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Biomedical subjects

R B Taylor

Publications and source records attributed to R B Taylor.

At least 19 recordsLinked to original sources
PubMed1992

Prophylactic use of apraclonidine for intraocular pressure increase after Nd:YAG capsulotomies.

We evaluated the prophylactic effect of 1% apraclonidine HCl in controlling the increase in intraocular pressure after Nd:YAG posterior capsulotomy in a large, multicenter double-masked clinical trial. One hundred sixty-four patients were enrolled into the apraclonidine-treated group, and 165 into the vehicle-treated group. The incidence of increase in intraocular pressure (greater than 5 mm Hg) in the apraclonidine-treated group (7%, 11 of 163 patients) was significantly less than that in the vehicle-treated group (39%, 64 of 164 patients). Similarly, the mean maximal change in intraocular pressure in the apraclonidine-treated group (1.3-mm Hg decrease) was significantly different from the increase in the vehicle-treated group (5.3-mm Hg increase). Few adverse reactions were observed. The risk for significant loss of visual function after Nd:YAG laser posterior capsulotomy, combined with the efficacy and relative safety of prophylactic apraclonidine, suggest its addition to the treatment armamentarium.

Adrenergic alpha-Agonists↗
PubMed1992

Simultaneous determination of some antibacterial drugs in isosensitest broth using high-performance liquid chromatography with solid-phase extraction.

A method is described for the simultaneous determination of combinations of some antibacterial drugs in a matrix of isosensitest broth. A double solid-phase extraction procedure is described in which trimethoprim and dibromopropamidine isethionate together with 4-chlorophenylbiguanide as internal standard are freed from endogenous components by a cation-exchange extraction cartridge and subsequently removed and individually separated by reversed-phase ion-pair chromatography. Sulfadiazine, sulfamerazine and p-aminobenzoic acid, unretained by ion exchange, are similarly isolated for chromatography by adsorption on a CH-bonded phase cartridge and individually assayed using the same chromatographic system. The rationale of the pre-treatment and chromatography is described and the quantitative aspects of the analyses of selected combinations of these drugs are reported.

4-Aminobenzoic Acid↗
PubMed1992

Spinal stimulation to locate preganglionic neurons controlling the kidney, spleen, or intestine.

The organization of sympathetic preganglionic neurons may be a substrate for selective control of sympathetic outflow to different vascular beds. This study was done to determine the spinal segments containing preganglionic neurons controlling discharge of renal, splenic, and mesenteric postganglionic nerves. In urethan-anesthetized rats, preganglionic neurons were stimulated by microinjecting D,L-homocysteic acid (3 nl, 0.17 M) into the lateral gray matter of the third thoracic (T3) to the fourth lumbar (L4) spinal segments. Responses from all three nerves could be elicited from segments T4-T13. The greatest increases in renal nerve discharge were evoked from segments T8-T12, the largest increase of 59 +/- 9% elicited from T10. Increases in splenic and mesenteric nerve discharge were smaller and were evoked more uniformly from T4-L3. The largest increases in discharge of splenic and mesenteric nerves were 19 +/- 5% (from T5) and 26 +/- 4% (from T10), respectively. The widely overlapping spinal cord segments controlling these three organs suggest that location of the preganglionic neurons in different spinal segments is not part of the mechanism for selective sympathetic control. However, the larger renal nerve responses demonstrate that sympathetic output to these organs can be differentiated at the level of the spinal cord.

Animals↗
PubMed1991

Determination of teicoplanin in plasma using microbore high-performance liquid chromatography and injection-generated gradients.

A reversed-phase isocratic high-performance liquid chromatographic method for the determination of total teicoplanin in plasma is reported. The method developed uses a bracketing injection technique in conjunction with large injection volumes on a 1 mm diameter column to form a limited injection-generated gradient. The chromatography yields adequate resolution among all the major components for individual quantitation and also allows quantitation of total teicoplanin in plasma using ultraviolet detection. Pretreatment is by solid-phase extraction which uses C8 Bond Elut cartridges and gives effective clean up from endogenous materials. The method offers a faster and simplified means to determine total teicoplanin in plasma than those previously reported, and has a detection limit of 50 ng/ml.

Anti-Bacterial Agents↗
PubMed1991

An evaluation of the antibacterial activities of combinations of sulfonamides, trimethoprim, dibromopropamidine, and silver nitrate compared with their uptakes by selected bacteria.

Modifications of antibacterial activity have been demonstrated using combinations of two antibacterials from trimethoprim, sulfonamides (sulfadiazine, sulfamerazine, and silver sulfadiazine), silver nitrate, and dibromopropamidine isethionate, either formulated in a cream base or dissolved in peptone water. The creams were evaluated using the agar cup diffusion method in isosensitest agar. The peptone water solutions provided fractional inhibitory concentrations for combinations of the antibacterial substances. The test organisms were Pseudomonas aeruginosa, Enterobacter cloacae, and Staphylococcus aureus. Bacterial uptakes of antibacterial combinations, determined by either an HPLC assay method or an atomic absorption method, combined with dry cell weight determinations, indicated that enhancement of activity of the antibacterial combinations against P. aeruginosa (two strains) and E. cloacae were related to marked increases in the bacterial uptake of the chemical agents. Decreases in activity were related to decreased uptake of either dibromopropamidine and/or silver ions. The effect of the trimethoprim and the sulfonamides was shown to depend on their effect on bacterial folate synthesis. It is suggested that partial blockade of the folate synthetic pathway leads to an effect on cell permeability which results in increased uptake of antibacterials. Dibromopropamidine isethionate also has an effect on cell permeability which produces an increased bacterial uptake of a second antibacterial present in the medium. These findings provide further explanation of how subinhibitory concentrations of trimethoprim and sulfonamide combinations are synergistic against a wide range of bacteria even when certain bacteria are resistant to either member of the combination.

Bacteria↗
PubMed1990

Bovine gamma globulin-specific CD4+ T cells are retained by bovine gamma-globulin-tolerant mice.

Immunological tolerance is an acquired state of antigen-specific nonresponsiveness which is generally attributed to either the deletion or suppression of tolerogen-specific T helper cell clones. Unresponsiveness to xenogeneic immunoglobulins can be readily induced and has been extensively studied in order to ascertain the means by which tolerance is established and maintained. As an absence of reactivity to foreign immunoglobulin has been noted in situations where suppressor cell activity was minimized, this tolerant state has often been ascribed to clonal deletion. The present study demonstrates that bovine gamma-globulin (BGG)-tolerant mice are unable to generate humoral responses to BGG in vivo and yet harbor BGG-specific CD4+CD8- T cells which can divide and secrete interleukin 2 when stimulated in vitro. Indeed, the in vitro reactivity to BGG of these cells exceeded that of a similar population of non-immune cells. This is in direct opposition to the loss of response that would be expected if clonal deletion were operative. The presence of BGG-specific CD4+ T cells, which appear to be at least partly primed, in mice unresponsive to BGG, indicates that tolerance to BGG is likely to be dependent on unidentified immunoregulatory processes rather than clonal deletion.

Animals↗
PubMed1990

Measurements of human bioluminescence.

In measuring the output of light from the human skin, we estimated the total photon rates to be of the order of 170-600 photons/s/cm2, depending on anatomical location. The light was strongest at the red end of the spectrum, but fell below detectable levels in the ultraviolet. Significant variations were observed between individuals in both photon rate and spectral profile. The photon rate also varied significantly with time for a single individual. The possible source of this light and its significance are discussed.

Equipment Design↗
PubMed1990

Patient profiling: individualization of hypertension therapy.

Although the stepped-care approach remains the cornerstone of antihypertensive therapy, the patient's profile must also be considered. Important issues include the patient's age, race and activity level, potential for hypertensive complications, presence of other diseases, cost of medications and probability of adherence to the recommended drug regimen. Nonpharmacologic treatment based on lifestyle changes is a useful adjunct to drug therapy, but it is not sufficient to control hypertension in most patients. Selection of pharmacologic therapy must be based on a knowledge of each drug's mode of action and side effects, as well as the characteristics of special patient populations.

Adrenergic beta-Antagonists↗
PubMed1979

Low avidity as a cause of prozone phenomena.

The incidence of prozones was studied, under various conditions, in a model indirect haemagglutination system and in a radioimmunoassay--both assays depending on the use of anti-immunoglobulin (anti-Ig). It was found that prozones were correlated with the presence of low avidity antibodies, and that these could compete with high avidity antibodies for the limited amount of anti-Ig available. It is proposed that the relatively rapid dissociation of low avidity antibodies allows them to form immune aggregates with the anti-Ig. With increasing size these aggregates would become more susceptible to being washed off. In this way low avidity antibodies could occupy the anti-Ig, and yet be relatively ineffective, either for haemagglutination or for the binding of radioactively labelled (or fluorescein-labelled) anti-Ig to the antigen.

Animals↗
PubMed1979

Hypertensive crisis possibly due to drug interaction.

This report describes a case of possible drug interaction in a patient taking chlorpromazine and guanethidine who experienced a hypertensive crisis following initiation of doxepin therapy. (We have been unable to find a report of a similar interaction at the doses described.) It is advised that physicians exercise caution when contemplating concomitant use of doxepin and guanethidine, even in usually recommended doses.

Blood Pressure↗
PubMed1979

Family behavior modification.

Behavior modification has been effective in dealing with problems in individual patients. The adaptation of behavior modification techniques to the family unit can help to lessen some harmful consequences of adverse human behavior. After identification of the problem and analysis of the stimuli, the behavior and its consequences, stimulus control and contingency management are discussed. A formal written contract, involving all family members and the physician, is useful.

Adolescent↗
PubMed1979

Family: a systems approach.

The family is a social system with elements of structure, bonding, boundaries and function. The person and the dyad are the building blocks (subsystems) of the family. A systems approach allows the family physician to elucidate specific areas of disruption, describe problems in terms of family elements and intervene at the appropriate hierarchic level to promote optimum health to family members.

Adult↗
PubMed1978

Use of HPLC to determine the effect of 17 beta-hydroxy-7 alpha-methylandrost-5-en-3-one (RMI 12,936) on production of progesterone by rat ovarian homogenate.

A new high presure liquid chromatography (HPLC) method for the determination of progesterone in the presence of other delta 43-ketosteroids is described. Using this method it is shown that the rate of production of progesterone from pregn-5-ene-3,20-dione by rat ovarioan homogenate is initally rapid but falls to zero within 10 min. Experiments indicate that the inhibition is due to the progesterone formed. Inclusion of RMI 12,936 with the pregn-5-ene-3,20-dione substrate results in a lower final level of progesterone and continuous production of 7 alpha-methyltestosterone. The reduction in the levels of progesterone in presence of RMI 12,936 corresponds closely to the reduction in plasma progesterone in vivo folowing administration of RMI 12,936 described previously.

Androstenols↗