The effect of bacterial melanin on electrical activity of neurons of the substantia nigra under conditions of GABA generation

The changes in spike activity of single neurons of the compact part of the substantia nigra, evoked by nucleus caudatus stimulation under conditions of long-term registration of the single and multiple, isolated and combined actions of GABA, GABA-amide, glutamine, and ethanolamine-O-sulfate (EOS) were studied in albino rats. Inhibition of poststimulus activity under GABA action was recorded and the inhibitory effect of GABA-amide was revealed. Primary excitatory and subsequent inhibitory effects of glutamine in combination with EOS were shown. The subsequent administration of bacterial melanin, synthesized by a mutant culture of Bacillus thuringiensis (BT-M) evoked a clear-cut and prolonged excitatory reaction during all the combined actions of GABA, GABA-amide, glutamine, and EOS. Preliminary administration of BT-M abolished the inhibitory poststimulus effects of GABA, GABA-amide, and EOS, as well as glutamine-induced excitation.     

Does the establishment of a Vascular Unit reduce the prevalence of ruptured aortic aneurysms?

AIM: The aim of this study was to assess the effect of a specialised Vascular Unit upon the prevalence of ruptured aortic aneurysms in the same population catchments' area and associated mortality rates. METHODS: Setting: prospective computerised data collection from 1997 to today, retrospective from 1990-1996. Subjects: 108 aneurysms were operated upon from 1990-1996, compared to 317 from 1997 to Aug 2002. Main outcome measures: statistical analysis was done using SPSS statistics with Kaplan Meier life table curves and compared by the log rank test while the Mann Whitney test was used for comparison of mortality. RESULTS: The median values for ruptured aneurysms per year were 5 for the early period, compared to 10 for the recent years, while the median values for both urgent and ruptured were 7 and 18.5 cases annually, respectively. The number of scheduled procedures increased by 500% in the second period, with median values of 7 and 36.5, respectively. In-hospital mortality according to category was 21% for scheduled, 31% for urgent and 69% for ruptured aneurysms in the early period, compared to 3.7%, 16% and 29% respectively, following the establishment of the Vascular Unit. CONCLUSION: Despite the five-fold increase in the total number of aortic aneurysm repairs (as expected), the number of ruptured aneurysms operated upon increased as well. There was just a trend for a reduction in the absolute numbers of ruptured aneurysms operated upon in the last 2 years. Mortality, on the other hand, decreased dramatically in all categories, with the overall 30-day mortality decreasing more than four-fold, from 40% to 9.3%, while the respective mortalities according to the category of intervention were 3.7% vs 21% for scheduled, 16% vs 35% for urgent and 29% vs 69% for ruptured aneurysms, with a P value of less than 0.01. However, there was no difference in the numbers of patients with ruptured aneurysm reaching the hospital (operated or not) between the two periods (median values of 11 and 10.5 annually). The presence of a Vascular Unit, although it achieves dramatically better results, is not associated with a reduction in the number of emergency proceduresaeat least in the intermediate termaedespite an expansion in the indications for surgery, increased awareness and prompt referrals (centralisation).     

Densitometry for assessment of effect of lung volume reduction surgery for emphysema.

To explore if change in the extent of emphysema correlated with change in lung function, the effect of resection of emphysematous tissue was studied by computed tomography (CT) densitometry. In addition, the current authors studied how surgery-induced change in emphysema related to lung density in control subjects. In total, 30 patients (14 females; mean+/-sd age 59+/-10 yrs) with severe emphysema before and 3 months after lung volume reduction surgery (LVRS), 48 patients with moderate emphysema and 76 control subjects were investigated. Lung density (15th percentile point) of both lungs and heterogeneity of lung density between 12 isovolumetric partitions in each lung were calculated from chest CT images. The 15th percentile point and its heterogeneity could distinguish controls from subjects with moderate emphysema with a sensitivity and specificity of >95%. LVRS significantly increased lung density by 5.0+/-10.9 g.L(-1) (n=30). Improvement in the diffusing capacity of the lung for carbon monoxide and in residual volume significantly correlated with an increase in lung density (n=20 and 28, respectively). Change in forced expiratory volume in one second did not correlate with change in lung density. In conclusion, lung density 15th percentile point is a valuable surrogate marker for detection of both the extent of and reduction in emphysema.