FROM Qutn TO Bt COTTON: DEVELOPMENT, ADOPTION AND PROSPECTS. A REVIEW

Cotton has unique history of domestication, diversification, and utilization. Globally it is an important cash crop that provides raw material for textile industry. The story of cotton started from human civilization and the climax arrived with the efforts of developing transgenic cotton for various traits. Though conventional breeding brought steady improvement in developing resistance against biotic stresses but recent success story of gene transferfrom Bacillus thuringiensis into cotton showed game changing effects on cotton cultivation. Amongst various families of insecticidal proteins Bt Cry-toxins received more attention because of specificity against receptors on the cell membranes of insect midgut epithelial cells. Rapid Bt cotton adoption by farmers due to its economic and environmental benefits has changed the landscape of cotton cultivation in many countries. But the variable expression of Bt transgene in the newly developed Bt cotton genotypes in tropical environment is questionable. Variability of toxin level in different plant parts at various life stage of plant is an outcome of genotypic interaction with environmental factors. Temporal gene expression of Cry1Ac is also blamed for the epigenetic background in which transgene has been inserted. The presence of genotypes with sub-lethal level of Bt toxin might create resistance in Lepidopteron insects, limiting the use of Bt cotton in future, with the opportunityfor other resistance development strategies to get more attention like gene stacking. Until the farmers get access to more recent technology, best option is to delay the development of resistance by applying Insect Resistance Management (IRM) strategies.

Development and in-vitro Evaluation of Once Daily Tablet Dosage Form of Loxoprofen Sodium

Purpose: To formulate and characterize once daily controlled release tablet of loxoprofen sodium.Methods: Eudragit RS-100, hydroxylpropyl methylcellulose (HPMC) and pectin were used as release retarding polymers. All the formulations were prepared by direct compression method. Various precompression studies were carried out to determine Hausner’s ratio, Carr’s index, angle of repose, bulk density and tapped density Differential scanning calorimetry (DSC) studies and also post-compression studies to evaluate hardness, friability, weight variation, drug content, in-vitro drug release were conducted on the tablets. The drug release data were subjected to kinetic models, including zero order, first order, Hixon Crowell, Higuchi and Korsmeyer-Peppas.Results: Compressibility index (7.6 ± 1.32 - 12.5 ± 1.43%), Hausner’s ratio (1.08 ± 0.04 - 1.14 ± 0.03), angle of repose (27.78 ± 0.47 - 30.49 ± 0.46°), hardness (6.25 ± 0.27 - 7.21±0.21 kg/cm2), friability (0.14 ± 0.06 - 0.28 ± 0.0 %), weight variation (249.5 ± 2.09 - 251.35 ± 2.41 mg) and drug content  (97.30 ± 0.28 - 103.70 ± 0.31 %) were within generally accepted limits for the pre-and post-compression formulations, respectively. The tablets having the maximum amount of among the three polymers tested as matrix materials, HPMC, represented by F3 tablets, exerted better sustained release properties after 12 h. Release pattern was more of Fickian diffusion followed by Higuchi mechanism.Conclusion: The release of the loxoprofen sodium was optimized up to 12 h.Keywords: Loxoprofen, Sustained release, hydroxypropyl methylcelluose, Pectin, Eudragit, Matrix tablets

Prediction of Risk Factors of Frequent Relapse Idiopathic Nephrotic Syndrome

This case control study was aimed to identify the predictive risk factors for frequent relapse idiopathic nephrotic syndrome (INS) and conducted in Sir Salimullah Medical College & Mitford Hospital, Dhaka and at Renal and Dialysis Unit of Dhaka Shishu Hospital and Bangladesh Institute of Child Health (BICH), Dhaka, from January 2006 to December 2006. We examined retrospectively the clinical course of fifty cases of frequent relapse nephrotic syndrome (FRNS) as cases and fifty cases of infrequent relapse nephrotic syndrome (IRNS) as control who met the predefined enrollment criteria, followed for at least one year after initial onset of disease. After enrollment following parameters were studied as predictors of frequent relapse: i) Socio-demographic variables: age, sex, socio-economic condition, number of living room ii) Disease related variables i.e. age of onset, duration of illness, frequency of relapse within the 1st year, regimen of initial steroid therapy, total cumulative dose of steroid for remission, day of remission after starting steroid, association with atopy and infection, concomitant upper respiratory illness iii) Biochemical and pathological variables (at the time of initial attack) i.e. Serum albumin, serum cholesterol, blood urea, 24 hours urinary protein, serum creatinine, complete blood count, urine RBC, urine pus cell, urine culture. The test statistics used to analyses the data were descriptive statistics, Chi-square probability test, Student's t-test and Binary logistic regression analysis for Odds ratio. Both univariate and multivariate logistic regression analysis revealed that age of onset (P<0.001, OR=0.9, 95% CI=0.85-0.95), poor socioeconomic status (P<0.034, OR=0.5.8, 95% CI=1.14-29.5) and low serum albumin level at the time of initial presentation (P<0.022, OR=0.8, 95% CI=0.65-0.97) were independent predictors of frequent relapse nephrotic syndrome. In conclusion, we demonstrated that age at onset, poor socioeconomic condition and low serum albumin level at the time of initial attack is independent risk factors for frequent relapse idiopathic nephrotic children. This information can be used as a predictor of FRNS.

Fluoroscopically guided balloon dilatation for the treatment of achalasia: long-term outcomes

To report the immediate and long-term outcomes following the fluoroscopically guided balloon dilatations performed in our department for the treatment of achalasia. We reviewed retrospectively all patients that underwent a fluoroscopically guided balloon dilatation because of achalasia in our department between April 2007 and September 2010. The follow-up was performed by interviews and/or investigation of the patient's medical and imaging records. The primary endpoints of the study were technical success, clinical success, major complication rates, and repeat dilatation rates because of recurrence of clinical symptomatology. Secondary endpoints were the rate of minor complications and the dilatation-free interval. Various parameters that could affect the clinical outcome were also analyzed. Thirty-nine consecutive patients (20 female) with a mean age 44 ± 17 years underwent 69 dilatations, while 10/39 (25.6%) patients had a history of a previous laparoscopic myotomy. The most common symptom was dysphagia (64/69, 92.7%), while regurgitation and/or retrosternal pain were present in 12/39 (30.7%) and 9/39 (23%) of the cases, respectively. Technical success was achieved in 98.5% (68/69). There were no procedure-related major complications. The mean balloon diameter used was 30 ± 3.9 mm, and the mean period of follow-up was 27.7 ± 16.0 months. Excellent or good initial responses were noted in 54/66 cases (81.8%). A repeated dilatation to deal with recurrence of symptoms was performed in 69.4% of the cases (25/36). In the majority of the cases, two dilatations were needed in order to achieve long-term relief from symptoms. A dilatation-free interval of 4 years was observed in 26.4%. Clinical success was achieved in 30/36 patients (83.3%). Subgroup analysis did not detect significantly different recurrence rates in patients with and without previous laparoscopic myotomy (50% vs. 69% respectively), those of young age (75% < 21 years vs. 68.8% > 21 years), and male gender (71.4% male vs. 55.0% females). The high redilatation rate was attributed to the utilization of smaller balloons by less experienced operators. Fluoroscopically guided balloon dilatation is a safe and effective method for the treatment of achalasia. Young age and prior Heller's laparoscopic myotomy were not associated with increased rates of recurrence rate or clinical failure.

Introgression of cotton leaf curl virus-resistant genes from Asiatic cotton (Gossypium arboreum) into upland cotton (G. hirsutum)

Cotton is under the constant threat of leaf curl virus, which is a major constraint for successful production of cotton in the Pakistan. A total of 3338 cotton genotypes belonging to different research stations were screened, but none were found to be resistant against the Burewala strain of cotton leaf curl virus (CLCuV). We explored the possibility of transferring virus-resistant genes from Gossypium arboreum (2n = 26) into G. hirsutum (2n = 52) through conventional breeding techniques. Hybridization was done manually between an artificial autotetraploid of G. arboreum and an allotetraploid G. hirsutum, under field conditions. Boll shedding was controlled by application of exogenous hormones, 50 mg/L gibberellic acid and 100 mg/L naphthalene acetic acid. Percentage pollen viability in F(1) hybrids was 1.90% in 2(G. arboreum) x G. hirsutum and 2.38% in G. hirsutum x G. arboreum. Cytological studies of young buds taken from the F(1) hybrids confirmed that they all were sterile. Resistance against CLCuV in the F(1) hybrids was assessed through grafting, using the hybrid plant as the scion; the stock was a virus susceptible cotton plant, tested under field and greenhouse conditions. All F(1) cotton hybrids showed resistance against CLCuV, indicating that it is possible to transfer resistant genes from the autotetraploid of the diploid donor specie G. arboreum into allotetraploid G. hirsutum through conventional breeding, and durable resistance against CLCuV can then be deployed in the field.

Relationship between serum IgE and frequent relapse idiopathic nephrotic syndrome

This prospective case control study was carried out in Renal and Dialysis Unit of Dhaka Shishu Hospital, Bangladesh from January 2004 to December 2004 to determine serum IgE level in frequent relapse Idiopathic nephrotic syndrome and to evaluate any role of IgE in the rate of relapse. Thirty cases of frequent relapse (FR) Idiopathic nephrotic syndrome (INS) were considered as cases and thirty cases of infrequent relapse nephrotic syndrome (IRNS) were considered as control. Serum IgE level was measured in all patients at the time of relapse and again four weeks after steroid treatment when patient was in remission. The test statistics used to analyses the data were descriptive statistics, Chi-square probability test, Student's "t"-Test, Mann Whitney test and Wilcoxon Signed Rank test. Majority of the patients' age in both the groups was between 2-6 years. The male female ratio in FR group was 2:1, while that in IR group was 3:2. Forty percent of the frequent relapsers and 30% of infrequent relapsers were found to possess the history of atopy. However, the difference between the two groups was not statistically significant (p>0.05). The mean serum albumin in FR was observed to be significantly lower (13.73±0.59 gm/L) than that in IR (15.73±0.67 gm/L) (p<0.05). Mean serum IgE at the time of relapse in FR (1791±95 IU/mL) was found to be more than 3 times higher than that in IR (560±50 IU/mL) (p<0.001). Serum IgE level at the time of remission has decreased to almost normal in IR group (204±21 IU/mL) but it was still found 5 times higher in FR group (1086±79 IU/mL) (p<0.001). Serum IgE level is high in both FR and IR groups of nephrotic syndrome at the time of relapse. It reverts back to normal in IRNS but persistently and significantly high in FR group in both relapse and remission. Level of the serum IgE can be used as a predictor of FRNS.

Evaluation of a new quality assessment strategy for blinded rechecking of random sputum smears for TB in Delhi, India

This study was conducted at the New Delhi Tuberculosis Center, Delhi, India, from 1 January 2006 to 31 December 2007 to assess the feasibility of implementing random blinded rechecking (RBRC), a quality assurance strategy, and its impact on the performance of tuberculosis smear microscopy in Delhi, RBRC activities are carried out monthly at District Tuberculosis Centers (DTCs). Forty thousand five hundred and six slides were rechecked during the study period. RBRC, as a method of quality assurance was found to be feasible for a large application. The quality of sputum microscopy improved, with a significant reduction in the number of false positive and false negative errors in 2007 compared to 2006. The number of microscopy centers reporting high false errors decreased significantly in 2007.

Prevalence of multidrug-resistant tuberculosis among category II pulmonary tuberculosis patients

BACKGROUND & OBJECTIVES

Multidrug-resistant tuberculosis (MDR-TB) has emerged as a significant global health concern. The most important risk factor for the development of MDR-TB is previous anti-tuberculosis therapy. Category II pulmonary TB includes those patients who had failed previous TB treatment, relapsed after treatment, or defaulted during previous treatment. We carried out this study to ascertain the prevalence of MDR-TB among category II pulmonary TB patients.

METHODS

This was a cross-sectional, descriptive study involving category II pulmonary TB patients diagnosed between 2005 and 2008. All sputum-positive category II TB cases were subjected to mycobacterial culture and drug-susceptibility testing (DST). MDR-TB was defined as TB caused by bacilli showing resistance to at least isoniazid and rifampicin.

RESULTS

A total of 196 cases of sputum-positive category II pulmonary tuberculosis patients were included. Of these, 40 patients (20.4%) had MDR-TB. The mean age of MDR-TB patients was 33.25 ± 12.04 yr; 9 patients (22.5%) were female. Thirty six patients showed resistance to rifampicin and isoniazid; while 4 patients showed resistance to rifampicin, isoniazid and streptomycin. The prevalence of MDR-TB among category-II pulmonary tuberculosis patients was 20.4 per cent.

INTERPRETATION & CONCLUSIONS

The prevalence of MDR-TB in category II TB patients was significant. However, nation-wide and State-wide representative data on prevalence of MDR-TB are lacking. We stress the importance of continuous monitoring of drug resistance trends, in order to assess the efficacy of current interventions and their impact on the TB epidemic.

Emergence of high-level fluoroquinolone-resistant Escherichia coli in Bangladesh

Fifteen fluoroquinolone-resistant strains of Escherichia coli were isolated from different clinical specimens of paediatric patients, 2 years after introduction of the drugs into Bangladesh. However, none of these patients had any definite history of treatment with fluoroquinolones. MICs of these strains to different antibiotics were determined by the broth microdilution method recommended by the Working Party of BSAC. Strains were highly resistant to all drugs except ceftriaxone. Study indicates a high frequency of fluoroquinolone-resistant E. coli strains among the clinical isolates which is possibly related to fluoroquinolone introduction.

Study of different methods of susceptibility testing of M. tuberculosis

This communication is on a multi-centre collaborative study carried out by New Delhi Tuberculosis (NDTB) Centre, Delhi, to compare the different methods of drug susceptibility testing (DST) of Mycobacterium tuberculosis for Streptomycin, Rifampicin, Isoniazid and Ethambutol in various accredited laboratories 40 samples (selected by simple random sampling technique) from sputum positive out-patients presenting between December 2004 and January 2005 were collected at New Delhi Tuberculosis Centre from 24 males and 16 females (age ranging from 18 to 55 years) were taken up for culture and susceptibility testing. The proportion method of DST done at NDTB Centre was taken as standard for comparing the other methods after it was found to have a good agreement with the proportion method performed at Tuberculosis Research Centre, Chennai (Kappa coefficient 0.75 to 1). All 40 sub-cultures were processed for DST by the resistance ratio and proportion methods at NDTB Centre. Also, the 40 sub-cultures were sent to Central JALMA Institute for Leprosy (JALMA), Agra that used the resistance ratio method and 25 sub-cultures were transported to National Institute of Communicable Diseases (NICD), Delhi for performing the Bactec 460TB method. The resistance ratio and proportion methods were compared both intra-laboratory (NDTB Centre) and inter-laboratory (NDTB Centre and JALMA). The sensitivity and specificity of the resistance ratio method compared to the proportion method both inter and intra-laboratory, were very high for all the drugs (except Ethambutol inter-laboratory). This was corroborated by the good agreement between the resistance ratio performed at the two centres. Bactec 460TB method, on the other hand, did not have acceptable measures of validity (sensitivity and specificity) compared to the proportion method for Streptomycin and Ethambutol. Both resistance ratio method & proportion method are comparable and either can be used for making clinical decisions. But Bactec 460 method, despite yielding early results loses out on validity.

Efficacy of repeat sputum examination in RNTCP

BACKGROUND

The guidelines of repeat sputum smear examination in initial smear negative patients (ISN), who also fail the antibiotic trial of three samples have been incorporated in the RNTCP diagnostic algorithm in India in 2005. This study was conducted to assess the utility of repeat sputum smear examination in symptomatic initial smear negative patients to detect new smear positives in the state of Delhi.

MATERIAL AND METHODS

The monthly records of the laboratory abstracts for the six quarters for all the 24 districts of Delhi were analysed w.e.f. first of January 2006 to 30th June 2007.

RESULTS

A total of 243,244 TB suspects were examined for diagnosis during the six quarters w.e.f. January 2006. Of these, 37,666 were found positive on sputum smear microscopy giving a positivity rate of 15.4%. During the same period, a total of 2,195 (1% of ISN ) TB suspects underwent repeat sputum examination, of which 272 were found positive giving a mean positivity of 12.3%.

CONCLUSION

A significant number of apparently smear negative TB cases may in fact be smear positive due to various reasons and can be detected by a simple repeat sputum examination. Yield of sputum positive cases in sputum reexamination is almost the same as in initial sputum examination i.e. 10-15%. Therefore, the policy of repeat sputum examination in symptomatic initial sputum negative cases failing the antibiotic trial should be meticulously followed as advocated in the RNTCP diagnostic algorithm.

Acquired drug resistance pattern in tuberculosis cases at the State Tuberculosis Centre, Delhi, India

SETTING

State TB Demonstration Centre, Delhi, India.

OBJECTIVE

To obtain a baseline estimate of the prevalence of multidrug-resistant tuberculosis (MDR-TB) among previously treated tuberculosis (TB) cases at the State Tuberculosis Centre in 2006.

DESIGN

A retrospective study. Drug susceptibility data of 5252 previously treated patients tested at this centre were analysed.

RESULTS

Of 2880 Mycobacterium tuberculosis isolates from previously treated cases, 1498 (52%) were resistant to one or more anti-tuberculosis drugs, of which 47.1% were MDR. Resistance to isoniazid was observed in all resistant isolates, followed by resistance to rifampicin in 1357 (47.1%), streptomycin in 403 (14.2%) and ethambutol in 107 (3.72%). A significantly higher rate of resistance, including MDR, was observed among treatment failures compared to relapses and defaulters.

CONCLUSION

A very high proportion of drug-resistant cases had MDR besides resistance to two or more drugs. This proportion was significantly higher among treatment failures compared to relapses and treatment after default cases, underlining the need for early identification of treatment failure by early referral for culture and drug susceptibility testing, and initiation of appropriate treatment.

Outcome of multi-drug resistant tuberculosis cases treated by individualized regimens at a tertiary level clinic

AIM

To determine the clinical, radiological and drug resistance profile as well as the factors associated with treatment outcome of Multi-Drug Resistant Tuberculosis (MDR-TB).

MATERIAL AND METHODS

All newly diagnosed patients with pulmonary MDR-TB from August 2002 to December 2004 enrolled at New Delhi Tuberculosis Centre, were included in the study. They were followed up clinically, radiologically and bacteriologically by sputum smear, culture and Drug Susceptibility Testing (DST) at regular intervals. According to their DST pattern and previous history of Anti-Tubercular Treatment (ATT), individualized treatment regimens were tailored for each patient.

RESULTS

Out of total 27 bacteriologically proven cases of MDR-TB included in this study, 19 were males (mean age and weight 38.5 years and 52.6 kgs, respectively) and eight females (mean age and weight 34.3 years and 40.7 kgs, respectively). A majority (18) were residents of Delhi and the rest hailed from different parts of North India. All of them had a history of previous treatment ranging from six to 34 months. Cavity on chest X-rays was seen in 81%, while 44% showed extensive involvement. The patients received at least four "second line drugs" during their treatment with a mean of 6.2 anti-tubercular drugs during their intensive phase. Of the 27 patients, 13 were cured, 10 defaulted, one died, one is still on treatment and two were referred for surgery. Radiological improvement was observed in two third of cases and chest X-ray of two patients showed a complete resolution. Six predictors were identified for successful outcome of MDR-TB. They include weight gain at six months, culture conversion, radiological improvement during treatment, disease with M. tuberculosis strains exhibiting resistance to less than or up to three anti-tubercular drugs, use of less than or up to three second line drugs in treatment and no change of regimen during treatment.

CONCLUSION

Default from treatment was observed to be a major challenge in the treatment of MDR-TB due to long duration and expense of ATT.

Molecular typing of Mycobacterium tuberculosis isolates from different parts of India based on IS6110 element polymorphism using RFLP analysis

BACKGROUND & OBJECTIVE

IS 6110 based typing remains the internationally accepted standard and continues to provide new insights into the epidemiology of Mycobacterium tuberculosis. The aim of the study was to characterize M. tuberculosis isolates obtained from different parts of India based on IS6110 element polymorphism using restriction fragment length polymorphism (RFLP) analysis.

METHODS

RFLP was analyzed among 308 isolates of M. tuberculosis deposited in the Mycobacterial Repository Centre, Agra, from different parts of India. DNAs isolated from these strains were restricted with Pvu II, transferred on to nylon membrane and hybridized with a PCR amplified DIG-labeled 245 bp IS6110 probe.

RESULTS

Based on the copy number, M. tuberculosis isolates were classified into four groups, (i) lacking IS6110 element; (ii) low copy number (1-2); (iii) intermediate copy number (3-5); and (iv) high copy number (6-19). Copy number higher than 19 however was not observed in any of the isolates studied. At the national level, 56 per cent of the isolates showed high copy number of IS6110, 13 per cent showed intermediate copy number, 20 per cent showed low copy number, whereas 11 per cent isolates lacked IS6110 element. At the regional level, there was not much difference in the RFLP profiles of isolates (IS6110 copy numbers/patterns) from different parts of the country.

INTERPRETATION & CONCLUSION

IS6110 DNA based fingerprinting could be a potentially useful tool for investigating the epidemiology of tuberculosis in India.