351
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Romdhane IH, Plana A, Hwang S, Danner RP. Thermodynamic interactions of solvents with styrene–butadiene–styrene triblock copolymers. J Appl Polym Sci 1992. [DOI: 10.1002/app.1992.070451120] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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352
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Gupta SK, Southam M, Hwang S. Pharmacokinetics of droperidol in healthy volunteers following intravenous infusion and rectal administration from an osmotic drug delivery module. Pharm Res 1992; 9:694-6. [PMID: 1608906 DOI: 10.1023/a:1015822715190] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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353
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Altman ES, Rea MM, Mintz J, Miklowitz DJ, Goldstein MJ, Hwang S. Prodromal symptoms and signs of bipolar relapse: a report based on prospectively collected data. Psychiatry Res 1992; 41:1-8. [PMID: 1561285 DOI: 10.1016/0165-1781(92)90012-r] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Prospectively collected data on 19 recently hospitalized patients with bipolar disorder were examined for prodromal changes preceding relapse. The 4-month periods before six manic and six depressive relapses were compared with each other and with a comparable period for seven patients who did not relapse. The Brief Psychiatric Rating Scale was used to assess symptoms. Significant elevations in unusual thought content were found 1 month before manic relapse. Depressive relapsers evidenced higher levels of conceptual disorganization throughout the prerelapse period. Nonrelapsers showed very stable symptom profiles.
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354
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Rea MM, Strachan AM, Goldstein MJ, Falloon I, Hwang S. Changes in patient coping style following individual and family treatment for schizophrenia. Br J Psychiatry 1991; 158:642-7. [PMID: 1860018 DOI: 10.1192/bjp.158.5.642] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Changes in relatives' affective attitudes are important contributors to the impact of family psychoeducational programmes on the course of schizophrenia. It remains unclear whether similar changes occur in the interactional style of schizophrenic patients participating in psychoeducational treatment. This study examined changes in the interactional style (coping style) of 33 schizophrenic patients in individual or family treatment. Significant changes were seen in the interactional style of the patients participating in the individual treatment. Similar changes were evident, but not significant, in the family treatment group. The quality of patient interactional style before or after treatment did not predict relapse in either group. Changes in relatives' interactional style early in family treatment are necessary to affect the short-term course of schizophrenia. Modification in patient behaviour during the early phase does not have similar predictive value.
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355
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Hwang S, Stevenson WG, Weiner I, Sherman CT. Delayed presentation of cardiac perforation after apparently successful catheter ablation for incessant ventricular tachycardia. Am Heart J 1990; 120:1465-6. [PMID: 2248199 DOI: 10.1016/0002-8703(90)90270-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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356
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Hwang S, Bohman R, Navas P, Norman JT, Bradley T, Fine LG. Hypertrophy of renal mitochondria. J Am Soc Nephrol 1990; 1:822-7. [PMID: 2133432 DOI: 10.1681/asn.v15822] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Compensatory renal hypertrophy leads to an increase in the size and metabolic capacity of renal tubular cells. Increased transport and metabolic activities must be sustained by an augmented rate of energy production, which is largely dependent on mitochondrial processes. Although previous studies have suggested that mitochondria proliferate in the hypertrophying cell, the data to support this have not been convincing. This study was designed to determine whether the mitochondria of the hypertrophied renal proximal tubular cell undergo hypertrophy or proliferation. Flow cytometric analysis of proximal tubular cells obtained from the kidneys of uninephrectomized rabbits revealed an increase in cell size and RNA content compared with control cells but showed no change in DNA content and nuclear size and no evidence of entry into the S/G2/M phases of the cell cycle. Histomorphometric analysis of cortical proximal tubules revealed that although cytoplasmic volume increased, mitochondrial density remained constant, indicating that mitochondrial volume increases in proportion to the increase in cell volume. By day 14, mitochondrial volume had increased 66% above control values. Electron microscopic examination of isolated S2 proximal tubules from 5/6 nephrectomized rabbits with maximal hypertrophy revealed mitochondrial cristae which appeared to be more densely packed than that in normal cells. The size of the functional mitochondrial pool per cell was determined by rhodamine-123 fluorescence. This increased within 24 h of uninephrectomy, peaked at approximately 80% above control levels at 5 days, and remained elevated throughout the 16 days of observation. The initial increase (days 1 and 2) occurred before a measurable increase in mitochondrial volume occurred and presumably reflects an increase in mitochondrial membrane potential.(ABSTRACT TRUNCATED AT 250 WORDS)
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357
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Hwang S, Saenz R. The problem posed by immigrants married abroad on intermarriage research: the case of Asian Americans. INTERNATIONAL MIGRATION REVIEW 1990; 24:563-76. [PMID: 12316439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/19/2023]
Abstract
"Cross-sectional and longitudinal variations in rates of intergroup marriage [in the United States] have often been used as indicators of assimilation for minority groups. This article demonstrates that both types of comparisons can give misleading results when census data are used for calculating intermarriage rates without restrictions. Census data include immigrants who married abroad (IMAs) in the enumeration. The inclusion of these individuals in the study of intermarriage inevitably biases the level of minority inmarriage upward, making cross-sectional and longitudinal comparisons of intermarriage rates for groups with different levels of IMAs inappropriate. Cumulation of IMAs also inflates the inmarriage rates of older cohorts, leading to a misimpression of increasing outmarriage among younger cohorts. These problems are illustrated for several Asian groups using 1980 Public Use Microdata Sample data for California. Alternative approaches for remedying the problem are proposed and their different implications for assimilation theory and research are discussed."
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358
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Hwang S, Jascur T, Vestweber D, Pon L, Schatz G. Disrupted yeast mitochondria can import precursor proteins directly through their inner membrane. J Biophys Biochem Cytol 1989; 109:487-93. [PMID: 2668297 PMCID: PMC2115710 DOI: 10.1083/jcb.109.2.487] [Citation(s) in RCA: 93] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Import of precursor proteins into the yeast mitochondrial matrix can occur directly across the inner membrane. First, disruption of the outer membrane restores protein import to mitochondria whose normal import sites have been blocked by an antibody against the outer membrane or by a chimeric, incompletely translocated precursor protein. Second, a potential- and ATP-dependent import of authentic or artificial precursor proteins is observed with purified inner membrane vesicles virtually free of outer membrane components. Third, import into purified inner membrane vesicles is insensitive to antibody against the outer membrane. Thus, while outer membrane components are clearly required in vivo, the inner membrane contains a complete protein translocation system that can operate by itself if the outer membrane barrier is removed.
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359
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Lozano JJ, Silberstein GB, Hwang S, Haindl AH, Rocha V. Developmental regulation of calcium-binding proteins (calelectrins and calpactin I) in mammary glands. J Cell Physiol 1989; 138:503-10. [PMID: 2522458 DOI: 10.1002/jcp.1041380309] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We recently showed that mammary glands contain a novel class of calcium-binding proteins (CBPs) that bind to membranes in a calcium-dependent manner. We have also established that these mammary CBPs are equivalent to the calelectrins and calpactin I/p36. Since it has been suggested that these proteins might be involved in exocytosis, we examined mammary glands for these CBPs during secretory differentiation. Immunohistochemical examination showed glands from virgin animals to be rich in calelectrins and calpactin I/p36, while glands from lactating animals contained little immunoreactive material. In addition, silver-staining and immunoblot estimation of the CBPs in lysates from collagenase harvested secretory epithelia showed these proteins to be significantly reduced compared to nonsecretory epithelia. Close examination of the CBP immunoreactive cells of the mammary gland shows that ductal cells are prominent in their staining and that the immunoreactive material is associated with the cell surface. Also, in juvenile glands the myoepithelial stem cells (cap cells) of the elongating end bud are devoid of the CBPs. In contrast to the in vivo data, epithelia cultivated on collagen gels demonstrate comparable levels of the CBPs in both nonsecretory and secretory monolayers. The in vivo data indicate that the CBPs are developmentally regulated during mammary gland differentiation such that secretory epithelia are essentially devoid of these novel proteins. Furthermore, a role for calelectrin and calpactin I/p36 in exocytotic casein secretion is questioned.
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360
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Baratta R, Ichie M, Hwang S, Solomonow M. Method for studying muscle properties under orderly stimulated motor units with tripolar nerve cuff electrode. JOURNAL OF BIOMEDICAL ENGINEERING 1989; 11:141-7. [PMID: 2704216 DOI: 10.1016/0141-5425(89)90125-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
An electrical nerve stimulation technique, using single tripolar electrode, was shown to be capable of recruiting motor units according to their size, while allowing simultaneous but independent control of firing rate in the active units. Test paradigms consisting of established fundamental physiological concepts of soleus-gastrocnemius architecture, firing rate behaviour of motor units of different sizes, and their susceptibility to fatigue were employed to validate the technique and demonstrate its utility as a basic and applied research tool.
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361
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Baratta R, Solomonow M, Hwang S, Itchie M. The dynamic model of skeletal muscle: I. Response of nine different muscle. J Biomech 1989. [DOI: 10.1016/0021-9290(89)90112-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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362
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Eilers M, Verner K, Hwang S, Schatz G. Import of proteins into mitochondria. Philos Trans R Soc Lond B Biol Sci 1988; 319:121-6. [PMID: 2901761 DOI: 10.1098/rstb.1988.0036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
A mounting body of evidence suggests that cytoplasmically synthesized proteins destined to be imported into the mitochondrial interior must at least partly unfold to penetrate across the mitochondrial membranes. During post-translational import, this unfolding process appears to be a major rate-limiting step. It can be blocked by ligands that stabilize the protein's native conformation and appears to be accompanied by the cleavage of ATP outside the mitochondrial inner membrane.
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363
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Eilers M, Hwang S, Schatz G. Unfolding and refolding of a purified precursor protein during import into isolated mitochondria. EMBO J 1988; 7:1139-45. [PMID: 2841112 PMCID: PMC454448 DOI: 10.1002/j.1460-2075.1988.tb02923.x] [Citation(s) in RCA: 129] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
A purified mitochondrial precursor protein unfolds to a protease-sensitive conformation at the surface of isolated mitochondria before being imported into the organelles. This unfolding is stimulated by a potential across the mitochondrial inner membrane, but does not require ATP. In contrast, import of the surface-bound unfolded precursor requires ATP, but no potential; it is accompanied by a refolding inside the mitochondria.
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364
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Garvey MJ, Hwang S, Teubner-Rhodes D, Zander J, Rhem C. Dextroamphetamine treatment of mania. J Clin Psychiatry 1987; 48:412-3. [PMID: 3312177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Five of six acutely manic patients treated with dextroamphetamine experienced a 50% or greater reduction in their mania severity scores. Side effects were noted in only one patient. The treatment results suggest that dextroamphetamine might be useful in the treatment of mania.
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365
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DesMarteau D, O'Brien B, Bauknight C, Singh S, Hwang S, Storzer W. Chemistry of carbonnitrogen multiple bonds. The useful synthon CF2NBr. J Fluor Chem 1985. [DOI: 10.1016/s0022-1139(00)83328-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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366
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DesMarteau D, O'Brien B, Bauknight C, Singh S, Hwang S, Storzer W. Novel chemistry of the extraordinary acid (CF3SO2)2NH. J Fluor Chem 1985. [DOI: 10.1016/s0022-1139(00)83283-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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367
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DesMarteau D, O'Brien B, Bauknight C, Singh S, Hwang S, Storzer W. Fluorination of halides with potassium fluoride; an old reaction—a new catalyst. J Fluor Chem 1985. [DOI: 10.1016/s0022-1139(00)83287-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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368
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Yan SC, Hwang S, Rustan TD, Frey WH. Human brain tubulin purification: decrease in soluble tubulin with age. Neurochem Res 1985; 10:1-18. [PMID: 3982586 DOI: 10.1007/bf00964768] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The soluble tubulin of human cerebral cortex, as assessed by [3H]colchicine binding of the 100,000 g supernatant fraction, decreases drastically with age, 75 percent from age 0 to age 90. There is also a considerably lower concentration of high molecular weight proteins in the soluble fraction of postmortem human cerebral cortex than in that of nonhuman species. Human brain tubulin can be polymerized into microtubules with DEAE-dextran. The DEAE-dextran induced microtubules are stable to cold temperature (4 degrees) and calcium. However, in the presence of 1 M glutamate, the microtubules become cold labile and depolymerize at 4 degrees. Thus we have developed a novel method for purifying polymerization competent tubulin from fresh or frozen human cerebral cortex. Human brain tubulin purified by our novel method is very similar to tubulin from the brains of other mammals in molecular weight, amino acid composition, polymerization-depolymerization parameters, and structural dimensions of the microtubules formed.
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369
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Hwang S, Zander J, Garvey M. Dexamethasone suppression test: use of two different dexamethasone doses. J Clin Psychiatry 1984; 45:390-2. [PMID: 6469924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The endocrinologic methods used in the dexamethasone suppression test (DST) for depression were examined, by employing two different doses of dexamethasone (0.5 or 1.0 mg) at 11 p.m. Nonsuppression to the 1.0 mg DST (plasma cortisol criterion value of 5 micrograms/dl) was seen in 33% of major depressives and in 15% of schizophrenics. A similar result was obtained with the 0.5 mg DST when 12 micrograms/dl was employed as the plasma cortisol criterion value. Plasma cortisol levels 33 hours postdexamethasone did not distinguish between major depressives and schizophrenics.
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370
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Verbesselt R, Tjandramaga TB, Mullie A, De Schepper PJ, Cook T, Derouwaux C, Kramp R, Hwang S. Comparative multiple dose kinetics of two formulations of indomethacin. Eur J Clin Pharmacol 1983; 24:563-8. [PMID: 6861873 DOI: 10.1007/bf00609904] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The kinetics of a controlled release (CR) formulation of indomethacin 75 mg (Indocid-Retard) given once daily was compared with a conventional 25 mg indomethacin capsule (Indocid) given 3 times daily for 7 days, to 14 healthy volunteers, using a randomized, cross-over, multiple-dose study design. The following differences in plasma indomethacin profiles after the 2 treatments were observed: average peak concentrations (Cmax) for the CR regimen were higher and the time to peak (Tmax) was significantly delayed. Trough (pre-morning dose) plasma concentrations (Cmin) on Days 2, 5, 6 and 7 were significantly lower after the CR-formulation. No statistically significant differences between preparations for area under the plasma concentration time curve (AUC0-24 h) or for renal clearance were observed. Average steady-state plasma concentrations (Cssp) on Day 7 of the multiple dose regimens averaged 0.477 and 0.427 microgram/ml for the 75 mg CR once daily and the conventional 25 mg t.i.d. treatments, respectively. These results show that the bioavailability of the CR and conventional indomethacin formulations under these multiple-dose conditions was not significantly different.
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371
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Garvey MJ, Tuason VB, Blomquist CH, Hwang S. Use of renal enzymes to evaluate nephrotoxicity in lithium treated patients. Br J Psychiatry 1982; 141:420-2. [PMID: 7171913 DOI: 10.1192/bjp.141.4.420] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
N-acetyl-beta-glucosaminadase (NAG) is a renal enzyme which is an early, sensitive and reliable indicator of renal damage. NAG assays of midstream spot urines were not significantly different in a group of controls when compared to patients starting lithium for the first time, or to a group of patients who had been taking lithium for more than one year. However, a small number of lithium-treated patients may have evidence of renal damage, identifiable by NAG assay.
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372
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Raghunathan R, Wuest C, Faust J, Hwang S, Miller ME. Isolation of ovine lymphocytes, granulocytes, and monocytes by counterflow centrifugation elutriation. Am J Vet Res 1982; 43:1467-70. [PMID: 7103229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A simple, brief 1-step counterflow centrifugation elutriation technique is described for the recovery of highly purified populations of lymphocytes and granulocytes from adult and fetal ovine peripheral blood. Monocytes are obtained as an enriched population. Lymphocyte and granulocyte recoveries average 80%, higher than with routine gradient centrifugation procedures. In this described technique, inexpensive medium is used, and it is completed in about 90 minutes. The individual blood cellular populations, when tested appropriately, demonstrated normal functional responses.
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373
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Hwang S, Kwan KC, Albert KS. A liner mode of reversible metabolism and its application to bioavailability assessment. JOURNAL OF PHARMACOKINETICS AND BIOPHARMACEUTICS 1981; 9:693-709. [PMID: 7341755 DOI: 10.1007/bf01070901] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A theoretical basis has been established for the bioavailability assessment of drug and metabolite wherein the biotransformation of one to the other is reversible. The method is applicable to linear systems and requires knowledge of drug metabolite clearance rates as well as the rate of their interconversion. While not necessary, an unconventional definition of plasma clearance appears desirable and expeditious. Depending on the experimental situation, clearance values may change between treatments; these changes should be recognized and accommodated. Alterations in experimental design are discussed as means to minimize the need for assumptions and/or to provide data in suitable form as tests of internal consistency.
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374
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Murdock SH, Schwartz DF, Hwang S. The effects of socioeconomic characteristics and off-reservation contacts on the service awareness and usage patterns of elderly native Americans. LONG TERM CARE AND HEALTH SERVICES ADMINISTRATION QUARTERLY 1980; 4:64-76. [PMID: 10245510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
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375
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Hwang S, Tuason VB. Long-term maintenance lithium therapy and possible irreversible renal damage. J Clin Psychiatry 1980; 41:11-9. [PMID: 6985889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
This article reviews the literature regarding structural damage and functional disturbances of the kidneys due to long-term maintenance lithium therapy. The correlation between structural changes and functional disturbances of the kidneys is examined. The prognostic implications of lithium-induced nephropathy are discussed, especially in regard to the possible development of chronic renal failure. Recommendations are made to provide maximum benefits of lithium therapy and to minimize accompanying risks of renal side effects.
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376
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Abstract
Assumptions attendant to model-independent bioavailability estimation were reexamined. Particular attention was given to the situation where an intravenous reference is not available and nonrenal clearance is assumed to be constant between treatments. Under these circumstances, the previously proposed approximation was compared with other bioavailability estimators. On the basis of error analysis, a procedure was devised to yield optimal relative bioavailability estimates.
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377
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378
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Hwang S, Owada E, Suhardja L, Ho NF, Flynn GL, Higuchi WI. Systems approach to vaginal delivery of drugs IV: methodology for determination of membrane surface pH. J Pharm Sci 1977; 66:778-81. [PMID: 17716 DOI: 10.1002/jps.2600660608] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A physical model including a diffusional layer in series with the membrane was developed for studying the possible differences between the pH at the membrane surface and that in the bulk solution. Both the membrane-secreted substances (acids and bases) and buffer constituents in the bulk solutions are assumed to contribute to the surface pH. Equations derived for this situation, together with experimental determinations of the acidic dissociation constant of the secreted material, the total secretion flux, the flux of total secreted acidic species, and the diffusion layer thickness, allow estimates to be made of the pH at the membrane surface. With the rabbit vagina, the membrane surface pH was close to that of the bulk solution in most cases. These results were supported by the fact that the absorption of 1-alkanoic acids in pH 2.2 phosphate buffers was relatively constant over the buffer concentration range of 0.003-0.1 M phosphate.
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379
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Hwang S, Owada E, Suhardja L, Ho NF, Flynn GL, Higuchi WI. Systems approach to vaginal delivery of drugs V: in situ vaginal absorption of 1-alkanoic acids. J Pharm Sci 1977; 66:781-4. [PMID: 17717 DOI: 10.1002/jps.2600660609] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The vaginal absorption of a homologous series of ionizable compounds, the 1-alkanoic acids, was studied using a perfusion method with a rib-cage cell surgically implanted in the rabbit vagina. The absorption rates of these compounds followed first-order kinetics. The physical model previously used for the 1-alkanols, but accounting for the pKa and pH effects in the present case was employed in the analysis of the carboxylic acid data. The aqueous diffusion layer thickness was 0.031 cm. The permeability coefficient for the lipoidal pathway increased 3.5-fold per methylene group. Both values agree reasonably well with those obtained in the alcohol study.
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380
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Hwang S, Owada E, Yotsuyanagi T, Suhardja L, Ho NF, Flynn GL, Higuchi WI. Systems approach to vaginal delivery of drugs II: In situ vaginal absorption of unbranched aliphatic alcohols. J Pharm Sci 1976; 65:1574-8. [PMID: 993988 DOI: 10.1002/jps.2600651105] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The absorption of unbranched aliphatic alcohols in the rabbit vagina was studied using a perfusion method, and the absorption rates were found to be first order with respect to the drug concentration in the vagina from methanol to octanol. A physical model involving an aqueous diffusion layer in series with a membrane consisting of aqueous pores and lipoidal pathways was used for analyzing the data. The physically based parameters in the model were determined. An effective diffusion layer thickness ("unstirred layer") of around 0.035 cm was found. The increase in the permeability coefficient for the lipoidal pathway per methylene group was around 2.5 for this homologous series.
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381
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Ho NF, Suhardja L, Hwang S, Owada E, Molokhia A, Flynn GL, Higuchi WI, Park JY. Systems approach to vaginal delivery of drugs III: Simulation studies interfacing steroid release from silicone matrix and vaginal absorption in rabbits. J Pharm Sci 1976; 65:1578-85. [PMID: 1033272 DOI: 10.1002/jps.2600651106] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A composite physical model involving the simultaneous receding boundary release of drug from a drug suspension-silicone polymer matrix system, diffusion across the aqueous layer, and passive transport across the vaginal membrane consisting of parallel lipoidal and aqueous pore pathways is described. Simulation studies with progesterone and hydrocortisone illustrate matrix release-limiting, membrane absorption, and aqueous diffusion layer-limiting cases when the cylindrical silicone delivery device is interfaced with the vaginal membrane of the rabbit.
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382
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Lozier RH, Niederberger W, Bogomolni RA, Hwang S, Stoeckenius W. Kinetics and stoichiometry of light-induced proton release and uptake from purple membrane fragments, Halobacterium halobium cell envelopes, and phospholipid vesicles containing oriented purple membrane. BIOCHIMICA ET BIOPHYSICA ACTA 1976; 440:545-56. [PMID: 963044 DOI: 10.1016/0005-2728(76)90041-4] [Citation(s) in RCA: 188] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
We have used flash spectroscopy and pH indicator dyes to measure the kinetics and stoichiometry of light-induced proton release and uptake by purple membrane in aqueous suspension, in cell envelope vesicles and in lipid vesicles. The preferential orientation of bacteriorhodopsin in opposite directions in the envelope and lipid vesicles allows us to show that uptake of protons occurs on the cytoplasmic side of the purple membrane and release on the exterior side. In suspensions of isolated purple membrane, approximately one proton per cycling bacteriorhodopsin molecule appears transiently in the aqueous phase with a half-rise time of 0.8 ms and a half-decay time of 5.4 ms at 21degreesC. In cell envelope preparations which consist of vesicles with a preferential orientation of purple membrane, as in whole cells, and which pump protons out, the acidification of the medium has a half-rise time of less than 1.0 ms, which partially relaxes in approx. 10 ms and fully relaxes after many seconds. Phospholipid vesicles, which contain bacteriorhodopsin preferentially oriented in the opposite direction and pump protons in, show an alkalinization of the medium with a time constant of approximately 10 ms, preceded by a much smaller and faster acidification. The alkalinization relaxes over many seconds. The initial fast acidification in the lipid vesicles and the fast relaxation in the envelope vesicles are accounted for by the misoriented fractions of bacteriorhodopsin. The time constants of the main effects, acidification in the envelopes and alkalinization in the lipid vesicles correlate with the time constants for the release and uptake of protons in the isolated purple membrane, and therefore show that these must occur on the outer and inner surface respectively. The slow relaxation processes in the time range of several seconds must be attributed to the passive back diffusion of protons through the vesicle membrane.
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383
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Sayre RM, Hwang S. Freezing and Storing Ditylenchus dipsaci in Liquid Nitrogen. J Nematol 1975; 7:199-202. [PMID: 19308154 PMCID: PMC2620096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
Abstract
After 18 months of storage at -150 C, some larvae of Ditylenchus dipsaci, which had been treated in a 7.5% solution of dimethyl sulphoxide and cooled to -25 C before storage, were still viable on thawing. Some survivors penetrated and developed normally in stems of alfalfa seedlings. Tests showed that active larvae could be frozen directly, thus eliminating the need to use the quiescent stage of this nematode previously thought necessary for successful storage at cryogenic temperatures. The method described is suitable for long-term storage of D. dipsaci and may, with slight modifications, be used to preserve other plant-parasitic nematodes.
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384
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Yotsuyanagi T, Molokhia A, Hwang S, Ho NF, Flynn GL, Higuchi WI. Systems approach to vaginal delivery of drugs I: development of in situ vaginal drug absorption procedure. J Pharm Sci 1975; 64:71-6. [PMID: 237108 DOI: 10.1002/jps.2600640113] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In the framework of the development of drug delivery systems for locally administered contraceptive drugs, a reliable method that can afford quantitative evaluation of drug absorption behavior was explored using the rabit doe. A system was constructed based upon perfusing the drug solution in the vaginal tract. For this purpose, a "rib-cage" type cell was constructed and surgically implanted in the rabbit prior to an experiment. The primary purpose of the present paper is to evaluate the method, including the surgical operation and the perfusion system. The absorption experiments were carried out using n-butanol-1minus 14C as the model solute to survey the reproducibility of the absorption behavior. Experiments were conducted with a number of rabbits on several successive days to determine the day-to-day and animal-to-animal variations. The drug disappearance in the reservoir followed first-order kinetics from which the apparent permeability coefficient was calculated. The results indicated that a set of experiments may be carried out on a single animal and that the method generally affords rather high precision.
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