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H Honda

Publications and source records attributed to H Honda.

At least 469 records · Page 26Linked to original sources
PubMed1984

A computer simulation of cell stacking for even thickness in mammalian epidermis.

The method of even stacking of epidermal cells in mammalian skin was studied by computer simulation. The epidermis consists of neat vertical columns of stacked, flattened, tetrakaidecahedral cells. Cells which have been proliferated in a basal layer migrate upwards, occupy the bottom regions of vertical columns, and become members constituting columns. Computer simulations demonstrated that the column height becomes considerably varied if the cells are randomly supplied from the basal layer. In contrast, if the cells are assumed to have an ability to find the uppermost region among the column's bases consisting of one base where the cell has reached and its neighbouring bases, the cells stack into columns whose heights are remarkably uniform even if the cells are randomly supplied. The results indicated that an epidermal structure consisting of the flattened polyhedral cells could itself function as a control mechanism of the epidermal thickness.

Animals↗
PubMed1984

Two-state model for bacterial chemoreceptor proteins. The role of multiple methylation.

To help understand the bacterial chemotactic response of excitation and adaptation, we propose a simple two-state model for receptor proteins (methyl-accepting chemotaxis proteins), in the light of evidence that they undergo multiple methylation in a preferred order. The model includes the following assumptions. (1) The receptor protein is in rapid equilibrium between two conformations, S and T, and the equilibrium shifts towards the T form as the number of methyl groups increases. (2) Attractants bind to the S form of the receptor, repellents bind to the T form, and both classes of ligand shift the S/T equilibrium according to the mass-action law. (3) The S form of the receptor accepts methyl groups one by one in a definite order, while the T form releases the methyl groups in the reverse order. Methylation and demethylation are slow reactions, and changes in the total number of methyl groups lag behind shifts in the S/T equilibrium. (4) The pattern of bacterial swimming at any moment is determined by the partition of the receptor between the two conformations, with tumbling frequency being a monotonically increasing function of the total T fraction of the receptor. This model shows that, if the receptor satisfies two sets of relationships imposed on its equilibrium and kinetic constants, it can maintain the steady-state total T fraction essentially constant over a broad range of ligand concentration, enabling cells to adapt to large changes in chemical environment. A stepwise change in ligand concentration leads to a rapid change in the total T fraction (excitation), followed by a slow relaxation process (adaptation). Computer simulations have been made of the whole response process, employing a receptor with six methylation sites per molecule and assuming simple sets of parameters. The results are in general agreement with published data on receptor methylation, as well as with a variety of observations of bacterial chemoresponse. Multiple methylation of the receptor proves to be necessary for the cells to respond sensitively to environmental changes.

Bacterial Physiological Phenomena↗
PubMed1984

A computer simulation of geometrical configurations during cell division.

A process of cell division in the blastular wall of the starfish, Asterina pectinifera, was observed, and an attempt was made to model with a computer simulation the way in which cell number increases in such a tissue. Dividing cells at stages between the 2(11)-cell and the beginning of rotation were observed to shift these positions to the outer surface of the cell sheet by rounding up, after which they divide and slip back into the sheet as two columnar daughter cells. The change of a polygonal pattern of the blastular wall by cell division was simulated by making use of geometrical models of polygonal cells and the rule of the direction of cell division which was confirmed by observation. The simulation proves valid for describing changes of polygonal patterns of cell sheets including dividing cells.

Animals↗
PubMed1984

Cloning of leucine genes of alkalophilic Bacillus No. 221 in E. coli and B. subtilis.

The leucine genes of alkalophilic Bacillus No. 221 were cloned into the HindIII sites of pBR322 and pGR71, and recombinant plasmids pHK101 and pHK111 were constructed. The cloned 7.2 kb DNA consisting of HindIII fragments of 4.0 kb and 3.2 kb could substitute for leucine genes (alpha-isopropylmalate (alpha-IPM) synthetase gene, beta-IPM dehydrogenase gene, and alpha-IPM isomerase gene) of E. coli and B. subtilis, but not ilvB gene of B. subtilis. The 4.0 kb HindIII fragment could substitute for alpha-IPM synthetase gene of E. coli, and the 3.2 kb HindIII fragment could substitute for alpha-IPM isomerase gene of E. coli. Both 4.0 kb and 3.2 kb fragments are necessary to substitute for beta-IPM dehydrogenase gene. The expression of beta-IPM dehydrogenase gene of alkalophilic Bacillus No. 221 was repressed by the addition of leucine in the culture medium of B. subtilis carrying the plasmid pHK111. These results indicated that the 7.2 kb fragment contains the leucine gene cluster and its regulatory region.

3-Isopropylmalate Dehydrogenase↗
PubMed1984

Monoclonal IgM-secreting neoplasms. Clinical and morphologic heterogeneity.

Two patients with monoclonal IgM-secreting neoplasms are presented. Though both patients could be diagnosed as Waldenström's macroglobulinemia, the clinicopathologic features were quite contrastive. Most neoplastic cells in Case 1 showed lymphocytic morphology with rather leukemic process, while those in Case 2 were highly polymorphic with solid proliferation. The clinical and morphologic heterogeneity in these cases and cases in the literature is discussed, and the possible requirement to establish a system for the subclassification of IgM-secreting neoplasms is insisted.

Antibodies, Monoclonal↗