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Biomedical subjects

K Morgan

Publications and source records attributed to K Morgan.

At least 253 records · Page 14Linked to original sources
PubMed1990

Recurrence risks for near relatives of children with sensori-neural deafness.

In a sample of children with sensori-neural deafness and no evidence of a syndrome, ototoxic exposure, or autosomal dominant or X-linked family history, seen in the Division of Medical Genetics of The Montreal Children's Hospital, the probability of a sibling being similarly affected was about 1 in 6, both in French-Canadian families and the remainder of the sample. The frequency of deafness of early onset was measured in the uncles and aunts of probands, and these figures were used to derive approximate recurrence risks for the offspring of probands (about 1 in 130, ignoring the possibility of autosomal dominant mutation) and for the offspring of the probands' unaffected sibs (about 1 in 250). A rough estimate of the number of autosomal recessive loci contributing to sensori-neural deafness is derived as 13.

Child↗
PubMed1990

X-linked hypophosphatemia: the mutant gene is expressed in teeth as well as in kidney.

Mutation at a locus (HPDR) on the X chromosome (McKusick 30780 [HPDR1]; 30781 [HPDR2]) causes impaired renal phosphate transport, hypophosphatemia, and an associated impairment in the process of mineralization in bone and teeth (X-linked hypophosphatemia [XLH]). We measured the dental pulp profile area (PRATIO [= pulp area/tooth area]) and serum phosphorus (Pi) values in uniformly treated XLH patients (six males, 81 teeth, 1,457 Pi values; 11 females, 129 teeth, 1,439 Pi values). Serum Pi values, reflecting the metabolic environment of tooth development, were obtained by repeated measurement between 1 mo and 26 years of age during treatment. PRATIO values calculated from standardized Rinn radiographs were used as outcome measurements of tooth development in XLH patients and in age-matched controls (12 males, 100 teeth; 27 females, 275 teeth). Age-dependent serum Pi values were not different in the treated XLH males and females. In teeth forming primary dentin there was no gene dosage effect on PRATIO values apparent in subjects below 15 years of age. However, in teeth forming secondary dentin a gene dosage was found in the subjects aged 15 to 25 years: XLH male teeth (n = 65) mean +/- SD = 0.163 +/- 0.046; XLH female teeth (n = 75) mean +/- SD = 0.137 +/- 0.039; control teeth (n = 209) mean +/- SD = 0.116 +/- 0.023; (higher PRATIO values mean less development or mineralization of secondary dentin); differences in these PRATIO values (males vs. female and XLH vs. control) were significant by mixed-model analysis of variance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Cystic fibrosis mutations in the Hutterite Brethren.

The presence or absence of the major cystic fibrosis (CF) mutation, delta F508, in the general patient population was determined by Kerem et al. using allele-specific oligonucleotides for the mutant and normal sequences in the polymerase chain reaction (PCR). delta F508 was identified by Riordan et al., and it is a 3-bp deletion of the phenylalanine codon at position 508. The Hutterite Brethren are an inbred North American population who have three different DNA marker haplotypes of CF chromosomes. Genomic DNA from both a CF child and one parent from each of 10 Hutterite families was analyzed for the presence or absence of the deletion mutation. delta F508 is associated with one of the three CF haplotypes in the Hutterite population, and this is the most common haplotype in a subset of the linkage family data of Kerem et al. The other two Hutterite CF haplotypes are generally rate in Caucasian populations. Since these two CF haplotypes do not carry the deletion mutation, they must carry a different CF mutation(s). The results of the PCR analysis for the deletion mutation lend additional support to our previous conclusion that there were at least three original carriers of CF mutations among the founders of the Hutterite population and that all copies of the same CF haplotype were identical by descent. One Hutterite CF patient has both of the haplotypes which do not carry delta F508. Analysis of this individual's DNA should allow identification of two additional CF mutations in this population.

Base Sequence↗
PubMed1989

Bovine cartilage types VI and IX collagens. Characterization of their forms in vivo.

1. Collagens were extracted from bovine cartilage by 4 M-guanidinium chloride in the presence of proteinase inhibitors and identified by immunoblotting with specific anti-collagen sera. 2. The collagens retained their native conformations (shown by the resistance of their triple-helical domains to pepsin digestion), and the molecular masses of their component alpha-chains indicated that the chains were intact. 3. Type VI collagen was extracted as a large-molecular-mass disulphide-bonded aggregate composed of components of molecular mass 140 kDa and 200-240 kDa, and was therefore similar to type VI collagen identified in noncartilaginous tissues. Immunoblotting established the 200-240 kDa components as intact forms of the alpha 3(VI) chain. 4. Type IX collagen consisted of three clearly separable components of molecular mass 84 kDa, 72 kDa and 66 kDa, which were assigned to the alpha 1(IX)-, alpha 3(IX)- and alpha 2(IX)-chains respectively, and a large proportion of this collagen had no covalently bound glycosaminoglycan attached to the alpha 2(IX)-chain. 5. Differences between the type IX collagen extracted from bovine cartilage and that identified in biosynthetic studies on chick cartilage are discussed.

Animals↗
PubMed1989

Non-Hodgkin's lymphoma of the larynx (stage IE).

Four cases of non-Hodgkin's lymphoma (NHL) limited to the larynx are described. All were diffuse, high-grade, B-cell lymphomas of large lymphoid cell type (three centroblastic and one immunoblastic). Immunocytochemistry was performed on three cases; two showed monoclonal cytoplasmic immunoglobulin and one showed monoclonal surface immunoglobulin. In three cases, complete remission was obtained with radical radiotherapy; the fourth patient died suddenly of acute laryngeal obstruction. The cases are compared with other reports of laryngeal non-Hodgkin's lymphoma (NHL) in the literature. The biologic behavior of these tumors has many features in common with other extranodal lymphomas arising from mucosa-associated lymphoid tissue (e.g., a tendency to remain localized for long periods of time and to disseminate to other extranodal and unusual sites, with good response to radiotherapy for both the primary tumor and extranodal recurrences).

Aged↗
PubMed1989

Interaction of inhibitin with the human erythrocyte Na+(Li+)i/Nao+ exchanger.

The kinetic interactions of inhibitin, a peptide isolated from cultured leukaemic promyelocytes, with erythrocyte Na+/Na+ and Na+/Li+ exchanges have been investigated. Inhibitin (1 microM) reduced the ouabain- and bumetanide-resistant sodium efflux and influx by equivalent amounts indicating an inhibitin-sensitive exchange component of 0.52 mmol/l per h. This value was not significantly different from that measured as the difference in sodium-rich (140 mM) and sodium-free media (0.49 mmol/l per h). Similarly, the inhibitin-sensitive lithium efflux was equivalent to the sodium/lithium countertransport component (0.36 vs. 0.34 mmol/l per h), indicating that both exchanges were mediated by the same transport process, which is inhibitin-sensitive. The dose-response curve revealed the presence of a single inhibitin binding site per exchanger with a Ki of 2.10(-7) M. In kinetic inhibition studies, inhibitin (0.1 microM) decreased the Vmax of ouabain- and bumetanide-resistant sodium efflux with no effect on the Km for external sodium, i.e., inhibitin displayed a non-competitive mechanism of action. These findings indicate that inhibitin interacts with the Na+(Li+)i/Nao+ exchanger at a site distinct from the sodium binding site.

Biological Transport↗
PubMed1989

A longitudinal study of anticollagen antibodies in patients with rheumatoid arthritis.

Antibodies to native and denatured collagens (types I, II, IX, and XI) were measured in sequential serum samples collected over 1.5-8.7 years (median 4.3) from 15 patients with rheumatoid arthritis. Eleven patients were seropositive and 4 were seronegative. Disease duration ranged from 3 years to 25 years before the first sample was tested. The patients showed a selective and varying response to collagens, even after disease had been present for a long time. Changes in the levels of antibody to one collagen type were not necessarily linked to changes in the levels of antibody to other collagens. Only some patients showed a strong correlation between C-reactive protein levels (a measure of disease activity) and antibodies to individual collagens. These findings suggest that rheumatoid arthritis patients produce antibodies to a wide variety of epitopes on these collagen molecules, as a result of different antigenic epitopes being exposed by cartilage degradation at different times throughout the disease.

Adult↗
PubMed1989

Flexibility of the shoulder joint measured as range of abduction in a large representative sample of men and women over 65 years of age.

In a representative survey of 1000 elderly men and women aged over 65 years living in their own homes, assessments have been made of flexibility measured as range of shoulder abduction in addition to health status, psychological well-being and reported customary activity. The results for shoulder abduction were approximately normally distributed and the mean values (+/- 1 standard deviation) were as follows: - in men aged 65-74 years, 129 (+/- 14) degrees and aged over 74 years, 121 (+/- 19) degrees; in women aged 65-74 years, 124 (+/- 19) degrees and aged over 74 years, 114 (+/- 22) degrees. These mean values are about 30 degrees less than those accepted for younger subjects. Nearly half the distribution falls below the accepted threshold level of 120 degrees for adequate function. There were significant effects of sex and age (P less than 0.001); women had poorer flexibility and the reduction with age amounted to 10 degrees per decade. Multiple regression analysis showed that the effect of age was accounted for in part by health, strength and customary use. The effects of use were most marked in those with some disability. This suggests that maintained or increased use could offset some of the age-related loss of the range of shoulder movement.

Aged↗
PubMed1989

A model for embryonal rhabdomyosarcoma tumorigenesis that involves genome imprinting.

Embryonal rhabdomyosarcomas (malignant pediatric tumors of striated muscle origin) have been shown to arise from cells that are clonally isodisomic for loci on chromosome 11p. We determined the parental origin of alleles in this genomic region in familial and sporadic cases of this disease and found that isodisomic chromosome 11p alleles in each tumor were of paternal origin. We have developed a modification of Knudson's two-hit model from these data that is capable of explaining the preferential allele retention and of resolving the apparent contradiction between such specific and early events in several embryonal tumors and discrepancies in the inheritance of predisposition in some of these diseases.

Alleles↗
PubMed1989

Factors influencing persistent subjective insomnia in old age: a follow-up study of good and poor sleepers aged 65 to 74.

Of 82 subjective insomniacs aged 65-74 years identified during a community survey and classified on the basis of self-reported sleep quality, 69 (84%) continued to complain of poor sleep when re-interviewed 18-24 months later. When compared with a control group of similarly stable 'good sleepers' (n = 64) drawn from the same community sample these persistent subjective insomniacs showed significantly higher levels of constitutional (trait) and transitory (state) anxiety, and neuroticism. Discriminant analysis indicated that elevated levels of neuroticism, reduced health status (as measured by the number of drugs prescribed) and relatively high levels of tea consumption were most closely associated with persistent complaints of poor sleep. Thus, despite the existence of health problems as a major cause of sleep disturbance in later life, personality factors appear to exert a pervasive influence on subjective sleep quality among the 'younger' elderly.

Aged↗
PubMed1989

Anti-type II collagen antibody in naturally occurring canine joint diseases.

Autoimmunity to collagen was investigated in several naturally occurring arthropathies of the dog. Increased levels of serum anti-native collagen type II antibody, as assessed by ELISA, were shown in 72.4% of dogs with rheumatoid arthritis (RA), 88% of dogs with infective arthritis (IA) and 52% of dogs with osteoarthritis (OA) (p less than 0.001). The mean levels of antibody in cruciate disease patients (CR) were also significantly increased compared to control dogs (p less than 0.01). Serum anti-collagen antibody in OA dogs correlated with that in precipitated serum immune complexes. There was also a correlation between anti-collagen antibody level in synovial fluid and in synovial fluid complexes in dogs with rupture of the cranial cruciate ligament. In all patient groups, collagenase digestion of polyethylene glycol (PEG) precipitates from sera and synovial fluids caused a significant rise in specific antibody levels to collagen, indicating the presence of collagen-anti-collagen complexes in all arthropathies. In dogs with RA, the levels of collagen-specific antibody in synovial fluid complexes correlated with the total IgG in these complexes. These findings implicate collagen-anti-collagen complexes in the pathogenesis of naturally occurring joint diseases in the dog, but they are unlikely to be the primary aetiological mechanism.

Animals↗
PubMed1989

Lymphocyte extracellular matrix interactions. Induction of interferon by connective tissue components.

Limiting dilution analysis was performed in the presence of interleukin 2 (IL-2) on lymphocytes isolated from the synovial fluid (SF) and peripheral blood (PB) of patients with rheumatoid arthritis (RA) and PB of normal donors. Clones of these 'spontaneously' IL-2-responsive cells from PB and SF were compared for their reactivity with components of the extracellular matrix (i.e. native or denatured type I or type II collagen and proteoglycan). It was determined that all clones from both PB and SF were activated to produce interferon (IFN) in the presence of any of the connective tissue components (CTC). Clones derived from normal PB behaved in a similar fashion but produced lower IFN-gamma levels. There was a synergy between the CTC and serum or plasma fibronectin, which was more apparent when soluble CTC were used as the stimuli rather than immobilized CTC. The fibronectin alone was unable to induce IFN-gamma production under any of the conditions tested (i.e. soluble or immobilized). These results demonstrate that clones of IL-2-responsive T cells can be activated by interactions with connective tissue components to produce IFN-gamma.

Cell Communication↗
PubMed1989

Recursive descent probabilities for rare recessive lethals.

Recursively computed descent probabilities provide an effective way to evaluate possible ancestries of rare alleles segregating in large and complex genealogies, but they ignore information other than the descent to a small set of current gene copies. We show how descent probability computations can be modified to incorporate the fact that no ancestor can be affected by a lethal recessive trait. This methodology is applied to two rare recessive traits segregating in a complex Hutterite (Lehrerleut) genealogy.

Alleles↗
PubMed1989

Periodontitis in sheep: a model for human periodontal disease.

The use of sheep as a suitable animal model of destructive forms of human periodontal disease has been assessed from comparative radiological, histological, and serological investigations of sheep with and without periodontal disease. The results showed that, in sheep with periodontitis, bone resorption, collagen breakdown, degradation of blood capillary vessel walls, cellular infiltration of plasma cells, lymphocytes, and epithelial infiltration were significantly greater than in sheep without periodontitis, and the features are similar to those in rapidly destructive forms of periodontal disease in man. The levels of serum IgG antibody reactive against B. gingivalis antigens (measured by ELISA) were significantly higher in sheep with periodontitis than those without, similar to the association reported in some types of human periodontal diseases. These findings suggest that periodontitis in sheep could represent a suitable animal experimental model for certain types of rapidly destructive human periodontal diseases.

Alveolar Process↗
PubMed1989

Familial Wiedemann-Beckwith syndrome and a second Wilms tumor locus both map to 11p15.5.

Wilms tumor of the kidney occurs with increased frequency in association with two clinically and cytogenetically distinct congenital syndromes, the Wiedemann-Beckwith syndrome (WBS) and the triad of aniridia, genitourinary anomalies, and mental retardation (WAGR). Constitutional deletions in the latter situation and similar alterations in sporadic Wilms tumors have implicated the chromosomal 11p13 region in neoplastic development. In contrast, some sporadic cases of WBS have been reported to have a constitutional duplication of chromosome 11p15. In order to resolve this seeming paradox, we have analyzed a family segregating WBS for linkage to DNA markers mapped to chromosome 11p. Consonant with the cytogenetic alterations in sporadic WBS cases, we obtained evidence for tight linkage of the mutation causing the syndrome to markers located at 11p15.5. Also consistent with this localization, we identified a subset of Wilms tumors, not associated with WBS, which have attained somatic homozygosity through mitotic recombination, with the smallest shared region of overlap being distal to the beta-globin complex at 11p15.5. These data provide evidence that familial WBS likely results from a defect at the same genetic locus as does its sporadic counterpart. Further, the data suggest there is another locus, distinct from that involved in the WAGR syndrome, which plays a role in the association of Wilms tumor with WBS.

Beckwith-Wiedemann Syndrome↗