Biomedical subjects

H Nagata

Publications and source records attributed to H Nagata.

At least 199 records · Page 11Linked to original sources

PubMed1994

[Prostaglandin E1 suppresses hypersecretion of antidiuretic hormone induced by surgical stress].

We studied the effects of prostaglandin E1 (PGE1) on decrease in urine output during surgery in patients for radical total hysterectomy under general anesthesia. The patients were randomly allocated into two groups. Five patients (control group) were given no PGE1 and served as control. Seven patients (PGE1 group) were given continuous infusion of PGE1 at a rate of 50 ng.kg-1 x min-1 after first measurement (baseline). Urine output in control group decreased by 68%, but in PGE1 group it did not change from the baseline. Urine sodium and fractional sodium excretion in control group decreased, but in PGE1 group they increased. Creatinine clearance increased from the baseline in both groups. Antidiuretic hormone in control group increased by 30%, but in PGE1 group decreased by 53%. Plasma renin activity, angiotensin I, angiotensin II in both groups increased, and those in the control group were higher than those in PGE1 group. However, aldosterone in the control group was lower than that in PGE1. These results indicate that diuretic effect of PGE1 could be mediated by suppression of antidiuretic hypersecretion induced by surgical stress, inhibition of the action of antidiuretic hormone, and suppression of sodium and water reabsorption in proximal and distal tubules. Also, PGE1 did not directly stimulate renin-angiotensin system.

Adult↗

PubMed1994

Attenuating effect of antithrombin III on the fibrinolytic activation and microvascular derangement in rat gastric mucosa.

The roles for the fibrinolytic activation and disorder of coagulation in formation of gastric ulcer induced by microvascular derangement were investigated. The rat stomach was exposed and repeated electrical stimuli (RES) were applied on the small arterial wall close to the lesser curvature to induce mucosal microcirculatory disturbances. The level of tissue-type plasminogen activator (t-PA), a key enzyme for fibrinolytic activity, in the regional blood of the stomach was significantly elevated immediately after RES. At 5 min after RES, the leakage of FITC-labeled albumin and thrombus formation in the mucosal microvasculature were visually demonstrated by using an intravital microscopic system. At 30 min, hemorrhagic erosions and linear ulcers were observed in the gastric mucosa. Pretreatment with human antithrombin-III (AT-III) in the range of 0.1-10 U/kg dose-dependently attenuated both the fibrinolytic activation and microvascular alteration promoted by RES. Human AT-III also prevented RES-induced gastric mucosal injury. Thrombin inhibitory activity in the gastric vein decreased (69.0 +/- 2.1%) just after RES, and further reduced at 30 min (47.7 +/- 5.3%). The present study suggests a hypothesis that human AT-III has a preventive effect on the gastric mucosal hemorrhagic changes via attenuating the fibrinolytic activation and subsequent microcirculatory disturbances.

Animals↗

PubMed1994

[Analysis of dysarthria in amyotrophic lateral sclerosis--MRI of the tongue and formant analysis of vowels].

To evaluate dysarthria in patients with ALS, we used MRI (gradient rephasing echo method) and compared it with the computed acoustic analysis. Five ALS male patients of progressive bulbar palsy type and five normal male were asked to phonate the five Japanese vowels, /a/./i/./u/./e/./o/. MRI of the sagittal tongue and vocal tract was obtained by the gradient rephasing echo method (0.2 Tesla, TR:30 ms, TE:10 ms, FA 25 degrees C, Hitachi). We could clearly visualize the change of tongue shape and the narrow site of the vocal tract for each vowel phonation. In normal subjects, the tongue shape and the narrow site of the vocal tract were distinguishable between each vowel, but unclear in ALS. Acoustic analysis showed that the first formant frequency of /i/./u/ in ALS was higher than normal and the second formant frequency of /i/./e/ in ALS was significantly lower than normal. The discrepancy from the normal first, second and third formant frequency for each vowel of ALS was most seen in /i/./e/. It was speculated that /i/ and /e/ were the most disturbed vowels in ALS. The first and second formant frequency of vowel depends on the tongue shape and the width of the oral cavity. Therefore the results of the acoustic analysis in ALS indicated poor movement of tongue in /i/./u/./e/ and were compatible with the findings of the sagittal tongue MRI. The sagittal view of the tongue in the gradient rephasing echo MRI and the acoustic analysis are useful in evaluation dysarthria in ALS.

Aged↗

PubMed1994

Characterization of coaggregation and fibrinogen-binding by Porphyromonas gingivalis.

We have examined whether the adhesin of Porphyromonas gingivalis which aggregates Streptococcus oralis contributes to its fibrinogen-binding. Various properties of coaggregation between P. gingivalis and S. oralis were compared with those of fibrinogen-binding to P. gingivalis cells. The coaggregation activity was measured by a turbidimetric method and the fibrinogen-binding activity was determined by using 125I-fibrinogen. Both the activities showed maximum values in the pH range from 5.0 to 6.0 and they were inhibited by arginine and lysine. Heating treatment of P. gingivalis 381 cells at 75 degrees C abrogated the activities. However, treatment of P. gingivalis 381 cells with proteinase K considerably reduced the fibrinogen-binding activity but not the coaggregation activity. Metal ions such as Zn2+ and Cu2+ inhibited the coaggregation activity but enhanced the fibrinogen-binding activity. The results also indicated that P. gingivalis strains 381, ATCC 33277 and SU-3 showed relatively higher activities both in coaggregation and fibrinogen-binding, whereas P. gingivalis strains W83, 51 and 165 showing lower fibrinogen-binding activity than P. gingivalis 381 did not coaggregate with S. oralis ATCC 9811. These findings suggest that coadhesin of P. gingivalis with S. oralis is not be associated with its fibrinogen-binding.

Adhesins, Bacterial↗

PubMed1993

Inhibition of coaggregation between Porphyromonas gingivalis and Streptococcus oralis by fibrinogen fragments.

The localization of regions of fibrinogen that inhibit coaggregation between Porphyromonas gingivalis and Streptococcus oralis was investigated. The coaggregation was inhibited by A alpha and gamma chains, but not by B beta chain. The inhibitory activity of fragment D was more potent than that of fragment E. Some cyanogen bromide-treated fragments isolated from A alpha and gamma chains including the NH2-terminal 148-207 amino acid residues of A alpha chain (A alpha 148-207) and gamma 1-78 showed inhibitory activities. A alpha 148-207 was further digested with lysyl endopeptidase. A alpha 158-176 and A alpha 192-206 which contained four and two arginine residues, respectively, retained the inhibitory activities. When the arginine residues of these two peptides were modified by phenylglyoxal, the inhibitory activities were much reduced. These findings suggest that the arginine residues of some specific regions of fibrinogen may play an important role in the inhibition of the coaggregation.

Amino Acid Sequence↗

PubMed1993

Antithrombotic effect of an anti-glycoprotein IIB/IIIA antibody in primate lethal thrombosis.

We investigated the antithrombotic effect of anti-glycoprotein (GP) IIb/IIIa antibody in a primate model of lethal thrombosis. Eight monkeys were injected intravenously with an anti-CD9 antibody (MALL13). They died within 5 min and displayed severe thrombocytopenia. Histological examination showed multiple platelet thrombi in the pulmonary microvasculature, but no thrombi in the liver, kidneys, or spleen. In contrast, monkeys pretreated with an anti-GPIIb/IIIa antibody (NNKY1-32) at 30 min before MALL13 administration did not die, and the thrombocytopenia in these animals did not develop as rapidly or become as severe. These results suggest that the antiCD9 antibody caused lethal pulmonary thrombosis in vivo, and that pretreatment with the anti-GPIIb/IIIa antibody was able to prevent this thrombosis.

Animals↗

PubMed1993

Oxyradical generation from leukocytes during endotoxin-induced microcirculatory disturbance in rat mesentery--attenuating effect of cetraxate.

By using the intravital microscope equipped with digital imaging processor, we investigated the granulocyte-mediated oxidative burst during the endotoxin-induced microvascular derangement in rat mesentery. The leukocyte behavior after the injection of acridine orange was detected by using a silicon-intensified target camera, the erythrocyte velocity was measured by using a high-speed video camera system, and the luminol-dependent photoemission was visualized by an ultrasensitive photon-counting camera in lipopolysaccharide (LPS)-treated microvascular beds. At 60 min after the LPS administration, a significant leakage of FITC-labeled albumin was observed along mesenteric venules under a fluorescence microscopy. The number of sticking leukocytes increased in association with the decrease in erythrocyte velocity after starting the LPS infusion. The luminol-dependent chemiluminescence in microvascular beds gradually increased over that recorded prior to LPS exposure and was fourfold higher 60 min after the start of LPS infusion. The distribution of the photoemission clearly corresponded to the venular endothelium, to which leukocytes adhered. In blood samples taken from the mesenteric vein at 60 min after the LPS administration, a decrease in the number of granulocytes and increases of total and individual chemiluminescence activities were observed. These results suggest that LPS induces oxidative burst from granulocytes on the venular endothelium. Cetraxate, an inhibitor of proteases including plasmin, significantly inhibited the leukocyte activation and prevented alterations in microvascular hemodynamics induced by LPS in vivo, whereas it had no effect on the LPS-induced oxyradical generation from adherent leukocytes in vitro. The present study demonstrates that proteases such as plasmin may play an important role in the pathogenesis of endotoxin-induced microvascular disturbances.

Animals↗

PubMed1993

Protein-losing enteropathy caused by mesenteric vascular involvement of neurofibromatosis.

A 44-year-old man with neurofibromatosis suffered from severe diarrhea and progressive hypoproteinemia. Enteric protein loss was confirmed by an alpha 1-antitrypsin clearance test. An x-ray study showed irregular mucosa in the distal segment of the ileum. Protein loss has subsided after ileocecal resection. Laparotomy and radiological examinations failed to demonstrate neurofibroma or other tumors in the abdomen. The resected ileum revealed marked edema of the wall and a pseudomembranous enteritis-like appearance in the luminal surface. Microscopically, lymphatic vessels in the intestinal wall were dilated. Marked thickening of the intima with spindle cell proliferation was observed in the mesenteric arteries and veins. This finding is consistent with vascular changes in neurofibromatosis. These vascular changes in the mesentery due to neurofibromatosis may cause protein-losing enteropathy by altering the hemodynamic state and microvascular permeability in the intestine.

Adult↗

PubMed1993

Mathematical modeling of fetal organ growth using the Rossavik growth model: II. Adrenal gland.

Growth of the fetal adrenal gland has been monitored by measurements of the circumference (AGC) and area (AGA) of the adrenal gland from 16 to 40 weeks menstrual age. Growth curves for these parameters have been determined using a Rossavik growth curve models [P = c(t)k + s(t)]. R2 values of 86.2 and 91.1% were obtained for AGC and AGA, respectively. Variability analysis indicated a progressive increase in variability with menstrual age for these two parameters. Variability data were used with the growth curve models to determine standard curves for AGC and AGA. These standard curves provide a superior means for evaluating the adrenal growth in the fetus and the fetal status in utero in high-risk pregnancies.

Adrenal Glands↗

PubMed1993

The effects of immobilization of long segments of the spine on the adjacent and distal facet force and lumbosacral motion.

Long levels of spinal instrumentation and fusion are common in surgery for spinal deformity. The effect on the remaining mobile segments is not well understood. The changes in lumbar facet loading and lumbosacral motion were evaluated as the number of immobilized levels increased. Four fresh canine cadaveric spines from T6 to sacrum were used. Lumbosacral motion was measured with an instrumented spatial linkage device, and facet loads were measured at L1, L4, and L7 using a strain gauge technique. Lumbosacral motion and facet loading were significantly increased (P < 0.05) after immobilization of proximal segments, and the amount of the increase was dependent on the number of immobilized segments (P < 0.05). This indicates that immobilization of long segments of the spine influences the remaining mobile segments by increasing the load and motion not only at the immediately adjacent segment but also at the distal segments.

Animals↗

PubMed1993

Mechanical stimulation by toothbrushing increases oxygen sufficiency in human gingivae.

We studied the immediate effect of mechanical stimulation with a toothbrush on oxygen sufficiency in human gingivae. Teeth were brushed with a modified Bass technique at various forces (100, 200, and 300 g) for various times (5, 10, and 30 s). Hemoglobin (Hb) oxygen saturation was measured before and intermittently for 60 min after brushing, by non-invasive tissue reflectance spectrophotometry. Hb oxygen saturation increased within a few min after brushing and then slowly returned to the initial level. Toothbrushing at 200 g for 10 s caused the longest-lived increase in Hb oxygen saturation; saturation remained about 6% above the baseline level for more than 25 min. Before brushing, Hb oxygen saturation was significantly lower in inflamed gingivae than in healthy gingivae (p < 0.05). After brushing of inflamed gingivae, the Hb oxygen saturation almost reached the level measured in healthy gingivae before brushing. These findings suggest that stimulation with a toothbrush increases oxygen sufficiency in both healthy and inflamed gingivae.

Adolescent↗

PubMed1993

Nitric oxide mediates vasoactive effects of endothelin-3 on rat mesenteric microvascular beds in vivo.

In order to clarify whether the vasoactive effects of endothelin-3 (ET-3) on microvessels are associated with the endothelium-derived relaxing factor (EDRF) in vivo, the authors examined the effects of L-NG-monomethyl arginine (L-NMMA), an analog of L-arginine, on low-dose ET-3 induced hemodynamic changes in the mesenteric microcirculation of male Wistar rats. The intravital observation revealed that ET-3 100 pM induced a remarkable and periodic vasoconstriction in arterioles, and the constriction was sustained for approximately fifteen minutes. No remarkable change was observed in the microvessels after the superfusion of 1 pM ET-3. Superfusion of 1 pM ET-3 with 100 microM L-NMMA elicited the vasoconstriction in arterioles, and the arteriolar diameter recovered to the control level within ten minutes in spite of continuing the superfusion. The vasoconstriction induced by low-dose ET-3 with L-NMMA was suppressed by the additional superfusion of 200 microM L-arginine. The present study suggests that the recovery of arteriolar diameter after the ET-3-induced constriction may be mediated by nitric oxide at least in the early phase.

Animals↗

PubMed1993

[Influence of epiphyseal cartilages on bone resorption of fetal rat femora].

We developed a facile method for studying bone resorption using fetal rat femur by labelling the bone with 45Ca in vitro. We found that cartilages stimulated the bone resorption of a shaft which was obtained by cutting off both distal and proximal cartilages from the femur. When the shaft was co-cultured with the cartilages isolated by a 0.4-microns microporous membrane in the same Transwell, the bone resorption of the shaft was increased. This finding suggests that the stimulation of bone resorption by the cartilages is not a result of recruitment of osteoclasts or the precursor cells from the cartilages. Indomethacin (10(-6) M) failed to influence the bone resorbing activity of the cartilages. The bone resorbing activity in the supernatant obtained from the cartilage-culture was decreased by heating. The bone resorbing activity of the supernatant did not remain in the lipid-extract or the pronase-digested supernatant, but was present in a fraction whose molecular weight was greater than 50,000. These results collectively suggest that the cartilages produce a bone resorption-stimulating factor(s) which is water-soluble, is a non-prostanoid material, contains protein and has a molecular weight greater than 50,000.

Animals↗

PubMed1993

[Effects of protease inhibitors and protein synthesis inhibitors on cartilage tissue-dependent bone resorption].

We studied bone resorption of fetal rat femora in association with cartilage tissue. Some protease inhibitors, e.g., E-64, pepstatin A, phosphoramidon, amastatin, bestatin, foroxymithine, did not influence the bone resorption, but some serine protease inhibitors such as PMSF, TLCK, TPCK and elastatinal inhibited the bone resorption at 10(-5) M, 10(-4) M, 10(-4) M, 10(-4) M, respectively. A conditioned medium, obtained from cartilage tissue-cultured medium in the presence of 10(-4) M TPCK, which was then excluded from the medium by dialysis after the culture, stimulated the bone resorption. Cycloheximide (0.1 to 10 micrograms/ml) and puromycin (0.3 to 30 micrograms/ml) inhibited the cartilage tissue-dependent bone resorption. A A transient treatment of the femora with cycloheximide (3 micrograms/ml) for a day inhibited the bone resorption, but after the treatment, in the absence of cycloheximide, the femora gradually recovered the bone-resorbing activity. The conditioned medium, obtained from cartilage tissue-cultured medium in the presence of cycloheximide (3 micrograms/ml), which was then excluded from the medium by dialysis after the culture, failed to influence the bone resorption. These findings collectively suggest that cartilage tissue produces a bone resorption-stimulating factor(s) which is a serine protease or contains the protein as an inactive, latent form and then a certain serine protease converts it to an active form.

Animals↗

PubMed1993

Prenatal evaluation and obstetrical management of fetuses at risk of developing lung hypoplasia.

The aim of this study was to measure the fetal lung area of normal human fetuses using ultrasound and them to test the predictive values of a nomogram in the identification of fetal lung hypoplasia. A nomogram for ultrasound-measured fetal lung area were constructed from 264 normal fetuses from 17 to 39 weeks of gestation. In 19 cases running the risk of developing lung hypoplasia, the sensitivity, specificity, and positive and negative predictive values of lung area measurements below the mean -2 SD were 75%, 100%, 94% and 100%, respectively, with total lung area showing a significant relation to the combined lung weight (Y = -1.05 + 2.06 X, r2 = 0.88). These results indicate that lung area measured by ultrasound is a good indicator of lung weight, and this nomogram of lung area may be useful in evaluating lung growth prenatally, as well as in the direct obstetrical management of fetuses at risk of developing lung hypoplasia.

Female↗

PubMed1993

[Efficacy of the treatment of gastric cancer as neo-adjuvant chemotherapy of 48 hour continuous intravenous infusion of 5-fluorouracil (5-FU) with leucovorin (LV)].

A 51-year-old female with inoperable gastric cancer and with infiltration of pancreatic tail diagnosed by abdominal CT was treated with leucovorin (LV) and 5-fluorouracil (5-FU). The regimen was: LV 30 mg/body/24 hr prior to 5-FU 1,000 mg/m2/day for 48 hrs. This treatment was repeated 6 times. After treatment, the size of tumor decreased so that the patient was able to be operated (Total gastrectomy with partial distal pancreatico-splenectomy). During the treatment, patient showed no side effect except for slight nausea. This neo-adjuvant chemotherapy might be a recommendable treatment of advanced gastric cancer.

Adenocarcinoma↗

PubMed1993

[Anesthetic management for cesarean section and clipping of aneurysm in a pregnant woman with ruptured cerebral aneurysm].

We report an anesthetic management for Cesarean section and clipping of aneurysm in a pregnant woman with a subarachnoidal hemorrhage secondary to a ruptured cerebral aneurysm. Anesthesia was induced with thiopental, vecuronium and sevoflurane, and maintained with sevoflurane (0.5-1%) before the delivery. Apgar score at 1 min was 1, but after 30 min her activity became almost normal. After the delivery, anesthesia was maintained with fentanyl for clipping surgery, because sevoflurane may inhibit uterine contraction and increase bleeding from the uterus after the delivery. We also infused prostaglandin E1 continuously at a rate of 50-70 ng.kg-1.min-1 to control arterial blood pressure and to maintain good contraction of the uterus during clipping surgery. We conclude that prostaglandin E1 is useful as a vasodilator after delivery because prostaglandin E1 contracts the uterus.

Adult↗

PubMed1993

Further histological observations on popliteal lymph nodes after interruption of the afferent lymphatic vessels.

Lymphatic vessels afferent to the popliteal nodes in young adult rats and guinea pigs were interrupted at the lowest edge of the popliteal fossa, and regressive changes in the nodes occurring 4 to 16 or 18 weeks after surgery were re-examined histologically. In the rat, some popliteal nodes were drained by lymphatic channel(s) from the tail. After surgery, the popliteal nodes without lymphatic channel(s) from the tail underwent regression of all their constituent deep cortical units and also the peripheral cortex comprising lymph follicles, until at 18 weeks, the lymphoid organization of the node reached a minimal level. On the other hand, in popliteal nodes having a lymphatic channel from the tail, some deep cortical units and the overlying peripheral cortex underwent hypotrophy, leaving the remaining units and their overlying peripheral cortex little affected. In the guinea pig, the treated nodes underwent progressive atrophy and ultimately became rudimentary, or even vanished, after 16 weeks. Treated rudimentary nodes were composed largely of stromal cells only, and these were replaced to a various extent by fat. The present results are discussed in relation to complete and incomplete inhibition of the afferent lymph flowing into the surgically treated nodes.

Animals↗