Clogging and Unclogging of Hydrocarbon-Contaminated Nanochannels.

The recent advantages of the fabrication of artificial nanochannels enabled new research on the molecular transport, permeance, and selectivity of various gases and molecules. However, the physisorption/chemisorption of the unwanted molecules (usually hydrocarbons) inside nanochannels results in the alteration of the functionality of the nanochannels. We investigated contamination due to hydrocarbon molecules, nanochannels made of graphene, hexagonal boron nitride, BC2N, and molybdenum disulfide using molecular dynamics simulations. We found that for a certain size of nanochannel (i.e., h = 0.7 nm), as a result of the anomalous hydrophilic nature of nanochannels made of graphene, the hydrocarbons are fully adsorbed in the nanochannel, giving rise to full uptake. An increasing temperature plays an important role in unclogging, while pressure does not have a significant role. The results of our pioneering work contribute to a better understanding and highlight the important factors in alleviating the contamination and unclogging of nanochannels, which are in good agreement with the results of recent experiments.

Correlation between pre-ramadan glycemic control and subsequent glucose fluctuation during fasting in adolescents with Type 1 diabetes.

BACKGROUND: Even though patients with type 1 diabetes mellitus (T1DM) are exempted from fasting, the vast majority elect to fast against the advice of their healthcare providers. We have previously reported the incidence of wide fluctuations in blood glucose (BG) along with "unrecognized" severe hypoglycemia during Ramadan fasting in adolescents with T1DM. This report compares the continuous glucose monitoring (CGM) data during fasting in adolescents with T1DM according to their Pre-Ramadan diabetes control. METHODS: Children and adolescents with T1DM who intended to fast the month of Ramadan were asked to wear the CGM during fasting for a minimum of 3 days. Hypoglycemia, hyperglycemia, and severe hyperglycemia were identified as BG <70 mg/dL (3.9 mmol/L), BG 201-300 mg/dL (11.2-16.7 mmol/L), or BG >300 mg/dL (16.7 mmol/L) respectively, while normoglycemia was identified as BG 70-200 mg/dL (3.9-11.1 mmol/L). Patients were categorized as well-controlled (Group 1) and poorly controlled (Group 2) if the pre-fasting HbA1C was ≤8% (64 mmol/mol) and >8%, respectively. We compared the mean BG and the percentages of time spent in hypoglycemia, hyperglycemia, and severe hyperglycemia between the two groups using Chi-square (significant difference when P value was <0.05). RESULTS: A total of 21 patients were enrolled (15 females), age 15 ± 4 years, duration of diabetes 6 ± 3 years, and HbA1C 8.5 ± 1.0% (70 mmol/mol). There were 7 subjects in Group 1, mean HbA1C 7.5 ± 0.4, and 14 subjects in Group 2, mean HbA1C 9.1 ± 0.9. The mean ± SD BG was 174 ± 76 mg/dL versus 199 ± 98, (P < 0.05) in Group 1 and Group 2, respectively. The percentages of hypoglycemia, hyperglycemia, and severe hyperglycemia were significantly higher in Group 2, while there was a higher percentage of normoglycemia in Group 1. The overall durations of hypoglycemia, hyperglycemia, and severe hyperglycemia in Group 2 were longer by 30, 14, and 135%, respectively, than those in Group 1. CONCLUSIONS: Glycemic control before Ramadan in adolescents with T1 DM appears to correlate with blood glucose profile during Ramadan fasting. Our data suggest that optimal glycemic control before Ramadan may reduce the potential risks associated with fasting and minimize glucose fluctuation.

Impacts of overgrazing in a long term traditional grazing ecosystem on vegetation around watering points in a semi-arid rangeland of North-Eastern Iran.

In this study, the effects of livestock overgrazing on vegetation of the critical area around livestock watering points in a traditional grazing ecosystem was investigated on a semi-arid rangeland in North-East of Iran. Transects were placed in 8 geographical directions around watering points and samples were taken systematically. In each experimental plot, 4 m2, percentage of canopy cover, abundance, density and species richness of vegetation were calculated. The results of this study showed that the percentage of canopy cover, density and species richness were changed with distance from watering points. Critical area immediately adjacent to watering points was dominated by unpalatable Peganum harmala and contained of ruderal species such as Sophora sp. Adjacent to this was a zone dominated by species of low palatability such as Acantholimon sp. and Hulthemia persica. In areas most distant from watering points relative importance of moderately palatable species such as Artemisia herba-alba increased. These results show the negative impacts of overgrazing on vegetation and palatability in a traditional grazing ecosystem, which may indicate the necessity of a monitoring programme, to manage livestock grazing and watering points in North-East of Iran.

Spectrophotometric determination of captopril with DTNB reagent in pharmaceutical formulation.

A simple and sensitive spectrophotometeric method has been developed for the determination of captopril in its dosage form. The method is based on the reaction of the drug with DTNB reagent in pH 8 to produce a yellow coloured species measurable at 412 nm. The absorbance-concentration plot is linear over the range 1-10 x 10(-5) M with correlation coefficient of 0.997. The molar absorptivity and minimum delectability were 13553 and 3.2 x 10(-7) respectively. The proposed method was applied successfully for determination of captopril in its tablets form. The mean quantity and recovery were found to be 25.01+/-2% and 100.04+/-2% (each tablet contain 25 mg captopril). Quantification of the same tablets was determined by a standard method such as HPLC. The mean quantity of each tablet was found to be 25.07+/-1.22% by using HPLC method. It was not statistically, significant difference between Ellman's and HPLC method. This proposed method can be successfully applied to the determination of captopril in water and its dosage form and can use instead HPLC.

Decreased superoxide anion production in cultured human promonocyte cells (THP-1) due to polyphenol mixtures from olive oil processing wastewaters.

The purpose of this study was to examine whether human monocytic line THP-1 after differentiation into adherent macrophages, taken as a model of human macrophages implicated in atheroma, is able to produce lower quantities of O(2)(*)(-) either in the presence of polyphenol-rich olive oil wastewater (OWW) fractions or after OWW preincubation and withdrawal from the medium. In these respective conditions, the purpose was to examine the scavenging activity and the cell action of OWW toward O(2)(*)(-) production. It was clearly seen that OWW fractions lowered the O(2)(*)(-) production in both conditions, leading to the conclusion that they were able to scavenge O(2)(*)(-) and to depress O(2)(*)(-) production in the cell. Given the role of O(2)(*)(-) in LDL oxidation and oxidized LDL in atheroma, these results support an antiatherogenic role of OWW and its potential utilization as a food complement.

The fatty acid bimodal action on superoxide anion production by human adherent monocytes under phorbol 12-myristate 13-acetate or diacylglycerol activation can be explained by the modulation of protein kinase C and p47phox translocation.

We studied the translocation of protein kinase C (PKC), the endogenous phosphorylation and presence in the membrane fraction of p47phox (the 47-kDa cytosolic component of the phagocyte NADPH oxidase), and the O-.2 production in human adherent monocytes (HAMs). This was performed under phorbol myristate acetate (PMA) or diacylglycerol stimulation after cell preincubation in the presence of either 13-methyltetradecanoate or arachidonate. At 3 nM and 30 microM, both fatty acids had enhancing and depressing effects, respectively, on PKC translocation and O-.2 production strictly depending on the PMA- or diacylglycerol-stimulated state of the cell. Endogenous phosphorylation and membrane presence of p47phox were markedly reinforced in PMA-stimulated HAMs in the presence as compared to the absence of 13-methyltetradecanoate. These results emphasize the fact that in intact cells the capacity of both FAs to potentiate or depress the HAM O-.2 production is mediated by a direct action on the PKC membrane translocation leading to a simultaneous endogenous phosphorylation and membrane translocation of p47phox. They confirm the recent findings (Kadri-Hassani, N., Léger, C. L., and Descomps, B. (1995) J. Lipid Med. Cell Signal. 11, 159-173) on the PKC-mediated, adherent monocyte-specific capacity of these fatty acids and others (with the exception of linear saturated fatty acids) to enhance the PMA-stimulated O-.2 production at nanomolar concentrations and to depress it at micromolar concentrations.

Bimodal action of fatty acids on PMA-stimulated O2.- production in human adherent monocytes.

Not only unsaturated linear fatty acids, but also saturated monomethyl-branched fatty acids (MMBFAs), are provided by food. They are capable of penetrating into the membrane lipids and promoting lipid disorder. Both NADPH oxidase and protein kinase C (PKC) are bound to cell cytoplasmic membranes and are responsive to unesterified fatty acids (UEFAs). We found that the O2.- NADPH oxidase-mediated production of human adherent monocytes was modified by unsaturated linear and saturated branched UEFAs only in the presence of phorbol myristate acetate. This result together with our inhibition data indicated an action strictly linked to PKC activity. The type and intensity of action depended on the UEFA concentrations and chain structure. Nanomolar concentrations showed potentiating effects whereas micromolar (< CMC) concentrations displayed depressant influences MMBFAs were generally more active than the other FAs. With respect to the micromolar depressant effect, oleate and linoleate were as active and docosahexaenoate nearly as active as MMBFAs. As assessed by iso-15:0 or arachidonate action, such bimodal alteration did not occur in non-adherent monocytes and neutrophils. Certain UEFAs could be considered as 'cellular' anti-oxidants on the sites of adherent-monocyte recruitment.

[Modulation by some fatty acids of protein kinase C-dependent NADPH oxidase in human adherent monocyte: mechanism of action, possible implication in atherogenesis]. / Modulation par certains acides gras de l'activité NADPH oxydase dépendante de la protéine kinase C chez le monocyte adhérent human: mécanisme d'action, implication possible dans l'athérogénèse.

It is largely admitted nowadays that the early stage of the atherosclerotic lesion involves formation of oxidized (and minimally oxidized) low-density lipoprotein. Their properties are briefly reviewed. It is recalled that a lipolytic process also takes place both at the lumenal surface and in the subendothelial space of the vessels implying lipoprotein lipase (LpL) activity. Recent studies emphasize the role of LpL in accumulating LDL in the vascular tissue (Rutledge & Golberg, J. Lipid Res., 1994, 35, 1152-1160), but the role of LpL-generated unesterified fatty acids (UEFA) in these two locations and their possible implication in atherogenesis are largely neglected. Physiological and pathophysiological significance of UEFA in the human adherent monocyte modulation of the superoxide anion (O2.-) production has been examined by our group, leading to a possible mechanism of modulation of LDL oxidative modification. The O2.- production-modulating effect of a 30-min UEFA preincubation has been studied in intact human adherent monocytes (HAM) after stimulation by a direct effector of protein kinase C (PKC). It has been established that UEFA alone (in the absence of PKC effectors) were not able to modulate the O2.- production of HAM whereas they had such a capacity in the presence of PKC effectors, phorbol myristate acetate (PMA) or diacylglycerol (DAG). In this case inhibitors of PKC such as GF 109203 X suppressed the modulating effect. UEFA have also been shown to possess a bimodal action in the presence of PKC effectors: they depressed or enhanced O2.- production at micromolar or nanomolar concentrations, respectively. All these results contrasted with others obtained in neutrophils or nonadherent monocytes, suggesting an absolute requirement of PKC for the phagocyte-NADPH oxydase (PHOX) activation especially in the case of HAM. In HAM, the maximal enhancing effects were obtained with monomethyl ramified saturated (MMRS) and linear unsaturated (LU) FAs such as arachidonic, eicosapentaenoic and docosahexaenoic acids (with exception of oleic, linoleic and linolenic acids which were without effect), whereas the maximal depressing effects were obtained with MMRS-FAs and LU-FAS such as oleic, linoleic and docosahexaenoic acids. Further investigations in HAM led us to examine the UEFA capacity at modulating the translocation of PKC, on the one hand, and the endogenous phosphorylation and membrane translocation of p47phox, on the other, in the presence of PMA or DAG. Using 13-methyl myristic (iso15:0) as FA model, it has been established that i) it was able to amplify or diminish PKC translocation at nanomolar and micromolar concentrations, respectively (this was also the case with arachidonic acid) ii) it enhanced and depressed the endogenous phosphorylation and the membrane translocation of p47phox at nanomolar/micromolar concentrations and iii) it was inactive in the absence of PMA or DAG. Taken together, our results strongly suggest that the active UEFA act directly on the monocyte PKC, modifying its kinase activity through interactions with PMA/DAG binding site of the regulatory domain of the protein. This leads to modulate the phosphorylation and translocation of p47phox, which in turn allows the assembling of the active PHOX complex and triggers the O2.- production. The direct action of UEFA on the PKC regulatory-domain known to strongly interact with the membrane lipids was also supported by the fact that linear saturated FAs that have already been reported to be unable to penetrate a lipid layer were devoided of effect on monocytic O2.- production. The free form of oleic and linoleic acids and, to a lesser extent, docosahexaenoic acid (in the case of oral administration of fish oil) are present at micromolar concentrations in the plasma.(ABSTRACT TRUNCATED AT 400 WORDS)

Vector competence of autogenous and anautogenous Culex pipiens mosquitoes for Wuchereria bancrofti.

Vector competence of autogenous and anautogenous Culex pipiens; derived from North Sinai Governorate, Egypt, for the human filaria parasite Wuchereria bancrofti was studied. After feeding on the same microfilaremic volunteers both biotypes were readily infected with the parasite (infection rates > 80%) and supported its development to the infective stage within 11 - 12 days. Infective rates of both autogenous and anautogenous mosquitoes were similar (> 95%). However, autogenous Cx. pipiens developed significantly less number of infective stage larvae (4.7 +/- 1.4 L3 / female) than did anautogenous siblings (6.7 +/- 3.6 L3 / female) (P < 0.05). Moreover, autogenous females were observed to contain twice the number of L3 larvae in the thoracic muscles and less larvae in the head region compared to autogenous counterparts. Vector competence characteristics of Cx. pipiens derived from a filariasis endemic area in Qalubiya Governorate were similar to those of anautogenous mosquitoes of North Sinai. These findings indicate that autogenous Cx. pipiens may be less efficient vector of W. bancrofti in endemic areas of Egypt.

Increase in Specific Proteins and mRNAs Following Transient Anoxia - Aglycaemia in Rat CA1 Hippocampal Slices.

Incorporation of [35S]methionine into proteins and two-dimensional gel autoradiograms was used to characterize early post-anoxia - aglycaemia protein synthesis in the CA1 area of rat hippocampal slices maintained in vitro. We have compared the effects of 3 - 4 min and 5 - 10 min insults, since the former but not the latter produces a reversible block of synaptic transmission (see companion paper). An insult of between 3 min 30 s and 4 min induces a transient increase in the labelled proteins during the first hour of reoxygenation, as compared to control. The increase in protein synthesis is conspicuous for several proteins, including actin, alpha-tubulin and heat-shock proteins (hsp70c and hsp90), as determined by immunoblotting. In the case of alpha-tubulin, we show with in situ hybridization and polymerase chain reaction procedures that the increase in protein synthesis is associated with a marked increase in the expression of the corresponding messenger RNAs. The results demonstrate that, in addition to regulatory proteins such as hsps, the synthesis of several polypeptides, including those associated with the cytoskeleton, is altered in anoxic damage.

[Malarial problems and the trans-Saharan highway]. / Problèmes palustres et route transsaharienne.

In Maghreb, malaria eradication is near. In particular, no indigenous strains of P. falciparum have been found for ten years. The few remaining cases of malaria are of P. vivax. In the Sahelian area, on the other hand, malaria eradication failed with P. falciparum and the efficient vector A. gambiae (s.l.). Until now, the Sahara desert separated these two areas. With construction of a trans-saharan highway, the situation is very different. Now, tropical malaria circulates in Maghreb and Sahara oases in the same way as vectors. However, it seems that local vectors in Maghreb (A. labranchiae) and in Sahara (A. multicolor et A. sergenti) are not efficient vectors for tropical strain of P. falciparum. These observations must be confirmed because there are probably different anopheles populations with different vectorial capacity in the same anopheles species and different plasmodial strains with different infective capacity in the same plasmodial species. Meanwhile a dangerous potential situation exists, the temporary or permanent colonization of some stations in Sahara, in Maghreb (?) by A. gambiae the efficient vector of tropical strains of P. falciparum. From now on, important efforts of Prevention and Control for vectors and malaria must be developed with large intensity in Saharan oases and in Maghreb.

Cholelithiasis in children with sickle cell disease.

A group of 47 children with homozygous sickle cell disease ranging in age from 2 to 18 years was studied for the prevalence of gallstones. All of these patients had oral cholecystogram and cholecystosonogram. Eight of the 47 patients (17%) had gallstones both on oral cholecystography and on cholecystosonography. These eight patients had a history of recurrent abdominal pain usually localized to the right upper quadrant. All were admitted on several occasions for sickle cell abdominal crises and four of these were admitted for acute hepatic crisis. These patients have undergone elective cholecystectomy and gallstones were found in every patient. The patients have been followed up from seven to 17 months after cholecystectomy and none have had abdominal symptoms or required hospitalization for abdominal crises.

A safety maneuver for closure of patent ductus arteriosus.

To avoid the risk of cut-thru during ligation or division of a patent ductus arteriosus, a simple maneuver is described to lower the pressure in the aorta and pulmonary artery by manual compression just before clamping or ligating the ductus. To gain sufficient length of the ductus for triple ligation, a technic is described utilizing the adventitia on the aortic end to prevent the linen tape or the silk ligature from slipping on the ductus.

Ultrasonic diagnosis and aspiration of loculated pleural effusion.

A method of localizing and evacuating pleural effusions under visual control is described which in the author's opinion is an improvement and enhancement over current procedures. This method is easy, rapid, safe and causes no distress to the patient. On many occasions, failures at puncture of loculated fluid by conventional methods can successfully be accomplished under ultrasonic guidance.