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Biomedical subjects

V Patel

Publications and source records attributed to V Patel.

At least 217 records · Page 12Linked to original sources
PubMed1986

Hydrophobic interaction chromatography of incompletely methylated transfer RNA from Escherichia coli on octyl-sepharose.

Phenylalanine-specific transfer RNA from methionine-starved relaxed Escherichia coli K12 separates into two components when chromatographed on Octyl-Sepharose. The difference in elution between the two tRNAs has been shown to depend on the methyl group in the highly modified 2-methylthio-N-6-isopentenyladenosine. The first eluted tRNAPhe lacks this methyl group, while the last eluted tRNAPhe is fully methylated. Other differences in the modification patterns have no effect on the elution from Octyl-Sepharose. The elution pattern of tyrosine- and serine-specific tRNAs, also normally containing ms2i6A, is similar.

Amino Acyl-tRNA Synthetases↗
PubMed1986

Early exposure to delta 9-tetrahydrocannabinol influences neuroendocrine and reproductive functions in female rats.

Sexual differentiation of the rat brain is affected by certain compounds administered during the neonatal period. We evaluated the effects of exposure to THC during the critical period of sexual differentiation of the female rat brain on postpubertal estrous cycles and brain neurotransmitter levels. Newborn female rats were injected either with vehicle (oil) or with different doses of THC (0.38; 1.9 or 3.8 mg/100 g) subcutaneously during the first 5 days after birth. The rats were examined daily by vaginal lavage smears from 3 to 10 months of life for phases of estrous cyclicity. The animals were then sacrificed and the anterior hypothalamus preoptic area (AHPOA) and medial basal hypothalami (MBH) were collected, processed and the methionine-enkephalin (met-enkephalin), beta-endorphin-like immunoreactivity (beta-end LI), LHRH and substance-P were measured by radioimmunoassays. In addition, serum LH and prolactin levels were measured by radioimmunoassay. Compared with the control rats, the rats perinatally exposed to THC exhibited either constant metestrus diestrus type vaginal smears or irregular estrous cycles. In the THC-treated animals, the met-enkephalin and beta-end LI levels were lower in the AHPOA and higher in the MBH. The LHRH levels of THC-treated rats were significantly lower in the MBH. The substance-P levels were significantly lower in the AHPOA of THC treated animals. In the THC-treated rats, serum LH was low but, the prolactin levels were not significantly different from the control animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Surgical problems in the management of giant fibroadenoma of the breast.

Giant intracanalicular fibroadenoma is reported to be the most common cause of a massive, deforming enlargement of one breast in the female adolescent. It occurs infrequently and has a varied histopathologic pattern. It is suggested that obstetricians and gynecologists should have an awareness of this potentially malignant tumor of the breast with its associated problems of diagnosis and surgical management. Consideration of these huge breast tumors in relation to other similar breast lesions is presented in order to emphasize differential characteristics and treatment.

Adolescent↗
PubMed1985

Effect of delta 9-THC on brain and plasma catecholamine levels as measured by HPLC.

The effects of chronic administration of delta 9-tetrahydrocannabinol (delta 9-THC) on the plasma and brain catecholamine (CA) levels were measured using high performance liquid chromatography-electrochemical detection (LC-EC) system. Intact male rats were injected daily with vehicle (50 microliter oil) or with delta 9-THC (3 mg/kg body wt) over a period of 25 days. Trunk plasma and tissue from preoptic area (POA) and mediobasal hypothalamus (MBH) were collected and catecholamine levels were detected by LC-EC system coupled to an electronic integrator. Alumina extract of tissue and plasma samples, spiked with the internal standard (dihydroxybenzylamine), were injected into the LC-EC system; the CA were chromatographed and eluted within 12 minutes using sodium phosphate buffer as the mobile phase. delta 9-THC treatment resulted in a significant decrease in plasma and MBH levels of norepinephrine (NE), epinephrine (E), POA levels of NE; and significant increases in MBH levels of dopamine (DA) and dihydroxyphenylacetic acid (DOPAC). Our study indicates for the first time that delta 9-THC treatment significantly alters not only the POA and MBH CA levels, but also the plasma CA levels.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1985

The effect of an academic examination on salivary norepinephrine and immunoglobulin levels.

Forty-six college students provided saliva samples just after taking an examination, one hour and 45 minutes later, and several days later, at a period of rest. As compared with baseline levels, the power stress of an examination was associated with an increase in salivary immunoglobulin A (S-IgA), a measure of B-cell immune function, and with an increase in norepinephrine (NE) concentrations in the saliva. The increase in NE was greater for those for whom n power was greater than n affiliation rather than for those for whom the reverse was true. Greater increases in, and levels of, NE at the examination and after were associated with greater subsequent drops in S-IgA, which reached below baseline levels for those for whom n power was stronger. The examination stimulated adrenergic activity, which in the long run depressed immune function for those with a strong power motive who had been most aroused adrenergically by the examination.

Achievement↗
PubMed1985

Inactivation of the beta-adrenergic receptor in cardiac muscle by dithiols.

The effect of sulfhydryl reagents on binding of the beta-adrenergic antagonist (-)-[3H]dihydroalprenolol hydrochloride [-)-[3H]DHA) to a microsomal fraction of rabbit ventricular muscle was studied. Incubation with the disulfide reducing agents dithiothreitol (DTT), 2-mercaptoethanol, and reduced glutathione resulted in loss of (-)-[3H]DHA binding. At 500 microM DTT, less than 50% of specific binding activity remained; at 100 mM, binding was completely eliminated. 2-Mercaptoethanol and reduced glutathione were less effective than DTT at inhibiting binding activity. The total binding capacity (Bmax) decreased from 155.4 fmol mg-1 of protein, in the absence of DTT, to 92.4 and 77.5 fmol mg-1 at 0.25 and 0.7 mM DTT, respectively. The equilibrium dissociation constant (KD) increased from 7.6 nM, in the absence of DTT, to 10.3 nM at 0.25 mM DTT and to 20.8 nM at 0.7 mM DTT. Thus, DTT-induced decline in (-)-[3H]DHA binding results from a decrease in both the number and affinity of membrane binding sites for the tracer. Receptors could be protected from DTT inactivation by preincubation with beta-adrenergic ligands. Oxidants could not reverse inactivation, with the exception of o-iodosobenzoate which was only partially effective. Thus, the beta-adrenergic receptor of rabbit ventricular muscle contains essential disulfide moietie(s) which can be inactivated by reducing thiols.

Animals↗
PubMed1985

A monokine stimulates production of human erythroid burst-promoting activity by endothelial cells in vitro.

Conditioned media were prepared from human peripheral blood monocytes and human umbilical vein endothelial cells. These media were assayed for erythroid burst-promoting activity (BPA) using human peripheral blood monocyte-depleted mononuclear cells as targets and assessing the stimulatory effect of the conditioned media on growth of early erythroid progenitor cells. Both monocytes and endothelial cells produced modest amounts of detectable BPA. Addition of varying concentrations of media conditioned by monocytes to plateau concentrations (5-10%) of media conditioned by endothelial cells had no additive effect. Endothelial cells incubated in the presence of 50% monocyte-conditioned medium produced 2.5- to 6.6-fold more BPA than did endothelial cells incubated only in control tissue culture medium. In contrast, endothelial cell conditioned medium did not stimulate increased BPA production by monocytes. Neither neutrophil- nor marrow fibroblastoid cell-conditioned medium stimulated BPA production by endothelial cells. Therefore, both monocytes and endothelial cells produce BPA. Moreover, monocytes produce a monokine that, in turn, stimulates the production of BPA by endothelial cells. Inasmuch as a monokine also has been shown to stimulate production of granulocyte-macrophage colony-stimulating activity, we propose that monocytes play a critical role in regulating the production of humoral regulators of the very early stages of hemopoietic cell differentiation.

Culture Media↗
PubMed1985

Effects of acute and subchronic delta 9-tetrahydrocannabinol administration on the plasma catecholamine, beta-endorphin, and corticosterone levels and splenic natural killer cell activity in rats.

The effect of acute (1 day) or subchronic (25 days) treatment with delta 9-tetrahydrocannabinol (THC), the major psychoactive constituent of marihuana, on plasma norepinephrine (NE), epinephrine (E), corticosterone, beta-endorphin (beta-end), and splenic natural killer (NK) cell activity of the rat was studied. Groups of animals received subcutaneously, either THC in corn oil + saline (3 mg THC/kg); oil + saline; or THC + naloxone (2 mg naloxone/kg and 3 mg THC/kg). Acute injection of THC with or without naloxone did not significantly change plasma levels of NE, E corticosterone, beta-end, or the NK cell activity. However, subchronic treatment with THC significantly reduced plasma levels of NE, E, corticosterone, and NK cell activity, compared to controls. The plasma beta-end levels were significantly elevated in the THC-treated animals. In the THC + naloxone group of animals, the plasma hormone levels (corticosterone and beta-end) were similar to control levels and the NK cell activity was significantly higher than in THC-treated animals. These results indicate that subchronic exposure to THC results in suppression of splenic NK cell activity. The interaction of THC with the endogenous opiate system appears to be a contributing factor leading to the NK cell suppression in rats. A direct suppressive action of THC or its metabolites on the NK cell is not ruled out by this study.

Animals↗
PubMed1984

Computed tomography of intraabdominal abscesses.

A total of 78 patients were subjected to computed tomography (CT) over a period of 18 months. CT proved extremely accurate in the diagnosis of intraabdominal abscesses and in estimating the extent of spread. The series included many examples of amoebic and hydatid abscesses with unusual presentations and appearances. The commonest appearance of abscesses on CT was a low-density mass with peripheral rims after the administration of intravenous contrast media, followed by gas-containing low-density lesions which were regarded as showing characteristic features of abscess formation. Pitfalls in the CT appearance of abdominal abscesses were many and correlation with the clinical presentation was essential for diagnosis. The greatest value of CT lay in the rapidity of diagnosis.

Abdominal Muscles↗
PubMed1984

The syndromes of pancreatic pseudocysts and fluid collections.

The clinical and radiologic spectrum of pseudocysts associated with alcohol-induced pancreatitis is wide and variable. Several illustrative cases which delineate the diversity of syndromes that occur with pseudocysts are presented. A classification is proposed to facilitate a more coherent approach to the concept of pseudocysts and is based on the clinical presentation. Thus, in acute pancreatitis duct disruption and enzyme activation may result in intrapancreatic or extrapancreatic fluid collections. In calcifying chronic pancreatitis duct obstruction may result in pseudocysts of the head, body, or tail of the pancreas, which can enlarge and penetrate into extrapancreatic sites. This subdivision will assist in elucidating the natural history of pseudocysts and pancreatic fluid collections. Furthermore, it may establish new guidelines for diagnosis and therapy.

Adult↗
PubMed1984

The spread of oesophageal cancer: an evaluation of clinical, barium and computed tomography assessments.

One hundred and three patients with proven oesophageal cancer were evaluated prospectively by clinical examination, upper gastro-intestinal barium studies and computed tomography (CT). The accuracy of each method in assessing the extent of disease was determined by correlation with findings at bronchoscopy (100 patients), thoracotomy (26 patients) and laparotomy (63 patients). The results indicated that CT will accurately demonstrate mass invasion of cancer into mediastinal structures. But the absence of fat-planes on CT is the least reliable indication of spread into peri-oesophageal soft tissues. Early mediastinal infiltration is best assessed by analysis of the oesophageal axis on barium swallow and the patient's symptoms. Computed tomography is not helpful in the diagnosis of mediastinal node metastases. Barium studies of the proximal stomach will accurately identify (and CT reliably exclude) local tumour extension into the stomach. CT can frequently fail to detect malignant abdominal lymphadenopathy in cachexic patients.

Abdominal Neoplasms↗
PubMed1984

Effect of chronic administration of delta 9-tetrahydrocannabinol on the endogenous opioid peptide and catecholamine levels in the diencephalon and plasma of the rat.

The effect of chronic administration of delta 9-tetrahydrocannabinol (delta 9-THC) on the endogenous opiate and catecholamine levels was investigated. Intact male rats were injected daily either with vehicle (50 microliters oil) or delta 9-THC in oil (3 mg delta 9-THC/kg body wt). The treatments were administered subcutaneously over a period of 25 days. All animals were decapitated after the last injection and trunk plasma was assayed for prolactin, beta-endorphin-like immunoreactivity (beta-end LI), norepinephrine (NE), epinephrine (E), dihydroxyphenyl acetic acid (DOPAC) and dopamine (DA). The preoptic area (POA) and medial basal hypothalamus were assayed for methionine enkephalin, beta-endorphin and catecholamines. Chronic delta 9-THC treatment resulted in an increase in POA and MBH methioine-enkephalin and beta-end LI as well as an increase in plasma beta-end LI. The POA, MBH and plasma NE and E levels were lower in these animals when compared with the controls. In the MBH, however, the delta 9-THC treated rats contained higher DA and DOPAC levels when compared with the controls. These results support our view that chronic delta 9-THC administration alters the activities of the endogenous opiate system as well as the catecholaminergic system and consequently impairs the endocrine functions.

Animals↗
PubMed1984

Enhanced T helper cell function for the spontaneous production of IgM rheumatoid factor in vitro in rheumatoid arthritis.

Co-culture experiments between T and B cells from normal subjects and rheumatoid arthritis (RA) patients were performed in order to assess the immunoregulatory effects of T cells on spontaneous production of IgM rheumatoid factor (IgM-RF). Cultures of normal B cells with normal, autologous or allogeneic T cells failed to synthesize IgM-RF. In contrast, RAT cells promoted IgM-RF production from normal B cells as well as from RA B cells. The 'helper' effect of T cells from RA patients for IgM-RF production was not HLA-DR4 restricted and could not be accounted for by an allogeneic effect. These observations suggest that activated T helper cells may contribute to the production of IgM-RF in RA.

Arthritis, Rheumatoid↗
PubMed1983

CT appearance of bladder malakoplakia.

The computed tomographic (CT) findings of malakoplakia of the bladder are presented. Although the CT findings were not considered specific for this condition, the presence of a solid bladder mass with or without extension beyond the confines of the bladder in a young woman with urinary tract infection should suggest the possibility of this diagnosis.

Adult↗