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Biomedical subjects

N Asakawa

Publications and source records attributed to N Asakawa.

52 records · Page 3Linked to original sources
PubMed1989

Effect of short-chain fatty acids on pancreatic exocrine secretion in calves aged 2 weeks and 13 weeks.

Effects of short-chain fatty acids on pancreatic exocrine secretion were studied under anesthesia in calves within 2 weeks of age (2-wks calves) given only whole milk and milk replacement and in which rumen fermentation has not begun yet, and in calves at 13 weeks of age (13-wks calves) weaned at 40 days of age and in which rumen fermentation has already begun. Basal rate of juice flow and protein concentration and amylase activity in pancreatic juice under basal condition were significantly lower in the 2-wks calves than those in the 13-wks calves. Intravenous administrations of acetate, propionate and butyrate stimulated pancreatic juice secretion and protein and amylase output in both groups of calves. Those responses were increased with increasing carbon number in the molecule of fatty acids. Although the response of amylase output (/kg of body weight) in the 2-wks calves was significantly less than that in the 13-wks calves, the response of juice flow and protein output (/kg of body weight) in the 2-wks calves were equivalent to or greater than those in the 13-wks calves. These results indicate that the characteristic of pancreas, being stimulated by short-chain fatty acids, in calves and probably in other ruminants is not generated on the process of postnatal development, but has been already acquired before rumen fermentation begins.

Acetates↗
PubMed1987

Validation of closed-loop subcutaneous insulin infusion algorithm--application of subcutaneous insulin absorption kinetics.

For long-term glycemic normalization with a closed-loop control system, a subcutaneous insulin infusion algorithm has been developed based on the pharmacokinetics of subcutaneously administered insulin. A 3-compartmental model was applied to mathematically express the relation between the insulin injected subcutaneously as an input and the plasma insulin response as an output. A computer simulation study using this model showed that the following insulin infusion algorithm is feasible for closed-loop glycemic control by selecting appropriate parameters (Kp/Kd/Kc = 0.0056/0.92/-0.11), IIR(t) = Kp G(t)+Kd d G(t)/dt+Kc, where IIR(t) is the subcutaneous insulin infusion rate at time t (min), G(t) is the blood glucose concentration and Kp, Kd, Kc are the constants. In 5 pancreatectomized dogs, subcutaneous insulin infusion with this algorithm made it possible to keep postprandial glycemic levels after oral glucose load (2 g/kg) at 168 +/- 14 mg/dl (mean +/- SEM) in 60 min and maintained normoglycemia from 180 to 300 min with the total amount of infused insulin being 0.14 +/- 0.019 U/kg. In 5 insulin-dependent diabetic patients, the peaks of postprandial glycemic levels after meal load (450 kcal) were controlled to 176 +/- 36 mg/dl at 90 min and were reduced to 98 +/- 13 mg/dl at 300 min with the total amount of infused insulin being 0.172 +/- 0.063 U/kg. The mean peak plasma insulin level was 49 +/- 11 microU/ml at 90 min. These results indicate the clinical controllability of postprandial glycemia with the closed-loop subcutaneous insulin infusion algorithm in diabetic patients.

Algorithms↗
PubMed1985

Long-term application of wearable artificial endocrine pancreas--closed-loop intravenous vs subcutaneous insulin infusion.

For closed-loop glycemic control on IDDM, closed-loop sc insulin infusion algorithm has developed by analysing the pharmacokinetics of sc insulin absorption. With the algorithm, daily glycemic excursion in IDDMs was controlled to near-normal levels. These data suggested that the closed-loop sc insulin infusion algorithm might be feasible to regulate glycemia in diabetic patients for a long-term period by wearable artificial endocrine pancreas.

Algorithms↗
PubMed1984

The development of wearable-type artificial endocrine pancreas and its usefulness in glycaemic control of human diabetes mellitus.

We have succeeded in miniaturizing a glucose monitoring system into a needle-type which preserves the characteristics suitable for application in a wearable closed-loop control system. The wearable artificial endocrine pancreas (12 X 15 X 6 cm, 400 g) consists of the sensor, a microcomputer which calculates the insulin and glucagon infusion rates and of a 2-syringe driving system. The device succeeded in controlling glycaemia perfectly in depancreatized dogs for a period of 3 days, and with replacement of subcutaneously inserted sensor for up to 7 days. When glucose monitoring by a needle-type glucose sensor inserted into subcutaneous tissue of the forearm or abdomen of healthy and diabetic volunteers was attempted, the readings were about 10% lower than blood glucose concentrations, but good correlation between them was observed in the range of 60 to 400 mg/dl. Perfect glycaemic control was established by infusing insulin either intravenously or subcutaneously in response to measured glucose concentrations on a moment-to-moment basis in diabetics for a period of several days. These results might indicate the feasibility of long-term glycaemic control in ambulatory diabetic patients with a wearable closed-loop glycaemic control system.

Blood Glucose↗
PubMed1980

Simultaneous determination of bestatin and p-hydroxybestatin, a major metabolite, in human serum by gas chromatography mass spectrometry. Utilization of quantitative selected ion monitoring and deuterium labelled internal standard.

A specific and sensitive method for the simultaneous determination of bestatin and its major metabolite, p-hydroxybestatin in human serum has been developed by selected ion monitoring using the corresponding deuterated internal standards. The N-trifluoroacetamide-O-trimethylsilyl either derivatives of the trideuteromethyl esters of bestatin and p-hydroxybestatin were suitable for quantitation by selected ion monitoring. The determination limit of these compounds by the present method is 1 ng ml-1 in human serum.

Adult↗
PubMedDate not supplied

Radioimmunoassay for ubenimex in human serum.

Anti-ubenimex antibody was produced by immunization of rabbits with ubenimex-bovine serum albumin (BSA) conjugate which was synthesized by coupling ubenimex directly to BSA using 1-ethyl-3-(3-dimethyl-aminopropyl)carbodiimide. The resulting antibody exhibited little cross-reactivity with p-hydroxyubenimex or (2S,3R)AHPA, (2S,3R)-3-amino-2-hydroxy-4-phenylbutanoic acid present in human serum as metabolites. Ubenimex in human serum could be measured selectively without prior drug extraction and purification. The standard curve prepared using the present assay method gave good linearity in the range 0.25-25 ng per assay tube. The detection limit was 125 pg per assay tube. The concentrations of ubenimex in human serum determined by the present method were in good agreement with those obtained by GC-SIM. The present method with its high sensitivity and specificity may be a valuable tool for the study of the pharmacokinetics of ubenimex.

Aminopeptidases↗
PubMedDate not supplied

Telemetry glucose monitoring device with needle-type glucose sensor: a useful tool for blood glucose monitoring in diabetic individuals.

For continuous monitoring of glucose concentration in ambulant diabetic patients, a telemetry glucose monitoring system with a needle-type glucose sensor has been developed. The system consists of a sensor transmitter (4 X 6 X 2 cm, 50 g) that converts current signals generated in a needle-type glucose sensor to high-frequency audio signals and a receiver that continuously calculates glucose concentrations from the received audio signals. The noise range of a monitoring record with the telemetry system (0.3 +/- 0.04%, mean +/- SEM) was significantly smaller than that with a wire-connected system, the wearable artificial endocrine pancreas (2.5 +/- 0.3%). Postprandial tissue glucose concentration responded well to the plasma glucose concentration, with a time lag of 5 min. Continuous glucose monitoring of five diabetic subjects for 77 +/- 22 h revealed that a significant correlation existed between the subcutaneous tissue glucose concentration and the plasma glucose concentration measured simultaneously in each patient. These data indicate the usefulness of the telemetry glucose monitoring system in strict glycemic control of diabetic individuals.

Autoanalysis↗