Community-level variation in TB testing history in Blantyre, Malawi.

SETTING: Equitable access to TB testing is vital for achieving global diagnosis and treatment targets, but access to diagnostic services is often worse in poorer communities. The SCALE (Sustainable Community-wide Active case-finding for Lung hEalth) survey estimated TB prevalence in Blantyre City, Malawi, and recorded previous engagement with TB services.OBJECTIVE: To explore local variation in the prevalence of ever-testing for TB in Blantyre and investigate potential socio-economic drivers.DESIGN: We fit a mixed-effects model to self-reported prior TB testing from survey participants across 72 neighbourhood clusters, adjusted for sex, age and HIV status and with cluster-level random intercepts. We then evaluated to what extent cluster-level variation was explained by two alternate poverty indicators.RESULTS: We observed substantial variation between clusters in previous TB testing, with little correlation between neighbouring clusters. Individuals residing in less affluent households, on average, had lower odds of having undergone prior testing. However, adjusting for poverty did not explain the cluster-level variations observed.CONCLUSION: Despite a decade of increased active case-finding efforts, access to TB testing is inconsistent across the population of Blantyre. This likely reflects health inequities that also apply to TB testing in many other settings, and motivates collection and analysis of TB testing data to identify the drivers behind these inequities.

Does tuberculosis screening improve individual outcomes? A systematic review.

BACKGROUND: To determine if tuberculosis (TB) screening improves patient outcomes, we conducted two systematic reviews to investigate the effect of TB screening on diagnosis, treatment outcomes, deaths (clinical review assessing 23 outcome indicators); and patient costs (economic review). METHODS: Pubmed, EMBASE, Scopus and the Cochrane Library were searched between 1/1/1980-13/4/2020 (clinical review) and 1/1/2010-14/8/2020 (economic review). As studies were heterogeneous, data synthesis was narrative. FINDINGS: Clinical review: of 27,270 articles, 18 (n=3 trials) were eligible. Nine involved general populations. Compared to passive case finding (PCF), studies showed lower smear grade (n=2/3) and time to diagnosis (n=2/3); higher pre-treatment losses to follow-up (screened 23% and 29% vs PCF 15% and 14%; n=2/2); and similar treatment success (range 68-81%; n=4) and case fatality (range 3-11%; n=5) in the screened group. Nine reported on risk groups. Compared to PCF, studies showed lower smear positivity among those culture-confirmed (n=3/4) and time to diagnosis (n=2/2); and similar (range 80-90%; n=2/2) treatment success in the screened group. Case fatality was lower in n=2/3 observational studies; both reported on established screening programmes. A neonatal trial and post-hoc analysis of a household contacts trial found screening was associated with lower all-cause mortality. Economic review: From 2841 articles, six observational studies were eligible. Total costs (n=6) and catastrophic cost prevalence (n=4; range screened 9-45% vs PCF 12-61%) was lower among those screened. INTERPRETATION: We found very limited patient outcome data. Collecting and reporting this data must be prioritised to inform policy and practice. FUNDING: WHO and EDCTP.

Estimating the prevalence of coinfection with influenza virus and the atypical bacteria Bordetella pertussis, Chlamydophila pneumoniae, and Mycoplasma pneumoniae.

Coinfections with common bacterial respiratory pathogens and influenza viruses are well-known causes of disease, often via synergistic interactions between the influenza virus, the bacteria, and the human host. However, relatively little is known about interactions between atypical bacteria and influenza viruses. A recent report by Reinton et al. explored this issue by analyzing data from 3,661 patients seeking medical assistance for the presence of Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Bordetella pertussis, as well as influenza A or B virus in nasal swab specimens. The report, however, did not accurately assess the epidemiologic interactions of these pathogens. We aimed to describe the interactions between these bacterial species and influenza infections. Strong and highly statistically significant antagonistic interspecies interactions were detected between C. pneumoniae and influenza virus [odds ratio (OR): 0.09; p < 0.0001) and M. pneumoniae and influenza virus infections (OR: 0.29; p = 0.003). No association was detected between B. pertussis and influenza infection (p = 0.34), contrary to the initial report, and coinfection was not detected at a higher-than-by-chance frequency within the population. Further support of these results is supplied by the analysis of two earlier investigations reporting data on influenza virus and these atypical bacteria. Our results supplement the large body of literature regarding interactions between influenza virus and typical respiratory pathogens, providing a fuller picture of the spectrum of interactions between influenza viruses and respiratory bacteria. Further, we demonstrate the importance of choosing the most appropriate reference populations for the analysis being performed and describe the pitfalls that may occur when care is not taken in this regard.

The tenderisation of shin beef using a citrus juice marinade.

The effectiveness of organic acids (acetic, citric, lactic) and a citrus juice marinade as tenderising agents in shin beef muscle was investigated. At 0.2 M, citric acid was more effective as a tenderising agent than acetic or lactic acid. Immersion of shin beef strips in citric acid (0-0.05 M) showed that a significant tenderising effect was obtained above a concentration of 0.013 M. When shin beef strips were immersed in the citrus juice marinade (31% orange juice, 31% lemon juice, 38% distilled water) mean pH decreased from 5.7 to 3.1 and mean sample weight increased by ∼65%. The mean Warner-Bratzler shear force value decreased from 178 to 44 N cm(-2) following marination while mean sensory analysis scores for tenderness and juiciness increased following marination. A mean total collagen content of 1.4 g/100 g was recorded in shin beef of which 9% was soluble in unmarinated samples and 29% was soluble in marinated samples. The results indicated that the tenderisation of beef samples using a citrus juice marinade could be attributed to marinade uptake by muscle proteins and also to solubilisation of collagen.

Inhibition of toxicity and protofibril formation in the amyloid-beta peptide beta(25-35) using N-methylated derivatives.

Beta (25-35) is a fragment of beta-amyloid that retains its wild-type properties. N-methylated derivatives of beta(25-35) can block hydrogen bonding on the outer edge of the assembling amyloid, so preventing the aggregation and inhibiting the toxicity of the wild-type peptide. The effects are assayed by Congo Red and thioflavin T binding, electron microscopy and an MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] toxicity assay. N-methyl-Gly-25 has similar properties to the wild- type, while five other methylation sites have varying effects on prefolded fibrils and fibril assembly. In particular, N-methyl-Gly-33 is able to completely prevent fibril assembly and reduces the toxicity of prefolded amyloid. With N-methyl-Leu-34 the fibril morphology is altered and toxicity reduced. A preliminary study of beta(25-35) structure in aqueous solution was made by small-angle neutron scattering (SANS). The protofibrillar aggregates are best described as a disc of radius 140 A and height 53 A (1 A = 0.1 nm), though the possibility of polydisperse aggregates cannot be ruled out. No aggregates form in the presence of N-methyl-Gly-33. We suggest that the use of N-methylated derivatives of amyloidogenic peptides and proteins could provide a general solution to the problem of amyloid deposition and toxicity and that SANS is an important technique for the direct observation of protofibril formation and destruction in solution.

Laccases and other polyphenol oxidases in ecto- and ericoid mycorrhizal fungi.

Polyphenol oxidases are known to be produced by a range of ectomycorrhizal (ECM) and ericoid mycorrhizal fungi. These enzymes include laccase (EC 1.10.3.2), catechol oxidase (EC 1.10.3.1) and tyrosinase (EC 1.14.18.1), between which there exists considerable overlap in substrate affinities. In this review we consider the nature and function of these enzymes, along with the difficulties associated with assigning precise enzymatic descriptions. The evidence for production of laccase and other polyphenol oxidases by ECM and ericoid mycorrhizal fungi is critically assessed and their potential significance to the mycorrhizal symbioses discussed.

The number of amino acid residues mismatches correlates with flow cytometry crossmatching results in high PRA renal patients.

Highly sensitized renal transplant candidates present a group at high risk for acute and chronic rejection. The probability of finding compatible donors for these recipients is significantly lower in comparison to those who have low PRA values. As a consequence, these patients spend longer time on the waiting list and become tethered to dialysis. The results of final cross match (XM) are critical for making a decision about whether such a candidate receives an organ or not. The degree of donor and recipient HLA compatibility predicts the results of XM. The goal of this study was to expand a variety of acceptable HLA-AB mismatches (MM) for high PRA kidney recipients using the HLAMATCHMAKER algorithm. This strategy focuses on the fine structural features of HLA polymorphism comprising amino acid residues or triplets (AAT), which are located in alpha-helical coils of HLA molecules and are available to antibodies. We analyzed serum samples from thirty-nine highly alloimmunized recipients (PRA > or = 85%). The level of sensitization was detected using FlowPRA Class I Screening Test. This group of transplant candidates included thirteen recipients who demonstrated negative results of final T/B FCXM and twenty-six, who were FCXM positive. The application of the HLAMATCHMAKER algorithm based on the HLA class I donor and recipient typing allowed us to detect the total number of AATMM as well as the number of immunogenic AAT in both FCXM negative and FCXM positive groups of recipients. Significantly greater numbers of both total and highly immunogenic AATMM have been emerged in the group of FCXM positive patients. Furthermore, the results of this analysis have shown a high degree of probability of positive FCXM if the number of highly immunogenic AATMM was > or = 1 (chi(2) = 22.9 Yate's correction; p = 0.000001). We did not observe overlapping between antibody specificity and permissible HLA-AB MM detected using the HLAMATCHMAKER strategy. Thus, the number of highly immunogenic AATMM can serve as a reliable predictive value for final FCXM results in highly sensitized renal transplant candidates. The HLAMATCHMAKER algorithm appears to be the proper strategy to find donors for high PRA recipients.

Inhibition of toxicity in the beta-amyloid peptide fragment beta -(25-35) using N-methylated derivatives: a general strategy to prevent amyloid formation.

beta-(25-35) is a synthetic derivative of beta-amyloid, the peptide that is believed to cause Alzheimer's disease. As it is highly toxic and forms fibrillar aggregates typical of beta-amyloid, it is suitable as a model for testing inhibitors of aggregation and toxicity. We demonstrate that N-methylated derivatives of beta-(25-35), which in isolation are soluble and non-toxic, can prevent the aggregation and inhibit the resulting toxicity of the wild type peptide. N-Methylation can block hydrogen bonding on the outer edge of the assembling amyloid. The peptides are assayed by Congo red and thioflavin T binding, electron microscopy, and a 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) toxicity assay on PC12 cells. One peptide (Gly(25) N-methylated) has properties similar to the wild type, whereas five have varying effects on prefolded fibrils and fibril assembly. In particular, beta-(25-35) with Gly(33) N-methylated is able to completely prevent fibril assembly and to reduce the toxicity of prefolded amyloid. With Leu(34) N-methylated, the fibril morphology is altered and the toxicity reduced. We suggest that the use of N-methylated derivatives of amyloidogenic peptides and proteins could provide a general solution to the problem of amyloid deposition and toxicity.

The effect of oxygen level and exogenous α-tocopherol on the oxidative stability of minced beef in modified atmosphere packs.

The effect of oxygen level (20, 40, 60 and 80%) in modified atmospheres on the oxymyoglobin content of intact and minced beef (M. semimembranosus, SM) was evaluated. There was no significant difference in the oxymyoglobin content of minced SM stored for up to 4 days in modified atmosphere packs containing 20, 40, 60 or 80% O(2). After 7 days, oxymyoglobin in minced SM decreased significantly (P⩽0.05) with decreasing oxygen level but by day 10 all samples had similarly low oxymyoglobin contents. Lipid oxidation increased significantly (P⩽0.05) between day 7 and 10 of storage in minced SM stored in modified atmospheres containing 40, 60 or 80% O(2). Oxymyoglobin and lipid oxidation occurred in intact SM but the extent of oxidation was lower than for minced SM. Exogenous α-tocopherol, dispersed in olive oil and added to minced SM (300 and 3000 mg α-tocopherol/kg lipid), had no significant effect on Hunter 'a' values when the samples were stored in low (20%) or high (80%) oxygen atmospheres. Exogenous α-tocopherol addition led to a significant reduction in lipid oxidation (P⩽0.05) in minced SM stored in high but not in low oxygen atmospheres.

Characterisation of equine matrix metalloproteinase 2 and 9; and identification of the cellular sources of these enzymes in joints.

The cellular production by resident articular cells and infiltrating inflammatory cells of the gelatinase matrix metalloproteinases (MMP) was investigated by tissue culture methods and analysis of cell supernatants by gelatin zymography. Peripheral blood neutrophils in short term culture produced MMP-9, as did peripheral blood monocytes in culture. Isolated articular chondrocytes in monolayer culture produced both MMP-2 and MMP-9, although articular cartilage maintained as explant culture produced MMP-2 alone. Synovial fibroblasts grown in monolayer culture produced MMP-2 alone, although synovial membrane in explant culture produced both MMP-2 and the active form of MMP-2. Lysis of blood polymorph neutrophils produced large quantities of MMP-9, but lysis of blood monocytes, synovial fibroblasts and articular chondrocytes produced little enzyme indicating that, unlike the other cell types, polymorph neutrophils store MMPs intracellularly. Equine MMP-2 was purified from synovial fibroblast cell culture supernatant, and equine MMP-9 from polymorph neutrophil cell culture supernatant, by gelatin-sepharose affinity chromatography. The 2 enzymes were identified from their molecular weights and by their respective N-terminal amino acid sequences which showed homology with the enzymes from other species. The demonstration that invasive cells and resident articular cells can produce enzymes which are capable of digestion of certain component molecules of the articular cartilage matrix, shows that therapeutic targeting of these enzymes could be a valid proposition in the prevention of cartilage destruction in osteoarthritis.

Physiological heterogeneity within fungal mycelia: an important concept for a functional understanding of the ectomycorrhizal symbiosis.

Individual mycelia of filamentous fungi display considerable heterogeneity at the physiological level. Important physiological processes such as nutrient absorption, extracellular enzyme secretion and solute translocation occur differentially within an individual mycelium, and vary according to spatio-temporal changes in patterns of gene expression as the mycelium develops and senesces. In ectomycorrhizal (ECM) fungi, gene expression appears to be strongly influenced by interaction with the soil environment and the host root. The ECM mycelium is thus a complex and dynamic entity wherein discrete regions display particular physiological attributes. Physiological heterogeneity is important in the overall functioning of the symbiosis. In the particular case of movement of phosphorus from soil to host root in the ECM symbiosis, heterogeneity might provide the driving force for the integrated processes of absorption, translocation and transfer. It is suggested that it is only by considering the sum of the seemingly disparate physiological processes within the heterogeneous mycelium that mycorrhizal functioning can be fully understood.

Reversible late potentials due to ischemia.

The role of ischemia in the development of reversible late potentials was assessed in 19 patients undergoing percutaneous transluminal coronary angioplasty. Signal-averaged electrocardiograms were performed before angioplasty, during ischemia caused by balloon inflation and after angioplasty. Five of 19 patients developed late potentials that reverted to normal after angioplasty. Age, sex, ejection fraction, left ventricular end diastolic pressure, vessels involved, and extent of myocardium in jeopardy did not predict the development of late potentials. Patients with a prior history of myocardial infarction were more likely to develop late potentials. Therefore, patients with prior myocardial infarction appear more likely to develop the substrate for reentrant ventricular tachycardia during periods of ischemia.

Growth of Bacillus stearothermophilus on glycerol in chemostat culture: expression of an unusual phenotype.

Bacillus stearothermophilus grew readily on glycerol in carbon-limited chemostat culture and expressed a high carbon conversion efficiency. However, the strain of organism used (probably B. stearothermophilus var. nondiastaticus) proved particularly sensitive to glycerol, both respiration and growth being severely impeded by any surfeit of this compound. Sensitivity was found to correlate with an exceptionally high level of expression of glycerol kinase [activities of more than 80 mumol min-1 (mg protein)-1 were manifest in crude cell-free extracts], coupled with low activities of methylglyoxal synthase and of glyoxylase (enzymes of the methylglyoxal bypass). It is proposed that metabolic dysfunction results from an uncontrolled gross accumulation of glycerol phosphate (and early products of its metabolism) within the cells, coupled with depletion of the intracellular phosphate pool.

The Ottawa County project: a report of a tuberculosis screening project in a small mining community.

Following a retrospective review of tuberculosis cases reported from Ottawa County, Oklahoma, from 1969 through 1973, a selective tuberculosis screening project was implemented. Screening of a "target group" of the population, 519 former miners, greater than or equal to 50 years of age, resulted in the discovery of abnormal chest X-rays in 182; (103 with silicosis, 36 with silicotuberculosis, 12 with inactive tuberculosis, and 31 with other abnormalities). Eighty-five of these persons had positive tuberculin skin tests. Preventive therapy was recommended for 50, and 36 completed the prescribed course of treatment. Eight new bacteriologically confirmed cases of tuberculosis were found and treated. A large number of persons (1,904) residing in the same area who were not part of the target group were also screened for tuberculosis. This group contained a large number of positive tuberculin reactors but very few were candidates for isoniazid preventive therapy. Thirteen persons in this group had abnormal chest X-rays consistent with inactive tuberculosis but 12 had been identified and given preventive therapy before the project began. These data suggest that selective approaches to screening for tuberculosis in a community which are based on an in-depth retrospective review of the tuberculosis case register can be highly successful.