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Biomedical subjects

S Koh

Publications and source records attributed to S Koh.

At least 19 recordsLinked to original sources
PubMed1996

Contagious ecthyma in the live sheep export industry.

OBJECTIVE: To investigate control options for contagious ecthyma (scabby mouth) in Australian sheep exported live to the Middle East. DESIGN: Prevalence, vaccination and modelling studies. PROCEDURE: One hundred and forty weaner sheep (less than 1 year old) on each of 106 farms in Western Australia (WA) and 18 farm groups of adult wethers received at a WA commercial feedlot were examined for lesions of scabby mouth. Sheep on a total of 26 farms in 3 States were divided into treatment and control groups for the vaccination study. A simple deterministic compartmental model was developed to establish which parameters had the greater effect on disease prevalence. RESULTS: The proportion of farms with evidence of scabby mouth in weaner sheep was 23.6% and, on those farms with the disease, the overall prevalence was 6.1%. At the feedlot, 4 out of 18 farm groups had 5 or more sheep with lesions on arrival. The overall prevalence in the 4 diseased groups was 5.2%. Sheep vaccinated on farm before trucking to the feedlot had a lower prevalence of scabby mouth at the end of simulated shipping than controls. The main determinant of scabby mouth prevalence was the proportion of sheep immune to the disease. CONCLUSION: A program of vaccination for scabby mouth will reduce the prevalence of disease during live export. However, using current technology it is not possible to deliver shipments of sheep to the Middle East that are guaranteed completely free of scabby mouth.

Animals↗
PubMed1996

Preventing factitious gingival injury in an autistic patient.

A 34-year-old man with a history of autism developed a deep gingival cleft. During clinical evaluation, the patient repeatedly scraped the affected area with his fingernail. The lesion's clinical features were consistent with focal inflammatory hyperplasia, periodontal disease and factitious stomatitis. This article describes the case and discusses diagnostic and behavioral issues important in treating any patient whose mental age is impaired.

Adult↗
PubMed1995

[The detection of anti-cerebellar antibody western blot analysis in serum from a patient with Miller Fisher syndrome].

We here report a case of Miller Fisher syndrome (MFS) in which serum anti-cerebellar antibody was detected by Western blot analysis. The 32-year-old male studied suffered from diplopia, gait ataxia and sensory disturbance in the distal portion of the upper limbs preceded by cold-like symptoms. Neurological examination on admission revealed that he had external ophthalmoplegia with bilateral ptosis, cerebellar ataxia and areflexia. A cerebrospinal fluid examination showed albuminocytologic dissociation with a protein concentration of 60 mg/dl. Brain CT and MRI showed no significant abnormalities. The patient was diagnosed as MFS, and treated it with two sessions of immunoadsorption plasmapheresis (IAPP). After receiving IAPP therapy, the patient's neurological symptoms and signs were improved. Western blot analysis showed the existence of antibody directed against mouse cerebellum but not against mouse cerebrum, brain stem, and spinal cord in his serum, the level of which was decreased after the IAPP therapy. Serum anti-GQ1b antibody was also elevated. As far as we are aware, there have been no reports showing the existence of anti-cerebellar antibodies detected by Western blot analysis. Though the pathogenesis of MFS remains unclear, our findings suggest that anti-cerebellar antibody detected by Western blot analysis may be caused by cerebellar ataxia in MFS.

Adult↗
PubMed1995

[Development and progression of pyogenic spondylitis in a canine experimental model].

An experimental model was prepared to investigate the process of inflammation in pyogenic spondylitis. Forty-seven mongrel dogs were used, involving 24 mature and 23 immature dogs. Under intravenous pentobarbital anaesthesia, the lumbar vertebral bodies were approached posterolaterally and inoculated using a small piece of gauze soaked in a staphylococcus aureus suspension. Roentgenographic and histological examinations were regularly performed for 24 weeks after the inoculation. Histologically, acute inflammation started within 1 or 2 weeks, and subsided by 5 or 6 weeks in both the mature and immature dogs. In 55% of the dogs, the inflammation was confined within the vertebral body, in 10% it invaded into the intervertebral disc, and in 35% inflammation invaded into the anterior longitudinal ligament. In the immature dogs, thickening of the trabeculae and the anterior cortex was observed around the inflammatory focus more often than in the mature dogs. The epiphyseal line acted as a barrier against invasion by the inflammation in the immature dogs. However, direct invasion of the inflammatory process into the disc could have occurred through the vascular buds which were the terminal branches of the metaphyseal artery close to the disc in both the mature and immature dogs. In contrast to the results reported by Ohno who inoculated the lumbar discs of mongrel dogs with staphylococcus aureus, in the present study, the disc space remained intact and was replaced by fibrous tissue. Consequently, it was concluded that pyogenic spondylitis should be defined as a different clinical entity from discitis.

Animals↗
PubMed1994

Metal affinity engineering of proinsulin carrying genetically attached (His)10-X-Met affinity tail and removal of the tag by cyanogen bromide.

An E. coli expression clone coding for human proinsulin, which was fused to NH2-terminal beta-galactosidase, was engineered for the separation from host proteins by introducing peptide devices, and for the sequential removal of the fused polypeptide by cyanogen bromide in front of the NH2 terminal residue (methionine) of the human proinsulin gene. Short synthetic genes encoding oligopeptide residues including (Glu)n, (His)n, (Trp)n, and (Ser)n (n = 10 or 11), which have certain characteristic physical properties such as metal-affinity, polarity, hydrophobicity, and hydrophilicity, respectively, were inserted at the junction region of the gene fusion. Interestingly, it was found that among the oligopeptides, the oligohistidine residue as an affinity-tag has greatly facilitated the procedures for FPI purification, particularly in the manner of selective metal-affinity precipitation. The chelating peptide covering the NH2-terminal beta-galactosidase portion could then be removed simply after purification to generate a protein with the natural amino acid sequence of proinsulin by cyanogen bromide.

Affinity Labels↗
PubMed1993

Immunoelectron microscopic localization of the HPC-1 antigen in rat cerebellum.

HPC-1 antigen is a neuron-specific 34 kDa protein, identical to p35A (syntaxin), and is thought to play important roles in docking or fusion of synaptic vesicles to presynaptic active zones. In the present study we analyze the distribution of HPC-1 antigen in rat cerebellum by a cryoimmunogold technique using an antibody against the fusion protein of beta-galactosidase and the HPC-1 antigen. HPC-1 antigen was detected at high density on the plasma membranes and synaptic vesicles of presynaptic boutons which formed synapses with dendrites of Purkinje cells, and on the plasma membranes of parallel fibres in the cerebellar molecular layer. In the granule cell layer, gold particles were also detected on the endoplasmic reticulum, nuclear membranes and the plasma membranes of granule cells. Presynaptic membranes and synaptic vesicles in glomeruli were also labelled by gold particles. To determine the topology of HPC-1 antigen on the membranes, the synaptosome fraction prepared from rat cerebellum was embedded in agarose, and processed for the pre-embedding protein A-gold technique. Intact synaptosomes were not labelled by gold particles. However, when fixed in hypotonic fixative to rupture plasma membranes, or when ruptured after fixation in normotonic fixative, the cytoplasmic surfaces of presynaptic membranes and synaptic vesicles were labelled by gold particles. These results suggest that most of the epitopes of HPC-1 antigen are located on the cytoplasmic surface of plasma membranes and synaptic vesicle membranes.

Animals↗
PubMed1993

[Surgical treatment of metastatic lung tumors].

From January 1970 to March 1991, 72 operations in 55 patients (31 males and 24 females) with metastatic lung tumors were performed in our department. Their cumulative survival rates was 25.5% at five years. With analysis of the various prognostic factors, patients both with solitary metastases and without lymph node metastases had a good prognoses. However, even in patients with recurrent lung metastatic tumors, long time survival was achieved with reoperation in two patients. We concluded that reoperation with or without effective chemotherapies was effective in selected patients.

Adolescent↗
PubMed1992

[Changes of plombage-operations in respiratory surgery].

The first plombage-operation for pulmonary tuberculosis was by Dr. Nagaishi (1947) and Dr. Wilson, who developed the plombage method employing hollow polymethylmethacrylate spheres. Although the method presented a relatively effective option at a time when no effective drugs were available, its use was discontinued because of such complications as lung injury, cavity-perforation, and empyema. Therefore, soft elastic resin materials, such as those used in sponge-plombage and air-plombage, replaced the hard resin materials. Each plombage method is associated with a certain medical historical period, in Japan. Still the "Kinchyu" method was used. However, the complication of chronic empyema with bronchopleural fistula was difficult to treat. A notable recent method is the pedicled omentum plombage method, which is effective in the treatment of patients who have not responded to standard operations. Finally there was surely a clinical significance in each medical historical period.

Adult↗
PubMed1991

Differential regulation of the low-affinity nerve growth factor receptor during postnatal development of the rat brain.

We studied the temporal and spatial localization of the low-affinity nerve growth factor receptor (LNGF-R) during the early postnatal period in rat brain in order to understand better the relationship between nerve growth factor (NGF)-like responsiveness and the development of specific central neuronal populations. Four different developmental patterns of LNGF-R mRNA hybridization were found in this study. First, some neurons contain high levels of LNGF-R mRNA from postnatal time points into adulthood, as exemplified by neurons of the cholinergic basal forebrain and mesencephalic trigeminal nucleus. Second, several cell groups exhibit robust hybridization during the early postnatal period but contain much reduced levels of LNGF-R mRNA in the adult brain. These include striatal neurons, Purkinje cells of the cerebellum, and several medullary nuclei. A third group of cells produces the LNGF-R transiently during development, including cranial nerve nuclei of the brainstem, the periolivary nuclei complex, the reticular formation, and the deep cerebellar nuclei. Finally, cell populations which may exist only transiently during central nervous system (CNS) development, such as subplate neurons of the cerebral cortex, appear to express the LNGF-R during only a brief period. These results show that the LNGF-R gene is differentially regulated in a cell type-specific manner during development, and suggests that diverse neuronal populations require only transient growth factor sensitivity, while others exhibit NGF-like responsitivity into maturity.

Animals↗
PubMed1991

Application of a metal capillary column in gas chromatographic determination of catechol-o-methyltransferase activity.

The utility of a deactivated metal capillary column, Rascot, in the measurement of an enzymatic reaction, in this case measurement of rat catechol-O-methyltransferase activity, was examined. 3,4-Dihydroxybenzaldehyde, 3,4-dihydroxybenzylalcohol and 3,4-dihydroxybenzoic acid were used as substrates and the m- and p-O-methylated products were separated by using Rascot after derivatization. The peaks on the chromatograms were symmetrical. The data obtained were compared with those reported in previously published papers. Good agreement with previous results proved that Rascot is able to withstand practical use in biological materials.

Animals↗
PubMed1991

Immunoblot analysis of IgE and IgG antibodies to honey bee venom: cross sectional and sequential studies in bee sensitive subjects.

To investigate the specific IgE and IgG immune response to honey bee venom (bv), we performed immunoblot analysis of sera from 47 bee sensitive subjects and followed the response during and after venom immunotherapy in 15 of these subjects. Fifteen venom proteins varying in molecular size from 20 to 105 kDa were identified as being antigenic and consisted of a high molecular weight (HMW) group (5 to 105 kDa, containing the previously identified allergens B and C) and a low molecular weight group (LMW) containing hyaluronidase and phospholipase A. In general for a given individual the anti-venom IgE and IgG response was qualitatively similar although some variation between individuals was apparent. Reactivity with hyaluronidase and phospholipase A appeared only in those subjects showing reactivity with HMW components. During immunotherapy specific anti-venom IgG and IgE responses tended to be linked. Increased responses being seen against all components in 4 of 12 subjects, reductions in 3 and unchanged responses in the remainder. Following immunotherapy (mean 4.0 years), spontaneous reduction of IgE and IgG was seen in 5 of 5 subjects. Loss of reactivity with the LMW components was prominent in these sera.

Adult↗
PubMed1990

Histological changes in aging lumbar intervertebral discs. Their role in protrusions and prolapses.

To study the relationships between the changes due to aging in lumbar intervertebral discs and the development of protrusion or prolapse, we carried out histological studies on operative specimens of thirty-one discs, of which twenty-two had been protruded and nine, prolapsed. The specimens were obtained during twenty-nine operations for herniation of a lumbar intervertebral disc in patients who were sixty years old or older. Changes in the anulus fibrosus were more extensive in the nine prolapsed discs than in the twenty-two protruded discs. Of the nine prolapsed discs, myxomatous degeneration, fibrosis, and swollen anular fibers were found in all nine, and cysts were seen in five. Of the twenty-two protruded discs, only five showed myxomatous degeneration; ten, fibrosis; one, a cyst; and sixteen, swollen fibers. For comparison, we also studied specimens that had been obtained at operation from twenty-one other patients, twenty to fifty-nine years old, who had a prolapsed disc. The anulus showed myxomatous degeneration in all twenty-one specimens, cysts in eight, and fibrosis in ten. In addition, we examined 368 autopsy specimens from people who had been between twenty-five and eighty-five years old at the time of death. In many of the subjects who had died in the sixth decade of life or later, we found that the orientation of the inner fiber bundles of the anulus fibrosus was reversed, so that they bulged inward. The reversal appeared to be the result of myxomatous degeneration of the middle fibers of the anulus, atrophy of the nucleus, and narrowing of the disc space. These histological findings suggest explanations for the predominance of protrusions of the nucleus pulposus in patients who are less than sixty years old and of prolapse of the anulus fibrosus in the few patients who are more than sixty years old who have herniation of an intervertebral disc.

Adolescent↗
PubMed1989

Loss of NGF receptor immunoreactivity in basal forebrain neurons of aged rats: correlation with spatial memory impairment.

Nerve growth factor (NGF) has recently been implicated as a trophic agent in the survival and maintenance of basal forebrain cholinergic neurons. To test the hypothesis that NGF may play a role in the age-related decline of cerebral cholinergic function and loss of cognitive ability, we investigated the possible correlation between the loss of basal forebrain neurons that stain for NGF receptor, and impairment of spatial reference memory performance in aged rats. Our results suggest that NGF receptor-positive basal forebrain neurons undergo marked cell atrophy and loss of neuropil staining in aged rats exhibiting impaired spatial learning and memory performance. Conversely, numerous, densely immunoreactive perikarya and a profuse neuritic plexus within the basal forebrain nuclei was consistently observed in behaviorally intact rats. Overall, the mean number of NGF receptor-positive basal forebrain neurons both in the nucleus of the diagonal band and nucleus basalis correlated with retention of the spatial task (r = 0.84 and r = 0.67, respectively; P less than 0.01). Our results support the view that progressive failure of retrograde trophic support due to the age-related loss of NGF receptors may promote degenerative changes in basal forebrain cholinergic neurons, and contribute to deterioration of cognitive ability in senescence.

Aging↗
PubMed1989

Effects of three types of combined O.C. pills on blood coagulation, fibrinolysis and platelet function.

The results of a prospective longitudinal controlled study comparing the coagulation effects of a standard low-dose combined oral contraceptive (Microgynon 30), a desogestrel-containing pill (Marvelon) and a triphasic preparation (Triquilar) after one year's treatment in ethnic Chinese women is presented in this paper. In general the changes in coagulation parameters are similar to those seen in Caucasian women. The rise in Factor VII levels seen at 6 and 12 months in Marvelon users was not present to a significant degree in the other pill users. Antithrombin III levels remained unchanged in Microgynon and Marvelon users but with Triquilar there was a significant fall at 6 and 12 months of use. Whether these differences have any clinical relevance in the local Chinese population with low incidence of thromboembolism remains to be seen.

Adenosine Diphosphate↗
PubMed1989

Localization of nerve growth factor receptor messenger RNA and protein in the adult rat brain.

We have used in situ hybridization and immunocytochemistry to map the cellular localization of NGF receptor (NGF-R) mRNA and protein in the adult rat brain. In addition to basal forebrain magnocellular neurons, NGF-R is widely expressed within the CNS, including neurons of the caudate/putamen, ventral premamillary nucleus, mesencephalic trigeminal nucleus, prepositus hypoglossal nucleus, raphe nucleus, nucleus ambiguous, and Purkinje cells of the cerebellum. Cells of the vestibulocochlear ganglion also contain NGF-R mRNA and protein. Ventricular subependymal cells and tanycytes are clearly stained by immunocytochemistry, yet only very weak hybridization is detectable in these cells. Also, greater amounts of NGF-R protein than of mRNA appear to be present in the glomeruli of the olfactory bulb, area postrema, and nucleus tractus solitarius. Areas that contain only NGF-R immunoreactive fibers and terminals can be distinguished from the cellular sites of NGF-R biosynthesis and include the suprachiasmatic nucleus, the principal olivary pretectal nucleus, the superior colliculus, the inferior olive, and the principal and spinal trigeminal nuclei. This study shows that NGF-R is widely expressed within individual neurons in different areas of the rat brain and identifies new potential CNS target sites of endogenous NGF.

Animals↗
PubMed1989

NGF induction of NGF receptor gene expression and cholinergic neuronal hypertrophy within the basal forebrain of the adult rat.

Chronic infusion of nerve growth factor (NGF) into the forebrain of the adult rat produced increases in NGF receptor (NGF-R) mRNA hybridization, NGF-R immunoreactivity, choline acetyltransferase (ChAT) mRNA hybridization, and neuronal hypertrophy, when compared with vehicle infusion or noninfused rat brain. In situ hybridization showed NGF induction of NGF-R gene expression, documented by increases in the number of NGF-R mRNA-positive cells within the medial septum, diagonal band, and nucleus basalis magnocellularis. NGF also produced hypertrophy of ChAT mRNA-positive neurons. These results suggest that NGF produces cholinergic neuronal hypertrophy through induction of NGF-R gene expression within the basal forebrain.

Animals↗