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Biomedical subjects

S G Dastidar

Publications and source records attributed to S G Dastidar.

At least 19 recordsLinked to original sources
PubMed2002

Experimental studies on synergism between aminoglycosides and the antimicrobial antiinflammatory agent diclofenac sodium.

The antiinflammatory agent diclofenac sodium (Dc) exhibited remarkable antibacterial effects both in vitro and in vivo. Fifteen different bacteria sensitive to Dc as well as to a number of common antibiotics were tested for synergistic effects in vitro. Disc diffusion test with Dc and aminoglycosides assessed by stringent computation showed clear-cut synergism. Synergism between Dc and streptomycin (Sm) was found to be statistically significant (p < or = 0.01) when compared with their individual effects. By the checkerboard assessment procedure, the fractional inhibitory concentration (FIC) index of this combination was found to be 0.49, confirming synergism. The mouse protective capacity of this combination was then evaluated in vivo against S. typhimurium as the virulent infecting bacterium, and the size of bacterial load determined from infected autopsied animals. Statistical analysis by Student's 't' test suggested this drug combination is highly synergistic; synergism was also noted between Dc and other aminoglycosides.

Aminoglycosides↗
PubMed2001

Trifluoperazine: a broad spectrum bactericide especially active on staphylococci and vibrios.

Trifluoperazine showed some significant antimicrobial activity when tested against 293 strains from two Gram-positive and eight Gram-negative genera. Minimum inhibitory concentrations of the drug were measured using an agar dilution technique. Forty six of 55 strains of Staphylococcus aureus were inhibited by 10-50 microg/ml of trifluoperazine. This drug also inhibited strains of Shigella spp., Vibrio cholerae and V. parahaemolyticus at a concentration of 10-100 microg/ml. Other bacteria including Pseudomonas spp. were moderately sensitive to trifluoperazine. In the in vivo studies this compound offered significant protection to Swiss albino mice at a concentration of 30 microg/mouse (P<0.001) when challenged with 50 median lethal dose of Salmonella typhimurium NCTC 74.

Animals↗
PubMed2001

Antimicrobial activity of new coumarin derivatives.

A preliminary exploration of coumarin analogs as novel antimicrobial agents was carried out to determine the basic features of the structure responsible for the observed biological activity. The substituents ester or carboxylic acid on the coumarin ring were needed to have potent inhibitory activity against both Gram-positive and Gram-negative bacteria. The presence of phenolic hydroxyl group and/or carboxylic acid was necessary to possess higher activity against Helicobacter pylori.

Anti-Bacterial Agents↗
PubMed2001

Leprosy bacillus--possibly the first chemoautotrophic human pathogen cultivated in vitro and characterised.

Leprosy bacillus (LB) and leprosy derived in vitro culture forms, the chemoautotrophic nocardioform (CAN) bacteria, showed an extremely close homology and identity with each other as regards a chemoautotrophic nutritional pattern, a nocardioform morphology, a weak acid-fastness coupled with Gram and Gomori's stain positivity, an exclusive mycolate and lipid profile, a phenolic glycolipid (PGL-I) and a highly sequestrated DNA characteristic, namely, a unique small size, a low G+C % mole, an exceptionally high gamma and UV radiation resistance, and a high thermal resistance. LB/CAN bacteria (CANb) gave positive signals for 36 kDa protein PCR, as well as, for 65 kDa epitope, and hybridisation with two or more probes and also by RFLP-analysis. Both LB/and CAN bacteria exhibited bacillary multiplication in the mouse footpads (MFP), nerve infiltration and evidences for local pathogenicity associated with pronounced systemic invasion. A highly reproducible mutilation model could be established which enabled a successful application of the postulates of Koch. The proof of their total identity was their anergic reactions in LL cases counterpoised against Mitsuda type strong nodular responses, mirroring the reactions of leprosy bacilli in TT cases, in accordance with the dictum of XIth International Leprosy Congress (1978). Thus, the chemoautotrophic nutritional requirements of LB, entirely unsuspected for a medically important pathogenic bacterium, having dimorphic (both bacillary and mycelial) characters with spores, mycelia and granules and unique pathogenicity of multilation manifested through the virulence factor, the enzyme collagenase, made LB or M leprae the highly enigmatic bacterium for so long.

Animals↗
PubMed2000

Screening for anti-HIV drugs that can combine virucidal and virustatic activities synergistically.

Chlorcyclizine HCl and ciprofloxacin HCl were shown to have anti-HIV activity. They possess virustatic and virucidal activities against HIV, a murine retrovirus (RV) and several other RNA and DNA viruses. These drugs were screened from a large number of compounds on the basis of in vitro mutagenicity and antimetabolite detection tests. Subsequent studies were based on different exo vivo cell cultures. These two compounds were then tested on an animal model, following standard test protocols, using another retrovirus, maintained as Ehrlich's ascites cell tumour virus (EACTV). The animal mortality and protection tests corroborated the findings obtained in vitro, suggesting that these drugs acted synergistically against HIV, exhibiting both virucidal and virustatic properties.

Animals↗
PubMed2000

The anti-bacterial action of diclofenac shown by inhibition of DNA synthesis.

Most strains of Gram-positive and Gram-negative bacteria were inhibited by 50-100 mg/l of the anti-inflammatory agent, diclofenac sodium (Dc). In vivo test using 30 or 50 microg Dc per 20 g mouse (Swiss Albino variety) significantly (P <0.001) protected the animals when challenged with 50 MLD of a virulent Salmonella typhimurium. The anti-bacterial action of Dc was found to be due to inhibition of DNA synthesis which was demonstrated using 2 micro Ci (3H) deoxythymidine uptake.

Animals↗
PubMed2000

A new powerful antibacterial synergistic combination of trimethoprim and trimeprazine.

The antihistaminic phenothiazine trimeprazine (Tz) was found to exhibit significant antibacterial activity on the basis of in vitro and in vivo tests. For the study of synergism due to a combination between Tz and trimethoprim (Tm), drug soaked filter paper discs were placed on young culture lawns of sensitive bacteria on nutrient agar plates. Calculation of the area of inhibition zones for determining the degree of synergism between Tz and Tm showed the increase to be statistically significant (p<0.01) when compared with their individual effects. By the checkerboard assessment procedure, the fractional inhibitory concentration (FIC) index was found to be 0.18, confirming synergism. The protective capacity of this combination was then assessed in Swiss white mice using S. typhimurium as the challenge bacterium, and the level of bacterial load was determined from infected autopsied animals. Statistical analysis of the data by students 't' test finally proved that a combination of Tz+Tm was highly synergistic.

Animals↗
PubMed2000

Validity of mechanism of gene transfer in the process called conjugation in bacteria.

We have attempted a new evaluation of the process of conjugation in bacteria, because of some basic dissimilarities observed between this and that of eukaryotes, or plants and animals. Reference donor and recipient strains, widely used to prove conjugation in bacteria, were chosen; addition of DNase during the conjugation process, led to an unexpected but highly reproducible increase in the transconjugant colony counts (TCC; ca. > or = 1 log), when compared with that of the controls without DNase. Transconjugants were also obtained when the same live donors were substituted with the UV-killed ones although the TCC was very low initially. Contrarily, donors treated with DNA-intercalating agents, e.g. acridine orange or ethidium bromide, resulted in a complete failure to produce transconjugants. There was a quantitative relationship between the DNase used on donors and levels of DNA sugars/nucleotides/DNA, which possibly resulted from interaction between the DNase and DNA being present/produced on the donor surface. This may be indicative of what may actually happen in the donor-recipient mixtures in the conjugation test proper, where the recipient DNase may activate a donor DNA production cycle. The evidences presented did not suggest that the donor DNA in the conjugation process is actually vestibuled through any intercellular conjugation passages, and is susceptible to the action of DNase or the intercalating dyes.

Animals↗
PubMed1999

Synthesis and antitumor activity of goniofufurone analogues.

Synthesis and antitumor activity of goniofufurone analogues 15, 16, 17, 33, and 46 is reported. Key step in the synthesis is Pd (II) mediated oxidative cyclisation of vinyl-(hydroxy) furans 18, 19 to the corresponding lactols 32, 43. Cytotoxicities of 15, 16, 17, 33, and 46 tested against six human cancer cell lines are reported. Change of stereochemistry at C-5, C-6 and C-7 position of goniofufurone (1) did not enhance the cytotoxicities significantly.

Antineoplastic Agents↗
PubMed1999

Potentiality of tricyclic compound thioridazine as an effective antibacterial and antiplasmid agent.

Thioridazine (Th), which is therapeutically used in psychiatric patients, was found to possess conspicuous antimicrobial activity when tested against 316 strains belonging to a number of Gram positive and Gram negative bacteria. Although Staphylococcus aureus, Vibrio chloerae and V. parahaemolyticus were found to be most sensitive, Th was highly bactericidal against S. aureus and bacteriostatic for vibrios and other Gram negative organisms. In the study of antiplasmid/curing effect of Th on twelve multiply antibiotic and Th resistant bacteria, it was observed that elimination of R plasmids was facilitated by choice of optimal concentration of Th. Significant elimination of single and combined antibiotic resistance occurred in E. coli and Shigella flexneri and not in S. aureus.

Anti-Bacterial Agents↗
PubMed1999

A comparative study on the Mitsuda type response to antigens of chemoautotrophic nocardioform bacteria and to standard lepromin in leprosy patients.

Anergy, or contrarily, Mitsuda-type responses towards 4 chemoautotrophic nocardioform antigens (CAN-Ags) and a control standard lepromin were tested in 73 LL, TT and borderline cases of leprosy. The antigens injected per patient varied from a maximum of 5 to a minimum of 2. Complete anergy to CAN-Ags was seen in 92/92 instances tested on 24 LL cases. The anergy was weakly modified or unmodified in 3 other LL cases which had been vaccinated before. Concurrent studies with the same antigens tested on 33 TT cases showed clear-cut, dose-dependent, Mitsuda-type late responses in 80/81 instances. The CAN bacteria, therefore, despite their origin from different unrelated leprous human, mouse footpad (MFP) and armadillo tissues, appeared to be identical with each other and also probably related to the leprosy bacillus, on the basis of these parameters.

Actinomycetales↗
PubMed1998

Antibacterial activity of the antiinflammatory agent diclofenac sodium.

Antimicrobial property of ten antiinflammatory drugs was tested with eleven sensitive bacteria belonging to both Gram positive and Gram negative types. Since most of the bacteria were moderate to highly sensitive to diclofenac (Dc), this compound was tested in vitro against 397 bacteria, most of which were inhibited by Dc at 50-100 micrograms/ml level. When tested in vivo, Dc at 1.5 and 3.0 micrograms/g body weight of a Swiss strain of white mice, could significantly protect the animals challenged with 50 MLD of Salmonella typhimurium NCTC 74. According to chi 2 test the in vivo data were highly significant (P < 0.001).

Animals↗
PubMed1997

Earliest ultrasound finding of implantation?

PURPOSE: Our purpose was to verify our earlier observation of an altered endometrial echo character during the periimplantation period, signifying the earliest detection of implantation by ultrasound. METHODS: The transvaginal ultrasound study used a 7.5-MHz probe on day 6 following preembryo transfer. RESULTS: Of 31 embryo transfers studied. 8 (25.8%) were positive for this sign on day 6, whereas 9 patients later showed a gestational sac, giving an accuracy of this sign of 88.8% (8 of 9). CONCLUSIONS: The normal secretory-phase endometrium shows a typical, evenly distributed hyperechogenecity described earlier by Hackeloer (1). In some cases of proliferative phases, too, this echo pattern has been reported by others (2, 3), and observed by us in stimulated and unstimulated cycles, and has been named type A endometrium by Gonen et al. (4) Both these varieties are seen to have an even, unbroken outline at the anterior and posterior myometrial-endometrial interphase. We report what we believe to be the earliest ultrasound picture of implantation, resembling this variety of endometrial echo but having an irregular outline (Fig. 2).

Chorionic Gonadotropin↗
PubMed1997

Antimicrobial potentiality of a new beta-lactum antibiotic fosfomycin.

Antimicrobial action of penicillin and some of its derivatives including fosfomycin was studied with respect to 225 strains of Gram-positive and Gram negative bacteria. Fosfomycin was found to possess somewhat less activity against Staphylococcus aureus compared with other penicillins; however, it showed powerful activity towards Escherichia coli, Klebsiella spp. and Proteus mirabilis.

Anti-Bacterial Agents↗
PubMed1997

Studies on antimicrobial effect of the antihistaminic phenothiazine trimeprazine tartrate.

The antibacterial and bactericidal activities of the antihistamine trimeprazine were studied against 243 strains of bacteria which included both Gram positive and Gram negative types. The susceptibility of these bacterial strains to trimeprazine was assessed by determining their minimum inhibitory concentration (MIC) which was found to be between 10 and 100 micrograms/ml. Nineteen strains of Staphylococcus spp. and Salmonella spp. were trimeprazine. Most of the strains belonging to Bacillus spp. and Salmonella spp. were inhibited by less than 100 micrograms/ml. Trimeprazine could also inhibit strains of Shigella spp. Vibrio cholerae and V. parahaemolyticus at 10-100 micrograms/ml. Strains of klebsiella, proteus, pseudomonas and citrobacter were moderately sensitive to trimeprazine. In in vivo studies it was seen that when trimeprazine was used at a concentration of 0.75 and 0.4 micrograms/gm body weight of the mouse both levels offered significant protection to Swiss mice challenged with 50LD50 of virulent strain of S. typhimurium 74. Statistical analysis of the data was found to be significant, p < 0.001 according to chi 2 test.

Animals↗
PubMed1996

Electron microscopic characteristics of actinomycetic agents having aetiological association with human leprosy and epizootic ulcerative syndrome of fish.

The transmission electron microscopic (TEM) studies of the human leprosy derived chemoautotrophic nocardio-form (CAN) bacteria and EUS derived CAN bacteria showed presence of double contoured cell-walls consisting of an electron transparent and a dense layer. The fibrillar structures on the surface of these CAN bacterial cells also suggested their similarity to the human tissue derived Mycobacterium leprae cells. These EM studies further revealed mycelial and coccoid bodies in all these bacteria as was observed originally.

Actinomycetales↗