Molecular characterisation of drug resistance in Mycobacterium tuberculosis isolates from North India

SETTING

A tertiary care hospital in North India.

OBJECTIVES

To analyse the frequency of mutations associated with resistance to rifampicin (RMP), isoniazid (INH) and streptomycin (SM) in Mycobacterium tuberculosis.

DESIGN

M. tuberculosis isolates from 171 pulmonary tuberculosis (TB) patients (newly diagnosed 102, 59.6%; retreated 69, 40.3%) were analysed. Drug susceptibility testing was performed using the proportion method and resistant isolates were characterised using the polymerase chain reaction, followed by restriction fragment length polymorphism and/or DNA sequencing, to screen for mutations in rpoB, katG, mabA-inhA and rpsL.

RESULTS

Of the 171 isolates, 16.9% (29/171) were multidrug-resistant. Of the 102 newly diagnosed and 69 retreated cases, respectively 5.9% (6/102) and 33.3% (23/69) were multidrug-resistant. rpoB mutations were found in 100% (31/31) of the RMP-resistant isolates, the most common being S531L in 74.2% (23/31); katG315 mutations were found in 79.6% (35/44) of the INH-resistant isolates; however, no mabA-inhA (-15) mutation was found; rpsL mutations were found in 48.9% (24/49) of the SM-resistant isolates, and codon 43 mutation were found in 42.5% (21/49).

CONCLUSIONS

This study characterises drug resistance-associated mutations in M. tuberculosis, information that could be used for the rapid screening of drug-resistant TB.

Novel inter-hemispheric white matter connectivity in the BTBR mouse model of autism

Alterations in the volume, density, connectivity and functional activation of white matter tracts are reported in some individuals with autism and may contribute to their abnormal behaviors. The BTBR (BTBR T+tf/J) inbred strain of mouse, is used to model facets of autism because they develop low social behaviors, stereotypical and immune changes similar to those found in people with autism. Previously, it was thought a total absence of corpus callosal interhemispheric connective tissues in the BTBR mice may underlie their abnormal behaviors. However, postnatal lesions of the corpus callosum do not precipitate social behavioral problems in other strains of mice suggesting a flaw in this theory. In this study we used digital pathological methods to compare subcortical white matter connective tracts in the BTBR strain of mice with those found in the C57Bl/6 mouse and those reported in a standardized mouse brain atlas. We report, for the first time, a novel connective subcortical interhemispheric bridge of tissue in the posterior, but not anterior, cerebrum of the BTBR mouse. These novel connective tissues are comprised of myelinated fibers, with reduced myelin basic protein levels (MBP) compared to levels in the C57Bl/6 mouse. We used electrophysiological analysis and found increased inter-hemispheric connectivity in the posterior hemispheres of the BTBR strain compared with the anterior hemispheres. The conduction velocity was slower than that reported in normal mice. This study shows there is novel abnormal interhemispheric connectivity in the BTBR strain of mice, which may contribute to their behavioral abnormalities.

A Low Force Valve for Dynamic Control of Molten Plastics in a Mold

Polymer processing has been limited by the lack of direct flow and pressure control of the polymer melt at multiple points in space and time. Improved axial and radial valve designs are discussed that require negligible actuation force to control the flow of the pressurized melt. The forces resulting from pressure loads and shear stresses are first analyzed for an axial valve pin. Subsequently, a radial valve design is implemented and experimentally characterized using neat polycarbonate. A sigmoidal response surface is fit to the experimental data and found to very well model the observed pressure drop as a function of flow rate and valve pin position. The juncture loss at the valve port is then characterized by estimating and removing the pressure drops in the circular flow segments of the valve. Analysis indicated that the juncture loss is inversely proportional to the exposed area, or vesica piscis, formed between the circular flow channel in the valve body and the flow port on the moving valve pin. While applicable to many different polymer processing operations, the validated models are used to show the dynamic valve pin position as a function of the desired flow rate and desired cavity pressure in the hot runner of an injection mold. Finally, the impact of the designs on lower power, more compact mechanical and control system designs are discussed.

Safety and feasibility of adjunctive regadenoson injection at peak exercise during exercise myocardial perfusion imaging: The Both Exercise and Regadenoson Stress Test (BERST) trial

BACKGROUND

The data existing in the literature regarding the safety of using regadenoson with symptom-limited exercise are limited, which motivated the authors to undertake this randomized study.

METHODS

We offered patients scheduled to undergo vasodilator stress nuclear myocardial perfusion imaging the opportunity to exercise instead. Patients who failed to reach target heart rate (THR) were randomized to (1) receive regadenoson at peak exercise or (2) stop exercise and receive regadenoson at rest. Patients who reached THR received a standard Tc-99m sestamibi injection with no regadenoson.

RESULTS

200 patients were included (66% male, mean age 52.5 ± 13.6). 125 patients (62%) reached THR with exercise alone. All stress protocols were well tolerated, and there were no significant adverse events. There were no statistically significant differences in the extent of perfusion abnormalities, image quality, or rate of referral to cardiac catheterization within 60 days between the groups. In fully adjusted logistic regression models, beta-blocker use and diabetes remained significant univariate predictors of failure to reach THR (OR 0.21, 95% CI 0.1-0.5, P < .0001, OR 0.34, 95% CI 0.2-0.7, P = .004, respectively).

CONCLUSIONS

A protocol combining regadenoson at peak exercise in patients unable to reach THR with exercise is feasible, well-tolerated, and yields comparable imaging results to a standard regadenoson injection at rest. In addition, pharmacologic stress testing may be over-ordered in current clinical practice, as patients referred for such testing were often able to exercise.

Tuberculous lymphadenopathy: a multicentre operational study of 6-month thrice weekly directly observed treatment

SETTING

Eight operational locations for the Revised National Tuberculosis Control Programme in six Indian states.

OBJECTIVE

To assess the 6-month efficacy of an intermittent thrice-weekly directly observed treatment (DOT) regimen for tuberculous peripheral adenopathy and the need for prolongation of treatment to 9 months for non-resolution of lymphadenopathy.

DESIGN

Patients aged >5 years with tuberculous lymphadenopathy were included in the study. Patients were evaluated for resolution at repeat visits following treatment. Those with poor resolution at 6 months were randomised to extended treatment up to 9 months or observation without additional treatment.

RESULTS

Resolution of lymphadenopathy was observed at the end of 6 months in 517/551 (93.8%) patients. There was a significant difference in response among patients with and those without the presence of systemic symptoms. There was no association between treatment response and number, size, site, consistency and matting of lymphadenopathy. No differences in response were seen in the remaining 34 patients with or without extended treatment.

CONCLUSION

The operational efficacy of 6-month thrice-weekly DOT for peripheral tubercular lymphadenopathy was satisfactory. There was no evidence of additional benefits of prolonging treatment to 9 months.

Role of surgical staging and adjuvant treatment in uterine serous carcinoma

PURPOSE OF INVESTIGATION

This study evaluates the association of clinical and pathologic characteristics of patients with uterine serous carcinoma (USC) with disease recurrence.

MATERIALS AND METHODS

Surgically-staged patients with USC at a single institution were identified and clinical and pathologic variables were compared.

RESULTS

Of the 51 patients included in this analysis, 75% percent received adjuvant chemotherapy, 51% received radiation therapy, and 47% received both. After a median follow-up of 33 months, 42% of patients had disease recurrence. On multivariable analysis, positive pelvic lymph nodes were associated with a shorter interval between surgery and recurrence: 13.6 months progression-free survival (PFS) with positive vs 17.2 months with negative lymph nodes (p = 0.05). Patients with early-stage disease who did not receive any adjuvant treatments had a significantly greater risk of disease recurrence (44.4% vs 7.70%, p = 0.043).

CONCLUSION

In this population of surgically-staged patients with USC, pelvic lymph node metastases were predictive of a shorter PFS.

Indian study on epidemiology of asthma, respiratory symptoms and chronic bronchitis in adults (INSEARCH)

SETTING

Field sites in 12 districts in different parts of India.

OBJECTIVE

To determine the nationwide population prevalence of and risk factors for asthma and chronic bronchitis (CB) in adults.

DESIGN

A standardised validated questionnaire based on the International Union Against Tuberculosis and Lung Disease's 1984 questionnaire was used to assess asthma and CB prevalence. Multivariate logistic regression analyses were performed to determine the risk factor associations. Estimates standardised to the 2011 population projection estimates for India were used to calculate the national disease burden.

RESULTS

A total of 85,105 men and 84,470 women from 12 urban and 11 rural sites were interviewed. One or more respiratory symptoms were present in 8.5% of individuals. The overall prevalence of asthma and CB was respectively 2.05% (adults aged ≥15 years) and 3.49% (adults aged ≥35 years). Advancing age, smoking, household environmental tobacco smoke exposure, asthma in a first-degree relative, and use of unclean cooking fuels were associated with increased odds of asthma and CB. The national burden of asthma and CB was estimated at respectively 17.23 and 14.84 million.

CONCLUSION

Asthma and CB in adults pose an enormous health care burden in India. Most of the associated risk factors are preventable.

Regulation of metabolic pathways in liver and kidney during experimental diabetes: Effects of antidiabetic compounds

Diabetes has been classified as a disease of glucose overproduction by tissues, mainly liver and glucose underutilization by insulin requiring tissues like liver, adipose and muscle due to lack of insulin. There is, however, glucose over utilization in tissues not dependent on insulin for glucose transport like kidney, nerve and brain. There are serious complications due to this excess glucose in these tissues and their reversal is important for a good metabolic control and normalisation of other parameters. Insulin, trace metals and some plant extracts have been used to see the reversal effects of the complications of diabetes in liver and kidney in experimental diabetes. Almost complete reversal of the metabolic changes has been achieved in the activities of key enzymes of metabolic pathways in liver and kidney and an effective glucose control has been achieved suggesting a combination of therapies in the treatment of metabolic disturbance of the diabetic state.

Giant vesical calculus with carcinoma bladder: A rare entity

A 60 year old male attended with history of dribbling of urine for one year along with frequent passing of urine at night for last 15-20 days. Rectal examination showed suggesting of 2 grad prostrate enlargement. Ultrasound shows vesicle calculus with no prostrate enlargement. At cystolithotomy, calculus (10x8x5cm) was noted. Histopathology shows keratinising squamous cell carcinoma. Postoperatively radiotherapy was done. Vesico cutaneous fistula was developed that healed subsequently. Journal of College of Medical Sciences-Nepal,2011,Vol-6,No-4, 61-63 DOI: http://dx.doi.org/10.3126/jcmsn.v6i4.6730

Rapid detection of rifampicin, isoniazid and streptomycin resistance in Mycobacterium tuberculosis clinical isolates by high-resolution melting curve analysis

AIMS

This study was carried out to evaluate high-resolution melting (HRM) curve analysis assay for detection of mutations in three drug resistance-associated genes of Mycobacterium tuberculosis.

METHODS AND RESULTS

Clinical isolates of Myco. tuberculosis phenotypically resistant to rifampicin (n = 29), isoniazid (n = 35) and streptomycin (n = 34) were analysed for mutations in rpoB, katG and rpsL genes, respectively, by HRM curve analysis and DNA sequencing. HRM curve assay resulted in 11 clearly distinguishable melt curves denoting eight types of mutations responsible for drug resistance. For the three drugs, respectively, the sensitivity of HRM curve assay was found to be 93·1, 80 and 61·8% compared to the phenotypic resistance patterns, and 93·1, 93·3 and 100% in comparison with the DNA sequencing.

CONCLUSIONS

The sensitivity and specificity of HRM curve assay was found to be comparable to DNA sequencing. The assay offers the advantage of high throughput, single step, rapid work flow and cost effectiveness and can be utilized as a rapid screening method for detection of drug-resistant tuberculosis.

SIGNIFICANCE AND IMPACT OF THE STUDY

HRM curve assay may prove to be an important tool for the development of rapid molecular diagnostic assays for detection of mutation-based drug resistance.

Global guidelines for treatment of tuberculosis among persons living with HIV: unresolved issues

The Revised National Tuberculosis Control Programme (RNTCP) in India uses a fully intermittent thrice-weekly rifampicin-containing regimen for all tuberculosis (TB) patients, including those who are human immunodeficiency virus (HIV) infected, whereas the World Health Organization (WHO) recommends daily anti-tuberculosis treatment at least during the intensive phase. The WHO recommendation was based on the results of a meta-analysis demonstrating increased risk of recurrence and failure among HIV-infected TB patients receiving intermittent TB treatment compared to a daily regimen. Review of the primary evidence indicates limited, low-quality information on intermittency, mostly from observational studies in the pre-antiretroviral treatment (ART) era. Molecular epidemiology in India indicates that most of the recurrences and many of the failures result from exogenous re-infection, suggesting poor infection control and high transmission rather than poor regimen efficacy. Subsequently published studies have shown acceptable treatment outcomes among HIV-infected TB patients receiving intermittent anti-tuberculosis regimens with concomitant ART. Treatment outcomes among HIV-infected TB patients treated under programmatic conditions show low failure rates but high case fatality; death has been associated with lack of ART. The highest priority is therefore to reduce mortality by linking all HIV-infected TB patients to ART. While urgently seeking to reduce death rates among HIV-infected TB patients, given the poor evidence for change and operational advantages of an intermittent regimen, the RNTCP intends to collect the necessary evidence to inform national policy decisions through randomised clinical trials.

Field reversed configuration confinement enhancement through edge biasing and neutral beam injection

Field reversed configurations (FRCs) with high confinement are obtained in the C-2 device by combining plasma gun edge biasing and neutral beam injection. The plasma gun creates an inward radial electric field that counters the usual FRC spin-up. The n = 2 rotational instability is stabilized without applying quadrupole magnetic fields. The FRCs are nearly axisymmetric, which enables fast ion confinement. The plasma gun also produces E × B shear in the FRC edge layer, which may explain the observed improved particle transport. The FRC confinement times are improved by factors 2 to 4, and the plasma lifetimes are extended from 1 to up to 4 ms.

Clinical and pathological response rates of docetaxel-based neoadjuvant chemotherapy in locally advanced breast cancer and comparison with anthracycline-based chemotherapies: eight-year experience from single centre

INTRODUCTION

The administration of neoadjuvant chemotherapy (NACT) prior to local therapy is advantageous for women with locally advanced breast cancer (LABC), since it can render inoperable tumors resectable and can increase rates of breast conservative surgeries.

MATERIALS AND METHODS

We retrospectively analyzed LABC patients who received NACT from January 2000 to December 2007. Out of 3000 case records screened, 570 (19%) were LABC and 110/570 (19%) treatment-naïve patients started on NACT were analyzed. Ninety-one (37 docetaxel [D], 54 anthracycline [A]) patients were eligible for response and survival analysis. Pathological complete remission (pCR) was defined as no evidence of malignancy in both breast and axilla.

RESULTS

Median age of the whole cohort was 45 years (range 25-68 years). Premenopausal were 42% and estrogen receptor + 49.5%. Most (90%) were T4 tumors and 70% were Stage IIIB. Median numbers of preoperative cycles were six and three in the D and A group respectively. Overall clinical response rates for breast primary were 74.3% and 53.7% (CR 28.6% vs. 16.7%, P=0.58) while for axilla ORR were 75.7% vs. 54.8% (51.4% vs. 40.4% CR, P=0.77) respectively for D and A. Corresponding pCR rates were 19% vs. 13% respectively. There was no significant difference in disease-free (three-year 56.84% vs. 61.16%, P=0.80) and overall survival (three-year 70% vs. 78.5%, P=0.86) between the two groups.

CONCLUSIONS

Although pCR rates were higher with docetaxel-based NACT, it did not translate into superior disease-free survival / overall survival compared to anthracycline-based chemotherapies.

Genetic polymorphisms in the P2X7 gene and its association with susceptibility to tuberculosis

BACKGROUND

Several studies have reported the influence of genetic variations on susceptibility to tuberculosis (TB). Polymorphism in P2X7 gene coding for P2X7 receptor present on macrophages has been linked to TB in different populations.

OBJECTIVE

To assess the role of P2X7 gene -762T/C and -1513A/C polymorphisms in TB susceptibility.

DESIGN

In a case-control study, polymerase chain reaction (PCR) amplification of genomic DNA extracted from peripheral blood samples of cases and controls was followed by restriction fragment length polymorphism or allele-specific PCR.

RESULTS

The 1513C allele was found to be associated with TB susceptibility (P = 0.02, OR for variant C allele 1.33, 95%CI 1.03-1.73). A significant protective association against TB was found for -762T/C polymorphism (P < 0.01, OR for variant C allele 0.72, 95%CI 0.57-0.91). On classifying samples on the basis of sex, only males showed a significant association between P2X7 -1513A/C and P2X7 -762T/C and TB in the present study.

CONCLUSION

A significant association of 762T/C and 1513A/C polymorphisms with TB in the P2X7 gene was found in our study population. A sex bias, with only males showing a significant association with the disease, is the first report of this kind. Genetic studies for the characterisation of the susceptibility genes can help to gain a better understanding of TB pathogenesis.

Bronchoscopic management of a rare benign endobronchial tumor

Benign endobronchial tumors are uncommon. Bronchoscopic removal is the preferred modality of treatment although surgery may be required in some cases. Rigid bronchoscopy is usually recommended in the management of these tumors. However, flexible bronchoscopy is also used in many centers. We present a case of endobronchial lipoma, where an unusual complication during flexible bronchoscopic resection using snare forceps necessitated urgent rigid bronchoscopy. This case highlights the importance of rigid bronchoscopy in the management of endobronchial tumors. We believe that with a large benign endobronchial tumor in tracheal or main-stem bronchus, physicians should initially employ rigid bronchoscopy, switching to flexible if more peripheral treatment is required.

Tuberculous osteomyelitis of mandibular condyle: a diagnostic dilemma

The incidence of tuberculosis (TB) is increasing worldwide and so are its consequences. Its oral manifestations are infrequent, occurring in approximately 3% of all cases. Although the primary lesion occurs as a pulmonary infection, the extrapulmonary infections have also shown an increase over the past few years. These infections generally involve the head and neck through haematogenous or lymphatic routes. The clinical presentation may be as an ulcer, granuloma, orofacial TB, TB of the salivary glands or tuberculous lymphadenitis. Rarely, secondary oral manifestations associated with pulmonary infection are seen, which can appear as lesions on the gingiva, palate, lips, tongue, buccal mucosa, frenulum and in the jaw bones. Owing to the rarity of orofacial TB, it seldom arouses clinical suspicion, especially when a positive history of a systemic infection or therapy is denied. Tuberculous involvement of the mandibular condyle is even rarer, and only two such cases are reported so far, both in English-language literature. Further, the diagnosis of such a case is extremely difficult as there are no specific signs pathogonomic of infection. The only manifestation may be a localized painful swelling of the jaw. The presented case is of osteomyelitis of the mandibular condyle in a 20-year-old male patient in whom TB was later suspected. In this case report the role of diagnostic techniques is emphasized as the osteomyelitis of the condyle has the risk of being easily missed owing to its atypical signs and symptoms and atypical radiographic appearance.

Association of mannose-binding lectin gene polymorphism with tuberculosis susceptibility and sputum conversion time

Mannose-binding lectin (MBL) plays an important role in innate immunity. The effect of low MBL levels producing variants of MBL2 gene on tuberculosis (TB) has been controversial with some studies reporting it to confer protection against the disease, whereas others estimating a susceptibility relation. Other than conducting a case-control study to evaluate the role of MBL A/B polymorphism on TB, we conducted a longitudinal study to check whether this MBL variant can influence the host response to Mycobacterium tuberculosis infection. A total of 357 TB patients (286 pulmonary TB, 71 extrapulmonary (EP) TB) and 392 healthy controls belonging to same ethnicity were included in the study. We found the mutant allele 'B' allele confers a protective role against TB in our study population. This effect was absent in EP patients. On stratification on the basis of sex, the protective role of the 'B' allele was found to be limited to females only and males reported no significant difference. No effect of MBL A/B polymorphism on sputum conversion time was reported. We conclude that MBL 'B' allele is associated with protection against TB, but no influence was found on sputum conversion rate.

Interferon gamma release assay (QuantiFERON-TB Gold In Tube) in patients of sarcoidosis from a population with high prevalence of tuberculosis infection

BACKGROUND AND OBJECTIVE

Detecting latent tubercular infection (LTBI) in sarcoidosis has important treatment implications. Traditionally tuberculin skin test (TST) is relied upon for this purpose. However, sarcoidosis is known to produce tuberculin anergy, which is not affected by high prevalence of tuberculosis (TB) infection. Interferon gamma release assays (IGRAs) have a higher sensitivity and specificity for detecting Mycobacterium tuberculosis (MTB) infection than the conventional TST as they utilize antigens specific for MTB complex. However, there is limited data regarding the performance of these tests in sarcoidosis, particularly in a setting of high population prevalence of LTBI. Herein, we studied the utility of IGRAs in the diagnostic work up of patients with sarcoidosis.

PATIENTS AND METHODS

Prospectively enrolled, biopsy-confirmed, glucocorticoid naive cases of pulmonary sarcoidosis; pulmonary and extrapulmonary TB; and, healthy controls underwent TST using 0.1 mL (1 tuberculin unit) of purified protein derivative RT23, and IGRA using QuantiFERON-TB-Gold In Tube assay (QFT) in blood. For TST an induration > or =10 mm was taken as positive. QFT was performed and interpreted as per the manufacturer's instructions.

RESULTS

We studied 38 patients with sarcoidosis (22 men, 16 women; mean age 42.5 years), 30 patients of TB (18 pulmonary, 12 extrapulmonary) and 30 healthy controls. Patients with sarcoidosis were more likely to have a negative TST compared to healthy controls (89.5% vs. 60%, p = 0.004) or TB (89.5% vs. 23.3%, p < 0.001). However, QFT positivity was not significantly different in sarcoidosis compared to controls (34.2% vs. 50%, p = 0.19), but was higher in TB patients as compared to sarcoidosis (60% vs. 34.2%, p = 0.03).

CONCLUSIONS

There is anergy to tuberculin in sarcoidosis. However, the results of QFT are not similarly affected. QFT continues to remain positive in many patients with sarcoidosis, and thus may be more accurate to detect LTBI in these patients.

Weaning by gradual pressure support (PS) reduction without an initial spontaneous breathing trial (SBT) versus PS-supported SBT: a pilot study

BACKGROUND AND AIM

Studies on weaning strategies have yielded conflicting results regarding the superiority of different methods. The aim of this RCT was to compare the efficacy of gradual pressure support (PS) reduction without an initial spontaneous breathing trial (SBT) with PS-supported SBT.

METHODS

Patients mechanically ventilated for >24h were randomized to weaning by gradual reduction of PS without an initial SBT versus once daily SBT (PS 7cm H(2)O). The primary outcomes were the rates of successful weaning trial and time to successful extubation. The secondary outcomes were the ICU and hospital length of stay, hospital mortality and the occurrence of ventilator-associated pneumonia (VAP).

RESULTS

Of the 120 patients (61 males, median age 35 years), 58 were assigned to PS and 62 to the SBT group. The median (IQR) duration of ventilation prior to weaning was 80.2 (50.5-175.6)h. The baseline characteristics were similar in the two groups except the PaO(2)/FiO(2) ratio, which was significantly higher in SBT group. The rates of successful weaning trial (89.7% versus 69.4%) were significantly higher in the PS group. The median duration of weaning (66h versus 81.5h, P=0.05) and the median duration of ICU stay (8 days versus 9.4 days, P=0.027) were lower in the PS group. There was no difference in hospital stay, mortality rates or occurrence of VAP in the two arms. On multivariate analysis, the duration of ventilation prior to weaning, baseline SOFA score and the weaning method were predictors of successful extubation.

CONCLUSIONS

Gradual reduction of PS without an initial SBT was found to be associated with better outcomes compared to once daily PS-supported SBT.

Trans-scleral dye injection during vitreous surgery to identify clinically undetectable retinal breaks causing retinal detachment

BACKGROUND/AIMS

Finding all retinal breaks is a critical step in rhegmatogenous retinal detachment (RRD) surgery in order to prevent persistent/recurrent retinal detachment (RD). We describe a technique of trans-scleral dye injection into the subretinal fluid under the detached retina in the context of recurrent/persistent RD in vitrectomized eyes, in order to determine the location of clinically unidentified (occult) retinal breaks causing RD.

METHODS

Retrospective consecutive single-surgeon case-series analysis of patients presenting with a repeat RRD after having been treated with pars plana vitrectomy (PPV) as the method of primary RRD repair. Trans-scleral injection of subretinal vision blue (TSVB) was used to help identify retinal breaks during repeat vitrectomy.

OUTCOME MEASURES

successful detection of a break; location of breaks; persistent retinal attachment; final visual acuity (VA); complications.

RESULTS

There were 395 cases of RRD during the 3-year period reviewed. TSVB was used for eight instances in seven eyes. All eight instances were repeat RRD. TSVB facilitated occult break detection in 7/8 instances of use. Breaks were at or adjacent to the previous cryo site in three instances. Persistent retinal attachment was achieved in 5/7 cases. Final VA increased in 5/7 cases. There was no evidence of complications as a result of TSVB injection.

CONCLUSIONS

TSVB coupled with indentation to vent a plume of dye through an occult break during vitreous surgery is a relatively simple technique that may facilitate the identification of occult retinal breaks and help achieve anatomical success and functional success.

Vitamin B12 deficiency presenting as pyrexia

Vitamin B12 deficiency is an uncommon cause of pyrexia. We report the case of a patient who presented with pyrexia and anaemia, which after exclusion of infective, inflammatory or endocrine causes was attributed to megaloblastic anaemia secondary to vitamin B12 deficiency. The patient's fever responded to treatment of vitamin B12 deficiency.

In vitro antioxidant activity of extracts from the leaves of Abies pindrow Royle

Traditionally, the leaves of Abies pindrow Royle are employed as an ayurvedic remedy for fever, hypoglycaemic, respiratory and inflammatory conditions. In this study, dichloromethane, methanol and acetone extracts of A. pindrow leaves were analysed for their phytochemical content and in vitro antioxidant activities. The methanol extract exhibited highest antioxidant activity while acetone extract showed presence of relatively high total phenol and flavonoids contents. The present study provides evidence that extracts of Abies pindrow leaves are a potential source of natural antioxidants and could serve as a base for future drugs.

Initial experience of endobronchial silicon stents from a tertiary care centre in North India

BACKGROUND

Central airway obstruction (CAO) is defined as obstruction of trachea and principal bronchi. Therapeutic rigid bronchoscopy with tracheobronchial stenting using silicon stents is a well established procedure in the management of such conditions. However, there is limited experience with this technique in India.

METHODS

Between January 2010 and April 2010, Dumon stents were placed in four patients with CAO. Three patients had symptomatic tracheal stenosis while one patient had malignant obstruction at the carina. Rigid bronchoscopy under general anaesthesia was performed to relieve the CAO followed by placement of silicon stents. Pre- and post-stent placement symptom assessment was performed with a symptom-based visual analogue scale.

RESULTS

Four patients underwent silicon stent placement in the tracheobronchial tree. Three patients had benign post-intubation tracheal stenosis and one had malignant tracheal obstruction at carina due to endobronchial growth. Significant improvement was achieved in all patients. There were no significant complications.

CONCLUSIONS

Rigid bronchoscopy with silicon stent placement is an effective and suitable method of relieving the distressing symptoms due to benign or malignant airway obstruction.

Immune responses to mycobacterial antigens in sarcoidosis: a systematic review

From the time sarcoidosis has been described, there has always been a viewpoint that the disease is in some way related to tuberculosis (TB). Sarcoidosis is a granulomatous disease, which is likely a result of continued presentation of a poorly degradable antigen. Mycobacterium tuberculosis has been a very strong contender for this antigen. Besides the molecular studies demonstrating mycobacterial deoxyribonucleic acid (DNA) in the sarcoid tissue, assessment of immune responses against mycobacterial antigens provides a useful tool to study the role of mycobacteria in the pathogenesis of sarcoidosis. We reviewed the studies focussing on T-cell and B-cell responses to tubercular antigens in patients with sarcoidosis. Pooled data from various studies does provide a suggestive, though not unequivocal evidence in favour of mycobacteria as a cause of sarcoidosis. These findings not only reinforce the possible pathogenic role of mycobacterial antigens in sarcoidosis, but at the same time also limit the clinical utility of molecular and serological studies based on mycobacterial antigens in the differential diagnosis of TB from sarcoidosis, particularly in a country with high endemicity for TB.