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Biomedical subjects

J Boyle

Publications and source records attributed to J Boyle.

At least 37 records · Page 2Linked to original sources
PubMed1988

Microcirculatory hematocrit and blood flow.

Direct measurements from many laboratories indicate that the oxygen tension in skeletal muscle is significantly less than in the large veins draining these tissues. Harris (1986) has proposed that because of the parallel anatomic arrangement of large arterioles and venules in skeletal muscle, a counter-current exchange between these vessels can occur. He theorized that diffusion of O2 between arteriole and venule would lower the PO2 in the blood as it enters capillaries and result in a decreased tissue PO2 and an increase in large vein PO2. Calculations (Appendix) show that the amount of O2 transferred between arteriole and venule is inadequate to account for this difference in PO2 between tissue and veins due to the small surface area that is involved. It is well documented that the microcirculatory hematocrit ranges between 20 and 50% of that in the supply vessels. The reduced hematocrit lowers the oxygen content in these vessels and results in a low oxygen tension in the surrounding tissue. True arteriovenous shunts are not present in most skeletal muscles, but 15-20% of the microvessels represent thoroughfare or preferential flow channels. It is suggested that these vessels contain a greater than normal hematocrit to account for a conservation of red cell mass across the microcirculation. Furthermore, it is shown that the hematocrit in the preferential flow channels is an inverse function of the flow rate for any level of the microcirculatory hematocrit. The increased hematocrit raises the flow resistance in these vessels which reduces flow further and represents a positive feedback condition which may contribute to the intermittent and uneven flow patterns which are present within the microcirculation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Tetanus--a continuing problem in minor injuries.

Tetanus is rare in North America because of highly effective specific immunization programs. Nevertheless, 15 patients with generalized tetanus were treated at the Vancouver General Hospital over a 20-year period; 10 of them were over 50 years of age. Two patients had no injury and 12 had suffered only minor wounds. None had received previous immunization and, even after wounding, prophylaxis was unsatisfactory in all cases. Nine patients required intensive care and two died. Positive cultures were obtained in only two cases. Four recommendations are made to prevent tetanus: (a) all wounds should be considered "tetanus-prone", (b) an accurate history of immunization should be obtained, (c) more attention should be given to prophylaxis at the time of injury and (d) patients should record vaccinations.

Adult↗
PubMed1986

A microcomputer program of pulmonary and tissue gas exchange.

A microcomputer program written in BASIC for the IBM-PC and compatibles has been developed to analyze the effects of many parameters on the gas exchange and transport phenomena in the lungs and the tissues. The program is designed for use by medical students and residents concerned with gas exchange (anesthesiology, pulmonary diseases, critical care, etc.) to study the steady state effects on blood and tissue oxygen and carbon dioxide levels. The present program consists of two main subroutines: Pulmonary Gas Exchange and Tissue Gas Exchange. Steady state gas exchange at the lungs can be studied using either a three-compartment model or V/Q relationships. The V/Q subroutine uses single or multiple populations of V/Q distributions to determine gas exchange using a log-normal distribution of V/Q ratios. Other variables can be adjusted which determine the arterial and mixed-venous blood gases. These values are then fed into the second part of the program to analyze factors which determine tissue O2 tension. The Tissue Oxygen Tension subroutine is also subdivided into a modified Krogh-Erlang model, which provides a three-dimensional plot of theoretical capillary and tissue O2 tensions, and a Piiper model which includes the effect of diffusion shunt on O2 tensions and treats the tissue as a well-stirred compartment. Minimal and maximal tissue O2 tensions are calculated using the Piiper model since the intercapillary distance is allowed to vary depending on the O2 delivery by diffusion. Estimates of blood and tissue O2 tensions, diffusion/perfusion coefficients, amount of O2 delivered and the size of the active capillary bed are summarized in a table.

Computers↗
PubMed1986

Hydroquinone concentrations in skin lightening creams.

Forty-one over-the-counter skin lightening creams were analysed for hydroquinone content, and the accuracy of tables of contents supplied with these products was assessed. Eight of the 41 were found to contain more than 2% hydroquinone, the maximum concentration permitted by the U.K. Cosmetic Products Regulations. Eighteen of these preparations failed to comply with labelling requirements. A list is given of those products containing less than 2% hydroquinone which are adequately labelled.

Consumer Product Safety↗
PubMed1985

Knee rehabilitation following arthroscopic meniscectomy.

Guidelines for knee rehabilitation after conventional open meniscectomy are generally well known. Less agreement exists on rehabilitation following arthroscopic meniscectomy. The program is sometimes arbitrary. Rehabilitation should follow a logical progression regardless of the type of surgery performed. Rehabilitation following knee surgery can be divided into four phases: immediate post-operative period, early healing phase, late healing phase, and conditioning for return to preinjury activity. Following arthroscopic surgery, the overall recovery time can be significantly shortened compared to conventional arthrotomy, primarily by decreasing the length of the early postoperative phases. A smaller incision causes less soft-tissue injury to skin, capsule, synovium, and other periarticular structures, resulting in less quadriceps inhibition and a more rapid recovery. The rate of tissue healing is not altered, however, and the knee must still heal completely before the patient can return to a full functional level. Not all patients are rehabilitated uniformly, and a great deal of variability exists following arthroscopic surgery. Factors that affect the speed of rehabilitation and return to normal function are the extent of meniscectomy performed, the coexistence of additional intra- or extra-articular pathology, and individual patient differences. Therefore, an arbitrary time frame for rehabilitation following arthroscopic meniscectomy is not recommended. Rather, each patient should progress from one stage of rehabilitation to the next, based on objective knee findings.

Arthroscopy↗