Characterization of inhibitors and substrates of Anopheles gambiae CYP6Z2.

Three CYP6Z genes are linked to a major pyrethroid resistance locus in the mosquito Anopheles gambiae. We have expressed CYP6Z2 in Escherichia coli and produced a structural model in order to examine its role in detoxification. E. coli membranes co-expressing CYP6Z2 and An. gambiae P450 reductase (AgCPR) catalysed the dealkylation of benzyloxyresorufin with kinetic parameters K(m) = 0.13 microM; K(cat) = 1.5 min(-1). The IC(50) values of a wide range of compounds were measured. Pyrethroids cypermethrin and permethrin produced low IC(50) values, but were not metabolized. Plant flavanoids were the most potent inhibitors. Several compounds were shown to be substrates, suggesting that CYP6Z2 has broad substrate specificity and plays an important chemo-protective role during the herbivorous phase of the life-cycle.

Factors predictive of voiding problems following insertion of tension-free vaginal tape.

OBJECTIVE: To identify predictive factors of urinary retention following a tension-free vaginal tape (TVT) procedure, so that patients may be better advised of their risk of undergoing catheterization and tape release. METHOD: A retrospective review of women who underwent a TVT procedure over five years. Patient age, pressure flow rate, concomitant vaginal surgery, and the form of anesthesia used for the surgery were analyzed. The Mann-Whitney U Test and logistic regression were used to explore the effect of these factors. RESULTS: Because of the small sample size, none of these factors were shown to be significantly predictive of postoperative voiding difficulty. However, there could be a correlation between postoperative voiding difficulty and concomitant posterior vaginal repair as well as lower preoperative flow rate. CONCLUSION: No significant predictive factors were found, but there was a trend toward long-term voiding difficulty for women who underwent posterior vaginal repair and women with low preoperative flow rates.

Plasma concentrations of prostaglandins during late human pregnancy: influence of normal and preterm labor.

Highly sensitive and specific RIA procedures have been used to measure prostaglandin concentrations in the peripheral circulation of late pregnant and parturient women. The concentrations of prostaglandin E (PGE) and prostaglandin F (PGF) in plasma samples assayed within 4 weeks of collection were not significantly different among the groups studied, the levels (mean +/- SEM, picograms per ml) were: late pregnancy (n = 13): PGE, 4.8 +/- 1.0; PGF, 6.2 +/- 0.5; early term labor (n = 5): PGE, 6.8 +/- 1.5; PGF, 7.9 +/- 0.7; late term labor (n = 5): PGE, 5.4 +/- 2.2; PGF, 12.4 +/- 3.5; and preterm labor (n = 7): PGE, 4.4 +/- 0.4; PGF, 6.9 +/- 1.4. The concentration of 13,14-dihydro-15-keto-prostaglandin F (PGFM) in late pregnancy was 59.0 +/- 7.8 pg/ml. During spontaneous term labor, the concentration of PGFM was significantly elevated (P less than 0.01) to 142.8 +/- 32.3 pg/ml in early labor and 282.7 +/- 55.3 pg/ml in late labor. The concentration of PGFM in plasma from patients in preterm labor (62.7 +/- 17.4 pg/ml) was not significantly different from that found during late pregnancy, but was significantly lower than levels found at term during early labor (P less than 0.05). The concentration of PGE increased significantly in frozen plasma samples stored for more than 4 weeks in all groups studied; the concentration of PGF was significantly elevated after storage only in the late pregnancy group (P less than 0.01). The plasma concentration of PGFM in all groups studied was unaffected by storage. It is concluded that measurement of PGFM concentrations is the most reliable method available of monitoring prostaglandins in the peripheral circulation and that great care must be exercised in the assay and interpretation of prostaglandin levels in human plasma.

Thromboxane B2 and human parturition: concentrations in the plasma and production in vitro.

The concentration of thromboxane B2 has been measured in the plasma of women during late pregnancy, during term and pre-term labour, in women with pre-eclampsia and in umbilical cord arterial and venous plasma. In addition, the rates of production of thromboxane B2 in vitro were determined for placental tissues obtained after spontaneous vaginal delivery or elective Caesarean section. The results obtained indicate significant differences during parturition between the sources and controlling mechanisms of thromboxane and prostaglandin production.

Measurement of pH to quantify urease activity.

The rate of change of pH caused by the hydrolysis of urea was measured for urease solutions of 18 different concentrations. Concentrations were converted into an activity, A (measured in IU/cm3), by using a titrimetric method to assay the urease sample. For activities in the range 0.6-38 IU/cm3, A was related to the initial rate of change of pH, (dpH/dt)0, (measured in s-1) by the empirical relationship: A = 549(dpH/dt)0-1423(dpH/dt)2(0). Values of (dpH/dt)0 were sensitive to changes in the urease activity of about 0.6 IU/cm3.

Tetanus immunisation state in a general practice population.

PIP: An immunization study that surveyed a limited area of participants found that most of the adult population is poorly immunized against tetanus. Among the adult population, women between the ages of 30-60 were the most poorly immunized. The participants were given a questionnaire that assessed the 3 main opportunities for receiving immunization: while in the armed services, in infancy, or by following a course that included 3 tetanus injections. Of the 543 participants who responded, only 69 (13%) had followed a primary course ensued by a booster in the past 5 years. Of the 412 who had not received proper immunization, only 177 planned to make an appointment for a tetanus injection. One month later, only 37 had followed up on the appointment. Future efforts aimed at improving the percentage of immunization should focus on target groups such as older women. It is a plausible method of immunization coverage to review the tetanus immunization record along with cervical smears every 5 years and offering an immunization for this target group.^ieng

Evidence-based practice. Guiding lights.

Traditional methods of implementing clinical guidelines and changing professional practice endure despite evidence that they are ineffective. The increasing demand for guideline implementation will have to be met within existing resources. Work in one health authority, which marries the methods of changing practice shown to be effective with the limited resources available, is already showing dividends.

Fluorapatite-mullite glass sputter coated Ti6Al4V for biomedical applications.

A number of bioactive ceramics have been researched since the development of Bioglass in the 1970's. Fluorapatite mullite has been developed from the dental glass-ceramics used for more general hard tissue replacement. Being brittle in nature, glass-ceramics are currently used mainly as coatings. This paper shows that fluorapatite glass LG112 can be used as a sputtered glass coating on roughened surfaces of Ti6Al4V for possible future use for medical implants. An AFM was used to measure the roughness of the surface before and after coating to determine the change in the topography due to the coating process as this greatly affects cell attachment. The sputter coating partially filled in the artificially roughened surface, changing the prepared topography. Osteoblasts have been successfully grown on the surface of these coatings, showing biocompatibility with bone tissue and therefore potential use in hard tissue repair.

Acidification of urine is not a feasible method for preventing encrustation of indwelling urinary catheters.

Encrusting deposits form on urinary catheters as a result of infection by bacteria which produce urease. Urease catalyses the hydrolysis of urea to produce ammonia, with the result that the pH of the urine increases and the deposits are precipitated. It has been suggested that acidification of urine may prevent this rise in pH and so prevent encrustation. Experiments were performed in vitro to determine whether acidification could be used to prevent the rise in pH when urease is present in urine. It was found that, in the presence of urease, the initial decrease in pH resulting from acidification was countered by further urea being converted into ammonia. Thus, although acidic washout solutions may dissolve encrusting deposits, acidification of urine is not a feasible method for preventing catheter encrustation.

Critical assessment of dilatation and curettage in 1029 women.

Of 1029 dilatation-and-curettage operations carried out in a 12-month period, more than half were in women aged under 40, and 38% were for menstrual disturbances. The yield of intrauterine disease in these groups was low--curettage for post-menopausal bleeding or discharge in 150 women detected 15 endomettrial carcinomas and a similar number of other endometrial lesions. The complication-rate resulting from curettage was 1.7%--i.e., equivalent to the overall rate of detection of endometrial carcinoma. Selection of patients submitted to uterine curettage could be better, but postmenopausal bleeding remains an indication for mandatory uterine curettage.

Melatonin in the maternal and umbilical circulations during human parturition.

The concentration of melatonin in maternal peripheral plasma was measured during late pregnancy, term and pre-term labour. There was a small increase in the mean concentration of melatonin during labour which was significant in term labour. Umbilical arterial and venous plasma, whether obtained at term, after spontaneous vaginal delivery or at Caesarean section, contained significantly greater concentrations of melatonin than maternal plasma. A significant arterio-venous difference was demonstrated for both groups of umbilical samples with raised venous levels after spontaneous vaginal delivery but higher arterial levels at Caesarean section.

Prevalence of HPV cervical infection in a family planning clinic determined by polymerase chain reaction and dot blot hybridisation.

The overall prevalence of human papillomavirus (HPV) cervical infection in 131 women attending a family planning clinic was 7% (HPV 6/11, 16, 18, 31) by dot blot hybridisation, 53% (HPV 11, 16, 31) by polymerase chain reaction (PCR), and 56% by the two methods combined. HPV 16 and 18 were the commonest types (4% each) by dot blot, HPV 16 (39%) by PCR. Fifteen percent of subjects had mildly abnormal cervical cytology (grades 1A, 2A, or 3). There was no significant correlation between cytological abnormality and HPV positivity, or between cytological or HPV status and other postulated risk factors for cervical neoplasia. It is concluded that PCR is considerably more sensitive than dot blot DNA hybridisation in detecting HPV cervical infection in such a "low risk" setting, where HPV copy number may be low. Firm conclusions cannot be drawn from our results regarding a causal role for HPV or other factors in the development of cervical neoplasia.

PIP: In 1989, health practitioners scraped the cervixes of 131 women who came to the St. Giles Clinic for family planning services in Northampton, England to compare the sensitivity of dot blot DNA hybridization and polymerase chain reaction (PCR). They also wanted to determine the prevalence of human papilloma virus (HPV) infection in a sexually active but not a high risk population. PCR detected HPV infection in 53% of the women while dot blot hybridization only detected it in 7%. Therefore PCR was more sensitive than dot blot hybridization. Together the 2 techniques indicated a 56% prevalence. Mildly abnormal cytology existed in 15% of the women. HPV positivity did not necessarily correlate with abnormal cytology. This lack of association did not necessarily indicate that HPV does not play a role in development of cervical neoplasia, however. This study found a significant relationship between cytological abnormality and being parous and between cytological abnormality and a history of genital warts (p.01). Further women with abnormal cytology tended to be younger (median, 21 years) than women with normal cytology or the group as a whole (24 years). In addition, the median number of sexual partners was higher in HPV positive women (3-4 partners) than HPV negative women or the entire group (=or- 2 partners). Nevertheless the correlation between abnormal cytology and age and sex partners was not significant. The researchers proposed that these cofactors may be more important in development of cervical neoplasia than HPV. Since HPV appeared frequently in women of median age of 24 years and a median of 2 lifetime sexual partners indicated that they may have been infected early with HPV by nonsexual routes. Researchers should investigate this possibility further by conducting age related serological studies in children.

The effect of cervical encerclage on plasma prostaglandin concentrations during early human pregnancy.

In women having either cervical encerclage under general anaesthesia or a vaginal examination in the early second trimester of pregnancy, peripheral plasma levels of 13,14-dihydro-15-keto prostaglandin F (PGFM) were measured before and after each procedure. A significant rise in circulating levels of PGFM was found within minutes of completing cervical encerclage but not after vaginal examination or induction of general anaesthesia.

Possible role for prostacyclin in human parturition.

Human amnion, chorion, decidua and placenta produced 6-oxo-PGF1alpha when superfused in vitro. Furthermore amnion, an avascular tissue, produced more 6-oxo-PGF1alpha after labour than all other tissues investigated and its production of 6-oxo-PGF1alpha was significantly greater after labour than before the onset of labour. These findings suggest that prostacyclin production by foetal membranes may have a role in the mechanisms controlling human parturition. Moreover, this is the first evidence for the production of prostacyclin by an avascular tissue.

Specific production of prostaglandin E by human amnion in vitro.

Prostaglandin production by intra-uterine human tissues has been investigated using a method of tissue superfusion. Tissues were obtained at elective Caesarean section and after spontaneous vaginal delivery. It was found that all the tissues studied (amnion, chorion, decidua and placenta) produced more prostaglandin E (PGE) and 13,14-dihydro-15-keto-prostaglandin F (PGFM - the major circulating metabolite of prostaglandin F) than prostaglandin F (PGF). Amnion produced significantly more PGE (but not PGF or PGFM) than any other tissue. Prostaglandin production by each tissue was similar whether it was taken at elective Caesarean section or after spontaneous vaginal delivery.

Tension-free vaginal tape for primary genuine stress incontinence: a two-centre follow-up study.

OBJECTIVE: To assess the safety and efficacy of the tension-free vaginal tape procedure in the treatment of primary genuine stress incontinence. PATIENTS AND METHODS: A two-centre follow-up study was conducted on 40 women with urodynamically confirmed primary genuine stress incontinence who had a tension-free vaginal tape inserted under local anaesthesia with sedation. Operative details were recorded and all patients followed up both subjectively, and objectively with repeat urodynamic studies and pad testing. RESULTS: The mean (range) age of the women was 51.1 (33-86) years, the median parity 2 (0-4) and mean body mass index 25.1 (19-35). The mean anaesthesia and operative duration was 42 (25-65) min; 93% of the women resumed immediate spontaneous voiding with no need for catheterization. The mean inpatient stay was 2.2 (2-4) days (where 2 days is equivalent to one night in hospital). The follow-up was conducted at a mean interval of 12.3 (6-24) months. Subjectively, 80% of women were cured and 17.5% significantly improved; objectively, genuine stress incontinence was cured in 95%. Symptomatic postoperative detrusor instability was found in 15% of women and symptoms of voiding dysfunction identified in 5% of women. There were no defects in healing or tape rejection. CONCLUSION: The tension-free vaginal tape procedure is a promising new technique that, in this short-term analysis, appears to be safe and effective. Intra-operative complications are uncommon and both hospital stay and recovery are short. Voiding complications are rare but symptomatic postoperative detrusor instability had an incidence of 15%.

A comparison of plasma prostaglandin levels in term and preterm labour.

Peripheral plasma levels of 13,14-dihydro-15-keto-prostaglandin F (PGFM) were determined in women during pregnancy and in term and preterm labour. The PGFM concentrations at term were not significantly different from the levels between 26 and 34 weeks gestation. In both term and preterm labour there was a rise in PGFM levels with increasing cervical dilatation although the mean values tended to be lower during preterm labour. These findings may provide an explanation for the effectiveness of prostaglandin synthetase inhibitors in suppressing myometrial activity in preterm labour.

Prostaglandins in umbilical plasma at elective caesarean section.

Prostaglandin E (PGE), prostaglandin F (PGF) and 13,14-dihydro-15-ketoprostaglandin F (PGFM) have been measured in umbilical cord plasma obtained immediately after delivery by elective Caesarean section. Umbilical venous plasma levels of PGE were significantly greater than the corresponding arterial levels (p less than 0.02); there were no significant arterio-venous differences for PGF or PGFM. In general, concentrations of PGFM exceeded those of PGE which in turn were greater than concentrations of PGF. Umbilical venous levels of PGE and both arterial and venous levels of PGF and PGFM were significantly greater after spontaneous labour with vaginal delivery than after elective Caesarean section.

Prostaglandins in the human umbilical circulation at birth.

Prostaglandin E (PGE), prostaglandin F (PGF) and 13, 14-dihydro-15-keto-prostaglandin F (PGFM) have been measured in umbilical cord plasma obtained immediately after delivery of the baby before clampiing of the cord. In general the prostaglandin levels followed the pattern PGFM greater than PGE greater than PGF. A significant arterio-venous difference was demonstrated only for PGE with raised venous levels (P less than 0.01). In cord blood samples obtained from infants whose mothers had received epidural anaesthesia, no arterio-venous difference for PGE could be demonstrated although the mean levels were not significantly different from controls. The concentrations of prostaglandins in umbilical cord plasma proximal to the placenta were found to rise continuously from the time of delivery of the baby with no significant changes after cord clamping or placental delivery. The possible physiological significance of these findings is discussed.