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Biomedical subjects

M Wilson

Publications and source records attributed to M Wilson.

At least 559 records · Page 31Linked to original sources
PubMed1989

[Neisseria gonorrhoeae: 3 years of surveillance of antibiotic susceptibility and search of beta-lactamase-producing strains].

247 strains of N gonorrhoeae were isolated from 453 patients with acute urethritis from 1985 to 1987. 19 strains produced beta-lactamase for a 7, 13 and 3% incidence in each of the 3 years. MIC between 1 and 8 micrograms/ml or between 65 and 256 micrograms/ml were found in 2 groups of beta lactamase producing strains. An increase in the sensitivity rate (81%) to penicillin of non beta-lactamase producing strains was observed in this period. The sensitivity to erythromycin and chloramphenicol remained constant while a slight increase in resistance to tetracycline was observed.

Anti-Bacterial Agents↗
PubMed1989

Differential distribution of immature Ixodes dammini (Acari: Ixodidae) on rodent hosts.

Ectoparasites such as ixodid ticks that remain attached to hosts for several days while feeding on blood are able to overcome the inflammatory and immune responses of some hosts and not others. The immature stages of the deer tick Ixodes dammini are found more frequently on the white-footed mouse, Peromyscus leucopus, than on other rodents. We propose that P. leucopus is more tolerant to I. dammini than is a less common host, the meadow vole, Microtus pennsylvanicus. To test this hypothesis, the distribution patterns and engorgement indices were determined for larval and nymphal I. dammini collected from wild-caught P. leucopus and M. pennsylvanicus. There were more immature ticks, which were more fully engorged, on P. leucopus than on M. pennsylvanicus. There were more and better engorged ticks on male than on female hosts. Laboratory studies on the number and weights of larval I. dammini collected off naive and previously exposed P. leucopus and M. pennsylvanicus support the results of the field study. Fewer larval ticks were recovered from previously exposed M. pennsylvanicus than P. leucopus, and the ticks weighed less. Larval and nymphal ticks aggregated among hosts in the study grid, and higher densities per male P. leucopus were correlated with higher engorgement indices, suggesting that immature I. dammini feed better at higher densities. The feeding success of I. dammini on its preferred host species might be due to its adaptation to the immune and inflammatory reactions of the host.

Animals↗
PubMed1989

The effect of chlorhexidine on Streptococcus sanguis biofilms.

The bactericidal effect of chlorhexidine on Streptococcus sanguis biofilms was investigated and compared with its effect on suspensions of the organism. The biofilms were found to be more resistant to the bactericidal effects of chlorhexidine than the bacterial suspensions in terms of the number of surviving organisms. The minimum inhibitory concentration (MIC) being 25 and 50 micrograms/ml, respectively, for the suspension and the 24 h biofilm. The age of the biofilm had a marked effect on the number of bacteria surviving. Older (72 h) biofilms tended to be more resistant to chlorhexidine than younger (24 h) ones, with the MIC being 200 and 50 micrograms/ml, respectively. Addition of blood to the test system greatly reduced the bactericidal effect of the chlorhexidine, increasing the MIC for the 24 h biofilm from 50 to 200 micrograms/ml.

Animals↗
PubMed1988

Evolutionary social psychology and family homicide.

Homicide is an extreme manifestation of interpersonal conflict with minimal reporting bias and can thus be used as a conflict "assay." Evolutionary models of social motives predict that genetic relationship will be associated with mitigation of conflict, and various analyses of homicide data support this prediction. Most "family" homicides are spousal homicides, fueled by male sexual proprietariness. In the case of parent-offspring conflict, an evolutionary model predicts variations in the risk of violence as a function of the ages, sexes, and other characteristics of protagonists, and these predictions are upheld in tests with data on infanticides, parricides, and filicides.

Age Factors↗
PubMed1988

Cottonseed hypersensitivity: new concerns over an old problem.

Seven subjects, who experienced systemic allergic reactions after the ingestion of a newly marketed food supplement, were evaluated to identify the responsible ingredient. Skin testing with extracts prepared from ingredients in the food supplements revealed marked sensitization of all of the subjects to cottonseed protein. Double-blind, placebo-controlled food challenges performed in two subjects with cottonseed flour produced reactions consisting of oropharyngeal pruritus, rhinitis, nausea, diaphoresis, dyspnea, cough, and a fall in pulmonary function tests of 45% or more. All placebo challenges were negative. Because of the reactions observed during these challenges, other subjects were not challenged orally with cottonseed protein but consumed without incident other ingredients in the supplement to which they were skin test positive. Our evaluation strongly incriminates cottonseed protein as the cause of the systemic allergic reactions in these subjects and is consistent with earlier articles in the literature describing the potent allergenicity of cottonseed protein.

Adolescent↗
PubMed1988

Assessment of c-myc expression in individual leukemic cells.

The expression of the proto-oncogene c-myc was studied at the protein level in cells obtained from patients with AML and CML. In florid AML and during the blastic phase of CML the majority of cells contain c-myc protein with the amount of protein differing widely among the cells of individual patients. In contrast, during complete remission in AML and during the chronic phase of CML cells containing c-myc protein are rare. Several studies demonstrated a discordance in the amount of c-myc transcript and the amount of c-myc protein present in cell populations thereby suggesting the presence of translational or post-translational regulation of c-myc expression. Further, the data suggest that high levels of c-myc protein in the leukemic cells of AML patients are associated with a poor response to therapy and that high levels in AML patients in CR or in the peripheral blood of chronic phase CML patients may be indicative of impending acute leukemia.

Gene Expression Regulation↗
PubMed1988

Changes in rate and pattern of caffeine metabolism after cigarette abstinence.

Caffeine metabolism is known to be accelerated in cigarette smokers, but the effects of smoking on the kinetics and pattern of metabolism in a daily consumption pattern have not been described. We investigated the effects of tobacco abstinence on the rate and pattern of caffeine metabolism in nine habitual smokers who consumed six cups of coffee per day, each cup containing 2 mg/kg caffeine. Abstinence from smoking for 4 days resulted in a 46% increase in the 24-hour AUC. Thus, significant, although probably not complete, normalization of the enzyme-inducing effects of cigarette smoking can be seen after 4 days abstinence. During abstinence, 24-hour urine ratios of dimethylxanthines to caffeine and mono-dimethylxanthines to dimethylxanthines were reduced, suggesting that cigarette smoking accelerates both demethylation steps. Other metabolic pathways were unaffected.

Adult↗
PubMed1988

Membrane currents in retinal bipolar cells of the axolotl.

By whole-cell patch-clamping bipolar cells isolated from enzymatically dissociated retinae, we have studied the nonsynaptic ionic currents that may play a role in shaping the bipolar cell light response and in determining the level of voltage noise in these cells. Between -30 and -70 mV, the membrane current of isolated bipolar cells is time independent, and the input resistance is 1-2 G omega. Depolarization past -30 mV activates an outward current (in less than 100 ms), which then inactivates slowly (approximately 1 s). Inactivation of this current is removed by hyperpolarization over the range -20 to -80 mV. This current is carried largely by K ions. It is not activated by internal Ca2+. The membrane current of isolated bipolar cells is noisy, and the variance of this noise has a minimum between -40 and -60 mV. At its minimum, the standard deviation of the voltage noise produced by nonsynaptic membrane currents is at least 100 microV. The membrane currents of depolarizing bipolar cells in slices of retina were investigated by whole-cell patch-clamping. Their membrane properties were similar to those of isolated bipolar cells, but with a larger membrane capacitance and a smaller input resistance. Their membrane current noise also showed a minimum near -40 to -60 mV. The time-dependent potassium current in axolotl bipolar cells is not significantly activated in the physiological potential range and can therefore play little role in shaping the bipolar cells' voltage response to light. Differences in the waveform of the light response of bipolar cells and photoreceptors must be ascribed to shaping by the synapses between these cells. The noise minimum in the bipolar membrane current is near the dark potential of these cells, and this may be advantageous for the detection of weak signals by the bipolar cells.

Adenosine Triphosphate↗
PubMed1988

Human-rhesus reassortant rotavirus vaccines: safety and immunogenicity in adults, infants, and children.

Human-rhesus reassortant rotavirus vaccines derived from rhesus rotavirus and human rotavirus serotypes 1, 2, or 4 were administered to adults, children, and infants after they had been given sodium bicarbonate buffer. Over 70% of infants and children developed antibody responses to or shed the candidate vaccine viruses. Individuals with prevaccination serum neutralization antibody titers less than or equal to 1:160 had significantly (P less than .0001) higher response rates than did individuals with prevaccination titers greater than or equal to 1:320. Similarly, shedding of vaccine viruses occurred significantly (P = .03) more often in children than adults and was inversely correlated with prevaccination antibody titers. No illnesses were observed in adults, and the vaccines were well tolerated in children. An increased rate of low-grade, transient fever (38.0-38.8 C) was noted only in children given serotype 2 vaccine, compared with controls (P = .006). No significant differences in the average number of unformed stools passed during the seven days after vaccination were noted in vaccinees versus controls. These vaccine strains are currently undergoing further evaluation in expanded clinical trials.

Adult↗
PubMed1988

Response of preterm infants to diphtheria-tetanus-pertussis vaccine.

The American Academy of Pediatrics recommendation that immunization of preterm infants with diphtheria-tetanus-pertussis (DTP) vaccine should begin at 2 months after birth, regardless of gestational age, is based on limited data. A prospective study was conducted to determine the immunogenicity and safety of DTP vaccine in preterm infants. One hundred ten preterm and 146 full term infants received doses of DTP at 2, 4 and 6 months after birth. Adjusted analysis of the antibody responses indicated that after three doses mean titers among preterm infants to each vaccine component were comparable to those of full term infants. Adjusted analysis of the incidence of adverse events indicated that the risk of adverse events in preterm infants was not significantly higher than that in full term infants. DTP vaccine is immunogenic and safe in preterm infants when the series is initiated at 2 months after birth, and this study supports the current recommendation of the American Academy of Pediatrics.

Antibody Formation↗
PubMed1988

Four new species of Isospora from the small tree finch (Camarhynchus parvulus) from the Galapagos Islands.

Four isosporan species are described from the small tree finch, Camarhynchus parvulus from Isabela Island on the Galapagos Archipelago. Isospora exigua n. sp. oocysts subspheroidal, one-layered, smooth, yellow-brown color, 20.4 X 20.1 (20-23 X 18-23) microns, with no micropyle, residuum, or polar body. Sporocysts ovoidal, 14 X 9.5 (13-15 X 8-10) microns, with small Stieda and substieda bodies and irregular-shaped residuum. Isospora rotunda n. sp. oocysts subspheroidal, single-layered, smooth, yellow-brown wall with large polar body and no micropyle or residuum, 20.9 X 20.8 (20-24 X 19-23) microns. Sporocysts ovoidal, 15 X 9.7 (13-16 X 9-10) microns with knob-like Stieda bodies, prominent substieda bodies and round residuum. Isospora fragmenta n. sp. oocysts subspheroidal with no micropyle or residuum but with many splinter-like polar granules and a smooth, colorless, single-layered wall, 25.3 X 24.2 (24-27 X 23-25) microns. Sporocysts piriform 15.4 X 11.5 (14-17 X 11-12) microns with knob-like Stieda bodies, prominent substieda bodies, and irregular-shaped residuum. Isospora temeraria n. sp. oocysts ellipsoidal with one polar body, no micropyle or residuum, and wall of a single layer, smooth, yellow-brown color, 25.4 X 21.1 (21-30 X 17-23) microns. Sporocysts piriform, 15 X 10 (14-15 X 9-11) microns with knob-like Stieda bodies, prominent substieda bodies, and a round residuum. One woodpecker finch, Cactospiza pallida, was found to be infected with I. exigua, and a warbler finch, Certhidea olivacea was infected with I. fragmenta.

Animals↗
PubMed1988

Root surface debridement--an in vitro assessment.

Root planing has been advocated to render periodontally involved root surfaces 'biologically compatible' with the surrounding soft tissues and thus promote healing. However, recent work has shown that only small amounts of cytotoxic material are likely to be incorporated within the root surfaces, thereby questioning the rationale for the traditional emphasis that is placed upon the removal of 'diseased cementum'. This investigation assessed by limulus amoebocyte lysate (LAL) assay and Polymyxin B affinity chromatography the extent of residual lipopolysaccharide (LPS) following root surface instrumentation in vitro. A conservative regime was carried out, consisting of 15 instrument strokes per surface designed to ensure complete overlapping of the strokes. This harvested varying amounts of LPS from 18 single-rooted teeth while leaving behind less than 0.24 ng of LPS per tooth in the majority (72%) of cases. This finding endorses the growing belief that extensive root planing may not be warranted.

Chromatography, Affinity↗