Performance of recombinant ESAT-6 antigen (ML0049) for detection of leprosy patients

AIMS

The study was aimed to evaluate the Mycobacterium leprae recombinant early secreted antigenic target-6 (rESAT-6) for its serological performance in leprosy patients.

METHODS AND RESULTS

Employing enzyme-linked immunosorbent assay (ELISA), serum samples were tested for prevalence of immunoglobulin G antibodies against M. leprae rESAT-6. The results revealed that the sensitivity of the assay for smear-positive leprosy patients was 82.4% (14 of 17) while for smear-negative patients it was 19.4% (six of 31). Interestingly, the performance of ESAT-6-based assay was statistically comparable with anti-phenolic glycolipid-I antibody-detecting ELISA, a most widely studied serological assay in leprosy. Regarding specificity, none of the 48 controls was positive indicating that antibody response to ESAT-6 was highly specific. Moreover, a high concordance between bacterial index and anti-ESAT-6 antibody-detecting assay was noted.

CONCLUSIONS

Recombinant ESAT-6 seems to be a potential serological reagent for detection of M. leprae infection.

SIGNIFICANCE AND IMPACT OF THE STUDY

ESAT-6 serology may have utility for (i) early diagnosis, particularly, of highly infectious form (multibacillary, MB) of leprosy, (ii) monitoring the response in smear-positive leprosy patients during the course of the chemotherapy, (iii) classification of leprosy patients into MB and paucibacillary groups for treatment purpose. Hence, further research on these lines is warranted.

Quantitative Determination of Reserpine, Ajmaline, and Ajmalicine in Rauvolfia serpentina by Reversed- Phase High-Performance Liquid Chromatography

A sensitive and reproducible reversed-phase high-performance liquid chromatography (HPLC) method using photodiode array detection is established for the simultaneous quantitation of important root alkaloids of Rauvolfia serpentina, namely, reserpine, ajmaline, and ajmalicine. A Chromolith Performance RP-18e column (100 x 4.6-mm i.d.) and a binary gradient mobile phase composed of 0.01 M (pH 3.5) phosphate buffer (NaH(2)PO(4)) containing 0.5% glacial acetic acid and acetonitrile are used. Analysis is run at a flow rate of 1.0 mL/min with the detector operated at a wavelength of 254 nm. The calibration curves are linear over a concentration range of 1-20 microg/mL (r = 1.000) for all the alkaloids. The various other aspects of analysis (i.e., peak purity, similarity, recovery, and repeatability) are also validated. For the three components, the recoveries are found to be 98.27%, 97.03%, and 98.38%, respectively. The limits of detection are 6, 4, and 8 microg/mL for ajmaline, ajmalicine, and reserpine, respectively, and the limits of quantitation are 19, 12, and 23 microg/mL for ajmaline, ajmalicine, and reserpine, respectively. The developed method is simple, reproducible, and easy to operate. It is useful for the evaluation of R. serpentina.

Imatinib mesylate therapy in advanced gastrointestinal stromal tumors—A Regional cancer centre experience

19505

Background: The treatment of gastrointestinal stromal tumors has been revolutionised by the advent of Imatinib, a specific tyrosine kinase inhibitor. Post operative local and metastatic recurrences of this tumor have been effectively managed by Imatinib. Here we present our experience of Imatinib in recurrent locally advanced/metastatic gastrointestinal stromal tumors (GIST). Methods: From Nov 2001 to Sep 2005, 33 patients with metastatic and / or locally advanced inoperable CD-117 positive GIST were offered imatinib mesylate therapy at 400 mg/day p.o. A total of 21 patients were evaluable for tumor response. Follow up period ranged from 4 months to 38 months with median follow up period being 18 months. Median age is 58 yrs, M:F ratio is 6:4. ECOG performance status was 0–1 in 70% (23 patients) and 2 in 30% (10 patients). 70% patients had post surgery recurrence. 2 patients (6%) had received adjuvant chemotherapy prior to recurrence. 30% (10 patients) had local recurrence, 40% (13 patients) had metastatic disease while 30% (10 patients) had local recurrence as well as metastatic disease. Results: Response evaluation was done by RECIST criteria. 15% (5 patient) showed CR while PR rates were 30% (10 patients). The overall major response (CR+PR) was 45%. The overall progression free survival was as high as 80%. All the patients who had a progression free survival also had a significant improvement in quality of life. Conclusions: Imatinib mesylate therapy shows significant survival benefits in locally advanced inoperable/metatstatic gastrointestinal stromal tumors. It will be a very long time before PET scan for evaluation and follow up becomes feasible in developing country setting.

No significant financial relationships to disclose.

Childhood nasopharyngeal carcinoma: A 4-year single institution experience

9069

Background: Pediatric nasopharyngeal carcinoma (PNC) represents a locally advanced undifferentiated tumor. In this study, clinical experience and therapeutic results of 24 children with newly diagnosed PNC, treated in a single oncology institution in India over a period of 5 years, are analyzed. Methods: 24 patients (23 males and 1 female) 7–14 years old (median = 12) from Jan 2000 to Sep 2005 with PNC were retrospectively evaluated. 18/24 patients were evaluable. 16 patients received induction chemotherapy followed by radiotherapy while 1 patient was offered concurrent chemoradiotherapy, 1 patient received radiotherapy alone. 15/16 patients received postradiation chemotherapy. The agents used in induction and adjuvant therapy were cisplatin (100 mg/m2) on day 1 and 5-fluorouracil 750 mg/m2 for 5 days. The dose of radiotherapy used was 60 gray in 30 fractions. Results: The time of onset of symptoms to diagnosis ranged from 1 month to 9 months with a median of 5.5 months. Histopathology was lymphoepithelioma in 5 patients (27.7%) while 13 patients (72.2%) had poorly differentiated carcinoma. Disease extent was T2 (n = 7), T3 (n = 6), and T4 (n = 5); N1 (n = 5), N2 (n = 7), and N3 (n = 5). 7 patients had intracranial invasion. None had metastatic disease on presentation. 13 patients (72.2%) achieved major response which included 7 (38.8%) complete remission and 6 (33.3%) partial remission after the induction chemotherapy and radiotherapy. 4 (22.2%) had progressive disease. Another 3 (16.6%) attained complete remission after post radiation chemotherapy which consisted of two cycles of cisplatin and 5-flourouracil. The follow up ranged from 5 months to 84 months with a median follow up of 35 months. The disease free survival ranged from 10 months to 53 months with a median of 33 months. The patients who had a better response to induction chemotherapy had a better disease free survival. Out of 7 patients who attained complete remission 2 relapsed with a median time to first relapse of 9.5 months. Toxicity to therapy was modest. Only one patient had grade 4 neutropenia and mucositis. There was no therapy related mortality. Conclusion: Chemoradiotherapy for nasopharyngeal carcinoma in children is an effective treatment modality with minimal toxicity.

No significant financial relationships to disclose.

Central venous access in the pediatric cancer patient—Problems unique to developing countries: 5-year experience at a regional cancer center in Western India

9049

Background: Central venous catheter (CVC) is required in the pediatric cancer patient for chemotherapy administration and supportive care. This study was carried out to review our experience with CVC, with special reference to issues unique to developing countries. Methods: 178 children who underwent 181 CVC insertions at our institute between January 2001 and October 2005 were retrospectively analysed for demographics, diagnosis, type of CVC, infective and non infective complications. Continuous data were assessed using the t test or the Wilcoxon rank sum test and categorical data by the chi square test or the Fisher’s exact test. Results: Median age was 6.5 years (0.6–13 yr). Commonest diagnosis was acute lymphoid leukemia (ALL) (n=60). CVC used were Hickman (n=162), subcutaneous ports (n=9) and peripherally inserted central catheters (n=10). Patients with hickman catheters had 164 insertions for 162 patients with a total of 14,090 catheter days, an average of 86.9 days/catheter. There were 5.36 culture positive infections /1000 catheter days. The commonest isolate was Coagulase negative S. Aureus (CNS) (44/80 cases). CVC infection with CNS was associated with higher risk of recurrent infections (OR=3.5 {95%CI=2.12–8.23} p=0.01). Patients having recurrent CVC infections received antibiotics for a median of 9.4 days as against a median of 10 days for those with non-recurrent infections (p=0.01, Wilcoxon rank sum). In 58 ALL patients, early (within 15 days of induction) insertion of CVC was associated with increased risk of culture positive infection as against late (after 15 days of induction) insertion (OR=2.3, 95%CI=1.0–5.2, p=0.05). Other complications were thrombosis (n=3), exit-site infection (n=5), tunnel infection (n=3), catheter fracture (n=1) and dislodgement (n=3). Conclusions: As most patients do not afford port, Hickman is the most preferred CVC in pediatric oncology in a developing country. Most patients are of low literacy and poor socioeconomic status. This is reflected in significantly high rates of CVC infection. Communication between the inserting doctor, nursing staff and proper counseling of the patient is the key to reduce complications

No significant financial relationships to disclose.

Simultaneous Determination of Vincristine, Vinblastine, Catharanthine, and Vindoline in Leaves of Catharanthus roseus by High-Performance Liquid Chromatography

A simple reversed-phase liquid chromatographic method is developed for the simultaneous quantitation of the anticancerous drugs vincristine, vinblastine, and their precursors catharanthine and vindoline using a Merck Chromolith Performance reversed-phase high-performance liquid chromatography column. A better resolution is obtained in comparison with available particulate-type C18 columns. The column provides good reproducibility and peak symmetry. Chromatography is carried isocratically with a mobile phase of acetonitrile-0.1M phosphate buffer containing 0.5% glacial acetic acid (21:79, v/v; pH 3.5) at a flow rate of 1.2 mL/min and UV detection at 254 nm. Parameters such as linearity, limits of quantitation (LOQ) and detection (LOD), precision, accuracy, recovery, and robustness are studied. The method is selective and linear for alkaloid concentration in the range 0.25 microg-25 microg/mL. The LOQ and LOD are 25, 46, 56, and 32 microg/mL and 8, 14, 18, and 10 microg/mL, respectively. The results of accuracy studies are good. Values for coefficient of variation are 2.50, 1.82, 1.33, and 1.13, respectively. The percent recovery of the alkaloids was found to be 96%, 97%, 98%, and 98%, respectively. Peak purity and homogeneity of these compounds in plant extract is studied using a photodiode-array detector. This simple and rapid method of analysis is applied for the determination of these alkaloids in a large number of leaf extracts of Catharanthus roseus..

Evidence for a Great Medieval Earthquake (~1100 A.D.) in the Central Himalayas, Nepal

The Himalayan orogen has produced three thrust earthquakes with moment magnitude (Mw) 7.8 to 8.5 during the past century, yet no surface ruptures associated with these great earthquakes have been documented. Here, we present paleoseismic evidence from east central Nepal that, since approximately 700 A.D., a single earthquake ruptured the Frontal Thrust fault at approximately 1100 A.D., with a surface displacement of approximately 17 (+5/-3) meters and a lateral extent and size that could have exceeded 240 kilometers and approximately Mw 8.8, respectively. Ruptures associated with Mw <8.2 events would contribute to the frontal Himalayas folding but would stop before reaching the surface. These findings could require substantial modifications to current regional seismic hazard models.

The effect of particle size and electrical charge on macrophage-osteoclast differentiation and bone resorption

In aseptic loosening, there is commonly periprosthetic bone loss and a heavy macrophage infiltrate in response to biomaterial wear particles generated from the implant materials. Macrophages which have phagocytosed wear particles are known to be capable of differentiation into bone resorbing osteoclasts. In this investigation we determine the role of particle size and particle charge on this process. Mouse monocytes and macrophages were co-cultured with osteoblast-like UMR106 cells and 1,25 dihydroxyvitamin D3 in the presence or the absence of (i) various sizes of latex beads (0.1, 1, 10 and 100 microm) and (ii) uncharged, positively- or negatively-charged sephadex beads of uniform shape and composition. The extent of osteoclast differentiation by monocytes or foreign body macrophages was determined by the expression of the osteoclast-associated enzyme tartrate-resistant acid phosphatase and lacunar bone resorption. No significant difference in the extent of osteoclast formation and bone resorption was noted in response to particle size. Osteoclast formation was also not significantly different in the presence of positively/negatively charged and uncharged particles. These findings indicate that osteoclast formation is not significantly influenced by particle characteristics, such as particle size. They also add support to the hypothesis that macrophage involvement in periprosthetic osteolysis is not dependent on particle phagocytosis and that it may be induced by particle contact.

Occult hepatitis B virus infection as a cause of cirrhosis of liver in a region with intermediate endemicity

BACKGROUND

Serological tests may fail to identify hepatitis B virus (HBV) infection as a cause of liver cirrhosis in a proportion of patients. The frequency of such occult infection in regions with intermediate HBV endemicity is not known. Such cases may be diagnosed by incremental testing for IgG anti-HBc, serum HBV DNA, and HBV DNA in liver tissue.

METHODS

We tested sera of 111 patients with cirrhosis, including 39 with history of significant alcohol ingestion, for HBsAg, anti-HBc and serum HBV DNA. In addition, in a subset of 14 patients, HBV DNA was looked for in liver tissue.

RESULTS

On HBsAg and anti-HBc testing, 66 patients had HBV infection. Serum HBV DNA testing identified HBV infection in 13 additional cases. Of 18 patients labeled as 'cryptogenic' on serological testing, HBV DNA was detected in the serum in 7 patients. Of 14 patients in whom paired liver tissue and serum specimens were tested, 4 additional patients with HBV infection were detected after liver biopsy analysis.

CONCLUSIONS

Serological tests for HBsAg and anti-HBc antibody are insensitive in identifying HBV infection in patients with liver cirrhosis. HBV DNA testing in serum and liver can help in establishing HBV infection as etiology, either alone or in addition to another cause.

Inhibition of anti-CD3 and interleukin-2 stimulated T lymphocyte proliferation by peptidomimetic opioid compound

In continuation to our earlier studies with peptidomimetic opioid compounds, we have further investigated immunosuppressive properties of one of our peptidomimetic compound (Tyr-NH-CH2-CH2-O-Phe-NH2) using peripheral blood mononuclear cells (PBMCs) of healthy volunteers. Peptidomimetic compound was evaluated for its effect on anti-CD3 and recombinant human interleukin-2 (rhIL-2) stimulated lymphocyte proliferation in vitro and lipopolysaccharide (LPS) induced activation of mitogen activated protein kinase (MAPK, pp42/44) in mouse macrophage cells (RAW 264.7). Our results show the immunosuppressive potential of synthetic peptidomimetic compound. This compound significantly inhibited anti-CD3 and rhIL-2 stimulated lymphocyte proliferation in vitro. However, this peptidomimetic compound did not show any effect on LPS induced MAPK activation. These observations suggest that above peptidomimetic compound has potential to inhibit immune responses mediated by lymphocytes.

Anticellular and immunosuppressive properties of ethanolic extract of Acorus calamus rhizome

Modulation of immune response to alleviate disease has been of interest since long. Plant extracts have been widely investigated for possible immunomodulatory properties. We have evaluated the anticellular and immunomodulatory properties of ethanolic extract of Acorus calamus rhizome. This extract inhibited proliferation of mitogen (phytohaemagglutinin; PHA) and antigen (purified protein derivative; PPD)-stimulated human peripheral blood mononuclear cells (PBMCs). In addition, A. calamus extract inhibited growth of several cell lines of mouse and human origin. It also inhibited production of nitric oxide (NO), interleukin-2 (IL-2) and tumor necrosis factor-alpha (TNF-alpha). Intracytoplasmic interferon-gamma (IFN-gamma) and expression of cell surface markers, CD16 and HLA-DR, on human PBMC, were not affected on treatment with A. calamus extract but CD25 expression was down regulated. Our study demonstrates the antiproliferative and immunosuppressive potential of ethanolic extract of A. calamus rhizome in vitro.

Purification and characterization of a lectin from wild sunflower (Helianthus tuberosus L.) tubers

A lectin (HTTL) was isolated from Helianthus tuberosus L. (wild sunflower) tubers using ion-exchange chromatography, gel filtration, and affinity chromatography. The lectin agglutinated both untreated and trypsin-treated rabbit erythrocytes and did not agglutinate human blood cells of groups A, B, and O. The gel filtration showed the native molecular mass of 72 kDa and subunit molecular masses of 17 and 18.5 kDa on 12% SDS-PAGE. The lectin activity was inhibited by D-mannose. The tetrameric protein revealed a unique characteristic by forming a broad zone of protein in native PAGE at pH 8.3, which dissociated into seven subunits of varying e/m ratios on acid gel at pH 4.3. These seven bands revealed two polypeptide species of molecular masses 17 and 18.5 kDa on 12% SDS-PAGE, as in the case of the native protein. The result indicated that of the seven subunits, three were homotetramers of 17 kDa, one was a homotetramer of 18.5 kDa, and three were heterotetramers of 17 and 18.5 kDa. The lectin was thermostable with broad pH optima (pH 4-8) and had no requirement for divalent metal cations for its activity. The amino acid composition showed that the lectin contained higher amounts of glycine, alanine, and lysine, but no methionine. The sugar content was estimated to be 5.3% mannose equivalent. The HTTL was mitogenic to mouse spleen (total) cells at 25 microg/ml concentration. The lectin showed characteristics different from those of the earlier reported H. tuberosus tuber lectins and hence opens up a new avenue to investigate the structure-function relationship of lectin in Helianthus species.

Evaluation of UV-radiation induced singlet oxygen generation potential of selected drugs

Photosensitization reaction of drugs leading to the formation of reactive oxygen species under ultraviolet radiation (UVR) can cause tissue injury, resulting in damage to various cellular macromolecules. The aim of this study was to determine the singlet oxygen generation potential of some commonly used antibiotics so that due precautions can be exercised to minimize their photosensitizing action and oxidative stress potential. The selected antibiotics were examined for their ability to produce singlet oxygen (1O2) under artificial UVA (320-400 nm). Singlet oxygen generation of various screened antibiotics under UVA is of the following order: Nalidixic acid > Amphotericin-B > Cephradine > Cefazolin > Nafcillin > Cephalothin > Ampicillin > Cephalexin > Puromycin > Kanamycin > Lincomycin > Tetracycline > Nystatin > Gentamicin sulphate. Nalidixic acid, the most potent generator of 1O2 among the screened antibiotics, was selected to carry out further studies. Certain specific quenchers of 1O2 such as beta-carotene, 1,4-diazabicyclo[2.2.2] octane (DABCO), and sodium azide (NaN3) accorded significant inhibition in the production of 1O2. The results suggest that precautions are necessary to avoid ultraviolet radiation after the intake of photoreactive drugs, especially in tropical countries such as India. These findings are significant because UVB radiation is reportedly increasing on earth surface in part due to depletion of stratospheric ozone layer. The selected drugs are commonly used for the treatment of various diseases. Thus, the synergistic action of both can lead to undesirable phototoxic responses.