Bacteria and virus removal effectiveness of ceramic pot filters with different silver applications in a long term experiment.

In 2012 more than 4 million people used a ceramic pot filter (CPF) as household water treatment system for their daily drinking water needs. In the normal production protocol most low cost filters are impregnated with a silver solution to enhance the microbial removal efficiency. The aim of this study was to determine the role of silver during the filtration and subsequent storage. Twenty-two CPFs with three different silver applications (non, only outside and both sides) were compared in a long-term loading experiment with Escherichia coli (K12 and WR1) and MS2 bacteriophages in natural challenge water under highly controlled laboratory circumstances. No significant difference in Log Removal Values were found between the filters with different silver applications. The results show that the storage time in the receptacle is the dominant parameter to reach E. coli inactivation by silver, and not the contact time during the filtration phase. The hypothesis that the absence of silver would enhance the virus removal, due to biofilm formation on the ceramic filter element, could not be confirmed. The removal effectiveness for viruses is still of major concern for the CPF. This study suggests that the ceramic pot filter characteristics, such as burnt material content, do not determine E. coli removal efficacies, but rather the contact time with silver during storage is the dominant parameter to reach E. coli inactivation.

Monitoring for disconnection: ventilators with bellows rising on expiration can deliver tidal volumes after disconnection.

Anesthesia ventilators with bellows that rise on expiration (standing bellows) are favored over ventilators with bellows that descend during expiration (hanging bellows). Standing bellows will not rise if there is a disconnection, and thus they facilitate detection of disconnections. Yet, during a disconnection of ventilators with standing bellows, mechanical inspiration compresses the empty bellows beyond its resting position; with expiration the elastic bellows recoils and aspirates up to 140 ml, depending upon the fresh gas flow. Tidal volumes recorded after disconnection ranged from 50 to 140 ml (mean, 112.2 +/- 9.22 [SD]) at adult settings and from 55 to 90 ml (mean, 69.8 +/- 4.28 [SD]) at pediatric settings. Thus, spirometers that measure tidal volume (VT) in the expiratory limb of the breathing system may falsely indicate an expiratory VT after a disconnection of the breathing system at the Y-piece or the endotracheal tube. Existing low-pressure alarms and capnography alarms provide redundant warning of disconnection, however, should the ventilator continue to deliver small VTs after a disconnection.

Dextran determination in human serum with the aid of an enzymatic glucose method.

A method is presented for the determination of dextran concentrations. Following acid hydrolysis and partial neutralization, the resulting glucose is determined with the aid of glucose oxidase. Specificity is better than that of previously applied methods. Mean recovery is 100.2 +/- 1.6% (SD) for concentrations from 180 mg.l-1 to 6000 mg.l-1. Coefficients of variation are 2.2% for 240 mg.l-1, 1.2% for 600 mg.l-1 and 1.8% for 1200 mg.l-1. When used for volume measurements, the accuracy is 99.3 +/- 2.1% (SD) for volumes of 2.5 to 3 liters.

Amniotic fluid amylase concentration: a reliable predictor of fetal maturity?

The amylase concentration in the amniotic fluid (ACAF) was studied in 138 subjects in relation to duration of pregnancy, fetal weight, L/S ratios and neonatal occurrence of respiratory distress syndrome (RDS). ACAF was found to be significantly correlated with duration of pregnancy (p less than 0.001) and fetal weight (p less than 0.005). The number of false immature predictions, based on a critical value of ACAF of 200 U/l, was relatively high: 36% for the gestational age greater than or equal to 36 weeks, and 38% for fetal weight greater than 2,500 g. ACAF also showed a significant relationship with the L/S ratio (p less than 0.0001). ACAF less than 300 U/l correctly predicted all instances of L/S ratio less than 2.0; however, the rate of false low predictions was 60%. In only 22 out of 138 AF samples (16%) could the performance of an L/S ratio have been avoided on the basis of the ACAF. ACAF less than 300 U/l correctly predicted both cases of neonatal RDS in the study population; however, 1 of these fetuses had an ACAF of 260 U/l. There were four times as many false predictions of lung immaturity on the basis of ACAF less than 300 U/l as from the L/S less than 2.0.

Evaluation of the total lung profile, including the two-dimensional L/S ratio for the establishment of fetal lung maturation.

Recently some articles have been published in which the total lung profile has been introduced to determine the fetal lung maturation. In the present study the two-dimensional L/S ratio and the total lung profile, especially the phosphatidyl-glycerol content, are compared with the conventional one-dimensional L/S ratio. The predictive value of each parameter in repect of its significance as an index of the occurrence of neonatal respiratory distress was studied and a mutual comparison is drawn between the respective indices of prenatal lung maturation. It is concluded that the two-dimensional L/S ratio and the total lung profile are promising new tools to estimate the fetal lung maturity.

The lecithin/sphingomyelin ratio in Macaca arctoides.

The amniotic fluid lecithin/sphingomyelin ratio (L/S ratio) of stumptail macaque monkeys (Macaca arctoides) was investigated by means of serial amniocenteses during the second half of pregnancy. Ten dated pregnancies were studied in 9 individual monkeys. The mean number of successful amniocenteses per pregnancy was 4. A rapid increase in the L/S ratio suggesting maturation of lung surfactant synthesis occurred as early as 130--140 days of pregnancy in some animals, and as late as 150--160 days in others. The earliest and latest times at which the L/S ratio first exceeded 2.0 were 135 and 164 days, respectively. These observations indicate that the L/S ratio of M. arctoides follows a course similar to that observed in human pregnancy, with a rise at 0.7--0.8 of term gestation. M. arctoides thus appears to be a useful model for the study of factors affecting fetal lung maturity, on the basis of the amniotic fluid L/S ratio. In particular, a rapid rise in L/S ratio before 130 days of pregnancy would be highly suggestive of accelerated maturation of pulmonary surfactant production.