A peptide-binding domain shared with an Antarctic bacterium facilitates Vibrio cholerae human cell binding and intestinal colonization

Vibrio cholerae, the causative agent of the disease cholera, is responsible for multiple pandemics. V. cholerae binds to and colonizes the gastrointestinal tract within the human host, as well as various surfaces in the marine environment (e.g., zooplankton) during interepidemic periods. A large adhesin, the Flagellar Regulated Hemagglutinin A (FrhA), enhances binding to erythrocytes and epithelial cells and enhances intestinal colonization. We identified a peptide-binding domain (PBD) within FrhA that mediates hemagglutination, binding to epithelial cells, intestinal colonization, and facilitates biofilm formation. Intriguingly, this domain is also found in the ice-binding protein of the Antarctic bacterium Marinomonas primoryensis, where it mediates binding to diatoms. Peptide inhibitors of the M. primoryensis PBD inhibit V. cholerae binding to human cells as well as to diatoms and inhibit biofilm formation. Moreover, the M. primoryensis PBD inserted into FrhA allows V. cholerae to bind human cells and colonize the intestine and also enhances biofilm formation, demonstrating the interchangeability of the PBD from these bacteria. Importantly, peptide inhibitors of PBD reduce V. cholerae intestinal colonization in infant mice. These studies demonstrate how V. cholerae uses a PBD shared with a diatom-binding Antarctic bacterium to facilitate intestinal colonization in humans and biofilm formation in the environment.

A randomized Phase I/II study to evaluate safety and reactogenicity of a heat-stable rotavirus vaccine in healthy adults followed by evaluation of the safety, reactogenicity, and immunogenicity in infants

Objectives: To assess the safety and reactogenicity of single oral dose of heat-stable rotavirus vaccine (HSRV) in healthy adults aged 18–45 years followed by assessment of safety, reactogenicity, and immunogenicity of three doses of HSRV in healthy infants aged 6–8 weeks at enrollment.

Trial Design: Single-center randomized controlled, sequential, blinded (adults) and open-label (infants).

Setting: Single site at International Center for Diarrheal Disease Research, Bangladesh (icddr,b).

Participants: Fifty eligible adults randomized in 1:1 ratio (HSRV: Placebo) followed by 50 eligible infants randomized in 1:1 ratio (HSRV: Comparator (RotaTeq®, pentavalent human-bovine (WC3) reassortant live-attenuated, rotavirus vaccine)).

Intervention: Adults received either a single dose of HSRV or placebo and followed for 14 days. Infants received three doses of either HSRV or comparator with a follow-up for 28 days after each dose.

Main Outcome Measures: Solicited and unsolicited adverse events (AEs) along with any serious adverse events (SAEs) were part of the safety and reactogenicity assessment in adults and infants whereas serum anti-rotavirus IgA response rates were part of immunogenicity assessment in infants only. Post-vaccination fecal shedding of vaccine-virus rotavirus strains was also determined in adults and infants.

Results: In this study, HSRV, when compared with placebo, did not result in increase in solicited adverse events (solicited AEs) in adults. In infants, HSRV had a safety profile similar to comparator vis-à-vis solicited AEs. In infants, fecal shedding of vaccine-virus strains was not detected in HSRV recipients but was observed in two comparator recipients. Percentage of infants exhibiting threefold rise in serum anti-rotavirus IgA titers from baseline to 1-month post-dose 3 in HSRV group was 88% (22/25) and 84% (21/25) in comparator group.

Conclusion: HSRV was found to be generally well-tolerated in both adults and infants and immunogenic in infants.

Risk factors for mortality among inpatients with smear positive pulmonary tuberculosis

Objective

To evaluate risk factors having significant effect on mortality of smear positive Pulmonary Tuberculosis (PTB) inpatients.

Methods

A descriptive cross-sectional study was conducted at Ojha Institute of Chest Diseases, Dow University Hospital Ojha Campus, Karachi. One hundred and seventy (170) inpatients of smear positive PTB confirmed by Acid Fast Bacilli (AFB) smear, aged between 13-80 years were enrolled by using consecutive sampling technique while patients with drug resistant Tuberculosis (TB) and extra pulmonary TB were excluded from the study. Selected patients were interviewed for collecting demographic data and risk factor data by using a standard questionnaire.

Results

Out of 170 PTB inpatients, mortality was observed in 23 (13.5%) patients among which male patients were 12 (52.2%), and female were 11 (47.8%). Mortality was significantly associated with increasing age (p=0.003), socioeconomic status (p=0.019), anemia (p=0.03), Chronic Liver Disease (CLD) (p=0.005), Diabetes Mellitus (DM) (p=0.001), Human Immunodeficiency Virus (HIV) (p=0.007), Hypertension (HTN) (p=0.006), recurrent TB (p=0.001), and smoking (p=0.001).

Conclusion

Increasing age, poverty, smoking history, and presence of comorbidities like DM, CLD, HIV, hypertension, and anemia are associated with higher mortality in smear positive PTB cases.

Peripapillary Retinal Nerve Fiber Layer (RNFL) Thickness Measurements by Topcon SD-OCT in Myopic Patients

OBJECTIVE

To evaluate the effect of low-to-moderate myopia on peripapillary retinal nerve fiber layer (RNFL) thickness measured by Topcon SD optical coherence tomography (OCT).

STUDY DESIGN

Cross-sectional study.

PLACE AND DURATION OF STUDY

Ophthalmology Department, Shifa Foundation Falahee Clinic, over a period of one year starting from June 2015.

METHODOLOGY

A total of 43 eyes of 43 patients, having mild to moderate myopic refractive error, were enrolled in the study. Refractive error/spherical equivalent was calculated. RNFL thickness was obtained from all four peripapillary quadrants: temporal, superior, nasal, and inferior; and 12 sub-quadrants using Topcon SD OCT. Pearson correlation coefficients (r) were calculated to evaluate relationships between the RNFL thickness and spherical equivalent (SE) before and after adjustment for ocular magnification.

RESULTS

The study included 51.2% females and 48.8% males. Mean age was 30.9 ±6.45 years. Mean axial length was 24.25 ±0.91 mm. Mean SE was -3.25 ±1.93 DS. Mean of average RNFL thickness (with Littmann's correction) was 97.28 ±8.15 µm. Correlation analysis among all subjects showed that the average, mean nasal quadrant, upper nasal, and inferonasal sub-quadrant RNFL thickness had positive correlation with spherical equivalent (r = 0.31, p = 0.045).However, correction of the magnification effect by applying Littmann formula eliminated this effect.

CONCLUSION

In low-to-moderate myopia, RNFL measurements vary with refractive error of the eye. Since ocular magnification significantly affects the RNFL measurement, it should be considered in diagnosing glaucoma.

Yield of closed pleural biopsy and cytology in exudative pleural effusion

Objective:

To determine diagnostic yield of Closed Pleural Biopsy (CPB) and Cytology in Exudative Pleural Effusion (PE).

Methods:

This prospective comparative study was conducted at Chest Unit-II & Medical Unit-IV of Dow University of Health Sciences, Karachi Pakistan from January 2011 till December 2014.

Results:

Ninety-four patients with exudative PE were finally included. The mean age (SD) was 44.0 (13.8) years. Overall Specific Diagnosis was reached in 76/94 patients; 46 Tuberculosis PE (TPE) & 30 Malignant PE (MPE). CPB diagnosed all TPE patients alone and 28/30 of MPE. Cytology diagnosed only 10/30 patients of MPE with 8 patients having both CPB & Cytology positive for malignancy whereas in the remaining two cases only Cytology positive. The sensitivity of CPB in detecting TPE and MPE was 93.9% and 82.4% respectively whereas specificity for both was 100%. The diagnostic yield of cytology in detecting MPE is only (33.3%). The diagnostic yield of CPB for TPE and MPE is 100% and 93.3% respectively. The overall specific diagnostic yield of CPB is 78.7%.

Conclusion:

CPB is better than pleural fluid cytology alone with the later adding little to diagnostic yield when both combined in distinguishing TPE from MPE, the two main differential of exudative PE in a TB-Endemic country.

A bacterial hemerythrin domain regulates the activity of a Vibrio cholerae diguanylate cyclase

The first demonstrated example of a regulatory function for a bacterial hemerythrin (Bhr) domain is reported. Bhrs have a characteristic sequence motif providing ligand residues for a type of non-heme diiron site that is known to bind O(2) and undergo autoxidation. The amino acid sequence encoded by the VC1216 gene from Vibrio cholerae O1 biovar El Tor str. N16961 contains an N-terminal Bhr domain connected to a C-terminal domain characteristic of bacterial diguanylate cyclases (DGCs) that catalyze formation of cyclic di-(3',5')-guanosine monophosphate (c-di-GMP) from GTP. This protein, Vc Bhr-DGC, was found to contain two tightly bound non-heme iron atoms per protein monomer. The as-isolated protein showed the spectroscopic signatures of oxo/dicarboxylato-bridged non-heme diferric sites of previously characterized Bhr domains. The diiron site was capable of cycling between diferric and diferrous forms, the latter of which was stable only under anaerobic conditions, undergoing rapid autoxidation upon being exposed to air. Vc Bhr-DGC showed approximately 10 times higher DGC activity in the diferrous than in the diferric form. The level of intracellular c-di-GMP is known to regulate biofilm formation in V. cholerae. The higher DGC activity of the diferrous Vc Bhr-DGC is consistent with induction of biofilm formation in low-dioxygen environments. The non-heme diiron cofactor in the Bhr domain thus represents an alternative to heme or flavin for redox and/or diatomic gas sensing and regulation of DGC activity.

Mannose-containing oligosaccharides of non-specific human secretory immunoglobulin A mediate inhibition of Vibrio cholerae biofilm formation

The role of antigen-specific secretory IgA (SIgA) has been studied extensively, whereas there is a limited body of evidence regarding the contribution of non-specific SIgA to innate immune defenses against invading pathogens. In this study, we evaluated the effects of non-specific SIgA against infection with Vibrio cholerae O139 strain MO10 and biofilm formation. Seven day old infant mice deficient in IgA (IgA^-/- mice) displayed significantly greater intestinal MO10 burden at 24 hr post-challenge when compared to IgA^+/+ pups. Importantly, cross-fostering of IgA^-/- pups with IgA^+/+ nursing dams reversed the greater susceptibility to MO10 infection, suggesting a role for non-specific SIgA in protection against the infection. Since biofilm formation is associated with virulence of MO10, we further examined the role of human non-specific SIgA on this virulence phenotype of the pathogen. Human non-specific SIgA, in a dose-dependent fashion, significantly reduced the biofilm formation by MO10 without affecting the viability of the bacterium. Such an inhibitory effect was not induced by human serum IgA, IgG, or IgM, suggesting a role for the oligosaccharide-rich secretory component (SC) of SIgA. This was supported by the demonstration that SIgA treated with endoglycosidase H, to cleave the high-mannose containing terminal chitobiose residues, did not induce a reduction in biofilm formation by MO10. Furthermore, the addition of free mannose per se, across a wide dose range, induced significant reduction in MO10 biofilm formation. Collectively, these results suggest that mannose containing oligosacchardies within human non-specific secretory IgA can alter important virulence phenotypes of Vibrio cholerae such as biofilm formation, without affecting viability of the microorganism. Such effects may contribute significantly to innate immune defenses against invading pathogens in vivo in the gastrointestinal tract.

Factors that affect implementation of web-based faculty evaluation forms: residents' perspectives from a developing country

CONTEXT

A web-based evaluation system for residents to provide feedback on faculty was piloted in four training programs at the Aga Khan University prior to institution-wide implementation. Of the four programs, less than 50% of forms were submitted by residents of three programs while more than 70% of forms were submitted by the residents of one program. This study was conducted to identify reasons for the varying participation rates of the four programs with a view to improving the system.

METHODS

A qualitative approach was employed using focus group discussions (FGDs). Volunteers were invited and three groups of eight to ten residents each were formed. Participants for FGDs were selected from all residency years. FGDs were used to identify residents' perceptions regarding the web-based faculty evaluation system and to identify residents' problems and concerns with completing the web-based faculty evaluating forms.

RESULTS

Technical issues in completing and submitting the forms online were identified to be the main deterrents to completing the evaluation forms. Non-accessibility of a resource person for resolving technical problems with the software and the burden of taking time out to complete the forms were considered as limiting factors by many residents. Residents recommended a focused orientation session to the new system within the departments.

CONCLUSION

Residents' confidence and support are key to promoting adequate participation in web-based evaluations. Focused orientation sessions, reinforcement, reminders, assurances of confidentiality, and removal of technical glitches should help to improve resident participation.

Cancer esophagus Karachi 1995-2002: epidemiology, risk factors and trends

OBJECTIVE

To study the trends of cancer esophagus in Karachi South during 1995-2002 and identify risk factors.

METHODS

Incident esophageal cancer cases recorded at the Karachi Cancer Registry for Karachi South, during 1st January 1995 to 31st December 2003 were reviewed. For maximum completion of data, incident cases registered from 1st January 1995 to 31st December 2002 were included for final analyses.

RESULTS

The Age Standardized Incidence Rates (ASIRs) of cancer esophagus in Karachi South for males were 6.5/100,000 (1995-1997) and 6.4/100,000 (1998-2002). In females the observed rates were 7.0/100,000 (1995-1997) and 8.6/100,000 (1998-2002).

CONCLUSION

In the moderately high incidence, cancer esophagus zone of Karachi, the ASIRs in males remained stable during the last decade, but in females, an upward trend was observed suggesting a progressively higher exposure to risk factors in the latter. The potential risk factors in Karachi are use of all forms of tobacco, areca nut, infrequent consumption of raw fruits and vegetables and diet deficiencies. There is a necessity to actively control the proven risk factors and address the existence of other risk factors. The primary recommended strategy for the control of cancer esophagus would therefore be legislation against tobacco and areca nut in Pakistan and public health education. The risk factors of cancer esophagus identified in this article need to be further confirmed.

Subcutaneous panniculitic T cell lymphoma mimicking histiocytic cytophagic panniculitis in a child

Subcutaneous panniculitic T-cell lymphoma is a very rare malignancy in the pediatric age group, its association with hemophagocytic syndrome had been described but the association with the skin lesions mimicking histiocytic cytophagic panniculitis which is characteristic of hemophagocytic syndrome has not, to our knowledge, been described in children. We report a child with panniculitic T-cell lymphoma associated with bone marrow hemophagocytosis and subcutaneous histiocytic infiltration with active phagocytosis simulating histiocytic cytophagic. We stress the importance of searching for T-cell lymphoma in patients with panniculitis and hemophagocytic syndrome.

Toxicity of 3'-deamino-3'-(3-cyano-4-morpholinyl) doxorubicin and doxorubicin in nude mice bearing human tumour xenografts

The toxicity of the intensely potent anthracycline 3'deamino-3'-(3-cyano-4-morpholinyl)doxorubicin (MRA-CN) has been evaluated in nude mice bearing human colonic cancer xenografts. In addition to dose related toxicity manifested as weight loss and effects on the haematology profile, we obtained evidence of cardiotoxicity with MRA-CN, which has not been reported previously. Even a single dose of 0.012 mg kg-1 could induce significant myocardial changes as seen by electron microscopy. Our results suggest that nude mice bearing human tumour xenografts may offer a very sensitive model for the evaluation of anthracycline induced cardiomyopathy. In view of the potential of MRA-CN in cancer treatment, these results need to be confirmed and extended.

Immunocytochemical investigation of carcinoembryonic antigen expression in neuroblastoma with monoclonal and polyclonal antibodies

Immunocytochemical localization of two monoclonal anticarcinoembryonic antigen antibodies (11-285-14; 11-359-6) which recognize different CEA epitopes, and a polyclonal anti-CEA antibody (DAKO) recognizing both carcinoembryonic antigen and nonspecific cross-reacting antigen, was studied in 59 tumor tissue samples from 18 patients with neuroblastoma. No evidence of intact tumor cell staining was seen with any of the antibodies although the polyclonal antibody often stained necrotic tissue and infiltrating inflammatory cells. It is concluded that at the level of sensitivity of immunocytochemical localization, neuroblastoma cells do not express carcinoembryonic antigen.

Familial intracranial gliomas

The pedigree of two interrelated families with 10 affected members suffering from malignant supratentorial gliomas is reported. In addition, three other unrelated families with two members each who were treated for different types of brain tumors are described. Genetic implications are discussed.

Acute renal failure in an infant with congenital neuroblastoma - successful treatment by hemodialysis

Acute renal failure developed in an infant aged 30 days during chemotherapy and irradiation for hepatic neuroblastoma (IV-S). Acute hemodialysis via a profunda femoris - long saphenous vein shunt was accomplished on 9 occasions in this 4 kg infant. The complications of septicemia and acute respiratory embarrassment caused by hepatomegaly were treated by appropriate antibiotic treatment, creation of a temporary ventral hernia and assisted ventilation. Careful attention to correct pediatric hemodialysis technique, as described, can permit long-term survival if the underlying disorder is also amenable to treatment.

Thymus-dependent lymphocytes and delayed hypersensitivity in low birth weight infants

The proportion of thymus-dependent (T) lymphocytes in the blood and the ability to mount cutaneous delayed hypersensitivity to a battery of antigens were evaluated in 50 low birth weight (LBW) infants when they were 3 months to 5 years old. There was a significant reduction in the number of T lymphocytes. Delayed hypersensitivity was impaired. The abnormalities were more pronounced in those with persistent growth retardation. It is suggested that continued postnatal depression of cell-mediated immunity in LBW infants may contribute to increased frequency of infections and immunopathological diseases.