Biomedical subjects
Publications and source records attributed to C Y Lin.
A myocardial rupture that occurred during anesthesia induction for infarctectomy was successfully repaired, and the patient is well and free of symptoms 10 1/2 months later.
By simulation of the FRC (functional residual capacity), washin of N2O was conceptually separated from uptake at the alveolar-capillary membrane. Data collected by mass spectrometry and pneumotachography during a period of 2 years showed a near-constant body uptake of N2O which makes clinical application of closed circuit N2O--O2 anesthesia simple and safe. The data failed to confirm accelerated washin by higher concentrations of N2O ("the concentration effect"), although there was a concentrating effect according to the law of mass action.
The aggregation of platelets induced by ADP, collagen, or epinephrine in human platelet-rich plasma is inhibited by long chain acyl-CoA thioesters. Palmityl-CoA exerts a concentration dependent inhibition of collagen-induced aggregation and of the primary and secondary waves of ADP-induced aggregation. Palmityl-CoA also inhibits the secondary wave of epinephrine-induced aggregation but has no effect on the primary wave. This inhibitory effect of palmityl-CoA can be reversed by addition of excess ADP and cannot be attributed to a detergent action.
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Chromatin isolated (pH 8.0) from soybean hypocotyl contains only RNA polymerase I activity as judged by its elution at low ionic strength (0.11 M ammonium sulfate) from DEAE-cellulose and DEAE-Sephadex, its total resistance to alpha-amanitin, and lack of preference for poly(dA-dT). The in vitro RNA product from this chromatin contains rRNA as a major component (36%) with little or no symmetry of transcription. The transcript from nuclei, where both RNA polymerases I and II are active, shows a dramatic increase in % rRNA (from 35 to 65%) when alpha-amanitin is present during synthesis. These observations suggest that plant RNA polymerase I is similar to animal RNA polymerase I in both its insensitivity to alpha-amanitin and preferential transcription of rRNA genes.
RNA polymerase I was purified from chromatin isolated from auxin-treated soybean hypocotyl. Purification was achieved by using Agarose A-1.5m gel filtration, DEAE-cellulose, CM-sephadex, and phosphocellulose chromatography, and sucrose density gradient centrifugation. With denatured calf thymus DNA as template, the enzyme has a high specific activity (200-300 nmol/mg/30 min at 28 degrees C) which is comparable to other RNA polymerase I enzymes purified from animals and yeast. While the gel profiles indicate that purification to homogeneity (greater than 90%) may not have been achieved, the enzyme appears to be composed of possibly 7 subunits, several of which are similar to the subunits of yeast RNA polymerase I. The putative subunits and molar ratios are 183 000 (1), 136 000 (1), 50 000 (0.5), 46 000 (0.5), 40 000 (0.5), 33 000 (0.2), and 28 000 (2). The purified enzyme strongly prefers a completely denatured template such as poly(dC).
Surgery has become an accepted method of treatment for coronary artery disease and its complications. Revascularization results in significant improvement in symptoms for patients with angina pectoris. Occasionally, patients requiring surgery for angina pectoris will sustain reversible ischemic damage during operation; such patients can be successfully weaned from cardiopulmonary bypass with full recovery when intra-aortic balloon counterpulsation is used. Arrhythmias associated with ischemic damage to the myocardium also can be controlled when IABCP is used for physiologic assistance. Patients in cardiogenicshock of pulmonary edema after acute myocardial infarction have an ominous prognosis. When decompensation occurs, IABCP may be used to stabilize the patient and to allow study and corrective surgery if possible. The prognosis is better for patients with ventricular septal defect, although selected patients without a mechanical defect of the myocardium can be salvaged if the response to IABCP is favorable. Counterpulsation has also been shown to be useful in achieving pulsatile cardiopulmonary bypass and in assisting high-risk patients through operation. External pressure circulatory assist (EPCA) is less effective than IABCP in assisting the failing myocardium; however, the external device is noninvasive and may be a useful adjunct in situations where IABCP is not feasible.
RNA polymerase I and II activities were measured in tissues of the soybean (Glycina max, var. Wayne) hypocotyl where dramatic changes in the relative level of RNA synthesis are associated with normal and auxin-induced growth transitions. When assayed in isolated nuclei, the activity of RNA polymerase I changed much more than the activity of RNA polymerase II during these growth transitions. The activity of RNA polymerase I expressed in the nuclei generally showed a positive correlation with the relative level of RNA synthesis (i.e. accumulation) of that tissue. Following solubilization of the RNA polymerases from these isolated nuclei and fractionation of them on DEAE-cellulose, the activity of RNA polymerase I relative to that of RNA polymerase II showed smaller changes during these growth transitions than when assayed in the nuclei. Thus, these data indicate that the activity of RNA polymerase I is significantly modulated in the nucleus, up or down depending upon the growth state, during growth transitions in the soybean in addition to lesser changes which occur in the apparent level of the enzyme.
We have studied the specificity of the acyl-CoA:diglyceride acyltransferase reaction in lactating rat mammary gland to provide a rational explanation at the enzyme level for the nonrandom distribution of fatty acids in milk fat triglycerides. Acyl-CoA:diglyceride acyltransferase activity was measured using various diglyceride and radioactive acyl-CoA substrates; products were identified as triglycerides by thin-layer and gas-liquid chromatography. Most of the enzymatic activity was located in the microsomal fraction and showed a broad specificity for the acyl donors tested C10, C12, C14, C16, C18, and C18:1 CoA esters). The acyltransferase activity was highly specific for sn-1,2-diglyceride enantiomers; rac-1,3- and sn-2,3-diglycerides were relatively inactive. The acyl-CoA specificity was not affected by the type of 1,2-diglyceride acceptor offered, although dilaurin was the best acceptor and sn-1,2-dilaurin greater than sn-1,2-dimyristin greater than sn-1,2-dipalmitin greater than sn-1,2-distearin. We have previously shown that in the microsomal fraction from lactating rat mammary gland, the acyltransferase activities concerned with the conversion of sn-glycero-3-phosphate to diacylglycerophosphate show a very marked specificity for long chain acyl-CoA's. Therefore, we conclude that the predominant localization of long chain fatty acids in the 1 and 2 positions, and of shorter chain fatty acids in the 3 position of the glycerol backbone, results at least in part from the specificities of the mammary gland acyltransferases.
A 5-year-old child with asplenia, situs inversus, single ventricle, common atrium, severe subvalvular pulmonary stenosis, 1-transposition of the great arteries, and absent inferior vena cava presented with severe limitation (resting arterial saturation 74 per cent). At operation, the systemic venous atrium was partitioned with a Dacron baffle, so that hepatic venous and coronary sinus blood was enabled to drain with the pulmonary venous blood into the single ventricle and aorta. The superior portion of this atrium was anastomosed to the divided main pulmonary artery, so that most of the systemic venous blood was allowed to flow directly to the lungs. Intraoperative hemodynamic studies revealed a pulmonary artery pressure of 12/9 mm. Hg and a superior vena caval flow that was 88 per cent of the ascending aortic blood flow. Follow-up catheterization studies revealed an intact partition, no anastomotic gradient, superior vena cava pressure of 20 mm. Hg, arterial saturation of 84 per cent, and excellent flow of contrast from superior vena cava to atrium to pulmonary artery. Exercise tolerance was markedly improved, and chronic fluid retention was not observed. This operation offers a new alternative for long-term palliation of complex lesions amenable to exclusion of the right ventricle, such as single or common ventricle with unreconstructable anomalies of the atrioventricular valves.
When etiolated soybean seedlings are treated with the synthetic auxin, 2,4-dichlorophenoxy-acetic acid, cells of the mature hypocotyl become swollen and proliferate abnormally. This abnormal growth induced by auxin coincides with a 5- to 8-fold increase in the alpha-amanitin-insensitive RNA polymerase associated with isolated chromatin or nuclei. The alpha-amanitin-sensitive RNA polymerase activity of the auxin-treated hypocotyl was similar to that of control tissue. The increase in RNA polymerase I activity of chromatin and nuclei was maintained after solubilization and fractionation on DEAE-cellulose. Auxin thus appears to enhance RNA synthetic activity (i.e., ribosomal RNA) in mature soybean tissue by altering RNA polymerase I directly rather than by altering RNA polymerase I directly rather than by altering the chromatin template.
Ribosomal subunits prepared by NH(4)Cl dissociation (0.5 m) of the monomeric ribosomes were much less active in in vitro protein synthesis than those prepared by KCl dissociation. The decrease in activity correlated with a detachment of some proteins (L(2) and L(9) as shown by gel electrophoresis) within the 60S ribosomal subunits. Subunits prepared with 0.3 m NH(4)Cl retained L(2) and L(9), but the activity remained low. Incubation of these 60S subunits in TKM buffer (50 mm tris [pH 7.5], 20 mm KCl, and 5 mm MgCl(2)) for 20 min at 37 C restored the activity almost to the level of those obtained by KCl dissociation. Treatment of the 0.3 m NH(4)Cl-derived 60S subunits with a protein reagent, Procion brilliant blue, prior to extraction of the ribosomal proteins resulted in the loss of L(2) and L(9), showing that these proteins were made accessible for dye binding. These observations suggest that a considerable degree of unfolding of the 60S subunit occurs at 0.3 m NH(4)Cl (this apparently leads to a preferential detachment of L(2) and L(9) at 0.5 m NH(4)Cl) and that the activity of the purified subunits depends not only on the presence of L(2) and L(9) but also on the organization of these proteins within the 60S subunits.
A quick procedure for the isolation of nuclei with good yield from soybean hypocotyl (Glycine max var. Wayne) was developed. The isolated nuclei appeared to retain their structural integrity. They were typically ellipsoidal with minima and maxima diameter of about 6 and 8 to 10 micrometers. While the nuclei were similar in size, the nucleoli were significantly larger in nuclei from auxin-treated tissue. The DNA content per nucleus was 4 +/- 1 picograms for both untreated and auxin-treated tissues. The DNA: RNA: protein ratio of isolated nuclei in untreated and auxin-treated tissues was 1: 3.1: 11 and 1: 5.4: 21.7, respectively. The purified nuclei were active in RNA synthesis; the level of RNA polymerase II activity expressed in the nuclei from untreated tissue was 50 to 60% higher than RNA polymerase. I. The nuclei from auxin-treated tissues contained about 2.5 times as much RNA polymerase I activity as nuclei from untreated tissue. The purified nuclei from both untreated and auxin-treated tissues were also active in the incorporation of (3)H-TTP into DNA.
An effective method for the isolation of nucleoli from auxin-treated soybean (Glycine max, var. Wayne) hypocotyl was developed by polytron homogenization and sucrose gradient centrifugation. The nucleoli expressed only the alpha-amanitin-insensitive RNA synthetic activity. This activity chromatographed as RNA polymerase I on DEAE-cellulose. It appears that the plant nucleolus, like the animal nucleolus, is the site of localization for RNA polymerase I.
Fatty acid synthetase was isolated from transplantable mammary adenocarcinomas carried by C3H mice. Comparison of physicochemical and immunological properties of this enzyme with those of the fatty acid synthetase isolated from normal glands of lactating C3H mice indicates that the enzymes are similar in all respects. The products of the purified fatty acid synthetase from normal and neoplastic tissues were the same, mainly long-chain fatty acids. The normal gland was found to contain 30 times more enzymes per g tissue than did the neoplasm; this may account in part for the relatively low rat of fatty acid synthetase found previously in this neoplasm.
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