Search PubMed⌕ Search

Biomedical subjects

M J Turner

Publications and source records attributed to M J Turner.

At least 145 records · Page 8Linked to original sources
PubMed1990

Treatment of Pneumocystis carinii pneumonia with 1,3-beta-glucan synthesis inhibitors.

Pneumocystis carinii pneumonia is a major cause of death in AIDS patients in the United States. The presently available treatments have limited use due to a high incidence of adverse reactions. Therefore, there is an urgent need for a safer method for treatment and prevention of this disease. Recent evidence has suggested that P. carinii is related to fungi and that the wall of the cyst form contains 1,3-beta-glucan as a major constituent. Based on this, several proposed 1,3-beta-glucan synthesis inhibitors were evaluated for their ability to control P. carinii pneumonia in vivo. Compounds from two classes of 1,3-beta-glucan synthesis inhibitors, the echinocandins and papulacandins, were found to be effective against P. carinii.

Animals↗
PubMed1990

Vinyl chloride-induced DNA adducts. I: Quantitative determination of N2,3-ethenoguanine based on electrophore labeling.

A sensitive assay for quantitative determination of the vinyl chloride (VC)-induced cyclic DNA adduct N2,3-ethenoguanine (EG) was developed. The method is based on the detection of EG as its di-pentafluorobenzyl derivative (3,5-PFB2-EG). This compound exhibited good gas chromatographic properties and was detected with high sensitivity by gas chromatography with electron capture detection (limit of detection 300 amol/microliters injected solution) or with negative ion chemical ionization mass spectrometry monitoring the [M-181]-fragment ion at m/z 354 (GC-NICI-MS, limit of detection 190 amol/microliters injected solution). EG, its 13C-labeled analog [13C4]-EG and 3,5-PFB2-EG were synthesized and characterized by UV and fluorescence spectrophotometry, 1H- and 13C-NMR spectroscopy and mass spectrometry. The standards were used to optimize the isolation of EG and its derivatization with pentafluorobenzyl bromide (electrophore labeling) at fmol quantities. DNA solutions were spiked with EG, the DNA was depurinated by mild acid hydrolysis, and EG was isolated from the hydrolysates by low-pressure strong cation exchange chromatography with subsequent C18 solid-phase extraction. The extracted EG was electrophore labeled and 3,5-PFB2-EG was detected using GC-NICI-MS. [13C4]EG served as internal standard. 3,5-PFB2-EG was quantitated relative to its 13C-labeled analog by measuring the ion ratio m/z 354/358. The limit of detection for the complete method was 60 fmol EG/mumols guanine. The method was applied to liver DNA from young Sprague-Dawley rats exposed to 600 p.p.m. VC from day 10 through day 14 after birth. The EG concentration in these samples was 1.8 +/- 0.3 pmol/mumols guanine.

DNA↗
PubMed1990

Is amniotic fluid quantitation of value in the diagnosis and conservative management of prelabour membrane rupture at term?

This study examined the hypothesis that ultrasound quantitation of amniotic fluid depth is of value in the diagnosis and management of prelabour rupture of the membranes (PROM) at term. The deepest vertical pool was measured in 151 consecutive patients with a history of suspected PROM for at least 10 h before labour. In 100 patients the diagnosis of PROM was confirmed by the collection of amniotic fluid at the vulva. There was no difference in mean depth of amniotic fluid in 100 patients with confirmed PROM, compared with 51 in whom PROM was not confirmed (48.5 mm SD 16.4 vs. 60.1 mm SD 16.5); the frequency of oligohydramnios (fluid depth less than 30 mm) was 5% and 5.8% respectively. There was no relation between ultrasound amniotic fluid quantitation and the onset of labour, the duration of labour nor the frequency of oxytocin augmentation in labour. The results show that ultrasound quantitation of amniotic fluid is of no value in the diagnosis and conservative management of PROM at term.

Amniotic Fluid↗
PubMed1990

New design rigid and soft vacuum extractor cups: a preliminary comparison of traction forces.

Women due for vacuum extraction were randomly allocated to delivery using one of two soft cups (Silc or Silastic) or two new design rigid cups (New Bird or O'Neil). Traction forces were recorded continuously and higher values were reached with the rigid than the soft cups (median 15.8, range 7.5-19.7 vs 11.1, 7.2-15.1 kg, P less than 0.01). Selection of the most appropriate vacuum cup for each clinical situation should take into account that the flexible cups are associated with less cosmetic disfigurement but have a lower capacity for traction.

Equipment Design↗
PubMed1990

Serum antibody responses in sheep after natural infection with Bacteroides nodosus.

Soluble outer membrane protein of Bacteroides nodosus extracted with potassium thiocyanate (KSCN) was employed as antigen in an enzyme linked immunosorbent assay (ELISA) to detect serum antibody in sheep naturally infected with a heterologous serogroup. Serum antibody responses in 55 sheep were monitored for 2 years and maximum levels were directly related to the severity of clinical foot lesions. Serum antibody levels rose 2 weeks after foot lesions developed and declined within several months of resolution of lesions. After the first footrot transmission period, antibody levels persisted significantly (P less than 0.001) longer in sheep that did not become affected in the next transmission period compared with sheep in which footrot recurred. Antibody response did not appear to result in resolution of foot lesions. ELISA using KSCN antigen gave similar results to whole cell ELISA where cells prepared from an homologous serogroup were used as antigen. Both these assays were more sensitive than ELISA in which heterologous whole cell antigen was used. Proteins extracted from the outer membrane of B. nodosus, which are known to be immunogenic in natural infection and common to different serogroups of B. nodosus, appear to be useful antigens for serological investigations of ovine footrot.

Animals↗
PubMed1990

Cytological screening history of patients with early invasive cervical cancer.

The value of population screening for cervical cancer has recently been questioned. The purpose of this study was to examine the cytological screening history in 100 consecutive patients undergoing Wertheim's hysterectomy for early invasive cervical cancer. Twenty three per cent of the patients were never screened; the screening history was unavailable in 11%; the patient was referred appropriately in 21%; there was a delay in referral for gynaecological assessment in 21%; the patient's previous cervical smear before referral was normal in 24%. If population screening in Ireland is to have an impact on mortality from cervical cancer, the results of this study indicate that greater attention needs to be given not only to extending the number of women screened, but also to increasing the frequency of screening and to improving the clinical response to an abnormal smear.

Adenocarcinoma↗
PubMed1990

The influence of birth weight on labor in nulliparas.

The purpose of this study was to examine the hypothesis that dystocia in nulliparas is directly related to birth weight. The study was confined to the first 1000 nulliparas delivered in 1988 who went into labor after 37 weeks' gestation with a single live fetus and cephalic presentation. The management of labor was standardized. As birth weight increased, there was an increase in the mean duration of labor and of the second stage of labor, in the incidence of oxytocin augmentation, and in the incidence of both cesarean and forceps delivery for dystocia. The direct relationship between birth weight and the mean duration of labor was independent of gestation and oxytocin augmentation. These findings suggest that birth weight is an important factor in the development of dystocia in nulliparas.

Birth Weight↗
PubMed1989

Potential of the sulfobetaine detergent Zwittergent 3-12 as a desorbing agent in biospecific and bioselective affinity chromatography.

The isolation in our laboratories of several antigens of interest from sporulated oocysts of Eimeria species by bioselective adsorption on matrices containing immobilized antigen-specific immunoglobulins IgG was initially unsuccessful. The preparations serving as source materials for these antigens contained low levels of the zwitterionic sulfobetaine detergent, Zwittergent 3-12. Since usually immunoaffinity processes are carried out in the presence of various detergents, we were surprised, subsequently, to find this detergent to be the cause of the problem in that it prevented antigen-antibody binding. These findings led us to study the potential role of Zwittergent 3-12 as an eluting agent from matrices holding bioselectively adsorbed materials. The results of seven case studies are presented in this paper and include experiments with beta-D-galactosidase adsorbed biospecifically and bioselectively on matrices via either specific antibody or inhibitor analogue. In all cases, Zwittergent 3-12 proved to be an effective desorbing agent.

Animals↗
PubMed1989

MK-801 is a potent nematocidal agent. Characterization of MK-801 binding sites in Caenorhabditis elegans.

MK-801, an N-methyl-D-aspartate antagonist in mammalian brain tissue, is a potent nematocidal agent. Specific MK-801 binding sites have been identified and characterized in a membrane fraction prepared from the free-living nematode Caenorhabditis elegans. The high-affinity MK-801 binding site has an apparent dissociation constant, Kd, of 225 nM. Unlike the MK-801 binding site in mammalian tissues, the C. elegans binding site is not effected by glutamate or glycine, and polyamines are potent inhibitors of specific MK-801 binding.

Animals↗
PubMed1989

Involvement of reversible binding to alpha 2u-globulin in 1,4-dichlorobenzene-induced nephrotoxicity.

Similarly to unleaded gasoline, 1,4-dichlorobenzene (1,4-DCB) administered for 2 years caused a dose-related increase in the incidence of renal tumors in male but not in female rats or in either sex of mice. Unleaded gasoline and 2,2,4-trimethylpentane (TMP), a component of unleaded gasoline, increased protein droplet formation and cell proliferation in male but not in female rat kidneys. These protein droplets contained, alpha 2u-globulin, a male rat-specific low-molecular-weight protein and 2,4,4-trimethyl-2-pentanol, a metabolite of TMP that was reversibly bound to this protein. Studies were undertaken to determine if 1,4-DCB produced similar effects; 1,2-DCB was used for comparison since it did not produce renal carcinogenesis in male rats. Gel filtration chromatography of a 116,000g supernatant prepared from kidneys of 1,4-[14C]DCB-treated rats showed that radiolabel coeluted with alpha 2u-globulin as one sharp peak as opposed to a multipeak pattern observed for 1,2-[14C]DCB; the maximal quantity of radiolabel for 1,4-DCB was twice that for 1,2-DCB. Equilibrium dialysis of kidney cytosol in the presence or absence of sodium dodecyl sulfate demonstrated that the radiolabel was reversibly bound to alpha 2u-globulin; the amount for 1,4-[14C]DCB-treated rats was almost twice as much as that for 1,2-[14C]DCB-treated rats. 1,2-DCB was also shown to be covalently bound to renal alpha 2u-globulin, and covalently bound to liver and plasma high-molecular-weight proteins. 1,4-DCB and, to a minor extent, 2,5-dichlorophenol, the major metabolite of 1,4-DCB, were reversibly bound to renal alpha 2u-globulin from 1,4-DCB-treated rats. 1,4-DCB increased protein droplet formation in male but not in female rat kidneys, whereas equimolar doses of 1,2-DCB showed no effect in either sex. Renal cell proliferation, measured by [3H]thymidine incorporation into renal DNA, was increased after 1,4-DCB but not after 1,2-DCB treatment. Nephrotoxicity and biochemical alterations induced by 1,4-DCB resemble those of unleaded gasoline and suggest that a similar mechanism is involved in the induction of alpha 2u-globulin nephropathy in male rats.

Alpha-Globulins↗
PubMed1989

Evidence for and characterization of a mannitol cycle in Eimeria tenella.

Recently, it was found that large quantities of mannitol are present in unsporulated oocysts of the protozoan parasite Eimeria tenella and that these levels diminish during maturation (sporulation). Investigations into the metabolic role of mannitol have led to the discovery that a mannitol cycle is present in this parasite. Prior to these studies the mannitol cycle was found exclusively in fungi. The parasite cycle is similar to that in the fungi although there are distinct differences in coenzyme requirements. The enzymes involved in the parasite pathway include mannitol-1-phosphate dehydrogenase (EC 1.1.1.17), mannitol-1-phosphatase (EC 3.1.3.22), mannitol dehydrogenase (EC 1.1.1.67), and hexokinase (EC 2.7.1.1). Kinetic studies were conducted to determine the Km and specific activities of these enzymes at both ambient temperature (where sporulation occurs) and the chicken's body temperature (41 degrees C). The data suggest that mannitol is produced during oocyst formation in the chicken gut and accumulated as an energy reserve for sporulation. The apparent lack of mannitol kinase in the organism and the Km values for the dehydrogenases in the reverse direction all indicate that the cycle only proceeds in one direction. In addition to serving as an energy storage system the cycle may also function as an electron 'sink' for the parasite which must survive in the anaerobic environment of the gut.

Animals↗
PubMed1989

Evidence for intracellular superoxide formation following the exposure of guinea pig enterocytes to bleomycin.

Spin trapping of free radicals during the exposure of guinea pig enterocytes to bleomycin (BLM) was investigated using an in vitro cell suspension. The spin traps employed in this study were 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) and 3,3-diethyl-5,5-dimethyl-1-pyrroline-1-oxide (DEDMPO). The hydroxyl radical spin-trapped adduct 2-hydroxy-5,5-dimethyl-1-pyrrolidinyloxyl (DMPO-OH) was observed with DMPO. In the presence of dimethyl sulfoxide (DMSO), the only 2,2,5-trimethyl-1-pyrrolidinyloxyl (DMPO-CH3) observed was that expected from hydroxyl radical formation by the decomposition of the superoxide spin-trapped adduct 2-hydroperoxy-5,5-dimethyl-1-pyrrolidinyloxyl (DMPO-OOH). Production of hydroxyl radical was not detected in the presence of DEDMPO, which is a nitrone that will spin trap hydroxyl radical, but not superoxide, at cellular concentrations. Thus, these data indicate that superoxide was produced during the exposure of guinea pig enterocytes to BLM and that DMPO-OH resulted from the cellular bioreduction of DMPO-OOH by glutathione peroxidase. Addition of superoxide dismutase to the in vitro reaction mixture indicated that superoxide production was intracellular.

Animals↗
PubMed1989

Pelvic drainage after anterior resection of the rectum.

Thirty patients undergoing anterior resection of the rectum were randomized for postoperative drainage with either corrugated (N = 14) or corrugated plus Shirley sump drain (N = 16). Drainage volume per 24 hours was measured, and volume of residual pelvic fluid collection estimated by CT scan on the seventh postoperative day. A mean of 591.9 +/- 415.2 ml of fluid drained during the first seven postoperative days. There was a significant (P less than 0.01) increase in 24 hour drainage volume between the fourth and sixth postoperative days. There was no significant difference in drainage volumes between the two drainage methods. Residual pelvic fluid collection (median volume, 16 ml) was detected in 80 percent of patients at one week after operation. While this was larger (24 ml median) for the corrugated only group compared with the corrugated plus sump drain group (11.5 ml median), the difference was not significant. Fluid loss during the first postoperative week (616.6 +/- 424.2 ml) was significantly (P less than 0.05) less when the anastomosis was situated higher than 12 cm (294 +/- 192 ml) compared with 6 to 12 cm from the anal margin (496 +/- 210 ml), or after coloanal anastomosis (1077 +/- 432 ml). Residual pelvic fluid collection was larger after coloanal anastomosis (median, 33 ml; range, 1.5 to 90 ml) compared with 6 to 12 cm (median, 11 ml; range, 0-124 ml) or higher than 12 cm (median 9 ml; range, 0 to 16 ml) from the anal margin, but the difference was not significant. Drainage after anterior resection is important because large volumes of serosanguineous fluid collect, especially after resection of low tumors. Neither of the drainage methods tested in this study prevented persisting pelvic fluid collection at the seventh postoperative day.

Anastomosis, Surgical↗
PubMed1989

Successful outcome after antepartum expulsion of placenta and fetus into the abdominal cavity; a case report.

Spontaneous rupture of the uterus before labour is a rare event associated with a high incidence of maternal and fetal death. We report a case of spontaneous uterine rupture at 34 weeks' gestation in a patient's second pregnancy. The case is unusual because both the mother and baby survived despite the expulsion of the placenta with the fetus into the abdominal cavity prior to laparotomy.

Abdomen↗
PubMed1989

Evidence for unusually short tubulin mRNA leaders and characterization of tubulin genes in Giardia lamblia.

We have cloned alpha- and beta-tubulin cDNAs from Giardia lamblia and have used these to determine the gene copy number in the organism and to isolate alpha- and beta-tubulin genomic clones. Studies of the gene organization demonstrate that two copies of beta-tubulin are linked in a head-to-head configuration. The DNA from these two copies and that from one alpha-tubulin copy has been sequenced upstream of the translation initiation codon, and analyzed for consensus to typical eukaryotic promoter sequences. Characterization of the alpha- and beta-tubulin mRNAs in this parasite by primer extension and S1 nuclease mapping has revealed an unusually short (6 nucleotides) 5' untranslated region.

Animals↗
PubMed1989

Measurement of the frequency response and common-mode gain of neonatal respiratory pressure and flow measurement systems. Part 1: Apparatus.

It is necessary, especially in neonatal work, for investigators to measure accurately the frequency response and common mode gain of respiratory pressure and flow transducers in air and other gas mixtures. Many of the systems designed for this task have been incompletely analysed and have unknown frequency responses themselves. We analyse aspects of systems employed previously and show that substantial amplitude and phase errors may have occurred. We describe a plethysmograph-based system which operates in any available gas mixture. A mathematical model of the acoustic microphone used as reference transducer, the microphone preamplifier, and the thermal behaviour of the plethysmograph, is developed to quantify the frequency response of the system. Maximum deviation from a perfect response is less than 1% in amplitude and 1 degree in phase for both pressure and flow measurements over the range 1-100 Hz. Measurements using a pressure transducer mounted on the tip of a catheter indicate that the error due to amplitude and phase variation in the plethysmograph is less than 0.1 dB and 0.4 degrees at 100 Hz.

Humans↗
PubMed1989

Measurement of the frequency response and common-mode gain of neonatal respiratory pressure and flow measurement systems. Part 2: Results.

We show that the technique of exciting a differential pressure transducer at one port to measure its differential gain yields incorrect results in the case of asymmetrical differential pressure transducers but is acceptable in the case of symmetrical transducers. We have measured the common-mode gain of a symmetrical and an asymmetrical differential pressure transducer from 1 Hz to 100 Hz, both directly and by computation from differential gain measurements. No compensation for common-mode error is necessary when a symmetrical transducer is used in mechanically ventilated neonates. We have also measured the frequency response of neonatal Fleisch and screen pneumotachographs connected to Validyne MP45 differential pressure transducers in air, 60% oxygen and 100% oxygen, and concluded that the effect of oxygen concentration is small below 40 Hz. However, the normalised frequency response of the flow transducer differs markedly from unity at frequencies inside the flow bandwidth generated by neonatal pressure cycled ventilators and dynamic correction is therefore necessary.

Humans↗