Lymph is returned to the blood circulation exclusively via four lymphovenous valves (LVVs). Despite their vital importance, the architecture and development of LVVs is poorly understood. We analyzed the formation of LVVs at the molecular and ultrastructural levels during mouse embryogenesis and identified three critical steps. First, LVV-forming endothelial cells (LVV-ECs) differentiate from PROX1+ progenitors and delaminate from the luminal side of the veins. Second, LVV-ECs aggregate, align perpendicular to the direction of lymph flow and establish lympho-venous connections. Finally, LVVs mature with the recruitment of mural cells. LVV morphogenesis is disrupted in four different mouse models of primary lymphedema and the severity of LVV defects correlate with that of lymphedema. In summary, we have provided the first and the most comprehensive analysis of LVV development. Furthermore, our work suggests that aberrant LVVs contribute to lymphedema.

Leprosy is not eradicable with currently available diagnostics or interventions as evidenced by its stable incidence. Early diagnosis of Mycobacterium leprae infection should therefore be emphasized in leprosy-research. It remains challenging to develop tests based on immunological biomarkers that distinguish individuals controlling bacterial replication from those developing disease. To identify biomarkers for field-applicable diagnostics, we determined cytokines/chemokines induced by M. leprae proteins in blood of leprosy patients and controls (EC) from high leprosy-prevalence areas (Bangladesh, Brazil, Ethiopia) and from South Korea where leprosy is not endemic anymore. M. leprae- sonicate induced IFN-γ was similar for all groups, excluding M. leprae/IFN-γ as a diagnostic read-out. By contrast, ML2478 and ML0840 induced high IFN-γ concentrations in Bangladeshi EC, which were completely absent for South Korean controls. Importantly, ML2478/IFN-γ could indicate distinct degrees of M. leprae exposure, and thereby the risk of infection and transmission, in different parts of Brazilian and Ethiopian cities. Notwithstanding these discriminatory responses, M. leprae proteins did not distinguish patients from EC in one leprosy endemic area based on IFN-γ. Analyses of additional cytokines/chemokines showed that M. leprae and ML2478 induced significantly higher concentrations of MCP-1, MIP-1β and IL-1β in patients compared to EC, whereas IP-10, like IFN-γ, differed between EC from areas with dissimilar leprosy prevalence. This study identifies M. leprae-unique antigens, particularly ML2478, as biomarker tools to measure M. leprae exposure using IFN-γ or IP-10, and also shows that MCP-1, MIP-1β and IL-1β can potentially distinguish pathogenic immune responses from those induced during asymptomatic exposure to M. leprae.

BackgroundThere are limited data on TB among prison inmates in Bangladesh. The aim of the study was to determine the prevalence of pulmonary tuberculosis (TB), its drug resistance and risk factors in Dhaka Central Jail, the largest prison in Bangladesh.MethodsCross sectional survey with, active screening of a total number of 11,001 inmates over a period of 2 years. Sputum samples from TB suspects were taken for acid- fast bacilli (AFB) microscopy, culture and drug susceptibility testing.ResultsAmong 1,781 TB suspects 245 (13.8%) were positive for AFB on microscopy and/or culture. The prevalence rate of sputum- positive pulmonary TB was 2,227/100,000. Fifty three cases (21.6% of 245 cases) were AFB- negative on microscopy but were found positive on culture. Resistance to isoniazid, rifampicin, streptomycin and ethambutol was 11.4%, 0.8%, 22.4% and 6.5% respectively. No multidrug resistance was observed. The main risk factors of TB in prison were exposure to TB patients (adjusted odds ratio 3.16, 95% CI 2.36–4.21), previous imprisonment (1.86, 1.38–2.50), longer duration of stay in prison (17.5 months for TB cases; 1.004, 1.001–1.006) and low body mass index which is less than 18.5 kg/m2 (5.37, 4.02–7.16).ConclusionsThe study results revealed a very high prevalence of TB in the prison population in Dhaka Central Jail. Entry examinations and active symptom screening among inmates are important to control TB transmission inside the prison. Identifying undiagnosed smear-negative TB cases remains a challenge to combat this deadly disease in this difficult setting.

BackgroundThe objectives of this study were to assess the tuberculosis (TB) burden and to provide an insight into the type of circulating M. tuberculosis species in urban slums of Bangladesh. We also aimed to test the feasibility of a larger transmission study in this setting.MethodsThis cross-sectional study was conducted in an urban slum of Dhaka city. The household members were actively screened to assess the presence of TB-related signs and symptoms; cough ≥3 weeks and body mass index (BMI) <17 kg/m2. Sputum specimens from suspects were collected for acid fast bacilli (AFB) microscopy, culture and drug susceptibility testing. Genotyping of M. tuberculosis was done using spoligotyping and variable number tandem repeats of mycobacterial interspersed repetitive units typing.ResultsAmong 9,877 adult screened for pulmonary TB (PTB), 25 were positive for AFB on microscopy and/or culture and the prevalence of new PTB cases was estimated to be 253/100,000. Only one child TB case was diagnosed among 5,147 child screened. Out of 26 cases, 21(81%) had cough for several duration and 5(19%) did not present with cough at the time of screening. One multidrug resistant case was found. Fifty two percent of all TB cases had BMI <17 kg/m2 (p = <0.001). Among the 20 analyzed isolates, 13 different spoligotype patterns were identified in which 5 clusters contained 12 strains and 8 strains had unique pattern.ConclusionsThe study revealed high prevalence of TB in urban slums. Screening using low BMI can be beneficial among risk group population. It is important to conduct larger study to validate clinical variables like cough <3 weeks and low BMI to define TB suspect and also to investigate the transmission of TB in slum settings.

BackgroundSputum smear microscopy is fast and inexpensive technique for detecting tuberculosis (TB) in high incidence areas but has low sensitivity. Physical and chemical sputum processing along with centrifugation have been found to show promise in overcoming this limitation. Our objective was to compare the sensitivity of smear microscopy obtained with smears made directly from respiratory specimens to those from concentrated specimens.MethodsBy active screening, 915 TB suspects were identified from Dhaka Central Jail and sputum specimens were aseptically collected. Direct smears were prepared by taking a small portion of the purulent part of the sputum with a sterile loop. The specimens were then processed by a standard N-acetyl-L-cysteine-NaOH digestion-decontamination method to prepare concentrated specimens. Both smears were then air dried, heat fixed, and stained by the Ziehl-Neelsen staining technique. The stained slides were examined under oil immersion and were graded following International Union Against Tuberculosis and Lung Diseases guidelines. All the specimens were inoculated into Lowenstein-Jensen (L-J) media and culture results were considered as gold standard to calculate sensitivity.ResultsOf 915 specimens, 73 (8%) specimens were positive both on direct and concentrated methods, one sample was positive on direct microscopy but was negative on concentrated method. An extra 14 (1.5%) samples were positive on concentrated method which were negative on direct smear. In L-J media 105 specimens were found positive for TB bacilli and of them, 74 (70.5%) and 87 (82.9%) were positive in direct and concentrated smear, respectively. The sensitivity of direct and concentrated smear microscopy was different when using positive culture as the gold standard (71% vs. 83%).ConclusionsThe results showed that concentrated technique increases the sensitivity of microscopy up to 12%. Therefore, the national programs in high TB burden countries may consider incorporating the technique into their guidelines at least in the district and higher level laboratories to improve case finding strategy.

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Background This study was set out to investigate the magnitude, patterns and molecular characterization of drug-resistant Mycobacterium tuberculosis strains at a tertiary referral hospital in Bangladesh. Methods Pulmonary tuberculosis (TB) patients admitted at National Institute of Diseases of the Chest and Hospital from February 2002 to September 2005 with or without previous history of TB and/or other complications were randomly interviewed. Among 265 participants enrolled, M. tuberculosis isolates from 189 patients were finally tested for susceptibility to rifampicin (RMP), isoniazid (INH), ethambutol (ETM) and streptomycin (STM). Genotyping of M. tuberculosis was done using deletion analysis and spoligotyping. Results Eighty-eight percent (n = 167) of the patients had history of previous anti-TB treatment while the remaining 12% were new TB cases. Of the 189 isolates, 9% were fully susceptible to the first line anti-TB drugs and 73.5% were multi-drug resistant TB. Other susceptibility results showed 79.4%, 77.2%, 76.7% and 78.8% resistance to INH, RMP, ETM and STM respectively. Multi-drug resistance was significantly higher among the 130 (78%) patients with previous history of anti-tuberculosis treatment (95% confidence interval, p = 0.001). Among the 189 analyzed isolates, 69% were classified as “modern” M. tuberculosis strains (i.e. TbD1- strains, lacking the M. tuberculosis -deletion region TbD1), whereas the remaining 31% were found to belong to the “ancestal” TbD1+ M. tuberculosis lineages. One hundred and five different spoligotype patterns were identified in which 16 clusters contained 100 strains and 89 strains had unique pattern. Strains with a spoligotype characteristic for the “Beijing” cluster were predominant (19%) and most of these strains (75%) were multi-drug resistant (MDR). Conclusions A high level of drug resistance observed among the re-treatment patients poses a threat of transmission of resistant strains to susceptible persons in the community. Proper counseling of patients and attention towards the completion of the anti-TB treatment is needed.

Background: Rifampicin resistance (RR) is a key indicator of multidrug-resistant tuberculosis (MDR-TB) and 95% of the RR is associated with the mutation in the 81-bp rifampicin resistance determining region (RRDR) of the rpoB gene of Mycobacterium tuberculosis complex (MTBC). The Xpert MTB/RIF (Xpert) assay uses five overlapping molecular beacon probes (A-E) complementary to RRDR region that detect MTBC and mutations associated with RR. The objective of the study was to investigate the distribution and frequency of mutations detected by Xpert assay among Beijing and non-Beijing RR-TB isolates. Methods: A total of 205 randomly selected RR-TB specimens detected by Xpert assay were included in this study. A portion of specimens was further subjected to culture, MTBDRplus test and the positive culture isolates were genotyped by spoligotyping. Results: We found that the most frequent mutation occurred at probe E (S531L) binding region in both Beijing and non-Beijing isolates (61.9% and 66.9%, respectively). The Beijing family had higher mutation rates than non-Beijing (19.0% vs 12.4%) at probe B (D516V) while the non-Beijing family had higher mutations at probe D (H526D or H526Y) than the Beijing (13.2% vs 10.7%) family. Mutations at probes Aand C were less common in both Beijing and non-Beijing isolates. There was no significant difference (P=0.36) in the occurrence of mutations at different probes between Beijing and non-Beijing isolates. Conclusions: The study results revealed that the most frequent mutation occurs in the region of probe E and the least common mutations at probe A and C among both Beijing and non-Beijing RR-TB cases. This first insight into the probe mutation variation and frequencies among the RR-TB cases in Bangladesh forms the baseline information for further investigation.