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Biomedical subjects

P Tan

Publications and source records attributed to P Tan.

At least 109 records · Page 6Linked to original sources
PubMed1987

Follistatin specifically inhibits pituitary follicle stimulating hormone release in vitro.

Two forms of purified follistatin, a single-chain polypeptide of mol wt 35,000 (35 Kd) protein, and a related molecule of mol wt 32,000 (32 Kd), which differs from the 35 Kd form in glycosylation or carboxyl terminal truncation, specifically inhibit the release of immunoreactive FSH by primary cultures of rat pituitary cells. Both forms of follistatin and inhibin-A give similar dose-response curves, with identical slopes and maximal effects, suggesting that they may all act through the same mechanism on the pituitary cells. The median effective dose (ED50) of each of the follistatins is 6.2-7.3 ng/ml (1.8 x 10(-10) M), which corresponds to approximately 1/3 of the potency of inhibin. The effect of 35 Kd or 32 Kd follistatin is highly specific for suppressing the release of immunoreactive FSH since there is no demonstrable concomitant effect on the secretion of other pituitary hormones. The effect of follistatins, like that of inhibins, is different from that of the hypothalamic hypophysiotropic factors, requiring greater than or equal to 18 h of incubation in a pituitary monolayer culture system to demonstrate. Coincubation of inhibin and follistatin shows an additive effect in the suppression of FSH release. Pituitary cells exposed to follistatin have significantly less depletion of intracellular FSH (0.01) than those treated with inhibin, indicating that follistatin may act primarily on the suppression of FSH release rather than on both release and synthesis of FSH, as is the case with inhibin.

Animals↗
PubMed1987

Fine-needle aspiration of salivary gland lesions. Comparison with frozen sections and histologic findings.

The results of 171 salivary gland fine-needle aspirates, with subsequent histologic correlation, were compared with those from previous head and neck series and analyzed for diagnostic accuracy. Cytologically, 118 cases were diagnosed as benign; 51, malignant; and two, insufficient for diagnosis. The false-negative rate was 4.7%, and the false-positive rate was 3.5%. Pleomorphic adenoma, mucoepidermoid carcinoma, chronic sialadenitis, and malignant lymphoma were the lesions most frequently misdiagnosed. Corresponding frozen sections (available in 38 cases) showed an exact correlation with the final surgical pathologic diagnosis in 58% of the cases, with no false-positive diagnoses but an 11% false-negative rate.

Adenoma, Pleomorphic↗
PubMed1986

Effect of topically applied flurbiprofen on ultraviolet-induced erythema.

The effect of flurbiprofen, a nonsteroidal antiinflammatory agent, on ultraviolet B-induced erythema was studied in normal volunteers. The effect of various concentrations as well as the effect of multiple applications were evaluated at 4, 8, and 24 hours after irradiation with three MEDs of ultraviolet B. Repeated applications of flurbiprofen during the four- and eight-hour periods following ultraviolet B exposure did not increase the blanching response obtained following a single treatment. A concentration dependent effect of flurbiprofen on blanching was observed with suppression of erythema increasing with increasing concentration of flurbiprofen up to 3%. Further increase in concentration up to 5% offered no added advantage. Significant differences in blanching were also observed at different postirradiation time periods. No cutaneous or systemic complications were reported during the entire study.

Administration, Topical↗
PubMed1984

Interleukin abnormalities in recently active rheumatoid arthritis.

Peripheral blood lymphocytes (PBL) from 14 patients with rheumatoid arthritis (RA) produced increased amounts of interleukin (IL) (p less than 0.05) as measured in a mouse thymocyte assay and showed enhanced proliferation in response to an IL containing supernatant (p less than 0.05) when compared with 9 age matched controls. Both enhanced IL production (p greater than 0.01) and responsiveness (p less than 0.002) were seen exclusively in a subgroup of 7 patients with a recent onset or exacerbation of their disease. PBL from RA patients with equally active disease which had been unchanged for more than 6 months produced and responded to IL normally. There was a direct correlation between IL production and responsiveness (r = 0.69, p less than 0.005). These 2 distinct IL abnormalities appear to reflect disease initiating or exacerbating factors in RA.

Arthritis, Rheumatoid↗
PubMed1983

Evidence for activated peripheral blood T-cells in rheumatoid arthritis.

We have previously demonstrated defective antigen specific T-suppressor (Ts) cell function in the peripheral blood lymphocytes (PBL) from patients with rheumatoid arthritis (RA). Our study was designed to delineate whether diminished Ts activity is due to impaired interleukin (IL) dependent clonal expansion of Ts cells or to prior in vivo activation. Patients with recent onset of RA, or a disease flare, exhibited enhanced IL generation (IL-1 and /or IL-2). Increased proportions of active E-rosettes, elevated spontaneous production of IgM, and total immunoglobulin in mitogen free cultures were consistent with the concept of prior lymphocyte activation in vivo. Our results do not support defective clonal expansion of Ts cells as the basis of deficient IL generation, but do support the concept of in vivo activation of PBM cells in some patients with RA.

Adult↗
PubMed1981

Immunoglobulin production in vitro by peripheral blood lymphocytes in systemic lupus erythematosus: helper T cell defect and B cell hyperreactivity.

Peripheral blood lymphocytes (PBL) from 16 patients with systemic lupus erythematosus (SLE) and 15 healthy control subjects were cultured and immunoglobulin (Ig) production in vitro was measured by immunofluorescent staining for intracytoplasmic Ig, a reverse haemolytic plaque assay to quantify cells secreting Ig and a solid-phase radioimmunoassay for Ig secreted into culture supernatants. Compared with normal PBL, lymphocytes from patients with SLE produced significantly fewer Ig-containing cells, Ig-secretion cells (ISC) and less Ig in supernatants in cultures stimulated by pokeweed mitogen (PWM). These differences were most pronounced during phases of disease activity. Culturing SLE PBL with a supernatant obtained from PWM-activated cultures of normal T lymphocytes partially restored their capacity to produce ISC. This observation suggests a helper T cell defect of SLE lymphocytes. In addition, PBL from patients with active SLE generated more ISC when cultured with Staphylococcus aureus bacteria (S aureus) than with PWM. S. aureus-stimulated cultures of SLE PBL also generated more ISC than PBL from normal individuals. The S. aureus response of SLE lymphocytes did not correlate with disease activity. As S. aureus is a T cell-independent mitogen, the latter observations suggest that in SLE an intrinsic B cell hyperreactivity may be a more persistent defect whereas T cell defects are transitory.

Adolescent↗
PubMed1980

Chromosomal mapping of human creatine kinase (brain type) using human-rodent somatic cell hybrids.

Concordant segregation of human brain-type creatine kinase, CK(BB), expression with nucleoside phosphorylase (NP) expression and the presence of chromosome 14 was observed in 53 independently derived cell hybrids between CK(BB)-positive human cells and CK(BB)-negative rodent cells. Further analysis of 26 subclones of two CK(BB)-positive human-mouse cell hybrids confirmed the positive correlation of CK(BB) expression with NP expression. The results suggest that the gene coding for human CK(BB) can be assigned to chromosome 14.

Animals↗
PubMedDate not supplied

Systemic absorption of epinephrine after endoscopic submucosal injection in patients with bleeding peptic ulcers.

Epinephrine injection is an effective, simple, and economical method of endoscopic hemostasis for bleeding peptic ulcers. We measured catecholamine levels in 18 patients with actively bleeding ulcers (8 gastric ulcers and 10 duodenal ulcers) treated by endoscopic injection. Injection of epinephrine (1:10,000 IU) was given until bleeding from the ulcers stopped. Catecholamine levels were assayed by high-pressure liquid chromatography. Immediately after the injection the plasma level of epinephrine rose by four to five times above the basal level and returned to the baseline in 20 minutes. Norepinephrine levels were not significantly raised in these patients. No cardiovascular complications were seen. Although adverse cardiac events have not been recorded, it seems prudent to monitor these patients closely during and immediately after epinephrine injection.

Absorption↗
PubMedDate not supplied

Clomipramine in the treatment of rapid (premature) ejaculation.

Twenty-three premature ejaculators (PEs) and 11 control subjects were administered 25 mg of clomipramine in a double-blind, placebo-controlled, crossover design study. During 2-week trials, subjects took either the drug or the placebo 4 to 6 hours prior to sexual activity. Daily diary data revealed that, for both groups, orgasmic latency was significantly increased when taking the clomipramine. For the PEs, the average increase in orgasmic latency during intercourse was from less than 1 minute to more than 3.5 minutes. Subjects also participated in two laboratory sessions while on the drug and placebo. During these lab sessions they were exposed to erotic videos with and without the addition of vibrotactile stimulation to the penis. Results from the laboratory data support those from the diaries. Specifically, PEs were significantly less likely to reach orgasm during the lab sessions while on the clomipramine than while on the placebo. Further, they reported a significantly greater sense of control over their orgasm while on the drug. The results of this study, along with previous research, strongly support the value of low doses of clomipramine in the treatment of premature ejaculation, specifically when taken on an as-needed basis as little as 4 hours prior to sexual activity. It is important to note, however, that the beneficial effects of the drug were not uniform across clinical subjects. In this study, those PEs with the shortest orgasmic latencies while on the placebo were the least likely to substantially improve while on the drug. Additional research is necessary to determine whether changes in the timing and dosage of the clomipramine administration can extend the benefits of the drug to those with the shortest latencies.

Adult↗