Search PubMed⌕ Search

Biomedical subjects

S Cousins

Publications and source records attributed to S Cousins.

28 records · Page 2Linked to original sources
PubMed1982

Increased platelet volume in diabetic retinopathy.

Platelet volume was measured in 30 healthy controls and 87 diabetic patients, the latter subdivided according to the absence, presence and severity of retinopathy, to investigate if platelet size is related to microangiopathy. The platelet volume of the whole diabetic population was increased (p less than 0.05) due to a higher percentage of large elements (p less than 0.05). The patients with various degrees of retinopathy had similar increases (p less than 0.05) in their platelet size, while those without complications occupied an intermediate position between normal controls and retinopathy patients. It is concluded that: (i) increased platelet size accompanies diabetic retinopathy, irrespective of its severity, and (ii) patients without this complication form a heterogeneous group, some of which already have alterations of platelet volume. The role of these abnormalities in the development and progression of diabetic microangiopathy remains to be established.

Adult↗
PubMed1981

Automated platelet counting--a re-evaluation of the sedimentation method.

Platelet counting by means of the Coulter Thrombocounter, using the Thrombofuge method for specimen preparation has been evaluated in order to determine the cause of discrepancies in results obtained in interlaboratory quality assessment surveys. The method was assessed for accuracy, precision, drift and carry-over. When the method was used, as in routine practice, some discrepancies occurred; an important source of error was identified as being due to the level of sedimented plasma layer from which samples are removed. When the method was performed strictly in accordance with the manufacturer's instructions results were generally satisfactory and comparable to those obtained with the whole blood reference method, although, even with this standardized technique, the Thrombo-fuge tended to give higher platelet counts than the reference method with counts above 200 X 10(9)/l. This discrepancy to be independent of PCV, MCV or other identifiable factors.

Blood Platelets↗
PubMed1979

Platelet counting-development of a reference method and a reference preparation.

A reference method has been defined for platelet counting by counting chamber haemocytometry, and a procedure has been developed, using platelet rich plasma (PRP) and a Coulter ZBI counter which provides a reliable, rapid and relatively simple method for platelet counting which is closely comparable to the reference method and can thus be used both as a secondary reference method and a routine method. The optimal method for obtaining PRP from EDTA blood was by augmented sedimentation with Boyum's methyl cellulose-metrizoate mixture at sp. gr. 1.08. This was shown to yield a platelet suspension which reflects closely the platelet content of the original blood. Calibration of electronic counters for platelet counting requires material which is stable and which parallels natural human platelets in size, distribution and other physical characteristics. A suspension of glutaraldehyde-fixed human platelets in glycerol appears to be suitable as a reference preparation. Its method of production is described.

Calibration↗
PubMed1978

Rehabilitation engineering as the crow flies. Part IV--Criteria and constraints.

When engineers function in a biomechanics clinic team, collecting information for the definition and solution of problems, and developing solutions in a logical pattern, then establishment of criteria by which to judge actions and results at various stages are essential. In our procedures, we make the most general statement we can which will indicate the goal we have for the patient or the type of patient being considered. Based on this, we proceed with a breakdown of the goal into increasingly explicit statements keeping the objective in focus. Eventually, with the criteria we need in order to decide "yes or no" to any aspect of the solution developing, we consider the constraints. These we see as imposed by the life-requirements of the patient, the effects of the physical environment, the limitations imposed by the social environment, and the limits of available technology including the skills of the designers, the manufacturing capabilities and the distribution system with which the designers must cope. When a "checklist" of requirements and limits has been established, the "critical eye" watches over the rehabilitation engineer as he in effect watches over himself!

Activities of Daily Living↗
PubMedDate not supplied

Effects of spontaneous gastric hypoacidity on the pharmacokinetics of zidovudine and didanosine.

STUDY OBJECTIVE: To determine the effect of spontaneous gastric hypoacidity on the pharmacokinetics of zidovudine and didanosine in subjects infected with the human immunodeficiency virus (HIV). DESIGN: Controlled, open-label, single-dose, pharmacokinetic study. SUBJECTS: Thirty-two asymptomatic HIV-infected subjects. INTERVENTIONS: Gastric pH studies were conducted in all 32 subjects, and 20 of these subjects (8 women, 12 men) were enrolled into the pharmacokinetic study. They were stratified into two groups according to fasting gastric pH: those without and with gastric hypoacidity (minimum gastric pH < 3 and > or = 3, respectively). Gastric pH was measured using the Heidelberg pH monitoring system in all subjects before and during pharmacokinetic analysis of zidovudine 100 mg or didanosine 200 mg (given as two 100-mg tablets dissolved in 6 oz water). Plasma samples were collected over 8 hours after dosing. MEASUREMENTS AND MAIN RESULTS: Six (20%) of 30 subjects had a minimum gastric pH of 3 or above on at least two occasions, and the remaining 2 had variable gastric pH. Although gastric pH was unchanged during the administration of zidovudine, it increased to greater than 9 in 11 of 12 subjects with didanosine, regardless of baseline value. For both drugs, there were no statistically significant differences in peak plasma concentration (Cmax), time to reach peak plasma concentration (Tmax), elimination rate constant (ke), and area under the plasma concentration-time curve from time zero to infinity (AUC0-infinity) between subjects with and without gastric hypoacidity despite sufficient statistical power to detect a 56% difference in clearance for either drug (alpha 0.05, beta 0.1). CONCLUSION: Gastric hypoacidity occurs in approximately 20% of HIV-infected patients and does not appear to influence zidovudine or didanosine pharmacokinetics.

Acquired Immunodeficiency Syndrome↗