Biomedical subjects

M Terasaki

Publications and source records attributed to M Terasaki.

15 recordsLinked to original sources

PubMed1992

Clinical application of arterialization of portal vein in living related donor partial liver transplantation.

Arterialization of the portal vein was employed during hepatic arterial reconstruction in our first few clinical experiences of partial liver transplantation using liver grafts obtained from living related donors. This procedure reduced the time required for revascularization of the grafts to about 25 min, and could in fact reduce the ischemic phase of the grafts. Repeated practice of the clinical transplantation technique has shortened the time needed to complete vascular reconstruction, eliminating the need for this procedure in most of our subsequent cases. In many clinical cases, however, there may be emergency situations which require vascular reconstruction, resulting in a prolongation of ischemic phase and the deterioration of the cellular viability of the graft. In such situations, arterialization of the portal vein can be a useful way to prevent the prolongation of the ischemic phase and to rescue the graft.

Arteriovenous Shunt, Surgical↗

PubMed1992

Preserved mitochondrial function by allopurinol despite deteriorated hemodynamics in warm ischemia-damaged canine liver.

To investigate the pathophysiology of warm ischemia (WI) of the liver, the changes in hemodynamics and energy metabolism were studied during and after 60-min complete WI induced by total hepatic vascular exclusion (HVE) in the canine model. Hepatic arterial blood flow after WI was maintained at 76% of the pre-ischemic level, while portal blood flow was only 27% of the pre-ischemic level associated with increased portal vein pressure, which was twice the pre-ischemic level, resulting in a decrease of total hepatic blood flow to 46% of the pre-ischemic level. Concentration of tissue lipid peroxide increased after WI. Arterial blood ketone body ratio (AKBR), which reflects the hepatic mitochondrial redox state, could not recover to the pre-ischemic level after termination of WI. However, when 100 mg/kg of allopurinol (xanthine oxidase inhibitor) was administered intravenously 10 min prior to initiating WI, AKBR was restored to the pre-ischemic level at 30 min after WI in spite of the fact that allopurinol administration to one group produced no remarkable changes in the hepatic hemodynamics compared with the group without allopurinol treatment. Concentration of adenine nucleotides was significantly higher for the treated group at the end of and after WI than for the group without allopurinol treatment and was maintained at a higher level even after WI. Lipid peroxide production was suppressed. Electron microscopic examination revealed that allopurinol treatment could not prevent mitochondrial swelling. It is suggested that WI causes injury primarily to the portal sinusoidal circulation, resulting in portal congestion concomitant with high portal pressure after the release of WI. Allopurinol could prevent the deterioration of mitochondrial ATP metabolism, and was able to inhibit lipid peroxide production, resulting in the rapid recovery of mitochondrial redox state in spite of the fact that it produced no amelioration of hepatic hemodynamics and morphological alterations.

Adenosine Triphosphate↗

PubMed1992

Decrease in regeneration capacity of rat liver after external biliary drainage.

In order to discover the effect of external biliary drainage on liver regeneration, we have produced a model system carrying cannula in the common bile duct of rat liver and examined the regeneration capacity of liver after partial hepatectomy under various conditions. Previously we have shown that hepatic cells proliferate by obstructive jaundice alone without partial hepatectomy [Terasaki et al; Jpn J Cancer Res 1991;82:170-175]. In the present study, we showed that DNA polymerase-alpha was induced by partial hepatectomy of rats suffering from obstructive jaundice and the induced level was similar to that of the normal regenerating liver. The level of DNA polymerase-alpha activity corresponded well to the liver regeneration capacity estimated by mitotic index. Contrary to our expectation, external biliary drainage for obstructive jaundice markedly suppressed the regeneration capacity of the remaining liver which was estimated by DNA polymerase-alpha activity, mitotic index and [3H]thymidine incorporation. The suppression may be due to the external biliary drainage itself because the liver regeneration of normal rats without jaundice was also suppressed by the biliary drainage. These results suggest that the external biliary drainage seriously suppresses the regeneration capacity of liver at least at the early stage of obstructive jaundice.

Animals↗

PubMed1992

Polarity of the ascidian egg cortex before fertilization.

The unfertilized ascidian egg displays a visible polar organization along its animal-vegetal axis. In particular, the myoplasm, a mitochondria-rich subcortical domain inherited by the blastomeres that differentiate into muscle cells, is mainly situated in the vegetal hemisphere. We show that, in the unfertilized egg, this vegetal domain is enriched in actin and microfilaments and excludes microtubules. This polar distribution of microfilaments and microtubules persists in isolated cortices prepared by shearing eggs attached to a polylysine-coated surface. The isolated cortex is further characterized by an elaborate network of tubules and sheets of endoplasmic reticulum (ER). This cortical ER network is tethered to the plasma membrane at discrete sites, is covered with ribosomes and contains a calsequestrin-like protein. Interestingly, this ER network is distributed in a polar fashion along the animal-vegetal axis of the egg: regions with a dense network consisting mainly of sheets or tightly knit tubes are present in the vegetal hemisphere only, whereas areas characterized by a sparse tubular ER network are uniquely found in the animal hemisphere region. The stability of the polar organization of the cortex was studied by perturbing the distribution of organelles in the egg and depolymerizing microfilaments and microtubules. The polar organization of the cortical ER network persists after treatment of eggs with nocodazole, but is disrupted by treatment with cytochalasin B. In addition, we show that centrifugal forces that displace the cytoplasmic organelles do not alter the appearance and polar organization of the isolated egg cortex. These findings taken together with our previous work suggest that the intrinsic polar distribution of cortical membranous and cytoskeletal components along the animal-vegetal axis of the egg are important for the spatial organization of calcium-dependent events and their developmental consequences.

Actin Cytoskeleton↗

PubMed1992

Characterization of endoplasmic reticulum by co-localization of BiP and dicarbocyanine dyes.

The original concept of endoplasmic reticulum derived from the observation of a reticular network in cultured fibroblasts by electron microscopy of whole cells. It was previously reported that the fluorescent dye, DiOC6(3), stains a similar network as well as mitochondria and other organelles in living cells. Here, we investigate the significance of the structures labeled by DiO6(3) in CV-1 cells, a monkey epithelial cell line. First, we show that the network stained in living CV-1 cells is preserved by glutaraldehyde fixation and then we co-label it with an antibody against BiP (immunoglobulin binding protein), a protein commonly accepted to be present in the endoplasmic reticulum. Anti-BiP labeled the same network as that labeled by DiOC6(3), so this network now is identified as being part of the endoplasmic reticulum. DiOC6(3) labels many other membrane compartments in addition to the endoplasmic reticulum. This, along with its lipophilic properties, suggests that DiOC6(3) stains all intracellular membranes. However, the extensive reticular network in the thin peripheral regions of cultured cells is easily distinguished from these other membranes. Thus, staining by DiOC6(3) is a useful method for localizing the endoplasmic reticulum, particularly in thin peripheral regions of cultured cells.

Animals↗

PubMed1992

[Construction of a multiple mood scale].

A self-report instrument to measure multiple mood states was constructed. Six hundred and forty-eight Japanese affect adjectives were collected and divided into two lists. Japanese undergraduates totaling 1,254 rated each adjective in the list on a 4-point intensity scale to assess their momentary mood states. Factor analyses revealed 131 items with high loading on extracted major factors. The new list of these 131 items was rated three times by undergraduates totaling 1,768 and was factor analysed. Throughout the factor analyses, eight factors emerged with consistent reliability. Finally, 80 items highly loaded on these factors were selected to construct eight 10-item mood scales. These scales were called Depression (Anxiety), Hostility, Boredom, Liveliness, Well Being, Friendliness, Concentration and Startle. The scales were shown to be internally consistent. A comparison of these scales with the English mood scales was presented.

Adolescent↗

PubMed1991

Biogenesis of transverse tubules in skeletal muscle in vitro.

The transverse (T) tubules of skeletal muscle are membrane tubules that are continuous with the plasma membrane and penetrate the mature muscle fiber radially to carry surface membrane depolarization to the sites of excitation-contraction coupling. We have studied the development of the T-tubule system in cultured amphibian and mammalian muscle cells using a fluorescent lipid probe and antibodies against T-tubules and plasma membranes. Both the lipid probe and the T-tubule antibody recognized an extensive tubular membrane system which subsequently differentiated into the T-system. At all developmental stages, the molecular composition of the T-system was distinct from that of the plasma membrane, suggesting that during myogenesis T-tubules and the plasma membrane form independently from each other and that exchange of membrane proteins between the two continuous compartments is restricted. In rat muscle cultures, T-tubule-specific antigens were first expressed in terminally differentiated myoblasts. Prior to myoblast fusion the antigens appeared as punctate label throughout the cytoplasm. Shortly after fusion the T-tubule-specific antibody labeled a tubular membrane system that extended from the perinuclear region and penetrated most parts of the cells. In contrast, the lipid probe, which labels the T-tubules by virtue of their direct continuity with the plasma membrane, only labeled short tubules extending from the plasma membrane into the periphery of the myotubes at the early stage in development. Thus, the assembly of the T-tubules appears to begin before their connections with the plasma membrane are established.

Animals↗

PubMed1991

Characterization of sea urchin egg endoplasmic reticulum in cortical preparations.

The cortical endoplasmic reticulum (ER) of sea urchin eggs was localized on isolated egg cortices by staining with aqueous suspensions of the dicarbocyanine "DiI." Immunofluorescence localization of a calsequestrin-like protein was essentially identical; this is consistent with a role for the ER in calcium regulation. The ER often encircles cortical granules, making it well-suited for initiating fusion and propagating the calcium wave. Thiazole orange and Hoechst dye 33258 at pH 2 stain ribosomes bound to the ER, providing evidence that the cortical ER is rough ER. High chloride concentrations were found to disrupt ER continuity.

Animals↗

PubMed1991

Energy metabolism of the liver in brain dead dogs assessed by 31P-NMR spectroscopy and arterial ketone body ratio.

The changes in hepatic energy state were assessed by 31P-nuclear magnetic resonance spectroscopy (31P-MRS) and arterial ketone body ratio (AKBR) in brain dead dogs. 31P-MRS and AKBR were measured before and at 3 hours after brain death. Wiggers' shock model was employed to compare the energy metabolism during hypotension. 1) The brain death model: Systemic blood pressure changed from 178.3/115.0 mmHg (mean) in the control period, to 259.5/162.5 mmHg during Cushing phenomenon (CU period) and to 63.3/51.7 mmHg after completion of brain death (BD period). beta-ATP/Pi increased from 1.27 +/- 0.14 (mean +/- SEM) to 1.46 +/- 0.16 in the early CU period, and then decreased to 1.11 +/- 0.15 at 60 minutes after BD, followed by a gradual increase to 1.33 +/- 0.13 at 3 hours after BD. Intracellular pH (pHi) increased alkaline to the control value. AKBR decreased from 1.10 +/- 0.26 to 0.46 +/- 0.15 in the CU period (p less than 0.05) and then increased to 1.48 +/- 0.25 after BD. 2) Wiggers' shock model: Systemic blood pressure was 190.0/112.5 mmHg in the control period, 83.8/51.3 mmHg during exsanguination (EX period) and 185.0/117.0 mmHg after retransfusion (RT period). beta-ATP/Pi decreased from 1.17 +/- 0.13 to 0.61 +/- 0.10 in the EX period (p less than 0.05) and increased to 1.37 +/- 0.08 in the RT period. The pHi deviated from 7.33 +/- 0.07 to 6.82 +/- 0.14 in the EX period (p less than 0.01) and to 7.51 +/- 0.21 in the RT period. AKBR decreased from 1.00 +/- 0.11 to 0.21 +/- 0.04 in the EX period and increased to 1.08 +/- 0.12 in the RT period. The energy metabolism of the liver was well maintained in the state of brain death in spite of remarkable hypotension, although that was not the case with Wiggers' shock model. It was suggested that the combination of 31P-MRS and AKBR was useful for the evaluation of graft liver viability.

Adenosine Triphosphate↗

PubMed1991

Organization of the sea urchin egg endoplasmic reticulum and its reorganization at fertilization.

The ER of eggs of the sea urchin Lytechinus pictus was stained by microinjecting a saturated solution of the fluorescent dicarbocyanine DiIC18(3) (DiI) in soybean oil; the dye spread from the oil drop into ER membranes throughout the egg but not into other organelles. Confocal microscopy revealed large cisternae extending throughout the interior of the egg and a tubular membrane network at the cortex. Since diffusion of DiI is confined to continuous bilayers, the spread of the dye supports the concept that the ER is a cell-wide, interconnected compartment. In time lapse observations, the internal cisternae were seen to be in continuous motion, while the cortical ER was stationary. After fertilization, the internal ER appeared to become more finely divided, beginning as a wave apparently coincident with the calcium wave and becoming most marked by 2-3 min. By 5-8 min the ER returned to an organization similar to that of the unfertilized egg. The cortical network also changed at fertilization; it became disrupted and eventually recovered. DiI labeling allowed continuous observations of the ER during pronuclear migration and mitosis. DiI-stained membranes accumulated in the region of the microtubule array surrounding the sperm nucleus and centriole (the sperm aster) as it migrated to the center of the egg; this accumulation persisted near the centrosomes and zygote nucleus throughout pronuclear fusion and the first two mitotic cycles. We have used a new method to observe the spatial and temporal organization of the ER in a living cell, and we have demonstrated a striking reorganization of the ER at fertilization.

Animals↗

PubMed1991

Demonstration of calcium uptake and release by sea urchin egg cortical endoplasmic reticulum.

The calcium indicator dye fluo-3/AM was loaded into the ER of isolated cortices of unfertilized eggs of the sea urchin Arbacia punctulata. Development of the fluorescent signal took from 8 to 40 min and usually required 1 mM ATP. The signal decreased to a minimum level within 30 s after perfusion with 1 microM InsP3 and increased within 5 min when InsP3 was replaced with 1 mM ATP. Also, the fluorescence signal was lowered rapidly by perfusion with 10 microM A23187 or 10 microM ionomycin. These findings demonstrate that the cortical ER is a site of ATP-dependent calcium sequestration and InsP3-induced calcium release. A light-induced wave of calcium release, traveling between 0.7 and 2.8 microns/s (average speed 1.4 microns/s, N = 8), was sometimes observed during time lapse recordings; it may therefore be possible to use the isolated cortex preparation to investigate the postfertilization calcium wave.

Aniline Compounds↗

PubMed1991

Induction of DNA replication and cell growth in rat liver by obstructive jaundice.

Obstructive jaundice, produced by ligating the common bile duct, induced a transient DNA replication followed by cell proliferation in rat liver. At 48 h after the operation, DNA polymerase alpha activity started to increase and reached its maximum level (more than twice the control) at day 4. At day 7, the enzyme level had decreased to the control level. Pulse-labeling experiment using radioactive thymidine showed that the rate of DNA synthesis increased approximately 2.5-fold in the same pattern as that of DNA polymerase alpha. The mitotic index in hepatocytes also increased 10-fold at day 4 and then decreased. The proliferation of liver cells induced by obstructive jaundice mimics the regeneration of partially hepatectomized liver, although the response was slightly delayed and the proliferation was transient.

Alanine Transaminase↗

PubMed1990

Recent progress on structural interactions of the endoplasmic reticulum.

Progress has been made recently in understanding certain aspects of the structure of the ER. It is very likely that kinesin, dynein, and myosin are associated with the ER and are responsible for distributing the fluid membranes of the ER by interaction of these motors with microtubules and actin filaments. Other kinds of structural protein associations with the ER are also likely, for instance, binding of cortical ER to subplasmalemmal regions or microtubule binding and/or polymerization along ER tubules.

Animals↗

PubMed1979

Major intracellular cations and growth control: correspondence among magnesium content, protein synthesis, and the onset of DNA synthesis in BALB/c3T3 cells.

Omission of Ca(2+) from the medium of confluent BALB/c3T3 cells for a period of 17 hr causes a large decrease in the number of cells synthesizing DNA. This effect is reversed by raising the Mg(2+) concentration of the medium to 20 mM. However, if the [Mg(2+)] is greater than 20 mM ("ultra-high" Mg(2+)), there is again a decrease in the number of cells synthesizing DNA. The synthesis of protein has a similar dependence on Mg(2+) concentration in Ca(2+)-deficient medium, but it responds within 45 min of the shift in cation concentrations rather than the 10 hr that is required for the change in DNA synthesis to become apparent. Cells in the ultrahigh Mg(2+) concentrations that are at first inhibitory to protein synthesis later return to maximal protein synthesis. This delayed increase in protein synthesis is reflected in a delayed increase in DNA synthesis. Intracellular concentrations of Mg(2+) in Ca(2+)-deficient media increase in proportion to extracellular Mg(2+) concentrations. Cells in medium with 30 mM Mg(2+) have a high intracellular content of Mg(2+) at 3 hr but have decreased their intracellular content by 17 hr, a time at which protein synthesis has been restored to normal. Intracellular Na(+) and K(+) concentrations also change in Ca(2+)-deficient medium, but independent variation of these ions shows that protein synthesis is relatively insensitive to their concentration. Intracellular Ca(2+) remains fairly constant under all these conditions. The rate of protein synthesis of intact cells changes as a function of intracellular Mg(2+) content in a manner very similar to that which has been reported for cell-free systems. We conclude that protein synthesis is very sensitive to small changes in intracellular [Mg(2+)] within physiological range and that the onset of DNA synthesis is dependent on the rate of protein synthesis. Regulation of the availability of Mg(2+) within the cell therefore presents a plausible mechanism for growth control.

Animals↗

PubMed1978

Magnesium reverses inhibitory effects of calcium deprivation on coordinate response of 3T3 cells to serum.

Deprivation of Ca(2+) in crowded cultures of 3T3 cells inhibits the onset of DNA synthesis. By raising [Mg(2+)] to 15 mM the inhibition produced by Ca(2+) deprivation can be fully overcome. Sparse cultures are not inhibited by a similar deprivation of Ca(2+), and therefore are not stimulated by supranormal [Mg(2+)]. The time course of stimulation of the onset of DNA synthesis by supranormal [Mg(2+)] in low [Ca(2+)] is the same as that produced by serum in physiological concentrations of Ca(2+) and Mg(2+). Concentrations of Mg(2+) > 20 mM in low [Ca(2+)] reverse the stimulation, and [Mg(2+)] >/= 30 mM kills many cells. In contrast to the stimulation by 15 mM Mg(2+), supranormal [Ca(2+)] has no effect on the onset of DNA synthesis in cultures inhibited by Mg(2+) deprivation, if the formation of insoluble Ca-P(i) complexes is prevented. Neither Na(+) nor K(+) reproduces the effects of Mg(2+). The uptake of uridine is another parameter of the coordinate response of 3T3 cells to serum stimulation that is inhibited by Ca(2+) deprivation, and supranormal [Mg(2+)] also reverses this inhibition. The results support the thesis that the coordinate response of growth and metabolism to external effectors is regulated by the availability of Mg(2+) within the cell and that the inhibitory effects of Ca(2+) deprivation are indirect and caused by a reduction in the availability of Mg(2+).

Blood↗