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Biomedical subjects

A Aoki

Publications and source records attributed to A Aoki.

At least 181 records · Page 10Linked to original sources

Influence of embedding media in prolactin labelling with immunogold techniques.

Immunogold labelling of prolactin in three different embedding media was compared. The polymeric prolactin in secretory granules was labelled in the three media, however, acrylic monomers (Lowicryl K4M and LR White) provided a more intense labelling with higher dilutions of the primary antibody, compared to the labelling in the epoxy resin (araldite). An intense labelling of monomeric prolactin in Golgi complex was detected only in acrylic embedments, and the labelling on the rough endoplasmic reticulum was significant only in LR White embedded tissues.

Acrylic Resins↗

Regression of redundant lactotrophs in rat pituitary gland after cessation of lactation.

Regressive changes occurring in the pituitary gland of the rat after removal of litters were studied. Pituitary glands of lactating rats were characterized by the presence of numerous hypertrophied lactotrophs. Interruption of lactation caused a blockade of prolactin synthesis and secretion, followed by degeneration of lactotrophs. Morphometric analysis of pituitary glands revealed that lactotrophs accounted for about 50% of the total hypophysial cell count in lactating rats. This percentage decreased progressively and reached pre-pregnant levels 7 days after removal of litters; the decrease was inversely correlated with an increase in the number of degenerating lactotrophs which comprised 30% of all lactotrophs 72 h after removal of litters. The morphological changes found in lactotrophs were closely related to changes in the prolactin content of serum and the pituitary gland. Regression of lactotrophs appeared to be the most important cause inducing the reversal of hypophysial lactotrophic activity to pre-pregnant conditions.

Animals↗

Improvement of prolactin immunolabelling in osmium-fixed acrylic-embedded pituitary gland.

Immunolabelling of prolactin (PRL) with protein A-colloidal gold complex and tissue fine structure were enhanced after postfixation of pituitary gland with osmium tetroxide and embedment in acrylic momers (LR White). Thin sections were treated with sodium metaperiodate before immunocytochemistry. An intense PRL labelling was detected in secretory granules, Golgi complexes and extracellular accumulation of the hormone. The use of osmium greatly improved the fine structure of the tissue and its stability during acrylic embedment.

Acrylates↗

Permeability studies of the guinea pig placental labyrinth. II. Tracer permeation and freeze-fracture of fetal endothelium.

Permeability of the fetal endothelium within the guinea pig placental labyrinth is studied by means of horseradish peroxidase (HRP) and ionic lanthanum as diffusion tracers. The paracellular transport of HRP is restricted by the occluding junctions of the fetal endothelium. In contrast, ionic lanthanum readily permeates most of the intercellular junctions and rapidly infiltrates the basal lamina. Freeze-fracture replicas reveal zonulae occludentes connecting the fetal endothelial cells. The network of the zonulae occludentes is variable, exhibiting highly complex areas as well as single strand interconnections. A correlation between the permeability studies and freeze-fracture findings is discussed.

Animals↗

Subcellular compartmentation of prolactin in rat lactotrophs.

The intracellular localization of different molecular forms of prolactin was studied in various experimental models covering a wide range of secretory states. By correlating electron microscopy, morphometry and quantification of monomeric (small) and polymeric (big) prolactin after differential extraction procedures, big prolactin was found stored in secretory granules while small prolactin was loosely associated with all organelles involved in hormone synthesis and processing. No correlation with levels of lactotrophic secretory activity was detected by either the number of secretory granules or prolactin content in lactotrophs.

Animals↗

Isolation of two different pools of pituitary prolactin.

Two pools of prolactin (Prl) were isolated from the pituitary gland. One readily soluble after homogenization and the other sedimented with secretory granules. In ovariectomized-oestrogen treated rats the latter represents the major Prl fraction of pituitary and can be recovered as immunoreactive Prl after extraction in 2.5 M urea. By correlation of electron microscopy, chromatography and RIA, evidence is gathered that the soluble fraction is constituted by monomeric (little) Prl and that secretory granules contain Prl in a polymerized form (big).

Animals↗

[A case of intracranial malignant lymphoma with pure akinesia and repeated regression on CT scans].

In a case of primary reticulum cell sarcoma in the brain, histologically verified by biopsy, the tumor regressed twice on a CT scan without radiotherapy. The systemic freezing phenomenon was seen as a main clinical symptom. The patient, a 44 year-old male, first complained of decreased livido and festinating speech. He also showed frozen gait, micrographia, a decrease in spontaneity and urinary incontinence. Four months after onset he was hospitalized. Neurological findings on admission revealed freezing of gait, writing, and speech, but there was no weakness of muscles with normal tendon reflexes, and normal muscular tone. In the CT scan on admission, there were high density areas mainly in the head of the right caudate nucleus, the medial deep portion of the right frontal lobe, the right side of the hypothalamus, the anterior thalamus, the globus pallidus. There were also nodular-type enhanced effects in the same areas. Regression of the tumor was seen on the CT scans after administration of betamethasone. The tumor which had again increased in size regressed spontaneously without the use of steroids after 3 months. Thereafter, the tumor gradually became larger and an open biopsy was performed. Histopathological findings showed a reticulum cell sarcoma. There were no findings of systemic malignant lymphoma. Such intracranial malignant lymphomas showing repeated regression including spontaneous one are very rare in the literature. The freezing phenomenon in this case started with festinating speech and spread to writing and gait. L-DOPA had no effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

[Thermographic analysis of the brain temperature in rats following microwave irradiation].

A thermoviewer, a new model of JTG-500 (JEOL, Japan) was utilized for finding the effect of microwave heat energy absorption and its conductivity in the brains of rats and mice following microwave irradiation (MWR). The frozen head was cut in either the sagittal, frontal or horizontal plane. After the frozen brain returned to room temperature (27-28 degrees C), the parts were put together with scotch tape and place in the exposure chamber. The rat's brain was irradiated at 6 kW for 0.6 sec and the mouse's brain was irradiated at 6 kW for 0.12 sec. Within 2 min. after irradiation, one side of each head was removed from the body and set in front of the camera unit. Each frame of a thermal image with its temperature information was stored in a data memory and the image of the brain surface was displayed at a flickerfree TV rate under the most optimum display condition. The temperature resolution of the device was 0.05 degrees C. In the individual rat planes, the highest energy was efficiently centralized in the middle of each individual plane and was distributed to the periphery showing phased decreases in temperature. The temperature differences recorded in the rat's sagittal, frontal and horizontal sections were; 4.6 degrees C, 5.0 degrees C and 3.4 degrees C, respectively. Temperature differences in rat brains irradiated by MWR were known to be below 5.0 degrees C under these experimental conditions. In the mouse planes, the highest level of microwave energy was also centralized in the middle of each individual section.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Effect of gossypol upon motility and ultrastructure of Trypanosoma cruzi.

Gossypol, a polyphenolic compound from the cotton plant, immobilizes and structurally alters cultured Trypanosoma cruzi epimastigotes. Ultrastructural changes observed in gossypol-treated parasites were first detected in the kinetoplast and mitochondrion. At 50 microM concentration, much disorganization was evident after 5 min of incubation. With 25 microM gossypol, the same effect occurred after 30 min. Most epimastigotes were rounded, containing various membranous structures that could not be related to known cell components.

Animals↗

[Carcinoma of the esophagus engrafted on corrosive stricture of the esophagus].

A highly significant incidence of esophageal cancer engrafted on corrosive stricture of the esophagus has been statistically evaluated. So far, only 8 cases in Japan and over 100 cases in foreign literatures have been reported. In 1976, we reported the first case of carcinoma of the esophagus associated with corrosive stricture of the esophagus in Japan. Our second case operated in 1975 was pathologically confirmed to be adenosquamous carcinoma of the esophagus which has never been reported in the literatures. In this paper surgical and pathological problems of the carcinoma of the esophagus associated with corrosive stricture of the esophagus were discussed adding to the analysis of 8 reported cases in Japan.

Aged↗

Ultrastructural changes in the hypothalamic ventromedial nucleus of ovariectomized rats after estrogen treatment.

The changes produced in the hypothalamic ventromedial nucleus (VMN) of ovariectomized rats after administration of 100 microgram estradiol benzoate/kg body weight were studied using light and electron microscopy. Quantitative morphometric studies included number and size of VMN neurons and nuclei, size and density of terminals and synaptic contacts, spine-to-shaft ratio of postsynaptic elements and relative frequency of two types of synaptic vesicles. Evidence was obtained favoring the concept of heterogeneous composition of the VMN: in ovariectomized animals many cells appeared in a state of quiescence, but other neurons showed no major alterations. Estrogen administration to ovariectomized rats produced evidence of metabolic stimulation such as increase in rough surfaced endoplasmic reticulum, condensation of nucleolar material, enlarged Golgi and presence of pleomorphic mitochondria. The number of neurons in the VMN was not modified by estrogen treatment; however, neuron soma and nuclei were larger. In the ventrolateral division of the VMN terminals and synaptic contacts per unit area were increased after estrogen treatment, but synaptic contact length, terminal size and spine-to-shaft ratio were not modified. The possibility that the differences observed may be consequent to changes in synaptic organization of the VMN related to its estrogen-dependent functions is discussed.

Animals↗