Biomedical subjects

J Sato

Publications and source records attributed to J Sato.

563 records · Page 32Linked to original sources

PubMedDate not supplied

A model of transient oscillatory pressure-flow relationships of canine airways.

In a previous paper (27) we developed a lumped parameter model of canine pulmonary airway mechanics featuring airway wall elasticity, gas inertance, and laminar and turbulent gas flow. The model accurately accounted for the steady-state pressure-flow data we obtained during sinusoidal cycling of the lung following a period of apnea. In the present paper, we extend the model to account for the transient decrease in the amplitude of the trans-airway pressure swings that we observed immediately following the apnea, which we have shown to be due to a vagally mediated bronchodilatation reflex. The extended model accounts for this transient in terms of a sudden change in airway smooth muscle tone acting on the viscoelastic properties of the airway wall and tissues mechanically coupled to it. Consequently, this model is able to temporarily store a volume of gas in the conducting airway tree as its volume changes cyclically with that of the whole lung. This means that the flow entering the airway tree from the trachea at any instant (V) is not precisely equal to that entering the alveoli (Valv) even when the gas is considered incompressible. We found that assuming V to be equal to Valv can lead to errors in estimating respiratory tissue impedance of as much as 10%. However, tissue hysteresivity remained almost unaffected, suggesting that the hysteretic properties of respiratory system tissues and airway wall are well matched.

Animals↗

PubMedDate not supplied

Effects of glimepiride on in vivo insulin action in normal and diabetic rats.

To evaluate the effects of glimepiride on insulin action in peripheral tissues, we investigated insulin-induced glucose uptake in normal and diabetic rats using the euglycemic clamp procedure (insulin infusion rates: 6 and 30 mU/kg/min). Normal rats: After oral administration of glimepiride (0.1 mg/kg/day; NG) or saline (NC) for 2 weeks, euglycemic clamp procedures were performed. During submaximal hyperinsulinemia (620 +/- 35 pmol/l, mean +/- S.E.M.), metabolic clearance rates of glucose (MCR) in NG were significantly higher than in NC (25.1 +/- 2.1 vs. 18.3 +/- 1.2 ml/kg/min, P < 0.05). During maximal hyperinsulinemia (5235 +/- 270 pmol/l), MCRs in NG were higher than in NC, but there was no statistical significance (43.3 +/- 2.8 and 38.9 +/- 2.8). Diabetic rats: streptozotocin-induced diabetic rats were divided into four groups, GI (glimepiride treatment, 0.1 mg/kg/day p.o., with insulin, 5 U/day s.c.), SI (insulin alone), SG (glimepiride alone), and SC (saline). MCRs in the four groups were similar during 6 mU/kg/min clamps. During 30 mU/kg/min clamps, MCRs in GI were significantly higher than those in SC, SG or SI (23.4 +/- 2.8 vs. 12.2 +/- 1.9 and 8.9 +/- 0.8, P < 0.01, and vs. 17.4 +/- 1.5, P < 0.05). Although MCRs in SI tended to be higher than in SC, there was no significant statistical difference between these two groups. These results suggest that glimepiride enhances insulin action in peripheral tissues, and that glimepiride treatment with insulin improves the insulin resistance observed in streptozotocin-induced diabetic rats.

Administration, Oral↗

PubMedDate not supplied

Clinico-neuropathological study of incontinentia pigmenti achromians--an autopsy case.

A clinico-neuropathological study of a Japanese girl with hypomelanosis of Ito, one of the neurocutaneous syndromes, is reported. At birth, typical skin hypopigmentation on the trunk and a hypopigmented streak on the left lower extremity were noted. From 2 months of age, intractable convulsions occurred and EEG showed various abnormalities. Psychomotor development was severely retarded and she died of pneumonia at the age of 13 months. Neuropathological examination revealed brachycephaly, micropolygyria and asymmetry of lateral ventricles. A histological examination showed a disarray of cortical lamination, and the existence of nerve cells in the white matter. These pathological findings showed a migration anomaly during brain maturation.

Autopsy↗

PubMedDate not supplied

L-arginine availability is not limiting for nitric oxide generation from recombinant endothelial nitric oxide synthase.

L-arginine (L-Arg) may be limiting for inducible nitric oxide synthase (NOS) activity and under certain circumstances, such as increased concentrations of a NOS inhibitor, may also be limiting for endothelial NOS activity. It is unknown if L-Arg is limiting for recombinant eNOS activity in the vascular wall after adenoviral mediated gene transfer. Our aim was to examine, if L-Arg is limiting for recombinant eNOS activity in the normal or atherosclerotic vessel wall. Rings of rabbit aorta from chow or cholesterol fed animals were transduced with adenovirus vector encoding eNOS (AdeNOS) or beta-galactosidase (AdbetaGal). After 24 h, transgene expression was confirmed and vasomotor studies were performed in the absence or presence of L-Arg. During maximal contractions to phenylephrine (10(-5) M), L-Arg (3 mM) was added to the organ chamber for 30 min. Subsequently, relaxations to acetylcholine during half-maximal contractions were obtained. In the chow- and cholesterol-fed animals, relaxations were significantly enhanced in the NOS and NOS + L-Arg groups compared to the betaGal and betaGal + L-Arg groups. There was no difference between NOS and NOS + L-Arg or betaGal and betaGal + L-Arg rings from chow- or cholesterol-fed animals. While gene transfer of eNOS enhances endothelium-dependent vasorelaxation in the normal and atherosclerotic vessel wall, L-arginine is not limiting for recombinant eNOS activity.

Animals↗

PubMedDate not supplied

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) in children undergoing high-dose chemotherapy and autologous peripheral blood stem cell transplantation.

The incidence of SIADH (the syndrome of inappropriate antidiuretic hormone secretion) was analyzed retrospectively in 43 children who received marrow-ablative chemotherapy before autografts with peripheral blood stem cells for lymphoid malignancies. SIADH was documented in three children (ages 3, 13, and 13 years) who received chemotherapy, which included high-dose methyl 6-[3-(chloroethyl)-3-nitrosoureido]-6-deoxy-alpha-D-glucopyranoside (MCNU) and cyclophosphamide, under a concomitant overhydration protocol. SIADH was manifested as frequent vomiting in two patients and as generalized seizure in one. Hyponatremia (< 125 mEq/L), hypo-osmolality (< 260 mOsm/kgH2O), and continued urinary excretion of sodium (> 30 mEq/L) were used to diagnose SIADH in these three patients. All signs and symptoms subsided within 24 hours either by fluid restriction alone (n = 1) or by supportive care including anticonvulsant and D-mannitol, or hyperhydration with saline plus 5% glucose and diuretic. None of the patients died. Careful monitoring of the serum sodium level, as well as the osmolality of plasma and urine, should be incorporated into the patient management protocol for this type of high-dose chemotherapy.

Adolescent↗