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Biomedical subjects

Matthew R Walters

Publications and source records attributed to Matthew R Walters.

6 recordsLinked to original sources
PubMed2006

Discovery and characterization of Sip1A: A novel secreted protein from Bacillus thuringiensis with activity against coleopteran larvae.

Bioassay screening of Bacillus thuringiensis culture supernatants identified strain EG2158 as having larvicidal activity against Colorado potato beetle (Leptinotarsa decemlineata) larvae. Ion-exchange fractionation of the EG2158 culture supernatant resulted in the identification of a protein designated Sip1A (secreted insecticidal protein) of approximately 38 kDa having activity against Colorado potato beetle (CPB). An oligonucleotide probe based on the N-terminal sequence of the purified Sip1A protein was used to isolate the sip1A gene. The sequence of the Sip1A protein, as deduced from the sequence of the cloned sip1A gene, contained 367 residues (41,492 Da). Recombinant B. thuringiensis and Escherichia coli harboring cloned sip1A produced Sip1A protein which had insecticidal activity against larvae of CPB, southern corn rootworm (Diabrotica undecimpunctata howardi), and western corn rootworm (Diabrotica virgifera virgifera).

Animals↗
PubMed2005

Acute stroke and diabetes.

Diabetes and hyperglycaemia are each over-represented amongst patients with acute stroke. Hyperglycaemia is associated with poor stroke outcome. Symptomatic intracranial haemorrhagic transformation is commoner in diabetes and hyperglycaemia but the treatment effect of thrombolysis appears not to be influenced by blood sugar level. Evidence from general patients treated in intensive care units suggests that intensive control of hyperglycaemia may improve early outcome; this evidence cannot be directly extrapolated to patients with acute stroke since supportive randomized controlled trial evidence describing benefits and risks of insulin administration for hyperglycaemia in stroke is scant. Nevertheless, at present the European guidelines suggest that glucose control may be advisable and place a threshold of 10 mmol/l for definite intervention; American guidelines are weaker. Glucose-potassium-insulin infusion or adjusted insulin infusions each have their proponents: both are effective but both carry a small risk of hypoglycaemia. Use of a suitable locally approved regimen seems advisable.

Acute Disease↗
PubMed2003

Serum urate as an independent predictor of poor outcome and future vascular events after acute stroke.

BACKGROUND AND PURPOSE: Serum urate concentration is associated with cardiovascular disease, and hyperuricemia predicts first-ever stroke. We explored the association of admission urate level with mortality, placement, and risk of further vascular events after acute stroke. METHODS: In patients with ischemic stroke or primary intracranial hemorrhage, we determined the association of urate level with 90-day placement (alive at home, good outcome; dead or living in care, poor outcome) and with the subsequent occurrence of ischemic stroke, myocardial infarction, or vascular death. In multivariate analysis (logistic regression for 90-day placement, proportional-hazards regression for time to further vascular event), we adjusted for stroke severity (modified National Institutes of Health stroke scale) and other clinical, biochemical, and radiological variables known to influence stroke outcome. RESULTS: We studied 3731 patients and measured serum urate in 2498. Elevated urate level predicted a lower chance of good 90-day outcome (odds ratio, 0.78 per additional 0.1 mmol/L; 95% confidence interval [CI], 0.67 to 0.91) independently of stroke severity and other prognostic factors. Vascular event risk increased with urate level (relative hazard, 1.27 per additional 0.1 mmol/L; 95% CI, 1.18 to 1.36). Higher urate levels have a greater effect on vascular event rates in the presence of diabetes (additional relative hazard, 1.22 per additional 0.1 mmol/L; 95% CI, 1.06 to 1.41). CONCLUSIONS: Independently of other prognostic factors, higher serum urate levels predicted poor outcome (dead or in care) and higher vascular event rates. The role of urate in stroke pathophysiology remains uncertain, but intervention to lower urate may be worth considering.

Acute Disease↗
PubMed2003

Low triglyceride, not low cholesterol concentration, independently predicts poor outcome following acute stroke.

BACKGROUND: Recent data have shown an unexpected association between poor outcome after acute stroke and lower serum cholesterol. Triglyceride concentration has been linked to coronary heart disease and stroke; however, there are currently no data on the relationship between triglyceride and stroke outcome. Such information may yield further mechanistic information on the relationship between lipids and stroke outcome. METHODS: We studied 1,310 nondiabetic patients presenting to our acute stroke unit with computed tomography-confirmed acute stroke. Fasting blood samples were drawn within 24 h of admission for glucose, lipids and a standard battery of biochemistry and hematological tests. Information on age, stroke type, admission blood pressure, smoking status, presence of atrial fibrillation, resolution time of symptoms and Oxfordshire Community Stroke Project clinical classification was collated. Stepwise proportional hazards regression was used to estimate the effect of the above variables on survival following stroke. RESULTS: Increased age (p < 0.0001), presence of atrial fibrillation (p = 0.009), hyperglycemia (p = 0.0005) and lower triglyceride level (p < 0.0001) independently predicted higher mortality; early resolution of symptoms (p = 0.005) independently predicted lower mortality. Although serum cholesterol level predicted outcome after adjusting for other prognostic factors, it did not remain significant when triglyceride level was entered into the model. The relative hazard per additional quartile of triglyceride was 0.84 (95% confidence interval 0.77-0.91). CONCLUSIONS: Low triglyceride concentration strongly predicts higher mortality following stroke, whereas serum cholesterol level is not an independent predictor. Outcome following stroke is thus related more strongly to triglyceride-rich than to cholesterol-rich lipoprotein concentrations. The mechanisms explaining this require further investigation.

Acute Disease↗
PubMedDate not supplied

Elevated serum urate concentration independently predicts poor outcome following stroke in patients with diabetes.

BACKGROUND: Type 2 diabetes is a risk factor for stroke and confers increased risk of poor outcome and further vascular events following stroke. Hyperuricaemia occurs commonly in patients with type 2 diabetes, but its significance as a predictor of outcome following stroke is uncertain. We sought to investigate the prognostic significance of elevated serum urate concentration in diabetic subjects following stroke. METHODS: We studied a cohort of type 2 diabetes patients presenting to our unit with computed tomography-confirmed acute stroke. Fasting blood samples were drawn within 24 h of admission for urate concentration and standard battery of biochemistry and hematological tests. Information on age, stroke type, prior hypertension, smoking status, resolution time of symptoms and National Institutes of Health Stroke Score was collated. The main outcome event was time to myocardial infarction, recurrent stroke or vascular death, as defined in the CAPRIE trial. Stepwise proportional hazards regression was used to estimate the effect of the above variables on event-free survival following stroke. RESULTS: One hundred and forty patients were studied. Median follow-up duration was 974 days (IQR 163 to 1830 days). Sixty-four patients suffered an outcome event. Urate levels of greater than 0.42 mmol/L (p < 0.001) and an increasing NIHSS score (p < 0.001) independently predicted increased likelihood of suffering an event. CONCLUSION: Elevated urate concentration is significantly and independently associated with increased risk of future vascular events in diabetic stroke patients. Further studies to elucidate the mechanism of this observation are required.

Aged↗