal numbers (n = 10) of age-, sex- and weight-matched rabbits kept under identical laboratory conditions, but not treated, with NaF solution, served as control. The fasting plasma calcium concentrations of fluoride-treated rabbits were significantly lower (P < 0.001) than those of control animals. In contrast to the decrease in plasma calcium level, and increase in intestinal radioactive calcium (45Ca) absorption was observed (P < 0.001) in all fluoride-treated animals. However, urinary calcium excretion levels were found to be reduced (P = not significant) in fluoride-treated rabbits. It is therefore concluded that long-term fluoride poisoning alters the calcium homeostatic mechanism, thereby affecting calcium metabolism.
Animals↗
Effect of cigarette smoking on maternal airway function during pregnancy.
The effects of cigarette smoking on maternal airway function during pregnancy were investigated in a cross-sectional study of 97 smokers and 175 nonsmokers at different gestational ages. The groups were comparable in age, height, and weight. All subjects were healthy. Forced vital capacity, forced expiratory volume in 1 second, their ratio, the forced expiratory flow rates between 0.2 and 1.2 L, 25% and 75%, and 75% and 85%, and instantaneous flows at lung volumes of 25%, 50%, and 75% were measured. All spirometric tests were unaffected by gestational age. However, all parameters of spirometry were significantly less in smokers than in nonsmokers when cumulative data during pregnancy were compared. Forced vital capacity, forced expiratory volume in 1 second, and their ratio were minimally reduced (4%, p less than 0.05; 8%, p less than 0.001; and 4%, p less than 0.001; respectively) in smokers as compared with nonsmokers. Larger reductions were noted in forced expiratory flow rates between 0.2 and 1.2 L (14%, p less than 0.001) and between 25% and 75% (16%, p less than 0.001), and in instantaneous maximum flows at lung volumes of 75% (11%, p less than 0.001) and 50% (13%, p less than 0.001). Maximum reduction of forced expiratory flow rates between 75% and 85% (26%, p less than 0.001) and in instantaneous flows at maximum lung volumes of 25% (23%, p less than 0.001) suggests marked increases in small-airway resistance and early small-airway disease in smokers. The progression of small-airway disease is related to the level of cigarette exposure. The results of our study demonstrate that the bronchodilatory effect expected in pregnancy is not sufficient to overcome the deleterious effects of cigarette smoking.
Adult↗
Maternal airways function during normal pregnancy.
Forced vital capacity, Forced expiratory volume in 1 second, expiratory flow rates and V max at different lung volumes were statistically unchanged during the course of pregnancy compared to non pregnant control group. There was no restrictive or obstructive defects during the course of pregnancy despite the added mechanical load to the respiratory apparatus by the gravid uterus.
Adolescent↗
Basal oxygen consumption during different phases of menstrual cycle.
Basal oxygen consumption was measured serially in 32 women aged 17 to 28 yr, during the menstrual, follicular and luteal phases of the menstrual cycle, using Benedict-Roth Metabolism Apparatus. The mean (+/- SD) total body oxygen consumption was found to be 166.54 +/- 13.904, 166.24 +/- 13.688 and 176.51 +/- 14.780 ml/min during the menstrual, follicular and luteal phases respectively. The oxygen consumption was significantly higher (P less than 0.001) in the luteal phase as compared to the other two phases whereas it was almost identical in the menstrual and follicular phases. The rise in oxygen consumption was found to be a post-ovulatory phenomenon possibly mediated through hormones, mainly progesterone. This rise in oxygen consumption was mainly metabolic and related to the pattern of food intake behaviour during the menstrual cycle.
Adolescent↗
Loss of penicillin resistance in Paracoccus denitrificans induced by mitomycin C and acridine orange.
In an attempt to eliminate the penicillin resistance gene of P. dentrificans by curing agents, such as acridine orange (AO) and mitomycin C, it was observed that AO treatment caused temporary phenotypic curing where development of sensitivity was a function of concentration of both the curing agent and benzylpenicillin. However, curing with mitomycin produced sensitive clones at a frequency of 6 X 10(-3) and two permanently cured clones were isolated. Heavy metal resistance and resistance to other drugs, however, remain unchanged in the mitomycin-cured isolate.
Acridine Orange↗
Effect of treatment with botulinum toxin on spasticity.
Botulinum toxin, a product of Clostridium botulinum, produces presynaptic neuromuscular block by preventing release of acetylcholine from nerve endings. The toxin was injected directly into the skeletal muscles of six patients with severe spasticity due to stroke-related hemiplegia. It produced both subjective and objective improvement. The toxin injections were well tolerated and no significant side effect was reported.
Adult↗
Botulinum toxin in treating spasticity.
The value of locally injected botulinum toxin is emphasised. The toxin was injected directly into the skeletal muscles of eight patients with severe spasticity due to stroke-related hemiplegia. It produced both subjective and objective improvement. The toxin injections were well tolerated and no significant side effects were noted.
Adult↗
Spectrophotometric determination of clioquinol and diodoquin in pharmaceutical preparations using uranyl acetate as a chromogenic agent.
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Clioquinol↗
Circulating levels of sialic acid and glycosaminoglycans: a diagnostic test for ankylosing spondylitis.
The circulating levels of sialic acid (N-acetylneuraminic acid) and glycosaminoglycans (GAGs) were measured in 69 patients with spinal disorders of orthopaedic interest (ankylosing spondylitis 17, osteofluorosis 6, idiopathic backache 10, osteoarthrosis 16, osteoporosis 20). The serum GAG levels showed no statistically significant change from control values in the five disorders investigated in the present study. Although osteoporosis and osteoarthrosis showed a decrease in serum sialic acid (SA) levels, the mean ratio (SA/GAG) demonstrated no change from control values. Idiopathic backache showed no difference in any of the parameters studied when compared with control values. Ankylosing spondylitis and osteofluorosis had a remarkable similarity in their clinical and radiological features, but a divergent mean value of ratio was noted. The mean ratio of both the conditions also showed a statistically significant difference from the control value. This suggests that the SA/GAG ratio can be used as a diagnostic test in ankylosing spondylitis.
Adolescent↗
Chronic fluoride toxicity: a scanning electron microscopic study of duodenal mucosa.
The effects of chronic fluoride toxicity on duodenal mucosa of rabbits were investigated using scanning electronmicroscope on materials obtained from rabbits subjected to oral administration of sodium fluoride at the dose of 10 mg/kg body weight per day for a period of 24 months. Significant morphological abnormalities were observed in the mucosa of all the fluoride treated animals [n = 9] when compared to that of control rabbits. The surface of the microvilli of duodenal epithelium revealed a "cracked-clay" appearance in fluoride treated rabbits. Besides, abrasion on the villus surface due to epithelial cell degeneration was also noticed. Mucus probably coating the degenerated cells formed strands over the villi in fluoride treated animals.
Animals↗