Stroma-free hemoglobin increases blood pressure and GFR in the hypotensive rat: role of nitric oxide.

The short-term systemic and renal hemodynamic effects of two stroma-free hemoglobin (SFH) solutions, one unmodified and the other modified by cross-linking, were examined in anesthetized rats after hemorrhagic hypotension. Both forms of SFH increased mean arterial pressure (MAP) and glomerular filtration rate (GFR) to baseline (prehemorrhage) values. The increase in MAP induced by unmodified SFH was greater than the increase in MAP caused by an albumin solution isoncotic to the unmodified SFH solution. Similarly, the increase in MAP caused by the modified SFH was also substantially greater than that induced by an albumin solution of comparable oncotic pressure to the modified SFH solution. Both unmodified and modified SFH increased GFR. As with MAP, the increase in GFR induced by both SFH solutions was greater than that associated with the oncotically matched albumin solutions. In separate experiments, the effects of nitric oxide (NO) inhibition with N omega-nitro-L-arginine methyl ester (L-NAME) on MAP after hemorrhagic hypotension and subsequent infusion of unmodified SFH or albumin were also examined. In the albumin-infused rats, L-NAME increased MAP. In marked contrast, NO inhibition with L-NAME had no further effect on MAP when infused after SFH. We conclude that both unmodified and modified SFH solutions acutely improve MAP and GFR by the combined effects of intravascular volume expansion resulting from the colloid effect of the protein and by inactivation of NO.

Thrombopoietin, flt3-ligand and c-kit-ligand modulate HOX gene expression in expanding cord blood CD133(+) cells

Haemopoietic stem/progenitor cell (HSPC) development is regulated by extrinsic and intrinsic stimuli. Extrinsic modulators include growth factors and cell adhesion molecules, whereas intrinsic regulation is achieved with many transcription factor families, of which the HOX gene products are known to be important in haemopoiesis. Umbilical cord blood CD133(+) HSPC proliferation potential was tested in liquid culture with 'TPOFLK' (thrombopoietin, flt-3 ligand and c-kit ligand, promoting HSPC survival and self-renewal), in comparison to 'K36EG' (c-kit-ligand, interleukins-3 and -6, erythropoietin and granulocyte colony-stimulating factor, inducing haemopoietic differentiation). TPOFLK induced a higher CD133(+) HSPC proliferation (up to 60-fold more, at week 8) and maintained a higher frequency of the primitive colony-forming cells than K36EG. Quantitative polymerase chain reaction analysis revealed opposite expression patterns for specific HOX genes in expanding cord blood CD133(+) HSPC. After 8 weeks in liquid culture, TPOFLK increased the expression of HOX B3, B4 and A9 (associated with uncommitted HSPC) and reduced the expression of HOX B8 and A10 (expressed in committed myeloid cells) when compared to K36EG. These results suggest that TPOFLK induces CD133(+) HSPC proliferation, self-renewal and maintenance, up-regulation of HOX B3, B4 and A9 and down-regulation of HOX B8 and A10 gene expression.

Dose-dependent effects of folic acid on blood concentrations of homocysteine: a meta-analysis of the randomized trials

Background: Dietary supplementation with B vitamins that lower blood homocysteine concentrations is expected to reduce cardiovascular disease risk, but there has been uncertainty about the optimum regimen to use for this purpose.

Endothelial Nox4 NADPH oxidase enhances vasodilatation and reduces blood pressure in vivo.

OBJECTIVE: Increased reactive oxygen species (ROS) production is involved in the pathophysiology of endothelial dysfunction. NADPH oxidase-4 (Nox4) is a ROS-generating enzyme expressed in the endothelium, levels of which increase in pathological settings. Recent studies indicate that it generates predominantly hydrogen peroxide (H(2)O(2)), but its role in vivo remains unclear. METHODS AND RESULTS: We generated transgenic mice with endothelium-targeted Nox4 overexpression (Tg) to study the in vivo role of Nox4. Tg demonstrated significantly greater acetylcholine- or histamine-induced vasodilatation than wild-type littermates. This resulted from increased H(2)O(2) production and H(2)O(2)-induced hyperpolarization but not altered nitric oxide bioactivity. Tg had lower systemic blood pressure than wild-type littermates, which was normalized by antioxidants. CONCLUSION: Endothelial Nox4 exerts potentially beneficial effects on vasodilator function and blood pressure that are attributable to H(2)O(2) production. These effects contrast markedly with those reported for Nox1 and Nox2, which involve superoxide-mediated inactivation of nitric oxide. Our results suggest that therapeutic strategies to modulate ROS production in vascular disease may need to separately target individual Nox isoforms.

Metronidazole Population Pharmacokinetics in Preterm Neonates Using Dried Blood-Spot Sampling

OBJECTIVES: To characterize the population pharmacokinetics of metronidazole in preterm neonates.
PATIENTS AND METHODS: Data were collected prospectively from 32 preterm neonates who received intravenous metronidazole for the treatment of or prophylaxis against necrotizing enterocolitis. Dried
blood spots (n 203) on ?lter paper were analyzed by highperformance liquid chromatography, and the data were subjected to pharmacokinetic analysis performed by using nonlinear mixed-effect modeling.
RESULTS: A 1-compartment model best described the data. Signi?cant covariates were weight (WT) and postmenstrual age (PMA). The ?nal population models for metronidazole clearance (CL) and volume of distribution (V) were: CL 0.0247 (WT/1.00)0.75 (1 0.107 [PMA 30]) and V 0.726 WT, where CL is in liters per hour, WT is in kilograms, PMA is in weeks, and V is in liters. This model predicts that the half-life of metronidazole decreases rapidly from 40 hours at 25 weeks’ PMA to 19 hours at 32 weeks’ PMA, after which it starts to plateau. This decrease in half-life is the result of a 5-fold increase in CL compared with only a 2.5-fold increase in V during the same period.
CONCLUSIONS: Currently, there are no speci?c dose recommendations for metronidazole in preterm neonates. However, a dosing scheme for preterm neonates that takes into consideration both the weight and PMA has been suggested and should avoid administration of doses that are excessive or more frequent than necessary.

Clinical and economic impact of contaminated blood cultures within the hospital setting

Blood cultures have an important role in the diagnosis of serious infections, although contamination of blood cultures (i.e. false-positive blood cultures) is a common problem within the hospital setting. The objective of the present investigation was to determine the impact of the false-positive blood culture results on the following outcomes: length of stay, hotel costs, antimicrobial costs, and costs of laboratory and radiological investigation. A retrospective case-control study design was used in which 142 false-positive blood culture cases were matched with suitable controls (patients for whom cultures were reported as true negatives). The matching criteria included age, comorbidity score and month of admission to the hospital. The research covered a 13-month period (July 2007 to July 2008). The findings indicated that differences in means, between cases and controls, for the length of hospital stay and the total costs were 5.4 days [95% CI (confidence interval): 2.8-8.1 days; P

Blood pressure lowering in patients without prior cerebrovascular disease for prevention of cognitive impairment and dementia

Background: This is an update of a previous review (McGuinness 2006). Hypertension and cognitive impairment are prevalent in older people. Hypertension is a direct risk factor for vascular dementia (VaD) and recent studies have suggested hypertension impacts upon prevalence of Alzheimer's disease (AD). Therefore does treatment of hypertension prevent cognitive decline?
Objectives: To assess the effects of blood pressure lowering treatments for the prevention of dementia and cognitive decline in patients with hypertension but no history of cerebrovascular disease.
Search strategy: The Specialized Register of the Cochrane Dementia and Cognitive Improvement Group, The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS as well as many trials databases and grey literature sources were searched on 13 February 2008 using the terms: hypertens$ OR anti-hypertens$. Selection criteria: Randomized, double-blind, placebo controlled trials in which pharmacological or non-pharmacological interventions to lower blood pressure were given for at least six months.
Data collection and analysis: Two independent reviewers assessed trial quality and extracted data. The following outcomes were assessed: incidence of dementia, cognitive change from baseline, blood pressure level, incidence and severity of side effects and quality of life.
Main results: Four trials including 15,936 hypertensive subjects were identified. Average age was 75.4 years. Mean blood pressure at entry across the studies was 171/86 mmHg. The combined result of the four trials reporting incidence of dementia indicated no significant difference between treatment and placebo (236/7767 versus 259/7660, Odds Ratio (OR) = 0.89, 95% CI 0.74, 1.07) and there was considerable heterogeneity between the trials. The combined results from the three trials reporting change in Mini Mental State Examination (MMSE) did not indicate a benefit from treatment (Weighted Mean Difference (WMD) = 0.42, 95%CI 0.30, 0.53). Both systolic and diastolic blood pressure levels were reduced significantly in the three trials assessing this outcome (WMD = -10.22, 95% CI -10.78, -9.66 for systolic blood pressure, WMD = -4.28, 95% CI -4.58, -3.98 for diastolic blood pressure). Three trials reported adverse effects requiring discontinuation of treatment and the combined results indicated no significant difference (OR = 1.01, 95% CI 0.92, 1.11). When analysed separately, however, more patients on placebo in Syst Eur 1997 were likely to discontinue treatment due to side effects; the converse was true in SHEP 1991. Quality of life data could not be analysed in the four studies. Analysis of the included studies in this review was problematic as many of the control subjects received antihypertensive treatment because their blood pressures exceeded pre-set values. In most cases the study became a comparison between the study drug against a usual antihypertensive regimen.
Authors' conclusions: There is no convincing evidence fromthe trials identified that blood pressure lowering in late-life prevents the development of dementia or cognitive impairment in hypertensive patients with no apparent prior cerebrovascular disease. There were significant problems identified with analysing the data, however, due to the number of patients lost to follow-up and the number of placebo patients who received active treatment. This introduced bias. More robust results may be obtained by conducting a meta-analysis using individual patient data.

Ocular blood flow analysis detects microvascular abnormalities in impaired glucose tolerance.

Objective: Waveform analysis has been used to assess vascular resistance and predict cardiovascular events. We aimed to identify microvascular abnormalities in patients with impaired glucose tolerance (IGT) using ocular waveform analysis. The effects of pioglitazone were also assessed. Methods: Forty patients with IGT and twenty-four controls were studied. Doppler velocity recordings were obtained from the central retinal, ophthalmic and common carotid arteries, and sampled at 200 Hz. A discrete wavelet-based analysis method was employed to quantify waveforms. The resistive index (RI),was also determined. Patients with IGT were randomised to pioglitazone or placebo and measurements repeated after 12 weeks treatment. Results: In the ocular waveforms, significant differences in power spectra were observed in frequency band four (corresponding to frequencies between 6.25 and 12.50 Hz) between groups (p