Development and field testing of low-cost, quantal microbial assays with volunteer reporting as scalable means of drinking water safety estimation

AIMS

To evaluate a low-cost water quality test for at-scale drinking water safety estimation in rural India.

METHODS AND RESULTS

Within a longitudinal study to characterize variability in household drinking water safety in rural Maharashtra, we piloted a low-cost presence-absence (LCPA) microbial test designed to be used by volunteer residents in rural areas. In comparing the LCPA results with standard laboratory methods for enumeration of Escherichia coli, we found that LCPA tests using modified mTec media were highly sensitive in detecting drinking water of moderate risk (88% of tests were positive at E. coli counts of 11-100 CFU per 100 ml) and high risk (96% of tests were positive at E. coli counts of 101 + CFU per 100 ml). The LCPA tests demonstrated low specificity for E. coli specifically, due to concurrent detection of Klebsiella: 38% of LCPA tests were positive even when E. coli was not detected in a 100 ml sample by membrane filtration, suggesting the test would be conservative in risk estimation. We also found that 47% of participants in rural villages in India were willing to conduct tests and return results after a brief training, with 45% of active participants sending their water testing results via short message service.

CONCLUSIONS

Given their low cost (~US$0.50 as piloted) and open-source format, such tests may provide a compelling alternative to standard methods for rapid water quality assessments, especially in resource-limited settings.

SIGNIFICANCE AND IMPACT OF THE STUDY

The lack of availability of water quality data constrains efforts to monitor, evaluate and improve the safety of water and sanitation infrastructure in underserved settings. Current water testing methods are not scalable because of laboratory and cost constraints. Our findings indicate the LCPA or similar low-cost microbial tests could be useful in rapid water safety estimation, including via crowdsourcing.

Dynamics of {beta}-amyloid reductions in brain, cerebrospinal fluid, and plasma of {beta}-amyloid precursor protein transgenic mice treated with a {gamma}-secretase inhibitor

gamma-Secretase inhibitors are one promising approach to the development of a therapeutic for Alzheimer's disease (AD). gamma-Secretase inhibitors reduce brain beta-amyloid peptide (Abeta), which is believed to be a major contributor in the etiology of AD. Transgenic mice overexpressing the human beta-amyloid precursor protein (APP) are valuable models to examine the dynamics of Abeta changes with gamma-secretase inhibitors in plaque-free and plaque-bearing animals. BMS-299897 2-[(1R)-1-[[(4-chlorophenyl)sulfony](2,5-difluorophenyl)amino]ethyl]-5-fluorobenzenepropanoic acid, a gamma-secretase inhibitor, showed dose- and time dependent reductions of Abeta in brain, cerebrospinal fluid (CSF), and plasma in young transgenic mice, with a significant correlation between brain and CSF Abeta levels. Because CSF and brain interstitial fluid are distinct compartments in composition and location, this correlation could not be assumed. In contrast, aged transgenic mice with large accumulations of Abeta in plaques showed reductions in CSF Abeta in the absence of measurable changes in plaque Abeta in the brain after up to 2 weeks of treatment. Hence, CSF Abeta levels were a valuable measure of gamma-secretase activity in the central nervous system in either the presence or absence of plaques. Transgenic mice were also used to examine potential side effects due to Notch inhibition. BMS-299897 was 15-fold more effective at preventing the cleavage of APP than of Notch in vitro. No changes in the maturation of CD8(+) thymocytes or of intestinal goblet cells were observed in mice treated with BMS-299897, showing that it is possible for gamma-secretase inhibitors to reduce brain Abeta without causing Notch-mediated toxicity.

Preoperative latanoprost to prevent ocular hypertension after phacoemulsification and intraocular lens implantation

PURPOSE

To evaluate the efficacy of latanoprost given 2 hours preoperatively to prevent ocular hypertension in the early period after phacoemulsification and posterior chamber intraocular lens (PC IOL) implantation.

SETTING

Departments of Ophthalmology, United Christian Hospital and Prince of Wales Hospital, Hong Kong, China.

METHODS

Sixty-four eyes of 64 patients with uncomplicated cataract having phacoemulsification with PC IOL implantation were included in this prospective randomized double-masked clinical trial. The eyes were randomly assigned to 1 of 2 groups: application of latanoprost 0.005% 2 hours before surgery or no latanoprost (control). Intraocular pressure (IOP) was measured 3 and 24 hours postoperatively. The anterior chamber was examined for the level of cells and flare using a slitlamp biomicroscope. The level of significance was 5%.

RESULTS

The decrease in the mean IOP was not statistically significantly different between eyes receiving latanoprost 2 hours preoperatively and control eyes 3 hours (P =.843) and 24 hours (P =.721) postoperatively.

CONCLUSION

A single application of latanoprost given 2 hours before phacoemulsification and PC IOL implantation did not produce a statistically significant IOP-lowering effect when compared with a control group in the first 24 hours after surgery.

Pars plana vitrectomy with silicone oil in the management of combined rhegmatogenous retinal and choroidal detachment

PURPOSE

Rhegmatogenous retinal detachment combined with spontaneous pre-operative choroidal detachment (RDCD) represents a rare but specific entity, which has in the past been associated with a poor prognosis. This study was designed to determine the efficacy of pars plana vitrectomy with silicone oil injection in the management of this very difficult vitreoretinal problem.

METHODS

A retrospective analysis was carried out of 13 eyes of 13 consecutive patients who underwent vitrectomy and silicone oil exchange.

RESULTS

In a total of 10 eyes (77%) the first procedure produced anatomical success. Two eyes required a further procedure to achieve retinal reattachment, producing a final anatomical success rate of 92%.

CONCLUSION

Pars plana vitrectomy with silicone oil exchange is an effective technique for managing RDCD.

Effect of intracameral acetylcholine on latanoprost in preventing ocular hypertension after phacoemulsification and intraocular lens implantation

PURPOSE

To evaluate the effect of intracameral acetylcholine on latanoprost in preventing ocular hypertension in the early period after phacoemulsification with posterior chamber intraocular lens (PC IOL) implantation.

SETTING

Department of Ophthalmology and Visual Sciences, Prince of Wales Hospital, Shatin, Hong Kong, China.

METHODS

Patients with uncomplicated cataract having phacoemulsification with PC IOL implantation were included in this prospective randomized double-masked clinical trial. The eyes were randomly assigned to 1 of 4 groups based on postoperative application of latanoprost 0.005% alone (Group 1), latanoprost 0.005% with intracameral acetylcholine (Group 2), intracameral acetylcholine alone (Group 3), and no medication (controls (Group 4). Intraocular pressure (IOP) was measured 3 and 24 hours postoperatively. The anterior chamber was examined for the level of cells and flare using slitlamp biomicroscopy.

RESULTS

Three and 24 hours after surgery, the decrease in mean IOP in eyes receiving latanoprost alone was not statistically significantly different from that in control eyes (P >.05). Eyes receiving intracameral acetylcholine alone had a significant decrease in the mean IOP at 3 hours (P <.05) but not at 24 hours compared to control eyes (P >.05). There were no significant differences in the mean postoperative IOP decrease between eyes receiving latanoprost with intracameral acetylcholine and those receiving intracameral acetylcholine alone (P >.05).

CONCLUSIONS

A single application of latanoprost did not significantly lower IOP in the first 24 hours after phacoemulsification with PC IOL implantation. Eyes receiving intracameral acetylcholine alone had a significantly greater decrease in IOP than control eyes at 3 hours but not at 24 hours. The addition of intracameral acetylcholine to latanoprost did not enhance or reduce latanoprost's IOP-lowering effect.

Dietary nucleotides augment dextran sulfate sodium-induced distal colitis in rats

We have previously shown that enteral and parenteral supplementation of nucleotides (NT) accelerates healing of small-bowel ulcers in rats with indomethacin-induced ileitis. The purpose of this study was to evaluate whether dietary NT supplementation would similarly affect ulcer healing in dextran sulfate sodium (DSS)-induced colitis in rats. Male Sprague-Dawley rats were randomly assigned to receive either nucleotide-free (NF) or NT-supplemented diets. After 2 d of prefeeding, colitis was induced by including 40 g/L of DSS in drinking water for 3 d, followed thereafter by tap water. Rats from each group were killed at 7 and 12 d after induction of colitis. Additional rats were also used for both the groups as controls (untreated groups). The length of colon was measured and evaluated by histological score. Colonic myeloperoxidase (MPO) activity was assessed. In a separate series of experiments, rats were studied at 0, 4, 7, and 12 d for interleukin-1beta (IL-1beta) in rectal dialysate and plasma. Ulceration predominated in the distal colon in DSS-treated rats. There was no significant difference between the histological scores of the NF and NT-supplemented groups either at 7 or 12 d. MPO activity at 7 and 12 d was significantly higher in the NT-supplemented compared to NF group (7 d: 1013 +/- 172 vs. 409.9 +/- 103.2; 12 d: 471.9 +/- 112.4 vs. 223.6 +/- 21.6 units. min-1. g colon-1). IL-1beta concentration in rectal dialysate was significantly higher at 7 d in both groups compared to 0 and 4 d. At 12 d it continued to be significantly elevated in the NT-supplemented group and was greater than in the NT-free group. Our data on the proinflammatory cytokine, in conjunction with MPO activity, strongly suggest that NT supplementation aggravates the severity of DSS-induced colitis in rats.

Expression and characterization of protein kinase C in isolated rabbit parietal cells

We investigated the expression, characterization and distribution of protein kinase C (PKC) isozymes in isolated rabbit parietal cells (PC). Cellular extracts of PC were analyzed by Western blot using isozyme-specific antibodies. The Ca2+-independent PKC-epsilon was detected in cytosolic, membrane and cytoskeletal fractions of basal and histamine-stimulated PC, whereas the Ca2+-dependent PKC-alpha was confined to the cytosolic and membrane fractions. Cytosolic and membrane fractions were partially purified by DEAE cellulose column chromatography with elution of increasing NaCl concentration. Eluates of 0.15 M and 0.3 M NaCl PC fractions were identified as PKC-alpha and -epsilon isoforms, respectively. Phorbol 12-myristate 13-acetate (TPA) treatment of PC for 15, 30 and 60 sec decreased significantly cytosolic PKC-alpha and increased membrane-associated PKC-alpha. In contrast to the distribution of PKC-alpha, TPA did not alter membrane or cytosolic level of PKC-epsilon. Comparison of the dose-response curves between TPA-induced hydrogen (H+) secretion, as measured by aminopyrine (AP) uptake, and the membrane-associated PKC-alpha suggests that translocation of PKC-alpha is not involved in the H+ secretory process in PC. Furthermore, a PKC inhibitor, staurosporine, produced a concentration-dependent enhancement of histamine-stimulated H+ secretion. These findings suggest that PKC-alpha plays a negative modulatory role, rather than an obligatory role, in H+ secretion. The localization and distribution of PKC-epsilon into the cytoskeletal fraction of PC also suggests that this isozyme may be involved in the cellular regulation of reversible morphological transformation during stimulation.

Dietary supplementation of nucleotides and arginine promotes healing of small bowel ulcers in experimental ulcerative ileitis

We previously showed that intravenous total parenteral nutrition supplemented with nucleosides and nucleotides (NS/NT) promoted ulcer healing in rats with indomethacin-induced ileitis. The present study evaluated whether dietary NT supplementation would similarly affect ulcer healing in this model. Female Lewis rats were randomized into either control or experimental groups receiving yeast RNA containing NT or arginine, glutamine, fish oil, guar gum, or a combination of yeast RNA+arginine diets. Ileitis was induced by two doses of indomethacin (7.5 mg/kg) administered subcutaneously 24 hr apart. Ulcer number and length were determined at 4, 8, and 14 days after induction of ileitis. Ileal villous and crypt length, crypt-villous ratio, and bromodeoxyuridine (BrdU) labeling were studied in the control and yeast RNA-supplemented diet groups. Ileal ulceration was present in all groups at 4 and 8 days and was almost healed by 14 days. Rats receiving yeast RNA, arginine, and yeast RNA + arginine diets showed a significant decrease in ulcer number (56%, 28%, and 34%, respectively) and length (67%, 41%, and 48%, respectively) compared to controls at 8 but not at 4 days. Glutamine, fish oil, and guar gum had no effect on ulcer healing at 4, 8, or 14 days. Among the histological parameters, a significant decrease in crypt length in the yeast RNA-supplemented group at 8 days suggested an acceleration of the healing process and restoration to a near-normal crypt-villous architecture. We conclude that the yeast RNA, arginine, and yeast RNA + arginine diets accelerated ulcer healing, as indicated by decreased ulcer number and length. We postulate that the underlying mechanism(s) contributing to ulcer healing may be related, in part, to increased cell proliferation.

Anomalous serum thyroxin measurements with the Abbott TDx procedure

We describe a patient whose serum gave consistently low results for thyroxin as measured with the Abbott TDx but normal results by radioimmunoassay. Further clinical and laboratory studies did not support the low TDx results. Anti-thyroxin antibodies did not explain the discordant results, and we found no evidence of heterophilic antibodies in the patient's serum. We were unable to identify the cause of the problem.

Anomalous serum thyroxin measurements with the Abbott TDx procedure

We describe a patient whose serum gave consistently low results for thyroxin as measured with the Abbott TDx but normal results by radioimmunoassay. Further clinical and laboratory studies did not support the low TDx results. Anti-thyroxin antibodies did not explain the discordant results, and we found no evidence of heterophilic antibodies in the patient's serum. We were unable to identify the cause of the problem.