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Biomedical subjects

H Sakai

Publications and source records attributed to H Sakai.

At least 217 records · Page 12Linked to original sources
PubMed2000

Molecular dimensions of Hb-based O(2) carriers determine constriction of resistance arteries and hypertension.

The effect of molecular dimension of hemoglobin (Hb)-based O(2) carriers on the diameter of resistance arteries (A(0), 158 +/- 21 microm) and arterial blood pressure were studied in the conscious hamster dorsal skinfold model. Cross-linked Hb (XLHb), polyethylene glycol (PEG)-conjugated Hb, hydroxyethylstarch-conjugated XLHb, polymerized XLHb, and PEG-modified Hb vesicles (PEG-HbV) were synthesized. Their molecular diameters were 7, 22, 47, 68, and 224 nm, respectively. The bolus infusion of 7 ml/kg of XLHb (5 g/dl) caused an immediate hypertension (+34 +/- 13 mmHg at 3 h) with a simultaneous decrease in A(0) diameter (79 +/- 8% of basal value) and a blood flow decrease throughout the microvascular network. The diameter of smaller arterioles did not change significantly. Infusion of larger O(2) carriers resulted in lesser vasoconstriction and hypertension, with PEG-HbV showing the smallest changes. Constriction of resistance arteries was found to be correlated with the level of hypertension, and the responses were proportional to the molecular dimensions of the O(2) carriers. The underlying mechanism is not evident from these experiments; however, it is likely that the effects are related to the diffusion properties of the different Hb molecules.

Animals↗
PubMed2000

Susceptibility to lipopolysaccharide of cholestatic rat liver produced with bile duct ligation: assessments of the mitochondrial glutathione pool and the effects of N-acetylcysteine.

We investigated whether rats with obstructive jaundice produced with bile duct ligation for 2 weeks are more susceptible to the additional stress of lipopolysaccharide (LPS) administration than sham-operated rats and also examined the effects of N-acetylcysteine (NAC) on LPS stimulation in rats with bile duct ligation. The effects of LPS on the mitochondrial glutathione pool and on oxidative stress of polymorphonuclear leukocytes were investigated in cholestatic rats. Serum concentrations of alpha-glutathione S-transferase showed that lipopolysaccharide stimulation caused more severe hepatocellular injury in cholestatic rats than in sham-operated rats. In addition, concentrations of mitochondrial reduced and oxidized glutathione and hepatic adenosine triphosphate showed that LPS stimulation decreased mitochondrial function more in cholestatic rats than in sham-operated rats. Intraperitoneal administration of NAC for 2 weeks significantly improved mitochondrial function and decreased hepatocellular injury. However, the oxidative stress of polymorphonuclear leukocytes that had infiltrated hepatic tissue was increased by NAC. The present results indicate that the cholestatic liver is susceptible to the additional stress of LPS, that NAC suppresses the adverse effects of LPS in cholestatic livers, and that the oxidative stress of polymorphonuclear leukocytes is not significantly involved in mitochondrial dysfunction or hepatocellular injury in this model.

Acetylcysteine↗
PubMed2000

Clinical investigation on pulmonary metastasis of head and neck carcinomas.

OBJECTIVE: To establish a treatment strategy for pulmonary metastases, we clinically investigated the characteristics of distant metastases from head and neck carcinomas. METHODS: In 636 head and neck carcinomas, the pathophysiology of distant metastases was investigated by charts, roentgenographies, computed tomographies and scintigraphies. RESULTS: Of the squamous cell carcinomas, oropharyngeal tumors were most highly metastatic, followed by lower gingiva, floor of the mouth, maxillary sinus, and tongue. In distant metastases, 30 (4.7%), 5 (0.8%), and 7 (1.1%) metastasized to the lungs only, lungs and other organs, and organs excluding the lungs, respectively. In pulmonary metastases, the right, left and both lungs were involved in 18, 5, and 8 patients, respectively, although details were not obtained for 4 patients. Pulmonary metastases consisted of 1, 2, and 3 or more tumors in 18, 4, and 6 patients, respectively. Diffuse cancer cell infiltration was observed in 3 patients. Of the 42 patients with distant metastases, 12 patients died of progressive pulmonary metastases, and 5 of these patients manifested only 1 pulmonary lesion throughout life. However, the metastatic pulmonary tumors were controlled surgically or conservatively in 3 patients. CONCLUSION: These results indicate that distant metastases from head and neck carcinomas involve the lungs most frequently and that chemoimmunotherapy and surgical removal of the metastatic tumors are recommended when indicated.

Adult↗
PubMed2000

Keratoacanthoma developing on a pigmented patch in incontinentia pigmenti.

Cutaneous manifestations of incontinentia pigmenti (IP) have classically been described as three sequential stages: an initial vesicobullous stage, a verrucous stage and a stage of swirled pigmentation. Verrucous lesions tend to last longer than vesicobullous eruptions, often persisting until 1 year of age. However, adult patients with verrucous lesions are rare. We report a case of keratoacanthoma with marked dyskeratosis on a pigmented patch in a 20-year-old woman. This tumor, like subungual keratotic tumors of IP, might have been developed as one of the late manifestations of the disease.

Adult↗
PubMed2000

Distorted trachea in patients with chronic obstructive pulmonary disease.

BACKGROUND AND OBJECTIVES: We evaluated the size and configuration of the trachea in patients with chronic obstructive pulmonary disease (COPD; n = 35) on high-resolution computed tomography (HRCT) images and compared them with those of healthy volunteers (n = 24). METHODS: Using a newly developed computed method for analyzing the digital data of HRCT, the size and configuration of the trachea were automatically evaluated. RESULTS: The size of the trachea of the COPD subjects was the same as that of the control subjects; however, the configuration was more distorted in the COPD patients. There was no difference in the tracheal index (TI), which is the ratio of the coronal to the sagittal length, between these two groups; however, the ratio of the short to the long radius (SR/LR) was significantly smaller in the COPD group than in the control group. There was a significant correlation between SR/LR and airflow limitation as assessed by pulmonary function tests in the COPD group. CONCLUSIONS: The SR/LR is a better index of tracheal deformity than the classical TI. This deformity is not a consequence secondary to hyperinflation or emphysematous change of the lung, because the low attenuation area of the lung was not correlated with SR/LR.

Aged↗
PubMed2000

Computed tomographic measurements of airway dimensions and emphysema in smokers. Correlation with lung function.

Chronic obstructive pulmonary disease (COPD) is characterized by the presence of airflow obstruction caused by emphysema or airway narrowing, or both. Low attenuation areas (LAA) on computed tomography (CT) have been shown to represent macroscopic or microscopic emphysema, or both. However CT has not been used to quantify the airway abnormalities in smokers with or without airflow obstruction. In this study, we used CT to evaluate both emphysema and airway wall thickening in 114 smokers. The CT measurements revealed that a decreased FEV(1) (%predicted) is associated with an increase of airway wall area and an increase of emphysema. Although both airway wall thickening and emphysema (LAA) correlated with measurements of lung function, stepwise multiple regression analysis showed that the combination of airway and emphysema measurements improved the estimate of pulmonary function test abnormalities. We conclude that both CT measurements of airway dimensions and emphysema are useful and complementary in the evaluation of the lung of smokers.

Adult↗
PubMed2000

Developmental changes in cerebrospinal fluid concentrations of monoamine-related substances revealed with a Coulochem electrode array system.

The relationship between age and cerebrospinal fluid concentrations of monoamine-related substances, including kynurenine, were investigated using a Coulochem electrode array system, to clarify developmental changes in monoamine-related substances in the human central nervous system. In neurologically normal children, significant inverse correlations with age were observed for the cerebrospinal fluid concentrations of 5-hydroxytryptophan, 5-hydroxyindole-acetic acid, kynurenine, homovanillic acid, 3-methoxy-4-hydroxyphenyl glycol, and 3-O-methyl-dopamine. The concentrations of their precursors, tryptophan and tyrosine, were not related to age. This is the first comprehensive study revealing developmental changes in monoamine-related substances including their precursors and metabolites.

Age Factors↗
PubMed2000

A common downstream signaling activity of osteoclast survival factors that prevent nitric oxide-promoted osteoclast apoptosis.

Treatment with NO-releaser NOC18 significantly promoted apoptosis in murine osteoclast-like cells, with a transient increase in caspase-3-like protease activity. In contrast, the apoptosis was protected against by caspase inhibitors, most efficiently with the broadly acting caspase specific inhibitor z-Asp-CH2-DCB, indicating involvement of multiple caspases in progression of the apoptosis. Among osteoclast survival factors examined, calcitonin completely protected against morphologically defined-apoptosis and the increase of caspase-3-like protease activity. The effect of calcitonin was mimicked by treatment of cells with (Bu)2cAMP and forskolin, and abolished by protein kinase-A inhibitor H-89. Independently from the PKA activation, colony stimulating factor-1, interleukin-1beta and the receptor activator of NF-kappaB ligand also protected against the apoptosis but were less effective than calcitonin. All survival factors investigated inhibited conversion of procaspases-3 and -9 to their mature forms in the cells. Thus, downstream antiapoptotic signaling activity from each factor overlapped in inhibition of caspases. However, how this was attained seemed to be different from each other. Typically, only colony stimulating factor-1 up-regulated expression of endogenous caspase inhibitor protein, X-linked inhibitor of apoptosis (XIAP), in the osteoclast-like cells.

Animals↗
PubMed2000

Subacute tuberculous pericarditis with fibroelastic constriction diagnosed upon pericardiectomy.

A patient with subacute pericarditis showed no evidence suggesting tuberculosis until pericardiectomy was performed because of hemodynamic deterioration. The excised pericardium had a rubbery fibroelastic consistency; histologically, there were granulomatous changes characteristic of tuberculosis. Although tuberculous pericarditis is a difficult diagnosis, this case illustrates the diagnostic and therapeutic importance of early pericardiectomy before myocardial inflammatory infiltration occurs together with end-stage pericardial fibrosis and calcification.

Diagnostic Techniques, Cardiovascular↗
PubMed2000

Heart transplantation in children in foreign countries with reference to medical, transportation, and financial issues.

Heart transplantation is increasingly becoming accepted worldwide as therapy for end-stage heart failure not only in adult patients but also in pediatric practice. The new law in Japan for organ transplantation from brain-dead patients was established on 16 October 1998, but there is no definite law or protocol for brain death in children under the age of 6 years and children less than 15 years of age cannot become donors. These facts make organ transplantation from the cadavers of neonates, infants and young children almost impossible in Japan, even though there are children who need heart or heart-lung transplantation. The present authors have to date transferred 8 patients to the USA or Germany for heart transplantation: 4 successfully underwent heart transplantation, but 4 died during the waiting period overseas. There are many things to consider; not only the medical problems involved in transportation, but also the financial issues when transferring patients to other countries. This report details the experience with the 8 cases that were transferred overseas for heart transplantation, and highlights the problems that need to be considered.

Child↗
PubMed2000

Acetylcholine-induced smooth muscle contraction of intrapulmonary small bronchi is augmented in antigen-induced airway hyperresponsive rats.

Smooth muscle responsiveness of intrapulmonary small bronchi obtained from repeatedly antigen-challenged rats was compared with that from control animals to determine whether smooth muscle contractility of peripheral airways is augmented by such repeated challenge. In intact (non-permeabilized) smooth muscles of intrapulmonary bronchi, the acetylcholine (ACh)-induced contractile response was significantly augmented in the repeated challenge group, although 60-mM K+-induced contraction was within the normal level. In beta-escin-permeabilized muscles, no significant difference between groups was observed in the Ca2+-induced contractile responses. Thus, augmented ACh-induced contraction of intact intrapulmonary small bronchial smooth muscle might be, at least in part, due to an enhanced ACh-mediated Ca2+-sensitizing signal.

Acetylcholine↗
PubMed2000

Three cases of cat scratch disease diagnosed by indirect immunofluorescence antibody assay and/or polymerase chain reaction of 16S rRNA gene of Bartonella henselae.

Three suspected cases of cat scratch disease were diagnosed by indirect immunofluorescence antibody assay and/or polymerase chain reaction. Patient 1 was a 10-year-old female who presented swelling of the right axillary [corrected] lymph nodes with pain and fever. She kept a kitten, and many scratches were observed on her both legs and dorsum manus. Antibody titers against Bartonella (B.) henselae were 1:32 for IgM 3 weeks after the onset of the symptoms and 1:64 for IgG 8 weeks after the onset. The DNA for 16S rRNA type I of B. henselae was detected from the blood sample obtained 3 weeks after the onset of symptoms by polymerase chain reaction for the first time in Japan. Patient 2 was a 22-year-old female veterinary student with a cat scratch at the bottom of her neck by a male kitten. She developed a papule at the scratch, slight fever, and neck pain. Although both Bartonella-specific IgG and IgM antibodies were negative before the scratch, the IgG antibody titer rose to 1:512 14 weeks after the onset. B. henselae was isolated from the kitten and its DNA found to be for 16S rRNA type I by PCR. Patient 3 was a 23-year-old female veterinary student with a cat scratch on her left forearm. A small reddish papule developed on the scratch, and she experienced swelling of the left axillary [corrected] lymph node and pain. Both the IgG and IgM antibodies against B. henselae were negative before the cat scratch, and the IgG titer rose significantly to 1:128 and 1:1,024 in 2 and 5 weeks, respectively, after the onset of the symptoms.

Adult↗
PubMed2000

Force-induced osteoclast apoptosis in vivo is accompanied by elevation in transforming growth factor beta and osteoprotegerin expression.

The mechanism controlling the disappearance of osteoclasts from bone surfaces after bone resorption in vivo is largely unknown. This is because there is no suitable experimental system to trace the final fate of osteoclasts. Here, we used an experimental model of tooth movement in rats to show that preexisting osteoclasts disappeared from the bone surface through apoptosis during a force-induced rapid shift from bone resorption to formation. On the distal alveolar bone surface of the maxillary molar in growing rats, many mature osteoclasts were present. When light tensional force was applied to the bone surface through an orthodontic appliance, these preexisting osteoclasts gradually disappeared. One day after the application of force, about 24% of the osteoclasts exhibited apoptotic morphology and the proportion of apoptotic cells was increased to 41% by day 2, then decreased afterward. These changes were undetectable on the control distal alveolar bone surface, which is free from tensional force. As shown by in situ hybridization, a marked increase in transforming growth factor beta1 (TGF-beta1) and osteoprotegerin (OPG) messenger RNA (mRNA) was observed in the stretched cells on the tensioned distal bone surface, simultaneously with the loss of osteoclasts. Both of these factors are known to have a negative effect on osteoclast recruitment and survival. As early as 2 days after force application, some of these stretched cells were identified as cuboidal osteoblasts showing intense signals for both factors. Our data suggest there may be a sequential link in tensional force applied on the bone lining cells, up-regulation of TGF-beta1/OPG, and disappearance of osteoclasts.

Acid Phosphatase↗
PubMed2000

Reversibility of serum NH3 level in a case of sudden onset and rapidly progressive case of type 2 citrullinemia.

A 48-year-old male presented with an acute change in mental status due to a marked elevation of plasma NH3 and was diagnosed with citrullinemia with amino acid analysis of blood. Hemodialysis and hemodiafiltration were performed, but serum chemical analysis did not show any improvement which led us to terminate dialysis following intensive care for 3 days. Surprisingly, NH3 level had decreased by 6 days after admission, coinciding with normalization of the size of the pupils. Since spontaneous remission had never been discussed, we discuss this relatively rare, but clinically significant entity with regard to its acute phase management and its potential reversibility.

Ammonia↗
PubMed2000

Hepatic artery pseudoaneurysms in a patient treated for miliary tuberculosis.

A 70-year-old woman with fever was admitted to our hospital. She was diagnosed as miliary tuberculosis and treated with antituberculous drugs. After seven weeks of therapy, she developed a sudden sharp upper abdominal pain and shock. Angiography of the celiac artery showed two hepatic artery pseudoaneurysms with extravasation. The hemorrhage was successfully stopped by microcoil embolization. The clinical course suggested that miliary tuberculosis had caused the pseudoaneurysms. Although aneurysms rarely occur as a complication of miliary tuberculosis, they should be diagnosed as early as possible because of the high rate of rupture and associated high mortality rate.

Aged↗
PubMed2000

Mobilization of intracellular Ca(2+) by thromboxane A(2) does not affect Ca(2+)-activated K(+) channels in rat colonic crypt cells.

The effects of 9,11-epithio-11,12-methano-thromboxane A(2) (STA(2)), a stable thromboxane A(2) analogue, and carbachol on colonic Ca(2+)-activated K(+) channels were studied. In indo-1-loaded single cells in isolated rat colonic crypts, both STA(2) (0.1 microM) and carbachol (10 microM) transiently increased intracellular free Ca(2+) concentration ([Ca(2+)](i)) by 136 and 155 nm, respectively. In whole-cell current-clamp experiments of the colonic crypt cells with Cl(-)-free solutions, carbachol (10 microM) hyperpolarized the cell by 19.7 mV, while STA(2) (0.1 microM) did not affect the membrane potential. In the isolated colonic mucosa that was permeabilized mucosally by a monovalent ionophore nystatin in the presence of a serosally directed K(+) gradient, carbachol (10 microM) transiently elicited K(+) current, but STA(2) (0.1 microM) did not. These results indicate that STA(2) elevates [Ca(2+)](i) in rat colonic crypt cells but does not activate basolateral Ca(2+)-activated K(+) channels.

Animals↗
PubMed2000

[Three-dimensional imaging of hepatic and intrahepatic portal veins with helical CT: determination of optimal volume of contrast medium by intravenous injection using MIP technique].

In this study, the optimal volume of contrast medium in the liver for three-dimensional (3D) imaging of the hepatic and portal veins by helical CT were determined by intravenous injection using the MIP technique. In the 48 cases examined, CT images of the liver were obtained following the administration of contrast medium (90, 120, or 150 ml and 1.0 <, < or = 1.5 ml; 1.5 <, < or = 2.0 ml; 2.0 <, < or = 2.5 ml or 2.5 <, < or = 3.0 ml/kg) for determination of the optimal volume. The mean body weight of the patients was 59 kg. Contrast medium (Iopamidol 300 mgl/ml) was injected at a rate of 3 ml/sec, and scanning was initiated 70 sec after the beginning of injection. Images were obtained throughout the entire liver using 5-mm collimation. MIP images were graded from poor to excellent based on their visualization of the hepatic vessels. Images produced with 120 ml of contrast medium presented excellent images of hepatic vessels, superior to those produced with 90 ml (hepatic vein: p < .001, portal vein: p < .001). Images produced with 2.0 <, < or = 2.5 ml/kg of contrast medium presented excellent images of the portal vein, superior to those produced with 1.5 <, < or = 2.0 ml/kg ml (p < 0.05). It is evident from the present data that a contrast medium volume of more than 120 ml or 2.0 <, < or = 2.5 ml/kg is sufficient for three-dimensional imaging of hepatic vessels. These images may be a useful diagnostic tool in patients with hepatic disease.

Contrast Media↗