Theophylline metabolism in acute asthma with MxA-indicated viral infection

BACKGROUND: Although viral infection might alter theophylline metabolism in acute asthma, there are some difficulties in detecting infection due to various kinds of viruses in a clinical setting. METHODS: To evaluate the usefulness of assessment of MxA protein in acute asthma exacerbated by viral infection, MxA protein expression in lymphocytes was assayed by flow cytometric analysis in whole peripheral blood in 21 children (aged 0-6 years) receiving continuous theophylline infusion for management of asthma attack. Serum theophylline levels were measured at 24 and 72 h after initiating theophylline infusion. RESULTS: At the beginning of theophylline infusion, 11 children had increased expression of MxA protein, indicating viral infected states. After 24 h continuous infusion, there were no differences in theophylline levels between MxA-negative and MxA-positive groups. After 72 h infusion, the mean theophylline level of MxA-positive children was significantly higher than that of MxA-negative children (9.7 +/- 2.2 microg/mL vs 7.3 +/- 1.6 microg/mL). The ratio of theophylline clearance at 72 h to that at 24 h in the MxA-positive group was significantly lower than that of the MxA-negative group (1.1 +/- 0.2 vs 1.4 +/- 0.1). CONCLUSIONS: Viral infection appeared to affect theophylline metabolism. Flow cytometric assay of lymphoid MxA protein expression in whole blood is an easy and useful method of evaluating viral infection in acute asthma exacerbation.     

Experimental acute glomerulonephritis induced in the rabbit with a specific streptococcal antigen

FITC-labelled IgG obtained from patients convalescing from acute poststreptococcal glomerulonephritis (APSGN) stains glomeruli of patients with early APSGN. We previously reported a streptococcal antigen (preabsorbing antigen (PA-Ag)) that preabsorbed the stain out of sera from the convalescent patients and thus prevented glomerular staining. To confirm the nephritogenicity of PA-Ag, we administered up to 40 mg of this antigen to rabbits for 8 days and observed them for up to 9 weeks. Immunohistological analysis showed diffuse and global glomerular staining for C3 without notable staining for γ-globulin. Light microscopic examinations revealed slight to moderate proliferative glomerulonephritis with exudative change. Control rabbits, which received similar doses of bovine serum albumin, did not show significant staining for C3. A transient and significant decrease in CH₅₀ was observed from weeks 3 to 7 (9.7 ± 0.3 U/ml at week 3; normal range 12.9 ± 0.6 U/ml). This experimental model showed a resemblance to immunological and immunohistological features of APSGN in humans. Although the precise mechanisms are yet to be determined, complement activation by PA-Ag seems to hold a key position in this model and in the human disease.     

Latent cerebral artery stenoses on magnetic resonance angiography in a patient diagnosed as probable Alzheimer disease

Abstract A 65-year-old woman with hypertension developed slowly progressive memory disturbance and disorientation. She was diagnosed as having Alzheimer-type dementia according to clinical criteria. Later her cognitive deterioration was noted to fluctuate in parallel to her blood pressure. Magnetic resonance angiography and single photon emission computed tomography showed bilateral middle cerebral artery stenoses and middle cerebral artery watershed dominant hypoperfusion. It is postulated that the patient's cognitive disturbance may have originated from vascular lesions.     

Pravastatin transport across the hepatocyte canalicular membrane requires both ATP and a transmembrane pH gradient

Hepatic excretion of non-bile acid organic anions is reported to be ATP-dependent and a defect of this transport has been reported in congenitally jaundiced rats, animal models of human Dubin-Johnson syndrome. To investigate the effect of the transmembrane pH gradient on hepatocyte canalicular membrane transport of ATP-dependent organic anions, uptake of pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase-inhibiting organic anion, by hepatocyte canalicular membrane vesicles was observed in the presence or absence of transmembrane pH gradients. Uptake was assessed by a rapid filtration technique. ATP-dependent pravastatin uptake was stimulated in the presence of a transmembrane pH gradient (in > out) in Sprague-Dawley (SD) rats. Uptake was dependent on both pravastatin and ATP concentrations and showed saturation kinetics. After intravenous injection of [¹⁴C]-pravastatin (0.3 μmol), 81% of the dose was excreted in the bile within 35 min in SD rats, whereas only 20% was excreted in the bile in Eisai hyperbilirubinuria rats. ATP and the pH gradient also co-stimulated the uptake of pravastatin in Eisai hyperbilirubinuria rats, although the K_m was much higher and V_max was much lower than corresponding values in SD rats. This coincided well with the marked reduction in in vivo biliary excretion of pravastatin in jaundiced rats.