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Biomedical subjects

A Morris

Publications and source records attributed to A Morris.

At least 91 records · Page 5Linked to original sources
PubMed2000

HIV risk behaviors among Asian drug users in San Francisco.

This study identified patterns of drug use and HIV risk behaviors in relation to cultural factors among Asian drug users in San Francisco. A sample of 92 Asian drug users (35 Chinese, 31 Filipino, 26 Vietnamese) who were not currently enrolled in drug treatment programs were recruited through targeted sampling methods and interviewed using a questionnaire with open-ended questions. The study evaluated responses of the participants based on content analyses. Compared with Chinese and Vietnamese, Filipino drug users had engaged in riskier behaviors in terms of injection drug use, having sex while on drugs, and having sex with injection drug users (IDUs). Cultural factors such as stigma of injection drug use and fear of needles were cited as reasons for not injecting drugs. Among IDUs, half cited trust as a reason for having shared needles. AIDS prevention programs targeting Asian drug users should consider specific cultural factors among high-risk groups (i.e., Filipinos, immigrants, women, and IDUs).

Adult↗
PubMed2000

Temporal evolution in the management of acute ST elevation myocardial infarction: the seven-year GUSTO experience from canada and the united states. The North American GUSTO-I and GUSTO-III investigators.

BACKGROUND: Temporal changes in baseline characteristics, treatment and clinical outcomes of patients presenting with acute ST elevation myocardial infarction in Canada and the United States have not been examined comprehensively over time. OBJECTIVES: To evaluate baseline characteristics, process of care and clinical outcomes. Also, to explore whether earlier process-of-care differences between Canada and the United States had changed and, if so, whether they influenced clinical outcomes. PATIENTS AND METHODS: A total of 13, 888 American and 3011 Canadian patients enrolled in 184 American and 38 Canadian hospitals that participated in both the Global Utilization of Streptokinase and Tissue Plasminogen Activator (alteplase) for Occluded Coronary Arteries (GUSTO-I) trial (1990 to 1993) and the Global Utilization of Strategies to Open Occluded Coronary Arteries (GUSTO-III) trial (1995 to 1997) were studied. Logistic regression was used to identify significant prognostic factors, to assess illness severity at hospital presentation and to classify trends between Canada and the United States. RESULTS: In both countries, illness severity on admission increased, door-to-needle time for thrombolysis was reduced, intensive care unit stay was shortened and hospital stay decreased from GUSTO-I to GUSTO-III. Whereas the administration of oral nitrates, calcium blockers and beta-blockers at discharge converged over time between countries, the disparity in the use of angiography and revascularization widened; the rise in American revascularization rate was most evident in patients without in-hospital ischemia. The 30-day and one-year mortality rates were comparable and declined nonsignificantly in both countries. CONCLUSIONS: Despite increased illness severity and varying medication and procedure rates, there was no increase over time in 30-day or one-year mortality; this remained comparable between countries throughout the seven-year observation period.

Aged↗
PubMed1999

A pilot study of naltrexone-accelerated detoxification in opioid dependence.

OBJECTIVE: 1. To determine whether naltrexone-accelerated detoxification with minimal sedation is an acceptable and effective form of induction onto naltrexone. 2. To monitor outcomes of detoxified patients. DESIGN: Observational study. SETTING: Medical ward of a general hospital (for detoxification) and a community clinic (for follow-up) in Sydney, NSW, 1998. PATIENTS: 15 heroin users and 15 people seeking withdrawal from methadone. INTERVENTION: Detoxification used naltrexone (12.5 or 50 mg), with flunitrazepam (2-3 mg), clonidine (150-750 micrograms) and octreotide (300 micrograms) for symptomatic support. Patients remained awake and were discharged when they felt well enough. Follow-up was daily for four days and then weekly for up to three months for supportive care. MAIN OUTCOME MEASURES: Acute side effects; patient ratings of severity and acceptability of withdrawal; nights of hospitalisation; rates of induction onto naltrexone; retention in treatment over three months; and relapse to opioid use. RESULTS: Acute withdrawal with delirium lasted about four hours. Octreotide was crucial for controlling vomiting; with octreotide no patient required intravenous fluids. There were no major complications. Eighteen patients (60%) reported that it was a "quite" acceptable procedure, 18 (60%) required only one night's hospitalisation, and 24 (80%) were successfully inducted onto naltrexone (defined as taking naltrexone on Day 8). Three months later, six (20%) were still taking naltrexone (with four of these occasionally using heroin) and seven (23%) were abstinent from opioids, including five not taking naltrexone. Eleven had gone onto methadone maintenance, seven had relapsed to heroin use, and one had died of a heroin overdose. CONCLUSIONS: Rates of induction onto naltrexone were comparable with those reported for accelerated detoxification under sedation, suggesting that it can be performed successfully with minimal sedation. As in other studies of naltrexone maintenance, retention was low, and relapse to heroin use was common.

Adolescent↗
PubMed1999

Generalization of the extended transmission disequilibrium test to two unlinked disease loci.

The extended transmission disequilibrium test (ETDT) of Sham and Curtis [1995] is a powerful test of the null hypothesis of no linkage between a multi-allelic marker locus and a disease susceptibility locus of unknown location in the presence of association between alleles at the two loci. We propose a generalization of the ETDT to test simultaneously for linkage of markers to two unlinked disease loci. Analysis of the simulated data for Problem 2 would suggest improvements in power to detect linkage to pairs of disease loci over single locus tests. This is as a result of the two locus model taking account of epistasis between the disease loci.

Alleles↗
PubMed1999

Bacterial vaginosis and past chlamydial infection are strongly and independently associated with tubal infertility but do not affect in vitro fertilization success rates.

OBJECTIVE: To determine the incidence of active vaginal infection in women undergoing IVF, relate it to the cause of infertility, and investigate a relation with the outcome of fresh ET. DESIGN: Cross-sectional study. SETTING: Tertiary care infertility referral center. PATIENT(S): Two hundred eighty-six women who underwent 344 oocyte recovery procedures for IVF cycles between March 1997 and January 1998. INTERVENTION(S): High vaginal swab specimens and endocervical swab specimens were obtained and ELISA serology was performed for detection of Chlamydia species on samples taken immediately before oocyte recovery. The results were related to the cause of infertility and the outcome parameters. MAIN OUTCOME MEASURE(S): Pregnancy rates. RESULT(S): Seropositivity for Chlamydia species and the presence of bacterial vaginosis both were strongly and independently associated with tubal disease. There was no difference in pregnancy rates in any of the groups regardless of their serologic status for chlamydial infection or current infection with bacterial vaginosis. CONCLUSION(S): This study provides further evidence of the pelvic pathogenicity of bacterial vaginosis. However, it shows that women who have bacterial vaginosis or who have been treated for chlamydial infection in the past achieve pregnancy rates with IVF treatment similar to those of women who have no evidence of such infections.

Adult↗
PubMed1999

Nosocomial bacterial meningitis, including central nervous system shunt infections.

Nosocomial bacterial meningitis and CSF shunt infections result in considerable morbidity and mortality, necessitating an organized and thoughtful approach to prevention, diagnosis, and management. Prophylactic antibiotics appear to reduce the rate of postcraniotomy meningitis often caused by S. aureus. On the other hand, prophylactic antibiotics do not appear to reduce the risk of developing a CSF shunt infection. CSF shunt infections usually require shunt removal and antimicrobial chemotherapy to effect a successful outcome.

Anti-Bacterial Agents↗
PubMed1999

Clear correlation of genotype with disease phenotype in very-long-chain acyl-CoA dehydrogenase deficiency.

Very-long-chain acyl-CoA dehydrogenase (VLCAD) catalyzes the initial rate-limiting step in mitochondrial fatty acid beta-oxidation. VLCAD deficiency is clinically heterogenous, with three major phenotypes: a severe childhood form, with early onset, high mortality, and high incidence of cardiomyopathy; a milder childhood form, with later onset, usually with hypoketotic hypoglycemia as the main presenting feature, low mortality, and rare cardiomyopathy; and an adult form, with isolated skeletal muscle involvement, rhabdomyolysis, and myoglobinuria, usually triggered by exercise or fasting. To examine whether these different phenotypes are due to differences in the VLCAD genotype, we investigated 58 different mutations in 55 unrelated patients representing all known clinical phenotypes and correlated the mutation type with the clinical phenotype. Our results show a clear relationship between the nature of the mutation and the severity of disease. Patients with the severe childhood phenotype have mutations that result in no residual enzyme activity, whereas patients with the milder childhood and adult phenotypes have mutations that may result in residual enzyme activity. This clear genotype-phenotype relationship is in sharp contrast to what has been observed in medium-chain acyl-CoA dehydrogenase deficiency, in which no correlation between genotype and phenotype can be established.

Acyl-CoA Dehydrogenase, Long-Chain↗
PubMed1999

Helicobacter pylori-associated antibodies in patients with duodenal ulcer, gastric and oesophageal adenocarcinoma.

OBJECTIVE: To associate Helicobacter pylori-associated antibodies with clinical disease in groups of patients with duodenal ulcer, gastric adenocarcinoma, oesophageal adenocarcinoma and normal mucosa. DESIGN: Prospective observational sero-epidemiology study. Identification of consecutive in-patients with duodenal ulcer, gastric adenocarcinoma, oesophageal adenocarcinoma and normal mucosa. Analyses of sera for antibodies to whole H. pylori, Cag A and Vac A antigens using ELISA and Western blot. Statistical analyses. SETTING: Walsgrave Hospital, Coventry, a district general hospital that serves a population of 350,000. PARTICIPANTS: Consecutive in-patients with an endoscopic diagnosis of duodenal ulcer (n = 31), gastric adenocarcinoma (n = 31), oesophageal adenocarcinoma (n = 40) and normal mucosa (n = 46). MAIN OUTCOME MEASURES: A profile of antibodies was constructed for each patient group and between-group comparisons were made. A logistic regression model determined the H. pylori-associated antibody that could best predict a patient's diagnosis. A discriminatory power for each antibody was calculated. RESULTS: Whole H. pylori, Cag A and Vac A antibodies are found more commonly in duodenal ulcer patients when compared to oesophageal adenocarcinoma (P < 0.003) and normal mucosa patients (P < 0.015). Similarly, gastric adenocarcinoma patients have antibodies to whole H. pylori, Cag A and Vac A more frequently than oesophageal adenocarcinoma (P< 0.002) and normal mucosa patients (P < 0.006). Vac A antibodies discriminate between duodenal ulcer/gastric adenocarcinoma and oesophageal adenocarcinoma/normal mucosa patients (odds ratio 5.56, log likelihood -90.06, P < 0.001) more effectively than Cag A antibodies (odds ratio 4.17, log likelihood -91.88, P < 0.001). CONCLUSIONS: Similar profiles of H. pylori-associated antibodies are seen in patients with duodenal ulcer and gastric adenocarcinoma, confirming that virulent H. pylori are involved in the pathogenesis of both diseases. Antibodies to Vac A could be used to identify patients at increased risk of developing H. pylori-associated disease.

Adenocarcinoma↗
PubMed1999

Mosaic structure of the human immunodeficiency virus type 1 genome infecting lymphoid cells and the brain: evidence for frequent in vivo recombination events in the evolution of regional populations.

In addition to immunodeficiency, human immunodeficiency virus type 1 (HIV-1) can cause cognitive impairment and dementia through direct infection of the brain. To investigate the adaptive process and timing of HIV-1 entry into the central nervous system, we carried out an extensive genetic characterization of variants amplified from different regions of the brain and determined their relatedness to those in lymphoid tissue. HIV-1 genomes infecting different regions of the brain of one study subject with HIV encephalitis (HIVE) had a mosaic structure, being assembled from different combinations of evolutionarily distinct lineages in p17(gag), pol, individual hypervariable regions of gp120 (V1/V2, V3, V4, and V5), and gp41/nef. Similar discordant phylogenetic relationships were observed between p17(gag) and V3 sequences of brain and lymphoid tissue from three other individuals with HIVE. The observation that different parts of the genome of HIV infecting a particular tissue can have different evolutionary histories necessarily limits the conclusions that can be drawn from previous studies of the compartmentalization of distinct HIV populations in different tissues, as these have been generally restricted to sequence comparisons of single subgenomic regions. The complexity of viral populations in the brain produced by recombination could provide a powerful adaptive mechanism for the spread of virus with new phenotypes, such as antiviral resistance or escape from cytotoxic T-cell recognition into existing tissue-adapted virus populations.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Two years' prospective experience using fluorescence in situ hybridization on uncultured amniotic fluid cells for rapid prenatal diagnosis of common chromosomal aneuploidies.

A probe was generated from the YAC clone 831B9 that was suitable for the prenatal detection of trisomy 21 using fluorescence in situ hybridization (FISH). This probe was initially tested on a series of 650 unselected amniotic fluid samples prior to the karyotype being available. 630 were correctly identified as having two copies and 13 samples were correctly scored as having three copies of chromosome 21. Seven samples failed to produce a result. A trial was then initiated, reporting to clinicians the interphase FISH results before cytogenetic analysis had been performed. During the first 18 months of this trial 1504 samples were tested: 1467 were correctly identified as disomic and 35 samples were correctly scored as trisomic for chromosome 21. Two samples failed to produce a result. A chromosome 18 specific probe (LI.84) was employed where there was a relevant clinical indication (181 samples) and 10 samples were correctly scored as having three copies of chromosome 18. Thus, this approach appears to be reliable and is popular with both clinicians and patients due to the speed of the result. However, it does not replace chromosomal analysis on cultured cells, which detected a range of abnormalities besides the trisomies and triploidies detected by FISH.

Amniotic Fluid↗
PubMed1998

Fluorescence studies of human semi-beta-hemoglobin assembly.

The intrinsic fluorescence properties of human alpha apohemoglobin at protein concentrations from 1 to 5 microM in 0.1 M potassium phosphate buffer, pH 7 or 8 at 5 degrees C were monitored in the absence and presence of a fixed concentration (5 microM) of a fluorescence quenching heme-containing native or Des (146-His, 145-Tyr) beta chain partner. These "reverse quenching" studies revealed that the emission intensity changes observed correlated well with protein concentration and theoretical extent of semi-beta-hemoglobin assembly. Furthermore, the relative quenching efficiencies were calculated to be 0.32, 0.25 and 0.61 for beta (pH 7), beta (pH 8) and Des beta (pH 7) chains, respectively. Thus, heme-mediated quenching was sensitive to the expected pH induced alpha apohemoglobin conformational change and to alteration in beta chain structure. Intramolecular changes induced by carboxylterminal modification (decreased "beta chain self-quenching") appeared to enhance the intermolecular rearrangements (increased "alpha chain partner quenching") seen upon subunit assembly.

Apoproteins↗
PubMed1998

Accurate evaluation of palpable breast masses by the triple test score.

BACKGROUND: We previously reported that the triple test (physical examination, mammography, and fine needle aspiration) for palpable breast masses yields 100% diagnostic accuracy when all 3 components are concordant (all benign or all malignant). However, 40% of cases are nonconcordant and require open biopsy. OBJECTIVE: To evaluate our experience with the triple test to develop a method to further limit the need for surgical biopsy. DESIGN: Diagnostic test study. SETTING: University hospital multidisciplinary breast clinic. PATIENTS: Two hundred fifty-nine patients with 261 palpable breast masses studied between 1991 and 1997. INTERVENTION: The triple test was prospectively applied to each breast mass. Each component of the triple test was assigned 1, 2, or 3 points for a benign, suspicious, or malignant result, respectively, yielding a total triple test score (TTS). MAIN OUTCOME MEASURES: The TTS was correlated with subsequent histopathologic examination results. RESULTS: Eighty-eight masses had a TTS of more than 6 points; all had malignant histopathologic characteristics. One hundred fifty-two masses had a TTS of 4 points or lower; all were benign. In both groups, diagnostic accuracy and predictive value were 100%, with P<.001. Twenty-one masses had a TTS of 5 points; of these, 13 (62%) were benign and 8 (38%) were malignant. CONCLUSIONS: The TTS reliably guides evaluation and treatment of palpable breast masses. Masses that score 6 points or higher are malignant and should undergo definitive therapy; masses that score 4 points or lower are benign and may be clinically followed up. Only those masses that score 5 points (8% of our database) require open biopsy.

Biopsy, Needle↗
PubMed1998

The pyrophosphate-dependent phosphofructokinase of the protist, Trichomonas vaginalis, and the evolutionary relationships of protist phosphofructokinases.

The pyrophosphate-dependent phosphofructokinase (PPi-PFK) of the amitochondriate protist Trichomonas vaginalis has been purified. The enzyme is a homotetramer of about 50 kDa subunits and is not subject to allosteric regulation. The protein was fragmented and a number of peptides were sequenced. Based on this information a PCR product was obtained from T. vaginalis gDNA and used to isolate corresponding cDNA and gDNA clones. Southern analysis indicated the presence of five genes. One open reading frame (ORF) was completely sequenced and for two others the 5' half of the gene was determined. The sequences were highly similar. The complete ORF corresponded to a polypeptide of about 46 kDa. All the peptide sequences obtained were present in the derived sequences. The complete ORF was highly similar to that of other PFKs, primarily in its amino-terminal half. The T. vaginalis enzyme was most similar to PPi-PFK of the mitochondriate heterolobosean, Naegleria fowleri. Most of the residues shown or assumed to be involved in substrate binding in other PPi-PFKs were conserved in the T. vaginalis enzyme. Direct comparison and phylogenetic reconstruction revealed a significant divergence among PPi-PFKs and related enzymes, which can be assigned to at least four distantly related groups, three of which contain enzymes of protists. The separation of these groups is supported with a high percentage of bootstrap proportions. The short T. vaginalis PFK shares a most recent common ancestor with the enzyme from N. fowleri. This pair is clearly separated from a group comprising the long (>60-kDa) enzymes from Giardia lamblia, Entamoeba histolytica pfk2, the spirochaetes Borrelia burgdorferi and Trepomena pallidum, as well as the alpha- and beta-subunits of plant PPi-PFKs. The third group ("X") containing protist sequences includes the glycosomal ATP-PFK of Trypanosoma brucei, E. histolytica pfk1, and a second sequence from B. burgdorferi. The fourth group ("Y") comprises cyanobacterial and high-G + C, Gram-positive eubacterial sequences. The well-studied PPi-PFK of Propionibacterium freudenreichii is highly divergent and cannot be assigned to any of these groups. These four groups are well separated from typical ATP-PFKs, the phylogenetic analysis of which confirmed relationships established earlier. These findings indicate a complex history of a key step of glycolysis in protists with several early gene duplications and possible horizontal gene transfers.

Amino Acid Sequence↗
PubMed1998

Influence of GB virus C viraemia on the clinical, virological and histological features of early hepatitis C-related hepatic disease.

BACKGROUND/AIMS: GB virus C is a newly described RNA virus. The aims of this study were to determine the prevalence of GB virus C infection in patients with chronic type C hepatitis and to examine the clinical, virological and histological features in hepatitis C and GB virus C co-infected patients. METHODS/RESULTS: One hundred and sixty patients with hepatitis C infection were studied. GBV-C RNA was detected in 33/160 (20.6%) patients; co-infected patients with hepatitis C and GB virus C infection were significantly younger (p=0.04). No difference was found between the two groups according to gender and biochemical parameters. Seventy-two of the 160 patients, for whom a liver tissue specimen taken simultaneously with the serum was available and who had compensated liver disease, were studied separately. The source of infection, duration of infection, HCV genotype and HCV RNA concentrations did not differ between 15/72 patients with dual infection and 57/72 with hepatitis C infection alone. Patients with co-infection had significantly higher degrees of portal and periportal inflammation (p=0.0006 and 0.01, respectively). No difference was observed in parenchymal activity score or extent of fibrosis. CONCLUSIONS: These results indicate a relatively high prevalence of GB virus C infection in younger patients with chronic hepatitis C, suggesting a common route of transmission. Although GB virus C co-infection does not alter the biochemical and virological profile of patients with HCV hepatitis, there is an association between GB virus C and hepatitis C viraemia and portal and periportal inflammation.

Adult↗