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Biomedical subjects

M Ikegami

Publications and source records attributed to M Ikegami.

At least 199 records · Page 11Linked to original sources
PubMed1994

Portal vein hemodynamics in cirrhotic patients with portal hypertensive gastropathy: an echo-Doppler study.

Portal hypertensive gastropathy is a major complication of cirrhosis. The aims of this study were to characterize portal vein hemodynamics and sympathetic nervous activity in cirrhotic patients with gastropathy. Forty-seven cirrhotics (mild gastropathy in 7) and 25 controls were included in this study. Portal vein hemodynamics was assessed by echo-Doppler, and sympathetic nervous activity by plasma adrenaline and noradrenaline concentrations. Portal blood flow was similar in cirrhotics and controls. However, the congestion index of the portal vein (calculated as the ratio of cross-sectional area and blood velocity) was significantly higher in the former than in the latter. Furthermore, the congestion index of the portal vein paralleled the severity of the gastropathy (ANOVA, p < 0.05). Plasma adrenaline and noradrenaline concentrations were higher in cirrhotics than in controls. However, there was no linear relationship between plasma adrenaline (ANOVA, NS) and noradrenaline (ANOVA, NS) concentrations and the severity of gastropathy. These results suggest a relative contribution of "passive congestion" in the pathogenesis of gastropathy.

Aged↗
PubMed1994

Cardiovascular responsiveness after isotonic exercise in cirrhotic patients: study on sympathoadrenergic and renin-angiotensin systems.

OBJECTIVES: The aim of this study was to evaluate cardiovascular responsiveness after isotonic exercise in cirrhotic patients. METHODS: Included were 11 cirrhotic patients and 10 age-matched normal subjects, who served as controls. Hemodynamic data were obtained on each subject before and after muscle exercise on a treadmill (7 metabolic units). Plasma noradrenaline concentration and plasma renin activity also were determined. RESULTS: In both groups, isotonic exercise increased heart rate and systolic arterial pressure, whereas diastolic arterial pressure was not modified. The increase in heart rate and systolic arterial pressure did not differ significantly between the two groups. Plasma noradrenaline concentration and plasma renin activity also were increased. The changes in plasma noradrenaline concentration and plasma renin activity was higher in cirrhotic patients than in controls (p < 0.05, p < 0.05), although the differences were not significant when calculated as a percentage. CONCLUSIONS: Cardiovascular responsiveness to isotonic exercise is almost intact in cirrhotic patients. However, supernormal activation of the sympathoadrenergic and renin-angiotensin systems is required to maintain cardiovascular homeostasis in these patients.

Adult↗
PubMed1994

Corticosteroids and fetal intervention interact to alter lung maturation in preterm lambs.

The relationship between cortisol infusion and time of fetal catheterization on postnatal lung function of prematurely delivered lambs was investigated with the hypothesis that the intervention of catheterization would alter fetal responsiveness to the maturational effects of corticosteroids. Fetal catheterization was performed on d 117 or on d 122 of gestation. Cortisol or saline control infusions were begun on d 126, with delivery 60 h later on d 128. The animals were ventilated for 1.25 h after delivery, and compliance, the ventilation efficiency index, labeled albumin leak into and out of the lungs, alveolar and lung saturated phosphatidylcholine and surfactant protein A were measured to evaluate lung performance and biochemical indicators of maturation. Cortisol improved compliance and ventilation efficiency and decreased labeled albumin recovery without changing alveolar saturated phosphatidylcholine or surfactant protein A in the animals catheterized at 122 d relative to 122-d saline-infused animals. However, the animals catheterized at 117 d and infused with saline were as mature as assessed by compliance and ventilation efficiency as the 122-d cortisol-treated animals. The 117-d cortisol-infused animals had significantly augmented lung function relative to either 117-d saline-infused or 122-d cortisol-treated lambs and were the only group that had increased alveolar surfactant protein A and lung saturated phosphatidylcholine pool sizes. This study demonstrates that the response of the fetal lung to a maturational agent such as cortisol is dependent on the history of previous fetal interventions.

Albumins↗
PubMed1994

[Intramucosal growth patterns of superficial colorectal carcinomas].

Intramucosal growth patterns of minute superficial colorectal carcinomas removed by endoscopic surgery were analyzed on these microscopic views by using two dimension morphometrical system. Superficial colorectal carcinomas were classified into 2 types based on endoscopic findings; superficial elevated type 21 cases and superficial depressed type 30 cases. Main factors determining growth pattern in mucosa depended on size in superficial elevated type and ratio of transmucosal growth in superficial depressed type. PG type and NPG type showed the same growth pattern in terms of ratio of transmucosal growth and mucosal thickness of central depressive area to the horizontal size. Accordingly, intramucosal growth patterns were different between superficial elevated type and superficial depressed type in minute lesions. And, PG type and NPG type could be included as superficial depressed type.

Carcinoma↗
PubMed1993

Reduced portosystemic hemodynamic responsiveness after orthostasis in patients with cirrhosis.

We studied portosystemic hemodynamic responsiveness after 1 min orthostasis in nine patients with cirrhosis and nine age-matched normal subjects. Orthostasis increased diastolic arterial pressure, which is a close indicator of arterial tone, in normal subjects (+17%, P < 0.01). In contrast, no significant change in diastolic arterial pressure was observed in patients with cirrhosis (-3%, NS). The increase in heart rate was less in patients with cirrhosis than in normal subjects (+15% vs +28%, P < 0.05). Orthostasis also decreased portal blood flow, which was assessed by an echo-Doppler flowmetry, in normal subjects (-27%, P < 0.01), but in patients with cirrhosis it was not modified (-3%, NS). Plasma noradrenaline concentration showed similar increase in both groups (normal vs cirrhosis; +61% vs +55%, NS). Although the change in plasma noradrenaline concentration was related with that in diastolic arterial pressure (r = 0.71, P < 0.05) and inversely with that in portal blood flow (r = -0.69, P < 0.05) in normal subjects, no such significant correlation was found in patients with cirrhosis. We conclude that (1) a reduced hemodynamic responsiveness to sympathetic stimulation exists on both systemic and portohepatic vascular beds and (2) such a blunted baroreflex function is probably located at the receptor or effector level in patients with cirrhosis.

Adult↗
PubMed1993

Effects of vasopressin and nicardipine on hemodynamics and liver function in patients with cirrhosis: comparison with vasopressin alone.

The effects of a combination of vasopressin and a calcium channel blocker (nicardipine) on portohepatic hemodynamics and liver function were compared with the effects of vasopressin alone in 18 patients with portal hypertension. Nine patients received 0.4 units/min of vasopressin and 9 patients received the same dose of vasopressin plus 0.3 mg/min of nicardipine for 40 min. Vasopressin plus nicardipine induced a significant reduction in both free portal venous pressure and the portal venous pressure gradient. These effects were similar to the changes with vasopressin alone (-14% vs. -16% in free portal venous pressure; -29% vs. -31% in portal venous pressure gradient). Vasopressin decreased both hepatic blood flow (-34%, P < 0.01) and intrinsic clearance of indocyanine green (-22%, P < 0.05). In contrast, these two parameters did not significantly change after vasopressin plus nicardipine (-8% and -3%, respectively). These results suggest that the addition of nicardipine improves hepatic impairment induced by vasopressin but causes no further reduction on portal pressure.

Aged↗
PubMed1993

Observer agreement and variability in measuring gastric mucosal blood flow by laser Doppler flowmetry in humans.

We evaluated the reliability (i.e. reproducibility and variability) in measuring regional gastric mucosal blood flow by laser Doppler flowmetry in a total of 32 subjects (12 normal subjects and 20 patients with cirrhosis). The measurements were performed in quadruplicate within 10 min by observer A (A1, A2) and B (B1, B2) using blind techniques. The intraclass correlation coefficient (Ri) was used to assess observer agreement. Overall, the level of intra- (Ri, 0.87 for A1 vs. A2 and 0.87 for B1 vs. B2) and interobserver agreement (0.86 for A vs. B) was excellent. In contrast, there was a higher observer variability assessed by coefficient of variation. Overall, the mean value of coefficient of variation was 12% (max. 35%) for A1 vs. A2, 12% (max. 35%) for B1 vs. B2, and 13% (max. 33%) for A vs. B. These results suggest that laser Doppler flowmetry, although the reproducibility may be clinically acceptable, seems to still be a subjective method for quantitation of gastric mucosal blood flow in humans. Therefore, studies using this method can only be acceptable when the changes that investigators intend to measure are significantly higher than the variability.

Adult↗
PubMed1993

The nucleotide sequence and genome structure of mung bean yellow mosaic geminivirus.

Complete nucleotide sequences of the infectious cloned DNA components (DNA 1 and DNA 2) of mung bean yellow mosaic virus (MYMV) were determined. MYMV DNA 1 and DNA 2 consists of 2,723 and 2,675 nucleotides respectively. DNA 1 and DNA 2 have little sequence similarity except for a region of approximately 200 bases which is almost identical in the two molecules. Analysis of open reading frames revealed nine potential coding regions for proteins of mol. wt. > 10,000, six in DNA 1 and three in DNA 2. The nucleotide sequence of MYMV DNA was compared with that of bean golden mosaic virus (BGMV), tomato golden mosaic virus (TGMV) and African cassava mosaic virus (ACMV). The 200-base region common to the two DNAs of each virus had little sequence similarity, except for a highly conserved 33-36 base sequence potentially capable of forming a stable hairpin structure. The potential coding regions in the MYMV DNAs had counterparts in the BGMV, TGMV and ACMV, suggesting an overall similarity in genome organization, except for absence of 1L3 in MYMV DNA 1. The most highly conserved ORFs, MYMV 1R1, BGMV 1R1, TGMV 1R1 and ACMV 1R1, are the putative genes for the coat proteins of MYMV, BGMV, TGMV and ACMV, respectively. MYMV 1L1 has also a high degree of sequence similarity with BGMV 1L1, TGMV 1L1 and ACMV 1L1.

Base Sequence↗
PubMed1993

Surfactant treatment effects on alveolar type II cell morphology in rabbit lungs.

The effects of exogenous surfactant administration on alveolar type II cells and the lung parenchyma were examined in adult rabbits. Natural surfactant was instilled into the left lobe of New Zealand White rabbits while the right lobe served as the control. Four hours post-instillation, the lungs were fixed by vascular perfusion. Surfactant instillation did not change alveolar type II cell size but was associated with a significant reduction in the volume fraction of lamellar bodies in type II cells (20.4% in control lobes compared with 11.9% in surfactant-treated lobes). The size distribution of lamellar body profiles was different in surfactant-treated lobes compared with control lobes, with a significant decrease in lamellar bodies > 0.8 microns in diameter and a twofold increase in lamellar bodies 0.2-0.4 microns in diameter. Composite body profile number was also increased by 87% (P < 0.05) after instillation of surfactant compared with control. Saline instillation decreased lamellar body volume fraction in type II cells but three times less than surfactant instillation. These observations are consistent with a strong stimulus for secretion of endogenous surfactant 4 h after surfactant instillation in normal adult rabbit lungs, whereas the increase in composite bodies is consistent with new lamellar body formation, probably from both de novo synthesized and exogenous natural rabbit surfactant. These observations confirm that the secretory and synthetic processes of alveolar type II cells are significantly affected by exogenous surfactant instillation.

Animals↗
PubMed1993

Lung function and surfactant distribution in saline-lavaged sheep given instilled vs. nebulized surfactant.

Adult sheep (35 +/- 3 kg) underwent saline lung lavage and 1.5 h of mechanical ventilation to induce acute lung injury. Animals received 100 mg lipid/kg body wt of tracheally instilled surfactant (Inst Surf) or either nebulized surfactant (Neb Surf) or nebulized saline (Neb Saline) and were killed 3 h later. Inst Surf and Neb Surf groups had significant improvements in oxygenation (P < 0.01) and peak inspiratory pressures (PIP) (P < 0.05) compared with pretreatment values. Improvements in oxygenation and PIP for Inst Surf animals were significantly greater than for Neb Surf animals (P < 0.05). Volumes of maximal pressure of quasi-static pressure-volume curves measured at the time the animals were killed were significantly greater for Inst Surf and Neb Surf animals than for animals given Neb Saline (P < 0.05). Alveolar recovery of exogenous surfactant was 100 times greater for Inst Surf animals (1,732 +/- 70 mg) than for Neb Surf animals (15.3 +/- 2.9 mg) at the time they were killed. Although there were no differences in exogenous surfactant distribution patterns at the lobar level between the two surfactant-treated groups, distribution histograms calculated for 10-g lung pieces revealed the Neb Surf animals had significantly more pieces within 25% of the mean value of 1.0 (42.7 +/- 6.9%) than did Inst Surf animals (20.8 +/- 5.5%) (P < 0.01). Exogenous surfactant therapy improved lung function with significantly different quantities of surfactant deposited in lung tissue for the two delivery methods evaluated.

Aerosols↗
PubMed1993

Lung responses to ultrasound-guided fetal treatments with corticosteroids in preterm lambs.

Maternal corticosteroid treatments augment lung function in the human preterm infant. However, not all fetuses respond, the response requires > or = 48 h of exposure, and multiple maternal doses expose the mother to potential risks. To evaluate the potential of direct fetal therapy, we used ultrasound to direct fetal intramuscular or intravascular injections of corticosteroids or saline in sheep and subsequently delivered the preterm lambs at 128 days gestational age to assess postnatal lung function. Relative to saline-injected controls, 0.5 or 2 mg/kg betamethasone given as a single intramuscular dose 48 h before delivery increased compliance and the efficiency of ventilation (as measured by an indicator that included ventilatory pressures and CO2 values) nearly twofold (P < 0.05). Lung volumes, measured from deflation pressure-volume curves, also increased (P < 0.05). However, the 2 mg/kg dose caused severe pulmonary interstitial emphysema in 5 of 13 lambs, suggesting adverse effects. An intravascular fetal dose of 12.5 mg/kg hydrocortisone or an intramuscular dose of 0.1 mg/kg betamethasone had no effect on postnatal lung function. In separate studies, the 2 mg/kg dose improved all indicators of lung function almost twofold after only 24 h of fetal exposure and delivery at 128 days gestational age (P < 0.01). There was a dose-dependent suppression of the postnatal cortisol surge in treated animals, although fetal treatment did not alter cord cortisol levels. Single-dose fetal hormone treatments can cause large and rapid improvements in postnatal lung function in preterm lambs.

Adrenal Cortex Hormones↗
PubMed1993

Treatment responses to surfactants containing natural surfactant proteins in preterm rabbits.

The in vivo function of surfactants reconstituted using natural surfactant lipid and protein constituents was evaluated in 27-day-gestation preterm rabbits. The animals were treated with protein-free surfactant lipids (LH-20), LH-20 + 5% SP-A, LH-20 + 1% SP-B, LH-20 + 1% SP-C, LH-20 + 5% SP-A + 1% SP-B + 1% SP-C (SP-ABC), natural sheep surfactant, or 4 ml/kg 0.45% NaCl (control) and then ventilated with tidal volumes of 8 ml/kg and 3 cm H2O positive end-expiratory pressure (PEEP). Ventilatory pressures (peak pressures minus PEEP) and dynamic compliances of the LH-20 + SP-C rabbits were greater (p < 0.01) than those of control, LH-20, and LH-20 + SP-A groups but lower (p < 0.05) than in the LH-20 + SP-B, LH-20 + SP-ABC, and sheep surfactant groups. Recoveries of intravascular labeled albumin in the lungs were comparable in the LH-20 + SP-B, LH-20 + SP-C, LH-20 + SP-ABC, and sheep surfactant groups and less (p < 0.01) than in LH-20 + SP-A rabbits, which had lower (p < 0.05) recoveries than did the control and LH-20 groups. The postventilation pressure-volume curves for LH-20 + SP-B and LH-20 + SP-ABC rabbits had significantly lower opening pressures, larger maximal lung volumes, and larger retained volumes on deflation relative to the LH-20 + SP-C, LH-20, and control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Physiologic responses and distribution of aerosolized surfactant (Survanta) in a nonuniform pattern of lung injury.

The underlying pattern of lung injury in patients with the adult respiratory distress syndrome (ARDS) may be nonuniform. The purpose of this study was to document whether a nonuniform pattern of lung injury influences treatment responses to aerosolized exogenous surfactant. Adult sheep underwent either total lung lavage (Tot Lav) or partial lung lavage (Par Lav) with saline, and they were subsequently mechanically ventilated for 90 min. Previous studies confirmed that this procedure induces acute lung injury. Partial lavage animals had their right upper lobe (RUL) protected from lavage by balloon obstruction of the RUL bronchus, and the occlusion was removed prior to the ventilatory period. Animals in both groups were then treated with either nebulized surfactant (Neb Surf) or nebulized saline (Neb Saline) for a further 180 min. PaO2, PaCO2, and peak inspiratory pressure significantly improved for the Tot Lav-Neb Surf animals compared with pretreatment values (p < 0.01). There were no significant changes for the other three groups (Tot Lav-Neb Saline, Par Lav-Neb Surf, Par Lav-Neb Saline). Lobar distribution of aerosolized [3H]surfactant in lung tissue revealed that Par Lav-Neb Surf animals had approximately 50% of the total surfactant recovered from the RUL compared with approximately 20% recovery from the RUL in the Tot Lav-Neb Surf group. The preferential deposition of exogenous surfactant in the RUL of the Par Lav-Neb Surf group resulted in significantly less surfactant deposited in other injured regions of the lung (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aerosols↗
PubMed1993

Changes in exogenous surfactant in ventilated preterm lamb lungs.

Preterm lambs were treated with either a surfactant from bovine lung (Survanta) or three synthetic surfactants (Exosurf), a 69:22:9 mixture of dipalmitoylphosphatidylcholine, phosphatidylglycerol, and palmitic acid prepared by heat annealing (Lipid Mixture 1) or with glass beads (Lipid Mixture 2). After 5 h of ventilation, large and small aggregate surfactant fractions were isolated from alveolar washes by centrifugation. SP-A was used as an indicator for the association of endogenous surfactant components with the treatment surfactants. The large aggregate fraction from Survanta-treated lambs contained more SP-A than did the fractions from the lambs treated with the other surfactants (p < 0.05). The surfactants used to treat the sheep and the large aggregate surfactants from alveolar washes increased compliances when tested in surfactant-deficient, immature rabbits, relative to that in control animals. The large aggregate fractions in alveolar washes from lambs treated with Survanta, Lipid Mixture 1, and Lipid Mixture 2 improved compliances in the preterm rabbits to a greater extent than did the surfactants used to treat the lambs. The small aggregate fractions were inactive as surfactants. The function of exogenous surfactant can be improved after exposure to the preterm lung. The improvement may result from the association of exogenous surfactant with components of endogenous surfactant.

Analysis of Variance↗
PubMed1993

Single dose versus two doses of betamethasone for lung maturation in preterm rabbits.

Most previous studies of induced lung maturation have used fetal exposures to multiple doses of hormones, and such treatments are associated with fetal growth retardation in rodents and rabbits. This study was designed to evaluate whether single-dose maternal corticosteroid treatments could induce lung maturation without causing fetal growth retardation. Lung maturation was evaluated in 27-d gestational age rabbits by measurements of lung function after preterm delivery and ventilation. Lung function was assessed by measurements of ventilatory requirements, responses to exogenous surfactant, measurements of the recovery of intravascular albumin in the lungs, and surfactant pool sizes. As demonstrated previously, 0.1 mg/kg betamethasone (1 mg = 2.13 mumol betamethasone) given 48 and 24 h before delivery caused both growth retardation (birth weight 20% lower than controls, p < 0.01) and lung maturation (improved compliance, decreased radiolabeled albumin recoveries) despite lower alveolar saturated phosphatidylcholine pool sizes (p < 0.05 versus controls). A single dose of 0.2 mg/kg betamethasone given 48 h before delivery had an equivalent effect on birth weight as the divided doses of 0.1 mg/kg betamethasone, with the only lung maturational effect being a decrease in recovery of labeled albumin in alveolar washes (p < 0.01). A single dose of 0.1 mg/kg betamethasone given 48 h before delivery decreased birth weight by 9.4% (p < 0.01 versus control) but had no effect on any of the lung maturation indicators. Fetal lung maturation caused by maternal corticosteroid is associated with global fetal growth retardation, and a single low dose of corticosteroid can cause growth retardation without inducing lung maturation.(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗