Ventilatory control studied with circulatory occlusion during exercise recovery

Summary Mechanisms involved in the control of pulmonary ventilation were studied in seven male subjects following 6 min of exercise on a cycle ergometer at 98w. Circulation to the legs was occluded by thigh cuffs (27 kPa) during the last 15 s of exercise and the subsequent 4 min of recovery. Respiratory gas exchange and the tidal partial pressures of O₂ and CO₂ were measured breathby-breath. The results were compared to control studies without occlusion. There was a significant increase in both systolic and diastolic blood pressures during occluded recovery. Following occlusion systolic pressure remained elevated while diastolic pressure returned to control values. Occlusion during recovery caused hyperventilation during the first 1.5 min after exercise as evidenced by significantly higher , P_ETO₂, and lower P_ETCO₂. Following the release of the cuffs P_ETCO₂, , and heart rate all increased significantly above control values, while P_ETO₂ decreased. P_ETCO₂ rose abruptly 14.5±0.9 s after the release of the cuffs. Marked increases inV _E and heart rate were seen, and occurred 30.8±1.5 s and 12.8±1.3 s, respectively, after cuff release. The 16.3±1.4 s lag between the increase in P_ETCO₂ and after occlusion suggests that the ventilatory response to a sudden load of hypercapnic blood is not mediated by a pulmonary chemoreceptor. Other receptors, probably the peripheral chemoreceptors, appear to be responsible for hypercapnic hyperventilation.     

Cytokine production pathway in the elderly

It is well known that aging is associated with various alterations in lymphoid cell functions, particularly with a progressive decline in immune responsiveness to exogenous antigens and increasing incidence of autoimmune phenomena. Many studies have been focused on the mechanisms of the immunologic features of aging. This review describes our results of studies performed to determine the influence of age on the capacity to produce interleukin-2 (IL-2), interferon-γ (IFN-γ), interleukin-4 (IL-4), interleukin-5 (IL-5), interleukin-6 (IL-6) and tumor necrosis factor (TNF). Mitogen-stimulated cultures of mononuclear cells (MNC) from human beings were assessed for cytokine-producing capacity. A significant decrease in IFN-γ and IL-2 production by MNC cultures from elderly individuals was observed. No significant difference was instead observed between cultures from elderly individuals and those from young ones as regards TNF-α, IL-4 and IL-6 production. Mitogen or antigen-stimulated cultures of MNC from aged mice also displayed a significant decrease in IFN-γ and IL-2 production as well as TNF-β. Instead IL-4 and IL-5 production significantly increased in these cultures. We suggest that this imbalanced cytokine production may well account for the pattern of immune response which may be observed in the elderly, i.e. a normal or increased humoral response (including autoimmune responses) in face of a low T cell immune responsiveness.     

Decision support in psychiatry – a comparison between the diagnostic outcomes using a computerized decision support system versus manual diagnosis

Background  

Correct diagnosis in psychiatry may be improved by novel diagnostic procedures. Computerized Decision Support Systems (CDSS) are suggested to be able to improve diagnostic procedures, but some studies indicate possible problems. Therefore, it could be important to investigate CDSS systems with regard to their feasibility to improve diagnostic procedures as well as to save time.     

Serum neopterin for early assessment of severity of severe acute respiratory syndrome

Neopterin and C-reactive protein (CRP) concentrations were determined in serum samples from 129 severe acute respiratory syndrome (SARS) patients and 156 healthy blood donors. In the patients with confirmed SARS, an early neopterin elevation was detected already at the day of onset of symptoms and rose to a maximum level of 45.0 nmol/L 3 days after the onset. All SARS patients had elevated neopterin concentrations (>10 nmol/L) within 9 days after the onset. The mean neopterin concentrations were 34.2 nmol/L in acute sera of SARS patients, 5.1 nmol/L in convalescent sera, and 6.7 nmol/L in healthy controls. In contrast, the mean CRP concentrations in both acute and convalescent sera of SARS patients were in the normal range (<10 mg/L). Serum neopterin level in SARS patients was associated with fever period and thus the clinical progression of the disease, while there was no significant correlation between the CRP level and the fever period. Serum neopterin may allow early assessment of the severity of SARS. The decrease of neopterin level was found after steroid treatment, which indicates that blood samples should be collected before steroid treatment for the neopterin measurement.     

Relationship between MUC5AC and altered expression of MLH1 protein in mucinous and non-mucinous colorectal carcinomas

The main purpose of this study was to examine the expression of mucins and mismatch repair proteins in colorectal carcinomas. The immunohistochemical distribution of apomucins MUC2, MUC5AC, and the expression of MLH1 and MSH2 proteins were examined in 76 mucinous and 60 non-mucinous colorectal carcinomas. MUC2 was noted in all mucinous carcinomas, whereas MUC5AC was present in 41 cases only (54%). In non-mucinous carcinomas, MUC2 was expressed in 61.7% of the tumors; by contrast, MUC5AC was present in 20% of the cases. The expression level of apomucins was significantly different in mucinous and non-mucinous lesions (p<0.001). Twenty-seven (35.5%) of the mucinous carcinomas showed no MLH1 expression, whereas 11 (18.3%) of the non-mucinous tumors did. This difference was statistically significant (p<0.005). Altered expression of MSH2 protein was never observed. The lack of MLH1 expression was considerably more frequent in carcinomas with secretion of MUC5AC (p<0.005). Our study has demonstrated this close relationship by immunohistochemical methods. In summary, our data show: (1) differences in the expression of mucins between mucinous and non-mucinous tumors; (2) a high frequency of altered MLH1 protein expression (35.5%) in mucinous carcinomas; (3) a significant relationship between the presence of MUC5AC and the altered expression of MLH1 protein in colorectal carcinomas.     

Efficacy of human recombinant erythropoietin plus IFN-alpha in patients affected by chronic hepatitis C.

Determination of serum iron levels in patients affected by chronic hepatitis C is considered fundamental for studying the response to interferon-alpha (IFN-alpha) treatment. IFN could induce anemia, which is promptly corrected by exogenous administration of recombinant human erythropoietin (rHuEPO). The aim of our study was to verify the possible beneficial effect of rHuEPO in patients affected by chronic hepatitis C and treated with IFN. Seventy consecutive patients (42 males and 28 females, mean age 46.4+/-5.2 years) affected by chronic hepatitis C were enrolled. In all patients, chronic hepatitis C was diagnosed on the basis of clinical and biological findings (alanine aminotransferase [ALT] serum levels at least 2-fold higher than normal values for at least 12 months and the presence of anti-HCV antibodies). All patients were negative for hepatitis B virus (HBV) infection, hepatitis D virus (HDV infection, and HIV infection. Statistical analysis was carried out using the Wilcoxon nonparametric sum rank test, the Spearman correlation rank test, and the Friedman ANOVA and Kendall coefficient of concordance. At the end of the treatment, our study series showed significant differences in serum levels of AST (p < 0.001), iron (p < 0.001), and ferritin (p < 0.001). At the end of the follow-up period, significant differences were seen in ALT, aspartate (AST), and iron ferritin and transferrin levels. All differences favored patients who received IFN-alpha and rHuEPO. We think that the depletion of circulating iron may improve the immune response impaired by iron accumulation in the liver. Our study confirms the important role played by iron in the response to IFN treatment, suggesting that the use of rHuEPO induces a better response to IFN in patients with chronic hepatitis C by activation of erythropoiesis.     

Identifying recent HIV infections using the avidity index and an automated enzyme immunoassay

We evaluated a procedure for identifying recent HIV infections, using sequential serum samples from 47 HIV-positive persons for whom the seroconversion date could be accurately estimated. Each serum sample was divided into two aliquots: one diluted with phosphate-buffered saline and the other diluted with 1 M guanidine. We assayed the aliquots with the automated AxSYM HIV1/2gO test (Abbott Diagnostics Division), without modifying the manufacturer's protocol. We then calculated the avidity index (AI): the ratio of the sample/cutoff value for the guanidine aliquot to that of the phosphate-buffered saline aliquot. We analyzed 216 serum samples: 34 samples were collected within 6 months of seroconversion (recent seroconversions), and 182 were collected after 6 months. The mean AIs, by time from seroconversion, were 0.68 +/- 0.16 (within 6 months) and 0.98 +/- 0.10 (after 6 months) (P < 0.0001). AI of <0.90 correctly identified 88.2% of recent infections but misclassified as recent infections 13.2% of serum samples collected afterward. The probability of an infection being classified as recent and having AI of > or = 0.90 would be 0.7% in a population with 5% recent infections. AI can identify with a certain degree of accuracy recent HIV infections, and being a quantitative index, it provides different levels of sensitivity and specificity, depending on the selected cutoff value. The standard assay procedure is not modified. This test is simple and inexpensive and could be used for surveillance, decision-making in treatment, and prevention.