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Biomedical subjects

C J Witkop

Publications and source records attributed to C J Witkop.

At least 37 records · Page 2Linked to original sources
PubMed1987

Agenesis of succedaneous teeth: an expression of the homozygous state of the gene for the pegged or missing maxillary lateral incisor trait.

Agenesis of the permanent teeth that replace the primary teeth, the succedaneous teeth, was found in children from two kindreds wherein both parents had pegged maxillary lateral incisor teeth. The trait small-pegged-missing maxillary lateral incisor teeth is inherited in an autosomal dominant manner, as demonstrated in the literature and in these families. Agenesis of succedaneous teeth is most likely an autosomal recessive trait due to the homozygous state of the gene for small-pegged-missing maxillary incisor teeth.

Adolescent↗
PubMed1987

Elevated urinary dolichol excretion in the Hermansky-Pudlak syndrome. Indicator of lysosomal dysfunction.

The Hermansky-Pudlak syndrome, a triad of albinism, platelets lacking dense bodies, and storage of ceroid-like material in tissues, occurs approximately once in 2,000 northwestern Puerto Ricans. The manifestations of storage disease are variable and include granulomatous colitis, restrictive lung disease, kidney failure, and cardiomyopathy. The autofluorescent material stored in the Hermansky-Pudlak syndrome is histochemically similar to that stored in neuronal ceroid/lipofuscinosis. The material in neuronal ceroid/lipofuscinosis contains dolichols, which are components of lysosomes, and patients show increased urinary excretion of dolichols. This study of 49 patients with the Hermansky-Pudlak syndrome found that urinary dolichol levels are increased in those patients with evidence of ceroid storage in the kidneys but are not elevated when storage occurs in tissues other than the kidneys. The excretion of ceroid was not influenced by the saturation state of dietary fat. A defect in processing of membranes of lysosomes, melanosomes, and dense bodies may be involved in the syndrome.

Albinism↗
PubMed1985

Syndrome of amelogenesis imperfecta, nephrocalcinosis, impaired renal concentration, and possible abnormality of calcium metabolism.

We describe a brother and sister with amelogenesis imperfecta, nephrocalcinosis and impaired renal concentrating ability. This is the second sibship reported, further substantiating autosomal recessive inheritance of this condition. There is lack of enamel, lifelong nocturnal enuresis, progressive punctate nephrocalcinosis, and decreased calcium and phosphate excretion over 24 hours and after an acute load. Increased serum osteocalcin and decreased urine delta-carboxyglutamic acid suggest involvement of vitamin K-dependent calcium binding proteins, although this may represent a secondary finding. No other evidence of abnormal calcium metabolism was found. Renal function is stable in the early teens, but the previously reported patients went on to renal failure.

1-Carboxyglutamic Acid↗
PubMed1985

The questionable relation between cochlear pigmentation and noise-induced hearing loss.

Some evidence has suggested that susceptibility to noise-induced hearing loss may be inversely proportional to the amount of melanin in the cochlea. However, published data have not been consistent in demonstrating this relation, and some results may be contaminated by lack of genetic control in experimental animals. In this investigation, noise-induced hearing loss was evaluated in pigmented and albino C57BL/6J mice that differed only in their ability to produce melanin. Surface-recorded electric responses to sound were used to assess auditory sensitivity. Results indicated no difference between the two groups either in pre-exposure thresholds or in magnitude of noise-induced threshold shift.

Animals↗
PubMed1984

Diagnosis of late infantile neuronal "ceroid-lipofuscinosis" from histochemical and ultrastructural changes in dental pulp.

Sections of dental pulp were removed from a tooth of a boy 3 years 10 months of age with myoclonic seizures. When stained with hematoxylin and eosin, these sections showed eosinophilic inclusions. Ultrastructurally, these inclusions were large cytosomes filled with whorls of electron-opaque substance. The opaque material consisted of bilaminate strands, approximately 15 nm in diameter, arranged in a curvilinear pattern compatible with that seen in the late infantile form of "ceroid-lipofuscinosis." Most histochemical staining reactions were compatible with ceroid or lipofuscin, with the exception of the diamine silver reaction. Late infantile ceroid-lipofuscinosis represents another disease in which asymptomatic accumulation of storage material occurs in the dental pulp.

Child, Preschool↗
PubMed1983

Combined chemical and electron microscopic studies of pheomelanosomes in human red hair.

This study clarified the fine structure of pheomelanosomes in human red hair by quantifying the contents of pheomelanin and eumelanin and by identifying the fine structure of melanocytes and melanosomes based on their melanogenesis type in follicles. Out of 5 red-haired subjects, 3 were found to exhibit pheomelanogenesis in follicles, while the remaining 2 were found to have a mixed type melanogenesis of pheomelanin and eumelanin. Melanocytes in the pheomelanic follicles contained spherical melanosomes which revealed sequences of development identical to those seen in the pheomelanosomes of mice and guinea pigs. In contrast, the follicles of mixed type melanogenesis contained 2 different populations of melanocytes, i.e., one with synthesis of spherical melanosomes such as seen in the pheomelanic follicles and the other with synthesis of ellipsoidal-lamellar (filamentous) granules of eumelanosome form. It was concluded that (a) visual differentiation of hair color does not always reflect the melanogenesis type in human red hair, (b) chemical analysis of melanogenesis type corresponds well to the fine structural differentiation of eumelanosomes and pheomelanosomes, and (c) human pheomelanosomes are spherical granules with microvesicular (vesiculoglobular) and proteinaceous matrices on which melanin deposition is spotty and granular.

Adult↗
PubMed1981

Tyrosinase subcellular distribution and kinetic parameters in wild type and C-locus mutant C57BL/6J mice.

The distribution and kinetic parameters of tyrosinase (EC 1.14.-18.1) from anagen hair follicles of the C57BL/6J mouse and several c-locus mutants were investigated. The results showed that c-locus mutations not only influenced the total tyrosinase activity, but the subcellular distribution as well. The kinetic parameters of tyrosinase were not influenced by the pigment mutations, suggesting that the mutations were not influencing the structure of the enzyme.

Animals↗
PubMed1981

Platelet aggregation independent of ADP release or prostaglandin synthesis in patients with hermansky-Pudlak syndrome.

Platelets from patients with the Hermansky-Pudlak (HPS) syndrome are deficient in the storage pool of adenine nucleotides and serotonin. As a result, the storage pool deficient (SPD) platelets develop only single waves of clumping when stimulated by threshold concentrations of aggregating agents which cause irreversible, biphasic aggregation of normal platelets. Yet, patients with HPS either have no bleeding problems or only mild symptoms. In the present study we have evaluated the importance of prostaglandin synthesis and secretion to the irreversible aggregation of HPS platelets. Results of the study demonstrate that aspirin-treated SPD platelets, which cannot form thromboxane or undergo the release reaction on stimulation by arachidonate, can still undergo irreversible aggregation in response to thrombin and ADP if treated first with epinephrine. A mechanism of membrane modulation mediated by alpha-adrenergic receptors cooperatively linked to the endoperoxide and thromboxane receptor can secure irreversible aggregation of normal or abnormal platelets despite absence of secretion and prostaglandin synthesis.

Adenosine Diphosphate↗
PubMed1980

Auditory brainstem anomalies in human albinos.

Brainstem auditory evoked potentials recorded from human albinos indicate significant hemispheric asymmetry. The asymmetry is symptomatic of differences between decussated and nondecussated auditory pathways in albino and pigmented humans at approximately the level of the superior olivary nuclei. Abnormal decussation of auditory pathways in albinos probably coincides with known visual system anomalies.

Adult↗
PubMed1980

Albinism in Nigeria with delineation of new recessive oculocutaneous type.

Seventy-nine Nigerian oculocutaneous albinos were investigated. Fifty-six had typical tyrosinase-positive albinism (TPA) and 23 had brown albinism (BA), a new oculocutaneous type. The TPA were characterized by localized but no generalized skin pigment, yellow hair, blue to brown irides, nystagmus, and reduced or absent retinal pigment. Localized skin pigment included freckles and lentigines. The iris and skin pigment were the result of the slow accumulation of pigment with age as both were found in older individuals. The most severe skin changes were premalignant keratoses and squamous cell carcinoma of the skin, and the skin malignancies were the major factor in limiting the lifespan for TPA. The BA were characterized by generalized light brown skin pigment, light brown hair, blue to brown irides, nystagmus, and reduced retinal pigment. There was little accumulation or change of pigment in the eyes or skin with age. The generalized light skin pigment was effective in reducing sensitivity to solar radiation and very few BA had premalignant keratoses. Pedigree analysis for BA suggested on autosomal recessive inheritance pattern.

Adolescent↗
PubMed1980

Concurrence of anorexia nervosa and yellow mutant albinism.

A review of published clinical reports shows that anorexia nervosa has been found in association with several genetic anomalies, principally gonosomal aneuploidy. An additional, and unique, association is described here: a case of anorexia nervosa in a patient with the yellow mutant form of oculocutaneous albinism and no other apparent chromosomal abnormalities. While the concurrence of these two disorders in a single person is apparently a chance phenomenon, our review of experimental publications shows that feeding disturbances also occur in yellow mutant mice. Such complementary findings suggest the need for continuing investigation of the genetic foundations of eating behaviour.

Adult↗
PubMed1980

Taurodontism, an isolated trait associated with syndromes and X-chromosomal aneuploidy.

A review of the literature on teeth with enlarged pulp chambers and apical displacement of the bifurcation or trifurcation of roots (taurodontism) and investigation of the association of this trait with X-chromosomal aneuploidy shows that: (1) Taurodontism is not a rare trait in modern man, as indicated by the majority of recent reports, but occurs in approximately 2.5% of adult Caucasians. (2) Taurodontism occurs in syndromes, particularly in those having an ectodermal defect. (3) Among 12 patients showing taurodontic teeth radiographically, all had normal karyotypes. (4) Among 12 patients showing various combinations of X-chromosomal aneuploidy, 11 had taurodontic molars. (5) Patients with a female habitus and X-chromosomal aneuploidy as well as patients with a male habitus and X-chromosomal states have taurodontic teeth. (6) There is no simple association of the degree of taurodontism and the number of X chromosomes, but, in general, patients with the more severe forms of the trait--meso- or hypertaurodontism--are more likely to have X-chromosomal aneuploidy. While taurodontism may be viewed as an extension of a continuous trait of pulp chamber size, the extreme shape may arise when conditions disturbing the epithelial-derived root sheath produce a generalized amplified instability of development, as has been suggested from tissue culture studies of X-chromosomal aneuploid cells.

Adult↗