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Biomedical subjects

H Ryu

Publications and source records attributed to H Ryu.

At least 109 records · Page 6Linked to original sources
PubMed1986

Immunogenicity of potassium thiocyanate extract of type A Pasteurella multocida.

The immunogenicity and cross-protectivity of potassium thiocyanate (KSCN) extracts from Type A Pasteurella multocida strains were evaluated in mice. Mice administered KSCN extracts showed signs of depression for several hours following immunization. These extracts induced protection against challenge with the virulent homologous bacterium although many of the surviving mice were clinically ill up to 72 h after challenge exposure. There was no consistent reciprocal protection between different strains of the serotype indicating lack of correlation between serotype and cross-immunogenicity. Antigenic analysis of KSCN extracts by crossed immunoelectrophoresis techniques revealed greater than or equal to 25 different antigenic components. When the antigenic content of P-2383 and P-1062 KSCN extracts were compared, most antigenic components were common to both; however, two strain-specific and antigenic components were identified with homologous and heterologous antisera. One component present in each of the extracts gave a precipitation line similar to that produced by a crude lipopolysaccharide extracted from the organism. This component was isolated by sucrose density gradient centrifugation. The component isolated from P-2383 KSCN extract sedimented rapidly, indicating a high molecular weight material, and contained 12% carbohydrate and 27% protein. Immunization of mice with this component induced resistance to challenge with the homologous strain and some degree of protection against certain heterologous strains.

Animals↗
PubMed1986

[Effects of halothane on sensory evoked potentials].

Intraoperative monitoring of central nervous system functions is useful for safe neurosurgical operations. For such a purpose, some kinds of sensory evoked potentials play significant roles, but their reliability during general anesthesia have not yet been established. The authors conducted experimental and clinical studies to reveal effects of halothane, a most popular anesthetic, on sensory evoked potentials. Eight adult cats, weighing 2.8-4.0 kg, were induced to anesthesia with thiopental and ether, and after tracheostomy and venous cannulation, they were immobilized with succinylcholine and artificially ventilated with mixture of oxygen, nitrous oxide halothane. The concentration of halothane was increased up to 4.0% by 0.5% steps. The body temperature, systemic blood pressure and carbon dioxide concentrations in expires gas were monitored continuously, and maintained within normal ranges as much as possible. The hypotension induced by halothane was easily corrected by dopamine infusion initially, but later became difficult to be controlled as the halothane concentration increased. In each concentration, short latency somatosensory evoked potentials by median nerve stimulations (SL-SEP), and brain stem auditory evoked potentials (BAEP) were recorded. Active electrode was placed on the bregma, and reference electrodes were placed on a hindlimb for SL-SEP, on the tongue for BAEP recordings. Peak amplitudes of SL-SEP were gradually decreased and finally disappeared without apparent dose dependency. Relatively the peaks with longer latencies were more affected than those with shorter latency such as P1 and N1. In BAEP, decrement of the amplitude was apparent in the peaks with longer latencies with an obvious dose dependency.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗
PubMed1985

[Facial nerve neurinoma--report of 2 cases].

Two cases of facial nerve neurinoma (VII-Nm) were reported. The first case is a 41-year-old man who had 16 years of history of slowly progressive right facial palsy and hearing disturbance. The tumor originated in horizontal portion of the right facial nerve, and extended epidurally into the middle cranial fossa, as well as medially along the facial canal to the C-P angle. The second case is a 55-year-old man with 16 years of history of progressive right facial palsy which was followed by hearing disturbance. The tumor was found in the vertical portion of the right facial nerve, expanding in the petrous bone. Both tumors were removed surgically. 116 VII-Nm were reported in the literature including our 2 cases. Most were reported in the ENT field, and only 11 cases in the neurosurgical field. Facial palsy or hearing disturbance is the initial symptom, depending on the site of origin in the facial nerve. VII-Nm can originate in any part of the facial nerve. The most common part of origin is the vertical portion where the tumor tends to expand locally, but it may extend extracranially along the facial canal. The tumor which originates in the tympanic portion tends to extend into the middle ear cavity. The tumor originating in the horizontal portion extends to the epidural space in the middle cranial fossa and/or medially along the facial canal. VII-Nm in the cisternal portion of the facial nerve extends to the posterior cranial fossa and produces the signs of C-P angle tumor. Unlike the acoustic neurinoma, VII-Nm is associated with marked facial palsy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Effect of type A Pasteurella multocida fractions on bovine polymorphonuclear leukocyte functions.

The effect of various Pasteurella multocida fractions on bovine polymorphonuclear leukocyte (PMN) functions was examined in vitro by using two encapsulated strains, P-2383 and P-1062 (both are Carter capsular type A and of bovine origin). The ability of PMNs to ingest Staphylococcus aureus and iodinate protein was significantly inhibited in the presence of live cells, heat-killed whole cells, or saline-extracted capsules but not in the presence of the decapsulated heat-killed cells. None of the fractions of the two strains inhibited nitroblue tetrazolium reduction by PMNs. The saline extract did not inhibit the binding of iodine to protein by a reaction involving xanthine, xanthine oxidase, and horseradish peroxidase. The PMN inhibitory factor was further characterized as a heat-stable capsular material of greater than 300,000 molecular weight.

Animals↗
PubMed1978

Nociceptive responses of neurons in medial thalamus and their relationship to spinothalamic pathways.

1. An extracellular study of the cat medial thalamus has revealed four types of somatosensory neurons. These were located primarily in the n. parafascicularis, n. subparafascicularis, and n. centralis lateralis; none were found in the n. centrum medianum. There was no functional segregation of neurons within each nucleus or between nuclei. Each type of neuron had large and often bilateral receptive areas. No somatotopic organization of neurons was found within the medial thalamus. 2. Noxious (N) and noxious-tap (NT) neurons comprising 72% of the sample (78 of 109 total) were considered to be nociceptive. N cells responded exclusively to noxious mechanical stimulation of skin, muscle fascia, tendons, and joints, and to direct stimulation of A-delta- and C-fiber groups in cutaneous, articular, and muscle nerves. NT cells responded to noxious and tap stimulation in a differential manner and to stimulation of the entire spectrum of A- and C-fibers. N and NT cells accurately signaled the duration of noxious mechanical stimulation. Their nociceptive responses were also graded as a function of both noxious stimulus intensity and the number of activated A-delta- and C-fibers. Stimulation of A- and C-fibers evoked, respectively, an inital burst and a late burst of discharges. A brief period of inhibition intervened between the initial and late bursts of NT cells. Prolonged afterdischarge was often observed following noxious natural stimulation or stimulation of A-delta- and C-fibers. The phenomenon of discharge "windup" was observed during iterative stimulation of C-fibers. 3. Tap (T) neurons (10%) responded only to brisk but innocuous taps applied to skin or underlying tissue. These cells were driven only by activation of A-alpha- and A-beta-fibers. The response to such stimulation was seen as an initial burst of discharges followed by an inhibitory period. 4. Inhibited (I) neurons (18%) had resting discharges that were inhibited by noxious stimuli and stimulation of A-beta- and C-fiber groups. 5. The results obtained from monitoring the peripherally evoked responses of nociceptive N and NT neurons before and after selective lesions of the spinal cord strongly suggested that the spinothalamic tracts were the only spinal projections mediating A- and C-fiber input to these cells. Each spinothalamic tract apparently carried information originating from both sides of the body.

Animals↗
PubMed1978

Nociceptive responses of neurons in the posterior group of nuclei and medial thalamus.

Anatomical studies have shown that fibers of the spinothalamic tract terminate in both the posterior group of nuclei (PO) and the nuclei of the medial thalamus. Only the PO receives fiber terminations from the spinocervicothalamic and dorsal column-medial lemniscal projections. This difference in connectively is reflected in the functional differences between the neurons in the PO and those in the medial thalamus. Although both PO and medial thalamus contain a large proportion of nociceptive neurons, only the PO contains neurons that have "lemniscal" response properties. Lesion studies have demonstrated the importance of the spinothalamic tract in mediating A and C fiber input to nociceptive neurons in the PO and medial thalamus. These studies showed that the nociceptive neurons in PO also receive A fiber input from the dorsal column-medial lemniscal projection and A and C fiber input from the spinocervicothalamic projection.

Afferent Pathways↗
PubMedDate not supplied

Identification of new urinary metabolites of famprofazone in humans.

Urinary metabolites of famprofazone following oral administration in humans were identified by gas chromatography-mass spectrometry with electron impact-ionization and comparison with the spectra and retention times of authentic standards. The metabolites were determined following selective derivatization with N-methyl-bis-trifluoroacetamide (MBTFA) and N-methyl-N-trimethyl silyl trifluoroacetamide (MSTFA). Famprofazone was rapidly and extensively metabolized by N-dealkylation, beta-hydroxylation, and p-hydroxylation. The major metabolite, representing approximately 15% of the dose, was methamphetamine. The other metabolites, which were present in minor amounts, were amphetamine, norephedrine, norpseudoephedrine, ephedrine, pseudoephedrine, p-hydroxyamphetamine, p-hydroxymethamphetamine, and p-hydroxydemethyl famprofazone.

Acetamides↗
PubMedDate not supplied

MRI of intracranial neurovascular compression.

Twelve patients with clinical indications of intracranial neurovascular compression (6, hemifacial spasm; 4, trigeminal neuralgia; 2, vertigo and tinnitus) were studied by MRI. Axial 1 mm thick slices were obtained in a 1.5 T unit using a three-dimensional (3D) fast low angle shot data set of 32 contiguous slices. The data were post-processed with multiplanar reconstruction algorithms to obtain oblique sagittal (along the long axis of a nerve) images or coronal images with a slice thickness of 0.8 mm. The MR angiographic images were also obtained from the same 3D data set with maximum intensity projection algorithms. The MR studies showed that 9 of 12 patients had neurovascular compression caused by one or two arteries. These findings were verified at surgery. In two of the remaining three patients, MRI failed to delineate the affected nerves compressed by a vein in one, and a previously applied prosthesis in the other. In the last patient no neurovascular compression was found by MRI or at surgery.

Aged↗