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Biomedical subjects

A Villa

Publications and source records attributed to A Villa.

At least 181 records · Page 10Linked to original sources
PubMed1995

Pericentric inversions of chromosome 4: report of a new family and review of the literature.

A family was cytogenetically studied because of the birth of a male child with a multiple congenital anomaly pattern, in whom a dup (4q) recombinant was found. His phenotypically normal mother's karyotype showed an apparently balanced pericentric inversion in a chromosome 4. So as to analyze the occurrence of recombinants, the cytogenetic data from this family are compared with those of the 18 previously reported familial cases of pericentric inversions (PIs) of chromosome 4. The congenital anomalies observed in the child strongly suggest Wolf-Hirschhorn syndrome but some of his clinical features seem to be pathogenetically related to the presence of lymphedema during the intrauterine period. In the multiple congenital anomaly pattern observed in this patient, the lymphedema could be the consequence of the large 4q duplication. The review of chromosome 4 PIs with 4q duplication suggests that the q3 region should be examined when edema is detected prenatally.

Adult↗
PubMed1995

Intracellular Ca2+ stores in chick cerebellum Purkinje neurons: ontogenetic and functional studies.

The molecular composition of intracellular Ca2+ stores in developing chicken cerebellum Purkinje neurons from embryonic day 11 (E11) to posthatching day 2 (P2) was studied by immunocytochemistry using specific antibodies for three molecular constituents, the receptor (R) and/or channel sensitive to inositol 1,4,5-trisphosphate (IP3), Ca(2+)-adenosinetriphosphatase (ATPase), and calsequestrin (CS). CS, IP3R, and Ca(2+)-ATPase were first detected by light-microscopic immunofluorescence in migrating Purkinje cells at E11-E12 and throughout late phases of embryonic development. Ontogenesis of CS, IP3R, and Ca(2+)-ATPase accompanied well-defined stages of cerebellum histogenesis and cytogenesis and was accomplished before hatching. High-resolution immunogold electronmicroscopy revealed that, at E18-P1, CS was still largely distributed to the endoplasmic reticulum (ER) lumen and began to be segregated to ER subcompartments (calciosomes) only by P2, whereas the IP3R was concentrated into ER cisternal stacks as early as E18. Both ionotropic and metabotropic plasma membrane receptors were present in dissociated single chicken Purkinje cells from E16 onward, as indicated by measurements of membrane currents (whole cell recording mode) and of cytoplasmic Ca2+ transients monitored with the cell-trappable fluorescent indicator fura 2-acetoxymethyl ester, respectively. Cytoplasmic Ca2+ transients were detected after either activation of glutamate metabotropic receptors, i.e., evidence of IP3-sensitive Ca2+ channels, or application of caffeine, i.e., evidence of ryanodine-sensitive Ca2+ channels. Intracellular Ca2+ stores appear to be functional during embryonic development.

Aging↗
PubMed1995

Local regression of breast tumors following intramammary ganciclovir administration in double transgenic mice expressing neu oncogene and herpes simplex virus thymidine kinase.

Females from a mouse lineage transgenic for the activated rat neu oncogene under the control of the mouse mammary tumor virus (MMTV) long terminal repeat (LTR) all develop breast tumors with high reproducibility within the first 2-3 months of life. These animals were crossed with mice from a lineage transgenic for the herpes simplex virus thymidine kinase gene (HSVtk) under the control of its own promoter and polyoma enhancer. Double transgenic mice (for both neu and tk) developed breast neoplasias with the same kinetics as the neu-only mice. Tumor-bearing double transgenic mice, treated intratumorally with the antiviral agent ganciclovir (GCV), showed an inhibiting effect on tumor growth. However, this effect was not seen either on GCV-treated neu-only transgenic mice or on saline-injected controls. This suggests that tk-engineered breast tumors are susceptible to GCV administered locally, and implies that neu-mice could be a useful model for testing the effectiveness of HSVtk-bearing vectors followed by systemic GCV on breast cancer cells.

Animals↗
PubMed1995

[Leukocytic procoagulant activity and chemotherapeutic drugs: the comparative effects of cisplatin and carboplatin on lympho-/monocytic procoagulant activity in vitro].

It is well known that a number of chemotherapeutic agents are able to induce procoagulating activity not only in neoplastic cells but also in normal, monocyte/macrophage cells, and some of them, including cisplatin, even increase procoagulating activity of the factor already expressed, providing a further example of the possible co-participation of chemotherapy in the onset of thrombotic complications in cancer patients. Carboplatin is an analogue of cisplatin but differs strikingly in terms of its collateral effects, in particular being less oto- and nephrotoxic. To the authors' knowledge there are no data regarding the possible effect of carboplatin on lympho/monocyte procoagulating activity. This study shows that not only platin but also carboplatin is able to increment the levels of lympho/monocyte procoagulating activity in vitro, with a dose-dependent effect, and to synergize with bacterial endotoxin in increasing this leukocyte activity, although the synergic effect is significantly greater in the case of carboplatin. The importance of these findings at a practical and clinical and clinical level still remains to be defined, in particular in the light of the different pharmacokinetic behaviour of these two chemotherapeutic agents and in the context of those neoplastic diseases for which cisplatin and carboplatin treatment is most frequently used.

Blood Coagulation Factors↗
PubMed1995

Study of the Mannich reaction: beta-amino-methylation of N-aryl and N-azaheteroaryl-substituted 2,5-dimethylpyrroles, compounds with potential biological activity.

Owing to the increasing need of drugs for the treatment of a variety of fungal and bacterial opportunistic infections, a study has been started with the aim of synthesizing structures amenable to a number of easily-to-perform structural modifications in order to meet the requirement of bypassing resistance phenomena. This paper reports on the synthesis of several N-(alpha-azaheteroaryl)-substituted 2,5-dimethyl-pyrroles bearing in one beta-position (or in both beta-positions) aminomethyl groups, introduced via a Mannich reaction. Electronic and steric effects by the N-(azaheteroaryl) substituents and the 2- and 5-methyl groups on the course of the Mannich reaction are discussed along with the results of in vitro tests against many Candida species, some bacteria, and several pathogenic plant fungi.

Anti-Bacterial Agents↗
PubMed1995

Characterization of nine novel mutations in the CD40 ligand gene in patients with X-linked hyper IgM syndrome of various ancestry.

X-linked immunodeficiency with hyper-IgM (HIGMX-1) is a rare disorder caused by defective expression of the CD40 ligand (CD40L) by activated T lymphocytes, resulting in inefficient T-B cell cooperation and failure of B cells to undergo immunoglobulin isotype switch. In the present work, we describe nine patients of various ancestry who bear different mutations in the X chromosome-specific CD40L gene. Two of the mutations were nonsense mutations, one each resulting in premature stop codons at amino acid residues 39 and 140. Three patients had single point missense mutations, one each at codons 126, 140, and 144. Another patient had a 4-bp genomic deletion in exon 2, resulting in a frameshift and premature termination. Three patients showed insertions, one each of 1, 2, and 4 nt, probably because of polymerase slippage, resulting in frameshift mutation and premature termination. Overall, these observations confirm the heterogeneity of mutations in HIGMX-1. However, the identification of two patients whose mutation involves codon 140 (previously shown to be altered in two other unrelated subjects) suggests that this may be a hotspot of mutation in HIGMX-1. In two additional patients with clinical and immunological features indistinguishable from canonical HIGMX-1, no mutation was detected in the coding sequence, in the 5' flanking region, or in the 3' UTR.

Base Sequence↗
PubMed1994

Genomic organization of the human VP16 accessory protein, a housekeeping gene (HCFC1) mapping to Xq28.

The region between DXS52 and Factor VIII gene in the human Xq28 chromosomal band contains a G+C-rich isochore to which many genes have been mapped. We report here the isolation and characterization of a transcript mapping about 50 kb telomeric from the vasopressin type 2 receptor gene in a 180-kb YACs/cosmid contig containing the L1CAM gene at its centromeric end. The determined transcribed sequence from a human fetal brain library is identical to that of the recently identified accessory protein HCFC1 (host cell factor, also called C1) that activates herpes simplex virus VP16 (alpha TIF) transactivator protein for association with the octamer motif-binding protein Oct-1 (Cell 74: 115, 1993). The gene is expressed in a ubiquitous pattern and a larger transcript of approximately 10 kb is present in all the tissues tested, while an alternatively spliced RNA of approximately 8.0 kb is present in muscle and heart tissues. Genomic sequencing allowed us to determine that the sequenced transcript is assembled from 26 exons spread over a relatively small genomic region of approximately 24 kb. This alllowed us to determine that a previously reported cDNA clone arises from the splicing out of an internal portion of exon 8 which does not change the reading frame. All together these results raise the possibility that alternative mRNA processing could partly contribute to the diversity of the polypeptide HCFC1 family in a subset of tissues.

Base Sequence↗
PubMed1994

Cytosolic Ca2+ binding proteins during rat brain ageing: loss of calbindin and calretinin in the hippocampus, with no change in the cerebellum.

The expression of two cytosolic, high affinity Ca(2+)-binding proteins, calbindin-28 and calretinin, has been investigated in the cerebellum and hippocampus of young and old rats (from 12 days to 30 months) by combining immunofluorescence and Western blotting. Three markers, calreticulin (the major Ca2+ binding protein within the lumen of the endoplasmic reticulum), MAP-2 (a microtubule binding protein concentrated in neuronal dendrites) and synaptophysin (an integral protein of synaptic vesicles), were studied in parallel. In the cerebellar cortex a rise from 12 to 60 days was observed with calbindin-28 and, especially, calretinin, concentrated in the Purkinje and granule neurons, respectively. The level of expression of the two proteins subsequently remained high and the distribution was unchanged, even in the cerebellum of old animals. A completely different pattern was observed in the hippocampus. Here calretinin, present especially in fibres and interneurons, was abundant in the young, decreased in the adult and reached low values in the old rats. Calbindin-28 accumulated during growth, especially in a subpopulation of CA1 pyramidal cells and in the mossy fibres of CA3, then declined, although irregularly, during ageing. These changes of the two proteins were more marked in the dorsal and central parts than in the ventral part of the hippocampus. In the same brain areas the levels of expression of the three additional markers and their distribution within neurons and synapses were unchanged by ageing.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1994

The exon-intron organization of the human X-linked gene (FLN1) encoding actin-binding protein 280.

We have determined the exon-intron organization of the human X-linked gene (FLN1) encoding actin-binding protein 280 (filamin), a ubiquitous protein that plays an important role in the mechanochemical activities of cells through its association with actin filaments and membrane components. The gene is composed of 47 exons spanning approximately 26 kb. The first and part of the second exon are untranslated. The actin-binding domain at the N-terminus is encoded by exons 2 to 5. The 96-amino-acid repeats corresponding to the elongated rod backbone of the protein are encoded by the remaining 42 exons: size, location, and boundaries of the exons cannot be easily correlated with the repeated structure, while sequences interrupting the repeats (the two hinge segments preceding repeats 16 and 24 and the 8-amino-acid (aa) segment interrupting the 15th repeat) were encoded by separate exons, suggesting that they may be recent additions to the X-linked protein. The 8-aa segment is encoded by exon 29, which is alternatively spliced.

Amino Acid Sequence↗
PubMed1994

Organization of the human CD40L gene: implications for molecular defects in X chromosome-linked hyper-IgM syndrome and prenatal diagnosis.

Recently, CD40L has been identified as the gene responsible for X chromosome-linked hyper-IgM syndrome (HIGM1). CD40L on activated T cells from HIGM1 patients fails to bind B-cell CD40 molecules, and subsequent analysis of CD40L transcripts by reverse transcription PCR demonstrated coding region mutations in these patients. This approach, however, is of limited use for prenatal diagnosis of HIGM1 in the early-gestation fetus. In this report, we have defined the genomic structure of the CD40L gene, which is composed of five exons and four intervening introns. With this information, we have defined at the genomic level the CD40L gene abnormalities for three previously described HIGM1 patients who demonstrated clustered deletions in the CD40L coding region. These different deletions arose from three distinct mechanisms, including (i) a splice donor mutation with exon skipping, (ii) a splice acceptor mutation with utilization of a cryptic splice site, and (iii) a deletion/insertion event with the creation of a new splice acceptor site. In addition, we have performed prenatal evaluation of an 11-week-old fetus at risk for HIGM1. CD40L genomic clones provide a starting point for further studies of the genetic elements that control CD40L expression. Our knowledge of the CD40L gene structure will prove useful for the identification of additional mutations in HIGM1 and for performing genetic counseling about this disease.

Base Sequence↗
PubMed1994

The role of pyruvate in neuronal calcium homeostasis. Effects on intracellular calcium pools.

It has long been known that pyruvate is essential for survival of prenatal neurons in culture. To understand the role of exogenous pyruvate in neuronal calcium homeostasis, we have investigated the effects of pyruvate (plus malate) addition to dissociated adult rat hippocampal and cerebral cortex cells and cultured CNS neurons having an unrestricted glucose supply. We found that pyruvate (plus malate) increased the respiration rate while ATP levels were unchanged. At the same time, cytosolic free calcium concentrations, [Ca2+]i, decreased while total 45Ca2+ and 40Ca2+ accumulation increased. The extra Ca2+ accumulated by the cells is attributable to an increase in the size of the intracellular calcium pools. Two such pools were identified on the basis of their sensitivity to specific drugs. The first pool was mobilized by thapsigargin plus tert-butyl hydroquinone and caffeine while the second pool was discharged by the mitochondrial uncoupler carbonyl cyanide p-trifluoromethoxphenylhydrazone (FCCP) (plus oligomycin). The two pools represented about 15-20% and 15-30%, respectively, of the rapidly exchangeable 45Ca2+ pools in cerebral cortex cells. In cultured hippocampal neurons, the collapse of the mitochondrial membrane potential (as induced by uncouplers (FCCP) or respiratory chain inhibitors (antimycin) caused a large increase in [Ca2+]i which varied in size and shape among cells and was reduced by external Ca2+ chelation. The latter condition also resulted in a partial discharge of FCCP-releasable 45Ca2+. The effects of FCCP did not result simply from ATP depletion since incubation in glucose-free medium and sequential additions of 2 mM deoxyglucose and 10 microM oligomycin, conditions that led to a dramatic reduction in cellular ATP levels, did not abolish the FCCP-induced [Ca2+]i rise. Taken together, the results indicate that mitochondria harbor a significant proportion of cellular Ca2+. The sensitivity of the mitochondrial pool size to pyruvate (plus malate) questions previous hypotheses concerning a kinetic limitation for Ca2+ accumulation in mitochondria in resting neurons.

Acetylcholine↗
PubMed1994

Dynamic mosaicism involving an unstable supernumerary der(22) chromosome in cat eye syndrome.

We have studied a girl, her sister and her mother who had a supernumerary marker chromosome in mosaicism. The marker was studied by cytogenetic methods and non-isotopic in situ hybridization with the single D22S9 DNA probe which maps to 22q11. The supernumerary chromosome was derived from a chromosome 22 and it did not present the same morphology in all the cells. At least 5 distinct types of the marker chromosome were detected and some of them were probably derived from each other (dynamic mosaicism). The proposita had an MCA pattern consistent with mild cat eye syndrome, while her sister and her mother had some of the manifestations described in this syndrome. A specific correlation could be established between phenotype and karyotype.

Abnormalities, Multiple↗