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Biomedical subjects

R G Gregg

Publications and source records attributed to R G Gregg.

At least 37 records · Page 2Linked to original sources
PubMed1995

Molecular characterization and expression patterns of a B-type nuclear lamin during sea urchin embryogenesis.

Developmentally regulated, tissue-specific patterns of nuclear lamin expression occur during vertebrate embryogenesis, but little is known regarding lamin ontogeny during the early development of other phyla. cDNA clones encoding a lamin from the sea urchins Strongylocentrotus purpuratus and Lytechinus variegatus have been identified, and the full coding region from the former has been sequenced. The predicted amino acid sequence indicates that this echinoderm lamin is more closely related to vertebrate B-type lamins than to dipteran fly and nematode lamins--the only other invertebrate lamins sequenced to date. Monoclonal and polyclonal antibodies to sea urchin lamin demonstrate that nuclei of unfertilized eggs and embryos exhibit relatively faint immunoreactivity until the differentiation of primary mesenchymal cells, the nuclear envelopes of which become strongly and selectively labeled by anti-lamin antibodies. Northern blots reveal stage-specific fluctuations in a single 4-kb lamin message during early development and, together with immunoblotting data, suggest that the increase in mesenchymal cell nuclear envelope immunoreactivity is due to a quantitative increase in a single type of lamin. These observations demonstrate that, similar to vertebrates, cell differentiation in invertebrates can be accompanied by a change in lamin expression patterns.

Amino Acid Sequence↗
PubMed1994

A calcium channel mutation causing hypokalemic periodic paralysis.

The only calcium channel mutation reported to date is a deletion in the gene for the DHP-receptor alpha 1-subunit resulting in neonatal death in muscular dysgenesis mice (1). In humans, this gene maps to chromosome 1q31-32. An autosomal dominant muscle disease, hypokalemic periodic paralysis (HypoPP), has been mapped to the same region (2). Sequencing of cDNA of two patients revealed a G-to-A base exchange of nucleotide 1583 predicting a substitution of histidine for arginine528. This affects the outermost positive charge in the transmembrane segment IIS4 that is considered to participate in voltage sensing. By restriction fragment analysis, the mutation was detected in the affected members of 9 out of 25 HypoPP families. The results indicate that the DHP-receptor alpha 1-subunit mutation causes HypoPP. An altered excitation-contraction coupling may explain the occurrence of muscle weakness.

Amino Acid Sequence↗
PubMed1993

Molecular characterization of the gene encoding the gamma subunit of the human skeletal muscle 1,4-dihydropyridine-sensitive Ca2+ channel (CACNLG), cDNA sequence, gene structure, and chromosomal location.

cDNA clones of the gamma subunit of the skeletal muscle 1,4-dihydropyridine-sensitive voltage-dependent Ca2+ channel were isolated from a human fetal skeletal muscle cDNA library using the rabbit gamma cDNA as a probe. The DNA sequence of the entire human cDNA was determined. Cosmids that contained the human gamma gene were isolated and used to determine the genomic organization of the coding sequences. Four exons were identified, spanning 12.5 kilobases of DNA. Reverse-transcribed polymerase chain reaction analysis detected the gamma transcript in human and mouse skeletal muscle RNAs, but not in RNA from human brain or cardiac muscle or from mouse brain, cardiac muscle, spleen, kidney, liver, or stomach. A polymorphic dinucleotide repeat within the gamma gene was identified. This repeat was used to type a subset of the Centre d'Etude du Polymorphisme Humain families. Linkage analysis indicates that the gamma gene is tightly linked (Z = 12.94, theta = 0.001) to growth hormone at chromosome 17q23, a region that also contains the adult skeletal muscle Na+ channel.

Amino Acid Sequence↗
PubMed1993

Assignment of the human gene for the alpha 1 subunit of the skeletal muscle DHP-sensitive Ca2+ channel (CACNL1A3) to chromosome 1q31-q32.

A human clone corresponding to the gene encoding the alpha 1 subunit of the skeletal muscle dihydropyridine-sensitive calcium channel (CACNL1A3) has been isolated and partially sequenced. Oligonucleotides based on this sequence were used in a polymerase chain reaction to amplify specifically the human gene in human-rodent somatic cell hybrids, allowing the assignment of CACNL1A3 to chromosome 1. A polymorphic dinucleotide repeat also was identified in the human clone and using PCR was typed on a subset of the CEPH families. Multipoint linkage analysis places the CACNL1A3 gene between D1S52 and D1S70, on chromosome 1q31-q32.

Amino Acid Sequence↗
PubMed1993

Assignment of the human gene for the beta subunit of the voltage-dependent calcium channel (CACNLB1) to chromosome 17 using somatic cell hybrids and linkage mapping.

A human clone containing a portion of the gene encoding several isoforms of the beta 1 subunit of voltage-dependent calcium channels was isolated and partially sequenced. The gene was mapped to chromosome 17 using the polymerase chain reaction with oligonucleotides that allowed the specific amplification of the human sequence in the human-rodent hybrids. A polymorphic dinucleotide repeat was identified within the gene and typed on a subset of the CEPH families. Using multipoint linkage analysis the most likely location of the beta 1 subunit gene is between D17S36 and NGFR on chromosome 17q11.2-q22.

Animals↗
PubMed1993

Application of DNA analysis in a population-screening program for neonatal diagnosis of cystic fibrosis (CF): comparison of screening protocols.

We compare two protocols for newborn screening for cystic fibrosis (CF). The first uses the immunoreactive trypsinogen (IRT) assay with a cutoff of > or = 180 ng/ml and a sweat test to identify CF patients. The second uses the IRT assay with a 100 ng/ml cutoff in conjunction with direct analysis for the delta F508 CF transmembrane conductance regulator (CFTR) mutation in a two-tiered (i.e., IRT/DNA) protocol, followed by a sweat test. We screened 220,865 newborns from Wisconsin for CF, using the IRT protocol identifying 369 infants with an elevated IRT, of whom 46 were found to have CF. Another 7 CF patients were identified who had a false-negative IRT level. The CF incidence in the white population was 1 in 3,431 (carrier incidence of 1 in 30). The IRT protocol had a sensitivity of 87% and a positive predictive value of 12.5%. We subsequently used the IRT/DNA protocol to screen 21,258 infants. Of 518 infants with an IRT level > or = 100 ng/ml, 24 carried at least one copy of the delta F508 CFTR mutation, and 4 of these infants were found to have CF, yielding a positive predictive value for this protocol of 16.7%. Direct comparison of the positive predictive value of the two protocols is not valid, because of the different populations screened. However, had the IRT protocol been used on the IRT/DNA cohort, 50 infants, including the 4 with CF, would have received sweat tests, yielding a positive predictive value of 8%. Because of the small sample size, this positive predictive value is not significantly different from that obtained for the IRT/DNA test. However, from a practical point of view the IRT/DNA approach does decrease considerably the number of sweat tests that must be undertaken. The number of false positives for the IRT protocol (46 in 21,258) is increased significantly compared with that for the IRT/DNA approach (20 in 21,258; P < .001). The incidence of delta F508 carriers detected in cohorts with an elevated IRT level was increased compared with the incidence in the general population. The direct costs for the IRT/DNA approach (100 ng/ml) were $11,374 per CF patient detected, compared with $10,187 per CF patient detected for the IRT protocol. Therefore, we conclude that the IRT/DNA approach to CF newborn screening decreases the number of false-positive subjects contacted, without a significant increase in cost.

Analysis of Variance↗
PubMed1993

Genetic heterogeneity in families with hereditary multiple exostoses.

We have carried out a linkage analysis on 11 families segregating gene(s) for hereditary multiple exostoses (EXT). Four highly informative, short tandem-repeat (STR) markers that have been physically mapped to an interval surrounding the Langer-Giedion chromosomal region (8q24.11-q24.13) were used in a multipoint linkage analysis. Significant evidence for linkage of EXT with genetic heterogeneity was found. A model of heterogeneity with linkage of the disease gene to the STR markers in 70% of the families (with a 95% confidence interval of 26%-96%) produced a maximum LOD score of 8.11, with the most likely position of EXT between D8S85 and D8S199. Thus there are at least two genes that are capable of causing hereditary multiple exostoses, one in the Langer-Giedion region and one at another, unlinked location.

Cell Line↗
PubMed1993

Refined genetic localization for central core disease.

Central core disease (CCO) is an autosomal dominant myopathy clinically distinct from malignant hyperthermia (MHS). In a large kindred in which the gene for CCO is segregating, two-point linkage analysis gave a maximum lod score, between the central core disease locus (CCO) and the ryanodine receptor locus (RYR1), of 11.8, with no recombination. Mutation within RYR1 is responsible for MHS, and RYR1 is also a candidate locus for CCO. A combination of physical mapping using a radiation-induced human-hamster hybrid panel and of multipoint linkage analysis using the Centre d'Etude du Polymorphisme Humain families established the marker order and sex-average map distances (in centimorgans) on the background map as D19S75-(5.2)-D19S9-(3.4)-D19S191-(2.2)-RYR1-(1.7)-D19S190-(1.6)-D19S47-(2.0)- CYP2B. Recombination was observed between CCO and the markers flanking RYR1. These linkage data are consistent with the hypothesis that CCO and RYR1 are allelic. The most likely position for CCO is near RYR1, with a multipoint lod score of 11.4, in 19q13.1 between D19S191 and D19S190, within the same interval as MHS (RYR1).

Alleles↗
PubMed1992

Skeletal muscle and brain isoforms of a beta-subunit of human voltage-dependent calcium channels are encoded by a single gene.

Clones of the beta 1-subunit of the voltage-dependent calcium channel (VDCC) from human skeletal muscle and hippocampus cDNA libraries, and from human genomic libraries, were isolated using a human skeletal muscle beta 1 cDNA probe generated by polymerase chain reaction. The skeletal muscle beta 1 cDNA (beta 1M) encodes a protein of 523 amino acids that is 97% identical to the rabbit skeletal muscle beta-subunit. Two different cDNAs, beta 1B1 and beta 1B2, were obtained from the human hippocampus library. The beta 1B1 transcript encodes a protein of 478 amino acids that is identical to the skeletal muscle beta-subunit (beta 1M), except for an internal region of 52 amino acids. The beta 1B2 transcript encodes a protein of 596 amino acids. The beta 1B2 polypeptide is identical to the beta 1B1 polypeptide at amino acids 1-444; however, it has a unique 152 amino acid carboxyl terminus. Like beta 1B1, it differs from beta 1M at the internal 52 amino acids. Analysis of the beta 1 gene structure demonstrates that these three cDNAs represent transcripts encoded by a single beta 1 gene. Transcripts from the beta 1 gene were detected in RNA from skeletal muscle, heart, spleen, and brain, but not in RNA from liver, stomach, or kidney.

Amino Acid Sequence↗
PubMed1992

A cysteine-for-arginine substitution (R614C) in the human skeletal muscle calcium release channel cosegregates with malignant hyperthermia.

A point mutation in the human gene for the skeletal muscle calcium release channel (ryanodine receptor [RYR1]) correlates with inheritance of malignant hyperthermia in a family of Northern European descent. The substitution of thymine for cytosine at position 1840 of the RYR1 transcript results in a cysteine-for-arginine substitution at position 614 (R614C) of the amino acid sequence. The mutation was absent in 59 normal individuals from the general population, in 61 additional unrelated malignant hyperthermia-susceptible patients, and in 18 patients with malignant hyperthermia associated with other inherited or congenital diseases. Together with reports of an equivalent mutation in six susceptible pig strains and an identical mutation in one other human pedigree, these findings suggest that the cysteine-for-arginine mutation represents a shared calcium release channel pathogenesis between porcine malignant hyperthermia and a subset of mutations responsible for the human malignant hyperthermia syndrome.

Adult↗