Sathiyavedu Thyagarajan Santhiya

INHIBITION OF GENOTOXICITY BY SAFFRON (CROCUS SATIVUS L.) IN MICE

Experiments were carried out to ascertain whether or not saffron (dried stigmas of Crocus sativus L.), a commonly used agent for flavoring and coloring food can exert modulatory effects on the in vivo genotoxicity of cisplatin (CIS), cyclophosphamide (CPH), mitomycin C(MMC) and urethane (URE). For this purpose, Swiss albino mice were pretreated for five consecutive days with three doses (20, 40 and 80 mg/kg body weight) of the aqueous extract of saffron. Genotoxic effects were assessed in the mouse bone marrow micronucleus test. The results obtained suggest that pretreatment with saffron can significantly inhibit the genotoxicity of CIS, CPH, MMC and URE. This inhibitory effect was not always dose-dependent. In addition, the hepatic glutathione S-transferase (GST) activity was assessed in the control and treated animals. No significant change in GST activity was observed after pretreatment with saffron alone. Treatment with the genotoxins alone significantly inhibited GST activity. Saffron pretreatment attenuated the inhibitory effects of the genotoxins on GST activity.

CRYBA4, a Novel Human Cataract Gene, Is Also Involved in Microphthalmia

Genetic analysis of a large Indian family with an autosomal dominant cataract phenotype allowed us to identify a novel cataract gene, CRYBA4. After a genomewide screen, linkage analysis identified a maximum LOD score of 3.20 (recombination fraction [theta] 0.001) with marker D22S1167 of the beta -crystallin gene cluster on chromosome 22. To date, CRYBA4 was the only gene in this cluster not associated with either human or murine cataracts. A pathogenic mutation was identified in exon 4 that segregated with the disease status. The c.317T-->C sequence change is predicted to replace the highly conserved hydrophobic amino acid phenylalanine94 with the hydrophilic amino acid serine. Modeling suggests that this substitution would significantly reduce the intrinsic stability of the crystalline monomer, which would impair its ability to form the association modes critical for lens transparency. Considering that CRYBA4 associates with CRYBB2 and that the latter protein has been implicated in microphthalmia, mutational analysis of CRYBA4 was performed in 32 patients affected with microphthalmia (small eye). We identified a c.242T-->C (Leu69Pro) sequence change in exon 4 in one patient, which is predicted here to disrupt the beta -sheet structure in CRYBA4. Protein folding would consequently be impaired, most probably leading to a structure with reduced stability in the mutant. This is the first report linking mutations in CRYBA4 to cataractogenesis and microphthalmia.

Effect of Spirulina fusiformis on cyclophosphamide and mitomycin-C induced genotoxicity and oxidative stress in mice

Spirulina fusiformis was tested for its possible in vivo protective effects against cyclophosphamide (CP) and mitomycin-C (MMC) induced genotoxicity and oxidative stress in mice. Pre-treatment with S. fusiformis (250, 500 and 1000 mg kg(-1), p.o., daily for 5 days) significantly reduced the chromosomal damage and lipid peroxidation with concomitant changes in antioxidants and detoxification systems. All the three tested doses were effective in exerting a protective effect against CP and MMC.

Protective effect of saffron (Crocus sativus L.) aqueous extract against genetic damage induced by anti-tumor agents in mice

The genotoxic potential of anti-tumor drugs limits their efficacy in the treatment of cancers. Since ancient times, saffron (dried stigmas of Crocus sativus L.) has been used as a spice and medicinal herb. Saffron is a rich source of carotenoids and is known for its anti-cancer and antitumor properties. The present study was designed to ascertain the chemoprotective potential of saffron against the genotoxicity of three well-known anti-tumor drugs-cisplatin (CIS), cyclophosphamide (CPH) and mitomycin C (MMC)-using comet assay. Three doses of saffron (20, 40 and 80 mg/kg b.w.) were orally administered to mice for five consecutive days prior to the administration of anti-tumor drugs under investigation. Pre-treatment with saffron significantly inhibited anti-tumor drugs induced cellular DNA damage (strand breaks) as revealed by decreased comet tail length, tail moment and percent DNA in the tail. These findings, together with our previous results, suggest a potential role for saffron as an anti-genotoxic, anti-oxidant and chemopreventive agent and could be used as an adjuvant in chemotherapeutic applications.

An MIP/AQP0 mutation with impaired trafficking and function underlies an autosomal dominant congenital lamellar cataract

Autosomal dominant congenital cataracts have been associated with mutations of genes encoding several soluble and membrane proteins. By candidate gene screening, we identified a novel mutation in MIP (c.494 G > A) that segregates with a congenital lamellar cataract within a south Indian family and causes the replacement of a highly conserved glycine by aspartate (G165D) within aquaporin0 (AQP0). Unlike wild type AQP0, expression of AQP0-G165D in Xenopus oocytes did not facilitate swelling in hypotonic medium. In transfected HeLa cells, wild type AQP0 localized at the plasma membrane while AQP0-G165D was retained within the secretory pathway, and localized mainly within the endoplasmic reticulum. These results suggest that mutation of this conserved glycine residue leads to improper trafficking of AQP0-G165D and loss of water channel function. They emphasize the importance of AQP0 for maintenance of lens transparency and identify a critical residue that is conserved among aquaporins, but has not previously been associated with disease-associated replacement.

Reduced levels of γ-crystallin transcripts during embryonic development of murine Cat2 nop mutant lenses

Abstract• Background: From previous experiments it is known that the murine dominant cataract mutants carrying the gene Cat2 have a decreased content of γ-crystallin-specific transcripts in the juvenile lenses, when the cataract is completely expressed. Moreover, the mutant locus has been mapped recently to chromosome 1, closely linked to the γE-crystallin gene (map distance 0.3±0.3 cM). In the present paper we describe the phenotypic changes and the γ-crystallin expression in embryonic lenses of the Cat2nop mutants as an example for the Cat2 allelic series. •. Methods: The technique of in situ hybridization was applied using a probe from the murine γD-crystallin gene, and, for control, from the murine αA-crystallin gene. Simultaneously, a series of lens sections was examined histologically. • Results: The presence of γ-crystallin mRNA was demonstrated from embryonic day 13.5 (E13.5) onward, but in the mutants to a lower extent than in the wild-type lenses. However, the first morphological abnormality in the mutant lenses was observed as swelling of lens fibers at day E15.5. Progressive degeneration of the lens core followed, leading to a cataracta immatura. • Conclusion: The reduced level of γ-crystallin transcripts is the first alteration observable during the embryonic development of the Cat2 mutant lenses; it precedes the morphological changes. This result represents an additional line of argument that the γ-crystallin genes may be the target of the mutation in the Cat2 mice.

Chromosomal Abnormalities in 979 Cases of Amenorrhea: A Review

Abstract Primary amenorrhea refers to absence of spontaneous menarche even after the age of 16 while in secondary amenorrhea, the condition follows a period of normal menstruation. Cytogenetic data in cases with primary (n=852) (PA) or secondary (n=127) amenorrhea (SA) investigated at the Department of Genetics, Dr. A.L. Mudaliar Post Graduate Institute of Basic Medical Sciences, University of Madras, during the 25-year period 1979 to 2004 was reviewed. Routine GTG-band analysis of metaphases from peripheral blood leucocytes revealed the incidence of chromosomal abnormalities in individuals with PA and SA to be 25.82% and 7.09% respectively. In addition to numerical abnormalities, the various structural aberrations of the X chromosome encountered were deletions, isochromosome for the long arm, translocations and ring chromosomes. Ascertainment of the karyotype aided in confirmation of the provisional diagnosis, a better phenotype-genotype correlation to understand clinical heterogeneity and in genetic counseling.

Genotoxic and antigenotoxic effects of Hemidesmus indicus R. Br. root extract in cultured lymphocytes

AIM OF THE STUDY The genotoxic and antigenotoxic potential of the ethanolic extract of Hemidesmus indicus roots were evaluated in cultured human lymphocytes using cisplatin as the positive mutagen. MATERIALS AND METHODS Cytogenetic damage and cytotoxicity were determined in cells exposed to different doses of the extract, ranging from 2 to 32 microg/ml of culture medium, either alone or together with cisplatin. RESULTS There was a significant reduction in cisplatin-induced frequencies of sister chromatid exchanges, chromosome aberrations and micronucleated binucleate cells at the lower concentrations of 4 and 8 microg/ml (P<0.05). However, the extract by itself reduced the proliferative rate index, mitotic index and cytokinesis-block proliferative index (P<0.05). Further, a significant increase in the percentage of chromosome aberrations was noticed at the higher concentrations. CONCLUSION Hemidesmus indicus root extract possesses significant genoprotective effect at the lower concentrations although it is cytotoxic and probably genotoxic at higher doses.

Protective effect of Hemidesmus indicus R.Br. root extract against cisplatin-induced cytogenetic damage in mouse bone marrow cells.

The aqueous extract of Hemidesmus indicus roots was investigated for its in vivo antigenotoxic effect against cisplatin-induced cytogenetic damage. Swiss albino mice were administered with various doses of the extract either singly (50, 100 and 200 mg/kg body weight) or as split doses (10, 20 and 40 mg/kg bw/day) for five consecutive days by oral gavage. As endpoints, chromosome aberrations, micronuclei in polychromatic erythrocytes, mitotic index and PCE/NCE ratio were estimated. The extract protected the bone marrow cells from cisplatin-induced genotoxicity in an inverse dose-dependent manner. However, the extract was cytotoxic at all doses. But, under split dose regime it conferred a higher level of genoprotection and was not cytotoxic at the lower two doses. The presence of saponins, tannins, phenols, terpenoids, flavonoids and coumarins in the crude extract could explain these effects.

X,7 TRANSLOCATION IN AN INDIAN WOMAN WITH HYPERGONADOTROPIC AMENORRHEA-A CASE REPORT

Translocations involving X chromosome and an autosome are rather rare due to the associated infertility in men and subfertility in women. X-autosome translocations are frequently associated with primary or secondary ovarian failure and at times Turner syndrome-like features if there is an involvement of the critical region of Xq13-q26. A 19-year-old proposita with a complaint of amenorrhea was found to have hypoplastic uterus and streak ovaries. Hormonal profile revealed hypergonadotropic hypogonadism. Chromosomal analysis of 25 conventionally stained metaphases revealed the karyotype to be 46,X,t(X;7)(q13;p15)de novo. This rare finding is the first report from India, to the best of our knowledge. She also exhibited the maternally inherited heteromorphic variant of chromosome 21. The occurrence of t(X;7) in the proposita with hypergonadotropic amenorrhea confirms the role of X-autosome translocations in ovarian dysfunction.