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L S Honig

Publications and source records attributed to L S Honig.

At least 55 records · Page 3Linked to original sources
PubMed1988

Neural differentiation, NCAM-mediated adhesion, and gap junctional communication in neuroectoderm. A study in vitro.

We studied the development of NCAM and gap junctional communication, and their mutual relationship in chick neuroectoderm in vitro. Expression of NCAM, as detected by monoclonal and polyclonal antibodies, and development of junctional communication, as detected by extensive cell-to-cell transfer of 400-500-D fluorescent tracers, occurred in cultures from stage-2 embryos onward. Both expressions presumably required primary induction. The differentiating cells formed discrete fields of expression on the second to third day in culture, with the NCAM fields coinciding with the junctional communication fields delineated by the tracers. Other neural differentiations developed in the following order: tetanus toxin receptors, neurofilament protein, and neurite outgrowth. Chronic treatment with antibody Fab fragments against NCAM interfered with the development of communication, suggesting that NCAM-mediated adhesion promotes formation of cell-to-cell channels. Temperature-sensitive mutant Rous sarcoma virus blocked (reversibly) communication and the subsequent development of neurofilament protein and neurites, but expression of NCAM continued.

Animals↗
PubMed1988

delta 5-3 beta-hydroxysteroid dehydrogenase activity in sebaceous glands of scalp in male-pattern baldness.

Sebaceous glands were isolated by manual dissection using a stereomicroscope from skin specimens of bald scalp of men with male-pattern baldness undergoing hair transplant or scalp reduction surgery and also from specimens taken from hairy and bald areas of scalp at autopsy of adult male victims of accidental death within 3 h post mortem. Homogenates of the isolated glands exhibited activities of delta 5-3 beta-hydroxysteroid dehydrogenase (3 beta HSD), 17 beta-hydroxysteroid dehydrogenase, and testosterone 5 alpha-reductase by the conversion of [3H]dehydroepiandrosterone (DHA) to 3H-delta 4-androstenedione (AD), [3H]testosterone, and [3H]dihydrotestosterone. Homogenates of glands from bald (B) scalp had greater 3 beta HSD activity than homogenates of glands from hairy (H) scalp. After differential centrifugation, 3 beta HSD activity was found mainly in the microsomal and 105,000 X g supernatant fractions. Specific activity of the enzyme based on protein mass was highest in the microsomal fraction; however, the total 3 beta HSD activity in the 105,000 X g supernatent of B glands was significantly (p less than .01) greater than that of H glands. 3 beta HSD activity in sebaceous glands isolated from autopsy specimens did not differ from that of glands isolated from surgical specimens in apparent Km (0.13-0.14 microM), pH optima (8.0), or coenzyme requirement for NAD. Since substantial 3 beta HSD activity was present in the cytosol, and cytosol of B glands showed increased 3 beta HSD activity, the increased conversion of DHA to AD may be a critical step for androgenic action and may be responsible for excessive androgenicity in male-pattern baldness.

3-Hydroxysteroid Dehydrogenases↗
PubMed1988

Oestrogen and progesterone receptors in lentigo maligna.

We have measured oestrogen and progesterone binding in specimens of histopathologically confirmed lentigo maligna (LM) lesions excised from five elderly white men, using a dextran-coated charcoal method. Oestrogen binding was observed in four of the five specimens, and progesterone binding in all five. Marginal normal skin showed only non-specific binding for oestrogen and progesterone. The presence of steroid hormone receptors in LM suggests the possibility that hormone responsiveness may be relevant in the transformation of a lentigo maligna into malignant melanoma.

Aged↗
PubMed1988

Multiple sclerosis: correlation of magnetic resonance imaging with cerebrospinal fluid findings.

MRI examination of 41 patients with clinical definite multiple sclerosis showed white matter lesions of high proton T2 signal consistent with demyelination in 76% and CSF abnormalities present in 76%. Of patients with CSF abnormalities, 26% had normal MRI scans; conversely 26% of patients with MRI abnormalities had negative CSF studies. Thus a significant number of multiple sclerosis patients had negative results on either MRI or CSF examination, while only 5% had normal results on both tests.

Adult↗
PubMed1985

Experimental fusion of the naturally cleft, embryonic chick palate.

The palatal shelf medial edges of day 8 (Hamburger-Hamilton [HH] stages 32-33) and day 9 (HH stage 35) embryonic chicks were surgically disrupted in ovo and in vitro in an attempt to discover if the naturally cleft chick palate could be induced to fuse experimentally. At HH stages 32-33 (day 8) the chick palatal shelves were apart at the time of in ovo operation. Consequently, their medial edges did not fuse but rather underwent embryonic would healing with re-epithelialisation (which often formed needle track invaginations), but no signs of inflammation or scar or scab tissue formation. Conversely, at HH stage 35 (day 9) the palatal shelves are in contact at the time of in ovo operation and so underwent fusion. The extent of palatal fusion depended upon the extent of initial medial edge epithelial disruption. Fusion did not spread from the operated sites to adjacent unoperated areas, where the palatal shelves were in contact with each other. Occasional epithelial seams were formed, but these persisted and did not undergo cell death. There was no evidence of inflammation or scar or scab tissue at the operated sites. Abnormal bony and muscular blastemae appeared in the continuity zones of these experimentally intact chick palates. Mortality was high for embryos operated upon in ovo. Palatal shelves explanted from HH stages 32, 33, and 35 chick embryos and cultured in vitro with their medial edges in contact did not fuse unless their medial edge epithelia were surgically disrupted, in which cases fusion always occurred regardless of the stage of the explanted shelves.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Maps of strength of positional signalling activity in the developing chick wing bud.

Tissue from the posterior margin of the developing limb bud, when grafted to the anterior margin, evokes the formation of a mirror-image limb duplication from the host tissue. We present maps of the spatial and temporal distribution of this signalling activity in the chick wing bud based on a bioassay that provides a quantitative measure of the completeness of the additional structures (the strength of activity index). Activity is first detected prior to the initial appearance of the limb primordium as early as Hamburger & Hamilton stage 14. It reaches a maximum during early outgrowth of the bud at stages 19 to 25. It then declines as the limb starts to differentiate into its final morphological pattern. The design of the experiment provides serendipitous data showing that two operators can consistently perform grafts with high reproducibility between them while variability between embryos is somewhat higher. The maps of activity are of particular practical value in precisely defining for the experimental embryologist and molecular biologist those positions and stages at which peak signalling activity resides.

Animals↗
PubMed1984

Differentiation of cultured palatal shelves from alligator, chick, and mouse embryos.

Palatal shelves from embryonic alligators, chicks, and mice were explanted at various stages of development and organ cultured in either chemically defined, serumless media or the same media supplemented with 10% fetal calf serum. Shelves from each vertebrate were either cultured singly or in contact, and heterologous combinations of palatal shelves from different animals were made: chick/mouse, chick/alligator, and mouse/alligator. Epithelial differentiation (particularly that of the medial shelf edge) was assayed by vital staining, histology, and scanning electron microscopy. In vitro medial edge epithelial differentiation, and consequently the mechanisms of palatal closure, were identical to those normally seen in vivo for each species, i.e., cobble-stoned migrating epithelia in the alligator, cell death and fusion in the mouse, and keratinisation and cleft palate in the chick. Differentiation was optimal in the chemically defined, serumless media and was independent of shelf contact in all three species. No heterologous combinations of palatal shelves closed with each other: Evidently, the modes of palatal closure in mice and alligators are sufficiently different to prevent them forming a chimeric palate, whilst neither is capable of inducing closure in a cocultured chick palatal shelf. These unified defined culture conditions make possible a large number of epithelial-mesenchymal recombination studies as well as specific inhibitor, teratogenic, and hormonal investigations.

Alligators and Crocodiles↗
PubMed1984

Influence of the major histocompatibility complex (H-2) on glucocorticoid-stimulated pulmonary surfactant synthesis in two congenic mouse strains.

Mice with different histocompatibility alleles in otherwise identical backgrounds (congenic inbred strains of H-2a and H-2b haplotypes), were used to study the possible influence of the major histocompatibility complex (MHC) upon glucocorticoid-stimulated pulmonary surfactant synthesis during embryonic and fetal stages of mouse lung development. Pregnant C57BL/10SnJ (H-2b) and congenic B10.A/SnSgJ (H-2a) mice were administered single or consecutive intraperitoneal injections of betamethasone during the period of 14 through 17 days gestation. Assays for incorporation of [3H]choline into total lipid and saturated phosphatidylcholine (an index for pulmonary surfactant synthesis) were conducted, 24 hr following the last treatment, on Days 17 or 18 of gestation. Control mice received injections of phosphate-buffered saline. The H-2 genotype appears to influence the relative responsiveness of glucocorticoid-stimulated surfactant synthesis during fetal lung development. The B10.A strain (H-2a haplotype) was more responsive to glucocorticoid-stimulated pulmonary surfactant synthesis than the H-2b haplotype. Whereas both strains were responsive to glucocorticoid-stimulated [3H]choline incorporation into lung surfactant, the differences in responsiveness at specific fetal stages suggest that genes within or closely linked to the H-2 complex might have a role in pulmonary surfactant biosynthesis during mouse lung development. The results also suggest the possibility that relative susceptibility to congenital pulmonary disorders may be influenced by the H-2 complex.

Alleles↗
PubMed1983

Does anterior (non-polarizing region) tissue signal in the developing chick limb?

The morphogenetic properties of embryonic chick limb bud tissue from anterior positions and from the posterior (polarizing) region are compared. Quail grafts, which possess the distinctive nucleolar cell marker, and gamma-irradiation are used. Supernumerary limb structures induced by anterior tissue wedge grafts are found to be nearly exclusively graft, donor tissue derived. This contrasts with the duplicate limb structures formed in response to posterior (polarizing region) tissue grafts in which host cells predominate. Distinction between anterior and posterior tissue properties was also demonstrated using doses of radiation (approximately 12 Gy = 1200 rad) which inhibit cell proliferation, but have negligible effects on avian polarizing activity. These doses, however, are found to completely abolish morphogenetic activity by chick or quail anterior tissue grafts. The results of anterior (non-polarizing) region tissue grafts are best interpreted as graft self-differentiation under the influence of a posterior signalling region, whose properties in the limb bud are demonstrably unique.

Animals↗
PubMed1982

Enamel gene products during murine amelogenesis in vivo and in vitro.

Epithelial-mesenchymal interactions regulate determination and differentiation of amelogenesis. Our attention has focused on identification of ameloblast gene products, the regulation of enamel mRNA synthesis, and subsequent translation into enamel proteins in vivo and in vitro. Enamel proteins are the most abundant gene products synthesized in fully-differentiated ameloblasts. Our experimental strategy has been to isolate major proteins, produce antibodies, localize enamel protein antigens during tooth development in vivo as well as in vitro (using serumless, chemically-defined medium), develop an immunoprecipitation assay, isolate poly(A)-products in a cell-free translation system, and then initiate molecular cloning of the corresponding murine enamel gene(s). The major murine enamel mRNA appears to code for a predominant polypeptide of approximately 20,000 MW. Inner-enamel epithelial cells differentiate into ameloblasts, and synthesize and secrete enamel proteins within six d when cap-stage molar tooth organs are cultured in serumless, chemically-defined medium. The regulation of epithelial differentiation under these experimental conditions indicates that epithelial-mesenchymal interactions determine and maintian ameloblast differentiation in vitro.

Ameloblasts↗
PubMed1982

Epithelial-derived basal lamina regulation of mesenchymal cell differentiation.

The mechanisms by which epithelial-mesenchymal interactions result in differentiation are not known. A number of recombinations between vertebrate tissues associated with epidermal organs (e.g. skin, feather, mammary gland, salivary gland, tooth organ) indicate that regional mesenchymal specificity is instructive for determination and differentiation of epithelial phenotypes. In epidermal organs within which mesenchyme becomes determined and differentiates into a unique phenotype, such as during tooth organogenesis and odontoblast differentiation. Does the epithelial-derived basal lamina regulate mesenchymal differentiation into odontoblasts and the expression of dentine extracellular matrix? Experiments were designed to test the hypothesis that murine or avian epithelial-derived basal lamina possess information which is instructive for determined dental mesenchyme to differentiate into odontoblasts. The strategy was to examine homologous and heterologous tissue recombinants between Theiler stage 25 C57BL/6 molar tooth organs and Hamburger-Hamilton equivalent stage 22-26 Japanese Pharoah quail mandibular processes. Trypsin-dissociated molar epithelium and mesenchyme, reconstituted, secreted a basal lamina within 8 hours and mesenchyme differentiated into odontoblasts and formed dentine matrix within 3 days. Isolated trypsin-dissociated mesenchyme did not differentiate in vitro, whereas heterologous recombinants between odontogenic mesenchyma and quail epithelia resulted in odontoblasts and dentine production. Mouse tooth or quail mandibular epithelia served to regulate odontogenic mesenchyme differentiation. EDTA-dissociated mouse molar mesenchyme, in the absence of epithelium but with adherent basal lamina, routinely differentiated into odontoblasts. Control tooth organs routinely formed both dentine and enamel extracellular matrices within 7-10 days in our serumless, chemically-defined organ culture system. Regulation of determined mesenchymal cells to differentiate into functional and highly specialized odontoblasts appears to be mediated by epithelial-derived basal lamina and is not species or organ-specific.

Animals↗
PubMed1982

Effects of ultraviolet light on the activity of an avian limb positional signalling region.

Cells from a region on the posterior margin of the developing avian limb bud (the polarizing region) can signal positional information to responding anterior cells. Polarizing activity may be assayed by disaggregation of the tissue into single cells, followed by reaggregation and grafting of cell pellet. This method enables treatments of the cells while in single-cell suspension. The effects of ultraviolet radiation (254 nm) were studied to determine the role of nucleic acids in polarizing activity. Ultraviolet radiation eliminated quail polarizing activity over the same range of doses as it reduced cell spreading (20-60 J/m2). In contrast to the published effects of gamma-radiation in which polarizing activity is affected only at doses much higher than those that are cell lethal, ultraviolet apparently abolishes cell survival and polarizing activity at comparable doses. Compared to other biological systems, polarizing activity is quite sensitive to ultraviolet light: the D37 is 18 J/m2; the extrapolation number, n, is 3 . 6. From comparison of the effects of ultraviolet radiation to those published for ionizing X- or gamma-radiation, one may conclude that ultraviolet and gamma-radiation abolish limb polarizing activity at equivalent nucleic acid dosages, not at equivalent cell lethal doses.

Animals↗
PubMed1981

Positional signal transmission in the developing chick limb.

It has been suggested that the pattern along the antero-posterior axis of the embryonic developing chick limb arises from a gradient of diffusible morphogen produced by a special region of cells on the posterior margin of the limb bud, called the polarizing region. Grafts of posterior polarizing-region tissue to an anterior site in an embryonic chick wing bud result in mirror-image duplication of the limb bud; typically three extra wing digits are produced (Fig. 1f, g). Direct evidence for a long-range signal has, however, been lacking, and recently it has been suggested that chick wing development might better be understood as resulting only from local, neighbour-neighbour-like interactions of the sort postulated to occur during regeneration of insect and amphibian limbs and insect imaginal disks. As we report here, operations were performed in which chick wing buds were made host to grafts of leg bud responding tissue adjacent (posteriorly) to a grafted polarizing region (Fig. 2). The results showed that the pattern signal from the polarizing region can be transmitted through the leg tissue over distances of tens of cell diameters.

Animals↗