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Biomedical subjects

G Talukder

Publications and source records attributed to G Talukder.

At least 37 records · Page 2Linked to original sources
PubMed1996

Clastogenic activity of pure chlorophyll and anticlastogenic effects of equivalent amounts of crude extract of Indian spinach leaf and chlorophyllin following dietary supplementation to mice.

Dietary consumption of green vegetables has been associated with protection against mutagenic and clastogenic activity of genotoxicants. Chlorophyll, being present in all green plants, had earlier been suggested to be the principal factor involved. Mice were administered (i) crude aqueous extract of leaf of Indian spinach, Beta vulgaris L. var.benghalensis Hort., and equivalent amounts of (ii) chlorophyll extracted from the leaf; (iii) purified chlorophyll, (iv) chlorophyllin, a sodium-copper derivative of chlorophyll; daily for 7 days. On day 7, one set of mice from each treatment was administered potassium dichromate-a known metallic clastogen. The mice were sacrificed after 24 hours. Chromosome preparations were made from bone marrow following the usual colchicine-air dry-Giemsa schedule. The cytogenetic endpoints scored were chromosomal aberrations and damaged cells. Crude leaf extract and chlorophyllin were nonclastogenic and reduced the clastogenic effects of potassium dichromate to the control distilled water level. Chlorophyll alone, whether extracted from the leaf or obtained in commercially purified form, was clastogenic and could reduce the effects of the chromium salt only to its own level. The protective action of the crude leaf extract may be attributed to the total effect of the interaction between the different components within the leaf extract, in which the clastogenicity of chlorophyll had been neutralized.

Animals↗
PubMed1996

Effects of crude garlic extract on mouse chromosomes in vivo.

Three concentrations (25, 50 and 100 mg/kg body weight) of fresh garlic (Allium sativum L.) were administered daily by gavage to Swiss albino mice for different durations up to 60 days. These concentrations had been observed to protect significantly against effects of known clastogens. The endpoints scored were frequencies of chromosomal aberrations and damaged cells induced in bone marrow preparations. These parameters were found to be directly dose dependent and after an initial enhancement at 7 days, were reduced following prolonged exposure for 30 and 60 days to the low level observed at 24 hr. Therefore, administration of a low concentration of garlic extract daily is suggested for at least 30 days to obtain the maximum benefit of the extract in protecting against the clastogenic effects of known genotoxicants.

Administration, Oral↗
PubMed1995

On the mechanism of modulation of transient outward current in cultured rat hippocampal neurons by di- and trivalent cations.

1. The mechanisms of Zn2+ modulation of transient outward current (TOC) were studied in cultured rat hippocampal neurons, using the voltage-clamp technique. In the presence of micromolar concentrations of external Zn2+, the voltage dependence of activation and inactivation was shifted to more positive membrane potentials. The gating of TOC was unaltered by internal application of Zn2+. The effect of Zn2+ were not mimicked by external Ca2+, except at very high concentrations (> 10 mM). 2. The modulatory effects of external Zn2+ on TOC gating were not reproduced, antagonized, nor enhanced by lowering external ionic strength, indicating that modulation by Zn2+ does not occur via screening of bulk surface negative charge. 3. A range of other divalent and trivalent metal ions also was studied, and several were found to modulate the transient outward current when added to the extracellular medium. In particular, Pb2+, La3+, and Gd3+ were potent modulators, showing activity in the low micromolar range. Other metal ions were weaker modulators (e.g., Cd2+) or were without activity at the concentrations tested (Fe3+, Cu2+, Ni2+). 4. The same range of ions also was tested on the delayed rectifier K+ current in cultured rat hippocampal neurons. None of the ions studied had significant effects on delayed rectifier gating, although high (> or = 100 microM) concentrations of Pb2+ and La3+ reduced maximal current amplitude, suggesting the possibility of channel block.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Chlorophyll and chlorophyllin as modifiers of genotoxic effects.

Reports on an inverse relationship between the consumption of fresh vegetables and human gastrointestinal cancer have been followed by screening for the protective activity of a large number of plant extracts, including leafy vegetables. Chlorophyll is ubiquitous in all green plant parts. Chlorophyllins are derivatives of chlorophyll in which the central magnesium atom is replaced by other metals, such as cobalt, copper or iron. An attempt has been made in this article to review the relative efficacy of chlorophyll and chlorophyllin in modifying the genotoxic effects of various known toxicants.

Animals↗
PubMed1993

Modification of clastogenicity of three known clastogens by garlic extract in mice in vivo.

The anticlastogenic activity of crude extract of garlic (Allium sativum L.) was studied in bone marrow cells of mice. Male laboratory-bred Swiss albino mice were given one of three concentrations of the freshly prepared extract (100 mg, 50 mg, and 25 mg/kg body weight) as a dietary supplement by gavage for 6 consecutive days. On the seventh day the mice were administered a single acute dose of two known clastogens, mitomycin C(1.5 mg/kg) and cyclophosphamide (25 mg/kg) or sodium arsenite (2.5 mg/kg), simultaneously with garlic extract. After 24 hr, chromosome preparations were made from the bone marrow cells. The endpoint studied were chromosomal aberrations and damaged cells. Garlic extract alone induced a low level of chromosomal damage. The clastogenicity of all three mutagens were reduced significantly in the animals which had been given garlic extract as dietary supplement. The extent of reduction was different for the three clastogens and may be attributed to the interaction with the different components of the extract.

Analysis of Variance↗
PubMed1993

Differential protection of chlorophyllin against clastogenic effects of chromium and chlordane in mouse bone marrow in vivo.

The anticlastogenic activity of sodium-copper-chlorophyllin was tested against two known clastogens, chromium(VI) oxide and the pesticide chlordane, both of which occur as environmental toxicants. The chemicals were administered to male Swiss albino mice by gavage and chromosomes were studied from bone marrow cells 24 h after the exposure, following colchicine-air drying-Giemsa preparation. The end-points screened were the frequencies of chromosomal aberrations and damaged cells. The clastogenic effects induced by chromium in aqueous solution (20 mg/kg body weight) were reduced to a significant level by chlorophyllin (1.5 mg/kg body weight), when administered both before and simultaneously with the toxicant. The effects of chlordane in olive oil (10 mg/kg body weight) were, however, not reduced by the administration of chlorophyllin (1.5 and 3 mg/kg body weight).

Analysis of Variance↗
PubMed1993

Zinc modulates transient outward current gating in hippocampal neurons.

The actions of zinc ions (Zn2+) on transient outward current (TOC) were studied in cultured embryonic rat hippocampal neurons and adult guinea pig CA1 neurons acutely isolated from hippocampal slices. Zn2+ (1-1000 microM) shifted both the activation and inactivation curves for the TOC in the depolarizing direction. These effects of Zn2+ were modeled, assuming a single class of binding sites for Zn2+, yielding apparent dissociation constants for Zn2+ between 10 and 35 microM. In addition, the activation kinetics of the TOC were significantly slowed by Zn2+; deactivation was slowed at the highest concentrations of Zn2. These complex actions of Zn2+ on the TOC are likely to delay repolarization and promote spontaneous activity, resulting in action potential prolongation and hyperexcitability of hippocampal neurons.

Action Potentials↗
PubMed1993

Chromosomal damage in lymphocytes of controls and patients with autosomal and sex-chromosomal disorders.

The frequency of chromosomal aberrations was studied in lymphocytes from karyotypically abnormal patients and normal donors. There was no difference between normal females and Down's syndrome female patients. Male Down's syndrome patients showed a significant increase in aberrations of normal diploid male lymphocytes and a significant difference was observed in male and female Down's syndrome patients. Sex-chromosomally abnormal patients, both X and Y chromosome deficient, showed elevated chromosomal aberrations compared with age and sex-matched normal diploid cells.

Adolescent↗
PubMed1992

Chromosomal alterations and sister chromatid exchanges induced by zirconium oxychloride in human lymphocytes in vitro with relation to age of donors.

Aqueous solutions of zirconium oxychloride were added to human peripheral blood lymphocyte culture. Cultures were set up from healthy donors of both sexes belonging to age groups of 0-10, 11-20, 21-30, 31-40, 41-50 and 51-60 years. Airdried Giemsa schedule was followed for preparation of chromosomal aberrations and micronuclei count. Flourescence plus Giemsa staining techniques were applied for the study of sister chromatid exchange. The endpoints screened were chromosome and chromatid breaks, dicentrics and rearrangements. The frequencies of chromosomal aberrations and sister chromatid exchanges induced were compared between the samples of different age groups. The frequency of CA could not be related to age of the donor. However, the frequency of SCE increased with increase in age of female donor.

Adolescent↗
PubMed1992

Interaction between two group IV metals--lead and zirconium--in bone marrow cells of Mus musculus in vivo.

The interaction between two group IV metals, the highly toxic lead and the relatively inactive and low toxic zirconium, was studied in the bone marrow chromosomes of Mus musculus in vivo. Low and high doses of zirconium oxychloride were fed orally to the experimental mice (i) 2 h before, (ii) 2 h after or (iii) together with different doses of lead nitrate. Protection against lead-induced clastogenicity was observed only when the lower dose of zirconium was administered prior to lead. All other combinations gave an additive or synergistic effect as was seen by significant increases in the frequencies of chromosomal aberrations.

Animals↗
PubMed1992

Comparison of the clastogenic effects of antimony trioxide on mice in vivo following acute and chronic exposure.

Antimony trioxide (Sb2O3), in aqueous suspension, was administered by gavaging to mice and monitored for chromosomal aberrations in bone marrow and sperm head abnormalities in germ cells. Acute exposure to the doses followed by observations after 6, 12, 18 and 24 h did not show any clastogenic effects. Chronic exposure daily to different doses for periods up to 21 days induced chromosomal aberrations in bone marrow. The frequencies were dose-dependent to a significant extent but no relationship could be seen with the sex of the animal. The findings indicate the harmful effects of cumulative exposure for prolonged periods to Sb2O3, which is being increasingly used in various industries.

Administration, Oral↗
PubMed1992

Modifying effect of iron on lead-induced clastogenicity in mouse bone marrow cells.

Essential trace elements such as iron (Fe) are known to interact with nonessential metals like lead (Pb), influencing its metabolism. Ferric chloride and lead nitrate were administered intraperitoneally to Swiss albino mice Mus musculus singly and successively, with or without a time gap of 1 h, to study the degree of protection, if any, afforded by iron against the clastogenic effects induced by Pb in bone marrow cells. A decrease in the frequency of lead-induced chromosomal aberrations was observed when Fe was given together with or prior to Pb administration.

Animals↗
PubMed1992

Zirconium. An abnormal trace element in biology.

The action of Zirconium (Zr) on biological systems presents an enigma. It is ubiquitous, being present in nature in amounts higher than most trace elements. It is taken up by plants from soil and water and accumulated in certain tissues. The entry into animal systems in vivo is related to the mode of exposure and the concentration in the surrounding environment. Retention is initially in soft tissues and then slowly in the bone. The metal is able to cross the blood brain-barrier and is deposited in the brain and the placental barrier to enter milk. The daily human uptake has been known to be as high as 125 mg. The level of toxicity has been found to be moderately low, both in histological and cytological studies. The toxic effects induced by very high concentrations are nonspecific in nature. Despite the presence and retention in relatively high quantities in biological systems, Zr has not yet been associated with any specific metabolic function. Very little information is available about its interaction with the compounds of the genetical systems, such as nucleic acids. Apparently, the metal is neither an essential nor toxic element in the conventional sense. However, the increasing exposure to this element through its increasing use in new materials and following radioactive fallout, has increased the importance of the study of its effects on living organisms. The tetravalent nature of the ionic state and the high stability of the compounds formed are important factors that need to be considered, as also the accumulation of this element in the brain, reminiscent of the relationship between Al3+ and Alzheimer's disease.

Animals↗
PubMed1992

Relative protection given by extract of Phyllanthus emblica fruit and an equivalent amount of vitamin C against a known clastogen--caesium chloride.

Aqueous extracts of Phyllanthus emblica L. fruit and an equivalent amount of vitamin C were administered orally by gavage to laboratory-bred Swiss albino mice for 7 days in order to evaluate the protection afforded by the two extracts against clastogenic effects of different doses of caesium chloride (CsCl) on bone marrow cells of Mus musculus in vivo. Both pretreatments significantly reduced the frequency of chromosome aberrations induced by CsCl given at three different doses, indicating that vitamin C, an essential component of P. emblica extract, was the effective agent in protecting against the clastogenicity of the metal salt.

Animals↗
PubMed1992

Cytotoxic effects of antimony trichloride on mice in vivo.

Clastogenic effects of antimony trichloride, used in small industries, were monitored in laboratory bred white Swiss mice in vivo, following oral administration by gavaging, after 6, 12, 18 and 24 h. Chromosomal aberrations were principally breaks and damaged cells observed from bone marrow preparations. The frequencies of chromosomal aberrations were directly related to the dose used and were significantly higher than the control. The chemical did not alter the frequency of dividing cells to any significant level.

Administration, Oral↗