Physical chemistry of polymers. VIII. Viscosimetric titration of acrylic acid — methacrylic acid copolymers

A study of the viscosimetric titration of acrylic acid - methacrylic acid copolymers (AA-MA) was made and the η_sp/C = f(α) curves at different ionic strength were determined. It was proved that the area under this function is proportional to the number of dissociated ionogenic groups of a macromolecule z = n?·α·j^?1 and on the other hand to the maximum value of the reduced viscosity (η_sp/C)_max.     

How efficient is acoustic radiation force impulse elastography for the evaluation of liver stiffness?

Background

In chronic liver diseases, a correct estimation of the severity of liver fibrosis is important for recommendations regarding the treatment. Nowadays, evaluation of fibrosis is done by noninvasive methods such as biochemical scores and transient elastography instead of liver biopsy. The lack of sensitivity to detect fibrosis, because of its heterogeneity is a drawback of liver biopsy (LB).

Objectives

To compare transient elastography (TE) and acoustic radiation force impulse (ARFI) for the evaluation of liver stiffness (LS), against percutaneous LB.

Patients and Methods

Our study comprised of 223 subjects; 52 without fibrosis (38 volunteers and 14 patients with F0 on LB), 36 with F1, 40 with F2, 26 with F3 and 69 with liver cirrhosis (46 with LB and 23 with signs of cirrhosis). For each patient we performed in the same session 10 TE and 5 ARFI measurements. The median values were calculated.

Results

A strong linear correlation (Spearman rho = 0.870) was found between TE and fibrosis (P < 0.0001); there was also a weaker correlation between ARFI and fibrosis (Spearman rho = 0.646; P < 0.0001). TE measurements were also correlated with ARFI measurements (Spearman rho = 0.733, P < 0.0001). The best test for predicting significant fibrosis (F ≥ 2) was TE with a cut-off value of 7.1 kPa (AUROC 0.953). For ARFI, the cut-off value was 1.27 m/s-area under ROC curve (AUROC): 0.890, sensitivity (Se) of 88.7%, specificity (Sp) of 67.5%, positive predictive value (PPV) of 64.5%, and negative predictive value (NPV) of 90% (P = 0.0044). For predicting cirrhosis (F = 4), the optimum cut-off values were 14.4 kPa for TE (AUROC: 0.985, Se: 95.6%, Sp: 94.7%, PPV: 89.2%, NPV: 98%) and 1.7 m/s for ARFI (AUROC: 0.931, Se: 93%, Sp: 86.7%, PPV: 73.6%, NPV: 96.9%) (P = 0.0102).

Conclusions

LS evaluation by means of ARFI is not superior to TE for the assessment of liver fibrosis. ARFI is an accurate test for the diagnosis of cirrhosis.     

Treatment of ligament laxity by electrothermal shrinkage or surgical plication: a morphologic and mechanical comparison

Capsular plication or thermal shrinkage can be used to enhance surgical joint stabilization. We compared mechanical or morphologic properties of the medial collateral ligament of the rabbit knee treated by either bipolar radiofrequency electrothermal shrinkage or surgical plication. After 12 weeks, the medial collateral ligaments were procured from treated and contralateral knees to undergo viscoelastic (creep) testing, quantitative transmission electron microscopy, and immunohistochemistry. Creep strain in thermal (1.85% +/- 0.32%) and plicated (1.92% +/- 0.36%) ligaments was almost twice that of the control group (1.04% +/- 0.15%), although there was no difference between treatment modalities. The morphologic parameters of all 3 groups were significantly different (P < .001). The thermal ligaments demonstrated predominantly small fibrils, whereas the plicated group displayed an intermediate distribution of heterogeneous fibrils, suggesting a different pattern of remodeling. Viscoelastic properties are similar after thermal shrinkage or plication, though inferior to those of intact ligaments.     

Acute cocaine induced deficits in cognitive performance in rhesus macaque monkeys treated with baclofen

Rationale

Acute and/or chronic exposure to cocaine can affect cognitive performance, which may influence rate of recovery during treatment.

Objective

Effects of the GABA-B receptor agonist baclofen were assessed for potency to reverse the negative influence of acute, pre-session, intravenous (IV) injection of cocaine on cognitive performance in Macaca mulatta nonhuman primates.

Methods

Animals were trained to perform a modified delayed match to sample (DMS) task incorporating two types of trials with varying degrees of cognitive load that had different decision requirements in order to correctly utilize information retained over the delay interval. The effects of cocaine (0.2, 0.4, and 0.6 mg/kg, IV) alone and in combination with baclofen (0.29 and 0.40 mg/kg, IV) were examined with respect to sustained performance levels. Brain metabolic activity during performance of the task was assessed using PET imaged uptake of [¹⁸?F]-fluorodeoxyglucose.

Results

Acute cocaine injections produced a dose-dependent decline in DMS performance selective for trials of high cognitive load. The GABA-receptor agonist baclofen, co-administered with cocaine, reversed task performance back to nondrug (saline IV) control levels. Simultaneous assessment of PET-imaged brain metabolic activity in prefrontal cortex (PFC) showed alterations by cocaine compared to PFC metabolic activation in nondrug (saline, IV) control DMS sessions, but like performance, PFC activation was returned to control levels by baclofen (0.40 mg/kg, IV) injected with cocaine.

Conclusions

The results show that baclofen, administered at a relatively high dose, reversed the cognitive deficits produced by acute cocaine intoxication that may have implications for use in chronic drug exposure.     

Drug related deaths between 2008 and 2011. A retrospective study in 32 Romanian counties

The purpose of this study is to determine the pattern of drug related deaths in Romania between 2008 and 2011 by analyzing the medical-legal cases, from a significant proportion of Romanian Counties (out of 41 plus the capital), in which the direct causal link between drug overdose and death was drug related. Material and methods. 446 forensic toxicology cases were analyzed in a four year period, obtained from more than two thirds of the counties in Romania. Results. 54.26% yielded a positive toxicological analysis, most often with benzodiazepines, opiates, barbiturates and cannabinoids. Males around 31 years old represented the most affected group. Illegal drug related deaths were more frequent in males and non-illegal drug related deaths were proportionally more frequent in females. Discussions and conclusions. The pattern of consumption is similar to the one obtained by similar studies in neighboring countries. The city capital has a very distinct pattern of consumption compared to other cities/counties.