Criegee intermediates and their impacts on the troposphere.

Criegee intermediates (CIs), carbonyl oxides formed in ozonolysis of alkenes, play key roles in the troposphere. The decomposition of CIs can be a significant source of OH to the tropospheric oxidation cycle especially during nighttime and winter months. A variety of model-measurement studies have estimated surface-level stabilized Criegee intermediate (sCI) concentrations on the order of 1 × 104 cm-3 to 1 × 105 cm-3, which makes a non-negligible contribution to the oxidising capacity in the terrestrial boundary layer. The reactions of sCI with the water monomer and the water dimer have been found to be the most important bimolecular reactions to the tropospheric sCI loss rate, at least for the smallest carbonyl oxides; the products from these reactions (e.g. hydroxymethyl hydroperoxide, HMHP) are also of importance to the atmospheric oxidation cycle. The sCI can oxidise SO2 to form SO3, which can go on to form a significant amount of H2SO4 which is a key atmospheric nucleation species and therefore vital to the formation of clouds. The sCI can also react with carboxylic acids, carbonyl compounds, alcohols, peroxy radicals and hydroperoxides, and the products of these reactions are likely to be highly oxygenated species, with low vapour pressures, that can lead to nucleation and SOA formation over terrestrial regions.

Comparison of modified Friedewald's formula with direct measurement of low-density lipoprotein cholesterol in Bangladeshi population.

A modification of Friedewald's formula to estimate serum low-density lipoprotein cholesterol (LDLC) up to serum triglyceride (TG) level of 11.3 mmol/L in Bangladeshi population has recently been published. The aim of this study was to compare the modified formula with direct measurement of LDLC in Bangladeshi population in a different setting. One thousand and fifty two specimens from adult subjects were analyzed. Serum total cholesterol (TC), high-density lipoprotein cholesterol (HDLC), LDLC and TG were measured by standard methods. The modified Friedewald's formula was applied to estimate LDL cholesterol concentration. Results were expressed as mean ± SD and calculated LDLC was compared with measured LDLC by two-tailed paired t test, Bland-Altman plot for absolute bias, Pearson's correlation coefficients of calculated LDLC with measured LDLC and Passing & Bablok regression equation of calculated LDLC against measured LDLC. The mean ± SD of measured LDLC was 2.98 ± 0.82 mmol/L. LDLC calculated by modified Friedewald's formula was 2.77 ± 0.86 mmol/L. The mean absolute bias was -0.20 ± 0.32 mmol/L, Pearson's correlation coefficient (r) was 0.9293 (P < 0.0001) and Passing & Bablok regression equation was y = - 0.3856+1.0597x for modified formula up to serum TG ≤ 11.3 mmol/L. Compared to original Friedewald's formula, performance of the modified Friedewald's formula was better up to serum TG ≤ 4.52 mmol/L. The study reveals that the modified Friedewald's formula may be used to calculate LDLC approximately in Bangladeshi population.

Analysis of low concentration reduced sulfur compounds (RSCs) in air: storage issues and measurement by gas chromatography with sulfur chemiluminescence detection.

Reduced sulfur compounds (RSCs) were measured at low concentrations in small volume air samples using a cryo-trapping inlet system and gas chromatograph outfitted with a sulfur chemiluminescence detector (GC-SCD). The relative sensitivity of the system to the RSCs follows the sequence H(2)S6 years from initial coating) saw significant loss of H(2)S and CH(3)SH within 2 days, while the more recent generation canister (<1 year from initial coating) yielded percent recoveries of RSCs in the range of 85% (H(2)S and CH(3)SH) to 95% (OCS, DMS and CS(2)) after 7 days of storage, suggesting that these canisters may be suitable for the short-term storage of low level RSCs. The development of this low concentration, low sample volume method is well suited for measuring RSC gas fluxes from natural soils in laboratory incubations and in field flux chamber studies.

Effects of temperature and soil moisture on methyl halide and chloroform fluxes from drained peatland pasture soils.

A series of laboratory-based incubations using a stable isotope tracer technique was applied to measure the net and gross fluxes of CH(3)Cl and CH(3)Br as well as the net fluxes of CHCl(3) from surface soils of the Sacramento-San Joaquin Delta of California. Annually averaged flux measurements show that these mineral/oxidized peat soils are a net source of CH(3)Cl (140 ± 266 nmol m(-2) d(-1)) and CHCl(3) (258 ± 288 nmol m(-2) d(-1)), and a net sink of CH(3)Br (-2.3 ± 4.5 nmol m(-2) d(-1)). Gross CH(3)Cl and CH(3)Br fluxes are strongly influenced by both soil moisture and temperature: gross production rates of CH(3)Cl and CH(3)Br are linearly correlated with temperature, whereas gross consumption rates exhibit Gaussian relationships with maximum consumption at soil moisture levels between 20 and 30% volumetric water content (VWC) and a temperature range of 25 to 35 °C. Although soil moisture and soil temperature strongly affect consumption rates, the range of gross consumption rates overall is limited (-506 ± 176 nmol m(-2) d(-1) for CH(3)Cl and -12 ± 4 nmol m(-2) d(-1) for CH(3)Br) and is similar to rates reported in previous studies. CHCl(3) fluxes are not correlated with methyl halide fluxes, temperature, or soil moisture. The annual emission rates of CHCl(3) from the Sacramento-San Joaquin Delta are found to be a potentially significant local source of this compound.

The effect of losartan and carvedilol on vasopressor responses to adrenergic agonists and angiotensin II in the systemic circulation of Sprague Dawley rats.

1 Interaction between renin-angiotensin (RAS) and sympathetic nervous systems (SNS) was investigated by examining the effect of cumulative blockade of angiotensin II (Ang II) and adrenergic receptors in normal Sprague Dawley rats. 2 Rats were treated with losartan (10 mg/kg), carvedilol (5 mg/kg), or losartan plus carvedilol (10+5 mg/kg) orally for 7 days. On day 8, the animals were anaesthetized with pentobarbitone and prepared for systemic haemodynamic study. Dose-response relationships for the elevation of mean arterial pressure or change in heart rate (HR) in response to intravenous injections of noradrenaline (NA), phenylephrine (PE), methoxamine (ME) and Ang II were determined. 3 Losartan or the combination of losartan with carvedilol blunted vasopressor responses to ME and Ang II. Dose-response relationships for agonist action on HR were significantly inhibited by all treatments except for the combination of losartan and carvedilol on the decrease in HR induced by PE. Carvedilol decreased vasopressor responses to NA, PE and Ang II, and HR responses to NA, ME and Ang II. Combination treatment produced similar effects to losartan on the vasopressor and HR responses but had a greater effect on vasopressor responses to ME and Ang II, and on HR responses to NA and Ang II than carvedilol alone. 4 It is concluded that peripheral vasoconstriction induced by Ang II is partly mediated by adrenergic action and that the vasopressor responses to adrenergic agonists depend on an intact RAS. These observations suggest an interactive relationship between RAS and SNS in determining systemic haemodynamic responses in 'normal' rats.

Socio-demographic characteristics of children infested with scabies in densely populated communities of residential madrashas (Islamic education institutes) in Dhaka, Bangladesh.

BACKGROUND: Outbreaks of scabies in institutions and the socio-economic consequences have not been reported from overpopulated countries such as Bangladesh. STUDY DESIGN: A community-based study among children from six residential Islamic education institutes (madrashas) in Dhaka. Multistage random sampling was used. OBJECTIVES: To study the socio-economic profile, water-sanitation facilities, personal hygiene and living conditions of these children. METHODOLOGY: Direct interviews were used to collect the data and clinical check up was performed in all children. RESULTS: In total, 492 children received clinical check-ups; 92.5% were boys (mean age: 11.2+/-2.4 years). 63.4% of fathers and 98.5% of mothers were either illiterate or had only received primary education, 55.1% of fathers were in low-paid labouring jobs, and 99% of mothers were housewives. Of the 98% of children who had scabies, 71% had been re-infected (96% during the winter). Randomly assigned anti-scabies drugs revealed an average cure rate of 85.5%. Seventy-four percent of children were living in poorly ventilated buildings with overcrowded sleeping arrangements. They had poor personal hygiene: 21% shared towels; 8% shared undergarments; 30% shared bed linen; and 81% kept their used clothes on a communal line or shelf. Sanitation was also poor: 39% bathed infrequently, although 97% carried out mandatory ablution. Most children (61%) washed their clothes (including undergarments) two or three times a fortnight, 35% did so every 2-3 days, and 3.7% washed their clothes on alternative days. Disease severity and re-infection were associated with infrequent washing of clothes (P<0.001) and bed linen (P<0.001), overcrowded sleeping arrangements (P<0.001) and infrequent bathing (P<0.001) with soap (P<0.001). This was further related to household income (P<0.001 for both). CONCLUSION: The study findings have potentially dangerous implications for public health. Immediate attention should be given to developing a sustainable long-term intervention programme to combat scabies hyperendemicity, and to save thousands of children from impending complications.

A study of blood glucose in paediatric laparoscopy.

BACKGROUND: There are few studies on stress responses to laparoscopic surgery in children. This study was conducted to assess the blood glucose levels in children undergoing laparoscopy. We also studied the effect of two different intravenous (i.v.) solutions on blood glucose in open and laparoscopic procedures. METHODS: One hundred and twenty healthy children, aged 2-12 years, undergoing either open or laparoscopic surgery, were randomized to receive either dextrose normal saline (DS) or Ringer's lactate peri-operatively (RL). All patients had blood glucose measurements performed immediately after induction but prior to the i.v. infusion of any fluid. Blood glucose was again measured 1 h after induction in the open cases and 1 h after insufflation in the laparoscopy cases. RESULTS: In the groups, baseline blood glucose values were comparable. In all groups, blood glucose concentrations increased from the immediate post-induction (baseline) values. When RL was infused, the 1-h blood glucose was higher in the laparoscopy group as compared with the open group. However, when DS was infused the difference between the 1-h blood glucose in the open and laparoscopic procedures was not statistically significant. In the laparoscopy group, the 1-h blood glucose value was significantly higher in the patients receiving dextrose solution. CONCLUSION: Laparoscopic procedures in children are associated with a rise in blood glucose levels similar to open surgery. The hyperglycaemic response was more pronounced when dextrose-containing solutions were infused peri-operatively.

Silver(I) complexes of 2-(2-aminoethyl)pyridine: nitrate and perchlorate salts of bis[mu-2-(2-aminoethyl)pyridine-kappa(2)N:N']disilver(I).

2-(2-Aminoethyl)pyridine (2-aep, C7H10N2) acts as a bridging ligand in bis[mu-2-(2-aminoethyl)pyridine-kappa(2)N:N']disilver(I) dinitrate, [Ag2(2-aep)2](NO3)2, and bis[mu-2-(2-aminoethyl)pyridine-kappa(2)N:N']disilver(I) diperchlorate, [Ag2(2-aep)2](ClO4)2. Both salts contain the dinuclear [Ag2(2-aep)2]2+ cation, which possesses a crystallographic inversion center. The Ag...Ag distance is 3.1163 (5) A for the nitrate and 3.0923 (3) A for the perchlorate salt, and may indicate a weak d(10)-d(10) interaction in each case. Essentially linear coordination of the AgI atom is perturbed by weak coordination to the anionic O atoms. These latter interactions organize the dinuclear cations into one-dimensional polymeric chains in the crystals of the two salts.

Efficacy of an anti-fertility vaccine based on mammalian gonadotrophin releasing hormone (GnRH-I)--a histological comparison in male animals.

A N-terminal modified gonadotrophin releasing hormone (GnRH-I, tetanus toxoid-CHWSYGLRPG-NH2) conjugate was evaluated histologically in a number of male animal species (mice, dogs and sheep). The immunogen has previously been shown to be highly effective in rats, by suppressing both steroidogenesis and spermatogenesis. However, cross-species efficacy of peptide vaccines is known to be highly variable. Therefore, a comparative evaluation of reproductive tissues from animals immunized against this immunogen adsorbed onto an alum-based adjuvant was made. The sheep and dogs were chosen, as use of anti-fertility vaccines in these species is important in farming and veterinary practice. Changes in testicular size were measured during the immunization period and the greatest alteration (attributed to gonadal atrophy) was observed in the rat. Following euthanasia, the testicular tissue was evaluated for spermatogenesis. The most susceptible species to GnRH-I ablation was the rat, which showed significant (P < 0.0001) arrest in spermatogenesis compared with untreated controls. Testicular sections taken from treated animals were completely devoid of spermatozoa or spermatids, in comparison with 94% of the untreated controls showing evidence of spermatogenesis. The immunized mice and rams also showed significant arrest (P < 0.0001). There was a 30-45% decrease in spermatogenesis and total azoospermia was not apparent. However, the least responsive were the dogs, which showed little significant variation compared to untreated animals and only a 5% decrease in activity. A comparison of the specific IgG response to GnRH-I indicated that in sheep and dogs the response was not maintained, unlike in rodents, suggesting that suppression of fertility may be due to differences in immune responses in different animal species.