Linking soils and human health: geospatial analysis of ground-sampled soil data in relation to community-level podoconiosis data in North West Cameroon.

BACKGROUND: Podoconiosis is a form of leg swelling, which arises when individuals are exposed over time to red clay soil formed from alkaline volcanic rock. The exact causal agent of the disease is unknown. This study investigates associations between podoconiosis disease data and ground-sampled soil data from North West Cameroon. METHODS: The mineralogy and elemental concentrations were measured in the soil samples and the data were spatially interpolated. Mean soil values were calculated from a 3 km buffer region around the prevalence data points to perform statistical analysis. Analysis included Spearman's rho correlation, binary logistic regression and principal component analysis (PCA). RESULTS: Six elements, barium, beryllium, potassium, rubidium, strontium and thallium, as well as two minerals, potassium feldspar and quartz, were identified as statistically related to podoconiosis. PCA did not show distinct separation between the spatial locations with or without recorded cases of podoconiosis, indicating that other factors such as shoe-wearing behaviour and genetics may significantly influence podoconiosis occurrence and prevalence in North West Cameroon. CONCLUSION: Several soil variables were statistically significantly related to podoconiosis. To further the current study, future investigations will look at the inflammatory pathway response of cells after exposure to these variables.

Association between infection with Helicobacter pylori and atopy in young Ethiopian children: A longitudinal study.

BACKGROUND: Epidemiological evidence from developed countries indicates that Helicobacter pylori infection correlates with a reduced risk of atopy and allergic disorders; however, limited data are available from low-income countries. OBJECTIVE: We examined associations between H. pylori infection in early childhood and atopy and reported allergic disorders at the age of 6.5 years in an Ethiopian birth cohort. METHODS: A total of 856 children (85.1% of the 1006 original singletons in a population-based birth cohort) were followed up at age six and half years. An interviewer-led questionnaire administered to mothers provided information on demographic and lifestyle variables. Questions on allergic disease symptoms were based on the International Study of Asthma and Allergies in Children (ISAAC) core allergy and environmental questionnaire. Serum samples were analysed for total IgE levels and anti-H. pylori cytotoxin-associated gene A (CagA) IgG antibody using commercially available ELISA kits. Stool samples were analysed for H. pylori antigen using a rapid immunochromatographic test. The independent effects of H. pylori infection (measured at age of 3, 5 and 6.5 years) on prevalence and incidence of atopy and reported allergic disorders (measured at age of 6.5 years) were determined using multiple logistic regression. RESULTS: In cross-sectional analysis, current H. pylori infection at age 6.5 years was inversely, though not significantly, related to prevalence of atopy and "any allergic condition" at age 6.5 years. However, detection of H. pylori infection at any point up to age 6.5 years was associated with a significantly reduced odds of both atopy and "any allergic condition" (adjusted OR AOR, 95% CI, 0.54; 0.32-0.92, P = .02, and .31; 0.10-0.94, P = .04, respectively). In longitudinal analyses, H. pylori infection at age 3 was inversely associated with incidence of atopy (AOR, 95% CI, 0.49; 0.27-0.89, P = .02). Furthermore, among H. pylori-infected children, those with a CagA+ strain had a more pronounced reduction in odds of atopy (AOR = 0.35 vs 0.63 for CagA+ vs CagA-), and this reduction reached borderline significance. CONCLUSION: These data are consistent with the hypothesis that early exposure to H. pylori is inversely associated with atopy and allergic conditions. A possible modest protective association against atopy was observed in those infected with a more virulent CagA+ strain of H. pylori.

Polymorphisms in the regulatory region of the porcine MYLPF gene are related to meat quality traits in the Large White breed.

The MYLPF gene encodes fast myosin regulatory light chain, and is a positional and functional candidate gene for meat quality. The aim of this study was to identify associations between SNPs in the promoter region of the porcine MYLPF gene and meat quality traits. A total of 22 SNPs were identified in a population of crossbred animals (n=86) and based on minor allele frequency and proximity to the transcription start site, five SNPs were genotyped in purebred; Large White (n=98), Duroc (n=99) and Pietrain (n=98) pigs. No associations were observed in the Pietrain breed, while the Duroc breed was almost monomorphic for all SNPs. In the Large White breed SNP g-1314A>G and linked SNPS g.-871T>G, g.-566T>C, g.-403C>G were associated with ultimate pH and driploss (P<0.05). This study identified associations between MYLPF and meat quality and highlights the importance of considering the genetic background within gene-assisted selection programmes.

Is Helicobacter Pylori infection inversely associated with atopy? A systematic review and meta-analysis.

BACKGROUND: The role Helicobacter Pylori (H. pylori) infection plays in the aetiology of atopy remains unclear, although a possible protective role has been hypothesized. OBJECTIVE: The aim of this study was to undertake a systematic review and meta-analysis of epidemiological studies to quantify the association between H. pylori infection and atopy. METHODS: A comprehensive literature search in MEDLINE/PUBMED and EMBASE (up to August 2013) was carried out to identify all observational epidemiological studies (cross-sectional, cohort and case-control) published in English that evaluated the association between H. pylori infection and objectively measured atopy (measured by allergen skin tests or specific IgE). The quality of included studies was assessed by the Newcastle-Ottawa scale. Random-effects meta-analyses were performed to obtain pooled estimates of effect. RESULTS: Twenty-two observational studies involving 21 348 participants were identified as eligible for inclusion in the review, of which 16 were included in the meta-analysis. H. pylori infection was associated with a significantly reduced odds of atopy (pooled odds ratio (OR) 0.82; 95% confidence interval (CI) 0.73 - 0.91; P < 0.01). Subgroup analysis according to atopy definition revealed a slightly greater protective effect for atopy defined as raised allergen-specific IgE (OR 0.75; 95% CI 0.62 - 0.92; P < 0.01; seven studies). Findings did not differ according to the population age (adult or children), methodological quality or study design. CONCLUSION AND CLINICAL RELEVANCE: Evidence from epidemiological studies suggests that H. pylori infection is associated with an estimated 18% reduction in odds of atopy. If the observed association is causal, more insights into the underlying mechanisms could provide clues to possible therapeutic opportunities in allergic disease.

Novel variation in the FABP3 promoter and its association with fatness traits in pigs.

This study examines associations between SNPs in the promoter region of the fatty acid binding protein 3 (FABP3) gene and fatness traits in pure bred Large White (n=98), Duroc (n=99) and Pietrain (n=98) populations. In the Large White breed, SNP g.-634 C>A was associated a 27% increase in IMF (%) in the heterozygote (CA) and a 38% increase in the homozygote (CC) relative to the (AA) genotype in the M. semimembranosus (SM) muscle (P=0.02). While the associations observed in this breed were suggestive of significance in both the SM and in the M. longissimus thoracis et lumborum (LTL) (P=0.08), these associations no longer attained significance at thresholds adjusted for multiple testing. In conclusion, SNPs in the FABP3 promoter may contribute to IMF without influencing carcass fatness traits in pigs, however further confirmation of these associations in larger independent populations would be essential before their incorporation into breeding programmes.

Exposure to Helicobacter pylori infection in early childhood and the risk of allergic disease and atopic sensitization: a longitudinal birth cohort study.

BACKGROUND: An inverse relation between Helicobacter pylori infection and allergic disease has been reported by a range of independent epidemiological studies, but evidence from longitudinal studies is scarce. OBJECTIVE: We have investigated the effects of H. pylori infection on the incidence and prevalence of allergic diseases and sensitization in a low-income birth cohort. METHODS: In 2005/2006, a population-based birth cohort was established in Butajira, Ethiopia, and the 1006 singleton babies born were followed up at ages 1, 3, and 5. Symptoms of allergic disease were collected using the ISAAC questionnaire, allergen skin tests performed, and stool samples analysed for H. pylori antigen and geohelminths. Multiple logistic regression was used to determine the independent effects of H. pylori measured at age 3 on the incidence of each outcome between ages 3 and 5 years (in those without the outcome at age 3), controlling for potential confounders, and to additionally assess cross-sectional associations. RESULTS: A total of 863 children were followed up to age 5. H. pylori infection was found in 25% of the children at both ages 3 and 5, in 21% at age 5 but not 3, and in 17% at age 3 but not at age 5. H. pylori infection at age 3 was significantly associated with a decreased risk of incident eczema between ages 3 and 5 (adjusted OR, 95% CI, 0.31; 0.10-0.94, P = 0.02). Cross-sectionally at age 5, H. pylori infection was inversely associated with skin sensitization (adjusted OR, 95% CI, 0.26; 0.07-0.92, P = 0.02). CONCLUSION AND CLINICAL RELEVANCE: These findings provide further evidence to suggest that early-life exposure to H. pylori may play a protective role in the development of allergy.

Feasibility of rapid ethical assessment for the Ethiopian health research ethics review system

One of the challenges in the process of ethical medical research in developing countries; including Ethiopia; is translating universal principles of medical ethics into appropriate informed consent documents and their implementation. Rapid Ethical Assessment (REA) has been suggested as a feasible approach to meet this application gap. In the past few years REA has been employed in few research project in Ethiopia and have been found to be a useful and practical approach. Feasibility assessment of REA for the Ethiopian research setting was conducted between 2012-2013 in order to inform the subsequent introduction of REA into research ethics review and governance system in the country. REA was found to be an appropriate; relevant and feasible venture. We argue that REA can be integrated as part of the ethics review and governance system in Ethiopia. REA tools and techniques are considered relevant and acceptable to the Ethiopian research community; with few practical challenges anticipated in their implementation. REA are considered feasible for integration in the Ethiopian ethics review system

Assessment of skin barrier function in podoconiosis: measurement of stratum corneum hydration and transepidermal water loss.

BACKGROUND: Podoconiosis is a common cause of lymphoedema in barefoot workers in Ethiopia and other countries. It has severe consequences for patients' physical function, quality of life and economic status. AIMS: To investigate stratum corneum (SC) hydration and transepidermal water loss (TEWL) in patients with podoconiosis compared with controls. METHODS: In total, 55 patients and 20 controls were recruited. For each study subject, SC and TEWL measurements were taken, along with foot and lower leg circumferences. Measurements were compared between the patient and control groups. RESULTS: Foot circumferences tended to be higher in patients with podoconiosis, with the mean foot:leg circumference ratio being 1·19 (95% confidence interval 1·11-1·28) times that for controls (P = 0·001). There was no detectable difference between patients and controls in TEWL values (P > 0·05); however, SC hydration was significantly lower in patients vs. controls for the foot (P = 0·004) and lower leg (P = 0·046) sites. CONCLUSIONS: Patients with podoconiosis have significantly lower SC hydration in the skin of their lower legs and feet than controls, which may lead to cracking and splitting, and increased risk of lymphoedema and infection.

Investigating the effect of intolerance of uncertainty on catastrophic worrying and mood.

Intolerance of uncertainty (IU) is a construct known to influence catastrophic worry and is often observed in Generalized Anxiety Disorder (GAD). Research into the psychological manifestations of GAD suggests IU is associated with worry, but has not confirmed a causal link. The current study investigated the relationship between catastrophic worry and IU in a non-clinical undergraduate and postgraduate population (n = 46), with a mean age of 26.8 (SD = 5.52 years), where 71.74% were women. Participants received either a high or low IU manipulation, mood was measured throughout the study on 100 point visual analogue scales (VAS), and worry was measured using the catastrophising interview (CI). The high IU group generated significantly more catastrophising steps than the low IU group. Increased levels of sadness and anxiety were observed in the high as compared to the low IU group post IU manipulation, and this difference was maintained throughout the CI interview. A mediation analysis revealed that sadness and anxiety did not significantly mediate the relationship between IU and number of CI steps. These findings have implications for GAD treatment, as they suggest that manipulating IU affects measures of worry and its associated emotional and behavioural symptoms.

Effects of Helicobacter pylori, geohelminth infection and selected commensal bacteria on the risk of allergic disease and sensitization in 3-year-old Ethiopian children.

BACKGROUND: Epidemiological studies have suggested that gastro-intestinal infections including Helicobacter pylori, intestinal microflora (commensal bacteria) and geohelminths may influence the risk of asthma and allergy but data from early life are lacking. OBJECTIVE: We aimed to determine the independent effects of these infections on allergic disease symptoms and sensitization in an Ethiopian birth cohort. METHODS: In 2008/09, 878 children (87% of the 1006 original singletons in a population-based birth cohort) were followed up at age 3 and interview data obtained on allergic symptoms and potential confounders. Allergen skin tests to Dermatophagoides pteronyssinus and cockroach were performed, levels of Der p 1 and Bla g 1 in the child's bedding measured and stool samples analysed for geohelminths and, in a random subsample, enterococci, lactobacilli, bifidobacteria and H. pylori antigen. The independent effects of each exposure on wheeze, eczema, hayfever and sensitization were determined using multiple logistic regression. RESULTS: Children were commonly infected with H. pylori (41%; 253/616), enterococci (38.1%; 207/544), lactobacilli (31.1%; 169/544) and bifidobacteria (18.9%; 103/544) whereas geohelminths were only found in 8.5% (75/866). H. pylori infection was associated with a borderline significant reduced risk of eczema (adjusted OR 0.49, 95% CI 0.24-1.01, P=0.05) and D. pteronyssinus sensitization (adjusted OR 0.42, 95% CI 0.17-1.08, P=0.07). Geohelminths and intestinal microflora were not significantly associated with any of the outcomes measured. CONCLUSION AND CLINICAL RELEVANCE: Among young children in a developing country, we found evidence to support the hypothesis of a protective effect of H. pylori infection on the risk of allergic disease. Further investigation of the mechanism of this effect is therefore of potential therapeutic and preventive value.

Prevalence and risk factors of wheeze and eczema in 1-year-old children: the Butajira birth cohort, Ethiopia.

BACKGROUND: The rising global prevalence of asthma and other allergic conditions has been linked to potential aetiological factors influencing the developing immune system. OBJECTIVE: To investigate the prevalence and associated risk factors for wheeze and eczema in 1-year-old children in a birth cohort from Butajira, Ethiopia. METHODS: In 2005/6, a population-based cohort of 1065 pregnant women was established. At 1 year of age, data on wheeze and eczema in the children were collected from the mother via an interview-administered questionnaire, along with numerous demographic and lifestyle factors. A stool sample was also obtained from the child for geohelminth analysis. RESULTS: The prevalence of wheeze was 11.5% (103/899) and eczema 8.6% (77/899). Independent predictors of wheeze were maternal allergic history [adjusted OR (AOR)=3.00, 95% CI 1.23-7.36], paternal allergic history (AOR=2.59, 95% CI 1.08-6.25), increasing household size (P for trend=0.023; AOR=3.54, 95% CI 1.31-9.56 for 7+ vs. 1-3 individuals) and paracetamol use by the child (overall P<0.001; AOR 11.04, 95% CI 4.30-28.31 for 4+ tablets in past month vs. never). Factors independently associated with eczema were maternal allergic history (AOR=3.68, 95% CI 1.54-8.77), household size (overall P=0.035; AOR=0.45, 95% CI 0.23-0.87 for 4-6 individuals relative to 1-3) and place of sleeping (overall P<0.001; AOR=0.29, 95% CI 0.10-0.82 for floor vs. bed/platform). CONCLUSION: These findings support the hypothesis that eczema in early life in these children is a manifestation of allergy, while wheezing is probably due to infection as well as allergy.

The role of transforming growth factor-beta1 and oxidative stress in podoconiosis pathogenesis.

BACKGROUND: Podoconiosis (endemic nonfilarial elephantiasis) occurs in susceptible individuals who go barefoot in regions of irritant volcanic soil. Silicate particles absorbed via the skin are thought to induce an inflammatory process and a consequent endolymphangitis of the lower leg lymphatics. OBJECTIVES: To establish which oxidative stress biomarkers play a part in the inflammatory process, and to test whether transforming growth factor (TGF)-beta1 also has a pathogenetic role. PATIENTS AND METHODS: We enrolled 50 patients with early clinical stage disease, 43 patients with advanced stage disease and 35 local healthy controls. Oxidative stress biomarkers included serum total peroxides (TP), total antioxidant capacity (TAC), total nitrate plus nitrite (TN), malondialdehyde (MDA) and total superoxide dismutase (SOD) activity. The oxidative stress index (OSI) was also determined. Serum total TGF-beta1 was assayed using sandwich enzyme-linked immunosorbent assay. RESULTS: Compared with healthy controls, patients with early stage disease showed significantly higher mean levels of TP (P < 0.001), MDA (P < 0.05) and OSI (P < 0.01); and significantly lower mean concentrations of SOD (P < 0.001) and TGF-beta1 (P < 0.001). Mean levels of TGF-beta1 were even lower among patients with advanced stage disease (P < 0.001). Mean TAC levels were significantly lower among patients with advanced disease than either other group (P < 0.001). CONCLUSIONS: This is the first study, to our knowledge, to attempt to elucidate the molecular pathogenetic events in podoconiosis. We conclude that TGF-beta1 may have a pathogenetic role, with oxidative stress playing a minor role in the early stages of disease.

Podoconiosis, non-filarial elephantiasis, and lymphology.

Several recent reviews of podoconiosis already exist in journals and on public access websites. After briefly covering the historical and epidemiological background, this narrative review will therefore attempt explicitly to link podoconiosis with lymphology, examining gaps in what is known of pathogenesis and identifying the areas of research in which input from lymphologists is most required. Finally, prevention and treatment will be described and the need for operational research to optimize community-based interventions outlined.

Recent advances in podoconiosis.

In terms of either research or public-health policy, podoconiosis, a non-infectious form of elephantiasis, has received little attention since the 1980s. The aim of this narrative review is to examine the results of the relevant research published in the past 2 years, in the context of the data from earlier investigations. The review concludes by indicating areas in which further investigation is necessary before robust intervention strategies, to reduce the public-health burden posed by podoconiosis, can be devised.

Generic construction of single component particles that elicit humoural and cellular immune responses without the need for adjuvants.

Insoluble, pure protein particles could be advantageous as single-entity vaccines or as carriers for small peptide epitopes. Dense gas anti-solvent precipitation was employed to produce pure protein particles which were found to be insoluble in water. As particulate and multimerized antigens are more immunogenic and hence more advantageous for vaccination, particles were produced via this method using ovalbumin as a model antigen. The particles produced had a mean diameter of approximately 300nm, and remained as discrete particles at low pH. At neutral pH or in the presence of electrolyte, the particles exhibited predictable flocculation behaviour to produce aggregates 1-5microm in diameter. Immunisation of mice with these flocculates elicited specific ovalbumin antibody production, T-cell proliferation and a cytotoxic T-cell response, all in the absence of adjuvant. Thus, dense gas processing could be used as a generic method to produce pure protein particulate vaccines.

The economic impact of HIV/AIDS morbidity and mortality on households in Addis Ababa, Ethiopia.

The present study investigates whether the household-level economic impact of an adult AIDS death is different from that of death from another cause. The data come from cross-sectional post-mortem interviews (verbal autopsies) with relatives or primary caregivers of deceased adults randomly selected from deaths recorded in an ongoing burial surveillance in Addis Ababa. Our analyses consist of three parts. First, we assess the sociodemographic risk factors for AIDS mortality. Subsequently, we reverse the causal order of this relationship and carry out an analysis of the effect of AIDS mortality on the subjective experience of change in the household's financial situation following the death of a household member. Finally, we quantify the direct and indirect costs of illness and death on the household. Results indicate that households experiencing an HIV/AIDS death are poorer than those experiencing a non-HIV/AIDS death. In addition, poorer households experience a greater decline in socioeconomic status following death of a household member. AIDS mortality has more detrimental effects on the household economic status than deaths due to other causes. While the difference between AIDS and non-AIDS mortality in terms of direct costs is minimal, the indirect cost of an AIDS death per household exceeds that of non-AIDS death by 58%. In conclusion, poor households are more likely to experience an AIDS death and in turn are more vulnerable to the socioeconomic impact of death. Therefore, it is justifiable to target HIV-impact mitigation programs on poorer households.

Validation of the Dermatology Life Quality Index among patients with podoconiosis in southern Ethiopia.

BACKGROUND: Podoconiosis is a geochemical elephantiasis common among subsistence farmers in Ethiopia. It is completely preventable but, untreated, leads to considerable physical disability, social stigma and economic disadvantage. Quality of life has to date not been assessed among patients with podoconiosis. OBJECTIVES: We aimed to assess the feasibility, internal consistency and concurrent validity of an Amharic translation of the Cardiff Dermatology Life Quality Index (DLQI) among patients with podoconiosis in southern Ethiopia. METHODS: We performed a comparative cross-sectional study among 74 new patients and 74 patients treated for at least 3 months at outreach clinics of the Mossy Foot Treatment and Prevention Association, a nongovernment organization providing services for more than 30,000 patients annually in southern Ethiopia. RESULTS: The DLQI was quick and simple to use, taking on average 4 min to administer. It distinguished successfully between new and treated patients (median scores 13 vs. 3, P < 0.001). The inter-item correlation averaged 0.44, and Cronbach's alpha was 0.90, indicating high internal consistency. The mean DLQI score for all patients was 8.42, and the highest score was for item 2 (feeling self-conscious). The item with the highest score among new patients was item 1 (pain), while that among treated patients was item 4 (clothes choice). CONCLUSIONS: The Amharic DLQI appears feasible, reliable and valid among patients with podoconiosis in southern Ethiopia. The DLQI will play an important role in assessing the physical and social interventions available locally and in guiding the roll-out of these interventions to much larger groups of patients throughout Ethiopia.

Repeatability and validity of IUATLD Respiratory Questionnaire responses as a measure of asthma in an Ethiopian population.

OBJECTIVE: To assess the repeatability and validity of the IUATLD respiratory symptoms questionnaire in relation to exercise-induced bronchoconstriction or bronchodilator responses in a community in southern Ethiopia. DESIGN: A case-control study. SETTING: Rural and small town setting in southern Ethiopia, April to May 2006. SUBJECTS: Two hundred and forty seven adults and children who previously reported wheeze in the past year, and 174 who did not. INTERVENTIONS: Administered IUATLD bronchial symptoms questionnaire; standardised free-running exercise test or (for those with airflow obstruction) assessment of bronchodilator response to inhaled salbutamol. RESULTS: Kappa values for four-week repeatability for the wheeze and asthma questions were 0.61 (95% CI 0.52 to 0.70) and 0.75 (0.63 to 0.87), respectively. Of the 58 people who reported wheeze in 2003 and in April 2006, only five had a positive exercise test or bronchodilator challenge (Positive Predictive Value (PPV) 0.09, 95% CI 0.01 to 0.22). Of the 12 who reported asthma in 2003 and April 2006, three had a positive result to either to exercise test or bronchodilator challenge test (PPV 0.25, 95% CI 0.05 to 0.50). CONCLUSION: Our findings suggest that self-reported wheeze and asthma have good short-term repeatability, but do not closely reflect exercise-induced bronchospasm or bronchodilator responsiveness. The validity of questionnaire methods of studying asthma epidemiology in developing countries needs further investigation.

Adherence to ART in PLWHA at Yirgalem Hospital; South Ethiopia

Background: Non-adherence to Antiretroviral Therapy is a major challenge to AIDS care; and the risks associated with it are extensive. Objective: To assess factors associated with non-adherence among AIDS patients receiving Antiretroviral Therapy at Yirgalem Hospital; Southern Ethiopia. Method: A comparative cross sectional survey was carried out at Yirgalem Hospital between July 10 and August 30; 2006. The two-proportion formula for unmatched case control study with 1:3 ratio was used to calculate the sample size. Systematic sampling was used to recruit patients. Using a structured and pre-tested questionnaire; data on drug adherence were collected through interview and pill count. Non-adherent patients were compared with adherent patients and associations with key risk factors were determined. Results: Two hundred and ninety one AIDS patients were involved in the survey. Prevalence of adherence in the week before interview was 74.2. Main reasons of non-adherence cited by the patients were; being busy or simply forgetting (51); change in daily routine (9.4); and being away from home (8.3). Non-adherence was commoner among patients reporting symptoms in the past four weeks (Adj. OR=6.41; 95CI: 2.41 to 17.08); who lived more than 47 km away (AOR= 2.48; 95CI: 1.24 to 4.98); or who had dependents (Adj. OR=1.95; 95CI: 1.06 to 3.57). Conclusions: Efforts must be made to make the service accessible by commencement of ART service in more Health Centers; to improve patients' awareness of ARV adverse effects; and to provide social support to all People Living with HIV; particularly those who have dependents.http://indexmedicus.afro.who.int/iah/fulltext/EJHD/vol 22 n2/Adherence to ART 174-179

Hydrogen peroxide derived from amine oxidation mediates the interaction between aminosugars and semicarbazide-sensitive amine oxidase.

Semicarbazide-sensitive amine oxidase (SSAO) also functions as a vascular-adhesion protein (VAP-1). The nature of the target site on lymphocytes to which endothelial-cell SSAO/VAP-1 binds is unknown. We have shown that amino sugars (galactosamine, glucosamine and mannosamine), which are not SSAO substrates, can bind to the enzyme as reversible inhibitors. Thus, they serve as a model system in which to study the interaction process. Binding occurred during substrate (benzylamine) oxidation but not when the amino sugar was incubated, for extended periods, with SSAO alone. These results suggest that one, or more of the products of the SSAO-catalysed amine oxidation might be necessary for the inhibitory process to occur. Two of the reaction products of benzylamine oxidation, benzaldehyde and ammonia were found to have no effect on the inhibition of SSAO by galactosamine. Preincubation of the enzyme with galactosamine plus H(2)O(2) was, however, found to result in time-dependent inhibition. This is not a result of the non-enzymic reaction between H(2)O(2) and the amino sugar, since preincubation of galactosamine with H(2)O(2) alone, for extended periods, did not give rise to an inhibitory species. The amount of exogenously added H(2)O(2) necessary for inhibition was very much greater than that formed during substrate oxidation. These results suggest that the H(2)O(2) formed as a product of the SSAO-catalysed oxidation reaction is more efective in promoting the binding of amino sugars.