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Biomedical subjects

B M Gray

Publications and source records attributed to B M Gray.

At least 19 recordsLinked to original sources
PubMed2002

Egg-based media for delayed processing of nasopharyngeal swabs in colonization studies of Streptococcus pneumoniae.

This report describes the development and evaluation of a selective egg-based medium for ambient-temperature storage and transport of nasopharyngeal (NP) swabs in colonization studies of Streptococcus pneumoniae. Egg-thioglycolate-antibiotic (ETA) medium is based on Dorset's egg medium but made with thioglycolate broth and the addition of gentamicin (3 mg/l), nalidixic acid (15 mg/l), and amphotericin B (2.5 mg/l). Laboratory studies were conducted using mock swabs from 34 NP samples with known colony counts of pneumococci, which had previously been frozen in STGG (skim milk, tryptone, glucose, glycerol) broth. ETA facilitated better recovery of pneumococci than did either Stuart's or Amies' transport media. In a field study of 117 children, NP swabs were placed in ETA, after being vortexed in STGG and direct-plated for colony counts. Of 52 swabs that were culture positive for pneumococci, all 52 grew pneumococci after 4 days of storage in ETA, and 49 isolates were recovered after 7 days. Transport media such as Stuart's and Amies' require the processing of swabs within about 24 h, and storage in STGG broth requires freezing at -70 degrees C. ETA should be a useful addition to the storage media available for use in epidemiological studies of pneumococcal colonization, especially in situations where prompt processing, rapid transport, or low-temperature storage are not possible.

Anti-Bacterial Agents↗
PubMed2001

Level of maternal antibody required to protect neonates against early-onset disease caused by group B Streptococcus type Ia: a multicenter, seroepidemiology study.

Because of the difficulty of conducting efficacy trials of vaccines against group B streptococcus (GBS), the licensure of these vaccines may have to rely on studies that measure vaccine-induced antibody levels that correlate with protection. This study estimates the level of maternal antibody required to protect neonates against early-onset disease (EOD) caused by GBS type Ia. Levels of maternal serum IgG GBS Ia antibodies, measured by ELISAs in 45 case patients (neonates with EOD caused by GBS Ia) and in 319 control subjects (neonates colonized by GBS Ia but without EOD) born at > or =34 weeks gestation were compared. The probability of developing EOD declined with increasing maternal levels of IgG GBS Ia antibody (P = .03). Neonates whose mothers had levels of IgG GBS Ia antibody > or =5 microg/mL had an 88% lower risk (95% confidence interval, 7%-98%) of developing type-specific EOD, compared with those whose mothers had levels < 0.5 microg/mL. A vaccine that induces IgG GBS Ia antibody levels > or =5 microg/mL in mothers can be predicted to confer a high degree of type-specific immunity to EOD to their infants.

Age of Onset↗
PubMed2001

In vitro activity of ABT-773, telithromycin and eight other antimicrobials against erythromycin-resistant Streptococcus pneumoniae respiratory isolates of children.

The activity of the ketolide ABT-773 against 180 erythromycin-resistant Streptococcus pneumoniae obtained from children was compared with telithromycin, azithromycin, clarithromyin, roxithromycin, clindamycin, penicillin, levofloxacin and gatifloxacin. Ketolide MICs were all < or =1 mg/l, with ABT-773 being the most potent of all drugs tested. MIC(90)s for macrolides and azithromycin in mefE+ isolates were 16-32 compared with >128 mg/l for ermB+ isolates. ABT-773 and telithromycin MIC(90)s for mefE+ isolates were 0.125 and 0.5, compared with 0.032 and 0.016 mg/l for ermB+ isolates and 0.5 and 1 mg/l, respectively, for isolates containing both genes. Clindamycin was active against mefE+ but not ermB+ isolates. 155 isolates were resistant to penicillin. All fluoroquinolone MICs were < 1 mg/l. Further studies of ketolides for treatment of paediatric S. pneumoniae infections are warranted.

Anti-Bacterial Agents↗
PubMed2000

Failure To detect muramic acid in normal rat tissues but detection in cerebrospinal fluids from patients with Pneumococcal meningitis.

Muramic acid serves as a marker for the presence of bacterial cell wall debris in mammalian tissues. There have been a number of controversial and sometimes conflicting results on assessing the levels of muramic acid in health and disease. The present report is the first to use the state-of-the art technique, gas chromatography-tandem mass spectrometry, to identify and quantify the levels of muramic acid in tissues. Muramic acid was not found in normal rat brain or spleen. However, when tissues were spiked with muramic acid, it was readily identified. The detection limit was <1 ng of muramic acid/100 mg (wet weight) of tissue. The levels of muramic acid reported in diseased human spleen and spleen of arthritic rats, previously injected with bacterial cell walls, were 100- to 1,000-fold higher. In the present study, muramic acid was also readily detected in the cerebrospinal fluid of patients with pneumococcal meningitis (6.8 to 3,900 ng of muramic acid/ml of cerebrospinal fluid). In summary, there can be an enormous difference in the levels of muramic acid found in different mammalian tissues and body fluids in health and disease. This report could have great impact in future studies assessing the role of bacterial cell wall remnants in the pathogenesis of certain human inflammatory diseases.

Animals↗
PubMed2000

Does managed care mean more hassle for physicians?

Using the results of a 1995 nationally representative survey of physicians, this paper examines the relationship between exposure to managed care and resources expended by physicians on administrative and insurance matters. Our measures of managed care exposure are the degree to which a physician experiences a variety of managed care techniques (i.e., utilization review, capitation payment, restricted panels, gatekeepers, discounted fees, compensation links to utilization measures, profiling, protocols, and salary payment). Physicians report expending, on average, three hours per week on insurance-related matters and 4.8 hours per week on administration. Although managed care techniques affect administrative and insurance-related burdens, the direction of that effect varies according to the form that managed care exposure takes. With the exception of being salaried, none of our variables has an economically significant effect on physicians' administrative/insurance burdens, even at the outer-most edge of the 95% confidence interval. Overall, our findings contradict the widely held notion that managed care dramatically raises the administrative and insurance burden of physicians.

Attitude of Health Personnel↗
PubMed1998

Immunogenicity of pneumococcal vaccine in persons with spinal cord injury.

OBJECTIVE: To determine immunogenicity and optimum timing for administering the 23-valent pneumococcal vaccine after spinal cord injury (SCI). DESIGN: Double-blind, randomized, placebo control study. SETTING: SCI unit in a tertiary care medical center and community. PARTICIPANTS: Eighty-seven persons with recent SCI. INTERVENTION: Participants were randomized to receive either placebo or pneumococcal vaccine at 16 to 18 days versus 4 to 6 months postinjury. MAIN OUTCOME MEASURES: Antibody concentrations were measured prior to intervention and 1, 2, and 12 months afterward to evaluate the immune response to five serotypes of Streptococcus pneumoniae. Effects of demographic and injury-related variables on immune response were also evaluated. RESULTS: Timing of vaccination did not influence mean antibody concentrations for any serotype (p > .05). Ninety-five percent of vaccinated persons had twofold or greater increases in antibody concentration for at least one serotype when measured 1 month after vaccination versus 35% of placebo groups (p < .01). After 12 months, 93% of vaccinated persons in both groups maintained antibody concentrations twofold or greater than baseline values. CONCLUSIONS: Most participants developed an immune response to at least one serotype that was maintained for at least 12 months. Immune response varied according to serotype. Given the favorable immune response and no effect of timing, persons with SCI should receive pneumococcal vaccine during initial hospitalization.

Adolescent↗
PubMed1997

Reduction of serum cholesterol in Watanabe rabbits by xenogeneic hepatocellular transplantation.

Transplantation of xenogeneic hepatocytes would provide a novel therapy for liver disease and would help to solve the problem of an insufficient supply of donor organs. We have tested whether xenogeneic cells infused into the liver could correct the metabolic defect in the Watanable heritable hyperlipidemic (WHHL) rabbit, an animal model for homozygous familial hypercholesterolemia, and we have investigated whether the infused cells traverse the lining of the portal vasculature. We find that porcine hepatocytes are localized in the hepatic sinusoids after surgery and subsequently migrate out of the vessels and integrate into the hepatic parenchyma. The integrated porcine hepatocytes provide functional LDL receptors that lower serum cholesterol in the WHHL rabbit by 30-60% for at least 100 days.

Animals↗
PubMed1994

A clinically applicable technique to study cytoskeletal dynamics in normal and abnormal polymorphonuclear leukocytes isolated from small volume blood samples.

Shape change and motility of polymorphonuclear leukocytes (PMNs) are essential for host defense and require dynamic reorganizations of microfilamentous cytoskeleton by reversible polymerization of G-actin into filaments (F-actin). Although clinical disorders of actin polymerization are rare, recently described simple methodologies for assaying actin dynamics in PMNs make the technique readily applicable to clinical studies. To develop a clinically useful F-actin assay, the authors investigated the optimal preparation conditions for PMN isolation that resulted in the least in vitro cytoskeletal activation and evaluated the variability in actin dynamics in acutely and chronically infected patients. Basal and chemotactic factor-activated PMN F-actin content was measured by a previously described flow cytometric technique in fixed, permeabilized, NBDphallacidin-stained PMNs isolated by centrifugation in Percoll or Ficoll-Hypaque density gradients or by countercurrent elutriation. F-actin content is expressed as mean fluorescent channel or relative fluorescence intensity. Basal F-actin in PMNs prepared from countercurrent elutriation (mean fluorescent channel = 79.0 +/- 4.5, n = 6) or by Ficoll Hypaque (82.0 +/- 3.5, n = 4) was significantly higher than endotoxin free, Percoll purified PMNs, whether purified in bulk (56.1 +/- 7.9, n = 8) or by the small volume modification applicable to clinical studies (53.3 +/- 8.7, n = 15). Basal Ficoll Hypaque purified PMNs have evidence of shape change, whereas endotoxin free, Percoll purified PMNs are smooth and round and represent the most basal cell equivalent in F-actin content to a circulating PMN.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗
PubMed1993

Endotoxin-induced organ injury.

OBJECTIVE: To review the effects of endotoxemia on the major organ systems of the body and discuss potential mechanisms of tissue injury. DESIGN: Appraisal of 60 articles representing a cross section of studies relating to in vivo and in vitro responses to endotoxin. MAIN METHODS: Cell cultures, isolated tissue preparations, animal and human studies. RESULTS: Endotoxemia results in the activation of numerous cellular and hematogenous mediators. These mediators range from prostaglandins, thromboxanes, and leukotrienes, to complement components. Tumor necrosis factor may be responsible for initiating many of the observed responses to endotoxin. Species and tissue specificity are a prominent feature of the response to endotoxin. CONCLUSIONS: No single agent can yet be implicated as the common mediator of endotoxin-induced organ injury. Endotoxin initiates the elaboration of a cascade of secondary mediators that amplify the response to the initial insult. The relative importance of individual agents as mediators of the response to endotoxin varies with the experimental model studied.

Animals↗
PubMed1993

Capsular type-specific polysaccharide partially inhibits group B Streptococcus-induced pulmonary hypertension.

Capsular type-specific polysaccharide is thought to be an important pathogenetic factor in Group B streptococcus (GBS) sepsis. To determine the effects of capsular type-specific polysaccharide on GBS-induced hemodynamic responses, anesthetized infant piglets were infused for 3 h with three related GBS Type lb strains that express different amounts of capsular type-specific polysaccharide. A larger capsule strain and a smaller capsule strain were isolated from an infected infant and its mother, respectively. A capsule-deficient mutant was then made from the larger capsule strain by transposon insertion mutagenesis. The smaller capsule strain and capsule-deficient mutant caused similar elevations in mean pulmonary artery pressure and pulmonary vascular resistance index and reductions in cardiac index. The larger capsule strain caused moderate pulmonary hypertension, but this response was smaller than for the other two GBS strains. Further comparisons in responses between the large capsule strain and its capsule-deficient mutant were then performed using unanesthetized piglets. The mutant caused significantly greater pulmonary hypertension and arterial plasma thromboxane B2 levels than the large capsule strain. The pulmonary hypertension induced by both strains was reversed by dazmegrel, a thromboxane A2 synthase inhibitor. These results suggest that (1) capsular type-specific polysaccharide is not an essential component in the generation of acute hemodynamic responses; (2) expression of large amounts of capsular type-specific polysaccharide on the organism surface partially inhibits GBS-induced pulmonary hypertension; and (3) the inhibition of the pulmonary responses is due to reduced thromboxane A2 release.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Case report: Rhodococcus equi pneumonia in a patient infected by the human immunodeficiency virus.

Rhodococcus equi, a facultative intracellular bacterium, is a common cause of pulmonary infection in farm animals, especially foals. Pulmonary and disseminated infection caused by this organism is occasionally seen in humans, especially in patients whose cell-mediated immunity has been altered by glucocorticoids or cytotoxic chemotherapy. Not surprisingly, the organism may cause serious disease in human immunodeficiency virus (HIV)-infected humans whose T cell-dependent immune system has been profoundly suppressed. This report describes an HIV infected patient with Rhodococcus equi pneumonia and reviews nine additional HIV-infected patients. Treatment in humans is not standardized. Studies in foals indicate that erythromycin and rifampin together are the treatment of choice. The patient in this report responded to this treatment briefly before relapsing and dying of the infection.

Actinomycetales Infections↗