PubMed Health⌕ Search

Biomedical subjects

K Morgan

Publications and source records attributed to K Morgan.

At least 199 records · Page 11Linked to original sources
PubMed1993

Type II collagen autoimmunity and Ménière's disease.

Antibodies to type II collagen have been reported by some authors to be raised in patients with Ménière's disease. In this study the antibody levels to type I and II collagen have been measured in 37 patients with Ménière's disease and 20 controls, using a solid-phase, double-antibody, enzyme-linked, immunoassay. No significant difference in antibody levels between the two groups was found. These findings do not support previously reported work which suggests that some cases of Ménière's disease are due to type II collagen autoimmunity.

Animals↗
PubMed1993

Point mutation in a 3' flanking sequence of the alpha-1-antitrypsin gene associated with chronic respiratory disease occurs in a regulatory sequence.

A point mutation in the 3' flanking sequence of the alpha-1-antitrypsin gene is associated with chronic respiratory disease. This study demonstrates that the mutation occurs in a motif that binds a nuclear factor. A direct consequence of the mutation is the loss of specific binding. Functional studies with constructs containing this region downstream of a reporter gene in the sense orientation demonstrated that the wild type sequence increased expression compared with control promoter plasmid and there was a significant reduction in expression by the mutant sequence. These effects were demonstrated in three distinct cell lines suggesting an ubiquitous rather than a tissue-specific effect. However, transacting factors may influence the response in different tissues. The mutation does not appear to affect basal expression of the protein as the plasma concentration of alpha-1-antitrypsin is normal in individuals who carry the mutation. However, the binding and functional studies suggest that it may reduce the three- to four-fold rise in plasma alpha-1-antitrypsin concentration that occurs during inflammation.

Base Sequence↗
PubMed1993

Genetic mapping of the breast-ovarian cancer syndrome to a small interval on chromosome 17q12-21: exclusion of candidate genes EDH17B2 and RARA.

A susceptibility gene for hereditary breast-ovarian cancer, BRCA1, has been assigned by linkage analysis to chromosome 17q21. Candidate genes in this region include EDH17B2, which encodes estradiol 17 beta-hydroxysteroid dehydrogenase II (17 beta-HSD II), and RARA, the gene for retinoic acid receptor alpha. We have typed 22 breast and breast-ovarian cancer families with eight polymorphisms from the chromosome 17q12-21 region, including two in the EDH17B2 gene. Genetic recombination with the breast cancer trait excludes RARA from further consideration as a candidate gene for BRCA1. Both BRCA1 and EDH17B2 map to a 6 cM interval (between THRA1 and D17S579) and no recombination was observed between the two genes. However, direct sequencing of overlapping PCR products containing the entire EDH17B2 gene in four unrelated affected women did not uncover any sequence variation, other than previously described polymorphisms. Mutations in the EDH17B2 gene, therefore do not appear to be responsible for the hereditary breast-ovarian cancer syndrome. Single meiotic crossovers in affected women suggest that BRCA1 is flanked by the loci RARA and D17S78.

17-Hydroxysteroid Dehydrogenases↗
PubMed1993

Antibodies to type II collagen in early rheumatoid arthritis.

Antibodies to native and denatured type II collagen were investigated in a group of 79 patients with rheumatoid arthritis (RA) of disease duration less than 12 months (median 8 months; range 3-12 months). Using a solid-phase ELISA to measure these antibodies, the incidence of patients with levels above the upper limit of normal (mean of normal plus 3 SD) was low as compared to previous findings in patients with established disease. The majority of positive sera contained small amounts of IgM antibodies to denatured type II collagen whilst a few had IgG antibodies to native and denatured type II collagen. These findings suggest that the production of high levels of serum anti-type II collagen antibodies in patients with RA is a secondary phenomenon, which may exacerbate the disease rather than be a primary cause of disease.

Adult↗
PubMed1993

Epitopes on the CB-11 peptide of type II collagen recognized by antibodies from patients with rheumatoid arthritis.

Using the technique of epitope scanning, the binding sites of antibodies to the CB-11 peptide of type II collagen, which is known to induce an inflammatory arthritis in animal models, have been investigated. Sera from seven patients have been tested against 272 peptides representing the CB-11 sequence, each patient produced a different profile of antibody binding and a number of epitopes have been identified. The specific nature of this binding has been established by the reduction in binding by absorption with type II collagen. The reactivity of sera from a further 13 patients, to peptides representing the two most frequently recognized epitopes, has been assessed.

Amino Acid Sequence↗
PubMed1993

Depressed beta-adrenergic receptor- and endothelium-mediated vasodilation in conscious dogs with heart failure.

Peripheral vasodilator responsiveness was examined in pacing-induced heart failure (HF) in 11 conscious dogs chronically instrumented for measurement of systemic (total peripheral resistance [TPR]) and local (iliac blood flow) vascular resistance. Dose responses to isoproterenol (ISO), acetylcholine (ACh), and nitroglycerin (NTG) were examined in the same dogs before pacing (control) and after 4 to 7 weeks of rapid ventricular pacing, which induced congestive HF, characterized by increased left ventricular end-diastolic pressure (6.7 +/- 0.4 [control] versus 28 +/- 1.5 [HF] mm Hg) and decreased cardiac output (-30 +/- 5%) and left ventricular dP/dt (-53 +/- 3%), as well as ascites and peripheral edema. In the control state, TPR fell by 57 +/- 2% in response to ISO (100 ng/kg), by 61 +/- 3% in response to ACh (3 micrograms/kg), and by 55 +/- 2% in response to NTG (10 micrograms/kg). In HF, smaller decreases (P < .05) in TPR were observed with the same doses of ISO (-50 +/- 2%) and ACh (-49 +/- 2%) but not with NTG (-58 +/- 3%). Depressed responses to systemic ISO and ACh, but not NTG, were observed in HF in the presence of ganglionic blockade and also after local administration of smaller doses of the drugs in the absence of ganglionic blockade, but where systemic effects were not elicited. Inhibition of nitric oxide synthase increased TPR to a greater degree before HF (+154 +/- 28% [control]) than after (+80 +/- 22% [HF]) and eliminated the depressed responses to ACh but not to ISO. beta-Adrenergic receptor density, as determined by 125I-cyanopindolol binding in membrane preparations from mesenteric vessels was significantly decreased after HF (130 +/- 3 [control] versus 100 +/- 8 [HF] fmol/mg, P < .05) without any change in affinity. Thus, peripheral vascular beta-adrenergic receptor downregulation occurs in HF, independent of altered endothelium-mediated peripheral vasodilation.

Acetylcholine↗
PubMed1993

X-linked nephrogenic diabetes insipidus mutations in North America and the Hopewell hypothesis.

In X-linked nephrogenic diabetes insipidus (NDI) the urine of male patients is not concentrated after the administration of the antidiuretic hormone arginine-vasopressin. This disease is due to mutations in the V2 receptor gene that maps to chromosome region Xq28. In 1969, Bode and Crawford suggested that most NDI patients in North America shared common ancestors of Ulster Scot immigrants who arrived in Halifax in 1761 on the ship Hopewell. A link between this family and a large Utah kindred was also suggested. DNA was obtained from 17 affected male patients from the "Hopewell" kindred and from four additional families from Nova Scotia and New Brunswick who shared the same Xq28 NDI haplotype. The Utah kindred and two families (Q2, Q3) from Quebec were also studied. The "Hopewell" mutation, W71X, is a single base substitution (G-->A) that changes codon 71 from TGG (tryptophan) to TGA (stop). The W71X mutation was found in affected members of the Hopewell and of the four satellite families. The W71X mutation is the cause of X-linked NDI for the largest number of related male patients living in North America. Other families (Utah, Q2 and Q3) that are historically and ethnically unrelated bear other mutations in the V2 receptor gene.

Amino Acid Sequence↗
PubMed1993

Incidence of dementia in a representative British sample.

In a four-year follow-up study of 1042 elderly people (aged 65 years or older), randomly sampled from the community, levels of dementia were assessed using a two-phase case-finding procedure (screening followed by clinical interview) among survivors. Clinical information on those not reinterviewed was provided by death certificates, hospital case notes, or postal questionnaires. The weighted four-year cumulative incidence of dementia was 3.7% (95% confidence intervals: 2.4%-5.0%), with age-specific rates of 0.9%, 2.8%, 5.2%, 9.0%, and 8.7% for the age groups 65-69, 70-74, 75-79, 80-84, and 85-89 years respectively. While consistent with data from other British regions, it remains likely that these rates underestimate true incidence.

Aged↗
PubMed1993

Identification of the M1101K mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene and complete detection of cystic fibrosis mutations in the Hutterite population.

The Hutterite population is a genetic isolate with an increased incidence of cystic fibrosis (CF). Previously we identified three CF haplotypes defined by polymorphisms flanking the CF transmembrane conductance regulator (CFTR) gene. delta F508 was present on one of the haplotypes in only 35% of CF chromosomes. We hypothesized that the other two CF haplotypes, one of which was the most common and the other of which is rare, each harbored different non-delta F508 mutations. Single-strand conformation polymorphism analysis detected a missense mutation, M1101K, in both chromosomes of a Hutterite patient carrying the two non-delta F508 haplotypes. M1101K appears to have originated on an uncommon CFTR allele and to be infrequent outside the Hutterite population. The presence of M1101K on two haplotypes is likely the result of a CFTR intragenic recombination which occurred since the founding, 10-12 generations ago, of the Hutterite population. The crossover was located between exons 14a and 17b, an interval of approximately 15 kbp. delta F508 and M1101K accounted for all of the CF mutations in patients from 16 CF families representing the three subdivisions of the Hutterite population.

Adolescent↗
PubMed1992

p53 mutations in formaldehyde-induced nasal squamous cell carcinomas in rats.

Formaldehyde induces squamous cell carcinomas in the nasal passages of rats following chronic inhalation exposure at concentrations of > or = 10 ppm. We have examined the complementary DNA of the tumor suppressor gene p53 from 11 primary formaldehyde-induced tumors for mutation using DNA sequence analysis. A polymerase chain reaction-amplified fragment of the rat p53 complementary DNA containing the evolutionarily conserved regions II-V was directly sequenced from each tumor. Point mutations in the p53 complementary DNA sequence were found in 5 of 11 of the tumors analyzed. These data demonstrate p53 point mutations in formaldehyde-induced squamous cell carcinomas and indicate a common alteration in certain rat and human squamous cell carcinomas of the respiratory tract.

Animals↗
PubMed1992

Cystic fibrosis mutations in French Canadians: three CFTR mutations are relatively frequent in a Quebec population with an elevated incidence of cystic fibrosis.

The French-Canadian population in the Saguenay-Lac St. Jean region of northeastern Quebec has an elevated frequency of cystic fibrosis (CF). The average incidence of cystic fibrosis was 1 in 891 births and the prevalence of CF carriers was estimated to be 1 in 15. We tested for 10 mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene in 133 French-Canadian CF families from Quebec. Ninety-one families were from the Saguenay-Lac St. Jean region and 42 families were referred from other regions of Quebec. We detected the CFTR mutation in 93 and 92% of the CF chromosomes in the Saguenay-Lac St. Jean and the major-urban Quebec families, respectively. The two groups of French-Canadian families were significantly different for the proportions of CFTR mutations. The three most common mutations in the Saguenay-Lac St. Jean families were delta F508 (58%), 621 + 1G----T (23%), and A455E (8%); and in the major-urban Quebec families were delta F508 (71%), 711 + 1G----T (9%), and 621 + 1G----T (5%). These results provide evidence for the role of founder effect in the elevated incidence of cystic fibrosis in the Saguenay-Lac St. Jean population.

Cystic Fibrosis↗
PubMed1992

Atrial natriuretic peptide in portal vein-ligated rats: alterations in cardiac production, plasma level and glomerular receptor density and affinity.

The atrial natriuretic peptide hormonal system is altered to a variable degree in patients with cirrhosis. Portal pressure and portal-systemic shunting are also varied in cirrhosis. We used a portal vein-ligated rat model with predictable portal hypertension to study the effects of portal hypertension alone on the atrial natriuretic peptide hormonal system. Sham-operated rats were used as controls. Mean portal pressure was significantly increased in portal vein-ligated rats (portal vein-ligated rats, 21.7 +/- 0.74 cm H2O; sham-operated rats, 13.7 +/- 0.47 cm H2O; p less than 0.0001). Plasma atrial natriuretic peptide decreased 50% in the portal vein-ligated rats (p less than 0.0001). Atrial natriuretic peptide messenger RNA level was decreased by 40% to 60% in the left and right atria and in the ventricles of portal vein-ligated rats (p less than 0.05 for each chamber). Only one class of glomerular binding site was identified by competitive binding studies. The atrial natriuretic peptide glomerular receptor density increased in the portal vein-ligated rats (portal vein-ligated rats, 1,660 +/- 393; sham-operated 725 +/- 147 fmol/mg protein, p less than 0.02), whereas affinity decreased (portal vein-ligated, 1.69 +/- 0.49; sham-operated, 0.55 +/- 0.12 nmol/L, p less than 0.02). No difference was seen in the amount of cyclic GMP generated by atrial natriuretic peptide stimulation in isolated glomeruli from portal vein-ligated and sham-operated rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Two hereditary defects related to vitamin D metabolism map to the same region of human chromosome 12q13-14.

We have localized the locus for the vitamin D receptor (VDR) responsible for hypocalcemic vitamin D-resistant rickets (HVDRR), close to the pseudovitamin D-deficient rickets (PDDR) locus, another disorder related to impaired vitamin D metabolism. PDDR (formerly vitamin D dependency type I, VDD1) was recently mapped to human chromosome 12q14 by linkage analysis. Here we report on the assignment of VDR to 12q13-14 by in situ hybridization and by linkage analysis. Linkage analysis between VDR, PDDR, and several RFLP markers show close linkage, with no recombination (theta = 0) between VDR and PDDR (Z = 1.94), a COL2A1 haplotype (Z = 4.03), ELA1 (Z = 0.98), and D12S15 (Z = 4.17). The analysis of extended haplotypes in one of the PDDR families provides evidence for recombination between VDR and PDDR and localizes VDR together with COL2A1 proximal to PDDR. Complete allelic association detected between VDR and COL2A1 loci on PDDR chromosomes and lower association between VDR and PDDR suggests a VDR location very close to COL2A1 and one more distant to PDDR. We propose the following order of loci: (VDR, COL2A1), (PDDR, ELA1, D12S15), D12S4, (D12S14, D12S17), D12S6. Thus, two clearly distinct loci involved in the control of vitamin D activity map close to each other in the region 12q13-14.

Chromosomes, Human, Pair 12↗
PubMed1992

Increased glomerular atrial natriuretic peptide receptor affinity in experimental nephrotic syndrome.

Atrial natriuretic peptide (ANP) is a cardiac hormone with natriuretic and diuretic effects. To better define the ANP hormonal system in the nephrotic syndrome, a condition associated with renal sodium retention, we undertook a study of glomerular ANP receptors in rats with puromycin aminonucleoside-induced nephrotic syndrome and in pair-fed controls. Nephrotic rats had significantly decreased serum albumin and total protein and significantly increased serum cholesterol, triglycerides and 24 hour urinary protein excretion. Plasma level of atrial natriuretic peptide was similar in both groups of rats. Competition binding inhibition studies in isolated glomeruli demonstrated one binding site in both groups of rats. The density of ANP binding sites in isolated glomeruli was similar in nephrotic and pair-fed rats while the binding affinity was increased significantly in the nephrotic rats. This is the first study to demonstrate alterations in renal ANP receptors in the nephrotic syndrome. Further studies will be necessary to determine whether alterations in glomerular ANP receptors contribute to renal sodium retention in the nephrotic syndrome.

Animals↗