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Biomedical subjects

S Mandal

Publications and source records attributed to S Mandal.

At least 19 recordsLinked to original sources
PubMed2005

Quantum transport through a DNA wire in a dissipative environment.

Electronic transport through DNA wires in the presence of a strong dissipative environment is investigated. We show that new bath-induced electronic states are formed within the band gap. These states show up in the linear conductance spectrum as a temperature dependent background and lead to a crossover from tunneling to thermal activated behavior with increasing temperature. Depending on the strength of the electron-bath coupling, the conductance at the Fermi level can show a weak exponential or even an algebraic length dependence. Our results suggest a new environmentally induced transport mechanism. This might be relevant for the understanding of molecular conduction experiments in liquid solution, such as those recently performed on poly(GC) oligomers in a water buffer (B. Xu et al., Nano Lett. 2004, 4, 1105).

Biophysical Phenomena↗
PubMed2004

Shell structure of the near-dripline nucleus 23O.

Breakup reactions were used to study the ground-state configuration of the neutron-rich isotope 23O. The 22O fragments produced in one-nucleon removal from 23O at 938 MeV/nucleon in a carbon target were detected in coincidence with deexciting gamma rays. The widths of the longitudinal momentum distributions of the 22O fragments and the one-neutron removal cross sections were interpreted in the framework of a simple theoretical model which favors the assignment of Ipi = 1/2+ to the 23O ground state.

Journal Article↗
PubMed2004

Three discrete areas within the chromosomal 8p21.3-23 region are associated with the development of breast carcinoma of Indian patients.

Deletion in the 22.9 -Mb chromosomal (chr.) 8p21.3-23 region has been shown to be necessary for the development of breast carcinoma (CaBr). In this study, we have attempted to detect the minimal deleted region(s) in the chr.8p21.3-23 region in 62 primary breast lesions having 56 CaBr tumors and six other breast lesions of Indian patients using 15 microsatellite markers. The loss of heterozygosity (LOH) was observed for at least one marker in 96.4% (54/56) of the CaBr samples. Three discrete minimal deleted regions with high frequencies of LOH (39-65%) were identified in the chromosomal 8p23.1-23.2 (D1), 8p23.1 (D2) and 8p 21.3-22 (D3) regions within 2.03, 0.41, 2.47 Mb, respectively. No significant correlation was observed with the high deleted regions and the different clinicopathological parameters. Interestingly, 51.8% (29/56) CaBr samples showed either loss of chr.8p or interstitial deletions in this arm, indicating the importance of chr.8p in the development of CaBr. The pattern of allelic loss in the bilateral lesions had indicated that the lesions were clonal in origin and probably the deletion in the D3 region was the early event among the D1-D3 regions. Thus, our data have indicated that the D1-D3 regions could harbor candidate tumor suppressor gene(s) (TSGs) associated with the development of CaBr.

Adult↗
PubMed2004

Reduced minimum inhibitory concentration of chloramphenicol for Salmonella enterica serovar typhi.

BACKGROUND: Ciprofloxacin replaced chloramphenicol (C), the best choice of antibiotic in the treatment of enteric fever, when C-resistant enteric fever emerged and caused outbreaks in different parts of the world. C-sensitive S. enterica serovar Typhi emerged again due to withdrawal of the antibiotic pressure. AIMS: To assess the in vitro efficacy of C against Salmonella enterica serovar Typhi isolates (1991-2003). MATERIAL AND METHODS: A total of 464 blood culture isolates of S. enterica serovar Typhi were subjected to C susceptibility by disc diffusion and agar dilution methods using Mueller-Hinton agar. The antibiotic susceptibility of S. enterica serovar Typhi isolates obtained in the year 2002 and 2003 was determined using ampicillin, cotrimoxazole, ciprofloxacin, nalidixic acid, ceftriaxone and cefotaxime, in addition to C. Escherichia coli strain ATCC 25922 was used as the control. Changes in C sensitivity of the isolates were analyzed using chi2 test with Yates correction. RESULTS AND CONCLUSIONS: All the isolates of 1991 were C-resistant with minimum inhibitory concentration values (MICs) of 2000-5000 mg/ml. In the following years decrease in frequency of C resistance was noticed: 1992 (50%), 1993 (32%), 1994 (27%) and 1995 (05%). The isolates of 1996-99 and 2001 were 100% C-sensitive. In 2000, sensitivity was also high (79%). The strains isolated in the year 2002 and 2003, showing reduced susceptibility of ciprofloxacin, were nalidixic acid resistant, but sensitive to the third-generation cephalosporins (ceftriaxone and cefotaxime). The MICs for C-sensitive isolates (1991-2003) ranged 0.1-5 mg/ml. Results suggest the necessity for re-evaluation of C therapy in typhoid fever.

Anti-Bacterial Agents↗
PubMed2003

In vitro efficacy of ciprofloxacin alone and in combination with amoxycillin against Salmonella typhi isolates.

Combined effect of ciprofloxacin (Ci) and amoxycillin (Ax) has been studied in vitro against 12 clinical isolates of S. typhi that showed Ci minimum inhibitory concentration (MIC) of > or =1 microg/ml. By agar dilution method, MIC values of Ax were 10-16 microg/ml for 11 isolates and 0.5 microg/ml for the remaining one isolate. The isolates, when treated with Ci and Ax in combination, showed fractional inhibitory concentration (FIC) of 0.004-0.256 microg/ml for Ci. FIC of Ax ranged from 6-10 microg/ml, except for a single isolate that showed Ax FIC of 0.25 microg/ml. Thus Ci was more efficacious in combination with Ax against S. typhi than Ci alone. The antibiotic combination exhibited an additive effect for all the isolates showing FIC index 0.504-0.832.

Amoxicillin↗
PubMed2002

Toxin-producing plankton may act as a biological control for planktonic blooms--field study and mathematical modelling.

Termination of planktonic blooms is of great importance to human health, ecosystem, environment, tourism and fisheries. Toxic substances released by plankton play an important role in this context. The effect of toxin-producing plankton (TPP) on zooplankton is observed from the field-collected samples and mathematical modelling. Information from both the studies led us to suggest that TPP may terminate the planktonic blooms by decreasing the grazing pressure of zooplankton and thus acts as a biological control.

Animals↗
PubMed2002

Nasopharyngeal carriage of Haemophilus influenzae.

OBJECTIVE: Nasopharyngeal colonization of Haemophilus influenzae (H. influenzae) in young children may be important in developing countries. METHOD: In this study, we screened school going children for carriage of H. influenzae. A total of 44 H. influenzae isolates out of a collection of 162 were characterized for biotypes, capsular serotypes and antibiotic resistance. RESULTS: A significant proportion of H. influenzae (25/44) isolates were serotype b. High antibiotic resistance was observed against commonly administered antibiotics like ampicillin (79%), chloramphenicol (20%), trimethoprim sulfamethoxazole (84%) and erythromycin (95%). Comparison of antibiotic resistance profile of nasopharyngeal isolates was observed to be correlated with those of H. influenzae from disease. CONCLUSION: Multidrug resistant nasopharyngeal H. influenzae in young healthy children may act as reservoir. Monitoring of antibiotic resistance among nasopharyngeal H. influenzae as a surrogate for invasive H. influenzae seems an attractive option.

Age Distribution↗
PubMed2002

Quercetin: critical evaluation as an antileishmanial agent in vivo in hamsters using different vesicular delivery modes.

Chemotherapy is still a major challenge for in vivo drug targeting to macrophages. Toxicity remains the major obstacle for the most potent drugs already known in the therapy of leishmaniasis. Thus, new drugs and new delivery systems are sought. By using different vesicular delivery modes e.g. liposomes, niosomes, microspheres and nanoparticles, attempts have been made to deliver an indigenous antileishmanial compound, quercetin, to treat experimental leishmaniasis in the hamster model so as to increase its efficacy as well as to reduce the toxicity. At equivalent quercetin concentration, the nanocapsulated quercetin was found to be the most potent in reducing the parasite burden in the spleen as well as in reducing hepatotoxcity and renaltoxicity compared to free drug or drug in other vesicular forms. An inverse relationship between the efficacy and the size of the vesicles was established. Such a drug vehicle formulation especially in the nanocapsulated form may be considered for clinical trials.

Algorithms↗
PubMed2002

Bilateral cryptorchidism with bilateral inguinal hernia and retrovesical mass in an infertile man: single-stage laparoscopic management.

A 30-year-old married man presented with the complaint of inability to procreate. Examination revealed bilateral nonpalpable testes and bilateral inguinal hernia. Ultrasonography of the abdomen could not locate the testis; instead, a hypoechoic 5 x 5-cm mass was found behind the bladder. A CT scan of the abdomen revealed the right testis near the right inguinal canal. The left testis could not be identified beside the soft tissue mass. The patient was taken for diagnostic as well as therapeutic laparoscopy. The testis on the right was found just proximal to the internal inguinal ring, and right orchidopexy was done. The left testis was small and rudimentary; hence, orchidectomy was done. Bilateral laparoscopic herniorrhaphy was carried out with polypropylene mesh by fixing it intracorporeally to the pubic bone, Cooper's ligament, inguinal ligament, and conjoint tendon. Subsequently, the retrovesical mass was excised and retrieved by dilating the umbilical port site. The operative time was 3.5 hours with minimal blood loss. The postoperative period was uneventful, and the patient was discharged after 24 hours. The histopathology examination of the retrovesical mass showed an extragonadal germ cell tumor compatible with seminoma.

Adult↗
PubMed2002

Diffuse neurofibroma of scalp.

Diffuse neurofibroma is an uncommon but distinct variety of neurofibroma, usually affecting trunk, head and neck regions of adolescents and young adults. The clinical features, gross macroscopic and histopathological findings are enunciated and the criteria for instituting the preferred modality of treatment for such lesions has been reviewed, stressing upon the need to exclude the neurofibromatoses preoperatively.

Adult↗
PubMed2002

R-factor in Proteus vulgaris from ulcerative disease of fish, Channa punctatus.

A Proteus vulgaris isolated from external ulcers of the fresh water fish Channa punctatus showed multidrug resistance and heavy metal tolerance. The isolate from the ulcer showed resistance to chloramphenicol (Ch), nalidixic acid (Nx), streptomycin (Str) and tetracycline (Tet) with minimum inhibitory concentration (MIC) values of 750, 150, 75 and 125 microg/ml, respectively. The isolate showed growth in medium containing cadmium (Cd2+), up to a concentration of 2.5 mM indicating its heavy metal tolerance. Resistance to Ch, Str, Tet and Cd2+ of the isolate was lost after plasmid curing. Presence of plasmid DNA in the wild type and its absence in the cured P. vulgaris suggested that the resistance were plasmid mediated.

Animals↗
PubMed2001

Dielectric relaxation in a single tryptophan protein.

Although dielectric relaxation can significantly affect the intrinsic fluorescence properties of a protein, usually it is fast compared to fluorescence timescales and needs to be slowed down by adding viscogens or lowering temperature before its impact on fluorescence can be studied. We report here a remarkable blue shift in fluorescence upon bimolecular quenching in the single-tryptophan thermostable protein Bj2S, the 2S seed albumin from Brassica juncea, at ambient temperature and viscosity. The magnitude of the blue shift ( approximately 5 nm at 50% quenching by acrylamide) is striking in a single-tryptophan protein and is attributed to a slowly relaxing dielectric environment in Bj2S from red edge excitation, steady-state polarization and time-resolved fluorescence experiments. Our results have important implications on interpretation of fluorescence of proteins with highly constrained backbones and in designing model systems for studying slow protein solvation dynamics using Trp fluorescence as the reporter probe.

Albumins↗