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Biomedical subjects

A T Lane

Publications and source records attributed to A T Lane.

At least 37 records · Page 2Linked to original sources
PubMed1990

Uptake of mercury by the hair of methylmercury-treated newborn mice.

Human hair has unique advantages in monitoring environmental exposures to methylmercury. Using newborn Balb/c mice as a model system, the incorporation of methylmercury into the hair was studied and compared with methylmercury distributions in other tissues. Newborn mice were given intraperitoneal injections of 203Hg-labeled methylmercury at designated times according to hair growth stages of the mouse. Animals were sacrificed 2 days after dosing. Distribution of mercury in pelt and other tissues was measured. The level of mercury in pelt was found to correlate with hair growth. The amount of mercury in pelt peaked when hair growth was most rapid and the total amount of mercury in pelt was significantly higher than that in other tissues, constituting 40% of the whole body burden. However, when the hair ceased growing, the amount of mercury in pelt dramatically dropped to 4% of whole body burden and mercury concentrations in other tissues except brain were elevated. Autoradiographic studies with tritium-labeled methylmercury demonstrated that methylmercury concentrated in hair follicles in the skin. Within hair follicles and hairs, methylmercury accumulated in regions that are rich in high-sulfur proteins. The uptake of inorganic mercury (administered as HgCl2) by pelt was also compared with that of methylmercury. The amount of inorganic mercury found in pelt was less than one-half that of methylmercury in animals with growing hair. Cessation of hair growth did not decrease the inorganic mercury level in pelt to the same extent as in the case of methylmercury.

Animals↗
PubMed1990

Effects of aging and xerosis on the amino acid composition of human skin.

Amino acid compositions of skin samples from young and old subjects and from age-matched donors with dry skin syndrome (xerosis) were examined. The amino acid contents of the free amino acid (FAA) fraction, soluble hydrolysate (SH) fraction, and whole cell hydrolysate (WCH) were determined. The greatest differences were observed between the FAA compositions of the young and old normal subjects. Xerosis did not appear to affect the amino acid compositions of samples from young subjects as much as old subjects. Overall, the effect of aging on the amino acid contents was more pronounced than the effect of xerosis. The amino acid composition of the FAA showed a high degree of similarity to filaggrin, whereas the WCH showed a similarity to keratin.

Aging↗
PubMed1990

Monoclonal antibodies to two different epitopes in a 30-kD CNBr peptide of the K1 and K2 keratins.

Two anti-keratin monoclonal antibodies, Kab-2 and Kab-3, with specificities for different epitopes of type II (basic) human epidermal keratins, were produced. These antibodies had different immunofluorescent staining patterns on human fetal epidermis. Western blots and solid phase RIA showed both antibodies bound to 65-67-kD basic keratins (K1 and K2) extracted from foreskin epidermis. Competitive binding studies with the two Kab antibodies and other anti-keratin monoclonal antibodies showed that Kab-2 and Kab-3 recognized related epitopes, distinct from the epitopes recognized by other anti-keratin antibodies AE-1, 2, and 3. Kab-2 and Kab-3 epitopes were distinguished by differences in their reactivity with peptides generated by Staphylococcus aureus V8 protease digestion of the K1 keratin; the antibodies recognized both common and unique peptides. Western blots of cyanogen bromide digests of the K1 keratin showed that both Kab antibodies reacted with a 30-kD fragment of the molecule presumed to be the N-terminal CNBr peptide. We interpret these data to indicate that in tissues, portions of the N-terminal region of the K1 keratin are differentially available for reaction with these monoclonal antibodies and that morphologic differences in staining with monoclonal antibodies to the same molecule can reflect epitope specificity or epitope availability related to supramolecular organization.

Animals↗
PubMed1990

Intraepidermal formation of Merkel cells in xenografts of human fetal skin.

An experimental transplantation model using human fetal skin was applied to approach the question of the embryologic origin of human Merkel cells. Palmar and plantar skin from five fetuses, between 8 and 11 weeks of estimated gestational age (EGA), was xenografted to subcutaneous beds of nude mice. After 4 or 8 weeks of growth, biopsies were taken from these xenografts and examined for the presence of Merkel cells, using immunocytochemistry with antibodies specific for simple epithelial-type cytokeratins and neuron-specific enolase (NSE) as well as using electron microscopy. Skin from the same fetuses at the time of transplantation was screened in the same way. In all fetuses, no (or very scarce) epidermal Merkel cells were detected at the transplantation time, but in all cases abundant epidermal Merkel cells of apparent human origin were found after 4 or 8 weeks in xenograft culture. Dermal nerve fibers, as recognized by neurofilament antibodies, were scarce or essentially absent in the xenografts. These results indicate that Merkel cells regularly develop in epidermis dissected and xenografted in an early fetal stage, although the dissection implies the interruption of the dermal nerves. The results strongly support the notion of the origin of Merkel cells from epidermal precursor cells. The apparent absence of dermal Merkel cells and dermal nerve fibers in the xenografts suggests that the presence of dermal sensory nerve fibers may be required for the dropping off of epidermal Merkel cells into the upper dermis, which occurs in normal fetal development.

Animals↗
PubMed1990

Semipermeable dressing and transepidermal water loss in premature infants.

Within the first days of life, 10 infants, of 32 weeks' gestational age or less, began 2 weeks of treatment with a semipermeable wound dressing over a small area of skin. The effects of the dressing on transepidermal water loss and cutaneous microflora were evaluated. Transepidermal water loss from the semipermeable dressing-treated skin was significantly less than that from the untreated skin immediately after placement of the dressing (8.1 +/- 1.8 g/m2.h-1 vs 17.7 +/- 3.5 g/m2.h-1, P less than .0001). The normal accelerated skin maturation process that occurs in these infants continued beneath the semipermeable dressing. The number of gram-negative bacilli or other bacteria did not increase beneath the semipermeable dressing beyond that seen on the untreated site. Malassezia furfur was found only on the control site, never beneath the semipermeable dressing. According to results of this preliminary study, a semipermeable dressing can be safely used in premature infants and the use of a semipermeable dressing may decrease the excessive transepidermal water loss associated with prematurity.

Bacteria↗
PubMed1989

Retention of differentiated characteristics in human fetal keratinocytes in vitro.

Many of the morphologic and biochemical changes that occur during human fetal skin development have been described, yet there has been little experimental analysis of the processes that regulate the development of human fetal skin. This is due in part to difficulties in culturing human fetal epidermal keratinocytes. We have successfully cultured fetal keratinocytes in two different in vitro systems; in a serum-free keratinocyte growth medium (KGM) on tissue culture plastic and cocultured with dermal fibroblasts as spheroidal aggregates. To characterize these fetal keratinocytes in vitro we have assessed their ability to express several markers of epidermal differentiation. Human fetal keratinocytes grown on plastic in KGM stratify and express some of the components of the differentiated epidermis, such as involucrin and the high molecular weight keratins. However, these keratinocytes co-express keratins and vimentin and do not form a structured basement membrane. More characteristics of fetal skin are preserved in mixed aggregates of epidermal keratinocytes and dermal fibroblasts, including epidermal stratification, synthesis of basement membrane components, tissue-specific expression of intermediate filaments, involucrin, and expression of high molecular weight keratins. The maintenance of human fetal epidermal keratinocytes in these two in vitro systems and their ability to express many differentiated characteristics suggests that these cultures will be valuable for studies of the molecular mechanisms that regulate the regionally specific differentiation of the human fetal epidermis.

Antibodies, Monoclonal↗
PubMed1989

Development of human fetal skin transplanted to the nude mouse.

Thirty-five human fetal skin (HFS) grafts were transplanted to nude mice for 7 to 70 d and evaluated histologically with 64 biopsies. The estimated gestational ages (EGA) of the grafts at the time of the transplantation ranged from 8 to 19 weeks. The maturation of the engrafted fetal skin was evaluated by assessing epidermal, dermal, and appendage development. Within the nude mouse, the HFS demonstrated progression in stratification and maturation of the epidermis. The dermis increased in depth, adding fibrovascular stroma and adipose tissue. The appendages demonstrated invagination, differentiation, and progression of organogenesis. Subcutaneously placed grafts showed the same rate of HFS development as HFS in utero. The grafts transplanted to the surface of the nude mice and exposed to air demonstrated an acceleration of development. We conclude that HFS transplanted to the nude mouse is an effective in vivo model for maintaining and altering HFS maturation.

Animals↗
PubMed1988

Perianal cellulitis. Cutaneous group A streptococcal disease.

Five case reports of perianal cellulitis caused by group A beta-hemolytic streptococci are presented. These reports illustrate delays in diagnosis and therapy of this condition that may present as chronic diaper dermatitis, perirectal fissures, painful defecation, fecal hoarding behavior, or proctocolitis. One patient had associated guttate psoriasis. In children especially, guttate psoriasis should alert physicians to culture perirectal as well as pharyngeal sites for group A streptococci.

Adult↗
PubMed1988

Cutaneous reaction to contrast material.

Two children are described who developed an apparent cutaneous contact reaction to contrast material in urine. Both children had undergone uneventful voiding cystourethrography with diatrizoate meglumine injection USP 18% followed by intravenous urography with diatrizoate meglumine injection USP 60%. Approximately 1 hour after urography cutaneous bullae and surrounding erythema of the buttocks (one case) or foreskin (one case) were noted. This reaction resembled a superficial chemical burn.

Buttocks↗
PubMed1988

Lichen planus sera react non-specifically with second trimester fetal skin.

Lichen planus (LP) is a relatively common papulosquamous disease of unknown etiology for which an "autoimmune" pathogenesis has been postulated. A LP-specific antigen has been found in the stratum granulosum of lesional skin, and circulating antibodies to this antigen have been found in sera of about 70% of LP patients. Specific binding of antibodies in LP sera to second trimester fetal skin has been reported (Med. Microbiol. Immunol., 1984; 172, 249). In the present study, we attempted to reproduce this work. Indirect immunofluorescence was performed using frozen sections of human foreskin or second trimester fetal skin (n = 7) incubated first with serum from 17 LP patients or 7 normal controls. The substrate was then washed and incubated with fluorescein-labelled rabbit antibodies to human immunoglobulins. Results showed that sera from both LP patients and normal controls reacted with epidermal cells of fetal skin above the basal cell layer. The foreskin substrate did not react with either sera. In conclusion, we could not confirm the differences in reactivity of LP vs. normal sera against second trimester fetal skin as previously reported. This discrepancy between the two studies may be attributed to methods of collection of fetal tissue, nonspecific binding of antibodies in serum of some LP patients, or increased levels of immunoglobulins against epidermal keratins in sera of LP patients or normal controls.

Autoantigens↗
PubMed1987

Development and care of the premature infant's skin.

Recent advances in neonatal care have greatly decreased mortality and morbidity in premature infants. Those who survive, however, often have significant cutaneous abnormalities. This has led to enhanced understanding and care of the premature infant's skin. Future dermatologic research may develop methods both to control epithelial maturation and to deliver therapy through the skin.

Humans↗
PubMed1986

The involvement of 6p in melanoma.

Karyotype analysis of first passage cells from a melanoma, occurring in a patient with a giant congenital nevus, revealed monosomy of chromosomes #6 and #11, and trisomy of chromosomes #8 and #22. Five marker chromosomes were present, including two ring chromosomes. The origin of three of the marker chromosomes was determined, and all were found to contain the region 6p21.1-6p23. The ring chromosomes were also thought to contain this region, to which the major histocompatibility locus has been mapped. The significance of these findings is discussed in the light of recent reports of chromosome studies of melanoma cells.

Child, Preschool↗
PubMed1986

Diet and atopic dermatitis.

Prevention or modification of the onset of atopic dermatitis has been difficult to document through prolonged breast feeding or delayed introduction of solid foods. Dietary management of established atopic dermatitis is not routinely indicated for the majority of patients. Dietary management of atopic dermatitis should not be continued indefinitely. Gradual reintroduction of the offending food(s) is often appropriate. The foods most commonly avoided in the management of atopic dermatitis are cow's milk, wheat, eggs, and nuts. Severe or prolonged dietary restrictions should not be instituted without full consideration of their impact on the patient's general health.

Age Factors↗
PubMed1986

Epidermal antigen preservation with freezing.

Antigen preservation in human foreskin was evaluated after prolonged storage. Foreskin sections previously separated and stored were examined after 24 h, 6 days, 102 days, 364 days, and 493 days, using indirect immunofluorescence techniques. Each foreskin was evaluated with high-titer human antisera against bullous pemphigoid and pemphigus antigens, rabbit antiserum against laminin, and IgG murine monoclonal antibodies against OKT6, OKIa, AF-1, and Kab-3. Each section was studied and scored by three independent observers. Except for decreased fluorescent staining of pemphigus antigens, no decrease of the immunofluorescence titers was seen over the period of observation.

Antibodies↗