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Biomedical subjects

B K Kim

Publications and source records attributed to B K Kim.

At least 181 records · Page 10Linked to original sources
PubMed1983

Separation of essential hypertensive patients based on blood pressure responses after the withdrawal of antihypertensive agents by step-wise discriminant analysis.

Thirty-five patients with uncomplicated hypertension were observed for blood pressure behaviour after prolonged antihypertensive medication withdrawal. Twenty-three patients (Group 1) remained normotensive (systolic less than 140 mmHg, diastolic less than 95 mmHg) for over 60 weeks compared to 12 patients (Group 2) who became hypertensive again during a 4-week placebo period. Discriminant analysis was performed on 31 clinical and laboratory variables measured before therapy to separate any discriminating factors for the two groups. Four variables maximized the separation of Group 1 from Group 2 patients. In descending order, these were serum sodium (p less than 0.001), mean corpuscular volume (p less than 0.01), serum albumin (p less than 0.01), and body weight (p less than 0.05). Using these four variables 73.9% of patients in Group 1 and 75% of patients in Group 2 were classified correctly into their respective groups. It is suggested that this observation may be useful in the development of new therapeutic regimens for patients with uncomplicated essential hypertension, for example by predicting those patients who may respond favourably to intermittent therapy or even to its withdrawal.

Adult↗
PubMed1983

Regression of left ventricular hypertrophy and control of hypertension in the spontaneously hypertensive rat (SHR): oxprenolol versus hydrochlorothiazide.

The control of hypertension with antihypertensive agents, in the spontaneously hypertensive rats (SHR) can result in regression of established cardiac hypertrophy. This study compared the effects of therapy with oxprenolol (Ox) and with hydrochlorothiazide (Htz) for (1) regression of established left ventricular hypertrophy (LVH) and (2) blood pressure control. Three groups of SHR and 3 comparable groups of Wistar-Kyoto (WKY) rats, matched for age, sex and body wt, were treated with tap water (Gp I), 60-200 mg hydrochlorothiazide kg-1 day-1 (Gp II) and 15-500 mg oxprenolol kg-1 day-1 (Gp III) for 13 weeks. Systolic and diastolic blood pressures (SBP, DBP mmHg), left ventricular wt/body wt ratio (LVwt/Bwt mg g-1) and left ventricular wall thickness (LVWT mm) were recorded. Oxprenolol lowered both systolic (mean +/- S.E. mmHg, 130 +/- 7 vs 189 +/- 8; P less than 0.01) and diastolic blood pressures (mean +/- S.E. mmHg, 104 +/- 6 vs 159 +/- 6; P less than 0.001) and caused regression of left ventricular hypertrophy (mean +/- S.E. mg g-1, 2.91 +/- 0.06 vs 3.10 +/- 0.09; P less than 0.05). In contrast, hydrochlorothiazide did not control blood pressure (mean +/- S.E. mmHg, 183 +/- 5 vs 189 +/- 6 and 152 +/- 5 vs 156 +/- 6), but it did cause regression of left ventricular hypertrophy (mean +/- S.E. mg g-1, 2.67 +/- 0.03 vs 3.10 +/- 0.09; P less than 0.01). Left ventricular wall thickness, measured in the mid-ventricular region, was significantly reduced only by hydrochlorothiazide (mean +/- S.E. mm, 2.76 +/- 0.06 vs 3.21 +/- 0.01; P less than 0.05). These results suggest that regression of left ventricular hypertrophy can occur with or without control of hypertension in the SHR.

Animals↗
PubMed1982

Inhibition of thrombin-neutralizing activity of antithrombin III by steroid hormones.

Estrogens in high doses have been shown to inhibit, in vitro, the thrombin-neutralizing action of antithrombin III (AT III). In this study we investigate the effect of estrogens on AT III in greater detail. To increase the sensitivity of measurement of AT III activity in the absence of heparin, we have developed an assay system utilizing human platelets, AT III and thrombin. The two proteins derived from human plasma were prepared in high purity. Platelet aggregation was induced by approximately 0.02 NIH U of thrombin. AT III was added in amounts that suppressed 95% of the aggregation-inducing effect of thrombin. Estrogens blocked the thrombin-neutralizing effect of AT III in dose-dependent manner. This effect was shown to be specific for AT III. Neither aggregability of platelets nor aggregating effect of thrombin were affected by the steroid hormone. Evidence for binding of estrogen to AT III was obtained from changes in intrinsic fluorescence of AT III. ACtivity of AT III was also reduced in increasing order of effectiveness by cholesterol, cortisone, testosterone and progesterone. Our studies suggest a direct effect of estrogens and other steroids on AT III, altering its specific neutralization of thrombin.

Antithrombin III↗
PubMed1982

Potassium conservation with amiloride/hydrochlorothiazide ("Moduret') in thiazide-induced hypokalaemia in hypertension.

A double-blind study was carried out in 24 hypertensive patients with thiazide-induced hypokalaemia (serum potassium less than 3.2 mmol/l) to compare the effects of treatment with an amiloride/hydrochlorothiazide combination or hydrochlorothiazide alone. The study was divided into three phases: (i) potassium repletion (Weeks 0 to 4) with oral potassium chloride (40 mmol/day), (ii) stabilization (Weeks 4 to 6) of normokalaemia, and (iii) active drug treatment (Weeks 6 to 14), patients being allocated at random to receive one or other of the two treatments. Dosage was 2 tablets per day of the 5 mg amiloride plus 50 mg hydrochlorothiazide combination or of 50 mg hydrochlorothiazide alone. The results showed that blood pressure control was comparable in both treatment groups but hydrochlorothiazide alone caused a statistically significant reduction in serum potassium levels compared to the drug combination. Apart from 1 patient who developed hypokalaemia on hydrochlorothiazide alone, no other side-effects of treatment were reported.

Amiloride↗
PubMed1982

Comparison of antihypertensive efficacy: propranolol versus oxprenolol in accelerated hypertension.

An open, randomized crossover study was carried out in 8 patients with accelerated hypertension to compare the antihypertensive efficacy of oxprenolol with that of propranolol. Dosage was titrated for each patient to achieve normotensive levels and was in the range of 40 to 320 mg twice daily. The same mg dosage was maintained for the alternative drug after crossover at 32 weeks for the second treatment period. The results showed that both drugs had equivalent antihypertensive effect on the erect systolic and diastolic and supine systolic blood pressures. Oxprenolol, however, produced a significantly greater reduction in supine diastolic blood pressure than did propranolol. There were no significant changes in heart rate or any of the other clinical or laboratory parameters monitored during either treatment, and side-effects were remarkably infrequent.

Clinical Trials as Topic↗
PubMed1982

Platelet-associated complement C3 in immune thrombocytopenic purpura.

Platelet-associated C3 (PA-C3) was measured with a quantitative immunofluorescence assay. With this assay, PA-C3 levels were determined for 78 normal volunteers, 30 patients with immune thrombocytopenic purpura (ITP), and 20 patients with nonimmune thrombocytopenias. Platelet-associated IgG (PA-IgG) levels were also measured with our standard quantitative immunofluorescence assay. All patients with nonimmune thrombocytopenias and ITP in remission had normal PA-C3 levels. Twenty-four patients with active ITP were classified into 3 groups: 9 (38%) with increased PA-IgG and normal PA-C3 levels, 10 (42%) with elevated PA-C3 and PA-IgG levels, and 5 (20%) with increased PA-C3 values only. A direct correlation was found between PA-C3 and PA-IgG levels. PA-IgG levels were higher in the group of patients with elevated PA-C3 levels than in those with normal values. Platelet survival studied showed reduced survival times of 1.5--2.5 days for the 5 patients with elevated PA-C3 levels only. Elevated PA-C3 levels returned to normal in 7 ITP patients whose platelet counts increased in response to corticosteroid therapy or to splenectomy. Therefore, PA-C3 and PA-IgG assays can be used to identify patients with ITP, to follow their response to therapy, and to classify them into immunologic subgroups similar to red cell classification by Coombs' testing in immune hemolytic anemia.

Adolescent↗
PubMed1982

Prolonged normotension following cessation of therapy in uncomplicated essential hypertension.

The blood pressure levels of 17 men and 7 women aged 27-65 years with uncomplicated essential hypertension were studied during and after withdrawal of antihypertensive therapy. Medication during the treatment phase included diuretics alone (13 patients), diuretic-nondiuretic combinations (5 patients), and nondiuretics alone (6 patients). Blood pressures were followed: greater than 48 weeks (with therapy) vs greater than 48 weeks (without therapy). SBP rose significantly (P less than 0.05) after therapy withdrawal but remained, for all but 6 of the 24, within the normotensive range (SBP mean +/- S.D. 125.2 +/- 11.1 mm Hg vs 134.9 +/- 13.3 mm Hg, and erect 87.4 +/- 9.3 mm Hg vs 131.2 +/- 12.0 mm Hg). DBP was unchanged (DBP mean +/- S.D., supine 83.8 +/- 8,0 mm Hg vs 85.2 +/- 6.2 mm Hg, and erect 87.4 +/- 9.3 mm Hg vs 86.7 +/- 6.6 mm Hg, P = 0.174). The blood pressures of 6 patients (25%) rose to levels requiring medication (SBP greater than 140 mm Hg. DBP greater than 95 mm Hg) between weeks 49 and 60. Salt intake was low (less than 100 mmol 24 h-1) and body weight remained stable (mean 75.4 +/- 12.4 kg vs 77.2 +/- 13.0 kg). These observations my indicate a role for intermittent antihypertensive therapy or quantitative reduction of medications, in the control of uncomplicated essential hypertension, provided that careful follow-up is available.

Adult↗
PubMed1981

Selection of donor platelets for alloimmunized patients using a platelet-associated IgG assay.

A quantitative immunofluorescence platelet-associated immunoglobulins (PA-IgG) assay was used to detect alloimmunity to platelets in 8/12 multitransfused patients and to perform platelet crossmatching in the 8 alloimmunized patients. The correct separation of multitransfused patients into alloimmune and nonalloimmune groups was substantiated with chromium-51-labeled platelet survival studies. For 5 alloimmunized patients, compatible and incompatible donor platelets were demonstrated by PA-IgG crossmatching and were confirmed by platelet survival studies. With the other 3 alloimmunized patients, only studies with 5 of these incompatible donor platelets showed markedly reduced survival times on 4 occasions. PA-Igg compatible donor platelets survived 3.5-8.7 days, while PA-IgG incompatible platelets showed survival times of 0.1-2.4 days. Overall, PA-IgG testing correctly indicated survival results on 15/17 occasions (88%), whereas platelet aggregation, serotonin release, and lymphocytotoxicity testing showed correct predictions for only 41%-59% of the survival studies. PA-IgG testing predicted which times, thus indication patients with platelet-specific alloantibodies. the PA-IgG assay provides a sensitive method to detect platelet alloantibodies and to perform platelet crossmatching, which can complement HLA typing in the selection of donor platelets for alloimmunized patients.

ABO Blood-Group System↗
PubMed1981

Detection of platelet alloimmunity with a platelet-associated IgG assay.

A quantitative immunofluorescence PA-IgG assay was used to detect alloimmunity to platelets. The assay identified serum alloantibodies in 10 out of 14 multitransfused patients and for two of three infants with neonatal thrombocytopenia. The correct separation of all multitransfused patients into alloimmune and nonalloimmune groups by the PA-IgG assay was substantiated with chromium-51--labeled platelet survival studies. The allogeneic nature of the serum antibodies was demonstrated by progressive absorption of the antibody with increasing numbers of allogeneic platelets but not with autologous platelets. The sensitivity of the PA-IgG assay for detection of serum alloantibodies was superior to that of platelet aggregation, platelet serotonin release, and lymphocytotoxicity testing. In dilution experiments with alloimmune serum, elevated levels of serum PA-IgG could still be detected on donor platelets when platelet aggregation and serotonin release tests became negative. Platelet survival studies with selected platelets performed in the 10 alloimmunized, multitransfused patients confirmed the results of the PA-IgG assays, predicting alloimmunity to the donor platelets. In contrast, platelet aggregation, platelet serotonin release, and lymphocytotoxicity testing indicated alloimmunity for 50% or less of the patients. Reduced platelet survival times were also seen with HLA A- and HLA B-matched donor platelets when donor-recipient incompatibility was demonstrated by the PA-IgG assay. Thus the PA-IgG assay provides a sensitive method to detect serum platelet alloantibodies and may offer a technique in platelet crossmatching.

Absorption↗
PubMed1977

Fluorometric determination of methyldopa in biological fluids.

A fluorometric method for the analysis of methyldopa, based on the formation of a fluorophore after oxidation and rearrangement, is described. The drug is isolated from biological fluids by adsorption on alumina and elution with an organic solvent. Fluoresence is linear from 0.1 to 1.5 microgram of methyldopa/ml. The assay has a lower limit of sensitivity of 100 ng/ml and is suitable for pharmacokinetic studies following therapeutic doses in animals and humans.

Adsorption↗
PubMed1976

Storage of human platelets by freezing.

Prolonged, probably indefinite storage of viable and functional human platelets is now possible by freezing with dimethylsulfoxide (DMSO). These platelets have a nearly normal survival upon reinfusion and are capable of sustained hemostatic effectiveness in thrombocytopenic patients. Adaptation of the freezing technique for large-scale usage has more recently been achieved. The method is mainly based on the following principles: (1) use of plasma for suspension of the platelet concentrate; (2) gradual addition (0.5% every 2 min) of DMSO to a final concentration of 5% and its gradual removal; (3) a slow cooling rate of about 1 degree C per min and rapid thawing (in 1 min); (4) use of a polyolefin plastic bag for freezing; (5) a washing medium of 20% plasma in Hanks' balanced salt solution; (6) final resuspension of the platelets in 50% plasma in Hanks' solution.

Alkenes↗