Selective G-quadruplex DNA stabilizing agents based on bisquinolinium and bispyridinium derivatives of 1,8-naphthyridine.

Various biologically relevant G-quadruplex DNA structures offer a platform for therapeutic intervention for altering the gene expression or by halting the function of proteins associated with telomeres. One of the prominent strategies to explore the therapeutic potential of quadruplex DNA structures is by stabilizing them with small molecule ligands. Here we report the synthesis of bisquinolinium and bispyridinium derivatives of 1,8-naphthyridine and their interaction with human telomeric DNA and promoter G-quadruplex forming DNAs. The interactions of ligands with quadruplex forming DNAs were studied by various biophysical, biochemical, and computational methods. Results indicated that bisquinolinium ligands bind tightly and selectively to quadruplex DNAs at low ligand concentration (∼0.2-0.4 µM). Furthermore, thermal melting studies revealed that ligands imparted higher stabilization for quadruplex DNA (an increase in the T(m) of up to 21 °C for human telomeric G-quadruplex DNA and >25 °C for promoter G-quadruplex DNAs) than duplex DNA (ΔT(m) ≤ 1.6 °C). Molecular dynamics simulations revealed that the end-stacking binding mode was favored for ligands with low binding free energy. Taken together, the results indicate that the naphthyridine-based ligands with quinolinium and pyridinium side chains form a promising class of quadruplex DNA stabilizing agents having high selectivity for quadruplex DNA structures over duplex DNA structures.

(99m)Tc-labeling of ciprofloxacin and nitrofuryl thiosemicarbazone using fac-[(99m)Tc(CO)3(H2O)3] core: evaluation of their efficacy as infection imaging agents.

The aim of this study was to radiolabel ciprofloxacin (Cip) and nitrofuryl thiosemicarbazone (NFT) with the fac-[(99m)Tc(CO)(3)(H(2)O)(3)](+) core and to evaluate the ability of the radiopharmaceuticals as tracers in detecting sites of infection. Cip and NFT were radiolabeled with the fac-[(99m)Tc(CO)(3)(H(2)O)(3)](+) core and characterized by RHPLC. The stabilities of the preparations were evaluated in saline and rat serum. In vitro binding studies of the radiopharmaceuticals with S. aureus were performed. Biodistribution studies were conducted at different time points after injecting (i.v.) the radiopharmaceuticals in rats (intramuscularly infected with S. aureus) as well as in rats with sterile inflammation. To assess the infection targeting capacity of (99m)Tc-tricarbonyl ciprofloxacin and nitrofuryl thiosemicarbazone, (99m)Tc(v)O-Cip and (99m)Tc(v)O-NFT were used as control. Scintigraphic imaging studies of tricarbonyl compounds and (99m)Tc(v)O-Cip were performed at 4 h after injection. The radiochemical purities of (99m)Tc(CO)(3)-Cip and (99m)Tc(CO)(3)-NFT were between 97-98% as determined by thin layer chromatography (TLRC) and RHPLC; no further purification is necessary before injection. The radiopharmaceuticals exhibited substantial stability when incubated in isotonic saline and serum up to 24 h. Biodistribution studies showed maximum uptake in the infected rat thigh muscle at 4 h post injection and washing out at slower rate from the infected site than the oxo technetium chelate. The mean ratios of uptake in infected/non-infected thighs were 3.87:1, 3.41:1 and 3.17:1 for (99m)Tc(CO)(3)-Cip, (99m)Tc(CO)(3)-NFT and (99m)Tc(v)O-Cip respectively. During scintigraphic studies, infection sites appeared quite distinctly with (99m)Tc(CO)(3)-Cip and (99m)Tc(CO)(3)-NFT, comparable to the behaviour with (99m)Tc(v)O-Cip. These results encouraged us for further development of infection imaging radiopharmaceuticals based on the (99m)Tc-tricarbonyl core.

Development and physical characterization of chloramphenicol loaded biodegradable nanoparticles for prolonged release.

The objectives of our study were to prepare a biodegradable nanoparticulate system of chloramphenicol (CHL) and to evaluate its ability to prolong in vitro release of CHL compared to free drug suspension (FDS). CHL-loaded polylactide-co-glycolide nanoparticles (CHL-PLGA-NPs) were prepared by an emulsion/solvent evaporation method using ethyl acetate and polyvinyl alcohol. CHL-PLGA-NPs were characterized by particle size, zeta potential, infrared spectra, drug entrapment efficiency and in vitro release kinetics measurement. Sonication was done with an ultrasound pulse sonicator at 70 W, 30 kHz for 60 s to produce stable NPs of mean size range from 277 nm to 433 nm. Drug to polymer ratio (D:P) was selected as formulation variable and significantly influenced entrapment efficiency (approximately 30% to 66%) and release (p < 0.05). Entrapment of CHL in biodegradable NPs significantly prolonged drug release compared to FDS and thus implies potential antibiotic delivery system for ocular application.

Prevalence of high-risk human papillomavirus type 16/18 infection among women with normal cytology: risk factor analysis and implications for screening and prophylaxis.

OBJECTIVE: To determine the prevalence of high-risk human papillomavirus (HR-HPV) 16/18 infection of uterine cervix among women in the reproductive age group, with cytologically normal cervical (Pap) smears; to analyse the risk factors for HR-HPV acquisition and to address their implications for cervical cancer screening and prophylaxis in a low resource setting. METHODS: Cervical samples from 769 cytologically negative women (age 18-45 years) attending a tertiary care centre in Delhi were subjected to HPV DNA testing and HR-HPV 16/18 and low-risk (LR)-HPV 6/11 sub-typing by polymerase chain reaction. Univariate risk factor analysis was carried out in HR-HPV positive (n = 86) versus HR-HPV negative women (n = 683) by chi-square test. RESULTS: The overall HPV prevalence among cytologically normal women was 16.6%. HR-HPV16 was detected in 10.1%, whereas HPV18 was detected in 1% of women. HR-HPV 16/18 comprised 67% of the total HPV positives. There was no decline in HR-HPV positivity with age, and women aged 40-44 years were at significantly increased risk for HR-HPV prevalence (P = 0.03). Statistically significant associations of HR-HPV infection were found with risk factors such as high parity (P = 0.04), cervicitis/hypertrophic cervix (P = 0.01), unhealthy cervix (P = 0.04), rural residence (P = 0.03), low socioeconomic status (P = 0.01) and illiteracy (P = 0.07). CONCLUSIONS: Although the sample size was small, based on the observation that HR-HPV 16 and 18 contributed significantly to the overall HPV prevalence in our setting, we speculate that testing/prophylaxis for these prevalent high-risk types could perhaps make cervical cancer screening and preventive programmes cost-effective. Larger community-based studies on HPV prevalence and persistence are required to validate these findings before definitive recommendations can be made to the policy makers.

Age trends in pre-cancerous and cancerous lesions of the uterine cervix in a cytology screening programme: what should be the target age group for a major thrust of screening in resource-limited settings?

OBJECTIVE: To identify the target age group where screening efforts may be concentrated in order to reduce the incidence of cervical cancer in resource-limited countries. STUDY DESIGN: The results of cyto-screening in a hospital-based screening programme for early detection of cervical cancer were analysed retrospectively. The frequency of epithelial cell abnormalities (ECAs) was computed in different age groups. OBSERVATIONS AND RESULTS: A total of 5.6% ECAs were detected on cyto-screening. The peak age incidence for squamous intraepithelial lesions (SILs) was in the 30-39 age group while that for malignancies was age >60 years. The mean ages for LSIL, HSIL and cancer were 34.7, 37.7 and 51.8 years respectively. Around 43% LSILs and 48% HSILs presented in the fourth decade. If both fourth and fifth decade are covered by screening we could detect almost two-thirds of SILs. CONCLUSIONS: A distinct latent period of more than a decade between the onset of SIL and development of frank cancer provides us with ample opportunity to prevent cervical cancer through screening. Our data validate the WHO recommendation of once in a lifetime screening of women in their fourth decade, for low-resource settings. If resources permit, screening can be extended to include women in the fifth decade. This approach would enable us to pick up maximum SILs within the available resources and prevent their progression to cancer.

Cell block as an adjunct to conventional Papanicolaou smear for diagnosis of cervical cancer in resource-limited settings.

OBJECTIVE: To assess the utility of indigenously prepared cell blocks (CBs) as an adjunct to a conventional smear test in providing a reliable diagnosis of clinically suspicious cervical cancer in resource-limited settings. METHODS: Eighty-six clinically suspicious cervical cancer cases underwent a conventional smear test, CB preparation from residual cellular samples and biopsies at the same sitting. Correlations were performed between these modalities in order to derive the sensitivity and specificity of the CB technique to diagnose cervical cancer. OBSERVATION & RESULTS: Out of 86 clinically suspicious cervical cancers, 72 (83.7%), 70 (81.4%) and 67 (77.9%) cases were diagnosed as malignant on tissue biopsies, CBs and smears respectively. CB-biopsy agreement in the diagnosis of malignancy was feasible in 87.5% of the cases while CB-Pap smear agreement was feasible in 92.5% of the cases. Sensitivity and specificity of CB preparation to diagnose malignancy was 92.5% and 100%, respectively, when the smear was taken as the reference test (excluding the unsatisfactory smears). When biopsy was taken as the gold standard, the sensitivity and specificity of CBs were 87.5% and 100% respectively (excluding the unsatisfactory biopsies). In 8/19 cases where the smear diagnoses were either unsatisfactory or atypical squamous cells/atypical glandular cells, CBs picked up malignant lesions. CONCLUSION: CBs prepared from the residual cellular sample of conventional cervical scrapes augment the sensitivity of the smear test. When used as an adjunct to the smear, CBs aid in providing a reliable diagnosis of cervical cancer in the majority of the clinically suspected cases and thus the biopsy load can be reduced significantly in resource-poor settings.

Test characteristics of various screening modalities for cervical cancer: a feasibility study to develop an alternative strategy for resource-limited settings.

OBJECTIVE: To determine test characteristics - sensitivity, specificity, positive and negative predictive values - of different screening modalities to detect cervical precancerous and cancerous lesions in order to devise an effective alternative strategy for cervical cancer screening in resource-poor settings. METHODS: A total of 472 women presenting with nonspecific gynecologic symptoms were screened by cytology, visual inspection with acetic acid application (VIA), VIA with magnification (VIAM) and human papillomavirus (HPV)-DNA testing. Colposcopic examination was performed in all and on-site biopsy was taken if any grade I and above lesion was detected on colposcopy (230). On histopathological examination, 105 showed cervical intraepithelial neoplasia II and above lesions. Sensitivity, specificity and predictive values for each test were calculated taking colposcopy and or directed biopsy as the gold standard. Comparisons were made with cytology in order to assess the feasibility of alternative strategies in resource-poor settings. RESULTS: VIA was less sensitive (86.7% versus 91.4%) but more specific (90.7% versus 86.6%) than cytology at low grade squamous intraepithelial lesion (LSIL) threshold but the difference was not statistically significant (P > 0.01). HPV testing improved the sensitivity over cytology (97.1% versus 91.4%) but there was a nonsignificant loss of specificity (84.2% versus 86.6%). Results of VIAM were more or less similar to VIA. CONCLUSION: VIA can be used as a mass screening tool for cervical cancer in resource-poor settings.

Extracranial complications of chronic suppurative otitis media.

The aim of this study was to find out the pattern of extracranial complications of CSOM cases who attended to the department of ENTD, Mymensingh Medical College Hospital during the period from July'1999 to June' 2001. Different types of extracranial complications of CSOM were presented here. A total of 100 cases, diagnosed clinically and radiologically were included in the study of which 66 were male and 34 were female giving a male to female ratio of 1.94 : 1 (p < 0.05). Majority cases (53) were in the age group of 11- 20 years followed by the age group of below 10 years where there were 30 cases. Majority (64) cases came from low socio-economic class. The number of different types of extracranial complications of CSOM were as follows: mastoid abscess 57, discharging sinuses 28, purulent labyrinthitis 07, Bezold's abscess 04, fascial nerve paralysis 03 and zygomatic abscess 01. In all cases of CSOM Cholesteatoma were detected. In 14 cases, Cholesteatoma were associated with granulation tissue/polyp. Modified radical mastoidectomy were performed in all cases. On analyzing the findings of the present study it was observed that mastoid abscess were the predominant extracranial complications of CSOM, affecting mostly the male population of 11 - 20 years age group coming from low socio-economic class.

Outcome of patients treated with the endoscopic dacryocystorhinostomy.

DCR allows an abstracted lacrimal drainage system to be drained into the nasal fossa. Since the development of endonasal endoscopic surgical technique, the endonasal approach presents it self as an alternative choice to the conventional external approach as in the former skin scar can be avoided. We performed DCR of 50 cases in endonasal endoscopic approach in Mymensingh Medical Collage Hospital. The age range of patient was found between 7 to 35 years, average 21 & male female ratio was 1:1.5 with follow up to 2.10 years with high success rate. Associated nasal disease correction septoplasty was done in 7 cases. In each & every case silicon tube was introduced & removed after 3 to 6 months. The only complication was periorbital injury in 5 cases, punctal tear in 2 cases and granuloma formation in 2 cases. Overall success rate was 86%.

Epidemiology of group-A streptococcal infection amongst children of different ethnic groups in Darjeeling.

The carrier rate of Group A Streptococcus (GAS) was studied amongst 932 children from 1+ upto 12 years of age in three major racial groups in the foothills of the Darjeeling district of West Bengal. It was altogether 13 per cent and was found to be evenly distributed in the three ethnic groups as Gurkhas: 11 per cent, Rajbanshis: 15 per cent and Cosmopolitans: 13 per cent, but the incidence of Rheumatic fever and/or Rheumatic heart diseases were unnoticed among the Gurkha children who also had significant low ASO titres.

Detection of duck plague virus antigen in tissues by immunoperoxidase staining.

An avidin-biotin-peroxidase method of immunoperoxidase staining was successfully adapted for detection of duck plague virus antigen in formalin-fixed, paraffin-embedded tissue sections of the liver and spleen of experimentally infected domestic ducks. Positive staining was localized mostly in the nucleus but was also present in the cytoplasm of a few hepatocytes and von Kupffer cells of the liver, and lymphocytes and reticular cells of the spleen.

Chloramphenicol resistant Salmonella typhi: the cause of recent out-break of enteric fever in Calcutta.

Fifty one strains of Salmonella typhi were isolated during the recent outbreak of enteric fever in and around Calcutta. Forty strains were multidrug resistant including Chloramphenicol. Minimum inhibitory concentrations (MIC) of Chloramphenicol was between 200 mcg per ml and 500 mcg per ml. All these strains were sensitive to Cephalexine, Gentamicin, Furazolidine and Ciproflexacin. Widal test was done in all the cases but the result was inconclusive.

Iron and hemoglobin status of the offspring of guinea pigs whose mother received large doses of vitamin C during pregnancy and lactation.

1. Lower level of serum and liver iron were noted in the offspring of experimental group quinea pigs who received 1, 2 and 3 mg ascorbic acid per 100 g body weight per day. 2. Similar results were obtained in the hemoglobin content of same animals. 3. Normal values were observed for hemoglobin and the content of iron in serum and liver in the same group of offsprings when they were fed 4 mg ascorbic acid per 100 g body weight per day.

Effects of high intake of vitamin C by the guinea pigs in pregnancy and lactation on the tissue levels of the vitamin in their offspring.

1. Though the growth-rate of the guinea pigs of both the groups - control and experimental were almost same, the gain in body weight in the offspring of experimental group animals were observed to be less when they were fed 1, 2 and 3 mg ascorbic acid per 100 g body weight per day. 2. Ascorbic acid content in the tissues of the offspring maintained on 1, 2 and 3 mg ascorbic acid belonging to the experimental group were low. 3. The rate of growth and the tissue content of ascorbic acid were found to be normal in the same group of animals when they were supplemented with 4 mg ascorbic acid per 100 g body weight daily.