Sustained beneficial hemodynamic responses to large doses of transdermal nitroglycerin in congestive heart failure and comparison with intravenous nitroglycerin

The hemodynamic effects of a new transdermal preparation of nitroglycerin were evaluated in 9 patients with chronic congestive heart failure (CHF). A graded infusion of nitroglycerin was administered initially to establish the dose-response relation for nitroglycerin and estimate the dose of topical nitroglycerin to be applied. Significant hemodynamic improvement was observed 0.5 to 1.0 hour after the cutaneous application of the nitroglycerin-impregnated polymer. The peak effect occurred at 6 hours, with the left ventricular filling pressure decreasing from 24 ± 2 to 18 ± 1 mm Hg (mean ± standard error of the mean) (p < 0.01) and the cardiac index increasing from 2.0 ± 0.2 to 2.6 ± 0.2 liters/min/m² (p < 0.01). The systemic vascular resistance decreased from 1,860 ± 198 to 1,531 ± 162 dynes s cm^?5 (p < 0.01). Heart rate and mean arterial pressure were unchanged. Significant hemodynamic benefit was observed for 24 hours, and no rebound deterioration occurred upon withdrawal of the drug. The average dose of transdermal nitroglycerin applied was 51 ± 6 cm² (1.7 ± 0.2 mg/kg; 6 of the 9 patients received 64 cm²). Thus, topical application of a new nitroglycerin-impregnated polymer induces an improvement in cardiac performance that is sustained for 24 hours in patients with chronic CHF. However, substantial doses of the drug may be required to produce a satisfactory hemodynamic response in most patients with CHF.     

Classification using ensemble learning under weighted misclassification loss

Binary classification rules based on covariates typically depend on simple loss functions such as zero-one misclassification. Some cases may require more complex loss functions. For example, individual-level monitoring of HIV-infected individuals on antiretroviral therapy requires periodic assessment of treatment failure, defined as having a viral load (VL) value above a certain threshold. In some resource limited settings, VL tests may be limited by cost or technology, and diagnoses are based on other clinical markers. Depending on scenario, higher premium may be placed on avoiding false-positives, which brings greater cost and reduced treatment options. Here, the optimal rule is determined by minimizing a weighted misclassification loss/risk. We propose a method for finding and cross-validating optimal binary classification rules under weighted misclassification loss. We focus on rules comprising a prediction score and an associated threshold, where the score is derived using an ensemble learner. Simulations and examples show that our method, which derives the score and threshold jointly, more accurately estimates overall risk and has better operating characteristics compared with methods that derive the score first and the cutoff conditionally on the score especially for finite samples.     

探讨急性脑梗死不同治疗方法的TOAST分型及其影像学表现

目的应用多模磁共振扩散加权成像-灌注加权成像分析急性脑梗死不同治疗方法的影像学表现特征。材料与方法回顾性分析在我院神经内科住院治疗的急性脑梗死患者110例,所有患者均行多模磁共振检查,记录其影像学表现、临床资料和实验室常规检查,并根据结果行扩散加权成像(diffusion weighted imaging,DWI)分型及急性卒中治疗Org 10172试验(trial of org 10172 in acute stroke treatment,TOAST)分型,根据不同治疗方法分为静脉溶栓组(43例)、动脉取栓组(34例)及保守治疗组(33例),并对3组的影像学及临床资料进行统计学分析。结果 (1)动脉取栓组患者存在半暗带及血管高信号征的比率均高于静脉溶栓组及保守治疗组,差异均有统计学意义(F=13.713,P=0.001;F=8.108,P=0.017)。(2)在DWI分型构成比方面,静脉溶栓组以小穿支梗死及单侧前循环梗死所占比率较大(25.58%、23.26%),动脉取栓组和保守治疗组以单侧前循环及前-后循环所占比率较大(52.94%、21.43%;30.30%、30.30%)。(3)在TOAST分型构成比方面,静脉溶栓组以大动脉粥样硬化型(largeartery atherosclerosis,LAA)所占比率最高(39.53%),动脉取栓组以不明原因型(undetermined etiology,UND)所占比率最高(73.53%),保守治疗组以小动脉闭塞型(small artery occlusion,SAO)所占比率最高(48.48%)。(4)在磁共振血管造影(magnetic resonance angiography,MRA)影像学表现上,静脉溶栓组及保守治疗组MRA表现正常所占比率最高(72.09%、51.52%),而动脉取栓组MRA表现为大脑中动脉狭窄或闭塞所占比率最高(41.18%)。(5)3组间比较,动脉取栓组的出血转化率最高(26.47%),差异有统计学意义(F=6.462,P=0.040)。(6)入院美国国立卫生研究院卒中量表(National Institute of Health stroke scale,NIHSS)评分及高血脂症在3组间比较差异具有统计学意义(t=6.209,P=0.003;F=6.176,P=0.046)。(7)保守治疗组发病时间(6.55±4.70)长于静脉溶栓组(2.93±1.05)及动脉取栓组(3.07±2.51),3组间差异有统计学意义(t=16.246,P=0.000)。结论了解不同治疗方法患者的影像学表现特征,可帮助临床医生根据具体情况选择合理的治疗方案,实现个性化治疗。     

A note on the surface topography of profiled wood decking

Profiled wooden deck-boards with small peaks and grooves machined into their surface are preferred in many countries to flat deck-boards because profiling makes the surface less slippery and prone to checking. Numerous companies manufacture profiled decking, and in this paper we examine the variation in topography of profiled wood decking. The topography of commercial profiled decking used in seven different countries was quantified using confocal profilometry, and principal components analysis was used to explore variability in topography between profiled decking samples and relationships between them. Confocal profilometry was able to measure the topography of profiled decking. We observed large variation in the height and width of profile peaks and also their peak and groove radii. Profiled decking can be classified into three morphological groups using the ratio of radii of surface grooves to those of peaks. Two of these groups, ribbed and rippled decking have been mentioned previously, but we identify and name a third group (ribble profile) with surface topography that lies between those of ribbed and rippled profiles. Our method of classifying profiles makes it possible to identify different types of profiled decking and provides a way of systematically comparing how profile topography influences the ability of profiles to restrict the checking of wood.     

Diabetic ketoacidosis. Induction of hypocalcemia and hypomagnesemia by phosphate therapy.

A nine year old boy with previously undiagnosed diabetes mellitus presented with severe ketoacidosis. His hyperglycemia (plasma glucose = 786 mg/dl), acidosis (arterial pH = 6.86), dehydration and coma responded well to therapy with intravenous fluids, bicarbonate and insulin. Potassium supplementation was given as a phosphate salt.Despite marked clinical and biochemical improvement, 28 hours after therapy was initiated he was found to have profound hypocalcemia (2.6 meq/liter), hypomagnesemia (0.8 meq/liter) and hyperphosphatemia (9.2 mg/dl). All three electrolyte levels had been normal upon admission, and they were gradually corrected with appropriate supplementation of calcium and magnesium and discontinuation of the intravenous phosphate. We interpret these iatrogenic electrolyte abnormalities in the patient described to have been the result of the massive phosphate load administered, resulting not only in hypocalcemia, but also in hypomagnesemia that inhibited parathyroid hormone release.Current recommendations suggest replacement of the potassium losses in diabetic ketoacidosis with the phosphate salt to compensate for depleted stores of 2,3-diphosphoglycerate. We caution physicians that such a regimen can result in severe electrolyte disturbances which potentially may be life threatening. Judicious use of potassium phosphate as an adjunct to traditional potassium chloride therapy, and close monitoring of serum calcium, magnesium and phosphorus, appears to be a preferable therapeutic regimen than potassium phosphate alone.     

Guidelines for epilepsy management in India classification of seizures and epilepsy syndromes

This article is part of the Guidelines for Epilepsy management in India. This article reviews the classification systems used for epileptic seizures and epilepsy and present the recommendations based on current evidence. At present, epilepsy is classified according to seizure type and epilepsy syndrome using the universally accepted International League Against Epilepsy (ILAE) classification of epileptic seizures and epilepsy syndromes. A multi-axial classification system incorporating ictal phenomenology, seizure type, epilepsy syndrome, etiology and impairments is being developed by the ILAE task force. The need to consider age-related epilepsy syndromes is particularly important in children with epilepsy. The correct classification of seizure type and epilepsy syndrome helps the individual with epilepsy to receive appropriate investigations, treatment, and information about the likely prognosis.