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Biomedical subjects

Y Kang

Publications and source records attributed to Y Kang.

At least 253 records · Page 14Linked to original sources
PubMed1986

Dual mode of projections from the parietal to the motor cortex in the cat.

The cortico-cortical projection from area 5 to area 4 gamma was studied in anesthetized cats. Intracortical microstimulation of area 5 produced EPSPs in pyramidal tract (PT) cells in area 4 gamma. Such EPSPs were analysed in a total of 54 fast PT cells. The rising phase of these EPSPs was often composed of fast and slow components. Fast-rising EPSPs (fast component) were produced predominantly by stimulation within layer III of area 5 while slow-rising EPSPs (slow component) were evoked predominantly by stimulation within layer V of area 5. The amplitudes of the fast and slow components of EPSPs produced during repetitive stimulation within layers III and V of area 5 decreased and increased, respectively, with an increase in the stimulus frequency without any appreciable changes in their latency and time-to-peak. The slow component was much less influenced by membrane hyperpolarization than the fast component. Retrogradely labeled neurons were found not only in layer III but also in layer V of area 5 following HRP injection centered on superficial layers (I-III) of area 4 gamma. It is suggested that there are two groups of cortico-cortical neurons in layers III and V of area 5, which may make monosynaptic contact with the proximal and distal sites of fast PT cells in area 4 gamma, respectively.

Animals↗
PubMed1986

[Nocardia brain abscess and ventriculitis--resistance of Nocardia to sulfonamides and susceptibility to beta-lactams].

A 31-year-old man had been healthy until the end of August, 1984 when he developed a sore throat, rhinorrhea, and high fever (39 degrees C). He was found to have hematuria and leukocytosis, though his complaints were not severe, and was not absent from his work. From the September 30, he experienced continuous pains on both temple regions and the neck. On October 6, he visited our hospital without any inflammatory signs. A screening CT scan demonstrated a ring-like enhancing mass with remarkable perifocal edema in the right temporal lobe. On emergency admission on October 9, a low grade fever (37.4 degrees C) and slight leukocytosis were noted, but not other primary lesions were present. He had normal immunological function of both humoral and cellular types. A provisional diagnosis of malignant brain tumor was made, but a possibility of brain abscess was not completely ruled out. He was initially treated with antidiuretics and steroid with prophylactic antibiotics, and underwent follow-up CT scanning. After a 10-day period with no obvious changes in CT scan, he suddenly complained of severe headache and fever, and became stuporous. A subsequent CT scan showed signs of ventriculitis, and contrast-enhancing multiloculated capsules. A lumber puncture revealed an increased number of cells, and concentration of protein in the CSF. An emergency trephination and drainage of an abscess was performed. Gram positive, acid fast, and branching fungi were found in both the smear of pus, and the samples from surrounding brain tissues. These were later identified as Nocardia asteroides in bacteriological studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

[Lymphoid adenohypophysitis, with special reference to 2 cases with sellar tumors spontaneously disappearing on the CT].

Lymphoid adenohypophysitis is an autoimmune disorder. Eighteen percent of the multipartums are reported to have autoantibodies to pituitary tissues. The symptoms in lymphoid adenohypophysitis, such as hypopituitarism and sellar tumors, exhibit spontaneous remission. The pituitary is a feasible target organ in other autoimmune diseases of the endocrine system. Of these patients, 19/287 showed a positive immune reaction with pituitary tissue antigens. Our three female patients with sellar and suprasellar mass were clinically diagnosed as having lymphoid adenohypophysitis, because of the spontaneous regression of tumors, or presence of immunologically and endocrinologically abnormal findings. The first case was a 31-year-old woman who had amenorrhea and galactorrhea syndrome for two years after delivery of her second child. CT scan revealed a supraseller enhanced mass lesion. She had concomitant signs of recurrent meningeal irritations. The number of cells in the CSF increased, though the protein concentration increased only slightly. During a one-year close observation, the suprasellar mass spontaneously regressed. The second patient was a 66-year-old woman. In 1945, she underwent hysterectomy and oophorectomy for appendicitis followed by adnexitis. She was admitted because of episodes of headache, vomiting and visual field defect in 1983. CT scan also showed a contrast enhanced mass in the suprasellar region. She had two episodes of high fever. After the treatment with antibiotics and anti-inflammatory agents for 4 months, the tumor disappeared. The third case was a 20-year-old female. She had neither neurological nor endocrinological abnormality, except for attacks of vertigo, nausea and vomiting.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Synaptic actions of the ventral root afferents on cat hindlimb motoneurons.

Postsynaptic potentials (PSPs) with long latencies were evoked in cat hindlimb motoneurons by stimulation of the distal stump of a cut ventral root. Measurements of their latency and the threshold in the responsible afferent fibers showed that they were produced mainly by the activity of the unmyelinated fibers in the ventral root that enter the spinal cord through the dorsal root. Patterns of PSPs evoked in flexor and extensor motoneurons by ventral root stimulation were similar to those observed in the flexion reflex.

Animals↗
PubMed1985

Frequency-to-voltage conversion in the pyramidal tract neuron: an important role of the inhibitory postsynaptic potential.

Frequency-coded impulses are known to be converted into postsynaptic potentials (PSPs) at the synapse of a target neuron. This can be termed frequency-voltage (F-V) conversion. Studies on this problem in pyramidal tract neurons (PTNs) showed that not only the amplitude but also the duration of depolarizing PSPs was determined as a function of the input impulse frequency. Two opposite patterns of F-V conversion were observed following activation of two input systems to PTNs. Inhibitory postsynaptic potentials were found to play an important role in the regulation of the duration of PSPs by curtailing excitatory post-synaptic potentials.

Animals↗
PubMedDate not supplied

Trans-synaptically induced bursts in regular spiking non-pyramidal cells in deep layers of the cat motor cortex.

In deep layers of the cat motor cortex, we have investigated the properties of neurons displaying trans-synaptically induced bursts. In in vivo experiments, extracellularly recorded burst neurons were separated into two subtypes based on their dependence on stimulation sites, the medullary pyramid or the ventrolateral (VL) thalamic nucleus, from which bursts of 10-20 spikes were triggered. The spike amplitude attenuation and frequency adaptation during a burst were more prominent in pyramid-dependent burst neurons than in VL-dependent burst neurons. Intracellular recordings in in vivo experiments revealed that pyramid-dependent bursts emerged from a long-lasting depolarization, while each spike during a VL-dependent burst was narrow in half-width and was followed by a fast AHP, similar to fast spiking neurons. In in vitro slice experiments, intracellular recordings were obtained from neurons that displayed a burst of attenuated spikes emerging from a long-lasting depolarization, and were also obtained from fast spiking neurons. They were morphologically recovered to be multipolar cells with sparsely spiny dendrites and local axonal networks, suggesting that they are inhibitory interneurons. The multipolar neurons displaying bursts of attenuated spikes may mediate the recurrent inhibition of pyramidal tract cells.

Adaptation, Physiological↗
PubMedDate not supplied

Modulation of T cell function by alpha-fetoprotein: An in vivo study on porcine thyroid peroxidase-induced experimental autoimmune thyroiditis in transgenic mice producing human alpha-fetoprotein.

Experimental autoimmune thyroiditis was induced in transgenic mice (TG-3) producing human alpha-fetoprotein (AFP) and in control mice by immunization of porcine thyroid peroxidase (TPO). Development of thyroiditis accompanied with mononuclear cell infiltration was observed in 6 out of 8 treated control mice. In contrast, the development was significantly suppressed in TG-3 mice and mild histologic change was observed in only 1 out of 8 TG-3 mice (p < 0. 05). Serum anti-TPO antibody titers gradually increased in TG-3 mice as well as in control mice and there were no significant differences. In vitro phytohemagglutinin response of splenocytes from TG-3 mice was lower than that from control mice. Significantly reduced numbers of CD4+ and CD8+ splenocytes, total thymocytes, and CD4+ thymocytes were found in the nontreated TG-3 mice as compared with those in control mice. These results suggest that ubiquitously produced AFP modulates in vivo T cell development and/or T cell-dependent immune responses.

Animals↗
PubMedDate not supplied

Analysis of epitopes of mouse monoclonal antibodies against human alpha-fetoprotein.

Thirty-six monoclonal antibodies (MAbs) against human alpha-fetoprotein (AFP) were analyzed for the location of their epitopes by reacting them with a set of yeast recombinant AFP proteins using ELISA. Recombinant AFP proteins containing either one, two or all three domains, i.e. domain I, domain III, domain I-II, domain II-III and domain I-II-III, were produced and secreted into the culture medium of yeast cells harboring the expression plasmids. Epitopes of 13 MAbs were localized on domain I and 17 others were on domain III. However, the exact location of the epitopes of the remaining 6 MAbs could not be defined. The epitope of an antibody, namely AFY6, which was located in domain I, was successfully mapped on an octapeptide, C175KAENAVE182, using synthesized overlapping octapeptides.

Animals↗
PubMedDate not supplied

Handedness and footedness in Korean college students.

This study was conducted to obtain normative data on foot preference and to compare footedness and handedness in a large sample (N = 866) of college students in Korea, where left-hand use for writing and other public acts is severely restricted (Kang & Harris, 1993). Based on scores from Korean-language versions of the Edinburgh Handedness Inventory (EHI; Oldfield, 1971) and the Waterloo Footedness Questionnaire Revised (WFQ-R; Elias, Bryden, & Bulman-Fleming, 1988), 11% of the subjects were left-footed but only 4.2% as left-handed. A significantly higher percentage of left-handers than right-handers showed crossed lateral preference, that is, for preference of the opposite-side foot. Of the left-handers with crossed preference, the majority were inconsistent left-handers (ILH; Peters & Servos, 1989), whereas most of those with uncrossed preference were consistent left-handers (CLH). Factor analysis of the EHI and WFQ-R revealed 2 handedness factors and 2 footedness factors. The footedness factors for skilled unipedal actions and for balancing-stabilizing varied in direction, strength, and relation to handedness in mixed-footers and left-handers, consistent with the possibility that the division of footedness into these categories might be neuropsychologically meaningful.

Adult↗
PubMedDate not supplied

Indomethacin reduces lung adenoma number in A/J mice.

The effects of indomethacin on A/J mice were investigated. The non-steroidal antiinflammatory drug (NSAID) indomethacin reduced significantly the number of lung adenomas 3, 4 or 8 months after urethane injection by 28, 30 and 29% respectively. The density of apoptotic cell bodies increased 2.9-fold in the lung adenomas of A/J mice treated with indomethacin. By immunocytochemistry, COX-2 immunoreactivity was present in the cytosol of lung adenomas, and in epithelial cells lining the bronchioli and bronchus as well as type 2 alveolar cells. COX-1 immunostaining was similar to that of COX-2 in the lungs of urethane-injected mice treated with or without indomethacin. By RT-PCR, COX-1 and COX-2 PCR products were present in mouse lung adenomas, alveoli and bronchioli. These results suggest that indomethacin may inhibit COX-1 and COX-2 in the A/J mouse lung resulting in reduced adenoma formation.

Adenoma↗
PubMedDate not supplied

Thrombelastography as an aid to regional anesthesia: preliminary communication.

Thrombelastography (TEG), a less commonly available technique used to assess hemostatic function, has recently gained popularity. Analysis of TEG yields qualitative information about platelet function, thromboplastin generation and their interaction with the intrinsic cascade to form a stable clot. Additional information is obtained about fibrinogen and Factor XIII levels as well as the fibrinolytic system. TEG has been shown to be more sensitive and accurate than traditional coagulation tests at both predicting and treating coagulopathies. We report here three cases in which TEG was used to assess hemostatic function in patients at risk for bleeding prior to the induction of regional anesthesia. In all three cases, traditional tests were inadequate to predict the safe practice of regional anesthesia. TEG provided this information and regional anesthesia was successfully employed.

Aged↗