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Biomedical subjects

G Lee

Publications and source records attributed to G Lee.

At least 397 records · Page 22Linked to original sources
PubMed1984

Dissolution of pulmonary carcinoma via argon-laser bronchoscopy. First clinical use of fiberoptic metal cautery cap heated by laser radiation.

A 60-year-old man with nonresectable lung cancer underwent bronchoscopy which revealed a large squamous cell tumor mass narrowing the free airway to the left lung. A flexible quartz fiber connected to an argon ion laser was then inserted through a hollow channel of the fiberoptic bronchoscope. The laser was activated to heat the metal cap on the distal tip of the fiber to thermally dissolve the mass and relieve airway obstruction.

Argon↗
PubMed1984

Effects of laser radiation on the morphology of human coronary atherosclerotic disease.

Laser energy delivered through optical fibers can produce potent controlled thermal dissolution of human coronary obstructive disease, thus widening the stenotic vascular lumen. The ease of vaporization and penetration depends not only on the physical properties of the laser beam but also on the physical characteristics of the atherosclerotic plaque. Lipid-laden plaques are more easily vaporized compared with plaques that are heavily calcified. In atherosclerotic animal models studied in vivo, laser radiation produced a charred lining around the evacuated area and rapid regeneration of a new endothelial lining. After several weeks, the laser-induced crater was still evident, and thrombogenesis was not a significant complication. Focal aneurysmal dilatation may develop when there is thermal injury of the medial layer, and acute perforation can occur if severe laser burn is extended beyond the adventitial layer. Further technical advances and achievements are needed before laser recanalization becomes a clinical reality.

Animals↗
PubMed1984

B lymphocyte precursors in embryonic and adult W anemic mice.

Mice homozygous for mutations at the dominant spotting or W locus on chromosome 5 have been extensively used as models of severe macrocytic anemia caused by defective hemopoietic stem cells. We examined cells of the developing B lineage in adult and embryonic W anemic mice both by phenotypic analyses and by three distinctly different functional assays for B lymphocyte precursors. Adult W/Wv mice had normal numbers of B cells in the spleen and bone marrow, and normal numbers of pre-B cells and cells identified by a monoclonal antibody directed to a B lineage cell surface antigen (14.8) in the bone marrow. Embryonic W/Wv and Wx/Wx mice had hypoplastic liver development at 16 days gestation with a corresponding reduction in absolute numbers of pre-B cells, 14.8+ cells, and clonable granulocyte-macrophage progenitor cells, although their frequencies were normal. As expected, spleen colony-forming units were greatly reduced both in absolute number and frequency. Adult bone marrow cells and fetal liver cells from W anemic mutants generated B cells in vitro as well as did cells from normal littermates, but W anemic cells failed to generate B lymphocytes as well in vivo. These observations likely reflect differences in precursor cells that contribute to B cell formation in these assays, and suggest that early B lineage precursors are reduced or defective in W anemic mice.

Aging↗
PubMed1983

Steroidogenesis despite a variant metabolism in primary cultures of pig granulosa cells.

Enzymic changes in primary cultures of granulosa cells over 9 days were measured and compared with changes occurring during follicular development in vivo. Characteristic of in vivo development of granulosa cells was a large increase in activities of the NADP+-dependent isocitrate, glucose-6-phosphate dehydrogenases and malic enzyme, and smaller increases in the activities of the NAD+-dependent lactate and malate dehydrogenases. In vitro, the NAD+-dependent dehydrogenases increased in activity, while the NADP+-dependent enzymes showed transient or no changes. Despite the uncharacteristic metabolism, granulosa cells in culture could synthesize steroids. Our results suggest that the cells in vitro and in vivo use different metabolic pathways to support syntheses dependent on reducing equivalents.

Animals↗
PubMed1983

DMSO is a substrate for chloroperoxidase.

Dimethyl sulfoxide has been used as a nonaqueous organic solvent in haloperoxidase reactions. However, it has been found that this solvent is not inert under chloroperoxidase reaction conditions, forming the halosulfoxide, the sulfone, and the halosulfone. The biological significance of this finding is briefly discussed.

Chloride Peroxidase↗
PubMed1983

Effects of laser irradiation on human thrombus: demonstration of a linear dissolution-dose relation between clot length and energy density.

Because vascular thrombosis often accompanies arteriosclerotic disease in occluding blood vessels, the dissolution properties of laser irradiation were investigated and the energies needed to penetrate different lengths of thrombus were quantitated. Spectrophotometric studies show that the blood clot due to the presence of hemoglobin is well absorbed by argon laser energies, which emit blue-green wavelengths between 454 and 514 nm. Thus, laser energies transmitted directly from an argon-ion source produced vaporization and penetration of human thrombus in a linear dose-response fashion; the longer the thrombus, the greater the power intensity or time exposure necessary to penetrate the clot.

Dose-Response Relationship, Radiation↗
PubMed1983

Effects of laser irradiation on human erythrocytes: considerations concerning clinical laser angioplasty.

Recent studies demonstrate the potential use of laser to vaporize human coronary atherosclerotic plaques. The laser energy is transmitted through flexible quartz fiber and discharged intravascularly. Since red blood cells could be exposed to intense heat, we examined effects of laser irradiation on human erythrocytes. Blood was obtained and placed in 5 ethylene diaminetetracidic acid (EDTA) vials for each normal donor. A flexible 400 microns diameter core quartz fiber coupled to an argon-ion laser source was positioned 1 cm above the surface of 1.5 ml blood. Four vials were exposed to 5 W laser beam for 5, 10, 15, or 20 s; the remaining vial was left untreated. Packed cell volume fell primarily during the first 5 s of laser exposure (p less than 0.01) and plateaued beyond 5 s. Plasma hemoglobin (Hgb) rose progressively with each increased duration of exposure (p less than 0.01). This study indicates that lysis of erythrocytes occurs in cells exposed directly to the laser beam. However, beyond the direct beam, damage to red cell membrane took place as evident by progressive Hgb leakage into plasma despite no further cell lysis. These observations require consideration during clinical laser angioplasty.

Erythrocyte Indices↗
PubMed1983

Laser irradiation of congenital heart disease: potential for palliation and correction of intracardiac and intravascular defects.

We examined the potential for laser irradiation of congenital heart defects, with the use of postmortem hearts and an argon ion laser with a flexible quartz fiber. Atrial septectomy was performed in five newborn hearts. Obstructive lesions were relieved by laser irradiation in valvular pulmonic and aortic stenosis, dysplastic pulmonary valve, pulmonary atresia, and coarctation of the aorta. To demonstrate the efficacy of in vivo cardiac laser surgery, atrial septectomy was also performed in an anesthetized dog model, under echocardiographic visualization, without change in heart rate or blood pressure. Our results demonstrate the feasibility of intracardiac and intravascular laser irradiation for palliation and repair of selected congenital heart diseases.

Animals↗
PubMed1983

Reduction of ventricular ectopic beats with oral acebutolol: a double-blind, randomized crossover study.

The antiarrhythmic efficacy of oral acebutolol, a new cardioselective beta-blocking agent, was assessed in a randomized double-blind, placebo-controlled study. Twenty-five patients with greater than or equal to 30 ventricular ectopic beats (VEB) per hour on three control ambulatory monitorings were studied. Mean VEB reduction from the control period was 35% with placebo and 45% and 50% with the use of acebutolol 200 mg and 400 mg, respectively. Eleven patients had greater than or equal to 70% reduction in VEB with acebutolol and nine of them had greater than or equal to 90 VEB reduction. Among these 11 patients, the mean VEB suppression was 51% after placebo but significantly higher following the two doses of acebutolol at 71% (p less than 0.05) and 86% (p less than 0.01). The mean reduction of paired VEB compared to placebo was 71% (p less than 0.05) and 75% (p less than 0.01) following 200 mg and 400 mg of acebutolol and only 49% after placebo. Complete suppression of paroxysmal ventricular tachycardia was also noted in five patients. Mean PR interval only increased slightly when patients took 400 mg of acebutolol, but there was no significant change in either the QRS or QTc intervals. A significant decrease in heart rate from that during control periods was noted after acebutolol. No significant adverse reactions were noted during the study. Acebutolol appears to be an effective and well-tolerated antiarrhythmic agent in the treatment of VEB and higher grades of ventricular ectopy.

Acebutolol↗
PubMed1983

The qualitative effects of laser irradiation on human arteriosclerotic disease.

To determine the effects of laser irradiation upon human coronary atherosclerotic disease, coronary plaques were extracted from fresh human cadaver hearts. Seventy-four diseased artery samples were sectioned either transversely or longitudinally and subjected to laser treatment from argon-ion and carbon dioxide sources. The laser beam affected vaporization and patency in fibrous, lipoid, and calcified plaques as observed histologically. Calcified blockage showed greater extent of charred remnants following controlled thermal injury than did fibrous or lipoid obstructions. The area and depth of penetration varied directly with intensity and duration of photoirradiation and inversely with the density of the atherosclerotic tissue. This study supports further research work on the use of lasers to effect relief of atherosclerotic obstructions.

Coronary Disease↗
PubMed1983

Solitary necrotic nodules of the liver simulating hepatic metastases.

Four cases are described in which solitary nodules were identified on the anterior aspect of the liver. These had characteristic histological appearances. Each had a necrotic core surrounded by a dense collar of hyalinised collagen, incorporating elastic fibres. While three of our patients had carcinoma elsewhere none had evidence of tumour in the liver. We do not believe that these lesions represent hepatic metastases. We suggest that they may be of traumatic aetiology or a sequel of previous infection.

Aged↗
PubMed1983

Necrotising granulomata in prostatic resection specimens--a sequel to previous operation.

Six cases, in which necrotising granulomata were discovered in transurethral resection specimens of prostate gland, are described. In four of these cases, granulomata of foreign body type were also present. None of the patients had clinical, microbiological or histological evidence of tuberculosis, past or present. All had had at least one previous prostatectomy. The necrotising granulomata had characteristic microscopic appearances. They were almost certainly caused by operative trauma.

Aged↗
PubMed1983

Effects of the administration of anticoagulants on the activity of the enzyme-reduced NAD(P)H dehydrogenase in rat livers, hepatomas and precarcinomatous rat liver lesions.

The anticoagulants dicumarol, warfarin and diphenadione, are in vitro inhibitors of the enzyme reduced NAD(P)H dehydrogenase of rat liver. These chemicals were administered by intragastric gavage to determine whether the same inhibitory effects could be observed in Sprague-Dawley male rats. Doses of 2 and 10 mg/100 g body weight were used. Our results indicate that only dicumarol inhibited the enzyme, whereas warfarin did not produce a significant effect, and diphenadione at large doses produced an increase in the activity of the enzyme. Dicumarol was further tested to see if it would alter the activity of the enzyme in hyperplastic nodules and liver hepatomas. A similar inhibitory effect was found. The three strains of rats tested in this work have different levels of reduced NAD(P)H dehydrogenase activity. Thus, our results indicate that dicumarol is the only anticoagulant that inhibits in vivo the reduced NAD(P)H dehydrogenase of rat liver and liver neoplasms.

Animals↗
PubMed1983

Increased exercise tolerance after nitroglycerin oral spray: a new and effective therapeutic modality in angina pectoris.

The prophylactic antianginal efficacy of nitroglycerin (NTG) oral spray was assessed in 20 patients with angiographically documented coronary disease and stable angina pectoris. The evaluation was by a randomized crossover trial involving treadmill exercise testing. On study day 1, a control treadmill exercise test was performed, followed 30 minutes later by a second exercise test 2 minutes after administration of either placebo (group A, 10 patients) or NTG spray 0.8 mg (group B, 10 patients). One week later, on study day 2, the patients again underwent control treadmill exercise testing followed by a second exercise test after either NTG spray (group A) or placebo (group B). NTG spray delayed the onset of anginal pain during exercise by a mean of 100 +/- 64 seconds (p less than 0.001) in 13 patients and prevented pain entirely in seven. Placebo did not significantly delay the appearance of angina and prevented chest pain in only one patient. NTG spray increased treadmill exercise duration by 31% before the onset of angina (p less than 0.001); placebo did not significantly alter the duration of exercise. NTG spray abolished in six patients and delayed in 14 patients the onset of exercise-induced ST-segment depression of 1 mm (p less than 0.001). Patients achieved a higher heart rate at peak exercise with NTG spray, and yet the maximal exercise-induced ST-segment depression of 2.1 +/- 1.0 mm during the control study declined to 1.3 +/- 0.9 mm on NTG spray (p less than 0.001). Placebo had no effect on exercise ST-segment depression. These data indicate that the oral NTG spray is an effective prophylactic for exercise-induced angina.

Administration, Oral↗