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Biomedical subjects

J A Mayo

Publications and source records attributed to J A Mayo.

18 recordsLinked to original sources
PubMed1992

Effects of the Nd:YAG dental laser on plasma-sprayed and hydroxyapatite-coated titanium dental implants: surface alteration and attempted sterilization.

The Nd:YAG dental laser has been recommended for a number of applications, including the decontamination or sterilization of surfaces of dental implants that are diseased or failing. The effects of laser irradiation in vitro (1) on the surface properties of plasma-sprayed titanium and plasma-sprayed hydroxyapatite-coated titanium dental implants, and (2) on the potential to sterilize those surfaces after contamination with spores of Bacillus subtilis have been examined. Surface effects were examined by scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction after laser irradiation at 0.3, 2.0, and 3.0 W using either contact or noncontact handpieces. Controls received no laser irradiation. Melting, loss of porosity, and other surface alterations were observed on both types of implants, even with the lowest power setting. For the sterilization study, both types of implants were first sterilized by exposure to ethylene oxide and then contaminated with spores of B subtilis. After laser irradiation, the implants were transferred to sterile growth medium and incubated. Laser irradiation did not sterilize either type of implant. The spore-contaminated implants in the control group were successfully sterilized with ethylene oxide.

Bacillus subtilis↗
PubMed1991

PDQ-R personality disorders in bipolar patients.

The prevalence of personality traits and disorders in bipolar patients as reported in the literature varies widely. The Personality Diagnostic Questionnaire-Revised (PDQ-R) is a self-report instrument for DSM-IIIR personality disorders found to have validity, but with high sensitivity and moderate specificity. This study was designed to assess personality disorders in bipolar patients using the PDQ-R. Fifty bipolar patients in a long-term lithium treatment program completed the PDQ-R. Over one half the patients (58%) scored for one or more personality disorders. A total of 71 diagnoses was made among the 50 patients, or a mean of 1.42 per patient. The majority of the axis II diagnoses were from cluster B, with borderline the most prevalent, followed by histrionic. The PDQ-R has high sensitivity but moderate specificity and may overdiagnose personality disorders in bipolar patients. The PDQ-R may register subclinical aspects of affective disorder as personality.

Adult↗
PubMed1991

Outcome of bipolar disorder on long-term treatment with lithium.

The long-term treatment outcome of 248 bipolar patients in an out-patient lithium programme was assessed. Over half of the patients (138 or 56%) had no affective episodes in the year observed. Patients were divided into outcome groups according to GAS scores: the outcome for 40% of patients was good, for 41% fair, and for 19% poor. More frequent psychiatric admissions before starting lithium treatment was the best predictor of poor outcome, followed by a negative affective style in the family and lower social class. Current alcohol and drug abuse was associated with poor outcome. Although familial and psychosocial factors were significantly associated with outcome, the findings suggest there may be inherent differences in the pathophysiology of bipolar disorder reflected in an increased frequency of episodes which account for a large variance in lithium treatment outcome.

Adult↗
PubMed1991

Subgingival bacteria associated with hydroxylapatite-coated dental implants: morphotypes and trypsin-like enzyme activity.

This study investigated the colonization of teeth and hydroxylapatite-coated dental implants by different groups of oral bacteria. Periodontal and gingival health were assessed and subgingival plaque samples were taken. Bacterial morphotypes in subgingival plaque samples were enumerated and expressed as percent of bacteria counted, and presence of trypsin-like enzymes was detected by hydrolysis of benzoyl-arginine naphthylamide (BANA). For both pooled and separate implant and teeth data, positive correlations were found between pocket depth and both BANA hydrolysis and percent spirochetes, and a negative correlation was found between pocket depth and percent cocci. With one exception, analysis of variance revealed no significant differences between implants and teeth for presence of bacterial morphotypes when considering both periodontal and gingival health.

Adult↗
PubMed1989

Comparison of properties of collected cells and cells from the culture vessel during continuous culture of Streptococcus mutans Ingbritt.

In continuous-culture studies chemostat effluents are usually collected into a receiving flask in an ice bath to obtain enough cells for an experiment. It is assumed that the properties of these are not significantly different from those of the culture in the chemostat vessel. This assumption has been tested for the dental pathogen Streptococcus mutans Ingbritt. Collected supernatant fluid and cells were compared with supernatant fluid and cells taken directly from the culture vessel, for four major groups of culture properties: viability and biomass, concentrations of metabolites and nutrients, activities of selected enzymes, and glycolytic rates. The assumption held true except for glycolytic rate during endogenous metabolism. It is suggested that comparison of collected and culture vessel cells is an important control which should be done in all continuous culture studies of microbial physiology and biochemistry, but that the properties of Strep. mutans cells collected on ice up to 16 h do reflect those of cells actively growing in the chemostat.

Bacteriological Techniques↗
PubMed1988

The role of social factors in affective disorders: a review.

A number of researchers, dissatisfied with traditional models of affective illness, have developed multidimensional systems models that more accurately reflect how genetic, biological, and social factors may interact to increase vulnerability or resilience to stressors and illness. The role of five social factors in this process--demographics, early childhood experiences, life events, social support, and families--is reviewed. Serious methodologic difficulties hamper the study of social factors in affective illness, prompting the authors to suggest that researchers develop a new research paradigm that attempts not only to quantify social factors but to understand their meaning to the individual.

Humans↗
PubMed1979

DNA base composition, nature of intracellular DNA, morphology, and classification of bacteriophages infecting Micrococcus luteus.

Ten bacteriophages infecting Micrococcus luteus have been characterized. All phages contain double-stranded DNA, of 64.3--73.5 mol% guanine plus cytosine (GC). The DNA of phage N7 has the highest GC content reported for any bacterial virus. No unusual bases have been found. The intracellular replicating DNAs of six phages are covalently closed circular molecules. All 10 phages have isometric, probably icosahedral, heads and long, flexible, noncontractile tails and can be sorted into two morphological groups based on size and presence or absence of a collar. Host-range studies indicate six host-range groups.

Bacteriophages↗
PubMed1979

Families of manic-depressive patients: effect of treatment.

The authors studied the families of 12 patients with bipolar manic-depressive illness. They measured family stability using a life events scale for a 2-year period before lithium treatment and for 2 years during lithium treatment. The patients responded well to treatment; they were able to resume normal roles within the family. The life events scores decreased substantially during treatment in comparison with before treatment. The most severe impact of the illness was found in the children: 45% (N = 10) were moderately ill or symptomatic. The authors discuss the effect of manic-depressive illness on the family system as a whole and emphasize the need to combine psychosocial treatment with lithium treatment.

Adolescent↗
PubMed1978

A comparison of methods for detecting bacteriophage contamination of tissue culture sera.

Detection of bacteriophage contamination of tissue culture sera by direct plating has been compared with detection methods based on batch enrichment and on the Poisson distribution (PD plating). Batch enrichment is extremely sensitive for detecting the presence of phage contamination. PD plating combines sensitivity with isolation of each contaminating phage in pure culture. Both batch enrichment and PD plating are more sensitive than direct plating. Neither method requires highly trained personnel or specialized equipment.

Bacteriophages↗
PubMed1977

Changes in macromolecular synthesis in Xanthomonas oryzae infected with bacteriophage XP-12.

Phage XP-12, which has complete substitution of the cytosine residues in its DNA with 5-methylcytosine residues, was shown to inhibit incorporation of uracil into host DNA and RNA during the latent period. This apparent inhibition of host macromolecular synthesis was not accompanied by extensive degradation of the host chromosome. Phage DNA synthesis in infected cells occurred at a faster rate than host DNA synthesis in analogous uninfected cells. However, phage DNA synthesis could not be accurately monitored by incorporation of [methyl-3H]thymidine into DNA because, soon after infection, there was a marked inhibition of utilization of exogenous thymidine for DNA synthesis. Phage infection conferred upon a thymine auxotrophic host the ability to synthesize thymine nucleotides for phage DNA synthesis. It is suggested that a phage-induced thymidylate synthetase activity is partially responsible for the inhibition of thymidine incorporation.

Bacteriophages↗
PubMed1975

Unusual properties of the DNA from Xanthomonas phage XP-12 in which 5-methylcytosine completely replaces cytosine.

Xanthomonas phage XP-12 contains 5-methylcytosine completely replacing cytosine. This substitution confers several unusual properties upon XP-12 DNA. The buoyant density of XP-12 DNA in CsCl gradients is 1.710 g/cm-3, 0.16 g/cm-3 lower than that expected for a normal DNA with the same percentage of adenine plus thymine. The melting temperature for XP-12 DNA in 0.012 M Na+ is the highest reported for any naturally occurring DNA, 83.2 degrees C, 6.1 degrees C higher than that of normal DNAs with the same percentage of adenine plus thymine. Unlike the minor amounts of 5-methylcytosine found in most plant and animal DNAs, the 5-methylcytosine residues of XP-12 derive their methyl group from the 3-carbon of serine instead of from the thiomethyl carbon of methionine. .

Bacteriophages↗
PubMedDate not supplied

Bacterial biofilm: a source of contamination in dental air-water syringes.

This study examined the bacteriology of dental air-water syringes, and found that the water delivered by these syringes can be persistently contaminated with bacteria. Flushing of the water line reduced but did not eliminate this contamination. Even after six minutes' flushing, some water samples still contained more than 10(4) viable bacterial cells per milliliter, although coliform counts were less than two per 100 milliliters as measured by a Most Probable Number assay. Sterilization of the tip or the entire syringe did not eliminate this contamination. Scanning electron microscopy revealed bacterial biofilms on the inner wall of the plastic tubing supplying water to the air-water syringe, but not on the air line or on new, unused tubing. Such biofilms probably can be found in any tubing which supplies water to components of dental units. The inoculum for these biofilms comes from ubiquitous environmental aquatic bacteria, some of which can cause disease in compromised patients. Biofilms can be held in check by regular flushing of the water lines with a biocide, and the authors affirm the use of the ADA guidelines for treatment of contaminated dental-unit water lines to control possible cross-infection.

Communicable Disease Control↗