101
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Abstract
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.
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102
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Abstract
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.
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103
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Abstract
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.
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104
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Abstract
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.
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105
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Dykes MH, Cheng SC, Cohen H, Valle RF. Multiple neuromuscular blocking agents and reversal in a patient with absent plasma cholinesterase. CANADIAN ANAESTHETISTS' SOCIETY JOURNAL 1986; 33:657-61. [PMID: 3768770 DOI: 10.1007/bf03014273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
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.
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106
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Burton GW, Cheng SC, Webb A, Ingold KU. Vitamin E in young and old human red blood cells . BIOCHIMICA ET BIOPHYSICA ACTA 1986; 860:84-90. [PMID: 3089279 DOI: 10.1016/0005-2736(86)90501-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
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.
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107
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Cheng SC, Abelson J. Fractionation and characterization of a yeast mRNA splicing extract. Proc Natl Acad Sci U S A 1986; 83:2387-91. [PMID: 3517868 PMCID: PMC323302 DOI: 10.1073/pnas.83.8.2387] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
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.
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108
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Hsieh HH, Bhatia SC, Andersen JM, Cheng SC. Psychotropic medication and nonfatal cafe coronary. J Clin Psychopharmacol 1986; 6:101-2. [PMID: 3700693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
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.
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109
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Bonavina L, Evander A, DeMeester TR, Walther B, Cheng SC, Palazzo L, Concannon JL. Length of the distal esophageal sphincter and competency of the cardia. Am J Surg 1986; 151:25-34. [PMID: 3946748 DOI: 10.1016/0002-9610(86)90007-3] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
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.
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110
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Lin RJ, Newman AJ, Cheng SC, Abelson J. Yeast mRNA splicing in vitro. J Biol Chem 1985; 260:14780-92. [PMID: 2997224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
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.
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111
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Luo ZM, Cheng SC, Wu YX. [Changes in plasma CK and CK-MB activity following permanent pacemaker implantation and its clinical significance]. ZHONGHUA NEI KE ZA ZHI 1985; 24:655-8, 701. [PMID: 3833503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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112
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Abstract
The authors have postulated previously that general anesthetic agents act via a potentiation of the inhibitory action of gamma-aminobutyric acid (GABA) at central synapses. If the hypothesis is true, GABA should induce anesthesia, however, GABA itself does not pass through the blood-brain barrier. A GABA analog was sought as a substitute to test the authors' hypothesis. A new bicyclic GABA analog, THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) was selected because its properties are similar to GABA in vitro. THIP was found to induce anesthesia in rodents, and its behavior was compared with that of thiopental, ketamine, midazolam, and gamma-hydroxybutyrate. Complete loss of righting reflex occurred with doses of THIP and thiopental just under 100 mumol/kg, with ketamine and midazolam less than 50 mumol/kg and with gamma-hydroxybutyrate of more than 6,000 mumol/kg. Complete recovery from thiopental and ketamine occurred in less than 5 min, with midazolam recovery required about half an hour and with gamma-hydroxybutyrate and THIP it took about 1 1/2 h. THIP induced analgesia as well as sedation and loss of righting reflex. Recovery was complete, and no adverse effects were noted in these rodents.
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113
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Newman AJ, Lin RJ, Cheng SC, Abelson J. Molecular consequences of specific intron mutations on yeast mRNA splicing in vivo and in vitro. Cell 1985; 42:335-44. [PMID: 3893746 DOI: 10.1016/s0092-8674(85)80129-x] [Citation(s) in RCA: 145] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
We have altered the TACTAAC sequence in the yeast CYH2m gene intron to TACTACC. This mutation changes the nucleotide at the normal position of the branch in intron RNA lariats produced during pre-mRNA splicing, and it prevents splicing in vivo. In a yeast pre-mRNA splicing system, CYH2m pre-mRNA carrying the TACTACC mutation is not specifically cut or rearranged in any way. Substitution of an A for the first G of the CYH2m intron, converting the highly conserved GTATGT 5' splice site sequence to ATATGT, also blocks intron excision in vivo and in vitro: pre-mRNA carrying this mutation was still cut normally at the mutant 5' splice site in vitro, to give authentic exon 1 and an intron-exon 2 lariat RNA with an A-A 2'-5' phosphodiester linkage at the branch point. This lariat RNA is a dead-end product. The subsequent cleavage at the 3' splice site is therefore sensitive to the sequence of the 5' end of the intron attached at the branch point.
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114
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115
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Benzon HT, Cheng SC, Avram MJ, Molloy RE. Sign of complete sympathetic blockade: sweat test or sympathogalvanic response? Anesth Analg 1985; 64:415-9. [PMID: 3985390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The sensitivity, specificity, and accuracy of the cobalt blue and ninhydrin sweat tests were compared with the sympathogalvanic response (SGR) in assessment of complete sympathetic blockade. Patients were randomly assigned to receive epidural administration of either preservative-free physiologic saline solution and 80 mg methylprednisolone (group I, control group, 9 patients) or 1.5% lidocaine with 80 mg methylprednisolone (group II, sympathetic blocked group, 10 patients). In group I, there was one false positive SGR (absence of SGR) before the block and there were four false positive SGRs after the block. In comparison, there were no false positive sweat tests (absence of sweating) before and after injection in group I. In group II, there were three false positive SGRs and no false positive sweat test before injection. After injection, one patient with an upper level of sensory blockade at T5 had persistent SGRs and positive sweat tests (false negative results). The study showed the sensitivity of the SGR and the sweat tests to be 90%. The specificity of the SGR was 56% compared to 100% for the sweat tests. The accuracy of the SGR was 74% compared to 95% for the sweat tests.
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116
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Abstract
Three ovarian-cancer-prone kindreds were studied, two of which contained identical twin sisters concordant for ovarian carcinoma. In one kindred, both identical twin sisters had daughters with ovarian carcinoma. In another kindred, one of the identical twin sisters had an ovarian-cancer-affected daughter. Ovarian carcinoma showed vertical transmission in all three families in a pattern consonant with an autosomal dominant mode of inheritance. Medical-genetic survey of each family included detailed questionnaires with retrieval of primary medical and pathology documents on cancer of all anatomic sites. Putative biomarker determinations included: (1) in vitro hyperdiploidy in dermal monolayer cultures; and (2) lower serum levels of alpha-L-fucosidase (less than or equal to 275 IU/ml) in all cancer-affected patients and statistically significant lower levels in 50% risk individuals when compared to spouse and published controls (P = 0.04 and P = 0.0002, respectively). These findings are discussed in context with the eventual development of a risk factor profile which, given acceptable sensitivity and specificity, would enable identification of individuals who would be prime candidates for intensive surveillance/management programs.
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117
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Cheng SC, Herman G, Modrich P. Extent of equilibrium perturbation of the DNA helix upon enzymatic methylation of adenine residues. J Biol Chem 1985; 260:191-4. [PMID: 3880739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The extent of equilibrium perturbation of the DNA helix associated with enzymatic methylation of dA residues has been determined by the agarose gel electrophoresis band-shift method. Utilization of EcoRI methylase under conditions of reduced specificity together with Escherichia coli dam methylase permitted modification of up to 300 dA residues/plasmid pBR322 dimer. A conformational change associated with methylation was observed, with the magnitude of the transition being linear with extent of modification of relaxed DNA circles. The conformational change corresponds to an unwinding of the DNA helix by 0.5 degrees/methyl group transferred to relaxed molecules. The magnitude of the effect was independent of temperature from 5-37 degrees C indicating that it is not the consequence of a thermal transition within this range.
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118
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Cheng SC, Herman G, Modrich P. Extent of equilibrium perturbation of the DNA helix upon enzymatic methylation of adenine residues. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)89714-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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119
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Cheng SC, Kim R, King K, Kim SH, Modrich P. Isolation of gram quantities of EcoRI restriction and modification enzymes from an overproducing strain. J Biol Chem 1984; 259:11571-5. [PMID: 6088551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Structural genes for EcoRI restriction endonuclease and modification methylase have been inserted into the plasmid vector pKC30 (Shimatake, H., and Rosenberg, M. (1981) Nature (Lond.) 292, 128-132) downstream from the bacteriophage lambda pL promoter. Upon induction of pL expression in strains producing a thermolabile lambda cI857 repressor, synthesis of EcoRI polypeptides is enhanced to the extent that after 4 h they represent several per cent of the total cell protein. Purification of activities overproduced in this manner yields preparations of endonuclease and methylase which appear identical to those obtained from conventional sources, with overall yields corresponding to 0.5 to 0.9 g of each enzyme/kg of cell paste.
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120
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Cheng RH, Majlessi MR, Cheng SC. Utilization of Barritt color reaction for studying synaptosomal creatine phosphokinase. Neurochem Res 1984; 9:571-6. [PMID: 6462328 DOI: 10.1007/bf00964384] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The assay for creatine phosphokinase activity depending upon the color formation from creatine was reinvestigated. Its sensitivity was improved to 5 nmol of creatine. The method gave satisfactory Michaelis constants for both creatine phosphate and adenosine-diphosphate and was useful in detecting low creatine phosphokinase activity.
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121
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Abstract
GABA-transaminase has been found to be released from rat brain synaptosomes by halothane in a dose-related manner. The releases of both GABA-transaminase and succinic semialdehyde dehydrogenase were increased with time. The release of other enzymes (creatine kinase, glutamate decarboxylase, aspartate transaminase, lactate dehydrogenase, and malate dehydrogenase) was less in magnitude and not related to the duration of incubation. Such observations suggested a specific event in the halothane-induced release of GABA-catabolizing enzymes. A suggestion linking mode of anesthetic action to a mitochondrial effect of volatile anesthetics was made.
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122
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Lynch HT, Albano WA, Danes BS, Layton MA, Kimberling WJ, Lynch JF, Cheng SC, Costello KA, Mulcahy GM, Wagner CA. Genetic predisposition to breast cancer. Cancer 1984; 53:612-22. [PMID: 6581856 DOI: 10.1002/1097-0142(19840201)53:3+<612::aid-cncr2820531306>3.0.co;2-5] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Breast cancer risk factors are closely intertwined with the patient's cultural background, which may contribute to breast cancer aggregations within families. The difficult questions are: (1) does a truly hereditary breast cancer subset exist; (2) which familial aggregations are hereditary; and (3) is the hereditary form distinctive from its sporadic counterpart? These queries will be resolved once biomarkers are identified that show high sensitivity and specificity with genotype. The authors provide a review of this subject and will focus on their recent discovery of increased in vitro hyperdiploidy in cultured skin fibroblasts from patients with or at risk for hereditary breast cancer. The authors discuss findings from their study of family histories in 225 consecutively ascertained patients with verified breast cancer from the Creighton University School of Medicine Oncology Clinic. Findings consistent with an hereditary breast cancer syndrome were identified in 5% of the patients. Given the 112,000 new cases of breast cancer in the United States in 1982, the authors estimate that with a confidence coefficient of 0.95 between 2410 and 8790 of these individuals will manifest hereditary breast cancer. Specific surveillance/management programs should be geared to high-risk members of these families in which cancer yield will be predictable.
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123
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Abstract
Plasmid pSCC31 contains the EcoRI endonuclease gene downstream from lambda pL. It does not yield transformants upon introduction into Escherichia coli unless the structural integrity of the endonuclease is destroyed. This makes it useful as a positive-selection cloning vehicle which can be employed for regulated overproduction of hybrid proteins.
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124
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Ni C, Cheng SC, Dryja TP, Cheng TY. Lacrimal gland tumors: a clinicopathological analysis of 160 cases. Int Ophthalmol Clin 1982; 22:99-120. [PMID: 6277818 DOI: 10.1097/00004397-198202210-00009] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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125
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Abstract
In brain slices, halothane was shown to inhibit the metabolic breakdown of GABA (gamma-aminobutyric acid), an inhibitory neurotransmitter. This inhibition leads to increased brain GABA content, presumably in the synaptic areas, and to the postulation that halothane anesthesia may arise from an enhanced synaptic inhibition due to this elevated GABA. The ability of many neurotropic agents to inhibit GABA breakdown was studied by assessing synaptosomal "GABA disposal". GABA disposal by intact synaptosomes, which simulate miniature synapses, measures the conversion of [1-14C]GABA to 14CO2 and includes the processes of uptake, release, and catabolism of GABA. The most potent inhibitor is chloroform, followed by halothane, enflurane, ether, and thiopental. Pentobarbital, ethanol, paraldehyde, and ketamine are weak inhibitors. Phenobarbital, morphine, and phenytoin are not inhibitory at pharmacologic concentrations. As a whole, anesthetic agents show particular inhibitory action on this metabolic process in this model system where the ID10 values (i.e., concentration of a drug necessary to produce 10 per cent inhibition of GABA disposal) correlate well with known pharmacologic potencies, ED50 values, or MACs. These observations support the possibility that anesthesia may be related to an inhibition of GABA disposal.
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