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Biomedical subjects

T Maki

Publications and source records attributed to T Maki.

At least 145 records · Page 8Linked to original sources
PubMed1990

In vivo 13C imaging enhanced by polarization transfer.

Carbon-13 NMR imaging has been combined with 1H-13C polarization transfer to improve image quality. Natural-abundance carbon images of Fischer rat bodies were obtained within a few minutes. Next 13C-labeled glucose was administered orally to rats, and spatial distributions of glucose and its derivatives were observed with this technique.

Animals↗
PubMed1990

Characterization of molecular species of liver microsomal carboxylesterases of several animal species and humans.

Seven carboxylesterase isozymes were purified to electrophoretic homogeneity from liver microsomes of mouse, hamster, guinea pig, rabbit, and monkey by the same procedure used previously to obtain three isozymes from the rat, and their physical, enzymological, and immunological properties were compared with those of the rat isozymes. The substrate specificity and immunological reactivity of liver microsomal carboxylesterases from pig, cow, beagle dog, and human were also examined for comparison, though these enzymes were not purified. The ten purified preparations have similar subunit weight (57,000-64,000), but their isoelectric points differ widely (4.7-6.5). The purification procedure of all isozymes included concanavalin A-Sepharose column chromatography. The isozymes were not eluted from the column with a high concentration of sodium chloride, but were efficiently eluted with alpha-methylmannoside. This observation suggested that the carboxylesterases studied are glycoproteins. All the isozymes except rat RL1 and RL2 possess a high hydrolytic activity toward all the substrates examined. Long-chain monoglyceride was hydrolyzed by the purified carboxylesterase isozymes. Anti-rat RH1 immunoglobulin G was found to possess high cross-reactivity with all isozymes tested, except monkey MK2, by immunoblotting analysis. The amino acid compositions of carboxylesterase isozymes showed considerable similarities, except for monkey MK2. The amino-terminal amino acid sequences showed a striking homology, except for monkey MK2, though the amino-terminal amino acid itself was different in every isozyme. Hepatic microsomal carboxylesterases in mammals play an important role in drug and lipid metabolism in the endoplasmic reticulum, and it is noteworthy that the isozymes from various species examined here showed considerable similarities in physical, enzymatic, and immunochemical properties.

Amino Acid Sequence↗
PubMed1990

Crucial role of pancreatic ductal collagenase injection for isolation of pancreatic islets.

We have been stressing the advantage of stationary digestion because of its simplicity and reproducible high yields of viable islets. In the present study optimal conditions of stationary in vitro collagenase digestion in mice and rats were examined. We also compared two possible routes for collagenase injection; ductal (PD) and portal venous (PV) based on subsequent islet yield and ability to reverse diabetes in rats. Three parameters which affect the quality of digestion are 1) collagenase concentration, 2) incubation time and 3) digestion temperature. Suitable conditions were easily determined and reproducible high yield of islets could be consistently obtained. The islets from one mouse pancreas (approximately 200 islets) could consistently restore normoglycemia in one STZ-induced diabetic mouse and the islets from one rat pancreas (500-600 islets) can restore normoglycemia in 5-6 STZ-induced diabetic mice within a couple of days. Islet yield in the PD method was greater than that in the PV method, and insulin release from PD islets in response to high glucose was well preserved after 24 hours of culture when compared to PV islets. The ability to restore normoglycemia in STZ-induced diabetic mice was well preserved when transplanting 100 PD islets as compared with the same number of PV islets. The PD islets revealed a well preserved structure with healthy endocrine cells, while the PV islets showed a dilated capillary network and distorted endocrine cell continuity. Histological examination of digested tissue following PD injection showed the complete destruction of pancreatic exocrine tissue, as well as mechanical separation and digestion of interstitial tissue between the islets and exocrine tissue, with the islet being preserved selectively intact.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Gamma-irradiation as a tool to reduce immunogenicity of islet allo- and xenografts.

Sensitivity of pancreatic endocrine cells to gamma-irradiation and alteration of islet immunogenicity by irradiation were examined. Syngeneic, allogeneic (DBA/2) and xenogeneic (rat) islets were irradiated and transplanted at varying doses (8, 24, 40, 80 and 160 Gy) into streptozotocin-induced diabetic B6AF1 mice. In an isograft model, late loss of graft function was observed in some animals given 200 24-Gy-irradiated islets. However, larger numbers (400-500) of islets given 40 Gy irradiation did not show reversal of normoglycemia. With higher doses (80 or 160 Gy) significant early as well as late graft loss was observed. In an allograft model, the irradiated islet allografts survived beyond controls. Marked prolongation was achieved with a broad range of irradiation doses between 8 Gy and 120 Gy with 30-90% of recipients maintaining normoglycemia over 50 days. Late loss of graft function was observed between 78 and 180 days with a dose over 24 Gy. Increasing dose resulted in a better allograft survival rate in the early postoperative period, but tended to curtail longterm survival. In an xenograft model, irradiation of islets with 8 to 24 Gy led to prolongation of graft survival. Maximum graft prolongation was achieved with 24 Gy. Higher doses were much less effective and, in some recipients, caused shortening of graft survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

An atypical case of cardiomyopathy in a child: hypertrophic or restrictive cardiomyopathy?

A case of an atypical form of cardiomyopathy, in which biopsy showed bizarre myocardial hypertrophy with disorganization, and in which there was no obvious hypertrophy of the interventricular septum and left ventricular free wall, is presented. Ventricular filling was critically impaired, and consequently pulmonary and systemic venous congestion predominated in the clinical presentation which was similar to that of restrictive cardiomyopathy.

Biopsy↗
PubMed1990

[Plasma atrial natriuretic peptide (ANP) levels in Parkinson's disease--with special reference to foot edema].

Edema in Parkinson's disease has been considered to be caused by autonomic nervous system dysfunctions, however little is still known about the exact pathophysiological mechanism involved. In this study, we focused on plasma atrial natriuretic peptide (ANP) levels in Parkinson's disease to elucidate the relationship between foot edema and plasma ANP levels. Thirty four cases of Parkinson's disease were studied. Plasma ANP levels were measured using the radioimmunoassay method. The incidence of foot edema in Parkinson's disease was approximately 30% of the cases studied, with a tendency to be more common in patients in the Yahr stages II and III groups. Predilection sites of the edema were observed from the pretibial to dorsal pedis of both lower thighs, especially on the side most severely affected by the disease. Onset of the edema was difficult to clarify because almost all of the patients with foot edema did not notice the edema by themselves. There was no clear relationship between edema and L-DOPA treatment of Parkinson's disease. For treatment of the edema, oral administration of Furosemide was effective in many cases, however the efficacy tended to gradually decrease. Plasma ANP levels in each age group of the Parkinson's disease cases were statistically high when compared to the values of the age-matched normal volunteers. Plasma ANP levels in the patients with foot edema were also significantly high when compared with the edema-free patients (p less than 0.001), however no relationships were found between plasma ANP levels, age and duration of the illness. It is known that plasma ANP is a cardiac hormone with fluid volume-reducing and vasodilating functions.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

[Pharmacokinetic, bacteriological and clinical studies on aztreonam in neonates].

Pharmacokinetic, bacteriological and clinical studies on aztreonam (AZT) were performed in neonates. The results obtained are summarized as follows. 1. Plasma levels and urinary excretion of AZT were determined in 18 neonates with ages between 1 and 30 days (gestation periods were 36 to 40 weeks and birth weights were 1,890 to 4,300 g) and in 2 infants with 54 and 60 days of age (gestation periods were 36 and 40 weeks, and birth weights were 2,300 and 3,300 g, respectively) upon one-shot intravenous injection of AZT 10 mg/kg (7 cases) or 20 mg/kg (11 cases) to the 18 neonates and 20 mg/kg to the 2 infants. Ampicillin (ABPC) 25 mg/kg was simultaneously injected to 5 cases of the neonates given AZT 20 mg/kg by one-shot intravenous injection and plasma concentrations of ABPC in these 5 cases were also studied. Plasma concentrations in neonates at 0.5 hour after intravenous injection of AZT 10 mg/kg were 11.5 to 27.6 micrograms/ml (average 20.3 +/- 5.5 micrograms/ml) and decreased with half-lives of 2.72 to 5.70 hours (average 3.81 +/- 1.28 hours), and the plasma levels at 8 hours after administration were 3.3 to 8.7 micrograms/ml (average 5.8 +/- 2.5 micrograms/ml). In the cases given AZT at 20 mg/kg, plasma levels at 0.5 hour were 12.4 to 48.8 micrograms/ml (average 35.9 +/- 11.6 micrograms/ml) and decreased with half-lives of 1.69 to 4.14 hours (average 2.94 +/- 0.76 hours) and AZT levels at 8 hours were 1.1 to 10.6 micrograms/ml (average 5.6 +/- 3.6 micrograms/ml). Urinary recovery rates in the first 8 hours after intravenous injection of the 10 mg/kg group were 15.5 to 61.9% (average 37.8 +/- 21.8%) and 16.3 to 62.2% (average 43.5 +/- 16.2%) for the 20 mg/kg group. Plasma concentrations in infants after administration of AZT 20 mg/kg were 33.0 to 35.6 micrograms/ml (average 34.3 +/- 1.8 micrograms/ml) at 0.5 hour and decreased with half-lives of 1.76 to 3.77 hours (average 2.77 +/- 1.42 hours) and AZT plasma levels at 8 hours were 1.4 to 5.8 micrograms/ml (average 3.6 +/- 3.1 micrograms/ml). Urinary recovery rates were 35.4 to 64.8% (average 50.1 +/- 20.8%). These results suggested that AZT shows a dose-dependent, high plasma concentration even in the neonatal period, as well as good urinary excretion from an early stage of the administration.(ABSTRACT TRUNCATED AT 400 WORDS)

Ampicillin↗
PubMed1990

[Gallstone and Parkinson's disease--ultrasound echography study].

Gastrointestinal symptoms caused by autonomic nervous system dysfunction has been well known in Parkinson's disease. This time we had a chance to see a patient with Parkinson's disease associated with acute abdominal pain because of gallstones. This study extended to examine abdominal findings in 79 cases of Parkinson's disease using abdominal ultrasound echography and also studied relationships between echographic findings and age, Hoen-Yahr stage and duration of the illness. Results were as follows: Echographic abnormalities were found 53.2% of the cases. Among them, gallstone was the most frequent findings and the incidence was 29.1% which showed significantly higher than that of the gallstone holding ratio (16.6%) in a age matched Japanese autopsy study. Subsequent findings were renal cyst (16.5%), renal stone (8.9%), liver cyst, portal dilatation and so on. No remarkable relationship was found between Hoen-Yahr stage and gallstone, however good correlation was found between duration of the illness and gallstone. It was concluded that gallstone holding ratio in Parkinson's disease is considerably high compared to that of a age matched Japanese autopsy study, which might be of great use in our daily clinics.

Age Factors↗
PubMed1990

Carbon-13 NMR imaging study of in-vivo glucose metabolism.

Carbon-13 NMR spectroscopy and chemical shift selective imaging studies of in vivo glucose metabolism were performed at 2.0 T. Some metabolite peaks were observed in 13C NMR spectra, and carbon NMR imaging focused in the spectral region attributed to D-1-13C-glucose were also performed. A 13C NMR signal accumulated in the liver was detected and the average time resolution of these spectra and images were 10 and 30 minutes, respectively.

Animals↗
PubMed1989

Evidence for an alteration in the microsomal Ca2+ release mechanism in senescent rat parotid acinar cells.

Previously, we have shown that Ca2+ mobilization following an alpha 1-adrenergic receptor stimulus is reduced in parotid acinar cells from senescent rats as a result of an altered ability of inositol 1,4,5-trisphosphate (IP3) to induce Ca2+ release from a non-mitochondrial, intracellular Ca2+ store (Ishikawa, Y., et al. Biochim. Biophys. Acta 968, 203-210). We have used this model to examine the IP3-induced Ca2+ release mechanism in these cells. 45Ca2+ efflux, after exposure to (-) epinephrine, from cells of young adult (3-6 months) rats was approx. 2-fold that observed from cells from older animals (approx. 24 months) either in the presence or absence of extracellular Ca2+. Similarly, cytosolic Ca2+ levels were greater in cells of young adult rats under these same incubation conditions. However, microsomal membrane preparations, from both age groups displayed similar IP3 binding sites (Kd approximately 90 nM, Bmax approximately 850 fmol/mg protein) and ATP-dependent Ca2+ transport ability (approx. 8 nmol/mg protein.min -1). These data suggest that there is an alteration in the IP3-induced Ca2+ release mechanism in microsomal membranes of parotid glands from senescent rats which may account for the decreased Ca2+ release seen after agonist stimulation of this tissue.

Animals↗
PubMed1989

Successful treatment of experimental diabetes by sequential transplantations of multiple-donor pancreatic islet allografts.

Fifty hand-picked islets were freshly prepared from DBA/2 mice and transplanted four times into a streptozotocin-induced diabetic B6AF1 mouse without immunosuppression. Blood sugar levels decreased progressively and all recipients became normoglycemic after the 4th grafting. Four repeated transplantations at 2-4-day or 14-day intervals restored normoglycemia for more than 200 days in virtually all recipients. However, a majority of recipients given four transplantations of 50 DBA/2 islets at 7-day intervals or four transplantations of 100 DBA/2 islets at 4-day or 14-day intervals acutely rejected their grafts. When handpicked islets were freshly prepared from each of four histoincompatible donors (DBA/2, DBA/1, A.SW, and C3H) and sequentially transplanted four times (islets from one donor for each transplantation) into diabetic B6AF1 recipients, virtually all recipients maintained normoglycemia for more than 200 days regardless of the number of islets per grafting or intervals between transplantations. Since the purity of human islet preparations to date has been at the level of crude-digested islets, crude islets were used in sequential transplantation. Four transplantations of approximately 50 crude islets prepared from each of four donors achieved marked prolongation of graft survival. In sharp contrast, transplantation of 250-500 single-donor crude islets or four sequential transplantations of DBA/2 50 crude islets resulted in acute graft rejection.

Animals↗
PubMed1989

Graft-versus-host disease in fully allogeneic small bowel transplantation in the rat.

Small bowel and its mesentery contain considerable amounts of lymphoid tissue that can mediate graft-versus-host disease in small bowel transplant (SBT) recipients. Present studies determined the existence of GVHD in a fully allogeneic SBT model and examined the effect of donor pretreatment with ALS in eliminating GVHD. Adult male Lewis (Lew) rats received orthotopic small bowel transplants from untreated (LewxBN)F1 (LBNF1) donors (group 1) or Brown Norway (BN) donors that were untreated (group 2) or pretreated with ALS (days -2 and -1) (group 3). All recipients were treated with cyclosporine 15 mg/kg/day i.m. on days 0-6 postoperatively. Animals were weighed and examined daily for signs of rejection and GVHD. No animals in groups 1 or 3 showed any physical signs of GVHD, but all of those in group 2 had characteristic weight loss, diarrhea, and dermatitis between 4 and 6 weeks postoperatively, from which they all recovered. Histologic examination of skin and spleen at this time confirmed the presence of GVHD. The relative spleen weight [( spleen weight/body weight] x 100) of group 2 animals was also significantly greater than that of unoperated control Lew animals. Spleen cells obtained from group 2 animals at the time of subclinical GVHD, but not cells from group 1 or 3 animals, caused enlargement of popliteal lymph nodes when they were injected into the footpads of Lew rats. This study shows that GVHD can manifest itself in recipients of a fully allogeneic small bowel transplant even when rejection is prevented by effective immunosuppression with CsA. However, combined use of recipient treatment with CsA and pretreatment of donor animals with ALS eliminates all manifestations of GVHD.

Animals↗
PubMed1989

Sudden cardiac death in childhood.

To evaluate the mechanism of sudden death in childhood and the physical activity levels at the onset of sudden death, we studied the following items: (1) the incidence and the circumstances surrounding sudden death at school in Kanagawa Prefecture, (2) high risk heart diseases detected among healthy school children by heart disease screening, (3) sudden cardiac death or near miss seen in outpatients with heart disease except congenital heart disease. Among total 15,156,346 school children, sudden death was observed in 97 subjects (M:77, F:20). Annual incidence of sudden death was 6.4 per 10(6). Of the 97 subjects, acute heart failure of unknown etiology was found in 60 (62%), cardiovascular disease in 18 (19%), cerebral vascular accidents in 14 (14%) and heat stroke in 5 (5%). Of the 78 subjects (M:64, F:14) considered as sudden cardiac death, 62 (79%) died during sports activities, and 16 (21%) died at rest. Of the 62 subjects, 29 died during track and field activities and 7 while swimming, both in physical education classes. Eighteen died during athletic club activities and 8 during extracurricular activities. Consequently, 54 subjects (87%) died in the presence of a school teacher. Of the 18 subjects with cardiovascular disease, 9 (hypertrophic cardiomyopathy in 3, myocarditis in 3, Kawasaki disease in 2 and long QT in one) were diagnosed initially by the autopsy study. Latent high risk heart diseases, detected among presumably healthy school children by the heart disease screening program, were the following: hypertrophic cardiomyopathy, long QT syndrome, Kawasaki disease and some arrhythmias (ventricular tachycardia, sick sinus syndrome, A-V block and atrial fibrillation). Follow-up observations of outpatients with heart disease revealed the same results as the heart disease screening program. In order to prevent sudden death at school, the following recommendations should be observed: 1) sports directors should learn "sports medicine in childhood", including primary cardiovascular resuscitation, 2) an accurate heart disease screening program should be operated to detect latent high risk heart diseases, advise on adequate medical treatment, and help ensure an appropriate selection of sports activities, 3) comprehensive autopsy studies should be performed.

Adolescent↗
PubMed1989

Evidence for age-related change in plasma 19-hydroxyandrostenedione.

The steroid, 19-hydroxyandrost-4-ene-3, 17-dione (19-hydroxyandrostene-dione, 19-OH-A-dione) has been known to enhance the mineralocorticoid action of aldosterone. To investigate the age-related change in the plasma 19-OH-A-dione concentration, plasma 19-OH-A-dione, androst-4-ene-3, 17-dione (A-dione), aldosterone and cortisol of 38 non-hypertensive healthy subjects (18 young men and 20 aged men) measured by specific radioimmunoassays. The basal plasma 19-OH-A-dione and A-dione concentration in aged men was significantly lower than in young men (P less than 0.01). Moreover, there was found to be a positive correlation between plasma 19-OH-A-dione and A-dione (P less than 0.01). On the other hand, plasma aldosterone and cortisol in aged men showed a tendency to decrease, but no statistical significance compared to young men was observed. This study demonstrated that there was an apparent age-related decrease not only in plasma A-dione, but also in plasma 19-OH-A-dione, an amplifier or aldosterone action.

Adolescent↗