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Biomedical subjects

N Jain

Publications and source records attributed to N Jain.

At least 109 records · Page 6Linked to original sources
PubMed1993

The influence of rearranged T cell receptor alpha beta transgenes on early thymocyte development.

Most murine thymocytes and mature T cells originate from a numerically minor population of CD8-4- (double-negative, DN) thymocytes. In this study, we investigated the effects of rearranged T cell receptor (TcR) alpha and beta transgenes on early T cell development. We analyzed the precursor potential, the expression of CD25 and TcR at mRNA and/or protein level in DN thymocyte subsets in TcR transgenic (Tg) mice. We report the following observations: (i) despite a large overrepresentation of total DN cells in TcR Tg mice, precursor-containing CD25+ DN and CD8lo4lo thymocytes are reduced to a third of the nontransgenic control numbers; (ii) like in the normal mice, CD25+ DN and CD8lo4lo can, and TcR+ DN cells cannot generate other thymic subsets; (iii) TcR alpha mRNA and TcR alpha/beta protein levels are quantitatively increased, but their developmental expression is similar to that in normal mice; and (iv) surface TcR alpha beta expression becomes detectable as the thymocytes down-regulate CD25, paralleling the situation in normal mice. Our findings implicate stringent transcriptional control, rather than TcR gene rearrangement, as a decisive regulator of TcR alpha beta expression in early ontogeny.

Animals↗
PubMed1993

Ontogeny of fetal CD8lo4lo thymocytes: expression of CD44, CD25 and early expression of TcR alpha mRNA.

CD8lo4lo cells are the immediate precursors of immature CD8hi4loTcRlo, CD8lo4hiTcRlo and CD8hi4hiTcRlo double-positive (DP) thymocytes in the adult murine thymus. These cells are the first subset in the adult thymus to express accessory CD8 and CD4 molecules, to rearrange the T cell receptor (TcR) alpha chain genes and to express the TcR alpha beta heterodimer at low levels at the surface. Here, we investigate the fetal ontogeny of CD8lo4lo cells. We detect these cells on day 15 of fetal development. They dominate the thymus on day 15.5, to become progressively less prominent thereafter. An important characteristic of fetal CD8lo4lo cells is the early expression of TcR alpha mRNA (on fetal day 15, 36-48 h earlier than reported previously). Our results also suggest, but do not prove, that the receptor may be expressed on the surface as early as day 15.5. Fetal CD8lo4lo cells, like their adult counterparts, become DP in vitro. However, early fetal CD8lo4lo thymocytes express both CD44 and CD25--unlike the adult subset--and that links them to their putative precursors, fetal CD44+CD25+ double-negative cells. This finding underscores the difference between adult and fetal thymocytes in turnover of membrane molecules and/or the kinetics of progression through phenotypic stages.

Animals↗
PubMed1993

Plasma levels of luteinizing hormone in intact and castrated photosensitive blackheaded buntings (Emberiza melanocephala) exposed to stimulatory and nonstimulatory photoperiods.

Experiments were performed to investigate the effects of castration and/or photostimulation on plasma luteinizing hormone (LH) in photosensitive blackhead buntings. Castration evoked a significant rise in plasma LH in birds held under 8 h light: 16 h darkness (8L:16D). On exposure to 18L:6D for 24 d, both the intact birds and the castrates exhibited a significant rise in plasma LH, although the change in LH levels in the castrates was approximately 8 times greater than in the intact birds. When control birds under 8L:16D which showed no change in plasma LH up to d 13 were transferred to a 36-h resonance cycle (8L:28D), plasma LH rose significantly within 4 cycles of the treatment. Furthermore, the intact buntings showed rapid increase and decrease in the plasma LH levels during a 16-wk exposure to long (16L:8D) but not to short (8L:16D) photoperiods. These results suggest that: i) the photoperiodic drive on LH secretion is inhibited by the testes; ii) the blackheaded bunting has a strong photoresponsive system; and iii) a circadian rhythm of photosensitivity is involved in the photoperiodic time measurement in this species.

Animals↗
PubMed1993

Parallel regulation of procollagen I and colligin, a collagen-binding protein and a member of the serine protease inhibitor family.

A potential regulatory linkage between the biosynthesis of colligin, a collagen-binding protein of the ER, and procollagen I was examined under a variety of experimental conditions. Cell lines which did not produce a significant amount of procollagen I mRNA also lacked the capacity to produce colligin mRNA. Anchorage-dependent cell lines like L6 myoblasts and normal rat kidney fibroblasts produced both colligin and procollagen I mRNA, but the level of both was concurrently reduced considerably in their ras-transformed counterparts. Similarly, during the differentiation of L6 myoblasts, levels of both colligin and procollagen declined together. Treatment of myoblasts by dexamethasone or EGF led to a decrease in the steady-state levels of procollagen I mRNA, and this was, again, accompanied by a decrease in colligin mRNA synthesis. On the other hand, when the rate of procollagen I synthesis was stimulated by treatment of myoblasts with TGF beta, it led to the concurrent augmentation of both the mRNA and protein levels of colligin. A linkage between the regulation of synthesis of procollagen I and colligin thus seems to exist. The only exception to this generalization is provided by the heat induction behavior of the two proteins. Treatment of myoblasts for a very short period leads to an increase in the synthesis of both the mRNA and protein levels of colligin. This, however, is not accompanied by a change in the mRNA levels of procollagen I. These studies establish that colligin and procollagen are generally tightly co-regulated except after heat shock, suggesting an important functional linkage.

Animals↗
PubMed1993

Gastric acid secretion in typhoid fever.

Gastric acid secretion was studied in 20 patients with typhoid fever (Group A), ten patients with fever other than typhoid (Group B), and ten healthy adults of matched age and sex (Group C). Patients with typhoid showed reduced acid secretion at the time of fever and one week after subsidence of fever as compared to Group C. In uncomplicated patients (Group A1), these values rose thereafter but in complicated patients (Group A2) they remained low even 12 weeks after subsidence of fever. This suggests that these patients had pre-existing hypochlorhydria which predisposed them to a severe form of disease. There may be many factors playing a significant role in making typhoid patients more prone to develop complications but the importance of gastric acid levels has also to be considered.

Adolescent↗
PubMed1993

The protein CD63 is in platelet dense granules, is deficient in a patient with Hermansky-Pudlak syndrome, and appears identical to granulophysin.

The levels and expression of the proteins CD63 and granulophysin in platelets from control and from a Hermansky-Pudlak syndrome subject (a condition characterized by dense granule and lysosomal deficiencies and the accumulation of ceroid-like material in reticuloendothelial cells) were examined. Immunofluorescence studies indicated that anti-CD63 and anti-granulophysin antibodies recognized similar numbers of granules; coapplication of antibodies did not identify more granules than the individual antibodies. Significantly fewer granules were recognized in Hermansky-Pudlak syndrome platelets than in control using either antibody. Immunoblotting studies demonstrated that anti-CD63 and anti-granulophysin antibodies apparently recognize the same protein, which was deficient in Hermansky-Pudlak platelets. Analysis by fluorescence-activated cell sorter (FACS) showed biphasic expression of CD63 and granulophysin after thrombin stimulation of control but not Hermansky-Pudlak platelets. Anti-CD63 effectively blocked detection of the protein by anti-granulophysin using immunofluorescence, ELISA, immunoblotting, and FACS analysis. Amino-terminal sequencing over the first 37 amino acids revealed that granulophysin was homologous to CD63, melanoma antigen ME491, and pltgp40. These results suggest that granulophysin and CD63 are possibly identical proteins. This is the first report of a protein present in platelet dense granules, lysosomes, and melanocytes, but deficient in a patient with Hermansky-Pudlak syndrome.

Adult↗
PubMed1993

Chloramphenicol resistant enteric fever.

In recent times there have been several reports of chloramphenicol resistant enteric fever necessitating the use of other antimicrobial agents. Clinical profile of 15 chloramphenicol resistant patients of enteric fever was studied. Three such patients (20%) responded to chloramphenicol despite in vitro resistance to the drug. Hence chloramphenicol still remains the drug of first choice in enteric fever as a majority (68.4%--26 out of 38) of our bacteriologically proven enteric fever patients were cured by the drug. The remaining 12 cases responded satisfactorily to ciprofloxacin (46.7%), gentamicin (20%), and ofloxacin (13.3%). There was an increased incidence of complications among the 15 drug resistant cases as compared to 23 cases of chloramphenicol sensitive enteric fever observed during the same period.

Adolescent↗
PubMed1992

Synthesis, characterization, cytotoxicity and DNA binding studies of diamminediethyldithiocarbamato-platinum(II) nitrate.

A new complex [Pt(NH3)2(ddtc)]NO3.2H2O as a 1:1 electrolyte has been prepared. This was characterized by spectroscopic methods. The electronic absorption spectrum of this complex in water suggests that it has a square planar geometry. The infrared, 1H NMR and x-ray photoelectron spectroscopic studies suggest the bonding of ammonia molecules and diethyldithiocarbamate as bidentate ligand to platinum(II) in this complex. The 50% inhibition value of this complex against P388 lymphocytic leukemia cells is comparable with cisplatin. This complex interacts with calf thymus DNA by coordinate covalent bond.

Animals↗
PubMed1992

Idiopathic intracranial hypertension: report of seven cases.

We describe seven patients with idiopathic intracranial hypertension (IIH), a disorder, mostly in young women, characterized by papilledema, elevated cerebrospinal fluid (CSF) pressure, normal CSF composition, and normal neuroradiologic studies. Obesity, the most consistent etiologic association, was present in two of our patients. Hypothalamic compression in IIH may induce increased appetite and result in weight gain. Use of trimethoprim/sulfamethoxazole has been reported to be associated with IIH and was seen in one of our patients. IIH is an important diagnostic consideration in the differential diagnosis for a patient with headache, visual disturbances, and papilledema.

Adult↗
PubMed1991

Cellular composition including lymphocyte subsets in preterm and full term human colostrum and milk.

The cellular composition of colostrum (within 72 hours post partum) and mature milk samples (5th-7th day post partum) from 20 mothers delivering preterm babies and 20 mothers delivering full term babies was examined. Lymphocyte subsets including T cells, B cells, T4 and T8 cells were quantitated by indirect immunoperoxidase staining using specific monoclonal antibodies. The mean total cell count in preterm colostrum (9,338/mm3) was significantly higher than in full term colostrum (5,594/mm3). Similarly, counts for macrophages, neutrophils and lymphocytes were significantly higher in preterm colostrum and milk as compared to full term colostrum and milk. B and T lymphocytes including T4 and T8 cells were identified in both preterm and full term breast milk. The absolute count of T, B, T4 and T8 cells was significantly higher in preterm colostrum compared to term colostrum, though the relative percentage distribution of lymphocyte subsets showed no significant difference between the two groups. T and B cells constituted about 74% and 26% of total lymphocytes, respectively in preterm as well as full term colostrum and about 69% and 31% in preterm and full term milk. The mean T4/T8 ratio was higher in preterm colostrum than term colostrum, being 1.82 and 1.60 respectively. However, this difference was not significant statistically and did not change statistically in the milk sample.

B-Lymphocytes↗
PubMed1991

Psychosocial aspects of deformed leprosy patients undergoing surgical correction.

A psychosocial study was conducted on 25 randomly selected leprosy patients undergoing corrective surgical procedures for their deformities. High anxiety and depression levels found preoperatively, reduced significantly after operation. Psychiatric assistance is needed for these patients in order to clear their psychic aberrations, create awareness, boost morale and to give self-confidence. Only 50-75% of preoperative expectations were satisfied but that was only in 40% of patients. This calls for a preoperative counselling session with the patients to help them reach the realistic goals that they can achieve. They should be told what benefits surgery can offer them and be made aware of the problems which will persist after operation, such as anaesthesia and analgesia.

Adolescent↗
PubMed1990

Anti-infective factors in preterm human colostrum.

Feeding of the infection prone preterm neonate with concentrated immunologically active ingredients in the form of colostrum may have even more significant clinical implications than in the full term infants. The scarcity of knowledge on anti-infective factors in colostrum of mothers delivering prematurely prompted us to carry out this study. Colostrum was collected and analysed from 25 mothers delivering prematurely (Study group) and 10 delivering at term (Control group). Major anti-infective factors namely IgA, IgG, IgM, lactoferrin and lysozyme were quantitated and total cell, macrophage, lymphocyte and neutrophil counts were performed. The mean concentrations of IgA, lysozyme and lactoferrin of preterm colostrum were significantly higher than in full term colostrum (p less than 0.001). IgG and IgM were found to be similar in both groups. The absolute counts of total cells, macrophages, lymphocytes and neutrophils were found to be significantly higher in the preterm colostrum as compared to the full term colostrum (p less than 0.001). Though in both the groups IgA was the predominant immunoglobulin, the mean percentage of IgA in the study group was significantly higher as compared to the control group. Degree of prematurity did not have any influence on the anti-infective protein levels in colostrum. However total cells and macrophages were significantly higher in colostrum of mothers delivering severely preterm babies.

Adult↗
PubMed1989

Tritium toxicity in postnatally developing mouse brain: neurochemical changes after continuous exposure.

Since tritium may emerge as a major radiopollutant, an attempt has been made to evaluate changes in total cholesterol, phospholipid and glycogen content in the postnatally developing mouse brain from 1 to 6 weeks of age; the exposure, at a dose level of 11.1 kBq (0.3 microCi)/mL of 3H, through maternal drinking water, was from gestation day 15 until the last interval studied (after a maternal priming injection). The brain-to-body weight ratio was increased during postnatal development as compared to that of sham-irradiated controls. The phospholipid concentration decreased significantly in all age groups. By contrast, glycogen content tended to increase from 1 to 5 weeks of age, and cholesterol content increased by 40.35 and 44.75% during the 2nd and 3rd weeks, respectively, and returned to a near normal level at later intervals.

Animals↗