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R P Erickson

Publications and source records attributed to R P Erickson.

At least 109 records · Page 6Linked to original sources
PubMed1991

Molecular and cytologic studies of Ehlers-Danlos syndrome type VIII.

We present a family with findings of Ehlers-Danlos syndrome type VIII and a presenile appearance due to decreased subcutaneous tissue with drawn skin, defective wound healing, contractures, and thin hair. To investigate this syndrome, we studied collagen production and the growth properties of cultured fibroblasts taken from affected relatives. We could not find evidence of a collagen defect or premature senescence of cultured fibroblasts, although the fibroblasts may have a decreased growth rate. We conclude that this family has findings of EDS VIII and premature aging and propose that this overlapping phenotype is due to a single pathogenetic mechanism. Our studies of collagen production and fibroblast replication did not discern this mechanism.

Adult↗
PubMed1991

The glucocorticoid hormone signal transduction pathway in mice homozygous for chromosomal deletions causing failure of cell type-specific inducible gene expression.

Wild-type newborn mice are characterized by the ability of certain liver-specific genes encoding various enzymes and mapping on different chromosomes to respond to glucocorticoid induction. Newborn mice homozygous for deletions at and around the albino locus on chromosome 7 fail to develop this competence for hormone-inducible gene expression even through they do show normal constitutive expression of the same genes. Studies of the glucocorticoid hormone signal transduction pathway reported here show identical expression of glucocorticoid receptor mRNA and protein in deletion homozygotes and normal littermates. Furthermore, the receptor interacts normally with the 90-kDa heat shock protein hsp90. Elevated glucocorticoid hormone levels in newborn deletion homozygotes, most likely resulting from their stressed condition, provide an explanation for the reduced binding activities of receptors reported previously. The elimination of receptors and hormones as direct targets of the chromosomal deletion effects suggests that the failure of inducible gene expression might reside in defective competence of the affected structural genes to respond to the hormonal stimulus.

Animals↗
PubMed1991

Correlation of phenotypic and genetic heterogeneity in cystic fibrosis: variability in sweat electrolyte levels contributes to heterogeneity and is increased with the XV-2c/KM19 B haplotype.

We have reinvestigated a classification of clinical heterogeneity among cystic fibrosis (CF) patients that we previously reported and investigated the possible relationship of the identified CF subgroups to haplotypes around the CF gene and to HLA-DR haplotypes. Age-corrected values for sweat electrolytes, rate of progression of lung disease as assessed by Brasfield chest x-ray scores, and severity of pancreatic insufficiency as assessed by daily supplemented enzyme dosage were obtained for 55, 59, and 59 patients, respectively. XV-2c and KM19 RFLPs were determined by hybridization to TaqI and PstI digests of human genomic DNA, respectively, and analysis of mutations by PCR amplification followed by allele-specific oligo-deoxynucleotide hybridization was performed for 29 patients. HLA-DR restriction fragment length polymorphisms (RFLPs) were determined by hybridization of cDNA beta 1 and genomic DQ alpha probes to TaqI digests of human genomic DNA. The results show that the previous subdivision on the basis of age-corrected levels of sweat electrolytes, as well as measures of severity of lung disease and pancreatic disease, is valid. In addition, the C and D haplotypes are associated with lower age-corrected sweat sodium level. No significant relationship between CF haplotypes and the other two disease variables or between HLA-DR haplotypes and any of the clinical variables was found.

Child↗
PubMed1991

Developmental appearance of proteins identified by two-dimensional gel electrophoresis in mouse gonadal tissue.

Gonadal protein patterns of the mouse were studied during fetal development by two-dimensional gel electrophoresis. Fetal mice at days 8.5, 10.5, 12.5, and 14.5 post-coitum were analyzed for male or female specific proteins. Although no sex specific proteins were found, several proteins were found which were expressed in significantly different amounts in the two sexes at about the time of gonadal differentiation. Hence, quantitative differences, rather than qualitative ones, could be related to the initiation of testis or ovary development.

Animals↗
PubMed1991

EMG muscle scanning: comparison to attached surface electrodes.

Electromyographic (EMG) muscle scanning measures brief samples of integrated muscle action potentials from individual muscles using a hand-held scanner with post-style electrodes. This "scanning" technique is widely used by biofeedback practitioners to quickly assess muscle activity in the diagnosis of musculoskeletal disorders. In an effort to compare muscle scanning with the established technique using attached surface electrodes, ten healthy subjects (25-35 years old) were scanned using 2-second sampling at five bilateral muscle sites while simultaneously monitoring the same sites with surface electrodes. This was repeated using 10-second scanning samplings. Pearson's product-moment correlations between scanning for 2 seconds and prolonged surface recording at all sites were 0.54-0.89. Scanning for 10 seconds improved the correlations to 0.68-0.91. EMG scanning for 2 seconds compares favorably with attached surface electrode recording. Comparisons are further improved by 10-second scans.

Adult↗
PubMed1991

Taste of glutamate salts in young and elderly subjects: role of inosine 5'-monophosphate and ions.

Taste sensitivity to five glutamate salts (sodium glutamate, potassium glutamate, ammonium glutamate, calcium diglutamate, and magnesium diglutamate) were determined in sixteen young (mean age 25.58 years) and eighteen elderly (mean age 86.89 years) subjects. The effect of inosine 5'-monophosphate (IMP) and ions on taste perception of glutamate compounds was also investigated. The detection thresholds for glutamate salts were 5.04 times higher in elderly subjects than in young subjects; the recognition thresholds were 3.84 times higher. For young subjects, 0.1 mM IMP lowered detection and recognition thresholds for all 5 salts. A stronger concentration of IMP (1 mM) had this effect in both young and elderly groups. Elderly subjects perceived suprathreshold concentrations as less intense than young subjects. Chloride and acetate salts of sodium, potassium, and calcium reduced the detection and recognition thresholds of L-glutamic acid but had no effect sodium glutamate thresholds.

Adult↗
PubMed1991

The effect of H-2 region and genetic background on hormone-induced ovulation rate, puberty, and follicular number in mice.

We have examined the effects of major histocompatibility (H-2) haplotypes and genetic background (all loci other than the H-2 region) on hormone-induced ovulation rate in congenic strains of mice. In comparison with the H-2a haplotype, the H-2b haplotype increased hormone-induced ovulation rate 92% on the A/J (A) genetic background. However, H-2 haplotype did not affect hormone-induced ovulation rate on the C57BL/10J (C57) genetic background. The H-2b-linked gene(s) increased hormone-induced ovulation rate on the A/J genetic background largely by (1) enhancing the maturation of follicles in response to pregnant mare's serum gonadotrophin (PMSG) and (2) altering the stages of follicular development which can be induced to ovulate in response to human chorionic gonadotrophin (hCG). The observed effects of H-2 on hormone-induced ovulation rate were not explained by differences in the timing of puberty, the number of follicles present in untreated females, or the incidence of follicular atresia. The effect of genetic background on hormone-induced ovulation rate was much greater than was the effect of the H-2 region. We found that hormone-induced ovulation rate was five- to six-fold higher on the C57 genetic background than on the A genetic background. The C57 genetic background increased hormone-induced ovulation rate by (1) enhancing the induction of follicular maturation in response to gonadotropins and (2) by reducing the incidence of follicular atresia.

Animals↗
PubMed1991

Antisense inhibition of beta-glucuronidase expression in preimplantation mouse embryos: a comparison of transgenes and oligodeoxynucleotides.

Using as a model the inhibition of beta-glucuronidase expression in preimplantation embryos, we have compared injections of transgenes directing the synthesis of antisense RNA and antisense oligodeoxynucleotides to our previous results with cytoplasmic injections of antisense RNAs. Pronuclear injection of an antisense DNA construct containing 1.4 kb of coding region of beta-glucuronidase fused to the mouse metallothionein I promoter results in transient inhibition of gene expression in preimplantation mouse embryos. Pronuclear injection of a smaller antisense DNA construct, overlapping the start codon, failed to inhibit gene expression. Injection of two 20-mer antisense oligodeoxynucleotides, one complementary to sequences including the initiation codon and the second complementary to exon 7 sequences of the beta-glucuronidase gene, failed to inhibit gene expression. In addition, cultures of embryos in the presence of antisense oligodeoxynucleotides had no effect on gene activity. Using radiolabeled oligomers added to the culture medium, we found poor uptake of oligodeoxynucleotides by embryos.

Animals↗
PubMed1991

Polymerase chain reactions with alphoid-repeat primers in combination with Alu or LINEs primers, generate chromosome-specific DNA fragments.

Y alphoid primers in combination with Alu and LINEs primers generated new DNA fragments in polymerase chain reactions (PCR) on DNA from a Y-only somatic cell hybrid but not from X-only, 3-only, or 21-only hybrids. X alphoid primers used in a similar manner generated new DNA fragments from the X-only hybrid, and 1 of the primers (X2) also generated new DNA fragments on 3-only and 21-only hybrids when used in conjunction with Alu or LINEs primers. In all but one case, consensus alphoid primers generated new chromosome-specific fragments in PCR reactions with the Alu or LINEs primers. A search for cryptic Alu- or alphoid-alone PCR products as the source for one Alu-alphoid band (chosen at random) was negative. Partial sequencing of products demonstrated that alphoid and Alu sequences were indeed contiguous in some newly synthesized DNA fragments. While Alu or LINEs primers generate smears of DNA fragments on total human DNA, the alphoid-non-alphoid repeat combinations generated electrophoretically distinguishable bands of DNA when the template was total DNA. While these were distinguishable with different chromosome-specific alphoid primers, the DNA fragments were not of the same sizes as those generated with the chromosome-only hybrids.

Animals↗
PubMed1991

Disorganisation: a possible cause of apparent conjoint twinning.

A patient with duplications of the internal organs and external structures of the lower half of the body might have traditionally been explained by incomplete twinning. The presence of a fifth digit-like structure protruding from the lower abdomen and facial and cranial abnormalities suggested that, instead, he might be an example of the disorganisation mutant. However, the presence of cardiac defects was not readily explained by invoking the presence of this mutation.

Abdomen↗
PubMed1990

Use of a probe for the putative sex determining gene, zinc finger Y, in the study of patients with ambiguous genitalia and XY gonadal dysgenesis.

Using reverse genetics, a candidate for the sex determining gene from the Y chromosome has recently been cloned. We have used a DNA probe from this gene to assess the presence of this crucial region of the Y chromosome in patients with sexual ambiguity or gonadal dysgenesis. The DNA from 3 cases of gonadal dysgenesis, one complicated by somatic anomalies and mental retardation, reacted normally with this putative sex determining gene. A patient having a small phallus and pseudovaginal, perineoscrotal hypospadias (PPSH) also had normal Y chromosomal DNA. We hypothesize that the defect in sex determination in all 4 cases is most probably subsequent to the primary sex determining switch.

Adult↗
PubMed1990

Ectopic expression of chloramphenicol acetyltransferase (CAT) in the cerebellum in mice transgenic for a carbonic anhydrase II promoter-CAT construct that is without apparent phenotypic effect.

We have developed six transgenic lines of mice with constructs containing presumptive 5' regulatory regions of carbonic anhydrase II (CA II). Four of the lines contained 1,100 bases of the 5' flanking region of the human CA II gene, and two transgenic lines resulted from a construct containing 500 bases of the 5' flanking region of the mouse CA II gene. Tissue-specific expression of the chloramphenicol acetyltransferase (CAT) gene was not obtained in any of the transgenic lines. One of the transgenic lines was found to have high levels of expression of CAT in cerebellum. This expression persisted through multiple generations and was independent of the parental origin of the transgene. On the assumption that the expression was due to the insertion of the transgene in or near a gene expressed normally in cerebellum, homozygous mice were bred for the transgenic insert to see if a mutation might have been induced. Homozygous mice were found and seemed to be normal in all aspects of their phenotype studied. Thus, in this case, neither the insertion of the gene nor the ectopic expression of CAT seemed to be harmful to the animals.

Animals↗
PubMed1990

The effect of amiloride analogs on taste responses in gerbil.

Amiloride analogs that were designed to inhibit three types of Na+ transport systems (the epithelial Na+ channel, the Na+/H+ antiporter, and the Na+/Ca++ exchanger) were applied to the tongue of the gerbil to determine their effects of electrophysiological taste responses to NaCl, CaCl2, sucrose, and glutamic acid. The pattern of responses from the chorda tympani nerve indicates that the taste of NaCl is almost totally accounted for by the epithelial Na+ channel. Phenamil, an amiloride analog which specifically blocks the epithelial Na+ channel at low concentrations, suppressed the taste responses to 0.03 M NaCl by 97%. The pattern of responses also indicates that the Na+/H+ antiporter and the Na+/Ca2+ exchanger do not mediate salt taste in the gerbil. None of the amiloride analogs blocked taste responses to CaCl2, sucrose, or glutamic acid. It is concluded that the salty taste of NaCl in the gerbil is almost totally mediated by the epithelial Na+ channel, and the kinetics of this channel are identical to amiloride-sensitive sodium channels in other systems.

Amiloride↗
PubMed1990

Inhibition of taste responses to Na+ salts by epithelial Na+ channel blockers in gerbil.

The Na+ transport inhibitor amiloride blocks taste responses to NaCl by 60-70%. The purpose of the present study was to determine if greater inhibition could be achieved with three potent amiloride analogs that are specific for the epithelial Na+ channel: phenamil, 2',4'-dimethylbenzamil, and 3',4'-dichlorobenzamil. Application of phenamil (100 microM) to the anterior tongue blocked integrated responses to NaCl from the chorda tympani nerve by 98.04%, but had no significant effect on sucrose or NH4Cl. This finding suggests that the epithelial Na+ channel alone transduces the taste of NaCl in gerbil. The residual 30-40% of the response that is not blocked by amiloride can simply be explained by the fact that amiloride is less potent than phenamil. On average, 100 microM phenamil blocked responses to Na+ salts with a variety of anions by 94.2%; 100 microM 2',4'-dimethylbenzamil, by 89.83%; and 100 microM 3',4'-dichlorobenzamil, by 72.56%. Small residual responses to salts of glutamate and phosphate were not eliminated by the amiloride analogs; this suggests that other transduction mechanisms may account for a small portion of taste responses for these salts in the gerbil.

Amiloride↗
PubMed1990

Post-meiotic gene expression.

Evolutionary arguments and well-designed experiments (based on false premises, however) had suggested that post-meiotic gene expression did not occur in animals. The techniques of molecular genetics have now clearly demonstrated such genetic activity in mammalian testes. The current problem is to understand why some classes of genes, such as Zfy and many oncogenes, are expressed in this manner.

Animals↗
PubMed1990

Major effects on teratogen-induced facial clefting in mice determined by a single genetic region.

A major correlation has been found between the incidence of glucocorticoid-induced cleft palate and the chromosome 8 segment identified by N-acetyl transferase in mice. The resistant strain became fully susceptible while the susceptible strain became resistant when this chromosomal region, representing less than 0.7% of the genome, was transferred from one strain to the other by the construction of congenic strains. 6-Aminonicotinamide-induced cleft palate and phenytoin-induced cleft lip with or without cleft palate are also influenced by this genetic region but not as strongly. In both cases the susceptible strain became quite resistant to the teratogen-induced clefting when the N-acetyl transferase region of chromosome 8 was transferred. However, this chromosomal region does not make the resistant strain susceptible to these two teratogens.

6-Aminonicotinamide↗