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Biomedical subjects

T Yano

Publications and source records attributed to T Yano.

At least 721 records · Page 40Linked to original sources
PubMed1985

Dating of the human-ape splitting by a molecular clock of mitochondrial DNA.

A new statistical method for estimating divergence dates of species from DNA sequence data by a molecular clock approach is developed. This method takes into account effectively the information contained in a set of DNA sequence data. The molecular clock of mitochondrial DNA (mtDNA) was calibrated by setting the date of divergence between primates and ungulates at the Cretaceous-Tertiary boundary (65 million years ago), when the extinction of dinosaurs occurred. A generalized least-squares method was applied in fitting a model to mtDNA sequence data, and the clock gave dates of 92.3 +/- 11.7, 13.3 +/- 1.5, 10.9 +/- 1.2, 3.7 +/- 0.6, and 2.7 +/- 0.6 million years ago (where the second of each pair of numbers is the standard deviation) for the separation of mouse, gibbon, orangutan, gorilla, and chimpanzee, respectively, from the line leading to humans. Although there is some uncertainty in the clock, this dating may pose a problem for the widely believed hypothesis that the pipedal creature Australopithecus afarensis, which lived some 3.7 million years ago at Laetoli in Tanzania and at Hadar in Ethiopia, was ancestral to man and evolved after the human-ape splitting. Another likelier possibility is that mtDNA was transferred through hybridization between a proto-human and a proto-chimpanzee after the former had developed bipedalism.

Animals↗
PubMed1985

Phylogenetic relationships among eukaryotic kingdoms inferred from ribosomal RNA sequences.

Phylogenetic trees among eukaryotic kingdoms were inferred for large- and small-subunit rRNAs by using a maximum-likelihood method developed by Felsenstein. Although Felsenstein's method assumes equal evolutionary rates for transitions and transversions, this is apparently not the case for these data. Therefore, only transversion-type substitutions were taken into account. The molecules used were large-subunit rRNAs from Xenopus laevis (Animalia), rice (Plantae), Saccharomyces cerevisiae (Fungi), Dictyostelium discoideum (Protista), and Physarum polycephalum (Protista); and small-subunit rRNAs from maize (Plantae), S. cerevisiae, X. laevis, rat (Animalia), and D. discoideum. Only conservative regions of the nucleotide sequences were considered for this study. In the maximum-likelihood trees for both large- and small-subunit rRNAs, Animalia and Fungi were the most closely related eukaryotic kingdoms, and Plantae is the next most closely related kingdom, although other branching orders among Plantae, Animalia, and Fungi were not excluded by this work. These three eukaryotic kingdoms apparently shared a common ancestor after the divergence of the two species of Protista, D. discoideum and P. polycephalum. These two species of Protista do not form a clade, and P. polycephalum diverged first and D. discoideum second from the line leading to the common ancestor of Plantae, Animalia, and Fungi. The sequence data indicate that a drastic change occurred in the nucleotide sequences of rRNAs during the evolutionary separation between prokaryote and eukaryote.

Animals↗
PubMed1985

Purification and properties of nucleotide pyrophosphatase from human placenta.

Nucleotide pyrophosphatase was purified from human placenta to near homogeneity with a specific activity of about 500-fold over the Triton extract of the homogenate. Purification was achieved most effectively by successive chromatographic steps with AMP-agarose and ADP-agarose columns, based on the affinity of the enzyme towards 5'-adenylate and adenosine 3',5'-diphosphate, and a lectin-Sepharose column, based on the glycoprotein nature of the enzyme. The purified enzyme was found to be essentially homogeneous on SDS-polyacrylamide gel electrophoresis with a mobility corresponding to 130K. The purified enzyme was found to hydrolyze a wide variety of nucleotides, i.e. 3'-phosphoadenosine 5'-phosphosulfate (PAPS), adenosine 5'-phosphosulfate (APS), NADH, ATP, nucleotide sugars, oligonucleotides, and p-nitrophenyl-thymidine 5'-phosphate (PNTP). From the oligonucleotides, the enzyme produced 5'-phosphates. Mg2+ was required for full activity. Glycine and sulfhydryl compounds such as 2-mercaptoethanol and 2,3-dimercapto-1-propanol were inhibitory. Most of these properties are common to nucleotide pyrophosphatases [EC 3.6.1.9] and type I (5'-phosphate forming) phosphodiesterases [EC 3.1.4.1] from various sources. The relevance of this enzyme to a unique genetic disease, Lowe's syndrome, is discussed.

Cations↗
PubMed1985

[Effects of human urinary trypsin inhibitor against operative stress].

Effects of human urinary trypsin inhibitor (MTI) against operative stress were investigated. Laparotomy in a mouse caused suppression of immunological functions such as phagocytic activity and antibody formation, followed by loss of resistivity to bacterial infection and acceleration of growth of concealed tumor. The operation also caused damages to the body such as enhancement of protein catabolism and suppression of renal function, followed by increase of blood urea nitrogen, increase of protease activity in skeletal muscle and suppression of PSP clearance. Since MTI wholly ameliorated these undesirable conditions of the body caused by operative stress, it was suggested that MTI has an effect on maintaining the homeostasis of the living body as well as the ability to inhibit trypsin.

Adjuvants, Immunologic↗
PubMed1985

[Experimental studies on regeneration of the pancreas--morphological and functional restoration of the remnant pancreas after major pancreatectomy].

In order to elucidate a regeneration of the pancreas, morphological and functional changes after major pancreatic resection were sequentially investigated in dogs. Within the first week after major pancreatectomy, the acinar cell division occurred, followed by hypertrophy resulting in an increase of the weight of the remnant pancreas. The regeneration rate correlated with the resection rate, glucose tolerance test, and insulin secretion of the remnant pancreas. Immediately after resection of more than 92% of the pancreas, severe diabetes and diarrhea developed. The regeneration rate was 29.9 +/- 6.03% (mean +/- SD) three to six weeks after surgery, without any recovery of the exocrine function. After twelve weeks following resection of 74 to 92% of the pancreas, so-called Sandmeyer's diabetes developed. The regeneration rate was 45.3 +/- 4.22% in the nondiabetic group, accompanied with a good recovery of the exocrine function, but in the diabetic group it revealed regeneration rate of 15.4 +/- 2.39% with less recovery of the exocrine function. When less than 74% of the pancreas was resected, no significant changes were observed in both morphological and functional studies in the remnant pancreas with regeneration rate of 5.5 +/- 6.62%.

Amylases↗
PubMed1985

[Treatment of meningeal carcinomatosis--neocarzinostatin perfusion therapy in the CSF pathway].

The authors presented the results of perfusion chemotherapy in the CSF pathway with neocarzinostatin (NCS) for the treatment of meningeal carcinomatosis. In three cases of stomach cancer and one case of malignant lymphoma, cranial polyneuropathy, progressive hydrocephalus and positive cytology of the CSF were found during treatment of malignant tumors. NCS therapy was performed by means of perfusion from the spinal subarachnoid space to the ventricle utilizing Ommaya's reservoir, or simply by repeated lumbar punctures. In all of four cases the number of malignant cells in the CSF was significantly diminished, and temporary neurological improvement was observed until the patient's death due to advanced primary lesions. These results indicated that in cases of meningeal carcinomatosis, NCS perfusion therapy using the CSF pathway was a much more favorable method than treatment with other chemotherapeutic agents with less noticeable side effects.

Adult↗