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Biomedical subjects

J Tanaka

Publications and source records attributed to J Tanaka.

At least 829 records · Page 46Linked to original sources
PubMed1983

Effect of hypothermia on survival time and ECG in rats with acute blood loss.

The effects of hypothermia on survival time and ECGs were investigated in hemorrhagic-shocked rats. Acute blood loss corresponding to LD84 was achieved within 1 min through cannulation of the carotid artery. Immediately following the hemorrhagic episode, extracorporeal cooling was performed by placing the animals, with ice packs attached to their lateral sides, in a cold water bath. Rewarming was achieved by removing the ice packs and resetting the temperature of the water bath to 37 degrees C. With this system, the survival time of the hemorrhagic rats was lengthened from 40 to 60 min without rewarming and to 123 min with rewarming. ECGs showed sinus bradycardia, prolonged PR and QRS intervals, AV block, and finally ventricular fibrillation in both the control and hemorrhagic groups during extracorporeal cooling. During rewarming, the above ECG changes returned to normal in the control group as did body temperature. In contrast, animals in the hemorrhagic group did not survive. Body temperature in this group began to rise toward normal, and above ECG changes showed slight but not complete improvement. It is concluded that extracorporeal cooling can lengthen the survival time of hemorrhagic-shocked rats and that recovery of the disturbed conduction system is a prerequisite for survival from severe hypothermia.

Acute Disease↗
PubMed1982

Saxitoxin binding sites in frog-myocardial cytosol.

Cytosolic fractions of frog heart homogenates contain large amounts of a soluble, large molecular weight protein that binds the specific neurotoxin saxitoxin with the same high affinity as does the plasma membrane. Another neurotoxin, tetrodotoxin, which ordinarily is competitive with saxitoxin, does not displace saxitoxin from the cytosolic sites or from plasma membrane-enriched vesicular fractions even when its concentration exceeds that of saxitoxin by a factor of 1000. Thus, cytosolic sites are similar to membrane sites in this respect. The vesicular fraction accounts quantitatively for the amount of saxitoxin bound by whole ventricles, so that no appreciable losses seem to occur. Therefore, the cytosolic site probably is a membrane site precursor, although other possibilities cannot be ruled out. In any case, the occurrence of a soluble molecule closely related to the sodium channel provides opportunities for further study of the structure of the sodium channel.

Animals↗
PubMed1982

Bentall's operation. A modification for coronary-graft anastomosis in an annuloaortic ectasia without displacement of the coronary origins.

Bentall's operation using a composite graft for complete replacement of an ascending aortic aneurysm and associated incompetent aortic valve is being widely used. In case of no displacement of the coronary origins, however, this technique often leads to difficulties in restoring the coronary flow. We now report a successful modification for this coronary-graft anastomosis.

Adolescent↗
PubMed1982

Coenzyme Q10: the prophylactic effect on low cardiac output following cardiac valve replacement.

A randomized, prospective study of the effectiveness of preoperative administration of coenzyme Q10 on the prophylaxis of postoperative low cardiac output state was performed in 50 patients with acquired valvular diseases necessitating valve replacement. There were 25 patients in the treatment group and 25 in the control group. Patients in the treatment group received 30 to 60 mg of coenzyme Q10 orally for six days before operation. Preoperative clinical variables, operative procedures, total cardiopulmonary bypass time, and aortic cross-clamping time were similar for the two groups. Postoperatively, mild to severe low cardiac output state developed in 28 of 50 patients (56%) and necessitated the administration of considerable amounts of inotropic agent. The treatment group showed a significantly lower incidence of low cardiac output state during the recovery period than the control group (p less than 0.05). These results suggest that preoperative administration of coenzyme Q10 will increase the tolerance of human hearts to ischemia during aortic cross-clamping.

Adult↗
PubMed1982

Significance of mitochondrial enhancement in restoring hepatic energy charge after revascularization of isolated ischemic liver.

The critical point of reversibility in hepatic ischemia was investigated. Immediately after the liver was isolated, the hepatic energy charge decreased rapidly from the control level of 0.85 to 0.28 and remained at a constant value during 30-, 60-, and 90-min ischemic periods. After revascularization of the liver, the rapidity toward the normalization of the energy charge and the mitochondrial phosphorylative activity were different according to the ischemic time. The livers after 30- and 60-min exclusion showed a normalization of the energy charge and the enhancement of mitochondrial phosphorylative activity, while the livers after 90-min exclusion showed only a slight increase of energy charge, which remained far from the normal value, and the enhancement of mitochondrial phosphorylative activity was not observed. From these results, it is suggestive that a rapid enhancement in phosphorylative activity of the liver mitochondria after revascularization plays a decisive role on the restoration of the viability of isolated ischemic liver.

Adenine Nucleotides↗
PubMed1982

The pathophysiology of septic shock: acute renal failure in rats following live E coli injection. A histochemical study of the proximal tubules.

Acute renal failure was induced in rats by injection of a lethal dose of live Escherichia coli. Enzyme activities of the proximal tubule were studied histochemically at three, six, and 12 hours following E coli injection. The enzymes examined were alkaline phosphatase (A1Pase), acid phosphatase (AcPase), adenosine triphosphatase (ATPase), succinate dehydrogenase (SDH), glucose-6-phosphatase (G6Pase), and glucose-6-phosphate dehydrogenase (G6PDH). At three hours, ATPase activity was slightly decreased, while other enzymes showed no changes in activities at this time. At six hours, a slight increase in AcPase activity was seen in the pars recta. At this time, although A1Pase showed no change in activity, other enzymes revealed slight decreases in activities: G6Pase and SDH in the pars convoluta, ATPase in the pars convoluta and pars recta, and G6PDH in pars recta. At 12 hours after treatment, all enzymes showed decreases in activities; however, no necrotic tubule changes were detectable by light microscopy. Since sodium reabsorption in proximal tubules requires a sodium pump consisting of Na-K ATPase, early histochemical changes in ATPase activity in proximal tubule following bacteremia may be related to early changes in sodium reabsorption causing polyuria and to the subsequent development of acute renal failure.

Acute Kidney Injury↗
PubMed1982

The pathophysiology of septic shock: studies of reticuloendothelial system function and liver high-energy metabolism in rats following sublethal and lethal Escherichia coli injection.

Phagocytic indices and the hepatic energy charge (ATP + 1/2 ADP/ATP + ADP + AMP) were studied in rats after intravenous sublethal or lethal injection of live Escherichia coli (12--15 X 10(8) or 4--5 X 10(8) organisms/100 gm of body weight). Phagocytic indices as determined by carbon clearance test were progressively decreased in both groups from 0.063 of control to 0.028 or 0.022 (sublethal or lethal) at 12 hours (P less than 0.001). This was mainly due to marked decrease in carbon uptake in the liver even though a marked accumulation of carbon occurred in the lung. At 24 hours in the sublethal group, the phagocytic index was elevated (P less than 0.01). With regard to the spleen, carbon uptake in the sublethal group remained unchanged, in contrast to the decreased uptake in the lethal group, leading to a significant difference between sublethal and lethal groups (P less than 0.05 or less at six and 12 hours). On the other hand, the hepatic energy charge levels in the lethal group progressively decreased from 0.86 to 0.62 until death (P less than 0.001), while those in the sublethal group remained moderately decreased. Following carbon administration, the hepatic energy charges in the control and lethal groups were decreased, while those in the sublethal group remained unchanged. These results suggest a functional reserve of phagocytic activity in liver and spleen and activated high-energy metabolism in the liver for phagocytosis may play a role in determining survival from bacteremic shock.

Adenosine Triphosphate↗
PubMed1982

The pathophysiology of septic shock: changes in hemodynamics in rats following live E coli injection. An application of the thermodilution method for measurement of cardiac output.

Fifteen anesthetized rats, 273 +/- 9 gm (SEM), were monitored hemodynamically for six hours following an IV injection of a sublethal (4--5) X 10(8) organisms/100 gm body wt, n = 5) or lethal 12--15 X 10(8) organisms/100 gm body wt, n = 5) dose of live Escherichia coli or saline (control, n = 5). A transpulmonary thermodilution method was used for measurement of cardiac output. Changes in the arterial blood temperature and pressure were recorded on a polygraph. In a simulated hydraulic model system, the measured flow rate was well correlated ( r = 0.993, P less than 0.001) with various actual flow readings (30--130 ml/minute). A sublethal dose resulted in a transient hyperdynamic state in the early stage; the cardiac index was increased from the initial rate of 258.2 +/- 9.4 to 312.3 +/- 10.7 ml/minute/kg with a concomitant decrease in the total peripheral resistance from 0.497 +/- 0.019 to 0.367 +/- 0.022 mm Hg/ml/minute/kg which was sustained for 120 minutes after treatment. In contrast, a lethal dose caused a prolonged hyperdynamic state in the early stage followed by a hypodynamic state in the late stage. The cardiac index was increased from 2.54 +/- 4.5 to 306.0 +/- 10.8 ml/minute/kg and the total peripheral resistance was decreased from 0.513 +/- 0.024 to 0.337 +/- 0.015 mm Hg/ml/minute/kg in the early stage, while, in the late stage, the former decreased to 195.0 +/- 13.3 ml/minute/Kg and the latter increased to 0.615 +/0 0.054 m Hg/ml/minute/kg. The mean arterial blood pressure was decreased in both groups in the early stage but maintained above 100 mm Hg. Essentially, no hemodynamic changes were noted in the control group. These results confirm our hypothesis that an injection of live E coli can produce a hyperdynamic state in the early stage as well as hypodynamic state in the late stage, and that serial hemodynamic studies on bacteremia in rats can be done successfully using the thermodilution method.

Animals↗
PubMed1982

A study of oxidative phosphorylative activity and calcium-induced respiration of rat liver mitochondria following living Escherichia coli injection.

Mechanisms of subcellular dysfunction of the liver in sepsis are still obscure. The present study investigates changes in oxidative phosphorylative activity and calcium-induced respiration of rat liver mitochondria following live Escherichia coli injection (E coli, Serotype: 0--18. A 1.25--1.5 X 10(9)/100 gm body wt inoculum of E coli bacteria was injected via the tail vein, causing a 100% mortality rate within 24 hours after injection. In order to determine alteration of liver mitochondrial membrane permeability, serum ornithine carbamoyltransferase activity was measured following E coli injection. This activity increased ten to 100-fold over that of controls with time following injection. However, the yield of liver mitochondria from treated rats, estimated by the amount of collected mitochondrial protein and the recovery rate of succinate dehydrogenase activity in the final mitochondrial suspensions, was not significantly different from that of controls. Mitochondrial oxidative phosphorylative activity measured using glutamate as a substrate was enhanced throughout all period to death (P less than 0.01 at three and six hours, P less than 0.05 in the fatal stage) and was associated with concomitant increases in respiratory control ratios. Similar results were obtained using beta-hydroxybutyrate as a substrate. This enhancement was accompanied by an increase in 2-4-dinitrophenol-stimulated ATPase activity (160% at three hours and 130% in the fatal stage). Calcium-induced stimulation of mitochondrial respiration as well as initial calcium uptake rate linked to respiration, using glutamate as a substrate, were higher in liver mitochondria from rats with E coli treatment than in those of controls throughout all periods (P less than 0.01 or less). These results suggest the coexistence of hyperfunctioning as well as deteriorated mitochondria following lethal treatment with E coli.

3-Hydroxybutyric Acid↗