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Biomedical subjects

A Ganguli

Publications and source records attributed to A Ganguli.

At least 19 recordsLinked to original sources
PubMed2005

Bacterial adhesion to bisphosphonate coated hydroxyapatite.

Staphylococcus aureus (S. aureus) is commonly associated with microbial infection of orthopaedic implants. Such infections often lead to osteomyelitis, which may result in failure of the implant due to localised bone destruction. Bacterial adhesion and subsequent colonisation of the device may occur as a consequence of contamination during surgery, or by seeding from a distant site through the blood circulation. Coating of the hydroxyapatite (HA) ceramic component of artificial hip joints with the bisphosphonates clodronate (C) and pamidronate (P) has been proposed as a means to minimise osteolysis and thereby prevent loosening of the implant. However, the effect of the bisphosphonate coating on bacterial adhesion to the HA materials must be determined before this approach can be implemented. In this study coated HA materials were incubated with the S. aureus and the number of adherent bacteria determined using the Modified Vortex Device (MVD) method. The number of bacteria adherent to the P coated HA material was significantly greater than that adherent to uncoated HA (60-fold increase) or to the C coated HA (90-fold increase). Therefore, even though earlier studies suggested that P bound to HA may improve osseointegration, the results presented would suggest that the use of this coating may be limited by the potential increased susceptibility of the coated device to infection.

Bacterial Adhesion↗
PubMed2003

Drug-induced kidney diseases.

Drug-induced kidney disease constitutes an important cause of acute renal failure and chronic kidney disease in present day clinical practice. Different classes of drugs, by virtue of immunological mechanisms or direct toxicity initiate certain stereotyped renal responses. For most patients suffering from drug-induced nephropathy common risk factors which precipitate the adverse effects include: old age, volume -depleted state, pre-existing renal dysfunction and coexisting use of other nephrotoxins. Although it is impossible to present all the drugs causing renal disease, a few prototype drugs are mentioned. In a case of undiagnosed renal disease a possibility of drug-induced renal failure should be kept as the prompt removal of the drug and supportive management can reverse the renal dysfunction to a large extent.

Humans↗
PubMed2002

The interactions of bisphosphonates in solution and as coatings on hydroxyapatite with osteoblasts.

Aseptic loosening is one of the major causes of failure of artificial hip joints, and it can occur for several reasons, including osteolysis of the bone tissue in response to stress shielding or cellular reactions to wear debris. Any treatment of the prosthesis which could minimize the osteolytic response of bone tissue may be able to extend the life-time of the implant. Bisphosphonates are potent inhibitors of osteoclastic bone resorption, and they bind avidly to hydroxyapatite (HA). Coating the prostheses with bisphosphonates may therefore inhibit osteolysis. We have investigated the potential for this approach by determining whether bisphosphonates interact with osteoblasts in vitro. The effects of pamidronate (P), clodronate (C), and etidronate (E) in solution and when coated onto HA were investigated. P inhibited protein and collagen syntheses potently when in solution, but not after being bound to HA. When bound to HA, both P and C increased DNA, protein and collagen syntheses of osteoblasts and may encourage the osseointegration of implants. The pharmacological effects of the bisphosphonates studied altered dramatically after binding to HA. This must be fully investigated before this approach to prolonging prostheses stability can be evaluated.

Journal Article↗
PubMed2001

Bioremediation of toxic chromium from electroplating effluent by chromate-reducing Pseudomonas aeruginosa A2Chr in two bioreactors.

The chromate-reducing ability of Pseudomonas aeruginosa A2Chr was compared in batch culture, with cells entrapped in a dialysis sac, and with cells immobilized in an agarose-alginate film in conjunction with a rotating biological contactor. In all three systems, the maximum Cr(VI) reduction occurred at 10 mg Cr(VI)/l. Whereas at 50 mg Cr(VI)/l concentration, only 16% of the total Cr(VI) was reduced, five spikings with 10 mg chromate/l at 2-h intervals led to 96% reduction of the total input of 50 mg Cr(VI)/l. Thus maximum Cr(VI) reduction was achieved by avoiding Cr(VI) toxicity to the cells by respiking with lower Cr(VI) concentrations. At 10 mg Cr(VI)/l, the pattern of chromate reduction in dialysis-entrapped cells was almost similar to that of batch culture and 86% of the bacterially reduced chromium was retained inside the dialysis sac. In electroplating effluent containing 100 mg Cr(VI)/l, however, the amount of Cr(VI) reduced by the cells immobilized in agarose-alginate biofilm was twice and thrice the amount reduced by batch culture and cells entrapped in a dialysis sac, respectively.

Biodegradation, Environmental↗
PubMed2001

Arabidopsis and the heat stress transcription factor world: how many heat stress transcription factors do we need?

Sequencing of the Arabidopsis genome revealed a unique complexity of the plant heat stress transcription factor (Hsf) family. By structural characteristics and phylogenetic comparison, the 21 representatives are assigned to 3 classes and 14 groups. Particularly striking is the finding of a new class of Hsfs (AtHsfC1) closely related to Hsf1 from rice and to Hsfs identified from frequently found expressed sequence tags of tomato, potato, barley, and soybean. Evidently, this new type of Hsf is well expressed in different plant tissues. Besides the DNA binding and oligomerization domains (HR-A/B region), we identified other functional modules of Arabidopsis Hsfs by sequence comparison with the well-characterized tomato Hsfs. These are putative motifs for nuclear import and export and transcriptional activation (AHA motifs). There is intriguing flexibility of size and sequence in certain parts of the otherwise strongly conserved N-terminal half of these Hsfs. We have speculated about possible exon-intron borders in this region in the ancient precursor gene of plant Hsfs, similar to the exon-intron structure of the present mammalian Hsf-encoding genes.

Amino Acid Sequence↗
PubMed1999

Survival and chromate reducing ability of Pseudomonas aeruginosa in industrial effluents.

The ability of a chromate-reducing Pseudomonas aeruginosa strain, isolated from tannery effluent, to survive and reduce chromate in the effluent of a tannery and an electroplating unit was evaluated. The test strain survived in the native tannery effluent but numbers fell sharply in the native electroplating effluent. Supplementation with a carbon (C), nitrogen (N) and phosphorus (P) source supported bacterial multiplication and chromate reduction in both types of effluents with almost equal efficiency. Chromate reduction, however, was not observed in the absence of C, N or P supplement, or in the chromate-reducing strain.

Biodegradation, Environmental↗
PubMed1998

Duplication of insertion element IS50 associated with Tn5 transposition in Azospirillum brasilense.

The characterization of a DNA fragment with a Tn5 insertion in a regulatory nif gene of Azospirillum brasilense is reported. Restriction endonuclease mapping, Southern hybridization with a Tn5 probe, and nucleotide sequencing revealed that IS50 had duplicated in Tn5. The duplication of an IS50 element suggests the occurrence of a replicative mechanism of transposition. A strategy, based on the bacterial ability of homologous recombination that was used to precisely eliminate Tn5 along with the duplicated IS50 element, is presented.

Azospirillum brasilense↗
PubMed1990

Comparative morphometric evaluation of permanent mandibular molar dentition of plain and hilly (Momba/Mongoloid) populations of eastern Indian states.

Morphometric comparative field studies were conducted of the permanent molars of plain people of Eastern India and Momba/Mongoloid population of eastern-most hill people known as Momba and claimed as Mongoloid. The data obtained was found very useful to distinguish and identify the two great neighbouring Asian people comprising one third of the total World human population.

Adult↗