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H T Chang

Publications and source records attributed to H T Chang.

At least 91 records · Page 5Linked to original sources
PubMed1991

Vasoactive intestinal polypeptide (VIP) immunoreactive elements in the caudal ventral striatum of the rat: a light and electron microscopic study.

Under the posterior limb of the anterior commissure, a brain region intercalated between the ventral striatum and the ventral pallidum was previously identified as the interstitial nucleus of the posterior limb of the anterior commissure by de Olmos. This region, referred here as the caudal ventral stratum (VSc), is characterized by a dense plexus of vasoactive intestinal peptide immunoreactive (VIP+) axons. Double-fluorescence immunocytochemical reactions reveal that the dense VIP+ plexus is found in a region also rich in dopaminergic (i.e., tyrosine-hydroxylase immunoreactive) fibers but poor in enkephalinergic terminals. The dense plexuses of VIP+ axons in VSc appear to be contiguous with those in the bed nucleus of stria terminalis (BNST) and the central nucleus of amygdala (CNA). These results support the notion that this VSc region is a part of the "extended amygdala" as proposed recently by Alheid and Heimer, and confirms that its anatomical properties are closer related to the ventral striatum than the ventral pallidum. Electron microscopic analysis reveals that the VIP+ boutons form asymmetrical synapses with dendrites and spines, and symmetrical synapses with somata of unlabeled VSc neurons. The few VIP+ neurons within this area form synapses with many unlabeled axon terminals on both their somata and dendrites. Some VIP+ neurons, however, also form axosomatic and axodendritic synapses with VIP+ boutons.

Amygdala↗
PubMed1991

Abdominal tuberculosis--a retrospective analysis of 121 cases.

From 1960 to 1989, a total of 121 patients with abdominal tuberculosis were treated at this hospital. Ages, at the time of diagnosis, ranged from 14 years to 81 years with a mean of 44 years. There were 86 males and 35 females. No clinical feature was diagnostic, but the leading presenting complaints were abdominal pain (79%) and fever (53%). Chest x-ray showed that 80 patients (69%) had coexisting evidence of pulmonary tuberculosis. Lesions were most commonly located at the ileocecal region (40%). The diagnosis was bacteriologically established in only 39 patients (32%). It was difficult to obtain the definitive diagnosis, most of our patients (91 cases) were diagnosed while undergoing laparotomy with tissue biopsy. Although the principal treatment of abdominal tuberculosis was chemotherapy and operation should be reserved until complications occurred, there were still 96 patients (79%) who underwent surgical procedures. The reasons of high operative rate were the difficulty of early diagnosis and the delay of proper treatment. The common complications of abdominal tuberculosis and the related managements were discussed and the findings in our cases which were helpful in diagnosing abdominal tuberculosis were also presented. Sixteen severely ill patients who died tended to be older, poor nutrition and associated with underlying medical diseases. Abdominal tuberculosis is still persistent in Taiwan, and it must be included in the differential diagnosis of obscure abdominal conditions to avoid diagnostic delay and unnecessary illness and death.

Abdomen↗
PubMed1990

Light and electron microscopic analysis of projection neurons retrogradely labeled with Fluoro-Gold: notes on the application of antibodies to Fluoro-Gold.

Fluoro-Gold has been a very popular fluorescent tracer used recently for retrogradely labeling projection neurons. In this study we described the advantages of using antibodies to Fluoro-Gold in conventional immunohistochemical reaction protocols to further extend the usefulness of this tracer for both light and electron microscopic neuroanatomical studies.

Animals↗
PubMed1990

Firing patterns and synaptic potentials of identified giant aspiny interneurons in the rat neostriatum.

Intracellular recordings were made in vivo from 9 giant aspiny neurons in the neostriatum of urethane-anesthetized rats. The cells were identified by intracellular staining with HRP or biocytin. The neurons exhibited morphological features typical of neostriatal cholinergic interneurons. Six of the cells were obtained from intact animals, while 3 were recorded from rats with ipsilateral hemidecortications. Giant aspiny neurons were characterized by their slow irregular but tonic (3-10/sec) spontaneous activity and long-duration action potentials. Examination of the underlying membrane potential trajectories during spontaneous firing revealed that individual action potentials were triggered from spontaneous small (1-5 mV) depolarizing potentials. These spontaneous potentials exhibited the voltage sensitivity of ordinary EPSPs. They were much less frequent during the 80-200 msec pause in tonic afferent input that follows the excitation evoked by cortical or thalamic stimulation, and were decreased in frequency in decorticate animals. Their rise times and half-widths matched those expected for unitary synaptic potentials placed proximally on the surface of the neurons. Low-intensity stimulation of neostriatal afferents produced small short-latency EPSPs that appeared to be composed of responses identical to the spontaneous depolarizing potentials. The latencies of the EPSPs evoked from the cerebral cortex and thalamus were consistent with a monosynaptic input from both structures, but the maximal size of the EPSPs was much smaller than that evoked in spiny neurons, suggesting that a smaller number of afferent inputs make synapses with each of the aspiny cells. Giant aspiny neurons exhibited much larger input resistances and longer time constants than spiny neostriatal neurons. They also exhibited relatively linear steady-state current-voltage relationship compared to spiny projection cells. Input resistances ranged from 71-105 M omega, and time constants ranged from 17.8-28.5 msec. Analysis of the charging transients in response to current pulses yielded estimates of dendritic length of approximately 1 length constant. Repetitive firing of the neurons was limited by a powerful spike afterhyperpolarization and by a strong spike frequency adaptation. The sensitivity of the giant aspiny interneuron to a relatively small number of proximal afferent synaptic contacts, its tonic firing, and its widespread dendritic and axonal fields place it in an excellent position to act as a modulator of the excitability of neostriatal projection neurons in advance of the onset of movement-related neostriatal activity.

Action Potentials↗
PubMed1989

Adrenergic innervation of the substantia innominata: co-localization of phenylethanolamine N-methyltransferase and tyrosine hydroxylase immunoreactivities within the same axons.

Adrenergic input to the rat substantia innominata (SI) was studied by immunocytochemical localization of phenylethanolamine N-methyltransferase (PNMT), the synthetic enzyme for adrenaline. Using primary antibodies derived from different species, we demonstrated in double-immunofluorescence labeling experiments that all PNMT-immunoreactive fibers in SI are also immunoreactive for tyrosine hydroxylase, the synthetic enzyme for dopamine. This result indicates that the PNMT immunoreactive axons in SI are indeed adrenergic fibers.

Adrenergic Fibers↗
PubMed1989

Noradrenergic innervation of the substantia innominata: a light and electron microscopic analysis of dopamine beta-hydroxylase immunoreactive elements in the rat.

Noradrenergic input to the rat substantia innominata (SI) was analyzed in this study by immunocytochemical localization of dopamine beta-hydroxylase (DBH), the synthetic enzyme for noradrenaline. DBH immunoreactive (DBH+) axons ramified extensively within the SI and appeared to be contiguous with the DBH+ terminal fields within the bed nucleus of stria terminalis and the amygdaloid complex. DBH+ axons in the SI exhibited many large boutons en passant and boutons terminaux. These DBH+ boutons appeared much larger than those in the cerebral cortex, hippocampus, and thalamus. Electron microscopic analysis revealed that DBH+ boutons formed asymmetrical synapses with mainly dendrites, but also somata and spines of SI neurons. Dendrites which were postsynaptic to DBH+ boutons also formed synapses with many other unlabeled axon terminals. Since previous studies have shown that dendrites of SI cholinergic neurons formed few synapses, the present result suggests that the noradrenergic influence of SI cholinergic neurons may be mediated mainly by polysynaptic pathways.

Afferent Pathways↗
PubMed1989

Application of des-gamma-carboxy prothrombin as a complementary tumor marker with alpha-fetoprotein in the diagnosis of hepatocellular carcinoma.

By means of staphylocoagulase, plasma des-gamma-carboxy prothrombin (DCP) was measured in 255 subjects. Of these, 59 were healthy controls, 100 had primary hepatocellular carcinoma (PHC), 33 had cirrhosis of the liver, 16 had hepatitis, 11 had metastatic carcinoma of the liver (MCL), and 36 subjects had previously been treated with anti-vitamin K drugs. The mean plasma DCP level in the healthy subjects was 3.02 VGH U/l. Of PHC patients 80% had DCP levels greater than 6 VGH U/l, which we regarded as probably abnormal. None of the patients with benign liver diseases (cirrhosis of liver or hepatitis) had DCP greater than 10 VGH U/l. Of the patients with MCL 54.54% had DCP greater than 6 VGH U/l. In our study DCP was found to be as sensitive a tumor marker as alpha-fetoprotein (AFP) in the diagnosis of PHC and was better in distinguishing PHC from benign liver disease. Of PHC patients 92% had at least one of the two tumor markers. Simultaneous determination of DCP and AFP should be applied in mass survey programs for detecting PHC, especially in countries with a high prevalence of hepatitis B virus infection.

Biomarkers↗
PubMed1988

Substance P-dopamine relationship in the rat substantia nigra: a light and electron microscopy study of double immunocytochemically labeled materials.

The synaptic relationships between substance P-containing terminals and dopaminergic neurons (immunoreactive for tyrosine hydroxylase) in the substantia nigra were studied at both light and electron microscopic levels using a pre-embedding double-labeling immunocytochemical method. Many substance P-containing terminals were found to form synapses directly with dendrites and somata of nigral dopaminergic neurons. Since most of the substance P-containing axon terminals arise from the striatum, this result suggests that striatal substance P neurons can have monosynaptic influence on nigral dopaminergic neurons.

Animals↗
PubMed1988

Dopamine-acetylcholine interaction in the rat striatum: a dual-labeling immunocytochemical study.

The relationship between cholinergic neurons and dopaminergic axons in the rat striatum was examined by a dual-labeling immunocytochemical method. Cholinergic neurons were identified by their immunoreactivity for choline acetyltransferase (ChAT), and dopaminergic axon terminals were identified by their positive immunoreactivity for tyrosine hydroxylase (TH). Electron microscopic analysis of dual-labeled sections revealed that while most TH-positive terminals formed synapses with unlabeled striatal neurons and dendrites, a number of TH-positive terminals formed close appositions, highly suggestive of synapses, with both large and small dendrites as well as somata of ChAT-positive neurons. Tight appositions were also found between TH-positive terminals and ChAT-positive terminals. Moreover, TH-positive terminals and ChAT-positive terminals were found to form synapses with common dendrites of unlabeled striatal neurons. These results indicated that 1) dopaminergic axon terminals could interact directly with striatal cholinergic interneurons via tight appositions with distances comparable to conventional synapses; and 2) there is a convergence of dopaminergic and cholinergic axon terminals on noncholinergic striatal neurons.

Acetylcholine↗
PubMed1987

Enkephalinergic-cholinergic interaction in the rat globus pallidus: a pre-embedding double-labeling immunocytochemistry study.

The synaptic relationships between leucine-enkephalin containing axon terminals and cholinergic neurons in the rat globus pallidus were studied at both light and electron microscopic levels using a high resolution pre-embedding double-labeling immunocytochemical method. Results indicated that leucine-enkephalin terminals very rarely form monosynaptic connections with cholinergic neurons in the rat globus pallidus, suggesting that enkephalinergic neostriatal efferents probably have little monosynaptic influences on the activities of pallidal cholinergic neurons.

Animals↗
PubMed1986

Intracellular recordings from rat nucleus accumbens neurons in vitro.

Intracellular recordings were obtained from rat nucleus accumbens (NAC) neurons in brain slice preparations. Local stimulations evoked depolarizing postsynaptic potential (DPSP). Injections of low intensity depolarizing currents decreased the amplitude of the DPSP and reversed a later portion of the DPSP into a hyperpolarizing potential. Superfusion of pentobarbital facilitated the reversal of this later portion of DPSP and bicuculline abolished this polarity reversal. These data suggested that the DPSP evoked by local stimulation consisted of a combination of an excitatory and an inhibitory postsynaptic potential, and that the latter was probably mediated by gamma-aminobutyric acid.

Animals↗
PubMed1985

Projection neurons of the nucleus accumbens: an intracellular labeling study.

Projection neurons of nucleus accumbens (NAC) of the rat were identified by either antidromic activation from stimulation of midbrain ventral tegmental area-substantia nigra (VTA-SN) regions, or by tracing axons of intracellularly labeled NAC neurons into the ventral pallidum. The morphology of these NAC projection neurons were determined to be medium spiny neurons similar to those identified in the caudate-putamen.

Animals↗
PubMed1984

The ultrastructural morphology of the subthalamic-nigral axon terminals intracellularly labeled with horseradish peroxidase.

The labeled axons of neurons intracellularly injected with horseradish peroxidase (HRP) in the rat subthalamic nucleus (STH) were studied with electron microscopy. The main axons and the efferent daughter branches were all myelinated. The morphology of the intrinsic axon terminals within STH was obscured by the dark HRP reaction products, but the labeled efferent STH terminals in the substantia nigra (SN) were revealed to contain small oval vesicles and formed asymmetrical synapses with dendrites of SN neurons.

Animals↗
PubMed1983

The fine structure of the rat subthalamic nucleus: an electron microscopic study.

The normal ultrastructure of the rat subthalamic nucleus (STH) was studied. The STH consisted of tightly packed neurons distributed within a neuropil filled with large numbers of blood vessels and thinly myelinated fibers. The somata of STH neurons (diameters, D, between 10 and 25 micron) contained abundant organelles but had only a small amount of both smooth and rough endoplasmic reticulum. The nuclei had deeply invaginated nuclear envelopes and pale nucleoplasm with little heterochromatin. STH neurons often were tightly apposed without any intervening glial membranes. Similar appositions were also found between somata and dendrites, dendrites and dendrites, and dendrites and initial axon segments. Although puncta adhaerentia were often observed, no gap junctions were found on any of these membrane appositions. In the neuropil, the dendrites were mostly smooth and thin (D between 0.5 and 1 micron) with an occasional stubby spine or thin dendritic appendage. At least two types of axon terminals were identified. Type 1 terminals (D up to 1 micron) contained medium-sized round vesicles (D about 45 nm) and formed asymmetrical synapses. Type 2 terminals were often large (D up to 5 micron) and contained both round and slightly flattened vesicles (D up to 50 nm). The type 2 terminals frequently formed adherens junctions with their postsynaptic targets in addition to forming relatively symmetrical synaptic junctions. The remaining axon terminals included a small number of terminals with various morphological characteristics and possibly some tangentially sectioned type 1 and type 2 terminals. Therefore they have not been classified as individual types in this study. A quantitative analysis indicated that the type 1 terminals formed synapses mainly with thin dendrites whereas the type 2 terminals formed synapses mainly with somata and larger dendrites.

Animals↗