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Biomedical subjects

K Desai

Publications and source records attributed to K Desai.

At least 19 recordsLinked to original sources
PubMed1991

Isolation of a cellular protein that binds to the human immunodeficiency virus Tat protein and can potentiate transactivation of the viral promoter.

The human immunodeficiency virus type 1 Tat protein is a powerful transactivator of the viral long terminal repeat (LTR). We have identified a cellular protein that strongly binds to Tat and can complement Tat transactivation in rodent cells. The cellular protein of about 36 kDa was isolated from extracts of human cells by Tat peptide-affinity chromatography and can form a complex with Tat in vitro. Tat transactivation is inefficient in rodent cells microinjected or transfected with the reporter plasmid pHIV-LTRCAT plus the Tat-expressing plasmid pCV-1. Remarkably, coinjection of purified 36-kDa protein with pHIV-LTRCAT plus pCV-1 stimulated Tat transactivation 2.7- to 4.9-fold. Taken together, our findings suggest that the 36-kDa protein may be a transcription factor or modulator that is important for efficient Tat transactivation.

3T3 Cells↗
PubMed1991

Bipolar hemiarthroplasty for subcapital fracture of the femoral neck. A prospective randomised trial of cemented Thompson and uncemented Moore stems.

We performed a randomised prospective trial to compare the results of 27 cemented and 26 uncemented bipolar hemiarthroplasties in active patients with displaced subcapital fractures of the femoral neck. After a mean follow-up of 17 months, significantly more of the uncemented group were experiencing pain in the hip and using more walking aids than the patients in the cemented group. The incidence of postoperative complications, the early mortality rate and the operating time and blood loss were not significantly different. Using otherwise identical prostheses the early results were much better with a cemented Thompson stem than with an uncemented Austin Moore stem.

Aged↗
PubMed1991

Osteochondritis dissecans of the knee. A long-term study.

Twenty-two knees with osteochondritis dissecans diagnosed before skeletal maturity were followed prospectively into middle age: 32% had radiographic evidence of moderate or severe osteoarthritis at an average follow-up of 33.6 years; only half had a good or excellent functional result. We found that osteoarthritis was more likely to occur if the defect was large or affected the lateral femoral condyle.

Adolescent↗
PubMed1989

Inhibition of platelet aggregation by abnormal high density lipoprotein particles in plasma from patients with hepatic cirrhosis.

ADP-induced aggregation of normal washed platelets was measured by nephelometry in the presence of plasma high density lipoprotein (HDL) from normal subjects and from 30 patients with hepatic cirrhosis. HDL, at one-eighth of its plasma concentration, inhibited platelet aggregation; the effect of cirrhotic HDL (40% [SD 29%] inhibition) was significantly greater than that of normal HDL (16% [11%]). The mean apolipoprotein E content of cirrhotic HDL was significantly higher than that of normal HDL, and strongly inhibitory HDL contained twice as many apolipoprotein-E-rich particles as weakly inhibitory HDL. Inhibition of platelet aggregation was correlated with the apolipoprotein E content of HDL from patients with cirrhosis.

Adenosine Diphosphate↗
PubMed1989

Rat pancreatic interlobular duct epithelium: isolation and culture in collagen gel.

Interlobular duct fragments from the pancreas of the rat were isolated by collagenase digestion and filtration, embedded in a matrix of rat-tail collagen, and cultured in a 1:1 mixture of Dulbecco's minimal essential and Ham's F12 media supplemented with cholera toxin (CT, 100 ng/ml) and epidermal growth factor (EGF, 10 ng/ml) in addition to supplements used previously, thereby improving the yield of ducts by a factor of two compared with previous results. The ducts were harvested by digestion of the collagen matrix with collagenase and were then dissociated by treatment with EDTA in divalent cation-free salt suspended in collagen and cultured as were the ducts. Numerous cysts appeared as a function of time and some of these enlarged dramatically. Some of the larger cysts exhibited secondary tubular processes extending into the surrounding collagen. The addition of bovine pituitary extract (BPE, 50 micrograms/ml) doubled the number of cysts, whereas omission of serum or CT + EGF reduced the number. BPE or forskolin could substitute effectively for CT. Agents that stimulate (secretin) or inhibit (e.g., ouabain or acetazolamide) fluid-electrolyte secretion in vivo had no effect on the number or average diameter of the cysts. The cysts were 83 to 88% epithelial with the balance of the cells being fibroblastic in appearance. Some cysts consisted only of epithelium. The proliferative capacity of the cystic epithelium was shown by the presence of mitotic figures and by an autoradiographic labeling index of 22 to 30% after a 24-h exposure to [3H]thymidine. The labeling index was reduced by the omission of CT + EGF. Transmission electron microscopy showed that the cysts exhibited morphologic features of duct epithelium in vivo, including apical microvilli, lateral interdigitations of the plasma membrane, and typical cytoplasmic organelles.

Animals↗
PubMed1989

Binding of apoE-rich high density lipoprotein particles by saturable sites on human blood platelets inhibits agonist-induced platelet aggregation.

High density lipoproteins (HDL, d 1.063-1.21 g/ml) are reported to stimulate, to have no effect on, or to inhibit agonist-induced platelet aggregation. We have hypothesized that these conflicting reports might be explained by opposing effects of individual HDL subclasses on platelet aggregability. Physiologic concentrations of HDL3 had little effect on ADP-induced aggregation of washed platelet suspensions, although higher levels were stimulatory. Normal concentrations of HDL2 (0.2-0.4 mg of protein/ml) inhibited aggregation; further fractionation by heparin-Sepharose chromatography identified the particles rich in apolipoprotein E, termed HDL-E, as the major anti-aggregatory subclass. Washed platelets bound radioiodinated HDL-E to a uniform class of saturable sites; they numbered 4,200 per platelet and the KD was 7.9 x 10(-7) M. Binding of HDL-E by platelets, and its anti-aggregatory action, showed a similar rapidity and both occurred within the physiologic concentration range. Moreover, the two processes were independent of the presence of divalent ions and were impaired by chemical modification of the apolipoprotein constituents of HDL-E. We conclude that occupation of cell-surface receptors by HDL-E particles impairs platelet responsiveness to exogenous agonists and that platelet aggregability in the presence of whole HDL may reflect the relative concentrations of the individual subclasses in the particular sample.

Adenosine Diphosphate↗
PubMed1988

To boost or not to boost: decreasing radiation therapy in conservative breast cancer treatment when "inked" tumor resection margins are pathologically free of cancer.

A retrospective study was performed to compare local treatment approaches for 108 treated breasts in 105 patients with Stage I or II breast cancer. Six cases with intraductal carcinoma have shown no evidence of recurrence. The other 102 cases had invasive cancer. In 54 treated breasts in 53 patients, the treatment approach involved surgical resection of the primary tumor, pathological determination of tumor-free "inked" specimen margins and 5000 cGy to the whole breast. Local radiation therapy (RT) boosts to the primary site were not given. This approach produced a 100% local control rate (mean follow-up of 38 months). In 28 treated breasts in 27 patients, the treatment approach involved tumor excision without evaluation of specimen margins followed by RT which included a local boost by either interstitial Iridium-192 implant or electron beam. This approach yielded an actuarial local control rate of 87% at 48 months (mean follow-up of 47 months). The difference in local control rate between the two groups was statistically significant (p less than 0.03). Among patients with clear surgical margins who received a local RT boost, 1 of 9 developed a local recurrence. Among those with tumor involving specimen margins who received a local boost, 1 of 8 developed local recurrence. Local recurrence developed more frequently among patients with poorly differentiated cancers (2 of 11 cases) than among those with other invasive cancers (3 of 91 cases). Comparison of treatment approaches was limited since poorly differentiated cancer was present in 25% of cases with unknown specimen margins, as compared with only 2% of those with clear surgical margins who did not receive a local RT boost. Our preliminary findings suggest that when "inked" primary tumor resection margins are pathologically free of cancer, 5000 cGy whole breast RT appears to be highly effective for local tumor control in patients with Stage I or II disease. Our results are inconclusive as to whether patients with poorly differentiated cancers should receive a local RT boost even when surgical margins are clear.

Actuarial Analysis↗
PubMed1987

Hereditary lecithin-cholesterol acyltransferase deficiency. Case report of a German patient.

Lecithin-cholesterol acyltransferase (LCAT) deficiency was first described in a Norwegian family as an inborn error of metabolism. Altogether, 35 patients in 18 families have been identified. The authors report the first German patient, who presented with the characteristic clinical features of corneal opacity, proteinuria, and mild anemia. Renal biopsy revealed foam cells and an increased mesangial matrix in the glomeruli. Confirmation of the clinical diagnosis of LCAT deficiency was obtained by plasma enzyme and lipid analyses. Functional LCAT activity was not detected in incubated plasma by chemical or radiochemical methods, although rocket immunoelectrophoresis indicated that the patient had about one-third of normal LCAT mass. In keeping with other reports of LCAT deficiency, apoE-rich discoidal particles were seen in the patient's high-density lipoprotein fraction by electron microscopic examination.

Adult↗
PubMed1986

Platelet aggregation and plasma lipoproteins in alcoholics during alcohol withdrawal.

Platelet aggregation, platelet lipid composition and plasma lipoprotein concentrations were measured each week in a group of seventeen alcoholics, without overt liver disease, for one month, following acute, total alcohol withdrawal. The platelets were initially hypoaggregable but, within 1-2 weeks of cessation of drinking, they became hyperaggregable and then gradually returned towards normal values. Hyperaggregability could not be explained by increases in either the cholesterol or the arachidonic acid content of the platelets. Plasma very-low-density lipoprotein cholesterol levels remained high throughout the study, but the initially raised levels of high-density lipoprotein (HDL) cholesterol fell by 26%. Low-density lipoprotein (LDL) cholesterol concentration rose by 10% after two weeks of withdrawal but then returned to about the starting level. The resulting changes in the plasma LDL-cholesterol:HDL-cholesterol ratio, which had increased by more than 50% after two weeks of abstinence, essentially paralleled the time course of enhanced platelet reactivity in all but four of the alcoholics. These findings suggest that alterations in plasma lipoprotein concentrations during acute alcohol withdrawal may be a contributory factor to the haemostatic disorders present in such patients.

Adult↗
PubMed1984

Acute normal tissue tolerance to 7 day per week accelerated fractionation.

Fifty-six sites in 49 patients were irradiated by a 7 day/week accelerated fractionation schedule to conventional tumor doses. Daily doses were 180 to 200 rad in 85% of sites. Patients were analyzed for normal tissue tolerance. A 7 day/week accelerated fractionation appears clinically tolerable at 180 rad per fraction.

Digestive System↗
PubMed1983

Technique to maintain separation of mandibular loops in interstitial implantation of head and neck tumors.

Cancers of the floor of the mouth and lower gingiva are treated by an approach combining external radiation treatment and interstitial implant with Iridium-192 radioisotopes. One technique to administer the dose to these areas is a "loop" technique. A major problem in edentulous patients is that the plastic loops housing the Iridium-192 sources slide out of place along the gum, resulting in loss of ideal spacing. When this occurs, dosimetry for the implant generated from localization films prior to loading does not reflect the distribution of dose delivered. To overcome this problem, we have devised polytetrafluoroethylene (PTFE) spacers which, when used between the loops, maintains their correct spacing. An implant technique and the spacers will be described.

Brachytherapy↗
PubMed1983

The effect of low density lipoprotein on in vitro porcine endothelial cell reendothelialization.

We have studied the effect of low density lipoproteins (LDL) on the ability of porcine thoracic aortic endothelial cells (EC's) to reendothelialize an in vitro experimental wound made in a confluent monolayer culture. Our results show that normolipidemic LDL enhances EC regeneration primarily by acting as a mitogenic agent on the cells in the migrating sheet of cells covering the denuded wound area. There was no evidence of LDL induced cytotoxicity in our study.

Animals↗
PubMed1978

New ultraviolet (340 nm) method for assay of uric acid in serum or plasma.

We propose a novel enzymatic method for assay of uric acid at 340 nm, which eliminates several disadvantages of both the colorimetric and enzymatic methods now in common use. Here, uric acid is catalytically oxidized to allantoin and hydrogen peroxide. The peroxide is reacted with ethanol in the presence of catalase to form acetaldehyde and water, and the acetaldehyde is reduced by NADH in the presence of alcohol dehydrogenase to ethanol. The decrease in absorbance at 340 nm caused by oxidation of NADH is directly proportional to the concentration of uric acid in the sample. Measurement of the change in absorbance between 20 and 200 s eliminates the need for a serum blank measurement. Absorbance and concentration are linearly related to 120 mg of uric acid per liter. The new method was compared with the uricase method in which decomposition of uric acid at 293 nm is directly measured. The results for the 47 patients' sera so examined can be expressed by the linear equation y340 = 1.0078x293 + 0.122 (r = 0.9984).

Alcohol Oxidoreductases↗