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Biomedical subjects

J H Ryu

Publications and source records attributed to J H Ryu.

At least 19 recordsLinked to original sources
PubMed1992

Syphilis: a disease to exclude in diagnosing sarcoidosis.

A 37-year-old man was referred to our institution for assessment of possible sarcoidosis with involvement of the central nervous system. Before referral, he experienced a systemic illness that persisted for several months, during which time ocular and pulmonary noncaseating granulomas were identified. Sarcoidosis with involvement of the central nervous system was tentatively diagnosed. Because of several inconsistencies in the preliminary diagnosis of sarcoidosis, further assessment was pursued, and syphilis was diagnosed. Herein we emphasize the useful clinical features for distinguishing syphilis from sarcoidosis and review the clinical manifestations of pulmonary syphilis.

Adult↗
PubMed1992

Receptor autoradiography with 11C and [3H]-labelled ligands visualized by imaging plates.

The distribution of histamine H1, H3, dopamine D1 and D2 receptors in the brain was studied by receptor autoradiography using a high-sensitivity and high-resolution imaging plate system. [3H]Pyrilamine, [3H](R)alpha-methyl-histamine, [11C]SCH23390, and [11C]N-methylspiperone (or [11C]YM-09151-2) were used as ligands to identify H1, H3, D1 and D2 receptors, respectively. Two different receptors (dopamine D2 and histamine H3) could be also labelled simultaneously in a single cryostat-sliced section using [11C]N-methylspiperone and [3H](R)alpha-methylhistamine, respectively. The imaging plate system is useful for receptor autoradiography of positron emitter-labelled and tritium-labelled receptor-ligands because of its high sensitivity.

Animals↗
PubMed1992

Monocyte heterogeneity in angiotensin-converting enzyme induction mediated by autologous T lymphocytes.

The ability of monocyte subpopulations to be induced selectively by T lymphocytes to synthesize enhanced levels of angiotensin-converting enzyme (ACE) was examined using an in vitro model employing normal peripheral blood monocytes and T lymphocytes. Separation of monocytes into subpopulations on the basis of buoyant density indicated no difference in the ability of the resulting monocyte subpopulations to produce basal levels of ACE when cultured in the absence of T lymphocytes. However, the subpopulations differed significantly in their ability to synthesize enhanced levels of ACE in response to the presence of autologous T lymphocytes; low-density monocytes were induced by T lymphocytes to synthesize three-fold more ACE than were high-density monocytes. Surface antigen labelling using MoAbs demonstrated that the low-density monocyte subpopulations also had a significantly higher percentage of Leu-M2+ monocytes compared with the high-density monocyte subpopulations. When monocytes were separated on the basis of the presence of the Leu-M2 antigen using an immune rosetting technique, T lymphocytes were able to induce significantly elevated levels of ACE in the Leu-M2+ enriched monocyte subpopulation but were unable to induce ACE beyond basal levels in the Leu-M2(+)-depleted monocyte subpopulation. These results demonstrate that monocytes are heterogeneous with respect to their ability to be induced by T lymphocytes to synthesize ACE. This raises the possibility that selective accumulation of a monocyte subpopulation in the granulomatous inflammation of sarcoidosis may be one of the factors required for elevated ACE synthesis in the resulting granuloma epithelioid cells.

Adult↗
PubMed1992

Selective effect of chronic lead ingestion on tyrosine hydroxylase activity in brain regions of rats.

Alterations of tyrosine hydroxylase activity in various regions of brain from rats postnatally exposed to lead were tested. Three groups of animals were prepared; (1) Rats exposed to lead at a low dose (0.05% lead acetate, PbAc); (2) Rats exposed to lead at a high dose (0.2% PbAc); (3) Age-matched normal control rats. At 2, 4, 6, and 8 weeks of age, weight of brain and body, and concentrations of lead in whole brain of animals in each group were measured. Activities of tyrosine hydroxylase and Na(+)-K+ ATPase were also measured at the same ages in 4 brain regions of each animal. Body weight gain was decreased after 6 weeks of age in rats exposed to lead at a high dose. Concentrations of lead in whole brain were increased from 0.37 to 0.83 (ng/mg wet tissue) in these animals. Exposure of rats to lead generally increased tyrosine hydroxylase activity and decreased Na(+)-K+ ATPase activity. However, changes of tyrosine hydroxylase activity were detected without concomitant changes of Na(+)-K+ ATPase activity in pons-medulla at 2 weeks of age and telencephalon at 6 weeks of age in rats exposed to lead at a low dose, and in midbrain at 4 and 6 weeks of age in rats exposed to lead at a high dose. These data imply that catecholaminergic nervous system in the brain regions described above could be selectively affected by lead.

Animals↗
PubMed1991

Microscopic pulmonary tumor embolism causing subacute cor pulmonale: a difficult antemortem diagnosis.

Microscopic pulmonary tumor embolism is difficult to diagnose. The most common initial clinical symptom is subacute progressive dyspnea, and the initial laboratory evaluation typically shows hypoxemia in a patient with clear lung fields on a chest roentgenogram. Another distinguishing feature may be hepatic abnormalities. In general, pulmonary angiography discloses no evidence of emboli, but multiple subsegmental peripheral perfusion defects are noted on ventilation-perfusion lung scans. The diagnosis of microscopic pulmonary tumor embolism can be confirmed by open-lung or transbronchial lung biopsy or by microvascular pulmonary cytology, a less invasive procedure that could be performed at the time of pulmonary angiography. Herein we describe two patients with unsuspected microscopic pulmonary tumor embolism that eventuated in subacute cor pulmonale and death. These cases illustrate the characteristic findings of this entity and emphasize the need for early diagnosis.

Adenocarcinoma↗
PubMed1991

Oxygen-exacerbated bleomycin pulmonary toxicity.

Bleomycin is an antineoplastic agent with potential for producing pulmonary toxicity, attributed in part to its free radical-promoting ability. Clinical and research experiences have suggested that the risk of bleomycin-induced pulmonary injury is increased with the administration of oxygen. We report a case in which the intraoperative administration of oxygen in the setting of previous bleomycin therapy contributed to postoperative ventilatory failure. Our patient recovered with corticosteroid therapy. Physician awareness of a potential interaction between oxygen and bleomycin may help reduce the morbidity and mortality related to bleomycin therapy.

Acute Disease↗
PubMed1991

Effects of acetate dialysate on transforming growth factor beta 1, interleukin, and beta 2-microglobulin plasma levels.

To evaluate potential adverse effects of acetate use in hemodialysis (HD), we measured plasma interleukin (IL-1 alpha, IL-1 beta, IL-6), TNF alpha, TGF beta 1, and beta 2-microglobulin levels with ELISA assays in normal (N = 9), CRF (N = 6), CAPD (N = 7) and HD (N = 8) subjects and compared the effects of acetate (Ac) and acetate-free (Ac-free) dialysate. TGF beta 1 was the only cytokine consistently detected. Compared to normals (median 57, range 53 to 68 pg/ml, one undetected; N = 8), TGF beta 1 was higher in the CRF (75, 70 to 97 pg/ml, one undetected) and CAPD (75.5, 66 to 116 pg/ml, N = 6) groups (P less than 0.05), and was somewhat higher in the HD (68, 52 to 88 pg/ml) group (P less than 0.10). Acutely, TGF beta 1 pre-HD (70, 63 to 88 pg/ml) increased above normals post AcHD [79.5, 65 to 140 pg/ml uncorrected for ultrafiltration (UF)] and was higher after AcHD versus Ac-free HD both uncorrected (79.5, 65 to 140 pg/ml vs. 70, 52 to 86 pg/ml) and corrected for UF (68, 51 to 115 pg/ml vs. 57, 43 to 69 pg/ml; P less than 0.05). beta 2-microglobulin was not different after AcHD (81.2 +/- 8.0 mg/ml) versus Ac-free HD (72.5 +/- 6.9 mg/ml). Significantly lower serum inorganic phosphorus was also found four hours post-AcHD compared to four hours post-Ac-free HD (0.87 mmol +/- 0.10 SEM vs. 1.05 mmol +/- 0.07 SEM; P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1991

The histologic characteristics of the core of the fissula ante fenestram.

In earlier studies of perilymphatic fistulae, we described their histologic criteria and the clinical criteria for the identification and prediction of patencies of the labyrinth capsule related to disorders of hearing and balance. These patencies were either of the fissula ante fenestram or of the round window niche-posterior canal ampulla fissure. The permeability of the fibrous core of a patent fissula ante fenestram has been questioned, authors of some earlier articles arguing that the tissue is loose, others that it is dense. This study demonstrates loose fibrous and cellular structure in the fissula's tract, dense collagen at the circumference. The loose arrangement of tissue suggests that fluid can pass through this patency, and it appears similar to that of the spiral ligament which has been shown to contain perilymph by way of intercellular communications with the perilymphatic space.

Ear, Middle↗
PubMed1990

Pulmonary fibrosis as an unusual clinical manifestation of a pulmonary-renal vasculitis in elderly patients.

Between 1978 and 1988, three patients at our institution had an initial diagnosis of idiopathic pulmonary fibrosis but later were correctly diagnosed as having pulmonary-renal syndrome and microscopic polyarteritis. These cases involved elderly patients with progressive dyspnea and nonproductive cough, bilateral dry crackling rales, bilateral interstitial infiltrates evident on a chest roentgenogram, and restrictive findings on pulmonary function testing. In two patients, lung biopsy specimens were obtained, and an initial diagnosis of nonspecific pulmonary fibrosis was made. All three patients eventually had microhematuria and renal insufficiency. A revised diagnosis of small-vessel pulmonary-renal vasculitis was based on the demonstration of segmental necrotizing glomerulonephritis in renal biopsy specimens in two patients, thrombotic microangiopathy consistent with healed vasculitis on postmortem examination of the kidney in one patient, and subsequent detection of small-vessel vasculitis on review of the two lung biopsy specimens. Anti-neutrophil cytoplasmic antibodies with perinuclear staining on indirect immunofluorescence microscopy were positive in the two patients in whom determinations were performed. The clinical manifestations of vasculitis were notably scarce--no involvement of the skin, nervous system, or gastrointestinal tract; no episodes of fever; and minimal or absent musculoskeletal symptoms. These cases illustrate the importance of a high index of suspicion for the diagnosis of systemic vasculitis in elderly patients and the need to consider a vasculitis in the differential diagnosis of idiopathic pulmonary fibrosis, especially if an active urinary sediment is present.

Aged↗
PubMed1989

Disseminated Aspergillus terreus infection in immunocompromised hosts.

Aspergillus terreus is ubiquitous in the environment but has rarely been found to be pathogenic. When recovered from clinical specimens, it is commonly considered a saprophyte. We report two cases of fatal disseminated A. terreus infection. The first patient was receiving corticosteroid therapy for immune thrombocytopenia when the condition developed, and the second patient was receiving immunosuppressive therapy after bone marrow transplantation for myelodysplasia. We also describe the frequency of recovery of A. terreus in our laboratory. The serious pathogenic potential of A. terreus in immunocompromised hosts should be recognized.

Adrenal Cortex Hormones↗
PubMed1989

Vestibular contribution to spatial orientation. Evidence of vestibular navigation in an animal model.

To determine if animals are capable of utilizing vestibular sensory input for spatial orientation, a six-arm radial maze with a rotating central turntable was constructed. Sprague-Dawley rats were trained on this apparatus by rotating them without visual, auditory, or olfactory cues. Animals were required to locate a reward (located in a constant position relative to the starting position) following random rotations varying from 0 to +/- 360 degrees, growing progressively larger in 60 degrees increments. Normal rats (N = 10) showed a steady improvement in performance over the training and testing period. Bilateral labyrinthectomy (N = 5) produced a profound decrement in that performance (p less than 0.001). When visual cues were added, labyrinthectomized animals improved their performance, but remained significantly below that of normal animals without visual cues (p less than 0.001). Normal animals allowed to use visual cues showed no improvement over their performance without visual cues. The results indicate that rats can utilize vestibular sensory information for navigational purposes. In fact, under these experimental conditions, rats are more successful in utilizing vestibular sensory input for navigation than visual cues.

Animals↗
PubMed1988

Recent advances in the management of venous thromboembolism.

Deep venous thrombosis and pulmonary embolism are frequently diagnosed in patients encountered in a primary-care practice. In the past 10 years, many important advances have been made regarding the management of these disorders. Risk factors have been better defined than in the past. Several new prophylactic measures--such as external pneumatic compression of the lower extremities, dihydroergotamine in combination with heparin, adjusted-dose heparin, and two-step warfarin therapy--can be used to help prevent deep venous thrombosis in surgical patients. The use of serial impedance plethysmography has expanded options for noninvasive diagnosis of deep venous thrombosis. Correlations between pulmonary embolism and ventilation-perfusion lung scan patterns have been clarified. Although much has been learned about heparin and warfarin that affect common management decisions, the indications for thrombolytic therapy for venous thromboembolism remain controversial. Finally, studies have shown that calf vein thrombi that are not detectable by impedance plethysmography and that show no evidence of proximal propagation by serial impedance plethysmography do not require treatment.

Anticoagulants↗
PubMed1988

A comparison of the carbon dioxide and neodymium: YAG lasers in a canine model of acquired subglottic stenosis.

In a previously defined canine model of subglottic stenosis, two different wavelength lasers--the carbon dioxide (CO2) and the neodymium-yttrium aluminum garnet (Nd:YAG)--were used as the principal surgical therapy, and the results were compared. Two lathyrogenic agents, colchicine and penicillamine, were also used in a subset of each treatment group in order to determine their effect as an adjunct to laser therapy in the treatment of subglottic stenosis. The CO2 laser treatment group showed an overall improvement; the Nd:YAG laser treatment group showed a worsening of subglottic stenosis. The dogs treated with the lathyrogenic agents had no added benefit from the use of these agents.

Aluminum↗
PubMed1985

Natural killer cell activity in cigarette smokers and asbestos workers.

In order to evaluate the effects of cigarette smoking and asbestos exposure on cellular immunity, we tested a group of cigarette smokers and asbestos workers for natural killer (NK) activity in the peripheral blood. The mean NK activity in cigarette smokers was lower than in normal subjects (13.7 +/- 1.6 versus 29.0 +/- 3%; p less than 0.05). As a group, the mean NK activity for the asbestos-exposed group was also reduced compared with that of the nonsmoking control group (22.6 +/- 3.2%; p less than 0.05). When divided according to the smoking status, the asbestos workers who were nonsmokers or ex-smokers showed similar decreases in NK activity compared with normal subjects (19.5 +/- 6.2 and 21.2 +/- 4.5%, respectively; p less than 0.05). A subgroup of asbestos-exposed subjects who currently smoked showed no decrease in NK activity. The data show that NK activity is reduced in the peripheral blood of cigarette smokers and asbestos workers. The relatively normal NK activity found in asbestos workers who also smoked is unexplained. Impairment of NK activity is a potential mechanism for the increased incidence of infection and cancer in smokers and neoplasia in asbestos workers.

Adult↗
PubMed1981

Nonlinear characteristics of single neurons in the vestibular nuclei.

The characteristics of response of 99 vestibular nuclei neurons were investigated in the cat anesthetized with pentobarbital sodium. All neurons responded to stimulation of the horizontal semicircular canals (HSCC) with prolonged 2, 4, 6, or 8 degrees/second2 angular acceleration. Neural response was recorded utilizing the single-neuron recording technique. The vestibular neurons responded nonlinearly to stimulation of the HSCC. Specifically (1) the time required to reach the maximum response level decreased nonlinearly with an increase in stimulus magnitude (SM); (2) the maximum response level increased nonlinearly with the increase in SM: (3) the neural response to excitatory stimulus was not the mirror image of that to an inhibitory stimulus. Several existing mathematical models were simulated by utilization of the IBM Continuous System Modeling Program, account for the nonlinear response of the vestibular nuclei neurons. The nonlinearities observed in the responses may be due to (1) nonlinear behavior of the end organ, (2) the influence of the CNS including the vestibular efferent system, or (3) the inherent neural properties of the vestibular nuclei.

Acceleration↗