Search PubMed⌕ Search

Biomedical subjects

A Tokunaga

Publications and source records attributed to A Tokunaga.

At least 181 records · Page 10Linked to original sources
PubMed1981

Cytochemical localization of alkaline phosphatase in intestinal metaplasia of the human stomach.

Alkaline phosphatase in the brush border of areas of intestinal metaplasia of human stomach was studied cytochemically. All absorptive cells in the upper part of the villi of the duodenum had strong alkaline phosphatase activity but, in areas of intestinal metaplasia, the metaplastic glands consisted of alkaline phosphatase-positive and negative absorptive cells. Alkaline phosphatase activity was found in tall dense microvilli of absorptive cells in areas of intestinal metaplasia and in the duodenum. However, in some areas of metaplastic epithelium the activity was very weak in some tall dense microvilli of absorptive cells but strong in those of neighbouring absorptive cells. No alkaline phosphatase activity was found in short sparse microvilli of absorptive cells in areas of intestinal metaplasia. The difference in alkaline phosphatase activity in microvilli of different cells in areas of intestinal metaplasia, which is not seen in the duodenum, indicates abnormal morphological and enzymatic differentiation intestinal metaplasia.

Alkaline Phosphatase↗
PubMed1981

[Studies of humoral immunological response on the aborted trophoblasts (author's transl)].

To elucidate whether a humoral immune mechanism does involve in genesis of spontaneous abortion (SpA), comparative study on dynamics of immunoglobulin (Ig) and complement (C) was performed between SpA and normal pregnancy in the first trimester (NP-I). IgG, IgM and beta 1C/beta 1A were assessed as to their histological distribution in the trophoblastic tissues (TrT) by direct immunofluorescence technique. In the sera, they were determined by single radial immunodiffusion. Whole C titer (CH50) was also assayed in the sera by Kabat's method. The following results were obtained: 1. IgG was noted in granular pattern on the surface of syncytiotrophoblasts (STr) in NP-1, but it was rarely found on Tr in SpA. On the other hand, IgM was not usually observed in NP-1, but it was usually found in linear pattern on the surface of STr in SpA. Furthermore, beta 1C/beta 1A globulin was observed in the cytoplasm of STr in SpA, while it was not found in STr, but found in the basement membrane and/or fibrinoid areas of TrT in NP-1. 2. IgG and IgM in the sera gave no significant difference between SpA and NP-1. CH50, however, showed significant decrease (41.2+/- 5.4) in SpA (N = 16) compared to that (51.8 +/- 8.5) in NP-1 (N = 26). Serum beta 1C/beta 1A globulin level was also lower (53.0 +/- 8.4) in SpA (N = 22) compared to tha (60.5 +/- 14.8) in NP-1 (N = 30). The results lead us to the conclusion that humoral immune cytotoxicity by IgM in cooperation with C may be involved in the mechanisms responsible for the damage of Tr in SpA.

Abortion, Spontaneous↗
PubMed1980

Cell types and synaptic organization of the medullary electromotor nucleus in a constant frequency weakly electric fish, Sternarchus albifrons.

The medullary electromotor nucleus (EMN) of Sternarchus albifrons was studied at the light and electron microscopic levels. The EMN consists of a dense meshwork of myelinated axons and glial elements with interposed large neurons; it is provided with an abundant supply of capillaries. Two types of essentially adrendritic nerve cells were distinguished on the basis of size: giant neurons (approx. 70 micrometers in diameter) and large neurons (approx. 30 micrometers in diameter). Their population ratio is 1:4. Only giant cells are labelled following the injection of retrograde tracer into the spinal cord; they are therefore identified with the so-called "relay cells" of other gymnotids. Tracer experiments further suggest that the descending axons of these relay cells give off collateral branches throughout the elongated spinal electromotor nucleus. In contrast, the large cells remain unlabelled and therefore lack spinal projections; they most likely correspond to "pacemaker cells." The perikaryal surface, including axon hillock and proximal part of initial segment of both types of EMN cells, is contacted by clusters of synaptic terminals and astrocytic processes. Two main varieties of synaptic terminals occur: (1) large endings and (2) ordinary end feet with standard size (S-type) and variable size (Sv-type) clear, spherical vesicles. The junction between large endings and EMN cells is characterized by the combination of gap junctions and surrounding intermediate junctions whose freeze-fracture characteristics were morphometrically analyzed. The large endings were formed by nodes of Ranvier as well as by fiber terminations, and synchronization within the EMN may be achieved by presynaptic fibers. Some of the contacts occur directly on the initial segment, which could allow activity to bypass the soma. It is concluded that the elctromotor system of Sternarchus is comprised of a rapid conduction pathway where medullary pacemaker and relay cells as well as spinal electromotor neurons are coupled by synapses with gap junctions. In contrast to the spinal electromotor neurons, the medullary EMN cells receive synapses with morphological characteristics of chemical transmission, and the S-type and SV-type terminals may possibly correspond to Gray's Type I and Type II synapses, respectively. These synapses may be involved in modulation of the electric organ discharge frequency.

Animals↗
PubMed1980

[Clinical studies on cases of cardiovascular disease during pregnancy (author's transl)].

The long term follow up studies on cases of cardiovascular diseases during pregnancy or delivery were reviewed in 181 patients administrated in our clinic. The results as follows: 1. An incidence of patients with cardiovascular disease during pregnancy was 1.46 per cent as a whole, and there was increasing tendency in congenital heart disease. 2. An accidental heart failure during pregnancy was seen in 7.7 per cent and all cases with NYHA III grade had an incidence of 100 per cent. 3. The occurrence of toxicosis and SFD pregnancy were more frequently seen in group of heart disease than in controls. But, no difference was observed in spontaneous abortion or neonatal asphyxia. 4. 28 patients with Starr-Edwards prosthetic heart valves became pregnant in our clinic. In these pregnancies, 5 cases receiving with warfarin therapy resulted in 3 anomalies of new born and in 2 spontaneous abortion. So, the use of warfarin seemed to have the risk to the fetus. But omission of the anticoagulant therapy on the other hand, increased the danger of systemic embolization to the mother. 5. The follow up study by mail in some cases revealed that, as a general, pregnancy and delivery may aggravate the condition of patients, especially who had mitral heart failures.

Abortion, Spontaneous↗
PubMed1979

Increase of large intramembranous particles in the presynaptic active zone after administration of 4-aminopyridine.

The effects of 4-aminopyridine (4-AP, 1 mg/kg i.v.) on the distribution of intramembranous particles in spinal motoneuronal synapses was examined in anesthetized (pentobarbital sodium, 50 mg/kg, i.p.) rats by freeze-etching electron microscopy. The particles were classified according to their size into small (4.2--10.5 nm in diameter) and large (10.5--18.9 nm in diameter). The active zone of the presynaptic membrane was identified on the basis of ultrastructural criteria. The large intramembranous particles in both protoplasmic (PF) and external fracture faces (EF) were aggregated more densely in the active zone as compared with its surroundings both in the control and 4-AP-treated group (P less than 0.001). The density of large particles in the PF rose from 300/sq.micron under the influence of 4-AP (P less than 0.001). The increased frequency of vesicle attachment sites at the presynaptic membrane (from 115/sq.micron in barbiturized controls to 150/sq.micron in 4-AP treated animals) seemed to be positively correlated with the increasing density of large particles. Based on these findings it is suggested that the large intramembranous particles of the presynaptic membrane may participate in the control of calcium fluxes which are essential to the transmitter release by exocytosis.

Aminopyridines↗
PubMed1979

Ultrastructural effects of 4-aminopyridine on the presynaptic membrane in the rat spinal cord.

The effects of 4-aminopyridine (4-AP, 1 mg/kg, i.v.) on the ultrastructure of synapses in the ventral horn of the spinal cord were examined in rats anesthetized with 50 and 100 mg/kg, i.p., pentobarbital sodium and alpha-chloralose respectively. The presynaptic membrane of the 4-AP-treated animals, in both S- and F-type synapses, was wrinkled and gave frequently rise to omega-shaped profiles. However, it was not prominently lifted in comparison with the controls. In both extracellular (EF) and protoplasmic fracture faces (PF) of freeze-etched replicas, the frequency of the presynaptic membrane modulations (PMM) per unit area rose significantly under the influence of 4-AP. The ratio of open (crater-like) to total PMM in EF increased almost twice under the experimental condition. No differential 4-AP effects were seen between pentobarbital- and chloralose-treated animals. The morphological evidence is consistent with electrophysiological data showing that 4-AP facilitates the transmitter release at synaptic endings.

Aminopyrine↗
PubMed1979

Three types of membrane modulations during transmitter release in rat spinal cord synapses.

Protoplasmic fracture faces of vesicle attachment sites (VSA) in the presynaptic active zone of rat spinal motoneurons were classified morphologically on the basis of particle-to-membrane relationships. Intramembranous particles are absent in type 1, located around the edges of type 2 and covering the center of type 3. Application of 4-aminopyridine (4-AP), which is known to enhance transmitter release, affected strikingly the total number of VAS (P less than 0.001) but not the percentage of the three types. It is postulated that the particle-free VAS (types 1 and 2) sharing 80--85% of VAS within the active zone, are related to exocytosis. The predominance of type 3 outside the active zone and its similarity to particle-loaded indentations possibly corresponding to coated vesicle formation, suggested that type 3 may represent endocytosis.

Aminopyridines↗
PubMed1977

The glabella-inion line as a baseline for CT scanning of the brain.

The optimal position of the head for CT scanning of the brain is discussed according to the statistical data of roentgencraniometry. The glabella-inion (GI) line was shown to be parallel to the frontal-occipital pole (FO) line which was substituted for a line joining the deepest gyral impressions in frontal and occipital parts of the cranial cavity. On the other hand, Reid's baseline and the canthomeatal (CM) line intersected the GI line at various angles from person to person. There was a significant difference between each average inclination angle of males and females. Regarding using either Reid's or the CM line for a baseline, it should be noted that the brains were scanned in almost random direction. Therefore it may be convenient to apply the GI line for comparing the findings between individuals, and for correlating them to the anatomical diagnosis.

Adult↗
PubMed1974

Further studies on induction of stomach cancer in hamsters by N-methyl-N'-nitro-N-nitrosoguanidine.

Oral administration of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) to hamsters at a concentration of 50-83 μg/ml in the drinking water resulted in a high incidence of tumours in the glandular stomach. Short-term administration of MNNG for 4-6 months resulted in more adenocarcinomata in the glandular stomach than long-term administration for 7-8 months. One case of metastasis of an adenocarcinoma of the glandular stomach to the liver and 2 cases of metastasis to the regional lymph nodes were found. Spindle cell sarcomata in the glandular stomach and adenocarcinomata in the duodenum were also often produced.Oral administration of MNNG at the very high concentration of 500-2000 μg/ml induced a hepatic cell carcinoma, intrahepatic bile duct carcinomata, bile duct cystadenomata and cystic dilatation, and a haemangioma in the liver but no tumour in the glandular stomach.Sequential morphological studies on the glandular stomach of hamsters receiving 50 μg/ml of MNNG in the drinking water showed 3 stages of change of the mucosa. The mucosa became atrophic and eroded in the first 16 weeks. Irregular atypical glands developed at the margins of erosions and proliferation of spindle cells in the submucosa were found after 18 weeks. Spindle cell sarcomata developed in animals after 20 weeks. Adenocarcinomata developed between 25 and 32 weeks.

Adenocarcinoma↗