Forskolin potentiates myocardial reactive hyperaemia in the open chest dog: the contribution of adenylate cyclase

Forskolin, a diterpene, directly stimulates adenylate cyclase and also potentiates receptor mediated stimulation of this enzyme by many stimulatory agonists. We exploited the potentiating effect of forskolin to test the hypothesis that activation of adenylate cyclase contributes to myocardial reactive hyperaemia, especially by release of adenosine at the time of brief coronary occlusions. In 10 open chest dogs, intracoronary forskolin infusions which produced plasma concentrations between 0.22 and 0.34 mumol.litre-1 slightly increased coronary blood flow and had no effect on haemodynamics or myocardial metabolism. Under these conditions, though peak reactive hyperaemic flow rates were not affected, forskolin infusions reversibly potentiated repayments of flow debt by 28, 25 and 27% following coronary occlusions of 15 s, 20 s and 30 s, respectively (p less than 0.05). In another seven dogs, after observations of the effects of forskolin (0.16-0.26 mumol), 10 mumol of 8-phenyltheophylline, a potent adenosine antagonist, was infused simultaneously with forskolin into the coronary arteries. Forskolin increased debt repayments by about 23-27% following 15 s, 20 s and 30 s occlusions, but with simultaneous 8-phenyltheophylline, forskolin induced increments in the debt repayments were reduced significantly (p less than 0.05). These results indicate that adenylate cyclase contributes to myocardial reactive hyperaemia, and adenosine has a significant role as metabolic regulator of reactive hyperaemia through activation of adenylate cyclase.     

Assessment of abnormal left atrial relaxation by transesophageal pulsed doppler echocardiography of pulmonary venous flow velocity

Background: Several studies on left ventricular relaxation have been undertaken in the past: however, left atrial (LA) relaxation has not been fully evaluated. Hypothesis: The purpose of this study was to assess abnormalities in LA relaxation by evaluating pulmonary venous flow velocity and interatrial septal motion using transesophageal echocardiography. Methods: The subjects were 56 untreated patients in sinus rhythm, including 25 with previous myocardial infarction, 9 with hypertrophic cardiomyopathy, 11 with dilated cardiomyopathy, as well as 11 with chest pain syndrome as controls. Peak first systolic velocity (PVS₁), peak atrial systolic velocity (PVA), and their time-velocity integrals (PVS₁-I and PVA-I, respectively) were calculated from the pulmonary venous flow velocity. Results: The PVS₁ and PVS₁-I correlated negatively with the maximum LA dimension and mean pulmonary capillary wedge pressure, and correlated positively with the amplitude of the interatrial septal motion during LA relaxation and percent fractional LA relaxation. The PVA and PVA-I did not correlate with the mean pulmonary capillary wedge pressure. There was a weak positive correlation between PVA and PVS₁, and a close positive correlation between the ratio of PVA to PVS₁ and mean pulmonary capillary wedge pressure. Multiple regression analysis indicated that the PVS₁ was most closely related to percent fractional LA relaxation, followed by mean pulmonary capillary wedge pressure. Conclusion: The PVS₁ determined from the pulmonary venous flow velocity is closely related to parameters of LA relaxation which may be determined by transesophageal M-mode echocardiography, and the ratio of PVA to PVS₁ is useful for noninvasive evaluation of LA pressure..     

Measurement of the Expiratory Ammonia Concentration and its Clinical Significance

Alghough gaseous ammonia (NH₃) can freely enter cells through the plasma membrane where NH₃ is cyto(neuro)toxic, NH₃ and ionic ammonia (NH₄ ⁺) contents have not been studied in biological materials. We developed a new method for measurement of expiratory NH₃ concentration, which may reflect blood NH₃ concentrations. The method is a sensor tube type-gas assay system. Expiratory NH₃ concentrations in patients with chronic liver diseases increased when their blood ammonia (NH₄ ⁺+NH₃) concentrations increased above 90 μg/dl (normal range; 12–66 μg/dl). However, cirrhotic patients, who had relatively higher expiratory NH₃ concentration compared to blood NH₃ concentrations (calculated from Henderson-Hasselbalch formula), were found to have subclinical encephalopathy. Measurement of experatory NH₃ concentration may be of clinical significance for the diagnosis of encephalopathy associated with hyperammonemia.     

Reduced helper (OKT4 +): suppressor (OKT8 +) T ratios in aplastic anaemia: relation to immunosuppressive therapy

T cell subset composition of peripheral blood and bone marrow from 22 patients with aplastic anaemia (AA) was studied by monoclonal antibodies (OKT3, OKT4 and OKT8). In the peripheral blood, OKT3 (pan-T), OKT4 (helper/inducer-T) and OKT8 (suppressor-T) cells varied widely in number. The ratios of OKT4:OKT8 exhibited the same tendency. However, a subgroup of AA with a reduced ratio of lower than 1.0 was present both in cases with or without prior prednisolone therapy. Of the eight patients treated with immunosuppressants, four with reduced ratios responded, whereas the other four with normal or higher ratios did not. The ratios of two of four responders gradually reached the normal level. These results suggest that the reduced OKT4:OKT8 ratio may be related to the cell-mediated immunosuppressive mechanism postulated as a cause of stem cell inhibition in a subgroup of AA, and indicate prospectively the effectiveness of immunosuppressive therapy.     

A Retrospective Study on Transmission of Adult T Cell Leukemia Virus by Blood Transfusion: Seroconversion in Recipients

Possible transmission of adult T cell leukemia virus (ATLV) by blood transfusion was studied retrospectively. Of 41 recipients of whole blood or blood components containing cells from donors having antibodies to antigen that is associated with ATLV (anti-ATLA), 26 (63.4%) produced anti-ATLA. However, no anti-ATLA was detected in all 14 recipients of fresh-frozen plasma prepared from anti-ATLA-positive donors. None of 252 recipients of blood with cell components from anti-ATLA-negative donors produced anti-ATLA. The development of anti-ATLA in the recipients may correspond to antibody production after establishment of primary infection with ATLV that is associated with cells in blood from anti-ATLA-positive donors who are ATLV carriers.     

Up-regulation of connexin45 in heart failure

INTRODUCTION: Heart failure is associated with reduced expression of the major gap junction protein connexin43 (Cx43), which may contribute to arrhythmias and sudden cardiac death in this patient population. Other cardiac connexins may be altered as well. Because connexin45 (Cx45) has been shown to colocalize with Cx43, we determined whether the number, size, or distribution of Cx45 gap junctions is altered in the failing heart. METHODS AND RESULTS: Cx45 expression levels were measured by immunoblotting and quantitative immunostaining in failing and control human left ventricles. Total Cx45 protein was significantly (P = 0.021) up-regulated 1.8-fold in failing hearts. Cx45 immunohistochemical signal was increased by 80% (P = 0.005) due to a 3.5-fold increase in the number of gap junctions containing Cx45. Cx45 mRNA was not altered in failing hearts, suggesting reduced degradation of Cx45 protein in the failing heart. Cx43 signal, on the other hand, was reduced by 49% in failing hearts. Double-label experiments demonstrated colocalization of Cx45 and Cx43 in the same gap junctions. CONCLUSION: Cx45 is markedly enhanced in the failing heart. Up-regulation of Cx45 in conjunction with down-regulation of Cx43 could result in abnormal impulse propagation and generation of ventricular arrhythmias, thereby predisposing patients in heart failure to sudden cardiac death.     

Influence of inhaled corticosteroids on community-acquired pneumonia in patients with bronchial asthma

OBJECTIVE: The aim of the present study was to evaluate the influence of inhaled corticosteroids (ICS) on community-acquired pneumonia (CAP) in patients with asthma. PATIENTS AND METHODS: All asthmatic patients who required hospitalization for CAP from the beginning of 1989 through December 2001 were enrolled in this retrospective study. Patients who used oral corticosteroids daily were excluded. Patients were divided into two groups based on whether or not they used ICS, and we analyzed clinical characteristics of the pneumonia. Sixty-two patients (28 males, 34 females; mean age, 54.5 years) were enrolled in this study. Thirty-seven of 62 patients used ICS, with the mean dosage being 777.9 microg/day. RESULTS: We found no significant differences between the two groups with regard to mean age, serum albumin level, duration of asthma, pulmonary function and frequency of intravenous infusion of corticosteroids in the outpatient department. There were no significant differences in body temperature, white blood cell count, and CRP value upon admission between the two groups. Differences were not significant in the period of resolution of the pneumonia or in the frequency of pathogens identified between the two groups. CONCLUSION: ICS therapy appears to have no influence on CAP in patients with asthma. We recommend that ICS should be continued to control asthma with adequate antibiotic therapy when asthmatic patients have CAP.     

Plasmodium falciparum associated placental pathology: a light and electron microscopic and immunohistologic study

Pathological changes were studied by light and electron microscopy on term placentas collected in Malawi from 20 P. falciparum infected women (11 primiparas and 9 multiparas). One placenta from an uninfected term primipara and 4 from multiparas were studied as controls. Changes included the presence of parasitized erythrocytes and malarial pigment particles in the intervillous space, excessive syncytial knotting, chronic basal villitis, malarial pigment deposits in the trophoblasts, trophoblastic damage with focal necrosis, partial loss of microvilli, and thickening of the trophoblastic basement membrane. Infected erythrocytes were not seen in the fetal circulation. Severity appeared to correlate with the level of maternal and placental parasitemias, regardless of infant birth weight or placental weight. Differences in the severity of pathological changes between primiparas and multiparas could not be demonstrated. Immunohistochemistry revealed that 45% of the placentas stained strongly for IgG and 15% stained for C3 and for P. falciparum antigens in the trophoblastic cytoplasm and basement membrane.     

Significance of normal oral flora, particularly group oral streptococci as defense mechanism against infection in healthy individuals (normal defense mechanism by oral Streptococcus group)]

The alpha-streptococci, consisted of normal oral flora mainly, with inhibitory activity against pathogenic microbes in healthy individuals was investigated by group A Streptococcus (indicator strain 6-22 nonmucoid T-12). Rate of alpha-streptococci with inhibitory activity against group A Streptococcus was increased as aging, and the rate in pre-school children was higher than that in school children. These results suggested that more than 90% of the tested alpha-streptococci with strong inhibitory activities (S. salivarius) against indicator strain had inhibitory activities against group A Streptococcus (mucoid T-6), H. influenzae, S. pneumoniae, group C Streptococcus, and from 40% to 70% of the tested strains had also inhibitory activities against other pathogens. As there were many strains of alpha-streptococci with inhibitory activities against pathogens, that usually detected in the upper respiratory infection, the problem on the strains in the future will explain significance of the defense mechanism against upper respiratory infection and this can be applied clinically.