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Biomedical subjects

M J Turner

Publications and source records attributed to M J Turner.

At least 163 records · Page 9Linked to original sources
PubMed1989

Vaginal pH in pregnancy in women delivered at and before term.

A microelectrode was used to measure vaginal pH in a longitudinal study during pregnancy in 30 women, 28 of whom were delivered at term. Excluding pH readings made in the presence of pathogenic organisms, 120 readings were taken. The mean vaginal pH of all subjects was 4.16 (SD 0.41). Analysis of variance showed no significant within-subject variation of pH during pregnancy. Two women had spontaneous preterm deliveries (less than 37 weeks) and their mean vaginal pH during pregnancy was 5.05 and 5.06. Eight women admitted in preterm labour, who then gave birth, had a mean pH of 5.43 (SD 0.94) which was significantly higher than the mean pH of 10 women in labour at term (4.58, SD 0.59). The relation between bacterial growth in vitro and the surrounding pH was also examined. Escherichia coli, a potential pathogen, behaved differently from both Lactobacillus (a commensal organism) and Candida albicans. The clinical observations show a trend towards higher vaginal pH values in association with preterm labour.

Female↗
PubMed1989

Toxigenic type D Pasteurella multocida in New South Wales pig herds--prevalence and factors associated with infection.

Between March and July 1987, a study was undertaken to determine the prevalence of and factors associated with toxigenic type D Pasteurella multocida infection in New South Wales pig herds. Toxigenic type D P. multocida was isolated from the nasal cavities of pigs in one (2%) of 50 randomly selected herds. Toxigenic isolates were also recovered from 2 (8%) of a separate group of 25 herds that had purchased pigs from a known infected piggery in South Australia (herd SA). Snout abnormalities were present in 9.4%, 3.2% and 1.8% of grower pigs in the 3 affected herds. Isolation of toxigenic P. multocida was significantly associated (p less than 0.0001) with the occurrence of clinically affected pigs in the herd. Purchase of at least 5 pigs from herd SA was associated with an elevated risk (p less than 0.05) of isolation of toxigenic P. multocida.

Animals↗
PubMed1989

Effects of temperature and composition on the viscosity of respiratory gases.

The steady-state sensitivity of resistance pneumotachographs is proportional to viscosity. Dynamic characteristics of pneumotachographs, pressure transducers, and mass spectrometers are also viscosity dependent. We derive linear equations to approximate the viscosities of O2, N2, CO2, H2O, He, N2O, and Ar for temperatures between 20 and 40 degrees C by using published viscosity data and a nonlinear extrapolation equation. We verify the accuracy of the extrapolation equation by comparison with published data. Our linear equations for pure gas viscosities yield standard errors less than 0.35 microP. We also compare a nonlinear equation for calculating the viscosities of mixtures of gases with published measured viscosities of dry air, humid air, and He-O2 and N2-CO2 mixtures. The maximum difference between published and calculated values is 1.3% for 10% CO2 in N2. All other differences are less than 0.38%. For saturated humid air at 35 degrees C, a linear concentration-weighted combination of viscosities differs from our nonlinear equation by 4.9, 2.1, and 1.7% at barometric pressures of 32, 83, and 100 kPa, respectively. By use of our method, the viscosity of normal respiratory gases can be calculated to within 1% of measured values.

Argon↗
PubMed1989

Dynamic skinfold measurements to assess fluid status in low birthweight infants. Part 1: Data acquisition and processing.

To evaluate the measurement of fluid status in the premature neonate using dynamic skinfold thickness (DST) measurement, a pair of calipers were interfaced to a computer, and weight and digital DST at four sites were measured daily in 24 neonates in the postnatal weight loss period. A biexponential equation was fitted to each curve from the instant the rate of caliper closure fell below 2 mm/s, and the five constants obtained used in a search for a parameter that correlated with the percentage of weight loss. The percentage of fall in the DST from 0.4 to 30 seconds yielded highest mean of individual coefficients of determination (COD) (0.83); the percentage of fall from 0.7 to 35 seconds yielded highest COD in pooled data (0.56). Expected weight loss can be predicted with standard error of 2.9% with pooled regression but with standard error of 1.3% using individual correlations. We conclude that individuals lose fluid in a consistent manner during this period but that interindividual differences are large and require further investigation.

Algorithms↗
PubMed1989

Dynamic skinfold measurements to assess fluid status in low birthweight infants. Part 2: Correlation with postnatal weight changes.

Computerized recording of dynamic skinfold thickness measurements was performed on low birthweight infants. Four skinfold sites were measured daily for the first 7 days postnatally and then at intervals up to 4 weeks of age. The percentage of fall of the skinfold between 0.4 and 30 seconds after caliper application was shown to correlate best with postnatal weight loss until minimum weight was reached. Of the 24 infants studied in detail, only two had a correlation coefficient less than 0.75 between changes in the percentage of fall of the skinfold and postnatal weight changes. There was, however, marked individual variation in the amount of weight loss for a given reduction in the percent of the skinfold. Assuming that most of the postnatal weight loss of low birthweight infants is due to reduction of extracellular volume, dynamic skinfold thickness appears to be a good noninvasive measure thereof.

Data Collection↗
PubMed1989

Laser vaporization versus laser excision conization in the treatment of cervical intraepithelial neoplasia.

One hundred patients with histologically confirmed cervical intraepithelial neoplasia suitable for ablative therapy were randomly allocated to treatment by either laser vaporization or laser excision conization under local anesthesia in the outpatient colposcopy clinic. The two methods were compared with respect to the immediate surgical complications, ease of performance, and long-term complications. They were comparable in most respects, and both were well accepted by the patients. Laser excision had the added advantage of providing further material for histologic examination to confirm the absence of invasion and the completeness of excision of the lesion.

Adolescent↗
PubMed1989

Contraceptive practices of patients referred for colposcopy with an abnormal cervical smear.

This study examined the contraceptive practices of 100 patients referred for colposcopy because of an abnormal cervical smear. At presentation 49% were using oral contraception but 94% had taken the pill at some time. Eight of the 10 patients using barrier methods were relying on condoms: in at least seven of the eight cases an abnormal cervical smear preceded condom usage. Thus, the method of contraception used when cervical neoplasia develops may differ from the method used when the patient presents for colposcopy. Although consistent with previous studies suggesting that the incidence of cervical neoplasia is increased in women using oral contraception, the risk of neoplasia is more likely to be explained by the degree of exposure of the cervix to an infectious carcinogen or to the immunosuppressive effects of seminal plasma. We suggest that future studies of the epidemiology and natural history of cervical neoplasia should include a detailed contraceptive history.

Adolescent↗
PubMed1989

Fetal survival following coagulopathy at 17 weeks' gestation.

Placental separation in the third trimester of pregnancy may be associated with coagulopathy, fetal distress, or intrauterine death. We report a case of vaginal bleeding due to placental separation at 17 weeks' gestation associated with disseminated intravascular coagulation. After treatment with blood, fresh frozen plasma, and fibrinogen, the pregnancy progressed uneventfully for another 12 weeks, when delivery by emergency cesarean section was performed.

Abruptio Placentae↗
PubMed1988

Crystallization of amino-terminal domains and domain fragments of variant surface glycoproteins from Trypanosoma brucei brucei.

Crystals were produced from variant surface glycoproteins (VSG) of Trypanosoma brucei brucei antigenic variants MITat 1.2, 1.6, and ILTat 1.22, 1.23, 1.24, 1.25, and 1.26. Purified VSGs had molecular weights from 60,000 to 68,000 on sodium dodecyl sulfate-polyacrylamide gels, whereas the crystals obtained were composed of polypeptides of approximate Mr 40,000-50,000. Amino-terminal amino acid sequences determined from the crystallized VSGs were identical to sequences obtained from the respective intact proteins, indicating that the crystals contained VSG amino-terminal fragments. Crystallization conditions and lattice dimensions of the crystals are given.

Animals↗
PubMed1988

Topologic analysis of the epitopes of a variant surface glycoprotein of Trypanosoma brucei.

A panel of variant-specific mAb has been raised against the Trypanosoma brucei variant MITat 1.2. The binding characteristics of these mAb have been determined by a combination of immunofluorescence assays, using living or fixed trypanosomes, and solid phase assays, using purified variant surface glycoprotein. In addition, these mAb have been tested for their ability to neutralize MITat 1.2 infections in mice. Finally, the epitopes recognized by the mAb have been defined by competitive binding assays. These results are discussed with respect to the structural organization of the surface coat of T. brucei.

Animals↗
PubMed1988

Partial characterization of the cross-reacting determinant, a carbohydrate epitope shared by decay accelerating factor and the variant surface glycoprotein of the African Trypanosoma brucei.

The variant surface glycoprotein (VSG) of the African trypanosome is anchored in the cell membrane by a complex glycan attached to phosphatidylinositol. The carboxyl terminal portion of VSG contains a cryptic carbohydrate epitope, the cross-reacting determinant (CRD), that is revealed only after removal of the diacylglycerol by phosphatidylinositol-specific phospholipase C (PIPLC) or VSG lipase. Recently, we have shown that after hydrolysis by PIPLC, decay-accelerating factor (DAF)--a mammalian phosphatidylinositol-anchored protein--also contains the CRD epitope. Using a two site immunoradiometric assay in which the capturing antibody is a monoclonal antibody to DAF and the revealing antibody is anti-CRD, we now show that sugar phosphates significantly inhibited the binding of anti-CRD antibody to DAF released by PIPLC. DL-myo-inositol 1,2-cyclic phosphate was the most potent inhibitor of binding (IC50 less than 10(-8) M). Other sugar phosphates, such as alpha-D-glucose-1-phosphate, which also possess adjacent hydroxyl and phosphate moieties in cis also inhibited binding at low concentrations (IC50 = 10(-5) to 10(-4) M). In contrast, sugar phosphates which do not possess adjacent hydroxyl and phosphate moieties in cis and simple sugars weakly inhibited binding (IC50 greater than 10(-3) M). These results suggest that myo-inositol 1,2-cyclic phosphate contributes significantly to the epitope recognized by the anti-CRD antibody and is consistent with analysis of the carboxyl terminus of VSG, which also suggested the presence of the cyclic inositol phosphate. In light of the recent findings that human serum contains a glycan-phosphatidyl-inositol-specific phospholipase D, which converts DAF from a hydrophobic to a hydrophilic form lacking the CRD, the observation that the phosphate is crucial for expression of the epitope may be relevant in understanding the origin of CRD-negative DAF in urine and plasma.

Animals↗
PubMed1988

Identification of an acid-lipase in human serum which is capable of solubilizing glycophosphatidylinositol-anchored proteins.

A lipase has been identified in human serum which can convert the membrane form of the variant surface glycoprotein of Trypanosoma brucei to a water soluble form. The conversion can be monitored by loss of [3H] myristic acid incorporated into the diacylglycerol of the glycophosphatidylinositol membrane anchor of the protein, but does not lead to the exposure of the antigenic determinant in the polar head group of the glycolipid. The serum lipase is a glycoprotein, and is optimally active at pH 5.4. Treatment at 62 degrees for one hour does not inactivate the enzyme, which is inhibited by chelating agents.

Animals↗