PubMed Health⌕ Search

Biomedical subjects

M Jacobson

Publications and source records attributed to M Jacobson.

At least 91 records · Page 5Linked to original sources
PubMed1991

Detection of human papillomavirus DNA in squamous cell carcinoma of the nail bed and finger determined by polymerase chain reaction.

Increasing evidence supports the association of squamous cell carcinoma of the finger and nail bed with human papillomavirus infection. We treated 12 patients with squamous cell carcinoma of the finger and nail bed, none of whom was originally diagnosed as having a malignant lesion. Half of the patients were referred for carbon dioxide laser ablation of what was believed to be a recalcitrant verruca vulgaris. Our objective was to evaluate these lesions for the presence of human papillomavirus by in situ hybridization techniques and the polymerase chain reaction. This is the first report of use of the polymerase chain reaction to detect human papillomavirus in formalin-fixed, paraffin-embedded specimens of periungual squamous cell carcinoma. Seven of the 12 lesions were evaluated for the presence of human papillomavirus by both in situ hybridization and the polymerase chain reaction. Five of the seven periungual lesions were found to contain human papillomavirus type 16 but not type 18 DNA with use of the polymerase chain reaction technique. In situ hybridization failed to identify human papillomavirus in any of these patients' tumors. Our data confirm the association between human papillomavirus and squamous cell carcinoma of the periungual region and suggest that biopsies should be performed on chronic, isolated lesions of the finger in adults before therapy is initiated.

Adult↗
PubMed1990

Dermatofibroma extending into the subcutaneous tissue. Differential diagnosis from dermatofibrosarcoma protuberans.

When dermatofibromas are composed predominantly of fibroblasts and extend into the subcutaneous tissue, it may be difficult to distinguish them from dermatofibrosarcoma protuberans. Because the patterns of extension of dermatofibroma have not been well characterized, we studied 185 cases of the fibrous variant of dermatofibroma with extension into the subcutaneous tissue and 40 cases of dermatofibrosarcoma protuberans. Dermatofibromas had two main patterns of extension into subcutaneous tissue. One pattern, seen in 133 of 185 cases (72%), consisted of irregular extension into the subcutaneous tissue in a vertical or radial fashion, predominantly along the septa, which appeared wedge-shaped. The other pattern, seen in 52 of 185 cases (28%), showed a smooth and well-demarcated deep margin that bulged into the subcutaneous tissue. Dermatofibrosarcoma protuberans also had two main patterns of extension into the subcutaneous tissue. In one pattern, seen in 12 of 40 cases (30%), slender spindle-shaped cells extended along septa and between fat cells in a classic honeycomb or lacelike pattern. The other pattern observed in 24 of 40 cases (60%) exhibited a distinct multilayered pattern in which the bundles of slender spindle-shaped cells showed a predominantly parallel orientation to the skin surface. In four cases (10%), a mixture of both patterns was present. We conclude that the patterns of extension of dermatofibroma into the subcutaneous tissue are different from the patterns of dermatofibrosarcoma protuberans.

Diagnosis, Differential↗
PubMed1990

Analysis of frequency of intermingling between labeled clones in Xenopus embryos.

These experiments were designed to provide data that would test alternative hypotheses of the basis of clonal intermingling during early development of Xenopus. Clones were initiated by injection of different fluorescent cell lineage tracers into two blastomeres in the same 512-cell embryo. In order to find out how frequently clonal intermingling or clonal separation developed between the progeny of two ancestral cells at different distances apart, the pair of injected cells was either adjacent, separated by one uninjected cell, or separated by two uninjected cells, chosen at random in the animal dorsal region of the embryo. The final positions of the labeled clones were analyzed at tailbud stages. The results closely match the probability of interclonal mingling predicted by a compartment model, in which two clones intermingle or remain separate as a function of the probability of a clonal restriction boundary developing between them, rather than as a continuous function of the distance between the two cells at the time of labeling.

Animals↗
PubMed1989

States of determination of single cells transplanted between 512-cell Xenopus embryos.

Single cells from 512-cell Xenopus embryos, totally labeled with intracellular horseradish peroxidase, were transplanted orthotopically (from either dorsal or lateral marginal zone) or heterotopically (between these two marginal zones) to unlabeled host embryos at the 512-cell stage. At tailbud stage 23 the locations, numbers, and histotypes of labeled cells were recorded. The transplanted cell had divided many times, giving rise to labeled progeny that expressed a wide range of cell types and were located in several different organs. Locations and cell types of progeny derived from orthotopic grafts to the dorsal marginal zone were different from those derived from grafts to the lateral marginal zone. Single cells grafted heterotopically to either dorsal or lateral positions expressed fates that were appropriate to their final grafted positions, and not to their original positions. We conclude that individual cells of the marginal zone at the 512-cell stage have multiple presumptive fates and have not been committed to any single fate.

Animals↗
PubMed1989

Desquamative inflammatory vaginitis. A case report.

The differential diagnosis of noninfectious desquamative inflammatory vaginitis includes pemphigus vulgaris, erosive lichen planus and benign mucous membrane pemphigoid. A 32-year-old woman had persistent, noninfectious, erosive vaginitis and linear deposits of IgA in the vaginal epithelial basement membrane zone. The differential diagnosis should be expanded to include mucosal involvement by linear IgA disease, a cutaneous vesiculobullous disorder.

Adult↗
PubMed1987

Clonal restriction boundaries in Xenopus embryos shown with two intracellular lineage tracers.

It has been proposed that clonal restriction boundaries develop in Xenopus embryos between clones initiated at the 512-cell stage, and that these boundaries result in formation of morphological compartments, each populated by progeny of a group of ancestral cells. Although this hypothesis has gained some acceptance, it has also been criticized because the use of only one cell lineage tracer was not a conclusive test of the hypothesis. However, the critical experiment, an assessment of the extent of mingling between two labeled clones in the same embryo, has now been performed. A model of the proposed arrangement of the ancestral cell groups in the 512-cell embryo predicted that the two clones would remain separate in 49% of cases and intermingle in 51% of cases. In fact, there was a bimodal distribution, in which separation of the clones occurred in 46% of embryos and extensive interclonal mingling was observed in 54%. These results are not compatible with hypotheses in which a unimodal distribution of mingling would be predicted but are consistent with the compartment hypothesis.

Animals↗
PubMed1987

Neural cell adhesion molecule expression in Xenopus embryos.

The spatiotemporal pattern of expression of the neural cell adhesion molecule NCAM was mapped immunohistochemically in embryos of the frog Xenopus, from blastula to early swimming stages, using a polyclonal antibody that recognizes Xenopus NCAM. The neural plate stage was the earliest at which NCAM could be detected. The initial sites of NCAM immunoreactivity were neural ectoderm, somitic mesoderm, and chordamesoderm. During formation of the neural tube, NCAM immunoreactivity became restricted to the neuroectoderm and its derivatives. During closure of the neural tube and for 2-4 hr thereafter, NCAM was expressed in a distinctive radial pattern in coronal sections of the neural tube. NCAM was observed in neural crest cells before migration and after formation of cranial and spinal ganglia. During the period of initial neurite outgrowth, NCAM became concentrated in the developing central nerve fiber pathways. NCAM was seen on peripheral nerves from the time of their initial outgrowth and it was strongly expressed at neuromuscular junctions during the period of their formation. These results show that NCAM is expressed after neural induction and functions during morphogenesis of the neural plate and tube, some neural crest derivatives, development of nerve fiber tracts, and formation of neuromuscular connections.

Animals↗
PubMed1987

Changes in neural cell adhesion molecule (NCAM) structure during vertebrate neural development.

Changes in carbohydrate and polypeptide form of the neural cell adhesion molecule (NCAM) have been documented during the development of central nervous system tissue in both chicken and frog. The carbohydrate variations reflect a high and low content of polysialic acid, and for the two vertebrates examined the expression of these forms is similar. At very early stages of neural development NCAM with a low content of polysialic acid is present, during histogenesis of the central nervous system NCAM with a high content of polysialic acid dominates, and there is a gradual return to NCAM with a low content of polysialic acid as the animals approach maturity. In contrast, the order of expression of the major NCAM polypeptide forms is different in the chicken and frog. These findings suggest that changes in sialic acid are a fundamental aspect of the function of NCAM in development, whereas NCAM polypeptide differences may affect events associated with a particular vertebrate. Studies have demonstrated that a decreased sialic acid content enhances the adhesion properties of NCAM. On this basis, we propose that NCAM with a low content of polysialic acid functions both to maintain integrity of neuroepithelium during morphogenesis of the early embryo and to stabilize differentiated structures in the adult, while the decreased adhesive function of NCAM with a high content of polysialic acid provides more plasticity in cell interactions during cell migration, axon outgrowth, and formation of neural circuits.

Animals↗
PubMed1987

Comparative organization of nitrogen fixation-specific genes from Azotobacter vinelandii and Klebsiella pneumoniae: DNA sequence of the nifUSV genes.

In the facultative anaerobe Klebsiella pneumoniae 17 nitrogen fixation-specific genes (nif genes) have been identified. Homologs to 12 of these genes have now been isolated from the aerobic diazotroph Azotobacter vinelandii. Comparative studies have indicated that these diverse microorganisms share striking similarities in the genetic organization of their nif genes and in the primary structure of their individual nif gene products. In this study the complete nucleotide sequence of the nifUSV gene clusters from both K. pneumoniae and A. vinelandii were determined. These genes are identically organized on their respective genomes, and the individual genes and their products exhibit a high degree of interspecies sequence homology.

Aerobiosis↗
PubMed1986

Postnatal changes in arborization patterns of murine retinocollicular axons.

The growth and arborization of murine retinocollicular axons have been studied by means of HRP axon filling during postnatal development. Transformations in arborization patterns have been correlated with changes in synaptic density in the superficial collicular neuropil and with the formation of synapses by HRP-filled axons. At all postnatal ages axons of the optic projection are fasciculated and most follow a rostrocaudally aligned path. On the day of birth the axons course through both stratum griseum superficiale (SGS) and stratum opticum (SO); during the following 4 days the axon trunks disappear from SGS and are subsequently found only in SO. From postnatal day (P) 0 to P3, the majority continue far caudally in the colliculus, giving rise to small ascending collaterals at multiple points along their course. Ultimately, usually by P3, one or two collaterals begin to branch profusely and by P5 the majority of axons give rise to a focal terminal ascending arborization. The general configuration of most arborizations at P3 approximates that of the mature axon. However, the richness of terminal branching increases from P3 through the first 2 postnatal weeks. Synaptic density is relatively low in the first postnatal week, and no synapses involving HRP-filled optic axons were identified in this interval. Subsequently, after elaboration of definitive arbors has begun, synaptogenesis in the surrounding neuropil accelerates. Synaptic density in the upper SGS approximates adult values early in the third postnatal week. By this time synaptic junctions involving the terminal arborizations of optic axons are abundant.

Aging↗