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Biomedical subjects

M L Williams

Publications and source records attributed to M L Williams.

At least 235 records · Page 13Linked to original sources
PubMed1981

Stratum corneum lipids in disorders of cornification: increased cholesterol sulfate content of stratum corneum in recessive x-linked ichthyosis.

Activity of the microsomal enzyme, steroid sulfatase, is absent in keratinocytes, fibroblasts, and leukocytes of patients with recessive x-linked ichthyosis. This study was undertaken to determine if cholesterol sulfate, a substrate of this enzyme, accumulates in the pathological scale of these patients. Scales from 8 patients with recessive x-linked ichthyosis, 10 patients with other forms of ichthyosis, and normal human outer stratum corneum were extracted with chloroform/water (1:2:0.8 by vol) and lipids were fractionated by quantitative, sequential thin-layer chromatography. Cholesterol sulfate was identified by cochromatography in several solvent systems, by its staining characteristics, by biochemical analysis, and by mass spectrometry. The mean cholesterol sulfate content of recessive x-linked ichthyotic scale was 12.5 +/- 0.8% of the total lipid, a fivefold increase over normal (P less than 0.0025), whereas the cholesterol sulfate content of other ichthyotic scale was normal. This increase in cholesterol sulfate content was accompanied by a decrease in total neutral lipids (P less than 0.0025) and free sterols (P less than 0.025) but no change in sterol esters or total sterols. These results demonstrate that deficiency of steroid sulfatase in recessive x-linked ichthyosis results in excessive accumulation of a substrate, cholesterol sulfate, in the pathologic scale, which may underly the pathogenesis of the scaling in this disorder. Measurement of cholesterol sulfate content in scale provides an alternative method to enzymatic assay for the diagnosis of this form of ichthyosis.

Adolescent↗
PubMed1981

Early development of infants of birth weight less than 1,000 grams with reference to mechanical ventilation in newborn period.

Growth, development, and neurologic status were assessed at 1 year of age in 38 infants of birth weight less than 1,000 gm who were born in 1976 through 1978. Twenty had received mechanical ventilation as newborns, and this group had a significantly higher incidence of respiratory distress syndrome, seizures, cardiac arrest, bronchopulmonary dysplasia, and retrolental fibroplasia than those not ventilated. The ventilated infants had a high incidence (70%) of bronchopulmonary dysplasia and of retrolental fibroplasia (20% grade III or IV). Seven of eight infants with severe developmental delay (greater than 2 SD), six of nine with moderate delay (greater than 1 SD), and seven of eight with neurologic disability had received ventilation. There was no difference in growth between the ventilated and nonventilated children. Of the total group, 53% showed no problems.

Bronchopulmonary Dysplasia↗
PubMed1981

Retinoid effects on epidermal structure, differentiation, and permeability.

Retinoids profoundly influence epidermal differentiation, but neither the nature of their antikeratinizing activity nor their mechanism of action is known. In this study, we have correlated morphologic and histochemical findings with an assessment of stratum cohesion and water barrier integrity in adult hairless mice treated with either 13-cis-retinoic acid or the aromatic retinoid, RO 10-9359. Both the synthetic retinoids produced dose-dependent alterations in transepidermal water loss, which were about 5 to 10 times greater in RO 10-9359-treated animals. In contrast to essential fatty acid deficiency, where diminished intercellular lamellar lipids may account for defective barrier function, these lipid-rich structures were intact in retinoid-treated tissues. Instead, retinoids produced both epidermal and stratum corneum loosening, manifested both by the ready production of intraepidermal friction blisters and by ease of removal of cornified cells by tape stripping. Dyshesion correlated with loss of desmosomes and intra- and intercellular accumulation of amorphous material in the upper epidermis. Since these deposits lacked the tinctorial properties of mucin, dyshesion could not be ascribed to the development of mucous metaplasia. Finally, dyshesion could not be attributed to either gain or loss of membrane sugars demonstrated with rhodamine-conjugated lectins, since these changed only late in the course of retinoid treatment. We conclude that the antikeratinizing basis for retinoid activity comprises: (1) dose-dependent alterations in transepidermal water loss and (2) epidermal and stratum corneum loosening, which may, in turn, lead to loss of epidermal cohesion and abnormal barrier function. Neither mucous metaplasia nor stratum corneum thinning appear to play a major role.

Animals↗
PubMed1981

Nature of skin fragility in patients receiving retinoids for systemic effect.

The origin and frequency of skin fragility, a frequent side effect of oral synthetic retinoids, was studied in ten patients receiving isotretinoin (13-cis-retinoic acid) for disorders of keratinization and in hairless mice treated with isotretinoin and the aromatic retinoid, etretinate (RO 10-9359). Clinical skin fragility occurred in eight of ten patients, and experimental friction blisters could be induced by pencil eraser abrasion in nine of nine patients and in the hairless mice. Light and electron microscopy of friction blisters showed fraying or loss of the stratum corneum and outer layers of the viable epidermis, loss of desmosomes and tonofilaments, and intracellular and intercellular deposits of amorphous material that did not stain with stains for mucin. The skin fragility produced by oral synthetic retinoids is epidermal in origin, since (1) retinoids induce profound disruption of epidermal morphologic appearance, (2) an intraepidermal split is produced by experimental friction blisters, and (3) urinary hydroxyproline excretion in patients receiving retinoids, a measure of collagen catabolism, was not increased.

Adolescent↗
PubMed1981

Retinoids, cancer, and the skin.

Vitamin A and its newly developed synthetic analogues recently have been demonstrated to have profound effects on disorders of keratinization, sebaceous gland function, and cancer. In separate sections of this article, we review the history, chemistry, metabolism, mechanism of action, toxicity, and clinical applications of both the naturally occurring and synthetic retinoids.

Antineoplastic Agents↗
PubMed1981

Epithelial focus assay for early detection of carcinogen-altered cells in various organs of rats exposed in situ to N-nitrosoheptamethyleneimine.

The purpose of these studies was to determine a) whether epithelial cells with altered in vitro growth capacity occur not only after topical application of 7-12-dimethylbenz [a]-anthracene but also after systemic administration of a carcinogenic nitrosamine, and b) whether such cells can be isolated from tissues other than tracheal mucosa. AT 3 and 20 weeks following intragastric administration of 150, 300, or 600 mg N-nitrosohepatamethyleneimine (NHMI)/kg, cells were harvested from tracheas, esophagi, and lungs (target tissues for NHMI) of inbred F344 rats and seeded into culture dishes. Normal cells from nonexposed organs produced no proliferative epithelial foci (EF). Of those tracheas sampled 3 weeks following exposure to 150 and 300 mg/kg 10 and 20%, respectively, contained one or more EF that could be subcultured. Of these tracheas harvested 3 weeks post exposure to 600 mg/kg or 20 weeks post exposure to 150-600 mg/kg, 80-100% contained EF that could be subcultured. Twenty weeks after 600 mg NHMI/kg, the incidence of tracheas harboring cell populations with neoplastic potential (agarose-positive EF) was 80%, whereas the tracheal tumor incidence determined at 24 months was only 29%. Epithelial focus-forming units with various abnormal in vitro growth potentials were also detected in esophagi and lungs of NHMI-exposed rats.

Animals↗
PubMed1980

Intracranial hemorrhage in the premature. Its predictive features and outcome.

Sixty-four infants with birth weights of 500 to 1,500 g were studied to determine the incidence and outcome of intracranial hemorrhage. Thirty-seven (58%) had hemorrhage and of these 60% died. Of the survivors, progressive hydrocephalus requiring treatment developed in only two infants. Serial computerized tomographic scans with measurement of ventricular-brain width ratios were found to be useful in objectively evaluating hydrocephalus. Review of perinatal data showed no association of maternal or obstetrical factors with neonatal hemorrhage but the infants who had intracranial bleeding showed a high incidence of low Apgar scores, respiratory distress syndrome, acidosis, hypoxia, apnea, hypotension, seizures, and requirement for respiratory support. Multiple regression analysis of potentially causative factors assigned importance to low gestational age, respiratory distress syndrome, birth asphyxia (low Apgar score), and vaginal delivery.

Cerebral Hemorrhage↗
PubMed1979

Homografts of the middle ear. Privileged tissue or privileged site.

To explain the survival and behavior of homografts, we have tried, by means of discussion and use of biological models, to resolve a problem with three unknowns, ie, the tympanic membrane, the ossicle, and the middle ear, with the notions of privileged tissue and privileged site. The tympanic membrane survives because of the relative stability of its fibers and the absence of mechanical trauma. Later, the membrane is sheathed by fibrous tissue. The ossicle is not only tolerated by the host but is also invaded and ossified.

Ear Ossicles↗
PubMed1979

Glycosylated haemoglobin levels in children with diabetes mellitus.

Total glycosylated haemoglobin (HbA1) levels were measured in 94 diabetic children aged between 3 and 19 years. The results were compared with traditional methods of assessing blood glucose control. HbA1 levels correlated with home urine glucose testing (P less than 0.05), with 24-hour urine glucose excretion (P less than 0.01), and with height velocity (P less than 0.001). Within the first two of these parameters there was a wide scatter of results, suggesting the inaccuracy of these methods for assessing control. The association of raised HbA1 levels with height velocities less than 10th centile shows the effect of poor control on growth. HbA1 may prove to be an objective method for assessing long-term blood glucose levels in diabetes, and thus it may be possible to determine the effect of good control in the prevention of the various diabetic complications.

Adolescent↗
PubMed1979

Herpes zoster in infancy.

Three cases of herpes zoster occurring in infancy are reported. In each case the mother had chickenpox in pregnancy.

Adult↗
PubMed1978

Newborn head size and neurological status. Predictors of growth and development of low birth weight infants.

One hundred eighteen infants with birth weights of 2,000 g or less were evaluated for growth and development at approximately 5 years of age. Review of neonatal data indicated that head circumference less than the tenth percentile at birth and abnormal neurological examination in the newborn period were important predictors of outcome. Both of these factors were associated with poor growth, later microcephaly, and neurological deficit. In addition, neonatal microcephaly was substantially related to poor intellectual attainment. Other associations were seen between microcephaly at birth and intrauterine growth retardation, low Apgar score, and low socioeconomic status, factors that also correlated with poor outcome.

Apgar Score↗
PubMed1978

Tumor induction in the trachea of hamsters with N-nitroso-N-methylurea.

Experiments were conducted to study the tumor response of hamster tracheas to N-nitroso-N-methylurea. Tracheas were exposed repeatedly with the use of a tracheal catheter. Ten to 30 exposures were given over a period of 5 to 20 weeks. The carcinoma incidence (including carcinoma in situ) was 0,42, 67, 88, and 94% for 10, 15, 20, 25, and 30 twice-weekly exposures, respectively. With 10 exposures 2 of 12 hamsters developed benign tracheal tumors. Mean tumor induction time decreased when frequency of exposure was increased from 50 weeks with 10 to 15 exposures to 28 weeks with 25 to 30 exposures. The major histological types of invasive carcinomas observed were epidermoid carcinomas (54%), anaplastic large-cell and small-cell carcinomas (26%), adenocarcinomas (13%), and combined epidermoid-adenocarcinomas (7%). Sacrifice studies revealed that with 10 to 20 twice-weekly exposures only metaplastic lesions with varying degrees of cellular atypia are present at the time of the last exposure. Neoplastic lesions develop during the subsequent exposure-free interval. The data suggest that this tracheal tumor induction system may be well suited for studying problems related to development and progression of neoplastic disease.

Adenocarcinoma↗
PubMed1977

Measurement of the adhesive strength of a gingival cell line to agar.

A new technique is described for measuring the adhesive strength of a gingival cell line to an agar substratum by the modification of the original "blister" test for adhesives. A cell monolayer was developed on a Petri dish with a hole in the center of the growing surface, overlayed with agar, and the system pressurized to debond the cells from the agar surface. Pressure changes were measured by a capacitance pressure transducer the output of which was measured by a strip-chart recorder. The modulus (E) of the agar overlay was determined and used in the calculation of the adhesive-bond strength (gammaalpha). The gammaalpha yield for the gingival cell line (cell-agar debond) was 48.8 ergs per cm2, and for the control (no cells) (agar-polystyrene debond) was 30.0 ergs per cm2.

Agar↗