Self-renewal, maturation, and differentiation of the rat myelomonocytic hematopoietic stem cell.

Hematopoiesis is viewed as a differentiating system emanating from a pluripotent hematopoietic stem cell capable of both self-renewal and differentiation. By identifying and characterizing a novel and highly specific in vitro mitogenic response to the N-acetyl glucosamyl/sialic acid specific, stem cell-binding lectin wheat germ agglutinin (WGA), we demonstrate the existance of a rare (0.1%), plastic adherent precursor in rat bone marrow capable of proliferation (two to seven divisions) in response to WGA. Stimulated cells possess a lineage (lin)low/- immunophenotype and immature blastoid morphology (WGA blasts). A subsequent proliferative response to stem cell factor (SCF), the ligand for the proto-oncogene receptor tyrosine kinase c-kit, is characterized by an initial maturation in immunophenotype and subsequent self-renewal of cells (SCF blasts) without differentiation for at least 50 generations. Although granulocyte colony-stimulating factor (G-CSF), interleukin (IL) -6, IL-7, and IL-11 synergize with SCF to increase blast colony formation, cytokines such as granulocyte-macrophage CSF or IL-3 are without significant effect. At all time points in culture, however, cells rapidly differentiate to mature neutrophils with dexamethasone or to mainly monocytes/macrophages in the presence of 1alpha,25-dihydroxyvitamin D3, characterized by cell morphology and cytochemistry. Removal of SCF during blast maturation, self-renewal, or induction of differentiation phases results in apoptotic cell death. Data indicate a pivotal role for SCF/c-kit interaction during antigenic maturation, self-renewal, and apoptotic protection of these lineage-restricted progenitors during non-CSF-mediated induction of differentiation. This approach provides a source of many normal, proliferating myelomonocytic precursor cells, and introduces possible clinical applications of ex vivo expanded myeloid stem cells.

Chromosome typing in lymphangioleiomyomatosis of the lung with and without tuberous sclerosis.

Two cases of lymphangioleiomyomatosis (LLM) of the lungs are compared, one with tuberous sclerosis and the other representing an isolated lung involvement. An increased frequency of complex chromosomal rearrangements was found in peripheral lymphocytes of the patient with tuberous sclerosis, in comparison to the patient with isolated lymphangioleiomyomatosis. Telomeric associations were found in cultured pulmonary smooth muscle cells from the patient with isolated LLM.

Chromosome abnormalities in bovine papillomavirus type 1-transformed Syrian hamster cells before and after tumor formation.

Syrian hamster embryonic fibroblasts transformed by infection with bovine papillomavirus type 1 cause tumors when inoculated into hamsters. Chromosome examinations revealed several abnormal clones in the transformed fibroblasts and a variety of additional markers in three tumors. Only one aberration, trisomy 11, was present in each cell. The extra chromosome #11, thus, is considered to be essential for tumor formation in this model system.

Clonal chromosome aberrations in a case of cutaneous T-cell lymphoma.

Cytogenetic analysis was performed on peripheral blood and on a skin infiltration from a patient with cutaneous T-cell lymphoma. The blood cells revealed no chromosome abnormalities; whereas, besides normal cells, the skin lesion yielded on aberrant clone with the following abnormalities: trisomies 8 and 17, a deletion of the short arm of chromosome 11, and formation of one marker chromosome with possible involvement of chromosome #14.

Chromosomal changes in bovine papillomavirus type 1-induced Syrian hamster tumors.

Bovine papillomavirus type 1 (BPV-1) induced fibrosarcomas in the Syrian hamster were studied cytogenetically by G- and C-banding techniques. All tumor derived cells showed chromosome abnormalities that remained stable during serial tumor transplantations. Cells without chromosome abnormalities found in two cultures were derived from the host animals on account of heterochromatin polymorphisms. In most tumors pseudodiploid cells prevailed, some cells were hypodiploid lacking one or two chromosomes, and one tumor showed two hyperdiploid cell clones with one and three additional chromosomes, respectively. Some of the chromosome abnormalities apparently are nonrandom. Three chromosomes (#1, #4, and #15) were most frequently involved in aberrations.

New observations on the karyotype of the Djungarian hamster, Phodopus sungorus.

In this paper, the C-banding pattern of the karyotype of Phodopus sungorus is presented and polymorphism is taken into consideration.

Studies on sex chromosomes of four hamster species: Cricetus cricetus, Cricetulus griseus, Mesocricetus auratus, and Phodopus sungorus.

In this paper, we present an analysis of the sex chromosomes of four hamster species after application of different staining techniques. The mitotic X chromosomes show a striking similarity in G-banding pattern but rather great differences in their C-banding patterns. A presumably homologous euchromatic segment that exhibits two distinct G-bands appears in the X chromosome of each species. The Y chromosome of Cricetus cricetus is in contrast to those of the other species, because it reveals a relatively well-differentiated G- and C-banding pattern. In meiotic metaphase I, interstitial chiasmata can be found in the sex bivalents of Cricetus cricetus and Cricetulus griseus, whereas the gonosomes of Mesocricetus auratus and Phodopus sungorus sungorus are terminally associated. The regions that are involved in pairing or association are always heterochromatic.

A comparative analysis of the karyotypes of Cricetus cricetus and Cricetulus griseus.

This study presents a comparison of the mitotic chromosomes of the two species of hamsters Cricetus cricetus (European hamster) and Cricetulus griseus (Chinese hamster), which have the same chromosome number of 2n=22.--G-banding procedure reveals striking similarities in both karyotypes and gives the possibility to analyse structural changes so that two examples for Robertsonian rearrangement can be observed.--A remarkable kind of difference between the two karyotypes becomes obvious after C-banding procedure. While Cricetus cricetus shows a large amount of predominantly centromeric heterochromatin, in Cricetulus griseus C-bands are less conspicuous, and a few chromosomes do not exhibit any centromeric heterochromatin at all.