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K Hummeler

Publications and source records attributed to K Hummeler.

At least 19 recordsLinked to original sources
PubMed1986

Utilization of [15N]glutamate by cultured astrocytes.

The metabolism of 0.25 mM-[15N]glutamic acid in cultured astrocytes was studied with gas chromatography-mass spectrometry. Almost all 15N was found as [2-15N]glutamine, [2-15N]glutamine, [5-15N]glutamine and [15N]alanine after 210 min of incubation. Some incorporation of 15N into aspartate and the 6-amino position of the adenine nucleotides also was observed, the latter reflecting activity of the purine nucleotide cycle. After the addition of [15N]glutamate the ammonia concentration in the medium declined, but the intracellular ATP concentration was unchanged despite concomitant ATP consumption in the glutamine synthetase reaction. Some potential sources of glutamate nitrogen were identified by incubating the astrocytes for 24 h with [5-15N]glutamine, [2-15N]glutamine or [15N]alanine. Significant labelling of glutamate was noted with addition of glutamine labelled on either the amino or the amide moiety, reflecting both glutaminase activity and reductive amination of 2-oxoglutarate in the glutamate dehydrogenase reaction. Alanine nitrogen also is an important source of glutamate nitrogen in this system.

Adenosine Triphosphate↗
PubMed1983

[15N] leucine as a source of [15N] glutamate in organotypic cerebellar explants.

Approximately 26.0% of the [15N] glutamate and [alpha 15N] glutamine formed in organotypic cerebellar explants was derived from [15N] leucine. Approximately 14.0% of the 15NH3 and [amide 15N] glutamine synthesized came from leucine nitrogen. Another 4.0% of the alpha nitrogen of both glutamate and glutamine was derived from [15N] valine. These results suggest that branched-chain amino acids, particularly leucine, may be important for the synthesis of glutamic acid by the brain.

Amino Acids↗
PubMed1982

Preservation of brush border transport systems for proline and alpha-methyl-D glucoside from rat, dog, and human kidney.

The effects of freezing renal tissue from rat, dog, and man on the time course of uptake of proline and alpha-methyl-D-glucoside by subsequently isolated brush border membrane vesicles was examined and compared with uptake patterns by membranes isolated from tissue that had never been frozen. The overshoot phenomenon was used as the critical criterion for viability of the transport systems. Membranes isolated from frozen rat and dog kidney possessed intact transport systems for proline and alpha-methyl-D-glucoside capable of producing normal or even enhanced overshoot patterns. Freezing human kidney prior to membrane isolation resulted in severe impairment of the vesicle transport capabilities. Freezing a crude membrane suspension, however, allowed the subsequent purification of only partially intact systems.

Animals↗
PubMed1981

Neuronal properties of neuroectodermal tumors in vitro.

Cell lines of medulloblastoma, retinoblastoma, and neuroblastoma, three childhood tumors derived from neuroectoderm, have been compared with respect to their neuronal properties. Neuroblastoma, a neural crest derivative, has been shown to express specific neuronal enzymes and the action potential sodium ionophore. Cell lines of medulloblastoma and retinoblastoma also express neuronal specific enzymes and therefore are considered to be of neuroblastic origin.

Acetylcholinesterase↗
PubMed1977

Isolation and characterization of a neuroblastoma cell line from peripheral blood in a patient with disseminated disease.

Circulation in the blood stream of neuroblastoma cells was confirmed by establishment of a cell line from the peripheral blood of a child with disseminated disease. The morphologic, enzymatic, and chromosomal pattern of this cell line was similar to a cell line established from the primary tumor on a previous occasion. The peripheral blood smear did not demonstrate tumor cells but increased numbers of atypical monocytes; lymphoblasts were evident, which may have been unrecognized neuroblasts.

Acetylcholinesterase↗
PubMed1976

Glycopeptides from the surgace of human neuroblastoma cells.

Glycopeptides suggesting a complex oligosaccharide composition are present on the surface of cells from human neuroblastoma tumors and several cell lines derived from the tumors. The glycopeptides, labeled with radioactive L-fucose, were removed from the cell surface with trypsin, digested with Pronase, and examined by chromatography on Sephadex G-50. Human skin fibroblasts, brain cells, and a fibroblast line derived from neuroblastoma tumor tissue show less complex glycopeptides. Although some differences exist between the cell lines and the primary tumor cells, the similarities between these human tumors and animal tumors examined previously are striking.

Antigens, Neoplasm↗
PubMed1976

Establishment and characterization of human neuroblastoma cell lines.

Three new tissue culture cell lines, CHP-100, CHP-126, and CHP-134, have been established from explant cultures of human neuroblastoma. The cell lines have been characterized with respect to morphology, chromosomes constitution, growth, neural enzyme content, and their ability to grow in nude mice. The cells grow as dense masses comprised of fibroblast-or neuroblast-like cells with small processes. The cell lines differ in their neural enzyme acitivity. The chromosomal content of the 3 cell lines is near diploid, and all are capable of forming tumors in nude mice. The morphological findings indicate that the cells in culture resemble those found in the tumor, and the enzyme activities are consistent with those of nervous tissue. This the morphological, biochemical, and tumorigenic properties confirm that the 3 cell lines are neoplastic cells of neural origin.

Acetylcholinesterase↗
PubMed1973

Comparison of the lipids of intracellular and extracellular rabies viruses.

The lipid composition of both intracellular and extracellular forms of the ERA strain of rabies virus grown in BHK/21 cells was determined. The lipids from purified preparations of both intracellular and extracellular virus yielded 57 and 58% neutral lipid, respectively. The phospholipids of the intracellular and extracellular virus constituted 43 and 42%, respectively. Triglyceride and cholesterol appear to be the major neutral lipids, whereas sphingomyelin, phosphatidylethanolamine, and phosphatidylcholine comprise the major bulk of phospholipid in both virus types. The molar ratio of cholesterol to phospholipid was 0.87 (intracellular) and 0.92 (extracellular). On the basis of the data presented, it is reasonable to assume that the lipids of both intracellular and extracellular rabies virus are similar.

Animals↗
PubMed1972

Studies on antibody-producing cells. IV. Ultrastructue of plaque-forming cells of rabbit lymph.

Efferent lymph of the popliteal lymph nodes of rabbits was collected 4 days after a single footpad injection of SRBC. Thin-layer agar plating was done to isolate plaque-forming cells of the lymph for electron microscope examination, and the numbers of plaque-forming cells (PFC) in cells from the lymph and lymph nodes were determined. Of 71 PFC of lymph isolated and examined, 93% were lymphocytes, most of them with signs of substantial levels of physiologic activity. The cytoplasm showed an abundance of free ribosomes and many finger-like projections. The endoplasmic reticulum (ER) was barely detectable in most of the active lymphocytic PFC, and in some, a few short narrow channels of ER could be seen. Approximately one-fifth of the lymphocytic PFC presented an appearance of senescence, with signs of degeneration: rounded cells, with amorphous nuclear chromatin, and very few microvilli. The remaining 7% of the PFC of the lymph showed an unusual combination of features: small round cells with a narrow ring of cytoplasm which, however, contained well-organized channels of ER. Such cells had been found only among PFC of peripheral blood of the rabbit. The number of PFC per million cells was higher in the lymph than in the suspensions of lymph node cells. In both the contralateral lymph node and its efferent lymph, the number of PFC was less than 1% that of the injected side.

Animals↗
PubMed1971

Studies on antibody-producing cells. 3. Identification of young plaque-forming cells by thymidine- 3 H labeling.

Mice injected with sheep RBC and then, 4 days later with thymidine-(3)H, were sacrificed on the day of thymidine-(3)H injection or 1 or 2 days later. Hemolytic antibody plaque preparations were made of cells from the draining lymph nodes by a thin-plating procedure permitting collection of isolated PFC for electron microscopic examination and radioautography. Of cells obtained on the day of thymidine-(3)H injections, 65% of the labeled PFC were in the lymphocytic category, in comparison with 13% found previously in the entire population of such cells. The remaining 35% were plasmablasts in early stages of differentiation. Cells obtained 1 day after the thymidine-(3)H injections showed a shift to a majority of labeled cells in the plasmacytic category. Also, the plasmablasts were substantially more differentiated than those of the previous day, and some mature plasma cells were now seen. The labeled PFC obtained on day 2 gave no indication of further differentiation. Cells of rabbit lymph nodes labeled in vitro with thymidine-(3)H showed a range of labeled PFC. The majority were in the plasmacytic category, including some mature plasma cells. The data from the experiments with in vivo labeling suggest a direct differentiation from antibody-synthesizing lymphocytes to plasma cells. Further, the in vivo experiments indicated that differentiation from nascent lymphocyte to plasma cell could be essentially completed within 1 day.

Animals↗