Campylobacter pyloridis in patients with gastric carcinoma.
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Adenocarcinoma↗
Biomedical subjects
S C Cheng
Publications and source records attributed to S C Cheng.
Chiral discrimination in the exchange of alpha-tocopherol stereoisomers between plasma and red blood cells.
The transport of 2R,4'R,8'-alpha-tocopherol and 2S,4'R,8'R-alpha-tocopherol from plasma into rat red blood cell membranes occurs with essentially no chiral discrimination. The previously demonstrated (10) preference of red blood cell membranes favoring 2R,4'R,8'R-alpha-tocopherol over the 2S,4'R,8'R stereoisomer is shown to be due to better retention of the former compound, i.e., to preferential retention of natural vitamin E.
Animals↗
A hypothetical model on the mechanism of anesthesia.
An hypothesis on the mechanism of action of general anesthetic agents is proposed. It is based on a potentiation of chloride influx due to the action of anesthetic agents on the GABA-receptor complex at the lipid-protein interface. This hypothesis accommodates various observations such as lipid solubility of anesthetic molecules, their lack of stringent structural requirement, pressure reversal of anesthetic action, and other neurochemical and neuropharmacological data.
Anesthesia, General↗
Spliceosome assembly in yeast.
Precursors to mRNA become substrates for splicing by being assembled into a complex multisubunit structure, the spliceosome. To study the assembly of the yeast spliceosome, intermediate complexes were separated by electrophoresis on nondenaturing polyacrylamide gels. Four splicing-dependent complexes, A1, A2-1, A2-2, and B, were observed. The order of assembly of these complexes was determined to be B----A2-1----A1----A2-2. The assembly process can be blocked at complex A1 by addition of 5 mM EDTA or by carrying out the assembly process in heat-inactivated rna2 extracts. The snRNA composition of the complexes was determined by hybridization with probes for five yeast snRNAs. snR14 (U4) was only found in complex A2-1, snR6 (U6) and snR7 (U5) were in complexes A1, A2-1, and A2-2, whereas snR20 (U2) was in all four of the complexes. snR19 (U1) was not present in any of the complexes. Hybridization with these probes was also employed to detect snRNPs present in yeast splicing extracts. We found that snR6, snR7, and snR14 were present together in a large complex. This complex underwent an ATP-dependent dissociation to give snR7 and snR6-snR14 complexes. snR19 and snR20 are present in distinct RNPs but the mobility of these is not affected by ATP. A mechanism for spliceosome assembly is proposed.
Animals↗
Familial idiopathic megaduodenum.
Familial idiopathic megaduodenum is an uncommon condition which may be associated with other visceral abnormalities. Antineuronal antibody directed against guinea-pig skeletal muscle was found in one member of the family suffering from megaduodenum, in whom degeneration of the Auerbach's and Meissner's plexuses was documented. The significance of this finding is unclear. Management of the complaint is problematic. Despite shortcomings of surgical treatment, surgery nevertheless has an important role to play when medical treatments fail.
Abdomen↗
Massive hollow fiber clotting: a distinct problem in treatment of cryoglobulinemia by membrane plasmapheresis.
Two patients with cryoglobulinemia were treated with plasmapheresis in combination with immunosuppressive therapy. One had Waldenstrom's macroglobulinemia, and the other suffered from systemic lupus erythematosus. Membrane plasmapheresis, using membrane plasma separators, was performed, and the initial plasmapheresis treatments were unsatisfactory because of clotting of hollow fibers by cryoglobulin. The plasma filtration rate and the clearance of immunoglobulins fell rapidly with the clotting of the hollow fibers. This technical difficulty was overcome by prediluting the blood with normal saline before passing it through the membrane plasma separator. The mechanism of preventing clotting of hollow fiber by saline predilution is likely to be the reduction of serum viscosity and the lowering of cryoglobulin concentration. This modification is simple and efficient and enables membrane plasmapheresis to be performed effectively in patients with cryoglobulinemia without complicated and expensive machines.
Blood Coagulation↗
Seasons of birth and subtypes of schizophrenia.
Many studies show a higher rate of birth of schizophrenic patients during the winter and early spring months. This is particularly prominent in studies involving northern European countries and the northern part of the United States. The interpretations for this apparent seasonality remain highly speculative. We examined the seasons of birth of 472 patients carrying the diagnosis of schizophrenia. We also studied the gender and paranoid vs nonparanoid subtypes of this subject group. The total group does not show an excess of winter births. The same is true for total male (n = 193) and total female (n = 279) schizophrenic patients. The different subtypes of female patients show a homogenous distribution by seasons of birth; but the male paranoid schizophrenia group (n = 102) shows a significant increase of births during the first quarter of the year. The findings are interpreted according to the prevailing hypotheses of schizophrenia. The implications of these findings are discussed.
Female↗
Processing and secretion of the Yarrowia lipolytica RNase.
Secretion of the extracellular RNase from the yeast Yarrowia lipolytica was studied in pulse-chase and immunoprecipitation experiments. A polypeptide of 45,000 daltons was immunoprecipitated from [35S]methionine-labeled cell extracts and supernatant medium by rabbit anti-RNase antiserum. The RNase was secreted rapidly; the time between synthesis and appearance in the extracellular medium was about 5 min. In pulse-chase experiments, about 50% of the RNase was still cell associated 30 min after labeling. A polypeptide of 73,000 daltons whose immunoprecipitation was blocked by an excess of purified RNase was also detected. It broke down to a polypeptide with the same mobility and same peptide map as the mature RNase. Peptide maps of the undegraded 73-kilodalton polypeptide and the intracellular mature RNase contained several peptides of identical mobility. Immunoprecipitates from cells labeled in the presence of tunicamycin contained 66- and 45-kilodalton polypeptides. Endoglycosidase H treatment of the 73-kilodalton polypeptide converted it to a 66-kilodalton form, but did not change the apparent molecular weight of the mature form of the RNase. Labeling kinetics from pulse-chase experiments did not clearly support a precursor-product relationship between the 73-kilodalton polypeptide and the intracellular 45-kilodalton form of the RNase, and other relationships between the two polypeptides are possible.
Carbohydrates↗
Acute hemofiltration in intensive care setting.
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Acute Kidney Injury↗
Dexamethasone suppression test in Parkinson's disease.
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Aged↗
Vitamin E in young and old human red blood cells .
Young and old human red blood cells contain about the same amount of alpha-tocopherol, a compound which has previously been shown to be the major lipid-soluble, chain-breaking antioxidant present in such cells. Since red blood cells lose up to ca. 20% of lipid material from their membrane as they age, the alpha-tocopherol/membrane-lipid ratio actually rises with age rather than declining as might have been expected on the basis of the free radical theory of aging. The alpha-tocopherol/arachidonic acid moiety ratios increase in the order: young red blood cells less than old red blood cells less than plasma, which argues against the suggested membrane stabilizing effect of alpha-tocopherol/arachidonic acid moiety complexes.
Adult↗
Multiple neuromuscular blocking agents and reversal in a patient with absent plasma cholinesterase.
The detailed clinical response of a patient with absent plasma cholinesterase (genotype E1s E1s) who received tubocurarine (3 mg), succinylcholine (120 mg), pancuronium (2 mg), and reversal with neostigmine (3 mg) is reported. The patient's responses were compared to the responses of a group of patients with genotype E1a E1a evaluated prospectively, and with eight other genotype E1s E1s patients reported in the literature. The present patient demonstrated evidence of a phase II block before and after attempted reversal, suggesting that free succinylcholine was present in her plasma and a mixed block was present at that time. Conservative supportive therapy was continued and a complete recovery resulted five hours and 30 minutes after the succinylcholine administration.
Adult↗
Length of the distal esophageal sphincter and competency of the cardia.
Pressure and abdominal length of the distal esophageal sphincter are important factors in maintaining competency of the cardia against challenges of intraabdominal pressure. Some patients with normal distal esophageal sphincter pressure and position may have reflux which could be due to the inability of the cardia to overcome challenges of intragastric pressure. Three experimental studies and one clinical study were designed to evaluate this problem. The results showed that the resistance to flow through the cardia is related to the integrated effect of distal esophageal sphincter pressure and length; the ratio of distal esophageal sphincter to intragastric pressure necessary to maintain competency is inversely related to the length of sphincter present; gastric dilatation has an adverse effect on the degree of competency achieved by a given distal esophageal sphincter length; and patients with an overall distal esophageal sphincter length of 2 cm or less measured at rest in the fasting state are subject to reflux caused by gastric dilatation, increased intragastric pressure independent of intraabdominal pressure, or both.
Adolescent↗
Fractionation and characterization of a yeast mRNA splicing extract.
We have fractionated a yeast whole cell extract that can accurately splice synthetic actin and CYH2 pre-mRNAs. Three fractions, designated I, II, and III, have been separated by use of ammonium sulfate fractionation and chromatography on heparin agarose. Each fraction alone has no splicing activity. Fractions I and II allow the first step of the splicing reaction to proceed, giving rise to the splicing intermediates, free exon 1, and intron-exon 2. Addition of fraction III completes the reaction. Micrococcal nuclease treatment of the whole cell extract or of either fraction I or II abolished splicing activity, indicating that fractions I and II have RNA moieties that are required in the splicing reaction. The nature of the RNAs was examined using antibodies directed against the trimethylated cap structure unique to small nuclear RNAs. Preincubation of the whole cell extract with protein A-Sepharose coupled to trimethylated cap antibody abolished splicing activity. This indicates that at least one essential RNA component contains a trimethyl cap. Thus, in yeast as in mammalian systems, small nuclear RNAs are involved in mRNA splicing.
Cell Fractionation↗
Extracellular RNase produced by Yarrowia lipolytica.
Production of extracellular RNase(s) by Yarrowia lipolytica CX161-1B was examined in media between pHs 5 and 7. RNase production occurred during the exponential growth phase. High-molecular-weight nitrogen compounds supported the highest levels of RNase production. Several RNases were detected in the supernatant medium. Based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the RNases had estimated molecular weights of 45,000, 43,000, and 34,000. It was found that Y. lipolytica secretes only one RNase (the 45,000-molecular-weight RNase) and that the 43,000 and 34,000-molecular-weight RNases are degradation products of this RNase. The alkaline extracellular protease secreted by Y. lipolytica was shown to have a major role in the 45,000- to 43,000-molecular-weight conversion, and it was demonstrated that the 45,000-molecular-weight RNase could be purified from a mutant which does not produce the alkaline extracellular protease. Purification of the RNase from a wild-type strain resulted in purification of the 43,000-molecular-weight RNase. This RNase was a glycoprotein with a molecular weight of 44,000 as estimated by gel filtration, an isoelectric point of pH 4.8, and a pH optimum between 6.5 and 7.0.
Culture Media↗
Fc and C3b receptor expression of phagocytes in poorly controlled diabetic patients.
Attachment, an energy-independent step, of sensitized sheep erythrocytes EA and EAC to Fc and C3b receptors, respectively, on granulocytes and monocytes from poorly controlled diabetic patients was investigated. The results show similar percentages of EA and EAC rosette-forming cells for normal and diabetic human neutrophils. The expression of Fc receptors on normal and diabetic monocytes were also similar in that the former contained 74.5 +/- 9.3% and the latter contained 66.0 +/- 9.4% rosette-forming cells. However, a significantly lower percentage (48.3 +/- 15.2%) of EAC rosette positive cells was found in diabetic monocytes as compared to that (68.1 +/- 8.2%) found in normal controls (p less than 0.001). Incubation of diabetic monocytes with insulin or serum obtained from normal individuals one hour prior to assay corrected the impaired expression of C3b receptors in diabetic monocytes. In addition, we also found that diabetic serum itself is noxious to C3b receptor expression by normal human monocytes and that high concentrations of glucose play no apparent role in the regulation of the receptor function.
Adult↗
Psychotropic medication and nonfatal cafe coronary.
Obstructive asphyxia, also known as cafe coronary, has been linked to both medicated and nonmedicated psychiatric patients. An 18-month prospective audit of choking patients was conducted in a psychiatric hospital. Based upon all medications received in the 5 days preceding the event, mean daily chlorpromazine and atropine equivalent dosages were also calculated for age, sex, and diagnosis matched controls based upon all medications received during their entire hospital stay. Paired t-tests showed no significant differences between choking patients and their matched controls except that greater mean daily chlorpromazine equivalents were present in the severe choking subgroup. Computation of log odds of choking risk increases with interaction of increased mean doses of each drug type and age, and also with interaction of increased chlorpromazine equivalents and increased atropine equivalents. Patients receiving high dosages of drug(s) with antidopaminergic or anticholinergic activity are at greater risk of choking and should be monitored closely.
Age Factors↗
Yeast mRNA splicing in vitro.
Synthetic actin and CYH2 pre-mRNAs containing a single intron are accurately spliced in a soluble whole cell extract of yeast. Splicing in vitro requires ATP. The excised intron is released as a lariat in which an RNA branch connects the 5' end of the molecule to the last A in the "intron conserved sequence" UACUAAC. Two other discrete RNA species produced during splicing in vitro may represent reaction intermediates: free, linear exon 1 and a form of the intron lariat extending beyond the 3' splice site to include exon 2. Both lariat forms correspond to molecules previously shown to be produced during yeast pre-mRNA splicing in vivo.
Actins↗