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Biomedical subjects

H B Lee

Publications and source records attributed to H B Lee.

At least 163 records · Page 9Linked to original sources
PubMed1984

Cardiovascular consequences of primary antihypertensive therapy with prazosin hydrochloride.

Ten patients with essential hypertension who had no end-organ damage were treated with prazosin, starting with a dose of 1 mg/day. The dose was titrated to a maximal tolerated dose not exceeding 20 mg/day in divided doses or until diastolic blood pressure decreased to 90 mm Hg or lower. Among this study population a statistically significant decrease in blood pressures was achieved in the supine, sitting and standing positions. Baseline studies were repeated after 8 weeks of continuous therapy. There was no significant change in peripheral plasma renin activity, serum aldosterone or urinary sodium excretion. Plasma volume increased significantly and the patient weight increased proportionately. Cardiac ejection fraction at rest did not change significantly after prazosin therapy. Exercise ejection fraction also was not changed significantly from baseline during therapy, and the exercise-induced increase in blood pressure was significantly blunted. No adverse effects of prazosin on cardiac function were detected in this short-term study.

Adult↗
PubMed1983

Pharmacologic alterations in Tc-99m binding by red blood cells: concise communication.

The effect of two antihypertensive agents (captopril and prazosin) and of digoxin on the efficiency of Tc-99m binding to RBCs was evaluated in the rat. RBCs were labeled with Tc-99m in vivo in six groups of rats: I-normotensive controls Wistar rat (WR), II-prazosin treated WR, III-spontaneously hypertensive rat (SHR), IV-prazosin-treated SHR, V-digoxin-treated WR, and VI-captopril-treated WR. The percentage of intravascular Tc-99m bound to RBC (%T) and the percentage of injected dose remaining intravascular 5 min after injection (%i.v.) were determined. Mean %T was 94.2, 83.8, 94.9, 86.1, 79.7, and 93.3 for groups I-VI respectively. Mean %I.V. was 96.4, 74.6, 94.9, 79.0, 74.4, and 87.4 for groups I-VI respectively. The findings demonstrate a significant reduction of RBC tagging with Tc-99m in rats treated with prazosin and digoxin but not with captopril. The data suggest a potential interference by patient medication with the performance of blood-pool studies.

Animals↗
PubMed1981

Left ventricular ejection fraction and its response to therapy in essential hypertension.

Left ventricular ejection fraction at rest and during treadmill and isometric handgrip exercise were determined in 16 patients with essential hypertension (mean age 47.4 years) before and after therapy. The untreated hypertensive patient showed a linear correlation between mean blood pressure and LVEF (r = 0.62, p less than 0.01). The relation of sitting, resting LVEF with systolic blood pressure was highly significant (r = 0.88, p less than 0.001). Prior to therapy no significant change in LVEF in response to exercise was noted. After therapy with captopril, a normal isotonic exercise response occurred consisting of a highly significant increase in ejection fraction (p less than 0.0025). Subjects receiving propranolol had a fall in LVEF with isometric stress (p less than 0.0025). These data suggest an increased ejection fraction in patients with essential hypertension when all other parameters of the heart are normal and an abnormal response to isotonic exercise which may be reversed with therapy.

Adult↗
PubMed1981

Physiologic effects of prazosin HCl: consequences of diuretic combination therapy.

The physiologic action of prazosin in man was studied in 23 patients including 10 treated with prazosin plus polythiazide. Responders to prazosin alone (blood pressure fell greater than 10 mm Hg) had a decrease in peripheral resistance (p less than 0.02) and no significant change in plasma volume, while nonresponders' plasma volume rose significantly (p less than 0.02). 10 patients treated with prazosin and polythiazide (blood pressure not normalized on prazosin alone) were analyzed at baseline (Rx 0), after prazosin (Rx 1), and after prazosin plus polythiazide (Rx 2). Mean supine blood pressure fell from 184/118 +/- 8/5 (SE) mm Hg at Rx 0 to 161/106 +/- 7/4 mm Hg at Rx 1 (p less than 0.005) and 129/89 +/- 4/4 mm Hg at Rx 2 (p less than 0.001). Supine renin increased in each group, but the increase with prazosin alone was not significant. Stimulated renin activity increased significantly after Rx 2 (p less than 0.0025). Cardiac output fell, plasma volume returned to baseline values, and peripheral resistance fell by 467 dyn s/cm-5 during thiazide treatment (p less than 0.025).

Adult↗
PubMed1981

Tc-99m DMSA renal uptake: influence of biochemical and physiologic factors.

Thirty-eight female Sprague-Dawley rats were studied to determine the effects of (a) tubular blockade and (b) commonly encountered changes in hydration and acid-base balance, on the urinary excretion and renal localization of Tc-99m dimercaptosuccinic acid (DMSA). Ten additional rats were studied to quantitate the in vivo protein binding of Tc-99m DMSA, and a final group of 12 animals was used to quantitate DMSA distribution in animals with diminished functional renal mass. Both osmotic diuresis and dehydration by water deprivation for 24 hr resulted in a plasma clearance of DMSA slower than in control animals. Acid-base imbalances significantly affected the renal accumulation of DMSA, and acidosis was associated with markedly increased background due to increased liver accumulation. The protein-bound portion of Tc-99m DMSA in the plasma was high, reaching 89% within the first 5 min, and rising very slightly (n.s.) ith time. The unbound portion of DMSA had a plasma clearance slightly higher than the GFR. Ablation of large amounts of renal tissue, resulting in significant decreases in GFR. Ablation of large amounts of renal tissue, resulting in significant decreases in GFR, did not significantly affect the renal localization of DMSA in the intact portions of the kidneys. These data demonstrate that commonly encountered changes in acid-base balance and hydration will significantly alter the biologic distribution of Tc-99m DMSA. These factors should be controlled when carrying out clinical studies.

Acid-Base Imbalance↗
PubMed1977

Isolated thyrotropin deficiency due to a pituitary tumour.

Hypothyroidism due to isolated deficiency of thyrotropin (TSH) associated with an enlarged sella turcica, presumably the result of a nonfunctioning pituitary adenoma, occurred in a 58-year-old man. Low serum concentrations of TSH and thyroid hormones, together with the lack of TSH response to administration of thyroid releasing hormone, indicated a pituitary deficiency of TSH. Serum values of other pituitary hormones were normal.

Adenoma↗
PubMed1977

Temperature control of a bone cement by addition of a crystalline monomer.

The peak temperature reached during the polymerization of a bone cement was reduced by addition of solid N-vinylcarboazole to the powder component. It was also necessary to saturate the liquid component with N-vinylcarbazole to prevent dissolution from the modified powder component on mixing. It is believed that this technique is generally applicable and opens up the possibility of achieving temperature control of bone cements with choice from a range of crystalline monomers.

Bone Cements↗
PubMed1977

Use of 99mTc-Cu-DTPA complex as a renal function agent.

The use of cuprous ion as a reducing agent for pertechnetate is described for the first time. The potential usefulness of a 99mTc-Cu-DTPA complex as a renal function agent was evaluated by organ distribution studies in animals and by simultaneous continuous-infusion and single-injection clearance studies. Radioiodinated iothalamate was used as a standard for the measurement of GFR. The ratio for the clearance with the new copper complex to that with iothalamate is close to unity, both for continuous infusion (0.97 +/- 0.01 s.e) and for single injection (1.05 +/- 0.03). The coefficients of correlation are similarly close to unity: 0.96 and 0.99, respectively. Dialysis of plasma samples obtained after injection of 99mTc-Cu-DTPA into bilaterally nephrectomized rats indicates that only small amounts (less than 4%) of the complex are protein-bound. These data and the low toxicity of the copper preparation in animals appear to justify its investigation for kidney function measurement and imaging in man as well as its use as a GFR agent in animal studies.

Animals↗
PubMedDate not supplied

Gene polymorphisms of endothelial nitric oxide synthase and angiotensin-converting enzyme in patients with lung cancer.

The objectives of this study were to examine the possible involvement of endothelial nitric oxide synthase (ecNOS) and angiotensin-converting enzyme (ACE) genes in the genetic basis of lung cancer. Two hundred eighteen patients with lung cancer and 121 healthy subjects were included in this study. The ecNOS and ACE genotypes were determined in all subjects by polymerase chain reaction. The distribution of genotypes of ecNOS gene was significantly different in the lung cancer group than in the control population. ACE genotype distribution was not significantly different in the lung cancer group compared with the control group. These results suggest that polymorphisms of the ecNOS gene, but not the ACE gene, may be associated with the development of lung cancer.

Chi-Square Distribution↗
PubMedDate not supplied

Kinetic resolution of racemic alpha-methyl-beta-propiothiolactone by lipase-catalyzed hydrolysis.

Kinetic resolution of racemic alpha-methyl-beta-propiothiolactone (rac-MPTL) using lipases in organic solvent was studied. The lipase from Pseudomonas cepacia (PCL) showed the highest (S)-enantioselectivity (E > 100), and cyclohexane containing 1% (v/v) buffer was identified as the best reaction medium for maintaining high enantioselectivity as well as high reaction rate. While the substrate inhibition was not observed up to 300 mM rac-MPTL, severe product inhibition was observed even at 50 mM racemic 3-mercapto-alpha-methyl propionic acid (rac-MMPA), which made the use of high substrate concentration difficult. To overcome the product inhibition, the products, (R)-MMPA, were neutralized by addition of a dilute basic solution. Although the resolution reaction proceeded further by the base titration, the enantioselectivity of the reaction decreased as a result of nonenantioselective hydrolysis of rac-MPTL in the basic solution. Under these conditions, 200 mM rac-MPTL was successfully resolved to above 95% ee(S) with 53% conversion.

Burkholderia cepacia↗
PubMedDate not supplied

Microencapsulation of lipid nanoparticles containing lipophilic drug.

A polymeric emulsion bead, which consists of core and capsule, was prepared. The core is composed of lipid nanoparticles containing lipophilic drug and semi-interpenetrating networks (semi-IPNs) are prepared to provide the capsule composed of sodium alginate and hydroxypropylmethyl cellulose (HPMC). The lipid nanoparticles were encapsulated into the polymeric emulsion bead with high drug loading efficiency, and lovastatin was used as a model drug. For the application as an oral drug delivery system, the enteric coating was performed with polymeric emulsion bead. The drug release pattern was controlled by the composition of capsule materials and environmental pH.

Administration, Oral↗