Biomedical subjects

J Hámori

Publications and source records attributed to J Hámori.

At least 19 recordsLinked to original sources

PubMed2005

Calretinin-immunoreactive unipolar brush cells in the developing human cerebellum.

We have studied the temporal and spatial characteristics of the development of unipolar brush cells (UBCs) in the human cerebellar vermis. Consistently with previous studies in rodents and cat, we have found that unipolar brush cells appear at a relatively late phase of cerebellar development and their development continues up to and beyond the first postnatal year. A series of 23 normal human brains, including 5 adult and 18 fetal or infant brains (between the 24th gestational week and the 11th postnatal month) were used. In order to visualize unipolar brush cells, calretinin-immunocytochemistry was performed on formaldehyde-fixed, paraffin-embedded blocks of the cerebellar vermis. Our results show that calretinin-immunoreactive unipolar brush cells are not yet present in the cerebellar vermis at the 28th gestational week. At birth, they are present in a relatively small number, mostly in the vestibular lobules. At the 3rd, 5th, 8.5th and 11th postnatal months the number of calretinin-immunoreactive unipolar brush cells gradually increase, first appearing in the vestibular lobules, followed by the invasion of the later developing vermal lobules, spreading in a rostro-caudal and proximo-distal direction. Although at the 11th postnatal month unipolar brush cells exhibited adult-like morphological and distributional features, their number appeared to be lower than in the adult cerebellum. The late maturation of unipolar brush cells implies that the cytoarchitectonical development of the human cerebellum is not completed by the end of the first postnatal year.

Aged↗

PubMed2005

Delayed postnatal settlement of cerebellar Purkinje cells in vermal lobules VI and VII of the mouse.

The postnatal development of the ganglionic (Purkinje) layer was studied in the mouse cerebellum from P0 to young adulthood with special emphasis to vermal lobules VI-VII (oculomotor vermis) in the mouse. In order to visualize Purkinje cells (PCs), toluidine blue staining of resin-embedded semithin sections and calbindin immunohistochemistry were utilized. The number of PCs in the whole cerebellum was 199,080+/-2966 at postnatal day eight (P8), 222,000+/-2979 at P20 and nearly the same, 225,800+/-7549 in young adults; i.e., there was an approximately 13.4% increase of PCs between P8 and adults. The number of PC somata aligned into a rostrocaudal stripe along the developing ganglionic layer increased by about 24% in vermal cerebellar lobule III but much more markedly (i.e., by 49%) in VI+VII between P6 and young adulthood. Between P6 and P16, the increase of the number of PCs in the ganglionic layer of lobules VI and VII resulted in the (delayed) completion of PC layer, caused by the (late) alignment of rostrocaudally dispersed PCs, although late postnatal migration of a smaller population of these cells cannot be excluded either. It is concluded that the oculomotor vermis belongs to the latest developing cerebellar cortical structures, which could be the reason for its frequent involvement in developmentally related disturbances and disorders.

Animals↗

PubMed2005

Quantitative analysis of the postnatal development of Purkinje neurons in the cerebellum of the cat.

We have studied the postnatal quantitative changes of cortical Purkinje neurons in the cerebellum of the cat at the following postnatal groups of age: P0, P42, P72 and adults. An unbiased counting method, the optical fractionator was used for the estimation of Purkinje cell numbers. A significant increase of Purkinje cell number was found between P0 (1.097 x 10(6)) and P42/P72 (1.805 x 10(6) and 1.895 x 10(6)) declining to 1.429 x 10(6) in the adult, still 30% higher than in the newborn. It was also observed that during the first few postnatal weeks large "gaps" were present in the Purkinje monolayer as revealed by Nissl staining and metabotropic glutamate receptor 1alpha immunocytochemistry. These Purkinje cell gaps were observed most frequently in well-definable areas, especially in the intermediate zone of the neocerebellum. Simultaneously with the numerical increase of Purkinje neurons between the P0 and P72 age groups, these gaps disappeared after the third postnatal week resulting in the completion of the Purkinje monolayer in the whole cerebellum.

Age Factors↗

PubMed2002

Number of GABA immunonegative and GABA immunopositive neurons in human epileptic temporal cortex.

The number of neurons, both GABA immunopositive and immunonegative, was determined in temporal epileptic foci of 7 patients after temporal lobectomy, and compared to neuronal numbers in temporal cortex of two controls taken from tumor operated patients. The thickness of the cortex of the epileptic cortex diminished by about 10%, while the number of nerve cells decreased to 67% of that of the control value: it was 19.000/mm(3) vs. 28.000/mm(3) found in the control. This decline was due to cell degeneration, which, however, was more severe for non-GABAergic nerve cells. Accordingly, the proportion of the GABA-positive neurons in the otherwise diminished neuronal population increased to 36.4% from the 32% control value. The number of GABAergic terminals, however, decreased even further, explaining the resulting disinhibition during epileptic seizures.

Epilepsy↗

PubMed2001

Distribution and action of some putative neurotransmitters in the stomatogastric nervous system of the earthworm, Eisenia fetida (Oligochaeta, Annelida).

The chemical neuroanatomy of the stomatogastric nervous system of the earthworm, Eisenia fetida, has been investigated, using antibodies raised against serotonin, tyrosine hydroxylase, octopamine, GABA, FMRFamide, proctolin, Eisenia tetradecapeptide and neuropeptide Y. Neurons immunoreactive to these antibodies can be observed in the stomatogastric ganglia. The labelled cells comprise altogether 95.4% of the total number of neurons in the ganglion. Immunoreactive projections were followed between stomatogastric individual ganglia as well as towards the enteric plexus. Intrinsic neurons containing the different signal molecules examined are present along the entire length of the enteric plexus, but serotonin immunoreactive perikarya were only found in the hindgut. The density of the different immunoreactive neurons, except the serotonin ones, is highest in the pharyngeal plexus, and the number of labelled neurons decreases along the alimentary canal towards the hindgut. A number of epithelial cells also reveal tyrosine hydroxylase, octopamine, GABA and Eisenia tetradecapeptide immunoreactivity. The action of some putative neurotransmitters, such as dopamine, octopamine, serotonin and proctolin was tested on foregut preparations. Dopamine and octopamine (10(-6)-10(-4) M) have an excitatory effect on the musculature, whereas the effect of serotonin depends on the actual muscle tension. Following precontraction evoked by acetylcholine, serotonin in low concentrations (10(-7)-10(-6) M) causes relaxation, whereas in higher (10(-4) M) concentration it evokes slight contractions. In preparations at basal tone, serotonin (10(-7)-10(-6) M) evokes contractions of the foregut. Atropine strongly inhibits the action of acetylcholine but is ineffective against serotonin, dopamine and octopamine. Similarly, the Na+ channel blocker tetrodotoxin fails to influence the contractile effect of dopamine, octopamine and serotonin. These results suggest that dopamine, octopamine and serotonin act directly on the muscle cells of the alimentary tract. Proctolin do not evoke any significant effect on the foregut.

Animals↗

PubMed2000

Postnatal development of unipolar brush cells in the cerebellar cortex of cat.

The postnatal developmental distribution pattern of metabotropic glutamate receptor (mGluR1a) immunoreactive unipolar brush cells (UBCs) was studied in the cerebellar cortex of kittens. On the day of birth (P0) UBCs are already present in the white matter in lobule X of the vermis, but only a few of these cell seemed to migrate to the deeper region of the internal granular layer. By the end of the first week (P8) UBCs were seen to invade the white matter + internal granular layer of lobules IX, VIII, I, and II of the vermis, and they spread further in the transitory area medio-laterally from the vermis toward the cerebellar hemispheres. By P15, UBCs appeared in lobules III and VII of the vermis, as well as in corresponding lobules of the neocerebellum, with especially high numbers in lobule VII. By P22, UBCs migrated further after their medio-lateral course in the neocerebellum, and began to invade lobules V and VI. At P62 the amount of UBCs in midsagittal planes of early developing vermal lobules (I, II, VII-X) resembled the P132 or adult pattern. The medio-lateral migration and incorporation of UBCs into the late-developing cerebellar lobules V and VI was completed only by P132, when the spatial distribution of UBCs in both the vermal and neocerebellar lobules was comparable to that seen in the 1 year old young adult cat. Although by P132 the postnatal migration of the vast majority of UBCs seemed to be completed, in the cerebellum of adult cats a few migrating UBCs could still be observed in the white matter of the cerebellar lobules, and beneath the ependyma of the fourth ventricle. It is concluded that during ontogenesis the migration course of UBCs follows essentially the developmental sequence of cerebellar lobules, although the incorporation of UBCs into the internal granular layer continues until 4 months postnatally, i.e., much beyond the apparent completion (about two months postnatally) of cytoarchitectonic built up of the cerebellar cortex of kittens.

Animals↗

PubMed2000

Innervation of a single vibrissa in the whisker-pad of rats.

Innervation of the gamma straddler vibrissa and distribution of individual gamma vibrissal sensory nerve fibers within infraorbital nerve branches were investigated in adult rats. In the close vicinity (2 mm) of the whisker-pad, one-fifth of the nerve fibers innervating the gamma vibrissa were still located in nerves to neighboring (beta, delta, C1 and D1) whiskers, while one-tenth of the innervating fibers were placed in nerves of more distant sinus hairs. This convergence of gamma vibrissal sensory nerve fibers to single vibrissa from neighboring nerves is suggested to be a consequence of overlapping vibrissal representation in the Gasserian ganglion.

Amidines↗

PubMed2000

Reorganization of peptidergic systems during brain regeneration in Eisenia fetida (Oligochaeta, Annelida).

After the extirpation of the brain reorganization of the peptidergic (FMRFamide, neuropeptide Y, proctolin) systems was studied in the newly forming cerebral ganglion of the annelid Eisenia fetida. During regeneration, all immunoreactive fibres appear on the 1st-2nd postoperative day. At the beginning of regeneration, immunoreactive neurons and fibres form a mixed structure in the wound tissue. On the 3rd postoperative day, FMRFamide positive and neuropeptide Y-immunoreactive, while on the 7th postoperative day proctolin-immunoreactive neurons appear in the loose wound tissue. From the 25th postoperative day a capsule gradually develops around it. The neurons of the preganglion move to the surface of the newly appearing preganglion. The number of these cells gradually increase, and by the 72th-80th postoperative days the localization and number of peptide-immunoreactive neurons is similar to that in the intact one. The neurons of all examined peptidergic systems may originate from the neuroblasts, situated on the inner and outer surface of the intact ganglia (e.g. suboesophageal and ventral cord ganglia). In addition FMRFamide and proctolin immunoreactive neurons may take their derive by mitotic proliferation from the pharyngeal neurons, too.

Animals↗

PubMed1999

Metabotrop glutamate receptor type 1a expressing unipolar brush cells in the cerebellar cortex of different species: a comparative quantitative study.

Morphology, distribution and number of unipolar brush cells (UBCs) was studied in the cerebellar vermal lobules I-X of the chicken, rat, guinea pig, cat, and monkey using monoclonal mGluR1a antibody as a marker to visualise these recently described nerve cells (Mugnaini and Floris [1994] J. Comp. Neurol. 339:174-180; Mugnaini et al. [1994] Synapse 16:284-311). The morphological appearance of mGluR1a immunopositive UBCs is similar in all species investigated: they are small cells, having a single, relatively short and thick dendrite, terminating in brush-like dendrioles. Although this, probably excitatory, cell type can be found all over the cerebellar cortex, highest density of UBCs can be seen in the vermal cortex. The present study, therefore, was focused on the quantitative morphology and distribution of UBCs in the 10 lobules of the vermis. Calculating the number of UBCs/l Purkinje cell (PC), we have found differences in this value (average in vermal lobules I-X) from 1.04 in rat, 1.10 in chicken, 1.16 in guinea pig, 2.27 in monkey, and up to 2.44 in cat. The highest density of UBCs was observed in lobules I, IX, and X, whereas the lowest number of UBCs/l PC was found in lobules IV-VI (in the mammals) and in lobules VII-VIII (in the chicken). In mammals, particularly the monkey and cat, an increased presence of UBCs was observed in vermal sub-lobules VIc-VIIb,c, a region defined as the oculomotor vermis because of its role in the control of saccadic eye movement. There is also a basic difference between chicken and mammals in the distribution of UBCs within the lobules: in mammals, the lowest density of these nerve cells was found in the peripheral portion of the lobules, near to the pia, while in the chicken, in contrast, the density of UBCs was the highest subpially with fewer UBCs located in the deepest curvature of the lobules. Finally, the functional significance of the differences in the density and in the distribution pattern of UBCs in the cerebellar vermis between the phylogenetically different species investigated is briefly discussed.

Animals↗

PubMed1999

Immunocytochemical mapping of NPY and VIP neuronal elements in the cat subcortical visual nuclei, with special reference to the pretectum and accessory optic system.

The aim of this study was to describe the distribution patterns of neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP)-immunoreactive (ir) neuronal elements in subcortical visual centers of the cat. Numerous NPY-ir neurons were present in the feline nucleus of the optic tract and in the anterior pretectal nucleus. Only a few NPY-ir neurons were found in the posterior, medial and olivary pretectal nuclei and in the accessory optic nuclei. Diffuse and heavily beaded NPY-ir fiber plexuses were observed throughout the superior colliculus, pretectum, and accessory optic system. Extensively arborising NPY-ir fibers were present in the mesencephalon and ventral lateral geniculate nucleus, while the dorsal visual thalamic nuclei contained only a few NPY-ir fibers. VIP-ir cells were present mainly in the accessory optic nuclei, and they were absent in the dorsal visual thalamus. Both NPY- and VIP-ir neurons were multipolar and fusiform in shape in the regions studied. Enucleation did not alter the appearance of NPY- and VIP-containing neuronal elements in the superior colliculus and pretectum while in the thalamus a subset of NPY-ir fiber population disappeared, indicating their retinal origin. Although there is a partial overlap in the topographical localization of the NPY- and VIP-ergic neurons in the pretectum, the colocalization of the two peptides could not be demonstrated. The present observations demonstrate the existence of two different and separate peptidergic (NPY and VIP) neuronal populations in the pretectum.

Animals↗

PubMed1998

Contralateral cortical projection to the mediodorsal thalamic nucleus: origin and synaptic organization in the rat.

The origin of the corticothalamic projections to the contralateral mediodorsal nucleus, the collateralization of cortical fibers and their synaptic organization in the ipsi- and contralateral mediodorsal nuclei were investigated in adult rats with double retrograde fluorescent and anterograde tracing. After tracer injections in the mediodorsal nuclei on either side, neurons were retrogradely labeled in all the areas of the contralateral prefrontal cortex in which ipsilateral labeling was also observed. Contralateral corticothalamic cells accounted for 15% of the labeled neurons in the orbital and agranular insular areas, while their proportion was lower (3%) in the anterior cingulate cortex. Up to 70% of the contralateral cortical neurons were double labeled by bilateral injections in the mediodorsal nuclei. At the electron microscopic level, unilateral injections of biotinylated dextran-amine in the orbitofrontal cortex resulted in anterograde labeling of small terminals and a few large boutons in the ipsilateral mediodorsal nucleus, while only small boutons were identified contralaterally. The diameter of postsynaptic dendritic profiles contacted by labeled small cortical endings was significantly larger in the ipsilateral mediodorsal nucleus than contralaterally. These findings demonstrate that dense contralateral cortical projections to the mediodorsal nucleus derive from the orbital and agranular insular areas, and that crossed corticothalamic afferents are mostly formed by collaterals of the ipsilateral connections. Our observations also point out the heterogeneity of corticothalamic boutons in the rat mediodorsal nucleus and morphological differences in the synaptic organization of prefrontal fibers innervating the two sides, indicating that ipsilateral cortical afferents may be more proximally distributed than crossed cortical fibers on dendrites of mediodorsal neurons.

Animals↗

PubMed1997

Octopamine-containing neurons in the alimentary tract of the earthworm (Eisenia fetida).

Octopamine-containing nerve cells have been demonstrated in the enteric plexus of the earthworm (Eisenia fetida), applying immunocytochemistry and HPLC assay. A few octopamine-immunoreactive neurons occurred in the fore- and hindgut, whereas their number in the midgut was considerably greater. Octopamine levels detected by HPLC correlated with the distribution of octopamine-containing nerve cells. A regulatory role for these intrinsic octopaminergic neurons is suggested in the enteric plexus in the earthworm alimentary tract. This is the first report on the occurrence of octopamine-containing nerve cells in the peripheral nervous system of an invertebrate.

Animals↗

PubMed1997

Distribution of metabotropic glutamate receptor type 1a in Purkinje cell dendritic spines is independent of the presence of presynaptic parallel fibers.

The metabotropic glutamate receptor type 1a (mGluR1a) is expressed at a high level in the molecular layer of the cerebellar cortex, where it is localized mostly in dendritic spines of Purkinje cells, innervated by parallel fibers. Treatment with methylazoxymethanol (MAM) of mouse pups at postnatal days (PND) 0 + 1 or 5 + 6 results in the partial loss of granule cells, the extent of which depends on the age of the animal at the time of injection. As a consequence of hypogranularity, the number of parallel fibers is decreased to such an amount that many of the postsynaptic Purkinje cell dendritic spines are devoid of axonal input, and only a limited number of spines participate in the formation of parallel fiber synapses, or, infrequently, in heterologous or heterotopic synapses with other presynaptic partners. At PND 30, 50% of the spines in the cerebella of mice treated with MAM at PND 0 + 1 was not contacted by any presynaptic element, compared to 5% in controls or 15% in the cerebella of mice treated with MAM at PND 5 + 6. The localization of mGluR1a was visualized by immunocytochemistry on ultrathin sections: approximately 80% of all Purkinje cell dendritic spines were immunopositive in controls and in both groups of MAM-treated mice, indicating that mGluR1a was present in Purkinje dendritic spines even when the corresponding synaptic input was absent. This observation indicates that the expression and subcellular distribution of mGluR1a are inherent, genetically determined properties of Purkinje cells.

Aging↗

PubMed1997

Light and electron microscopic demonstration of mGluR5 metabotropic glutamate receptor immunoreactive neuronal elements in the rat cerebellar cortex.

The cellular and subcellular localization of the mGluR5 metabotropic glutamate receptor subtype was studied in the rat cerebellar cortex, by using the preembedding immunoperoxidase and immunogold techniques. Light microscopic observations revealed an abundant, intense labeling of neurons in the granular layer as well as in the molecular layer. Lugaro and Golgi cells exhibited an intense mGluR5 immunoreactivity, while only a fraction of the neurons in the molecular layer were found to be mGluR5 immunopositive. In addition to a dense plexus of immunoreactive dendrites in the molecular layer of the cerebellar cortex, the mGluR5 immunopositive Golgi cell dendrites resembling axons at the light microscopic level were also labeled in the granular layer. At the ultrastructural level, mGluR5 immunoreactivity was present in neuronal elements postsynaptic to axon terminals of different morphology. By using a pre-embedding immunogold method, it was found that mGluR5 immunoreactivity is accumulated at the plasma membranes extrasynaptically as well as at the periphery of the postsynaptic specializations, mainly of the parallel fiber synaptic contacts. These findings provide morphological evidence that mGluR5 is expressed by a population of neurons in the cerebellar cortex and can synaptically be activated via the parallel fiber system.

Animals↗

PubMed1997

The role of different tumor markers in the early diagnosis and prognosis of pancreatic carcinoma and chronic pancreatitis.

The examination of tumor markers in the diagnosis and in the evaluation of progression of tumors has got an increasing significance. The serum level changements of three tumor markers (CEA, CA 19-9, CA 125) were examined before and after the operation in 94 patients operated for pancreatic carcinoma (PC) and chronic pancreatitis (CP) between March 1994 and December 1996 at the 2nd Dept. of Surgery of Debrecen Medical University. From the patients 62 were operated for carcinoma, in 19 cases the tumor was resectable, 43 patients had palliative operation. In 32 patients ductal decompression was performed because of CP. The authors evaluate the serum level changements of the three tumor markers examined in three groups of patients before and after the operation. In conclusion CA 19-9 is the most sensitive marker of PC, the sensitivity was 77.4%, the specificity was 87.5%. CEA and CA 125 are not as sensitive markers of PC as CA 19-9, while CEA and CA 125 serum levels are both increased in half of the patients with chronic pancreatitis.

Adult↗

PubMed1997

Surgical treatment of pancreatic head and periampullary tumors.

The aim of this study was the comparison of the postoperative results of standard Whipple pancreatoduodenectomy (WP), pylorus preserving pancreatoduodenectomy (PPPD) and palliative bypass operation performed for treatment of pancreatic head and periampullary tumors. In the period from Jan. 1992 to 1996 106 patients had tumors located in the head of pancreas and 21 patients had periampullary tumors. The diagnosis was established by ERCP, transabdominal ultrasonography and computer tomography. We assessed the morbidity, mortality, prognostical data of the surgery of pancreatic head and periampullary tumors. Tumor markers such as CEA, CA 19-9 and CA 125 were also studied. The operability rate was 26% in case of pancreatic head tumors and 69% in peri ampullary tumors. The mortality rate was 6%. Postoperative complications were in 23 patients(18.1%). There was no significant difference between the survival of WP and PPPD group, but we found much better survival in patients with periampullary tumor. After palliative operation the survival rate was 6.1 months in case of pancreatic head carcinoma and 11 months in case of periampullary tumors. Our data provided many evidences about the advantage of PPPD in the patients with malignant periampullary and pancreas head tumors and the long-term results and quality of life is much better after PPPD.

Ampulla of Vater↗

PubMed1996

Light and electron microscopic analysis of synaptic input from cortical area 17 to the lateral posterior nucleus in cats.

The morphology and synaptic organization of the corticothalamic (CT) fibres from area 17 were studied in the lateral posterior nucleus (LP) of the thalamus in cats. Injection of the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHAL) into primary visual cortex labelled a band of CT fibres in the LP with terminal field confined to its lateral division "LP1". PHAL-labelled CT axons in the LP1 gave rise to both en passant and terminal boutons. They usually established several synaptic contacts--often in complex glomerulus-like synaptic arrangements--with dendritic shafts of large diameter and presynaptic dendrites containing pleomorphic vesicles. Postsynaptic targets of the PHAL-labelled CT boutons were characterized by postembedding gamma-aminobutyric acid (GABA) immunocytochemistry. It appeared that, in the LP1 of the cat, almost half (44.5%) of the postsynaptic dendrites to CT boutons from area 17 belonged to the GABA-immunopositive interneurons and the majority (41%) of these GABA-immunopositive dendrites were F2 terminals. These results indicate that the CT axons from the striate cortex in the LP of the cat, in addition to a direct excitatory action, exert a powerful feed-forward inhibition on the thalamic principal cells.

Animals↗

PubMed1996

Immunocytochemical localization of mGluR1a metabotropic glutamate receptor in inhibitory interneurons of the cerebellar cortex.

Immunocytochemical investigation of metabotrop glutamate receptor la in the cerebellar cortex of rat revealed a presence of this receptor in all cortical inhibitory nerve cells (Purkinje, basket, stellate, Lugaro and Golgi). In addition to the previously described localization of this receptor in Purkinje dendritic spines supplied by parallel and climbing fibres and considered to be responsible for cerebellar long-term depression, we have observed metabotropic glutamate receptor la immunopositivity also in the synapses between parallel fibres and dendrites of basket, stellate and Golgi neurons. The postsynaptic receptor was also present occasionally in inhibitory synapses between stellate cell axons and Purkinje cells as well as between Purkinje axon collaterals and Lugaro cell dendrites. The possibility, that mGluR1a receptors in basket, Golgi and stellate cells might directly or indirectly contribute to cerebellar LTD, is discussed.

Animals↗