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Biomedical subjects

M McKenzie

Publications and source records attributed to M McKenzie.

13 recordsLinked to original sources
PubMed1992

Subunit interactions of vesicular stomatitis virus envelope glycoprotein stabilized by binding to viral matrix protein.

The mechanism by which viral glycoproteins are incorporated into virus envelopes during budding from host membranes is a major question of virus assembly. Evidence is presented here that the envelope glycoprotein (G protein) of vesicular stomatitis virus binds to the viral matrix protein (M protein) in vitro with the specificity, reversibility, and affinity necessary to account for virus assembly in vivo. The assay for the interaction is based on the ability of M protein to stabilize the interaction of G protein subunits, which exist as trimers of identical subunits in the virus envelope. The interaction with M protein was shown by using G proteins labeled with fluorescent probes capable of detecting subunit dissociation and reassociation in vitro. The results show that the M protein isolated from virions either as purified soluble protein or as nucleocapsid-M protein complexes interacts with the G protein in vitro and that the reaction is reversible. The interaction between the G and M proteins was not serotype specific, but no interaction between the vesicular stomatitis virus M protein and the influenza virus hemagglutinin could be detected. These results support the conclusion that the interactions described here are the ones that govern assembly of G protein into virus envelopes in vivo.

Fluorescence↗
PubMed1992

Vaccination of Lewis rats against Mycoplasma arthritidis-induced arthritis.

The nature of Mycoplasma arthritidis antigens responsible for eliciting protective immunity in rats was studied by inoculation of rats with mycoplasmal components that had been subjected to a variety of physical and chemical treatments. All inocula tested induced good protection against development of clinical illness, as assessed by changes in body weight and appearance of joint swelling and/or temporary hind limb paralysis. Although all preparations stimulated development in inoculated rats of high titer of antimycoplasmal antibodies measured by ELISA, the complement-fixation antibody response was poor and, in some cases, lacking altogether. This indicated that completion-fixation antibodies may not be involved in protecting rats against M arthritidis-induced illness. Protective antigens were stable to heat (100 C for 10 minutes), formalin, and denaturation by sodium dodecyl sulfate (SDS). Inoculation with membrane and soluble cytoplasmic fractions was protective, as was inoculation with 5 M arthritidis fractions separated according to molecular weight by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). For this latter experiment, rat antisera obtained after vaccination, but prior to challenge exposure, were tested by immunoblot analysis against electrophoretically separated M arthritidis membrane proteins. Interestingly, all antisera from these rats recognized antigens migrating far outside the molecular weight range of the cell fractions with which rats were inoculated. This indicated either that the protective antigens may be composed of numerous antigenically related subunits that separated by SDS-PAGE into a variety of molecular weight ranges or that a few major antigens may exist in several forms or phases within a given population of M arthritidis.

Animals↗
PubMed1991

Wound infections in orthopedic surgery: effect of extended surveillance on infection rate.

Substantial evidence now exists that ongoing surveillance of surgical wound infections can contribute to reduced infection rates. What is not yet determined is whether surveillance should be limited to the postoperative hospital stay or should be continued after patient discharge. To determine the number of infections occurring after discharge, the authors contacted a random sample of their patients who did not have wound infections during their hospitalization after orthopedic surgery. This was done 30 days after the procedure. The authors selected 273 patients of 1375 who underwent orthopedic surgery over a 7-month period and were able to contact 199 (73%). At the 30-day follow-up 23 patients (11.6%) had wound infections, as judged by wound discharge and physician prescription of antibiotics in 20 and the patient's description of pus issuing from the wound in 3. During the same period postoperative wound infections were found in only 19 (1.5%) of 1278 patients who were subjected to in-hospital surveillance. The authors conclude that, in patients who undergo orthopedic procedures, the majority of wound infections occur after discharge from the hospital and that infection rates based only on in-hospital surveillance greatly under represent true surgical wound infection rates for orthopedic procedures.

Alberta↗
PubMed1990

Surgical wound infections occurring in day surgery patients.

The occurrence of surgical wound infection in outpatient day surgery has not been extensively studied despite the increasing popularity of this mode of treatment. The present study was conducted to determine the frequency of surgical wound infections in a day surgery population. We randomly selected during a 6-month period 635 (25%) of 2540 patients undergoing a day surgery procedure in which a skin incision was made. The patients were telephoned 1 month after their procedure by an infection control practitioner. Infection was diagnosed if the patient reported that (1) their physician had made a diagnosis of a wound infection or (2) pus was or had been issuing from the wound. Of the 515 patients contacted, 72% had undergone a clean and 28% a clean-contaminated procedure. Patient risk factors for infection were almost completely absent in our day surgery patients. Twenty-six wound infections were diagnosed, 19 of which were identified by physicians' diagnosis and 7 by patient description, for a rate of 5.05%. Two patients required hospitalization for their infections, and 14 were treated with antibiotics. The clean wound infection rates were 4.62%, less than half the infection rate seen in our patients undergoing inpatient surgery at 1 month follow-up by the same surveillance technique. We conclude that day surgery infection rates are much lower than inpatient surgery infection rates at our facility, probably because of a relative absence of risk factors in the day surgery patients.

Ambulatory Surgical Procedures↗
PubMed1990

Effect of surgeon's diagnosis on surgical wound infection rates.

To determine the impact of a surgeon's diagnosis of surgical wound infections on infection rates, during a 6-month period we prospectively examined patients undergoing surgical wound surveillance for any of four services (orthopedic surgery, general surgery, neurosurgery, or cardiovascular surgery). Criteria were judged as standardized if the infection control practitioner observed pus, redness, or drainage associated with positive culture or if a diagnosis of deep-seated infection was made. Surgeon's diagnosis was judged as a nonstandardized criterion. Using the Centers for Disease Control's criteria, we identified 113 surgical wound infections in 3024 patients undergoing surgical procedures in the four services. Of these, 95 (84%) met objective criteria (pus observed in 53%; drainage, redness, and positive culture in 20%; and deep-seated infection in 11%). In 18 patients (16%), the nonstandardized criterion alone was used for diagnosis. There was wide variation in use of the nonstandardized criterion, ranging from 5% of orthopedic infections to 21% of cardiovascular surgery infections and 40% of neurosurgical infections. For individual surgeons with at least one wound infection, the range of surgeon's diagnosis was up to 67%. We conclude that a surgeon's diagnosis can have a major impact on surgical wound infection rates; this impact is not borne equally among surgical services or individual surgeons.

Alberta↗
PubMed1988

The risk of cytomegalovirus infection in seronegative transfusion recipients not receiving exogenous immunosuppression.

We studied 637 transfusion recipients seronegative for cytomegalovirus (CMV) in the following categories: neonates; pregnant women; and patients experiencing trauma, burns, cardiovascular surgery (adult or pediatric), major surgery, or gastrointestinal hemorrhages. Cultures and serological tests were used to follow up subjects for evidence of CMV infection for a period of three months after their last transfusion. Six (0.9%) developed CMV infection. No significant differences in risk among patient categories were observed. Infected patients received a significantly larger mean number of units of cellular blood products (CBP; 50.0 +/- 38.9 vs. 6.2 +/- 8.5; P less than .001) and plasma (23.7 +/- 15.3 vs. 2.6 +/- 4.6, P less than .001) than did uninfected patients. This result represents a risk per unit of CBP transfused of 0.14%, or approximately 0.38% per unit of seropositive CBP transfused. We observed, however, that patients exposed to CBP from greater than 30 donors had a higher risk of acquiring CMV infection than would be predicted if infectious units were randomly distributed among all donors (P less than .01).

Adult↗
PubMed1988

Bioavailability of a slow-release theophylline capsule given twice daily to preschool children with chronic asthma: comparison with liquid theophylline.

The reliability of slow-release theophylline products in young children has been questioned. Therefore, we studied the bioavailability of a commonly prescribed slow-release theophylline formulation (Slo-Bid Gyrocaps), administered twice daily by sprinkling the beads on applesauce. Serial measurements of serum theophylline concentrations were obtained during steady state in eight children (ages 1.6 to 5 years) after receiving a reference liquid theophylline product every six hours and also while receiving the slow-release product every 12 hours. The morning dose of slow-release theophylline was given before the child had eaten, and the evening dose was given two hours after supper. The extent of absorption of the slow-release product was 98.3 +/- 20.2% (mean +/- SD) relative to the liquid reference. The serum concentration fluctuations, expressed as percentage of the measured trough, did not differ between the two products: 108 +/- 59% v 129 +/- 97% (P greater than .05) for reference and slow-release products, respectively. Three of the eight patients had unacceptably large fluctuations (greater than 100%) while receiving the slow-release regimen, and two of these three had unacceptable fluctuations while receiving the liquid reference. The rate of absorption was slower after the evening dose of slow-release product (postprandial), resulting in significantly smaller fluctuations, and lower peak concentrations. Time to peak concentration while receiving the slow-release regimen varied from two to four hours after the evening dose and from two to eight hours after the morning dose. However, the average difference between the peak concentration and the four-hour measurement after the morning dose was only 0.3 microgram/mL (range 0 to 2.6 micrograms/mL).(ABSTRACT TRUNCATED AT 250 WORDS)

Asthma↗
PubMed1979

Multiple primary prostate cancer.

Although increasing reports are noted of apparent endometrial carcinoma of prostatic origin, the controversy is present of the actual existence of such an entity. The association of papillary prostatic cancer (endometrial or ductal) with the typical microacinar variety has also been previously presented. This report is an account of 2 cases of multiple prostatic primary tumors. The first case is the twelfth reported case of endometrial (utricular) carcinoma not only simultaneously associated with microacinar type carcinoma, but also with a previous transitional carcinoma of the urinary bladder. The second case is a papillary carcinoma and associated microacinar type with the papillary component responding dramatically to chemotherapy. Significant aspects of interest in this case include the site of papillary metastasis to the lungs, elevated estrogen levels with normalization after treatment, and finally response to chemotherapy.

Adenocarcinoma, Papillary↗
PubMed1978

A human plasma component that binds benzo(a)pyrene.

A component capable of binding benzo(a)pyrene was measured in plasma from cigarette smokers and nonsmokers. This plasma fraction was found to have a high specificity of binding to benzo(a)pyrene, bound benzanthracene competitively with benzo(a)pyrene, and was positively correlated (r = 0.861, p less than 0.001) with the capacity of the individual subject's lymphocytes to be induced for AHH activity in culture. An inverse correlation (r = -0.957, p less than 0.001) between the presence of the plasma component in lung cancer patients and the capacity of lung cancer patients' lymphocytes to be induced in culture is unexplained at this time. A benzo(a)pyrene-binding fraction was not found in induced or uninduced cultured lymphocytes from smokers or nonsmokers, or in homogenates of lung excisional tissue from smokers with or without primary lung cancer.

Aryl Hydrocarbon Hydroxylases↗
PubMed1978

Steroid hydroxylase induction in cultured human lymphocytes: effects of the menstrual cycle.

Steroid hydroxylases (SAH) are inducible in cultured human lymphocytes following treatment with estradiol-17beta. The enzyme systems induced are carbon monoxide sensitive and convert estradiol-17beta to a metabolite chromatographically indistinguishable from estriol. The level of inducibility of SAH varies drastically over a normal menstrual cycle with maximum induction in the late follicular phase and minimum induction during the luteal phase. The use of an oral contraceptive containing both a synthetic progestogen and ethynyl estradiol reduced SAH induction levels to those typically seen during the luteal phase of the menstrual cycle.

Cells, Cultured↗
PubMedDate not supplied

Transfusion-acquired cytomegalovirus infection in neonates. A prospective study.

The incidence of cytomegalovirus (CMV) infection was determined in 114 transfused neonates of any birthweight born to CMV antibody-negative mothers. In a second phase of this study, an additional 28 transfused infants weighing less than 1250 g, born to both CMV antibody-negative and antibody-positive mothers, were followed. All infants underwent weekly virus culture and monthly serology during hospitalization and at 6 to 12 weeks after their last transfusion. Only one of 126 (0.8%) seronegative infants and one of 16 (6.3%) seropositive infants developed CMV infection. If the assumption is made that the CMV-infected infant received only 1 unit of infectious blood, the risk of transfusion-acquired CMV infection to seronegative infants is 0.16 percent per cellular unit transfused or 0.37 percent per seropositive cellular unit transfused. Despite similarities in the prevalence of CMV antibody in the donor population, the age of blood products used, and the mean number of donor exposures, a significantly lower incidence of CMV infection was found in the seronegative transfused infants than that in two previously published studies (p less than 0.01, p less than 0.001). Because no mortality and very little morbidity could be attributed to transfusion-acquired CMV infection in the nurseries, the authors can see no justification for the provision of specialized blood components for the prevention of CMV infection in this patient population.

Antibodies, Viral↗