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Biomedical subjects

H Hirasawa

Publications and source records attributed to H Hirasawa.

At least 19 recordsLinked to original sources
PubMed1999

Effects of nitric oxide, light adaptation and APB on spectral characteristics of H1 horizontal cells in carp retina.

The spectral characteristics of cone-driven horizontal cells of H1 subtype (H1 HCs) receiving main synaptic input from red-sensitive cones were studied in light- and dark-adapted retinae of carp. The spectral sensitivity profile of H1 HCs in dark-adapted retinae was practically the same as the absorption spectrum of red-sensitive cones. Light-adaptation decreased the sensitivity preferentially in the short-wavelength (blue/green) region, resulting in a relative enhancement of the 617 nm peak. Application of nitric oxide (NO) donors, sodium nitroprusside (SNP) and S-nitrosoglutathione (SNOG or GSNO), or dopamine to dark-adapted retinae decreased the sensitivity preferentially in blue/green region, an effect similar to that of light-adaptation. Application of haemoglobin (Hb, an NO scavenger) or 2-amino-4-phosphonobutyrate (APB, a metabotropic glutamate receptor agonist), to light-adapted retinae increased the sensitivity preferentially in the blue/green region, an effect similar to dark-adaptation. The photoresponses of H1 HCs were univariant in dark-adapted retinae as well as Hb-treated light-adapted retinae. In light-adapted retinae with normal Ringer, however, the univariance did not hold. These results suggested that the photoresponses of H1 HCs to short-wavelength stimuli contain a depolarising (sign-reversing) component, which can be activated by light-adaptation or application of NO and dopamine, and inactivated by dark-adaptation or deprivation of NO or application of APB.

Adaptation, Ocular↗
PubMed1999

[Evaluation of severity in shock].

Shock is defined as organ failure due to the disturbance of perfusion in vital organs and various humoral mediators. Multiple organ failure (MOF) is a typical pathophysiologic condition subsequent to shock. Therefore the severity of shock should be evaluated based on the severity of organ failure. Recent advances in our understanding of the pathophysiology of shock have demonstrated that organ failure is the summation of cellular dysfunction in vital organs caused by tissue hypoxia and various humoral mediators. We have developed and clinically applied the cellular injury score (CIS) as a severity scoring system in patients with shock and resultant MOF. The CIS is derived from the scoring of three parameters of intracellular metabolism: the arterial ketone body ratio (AKBR); osmolality gap (OG); and blood lactate level. The CIS correlates well with the degree of organ failure and mortality rate in patients with MOF and accurately indicates the severity of shock in individual patients. Our results suggest that the CIS is a useful scoring system based on the pathophysiology of shock, not only to predict the outcome and evaluate the severity in patients with shock and MOF but also to predict the development of MOF subsequent to shock.

Biomarkers↗
PubMed1998

Possible association of missense mutation (Gly[-63]Glu) of the neurotrophin-3 gene with Alzheimer's disease in Japanese.

Several lines of evidence have suggested a possible involvement of neurotrophic factors in the pathogenesis of neurodegenerative disease. We examined whether a missense mutation (Gly[-63]Glu) of the neurotrophin-3 (NT-3) gene is associated with Alzheimer's disease (AD) in a Japanese sample of 123 patients and 215 controls. We found that homozygotes or heterozygotes for the mutated type (Glu[-63]) were significantly more common among the patients than the controls (P = 0.013, odds ratio 1.77, 95% CI 1.12-2.79). The mutated type was more frequent among the patients than the controls (P = 0.011, odds ratio 1.63, 95%CI 1.11-2.38). This association between NT-3 and AD was more prominent among those who did not carry the epsilon4 allele of the apolipoprotein E gene than those who carried the epsilon4 allele. Our results suggest that the Glu(-63) allele of the NT-3 gene by itself or another mutation nearby which would be in linkage disequilibrium to the mutation is a risk factor for AD.

Adult↗
PubMed1998

Cellular injury score for multiple organ failure severity scoring system.

BACKGROUND: Cellular Injury Score (CIS) is an index of cellular injury, being calculated from three parameters of intracellular metabolism: arterial ketone body ratio, osmolality gap, and blood lactate. METHODS: The usefulness of CIS as a severity scoring system for patients with multiple organ failure was prospectively evaluated in 157 consecutive patients with MOF (58 survivors, 99 nonsurvivors). RESULTS: CISs in nonsurvivors were significantly higher compared with those in survivors throughout the clinical courses. CIS was significantly correlated with the number of failing organs and mortality rate. The optimal cutoff point of CIS from receiver operating characteristics curve analysis was 4 for the maximal value during the clinical course. The changes in CIS well reflected the severity of injury in survivors and nonsurvivors who died within 2 weeks. CONCLUSION: CIS could be a useful index for mortality risk prediction and is potentially applicable as a severity scoring system for individual patients with MOF.

3-Hydroxybutyric Acid↗
PubMed1998

Cerebral blood volume in the sleep measured by near-infrared spectroscopy.

We investigated the relationship between hemodynamic changes in the cortex measured by near-infrared spectroscopy (NIRS) and the polysomnographic changes during sleep. Four healthy male volunteers participated in the study. Near-infrared spectroscopy measuring and polysomnographic recordings were done simultaneously during sleep. In many case, oxy-hemoglobin (oxy-Hb) decreased and deoxy-hemoglobin (deoxy-Hb) increased during the transition from wakefulness to sleep, and oxy-Hb increased toward deep sleep. Oxy-Hb and deoxy-Hb had larger fluctuations during REM sleep than those during non-REM sleep. During REM sleep, oxy-Hb often showed a lower level and deoxy-Hb showed a higher level than those during the preceding and following non-REM sleep.

Adult↗
PubMed1998

[Stress ulceration related bleeding (SURB) in intensive care unit].

Today in critically ill patients the frequency of major stress ulceration related bleeding (SURB) has decreased. However this syndrome has not totally disappeared and its mortality remains very high once it develops. It's high mortality seems to be due to the facts that pathogenesis of SURB is mucosal ischemia resulting from splanchnic hypoperfusion in the setting of various insults in the ICU and that SURB reflects gut failure as a part of multiple organ failure (MOF). Therefore in the prevention of SURB, the optimization of tissue oxygen metabolism in splanchnic area must be considered in addition to the common prophylactic measures such as decreasing or neutralizing gastric acid and protecting gut mucosa.

Histamine H2 Antagonists↗
PubMed1998

[Critical care for organ failure].

We retrospectively studied the critical care regimen for multiple organ failure (MOF) in 141 surgical MOF patients treated in the intensive care unit of Chiba University Hospital between January 1988 and April 1998. Patients with gut failure received parenteral instead of enteral nutrition for various reasons such as concomitant ileus. Of the patients with respiratory failure. 138 were placed on a ventilator and 6 received percutaneous cardiopulmonary support. Continuous hemodiafiltration (CHDF) was performed in 98 patients with renal failure. Plasma exchange was carried out in 13 patients with liver failure. Of these patients, 62 (44%) survived. Colloid osmotic pressure was used as an indicator for fluid therapy. For prophylaxis against bacterial translocation, we performed selective digestive decontamination. Recently blood purification methods, particularly CHDF, have become common in the critical care setting. CHDF is efficacious not only as continuous renal replacement therapy but also as a humoral mediator modulator and is currently the first-choice method for blood purification in critical care. In conclusion, there have been many advances in the critical care of patients with organ failure. Multidisciplinary treatment, including artificial support for failing organs, is necessary for the survival of these patients.

Cardiopulmonary Bypass↗
PubMed1997

Efficacy and limitation of apheresis therapy in critical care.

Apheresis therapy such as plasma exchange and plasma adsorption has become therapeutic tools in critical care. The indications for apheresis therapy in ICU patients include fulminant hepatic failure, thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS), autoimmune disease, and sepsis. During the past 11 years, 150 patients with various kinds of critical illnesses were treated with apheresis therapy in our ICU, and the overall survival rate was 50%. Apheresis therapy is especially useful in the treatment of a patient with fulminant hepatic failure because liver transplantation is seldom performed in Japan; therefore, the patient should be treated with artificial liver support. When plasma exchange is performed on the critically ill, continuous hemodiafiltration should be performed simultaneously to overcome the adverse effects of plasma exchange such as hypernatremia, metabolic alkalosis, and abrupt changes in colloid osmotic pressure and to enhance the removal rate of the causative middle molecular weight substances of hepatic failure or hepatic coma.

Autoimmune Diseases↗
PubMed1997

Quantitative EEG correlates of normal aging in the elderly.

To clarify the effect of normal aging on the EEG in the elderly, relative EEG power and coherence were studied in 68 elderly subjects (age range 61-90 years) as well as in 20 young subjects (age range 23-38 years). Relative beta power was significantly higher in the elderly subjects, while no significant differences were seen among the elderly groups. Therefore it may be assumed that EEG power in the centrooccipital region among the normal elderly remains almost unchanged. Also, age had no effect on interhemispheric coherence. However, intrahemispheric coherence was found to decrease with age in all bands almost linearly. Thus, intrahemispheric coherence is a more sensitive indicator of normal aging than relative power.

Adult↗
PubMed1997

[Polysomnographic changes in normal human aging].

We studied the effect of normal aging on human sleep. The subjects were 105 volunteers between the ages of 10 and 97 years. Polysomnography was done for three consecutive nights. Data collected on the second and third nights were scored according to the manual of Rechtschaffen and Kales. The sleep efficiency and the time percent of stage REM, stage 3, and stage 4 decreased gradually with age. The time percent of wakefulness stage 1. and stage 2 increased gradually with age. Stepwise regression analysis showed that sleep efficiency and the time percent of stage 3 + 4 were related to age. Sleep in the elderly is said to be characterized by more frequent awakenings, longer periods of light sleep (stage 1 + 2), shorter periods of deep sleep (stage 3 + 4) and REM sleep. The present results suggest that polysomnographic changes can be found even in young adults.

Adolescent↗
PubMed1996

Blood purification for prevention and treatment of multiple organ failure.

Blood purification has been applied conventionally as an artificial kidney or artificial liver in the management of patients with multiple organ failure (MOF), and most blood purifications have been performed intermittently. Recent advances in medical engineering made it possible to perform such blood purifications continuously (i. e., 24 hours a day, 7 days a week if necessary) even in critically ill patients. This modality is referred to as continuous renal replacement therapy (CRRT) or continuous blood purification (CBP). Among many kinds of CBP, continuous hemodiafiltration (CHDF) is most useful for management of MOF, as it can be performed without serious or hazardous side effects, and improvement can be expected with it. Recently, CHDF and polymyxin B immobilized endotoxin adsorption columns were used for the prevention or treatment of MOF, with the expectation that such therapy can be effective as a countermeasure against the pathophysiologic causes of MOF. Our data and that of others clearly indicate that continuous blood purification, such as with CHDF and endotoxin adsorption, can remove or decrease the blood levels of humoral mediators, including proinflammatory cytokines, and can improve tissue oxygenation, especially oxygen consumption (VO2) among critically ill patients including those with MOF. Blood purification is also useful in the careful management of fluid, electrolytes, and acid-base balance and for the removal of metabolic wastes. Blood purification is now considered to be one of the basic therapeutic tools of critical care, equal to nutritional support with total parenteral nutrition and respiratory support without a ventilator.

Critical Care↗
PubMed1996

[Methicillin-resistant Staphylococcus aureus infection in the Akita University Hospital: surveillance and microbiology data].

In order to control the nosocomial infections by methicillin-resistant Staphylococcus aureus (MRSA) in the Akita University Hospital, the systematic surveillance for MRSA-infection has been done since October in 1991. We reviewed MRSA-isolation numbers, MRSA-detected patient numbers, risk factors of nosocomial infection and patient's basic diseases with the data of a total 336 cases, and then examined the microbiological characteristics of MRSA strains which had been isolated in our hospital in 1986 approximately 1994. The results obtained are as follows; 1) MRSAs were isolated at 13 per month on the average and the detection rate was 0.81 to 1,000 inpatients per day. 2) MRSAs were isolated more in the surgical ward. 3) Patients with 0 year old and more than 60 years old were more infected. 4) MRSA was isolated more from the immunocompromised patients with underlying diseases such as malignant tumors but half of the diseases were not affected by MRSA. 5) Seventy percent of patients had the risk factors of MRSA-transmission such as surgical operation and IVH-cathetering. 6) All isolates of MRSA strains in our hospital showed type II in coagulase type analysis and resistance to minocycline and ofloxacin. 7) It was suggested that one strain expanded throughout the hospital by several DNA analysis with the mecA gene in MRSA. These surveillance and microbiology data will be useful for our nosocomial mecA gene in MRSA. These surveillance and microbiology data will be useful for our nosocomial infection control.

Adolescent↗
PubMed1996

[Acute renal failure following surgical insult].

It has been claimed that acute renal failure (ARF) following surgical insult was mainly due to the reduction in renal blood flow, especially in renal cortical blood flow. Recent studies, however, pointed out that the majority of the surgical ARF developed due to prolonged SIRS (systemic inflammatory response syndrome) and that those patients developed ARF as a part of multiple organ failure (MOF) complicating other organ failures such as acute respiratory failure. It has been also pointed out that variety of humoral mediators including pro-inflammatory cytokines play a major role in the development of ARF following SIRS. Therefore, the management of such ARF should include some countermeasures against humoral mediators. Various blood purifications have been applied in the management of the patients with ARF. Recently continuous blood purifications got their popularity in the management of the critically ill. Continuous hemodiafiltration (CHDF) has been reported to be applied without any hazardous side effect on the most critically ill patients. CHDF can not only support failing renal function but also can effectively remove causative humoral mediators from the blood stream of the patients. Therefore the CHDF is the first choice blood purification in the management of the ARF patients following surgical insults.

Acute Disease↗
PubMed1996

[Prevention and treatment of postoperative septic MOF and DIC and efficacy of blood purification].

Pathophysiologic concept of SIRS has been proposed for the better management of postoperative severe infection and septic MOF, and the concept has been found to be very useful. It is very important to identify the high risk SIRS patients of the development of septic MOF and to treat those patients aggressively to prevent the development of septic MOF. In the prevention and treatment of septic MOF, the blood purification has been found to be very effective. Among the blood purifications, continuous blood purification, such as continuous hemodiafiltration (CHDF) should be chosen for this purpose. CHDF has been claimed to be very effective to removal of causative humoral mediators from the blood stream. The concept of DIC has been changed recently and the concept of DII (disseminated intravascular inflammation) should be applied instead of DIC, since the main feature of this pathologic condition is the damage of endothelial cells due to extensive systemic inflammation.

Disseminated Intravascular Coagulation↗