Detection of Mycobacterium bovis in bovine tissue samples by the Abbott LCx Mycobacterium tuberculosis assay and comparison with culture methods

A ligase chain reaction (LCR) DNA amplification method for the molecular diagnosis of Mycobacterium tuberculosis complex (Abbott LCx MTB) was evaluated in comparison with solid (Lowenstein Jensen), liquid (7H12, Bactec 460 system) phase culture and microscopic examination (ME) on 86 tissue samples collected from 86 intradermal tuberculin positive cattle and one pool from 4 guinea pigs experimentally infected with M. bovis. Overall, 48 samples (58.81%) were culturally positive for mycobacteria, and on the basis of biochemical characters, all the isolates were identified as M. bovis. Sensitivity was 83.92% for LCx, 53.57% for LJ, 85.71% for Bactec and 41.07% for ME. In 3 out of 25 "no visible lesion" tissue samples, M. bovis was detected only by LCx and Bactec but not by LJ and ME. The concordance in the determination of positives and negatives among the methods observed in pairs was calculated according to Cohen's K concordance coefficient and showed 81.1% of concordance of LCx vs Bactec, 68.8% LCx vs LJ, 72.2% LCx vs ME, 80.0% Bactec vs LJ, 66.7% Bactec vs ME, 85.5% LJ vs ME. Despite a certain variability in concordance rates, both Cohen's K concordance coefficients or standardized (Zk) values were statistically significant. Both LCx and Bactec appear not alternative but subsidiary to the other methods traditionally applied for direct diagnosis of bovine tuberculosis on tissue samples from cattle reacting to intradermal tuberculin test.

The impact of the major causes of death on life expectancy in Italy

BACKGROUND

This study aims to evaluate the contribution of the reduction in major cardiovascular diseases (CVD), malignant neoplasms (MN), accidents and AIDS mortality to the gains in life expectancy observed during the decade 1985-1994, as well as to calculate and compare the potential gains due to the partial or total elimination of these causes.

METHODS

Mortality data from the Italian Mortality Data Base were analysed by the method of decomposition of changes in life expectancy and the partial multiple decrement life table technique.

RESULTS

In Italy, considering the decade 1985-1994, the gain in life expectancy at birth was 2.27 years for men and 2.16 for women. The major contribution to this increase was the reduction in CVD mortality followed by fewer deaths from accidents and MN. Conversely, AIDS caused a loss in the length of life of adults. Major potential gains in life expectancy at birth could be obtained by the elimination or even partial reduction of CVD and MN mortality. When working life (15-64 years) is considered, the relative importance of the causes changes. The elimination of accidents and AIDS would result in increased life expectancy longer than that associated with a 50% reduction in CVD.

CONCLUSIONS

The findings of this study provide useful information which could contribute to a more effective allocation of resources for research activity and public health programmes.

Melatonin protects human red blood cells from oxidative hemolysis: new insights into the radical-scavenging activity

Antioxidant activity of melatonin in human erythrocytes, exposed to oxidative stress by cumene hydroperoxide (cumOOH), was investigated. CumOOH at 300 microM progressively oxidized a 1% suspension of red blood cells (RBCs), leading to 100% hemolysis in 180 min. Malondialdehyde and protein carbonyls in the membrane showed a progressive increase, as a result of the oxidative damage to membrane lipids and proteins, reaching peak values after 30 and 40 min, respectively. The membrane antioxidant vitamin E and the cytosolic reduced glutathione (GSH) were totally depleted in 20 min. As a consequence of the irreversible oxidative damage to hemoglobin (Hb), hemin accumulated into the RBC membrane during 40 min. Sodium dodecyl sulfate (SDS) gel electrophoresis of membrane proteins showed a progressive loss of the cytoskeleton proteins and formation of low molecular weight bands and protein aggregates, with an increment of the intensity of the Hb band. Melatonin at 50 microM strongly enhanced the RBC resistance to oxidative lysis, leading to a 100% hemolysis in 330 min. Melatonin had no effect on the membrane lipid peroxidation, nor prevented the consumption of glutathione (GSH) or vitamin E. However, it completely inhibited the formation of membrane protein carbonyls for 20 min and hemin precipitation for 10 min. The electrophoretic pattern provided further evidence that melatonin delayed modifications to the membrane proteins and to Hb. In addition, RBCs incubated for 15 min with 300 microM cumOOH in the presence of 50 microM melatonin were less susceptible, when submitted to osmotic lysis, than cells incubated in its absence. Extraction and high-performance liquid chromatography (HPLC) analysis showed a much more rapid consumption of melatonin during the first 10 min of incubation, then melatonin slowly decreased up to 30 min and remained stable thereafter. Equilibrium partition experiments showed that 15% of the melatonin in the incubation mixture was recovered in the RBC cytosol, and no melatonin was extracted from RBC membrane. However, 35% of the added melatonin was consumed during RBC oxidation. Hydroxyl radical trapping agents, such as dimethylsulfoxide or mannitol, added into the assay in a 1,000 times molar excess, did not vary melatonin consumption, suggesting that hydroxyl radicals were not involved in the indole consumption. Our results indicate that melatonin is actively taken up into erythrocytes under oxidative stress, and is consumed in the defence of the cell, delaying Hb denaturation and release of hemin. RBCs are highly exposed to oxygen and can be a site for radical formation, under pathological conditions, which results in their destruction. A protective role of melatonin should be explored in hemolytic diseases.

Savings obtained using an oxygen economizer device: a cost-minimization analysis

As liquid oxygen represents a relevant burden on healthcare systems, different methods have been developed to reduce oxygen consumption, including economizers. The aims of the study were: 1) to evaluate the efficacy of an economizer device (Companion 5 Oxygen Saver) in a significant sample of patients, and 2) to perform cost-minimization analysis of the possible savings to be obtained using the device. The study was designed as an open, prospective clinical trial in which equivalence in haemoglobin saturation with and without the economizer device was demonstrated, preliminary to cost-minimization analysis in patients affected by restrictive and obstructive lung disease. Patients were to use their usual O2 flow, provided it was able to guarantee a saturation of > or = 90% and an arterial oxygen tension (Pa,O2) of > or = 8.0 kPa (60 mmHg) during rest, sleep and exercise with and without the economizer (mean value and different saturation ranges compared by means of parametric or nonparametric tests where appropriate). The average unit cost was calculated with and without the economizer, based on the average unit O2 consumption, and cost-minimization analysis was performed. In 29 patients enrolled, the mean (+/- SD) O2 flow in L.min-1 was 1.5 +/- 0.6 during sleep, 1.4 +/- 0.6 during rest and 2.3 +/- 1.1 during exercise. The mean oxygen saturation during sleep was 91.2 +/- 19.5% without and 97.2 +/- 3.9% with the economizer device (p = 0.09), the mean saturation during rest was 88.8 +/- 22.7% without and 92.1 +/- 14.9% with the economizer device (p = 0.42), and the mean saturation during exercise was 84.7 +/- 19.3% without and 91.8 +/- 15.9% with the economizer device (p = 0.04). The total daily O2 consumption was significantly lower using the economizer device (2,384 +/- 950.3 versus 93.0 +/- 482.9 L, p < 0.001). The potential savings, estimated per patient per year, were 530,114 +/- 184,233 L, corresponding to US$2,492 +/- 866. During the first year the total unit savings would be US$1,892. The savings, consistently relevant alongside the whole range of variation explored by sensitivity analysis both during the first and the following years, justify considering the adoption of similar economizers on a larger scale, although further studies should be performed to evaluate whether or not liquid oxygen really represents the most cost-effective method of treating hypoxaemic patients.

The use of magnetic resonance imaging in posterior tibial tendon dysfunction

The role of magnetic resonance imaging in the evaluation of the patient with posterior tibial tendon dysfunction is discussed. Considerations for the proper positioning of the patient and optimal technique to obtain appropriate images of the posterior tibial tendon and associated joint abnormalities are highlighted. Cases are presented to show the effectiveness of magnetic resonance imaging in different clinical situations. The treatment algorithm for posterior tibial tendon dysfunction should include magnetic resonance imaging as a diagnostic tool when appropriate.

Pharmacokinetics of dirithromycin in patients with mild or moderate cirrhosis

The pharmacokinetics of dirithromycin were determined over a 72-h period following oral administration of a single 500-mg dose to 8 healthy volunteers and to 16 cirrhotic patients (8 patients with class A cirrhosis and 8 patients with class B cirrhosis according to Pugh's & Child's classification). Drug levels in plasma and urine were determined by microbiological assay. The mean maximum concentrations of drug in serum obtained 3 to 4 h after administration were 0.29 +/- 0.22 mg/liter in volunteers and 0.48 +/- 0.21 and 0.52 +/- 0.38 mg/liter in patients with class A and class B cirrhosis, respectively. The elimination half-life (t1/2beta) was 23.3 +/- 7.6 h in healthy subjects and 35.2 +/- 11.8 h and 39.5 +/- 11.0 h in patients with class A and class B cirrhosis, respectively. The mean area under the concentration-time curve (AUC) and t1/2beta were significantly higher in patients with class A and B cirrhosis than in healthy controls, while total and renal clearances were markedly reduced (P < 0.01). The time to the maximum concentration of drug in serum and the volume of distribution values appeared to be similar in all groups, and the mean recovery in urine at 72 h ranged from 3.7 to 5.7%, without significant differences among groups. These results demonstrate that some dirithromycin kinetic parameters are significantly different in cirrhotic patients in comparison to those in healthy volunteers. However, an increase in the t1/2beta or AUC, which is also observed with other semisynthetic macrolides (e.g., azithromycin), does seem to be not clinically relevant if one takes into account both the high therapeutic indices of these antibiotics and the usually short duration of therapy. Therefore, on the limited basis of single-dose administration, no modifications of dirithromycin dosage seem to be required even for patients with class B liver cirrhosis.

Stress proteins in fungal diseases

Heat shock proteins (hsps) are ubiquitous families of proteins, found in all organisms studied so far. They are highly conserved across the species barrier and serve fundamental functions in cell physiology. The term 'heat shock' was adopted because of the early observation of the heat-inducible nature of these proteins, although, as it is now realized that they can be induced by a variety of stressful stimuli, it is probably more appropriate to call them 'stress proteins'. The nomenclature of many hsps, for example hsp90, hsp70 and hsp60, reflects the approximate molecular mass of hsps within each of these families. For many bacterial and parasitic infections, hsps were first recognized as immunodominant antigens on immunoblots of extracts from the organism probed with immune sera, or in T-cell proliferation assays. They have now been identified in a range of fungal pathogens, again often linked to an immune response. In this symposium, we review the association of hsps with humoral immunity to candidosis and aspergillosis, cellular immunity to histoplasmosis, and the identification of hsp70 in another dimorphic fungus, Paracoccidioides brasiliensis. Finally, the crucial role of the membrane in setting the temperature of the heat shock response in yeasts is discussed.

Factors influencing the expression in vitro of Candida albicans stress mannoproteins reactive with salivary secretory IgA

We have examined the influence of subinhibitory concentrations of several antifungals, the different glucose and ammonium sulphate concentrations in the culture medium as well as the strain variability on the expression in vitro of stress mannoproteins reactive with salivary sIgA in C. albicans and other Candida spp isolates. Irrespective of the conditions used, no reactivity with salivary sIgA was observed in yeast cells grown at 25 degrees C. However, when grown at 37 degrees C, all of the 10 C. albicans strains, but only 9 out of 28 non-C. albicans isolates studied showed reactivity with salivary sIgA. Cells grown at 37 degrees C in medium containing maximum concentrations of glucose and ammonium sulphate expressed the antigens reactive with sIgA during longer periods of time than the cells grown in medium with minimal concentrations of the same compounds. The regulatory role showed by the concentration of glucose and ammonium sulphate on the antigenic expression was subordinated, nevertheless, to the most important factor, the temperature of incubation. Only isolates showing low susceptibility expressed the antigens reactive with sIgA under the influence of subinhibitory concentration of antifungals. However, induced resistance to one of the antifungals tested (5 fluorocytosine) allowed the antigenic expression at elevated subinhibitory concentrations even in previous susceptible strains. In conclusion, in addition to the temperature, factors such as characteristics of the strain, the concentration of glucose and ammonium sulphate in the culture medium and the resistance to antifungals played a role on the expression of C. albicans antigens reactive with sIgA, which could be of clinical relevance in the course of infection.

A transphyletic anti-infectious control strategy based on the killer phenomenon

A strategy for the prevention and control of candidiasis, pneumocystosis, and tuberculosis, based on the idiotypic network of the yeast killer effect has been envisaged. Anti-idiotypic antibodies representing the internal image of a candidacidal, pneumocysticidal, and mycobactericidal killer toxin from Pichia anomala and idiotypes of killer toxin-neutralizing monoclonal antibodies mimicking the specific cell wall receptor of sensitive microorganisms might provide a unique approach for engineering innovative antibiotics and vaccines active against taxonomically unrelated pathogenic microorganisms. The rationale of the strategy relies on a phenomenon of microbial competition which has been mutated by the immune system in the response to natural infections.

Prevention of recurrent depression with cognitive behavioral therapy: preliminary findings

BACKGROUND

Cognitive behavioral treatment (CBT) of residual symptoms after successful pharmacotherapy yielded a substantially lower relapse rate than did clinical management in patients with primary major depressive disorders. The aim of this study was to test the effectiveness of this approach in patients with recurrent depression (> or = 3 episodes of depression).

METHODS

Forty patients with recurrent major depression who had been successfully treated with antidepressant drugs were randomly assigned to either CBT of residual symptoms (supplemented by lifestyle modification and well-being therapy) or clinical management. In both groups, during the 20-week experiment, antidepressant drug administration was tapered and discontinued. Residual symptoms were measured with a modified version of the Paykel Clinical Interview for Depression. Two-year follow-up was undertaken, during which no antidepressant drugs were used unless a relapse ensued.

RESULTS

The CBT group had a significantly lower level of residual symptoms after discontinuation of drug therapy compared with the clinical management group. At 2-year follow-up, CBT also resulted in a lower relapse rate (25%) than did clinical management (80%). This difference attained statistical significance by survival analysis.

CONCLUSIONS

These results challenge the assumption that long-term drug treatment is the only tool to prevent relapse in patients with recurrent depression. Although maintenance pharmacotherapy seems to be necessary in some patients, CBT offers a viable alternative for other patients. Amelioration of residual symptoms may reduce the risk of relapse in depressed patients by affecting the progression of residual symptoms to prodromes of relapse.

Effect of Pichia anomala killer toxin on Candida albicans

The effect of a Pichia anomala killer toxin upon a Candida albicans-sensitive strain was studied. Yeast and hyphae, after treatment with the toxin, were less capable of uptaking either [3H]-uridine or [35S]-methionine. In addition, the hyphal form of the fungus appeared to be less capable of DNA synthesis after toxin treatment. No effect of the killer toxin was shown upon a natural resistant mutant of the source strain. These data suggest that, similar to other killer yeast toxins, the toxin of P. anomala can produce a number of quantifiable effects upon sensitive C. albicans cells.

Neonatal mouse immunity against group B streptococcal infection by maternal vaccination with recombinant anti-idiotypes

We investigated whether immunization with recombinant anti-idiotypic antibody fragments mimicking the conformation of the capsular antigen can protect against infection by group B streptococcus, an important neonatal pathogen. Single-chain fragment-variable anti-idiotypes competed with the type III carbohydrate for binding to type-specific antibodies and elicited, in mice, the production of protective immunoglobulins reacting against the type III polysaccharide. Moreover, maternal immunization with soluble or phage-displayed fragments protected neonatal mice against streptococcal infection. These data indicate that recombinant anti-idiotypic antibodies may be useful in developing protein images of relevant carbohydrate epitopes and, ultimately, in preventing infections by encapsulated bacteria.

Evaluation of the Abbott LCx Mycobacterium tuberculosis assay in comparison with culture methods in selected Italian patients

A ligase chain reaction (LCR) DNA amplification method for the molecular diagnosis of Mycobacterium tuberculosis (Abbott LCx MTB) was evaluated in comparison with solid and liquid phase culture on 622 selected samples collected in two large Italian hospitals, of which 310 obtained from HIV-1 positive patients and 312 from HIV-negative individuals. The overall prevalence of mycobacteria by culture was 22% (137/622), and the apparent sensitivity and specificity of LCx vs. culture were 87.6% and 98.2%. Of the 26 culture positive/LCx negative samples, 22 were positive for MOTT and 4 for M. tuberculosis. All 9 samples positive by LCx and negative by culture were classified as true positive by clinical criteria. The final values of sensitivity, specificity, positive predictive value and negative predictive value for LCx rose to 96.8%, 100%, 100% and 99.2%, respectively. The adjusted sensitivity of culture methods was 89.5% for solid phase and 92.7% for Bactec. In view of the high sensitivity on both smear-positive (100%) and smear-negative (92.4%) samples and of the high negative predictive value, the LCR-based amplification method appears suitable as a routine screening method for the rapid diagnosis of M. tuberculosis in high-risk patients.

Well-being therapy. A novel psychotherapeutic approach for residual symptoms of affective disorders

BACKGROUND

There is increasing awareness of the prognostic value of residual symptomatology in affective disorders and of the need for specific therapeutic strategies in this phase of illness. The aims of the study were to apply a novel, short-term psychotherapeutic approach for increasing well-being, based on Ryff's conceptual model, to remitted patients with affective disorders and to compare the results with those obtained with symptom-oriented cognitive behavioural strategies.

METHODS

Twenty patients with affective disorders (major depression, panic disorder with agoraphobia, social phobia, generalized anxiety disorder, obsessive-compulsive disorder) who had been successfully treated by behavioural or pharmacological methods were randomly assigned to a well-being enhancing therapeutic strategy (well-being therapy) or cognitive-behavioural treatment of residual symptoms.

RESULTS

Both well-being and cognitive-behavioural therapies were associated with a significant reduction of residual symptoms. However, a significant advantage of well-being therapy over cognitive-behavioural strategies was observed with observer-rated methods.

DISCUSSION

These preliminary results suggest the feasibility of well-being therapy in the residual stage of affective disorders. Further research should determine its value as a relapse-preventive strategy in specific mood and anxiety disorders.

Mycobactericidal activity of human natural, monoclonal, and recombinant yeast killer toxin-like antibodies

Human natural (KTAb), murine monoclonal (KTMAb), and single-chain recombinant (KTScFv) candidacidal antibodies representing the internal image of a killer toxin from the yeast Pichia anomala (KT), characterized by a wide spectrum of antibiotic activity, exerted a lethal effect against a KT-sensitive multidrug-resistant isolate of Mycobacterium tuberculosis. KTMAb and KTScFv were produced by the hybridoma and DNA technologies, respectively, from the spleen lymphocytes of animals immunized with the idiotype of a KT-neutralizing MAb (MAb KT4), while KTAb were purified against MAb KT4 from the vaginal fluid of women infected with Candida albicans cells bearing an idiotype-like KT cell wall receptor. Mycobactericidal activity was related to the binding of KTAb, KTMAb, and KTScFv to the cell surface of KT-sensitive bacterial cells and was prevented by specific absorption of KT-like antibodies onto MAb KT4. These data identify a novel potentially useful immunotherapeutic approach to tuberculosis.

Hepatitis C virus infection in households of anti-HCV chronic carriers in Italy: a multicentre case-control study

To test the hypothesis that households of anti-HCV positive subjects might be at increased risk of HCV infection, a case-control study was carried out comparing 518 family members of 205 anti-HCV positive subjects (index carriers) with 281 family members of 100 anti-HCV negative subjects (index controls), consecutively observed in ten gastroenterology units in different Italian regions. The index carriers were age and sex matched to the index controls and their households were similar with respect to the main sociodemographic characteristics. Anti-HCV antibodies were found in 6.9% (36/518) of household members of index carriers and in 3.2% (9/281) of household members of index controls (p < 0.05). The results of multiple logistic regression analysis showed that being over 50 years of age was the sole independent predictor for a household contact of the likelihood of being anti-HCV positive (O.R. 3.6; C.I. 95% = 1.5-8.2). Being in the household of an anti-HCV index carrier was marginally associated to anti-HCV positivity (O.R. 2.0; C.I. 95% = 0.9-4.6). No association was found for sex, area of residence, family size, lowest level of schooling, or any type of family relationship. These findings are not in compliance with the statement that household contacts of HCV carriers are at increased risk of HCV infection. The 3.2% anti-HCV prevalence rate observed among household contacts of anti-HCV negative index controls may suggest that the true anti-HCV prevalence in the general population in Italy is nearly 2.5 times as high as the 1.3% found in Italian blood donors.

Inhibitory effect of human natural yeast killer toxin-like candidacidal antibodies on Pneumocystis carinii

BACKGROUND

Human natural antibodies have been found that owe their candidacidal action to the mimicry of a yeast killer toxin produced by the yeast Pichia anomala (PaKT). Candidacidal human natural antibodies (KTAb) are elicited by and bind to a KT receptor (PaKTR) present on the cell surface of infectious PaKT-sensitive microorganisms. Because of the recognized susceptibility of Pneumocystis carinii organisms to PaKT upon the occurrence of specific PaKTR, we examined whether human natural KTAb could also bind to and inhibit P. carinii.

MATERIALS AND METHODS

Immunoaffinity-purified KTAb from the vaginal fluid of patients affected by candidiasis were tested and compared with PaKT for their ability to inhibit rat-derived P. carinii attachment to epithelial lung cells as well as infectivity to nude rats. Immunofluorescence studies were also performed by biotinylated PaKT in competition with human KTAb to establish their specific binding to PaKTR on the surface of rat-derived and human P. carinii organisms.

RESULTS

Human natural candidacidal KTAb exerted a strong, specific inhibitory activity against rat-derived P. carinii organisms that are susceptible to PaKT itself. The antimicrobial activity of human KTAb was abolished by adsorption with a specific PaKT-neutralizing mAb KT4. Immunofluorescence studies of competition with PaKT showed that human KTAb efficiently bind to the specific PaKTR on the surface of rat-derived and human P. carinii organisms.

CONCLUSIONS

The results strongly suggest that human KTAb, elicited by a common transphyletic receptor of different pathogenic microorganisms during infection, may play a role in antibody-mediated cross-immunity and, if properly engineered, as functionally equivalent recombinant antibodies they could exert a therapeutic activity against pneumocystosis in vivo.

Premature mortality in Italy during the first decade of the AIDS epidemic: 1984-1993

BACKGROUND

AIDS has become a leading cause of premature mortality in many countries, owing to the decline in other major causes of premature death and the increase in AIDS itself. This study was carried out to determine the trends in premature mortality due to selected causes in Italy.

METHODS

Data from the Italian Mortality Data Base, for the ten years from 1984 to 1993 (the first decade of the AIDS epidemic) were analysed. Premature mortality was measured in terms of years of potential life lost before the age of 70 years (YPLL), excluding infant mortality. Trends in premature mortality due to AIDS were compared with those of the principal causes of premature death: lung cancer, colon-rectum cancer, stomach cancer, leukaemia, female breast cancer, uterine cancer, myocardial infarction, stroke, liver diseases, suicide, road accidents and overdose.

RESULTS

In this period there has been a marked increase in premature mortality from AIDS both among males aged 1-69 years (from a rate of YPLL of 0.01 per 1000 in 1984 to 3.71 in 1993) and females of the same age group (from 0 deaths in 1984 to a rate of YPLL of 1.02). Throughout the same period all the other causes of premature death have been declining, with the exception of suicide and overdose among males, and overdose and lung cancer among females. For people aged 25-44 years, AIDS has become the greatest cause of premature death. The increasing trend in premature mortality due to AIDS is most pronounced in the northern and central areas of Italy.

CONCLUSIONS

AIDS is the leading cause of death among males aged 25-44 years in Italy and is having an important impact on premature mortality among females in the same age group.

Yeast killer systems

The killer phenomenon in yeasts has been revealed to be a multicentric model for molecular biologists, virologists, phytopathologists, epidemiologists, industrial and medical microbiologists, mycologists, and pharmacologists. The surprisingly widespread occurrence of the killer phenomenon among taxonomically unrelated microorganisms, including prokaryotic and eukaryotic pathogens, has engendered a new interest in its biological significance as well as its theoretical and practical applications. The search for therapeutic opportunities by using yeast killer systems has conceptually opened new avenues for the prevention and control of life-threatening fungal diseases through the idiotypic network that is apparently exploited by the immune system in the course of natural infections. In this review, the biology, ecology, epidemiology, therapeutics, serology, and idiotypy of yeast killer systems are discussed.