Search PubMed⌕ Search

Biomedical subjects

H B Lee

Publications and source records attributed to H B Lee.

At least 127 records · Page 7Linked to original sources
PubMed1993

A wettability gradient as a tool to study protein adsorption and cell adhesion on polymer surfaces.

A new method for preparing a wettability gradient on polymer surfaces was developed. Low density polyethylene sheets were treated in air with corona from a knife-type electrode whose power gradually increases along the same length. The polymer surfaces oxidized gradually with the increasing power and the wettability gradient was created on the surfaces as evidenced by the measurement of water contact angles, Fourier-transform infrared spectroscopy in the attenuated total reflectance mode, and electron spectroscopy for chemical analysis. The wettability gradient surfaces prepared were used to investigate the interactions of model protein and cells in terms of the surface hydrophilicity/hydrophobicity of polymeric materials.

Adsorption↗
PubMed1993

Effects of delayed treatment with enalapril and/or lovastatin on the progression of glomerulosclerosis in 5/6 nephrectomized rats.

To evaluate the effect of delayed treatment with enalapril or lovastatin on the progression of glomerulosclerosis and to examine if the combined treatment with enalapril and lovastatin show synergistic effect, a total of 31 Sprague-Dawley rats were studied for 16 weeks following 5/6 nephrectomy (NPX). Treatment was delayed until 8 weeks after NPX. In untreated control rats (n = 8), sustained systemic hypertension with increasing proteinuria, serum cholesterol, triglyceride, BUN and widespread glomerulosclerosis and mesangial expansion were observed. Treatment with enalapril alone (R, n = 8) reversed systemic hypertension, prevented a further increase in proteinuria, and significantly reduced glomerulosclerosis relative to the control group. Treatment with lovastatin alone (L, n = 7) also reduced glomerulosclerosis and serum cholesterol compared to the controls. The drug also prevented a further increase in proteinuria and systemic blood pressure although the difference from the control rats did not reach statistical significance. Treatment with both enalapril and lovastatin (RL, n = 8) almost completely prevented glomerulosclerosis and significantly reduced mesangial expansion, systemic blood pressure, serum cholesterol, and proteinuria compared to controls. Only the combined treatment stabilized BUN and reduced mesangial expansion compared to control R, or L groups. Conclusion. Delayed treatment with enalapril or lovastatin is effective in preventing the progression of glomerulosclerosis, and combined treatment appears to show synergistic effect in 5/6 nephrectomized rat model.

Animals↗
PubMed1992

Expression of a cardiac Ca(2+)-release channel isoform in mammalian brain.

Mammalian brain possesses ryanodine-sensitive Ca2+ channels, which in muscle cells mediate rapid Ca2+ release from intracellular stores during excitation-contraction coupling. Analysis of bovine brain ryanodine receptor (RyR) channels suggests specific expression of the cardiac-muscle RyR isoform in mammalian brain. Localization using cardiac-muscle RyR-specific antibodies and antisense RNA revealed that brain RyRs were present in dendrites, cell bodies and terminals of rat forebrain, and highly enriched in the hippocampus. Activity of skeletal-muscle RyR channels is coupled to sarcolemmal voltage sensors, in contrast with cardiac-muscle RyR channels, which are known to be Ca(2+)-induced Ca(2+)-release channels. Thus Ca(2+)-induced Ca2+ release from intracellular stores mediated by brain RyR channels may be a major Ca(2+)-signalling pathway in specific regions of mammalian brain, and hence may play a fundamental role in neuronal Ca2+ homoeostasis.

Animals↗
PubMed1992

Serum alpha 1-antitrypsin in patients with hepatocellular carcinoma.

To evaluate the diagnostic value of alpha 1-antitrypsin (alpha-AT) as a tumor marker for hepatocellular carcinoma (HCC), we studied the serum levels of alpha-AT by rocket immunoelectrophoresis and alpha-fetoprotein (alpha-FP) by radioimmunoassay in 46 proven HCC patients, 43 cirrhosis patients and 200 healthy blood donors. The mean alpha-AT level of the 46 patients with HCC (4.8 +/- 2.7 mg/ml) was significantly higher than that of 200 healthy control subjects (1.7 +/- 0.7 mg/ml) (P less than 0.0001). The sensitivity of alpha-AT in 24 patients with high level of alpha-FP (greater than 400 ng/ml) and 22 patients with low level of alpha-FP (less than 400 ng/ml) were 96% and 64%, respectively. There was no substantial correlation between alpha-FP and alpha-AT in the two groups (alpha-FP greater than 400 ng/ml, alpha-FP less than 400 ng/ml) (r = 0.078, 0.064). The sensitivity for HCC using alpha-FP level alone (greater than 400 ng/ml) was only 52%, and the sensitivity using alpha-AT level alone (greater than 3.2 mg/ml) was 76% of the 46 patients. Combining both tests, sensitivity was improved only to 80%.

Adolescent↗
PubMed1992

Renin predicts diastolic blood pressure response to nonpharmacologic and pharmacologic therapy.

OBJECTIVE: Plasma renin activity was measured at baseline and 6 months in a trial of nonpharmacologic therapy of mild hypertension to determine whether plasma renin activity predicts the diastolic blood pressure (DBP) response to nonpharmacologic therapy. DESIGN, SETTING, AND PARTICIPANTS: Randomized controlled trial of volunteers from the general community with mild hypertension (DBP between 90 and 100 mm Hg), off all antihypertensive therapy at baseline, treated in special research clinics (n = 593). INTERVENTIONS: Subjects were randomly assigned to usual, weight loss, or low sodium/high potassium diet and then randomly assigned to receive placebo, chlorthalidone, or atenolol. MAIN OUTCOME MEASURES: Renin was analyzed as plasma renin activity and as a renin index (logarithm of 24-hour urinary sodium excretion times logarithm of plasma renin activity) (593 patients at baseline and 6 months) to correct for varied sodium intakes. The DBP was measured using the random zero device. RESULTS: Change in DBP at 6 months could be predicted from baseline plasma renin activity or renin index. The DBP was decreased after 6 months of therapy by 2 mm Hg for each unit increase in baseline plasma renin activity and by 0.16 mm Hg for each unit increase in baseline renin index. Patients in the highest renin index quartile had a greater DBP response to atenolol therapy, and patients in the lowest renin index quartile had a greater DBP response to chlorthalidone therapy. Weight loss diet achieved a greater reduction in DBP in patients with higher baseline renin index and had an additive effect on DBP response in both of the drug groups. Patients on a weight loss diet receiving placebo in the highest baseline renin index quartile had a reduction in DBP of 12.4 mm Hg, compared with 4.4 mm Hg in the lowest baseline renin index quartile (P = .009). A low sodium/high potassium diet had a lesser effect than a weight loss diet on pharmacologic therapy. As with the weight loss diet, patients on a low sodium/high potassium diet in the highest baseline renin index quartile had a greater reduction in DBP than patients in the lowest baseline renin index quartile. CONCLUSIONS: These data suggest a significant relationship between baseline levels of plasma renin index and the likelihood of success of nonpharmacologic treatment of hypertension.

Adult↗
PubMed1992

Subcutaneously implanted catheters reduce the incidence of peritonitis during CAPD by eliminating infection by periluminal route.

UNLABELLED: Recent experiences with Y-connectors suggest that the flush-before-fill effectively reduces intraluminal infection. Periluminal infection, however, remains an important route of peritonitis (P). We have recently reported reduced P incidence with the introduction of a new access technique as described by Moncrief in which the external segment of peritoneal catheter is left implanted subcutaneously for 6 weeks before exteriorization and bag exchanges. P developed once every 14.0 patient-mos with the new access while the incidence was one episode per 10.7 mos with conventional access. Significantly fewer patients with the new access compared to those with conventional access experienced P during the observation period (p < 0.01). Although the overall incidence of exit-site infection (ESI) was not different, there were significantly fewer episodes of simultaneous P and ESI with the new access (2P in 47 episodes of ESI) than with conventional access (36P in 126 ESI). While 10 of the 36 episodes of simultaneous infection in the conventional technique were caused by same organisms, none of the 2 episodes with the new access technique was caused by same organisms. CONCLUSION: The results of this study suggest that the new access technique reduces P incidence by virtually eliminating infection by the periluminal route.

Adolescent↗
PubMed1992

Effects of erythropoietin-induced hemopoiesis on peritoneal transport and on in vitro T cell response in CAPD.

UNLABELLED: In order to investigate the therapeutic efficacy of subcutaneously administered erythropoietin (rHuEPO) and the effects of rHuEPO-induced hemopoiesis on peritoneal transport and on cellular immune responses, we performed standardized peritoneal equilibration tests and measured T cell subsets and phytohemagglutinin (PHA)-induced interleukin-2 receptor (IL-2R) expression of PBMC by flow cytometry before and after subcutaneous rHuEPO (Eprex-, Cilag), 4000 U twice weekly, in 13 stable CAPD patients. Hct increased from 21.3 +/- 3.4% to 30.0 +/- 4.8% after 1 mo and to 32.7 +/- 4.9% after 2 mon of rHuEPO. Drained volume after 4 hrs of dwell with 4.25% dialysate increased from 2,675 +/- 204 ml to 2,807 +/- 174 ml (P < 0.05). D4/P4 creatinine increased from 0.68 +/- 0.07 to 0.71 +/- 0.06 (P < 0.05) and creatinine clearance from 7.57 +/- 0.71 to 8.03 +/- 0.63 ml/min (P < 0.05). The number of total circulating lymphocytes, T4,T8, T4/T8 with or without PHA did not change after rHuEPO. PHA-induced IL-2R expression by PBMC as expressed by mean channel of fluorescence intensity increased from 149.8 +/- 6.7 to 156.8 +/- 6.1 (P < 0.05). CONCLUSION: Subcutaneous rHuEPO is effective in correcting anemia in CAPD patients. rHuEPO-induced hemopoiesis is associated with increase in peritoneal creatinine and water transport and also with PHA-induced IL-2R expression.

Adult↗
PubMed1992

The effect of captopril on glucoheptonate uptake in experimental renal artery stenosis.

This study attempted to evaluate the role of glucoheptonate (GHA) in captopril renography in an in vivo laboratory investigation in which postcaptopril glucoheptonate uptake was analysed in awake 2KlC hypertensive rats. Clamped kidney uptake in a previous study was greater in the poststenotic kidney than in the normal kidney (P = 0.01) in rats with mild renal artery stenosis. A glucoheptonate renogram protocol was developed for use in rats anaesthetized with sodium pentobarbital. An 123I-hippuran scan was performed to determine the relative renal function, followed by a control 99Tcm-GHA scan. Five minutes after administering captopril, another 99Tcm-GHA scan was performed. Relative renal uptake was determined between 30 and 90 s postinjection. 99Tcm-GHA uptake in the clamped kidney was more than 50% of total uptake in 3/9 of the abnormal rats' control scans. No abnormal rats clamped kidney 99Tcm-GHA uptake was greater than 50% in the postcaptopril scans. Captopril reduced GHA uptake in all nine of the animals with baseline scans. These findings suggest that the laboratory observation of captopril induced paradoxically increased 99Tcm-GHA uptake in renal artery stenosis may not be observed scintirenographically. Moreover, the data support a potential value of glucoheptonate in captopril renography.

Animals↗
PubMed1992

Renal functional response to captopril during diuretic therapy.

Antihypertensive agents may modify the renal effects of angiotensin converting enzyme inhibition (ACEI). This potential interaction, which is important in the diagnosis of renovascular hypertension was studied in two rat models with and without diuretic treatment prior to ACEI. Acute intravenous administration of furosemide or hydrochlorothiazide in one-kidney, one-clamp animals (1K1C) did not change glomerular filtration rate (GFR) or effective renal plasma flow (ERPF). ACEI administration after furosemide and hydrochlorothiazide decreased GFR (p less than 0.001, p less than 0.01) but not ERPF. Chlorothiazide administered to 1K1C prior to ACEI, decreased GFR (p less than 0.02) but not ERPF captopril administration to 1K1C which received hydrochlorothiazide intraperitoneally for 7-10 days decreased GFR (p less than 0.007) and ERPF (p less than 0.02), while two-kidney, one-clamp animals (2K1C) decreased GFR only in the clamped kidney (p less than 0.005). ERPF in 2K1C increased only in the contralateral kidney (p less than 0.01). Without diuretic 1K1C animals decreased GFR and ERPF after ACEI (p less than 0.005, P less than 0.001). In the clamped kidney of 2K1C rats, GFR and ERPF decreased significantly (p less than 0.0005, p less than 0.004) and contralateral kidney ERPF increased (p less than 0.001), but GFR did not. The consequences of ACEI on GFR are similar with or without diuretic. These data suggest that diuretic therapy may not significantly interfere with ACEI evaluation of renovascular hypertension.

Animals↗
PubMed1991

Determination of resin and fatty acids in sediments near pulp mill locations.

A gas chromatographic method for the determination of resin and fatty acids in sediments is described. In this procedure, the sediment sample was air-dried and soxhlet-extracted with a mixture of acetone--methanol (88:12, v/v) in the presence of hydrochloric acid. The acids extracted were converted into their pentafluorobenzyl esters and were then cleaned up on a deactivated silica gel column. Final analysis was performed on either a DB-17 or a DB-5 capillary column with electron-capture detection. Quantitative recovery was obtained from fortified sediments for all acids except palustric, neoabietic and levopimaric acids. The detection limit of all acids in this method was 0.1 micrograms/g based on 1 g of sample. This procedure has been successfully applied to the monitoring of resin and fatty acids in sediment samples collected in the vicinity of several Canadian pulp mill locations.

Canada↗
PubMed1991

Cell adhesion and growth on polymer surfaces with hydroxyl groups prepared by water vapour plasma treatment.

Various polymer surfaces--polyethylene, polypropylene, polystyrene, polyethylene terephthalate and poly(methyl methacrylate)--were modified by water vapour plasma discharge treatment. The plasma-treated polymer surfaces were characterized by water contact angle measurement and electron spectroscopy for chemical analysis. It was observed that by the water vapour plasma treatment, the wettability of the polymer surfaces increases largely and almost all functional groups produced on the surfaces are hydroxyl groups. The interactions of Chinese hamster ovary cells with the polymer surfaces having hydroxyl groups by plasma treatment were investigated. The cells adhered and grown on the polymer surfaces were counted using a haemocytometer and photographed with an inverted microscope with a camera attached. The water vapour plasma-treated polymers showed good adhesion, spreading and growth properties on the surfaces with high hydroxyl group density. We confirmed that the water vapour plasma treatment is a simple and effective method to produce hydroxyl groups on the polymer surfaces, which probably have a positive effect on cell adherence.

Animals↗
PubMed1991

Behavioral teratogenicity of methamphetamine.

Pregnant Wistar rats were given daily subcutaneous administrations of methamphetamine (MAPT; varying doses ranging from 1.0 to 4.5 mg/kg) from days 7 to 20 of gestation and teratogenic effects have been determined. The teratogenic effects inducible with orally administered caffeine (90 mg/kg/day) for the same durations were used as the positive controls. MAPT doses greater than 2.0 mg/kg have suppressed the rate of maternal weight gain. Some of the offsprings (F1) of the prenatal MAPT treated groups had decreased growth rate and delayed development of physical characters and functional reflexes. The male offsprings of the MAPT treated groups had significant decreases in their spontaneous motor activity but had enhanced conditioned avoidance responses. However, the mating performances of these offsprings were not affected. These results indicated that prenatal exposure of MAPT may induce some behavioral teratogenicity in rats.

Animals↗
PubMed1990

Ragweed IgE and IgG4 antibody in nasal secretions during immunotherapy.

We have developed sensitive amplified immunoassays for measurement of IgE and IgG4 ragweed (RW) antibodies in unconcentrated nasal washes. IgE to Amb a I (formerly antigen E) can be assayed to less than 0.1 ng/ml using IgE capture by anti-IgE on microtitre plates and an alkaline phosphatase-conjugated Amb a I with an amplification substrate technique. IgG4 to whole RW extract was assayed to less than 0.01 ng/ml by amplification ELISA using monoclonal anti-IgG4. Nasal washes (NW) (10 ml) and serum were obtained in December from 22 RW-sensitive patients before and after 1 and 2 yr of RW immunotherapy (IT), and assayed for Amb a I IgE or RW IgE and RW IgG4 antibodies Amb a I IgE could be measured in the NW of 15/22 pre IT, 19/22 at 1 yr IT, but only 3/10 at 2 yr IT (compared with pre-IT, P less than 0.05). Mean Amb a I IgE in NW was 0.66, 0.36 and 0.21 ng/ml at pre, 1 yr and 2 yr IT (P-values greater than 0.05). Mean serum RW IgE, was 76, 55 and 27 ng/ml at pre, 1 yr and 2 yr IT (P-values greater than 0.05). Amb a I IgE in nasal washes was correlated with RW IgE in serum (r = 0.56, P less than 0.001, n = 44). RW IgG4 was detectable in NW of 15/22 pre-IT, 18/22 at 1 yr IT and 9/10 at 2 yr IT (P-values greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Effect of serum urokinase on urine fibrinolytic activity.

The purpose of this study was to see if the serum level of urokinase might influence the urine fibrinolytic activity. Serum fibrinolytic activity precipitated in dextran sulfate euglobulin fraction was measured on the plasminogen-rich plate before, during, and after the urokinase infusion. The fibrinolytic activity of euglobulin increased during urokinase infusion by dose-dependent pattern (n = 4, mean: 230%, range: 173-333% of basal level) and decreased below the basal level after cessation of urokinase (n = 4, mean: 18%, range: 0-27% of basal level). There was inverse correlation between the urine fibrinolytic activity and serum fibrinolytic activity in all cases (r = -0.75, 0.01 less than p less than 0.02 in case 2; r = -0.88, 0.0001 less than p less than 0.005 in case 3; r = -0.74, 0.05 less than p less than 0.10 in case 1a and r = 0.59, 0.05 less than p less than 0.10 in case 1b). This finding suggests that the urine fibrinolytic activity production was under control of the serum urokinase level with feedback mechanism.

Aged↗
PubMed1990

Peritoneal solute clearances in diabetics.

In order to examine solute transport across the peritoneal membrane and responsiveness of the peritoneal microcirculation to a vasodilator in diabetics on continuous ambulatory peritoneal dialysis (CAPD), we obtained peritoneal clearances of urea (Curea) and creatinine (Ccr), protein concentrations in the drained dialysate (DPC), and percentage of peritoneal glucose absorption (% PGA) before and after nitroprusside (NP) addition to the dialysate in 13 diabetics (DM) and 13 nondiabetics (non-DM) matched for age, sex, body weight, and duration of CAPD. Control (before NP) Curea, Ccr, DPC, and %PGA were not different between DM and non-DM. NP significantly enhanced Curea, Ccr, and DPC in both DM and non-DM. Curea, Ccr, DPC, and %PGA after NP were again not different between DM and non-DM. The findings suggest that peritoneal solute clearances and responsiveness of the peritoneal microcirculation to NP in diabetics are not different from nondiabetics at the beginning of CAPD despite evidence for widespread vascular diseases in diabetic ESRD patients.

Biological Transport, Active↗