Abdominal tuberculosis: a presumptive diagnosis

BACKGROUND: Abdominal tuberculosis (TB) is common. But the diagnosis of abdominal TB is fraught with difficulties as it is often not possible to get a microbiological confirmation of the infection. We therefore undertook this study to highlight those pertinent clinical and laboratory features which would enable one to make a provisional diagnosis of abdominal TB early, to pave way for a trial of anti-tuberculosis chemotherapy. METHOD: This is a retrospective study of 12 patients treated for abdominal TB in our department over a period of 2 years. FINDINGS: Seven of the patients suffered from chronic diarrhoea for periods ranging from 4 weeks to 12 months. Four patients had progressive abdominal distension (ascites). The last patient came in with multiple abdominal swellings. Seven patients had clinical and biochemical features of malabsorption. Another 9 patients also had persistent pyrexia. The ascitic fluid was exudative in the 4 patients mentioned earlier. A definitive diagnosis could not be established in any of these patients. The diagnosis of abdominal TB was thus one of exclusion in these patients who showed prompt response to anti-tuberculosis therapy. CONCLUSION: Our study justifies a trial of anti-TB chemotherapy in TB endemic areas in the following clinical situations: (a) patients with chronic diarrhoea of unknown aetiology and (b) patients with exudative ascitic fluid, after all other possible causes, have been excluded. A prompt response to anti-TB therapy should be accepted as sufficient ground for the diagnosis of abdominal TB even when histopathological or microbiological confirmation of the disease is not possible. Our study reflects the experience of other workers from Third World countries.     

Adenosine in the mammalian heart: nothing to get excited about

Until quite recently, the cardiodepressant actions of adenosine were widely accepted. A nucleoside that produces negative chronotropic and ionotropic effects, adenosine, has been used clinically as the drug of choice for terminating supraventricular (atrioventricular node) tachycardia and is likely to play an important part in regulating arrhythmogenic activity as an endogenous antiarrhythmic metabolite. Despite this, recent experimental data, particularly resulting from in vitro studies using animal models, have shown a paradoxical excitable action of adenosine in the heart. In this article, Amir Pelleg and Steven Kutalek present the reasons why they continue to believe that any excitatory actions of adenosine in the heart are clinically irrelevant.     

Distinct stability of recombinant L and H subunits of human ferritin: calorimetric and ANS binding studies

Thermodynamic and pH stability of recombinant human L- and H-ferritins were probed by differential scanning calorimetry and 8-anilino-1- naphthalenesulfonate (ANS) binding in the pH range 2-7. At pH 2.0-2.8 they were dissociated into subunit monomers and in this pH interval the H-subunit displayed a single calorimetrically-revealed domain with properties of a molten globule-like state: low enthalpy (6.3-8.0 J/g or 169-172 kJ/mol) and Tm of thermal unfolding (approximately 50 degrees C), a wide transition range (approximately 20 degrees C) and high ANS binding. In contrast, at pH 2 the L-ferritin subunit showed two calorimetric domains with Tm of 35 and 40 degrees C with similar unfolding enthalpies and with moderate extent of interactions, as indicated by the ratio of calorimetric enthalpy (293.9 kJ/mol) and van't Hoff enthalpy (174.2 kJ/mol) for the thermal transition. A pH increase from 2.0 to 2.8 determined the coupling of the two domains into a single cooperative folding unit and drastic increase of the transition temperature (from 37 to 80 degrees C). The contacts between the two domains in the L-subunit appeared to contribute to about 30% of the total stabilization free energy. The unfolding enthalpies, heat capacity changes and pronounced ANS binding of the L-subunit at pH 2.0- 2.8 indicated that part of the structure lacked 'meltable' tertiary interactions. The results indicate that H- and L-subunits are stabilized by largely different intra-chain interactions with a critical contribution to L-subunit stability of embedded salt bridge(s) absent in the H-subunit.      

Primary bovine hepatocytes in the study of cytokine induced acute-phase protein secretion in vitro

OBJECTIVE: To determine placental transfer of ketanserin and to assess the effect of serotonin-2 receptor blockade by ketanserin on serotonin- and phenylephrine-induced vasoconstriction. STUDY DESIGN: Five chronically instrumented pregnant ewes at 120 days gestation were injected with 20 mg ketanserin i.v., and fetal and maternal arterial samples were obtained at predetermined intervals to assess placental transfer. Maternal and fetal responses of blood flows and pressures were determined after injected of serotonin (20 micrograms/kg) or phenylephrine (10 micrograms/kg) before and after ketanserin (0.75 mg/kg). RESULTS: In the ewe, ketanserin is transferred across the placenta and reaches measurable levels in the fetal lamb. Ketanserin blocks the maternal and fetal serotonin-induced rise in arterial pressure, but not the serotonin-induced reduction in uterine blood flow. CONCLUSION: In the pregnant ewe, the serotonin-induced rise in maternal and fetal blood pressure is effectively antagonized by ketanserin, whereas the serotonin-induced reduction in uterine blood flow is not.