Search PubMed⌕ Search

Biomedical subjects

J H Ryu

Publications and source records attributed to J H Ryu.

At least 73 records · Page 4Linked to original sources
PubMed1998

Localization of nerve growth factor, trkA and P75 immunoreactivity in the hippocampal formation and basal forebrain of adult rats.

In the immunohistochemical staining of nerve growth factor, it has been reported that fixation-dependent lability of nerve growth factor hampers its localization. In the present study, we used two different polyclonal antibodies to immunostain nerve growth factor in rat brain tissue. We found that in paraformaldehyde-fixed (immersion- or perfusion-fixed) brains, nerve growth factor-like immunoreactivity was located primarily in the cytoplasmic membrane and fiber tract of hippocampal neurons and was sparse in cortical neurons. When fresh frozen brain sections were fixed in paraformaldehyde solution, nerve-growth factor-like immunoreactivity was distributed evenly in the cell body. However, when fresh frozen brain sections were fixed in acetone, immunoreactivity to nerve growth factor was present as discrete or confluent dense particles in the cell body, especially in the nuclear region. Also, when paraformaldehyde-perfusion-fixed brain sections were heat treated in salt solution before immunostaining, nerve growth factor-like immunoreactivity could be retrieved in the cytoplasmic and nuclear regions. The hippocampal formation, cerebral cortex and basal forebrain expressed nerve growth factor-like immunoreactivity. Double immunostaining in fresh frozen brains showed that the low-affinity nerve growth factor receptor (p75) co-expressed with nerve growth factor and trkA proto-oncogene in basal forebrain neurons. Our study shows that formaldehyde fixation can mask nerve growth factor antigen, and special treatment, such as heating, is needed to retrieve nerve growth factor antigen to permit immunohistochemical detection. For immunohistochemical study of nerve growth factor in rat brain tissue, successful immunostaining can be obtained by using fresh frozen brains to prevent the masking effect of fixatives or by using paraformaldehyde-fixed brains with heat treatment. It is likely that nerve growth factor is synthesized and accumulated mainly in the cell body but not in the fiber tracts, which is similar to the distribution of its messenger RNA. The co-existence of p75 with nerve growth factor and trkA in basal forebrain neurons suggests the role of low- and high-affinity receptors in regulating the trophic effect of nerve growth factor.

Animals↗
PubMed1998

Prognostic significance of histopathologic subsets in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a generally fatal disorder with a reported median survival of 3 to 6 yr. This has been based on relatively few studies with diagnoses inconsistently confirmed by adequate lung biopsy. Retrospective analysis of 104 patients with IPF who had open lung biopsy (OLB) at Mayo Medical Center from 1976 to 1985 was performed to establish the overall survival rate, the spectrum of histopathological subgroups and their associated prognostic significance. The study group consisted of 54 men and 50 women with a median age of 63 yr. Median survival was 3.8 yr after diagnosis by OLB with an estimated 10 yr survival of 27%. Current histopathologic review showed a heterogeneous group including usual interstitial pneumonia (UIP), desquamative interstitial pneumonia (DIP), nonspecific interstitial pneumonia/fibrosis (NSIP), acute interstitial pneumonia (AIP), bronchiolitis, bronchiolitis obliterans organizing pneumonia (BOOP), and others. Median survival of the UIP group was 2.8 yr which is significantly worse (p < 0.001) than for other subgroups of chronic interstitial pneumonias. IPF includes several histopathologic subgroups with significantly different survival rates. Patients with UIP have worse survival than patients with other types of idiopathic chronic interstitial pneumonias including NSIP. Accurate histopathologic classification is essential for prognostication in patients with IPF.

Adult↗
PubMed1998

Colchicine versus prednisone in the treatment of idiopathic pulmonary fibrosis. A randomized prospective study. Members of the Lung Study Group.

Twenty-six symptomatic subjects with clinical evidence plus either high-resolution computed tomography (HRCT, n = 25) or open-lung biopsy (OLB, n = 1) patterns typical for idiopathic usual interstitial pneumonia (idiopathic UIP) were entered into a randomized prospective treatment trial using high-dose prednisone (n = 12) versus colchicine (n = 14). The minimum dose of prednisone used was 60 mg/d for 1 mo, tapered to 40 mg/d over the second month, tapered to 40 mg every other day during the third month, with subsequent doses adjusted as clinically indicated. The dose of colchicine was 0.6-1.2 mg/d, as tolerated. The presence of a rim of subpleural honeycomb change was present in all of the 25 subjects who had HRCT. Subjects treated with high-dose prednisone alone experienced a higher incidence of serious side effects and also exhibited a trend (not statistically significant, p = 0.391) to more rapid decline of pulmonary function and shortened survival than did those treated with colchicine alone. In most subjects with typical clinical and HRCT features of idiopathic UIP, neither prednisone nor colchicine resulted in objective improvement, and the disease continued to progress in the majority. Colchicine appears to be a safer alternative to a trial of high-dose prednisone but may be no different than no therapy.

Aged↗
PubMed1998

Idiopathic pulmonary fibrosis: current concepts.

Idiopathic pulmonary fibrosis (IPF) is generally defined as a progressive, fibrosing inflammatory disease of the lung parenchyma of unknown cause. It is characterized by slowly increasing dyspnea, diffuse interstitial lung infiltrates, restrictive lung dysfunction, and impaired gas exchange. Ultimately, it is fatal in most patients, and treatment options remain unsatisfactory. The advent of high-resolution computed tomography of the chest and modifications in the histopathologic classification of interstitial pneumonias have reshaped the concept of IPF. Although initially thought to be a relatively specific clinicopathologic entity, it seems likely that IPF as previously defined is a heterogeneous disorder consisting of several clinicopathologic entities with differing histopathologic patterns, clinical course, response to therapy, and prognosis. The most common histologic pattern in cases previously defined as IPF is usual interstitial pneumonia, which is associated with a median survival of less than 3 years. For accurate prognosis and optimal management of patients, the clinician should attempt to be as precise as possible in distinguishing various clinicopathologic entities that have been included under the clinical heading of IPF. In the future, we recommend that the use of the term "idiopathic pulmonary fibrosis" be restricted to patients with usual interstitial pneumonia and that clinicians recognize the fact that other idiopathic interstitial pneumonias do not have the same prognostic effect traditionally ascribed to IPF.

Diagnosis, Differential↗
PubMed1998

Clinical recognition of pulmonary embolism: problem of unrecognized and asymptomatic cases.

Dyspnea, pleuritic chest pain, and tachypnea are widely appreciated as common initial features of pulmonary embolism (PE). This knowledge is derived primarily from prospective studies evaluating diagnostic tests or therapeutic interventions in which the study patients are suspected to have PE based on their initial symptoms. Autopsy studies, however, continue to show that most cases of fatal PE are unrecognized and undiagnosed. Data from studies screening for PE in patients with deep venous thrombosis and in postoperative patients suggest that many patients with PE are asymptomatic and that PE is unrecognized. We believe that the current concepts regarding the initial clinical features of PE are too narrow and biased toward symptomatic cases. High clinical suspicion may be insufficient in recognizing PE. Herein we summarize the available data and explore the implications for clinical practice.

Chronic Disease↗
PubMed1997

Assessment of the patient with chronic cough.

Chronic cough, defined as cough that persists for 3 weeks or longer, is one of the most common symptoms evaluated by a primary-care physician. With the exclusion of cigarette smoking, postnasal drip, asthma, and gastroesophageal reflux are responsible for more than 80% of the causes of chronic cough. Elicitation of a thorough history and performance of a physical examination will usually provide clues about the cause of chronic cough. The use of diagnostic tests including methacholine challenge, gastroesophageal reflux studies, and sinus imaging is based on clinical suspicion. Treatment of chronic cough is aimed at the underlying cause.

Asthma↗
PubMed1997

Extracellular components implicated in the stationary organization of the actin cytoskeleton in mesophyll cells of Vallisneria.

In mesophyll cells of Vallisneria gigantea Graebner, an aquatic angiosperm, the association of the plasma membrane with the cell wall at the end wall has been reported to be indispensable for the mechanism that maintains the stationary organization of the bundles of microfilaments (MFs) [Masuda et al. (1991) Protoplasma 162: 151]. To identify putative extracellular components that might play a crucial role in this mechanism, we examined the effects of two exogenously applied synthetic hexapeptides, GRGDSP and ARYDEI, which include an RGD and an RYD motif, respectively. The RGD motif is known as a recognition site in molecules required for adhesion to the substratum at sites of focal contacts. Within 24 h, both peptides (at concentrations of 1-15 mM) induced extremely abnormal patterns of cytoplasmic streaming, as well as the striking disruption of the arrangement of bundles of MFs. GRGESP and ARYEEI peptides, used as controls, had no detectable effects. Immunofluorescence microscopy revealed that polyclonal antibodies against the ARYDEI peptide bound to the cell walls of mesophyll cells while a preimmune serum did not. Western blotting analysis demonstrated that the antibodies recognized polypeptides of 54 kDa and 27 kDa in an extract of total proteins from the leaves of Vallisneria. The results suggest that some extracellular proteins(s), with a conserved RGD or RYD motif in its amino acid sequence, might be involved in the maintenance of the stationary organization of the bundles of MFs.

Actin Cytoskeleton↗
PubMed1997

Colchicine versus prednisone as treatment of usual interstitial pneumonia.

OBJECTIVE: To assess the results with colchicine and prednisone as initial single-drug therapy in patients with usual interstitial pneumonia (UIP). MATERIAL AND METHODS: We reviewed the serial pulmonary function test results in 22 patients with typical clinical and high-resolution computed tomographic features of UIP who were treated with colchicine as initial single-agent therapy and compared them with a group of 22 historical patients with UIP of similar severity diagnosed by open-lung biopsy who were given prednisone as initial single-drug therapy. RESULTS: No significant difference was detected in the rate of decline of pulmonary function or in the time to "failure" between the two study groups. A trend was suggested for more rapid decline of pulmonary function in the prednisone-treated than in the colchicine-treated group. The design of this study does not allow distinction between a possible beneficial effect of colchicine and a possible adverse effect related to weaning from high-dose prednisone. Colchicine was well tolerated; few side effects other than mild diarrhea were noted in those patients able to take the drug long enough to return for pulmonary function testing at 3 months. In comparison, the side effects of prednisone were more serious and were not always reversible with cessation of therapy. CONCLUSION: This study lends further support to the assumption that colchicine may be a satisfactory and less hazardous substitute for prednisone in the treatment of patients with UIP.

Aged↗
PubMed1996

Behavioral studies on rats with transient cerebral ischemia induced by occlusion of the middle cerebral artery.

The behavioral effects of transient cerebral ischemia in adult Wistar rats were studied. In Experiment 1, rats were subjected to 90-min occlusion of the unilateral, left or right, middle cerebral artery (MCA) followed by recirculation. The locomotor activity had not changed 3 and 30 days after the occlusion, except that the number of rearing was significantly decreased by left MCA occlusion. Rats were examined in a radial maze system for learning and memory ability during 4 weeks from the 3rd day after ischemia (the 3rd day was counted as day 1 of the experiment). Maze performance was slightly disturbed due to focal brain damage by MCA occlusion, but the disturbance was statistically significant only on days 6, 11, and 15 in the right occlusion. In Experiment 2, rats were trained to master a radial maze task completely for 4 weeks, and then subjected to transient unilateral (right) ischemia as described above. These rats showed an increase in incorrect entry in the radial maze task from day 4 to day 14. However, on day 21, the number of incorrect entry decreased to the control level of the sham-operated group. The numbers of correct choice were inversely related with those of incorrect entry, though slightly blunted. Coincidentally, the time required to solve the maze task was also prolonged from day 4 to day 14, but returned to the control time on day 21. These results suggest that unilateral ischemia transiently suppresses both acquiring radial maze performance and maintenance of learned performance and that it is a good model for studying human focal cerebral ischemia.

Adult↗
PubMed1996

The effect of dopamine D1 receptor stimulation on the up-regulation of histamine H3-receptors following destruction of the ascending dopaminergic neurones.

1. The binding of [3H]-(R)alpha-methylhistamine and [3H]-N alpha-methylhistamine to histamine H3-receptors, [3H]-SCH23390 to dopamine D1-receptors, and [3H]-YM09151-2 to dopamine D2-receptors was investigated by quantitative receptor autoradiography in the rat brain following 6-hydroxydopamine injection into the substantia nigra. 2. The levels of [3H]-(R)alpha-methylhistamine binding sites in the denervated striatum and substantia nigra were significantly higher than those in the contralateral side from 1 week to 12 weeks after nigral lesions. The H3-receptor binding was maximal at 3 weeks after nigral lesions and maintained until 12 weeks. 3. The increased number of histamine H3-receptors was decreased to the level of the contralateral side by chronic treatment with a selective dopamine D1 agonist, SKF38393, but not modified by a selective dopamine D2 agonist, quinpirole. 4. Dopamine D1- and D2-receptors in the striatum were similarly up-regulated after unilateral nigral lesion. On the other hand, the number of dopamine D2-receptors in the substantia nigra was markedly decreased after administration of 6-hydroxydopamine. 5. The treatment with (S)alpha-fluoromethylhistidine increased the H3-receptor binding in both the ipsilateral and contralateral sides. As a result, the magnitude of the ratio of the H3-receptor binding between ipsilateral and contralateral sides was partially attenuated by treatment with (S)-alpha-fluoromethylhistidine. 6. These results strongly suggest that the expression of histamine H3-receptors in the striatum and substantia nigra is influenced through D1-receptors by tonic nigrostriatal dopaminergic inputs.

Animals↗
PubMed1996

The brain histamine (HA) and pituitary luteinizing hormone (LH) levels in female rats anesthetized with ether on proestrus.

Levels of brain histamine (HA) and pituitary luteinizing hormone (LH) were determined in female rats anesthetized with ether in the afternoon of proestrus. The rats after 6-hr ether anesthesia had an average HA concentration higher than that of non-anesthetized rats in the hypothalamus, but not in the cortex or diencephalon. Ether-anesthetized rats also showed a higher LH level in the pituitary than that of non-anesthetized rats. These findings agree well with our previous observation of an inhibited ovulation associated with a decrease in serum LH in female rats anesthetized with ether in the afternoon of proestrus. Furthermore, it is suggested that the release of pituitary LH into the circulating blood is regulated by the level of HA in the hypothalamus.

Anesthesia↗
PubMed1996

Basophilic deposits on the cupula: preliminary findings describing the problems involved in studies regarding the incidence of basophilic deposits on the cupula.

In this study, the possibility of whether basophilic deposits adhered to the cupulas in the semicircular canals was investigated histologically. Results indicated that basophilic deposits were present in all three cupulas of the semicircular canals. The overall incidence of basophilic deposits in the superior, lateral and posterior semicircular canal cupulas was 26%, 41% and 37%, respectively. The incidence of basophilic deposits bound to the cupulas increased with age. The possible origin of these basophilic deposits on the cupulas and the increased incidence of basophilic deposits with increasing age are discussed.

Adult↗
PubMed1996

Update on idiopathic perilymphatic fistulas.

Idiopathic perilymphatic fistula has been confirmed with clinical-temporal bone histopathologic studies as a separate inner ear disease. Criteria for its diagnosis are sudden or progressive sensory hearing loss, or for vestibular components, a positive fistula test, constant disequilibrium, and positional nystagmus or postural vertigo. Nonsurgical treatment, such as keeping the head higher than the heart and avoiding heavy lifting, can be tried. When it is ineffective or when there is sudden hearing loss without improvement, surgical sealing of the leak should be attempted.

Adult↗
PubMed1995

Ontogenetic development of histamine receptor subtypes in rat brain demonstrated by quantitative autoradiography.

The postnatal ontogenetic development of the histamine receptor subtypes was studied in rat brain by quantitative receptor autoradiography with highly sensitive imaging plates. H1 receptor binding sites labeled with [3H]pyrilamine were detected on postnatal day 2 (P2) and increased very slowly until P9, and then rapidly reaching the adult levels in the hypothalamus, hippocampus, and amygdala by P16. The densities of H1 receptor binding sites in the cortex, striatum, thalamus, and substantia nigra were relatively low during development. H3 receptor binding sites labeled with [3H](R) alpha-methylhistamine were not detectable until P9. On P9, their density was higher in the substantia nigra than in other regions. Subsequently, H3 receptor binding increased, reaching the adult levels in the substantia nigra on P16 and in the other regions on P23. The histamine concentration was initially very high, but decreased to the adult level by P16. On the contrary, the activity of L-histidine decarboxylase of whole brain tissue was low on P5, and increased markedly from P16 to P23, to the adult level on P30. Administration of (S) alpha-fluoromethylhistidine (FMH), a specific inhibitor of L-histidine decarboxylase (HDC), significantly decreased both the HDC activity and histamine concentration during postnatal development. FMH treatment did not change H1 receptor binding in any brain region, but significantly increased H3 receptors in the substantia nigra and striatum on P23. Unilateral injection of 6-hydroxydopamine into the striatum on P2 resulted in up-regulation of H3 receptor binding sites in the dorsomedial (11%) and dorsolateral (18%) regions of the striatum and substantia nigra (31%) on P23, but no change in the H3 receptor density in the nucleus accumbens or frontal cortex on P11 and P23. These results demonstrate that the developmental patterns of H1 and H3 receptors are heterogeneous and independent of each other. There are marked mismatches of presynaptic and postsynaptic markers of the histaminergic neuron system as in other aminergic systems.

Aging↗
PubMed1995

Idiopathic perilymphatic fistulas. A temporal bone histopathologic study with clinical, surgical, and histopathologic correlations.

OBJECTIVE: To report a case of idiopathic perilymphatic fistulas diagnosed and successfully treated during life and confirmed histopathologically post mortem. METHODS: Perilymphatic fistulas were diagnosed clinically and repaired surgically. Light microscopic histopathologic studies were made of both temporal bones after death. RESULTS: Vestibular symptoms had improved postoperatively. Postmortem histopathologic examination of the temporal bones demonstrated patencies of the labyrinth capsule that had been predicted clinically during life, the qualities of the membranous labyrinth in both the operated-on and the unoperated-on ears, and the elements of the surgical repair. Notably, there was no evidence of endolymphatic hydrops. CONCLUSIONS: The histopathologic findings document the relationships of the fistula ante fenestram and the fissure connecting the round window niche and the posterior semicircular canal to idiopathic perilymphatic fistulas. Also, the diagnostic features reported herein allowed this patient with fluctuating hearing loss, episodic vertigo, and tinnitus to be distinguished from a patient with Meniere's syndrome. These findings have implications regarding past and future studies of vestibular and cochlear disorders.

Aged↗