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Biomedical subjects

M Wilson

Publications and source records attributed to M Wilson.

At least 523 records · Page 29Linked to original sources
PubMed1991

Serodiagnosis of echinococcosis: evaluation of two reference laboratories.

Two reference laboratories (CDC, Atlanta, and Institute of Hygiene, Vienna) were evaluated for their ability to diagnose echinococcosis from single serum-specimens by serological assays. Out of 18 specimens, both laboratories correctly identified the 12 sera from patients with echinococcosis. Each laboratory was able to give the species diagnosis for 11 of 12 cases. The CDC abstained from giving a final species-diagnosis for a serum from a patient with alveolar echinococcosis, the Institute of Hygiene similarly, for a case of cystic echinococcosis. Our findings reveal the considerable potential of today's serological methods for primary diagnosis of infections with Echinococcus granulosus and Echinococcus multilocularis.

Adult↗
PubMed1990

The anti-proliferative properties of 4-benzylphenoxy ethanamine derivatives are mediated by the anti-estrogen binding site (ABS), whereas the anti-estrogenic effects of trifluopromazine are not.

We compared the anti-proliferative properties of 4-benzylphenoxy-N ethyl morpholine (morpho-BPE) and trifluopromazine (TFP) on both the human breast cancer cell lines, MCF7, and its tamoxifen-resistant variant RTx6. We found that the calmodulin antagonist trifluopromazine (TFP) which bound ABS weakly, inhibited MCF7 cell growth but did not follow the relationship observed for diphenylmethane derivatives between MCF7-inhibitory potencies and their Ki. Regarding the tamoxifen-resistant RTx6 cells, TFP but not morpho-BPE induced inhibition of the proliferation. Using a tritiated derivative of morpho-BPE, two distinct binding sites could be demonstrated. Indeed, a low affinity binding site was present in both cell lines whereas a high affinity binding site was mainly found in MCF7 cells although being in lower concentration (less than 10%) in RTx6 cells. Both tamoxifen and TFP displaced morpho-BPE from the two binding sites. The uptake and efflux of the tritiated drug were similar in the two cell lines. The drug did not appear to be metabolized. We concluded that TFP and morpho-BPE belong to distinct classes of molecules and that ABS mediates the anti-proliferative action of diphenylmethane derivatives but not the inhibitory effect of the calmodulin antagonist TFP.

Antineoplastic Agents↗
PubMed1990

The lateral spread of signal between bipolar cells of the tiger salamander retina.

When mapped with a small spot of light, the central receptive fields of bipolar cells in the salamander retina are much larger than the extent of bipolar cell dendrites. Furthermore responses of bipolar cells to distant spots of light are considerably delayed relative to proximal spots. Using quantitative modelling, electrical coupling between bipolar cells is examined and rejected as a sufficient explanation of the data. An active process appears to shape signal waveform as signals spread laterally in the bipolar cell layer. Chemical synaptic coupling between bipolar cells is considered and shown to be inconsistent with the data. It is suggested that local, transient negative feedback from amacrine cells is involved in shaping bipolar cell signals.

Animals↗
PubMed1990

The prevalence of beta-lactamase producing bacteria in subgingival plaque and their sensitivity to Augmentin.

Subgingival plaque samples from 20 patients with chronic periodontitis who had received no antibiotics for at least 3 months were screened for the presence of beta-lactamase-producing bacteria. Thirteen of the patients harboured beta-lactamase producing bacteria, most of which were members of the genus Bacteroides. The most frequently isolated species were Bacteroides melaninogenicus and Bacteroides capillosus which are often implicated in acute oral infections. All of the beta-lactamase-producing bacteroides strains were sensitive to a combination of amoxycillin with clavulanic acid (Augmentin).

Adult↗
PubMed1990

Dose-dependency of caffeine metabolism with repeated dosing.

Some recent epidemiologic studies have reported a nonlinear dose-response in the relationship between coffee consumption and health risks, such that the risks increase disproportionately to the increase in dose. Assuming caffeine contributes to the adverse health effects of coffee, a possible explanation for the nonlinear dose-response relationship is dose-dependent metabolism of caffeine. We examined the hypothesis that under chronic dosing conditions the metabolism of caffeine is dose-dependent. Nine healthy subjects were given, in randomized 5-day treatment blocks, placebo, 4.2 (low) and 12 (high) mg/kg/day caffeine in decaffeinated coffee, in six divided doses spaced throughout the day. On the third day of each dosing period, 25 mg of stable-isotope labeled caffeine (2-13C, 1,3-15N2) was given intravenously. Clearance of labeled caffeine fell from 0.118 (placebo treatment) to 0.069 (low dose; p less than 0.005) and to 0.54 (high dose; p less than 0.001) L/hr/kg. The formation and metabolite clearances of paraxanthine, the major primary metabolite of caffeine, also decreased comparing the low and high doses (p less than 0.05). We conclude that caffeine metabolism is dose-dependent, resulting in nonlinear accumulation of methylxanthines in the body. Dose-dependent metabolism of caffeine may explain in part why people who drink large amounts of coffee are at greater risk for cardiovascular disease.

Adult↗
PubMed1990

Lack of effect of an inspiratory threshold load on plasma atrial natriuretic peptide levels.

1. After a run-in period, six healthy, recumbent, water-loaded male subjects breathed through an inspiratory threshold load for 90 min. To correct for prolonged recumbency, a similar protocol was followed on a separate control day, but without an inspiratory load. 2. A negative intrathoracic pressure of at least 30 cmH2O was required to overcome the threshold load. 3. Urine was collected every 30 min and analysed for sodium concentration. 4. Plasma samples were collected every 30 min and analysed for atrial natriuretic peptide concentration. 5. The inspiratory load had no effect on urine volume, urinary sodium excretion or plasma atrial natriuretic peptide levels.

Adult↗
PubMed1990

The effect of sub-inhibitory concentrations of chlorhexidine on the proteolytic activity of Bacteroides gingivalis.

Bacteroides gingivalis was grown in the presence of chlorhexidine at concentrations lower than the minimum inhibitory concentration (1.25 mg/l). These sub-inhibitory concentrations were found to stimulate growth in terms of an increase in the number of viable cells, the greatest increase being at a concentration of 0.75 mg/l of chlorhexidine. The total proteolytic activity of the cultures (assayed by means of azocasein hydrolysis) grown in the presence of chlorhexidine and their specific activities (per 10(6) cells) were found to be less than those of the cultures grown in the absence of chlorhexidine. In the case of the trypsin-like activity of the microorganism, a different pattern was found. Thus, although the specific activities of the chlorhexidine-grown cultures were lower than those of the chlorhexidine-free cultures, the total activity in the chlorhexidine-grown cultures was greater.

Bacteroides↗
PubMed1990

Effect of phenoxyethanol, chlorhexidine and their combination on subgingival plaque bacteria.

The effects of phenoxyethanol, chlorhexidine and a mixture of both on subgingival plaque samples from 44 patients with chronic periodontitis were investigated in vitro. At a concentration of 0.5 mg/ml, chlorhexidine inhibited the growth of all cultivable bacteria in all 44 samples while a comparable effect was achieved with phenoxyethanol only at a concentration of 20 mg/ml. All cultivable bacteria in the samples were inhibited by a mixture of the two agents containing 5 mg/ml of phenoxyethanol and 0.125 mg/ml of chlorhexidine i.e. considerably lower concentrations than when the agents were used separately. Kill times for 99.9% of bacteria in 19 of the plaque samples were less than 15 min using a chlorhexidine concentration of 0.125 mg/ml, but were from 24 to greater than 240 min with 10 mg/ml phenoxyethanol. A mixture of the two agents at these concentrations was more effective than either agent alone with 99.9% kill times of less than 10 min. This investigation has shown that the addition of phenoxyethanol to chlorhexidine results in a mixture which is effective against bacteria found in subgingival plaque samples from patients with chronic periodontitis. It also implies that formulations with lower concentrations of chlorhexidine than those currently in use may be effective as adjuncts in the treatment of chronic periodontitis.

Adult↗
PubMed1990

Effect of minocycline on subgingival plaque bacteria.

The effects of minocycline on subgingival plaque samples from patients with chronic periodontitis were investigated in vitro. Minocycline concentrations as low as 1.0 microgram/ml inhibited 95.7% of the cultivable bacteria in the samples but 256 micrograms/ml was necessary to inhibit all of the cultivable bacteria in the samples. Although up to 99.9% of bacteria in the plaque samples were killed by a 6 h exposure to 8.0 micrograms/ml of minocycline, large numbers of viable bacteria remained. These results imply that adequate reductions in the numbers of viable subgingival plaque bacteria are unlikely to occur after exposure to minocycline at concentrations attainable in gingival crevicular fluid after systemic administration.

Adult↗
PubMed1990

An assessment of the accuracy of NovoPen 1 delivery after prolonged use.

Forty-five NovoPen 1 injection devices have been assessed for accuracy of insulin delivery. Twenty-six pen-injectors had been returned either because the device had developed structural faults or the patients had experienced unexpected deterioration in diabetic control. Twelve of these pen-injectors were unusable. The remaining 14 pen-injectors ('faculty pen-injectors') were assessed by measuring the weight of insulin solution delivered in each of 10 depressions of the plunger and compared with similar measurements from 10 unused pen-injectors ('new pen-injectors') and 9 pen-injectors ('used pen-injectors') which had been used uneventfully for greater than 3 years. New pen-injectors delivered insulin solution with an accuracy (median error) of 2.8% and reproducibility (median SD) of 2.0%. Used pen-injectors had an accuracy of 2.3% and reproducibility of 3.5%. The 14 suspect pen-injectors ('faculty pen-injectors') demonstrated an accuracy of 2.8% with reproducibility of 4.0%. The reduction in reproducibility was due to faults in 4 pen-injectors, 2 of which consistently delivered less insulin than expected, while a further two pen-injectors were intermittently inaccurate.

Humans↗
PubMed1990

Is parent-offspring conflict sex-linked? Freudian and Darwinian models.

Freud's Oedipal theory sees parent-offspring conflict as a within-gender rivalry, whereas most modern evolutionary models interpret it as a gender-blind disagreement about resource allocation. New analyses of family homicides and a critical review of prior evidence do not support the central Freudian claim of a same-sex contingency in parent-offspring antagonism during the Oedipal phase. Several errors of fact and interpretation in psychoanalytic theorizing about family relations are discussed. We argue that psychoanalysts mistake substantive conflicts between nonrelatives for symbolic manifestations of family conflicts.

Conflict, Psychological↗
PubMed1990

Mycoplasma in relation to gingivitis and periodontitis.

In this study, mycoplasma were enumerated in the gingival crevicular fluid (GCF) of gingivitis and periodontitis patients. GCF samples were obtained from the mesial (approximal) gingival crevice or periodontal pocket of the maxillary right first permanent molar. Samples were cultured anaerobically on a medium selective for mycoplasmas as well as on a non-selective medium to obtain a total anaerobic count. Mycoplasmas were present in the GCF of both gingivitis and periodontitis patients, but a greater % was obtained from the GCF of patients with periodontitis. The proportions of mycoplasma appeared to be independent of the disease activity as expressed by bleeding on probing (PBI), but to be related to probable pocket depth, as shown by the higher %s in periodontitis than gingivitis for a given PBI. On the basis of an increased proportion in relation to disease severity, mycoplasmas would therefore appear to be amongst those micro-organisms associated with CIPD.

Adult↗
PubMed1990

The assessment of ultrasonic root surface debridement by determination of residual endotoxin levels.

Recent demonstrations of the superficial nature and ease of removal of root-surface-associated cytotoxic materials suggest that extensive root-surface instrumentation is not warranted clinically. This in vitro investigation determined the detoxifying effects of a conservative regime of ultrasonic root debridement, using the Limulus amoebocyte lysate assay for lipopolysaccharide (LPS) as an indication of the presence or absence of cytotoxic materials. 20 extracted periodontally-involved single-rooted teeth, with no clinically detectable calculus deposits, were debrided with a Cavitron TF-10 tip. Light pressure, resulting from a force application of approximately 50 g, lasting for 0.8 s/mm2 of root surface was used and complete overlapping instrumentation ensured. The finding of LPS levels of less than 2.5 ng per root in 19 out of 20 teeth after such debridement was comparable to LPS levels found on healthy, uninvolved control teeth, and thus endorses the growing belief that root surface cleanliness can be readily achieved.

Dental Prophylaxis↗
PubMed1990

The survival of subgingival plaque bacteria in an amine fluoride-containing gel.

Subgingival plaque samples from 20 patients with chronic inflammatory periodontal disease were exposed to a commercial gel formulation containing 2 amine fluorides. The MIC of the gel for these samples ranged from 33 to 260 micrograms/ml with a modal value of 260 micrograms/ml. In each sample, the most resistant organisms (i.e., those organisms surviving at one doubling dilution below the MIC) were identified. 33 such organisms were isolated, of which 22 (67%) were strict anaerobes, and 25 (75%) were Gram negative. The 2 most frequent isolates were Bacteroides ruminicola ss. brevis and a Selenomonas species, neither of which is a recognised periodontopathogen. The gel had a rapid effect on the viability of the bacteria in the plaque samples, the 90% kill time being 17 min or less for 90% of the samples (range less than 5 to 71 min).

Adult↗
PubMed1990

Species-dependent differences in the properties of particulate cyclic nucleotide phosphodiesterase from rat and rabbit ventricular myocardium.

The ability of cyclic nucleotide phosphodiesterases (PDEs) to hydrolyse cyclic (c)AMP in rat and rabbit ventricular myocardium has been compared. The PDE activity of rabbit, but not rat, cardiac homogenate and supernatant fraction was potentiated by Ca2+/calmodulin and attenuated by cGMP. Both rabbit and rat ventricular myocardium were shown to have a membrane bound PDE. However, rabbit membrane-bound PDE was inhibited by cGMP and low concentrations of milrinone (IC50 2.7 microM). In contrast, rat membrane-bound PDE was not inhibited by either cGMP or low concentrations of milrinone (IC50 19 microM), but it was potently inhibited by rolipram (IC50 2.2 microM). Thus, in rabbit the particulate PDE is milrinone sensitive (PDE III) whilst in rat it is the rolipram sensitive (PDE IV) isoenzyme. There are clearly species differences in the intracellular localization and relative activities of PDE isoenzymes in cardiac tissue. This may explain the species differences already found in the activity of selective PDE isoenzyme inhibitors as inotropic agents.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗