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Biomedical subjects

G Romeo

Publications and source records attributed to G Romeo.

At least 19 recordsLinked to original sources
PubMed1992

Congenital diaphragmatic hernia associated with ipsilateral upper limb reduction defects: report of a case with thumb hypoplasia.

Four unrelated cases of congenital diaphragmatic hernia associated with ipsilateral upper limb reduction defects were reported by McCredie and Reid in 1978 (J Pediatr 92: 762-765). As contiguous segments of the cervical neural crest are involved in the development of diaphragm and arms, the authors suggested that an early injury to the cervical neural crest might be the common underlying pathogenesis. We describe here a further example of this malformation complex: a newborn with a left posterolateral diaphragmatic hernia associated with ipsilateral thumb hypoplasia.

Abnormalities, Multiple↗
PubMed1992

A volume-sensitive chloride conductance revealed in cultured human keratinocytes by 36Cl- efflux and whole-cell patch clamp recording.

The Cl- transport mechanism responsible for the stimulation of 36Cl- efflux after exposure to hypotonic medium (210 mosmol/kg) was investigated in human keratinocytes. The involvement of the anion exchanger and of the Cl-/cation cotransporters was ruled out by the finding that replacement of extracellular Cl- by the poorly permeant anion gluconate, and the addition of bumetanide and furosemide, inhibitors of the Na+/K+/Cl- and K+/Cl- cotransporters, respectively, failed to significantly reduce the activation of Cl- efflux by hypotonic medium. 'Whole cell' configuration of the patch clamp technique directly revealed the presence of a macroscopic Cl- current, which was evoked by incubation with hypotonic medium and was reversed by elevation of the extracellular osmolality. Volume-sensitive current showed outward rectification of the current-voltage relationship and time-dependent inactivation at depolarizing voltages. This current was Cl- selective, because the zero-current reversal potential approached the Cl- equilibrium potential, when extracellular Cl- was replaced by gluconate. 0.1 mM 1,9-dideoxyforskolin significantly reduced either 36Cl- efflux and the Cl- current, suggesting that the Cl- efflux and the macroscopic current activated after exposure to hypotonic medium are mediated by the same pathway. Electronic cell sizing showed that in keratinocytes hypotonic swelling was not followed by a significant regulatory volume decrease response.

Biological Transport↗
PubMed1992

Ionic selectivity of volume-sensitive currents in human epithelial cells.

The ion selectivity of swelling-activated Cl- currents has been investigated in three different human epithelial cell lines, two derived from the airway epithelium (9HTEo- and CFNPE9o-) and one from a colon carcinoma (T84). The relative permeability of volume-sensitive currents with respect to Cl- is: I- (1.19) greater than NO3- (1.07) approximately Br-(1.05) greater than Cl-(1.0) greater than F-(0.5) approximately HCO3-(0.48) greater than isethionate(0.28) greater than aspartate (0.14) approximately gluconate(0.13) approximately SO4(2-)(0.12). This type of ion selectivity is similar to that described for depolarization-activated outwardly rectifying Cl- channels found in epithelial cells.

Anions↗
PubMed1992

Extracellular 2-chloroadenosine and ATP stimulate volume-sensitive Cl- current and calcium mobilization in human tracheal 9HTEo- cells.

The perforated-patch whole-cell technique was used to record membrane currents in epithelial cells (9HTEo-) obtained from the human tracheal epithelium. Extracellular application of 2-chloroadenosine and ATP (0.01-100 microM) caused activation of Cl- currents similar to those regulated by cell volume in airway and intestinal cells. This response was inhibited by increasing extracellular osmolality, by omission of extracellular Ca2+, or by the addition of the A2 adenosine receptor antagonist 3,7-dimethyl-1-propargylxanthine (DMPX). Fluorimetric measurements with fura-2 reveal that 2-chloroadenosine and ATP elicited both a Ca2+ influx through the plasma membrane and a release from intracellular stores.

2-Chloroadenosine↗
PubMed1992

Construction of a map of chromosome 16 by using radiation hybrids.

A human-hamster cell hybrid carrying a single copy of chromosome 16 as the only human genetic material was irradiated with a single dose of gamma-rays (7000 rads; 1 rad = 0.01 Gy) and then fused with a thymidine kinase-deficient hamster cell line (RJKM) to generate radiation hybrids retaining unselected fragments of this human chromosome. In two experiments, 223 hybrids were isolated in hypoxanthine/aminopterine/thymidine (HAT) medium and screened with 38 DNA probes, corresponding to anonymous DNA or gene sequences localized on chromosome 16. The most likely order and location of the 38 DNA sequences were established by multiple pairwise analysis and scaled to estimate physical distance in megabases. The order and the distances thus obtained are mostly consistent with available data on genetic and physical mapping of these markers, illustrating the usefulness of radiation hybrids for mapping.

Chromosome Mapping↗
PubMed1992

Four new mutations of the CFTR gene (541delC, R347H, R352Q, E585X) detected by DGGE analysis in Italian CF patients, associated with different clinical phenotypes.

The delta 508 mutation accounts for about 53% of the molecular defects causing cystic fibrosis (CF) in Italy. The numerous additional mutations detected so far are all relatively rare, and about 30% of CF chromosomes carries unknown mutations in our patients. In order to identify the non-delta F508 mutations causing CF in our population, we performed GC-clamped denaturing gradient gel electrophoresis (DGGE) on 9 exons of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in a sample of 86 Italian CF patients carrying unknown mutations on at least one chromosome. Direct sequencing of 17 samples showing an altered electrophoretic mobility allowed the identification of four new mutations (541delC, R347H, R352Q, and E585X), five mutations already known (G85E, I148T, G178R, 1078delT, and R347P), and one rare variant (1898 + 3A-->G). The strategy based on GC-clamped DGGE represents an efficient and rapid approach for mutation detection for those genetic diseases, such as CF, in which a large number of rare molecular defects has been described.

Base Sequence↗
PubMed1992

Deletion delta F508 and haplotype analysis of CFTR gene region in Slovak CF patients.

Analysis of a sample of 50 unrelated cystic fibrosis (CF) patients and 46 nuclear families from Slovakia (Czechoslovakia) by the polymerase chain reaction and Southern hybridization revealed that the proportion of the delta F508 mutation was 58% in this population, and that the frequency of the B (i.e., KM19/XV2c [1-2]) haplotype was increased in both delta F508 and non-delta F508 CF chromosomes (98% and 46%, respectively). These results support the view that the trans-European gradient of the delta F508 frequency is of a geographical rather than of an ethnic origin, and that in Slavonic populations, there exists an as yet unidentified but frequent CF mutation other than delta F508, associated with the B haplotype.

Blotting, Southern↗
PubMed1992

Radiation hybrids for mapping and cloning DNA sequences of distal 16p.

Three hundred fifteen radiation hybrids (RH) were isolated using a monochromosomal cell hybrid containing chromosome 16 only. A panel of 18 RH, which showed breakpoints among four markers (3.15, 26.6, 3'HVR, and 5'HVR) mapping in the distal portion of 16p, were selected and characterized for the retention of nine additional DNA sequences already localized in this region, and for one centromeric sequence. One or more breakpoints were identified in nine of the 12 intervals defined by the 13 single-copy sequences used. This panel of RH represents a tool for the construction of a detailed physical map of the distal part of 16p and for cloning sequences located in the proximity of disease genes. Three inter-Alu DNA sequences, amplified from one of these RH containing the autosomal dominant polycystic kidney disease (PKD1) gene, were cloned and mapped in the panel. Sequencing of the ends of one of three clones showed a (CAAA)n repeat, which revealed a two-allele polymorphism.

Base Sequence↗
PubMed1992

Fine mapping and cloning of the breakpoint associated with Menkes syndrome in a female patient.

The gene responsible for Menkes syndrome has been assigned to Xq13 by a combination of comparative mapping and linkage analysis. A previous report has mapped the translocation breakpoint associated with the disease in a female patient to an interval delimited by PGK1 and a group of six more proximal Xq13 markers, including DXS56. We have characterized a number of PGK1- or DXS56-positive YACs, from which we have generated six new markers. One of them identifies a small overlap region between a PGK1-positive YAC and three DXS56-positive YACs, distal to the Menkes breakpoint. A 560-kb region covered by a DXS56-positive YAC has been restriction-mapped and subcloned, disclosing a 187-kb MluI fragment astride the breakpoint. A probe mapping distal to the rearrangement in the same interval reveals altered PGFE fragments in a hybrid constructed from the translocation patient's DNA. We describe the development of a cosmid contig extending 150 kb from a nearby CpG island across the breakpoint. This contig includes four adjacent clones displaying cross-specific hybridization.

Base Sequence↗
PubMed1992

Autosomal recessive microcephaly with early onset seizures and spasticity.

We describe two siblings, a male and a female pair, born of consanguineous parents, affected with a rare genetic form of congenital microcephaly. The clinical syndrome is characterized by early onset myoclonic seizures, spasticity, and profound psychomotor retardation without detectable brain malformations. To date, only two kindreds and one sporadic case with a similar clinical picture have been observed and reported (Tolmie et al. 1987, Bundey & Griffiths 1977). The severity of the neurological features and their perinatal onset differentiate the syndrome from the more common autosomal recessive microcephaly with spasticity/seizures.

Child, Preschool↗
PubMed1992

Oculocerebral syndrome with hypopigmentation (Cross syndrome): report of a new case.

A syndrome of ocular and cutaneous hypopigmentation, severe mental retardation with spastic tetraplegia and athetosis was first observed by Cross in three siblings of an inbred Amish family. Since then, seven other patients, three sporadic and four with familial recurrence, have been reported in the literature, confirming the autosomal recessive inheritance. The clinical spectrum of the syndrome has been expanded to include true developmental defects of the CNS such as cystic malformation of the posterior fossa of the Dandy-Walker type. We report a new case of Cross syndrome.

Brain↗
PubMed1992

Genetic variants of alpha-1-antitrypsin (AAT).

This paper reviews the genetic variants of alpha-1-antitrypsin (AAT) which have been sequenced with special emphasis on the s.c. deficiency variants. These result in AAT low plasma levels via three main mechanisms: 1) intracellular storage; 2) intracellular degradation; 3) lack of synthesis. Intracellular storage occurs with the classical Z variant and with a few variants called M-like, because of their isoelectric focusing (IF) pattern. The storage phenomenon causes liver damage and can be demonstrated at both light and electron microscopic level with the help of immunohistochemistry. We report a new deficiency variant of AAT (M-Cagliari) characterized by very low plasma levels, massive storage of AAT and liver cirrhosis. By using immunohistochemical techniques and DNA analysis we could demonstrate that M-Cagliari has antigenic and genetic properties other than the Z AAT.

Base Sequence↗
PubMed1992

Modulation of ferritin H-chain expression in Friend erythroleukemia cells: transcriptional and translational regulation by hemin.

The mechanisms that regulate the expression of the H chain of the iron storage protein ferritin in Friend erythroleukemia cells (FLCs) after exposure to hemin (ferric protoporphyrin IX), protoporphyrin IX, and ferric ammonium citrate (FAC) have been investigated. Administration of hemin increases the steady-state level of ferritin mRNA about 10-fold and that of ferritin protein expression 20-fold. Experiments with the transcriptional inhibitor actinomycin D and transfection studies demonstrate that the increment in cytoplasmic mRNA content results from enhanced transcription of the ferritin H-chain gene and cannot be attributed to stabilization of preexisting mRNAs. In addition to transcriptional effects, translational regulation induces the recruitment of stored mRNAs into functional polyribosomes after hemin and FAC administration, resulting in a further increase in ferritin synthesis. Administration of protoporphyrin IX to FLCs produces divergent transcriptional and translational effects. It increases transcription but appears to suppress ferritin mRNA translation. FAC treatment increases the mRNA content slightly (about twofold), and the ferritin levels rise about fivefold over the control values. We conclude that in FLCs, hemin induces ferritin H-chain biosynthesis by multiple mechanisms: a transcriptional mechanism exerted also by protoporphyrin IX and a translational one, not displayed by protoporphyrin IX but shared with FAC.

Animals↗
PubMed1992

Molecular and cytogenetic characterization of radiation hybrids specific for human chromosome 16.

Two hundred and twenty-three radiation hybrids retaining random fragments of human chromosome 16 were isolated during two successive experiments in HAT medium and screened with a total of 38 DNA probes, corresponding to anonymous DNA or gene sequences localized on chromosome 16. The presence of single or multiple human chromosomal fragments in a small subset of these hybrids was determined using in situ hybridization with total human DNA. The results confirm that individual radiation hybrids are often heterogeneous with respect to the retention and distribution of human fragments, as already suggested by their characterization with DNA probes. A number of these 223 radiation hybrids, whose detailed characterization has not been previously reported, represent a resource for the rapid isolation of new DNA markers or coding sequences from specific regions of chromosome 16 where human disease genes are already known to map.

Chromosomes, Human, Pair 16↗
PubMed1992

Mapping of human hexokinase 1 gene to 10q11----qter.

Two partial-length cDNAs encoding the type 1 human hexokinase (ATP:D-hexose 6-phosphotransferase) were isolated from a placenta cDNA library using a 50-bp oligonucleotide synthesized according to the known sequence of human HK1. Using the larger (1.8 kb) cDNA insert as a probe and a panel of human-hamster somatic cell hybrids, we were able to assign the HK1 gene to the long arm of chromosome 10.

Animals↗
PubMed1992

Human lens transparence in high-myopic subjects.

The possibility of a relation between high myopia and lens opacity was studied. For this research, the Lens Opacity Meter 701 was used. The lens opacity values measured in 91 high-myopic eyes were compared with those measured in a control group of 106 emmetropic eyes. This comparison showed that myopic had always higher lens opacity values than emmetropic ones, and this result was statistically significant after the age of 20.

Adolescent↗