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Biomedical subjects

J Otsuka

Publications and source records attributed to J Otsuka.

At least 73 records · Page 4Linked to original sources
PubMed1981

Fine structure of the parotid gland of Chinese hamster (Cricetulus griseus).

The parotid gland of Chinese hamster was examined by light and electron microscopy. The parotid acinar cells contained acidophile granules and reacted with the periodic acid-Schiff (PAS) reagent but failed to stain with alcian blue (AB). The acini were composed of light, dark and specific light cells containing secretory granules of various sizes and densities. Intercalated duct cells were composed exclusively of light cells and contained a few vesicles, fine granules and polygonal granules. Striated duct cells were PAS-positive and AB-negative, being composed of light and dark cells. These cells contained vesicles and fine granules, and the light cells in the male contained electron dense polygonal granules. No myoepithelial cells were detected around the acini, intercalated ducts or striated ducts, while nerve terminals were demonstrable among adjacent acinar cells or between the acinar cells and the underlying basement lamina.

Animals↗
PubMed1981

[Linear measurements of the bones of Lepus brachyurus brachyurus Temminck, Pentalagus furnessi Stone and Oryctolagus cuniculus Linnaeus (JW-NIBS). II. On the Ossa membri thoracici et pelvini (author's transl)].

The bones of the thoracic and pelvic limbs of Lepus brachyurus brachyurus, Pentalagus furnessi and Oryctolagus cuniculus (strain: JW-NIBS) were investigated morphologically and osteometrically. The results obtained are summarized as follows. 1. The length of long bones in limbs is the largest in Lepus except the distal phalanges, next in JW-NIBS and the smallest in Pentalagus. 2. The breadth of long bones in limbs except the distal phalanges is generally larger in Pentalagus than in Lepus and JW-NIBS, and not significantly different between Lepus and JW-NIBS. 3. The area of articular surface in each limb bone is most extensive in Pentalagus. 4. The distal phalanges of Pentalagus are strong and heavy, the largest in length and the widest in breadth, while those of JW-NIBS are small and light. 5. The distances between the right and left cranial ventral iliac spines, acetabula or ischiatic tuberosities in hip bones are longer in the female than in the male. These differences in sex are distinct in Lepus and JW-NIBS and not clear in Pentalagus.

Animals↗
PubMed1980

[Linear measurements of the bones of Lepus brachyurus brachyurus Temminck, Pentalagus furnessi Stone and oryctolagus cuniculus Linnaeus (JW-NIBS). I. On the cranium and ossa trunci (author's transl)].

The Ossa cranii and ossa trunci in Lepus brachyurus brachyurus, Pentalagus furnessi and Oryctolagus cuniculus (strain : JW-NIBS) were investigated morphologically and osteometrically. The number of coccygeal vertebrae is 10-12 in Lepus, 10-11 in Pentalagus and 15-17 in JW-NIBS. The number of upper cheek teeth of Pentalagus is six on one side. Therefore, Lyon's view that the number of upper cheek teeth of Pentalagus is five may not be applicable to use as one of the discriminative characteristics. The sizes of orbit and tympanic bullae in Pentalagus are remarkably small. The length of neurocranium and the inner breadth of caudal surface of vertebral foramina in cervical, thoracic and lumber vertebrae in JW-NIBS are small than those in Lepus and Pentalagus. Among three genera, there are conspicuous differences in shapes of spinous and transverse processus in the lumber vertebrae. The coefficient of variability of the measurements in JW-NIBS is smaller than that in Lepus.

Animals↗
PubMed1978

Conformational change and cooperative ligand binding in hemoglobin.

Although many studies have been carried out on the cooperativityly of ligand binding to hemoglobin, its molecular mechanism is not yet completely confirmed. Various models have been proposed on one hand, but on the other hand the direct judgement of the validity of each model is confronted with experimental difficulties. With this situation in mind, we re-examine carefully various kinds of experimental data, with the intention of finding any hints for future studies on the molecular mechanism of the cooperativity of ligand binding not only to hemoglobin but also to other allosteric proteins composed of subunits. As a result of these re-examinations most of the experimental data can be consistently explained from the viewpoint that the strain due to ligation is transmitted to the interfaces of the subunits and the degree of the strain stored in the interfaces between the subunits controls the cooperativity of of ligand binding. The subjects selected to the present study are molecular structural differences between the deoxy- and oxy-hemoglobin, temperature dependence of oxygen equilibrium constants, and recombination curves of carbon monoxide in flash photolysis experiments. In the first section, the difference of the interfaces of the subunits between deoxy- and oxy-hemoglobin is investigated on the basis of the atomic coordinates determined by Perutz et al. and we examine energetically which of the segment's pairs contributes mainly to the difference in the molecular structure between the two forms. On the basis of this investigation, it is shown in the next section that the oxygen equilibrium constants of human adult hemoglobin under normal physiological conditions are well explained by the following sequence of the conformational changes. The local changes in the interfaces of the subunits are reflected directly on the small differences among the first three Adair constants and the succeeding rearrangement to the four subunits causes the outstandingly larger value of the fourth Adair constant. In more alkaline pH, this rearrangement begins to occur at the earlier stages of ligation. In the succeeding section, it is pointed out that the property of this rearrangement can be studied in more detail through the recombination curves followed by flash photolysis under special conditions.

Allosteric Regulation↗
PubMed1975

Calculation of the energy difference between the quaternary structures of deoxy- and oxyhemoglobin.

The energy difference between the quaternary structures of deoxy- and oxyhemoglobin is evaluated on the basis of the atomic coordinates determined by X-ray diffraction analysis. Calculation of the van der Waals interaction between subunits shows that in a hemoglobin molecule as a whole, the interaction is more attractive in the oxy form than in the deoxy form by about 8 kcal/mol, and that in each pair of two subunits except the pair alpha1alpha2, the interaction energy varies by about 15 kcal/mol. The electrostatic interactions originating in the partial charges on all constituent atoms of hemoglobin and in the polar residues on the surface of hemoglobin make only a small contribution to the energy difference between the quaternary structures of deoxy- and oxyhemoglobin. Thus, the contribution of the clusters of the polar residues in the internal cavity between like subunits and also of the freedom of rotation of the C-terminal of each subunit in oxyhemoglobin may be important energetically in the transition from deoxy to oxy quaternary structure. In this point, the present calculation supports Perutz' model, but suggests necessity of further investigations on the transitional characteristics of the quaternary structure in the intermediate steps of oxygenation. The discussion on the transitional characteristics is given in the last section.

Animals↗