Calculation vs calibration curve for INR determination. Results of an interlaboratory proficiency scheme.

We surveyed 271 laboratories participating in a quality assessment program to ascertain whether the use of a calibration curve for determining the international normalized ratio (INR) would improve interlaboratory accuracy and precision. Lyophilized warfarinized samples with INR values assigned through manual calibration against internationally assigned rabbit reference thromboplasts were assayed for prothrombin time. Calibration analysis on the results was performed by linear regression.

Coordination of breathing and swallowing: effects of bolus consistency and presentation in normal adults.

Respiration and swallowing were recorded simultaneously by inductance plethysmography, submental electromyography, and a throat microphone in 10 normal subjects during eating and drinking tasks that included single boluses of varying volume (5-20 ml) and consistency presented with a syringe and cup, a 200-ml drink taken with and without the use of a straw, and a sandwich meal. Swallows were associated with a brief swallow apnea (SA) lasting approximately 1 s. Swallow effects on the duration or tidal volume of the preswallow, postswallow and swallow-associated breathing cycles varied depending on bolus characteristics and presentation.

Student placements in administration.

From 1988-1993 the Occupational Therapy Manager at St. Joseph's Health Centre in London, Ontario provided nine block placements with a major focus in administration. The administration placements and the results of a questionnaire completed by the students are discussed.

A cosine modulation artifact in modulation transfer function computations caused by the misregistration of line spread profiles.

Modulation transfer functions (MTFs) are used to analyze the spatial frequency transfer characteristics of medical imaging systems. By definition, accurate MTFs should not include the effects of image noise and they should not be aliased. Therefore, many techniques used to compute MTFs register and average together multiple profiles to improve both signal to noise and/or eliminate aliasing.

Quantification of myocardial blood flow and extracellular volumes using a bolus injection of Gd-DTPA: kinetic modeling in canine ischemic disease.

In order to clarify the relationship between coronary artery disease (including myocardial infarction) and image contrast in gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA)-enhanced MRI it was decided to model the myocardial tissue distribution and clearance of Gd-DTPA using the modified Kety equation. Using a canine model, myocardial tissue Gd-DTPA concentrations ([Gd-DTPA]m) were measured 1 or 5 min after a bolus injection of Gd-DTPA or immediately after the end of a constant infusion of Gd-DTPA in a total of 35 dogs. It was found that within 5 min of a bolus injection [Gd-DTPA]m is determined primarily by myocardial blood flow (MBF) and after about 10 min primarily by myocardial extracellular volumes (MECV).

Loosening of cementless femoral stems: a biomechanical analysis of immediate fixation with loading vertical, femur horizontal.

Large joint implants must have immediate fixation to be successful. Unfortunately, the magnitude and consistency of achieving this remains largely unknown. For cementless femoral components it is being increasingly appreciated that torsional loading as occurs during stair climbing or rising from a chair leads to loosening and thigh pain in some cases.

Arachidonic acid release from cultured human amnion cells: the effect of dexamethasone.

Glucocorticoids inhibit prostaglandin (PG) synthesis in several cell types, presumably by inhibiting arachidonic acid (AA) deacylation from phospholipids. We studied the effects of glucocorticoids on cultured term human amnion cell AA release. Confluent monolayer cultures of amnion cells were adapted to serum-free medium, and phospholipids were labeled for 18 h with [14C]AA.

Dexamethasone stimulates arachidonic acid conversion to prostaglandin E2 in human amnion cells.

The purpose of this investigation was to study the mechanism of stimulation of PGE2 output from human amnion epithelial cells by the synthetic glucocorticoid dexamethasone. Cells incubated in serum-free pseudo-amniotic fluid produced very low levels of PGE2, even when arachidonic acid (1 microM) was present. Pretreatment of cells with dexamethasone (50 nM) for 21 h increased the PGE2 output 6- to 7-fold in 2-h incubations only in the presence of arachidonic acid.

Production of prostaglandins by fetal rat lung type II pneumonocytes and fibroblasts.

The output of prostaglandins I2, E2, F2 alpha and 13,14-dihydro-15-keto-PGF2 alpha (PGFM) from third passage day 20 rat fetal fibroblasts and type II alveolar pneumonocytes was studied. In 2 h incubations, the output levels for each cell type were: PGI2 greater than PGE2 much greater than PGF2 alpha = PGFM when cells were incubated with Ca2+ ionophore A23187 (10 microM) or arachidonic acid (1 microgram/ml).

An audit of blood component therapy in a Canadian general teaching hospital.

As part of a quality assurance program a retrospective audit of transfusion practices for packed red blood cells, fresh frozen plasma and albumin was undertaken with predetermined criteria in a general teaching hospital. Of 520 transfusion episodes with 1218 units of packed red blood cells given to 297 patients 88% were considered appropriate; of 106 episodes with 405 units of fresh frozen plasma given to 83 patients 90% were deemed appropriate; and of 187 episodes with 320 units of albumin given to 99 patients 64% were considered appropriate. The results of this audit, when compared with those of other surveys of blood use in a similar population, suggest that pretransfusion approval of requested components would reduce the number of inappropriate transfusions.

Glucocorticoids stimulate prostaglandin synthesis in human amnion cells by a receptor-mediated mechanism.

Prostaglandin E2 (PGE2) synthesis by human amnion increases with the onset of labor and is thought to participate in the initiation and maintenance of parturition. Since cortisol levels increase in amniotic fluid in late pregnancy, we studied the effects of glucocorticoids on cultured term human amnion cell PGE2 output. In 24-h studies, the synthetic glucocorticoid dexamethasone stimulated basal PGE2 output 2-fold over control levels at 16-500 nmol/L.

The action of epidermal growth factor on human amnion prostaglandin E2 output.

The mechanism of stimulatory action of epidermal growth factor on term human amnion prostaglandin E2 production was studied. Monolayer cultures of amnion epithelial cells from spontaneous vaginal deliveries were preincubated for 24 h with serum-free media and treated with epidermal growth factor, calcium ionophore A23187 (4.5 microM), and arachidonate.

Risks and benefits of elective hip replacement in the octogenarian.

We reviewed the records for 100 consecutive cases of elective hip replacement in 91 patients in their 80s (average age 82.8 years), all of whom lived in their own homes before surgery. In 92 cases the patients returned home, 59 within 3 weeks.