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Biomedical subjects

M Melnick

Publications and source records attributed to M Melnick.

At least 109 records · Page 6Linked to original sources
PubMed1976

Allelic restriction: a biologic alternative to multifactorial threshold inheritance.

Contrary to the argument regarding the conservatism of the multifactorial threshold model for describing the inheritance of congenital malformations, little biological insight has resulted from the series of tautological, albeit grandiose, mathematical assumptions currently comprising the basis for this hypothesis. The working hypothesis of this presentation is to apply the "allelic restriction" model to the genesis of common human congenital malformations. New population data concerning isolated cleft palate closely fit the predictions of the proposed hypothesis. Recognising the heterogeneity of cleft palate as well as other common congenital malformations (namely, the difference between phenocopies, definable syndromes, and true hereditary cases), the "allelic restriction" model accords with the apparent greatly "reduced penetrance" of the heriditary cases. This model is meant to apply only to those congenital malformations which have both a high population frequency and a relatively small number of families showing an atypical type of vertical transmission.

Adult↗
PubMed1976

Periodontosis: a phenotypic and genetic analysis.

Two families who provide additional data concerning the metabolic, radiographic, and clinical parameters of periodontosis are presented. These findings include decreased serum alkaline phosphatase levels with absent liver isozyme fractions, decreased tubular bone over-all width and medullary space with relatively increased cortical area, and at least one case of primary dentition alveoloclasia with no permanent dentition alveoloclasia. In addition, a segregation analysis was performed on these two families and all completely reported families found in the literature. The results indicate that periodontosis is most probably inherited as an X-linked, dominant trait with decreased penetrance but relatively consistent gene expressivity. The female: male ratio of affected persons is approximately 2:1, and there is an over-all deficiency of males in these affected families.

Female↗
PubMed1976

Aarskog syndrome: new oral-facial findings.

The Aarskog syndrome is characterized by short stature with typical facial, digital and genital anomalies. A further case is reported which presented with the uncommon finding of ophthalmoplegia and three previously unreported oral-facial findings: enamel dysplasia, a "col" deformity of the anterior mandible and a paresis of the facial muscles innervated by the VII cranial nerve. The implications of genetic heterogeneity in this nosologic classification are discussed.

Abnormalities, Multiple↗
PubMed1976

Familial branchio-oto-renal dysplasia: a new addition to the branchial arch syndromes.

The present report concerns a two-generation family of nine individuals in which the father and three of the six living children all had: (1) a mixed hearing loss with a Mondini type cochlear malformation and stapes fixation; (2) cup-shaped, anteverted pinnae with bilateral prehelical pits: (3) bilateral branchial cleft fistulas; and (4) bilateral renal dysplasia and anomalies of the collecting system. The father and one affected son also had aplasia of the lacrimal ducts. A fourth child who died at 5 months of age was reported to have branchial cleft fistulas and bilateral polycystic kidneys at autopsy. In addition, the concept of noso-embryologic communities is presented. Such groups are composed of syndromes whose total phenotypic spectra not only overlap but also share common elements in embryogenesis. This concept is illustrated with a group of branchial arch syndromes that are related in this way.

Abnormalities, Multiple↗
PubMed1975

Odontomatosis.

Explore the source record for details and available documents.

Adult↗
PubMed1975

Orofaciodigital syndrome, type I: a phenotypic and genetic analysis.

An additional family with the orofaciodigital syndrome. Type I, is presented. On the basis of previously published pedigrees, as well as the present case, data are presented that conclusively support an X-linked dominant mode of inheritance. Segregation analysis demonstrated that not only is there lethality in the male but there is significant lethality in the female due to lyonization. In addition, a review of the familial cases will demonstrate a large degree of intra- and interfamilial variation.

Abnormalities, Multiple↗
PubMedDate not supplied

The neural consequences of repetition: clinical implications of a learning hypothesis.

Repetitive strain injuries (RSIs) are difficult to treat. Some individuals with RSIs may ultimately develop chronic pain syndromes or movement problems like focal hand dystonia (FDh), a disorder of motor control manifested in a specific context during skilled, hand tasks. This paper reports on the results of four neuroplasticity studies suggesting that repetitive hand opening and closing can lead to motor control problems, measurable somatosensory changes, and problems in graphesthesia and stereognosis. The experiments support a learning hypothesis for the origin of severe RSIs, particularly FDh. This degradation in the sensory representation of the hand may not only explain the therapeutic challenge of returning these patients to work, but also provide a foundation for developing more effective physical rehabilitation strategies. Implications and conjectures for the applications of this learning hypothesis to conditions of chronic pain are also discussed.

Adult↗
PubMedDate not supplied

Neural tube defects, methylenetetrahydrofolate reductase mutation, and north/south dietary differences in China.

There is a well-recognized correlation between methylenetetrahydrofolate reductase (MTHFR) C677T mutation homozygosity, elevated plasma homocysteine, and increased risk of neural tube defects (NTDs). This risk is modulated by maternal and fetal folate levels provided provided by diet or supplement. Although the frequencies of the C677T mutation are nearly identical between north and south China, the incidence of NTDs is nearly 5 times greater in the north than in the south. This dramatic difference appears related to the fact that dietary sources of folate are more plentiful and varied in South China.

China↗
PubMedDate not supplied

H-2 haplotype and heterochronic orofacial morphogenesis in congenic mice: consideration as a possible explanation for differential susceptibility to teratogenesis.

For over 40 years it has been known that genetically different inbred strains of mice have different degrees of susceptibility to corticosteroid-induced cleft palate. Gene(s) at or near the H-2 region on chromosome 17 have been implicated. One postulated explanation is that the strain difference in susceptibility is not related to differential corticosteroid action, but to differences in normal developmental pattern. Studies have demonstrated significant quantitative differences between inbred strains for a number of growth variables relative to palatal development. It is also known that there are genes at or near the H-2 complex that influence pre- and post-implantation development. Thus, we sought to determine the relationship in H-2 congenic mice between haplotype differences and variation in normal orofacial development. Morphometric analyses of the palatal region in serially sectioned E13 and E17 B10 and B10.A mice were completed. We were able to find some evidence for H-2 haplotype related phenotypic differences, but these differences are less than compelling as an explanation for haplotype-dependent susceptibility differences. A more likely explanation is GR-mediated differential corticosteroid responsiveness and its consequent effects on palatal shelf growth.

Adrenal Cortex Hormones↗