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F Solomon

Publications and source records attributed to F Solomon.

At least 91 records · Page 5Linked to original sources
PubMed1982

Cytoplasmic microtubule-associated proteins: phosphorylation at novel sites is correlated with their incorporation into assembled microtubules.

We have analyzed the detailed structure and cytoplasmic distribution of cytoplasmic microtubule-associated proteins. The procedure used to identify these proteins, based on preparation of detergent-extracted cytoskeletons, permits separation of fractions containing assembled and unassembled microtubule proteins. We show that two of these proteins, 69 and 80 kd, are closely related to one another and that each protein is present as a set of structurally related polypeptides with differing isoelectric points. In both neuroblastoma and pheochromocytoma cells, several of the isoelectric variants are greatly enriched in the fraction containing assembled microtubule components. Their differential distribution is correlated with phosphorylation at novel sites on the protein. These results support the possibility that covalent modification of a cytoskeletal component may specify its functional state.

Animals↗
PubMed1982

Proteins specifically associated with the microtubules of the mammalian mitotic spindle.

The molecular species that determine the unique structure and functions of the microtubules in the mitotic spindle are not known. We describe the results of two new approaches to the molecular structure of the spindle. Both approaches rely on detergent-extracted preparations of synchronized populations of cells metabolically labeled with 35S-methionine or 32P-phosphate. In these preparations, the original cellular microtubules are preserved. The microtubule components can be released from the detergent-extracted preparations by selective depolymerization with calcium ions. Alternatively, the microtubules can be stabilized by taxol, freed of chromatin by digestion with DNAase and freed of the surrounding cage of intermediate filaments by further extraction at low ionic strength. Gel electrophoresis of each of these preparations of mitotic microtubules demonstrates that they contain microtubule-associated proteins that we have previously shown to be present in interphase microtubules. They also contain a protein of 150,000 daltons, which is the first mitosis-specific microtubule-associated protein identified in mammalian cells.

Alkaloids↗
PubMed1981

Molecular analysis of cytoplasmic microtubules in situ: identification of both widespread and specific proteins.

We have analyzed the molecular components of cytoplasmic microtubules in situ in several types of cultured cells. Our approach makes use of preparations of detergent-extracted cytoskeletons that contain the original cellular microtubules. Identification of microtubule components is based on two criteria: their presence in the cytoskeleton preparations is dependent upon the presence of intact microtubules, and they are released from such preparations by buffers that depolymerize microtubules. Proteins that meet these criteria are described. Some of them are restricted to cells of certain species or tissues of origin. Others appear to be of widespread distribution. Among the latter is a protein homologous to one of the tau polypeptides in brain microtubule protein.

Animals↗
PubMed1981

Cytochalasin separates microtubule disassembly from loss of asymmetric morphology.

When neuroblastoma cells bearing neurites are incubated with colchicine or Nocodazole, the cytoplasmic microtubules are depolymerized and concomitantly the neurites retract. We report here that cytochalasin separates the two effects of these drugs: it quantitatively inhibits neurite retraction but does not inhibit microtubule assembly. The neurites that remain contain intermediate filaments and actin but are devoid of microtubules. Depletion of cellular ATP also blocks neurite retraction induced by colchicine or Nocodazole, but some assembled microtubules persist under these conditions. The results suggest that neurite retraction is an active cell process.

Actins↗
PubMed1981

Specification of cell morphology by endogenous determinants.

We are studying the mechanisms by which cells elaborate their differentiated morphologies. Here we discuss one aspect of this issue: the specification of the detailed shape of individual cells. We describe an experimental system in which endogenous determinants of morphology are expressed. These determinants originally were detected in the morphological relationships between sister neuroblastoma cells. Approaches to analyzing these relationships are presented. The properties and behavior of the endogenous determinants have been partially characterized by further experiments, which are also described. The significance and the prospects for further analysis of our findings are discussed.

Axons↗
PubMed1981

Human lymphocytes-macrophages interaction: a good prognostic sign in malignant lymphoma.

The lymphocyte surface markers as well as the lymphocytes-macrophage interaction were examined in 12 malignant lymphoma patients in the peripheral blood, bone marrow and/or lymph node biopsy or in the pleural effusion (1 patient). In 5 of them a lymphocytes-macrophage interaction ("immunological island") was found: these 5 patients responded well to chemotherapy and their clinical course was satisfactory. The patients in whom a low mouse rosettes percentage was found were in a poorer clinical condition as compared to those with a high mouse rosettes percentage. The lymphocyte-macrophage interactions are probably due to immunological activation of the patient by the malignant antigen and seemed to be a good prognostic sign.

Antigens, Neoplasm↗
PubMed1980

Neuroblastoma cells recapitulate their detailed neurite morphologies after reversible microtubule disassembly.

The detailed neurite morphologies of neuroblastoma cells can be specified by heritable information. This paper reports an investigation into how that information is stored. Cells with neurites are incubated with the microtubule-depolymerizing drug Nocodazole. The neurites retract and the cell bodies round up. The neurites reextend when the drug is removed. 58% of all cells recapitulate their original neurite morphology in detail. The same percentage of recapitulation is observed among a subset of the cells, about half the population, which move across the substratum during retraction and reextension. The results suggest that the storage of morphological determinants survives an interruption in their expression. In addition, reexpression of specific morphology does not require external cues or maintenance of the overall geometry of the cytoskeleton.

Benzimidazoles↗
PubMed1980

Hemochromatosis in a renal transplant recipient.

A 47 year old kidney transplant recipient who died from liver failure caused by hemochromatosis, is described. The diagnosis was established by post mortem examination. The question whether these findings are an extreme form of the common pathological changes seen in the liver in other transplant recipients, or were related to infectious hepatitis or were due to the use of immunosuppressive therapy, remains unanswered.

Female↗
PubMed1979

Sleeping pills.

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Anti-Anxiety Agents↗