Imipramine binding sites on platelets of patients with major depressive disorder

[No abstract available]Articl

Central effects of the preservative, methylparaben. In vivo activation of cAMP-specific phosphodiesterase and reduction of cortical cAMP

The phenolic preservative, methylparaben (MPB), has in the past been demonstrated to harbour definite pharmacological effects. In an attempt to examine the possible central effects of MPB, notably on cyclic nucleotides and cyclic nucleotide phosphodiesterase (PDE; EC 3.1.4.17), rats were orally treated with the drug (0.4% in rat food) for 3 weeks with cortex extracts being used for the various determinations. Three isozymes were identified by DEAE-cellulose anion exchange chromatography, namely the calmodulin/calcium-stimulated form or PDE I (peak I), the cGMP-stimulated form or PDE II (peak II), and an independent form not affected by either calmodulin or cGMP also known as PDE IV (peak III). The presence of MPB induced a significant decrease in cortical cAMP, as well as strongly stimulating the activity of PDE IV (peak III). In addition, a small, yet significant, increase in cGMP levels was observed. Since no increase in cGMP hydrolysis was observed, we conclude that chronic ingestion of MPB induces a preference for cAMP hydrolysis, which was confirmed by the increase in PDE IV (peak III) activity. PDE IV is a membrane-bound, low K(m) PDE exhibiting high selectivity for cAMP hydrolysis. While there was an increase in cGMP, we failed to observe an increase in the activity of the cGMP-stimulated PDE (PDE II). These data are discussed with reference to the possible membrane effects of MPB allowing it to alter both the kinetic properties of PDE IV with the resultant effects on cAMP, as well as a means whereby it may activate guanyl cyclase and increase cGMP.Articl

The diagnostic utility of adenosine deaminase isoenzymes in tuberculous pleural effusions

SETTING: Pleural adenosine deaminase (ADA) levels have been found to be useful in diagnosing tuberculous pleuritis. Elevated ADA levels have been attributed to ADA2 isoenzyme, although no comprehensive studies have evaluated ADA2 as a diagnostic test. OBJECTIVE: To estimate the diagnostic accuracy of ADA and ADA2 in diagnosing tuberculous pleurisy. METHOD: A 3-year retrospective study was carried out. ADA and ADA 2 were determined on patients diagnosed according to predetermined criteria. RESULTS: A total of 951 samples were received, including 387 patients with tuberculosis (TB). ADA values ≥52.4 U/l yielded a sensitivity, specificity and positive (PPV) and negative predictive value (NPV) respectively of 93.7% (95%CI 90.0-96.0), 88.7% (95%CI 85.7-91.3), 85.5% (95%CI 81.7-88.8) and 95.2% (95%CI 92.9-96.9). ADA2 values ≥40.6 U/l yielded a sensitivity, specificity and PPV and NPV of respectively 97.2% (95%CI 95.0-98.7), 94.2% (95%CI 91.8-96.0), 92.2% (95%CI 89.1-94.7) and 98.0% (95%CI 96.3-99.0). The χ2 and McNemar tests proved the superiority of ADA2 statistically. CONCLUSION: ADA2 is superior to ADA in the diagnosis of tuberculous pleuritis and should be used as a routine test in the diagnostic work-up of patients with pleural effusions in areas with high TB prevalence. © 2009 The Union.Articl

How effective is the Department of Health's leaflet on HIV/ AIDS Counselling for low literate South Africans?

Comprehension of what is communicated in a text can be tested to check a text's effectiveness. In most text types, including persuasive texts, comprehension is the prerequisite for successful information processing. In this contribution the effectiveness of the South African National Department of Health's multilingual leaflet on HIV/AIDS Counselling is evaluated. The questions posed were about whether low-literate South Africans could comprehend and remember the message in the leaflet. Structured interviews were used to research these possibilities when low-literate African language speakers had read them. It was found that the majority of the respondents was not able to recall the main points of the message, or to formulate the content of key paragraphs in their own words. Despite possible inherent errors in the research design, our conclusion was that the leaflet is not effective in conveying its message among low-literate South Africans. The confusing outer structure of the leaflet and prior knowledge based on cultural understanding of the topic might have caused a cognitive overload for the readers and made the message incomprehensible to them. On the basis of our findings we designed a checklist which translates comprehensibility and memorability into textual characteristics which are measurable. This instrument can be of assistance to document designers who have to evaluate such characteristics in materials for low-literates

Phosphorylation increases α-bungarotoxin binding to acetylcholine receptor-enriched membrane preparations

Acetylcholine receptor (AChR)-enriched membrane preparations from Torpedo electroplax bind α-bungarotoxin with a K(D) of 8.4 nM and the concentration of binding sites is 16 pmoles/mg protein. When, however, the α-toxin is incubated with receptor samples, phosphorylated in the presence of Mn2+ (10 mM) and ATP (0.5 mM), the concentration of binding sites is increased to 94 pmoles/mg protein, although there is no marked change in the K(D) (11 nM). Binding of acetylcholine to AChR-enriched membrane preparations occurs at a receptor which has two different conformational states with K(D)'s of 8.4 nM and 520 nM. The concentration of binding sites for the high affinity components is 1.35 pmoles/mg protein and for the low affinity component is 12 pmoles/mg protein. The effect of phosphorylation of the AChR on agonist binding could not be determined.Articl

Alpha2-adrenoceptor levels on platelets of patients with major depressive disorders

[No abstract available]Articl

Characterization of protein phosphorylation in acetylcholine receptor-enriched membrane preparations from torpedo fuscomaculata

When the acetylcholine receptor (AChR*) from Torpedo is phosphorylated, ATP is found to bind non-covalently to the preparation. After correction is made for this binding of ATP, the phosphorylation reaction has a Km of 0,16 mM, a pH optimum of 8,6 and reaches maximal activity within 3 min. The intrinsic kinase activity is very specific for the AChR and does not phosphorylate either histones or phosvitin. The only amino acid to be phosphorylated is serine and cyclic GMP causes stimulation of the reaction. © 1982 Martinus Nijhoff/Dr W. Junk Publishers.Articl