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M Varella-Garcia

Publications and source records attributed to M Varella-Garcia.

54 records · Page 3Linked to original sources
PubMed1997

Diminished tumorigenic phenotype after depletion of mitochondrial DNA.

Modulation of tumorigenicity has been considered to be a reflection of the (nuclear) genetic and cellular aberrations present in tumor cells. Recent studies have suggested that cytoplasmic elements can also contribute to the malignant phenotype of cancer, and that mitochondria may be important in this process. We, therefore, undertook a study to evaluate the effects of depletion of functional mitochondria on the tumorigenic phenotype. Brain and breast tumor cells were depleted of mitochondrial DNA [rho(-)] by treatment with ethidium bromide. These rho(-) respiratory-deficient cells showed a distinct change in the tumorigenic phenotype, including loss of ability to grow in an anchorage-independent fashion and, interestingly, a substantial increase in sensitivity to cytotoxic drugs (1,3-bis-chloroethyl-1-nitrosourea and cis-diamminedichloroplatinum(II)). Reversion to the tumorigenic phenotype was accomplished with transfer of normal mitochondria into the diminished tumorigenic rho(-) cells. No changes in expression of the apoptosis genes bcl-2 and bax, nor the drug resistance genes mdr1, mrp, or O6-alkyltransferase was found in any of the cell types (de novo, rho(-), or cybrid). Further, the type of cell death remained the same, i.e., cells with and without mitochondria underwent apoptosis in response to exposure to cytotoxic agents. Our results indicate that mitochondria/mitochondrial DNA play a direct role in modulating aspects of the tumorigenic phenotype, although they are not necessarily a sine qua non for apoptotic cell death. This is particularly interesting because most tumor tissues are more dependent upon glycolysis for energy production, rather than mitochondrially mediated oxidative phosphorylation. Creation of rho(-) cells will be useful to study the mitochondrial processes involved in tumorigenesis.

Animals↗
PubMed1996

Distinct 3p21.3 deletions in lung cancer and identification of a new human semaphorin.

Loss of chromosome 3p is a critical event in the pathogenesis of lung cancer. Overlapping homozygous 3p21.3 deletions in lung cancer cell lines involving GNAI2 were characterized and found to involve a region of genomic instability. A new widely expressed Semaphorin, H.SemaIV, was isolated from the GNAI2 deletion region. Reduced H.SemaIV expression allowed identification of additional cell lines with submicroscopic or larger deletions of the locus which occurred in a heterogeneous manner. We also demonstrate the presence of a distinct 3p21.3 homozygous deletion region, adjacent to the DNA mismatch repair gene, hMLH1, and identified deletions in direct tumors. This appears to represent one of the first demonstrations of homozygous deletions affecting 3p in direct lung tumors.

Amino Acid Sequence↗
PubMed1996

Complex cytogenetic rearrangement in a case of unicameral bone cyst.

Cytogenetic analysis of a unicameral bone cyst surgically resected in an 11-year-old boy revealed a highly complex clonal structural rearrangement involving chromosomes 4, 6, 8, 16, 21, and both 12. These findings reinforce the need for further studies on unicameral bone cysts to verify the frequency and to understand the significance of chromosome anomalies in this type of lesion.

Bone Cysts↗
PubMed1996

Karyotypic patterns of seven species of molossid bats (Molossidae, Chiroptera)

G- and C-banding patterns of seven species of the bat family Molossidae, Eumops glaucinus, E. perotis, Molossops abrasus, M. temminckii, Molossus ater, M. molossus, and Nyctinomops laticaudatus, were identified. Comparisons among the karyotypes of these species showed extensive homologies between E. perotis, M. ater, M. molossus, M. abrasus, and N. laticaudatus, demonstrating inter- and intrageneric conservatism, and a lesser degree of homologies in M. temminckii and E. glaucinus, reflecting intrageneric variation. Chromosomal variation was due to inversions, Robertsonian rearrangements, translocations, and variations in the location of constitutive heterochromatin and nucleolus organizer regions. The chromosome corresponding to No. 5 in the M. ater karyotype is discussed. We suggest that the Nyctinomops and Molossops karyotypes represent the primitive condition and that Molossus and Eumops have derived karyotypes.

Animals↗
PubMed1996

Expansion of bronchial epithelial cell populations by in vitro culture of explants from dysplastic and histologically normal sites.

The genetic and phenotypic properties of cells which ultimately give rise to carcinoma of the lung are not well defined in part because of unavailability of preneoplastic cells from well-characterized dysplastic sites. In order to expand bronchial epithelial cell populations from patients at high risk for lung cancer, endobronchial biopsy specimens were explanted onto collagen- and fibronectin-coated dishes and cultured in serum-free, chemically defined media. One hundred forty-nine biopsy pairs were obtained from smokers and from healthy volunteers for culture and histologic evaluation. The histologic appearances of mucosa adjacent to the site of the cultured biopsies ranged from normal through varying degrees of noninvasive squamous dysplasia to invasive carcinoma. Confluent monolayers of pure epithelial cells were obtained from 68% of the cultured explants. Sites exhibiting high-grade dysplasia were 51% more likely to yield successful cultures than sites exhibiting normal histology (13 of 14 cultures successful versus 52 of 83 cultures successful, P < 0.02). Cultures had a maximum proliferative life span of 81 days and none of the cultures spontaneously became immortalized. Immunolabeling studies revealed that all cultured epithelial cells, regardless of the in situ histologic appearances of the mucosa at the biopsy site, strongly expressed keratin and epidermal growth factor receptor, weakly expressed transferrin receptor and human folate receptor, and were negative for neural cell adhesion molecule and human leukocyte antigen DR (HLADR). Ploidy and karyotypic analyses were performed in a limited number of explants from normal and dysplastic sites and all were found to be diploid without karyotypic abnormality. We conclude that pure bronchial epithelial cell populations can be routinely expanded from histologically normal and dysplastic sites by tissue culture of biopsy explants and that the expanded cell populations may represent a library of normal and preneoplastic cells which are suitable for immunophenotypic, ploidy, genetic, or functional analyses.

Bronchi↗
PubMed1992

Sister chromatid exchanges and chromosome aberrations in lymphocytes of nurses handling antineoplastic drugs.

Chromosomal aberrations (CA) and sister-chromatid exchanges (SCE) were investigated in peripheral lymphocytes of 15 nurses and nurse's aides handling cytostatic agents in hospital oncology units. Significantly increased frequencies were noted for both CA and SCE rates when the exposed individuals were compared with 15 nurses working in other hospital units and to a control sample matched by sex and age. This points to the need for emphasizing protective measures in the handling of anti-neoplastic agents.

Adult↗
PubMed1992

Sister-chromatid exchanges in beta-thalassaemic patients under conditions of in vivo and in vitro depletion of folic acid.

In order to investigate the effect of folate depletion, lymphocyte sister-chromatid exchange (SCE) rates were compared among homozygous beta-thalassaemic patients with low folic acid levels, heterozygous beta-thalassaemic patients with normal folate levels and healthy persons with normal haemoglobin, in cultures with both normal and depleted folate conditions. Significantly higher SCE rates were found in homozygous patients in all assays, but the in vitro folate depletion did not induce an increase in SCE frequency in any group.

Adolescent↗
PubMed1991

A 2.5-Mb physical map within 3p21.1 spans the breakpoint associated with Greig cephalopolysyndactyly syndrome.

Numerous investigations suggest that one or more genes residing in the p14 to p21 region of human chromosome 3 are critical to the development of neoplastic diseases such as renal cell carcinoma and small-cell lung cancer (SCLC). This region is additionally involved in several interchromosomal translocations, one of which is associated with the developmental disorder Greig cephalopolysyndactyly syndrome. A series of five loci that map in close proximity to the Greig syndrome breakpoint [t(3;7)(p21.1;p13)] at 3p21.1 have been physically linked by pulsed-field gel analysis over a 2.5-Mb region. The probes include ACY1, cA84 (D3S92), cA199 (D3S93), pHF12-32 (D3S2), and MW-Not153 (D3S332). The Greig 3;7 translocation breakpoint was discovered between clones cA199 and MW-Not153, separated by 825 kb. Further analysis revealed comigration of a rearranged fragment detected by MW-Not153 and a chromosome 7 probe previously shown to be in close proximity to the breakpoint (CRI-R944). This latter probe also detects a rearrangement in a second Greig-associated translocation, (6;7)(q27;p13). The physical map resulting from this analysis orders the markers along the chromosome and identifies several locations for CpG islands, likely associated with genes. Although probe pEFD145.1 (D3S32) has been genetically linked to D3S2 (2 cM), physical linkage to the other five loci could not be demonstrated. One of the linked loci, D3S2, has been widely utilized in the analysis of chromosome 3p loss in several malignant diseases. Since expression of ACY1, a housekeeping gene, is specifically reduced in many cases of SCLC, knowledge of its precise chromosomal position and identification of neighboring putative gene loci should facilitate investigation into the mechanism of this reduction.

Cell Line↗
PubMed1989

Plasma folate and vitamin B12 levels in beta-thalassemia heterozygotes.

Plasma folic acid and vitamin B12 levels of 21 heterozygous beta-thalassemic patients from São José do Rio Preto, SP, Brazil did not differ from those of family member controls or of controls matched for age, sex and socioeconomic status. All values were within the normal range for folic acid (3-17 ng/ml) and vitamin B12 (200-950 pg/ml). A highly significant positive correlation (P less than 0.01) between folic acid and B12 levels was observed both in thalassemic patients (r = 0.93) and in the controls (r = 0.97).

Adolescent↗
PubMed1985

Partial trisomy 12q24.31----qter.

Clinical details of a male child with the karyotype 46,XY,-4,+der(4),t(4;12) (p16;q24.31)mat are reported and compared with those of other known cases of partial trisomy of the distal region of 12q. This condition is apparently associated with mental and psychomotor retardation, widely spaced eyes, flat nasal bridge, low set ears, down-turned mouth, micrognathia, loose skin at the nape, widely spaced nipples, simian creases, clinodactyly, abnormalities of the genitourinary system, alterations in the sacrococcygeal region, and deformities of the lower limbs. In the majority of the reported cases, the break-point was in the 12q24 region and resulted from adjacent 1 segregation of a maternal balanced translocation.

Abnormalities, Multiple↗
PubMed1982

Prominent satellites in oligophrenic, malformed patients: incidence, frequency of satellite associations and karyotype-phenotype comparisons.

Lymphocyte chromosome preparations from 51 malformed patients with idiopathic mental retardation were analyzed for presence or absence of prominent satellites, a high frequency (22%) of s+ variants being found. However, it is not possible to visualize a phenotypic tendency in the s+ patients either as an increase or decrease in IQ levels or as an etiological relation of the quantitative or qualitative developmental disorders. G--and Ag--NOR--banding techniques were performed in 5 s+ patients and their parents and in all cases apparently identical prominent satellites were observed in both the proband and one of his parents. Nevertheless in some cases the proband's chromosome presents a decreased frequency of silver stained NORs and also has a smaller frequency of participation in acrocentric associations than the carrier parent's chromosome. The different behaviour of the s+ chromosomes presently studied may be caused by a complex regulatory mechanism depending upon each individual chromosome pool.

Child↗
PubMed1981

Structural aberration of the X chromosome in a patient with gonadal dysgenesis: an approach to karyotype-phenotype correlation.

An 18-year-old female with some stigmata of pure dysgenesis had a chromosome constitution of 46,X,dir dup(X) (pter leads to q27: :q21 leads to qter). The abnormal chromosome was always late replicating. The clinical and cytogenetic picture is compared with that of patients with X;X translocation and some problems of karyotype-phenotype correlation are discussed.

Adolescent↗
PubMed1978

Trisomy 8 syndrome.

Clinical and dermatoglyphic data on a male patient with complete trisomy 8 are reported and compared with those of other known cases of trisomy 8. The more discriminating findings for this condition are skeletal anomalies, restricted articular function, and speech problems.

Adult↗
PubMedDate not supplied

HER-2 and cancer antigen 125 evaluation in ovarian borderline tumors by immunohistochemistry and fluorescence in situ hybridization.

The study determined the expression of cancer antigen (CA) 125 and HER-2 in 45 borderline ovarian tumors (BOTs) and investigated the correlation of these biologic markers with histologic type, clinical stage, and outcome. The level of CA 125 protein was assessed using DAKO's M-11 clone antibody in immunohistochemistry (IHC) assays (Carpinteria, CA). The HER-2 protein expression was assessed in IHC assays using the HercepTest (DAKO), and the HER-2 gene copy number per cell was investigated through fluorescence in situ hybridization (FISH) assays using VYSIS' PathVysion DNA Probe (Downers Grove, IL). Expression of the CA 125 protein was detected in 49% of the samples (22 out of 45 tumors) and significantly associated with the serous histologic type. However, CA 125 expression did not associate with clinical stage or outcome. Protein overexpression or gene amplification of HER-2 was not found. However, abnormal FISH results were detected in 16% (seven out of 45 patients) of specimens comprising extranumerary copies of HER-2 and/or chromosome 17 per cell. Abnormal FISH results were found to be independent of CA 125 expression and histologic type whereas they positively associate with advanced clinical stage. Our data show that HER-2 is not altered in BOTs, and the presence of aneusomy for chromosome 17 and HER-2 may predict tumor progression.

Adenocarcinoma, Mucinous↗