Environmental factors and refractive error in Chinese schoolchildren

We surveyed and assessed 2,323 schoolchildren aged seven to 17 years from four schools in China, two in the city of Tianjin and the other two in a neighbouring rural village, Ban Chau, to investigate the prevalence of refractive error and its relationship with environmental factors. Every child from each of the participating classes was recruited in this study to avoid self-selection. A questionnaire was issued which queried some aspects of the child's visual habits and home. Refraction was canied out using the Canon R-22 autorefractor. The degree and frequency of myopia in these children increased almost linearly from age seven to 17 years. There was little difference between the urban and rural groups. Of the factors explored, the number of hours spent on near work showed the best correlation with the degree of myopia, albeit only weakly.     

Reactive oxygen species and acute renal failure

Acute renal failure is commonly due to acute tubular necrosis (ATN), the latter representing an acute, usually reversible loss of renal function incurred from ischemic or nephrotoxic insults occurring singly or in combination. Such insults instigate a number of processes-hemodynamic alterations, aberrant vascular responses, sublethal and lethal cell damage, inflammatory responses, and nephron obstruction-that initiate and maintain ATN. Eventually, reparative and regenerative processes facilitate the resolution of renal injury and the recovery of renal function. Focusing mainly on ischemic ATN, this article reviews evidence indicating that the inordinate or aberrant generation of reactive oxygen species (ROS) may contribute to the initiation and maintenance of ATN. This review also discusses the possibility that ROS may instigate adaptive as well as maladaptive responses in the kidney with ATN, and raises the possibility that ROS may participate in the recovery phase of ATN.     

The renal vascular effects of meglumine diatrizoate.

Left ventricular injection of meglumine diatrizoate caused an initial (1-10 minute) decrease in renal vascular resistance followed by a late (30-minute) increase in renal vascular resistance. The late renal vasoconstrictor response was not blocked by bilateral cervical vagotomy, by renal adrenergic blockade or by renal alpha adrenergic receptor blockade; it was blocked by prior extracellular fluid volume expansion and blockade of the response of the kidney to angiotensin II. There was no effect on intrarenal distribution of blood flow. In the kidney perfused at constant flow, injections of meglumine diatrizoate into the kidney resulted in early renal vasodilation (1-5 minutes) with a return to control renal vascular resistance by 7 minutes; no vasoconstriction was observed. The renal vasodilatation was not abolished by prior treatment with atropine. Vasodilator responses identical to those observed with meglumine diatrizoate were obtained with 4.5% NaCl (equiosmolar to meglumine diatrizoate); no response was obtained with 0.9% NaCl. When given into either the left ventricle or the renal artery, meglumine diatrizoate caused an early reversible depression in renal extraction of para-aminohippurate; both 0.9 and 4.5% NaCl were without effect. The renal vasodilation produced by meglumine diatrizoate initially appears to be caused by its hyperosmotic properties; the late renal vasoconstrictor response appears to be mediated via an activation of the renin-angiotensin system. The depressive effect of meglumine diatrizoate on the renal extraction of para-aminohippurate is not related to its osmotic properties but rather to an effect of the organic iodinated molecule on cellular transport of para-aminohippurate.     

A pH-measuring radio capsule for the alimentary canal

Merits of a new telemetering system designed to measure pH in the gastrointestinal tract are briefly discussed in conjunction with present technics. In vitro evaluation of the Corning Acido Capsule system includes (a) temperature stability measurements, (b) speed of response to abrupt changes in pH, (c) accuracy of pH indication in the range of pH 1 to pH 8, and (d) long-term stability of the system. The data show that the pH determination is accurate to ± 0.2 pH units for tests lasting up to 18 hours. Preliminary in vivo evaluations indicate that the capsule system provides a convenient and accurate method of measuring hydrogen-ion activity in the alimentary canal, and suggest further in vivo evaluation of the system.The authors would like to acknowledge the help of the departments of the Electronic Research Laboratory that were involved in the research and development work of this system.     

Prenatal ethanol exposure alters ventricular myocyte contractile function in the offspring of rats: influence of maternal Mg2+ supplementation

Fetal alcohol syndrome (FAS) is often associated with cardiac hypertrophy and impaired ventricular function in a manner similar to postnatal chronic alcohol ingestion. Chronic alcoholism has been shown to lead to hypomagnesemia, and dietary Mg2+ supplementation was shown to ameliorate ethanol- induced cardiovascular dysfunction such as hypertension. However, the role of gestational Mg2+ supplementation on FAS-related cardiac dysfunction is unknown. This study was conducted to examine the influence of gestational dietary Mg2+ supplementation on prenatal ethanol exposure-induced cardiac contractile response at the ventricular myocyte level. Timed-pregnancy female rats were fed from gestation day 2 with liquid diets containing 0.13 g/L Mg2+ supplemented with ethanol (36%) or additional Mg2+ (0.52 g/L), or both. The pups were maintained on standard rat chow through adulthood, and ventricular myocytes were isolated and stimulated to contract at 0.5 Hz. Mechanical properties were evaluated using an IonOptix soft-edge system, and intracellular Ca2+ transients were measured as changes in fura-2 fluorescence intensity (Delta FFI). Offspring from all groups displayed similar growth curves. Myocytes from the ethanol group exhibited reduced cell length, enhanced peak shortening (PS), and shortened time to 90% relengthening (TR90) associated with a normal Delta FFI and time to PS (TPS). Mg2+ reverted the prenatal ethanol-induced alteration in PS and maximal velocity of relengthening. However, it shortened TPS and TR90, and altered the Delta FFI, as well as Ca2+ decay rate by itself. Additionally, myocytes from the ethanol group exhibited impaired responsiveness to increased extracellular Ca2+ or stimulating frequency, which were restored by gestational Mg2+ supplementation. These data suggest that although gestational Mg2+ supplementation may be beneficial to certain cardiac contractile dysfunctions in offspring of alcoholic mothers, caution must be taken, as Mg2+ supplementation affects cell mechanics itself.     

Support effects on catalysis of low temperature methane steam reforming

Low temperature (<500 K) methane steam reforming in an electric field was investigated over various catalysts. To elucidate the factors governing catalytic activity, activity tests and various characterization methods were conducted over various oxides including CeO₂, Nb₂O₅, and Ta₂O₅ as supports. Activities of Pd catalysts loaded on these oxides showed the order of CeO₂ > Nb₂O₅ > Ta₂O_5. Surface proton conductivity has a key role for the activation of methane in an electric field. Proton hopping ability on the oxide surface was estimated using electrochemical impedance measurements. Proton transport ability on the oxide surface at 473 K was in the order of CeO₂ > Nb₂O₅ > Ta₂O_5. The OH group amounts on the oxide surface were evaluated by measuring pyridine adsorption with and without H₂O pretreatment. Results indicate that the surface OH group concentrations on the oxide surface were in the order of CeO₂ > Nb₂O₅ > Ta₂O_5. These results demonstrate that the surface concentrations of OH groups are related to the proton hopping ability on the oxide surface. The concentrations reflect the catalytic activity of low-temperature methane steam reforming in the electric field.

Low temperature (<500 K) methane steam reforming in an electric field was investigated over various catalysts.     

Efficacy of morning-only 4 liter sulfa free polyethylene glycol vs 2 liter polyethylene glycol with ascorbic acid for afternoon colonoscopy

AIM:To compare the bowel cleansing efficacy of same day ingestion of 4-L sulfa-free polyethylene glycol(4-L SF-PEG)vs 2-L polyethylene glycol solution with ascorbic acid(2-L PEG+Asc)in patients undergoing afternoon colonoscopy.METHODS:206 patients(mean age 56.7 years,61%male)undergoing outpatient screening or surveillance colonoscopies were prospectively randomized to receive either 4-L SF-PEG(n=104)or 2-L PEG+Asc solution(n=102).Colonoscopies were performed by two blinded endoscopists.Bowel preparation was graded using the Ottawa scale.Each participant completed a satisfaction and side effect survey.RESULTS:There was no difference in patient demographics amongst groups.4-L SF-PEG resulted in better Ottawa scores compared to 2-L PEG+Asc,4.2 vs4.9(P=0.0186);left colon:1.33 vs 1.57 respectively(P=0.0224),right colon:1.38 vs 1.63 respectively(P=0.0097).No difference in Ottawa scores was found for the mid colon or amount of fluid.Patient satisfaction was similar for both arms but those assigned to 4-L SF-PEG reported less bloating:23.1%vs 11.5%(P=0.0235).Overall polyp detection,adenomatous polyp and advanced adenoma detection rates were similar between the two groups.CONCLUSION:Morning only 4-L SF-PEG provided superior cleansing with less bloating as compared to 2-L PEG+Asc bowel preparation for afternoon colonoscopy.Thus,future studies evaluating efficacy of morning only preparation for afternoon colonoscopy should use4-L SF-PEG as the standard comparator.