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Biomedical subjects

L A Robinson

Publications and source records attributed to L A Robinson.

At least 91 records · Page 5Linked to original sources
PubMed1984

Creatine phosphate: an additive myocardial protective and antiarrhythmic agent in cardioplegia.

The potential for enhancing myocardial protection by adding high-energy phosphates to cardioplegic solutions was investigated in a rat heart model of cardiopulmonary bypass and ischemic arrest. Creatine phosphate (CP) was evaluated as an additive to the St. Thomas' Hospital cardioplegic solution. Dose-response studies (CP 0 to 50 mmol/L) revealed 10.0 mmol/L as the optimal concentration which improved recovery of aortic flow and cardiac output after a 40 minute period of normothermic (37 degrees C) ischemic arrest from 21.2% +/- 5.4% and 32.8% +/- 4.6% in the CP-free control group to 82.5% +/- 3.7% and 82.6% +/- 4.2% (p less than 0.001), respectively. Creatine kinase (CK) leakage was reduced by 68.7% (p less than 0.001) in the CP group. With hypothermic (20 degrees C) ischemia (240 minutes) and multidose (every 30 minutes) cardioplegia, recoveries of aortic flow and cardiac output were improved from 33.1% +/- 8.4% and 42.2% +/- 7.7% in the CP-free control group to 77.9% +/- 4.2% and 79.6% +/- 4.3% (p less than 0.001), respectively, in the drug group. In addition to improving function and decreasing CK release, CP reduced reperfusion arrhythmias, significantly decreasing the time between cross-clamp removal and return of regular rhythm and also completely obviating the need for electrical defibrillation. 51Chromium-ethylenediaminetetraacetic acid (51Cr-EDTA), an extracellular space marker, was used to study the disappearance of CP from the cardioplegic solution during its stasis in the heart. Upon reperfusion, two thirds of the infused dose appeared unchanged in the coronary effluent; the remainder was either degraded or accumulated by the myocardium. Despite its alleged inability to enter the myocardial cell, exogenous CP exerts potent protective and antiarrhythmic effects when added to the St. Thomas' Hospital cardioplegic solution. Although the mechanism of action remains to be elucidated, it may involve binding or uptake of the drug.

Adenosine Triphosphate↗
PubMed1984

Alopecia areata treated with topical minoxidil.

A 1% minoxidil topical solution was used to treat 48 patients with alopecia areata, ie, 24 patients with patchy disease and 24 patients with alopecia totalis or alopecia universalis. Twenty-five patients had terminal hair regrowth; in 11 of the 25 patients, it was cosmetically acceptable. No clinical features of the disease seemed to indicate the likelihood of hair regrowth. Hair regrowth began approximately two months after the initiation of treatment and was not uniformly well maintained after the treatment was terminated. One patient had an allergic contact dermatitis reaction to the minoxidil solution; no systemic side effects were seen. No notable systemic absorption was found in 18 adult patients. Effects on cutaneous blood flow or the immune system or some direct effect on hair follicles are possible mechanisms by which minoxidil therapy might stimulate hair growth.

Administration, Topical↗
PubMed1983

Effect of written information on physicians' knowledge of drug prices.

Fifty-four residents in internal medicine and primary care medicine were surveyed before and after receiving a prescription drugs price guide booklet to determine whether providing written price information to the residents would improve their knowledge of drug costs. Results indicated that the pricing information did not improve the residents' knowledge of drug costs. It was also found that neither the residents' concern with the importance of drug cost nor their personal assessment of their knowledge of drug cost influenced their incorporation of drug price information into their professional data base.

Arkansas↗
PubMed1983

Isotretinoin in severe, recalcitrant cystic acne: a review.

Isotretinoin, an isomer of retinoic acid, recently has been approved by the Food and Drug Administration for treatment of severe, recalcitrant acne. The most impressive effects include inhibition of sebum production and a reversible decrease in sebaceous gland size. Isotretinoin has proved to be an effective drug; response to therapy has been seen in virtually 100 percent of patients treated. Almost all patients experience reversible cutaneous and mucous-membrane symptoms while on isotretinoin treatment. Other common side effects include conjunctivitis (38 percent) and eye irritation (50 percent). The recommended dosage is 1-2 mg/kg/d for no longer than 16 weeks. Isotretinoin is currently the treatment of choice for severe, recalcitrant acne; however, because of potential side effects associated with retinoids, isotretinoin should be reserved for those patients who are unresponsive to conventional therapy, including topical and systemic antibiotics.

Acne Vulgaris↗
PubMed1982

Comparison of stated and measured patient heights and weights.

Stated and measured patient heights and weights were compared, and the clinical importance of any differences was determined. A total of 112 health-clinic patients were interviewed for height and weight determinations. They were divided into four groups: men 21-35 years old; men 65 years and older; women 21-35 years old; and women 65 years and older. The stated and the actual heights and weights were analyzed for significant differences. Calculations of body surface area (BSA) and basal energy expenditure (BEE) were used to determine the clinical impact of any discrepancies. Patients in all groups tended to overestimate their height, but only the estimates of men differed significantly from the measured values. Differences between stated and measured heights for older women showed statistical differences from younger men and women but not from older men. All groups except young men overestimated their weight. Older men showed the greatest tendency towards overestimation of weight. In elderly men, the calculations of BSA and BEE were significantly different (p less than 0.002) when stated versus measured values were used. These differences were not considered clinically important. Overall, patients in all groups were well aware of their heights and weights.

Adult↗
PubMed1981

Syndrome of congenital internal mammary-to-pulmonary arteriovenous fistula associated with mitral valve prolapse.

Congenital fistulas of the internal mammary artery to the pulmonary circulation are rare, with only 12 patients described in the world literature. Two additional patients are now described who have an associated prolapse of the mitral valve, one of whom had mitral insufficiency. In most instances, the arteriovenous fistula is essentially asymptomatic and is often discovered when a continuous murmur is heard on routine chest examination. The definitive diagnosis is made best by selective arteriography. The embryologic origin of these fistulous communications may be the maldevelopment of accessory bronchial arteries arising from the internal mammary artery. In view of the potential risks of congestive heart failure as well as proximal dilation and degeneration of the parent artery, secondary hypertension, and endocarditis, operative closure of the arteriovenous fistula is recommended.

Adolescent↗
PubMed1981

Effects of oxygen toxicity on regional ventilation and perfusion in the primate lung.

Since the effect of prolonged exposure to high concentrations of oxygen on regional ventilation and perfusion has not been previously, a reproducible primate model of oxygen toxicity was developed to investigate the pathophysiologic changes that occur. Regional ventilation and perfusion were measured by 133Xe techniques in 10 baboons before and after 108 hours of continuous exposure to an inspired oxygen concentration of more than 90%. Arterial blood gases, shunt fraction (QS/QT), cardiac output, physiologic dead space (VD/VT), and pulmonary vascular resistance were also measured. Light and electron microscopic histology confirmed early pathologic changes of oxygen toxicity in every animal after exposure. PaO2 in room air decreased markedly after exposure from 90 +/- 4 to 46 +/- 5 mm Hg, and QS/QT rose to 30 +/- 2%. VD/VT, PaCO2, and pH were not altered by exposure to hyperoxia. Similarly, cardiac output and pulmonary vascular resistance remained unchanged. The distribution of regional ventilation and perfusion remained normal during and after prolonged high-oxygen exposure. Early oxygen toxicity was characterized by profound hypoxemia without regional ventilation-perfusion mismatch. Although impaired diffusion through a thickened alveolar membrane may be partially responsible for this hypoxemia, the markedly increased alveolar-arterial oxygen gradient when FIO2 = 1.0 indicates that shunting at the alveolar level (secondary to absorptive collapse or pulmonary edema) is a major cause of the hypoxemia.

Animals↗
PubMed1980

The effect of methylprednisolone sodium succinate on erythrocyte and haemoglobin function.

1. As it has been suggested that the beneficial effect of methylprednisolone in shock is due to its effect on erythraocyte oxygen affinity, we studied its effect on incubated erythrocytes and on haemoglobin solution. 2. Incubation of fresh whole blood anticoagulated with acid/citrate/dextrose with methylprednisolone (7 mmol/l) produced a significant decrease in oxygen affinity, which was not seen with lower concentrations of methylprednisolone. When either acid/citrate/dextrose blood stored for 10 days or fresh heparinized blood was used, no significant increase in the partial pressure of oxygen at 50% haemoglobin saturation (P50) was demonstrated even with methylprednisolone at 7 mmol/l. At the highest concentration achieved in plasma with standard therapeutic doses (56 mumol/l) there was no increase in P50 under all the conditions studied. 3. Methylprednisolone reduced the oxygen affinity of haemoglobin in solution. The reduction in oxygen affinity was less than that produced by 2,3-diphosphoglycerate and more than that of either sodium succinate or sodium chloride. 4. From the results of this study we conclude that the effect observed in whole cells is probably due to a direct effect of methylprednisolone on haemoglobin. To produce a significant decrease of oxygen affinity of while blood in vitro requires a plasma concentration of methylprednisolone above that obtained in plasma in vivo, with the currently used therapeutic doses.

Cells, Cultured↗
PubMed1980

Assessing readability of patient information materials.

Four readability tests that can be used for evaluating the level of difficulty of patient drug information are described, and instructions for their use are given. Assessment of readability procedures are based on either word and sentence lengths (method 1) or word elimination from a standard list (method 2). The Flesch and Fog formulas (method 1) are suitable for determining readability levels from fifth or fourth grade, respectively, to college. The Fry readability graph (method 1) allows a quick estimation of readability levels between grade 1 and college. The Spache system (method 2), used for children's material, determines readability levels between grades 1 and 3. Using the Flesh formula, the readability levels of 111 patient-oriented brochures and pamphlets were assessed. Only 50% were written at or below the accepted standard of eighth-grade level. To fulfill its function, patient drug information should not exceed the reading level of the intended readers. The described tests provide relatively simple methods for assessing readability levels.

Evaluation Studies as Topic↗
PubMed1979

Clinical pharmacy involvement in geriatric health clinic at a high-rise apartment center.

During an initial 9-week period of involvement in the operation of a health clinic for ambulatory geriatric patients in three high-rise apartment complexes, the activities and opportunities for a pharmacist and pharmacy students were documented. For 120 of the 550 geriatric residents of the center, medication histories were completed during the study period. These 120 patients reported a total of 270 medical problems. They were taking 366 prescription drugs (average, 3.9 per patient). During the 9-week study, 43 drug interactions were documented, and about 25 percent of the patients interviewed complained of some untoward drug effect. The opportunities for pharmacist involvement and the educational opportunities for pharmacy students were demonstrated. The period since the initial 9-week study has shown even greater acceptance and utilization of the pharmacy services, with an increased number of visits by patients.

Ambulatory Care Facilities↗