Characterization of human hairbulb tyrosinase: properties of normal and albino enzyme

Human hairbulb tyrosinase from normally pigmented and tyrosinase-positive oculocutaneous albino (TPA) hairbulbs was studied by single hairbulb and by pooled hairbulb assay procedures. The response to temperature and pH was the same for TPA and normal enzyme. The Km for tyrosine as substrate and the Km or dopa as cofactor was the same for TPA and normal enzyme. These studies show that TPA tyrosinase is kinetically normal and that the defect with this form of albinism must be elsewhere in the melanin pathway.

Ultrastructural study of hereditary benign intraepithelial dyskeratosis

Specimens taken from the buccal mucosa of two patients with hereditary benign intraepithelial dyskeratosis (HBID) were studied with the transmission electron microscope. Ultrastructural features were described and compared with those of white sponge nevus and Darier's disease. Ultrastructural findings in HBID revealed the presence of numerous vesicular bodies in immature dyskeratotic cells, densely packed tonofilaments filling the cytoplasm of mature dyskeratotic cells, and the disappearance of cellular interdigitations and desmosomes in mature dyskeratotic cells.

Detection of heterozygotes for tyrosinase-negative oculocutaneous albinism by hairbulb tyrosinase assay

Five heterozygotes for ty-neg OCA had absent or markedly reduced hairbulb tyrosinase activity, when compared to normally pigmented control subjects. Clinically, all five were fully pigmented and could not be distinguished from the normal control subjects. It is proposed that the quantitative hairbulb tyrosinase assay can be used to detect heterozygotes for ty-neg OCA. A mechanism to explain the low levels of activity in the hairbulbs from heterozygotes is discussed.

The Hermansky-Pudlak syndrome. Evidence for a lowered 5-hydroxytryptamine content in platelets of heterozygotes

A Dutch kindred with the Hermansky-Pudlak syndrome (HPS) is described. We show for the first time evidence of a lowered platelet 5-hydroxytryptamine content in obligate heterozygotes. Platelet ATP and ADP levels and ATP/ADP ratio were normal in these patients. Platelet aggregation with ADP, collagen and adrenaline was within the normal range. In contrast to the homozygous HPS patients the heterozygotes are normally pigmented and none has diaphanous irides, nystagmus or a bleeding tendency. All homozygous HPS patients have the typical triad of oculocutaneous albinism, pigmented macrophages in the bone marrow and a bleeding disorder, based on a platelet dysfunction. The platelets showed the typical characteristics of a storage pool deficiency. Their platelet factor 3 availability was decreased and the aggregation patterns showed an absent second wave with ADP, adrenaline and absent collagen aggregation. Platelet ADP levels were strongly decreased in all homozygous HPS patients, whereas ATP was lowered only in 3 out of 6 HPS patients. The 5-hydroxytryptamine content of their platelets was very low (15-20% of normal).

[Globodontia--a new familial tooth abnormality]

A new, congenital anomaly of tooth form transmitted as an autosomal dominant trait was found in a father and two of his three sons. While the incisors appeared unchanged, the posterior teeth have characteristic massive globe-shaped crowns with irregularly arranged, rounded cusps. The occlusal surfaces resemble in their extreme form the underside of a tomato. The relation to the otodental syndrome is not clear as yet.

The influence of prostaglandin G2 on platelet ultrastructure and platelet secretion

Prostaglandin G2 (PGG2) is a labile endoperoxide produced physiologically following exposure of platelets to aggregating agents. We report here studies using isolated PGG2. This agent stimulates a concentration-dependent internal platelet contraction very similar to that produced by the calcium ionophore A23187. EDTA prevented platelet aggregation but did not prevent PGG2-stimulated internal contraction or secretion. In contrast, prostaglandin E1 and dibutyryl cyclic AMP inhich selectively labilizes platelet granules, was added to platelets together with PGG2 there was a superadditive effect on platelet secretion. Thus, granule labilization induced by PMA is a separable phenomenon and complementary to the effect of PGG2 on contraction. The ultimate degree of secretion is dependent on both processes. Studies using additional inhibitors supported the hypothesis that PGG2 activates platelets (either directly or following conversion to thromboxane A2) by transporting calcium from an intracellular store to the cytoplasmic site of the platelet contractile proteins.

Clinical aspects of dental anomalies

Many inherited disorders have oral manifestations which can be detected on dental radiographs as alterations in the morphology or chemical composition of the teeth. Thus the dentist may be the first to detect disorders of development and metabolism of importance to the general health of the patient and his family. In one group of conditions the pulp chamber is larger than normal. This may be associated with taurodontism in such conditions as polyploidy of the -X chromosome and trisomy-21 or Down's syndrome. Taurodontism also occurs in a variety of other syndromes including the tricho-dento-osseous syndrome described by Robinson, Miller and Worth (1966) and Mohr's syndrome. It may also be associated with scanty hair endoligodentia. In certain metabolic conditions the pulp chamber may be enlarged but the teeth are of relatively normal from (cynodont). Such cases include hypophosphatemic vitamin D-resistant and dependent rickets, pseudo-hypoparthyroidism otodental syndrome and hypophosphatasia. Small pulp chambers and associated anomalies of root morphology also occur in hereditary disorders either alone or as part of various syndromes such as dentino-osseous dysplasia and brackioskeletogenital syndrome. Dentinogenesis imperfecta may occur alone or as one manifestation of osteogenesis imperfecta. Other developmental defects including pulpal dysplasia, labodontia and dens invaginatus are also associated with small pulp chambers.

Glycosaminoglycans of EDTA soluble and insoluble dentin in dentinogenesis imperfecta type I

A study of glycoasminoglycans (GAGs) in dentinogenesis imperfecta Type I (DI I) revealed increased GAG in DI I EDTA soluble dentin as compared to controls. EDTA insoluble GAG contained less GAG than age-matched controls. The role of GAG in dentin pathosis is discussed.

Globodontia in the otodental syndrome

A family of Polish extraction was studied in which massive, globe-shaped posterior teeth were found in a father and two of his sons, similar to those described in a previous family in which persons with this type of teeth also had a high-frequency sensorineural deafness. The audiograms in this family showed high-frequency air-conduction thresholds in the father and one son with globodontia and in other relatives without the tooth defect. The other son with abnormal teeth had a normal-appearing audiogram. Absence of premolar teeth and yellow-white spots of local hypomaturation of enamel on canine teeth were also findings in this kindred, as reported or observed in other kindreds. The disorder illustrates the problem of variable expressivity of a trait which makes it difficult to predict the risk of having an affected child when only one feature of a syndrome is present in a relative of a fully affected patient.

Influence of prostaglandins E1, E2, and arachidonate on melanosomes in melanocytes and keratinocytes of anagen hair bulbs in vitro

Anagen hair bulbs were collected and maintained in organ culture for periods up to 24 hr. Prostaglandin E1, E2 and arachidonate were introduced to the cultures and stimulated a series of cellular events characterized by peripheral orientation of microfilaments in the dendritic processes of melanocytes, complexing of melanosomes; and degradation of melanosomes within keratinocytes. These events were dependent on the concentration of prostaglandins. In addition, the most potent agent for these events was arachidonate. The action of arachidonate was hypothesized to occur through the production of endogenous prostaglandins since arachidonate was ineffective in the presence of inhibitors of prostaglandin synthetase.

Labile aggregation stimulating substance (LASS): the factor from storage pool deficient platelets correcting defective aggregation and release of aspirin treated normal platelets

Mixtures of equal volumes of Hermansky-Pudlak (HP) syndrome (adenine nucleotide storage pool deficient) and aspirin treated (AT) platelets (inhibited release of adenine nucleotides) undergo irreversible aggregation when exposed to collagen or adrenaline, whereas neither alone will do so. The present investigation has explored the basis for the mutual correction. Correction in the mixed system was accompanied by release of significant amounts of [14C]5-hydroxy-tryptamine from the AT platelets, whereas very little isotope was released when AT platelets alone were exposed to collagen. The correction of aggregation and the release of isotope could both be suppressed by pre-treating HP platelets with aspirin. Labile aggregation stimulating substance (LASS) composed of two closely linked intermediates of prostaglandin (PG) E2 and PGF2alpha biosynthesis, produced using a microsomal fraction of HP platelets, could correct the aggregation and secretion defect of AT platelets exposed to collagen. These findings indicate that HP platelets when mixed with AT platelets and exposed to collagen secrete a substance which is responsible for the correction. LASS, identified as the factor involved, acted as an intercellular messenger which mediated the correction by overcoming the influence of aspirin on normal cells.

Autosomal dominant hypodontia with nail dysgenesis. Report of twenty-nine cases in six families

Clinical details of twenty-three of twenty-nine cases of hypodontia and nail dysgenesis are presented. The classic features of severe hypodontia and a distinctive congenital nail defect were found in all families. The use of a simple method of sweat testing disclosed a minor deficiency of sweating in one family.

Hypoplastic enamel, onycholysis, and hypohidrosis inherited as an autosomal dominant trait. A review of ectodermal dysplasia syndromes

A syndrome consisting of a hypocalcified-hypoplastic enamel, onycholysis with subungual hyperkeratosis, seborrheic dermatitis of the scalp, and hypofunction of the sweat glands with rough dry skin is inherited as an autosomal dominant trait in a kindred of Caucasian ancestry.