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Biomedical subjects

R C Walker

Publications and source records attributed to R C Walker.

30 records · Page 2Linked to original sources
PubMed1987

Symposium on antimicrobial agents. The quinolones.

The fluoroquinolones are a new class of antimicrobial agents structurally related to nalidixic acid. They have a broad spectrum of activity against pathogens, including Pseudomonas aeruginosa, other multiresistant gram-negative bacteria, and methicillin-resistant Staphylococcus aureus but not anaerobes. They are well absorbed after oral administration, and some achieve serum and tissue levels well exceeding the minimal inhibitory concentrations for susceptible bacteria. Adverse reactions are rare, and when they occur they are usually mild. Use of quinolones should be avoided in children because of possible damage to developing cartilage. These agents should prove useful in the treatment of urinary tract infections caused by bacteria resistant to other oral agents, bacterial gastroenteritis, and gonococcal infections. The use of quinolones may potentially reduce the cost of treatment of certain systemic infections caused by multiantimicrobial resistant organisms because outpatient oral therapy is possible.

Adolescent↗
PubMed1987

The treatment of animal bite injuries of the eye and ocular adnexa.

Animal bites to the eye and ocular adnexa may result in significant morbidity. Management includes wound care and surgical repair of traumatized tissue, treatment of infection (most commonly Pasteurella multocida), appropriate tetanus and rabies prophylaxis, and notification of state public health officials.

Animals↗
PubMed1986

Changing epidemiology, diagnosis, and treatment of Clostridium difficile toxin-associated colitis.

One hundred and ninety patients with Clostridium difficile toxin-associated colitis (CTAC) or pseudomembranous colitis (PMC) were identified, from microbiology records, disease index and proctoscopy service records, and studied retrospectively. CTAC was associated with cephalosporin antibiotic administration in 70 per cent of the patients. CTAC developed postoperatively in 108 patients after all types of surgery with no preponderance for abdominal surgery. Identification of cytotoxin in stool samples was the primary diagnostic test in 81 per cent of patients but cytotoxin was isolated in 98 per cent of all patients. Pseudomembranes visible on proctoscopy established the diagnosis in 19 per cent of patients and were more commonly seen in severe colitis (71 per cent) than in mild colitis (23 per cent). CTAC responded similarly to oral vancomycin and metronidazole with a relapse rate of 20-23 per cent, respectively. With its association with cephalosporin administration, CTAC is likely to occur with increasing frequency in surgical practice. Oral metronidazole is an effective, cheap, alternative to vancomycin therapy.

Adolescent↗
PubMed1986

Comparison of culture, cytotoxicity assays, and enzyme-linked immunosorbent assay for toxin A and toxin B in the diagnosis of Clostridium difficile-related enteric disease.

Clostridium difficile culture, test tube, and microtiter cytotoxicity assays, and enzyme-linked immunosorbent assays (ELISAs) for toxin A and toxin B, were simultaneously performed on 113 fresh diarrheal stool specimens randomly selected from those submitted to our clinical laboratory for routine C. difficile testing. The performance of these tests in diagnosing C. difficile-related enteric disease (CDRED) was based on a clinical assessment of the likelihood of CDRED as determined by a systematic review of case histories blinded from the test results. Among 61 antibiotic recipients, both the microtiter cytotoxicity assay and the toxin A ELISA were highly specific for CDRED (95% and 100%, respectively). Specificities for the other procedures were much lower (tube cytotoxicity assay, 79%; culture, 74%; and toxin B ELISA, 56%). The high sensitivities of the culture (89%) and toxin B ELISA (83%) were somewhat negated by their low specificities. The only test that was both specific and had acceptable sensitivity (78%) was the microtiter cytotoxicity assay. This study indicates that ELISAs for detection of C. difficile toxins are not as reliable as the cytotoxicity assay in the laboratory diagnosis of CDRED, and that clinical correlation is essential in the evaluation of any new test for CDRED.

Adult↗
PubMed1986

Characterization of enkephalin degradation in rat plasma.

Approximately 80% of the hydrolysis of [leu]enkephalin in rat plasma can be attributed to bestatin-sensitive aminopeptidase activity, and an additional 5% is due to angiotensin converting enzyme. Thiorphan-sensitive enkephalinase hydrolysis of [leu]enkephalin could not be detected in plasma. On the other hand, 2-d-ala-l-[leu]enkephalin is metabolized approximately 35% by an unidentified bestatin-sensitive enzyme and approximately 15% by thiorphan-sensitive enkephalinase in rat plasma, while captopril-sensitive angiotensin converting enzyme is without measurable activity against this substrate.

Aminopeptidases↗
PubMed1986

Lysis-centrifugation blood culture technique. Clinical impact in Staphylococcus aureus bacteremia.

To determine the clinical impact of enhanced detection of Staphylococcus aureus by a lysis-centrifugation (LC) blood culture system, consecutive cases of S aureus bacteremia during a seven-month period were reviewed. Of 77 clinically significant cases, the LC system detected 70 cases (91%) while a conventional broth system detected 67 cases (87%). Of 60 cases detected by both systems, the LC system was positive earlier than the broth system by one or more days in 34 cases (57%) and later in none. It also detected more (12 vs four of 13) patients with persistent bacteremia who were receiving antimicrobial treatment. Forty-three patients (56%) did not receive appropriate antimicrobial therapy until cultures were reported positive. Enhanced detection of S aureus bacteremia is a clinically important advantage of the LC blood culture technique.

Bacteriological Techniques↗
PubMed1984

Uronide Deposition Rates in the Primary Root of Zea mays.

The spatial distribution of the rate of deposition of uronic acids in the elongation zone of Zea mays L. Crow WF9 x Mo 17 was determined using the continuity equation with experimentally determined values for uronide density and growth velocity. In spatial terms, the uronide deposition rate has a maximum of 0.4 micrograms per millimeter per hour at s = 3.5 mm (i.e., at the location 3.5 mm from the root tip) and decreases to 0.1 mg mm(-1) h(-1) by s = 10 mm. In terms of a material tissue element, a tissue segment located initially from s = 2.0 to s = 2.1 mm has 0.14 mug of uronic acids and increases in both length and uronic acid content until it is 0.9 mm long and has 0.7 mug of uronide when its center is at s = 10 mm. Simulations of radioactive labeling experiments show that 15 min is the appropriate time scale for pulse determinations of deposition rate profiles in a rapidly growing corn root.

Journal Article↗
PubMedDate not supplied

Pretransplantation seronegative Epstein-Barr virus status is the primary risk factor for posttransplantation lymphoproliferative disorder in adult heart, lung, and other solid organ transplantations.

BACKGROUND: The relative importance and interrelationship of risk factors for posttransplantation lymphoproliferative disorder are poorly understood. METHODS: The prospective pretransplantation serologic testing for Epstein-Barr virus of all nonrenal solid organ transplant recipients at our institution made it possible to assess the relative risk for posttransplantation lymphoproliferative disorder in seropositive and seronegative recipients. RESULTS: Fourteen cases of lymphoproliferative disorder were identified in the first 389 consecutive transplant recipients (288 liver, 44 heart, 20 lung, 37 kidney-pancreas) undergoing transplantation from 1985 to 1992 (mean follow-up 33 months). The incidence rates of lymphoproliferative disorder (per 100 person-years) during the first 2 years after transplantation (a period in which all cases occurred) were 1.4 for liver, 2.0 for heart, 6.2 for lung, and 5.2 for kidney-pancreas transplant recipients and were significantly different between liver and lung (p = 0.005) and liver and kidney-pancreas (p = 0.002) groups. Of 367 seropositive patients, lymphoproliferative disorder developed in only three. The incidence rate ratios between seronegative and seropositive recipients were as follows: 76 ([95% confidence interval; 46, 144], p = 0.0000) for any form of lymphoproliferative disorder and 145 ([60, 347], p = 0.0000) for fatal or brain forms. The incidence rate of lymphoproliferative disorder was significantly higher for seronegative recipients who required antilymphocyte antibody therapy for rejection than for those who received none. CONCLUSIONS: The high intrinsic risk for lymphoproliferative disorder in the Epstein-Barr virus seronegative patient, which is amplified by higher levels of immunosuppression, may, in some instances, preclude transplantation.

Acyclovir↗