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Biomedical subjects

M O'Brien

Publications and source records attributed to M O'Brien.

107 records · Page 6Linked to original sources
PubMed1975

Automated spectrophotometric assay of cefazolin.

An automated, stability-indicating, UV spectrophotometric assay for cefazolin is presented. The method employs a reaction with hydroxylamine and derives its stability-indicating power through comparison of reacted and unreacted aliquots of the sample. A double-probe sampling procedure is used. Good agreement with microbiological assays is obtained, and the coefficient of variation is about 1%.

Autoanalysis↗
PubMedDate not supplied

Anti-Kell (K1) in idiopathic thrombocytopenic purpura.

A transiently occurring anti-Kell antibody was observed in a 2 1/2-year-old child who had idiopathic thrombocytopenic purpura after recovery from an upper respiratory tract infection. The antibody was probably of the IgM class. There was no history of prior blood transfusion.

Agglutination Tests↗
PubMedDate not supplied

Association of bone mineral density and pediatric fractures.

Bone mineral density in the lumbar spine and the left femoral neck was measured for a group of 17 children, 3-14 years of age, who had sustained traumatic fractures. Children with any signs of metabolic bone disease were excluded from the study. Identical measurements were made on an age- and sex-matched control population using dual photon absorptiometry. Analysis of bone mineral measurements revealed that there were no statistically significant differences between the lumbar and femoral neck densities of the two groups. The results indicate that reduced bone density is unlikely to play a significant role in acute traumatic pediatric fractures.

Adolescent↗
PubMedDate not supplied

Performance and clinical use of a convertible hemodialysis (HD) - ultrafiltration (UF) system.

A hemodialysis-ultrafiltration system has been developed and evaluated. It may be used either as a conventional hemodialyzer or as a nondialytic ultrafilter. When used as a dialyzer an ultrafiltration controller is required to fix ultrafiltration rate at the desired level. Rates of low molecular solute removal are compatible with those observed in commercially available artificial kidney systems, higher clearances are obtained for middle molecules, and the rate of ultrafiltration can be controlled within narrowly prescribed limits.

Blood Flow Velocity↗
PubMedDate not supplied

Mean flow velocity in the right common carotid artery before and after maximal exercise.

The effect of exercise on mean flow velocity (MFV) in the right common carotid artery (RCC) was studied using pulsed Doppler ultrasound. MFV was measured at rest and at 2 minutes intervals after a 6 minute rowing ergometer test. Age-related maximum heart rate of 190 +/- 10 beats.min-1, maximum respiratory rate of 60 +/- 5 breaths.min-1, and postexercise lactate level of greater than 8 mmol.l-1 were the criteria used to define maximal exercise. The control group comprised 13 healthy, active males, mean age 19.8 years, with 19 healthy oarsmen, mean age 19.9 years, in the exercise group. At rest, MFV in the RCC was found to be 18.6 +/- 5.6 and 16.4 +/- 6.3 cm.min-1 in the control and exercise groups respectively. After exercise, MFV decreased to 21% of its resting value and remained significantly reduced (posthoc tests, Newman Keuls at alpha = 0.01) until 14-16 minutes of recovery. Mean systemic arterial pressure (MSAP) remained within normal limits. Mean age-related maximum heart rate was 182 +/- 3 beats.min-1, respiratory rate 58 +/- 3 breaths.min-1, and postexercise serum lactate 20.2 +/- 3.5 mmol.l-1 which satisfied the criteria for maximal exercise. In this group of young males, MFV in the RCC decreased markedly after maximal exercise and remained significantly reduced for a long period. This sustained reduction in MFV has not previously been described and is most likely due to vasoconstriction in distal cerebral resistance arterioles mediated by hypocapnia and autonomic activity.

Adult↗