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Biomedical subjects

M C Roberts

Publications and source records attributed to M C Roberts.

At least 91 records · Page 5Linked to original sources
PubMed1996

Characterization of tetracycline and erythromycin resistance determinants in Treponema denticola.

Treponema denticola isolates were evaluated for the presence of known tetracycline and erythromycin resistance determinants by Southern blot hybridization of whole-cell DNA and PCR assays. We examined all isolates available, which included 12 clinical and 4 American Type Culture Collection isolates. Two isolates carried the Tet B determinant, five isolates carried both the Tet B and Erm F determinants, seven isolates carried the Erm F determinant, and two did not carry any of the Tet or Erm determinants tested. Both the Tet B and Erm F determinants appeared to be associated with the chromosome. Neither of the two T. denticola donors tested could transfer the Tet B determinant, but three of four T. denticola tested transferred the Erm F determinant to an Enterococcus faecalis recipient. This extends the host range of both the tetB and ermF genes into the genus Treponema.

Anti-Bacterial Agents↗
PubMed1996

Transferable erythromycin resistance in Listeria spp. isolated from food.

An erythromycin-resistant (Emr) Listeria innocua and an Emr Listeria monocytogenes isolate both carried ermC genes, which code for rRNA methylases. The ermC genes were transferable by conjugation to recipient L. monocytogenes, Listeria ivanovii, and Enterococcus faecalis but did not appear to be associated with conjugative plasmids.

Chromosomes, Bacterial↗
PubMed1996

Prokaryotic DNA sequences in patients with chronic idiopathic prostatitis.

Half of all men experience symptoms of prostatitis at some time in their lives, but the etiology is unknown for more than 90% of patients. Optimal clinical and culture methods were used to select 135 men with chronic prostatitis refractory to multiple previous courses of antimicrobial therapy. The subjects had no evidence of structural or functional lower genitourinary tract abnormalities of bacteriuria or bacterial prostatitis by traditional clinical tests, or of urethritis or urethral pathogens by culture. Specific PCR assays detected Mycoplasma genitalium, Chlamydia trachomatis, or Trichomonas vaginalis in 10 patients (8%). Broad-spectrum PCR tests detected tetracycline resistance-encoding genes, tetM-tetO-tetS, in 25% of patients and 16S rRNA in 77% of subjects. The tetM-tetO-tetS-positive cases constituted a subset of the 16S rRNA-positive cases. Patients with 16S rRNA were more likely to have > or = 1,000 leukocytes per mm3 in their expressed prostatic secretion than men whose prostate biopsy specimens were negative for 16S rRNA (P < 0.001). Based on direct sequencing and repetitive cloning, multiple sources of 16S rRNA were observed in individual patients. Sequences of 29 cloned PCR products revealed 16S rRNAs distinct from those of common skin and gut flora. These findings suggest that the prostate can harbor microorganisms that are not detectable by traditional approaches. These organisms may be associated with inflammation in the expressed prostatic secretions. Molecular methods hold great promise for identifying culture-resistant microorganisms in patients with chronic prostatitis.

Adult↗
PubMed1995

Accuracy of clinicians in predicting site and type of lesion as well as outcome in horses with colic.

OBJECTIVE: To assess the ability of clinicians to predict the site and type of lesion as well as outcome in horses with colic. DESIGN: Prospective case study. SAMPLE POPULATION: 139 horses admitted for evaluation of signs of colic. PROCEDURE: Six interns and residents examined horses with colic and predicted the segment of intestine that was affected, the type of lesion, and whether the horse would survive to discharge. Accuracy of prediction of site and type of lesion and survival prediction was compared between the first and second halves of the year, using chi 2 analysis and 95% confidence intervals on sensitivity and specificity. chi 2 Analysis was used to assess accuracy between predicted site and type of lesion and intraoperative or necropsy findings and to assess accuracy between predicted survival and actual outcome. RESULTS: Significant association existed between predicted segment of affected intestine or type of lesion and intraoperative findings (P < 0.05). There was a significant association between predicted survival and outcome (P < 0.001). Accuracy of survival prediction improved significantly (P = 0.002) during the year. CLINICAL IMPLICATIONS: Clinicians can accurately predict horses with colic that will survive surgery on the basis of clinical impressions. The ability to predict those horses that will survive improves with training.

Animals↗
PubMed1995

Cognitive change after treatment for neurosyphilis. Correlation with CSF laboratory measures.

The decision to re-treat a patient with neurosyphilis is usually based on the clinical response, cerebrospinal fluid (CSF), cell count, and CSF protein concentration. The value of the CSF Venereal Disease Research Laboratory (VDRL) test on its own as a marker for treatment response in neurosyphilis has not been established. To assess the usefulness of CSF markers for continuing infection, 12 patients with neurosyphilis were reevaluated 1 year after treatment. Change in cognitive functioning, as assessed by the Mini-mental State Examination (MMSE), was correlated with the CSF cell count, protein content, IgG index, and VDRL test titer at follow-up. A significant negative correlation was obtained between 1 year improvement in MMSE score and CSF VDRL titers at both the 6- and the 12-month follow-up examinations, and with the 6-month CSF protein concentration. These findings suggest that the CSF VDRL titer may be an indicator of continued Treponema pallidum activity in patients without obvious clinical deterioration.

Adult↗
PubMed1995

Class D and E tetracycline resistance determinants in gram-negative bacteria from catfish ponds.

DNA probes were used to examine tetracycline-resistant Gram-negative bacteria (281 strains representing eight species) from catfish ponds. The isolates, which did not previously hybridize with the Tet A, B and C determinants, were examined for the presence of tetracycline-resistance Tet D and Tet E determinants. The distribution of the Tet D determinant ranged from 0 to 83%, depending on the bacterial species. Tet E was found only in 69% of Aeromonas hydrophila isolates. Eighteen per cent failed to hybridize with any of the five Tet determinants.

Animals↗
PubMed1995

Detection of two groups of 25.2 MDa Tet M plasmids by polymerase chain reaction of the downstream region.

Forty-four Neisseria gonorrhoeae, 12 N. meningitidis, four Kingella denitrificans and one Eikenella corrodens carrying 25.2 MDa Tet M plasmids were analysed using polymerase chain reaction (PCR) to the downstream region of the incomplete Tet M transposon. From each isolate, one of two different PCR fragments of approximately 700 or 1600 bp were obtained. The two different sized PCR fragments had > or = 90% DNA sequence identity with Ureaplasma urealyticum Tet M downstream sequences. The difference between the large PCR fragment and the smaller PCR fragment was a deletion of over 800 bp in the smaller fragment. Both PCR fragments were found in plasmids isolated from N. gonorrhoeae and K. denitrificans. The smaller PCR fragment was found in N. meningitidis plasmids and the larger PCR fragment was found in the E. corrodens plasmid.

Bacterial Proteins↗
PubMed1995

Pulsed-field gel electrophoresis for genomic analysis of Neisseria gonorrhoeae.

Pulsed-field gel electrophoresis (PFGE) is a technique for analyzing large DNA fragments. PFGE was compared to auxotyping and Por serovar (A/S) classification to determine its utility in the study of gonococcal infection, subtyping A/S classes, and clone identification. PFGE patterns were stable in vitro after 2 isolates were passaged 50 times, and those from sex partners were indistinguishable with both enzymes. Fourteen proline-requiring IA-6 isolates from Kenya produced 8 NheI and 7 XbaI patterns; these included 6 Tet M-carrying isolates, all producing the same NheI pattern. PFGE patterns of 14 arginine-, hypoxanthine-, and uracil-requiring IA-1,2 isolates, from the US Pacific Northwest and Hawaii in 1993, were less diverse with both enzymes. PFGE analysis represents a potentially useful addition to the current gonococcal classification system.

Contact Tracing↗
PubMed1995

Factors affecting children's attitudes toward health care and responses to stressful medical procedures.

Assessed factors hypothesized to influence children's and mothers' attitudes toward health care phenomena and children's distress during a stressful medical procedure in a pediatric outpatient clinic. Children, ages 6-11 years, and their mothers attending a county health department for a well-child physical examination participated. Pearson correlation coefficients were calculated and hierarchical regression analyses were conducted. Results indicated that several factors, including age, health locus of control, and maternal health care attitudes were significant predictors and/or correlates of children's attitudes toward health care and their behavioral responses during an aversive procedure. Implications of these findings for health prevention and education efforts with children are discussed.

Adult↗
PubMed1995

Characterization of tetracycline resistance in Actinobacillus actinomycetemcomitans.

Comparison of susceptibility data for Actinobacillus actinomycetemcomitans has been difficult because of the lack of standard susceptibility testing conditions. In this study, minimum inhibitory concentration to tetracycline was evaluated by comparing different media, air conditions and incubation times. Ten of 22 (45%) A. actinomycetemcomitans isolated from periodontally diseased sites grew on media supplemented with 4 micrograms per ml of tetracycline, but minimum inhibitory concentrations ranged from 0.125 to 8 micrograms/ml depending on the media and condition used. The best results were obtained with brain heart infusion agar (Difco Laboratories, Detroit MI) incubated in 5% CO2 for 48 h. Eighteen (82%) of the A. actinomycetemcomitans isolates hybridized with the Tet B determinant. The Tet B determinant was transferable between A. actinomycetemcomitans isolates as well as a Haemophilus influenzae recipient and appears to be associated with conjugative plasmids.

Aggregatibacter actinomycetemcomitans↗
PubMed1995

Susceptibilities of Neisseria gonorrhoeae to the glycylcyclines.

To assess the activities of two glycylcyclines, N,N-dimethylglycylamido (DMG) derivatives of minocycline (MINO) and 6-demethyl-6-deoxytetracycline (DMDOT), 203 gonococcal isolates recovered at six sexually transmitted disease clinics in the western United States were evaluated. Antimicrobial susceptibilities to tetracycline HCl, doxycycline, MINO, DMG-DMDOT, and DMG-MINO were determined by agar dilution tests. DMG-DMDOT and DMG-MINO were more active than tetracycline HCl, doxycycline, or MINO regardless of the presence of Tet M or of chromosomal mutations mediating tetracycline resistance (P < 0.001).

Gonorrhea↗
PubMed1995

Vasopressin secretion and memory impairment in alcoholic Korsakoff's syndrome.

The response of arginine vasopressin (AVP) to an intravenous hypertonic saline infusion was investigated in 19 patients with alcoholic Korsakoff's syndrome, 17 non-amnesic alcoholics and 21 non-alcoholic controls. Compared with non-alcoholic controls the Korsakoff patients had elevated basal AVP levels and showed erratic fluctuation of AVP secretion, not related to changes in serum sodium levels. The non-amnesic alcoholics had a similar, but less severe derangement. Neuropsychological tests revealed significant correlations between basal AVP levels and memory performance in the non-amnesic alcoholics, raising the possibility of a common lesion--most likely in the diencephalon--for memory impairment and AVP dysregulation in chronic alcoholics.

Adult↗
PubMed1995

The thyrotropin releasing hormone stimulation test in alcoholism.

The mechanism for a blunted thyroid stimulating hormone (TSH) response to thyrotropin releasing hormone (TRH) in alcoholics is not known. We performed a combined TRH and gonadoliberin stimulation test on three well-defined groups of nondepressed alcoholic men. Group A comprised patients with acute withdrawal symptoms (n = 28), group B patients abstinent for 5-8 weeks (n = 29) and group C patients who had been abstinent for > 2 years (n = 16). Twenty-two healthy male volunteers were used for comparison. A blunted TSH response to TRH (delta TSH < 5 microU/l) occurred only in groups A (39%) and B (17%). In group A delta TSH showed a significant negative correlation with the severity of withdrawal symptoms and a significant positive correlation with serum magnesium levels. In group B, patients with a family history of alcoholism had significantly lower delta TSH levels than those without such a family history. Groups did not differ with respect to basal and delta prolactin, and TSH responses were not significantly associated with vitamin deficiency, cortisol levels or free thyroid hormone levels. We conclude that TRH stimulation test blunting appears to be related to factors operating in the withdrawal state and improves with continued abstinence. A possible role of genetic factors and serum magnesium needs to be further explored.

Adult↗
PubMed1994

Evaluation of factors associated with postoperative ileus in horses: 31 cases (1990-1992)

Medical records of horses that underwent surgical treatment for colic between 1990 and 1992 were reviewed. Horses with a pulse rate of > or = 60 beats/min or signs of abdominal pain, which were also accompanied by a volume of > 2 L of material that refluxed from the stomach during the postoperative period (excluding horses with anterior enteritis), comprised the postoperative ileus (POI) group. Horses that had < 2 L of material reflux during the postoperative period and survived > 3 days after surgery comprised the reference population. The association of preoperative and intraoperative clinical variables with development of POI was evaluated by use of logistic regression analysis. Of 148 horses, 117 were assigned to the reference population, and 31 (21%) developed POI. Multiple logistic regression analysis was used to determine that PCV, pulse rate, type and location of lesion detected during surgery, and serum glucose concentration were the most important variables associated with development of POI. Time of recovery from anesthesia to development of POI was 0.5 to 120 hours (median, 13 hours). Duration of POI was 1 to 7 days (median, 1 day). Four of 31 (13%) horses with POI died. Of 148 horses, only 10 (7%) died; however, 4 of the 10 (40%) deaths in the short-term postoperative period were attributable to POI.

Animals↗