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Biomedical subjects

M Mito

Publications and source records attributed to M Mito.

At least 55 records · Page 3Linked to original sources
PubMed1994

Effects of low-power laser irradiation on multiple unit discharges induced by noxious stimuli in the anesthetized rabbit.

This study discusses the effects of low-power laser irradiation upon multiple unit discharges within a peripheral nerve that were induced by a noxious stimulation in anesthetized rabbits. Responding to a pinch stimulation of plantar skin, transitory increase of neuronal discharges was induced in the sural nerve. This was reduced within a minute, and persistent increases, which continued during a period of the stimulation, occurred. These increases became significantly smaller than the control value during a low-power laser irradiation that was applied to the exposed sural nerve distal to the recording site. These results suggested an inhibitory effect of low-power laser irradiation on the impulse conduction within a peripheral nerve. Possible analgesic effects of low-power irradiation are discussed.

Animals↗
PubMed1994

Is the biological artificial liver clinically applicable? A historic review of biological artificial liver support systems.

Hemoperfusion, hemodiafiltration, plasma exchange, and extracorporeal liver perfusion have already been adopted to treat patients with acute and chronic hepatic failure. However, the survival rate of patients with acute hepatic failure remains at approximately 30% and has not improved as expected. Current advances in biotechnology have opened the way for the development of a biological artificial liver, which is called the hybrid artificial liver because it consists of both biological and artificial materials. Isolated hepatocytes have been investigated for use in various types of hybrid artificial liver. In addition, the role of biomatrices, microcarriers, and the microencapsulation technique has been studied with respect to long-term maintenance of hepatocellular function and development of high-density culture systems for hepatocytes. Before clinical application of hybrid artificial liver support systems becomes possible, many problems have to be resolved, including large-scale preparation and long-term preservation of biomaterials, high-density and stable immobilization of biomaterials on artificial materials, control of immunological hazards, biocompatibility, safe transportation and sterilization of biomaterials, and the high cost. We review the history of biological artificial livers and discuss their future role.

Animals↗
PubMed1994

[Effect of RES on liver regeneration and survival after 90% partial hepatectomy].

In previous studies, 90% partial hepatectomy in the rat was invariably accompanied by 100% mortality within 40 hr. This paper describes the effect of enhanced reticuloendothelial system (RES) on liver regeneration after 90% partial hepatectomy. RES was activated using 5 K.E. of OK-432 injected intraperitoneally 24 hr before 90% partial hepatectomy. Ninety per cent of the liver mass was resected and rats were provided with tap water or 20% glucose orally and subcutaneously. Survival time was strikingly different. In rats provided with tap water only; 100% of rats died before 42 hr. In rats provided with 20% glucose; 44.2% of rats survived beyond 42 hr. In rats pretreated with OK-432 and provided with 20% glucose; 87.0% of rats survived beyond 42 hr. This regimen results in severe hypoglycemia and dead within 42 hr. When RES was activated before 90% partial hepatectomy, significantly higher blood glucose level was observed. BrdU labeling index was significantly higher in rats pretreated with OK-432 than in control rats. The results indicate that enhancement of RES before 90% partial hepatectomy provides acute metabolic support and enhancement of liver regeneration resulting in improved survival.

Animals↗
PubMed1994

Laparoscopic cholecystectomy from fundus downward.

Laparoscopic cholecystectomy from fundus downward (LCFD) is desirable when exposure of the cystic duct is difficult and hazardous. First the cystic duct and artery are exposed and clipped, and the artery is divided. Then removal of the gallbladder is started from fundus downward. After the gallbladder is dissected from the liver bed, the cystic duct is double clipped and divided. This approach affords better visualization of the cystic duct and common duct with less chance of common duct injury. Twenty-eight LCFDs were performed without complications, immediate or late. LCFD appears to be a safe procedure and does not compromise the retrograde method.

Adult↗
PubMed1994

The immunostimulant OK-432 enhances liver regeneration after 90% hepatectomy in rats.

The effect of reticuloendothelial system activation on liver regeneration after 90% hepatectomy was investigated. OK-432, a killed streptococcal preparation that increases reticuloendothelial system activity, was administered to rats before 90% partial hepatectomy. Pretreated rats showed marked improvement in long-term survival: 87% (18 of 23) survived beyond 42 hr, compared with only 44.2% (24 of 52) of controls (p < 0.05). Survival was determined by means of life-table analysis and regeneration response by means of bromodeoxyuridine labeling index of hepatic DNA. OK-432 pretreatment had significantly increased bromodeoxyuridine labeling index 18, 24, and 42 hr after partial hepatectomy (p < 0.05). The results indicate that reticuloendothelial system activation by OK-432 before 90% partial hepatectomy enhances liver regeneration and improves survival, but these factors may not be related. The improved survival may be because of less infection in macrophage-stimulated animals or more rapid clearance of hypotension-causing vasoactive compounds.

Adjuvants, Immunologic↗
PubMed1993

Defective signal transduction induced by thromboxane A2 in a patient with a mild bleeding disorder: impaired phospholipase C activation despite normal phospholipase A2 activation.

A patient with a mild bleeding disorder whose platelets responded defectively to thromboxane A2 (TXA2) was identified, and the mechanism of this dysfunction was analyzed. The platelets were defective in shape change, aggregation, and release reaction in response to synthetic TXA2 mimetic (STA2). When the platelet TXA2 receptor was examined with both a 125I-labeled derivative of a TXA2 receptor antagonist ([125I]-PTAOH) and [3H]-labeled TXA2 agonist ([3H]U-46619), the equilibrium dissociation rate constants (kd) and the maximal concentrations of binding sites (Bmax) of the platelets to both ligands were within normal ranges, suggesting that the binding capacity of their TXA2 receptor was normal. STA2 could not induce IP3 formation and intracellular Ca2+ mobilization, whereas these responses to thrombin were within normal ranges. GTPase activity was also decreased when the patient's platelet membrane was challenged with STA2. On the other hand, lysophosphatidylinositol formation, which is a direct indicator of phospholipase A2 (PLA2) activation, was found to be normal when the [3H]-inositol-labeled platelets were challenged with STA2. Thromboxane B2 (TXB2) was also produced in response to STA2. These results suggested that the abnormality in these platelets was impaired coupling between TXA2 receptor and phospholipase C (PLC) activation. Furthermore, it is also suggested that the activation of PLA2 and PLC are separable events in thromboxane-induced platelet activation.

Adult↗
PubMed1993

Large-scale cryopreservation of isolated dog hepatocytes.

This study aimed to develop methods for the large-scale preparation of hepatocytes from large animal livers and for the mass cryopreservation of isolated hepatocytes. Isolated hepatocytes were obtained from Beagle dogs weighing around 10 kg by collagenase digestion plus preperfusion with the Ca2+ chelator ethylene glycol bis N,N'-tetraacetic acid. The cell yield was 2.1 +/- 0.45 x 10(10)/liver with 90% viability by the trypan blue dye exclusion test, and the estimated cell yield was 72 +/- 13%. The optimal conditions were large-scale cryopreservation of dog hepatocytes were (i) a freezing rate of 1-10 degrees C/min, (ii) a dimethyl sulfoxide (Me2SO) concentration of 20% (final concentration: 10%), (iii) a cell density that did not exceed 10(8)/ml, and (iv) rapid thawing in a 37 degrees C water bath. The viability of preserved hepatocytes was 75 +/- 3.0% and the estimated recovery rate was approximately 50%. Preserved hepatocytes showed 20-50% of the metabolic activity of fresh cells, as assessed by ammonia and fructose loading tests, ATP content, and [14C]leucine uptake. Following culture after thawing, the morphological normalization of preserved cells was confirmed by light and electron microscopy.

Adenosine Triphosphate↗
PubMed1993

Cord dorsum potentials suppressed by low power laser irradiation on a peripheral nerve in the cat.

The effects of low-power helium-neon laser irradiation on the cord dorsum potentials (CDP) evoked by electrical nerve stimulation of a distal portion of exposed sural nerve were observed in unanesthetized decerebrate cats. These evoked CDP were significantly suppressed (25.6 +/- 2.5%, p less than 0.01) during low-power laser irradiation. It is suggested that the analgesic effects of low power laser irradiation is based on the decrease of ascending signals from the spinal cord to the higher central nervous system. The suppressive effect of low power laser irradiation upon the impulse transmission of nerve fibers is discussed.

Analgesia↗
PubMed1993

Encapsulated hepatocyte transplantation for the treatment of D-galactosamine-induced acute hepatic failure in rats.

Intraperitoneal transplantation of hepatocytes encapsulated with calcium alginate gel produced a marked improvement in the survival rate (75%) of rats with D-galactosamine (D-gal)-induced acute hepatic failure (AHF) when compared to the rate of 50% in rats undergoing free hepatocyte transplantation (HCTX). The viability of encapsulated hepatocytes was still 70% at 36 h after transplantation, and a gradual improvement in the serum glutamic oxaloacetic transaminase (GOT) and total bilirubin values was observed after encapsulated HCTX. Moreover, the arterial blood ketone body ratio (AKBR) remained within the normal range for the whole period of the investigation (60 h after transplantation), and histological investigation of the liver at 36 h demonstrated only slight inflammatory cell infiltrates without hepatocellular necrosis. The phagocytic index rose immediately after encapsulated HCTX and remained high subsequently. A prostaglandin inhibitor, indomethacin, blocked the improvement in survival rate, serum GOT, and AKBR of rats with D-gal-induced AHF despite encapsulated HCTX. Furthermore, no increase in the phagocytic index was observed. Indomethacin apparently suppressed the activation of Kupffer cells by encapsulated HCTX, which then failed to improve the survival of rats with D-gal-induced acute hepatic failure. Our results indicate that the reticuloendothelial system seems to play an important role in the efficacy of encapsulated HCTX in rats with D-gal-induced AHF.

Animals↗
PubMed1993

Combination therapy with rhGM-CSF and rhEpo for two patients with refractory anemia and aplastic anemia.

Because GM-CSF possesses burst-promoting activity (BPA) and megakaryocyte colony-stimulating activity (Meg-CSF) as well as stimulating activity on granulocyte-macrophage progenitors, and erythropoietin (Epo) has thrombopoietin-like activity, the combination therapy of GM-CSF and Epo seems to be more effective for stimulating erythropoiesis and thrombocytopoiesis in patients with pancytopenia. For this reason, the combination therapy of recombinant human GM-CSF (rhGM-CSF) and rhEpo was performed in two patients with refractory anemia (RA) and aplastic anemia (AA). Epo-unresponsive anemia was remarkably improved by adding rhGM-CSF to Epo and the effect lasted for 1 1/2 months in a patient with RA, but severe anemia occurred again immediately after the discontinuation of Epo. The neutralizing antibodies against GM-CSF were not demonstrated at the phase when anemia re-progressed in this patient. In a patient with AA, anemia and thrombocytopenia, which were refractory to previous administration of rhGM-CSF, responded to the combined administration of GM-CSF and Epo. Although the effects were maintained for 3 1/2 months, the anemia and thrombocytopenia became worse again after the administration of rhGM-CSF was changed from daily to every other day. These findings suggest the usefulness of combination therapy of GM-CSF and Epo for patients with pancytopenia.

Adult↗
PubMed1992

Hepatic support by hepatocyte transplantation in congenitally metabolic diseased rats.

Nagase analbuminemic rats (NAR), which lack albumin synthesis in the liver, underwent intrasplenic hepatocyte transplantation (HCTx), and the long-term effects were studied using functional and morphological examinations. Hepatocytes were isolated from congenic F344 rats with collagenase infusion, and 1 x 10(7) cells were injected into the spleen of 3-month-old NAR (n = 10). Serum albumin increased with time, reaching 53.9 mg/dl 14 months after HCTx, which was equivalent to 2.1% (maximum 4%) of serum albumin in normal rats. On the other hand, untreated NAR showed persistently low serum albumin levels (0.99 +/- 0.23 mg/dl at 10 months). According to immunostaining with anti-rat albumin antibody at 16 months after HCTx, hepatocyte grafts occupied 27-41% of the spleen area and weighed 120-420 mg, which was equivalent to 0.8-2.9% of a whole liver. Our study demonstrated that grafted hepatocytes can grow in the spleen with the ability to synthesize albumin. HCTx in NAR is a new experimental system to monitor the function and survival of grafted heptocytes without sacrificing the animals by measuring serum albumin levels. Certain manipulations to facilitate the growth of grafted hepatocytes are necessary to achieve sufficient hepatic support in HCTx.

Animals↗
PubMed1992

[A study of hepatocellular transplantation].

Clinical liver transplantation has been done for patients with irreversible hepatic diseases, but the shortage of donor livers from heart beating cadavers has become very serious. Hepatocyte transplantation requires no vascular anastomosis and donor hepatocytes are easy to obtain from living donors and easy to preserve for a long time. In the animal experiments, transplanted hepatocytes survived in the spleen for long periods of time, and cytochemical investigation revealed differentiated liver functions, such as gluconeogenesis, albumin synthesis, bilirubin conjugation. Intrasplenic transplantation of hepatocytes relieved congenital disorders of liver enzymes in rats. Moreover, transplanted hepatocytes re-composed normal cord structures with hepatic sinusoids in the spleen of rats. Hepatocytes could also be isolated from human cirrhotic livers by a multi-perfusion method, and the viability was almost 80%. After the success in transplantation of human hepatocytes into the spleen of athymic mice, 6 patients have undergone clinical trial of intrasplenic hepatocyte transplantation without any complications. In the future, the progress of gene manipulation techniques may make possible rapid growth of transplanted hepatocytes. Intrasplenic transplantation of isolated hepatocytes provides an in-vivo experimental model to study cellular growth and functions in detail.

Animals↗
PubMed1992

Stress platelets in normal individuals and patients with idiopathic thrombocytopenic purpura.

To test the hypothesis that stress platelets (SPs) described by Tong et al. in rats may be a parameter of young platelets in humans, we examined and characterized SPs in normal individuals and in patients with idiopathic thrombocytopenic purpura (ITP). Our results indicated that SPs comprise about 1.2% of the circulating platelets in normal individuals and 2.6% in ITP patients. The configuration of SPs as well as of various irregular forms of circulating platelets was found to be supported by synergism of both the platelet microfilaments and microtubules. SPs showed some segmentation, the degree of which was similar in normal individuals and ITP patients, and they underwent further segmentation during in vitro incubation, mainly promoted by microtubules, so that they sometimes appeared like discoid platelets in a chain. These observations suggest a new mode of production of discoid platelets in the circulation. Thus, identification and enumeration of SPs may be useful for evaluating thrombocytopoiesis in humans.

Adult↗