Search PubMed⌕ Search

Biomedical subjects

J Scott

Publications and source records attributed to J Scott.

At least 325 records · Page 18Linked to original sources
PubMed1993

Molecular and genetic analyses of the B type surface protein gene from Paramecium tetraurelia.

The gene encoding the B type variable surface protein from Paramecium tetraurelia stock 51 has been cloned and sequenced. The 7,182 nucleotide open reading frame contains no introns and encodes a cysteine-rich protein that has a periodic structure including three nearly perfect tandem repeats in the central region. Interestingly, the B gene is located near a macronuclear telomere as was shown previously for two other paramecium surface protein genes. In this paper, we characterize four independent mutants with complete macronuclear deletions of the B gene. Previous analysis of different macronuclear deletion mutants of the A surface protein gene demonstrated two types of inheritance: typical Mendelian segregation (as illustrated by d12) and cytoplasmic inheritance (shown by d48). F1 analysis of four B- mutants crossed with wild-type cells reveals heterozygous F1 cell lines derived from both parental cytoplasms contain approximately the same copy number of the B gene, as expected for a recessive Mendelian mutation. Analysis of F2 progeny from three of these four B- mutant crosses indicates that one of the three exhibits a Mendelian 1:1 segregation ratio of B+ and B- cell lines. The other two show a preponderance of B+ cells, but this is not correlated with the parental cytoplasmic type. In addition to having a large number of B+ individuals, the d12.144, A-, B- mutant produced some F2 progeny that stably maintain less than normal macronuclear amounts of the A gene and/or the B gene.

Animals↗
PubMed1993

A training program in universal precautions for second-year medical students.

BACKGROUND: A training program in universal precautions was developed and implemented in 1991-92 for second-year students at the George Washington University School of Medicine and Health Sciences. The students were required to participate in a three-hour session that consisted of lecture, demonstration, and practice components focused on the risks of bloodborne-disease exposure and the techniques of phlebotomy and intravenous insertion using universal precautions. METHOD: All 135 second-year students participated in the lecture component, but only 120 students, who were unfamiliar with the procedures, were required to participate in the demonstration and practice components. Each of these students was asked to answer pre- and postsession knowledge questions and to rate his or her preparedness on a five-point Likert scale, ranging from 1, "not prepared at all," to 5, "well prepared." Paired t-tests were used to compare the pre- and postsession knowledge scores and self-assessed preparedness scores. At the end of the training program, the students were offered the opportunity to volunteer for additional, individualized training with the hospital phlebotomy service. Unpaired t-tests were used to compare differences between the postsession knowledge scores of the volunteers and nonvolunteers. RESULTS: A total of 103 students completed both pre- and posttests. The students' knowledge scores increased from means of 64.7% to 88.5% (p = .001). Their self-assessed preparedness scores also increased, ranging from a low of means of 1.6 presession and 3.4 postsession for intravenous insertion to a high of means of 3.19 presession and 4.26 postsession for addressing personal concerns about possible exposure. The 43 students who volunteered for additional training scored significantly better on the postsession knowledge questions than did the nonvolunteers, suggesting that those who may have needed it most failed to sign up for additional training. CONCLUSION: The training session significantly improved the students' knowledge and sense of their own competency.

Curriculum↗
PubMed1993

Radiofrequency catheter ablation for AV nodal reentry: a technique for rapid transection of the slow AV nodal pathway.

Selective radiofrequency (RF) catheter ablation of the slow AV nodal pathway has shed new light on the anatomy and physiology of the atrioventricular junction. The recording of "slow pathway potentials" facilitates localization of the slow pathway and has led to a concept of multiple pathway components with atrial insertion sites covering a potentially broad region surrounding the coronary sinus os. The critical area for complete interruption of the slow pathway may be larger than lesion size produced by ablation at a single site, resulting in multiple RF applications with lengthy sessions and prolonged radiation exposure. Information from both old and recent literature suggests that the slow AV nodal pathway is represented by a group of fibers originating from the posteroinferior interatrial septum and coursing anterosuperiorly near the tricuspid annulus before converging upon the compact AV node. Based on this anatomical arrangement, the present study was conducted to evaluate a technique designed to transect the slow pathway by producing a linear RF lesion perpendicular to the orientation of the slow pathway within the mid-portion of Koch's triangle. Using this technique, 30 of 30 patients with common AV nodal reentry were rendered noninducible using 1 to 3 RF applications. Total procedure time averaged 3.4 +/- 1.1 hours and fluoroscopy time averaged 14.8 +/- 4.6 minutes. As a marker of efficacy, episodic nonsustained atrial tachycardia (NSAT) during RF delivery occurred in 28 of 30 (93%) successful applications. Three patients experienced tachycardia recurrence and were successfully ablated by repeat procedure. Conduction characteristics and refractoriness of the fast pathway were unchanged in 23 of 23 patients reevaluated at a mean of 7.2 weeks postablation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Patterns of treatment resistance in bipolar affective disorder.

The mean index episode length in 19 consecutive admissions with treatment-resistant bipolar affective disorder was 21.7 months. Four patterns of resistance were identified: rapid cycling (37%), other forms of cycling (32%), chronic depression (26%) and mixed states (6%). Female gender was significantly associated with rapid cycling. Other risk factors for treatment-resistant bipolar disorder, including a high prevalence of family history of affective disorder (72%) and electroencephalographic abnormalities (54% of recordings), were not confined to the rapid cycling group.

Adult↗
PubMed1993

Yersinia enterocolitica septicaemia from transfusion of red cell concentrate stored for 16 days.

Two cases of transfusion transmitted Yersinia enterocolitica biotype 3, serotype 09 infection occurred in south east Scotland within four months of each other. In one case, a 79 year old man died the day after receiving a unit of red cell concentrate that had been stored for 29 days after donation. In the second case a 78 year old man died three days after transfusion of a unit of red cell concentrate that had been collected 16 days before transfusion. The donors of both units had no symptoms attributed to gastrointestinal infection. Early outdating of blood for transfusion after three weeks of storage is unlikely to eradicate Y enterocolitica associated fatalities from blood transfusion, and alternative methods should be considered.

Aged↗
PubMed1993

Stable isotopes show a direct relation between VLDL apoB overproduction and serum triglyceride levels and indicate a metabolically and biochemically coherent basis for familial combined hyperlipidemia.

Familial combined hyperlipidemia (FCHL) may be genetically and metabolically more heterogeneous than previously thought. A consistent feature is an increase in circulating very-low-density lipoprotein (VLDL) apolipoprotein (apo) B, which could be due to either an increase in apoB production or a decrease in its catabolism. Therefore, we directly measured VLDL apoB production in the postabsorptive state in seven FCHL subjects (four male, three female) and seven normal control subjects (three male, four female) by using L-[1-13C]leucine as an endogenous label. Mean age and body mass index did not differ significantly between the two groups. The mean total cholesterol levels were 4.7 +/- 0.8 and 8.8 +/- 1.6 mmol/L (+/- SD, P < .01) and the mean triglyceride levels were 0.84 +/- 0.14 and 3.30 +/- 1.10 mmol/L (+/- SD, P < .01) in the control and FCHL groups, respectively. Although the fractional production rate of VLDL apoB was 38% lower in the FCHL group than in the control subjects (0.11 +/- 0.03 versus 0.18 +/- 0.02 pool/h; mean +/- SD, P < .01), its absolute production rate was 2.7 times greater (534 +/- 193 micrograms/kg per hour in FCHL versus 196 +/- 71 micrograms/kg per hour in control subjects; mean +/- SD, P < .01). There was a linear relation (r = 0.8, P = .03) between triglyceride levels and the VLDL apoB production rate in FCHL, the slope of which indicated a similar VLDL triglyceride-to-apoB ratio in the FCHL and control groups. We conclude that FCHL is a metabolically coherent disorder and that the increase in circulating apoB and triglyceride levels in FCHL is due to secretion of an increased number of VLDL particles, each containing, on average, a normal amount of triglyceride and one molecule of apoB.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Bronchoalveolar lavage and transbronchial lung biopsy during acute rejection and infection in heart-lung transplant patients. Studies of cell counts, lymphocyte phenotypes, and expression of HLA-DR and interleukin-2 receptor.

The total and differential cell counts of 135 bronchoalveolar lavages (BAL) in 48 heart-lung transplant (HLT) patients were compared with the histologic findings in concurrent transbronchial lung biopsies (TBBs). Counts of CD3+, CD4+, and CD8+ lymphocytes were recorded, and a semiquantitative assessment of HLA-DR and interleukin-2 receptor (IL-2R) expression was made on 29 occasions. There were five diagnostic categories: normal (n = 8), acute rejection (ALR) (n = 57), treated rejection (TR) (n = 19), infection (INF) (n = 24), and chronic rejection (CR) (n = 24). Total cell counts in INF were significantly higher than counts in all the other diagnostic groups. The highest BAL lymphocyte counts, significantly higher than in INF, were found in ALR because of increased CD8+ cells, exceeding 15% in 13 of 57 BALs. TBBs in ALR by contrast showed significantly increased numbers of both CD8+ and CD4+ cells. High dose corticosteroid treatment of ALR caused a fall in cellularity of BAL and TBB specimens but not always to values seen when patients were well. During INF and CR, significantly increased numbers of PMNs were seen in the BAL. HLA-DR and IL-2R expression was enhanced in cells of BAL and TBB in all complications. BAL can only supplement at present histologic examination of TBB in the diagnosis of complications after HLT.

Acute Disease↗
PubMed1993

Autobiographical memory in depression: state or trait marker?

Two cognitive measures were used to assess 22 patients who met DSM-III-R criteria for major depressive disorder: the Autobiographical Memory (AM) test and the Dysfunctional Attitude Scale. They were followed up over seven months. Measurement of dysfunctional attitudes did not predict outcome at seven months. Overgeneral recall on the AM test at initial assessment, especially for emotionally positive memories, was highly correlated with failure to recover from depression and accounted for 33% of the variance in HRSD score at follow-up. Overgeneral recall of emotional memories did not change during follow-up. It is suggested that overgenerality is a trait marker indicating vulnerability to persistent depression.

Adult↗
PubMed1993

Homelessness and mental illness.

In Great Britain 1-2 million people may be homeless. Most homeless people are men, but about 10-25% are women, of whom about half are accompanied by children. Significant mental illness is present in 30-50% of the homeless: functional psychoses predominate; acute distress and personality dysfunction are also prevalent. Co-morbidity of mental illness and substance abuse occurs in 20%, and physical morbidity rates exceed those of domiciled populations. The homeless mentally ill also have many social needs. Pathways to homelessness are complex; deinstitutionalization may be only one possible cause of the increase in the number of homeless people. There is much recent research estimating the extent of mental illness and the characteristics of selected subgroups of accessible homeless people. The evaluation of potential service solutions has received less attention. This review outlines the research, highlights current views on the definition and classification of homeless populations, and offers some guidelines on avenues which need to be explored.

Cross-Cultural Comparison↗
PubMed1993

Effects of elevating blood alcohol levels on tasks related to dart throwing.

Light (0.02% BAC) and moderate (0.05% BAC) does of alcohol were administered to 10 dart throwers while effects were monitored on tasks related to dart throwing, i.e., rotary pursuit and hand steadiness. Balance and accuracy of throwing improved with the 0.02% BAC, but performance was impaired with 0.05% BAC. The higher BAC levels were linked with deteriorations on rotary pursuit and hand steadiness.

Adult↗
PubMed1992

The quantitative analysis of endogenous folate catabolites in human urine.

In man folates are catabolized and excreted as inactive cleaved degradation products, a mixture of pteridines and p-aminobenzoylglutamate (pABGlu) or its acetamido derivative (apABGlu). The daily rate of excretion represents the inescapable use of the vitamin in metabolic activity and thus has implications for determining the recommended dietary allowance for the vitamin. Furthermore, the rate of catabolism has been suggested to rise during pregnancy and in certain disease states. A method is described for the quantitative extraction and assay of the folate catabolites pABGlu and apABGlu in human urine. Aliquots of 24-h urine collections are acidified and applied to columns of Dowex 50W cation-exchange resin. The catabolites are selectively batch-eluted with increasing concentrations of HCl. The fraction containing pABGlu is diazotized and then applied to a C18 Sep Pak column for further purification and concentration. The fraction containing apABGlu was deacetylated and reapplied to the Dowex column and then treated identically to the pABGlu fraction. The methanolic concentrates of both extracts were evaporated to dryness and reconstituted with water and pABGlu was regenerated by reductive cleavage of the diazotized material with Zn/HCl. The extracts of the two catabolites were separated by reverse-phase HPLC using a Radial Pak C18 column. Recovery of isolated material was monitored by the addition of high specific activity tritiated labels of both compounds added as internal standards to all urine aliquots prior to purification and analysis.

4-Aminobenzoic Acid↗
PubMed1992

Oleate-mediated stimulation of apolipoprotein B secretion from rat hepatoma cells. A function of the ability of apolipoprotein B to direct lipoprotein assembly and escape presecretory degradation.

Physiological concentrations of oleate stimulate apolipoprotein (apo) B-containing lipoprotein secretion from HepG2 cells without increasing apoB mRNA levels. The purpose of this study was to determine whether oleate acts by increasing translation of apoB mRNA or through posttranslational effects on the apoB protein. To address the mechanism of oleate-stimulated secretion of apoB, a series of carboxyl terminally truncated apoB constructs was made. Each contained the SV40 early promoter, the apoB 5'-untranslated region, and SV40 polyadenylation signals. Any difference in the response to oleate between endogenous apoB and the proteins encoded by the constructs or between the constructs themselves should thus depend on the protein sequence. Stable transformants were established for each of the constructs in the rat hepatoma cell line McArdle-RH7777. The effect of oleate on secretion of the apoB protein products was determined by labeling with [35S]methionine, immunoprecipitation, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Carboxyl-terminal truncation of apoB41 resulted in a loss of the ability of apoB secretion to respond to oleate. Ultracentrifugation of secreted proteins on continuous CsCl gradients from 1.0-1.4 g/ml revealed that this correlated with a decrease in the ability of apoB to be recovered as a buoyant lipoprotein particle. Addition of oleate decreased the densities at which the short forms of apoB secreted as lipoproteins were recovered. Pulse-chase analysis of the secretion of apoB100 and of the truncated proteins revealed that they all underwent rapid posttranslational intracellular degradation. We conclude that oleate has no effect on the translation of apoB mRNA but promotes the secretion of apoB-containing lipoproteins by reducing presecretory degradation of those forms of apoB that can produce buoyant lipoproteins.

Animals↗
PubMed1992

The assembly and secretion of ApoB 100-containing lipoproteins in Hep G2 cells. ApoB 100 is cotranslationally integrated into lipoproteins.

The possibility that apoB 100 is cotranslationally translocated to the endoplasmic reticulum lumen and integrated into lipoproteins has been investigated. ApoB 100 nascent polypeptides were shown to be secreted from pulse-labeled Hep G2 cells after treatment with puromycin and chase for 1 or 2 h in the presence of puromycin and cycloheximide. These nascent polypeptides banded during sucrose gradient ultracentrifugation between the position of the high (HDL) and the low (LDL) density lipoproteins, revealing an inverse relationship between the length of the polypeptide and the density of the fraction. ApoB 100 occurred in the position of LDL and very low density lipoproteins (VLDL). Electronmicroscopy studies of the apoB-containing particles from the gradient indicated an increase in size with increasing length of the polypeptide. Furthermore, labeling studies indicated that the triglyceride load increased with the length of the polypeptide. An inverse relationship between the size of C-terminally truncated apoB polypeptides and the density of the assembled lipoproteins was also observed in experiments with transfected minigenes coding for apoB 41, apoB 29, and apoB 23. These proteins appeared on HDL particles. Pulse-chase experiments indicated that 80-200-kDa apoB nascent polypeptides on particles with HDL density, with time, were converted into larger polypeptides on lighter particles, to be fully replaced by apoB 100 on LDL-VLDL particles. The formation of these LDL-VLDL particles could be blocked by cycloheximide. Sixty-five percent of pulse-labeled apoB nascent polypeptides present in the microsomal fraction was released by sodium carbonate treatment, and 77% of these polypeptides could be recovered on the immature particles (banding between HDL and LDL) after sucrose gradient ultracentrifugation. Pulse-chase experiments indicated that these nascent polypeptides, on the immature lipoproteins, had the capacity to be precursors for all the apoB 100-containing LDL and VLDL particles formed in the cell. The obtained results indicate that a major portion of the apoB nascent polypeptides in the cell form lipoproteins cotranslationally during the translocation to the lumen of the endoplasmic reticulum.

Apolipoprotein B-100↗
PubMed1992

Coronary flow reserve is impaired early after cardiac transplantation.

The highest mortality rate after cardiac transplantation, at present, occurs within the first year after cardiac transplantation. The state of the coronary microcirculation soon after cardiac transplantation has not been previously assessed. We investigated the hypothesis that coronary flow reserve (CFR) is impaired in the early postoperative period after cardiac transplantation. A 3F intracoronary Doppler flow probe was inserted into the left anterior descending coronary artery and maximal coronary flow was assessed using the non-endothelial-dependent vasodilator papaverine. We compared two groups of patients: group A--13 patients studied 3 months after operation; and group B--25 patients studied at a median of 4 years after operation (range 2-8 years) without coronary occlusive disease (COD). CFR was defined as the quotient of maximum hyperaemic to resting velocity (vel). CFR was markedly impaired in group A patients compared with group B (3.3 SEM 0.3 versus 4.2 SEM 0.2, P < 0.01). No significant differences between mean resting or peak velocities, original diagnosis, age, active rejection, blood pressure, lipid levels, ischaemic time, cyclosporin levels or cytomegalovirus (CMV) status were noted. Responses to papaverine in resistance coronary vessels are impaired in the early postoperative period after cardiac transplantation. This is caused by a combination of higher resting flow and lower peak flow in the early group. This impairment of function in the coronary microcirculation may contribute to early graft dysfunction and reflect changes in vascular smooth muscle function leading to the development of COD.

Adult↗
PubMed1992

Monoclonal antibodies against soman: characterization of soman stereoisomers.

Hybridomas were produced which expressed monoclonal anti-soman antibodies as determined by microtiter enzyme-linked-antibody immunoassay (EIA). Each of these antibodies was titrated using a competitive inhibition enzyme immunoassay (CIEIA) with a variety of test ligands. The ligands used included soman (a racemic mixture), sarin, tabun, and each of the four stereoisomers of soman (C+ P+, C+ P-, C-P+ and C-P-). In all cases the antibodies tested exhibited IC50 values of 10(-4)-5 x 10(-6) M for soman. When sarin or tabun was used as a ligand, the antibodies exhibited no cross reactivity. All of the antibodies cross reacted with the four soman stereoisomers. A second group of hybridomas were produced which expressed monoclonal antibodies against CsPs-soman. These antibodies were used to make preliminary absolute chiral assignments to the four soman stereoisomers.

Animals↗