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Biomedical subjects

C Y Lin

Publications and source records attributed to C Y Lin.

At least 451 records · Page 25Linked to original sources
PubMed1980

Tissue specificity for the effect of estrogen on lipogenic activity in male and female rats.

Estrogen treatment decreased fatty acid synthetase and acetyl-CoA carboxylase (EC 6.4.1.2) activities and lowered the lipogenic capacity of mammary gland and the hormone-responsive, transplantable mammary adenocarcinoma R3230AC in male and female Fischer rats whereas the activity of these enzymes and the lipogenic capacity were increased in liver. Estrogen increased the activity of thioesterase II, an enzyme which terminates fatty acid synthesis at medium chain lengths, in both normal and neoplastic mammary tissue.

Acetyl-CoA Carboxylase↗
PubMed1980

Coronary vasoconstrictor extracted from blood plasma stimulates platelet lipoxidase activity.

The effects of a coronary vasoconstrictor, obtained from human blood plasma, on aggregation and arachidonate metabolism by human platelets was determined. At low concentrations, the vasoactive factor stimulated formation of prostaglandins, thromboxane B2, and 12-L-hydroxyeicosatetraenoic acid in both intact platelets and in platelet microsomal enzyme preparations. As factor concentration was increased, thromboxane B2 formation decreased, but production of the other products continued to rise. Low concentrations of factor initiated platelet aggregation, whereas high concentrations prevented arachidonate-induced aggregation. Low levels of factor could induce aggregation via stimulation of thromboxane A2 production. Increases in formation of 12-L-hydroperoxyeicosatetraenoic acid at high factor concentrations could inhibit formation of thromboxane A2 and thus prevent aggregation.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1980

Closed circle systems. A new direction in the practice of anesthesia.

On the basis of the near-constant uptake of inhalation anesthetics at the alveolar membrane, the large closed-circuit volume which acts as a buffer, and the effect of concentration on uptake, we have evolved a simple and practical technique of closed-circuit anesthesia. After initial high flow wash-in of anesthetic gases into the FRC, a nearly constant slow fresh-gas flow can be maintained.

Anesthesia, Inhalation↗
PubMed1980

Assessment of vaporizer performance in low-flow and closed-circuit anesthesia.

The performance of five of the most commonly used halothane vaporizers and three enflurane vaporizers was tested under conditions encountered in low-flow and closed-circuit anesthesia. Anesthetic gas concentrations were measured continuously with a mass spectrometer connected to a circle system. The results indicated that all of the units tested, except the Fluotec Mark II, may be adapted for use in low-flow or closed-circuit anesthesia to provide accurate amounts of potent inhalation anesthetics. One should be aware, however, that the concentration of nitrous oxide affects vaporizer output, that changes in output occur during positive-pressure ventilation, and that the output of some of the vaporizers may increase when a change from high flow to low flow is made. It is also strongly recommended that upstream oxygen flushing be abandoned in the practice of low-flow or closed-circuit anesthesia.

Anesthesia, Inhalation↗
PubMed1980

Steroids in heart surgery: a clinical double-blind and randomized study.

The role of steroids in heart surgery was assessed in a group of 95 patients undergoing cardiopulmonary bypass. The treated group (47 patients) received repeated doses (every six hours) of methylprednisolone (30 mg/kg IV) in a double-blind, randomized fashion. The control group (48 patients) received a placebo in a fashion identical to the treated group. There were no significant (P less than 0.1) hemodynamic or biochemical differences between the control group and the patients receiving methylprednisolone. An improvement in survival was observed in the group receiving methylprednisolone. This finding cannot be explained with the data obtained from this study, in particular, when no other biochemical findings were improved. A more exhaustive hemodynamic and biochemical analysis is necessary to understand the subtle changes that are incurred with the use of steroids for heart surgery.

Adolescent↗
PubMed1980

Report of a case of Nezelof syndrome.

In this report, we present a 5 months old male baby, who suffered from watery diarrhea since 4 days old. From then on, he had been admitted 3 times in 3 different hospitals but the symptoms still bothered him off and on. During the days of hospitalization, sepsis with positive blood culture of Klebsiella was noted. The patient expired at 5 months of age. The T cell count was 20% active T was 0. Delayed hypersensitivity skin tests including Candida (10 X), PHA (10 micrograms), PHA (1 microgram), SK/SD (50 units) were negative. The granulocyte function study showed normal. Immunoglobulin analysis revealed IgG: 1320 mg%, IgA: 120 mg%, IgM: 100 mg%. Agenesis of thymus, failure of lymphoid differentiation and abnormal lymphoid architecture with absence of germinal centers were noted at autopsy. Combined immunodeficiency with normal immunoglobulins (Nezelof syndrome) is a disease of primary immunodeficiency characterized by recurrent infections, failure to thrive, lymphopenia, diminished lymphoid tissue, abnormal structure or agenesis of the thymus, and presence of normal or increased levels of one or more of the major immunoglobulin classes, but with impaired antibody synthesis. Since its original description by Nezelof and associates in 1964, it has been reported on the subsequent occasion. In this report, we present our one experience and review the clinical and laboratory data in 33 reported cases.

Humans↗
PubMed1979

The prosthetic (Teflon) central aortopulmonary shunt for cyanotic infants less than three weeks old: results and long-term follow-up.

The expanded microporous polytetrafluoroethylene (PTFE) 4 mm vascular prosthesis has been used to create a central aortopulmonary shunt in 20 critically ill infants less than 3 weeks old. The infants ranged from 1 to 18 days old (5.25 days), and from 1.5 to 4.0 kg (2.9 kg). Conduit length ranged from 2 to 6 cm (4 cm). Sixteen patients had atresia of the tricuspid or pulmonary valve. There were 6 early deaths (30%), only 1 of which was shunt related. The mean preoperative arterial oxygen saturation was 62% (range, 33 to 80%), and mean postoperative saturation was 87% (range, 78 to 90%). There were 5 late deaths, 1 probably caused by shunt failure. Nine long-term survivors have done well. Follow-up ranges from 1 to 36 months (18 months). Factors influencing conduit function are length, technical considerations, and pulmonary vascular resistance. Late restudy in 5 of 9 survivors confirms patency and demonstrates bidirectional pulmonary blood flow. Since PTFE shunt flow capability is fixed, the infant may require repair or a second shunt within 24 months of the initial procedure.

Aorta↗
PubMed1979

Detection, prediction, and significance of perioperative myocardial infarction following aorta-coronary bypass.

One hundred consecutive patients undergoing aorta-coronary bypass grafting (ACBG) alone, without ventricular venting, were prospectively studied to determine the incidence and consequence of perioperative myocardial infarction (PMI) and the clinical variables that were predictive of PMI. Incidence was determined by serial electrocardiography (ECG) 100 patients; serum CK, GOT, and LDH (100 patients). CK isoenzymes (qualitative 100 patients, quantitated 50 patients); vectorcardiography (VCG) (78 patients); and 99mtechnetium pyrophosphate scintigraphy (TcPyp) (52 patients). The incidence of PMI by ECG was 9%; an additional 8% of cases was diagnosed by enzymes alone. The incidence of diagnostic change by VCG was 19% and by scintigraphy, 25%. Using at least one changed variable of the remaining three as the reference standard, the relative sensitivity and relative specificity of given variables in the diagnosis of PMI were as follows: ECG 67% and 100%, respectively; VCG 85% and 94%; scintigraphy 92% and 97%; and serum enzymes 86% and 96%. By univariate analysis, unstable angina was the only significant predictor of PMI. The operative mortality rate was 2% and the mortality rate at 12 months was 5%. There was a significantly greater mortality rate in patients with PMI diagnosed by ECG (p less than 0.01), in patients with unstable angina pectoris before operation (p less than 0.05), and in women (p less than 0.05).

Analysis of Variance↗
PubMed1978

Release of two thioesterase domains from fatty acid synthetase by limited digestion with trypsin.

Limited digestion, with trypsin, of the fatty acid synthetase from rat mammary gland releases an enzymically active thioesterase component that, under denaturing conditions, consists of two major species of mol.wts. 35000 and 17500 and a minor species, mol.wt. 15,000. The 17500- and 150000-mol.wt. species are shown to originate from the 35000-mol.wt. species as a result of nicking by trypsin. The nicked polypeptides are enzymically active. The fatty acid synthetase is inhibited by [1,3-14C]di-isopropyl phosphorofluoridate, which is shown to bind to, and inactivate, two thioesterase active sites. When the [1,3-14C]di-isopropyl phosphate-labelled fatty acid synthetase is subjected to limited digestion with trypsin, all of the radioactivity is recovered in the isolated thioesterase component, i.e. in the 35000-mol.wt. polypeptide and its nicked products. Since the isolated thioesterase is shown to bind only one di-isopropyl phosphate residue per 35000-mol.wt. polypeptide, we conclude that the fatty acid synthetase has two thioesterase domains, both of which are removed by limited trypsin treatment.

Chromatography, Gel↗
PubMed1978

Properties of the thioesterase component obtained by limited trypsinization of the fatty acid synthetase multienzyme complex.

The fatty acid synthetase from lactating rat mammary gland is shown to consist of two polyfunctional polypeptides of similar molecular weight (about 220,000); a 4'-phosphopantetheine residue is covalently bound to one, or both subunits. Limited trypsinization of the fatty acid synthetase releases on enzymatically active thioesterase component which has been purified and its properties studied. The thioesterase sediments in the ultracentrifuge as a single component of molecular weight 32,000; its sedimentation coefficient is 2.9 x 10-(13) s its diffusion coefficient 5.0 x 10-(7) cm2 s-(1). The thioesterase also elutes from a column of Sephadex G-75 as a single, symmetrical peak of constant specific activity. However, electrophoresis of the denatured thioesterase in the presence of sodium dodecyl sulfate reveals that the enzyme has been partially nicked during isolation. The kinetic data of the enzyme reaction were studied using palmityl-CoA as a model substrate. Solvent pH was found to affect both Vmax and Km (Km = 0.5 micron at pH 6.6, 2.5 micron at pH 8.0) wereas solvent ionic strength affected Vmax but no Km. The thioesterases from the fatty acid synthetases of rat liver and lactating mammary gland have identical physical properties, identical amino acid compositions, and are immunologically indistinguishable. Both thioesterases hydrolyze long chain, in preference to short chain, thioesters of CoA, an observation consistent with their role in regulation of the chain-terminating step in fatty acid synthesis by the parent multienzyme complexes.

Amino Acids↗
PubMed1978

Surface cooling (20 degrees C) and circulatory arrest in infants undergoing cardiac surgery. Results in ventricular septal defect, complete atrioventricular canal, and total anomalous pulmonary venous connection.

During a six-year period, 46 severely symptomatic infants (average age, 5.1 months) underwent correction of ventricular septal defect (22 patients), total anomalous pulmonary venous connection (13 patients), and complete atrioventricular canal (11 patients), with the use of surface cooling to 20 degrees C. Cardiac repair was performed during circulatory arrest, and rewarming was performed with a pump oxygenator. Ten patients undergoing repair of ventricular septal defects were studied hemodynamically at 21 degrees C, before repair and at 37 degrees C after rewarming. Heart rate, left ventricular systolic pressure, maximum dp/dt, cardiac index, stroke work, and oxygen consumption were reduced substantially at 21 degrees C. Systemic vascualr resistance was increased at 21 degrees C. All changes were reversible with repair and rewarming. A protocol for hemodilution and crystalloid volume loading was devised to maintain urine output after early patients were noted to demonstrate renal dysfunction. With this protocol, survival rates were 89% for patients with ventricular septal defects, 67% for those with atrioventricular canal defects, and 85% for those with total anomalous pulmonary-venous connection.

Blood Pressure↗
PubMed1978

Complete common atrioventricular canal in infancy--surgical repair and postoperative hemodynamics.

Fourteen infants with complete common atrioventricular canal (CCAVC) underwent open heart surgery under deep hypothermia and circulatory arrest. There were three operative deaths and two late deaths. Postoperative studies performed in seven of the nine survivors revealed nearly normal hemodynamics. There were no residual shunts, and excellent mitral valve function was observed in six patients. In one patient, residual mitral regurgitation was noted. The pulmonary artery pressures and pulmonary vascular resistances were normal except in one who had severe pulmonary vascular obstructive disease before surgery. The mean left ventricular end-diastolic volume changed from 175 +/- 24% (SEM) before surgery to 106 +/- 7% after surgery (P less than 0.01). The corresponding right ventricular end-diastolic volume changed from 166 +/- 16% to 102 +/- 19% (P less than 0.025). Left ventricular ejection fraction was mildly decreased before and after surgery (0.63 +/- 0.02). Surgical repair of CCAVC is possible during the first year of life, with likely normalization of cardiac size and function. Unsatisfactory results related to pulmonary vascular obstruction may be anticipated if repair is delayed much beyond the first year.

Atrioventricular Node↗