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S Reed

Publications and source records attributed to S Reed.

At least 19 recordsLinked to original sources
PubMed1992

Mechanism of resistance to complement-mediated killing of bacteria encoded by the Salmonella typhimurium virulence plasmid gene rck.

We find that pADEO16, a recombinant cosmid carrying the rck gene of the Salmonella typhimurium virulence plasmid, when cloned into either rough or smooth Escherichia coli and Salmonella strains, confers high level resistance to the bactericidal activity of pooled normal human serum. The rck gene encodes a 17-kD outer membrane protein that is homologous to a family of virulence-associated outer membrane proteins, including pagC and Ail. Complement depletion, C3 and C5 binding, and membrane-bound C3 cleavage products are similar in strains with and without rck. Although a large difference in C9 binding was not seen, trypsin cleaved 55.7% of bound 125I-C9 counts from rough S. typhimurium with pADEO16, whereas only 26.4% were released from S. typhimurium with K2011, containing a mutation in rck. The majority of C9 extracted from rck strain membranes sediments at a lower molecular weight than in strains without rck, suggesting less C9 polymerization. Furthermore, SDS-PAGE analysis of gradient peak fractions indicated that the slower sedimenting C9-containing complexes in rck strains did not contain polymerized C9 typical of the tubular membrane attack complex. These results indicate that complement resistance mediated by Rck is associated with a failure to form fully polymerized tubular membrane attack complexes.

Antibodies, Monoclonal↗
PubMed1992

A unique cysteine proteinase gene of pathogenic Entamoeba histolytica correlates with virulence.

Extracellular neutral cysteine proteinases are an important virulence factor of E. histolytica. Experimental evidence supporting its role in invasion includes the ability to degrade components of the extracellular matrix and activate complement by specifically cleaving C3. We had previously reported the isolation of fragments encoding cysteine proteinase genes from HM-1 (ACP1) and a nonpathogenic strain (REF291, ACP2) by PCR using consensus sequences based on conserved structural motifs of eukaryotic cysteine proteinases. Using similar techniques, we have now identified a third gene encoding a cysteine proteinase which is present in both pathogenic and nonpathogenic strains and have correlated cysteine proteinase specific-mRNA levels with enhanced proteolytic activity and cytopathic effect on a fibroblast cell monolayer, a quantitative assay of virulence.

Animals↗
PubMed1992

Use of polymerase chain reaction and nonradioactive DNA probes to diagnose Entamoeba histolytica in clinical samples.

E. histolytica parasites in Mexican children's stools were identified and typed as pathogenic or non-pathogenic using the polymerase chain reaction (PCR) and nonradioactive probes. PCRs were performed with primers specific for 145 base pair (bp) pathogenic or 133 bp non-pathogenic DNA sequences, which are highly repeated in E. histolytica parasites with pathogenic or non-pathogenic isoenzyme patterns, respectively. Dot-blotted PCR products were identified with a horseradish peroxidase-conjugated oligonucleotide probe specific for either the 145 bp pathogenic or 133 bp non-pathogenic sequences. The PCR and the 145 bp pathogenic probe correctly identified eight cultures with pathogenic isoenzyme types and none of nine cultures with non-pathogenic isoenzyme. The PCR and 133 bp non-pathogenic probe identified all of the non-pathogenic cultures, none of the axenized pathogenic cultures, and three of five xenic cultures with pathogenic isoenzymes. The two probes together identified all 49 stools containing E. histolytica by light microscopy (sensitivity = 1.0), which represented the entire set of the E. histolytica-positive stools diagnosed at the Hospital Infantil over a 10 week period. Most patient isolates were positive with both 145 bp pathogenic and 133 bp non-pathogenic probes, suggesting that these children, 60% of whom were dysenteric, are infected with mixed populations of amebas.

Animals↗
PubMed1991

Plateletpheresis with the COBE spectra single needle access option.

A group of modifications, including a reservoir bag in the return circuit, has been devised to allow single needle plateletpheresis with the COBE Spectra. We compared the number and quality of platelets collected from 10 subjects in paired donations with single and dual needle protocols. There was no evidence of hemolysis with either protocol. Mean (+/- SD) platelet yields were 3.61 +/- 1.47 x 10(11) with two needles and 3.31 +/- 1.31 x 10(11) with the single needle procedure (P = .13). Mean leukocyte levels (standard manual counting chamber) were 1.0 +/- 1.7 x 10(7) and 1.2 +/- 1.0 x 10(7), respectively (p = .78). pH values during storage were acceptable in both groups of concentrates, and there were no significant differences between the single needle and dual needle concentrates in morphology scores or beta-thromboglobulin levels at 0, 1, 3, or 5 days of storage. Thus the single needle modification produced platelets that were comparable in quantity and quality to those from the standard dual needle plateletpheresis protocol.

Blood Donors↗
PubMed1991

Detection of HIV-1 in Entamoeba histolytica without evidence of transmission to human cells.

Intestinal protozoa like Entamoeba histolytica and Giardia lamblia have been proposed as vectors or cofactors in the development of AIDS. To determine whether these protozoa could transmit HIV, laboratory strains of protozoa were cocultured with cells chronically infected by a highly replicative strain of HIV-1. Entamoeba histolytica, but not Giardia lamblia, took up virus. Immunologically detectable HIV-1 was present in the amebae up to 48 h after exposure to infected cells, but this virus could not be transferred to uninfected human cells. Amebae isolated directly from two HIV-infected individuals were also found to be positive for HIV-1. After lysis of these protozoa and coculture with uninfected peripheral blood mononuclear cells, no transfer of virus to the human cells was observed.

Animals↗
PubMed1991

Argon laser versus thermal cautery for punctal occlusion. An animal study.

A subset of the dry-eye patient group manifests their problem so severely that permanent punctal occlusion is required. The technique most often used today is thermal cautery. In this prospective study, an animal model was developed, and the effectiveness of the argon laser as a primary alternative therapy to thermal cautery was evaluated. Dogs were found to have a punctum similar in shape and location to humans; therefore, they were deemed to be a more appropriate animal model for punctal studies than cats. Both laser and thermal cautery are similarly effective in completely occluding puncta in animals. There was a trend toward greater stenosis with the laser in those puncta that were only partially occluded. In addition, laser punctal occlusion appeared to be less painful than thermal cautery.

Animals↗
PubMed1991

Isolation of a strain-specific Entamoeba histolytica cDNA clone.

Entamoeba histolytica is an intestinal parasite causing significant morbidity and mortality worldwide. More tools are needed to understand the epidemiology and molecular pathogenesis of amebiasis. A cDNA library was constructed by using poly(A)+ RNA isolated from an axenic strain of E. histolytica, HM1:IMSS, which expresses a pathogenic isoenzyme pattern (zymodeme). Differential screening of the library yielded a strain-specific 3' polyadenylated cDNA clone, C2, possessing nine 26-nucleotide tandem repeats. RNA and DNA transfer blot analysis of four axenic strains of E. histolytica possessing the same pathogenic zymodeme revealed that the gene is present and expressed in pathogenic E. histolytica HM1:IMSS and 200:NIH but is not present in pathogenic strains HK-9 and Rahman. In addition, Southern blot analysis using the C2 clone showed heterogeneity of genomic organization between HM1:IMSS and 200:NIH. DNA dot blot hybridization analysis demonstrated that cDNA clone C2 was also able to distinguish axenically cultured E. histolytica strains possessing pathogenic zymodemes from those possessing nonpathogenic zymodemes and could detect as few as 100 amebic trophozoites. We conclude that C2 is a strain-specific E. histolytica cDNA clone that, in conjunction with other E. histolytica-specific probes, could serve as a useful epidemiologic tool.

Animals↗
PubMed1990

Computerization of plateletpheresis quality control records with a commercially available spreadsheet program.

Many apheresis units lack the resources to acquire customized computer software for record keeping. We have adapted a commercially available "spreadsheet" program (Lotus 1-2-3) to aid in quality control activities for plateletpheresis. Data are entered in a grid pattern wherein each donation occupies one row and successive columns contain numerical data derived from the donation. The last two columns contain formulas that calculate yield and collection efficiency from values entered in preceding columns. The program runs on an IBM PC or equivalent with 512 K RAM; the combined cost of a computer and software is currently under $2,000.00. Data entry requires fewer keystrokes per record than computation of yield and efficiency with a calculator, and creates an inclusive permanent record for future analysis. Data sorting and statistical functions allow rapid identification of incomplete records, and derivation of average platelet yield and/or collection efficiency for any time period of interest. The program also facilitates determining the proportion of donations that fall below any chosen cutoff. Performance characteristics of a particular instrument or operator can be assessed easily by isolating the pertinent records and analyzing them separately. The system will thus accomplish a variety of quality control activities, including those mandated by licensing agencies. It can be implemented by apheresis personnel with limited "computer literacy" and is superior to manual tabulation of quality control data in both ease of data entry and facility of analysis.

Data Interpretation, Statistical↗
PubMed1990

Adapting problem-based learning to a traditional curriculum: teaching about prevention.

How best to teach medical students is an issue of importance in medical education. At Dartmouth Medical School, a required first-year course emphasizes small-group learning through five modules that are both problem-based and task-oriented. The prevention module that requires small groups to plan the solution to a problem in prevention is described. Evaluation reveals that the program is feasible for teaching about prevention, and that the following principles are important to consider when implementing problem-based, task-oriented learning in an otherwise traditional curriculum: (1) Be clear in explaining the unique expectations and requirements of small-group learning to students. (2) Limit the duration of any special learning module to less than a week. (3) Take into account the demands of the traditional curriculum when scheduling to minimize competition with traditional examinations.

Curriculum↗
PubMed1989

DNA hybridization probe for clinical diagnosis of Entamoeba histolytica.

As an alternative to microscopic identification of Entamoeba histolytica parasites isolated from stool, a sensitive and species-specific DNA hybridization probe was made for rapid diagnosis of E. histolytica parasites in clinical samples directly applied to nylon membranes. The DNA hybridization probe was made by screening a genomic library of a virulent HM-1:IMSS strain of E. histolytica to detect recombinant plasmids containing highly repeated parasite DNA sequences. Four plasmid clones that reacted across Entamoeba species coded for highly repeated rRNA genes of E. histolytica. Four other plasmid clones were E. histolytica specific in that they bound to four axenized and nine xenic strains of E. histolytica but did not recognize closely related E. histolytica-like Laredo, Entamoeba moshkovskii, or Entamoeba invadens parasites. The diagnostic clones detected as few as eight cultured amoebae and did not distinguish between pathogenic and nonpathogenic zymodemes of E. histolytica. The diagnostic clones were sequenced and contained 145-base-pair sequences which appear to be tandemly repeated in the genome. No stable transcript which is homologous to the diagnostic DNA was detected. In a study of stool samples from Mexico City shown by microscopy to contain E. histolytica, Entamoeba coli, Giardia lamblia, Endolimax nana, Trichuris trichiuria, and Chilomastix mesnili parasites, the DNA hybridization probe demonstrated a sensitivity of 1.0 and a specificity of 0.93. We conclude that the DNA hybridization probe can be used for rapid and accurate diagnosis of E. histolytica parasites.

Animals↗
PubMed1989

Restoration of wrist extension after paralysis.

Loss of active extension of the wrist is a major functional handicap for the affected patient. Restoration of wrist extension, primarily accomplished via tendon transfers, is a fundamental part of surgical treatment after paralysis. The anatomy and physiology of the wrist, the clinical aspects, the history, and restorative treatment of wrist extension after paralysis are discussed.

Humans↗
PubMed1988

Aberrant protamine 1/protamine 2 ratios in sperm of infertile human males.

Protamines were extracted from the sperm of fertile and infertile human males and the relative proportion of protamines 1, 2, and 3 were determined by scanning microdensitometry following electrophoresis of total protamine in polyacrylamide gels. The proportion of the three protamines was found to be similar in sperm obtained from different normal males. The distribution of protamines in sperm obtained from a select group of infertile males producing an elevated level of large sperm heads, in contrast, was different from that of the fertile males.

Densitometry↗
PubMed1988

Visceral leishmaniasis: a disease associated with inability of lymphocytes to activate macrophages to kill leishmania.

1. The production of lymphokines capable of activating macrophages to kill leishmania was evaluated in seven visceral leishmaniasis patients. 2. Macrophages from healthy donors cultivated in vitro with supernatants from lymphocyte cultures of visceral leishmaniasis patients were infected with L. d. chagasi or L. m. amazonensis. After infection the number of amastigotes per 100 cells was counted. 3. The supernatant from visceral leishmaniasis lymphocytes did not significantly reduce the number of intracellular amastigotes of L. donovani chagasi (89 +/- 27%) in relation to controls (culture containing medium alone). In contrast, supernatants of mucocutaneous lymphocyte cultures decreased the percentage of infection to 26 +/- 11%. The supernatant of antigen-stimulated lymphocyte cultures from visceral leishmaniasis patients also did not inhibit L. mexicana amazonensis growth. The supernatant of visceral leishmaniasis lymphocytes stimulated with PHA reduced the number of intracellular amastigotes to 62 +/- 23% in relation to controls. 4. The inability of lymphocytes from visceral leishmaniasis patients to proliferate when stimulated with leishmania antigens and to activate macrophages to kill leishmania may represent a fundamental defect and lead to the acquisition of the disease.

Adolescent↗
PubMed1986

A case of fatal sodium azide ingestion.

A fatal case of sodium azide poisoning in which exchange blood transfusions, charcoal hemoperfusion, hemodialysis and potent vasopressor agents failed to prevent the development of circulatory collapse associated with a wide complex cardiac rhythm is presented. The cellular toxin sodium azide resulted in the development of an altered mental status, profound metabolic acidosis, cardiac arrhythmia (atrial fibrillation and terminal wide complex arrhythmias), a relative decrease in cardiac output, hypotension and non-cardiogenic pulmonary edema. Further animal studies are needed to gain new approaches for the treatment of this rare cause of human poisoning.

Acidosis↗
PubMed1985

Assessment and management of asthma in an accident and emergency department.

Patients with asthma presenting to the accident and emergency department at Southampton General Hospital during 12 months were reviewed retrospectively to determine how many patients attended, when and how patients were assessed and treated, and what factors appeared to influence whether a patient was admitted to a medical ward or not. Thirty five visits were made by patients requesting a repeat prescription for a metered dose inhaler. A further 193 visits were made by 152 patients (93 male, 59 female); only data on the first visit of any individual were analysed in this study. Patients were more likely to visit in the autumn, at the weekend, and in the evenings. Observations and measurements used to assess the severity of asthma were recorded with variable frequency--heart rate in 84% of examinations, pulsus paradoxus in 13%, and peak flow rate in 11%. Blood pressure was five times more likely to be recorded than peak flow rate. The drugs used to treat asthma were, in order of frequency, a beta agonist (120 patients), intravenous aminophylline (39), and intravenous corticosteroids (30). Sixty (39%) of the patients were admitted to a medical ward. Admission was more likely to occur when patients arrived during the week than at the weekend, when they had cyanosis or pulsus paradoxus, and after receiving parenteral treatment. There was no difference in mean heart rate between patients admitted to the ward and those discharged home. Although there was no specific evidence of inappropriate admission to or discharge from hospital in this retrospective study, the failure to record more objective measurements of the severity of asthma and, in particular, the extent of the airflow obstruction, is cause for concern.

Adolescent↗