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Biomedical subjects

A Tokunaga

Publications and source records attributed to A Tokunaga.

At least 163 records · Page 9Linked to original sources
PubMed1985

Distribution of the tecto-thalamic projection neurons in the hereditary microphthalmic rat.

Tecto-thalamic projections in the hereditary bilaterally microphthalmic rat were studied by means of WGA-HRP injection into the dorsal lateral geniculate nucleus (LGNd) and the lateroposterior thalamic nucleus (LP). Histological study in the mutant rats showed that whereas LGNd and superficial layers of the superior colliculus (SC) suffered from a remarkable reduction in size, LP had no histological changes as compared to the normal animals. Unilateral injection of the tracer into the microphthalmic LGNd showed that WGA-HRP positive neurons were present mostly in the ipsilateral str. griseum superficiale (SGS) of the SC. However, the number of labeled SGS neurons of the microphthalmic animals was about 3% of the normal. Although cell bodies of the normal tecto-LGNd neurons in the SGS were spindle-form in shape and issued one or two proximal dendrites from each pole, the microphthalmic tecto-LGNd neurons showed an irregular contour and their dendrites were not so intensively labeled. Unilateral injections of WGA-HRP into the LP revealed that the tecto-LP neurons were mainly distributed in the ipsilateral str. opticum of the colliculus (SO) in both normal and microphthalmic animals. However, the number of labeled SO cells in the microphthalmic rat was about one-half of the normal. Furthermore, the size of labeled tecto-LP neurons was smaller than that of the normal ones, and they showed irregular round to oval cell bodies with equivocally labeled dendrites, in contrast to the normal tecto-LP neurons with polygonal cell bodies extending three or more dendrites in a radial fashion. These results indicate that there exist the tecto-LGNd and -LP projection neurons in the microphthalmic rat and that their laminally segregated projection is fundamentally preserved. However, the number of the tecto-thalamic projection neurons, especially of the tecto-LGNd cells, was markedly diminished in the mutant tectum compared to normals.

Animals↗
PubMed1985

Quantitative morphological changes in the superior colliculus and the parabigeminal nucleus in the bilaterally microphthalmic rat.

Quantitative morphological changes in the superior colliculus (SC) and the parabigeminal nucleus (PB) were studied in hereditary bilaterally microphthalmic rat, which lacks the optic nerve completely. Volumes of the retinorecipient superficial collicular layers of SC (SCS) to the central gray matter were decreased by 35% with respect to the normal. However, the cell density in SCS was increased as much as 150% of the normal. The stratum griseum superficiale was packed densely and irregularly with small-sized round nerve cells. The stratum opticum of the mutant rat appeared as a narrow band with few fiber components, but it contained some medium-sized polygonal neurons. No significant changes were found in the deeper layers of the microphthalmic SC. Bilaterally microphthalmic PB reduced both its volume and cellular density per unit area (about 30 and 75% of the normal, respectively). Furthermore, in contrast to the normal rat, the mutant PB could not be subdivided into the dorsal, middle and ventral subgroups.

Animals↗
PubMed1985

Ascending projections to the lateral thalamic nuclei from the substantia grisea centralis in the rat: a retrograde WGA-HRP study.

Ascending projections to the lateral thalamic nuclear group from the substantia grisea centralis (SGC) were studied by injections of wheat germ agglutinin-conjugated with HRP (WGA-HRP) into the laterodorsal (LD) and lateroposterior (LP) thalamic nuclei. The present study demonstrated that the pars ventralis of the SGC at the levels of the intercollicular region and of the locus ceruleus sent fibers to both the LD and LP on both sides with homolateral predominance. Distribution pattern and morphological characteristics of the LD-projection neurons in the SGC were similar to those of SGC-LP projection cells. WGA-HRP injections into the LD or LP labeled also a considerable number of neurons in the dorsal raphe nucleus and the dorsal tegmental nucleus bilaterally with homolateral predominance, but the nucleus of Darkschewitsch contained labeled neurons only after the LD injection.

Animals↗
PubMed1985

The reciprocal connections of the suprageniculate nucleus and the superior colliculus in the rat.

Reciprocally bilateral connections between the superior colliculus and the suprageniculate nucleus have been studied in the rat, using the anterograde and retrograde transport techniques of HRP. In those cases where the HRP deposit was restricted to the superficial layers of the colliculus, anterogradely labeled fibers and retrogradely labeled neurons were observed in the ipsilateral suprageniculate nucleus. However, upon HRP injection extended into the intermediate layers of the colliculus, the number of labeled fibers and neurons was not only increased ipsilaterally but were also observed in the contralateral suprageniculate nucleus. The density of the labeled fibers and the number of labeled neurons was always greater in the ipsilateral side. These results show that the suprageniculate nucleus and the superior colliculus are connected reciprocally and bilaterally, with an ipsilateral dominance.

Animals↗
PubMed1985

Amplification of activated c-Ha-ras-1 in human melanoma.

Two alleles of c-Ha-ras-1 in a human melanoma could be distinguished by restriction fragment length polymorphism, and one of them was demonstrated to be amplified 10-20 times by hybridization to a specific probe. Molecular cloning and nucleotide sequence analysis revealed that the amplified allele contained the activated c-Ha-ras-1. In the ras family, amplification of c-Ki-ras-2 and c-Ha-ras-1 has been demonstrated in several human tumors. However, the present result provides the first direct evidence that gene amplification occurs in the activated allele.

Cloning, Molecular↗
PubMed1985

Essential region for transforming activity of human c-Ha-ras-1.

An SstI fragment of 2.9 kb carrying all four coding exons of the human melanoma c-Ha-ras-1 oncogene could not transform mouse NIH 3T3 cells. Preparation of plasmid clones carrying the 2.9 kb SstI DNA and adjacent regions and analyses of the biological activities of the clones revealed that, for transforming activity of c-Ha-ras-1, a nucleotide sequence of 0.85 kb adjacent to the 2.9 kb DNA in the upstream region was required.

Animals↗
PubMed1984

Auditory and non-auditory subcortical afferents to the inferior colliculus in the rat.

Afferent projections to the rat inferior colliculus (IC) were studied by using the method of retrograde transport of horseradish peroxidase (HRP). Microinjection of HRP revealed an ordery arrangement of fiber projections between the cochlear and the central nucleus of IC; it entails a reversal of the dorso-ventral nucleotopic organization. An indistinct dorso-lateral nucleotopic projection was found between the lateral superior olivary nucleus and the central nucleus. Small number of neurons in some brainstem non-auditory structures were always labeled: the parabrachial region of the midbrain lateral tegmentum, the pars lateralis of substantia nigra, dorsal part of the central gray matter at a caudal 2/3 level of IC, and deep layers of the superior colliculus, ipsilaterally, and the spinal trigeminal and posterior column nuclei, contralaterally. Small injection restricted within the external and pericentral nuclei (cortical zone) of IC resulted in a higher distribution ratio of labeled neurons in the non-auditory structures as compared with those in the central nucleus. On the other hand, the ratio in the brainstem auditory nuclei decreased definitely after HRP-injection within the cortical zone, with an exception of the ipsilateral central nucleus of IC which contained many labeled cells following the injections in the cortical zone. The present results suggest a dual function of the inferior colliculus. The central nucleus acts as a relay station in the main auditory system, while the cortical zone, with its converging auditory, visual and somatic inputs, may act as a subcortical integration center for acoustico-motor behavior.

Afferent Pathways↗
PubMed1983

Laminar origin of the tecto-thalamic projections in the albino rat.

Cells of origin of the tecto-LP (lateroposterior nucleus of the thalamus) projection and the tecto-LGNd (dorsal nucleus of the lateral geniculate body) projection were studied in the albino rat by means of retrograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP). Tecto-LGNd neurons with small spindle form were located in the stratum griseum superficiale of the superior colliculus (SC), whereas tecto-LP neurons with polygonal shape were found in the stratum opticum of the SC.

Animals↗
PubMed1983

[3H]thymidine autoradiographic and alkaline phosphatase histochemical studies of intestinal metaplasia of the human stomach.

The relationship between cell proliferation and enzyme activity in intestinal metaplasia of the human stomach was studied using a combined method of [3H]thymidine autoradiography and alkaline phosphatase histochemistry on the same section. Three types of intestinal metaplasia were observed depending on variations in both enzymatic activity and isotope labelling. One type shows alkaline phosphatase-positive cells along the entire length of the glands with [3H]thymidine-labelled cells localized only at the bottom of the glands, resembling the duodenum. In another type of intestinal metaplasia, alkaline phosphatase-positive cells are present on the surface and/or upper half of the glands with mitotically active cells occupying the lower part of the glands. The third variety of intestinal metaplasia is characterized by the absence of alkaline-phosphatase activity and [3H]thymidine-labelled cells present in an extended zone in the lower half of the glands. Differences in labelling patterns of [3H]thymidine and the activity of marker enzyme in various types of intestinal metaplasia seem to reflect variations in cell differentiation during intestinalization of gastric mucosa.

Alkaline Phosphatase↗
PubMed1983

Hepatitis B immunoglobulin (HBIG) efficacy in the prevention of perinatal transmission of hepatitis B virus (HBV) infection.

Twelve out of 13 infants born from mothers having both HBsAg and HBeAg developed HBV carrier state within 4 months after birth. On the other hand, no babies from mothers having HBsAg and anti-HBe developed HBV carrier state. In order to prevent perinatal transmission of HBV, HBIG was administered into 14 babies born from mothers with positive HBeAg three or four times during 6 months after birth. During 12 months or more of observation period 5 out of 14 infants who received HBIG acquired active anti-HBs response after discontinuation of HBIG (passive-active immunization). However, 3 out of 14 infants unfortunately developed persistently positive HBsAg antigenemia at 12th, 14th and 14th month respectively after birth. Remaining 6 babies still have no virus markers, indicating not infected. These results indicates that HBIG administration was extremely effective for prevention of perinatal transmission of HBV. However, additional preventive measures with active immunization (HBV vaccine) seems to be necessary to prevent completely the perinatal transmission of HBV.

Carrier State↗