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Biomedical subjects

A Stokes

Publications and source records attributed to A Stokes.

52 records · Page 3Linked to original sources
PubMed1980

Antimicrobial effects of trimethoprim and sulphadiazine in infected urine and blood.

Sulphadiazine and trimethoprim in a wide range of concentrations were added to urine from patients with untreated urinary-tract infections. At therapeutic concentrations, the antibacterial activity of trimethoprim was not increased by the addition of sulphadiazine. Exposure of Escherichia coli to trimethoprim in urine was not associated with an increase in resistance to that agent. It was also not possible to select, in vitro, stable resistance to trimethoprim in sensitive cultures of E. coli. At therapeutic levels in blood, trimethoprim and sulphadiazine singly produced mainly a bactericidal action on pathogens responsible for urinary-tract infections. Sulphadiazine occasionally enhanced the effect of trimethoprim at subtherapeutic levels. These findings support the need for further evaluation of trimethoprim alone, rather than its use as a combination with a sulphonamide.

Bacteriuria↗
PubMed1979

Studies on recently isolated cultures of methicillin-resistant Staphylococcus aureus.

Of 19 recently isolated cultures of methicillin-resistant Staphylococcus aureus, 18 showed inducible low-level resistance to minocycline, 15 showed high-level resistance to streptomycin, and 4 showed resistance to low levels of streptomycin. Two cultures produced yellow pigment and may have been derived in vivo by loss of a gene(s) determining orange pigment. Treatment of three cultures with serial exposures to N-methyl-N'-nitro-N-nitrosoguanidine resulted in a widening of phage typing pattern that included all reactions in group I, the great majority in group III, but none in group II. The widening in phage lysis was possibly due to the elimination of defective prophages. Transfer of tetracycline resistance occurred from 12 out of the 19 cultures to a recipient in mixed culture; this transfer required either Ca2+ or Mg2+, was abolished by citrate, and enhanced by high cell density. It was probably mediated by defective bacteriophages. No evidence was obtained for the occurrence of recombination within the methicillin-resistant clone in nature. Eleven methicillin-resistant cultures stored for at least 5 years on agar slopes at 20 degrees C had all lost this resistance at high frequency.

Anti-Bacterial Agents↗
PubMed1978

Effect of thymidine on activity of trimethoprim and sulphamethoxazole.

Thymidine at levels as low as 0.05 mg/1 reduces the activities of sulphamethoxazole and trimethoprim and their combination in vitro. Using a biological assay procedure, levels of thymidine greater than this were interpreted as being present in urine. The addition of sulphamethoxazole and trimethoprim, singly or in combination, to urine obtained from patients with urinary tract infections showed that all the antibacterial effect towards sensitive organisms was due to the trimethoprim component. It is suggested that trimethoprim should replace the combination co-trimoxazole for the treatment of some lower urinary tract infections, and that laboratory media, if they are to resemble the clinical environment, should contain thymidine.

Bacteriuria↗
PubMed1977

Susceptibility of the "penicillinase-resistant" penicillins and cephalosporins to penicillinase of Staphylococcus aureus.

The activities of some semisynthetic penicillins and cephalosporins have been tested against clinical strains of Staphylococcus aureus. The apparent activity in vitro varies with the method of testing used. Determination of MICs using light inocula fails to detect the destructive effect of penicillinase on the antibiotic. This was, however, demonstrated reproducibly by the use of a technique in which a heavy inoculum was pre-incubated for two hours before application of antibiotic to wells. This method of testing probably represents most of the clinical situations in which the drugs are used since both in vitro and in vivo a growing culture is exposed to an antibiotic gradient. Flucloxacillin was inactivated by penicillinase considerably more than either methicillin, cloxacillin, or nafcillin. Cephaloridine was the most vulnerable of the cephalosporins. Cephazolin, cephalothin, and cephalexin were intermediate. Cephradine was the least hydrolysed by staphylococcal penicillinase. It is recommended that the activities of all penicillins and cephalosporins against staphylococci should be tested by diffusion at 37 degrees C with pre-incubation of the culture for two hours at this temperature.

Cephalosporins↗
PubMedDate not supplied

Adaptation of finger-smoothed irreversible hydrocolloid to impression surfaces.

This study investigated a surface moistening technique in which the surface of an irreversible hydrocolloid impression material was smoothed using a moistened, gloved finger prior to impression making. To determine the effect of the procedure on the surface integrity of machined brass die, impressions with and without smoothed surfaces were made and examined. Similarly, multiple impressions were made for a single dentate subject, and stone casts were poured. These casts were assessed by three experienced clinicians. Results indicated that the moistened finger technique resulted in fewer surface bubbles and voids than did impressions made when the material was only loaded with a spatula and not smoothed.

Alginates↗
PubMedDate not supplied

Blood pressure control with diltiazem XR, a novel extended-release formulation of diltiazem HCl, in mature and elderly hypertensive patients.

The safety and efficacy of an extended-release form of diltiazem HCl (diltiazem XR) in patients 55 years or older with mild-to-moderate essential hypertension were examined in a multi-center, double-blind, randomized, placebo-controlled, parallel-group study involving 350 patients with supine diastolic blood pressure (DBP) between 95 mm Hg and 114 mm Hg. Patients were randomized to a once-daily dose of diltiazem XR (240 mg) or placebo; 261 patients received diltiazem XR and 89 received placebo. After 4 weeks, the dose was doubled (to 480 mg) in patients whose supine DBP was > 90 mm Hg, and treatment was continued for another 4 weeks. Diltiazem XR consistently reduced blood pressure (BP) in the study population. At end-point, the mean reduction in supine DBP was 8.65 mm Hg in the diltiazem XR group and 2.75 mm Hg in the placebo group (P < 0.0001). Subgroup analysis confirmed the efficacy of diltiazem XR in men, women, patients between the ages of 55 and 64 years, patients 65 years or older, and non-black patients. Other BP values (supine systolic, standing diastolic, and standing systolic) also were significantly reduced in patients treated with diltiazem XR. BP reduction (supine DBP < or = 90 mm Hg or by > or = 10 mm Hg) was achieved in 58% of patients receiving diltiazem XR compared with 27% of patients receiving placebo. Decreases in apical heart rate were minimal and similar in both groups. No significant differences were noted in adverse events in the diltiazem XR and placebo groups: 36.4% of patients in the diltiazem XR group and 37.1% in the placebo group had no adverse experiences, and 63.6% and 62.9%, respectively, had at least one adverse event. Physical examination findings and laboratory values were clinically unremarkable and comparable in the diltiazem XR and placebo groups. Diltiazem XR given once daily at doses of 240 mg and 480 mg was safe and effective in lowering blood pressure in mature and elderly patients with mild-to-moderate hypertension.

Aged↗