PubMed Health⌕ Search

Biomedical subjects

Michael Jenkins

Publications and source records attributed to Michael Jenkins.

5 recordsLinked to original sources
PubMed2005

Which general practices have higher list inflation? An exploratory study.

BACKGROUND: There is a 7% discrepancy between English population estimates based on census figures and those based on the registered lists of GPs. GP income under the 2004 new contract will be based on registered patient populations but a national 'de-ghosting' exercise will ensue, aiming to eliminate list inflation. OBJECTIVE: To derive an estimate of the variation in list inflation between individual general practices. METHODS: Letters were sent to all men aged 20-29 years and registered at practices based in three inner city Primary Care Trusts (n = 42 712). Non respondents received one further reminder. Cards were issued to each GP listing non responders. Patients were deducted from the GP list after six months if the GP did not verify the address. RESULTS: 42 712 letters were sent. 33.5% of registered patients were eventually deducted from the GP list (deduction figures only available for 20-24 year old group). Practice level deduction rates ranged from 7-76%. Practices with higher deduction rates achieved lower vaccination rates for 2 year olds (Pearson's r = 20.25; P = 0.005) and cervical smear rates (Pearson's r = 20.18; P = 0.04); they also had cheaper prescribing costs per ASTRO-PU (Pearson's r = 20.20; P = 0.03). CONCLUSIONS: If these findings apply to the whole registered population, the national de-ghosting exercise is likely to result in large changes to the list size of some practices. Without correcting for list inflation, primary care research based on patient list size as the denominator may underestimate various measures of GP activity, particularly in deprived inner city areas. Resource allocation is also likely to be distorted by differences in list inflation.

Adult↗
PubMed2004

Cryptosporidium parvum oocyst inactivation in field soil and its relation to soil characteristics: analyses using the geographic information systems.

The need exists to understand the environmental parameters that affect inactivation of Cryptosporidium parvum oocysts in soil under field conditions. The inactivation of C. parvum oocysts placed in the natural environment was studied at a dairy farm in western New York State, USA. Seventy sampling points were arranged in a grid with points 150 m apart using the Geographic Information System. The sampling points were distributed among three distinct areas: woodland, corn field and pasture. Purified oocysts were inoculated into chambers filled with soil from each sampling point, and buried in the surface of each respective sampling point. To compare C. parvum oocyst survival with another organism known to survive environmental stresses, Ascaris suum eggs were also placed in soil contained in chambers and buried at the same sampling points as the oocysts. As controls oocysts and eggs in distilled water were also placed at each sampling point. Oocyst and egg viability, soil pH and percent gravimetric water content were measured at all sampling points at 0, 60 and 120 day sampling periods. Soil organic content was determined for each sampling point. At 120 days after placement, mean viability of C. parvum oocysts was 10% although at a few sampling points, 30% of oocysts were still potentially infective; whereas 90% of A. suum eggs were viable at all sampling points. Statistically significant differences were not observed among the three different sampling areas, and no statistically significant predictors were found by regression analysis. Results exemplified the heterogeneity of soil parameters and oocyst viability across a landscape; such results make predictive models for C. parvum inactivation problematical. The long-term survival of C. parvum oocysts in soil under field conditions, as this study demonstrated, emphasizes their potential as a risk to contaminate surface waters.

Agriculture↗
PubMed2002

Melatonin reduces TNF-a induced expression of MAdCAM-1 via inhibition of NF-kappaB.

BACKGROUND: Endothelial MAdCAM-1 (mucosal addressin cell adhesion molecule-1) expression is associated with the oxidant-dependent induction and progress of inflammatory bowel disease (IBD). Melatonin, a relatively safe, potent antioxidant, has shown efficacy in several chronic injury models may limit MAdCAM-1 expression and therefore have a therapeutic use in IBD. METHODS: We examined how different doses of melatonin reduced endothelial MAdCAM-1 induced by TNF-a in an in vitro model of lymphatic endothelium. Endothelial monolayers were pretreated with melatonin prior to, and during an exposure, to TNF-a (1 ng/ml, 24 h), and MAdCAM-1 expression measured by immunoblotting. RESULTS: MAdCAM-1 was induced by TNF-a. Melatonin at concentrations over 100 microm (10(-4) M) significantly attenuated MAdCAM-1 expression and was maximal at 1 mM. CONCLUSIONS: Our data indicate that melatonin may exert therapeutic activity in IBD through its ability to inhibit NF-kappaB dependent induction of MAdCAM-1.

Cell Adhesion Molecules↗
PubMedDate not supplied

Preferential transport of Cryptosporidium parvum oocysts in variably saturated subsurface environments.

When oocysts of the protozoan Cryptosporidium parvum contaminate drinking water supplies, they can cause outbreaks of Cryptosporidiosis, a common waterborne disease. Of the different pathways by which oocysts can wind up in drinking water, one has received little attention to date; that is, because soils are often considered to be perfect filters, the transport of oocysts through the subsoil to groundwater is generally ignored. To evaluate the significance of this pathway, a series of laboratory experiments investigated subsurface transport of oocysts. Experiment 1 was carried out in a vertical 18-cm-long column filled either with glass beads or silica sand, under conditions known to foster fingered flow. Experiment 2 involved undisturbed, macroporous soil columns subjected to macropore flow. Experiment 3 aimed to study the lateral flow on an undisturbed soil block. The columns and soil samples were subjected to artificial rainfall and were allowed to reach steady state. At that point, feces of contaminated calves were applied at the surface along with a known amount of potassium chloride to serve as a tracer, and rainfall was continued at the same rate. The breakthrough of oocysts and chloride, monitored in the effluent, demonstrate the importance of preferential flow on the transport of oocysts. Compared with chloride, peak oocyst concentrations were not appreciably delayed and, in some cases, occurred even before the chloride peak. Recovery rates for oocysts were low, ranging from 0.1 to 10.4% of the oocysts originally applied on the columns. However, the numbers of oocysts present in the effluents were still orders of magnitude higher than 10 oocysts, the infectious dose considered by the U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, to be sufficient to cause Cryptosporidiosis in healthy adults. These results suggest that the transport of oocysts in the subsurface via preferential flow may create a significant risk of groundwater contamination in some situations.

Animals↗