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Biomedical subjects

J R Warren

Publications and source records attributed to J R Warren.

At least 19 recordsLinked to original sources
PubMed1998

Cross-contamination of specimens with Mycobacterium tuberculosis: clinical significance, causes, and prevention.

At the Veterans Affairs Lakeside Medical Center, two episodes of specimen cross-contamination with Mycobacterium tuberculosis were detected during a 54-month period by molecular strain typing using DNA restriction fragment length polymorphism for 3 patients without clinical or radiologic signs of tuberculosis (TB). A cross-contaminated specimen was the only culture-positive specimen for each of the 3 patients. Laboratory features of cross-contamination included acid-fast smear negativity, growth only in broth or solid medium, and growth in solid medium with 5 or fewer colonies. Retrospective analysis demonstrated identical features for occasional culture-positive specimens from 54 patients with TB during the same period. However, productive cough, pleural pain, weight loss, night sweats, chest radiograph results suggestive of TB, positive tuberculin skin testing, and/or multiple culture-positive specimens were invariably present in patients with TB with such specimens. Most patients with TB (50/54; 93%) had multiple specimens positive in culture for M. tuberculosis, and the few patients with TB with single culture-positive specimens were symptomatic. These results indicate that correlation with clinical manifestations is necessary to determine the significance of isolated, acid-fast smear negative, and/or low-yield culture-positive specimens. Although the prevalence of specimen cross-contamination is low (0.1%), possible sources (especially the use of single-reagent delivery systems for multiple specimens) should be eliminated by mycobacteriology laboratories.

Adult↗
PubMed1998

Detecting disseminated Mycobacterium avium complex infections in HIV-positive patients. The usefulness of bone marrow trephine biopsy specimens, aspirate cultures, and blood cultures.

Disseminated Mycobacterium avium complex (MAC) infections are common in patients with acquired immunodeficiency syndrome (AIDS). These patients frequently seek care with fever accompanied by generalized systemic symptoms and undergo bone marrow biopsy. It is our practice to stain all bone marrow trephine biopsy specimens from patients infected with HIV for acid-fast bacilli (AFB). We evaluated this practice by comparing the sensitivity and turnaround time for detection of MAC by biopsy specimen staining, bone marrow aspirate culture, and blood culture. Bone marrow trephine biopsy specimens with corresponding bone marrow aspirate and blood cultures from 86 HIV-positive patients were reviewed. Of the 86 patients, 30 had positive results for disseminated MAC infection, and all 30 of those patients had positive blood cultures. Bone marrow aspirate cultures identified 17 MAC-positive cases, and AFB staining of the biopsy specimen identified 9. The mean times to detection of MAC positivity were 1.1 days for AFB staining of the biopsy specimen, 19 days for bone marrow aspirate culture, and 16 days for blood culture. While AFB staining of biopsy specimens was the least sensitive of the detection methods, it was useful for the rapid diagnosis of disseminated MAC infection, allowing for prompt initiation of antimycobacterial therapy in one third of patients.

Biopsy↗
PubMed1998

Induction of a variety of preneoplasias and tumours in the mammary glands of transgenic rats.

Although transgenic mouse models for breast cancer have frequently been reported in the literature, transgenic rat models have not been described. We have generated transgenic rats overexpressing the human transforming growth factor alpha (TGF alpha) and c-erbB-2 genes in the mammary gland under the control of the mouse mammary tumour virus (MMTV) long terminal repeat promoter, and have analysed multiple lines of these rats to the second (F2) generation. Female MMTV/TGF alpha rats frequently develop severe hyperplasias during pregnancy, and a variety of tumours of long latency. The mammary glands of MMTV/TGF alpha rats fail to involute fully after the completion of lactation. Expression of the TGF alpha transgene is highest in the hyperplasias. MMTV/c-erbB-2 female rats develop a spectrum of benign and malignant lesions, including ductal carcinoma in situ and carcinomas. Expression of the c-erbB-2 transgene is found in benign tumours such as fibroadenomas, but is highest in the carcinomas. These animals model a spectrum of lesions found in human breasts and suggest that TGF alpha overexpression can act at a relatively early stage in the pathogenesis of breast cancer in the rat, resulting in a predominantly hyperplastic response, whereas overexpression of c-erbB-2 plays a role in the induction of various benign lesions and more advanced breast carcinomas.

Animals↗
PubMed1997

Cerebrospinal fluid broth culture isolates: their significance for antibiotic treatment.

Enriched broth medium is routinely used as a supplement for agar plate culture of cerebrospinal fluid (CSF). To assess the clinical utility of broth cultures, 151 consecutive CSF bacterial and fungal isolates obtained from 91 patients were retrospectively reviewed for the effect of results on treatment. Treatment decisions associated with individual CSF specimens for which isolates were recovered from thioglycollate broth only were compared with the treatment decisions associated with CSF specimens for which isolates were recovered by agar plate culture. Treatment was defined as initiation of or change in antimicrobial therapy based on the reporting of CSF culture isolates. Thirty-six (24%) of the 151 isolates were recovered in broth only. Three (8%) of these 36 isolates (from 34 patients) resulted in treatment with antimicrobial agents; however, 2 of the 3 treated isolates (Candida tropicalis, Proteus mirabilis) were recovered from a second CSF specimen in agar plate culture within 24 hours. Thus, only a single isolate (3%; Staphylococcus epidermidis) was treated based solely on a positive broth culture result. In contrast, 60 (52%) of the 115 isolates recovered in agar plate culture from 23 (40%) of 57 patients were treated (staphylococci, 28; gram-negative bacilli, 14; Cryptococcus neoformans, 10; Streptococcus pneumoniae, 3; Streptococcus sanguis, 1; other, 4). We conclude that treatment with antimicrobial agents based on isolates recovered from CSF specimens in broth culture alone is infrequent and infer from the data that the use of CSF broth cultures contributes little to treatment decisions.

Adolescent↗
PubMed1997

Plasmacytoma of the sigmoid colon associated with a diverticular stricture: case report and review of the literature.

Plasmacytoma is a malignant tumour composed of plasma cells. Most commonly this takes the form of a plasma cell infiltration of bone marrow-multiple myeloma. This may be seen radiologically as either discrete lytic lesions or diffuse osteoporosis. Plasma cells are seen on bone marrow biopsy, and monoclonal immunoglobulins may occur in plasma and/or urine. Less frequently, plasma cell tumours may present as a solitary myeloma of bone, which often progresses to multiple myeloma, or as a plasma cell leukemia. Primary plasma cell tumours in an extramedullary site are relatively rare. Such soft tissue plasmacytomas usually occur in the nasopharynx or conjectiva, and are seldom located in the lower gastrointestinal tract. We report a case of primary plasmacytoma associated with a diverticular stricture in the sigmoid colon, an occurrence not previously documented, and review the current literature.

Bone Marrow↗
PubMed1996

Long-term follow-up of gastric histology after Helicobacter pylori eradication.

Helicobacter pylori causes chronic active gastritis and is thought to be associated with the development of gastric atrophy, intestinal metaplasia and carcinoma. As the effect of H. pylori eradication on this process is poorly understood, we sought to determine the long-term effects of H. pylori eradication on gastric histology. Fifty-four patients with duodenal ulceration associated with H. pylori infection received H. pylori eradication therapy in 1985/86 and either remained infected (n = 22) or had the infection eradicated (n = 32); patients were followed up by endoscopy with gastric antral biopsy for 7.1 years (mean). Histopathological analysis of gastric antral mucosa from patients rendered H. pylori-negative revealed a marked decrease in both inflammatory cells within the lamina propria and intraepithelial neutrophils and an increase in epithelial mucinogenesis. Gland atrophy remained unchanged in both H. pylori-positive and -negative patients. When examined for the presence and severity of intestinal metaplasia, there was neither a difference between the two patient groups nor a change with time. These data demonstrate that significant long-term improvements in gastric histology accompany H. pylori eradication when compared with histology in patients with persistent infection. Whether this confers a protective effect by reducing the risk of gastric carcinoma remains unknown.

Adult↗
PubMed1995

In vitro activity of RP 59500 (quinupristin/dalfopristin) and ramoplanin against vancomycin-resistant Enterococcus faecium.

Vancomycin-resistant Enterococcus faecium (VREF) collected between July 1991 and February 1994 were tested in vitro against RP 59500 and ramoplanin using agar dilution and standard macro broth dilution procedures. Colony counts were determined at 0, 4, and 24 h. RP 59500 had an MIC range of < or = 0.5-8 micrograms/ml with an MIC90 of 2 micrograms/ml and a MBC range of < or = 0.5-16 micrograms/ml with an MBC90 of 16 micrograms/ml. Ramoplanin had an MIC range of < or = 0.125-1 microgram/ml with an MBC range of < or = 0.125-4 micrograms/ml. The MIC90 for ramoplanin was 1 microgram/ml and the MBC90 was 4 micrograms/ml for the tested isolates. Against these isolates of E. faecium, RP 59500 was bactericidal at 8x MIC, a potentially achievable level using a high drug dosage. Ramoplanin was bactericidal at 2x MIC.

Anti-Bacterial Agents↗
PubMed1995

Enterococcus faecium and Enterococcus faecalis bacteremia: acquisition and outcome.

The incidence of enterococcal bacteremia due to Enterococcus faecium is increasing. To understand the clinical significance of E. faecium bacteremia, we compared 16 patients who were bacteremic due to E. faecium to 56 patients who were bacteremic due to Enterococcus faecalis. E. faecium bacteremia developed most frequently in severely ill patients with fever or hypothermia accompanied by CNS, cardiovascular, and/or pulmonary dysfunction, while E. faecalis bacteremia occurred most often in less seriously ill patients. Nosocomial acquisition, cancer, neutropenia, renal insufficiency, current corticosteroid therapy, and previous treatment with broad-spectrum antibiotics were significantly more frequently associated with E. faecium bacteremia. Mortality was significantly higher among patients infected with E. faecium than among those infected with E. faecalis (50% vs. 11%; P = .001); this was true particularly among patients with monomicrobial or nosocomial bacteremia, those who had previously received antibiotic treatment, and those with cancer. Death due to enterococcal bacteremia was observed only among severely ill patients. These findings suggest that E. faecium often infects debilitated patients and that such infection appears to be a significant factor contributing to mortality.

Bacteremia↗
PubMed1994

Duodenal ulcer treated with Helicobacter pylori eradication: seven-year follow-up.

The long-term benefits of Helicobacter pylori-eradication treatment (HET) in H pylori-associated duodenal ulcer are unclear. We followed up patients with duodenal ulcers from a trial of H pylori eradication in 1985-86. 63 of 78 patients (81%) were reviewed clinically and had upper gastrointestinal endoscopy with gastric antral biopsy. Of 35 patients previously rendered H pylori negative, 32 (92%) remained H pylori negative after 7.1 years (mean). All patients initially H pylori positive remained infected, unless HET was given in the interim. Duodenal ulceration was found in 20% (5 out of 25) of patients remaining H pylori-positive, compared with 3% (1 of 38) of H pylori-negative patients (p < 0.05). The reduction of duodenal ulcer relapse obtained from H pylori eradication in H pylori-associated duodenal ulcer extends to at least 7 years after treatment, and is likely to be due to freedom from H pylori infection. However, duodenal ulcer may recur in patients rendered H pylori negative, due to factors other than reinfection with H pylori.

Adult↗
PubMed1993

Bactericidal activity of the fluoroquinolone WIN 57273 against high-level gentamicin-resistant Enterococcus faecalis.

The fluoroquinolone WIN 57273 showed identical bactericidal activities (MBC for 90% of the strains = 0.25 micrograms/ml) for bacteremic strains of Enterococcus faecalis with and without high-level gentamicin resistance. WIN 57273 was bactericidal in time-kill measurements with highly gentamicin-resistant, ciprofloxacin-susceptible strains of E. faecalis. However, WIN 57273 was indifferent with penicillin for gentamicin-resistant E. faecalis and was not bactericidal for ciprofloxacin-resistant E. faecalis.

Anti-Infective Agents↗
PubMed1993

When is Helicobacter pylori infection acquired?

Cross sectional surveys have shown an increasing prevalence of Helicobacter pylori (H pylori) infection with increasing age in Western populations. The aim of this study was to examine the pattern of acquisition of H pylori infection over a 21 year period in a group of 141 adults who had blood samples and serum stored in 1969, 1978, and 1990. A prevalence of H pylori antibody of 39% in 1969 serum samples, 40.9% in 1978, and 34.8% in 1990 was found when assessed by an enzyme linked immunosorbent assay (ELISA). Of the 86 subjects who were seronegative in 1969, only six (7%) were seropositive in 1990. These data suggest that a cohort effect may contribute to the pattern of increasing prevalence of H pylori infection seen with increasing age. Acquisition of infection in adults is rare. It is unlikely, therefore, that reinfection will occur after successful eradication.

Adult↗
PubMed1992

Inhibition of preimplantation mouse embryo development by isoflurane.

OBJECTIVE: Preimplantation mouse embryos were exposed to a commonly used inhalational anesthetic agent, isoflurane, to determine its effects on embryo development. STUDY DESIGN: Two-cell embryos were exposed at various intervals (5 to 6 hours, 3 to 4 hours, and 0 to 1 hour) before the onset of their first cleavage in vitro. In addition, the effects of 5% isoflurane on four-cell embryos exposed about 2 hours after the first cleavage and morula stage embryos also were examined. RESULTS: Development to the blastocyst stage was inhibited by 3% and 5% isoflurane (p less than 0.005) but not by 1.5% isoflurane when two-cell embryos were exposed 3 to 4 hours or 0 to 1 hour before the onset of cleavage. Most of the affected embryos completed cell division and came to a halt at the three- to four-cell stage. The development of embryos exposed to isoflurane at the four-cell or morula stage was unaffected. CONCLUSIONS: Isoflurane adversely affects subsequent preimplantation development when two-cell mouse embryos are exposed just before the onset of their first cleavage in vitro.

Animals↗
PubMed1991

High-level gentamicin resistance in Enterococcus faecalis bacteremia.

In a retrospective analysis, patients with bacteremia due to Enterococcus faecalis with and without high-level gentamicin resistance (GRE; MIC greater than 2000 micrograms/ml) were compared. Bacteremic patients with GRE (n = 32) had significantly higher rates of nosocomial acquisition and bladder catheterization, longer hospitalizations, and more frequent prior treatment with cephalosporins than did bacteremic patients without high-level resistance (n = 19). Overall mortality was significantly associated with septic shock, high-risk source (intraabdominal, wound, respiratory tract, multiple, unknown), and polymicrobial bacteremia. Higher mortality was observed in GRE bacteremia (47%) than in bacteremia without high-level resistance (37%), but this difference was not statistically significant. For patients with monomicrobial bacteremia, low-risk source (genitourinary tract, intravascular), or treatment with antibiotics appropriate for the enterococcus, higher mortality with GRE bacteremia approached statistical significance. These results suggest that high-level resistance adversely affects survival with a pure E. faecalis bacteremia or low-risk bacteremic source. Also, response to antibiotic therapy may be diminished by high-level resistance.

Adult↗
PubMed1990

Effects of nitrous oxide on preimplantation mouse embryo cleavage and development.

Preimplantation mouse embryos were exposed to nitrous oxide for 30 min to determine its effects on subsequent development after short durations of exposure. Two-cell mouse embryos were exposed to 60% nitrous oxide/40% oxygen at 6-7 h, 3-4 h, or 0-1 h prior to the expected onset of their first cleavage in vitro, or at the 4-cell or morula stages. Effects of nitrous oxide were not observed except in 2-cell embryos treated within 4 h of the expected in vitro cleavage. At 3-4 h and 0-1 h prior to the onset of cleavage, exposure to 60% nitrous oxide/40% oxygen resulted in blastocyst development rates of 27.7% and 4.7%, respectively, while control rates ranged from 75% to 77%. The majority of affected embryos were halted at the 2-cell stage before completing cell division. Similar effects were obtained with 80% nitrous oxide/20% oxygen. Thus, we conclude that brief exposure of mouse preimplantation embryos to nitrous oxide may be deleterious to subsequent embryo cleavage, but this effect is highly dependent on the developmental stage at which exposure occurs.

Animals↗
PubMed1989

The 14C-urea breath-test for the detection of gastric Campylobacter pylori infection.

A breath-test has been developed for the detection of gastric infection with Campylobacter pylori. Urea that is labelled with carbon 14 is administered to a fasting patient and the patient's breath is sampled for radioactivity over the following 30 minutes. If C. pylori is present in the patient's stomach, urease activity causes hydrolysis of the urea and the 14C is absorbed as carbon dioxide. This carbon dioxide enters the patient's bicarbonate pool and eventually is excreted in the breath. The results are expressed as a percentage of the administered dose/mmol carbon dioxide x kg body weight. Sixty-three patients who were undergoing endoscopy were studied. The radioactivity in exhaled breath which was sampled within five minutes of 14C-urea administration was attributed to the presence of urease enzyme in mouth organisms and was discounted. The time-radioactivity curves for breath samples from five to 30 minutes after the administration of 14C-urea gave an excellent separation between subjects with negative results of the examination of gastric-biopsy samples and patients with microbiological and histological evidence of infection with C. pylori. The area under the time-radioactivity curve at between five and 30 minutes after the administration of 14C-urea in 24 patients with negative microbiological results was 6.9 +/- 4.4 area units; in 35 of 39 patients with positive microbiological results, this area was greater than 40 area units. Measured against the results of the microbiological examination of gastric-biopsy samples, the sensitivity of breath-testing was 90% and the specificity was 100%. Measured against the results of histological examination for the presence of C. pylori infection, breath-testing had a sensitivity of 94% and a specificity of 93%. A positive breath-test result also correlated well (P = 0.0001) with the serological antibody test-result. The role of non-invasive tests--enzyme-linked immunosorbent assays and 14C-urea breath-testing--in the management of gastritis and peptic ulcer disease is discussed. We consider that the 14C-urea breath-test has an important role in the noninvasive confirmation of gastric infection with C. pylori and in the follow-up of patients after treatment.

Adult↗