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A direct interrogation, portable analysis technique (portable FT-IR) and a novel environment-monitoring profluorescent sensor for studying aircraft coating degradation have been developed. For the direct interrogation approach, a standard military aircraft paint: 459-line Anzothane flexible polyurethane (lead free) has been used to illustrate a new potential field technique to evaluate coating service lifetime, portable FT-IR. This technique allows direct analysis of chemical changes within the degrading coatings and has the potential to evaluate service lifetime when coupled with advanced statistical analysis methods (chemometrics). The degradation environment monitoring sensors are embodied in a profluorescent environment-sensitive witness patch that may be analysed in-service by a field-deployable fluorescence spectrometer. Accelerated ageing for both the paint and the witness patches has been undertaken and their capabilities as aircraft paint degradation monitors assessed.

Biodegradable composite materials free from toxic initiator residues have been prepared using calcium alkoxides bound to silica. Polycaprolactone with low polydispersity was synthesized by ring-opening polymerization of e-caprolactone at 100 °C on a calcium alkoxide-functionalized silica substrate prepared by the grafting of a hydrolysed epoxy silane onto silica gel, followed by reaction with calcium hydride. The polymerization was also initiated by the product of the direct reaction of calcium hydride with unfunctionalized silanol groups. Characterization of the reaction products and the real-time reaction kinetics using Raman spectroscopy suggests a living coordination–insertion mechanism. There is a difference in reactivity of a factor of ca 7 between the calcium alkoxide formed on the silanized and unsilanized silica surface, resulting in a monomer conversion of 90% in 100 h for the silanized silica compared to only 30% for the unsilanized silica. The degree of grafting ranges from a maximum of 30% for the silanized surface to 10% for the unsilanized silica alone. There is evidence for cyclic transesterification products, and release of the polymer from the silica occurs in this way and also by adventitious hydrolysis. Copyright © 2010 Society of Chemical Industry

A systematic cervical cancer screening program was initiated in January 1987 at The Aga Khan University Medical Center, Karachi, Pakistan. The 8,784 cervical smears obtained in 3 subsequent years from 8,412 consecutive women attending the gynecology and antenatal clinics were reviewed. "Positive" smears were found in 111 (1.3%) patients; 107 (1.27%) smears showed squamous epithelial dysplasia and 4 smears showed adenocarcinoma. The highest incidence of abnormal smears was found in the 45-54 years age group. Colposcopy and biopsy was performed on all patients with "positive" smears except on those with atypical or mildly dysplastic ones, in whom only the persistence of the abnormality on repeated smears was considered an indication for tissue evaluation. The histopathologic diagnosis of these biopsy specimens revealed cervical intra-epithelial neoplasia in 60 patients and invasive cervical cancer in 6 patients.

In order to determine the prevalence of glucose intolerance in pregnancy, 2,230 consecutive women attending the antenatal clinic at the Aga Khan University Medical Centre in Karachi, Pakistan were subjected on the first antenatal visit, irrespective of gestational age, to a 75 g glucose challenge followed 2 hr later by plasma glucose determination. The test, was repeated at 28-32 weeks of gestation for those patients who had an abnormal initial screen at less than 28 weeks gestation followed by a normal glucose tolerance test and for those who had a risk factor for gestational diabetes even though the initial screen at less than 28 weeks gestation was normal. The initial glucose challenge test was abnormal (2 hr plasma glucose greater than 140 mg%) in 8.6% of the screened population. An oral glucose tolerance test on these patients revealed a prevalence for the entire population of 3.5% of gestational diabetes and 1.9% of impaired glucose tolerance test based on the modified O'Sullivan criteria. Patients with abnormal glucose tolerance test were older, had higher parity, a past history of macrosomia and a family history of diabetes compared to the controls. These patients also had a higher incidence of preterm labour and caesarean section. In the neonates hypoglycemia and hyperbilirubinemia were similarly higher. The fetal abnormality rate was 5.6% and the perinatal mortality was 28/1,000 which were higher than the controls.

Catalysis of the ring-opening reaction of L-lactide and e-caprolactone to form the corresponding biodegradable polyesters is frequently performed using organometallic compounds such as tin(II) 2-ethylhexanoate, which operates by a living, coordination insertion mechanism. For biomedical applications, non-toxic calcium salts have been researched but these rarely approach the same efficiency. The use of heterogeneous immobilized catalysts offers an alternative approach, but competing reactions such as transesterification affect the final molecular weight and polydispersity. The formation of hybrid materials by using silica as the initiation site offers the prospect of biomaterials with novel properties. Copyright © 2009 Society of Chemical Industry

Two supported metallocene catalysts (CS 1: PQ 3030/MAO/Cp2ZrCl2 and CS 2: PQ 3030-BuGeCl3/MAO/Cp2 ZrCl2) were prepared by sequentially loading MAO and Cp2ZrCl2 on partially dehydroxylated silica PQ 3030. In catalyst CS 2, nBuGeCl3 was used to functionalize the silica. These catalysts were characterized by DR-FTIR spectroscopy, CPMAS NMR spectroscopy, and XPS. Their catalytic performance was evaluated by polymerizing ethylene using the MAO cocatalyst and characterizing the resulting polymers by GPC. Both catalysts produced two metallocenium cations (Cation 1: [Cp2ZrCl]+ and Cation 2: [Cp2ZrMe]+) with comparable equilibrium concentrations and showed varying solid-state electronic environments. The modified supports (PQ 3030/MAO and PQ 3030-BuGeCl3/MAO) acted as weakly coordinating polyanions and stabilized the above cations. BuGeCl3 did not affect the solid-state electronic environment. However, it increased the surface cocatalyst to catalyst molar ratio (Al:Zr), acted as a spacer, increased catalyst activity, and enhanced chain-transfer reactions. The separately fed MAO cocatalyst shifted the equilibrium between Cation 1 and Cation 2 toward the right. Consequently, more Cation 2 was generated, which acted as the effective and active single-site catalytic species producing monomodal PDI. Copyright © 2006 John Wiley & Sons, Ltd.

Ethylbisindenyl zirconium dichloride (Et(Ind)2ZrCl2) and the MAO methylalumoxane (MAO) co-catalyst were heterogenized on Davision silica 955 partially dehydroxylated at 275 °C, following the concept of equilibrium adsorption. The influence of MAO on the electronic environment resulting from the heterogenization was investigated using XPS. Heterogenization of Et(Ind)2ZrCl2 and MAO on the above silica generated two types of zirconocenium cations (Cation 1 and Cation 2), independent of the heterogenization methods. Based on the postulated surface chemistry, Cation 1 is presumed to be in the form of an ion-pair [SiO]−[Et(Ind)2ZrCl]+, whereas Cation 2 is presumed to be a trapped multi-coordinated crown complex of MAO. In the absence of MAO, only Cation 1 is formed. The present study provides some support for the postulated surface chemistry regarding heterogenization of Et(Ind)2ZrCl2 and MAO on silica. Copyright © 1999 John Wiley & Sons, Ltd.

Et(Ind)2ZrCl2 and MAO co-catalyst, which polymerize ethylene and propylene, were heterogenized on partially dehydroxylated Davison silica 955, following the method of equilibrium adsorption. The dispersion of these catalyst components on the silica support was investigated by measuring the spatial concentration profiles of Si, Al, and Zr using a micro-PIXE technique. These components were found to be uniformly distributed over the support irrespective of the variation in the heterogenization procedures and the experimental conditions used. The Si∶Al ratios determined by the micro-PIXE technique were similar to those measured by the spectrophotometric method. However, the Al∶Zr ratios measured by the former were somewhat lower than those determined by the latter. Micro-PIXE measurements confirmed the presence of several trace impurities such as K, Ca, Ti, Fe, Ni, Cu, and Zn which may potentially poison the resulting catalyst.

Nonisothermal, uncontrolled polymerization, conducted in varying mixing regimes, offered a facile methodology to evaluate the influence of several important process development factors such as mixing, reaction exotherm, and thermal perturbations on the catalytic activity and kinetic stability, polymerization performance, and properties of the resulting polymers. Ethylene was homo- and copolymerized with hexene-1 under varying impeller speeds (hence, thermal perturbations), using Ind2ZrCl2 and Et(Ind)2ZrCl2 and the MAO cocatalyst. With respect to the effects of the above process development factors, the following was observed: The reaction exotherm profiles, tracing the polymerization history, qualitatively represented the kinetic profile and the catalytic stability. The unbridged Ind2ZrCl2 was shown to be more stable than the bridged Et(Ind)2ZrCl2. With change in the level of stirring from a diffusion-controlled regime to a nondiffusion-controlled, external gas–liquid mass-transfer resistance-free one, the reaction exotherm and the run time-average catalytic activity increased. So far as the influence of the chiral versus the achiral zirconocene structure is concerned, the copolymer composition distribution and soluble fraction generated by chiral Et(Ind)2ZrCl2 were more sensitive to the mixing conditions and thermal perturbations than were those produced by achiral Ind2ZrCl2. Et(Ind)2ZrCl2 produced higher molecular weight backbones, incorporated more hexene-1 and chain branching, and introduced less crystallinity in the copolymers than did Ind2ZrCl2. The influence of Ind2ZrCl2 on higher-weight homopolymer backbones was opposite to that of Et(Ind)2ZrCl2. Incorporation of hexene-1 significantly decreased the average molecular weights and density and increased the run-time-dependent average catalyst activity. A positive comonomer effect took place. The bulk polymer properties did not critically depend on the mixing state. Thermal perturbations broadened the polydispersity index. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 137–147, 1998

Daily sc injections of phenobarbital at anticonvulsant therapeutic doses for the rat (40 mg/kg) for the first 7 days of life resulted in below normal levels of serum testosterone from around birth to before puberty, normal levels during puberty and above normal levels of the androgen after puberty and in adulthood. Cluster analysis of the plasma testosterone secretory profiles obtained at 15-min intervals from phenobarbital-treated rats at 65 and 165 days of age revealed a significant increase in both the peak amplitudes and their durations resulting in a 100% increase in the amount of hormone secreted during the peak periods. In general, most of the rats (control and experimental) secreted testosterone as two large peaks, each 3 to 4 hr in duration, during the 10-hr lights-on collection period. In addition to permanently disrupting the ultradian profiles of plasma testosterone, neonatal exposure to the barbiturate altered testicular responsiveness to steroidogenic regulatory agents. That is, neonatal exposure to phenobarbital enhanced the responsiveness to exogenous hCG as measured by an above-normal increase in testosterone concentration. Moreover, phenobarbital-induced reductions in serum testosterone levels were delayed in adult rats neonatally exposed to the barbiturate. Whereas a single challenge dose of phenobarbital (1 or 10 mg/kg) reduced serum testosterone concentrations in control animals by almost 80% within 3 hr, a decline in serum androgen levels in the neonatally phenobarbital exposed males was not observed until 12 hr after the challenge dose. These results indicate that postpartum exposure to therapeutic levels of phenobarbital can permanently disrupt testosterone secretory profiles and alter pathways regulating testicular steroidogenesis.

Ca 2+ and Mg 2+ caused a concentration-dependent activation of ATP hydrolysis by mitochondrial membranes of Hymenolepis diminuta , a rat intestinal cestode. Ca 2+ was the more potent, but Mg 2+ the more effective. The Lineweaver-Burk plot yielded K m and V max values of 1.15 mM and 217.4 nmol P i min −1 mg −1 protein for Ca 2+ -dependent activity, and 1.86 mM and 333.3 nmol P i min −1 mg −1 protein for Mg 2+ -dependent activity, respectively. Neither Na + nor K + , nor a combination of the two cations, induced the hydrolysis of ATP. Ouabain, a specific inhibitor of Na + /K + ATPase, did not affect the rate of ATP hydrolysis induced by Mg 2+ alone or in combination with Na + or K + . The membrane-bound enzyme was not affected by neuraminidase and concanavalin A. Ca 2+ and Mg 2+ also induced appreciable hydrolysis of other nucleoside triphosphates by the membranes. Some kwown anthelmintics, e.g. niclosamide, praziquantel and mebendazole, had no effect on ATPase activities. In addition to other compounds including respiratory inhibitors and uncouplers of phosphorylation, ruthenium red, which blocks Ca 2+ influx into the cestode mitochondria, had no influence on the rate of ATP hydrolysis induced by the cations. Triton X-100 was found most suitable for solubilization of both activities. The differences between cestode ATPase and its mammalian counterpart have been discussed.

Low-density polyethylene-based greenhouse films have been monitored for outdoor weather effects by mounting the film on a model greenhouse and on aluminum exposure racks at Dhahran plastic exposure facility. The change in chemical properties was monitored by Fourier transform infrared (FTIR) spectroscopy. The thermal properties were observed by differential scanning calorimetry (DSC) and the drop in percent elongation and stress at break was monitored. It is concluded that greenhouse film mounted on the model greenhouse degraded more in comparison to the film on aluminum racks. The spectral emissions with wavelength between 7 and 14 μm are an important part of the energy losses from the soil and the plants inside a greenhouse. The partial prevention of the dissipation of this thermal energy from the greenhouse film during cool night hours creates a unique environment and influences the degradation reactions in the plastic film Pesticides, mostly sulfur- and halogen-based compounds, can also accelerate the degradation of the film.

Summary: An audit of labour following Caesarean section was carried out over a 70-month-period to assess our management of labour following Caesarean section and to support the hospital quality assurance review progress for obstetric care: 419 patients with 1 previous Caesarean section were given a trial of labour: 314 (75%) women had a vaginal delivery and 105 (25%) had a repeat Caesarean section. The highest failure rate was observed in women whose previous indication for Caesarean section was cephalopelvic disproportion. There were 6 (1.4%) cases of scar dehiscence and 4 (1%) of uterine rupture. Vaginal delivery following Caesarean section is a viable cost-effective, safe procedure in a high quality labour and delivery unit in a developing country.

We determined in nondiabetic women, the relationship of plasma glucose values obtained 2 hours after a 75 g oral glucose challenge test (GCT) at 16-20 weeks' gestation, with the incidence of macrosomia in term deliveries (37-41 weeks' gestation). From 1988-1990, in a systematic screening programme data collected prospectively from 1,331 women were analysed retrospectively. Women with gestational diabetes or impaired glucose tolerance (n = 53) were excluded. The rest (n = 1,278) had no evidence of glucose intolerance including 1,215 women with normal plasma glucose by GCT (7.8 mmol/L 2 hours after 75 g oral glucose load) and 63 women with abnormal GCT but not abnormal value at a glucose tolerance test. The GCT values were divided into 5 groups: Group A (4.5 mmol/L), B (4.5-5.5 mmol/L), C (5.6-6.6 mmol/L), D (6.7-7.7 mmol/L) and E (7.8 mmol/L). The variables studied were age, parity, gestational age at delivery and incidence of macrosomia. Using4 kg birth-weight as the definition of macrosomia, the incidence increased from 1.2% to 9.5% with increasing plasma glucose values in the GCT from Group A (4.5 mmol/L) to E (7.8 mmol/L). Similar trends of increasing incidences from 7.2% to 15.8% and 2.9% to 9.5% were noted when 90th and 95th birth-weight percentiles, respectively were used as definitions of macrosomia. The test of linear trend in this association was significant (p0.01). These results were not influenced by parity or gestational age at delivery.(ABSTRACT TRUNCATED AT 250 WORDS)

Maternal mortality remains a scourge of motherhood even as we approach the end of the 20th century. The magnitude of maternal mortality in developing countries and its disparity with similar statistics from the developed world1) has touched a responsive cord in some policy makers and health services officials. With this background in mind, this commentary presents some of the problems encountered in attempting to reduce maternal mortality, and by asking some pertinent questions — offer some solutions.

Type 2 diabetes mellitus is a metabolic disease leading to microvascular and macrovascular complications including coronary artery disease and stroke. Management of diabetes has been challenging, particularly in the presence of the enormous prevalence of obesity. In recent years, various inhibitors of the enzyme dipeptidyl peptidase (DPP)-4 have been developed to treat diabetes. The enzyme DPP-4 cleaves incretins, which, among other functions, stimulate insulin and suppresses glucagon. Inhibition of this enzyme results in an increase in the half-life and the sustained physiologic action of incretins, leading to an improvement in hyperglycemia. One such agent, namely sitagliptin (MK-04,310), has been introduced into the United States market, and another agent, vildagliptin (LAF237), is being used in Europe and elsewhere. This article is intended to evaluate the effectiveness of DPP-4 inhibitors as a therapeutic modality for managing type 2 diabetes. The authors conducted a literature search of various databases to identify the clinical trials involving the DPP inhibitors and concluded that the DPP-4 inhibitors, for example, sitagliptin and vildagliptin, are efficacious for managing diabetes as monotherapy or combination therapy.

We have previously reported that Ca2+ influx into the mitochondria of Hymenolepis diminuta, a rat intestinal cestode, takes place through an electrophoretic uniport system. Sodium and lithium were found to induce efflux of 45Ca2+ from the mitochondria of H. diminuta. The two cations induced the efflux in a hyperbolic and linear fashion, respectively. The efflux as well as an exchange of external Ca2+ with internal 45Ca2+ was inhibited by lanthanum. The type of Ca2+ transport system in the cestode organelle has been discussed and compared with that of the host (mammalian) counterpart.

EDITORIAL COMMENT: We accepted this paper for publication because readers may wish to use it as a model for scrutiny of their own hospital statistics, especially in Australia where the hysterectomy rate is probably considerably higher than in Pakistan. Summary: Hysterectomy in Pakistan, like in other parts of the world is considered to be overused in a number of cases. As a part of a quality assurance process at the Aga Khan University Medical Centre, Karachi, 376 hysterectomies performed between January, 1987 and December, 1989 were retrospectively analysed and the results are presented. In 250 (66.5%) cases, where pathology was expected to be found, the hysterectomy was considered justified if the preoperative diagnosis was verified by the pathology report of if significant alternate pathology was present. In 126 (33.5%) cases, where no pathology was expected to be found ‘validation criteria’ were used to ascertain justification of the procedure. The results showed justification rates of 83% for recurrent uterine bleeding, 85% for adenomyosis, 90% for adnexal masses and endometrial carcinoma, 95% for fibroids, 97% for pelvic relaxation and 100% each for pregnancy catastrophe, endometriosis, chronic pelvic inflammatory disease and premalignant disease of uterus and cervix. In general 92.0% of all hysterectomies in this series were justified.