Biomedical subjects

H Chung

Publications and source records attributed to H Chung.

At least 91 records · Page 5Linked to original sources

PubMed1995

Health care reform: implications for academic psychiatric institutions.

Health care reform provides an opportunity to redefine all aspects of our health care delivery system. This article focuses on mental health services and on the implications of health care reform for academic psychiatric institutions. Questions are raised regarding the challenges that academic psychiatric centers will face in pursuing the traditional responsibilities of research, education, and clinical care. The authors propose that intersystems dialogue will create solutions to the questions. The challenge to academic psychiatric institutions rests in creating the dialogue that will inform and guide new decisions regarding research, education, and clinical priorities with the ultimate aim of ensuring that quality is preserved through reform.

Academic Medical Centers↗

PubMed1995

Simultaneous measurement of glucose and glutamine in aqueous solutions by near infrared spectroscopy.

A method is described for measuring the concentrations of both glucose and glutamine in binary mixtures from near infrared (NIR) absorption spectra. Spectra are collected over the range from 5000-4000/cm (2.0-2.5 microns) with a 1-mm optical path length. Glucose absorbance features at 4710, 4400, and 4300/cm and glutamine features at 4700, 4580, and 4390/cm provide the analytical information required for the measurement. Multivariate calibration models are generated by using partial least squares (PLS) regression alone and PLS regression combined with a preprocessing digital Fourier filtering step. The ideal number of PLS factors and spectral range are identified separately for each analyte. In addition, the optimum Fourier filter parameters are established for both compounds. The best overall analytical performance is obtained by combining Fourier filtering and PLS regression. Glucose measurements are established over the concentration range from 1.66-59.91 mM, with a standard error of prediction (SEP) of 0.32 mM and a mean percent error of 1.84%. Glutamine can be measured over the concentration range from 1.10-30.65 mM with a SEP of 0.75 mM and a mean percent error of 6.67%. These results demonstrate the analytical utility of NIR spectroscopy for monitoring glucose and glutamine levels in mammalian and insect cell cultures.

Buffers↗

PubMed1995

Polymorphism, mesomorphism, and metastability of monoelaidin in excess water.

The polymorphic and metastable phase behavior of monoelaidin dry and in excess water was studied by using high-sensitivity differential scanning calorimetry and time-resolved x-ray diffraction in the temperature range of 4 degrees C to 60 degrees C. To overcome problems associated with a pronounced thermal history-dependent phase behavior, simultaneous calorimetry and time-resolved x-ray diffraction measurements were performed on individual samples. Monoelaidin/water samples were prepared at room temperature and stored at 4 degrees C for up to 1 week before measurement. The initial heating scan from 4 degrees C to 60 degrees C showed complex phase behavior with the sample in the lamellar crystalline (Lc0) and cubic (Im3m, Q229) phases at low and high temperatures, respectively. The Lc0 phase transforms to the lamellar liquid crystalline (L alpha) phase at 38 degrees C. At 45 degrees C, multiple unresolved lines appeared that coexisted with those from the L alpha phase in the low-angle region of the diffraction pattern that have been assigned previously to the so-called X phase (Caffrey, 1987, 1989). With further heating the X phase converts to the Im3m cubic phase. Regardless of previous thermal history, cooling calorimetric scans revealed a single exotherm at 22 degrees C, which was assigned to an L alpha+cubic (Im3m, Q229)-to-lamellar gel (L beta) phase transition. The response of the sample to a cooling followed by a reheating or isothermal protocol depended on the length of time the sample was incubated at 4 degrees C. A model is proposed that reconciles the complex polymorphic, mesomorphic, and metastability interrelationships observed with this lipid/water system. Dry monoelaidin exists in the lamellar crystalline (beta) phase in the 4 degrees C to 45 degrees C range. The beta phase transforms to a second lamellar crystalline polymorph identified as beta* at 45 degrees C that subsequently melts at 57 degrees C. The beta phase observed with dry monoelaidin is identical to the LcO phase formed by monoelaidin that was dispersed in excess water and that had not been previously heated.

Biophysical Phenomena↗

PubMed1995

Racial differences in treatment of psychiatric inpatients.

OBJECTIVE: The study examined several aspects of inpatient psychiatric treatment to determine if differences existed between treatment of African-American and white patients. METHODS: Using a structured chart review, data were collected on 76 African-American and 88 white patients consecutively admitted to an acute inpatient setting with a principal axis I diagnosis of a major mood or psychotic disorder. Racial differences in treatment were examined using analysis of variance and logistic regression to assess the effects of diagnosis and socioeconomic status. RESULTS: Nonpsychotic African-American patients had shorter lengths of stay than white patients with similar disorders. White patients were more likely to be on one-to-one observational status. Clinicians were more likely to order urine drug screens for African-American patients with high socioeconomic status than for comparable white patients. African-American patients with schizophrenic disorders received higher neuroleptic dosages than white patients with similar diagnoses. CONCLUSIONS: Most racial differences cited in earlier studies of psychotic patients were not found or were not statistically significant once socio-economic status and diagnosis were accounted for. However, racial differences related to the detection, phenomenology, treatment, and course of psychotic disorders and the diagnosis and management of alcohol and drug use disorders and personality disorders were found.

Adolescent↗

PubMed1995

Facial dimple with accessory bone and teeth.

Accessory jaws (distomus), with or without teeth, rarely occur. This condition has been observed most commonly in association with lateral facial clefts. A case of a 6-year-old child with a unilateral facial dimple which is interpreted as a putative vestige of a lateral facial cleft and accessory maxilla is reported. Possible aetiology is addressed and previous cases are reviewed.

Child↗

PubMed1995

The effect of subtenon injection of methylprednisolone acetate on the breakdown of blood retinal barrier after cryotherapy.

Using computerized vitreous fluorophotometry (VFP, Fluorotron), we examined the effect of cryotherapy on the blood retinal barrier (BRB) and the effect of subtenon injection of methylprednisolone acetate (Depomedrol). In experiment 1, the right eyes of the 13 pigmented rabbits were treated with heavy cryotherapy after baseline VFP readings. The freezes were applied at 6 places in each quadrant around the equator are in two rows, a total of 24 places circumferentially. The left eyes were reserved as controls. In 6 rabbits (cryo with steroid group), Depomedrol 10 mg of Depomedrol was injected into subtenon space after cryotherapy. The other 7 rabbits were treated with cryotherapy only (cryo only group). The VFP readings were taken 1, 3, 5, and 7 days, 2, 3, 5, and 7 weeks after cryotherapy. Cryotherapy increased the breakdown of BRB significantly. The peak VFP readings were obtained 5 days after cryotherapy in the cryo only group and 7 days after cryotherapy in the cryo with steroid group. In the cryo only group, the severity of the breakdown of BRB was higher than in the cryo with steroid group, and the increased VFP readings could not be normalized until 7 weeks after cryotherapy. In experiment 2, both eyes of the 8 pigmented rabbits were treated with medium cryotherapy after baseline VFP readings. The freezes were applied at 3 places in the superior temporal quadrant and at 3 places in the superior nasal quadrant, a total of 6 places. Depomedrol 10 mg was injected into subtenon space after cryotherapy in the right eyes only.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

The curvature elastic-energy function of the lipid-water cubic mesophase.

Cell and lipid membranes are able to bend, as manifested during membrane fusion and the formation of non-lamellar lyotropic mesophases in water. But there is an energy cost to bending of lipid layers, called the curvature elastic energy. Although the functional form of this energy is known, a complete quantitative knowledge of the curvature elastic energy, which is central to predicting the relative stability of the large number of phases that lipid membranes can adopt, has been lacking. Here we use X-ray synchrotron diffraction measurements of the variation of lattice parameter with pressure and temperature for the periodic Ia3d (Q230) cubic phase of hydrated monoolein to calculate the complete curvature elastic-energy function for the lipid cubic mesophase. This allows us to predict the stabilities of different cubic and lamellar phases for this system as a function of composition.

Glycerides↗

PubMed1994

The neutral area surface of the cubic mesophase: location and properties.

A neutral area surface can be defined as one whose area remains fixed upon bending. It is assumed that such a surface exists within the amphiphilic monolayers that constitute the bicontinuous cubic mesophases and that it parallels approximately the highly convoluted polar/apolar interface in such systems. Here, we report on how the neutral area surface in the cubic phase (space group Ia3d) of the hydrated monoacylglycerol, monoolein, was determined. It is located at a distance of approximately 8.8 A from the methyl terminus of the acyl chain. At 25 degrees C, the surface area per lipid molecule at the neutral area surface is 35.1 +/- 0.2 A2, which is remarkably similar to the mean cross-sectional area of hydrated monoolein in the lamellar liquid crystalline phase at this same temperature.

Biophysical Phenomena↗

PubMed1994

Urinary methamphetamine concentration following famprofazone administration.

A 37-year-old man had a considerable concentration of methamphetamine in his urine, but he denied taking any abused drug. It was found that he took a pain killer that contains famprofazone, a relatively strong analgesic whose metabolites include methamphetamine and amphetamine. The human urinary metabolism of famprofazone was investigated. Immunoassay was used as a preliminary test, and gas chromatography with flame-ionization detection and gas chromatography-mass spectrometry were used for quantitation and confirmation.

Adult↗

PubMed1994

Results of vitreous surgery for posterior complications of chronic uveitis.

To determine surgical results and predictive factors of final visual acuity, a total of 30 eyes in 30 uveitis patients who underwent vitreous surgery including pars plana vitrectomy were followed for at least 6 months and various preoperative factors and postoperative results were analyzed. Our surgical indications were vitreous opacity, traction retinal detachment, combined rhegmatogenous-traction detachment. Preoperatively detached retina was finally reattached in 15 (83.3%) of 18 eyes. Final visual acuity improved in 19 (63.3%) of 30 eyes, but decreased in 3 eyes compared with the initial acuity. Cystoid macular edema was the main cause of poor visual acuity after surgery. Eyes with good final visual acuity showed relatively normal electroretinograms before surgery, but the relationship between them was not statistically significant. Duration of postoperative inflammation affected final visual acuity significantly. These results suggest that chronic uveitis patients with vitreoretinal complications can be managed by vitreous surgery with good anatomic and functional results.

Adolescent↗

PubMed1994

Vitrectomy for severe proliferative diabetic retinopathy.

To analyse the results of diabetic vitrectomy according to the severity of proliferation [severe (SPG) vs. less-severe proliferation group (LSPG)], and methods of the operation, which was complete removal of anteroposterior vitreous traction with or without complete removal of preretinal memebrane, we compared both groups by using anatomic success rate and postoperative visual acuities (VA). The results were as follows: The anatomic success rate and postoperative VA were significantly better in LSPG than in SPG. In SPG, anatomic success rate and postoperative VA tended to be better when complete removal of anteroposterior traction was possible than when impossible. In SPG, postoperative VA tended to be better when complete removal of preretinal membrane was possible, but the anatomic success rate was the same for each group. So, when severe proliferation (including table-top elevation of posterior retina), complete removal of anteroposterior traction only can improve the anatomic success rate of the surgery.

Adult↗

PubMed1993

Relationship between NMR transverse relaxation, trabecular bone architecture, and strength.

Structure, biomechanical competence, and incremental NMR line broadening (R'2) of water in the intertrabecular spaces of cancellous bone were examined on 22 cylindrical specimens from the lumbar vertebral bodies of 16 human subjects 24-86 years old (mean, 60 years old). A strong association (r = 0.91; P < 0.0001) was found between Young's modulus of elasticity and R'2 for a wide range of values corresponding to cancellous bone of very different morphologic composition. NMR line broadening is caused by the inhomogeneity of the magnetic field induced as a consequence of the coexistence of two adjacent phases of different diamagnetic susceptibility--i.e., mineralized bone and water in the marrow spaces. Structural analyses performed by means of NMR microscopy and digital image processing indicated that the variation in R'2 is closely related to the trabecular microstructure. Mean trabecular plate density measured along the direction of the magnetic field was found to play a major role in predicting R'2 (r = 0.74; P < 0.0001). This behavior was confirmed when the plate density was varied in individual specimens, which was achieved by rotating the specimen, making use of the bone's structural anisotropy. It is concluded that the NMR transverse relaxation rate in human cancellous bone of the spine is significantly determined by trabecular structural parameters relevant to biomechanical strength. The results further underscore the important role played by the transverse trabeculae in contributing to cancellous bone strength. The work has implications on possible in vivo use of quantitative magnetic resonance for the assessment of fracture risk in osteoporotic patients.

Bone Marrow↗

PubMed1993

Bioavailability and disposition kinetics of HI-6 in Beagle dogs.

The absorption and disposition kinetics of HI-6 were determined in Beagle dogs given single doses (25 mg kg-1) of the drug by the intravenous, intramuscular, and oral routes. Concentrations of the oxime in plasma and urine were measured by HPLC. A two-compartment open model was used to describe the disposition curve following intravenous drug administration while a one-compartment open model with first-order absorption adequately described the data following intramuscular or oral administration of the dose. Extravascular distribution of HI-6 was limited (Vss 203 ml kg-1) and the drug was eliminated rapidly after intravenous administration (t1/2 46.5 min, MAT 55.4 min). Systemic clearance was 3.68 ml min-1 x kg. A major fraction of the dose (63.7 per cent) was excreted in urine over a 24-h collection period. Following intramuscular drug administration, the absorption half-life (t1/2(a), 5.3 min), MAT (17.1 min), Cmax (70.37 micrograms ml-1) and tmax (15.9 min) indicate that the drug was rapidly absorbed. Systemic availability was 83.43 per cent after oral drug administration, absorption was preceded by a lag time (23.2 min). The t1/2(a) (41.5 min), MAT (81.6 min), Cmax (4.30 micrograms ml-1) and Tmax (90.6 min) indicate somewhat delayed absorption. Systemic availability (11.38 per cent) and the fraction of dose excreted unchanged in the urine (9.3 per cent) show that the drug was poorly absorbed. The apparent half-life (58.0 min) and MRT (137.6 min) following oral administration were significantly longer (p < 0.05) than following intravenous or intramuscular administration suggesting that the rate of absorption from the gastrointestinal tract decreases the elimination rate of the drug. In conclusion, HI-6 has limited distribution within the body, is rapidly eliminated mainly by renal excretion unchanged in the urine, and the bioavailability (i.e. rate and extent of absorption) of the drug varies with the route of administration.

Administration, Oral↗

PubMed1993

High-resolution variable flip angle 3D MR imaging of trabecular microstructure in vivo.

Two conceptually related variable-flip-angle 3D spin-echo pulse sequences were designed for imaging at voxel sizes of 2-5 x 10(-3) mm3 corresponding to pixel areas of less than 100 x 100 microns2 and section thicknesses on the order of 300-400 microns on a conventional 1.5 T MR imaging system equipped with 1 G/cm imaging field gradients, providing 12 sections in 10 min imaging time. The pulse sequences make use of the concept of restoring longitudinal magnetization inverted by the 180 degrees phase reversal pulse and are derivatives of pulse sequences previously dubbed "FATE" and "RASEE." It is shown that even in the small-voxel regime (< 10(-2) mm3 voxel size) and at echo times on the order of 10 ms, gradient echo images are sensitive to intrinsic fields causing artifactual boundary effects, including signal loss from intravoxel phase scrambling and spatial mismapping. At this resolution the variable flip-angle spin-echo pulse sequences are demonstrated to be better suited for imaging magnetically heterogeneous systems such as trabecular bone microstructure in vivo. These pulse sequences are found to be substantially less sensitive to distortions from magnetic dipole fields occurring at the boundaries of two phases of different magnetic permeability.

Bone and Bones↗

PubMed1993

Non-steroidal anti-inflammatory drug and endotoxin induced uveitis.

Suprofen eye drop was instilled into one eye of 10 pigmented rabbits and then anterior uveitis was induced by intraperitoneal injection of endotoxin of Shigella flexneri serotype 1A to evaluate the effects of non-steroidal anti-inflammatory drug on endotoxin induced uveitis. The pupillary diameters were measured, and aqueous cell and flare gradings were recorded in 20 eyes of 10 rabbits for one week at an interval of 12 hours for the first 24 hours and then every 24 hours for a week. A difference between the treated and control groups were investigated. All the above parameters showed greatest changes at 12 or 24 hours after injection and became normal by one week. The two groups demonstrated statistically significant difference at 12 hours, day 1 and day 2 as for pupillary diameter, at day 1 and day 2 as for cell and at 12 hours and day 1 as for flare. Thus, it can be concluded that prostaglandins play a role in miosis, in the appearance of inflammatory cells and flare in endotoxin induced uveitis and the topical administration of non-steroidal anti-inflammatory drug can alleviate signs of anterior uveitis. Specific relationship between leukotriene B4 and aqueous cell was not demonstrated.

Administration, Topical↗

PubMed1992

Direct correlation of structure changes and thermal events in hydrated lipid established by simultaneous calorimetry and time-resolved x-ray diffraction.

In many lipid systems, polymorphic and mesomorphic behavior depends on sample thermal history. To establish unequivocally the structural origin of endothermic and exothermic events in such systems, we have performed simultaneous calorimetry and time-resolved x-ray diffraction (SCALTRD). To this end, aluminum calorimetry crucibles were used to contain the hydrated lipid sample, and the calorimeter was mounted with the base of the crucible oriented perpendicular to a synchrotron-derived focused monochromatic x-ray beam for SCALTRD data collection. Measurements were made with hydrated monoelaidin and 1,2-dielaidoyl-sn-glycero-3-phosphoethanolamine (DEPE) contained in hermetically sealed crucibles. Time-resolved x-ray diffraction (TRXRD) data were collected using an x-ray image intensifier/video system and a streak camera containing an x-ray sensitive image plate and/or film. SCALTRD analysis of the lamellar gel to lamellar liquid crystalline phase transition in hydrated monoelaidin gives identical progress curves by calorimetry and TRXRD at a scan rate of 1 degree C/min. At faster rates, calorimetry shows a broader phase transition that starts at a lower and ends at a higher temperature than is observed by TRXRD. The disparity arises in part because the x-ray beam used in TRXRD interrogates only a small portion of the sample, whereas the calorimeter responds to the entire sample volume. Because data collection times are relatively long, radiation damage is an important potential problem for SCALTRD measurements. Such an effect was observed with DEPE/water in that TRXRD shows the lamellar gel to lamellar liquid crystalline phase transition occurring at a lower temperature than observed by calorimetry. We speculate that the sample accumulates impurities locally as a result of radiation damage that has the effect of lowering the phase transition temperature at the site of interrogation by the x-ray beam. This "methods-in-combination" SCALTRD approach facilitates the direct correlation of structure rearrangements and thermal events in the same sample under identical conditions of thermal history. The information content of the data so derived far surpasses that available from either method used in isolation.

Calorimetry↗

PubMed1992

Immunopathology of experimental autoimmune uveoretinitis in primates.

The eyes and pineal glands from 10 monkeys immunized with S-antigen were studied using routine histopathological and immunohistochemical techniques. Seven out of 10 animals developed uveitis between 19 and 33 days after the initial immunization. Histopathology of the eyes harvested 70 days after immunization showed moderate to marked uveoretinitis, subretinal fibrosis, retinal necrosis and gliosis. The pineal glands demonstrated chronic pinealitis. The infiltrating cells were both CD3 and CD19/CD22 lymphocytes with a ratio of 1.4 in the eye and 2.2 in the pineal gland. The ratio of CD4 to CD8 lymphocytes was 1.5:1. MHC Class II antigens and adhesion molecule (ICAM-1) were observed on resident cells. The influx of B lymphocytes and the formation of subretinal fibrosis differentiate the disease in the monkey from that in the rat and mouse. These findings are similar to Vogt-Koyanagi-Harada syndrome and subretinal fibrosis with uveitis syndrome in human.

Animals↗

PubMed1992

Distribution of prostaglandin E2 in gastric and duodenal mucosa: possible role in the pathogenesis of peptic ulcer.

BACKGROUND: Prostaglandin E which is present abundantly in the gastric mucosa is a powerful inhibitor of gastric acid secretion and a stimulus to gastric mucus production. In addition, prostaglandin E2 inhibits ulcer formation in animals, and the synthetic analogues of prostaglandin E have successfully been used in the treatment of patients with gastric and duodenal ulcer disease. To evaluate the role of endogenous prostaglandin E2 in the pathogenesis of the peptic ulcer disease, we measured mucosal prostaglandin E2 levels in patients with gastric and duodenal ulcer disease and compared with that of non-ulcer control persons. METHODS: The study population was made up of 44 non-ulcer persons, 36 patients with a benign gastric ulcer, and 48 with a duodenal ulcer. Every mucosal specimen, taken from the antrum and from the duodenal bulb, were homogenized, mixed with 1 M HCl, and centrifuged. After removal of the supernatant, precipitate was eluted with ethyl acetate in the Amprep C18 minicolumn. Then the extracted prostaglandin E2 in the ethyl acetate fractions was converted into its methyl oximate derivatives, and the prostaglandin E2 level was measured by radioimmunoassay. During the procedure any homogenized specimen which was looking grossly bloody was removed from the assay in order to avoid any possible contamination or prostaglandin E2 in blood. RESULTS: In non-ulcer persons, the mean values was 258.17 +/- 127.03 pg/mg. tissue in antrum and 121.07 +/- 67.46 pg/mg. tissue in duodenal bulb. The corresponding values were 186.42 +/- 70.51 pg/mg. tissue, 79.44 +/- 39.04 pg/mg. tissue in gastric ulcer patients and 204. 94 92.03 pg/mg. tissue, 99.66 +/- 56.10 pg/mgl. tissue in duodenal ulcer patients respectively. Gastric ulcer patients have the significantly lower level of the antral and duodenal prostaglandin E2 (p < 0.005). Those levels of duodenal ulcer patients were also significantly lower than those of non-ulcer persons (p < 0.025 & 0.05). Antral prostaglandin E2 level increased to 305.21 +/- 104.91 pg/mg. tissue in the gastric ulcer patients (p < 0.005) and to 271.02 +/- 93. 23 pg/mg. tissue in the duodenal ulcer (p < 0.005) when the ulcer crater was healed. The duodenal bulb prostaglandin E2 level was also increased in the healed stage of ulcer, e. g., 128.84 +/- 57.62 (p < 0.005) and 112.60 +/- 42.25 pg/mg. tissue, respectively. CONCLUSION: These results suggest that prostaglandin deficiency in the antral and duodenal bulb mucosa may have an important role in the pathogenesis of peptic ulcer disease.

Adult↗