Viscosity effects of polyvinyl siloxane impression materials on the accuracy of the stone die produced.

BACKGROUND: The purpose of the present study was to investigate the effect of different viscosities of polyvinyl siloxane (PVS) impression materials on the accuracy of the stone die produced. METHODS: A three-unit bridge master model was fabricated using cold-cure acrylic resin. Four combinations of different viscosities of PVS impression materials - regular body (monophase) alone, light body with regular body, light body with heavy body, and light body with putty - were used to make an impression of the master model. Ten impressions from each group were taken and Type IV gypsum stone was used to generate the dies. The dies were measured at the inter-abutment distance, occlusogingival length, and shoulder width with a measuring microscope and were compared with the master model using one-way analysis of variance and Tukey (honest significant difference) test. RESULTS: Differences were found for inter-abutment distance between the master model and the light body with regular body and light body with putty dies (both P < 0.02). A difference was found for shoulder width between the master model and the regular body alone die (P = 0.01). No differences were found for occlusogingival distance (all P > 0.08). CONCLUSION: Results suggested inter-abutment distance was most accurate when using a PVS light body combination. Occlusogingival length was accurate using any of the studied PVS combinations, and shoulder width was more accurate when using the regular body PVS. RELEVANCE FOR PATIENTS: These results should be considered when choosing the viscosity of the PVS to use for producing impressions of high accuracy and fabricating a well-fitting fixed prosthesis.

Management of hyponatremia: providing treatment and avoiding harm.

Hyponatremia, in its most severe form, requires urgent infusion of hypertonic saline to correct cerebral edema. However, overly rapid correction of chronic hyponatremia can cause osmotic demyelination syndrome. The authors review the treatment of hyponatremia in order to provide clinicians with a sound approach in a variety of settings in which severity, symptoms, and underlying disease states influence therapy. Also discussed is the current role of vasopressin antagonists in treatment.

Use of 12x/month haemoglobin monitoring with a computer algorithm reduces haemoglobin variability.

BACKGROUND: Haemoglobin variability may be associated with increased death. Frequent haemoglobin monitoring may allow earlier detection of trends in haemoglobin slopes, alerting staff to intercurrent events. The more frequent haemoglobin values may provide early evidence of response to erythropoietin (EPO) doses, and allow more appropriate anaemia management. Our objective is to assess whether frequent haemoglobin monitoring data (12x/month) using a computer algorithm (AMIE, Leeds, UK) will reduce haemoglobin variability compared with 1x/month monitoring. METHODS: We performed an observational case-control study of 44 unselected patients, comprising one dialysis facility measuring Crit-Line haemoglobin, lab haemoglobin, standard deviation of residuals as surrogate of haemoglobin variability and EPO dosing. RESULTS: Haemoglobin variability and 'percent in target haemoglobin range' significantly improved with 12x/month haemoglobin results using a computer algorithm. There was also a non-significant trend toward for lower EPO doses. CONCLUSION: Use of a computer algorithm to analyse 12x/month haemoglobin values provides early evidence of haemoglobin trends and allows more appropriate anaemia management, with decreased haemoglobin variability, lower EPO doses and more patients achieving target haemoglobin.

Isolation and characterization of LCHN: a novel factor induced by transient global ischemia in the adult rat hippocampus.

Using mRNA differential display to identify cerebral ischemia-responsive mRNAs, we isolated and cloned a cDNA derived from a novel gene, that has been designated LCHN. Antisense mRNA in situ hybridization and immunoblotting confirmed LCHN expression to be induced in the rat hippocampus following transient forebrain ischemia. The deduced amino acid sequence of the novel LCHN cDNA contains an open reading frame of 455 amino acids, encoding a protein with a predicted molecular mass of approximately 51 kDa. Although LCHN is highly conserved between rat, mouse, and human, the deduced amino acid sequence of LCHN does not possess significant homology to other known genes. LCHN immunoreactivity is detected within the somatodendritic compartment of neurons, is also present on dendritic growth cones, but is not detected on astrocytes. The induction of LCHN in the hippocampus following ischemic injury may have functional consequences, as the ectopic over-expression of LCHN generated neurons with longer and more branched axons and dendrites. Taken together, these data suggest that LCHN could play a role in neuritogenesis, as well as in neuronal recovery and/or restructuring in the hippocampus following transient cerebral ischemia.

Perioperative management of patients on oral anticoagulants: a decision analysis.

BACKGROUND: To better inform clinicians on the optimal management of patients on oral anticoagulation who need to undergo surgery or invasive procedures, the authors performed a decision analysis examining whether a perioperative aggressive or minimalist strategy results in greater quality-adjusted survival. METHODS: A decision analysis model was created comparing withholding warfarin (minimalist strategy) to withholding warfarin and administering treatment-dose subcutaneous low-molecular-weight heparin (LMWH) or intravenous heparin perioperatively (aggressive strategy). The base-case analysis examined a hypothetical 60-year-old hypertensive individual with mechanical aortic valve replacement undergoing major abdominal surgery. A probabilistic sensitivity analysis was performed using a Monte Carlo simulation with quality-adjusted life expectancy (QALE) as the outcome. Secondary analyses examined patients with a mechanical mitral valve and atrial fibrillation. Sensitivity analyses were performed for each variable. RESULTS: Under the base-case scenario, the minimalist strategy was preferred for 78% of trials in the Monte Carlo simulation, with a mean benefit of 0.003 years (95% confidence interval, -0.005 years to 0.011 years). Sensitivity analyses based on point estimates indicate that the aggressive strategy is preferred when the annual stroke rate is >5.6% or the increase in postoperative major bleeding induced by heparin is <2.0%; however, the benefit is small over the range of plausible values. CONCLUSIONS: For most patients with a mechanical aortic valve or atrial fibrillation undergoing major surgery, a minimalist strategy of simply withholding oral anticoagulation provides similar QALE as an aggressive strategy of administering perioperative subcutaneous LMWH or intravenous heparin. The aggressive therapy provides greater QALE for patients at higher risk of stroke (e.g., mechanical mitral valves), although the benefit is small.