Biomedical subjects

M C Roberts

Publications and source records attributed to M C Roberts.

At least 109 records · Page 6Linked to original sources

PubMed1994

Evaluation of the detection limits of PCR for identification of Mycoplasma pneumoniae in clinical samples.

The detection limits of the polymerase chain reaction (PCR) for Mycoplasma pneumoniae were determined using specimens from persons known to have had M. pneumoniae pneumonia. Four primers were selected from the known sequence of the P1 gene. The primer pair (P1-178 and P1-809) which generates a 631 fragment gave the lowest detection limit. Nineteen of 21 throat swabs, which contained between 0.06 and 2 colony-forming units (CFU) per microlitre, from culture positive patients, were positive by PCR. The fact that M. pneumoniae grows in broth culture in spherules causes problems for determining the number of CFU detected in PCR. Filtering broth cultures through a 0.6 micron polycarbonate filter increased the number of CFUs two-to-ten-fold compared to unfiltered cultures. The lysis method needed to assay throat swabs differed from that necessary for broth cultures in that proteinase K treatment for 18 h increased the detection limit 10- to 100-fold when compared to NaOH digestion.

Base Sequence↗

PubMed1994

Single polymerase chain reaction for the detection of tetracycline-resistant determinants Tet K and Tet L.

Oligonucleotide primers were used in polymerase chain reaction assays to detect tetracycline-resistant determinants Tet K and Tet L. Forty-three isolates representing 11 genera carrying Tet K and/or Tet L determinants gave appropriate PCR products. The PCR products hybridized with labelled Tet K or Tet L probes, and differentiated the Tet K from the Tet L PCR products. We confirmed that two Haemophilus aphrophilus carried the Tet K determinant and two Veillonella parvula carried the Tet L determinant. This is the first time that either of these two genes have been found in Gram-negative species. Four vaginal samples, previously positive with the Tet M/O PCR assay, were also positive with the Tet K/L assay. This is the first report of a PCR assay for the detection of Tet K and Tet L determinants in bacteria or clinical specimens.

Animals↗

PubMed1994

Macrolide-lincosamide resistance determinants in streptococcal species isolated from the bovine mammary gland.

Seventy one streptococci isolated from dairy cows with clinical mastitis were tested for erythromycin and lincomycin susceptibility. Ten isolates (7.1%) were resistant to erythromycin and/or lincomycin and seven were constitutive and three were inducibly resistant. Nine of the isolates hybridized with one or more of the Erm probes tested and eight isolates gave PCR products with rRNA methylase primers. The Erm determinants were transferable at frequency of 10(-5) to 10(-6) per recipient.

Animals↗

PubMed1994

Characterization of antibiotic resistance in Streptococcus suis.

Twenty one isolates of Streptococcus suis were screened for antibiotic resistance by growth on antibiotic-containing media, by measuring minimum inhibitory concentrations, by hybridization to specific DNA and oligonucleotide probes for antibiotic resistance genes, and by PCR. The isolates were from a slaughter house survey of respiratory pathogens in Norwegian pigs in 1986. Fifteen isolates were resistant to tetracycline, with MICs ranging from 4-128 micrograms/ml. Genes coding for the Tet O and Tet M determinants were detected in eight and five isolates, respectively. Genes coding for other Gram positive Tet determinants, Tet K, Tet L, and Tet P, were not detected. One isolate was constitutive resistant to erythromycin with MIC of 128 micrograms/ml. Five other isolates carried inducible erythromycin resistance. All these isolates, and five others, were positive in a PCR assay for erythromycin resistance, and hybridized with the Erm C and/or Erm B probes. No resistance against chloramphenicol (5 micrograms/ml) or rifampin (10 micrograms/ml) could be could be detected, but five isolates were resistant to streptomycin (250 micrograms/ml), four isolates were resistant to kanamycin (10 micrograms/ml), and one isolate was resistant to fusicic acid (10 micrograms/ml). In mating experiments with Enterococcus faecalis JH2-2 as recipient, tetracycline, erythromycin, and kanamycin genes were transferred separately to the recipient strain at a rate of 10(-7) transconjugants/recipient cell.

Animals↗

PubMed1994

Epidemiology of tetracycline-resistance determinants.

Resistance to tetracycline is generally due either to energy-dependent efflux of tetracycline or to protection of the bacterial ribosomes from the action of tetracycline. The genes that encode this resistance are normally acquired via transferable plasmids and/or transposons. Tet determinants have been found in a wide range of Gram-positive and Gram-negative bacteria and have reduced the effectiveness of therapy with tetracycline.

DNA Transposable Elements↗

PubMed1994

Characterization of the genetic basis of antibiotic resistance in Clostridium difficile.

By using dot blot hybridization, 69 of 102 Clostridium difficile isolates (68%) from the United States and other countries hybridized with at least one of nine DNA probes for erythromycin (Erm), tetracycline (Tet) or chloramphenicol (Cat) resistance determinants. The distribution of individual determinants in descending order of frequency was: Tet M, 32%; Erm Q, 25%; Erm FS, 18%; Tet P, 15%; Tet K, 15%; Cat P, 15%; Cat Q, 12%; Erm BP, 11%; Tet L, 7%. This is the first report of Tet P being carried by C. difficile and hitherto Erm FS has only been found within the genus Bacteriodes, while neither Tet K nor Tet L have been previously identified among the genus Clostridia. Eighteen percent of the hybridizing isolates carried multiple determinants coding for the same phenotype. A higher frequency of resistance genes was associated with prior exposure to antimicrobial agents, cytotoxin production and diarrhoea. Isolates recovered from bone marrow transplant patients carried significantly fewer antibiotic resistance genes than did those from immunocompetent general medicine patients. However, this may be due to the fact that each was located at a different site. Antibiotic resistance determinants may play a role in the virulence associated with C. difficile.

Clostridioides difficile↗

PubMed1994

Prevention/promotion in America: still spitting on the sidewalk.

Using a metaphor from disease prevention and health promotion efforts from the early 1990s, prevention and promotion efforts of the late 1900s are examined. Primary analyses are made on societal failures to grapple effectively with the major health problems associated with smoking, motor vehicles, and guns. Critical examples are described where American society and decision-makers lack commitment to prevention and promotion ideals and, in these and other situations, have actively encouraged the growth of health problems. The conclusion is drawn that the American society has acquiesced to let the major killers and disablers of children and adults to continue unabated. A stronger commitment to promotion and prevention is encouraged.

Accidents, Traffic↗

PubMed1994

Tetracycline resistance determinants in Mycobacterium and Streptomyces species.

Two of seven tetracycline-resistant (Tcr) Mycobacterium fortuitum group isolates and six Tcr clinical Streptomyces isolates carried gram-positive Tcr determinants (Tet K and Tet L) and Streptomyces resistance determinants (Otr A, Otr B, and Otr C). This represents the first documentation of the acquisition by mycobacteria of determinants coding for antibiotic resistance and suggests the potential for the spread of antibiotic resistance determinants within mycobacterial species.

Base Sequence↗

PubMed1994

Decreased susceptibility to penicillin G and Tet M plasmids in genital and anorectal isolates of Neisseria meningitidis.

Genital and anorectal isolates of Neisseria meningitidis were characterized, and their antimicrobial susceptibilities were determined. Twelve of 43 isolates demonstrated moderate susceptibility to penicillin G (MIC range, 0.125 to 0.5 microgram/ml). Two isolates were resistant to tetracycline (MIC, > or = 8 micrograms/ml) and contained plasmids of 25.2 MDa.

Anti-Bacterial Agents↗

PubMed1994

The usefulness of cerebrospinal fluid tests for neurosyphilis.

To determine the usefulness of cerebrospinal fluid (CSF) tests for syphilis at a large academic hospital, clinical and laboratory data on 644 patients in whom such testing was requested over a 12-month period were analysed. In 198 cases (31%) the Treponema pallidum haemagglutination (TPHA) screening test could not be performed because of insufficient fluid. Thirty-eight of the remaining patients were diagnosed as having active neurosyphilis. Examination of 22 files of patients who had a positive TPHA and fluorescent treponemal antibody absorption (FTA-Abs) test together with a negative CSF Venereal Disease Research Laboratory (VDRL) test revealed that other CSF measures indicating disease activity (CSF protein, cells or IgG index) were not utilised optimally. In 10 (45%) of these patients neurosyphilis was not diagnosed despite either abnormal or incomplete CSF biochemical analysis, indicating that if the CSF VDRL is used as the sole marker for disease activity, some cases of neurosyphilis are likely to be missed.

Adult↗

PubMed1994

Endocrine function in alcoholic Korsakoff's syndrome.

Hypothalamic-pituitary function was studied by means of several dynamic endocrine tests in 19 patients with alcoholic Korsakoff's syndrome, 17 non-amnesic alcoholics and 21 non-alcoholic controls. The responses of thyroid stimulating hormone, prolactin, follicle stimulating hormone, and luteinizing hormone to a combined thyrotropin releasing hormone and gonadoliberin stimulation test did not differ significantly. For the dexamethasone suppression test, the Korsakoff patients had significantly higher basal serum cortisol and 08:00 hr post-dexamethasone cortisol levels than non-alcoholic controls. These findings raise the possibility that chronically elevated cortisol levels may contribute to cognitive impairment in alcoholic Korsakoff's syndrome.

Adult↗

PubMed1993

Disordered water homeostasis and cognitive impairment in schizophrenia.

To investigate a possible association between disordered water homeostasis and cognitive impairment in schizophrenia, neuropsychological tests were applied to 16 schizophrenic patients with severely deranged water homeostasis and to 16 matched schizophrenic controls. The patients with disordered water homeostasis tended to obtain poorer scores than the controls throughout, the differences being statistically significant for two of the tests (Wechsler Memory Scale Visual Reproduction and Trial Marking Test part A). These results were not ascribable to differences in the duration of the illness, premorbid IQ, medication, or electroconvulsive therapy received, or prominence of any particular symptoms. The results suggest the co-existence of disordered water homeostasis and cognitive impairment in a subset of schizophrenic patients.

Adult↗

PubMed1993

Peritonitis in horses: 67 cases (1985-1990).

Peritonitis was diagnosed in 67 horses between 1985 and 1990: 14 horses developed septic peritonitis after intestinal rupture, 25 horses developed peritonitis after abdominal surgery, and 28 horses had peritonitis not associated with intestinal rupture or abdominal surgery. Forty of 67 horses (59.7%) did not survive. Nonsurvivors had higher heart rates (P = 0.01), RBC count (P = 0.039), serum creatinine concentration (P = 0.036), PCV (P = 0.007), and anion gap (P = 0.005); lower venous blood pH (P = 0.002); and a greater number of bacterial species cultured from peritoneal fluid samples (P = 0.054), compared with those from survivors. Nonsurvivors were more likely to have signs of abdominal pain (P < 0.000), circulatory shock (P = 0.009), and bacteria in peritoneal fluid samples (P = 0.042). Physical examination and peritoneal fluid analysis were the most valuable diagnostic aids for intestinal rupture. Peritonitis after abdominal surgery resulted in high mortality (56%); peritonitis not associated with intestinal rupture or abdominal surgery had lower mortality (42.9%). Clinical and laboratory indices can be of value in determining the prognosis for horses with peritonitis.

Animals↗

PubMed1993

Detection of Tet M and Tet O tetracycline resistance genes by polymerase chain reaction.

Degenerate oligonucleotide primers were used in polymerase chain reaction assays to detect tetracycline resistance genes, Tet M and Tet O. Each of 44 clinical isolates and eight laboratory strains, representing 20 different species carrying either Tet M or Tet O determinants, gave appropriate PCR products with the two primer sets. The PCR products hybridized with radiolabelled Tet M or Tet O probes. The PCR assay was then used to evaluate vaginal swab specimens from women with vaginitis and semen specimens from men with prostatis. Seven of eight vaginal samples and five of eight semen samples exhibited PCR products that hybridized with the radiolabelled probes, suggesting the presence of Tet M and/or Tet O genes. PCR-based detection of Tet M and/or Tet O genes holds promise for evaluation of urogenital specimens.

Bacteria↗

PubMed1993

Children's perceptions of ill peers as a function of illness conceptualization and attributions of responsibility: AIDS as a paradigm.

Assessed the impact of developmental level of illness conceptualization and degree of assigned responsibility on children's reactions to ill peers. Accounts of hypothetical peers were manipulated in a multivariate design with three levels of Disease Label (AIDS vs. cystic fibrosis vs. no label) and two levels of Responsibility Information (low responsibility vs. no responsibility information), with the children's conceptualizations as a continuous variable. Subjects receiving information that the peer was not responsible for the illness tended to endorse higher ratings of acceptance than those receiving no information about illness responsibility. Accounts of peers with AIDS resulted in lower ratings of acceptance than those presented with accounts of peers with cystic fibrosis or an unlabeled illness. Subjects obtaining higher illness conceptualization scores tended to perceive less vulnerability to casual contagion.

Acquired Immunodeficiency Syndrome↗

PubMed1993

Society of Pediatric Psychology Task Force Report: pediatric psychology and injury control.

Injuries are the major causes of death for children. Pediatric psychology offers significant contributions to the multidisciplinary efforts necessary to prevent injuries and reduce harm to children. This Task Force Report reviews epidemiological data, characteristics of children's injuries, passive and active interventions for reducing injuries, and research, policy, and evaluation issues for individual and community injury control efforts. Directions for future pediatric psychology efforts are identified and placed in a context of collaborative efforts required to advance the control of children's injuries.

Adolescent↗

PubMed1993

Genetic basis of tetracycline resistance in food-borne isolates of Listeria innocua.

Eleven of 12 tetracycline-resistant Listeria innocua strains, isolated from chicken or turkey frankfurters and mozzarella cheese, were shown to carry DNA sequences which hybridized with the Tet M probe; of these, two strains also hybridized with Tet K. The remaining strain hybridized with the Tet K probe only. The Tet M determinant appeared to be located on the chromosome; in one case, it was transferable by conjugation to recipients Listeria monocytogenes, Listeria ivanovii, and Enterococcus faecalis.

Cheese↗

PubMed1993

Morphologic characterization of castor oil-induced colitis in ponies.

Ten ponies (160-250 kg, ages 17 months to 20 years) developed severe diarrhea within 24 hours of castor oil administration (2.5 ml/kg orally). The diarrhea was most severe between 24 and 48 hours post-dosing and subsided by 72 hours. Ponies were euthanatized at 24, 48, and 72 hours post-dosing and intestine was evaluated histologically and ultrastructurally. Twenty-four hours after dosing, the mucosa of the cecum and ventral colon had extensive superficial epithelial erosion and neutrophil infiltration. In the ileum, the epithelium of villous tips was separated from the lamina propria. Scanning electron microscopic examination of the cecal mucosa revealed that basement membranes were exposed in most areas except within necks of crypts. Ultrastructurally, changes in superficial enterocytes of the cecum and ventral colon were characterized by loss of microvilli, distortion of the cytoplasmic terminal web, expansion of the cytoplasmic matrix with formation of precipitates, and widening of intercellular spaces between junctional complexes. Enterocytes located within necks of crypts were flattened along the basement membrane and extended to margins of erosions. Venules within the superficial lamina propria were occluded by fibrin thrombi. Erosions in the cecum and ventral colon of ponies examined 48 hours after treatment were less extensive than those of ponies examined at 24 hours. At 48 hours post-dosing, basement membranes adjacent to crypts were covered by cuboidal enterocytes characterized ultrastructurally by sparse, irregularly shaped microvilli located on broad cytoplasmic protrusions and by numerous free ribosomes. These features indicated that immature enterocytes had migrated from crypts to resurface the eroded mucosa.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗