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Biomedical subjects

C F Chang

Publications and source records attributed to C F Chang.

At least 145 records · Page 8Linked to original sources
PubMed1991

Demonstration of the phosphorylation of dihydropyridine-sensitive calcium channels in chick skeletal muscle and the resultant activation of the channels after reconstitution.

We have examined the effects of cAMP elevating agents on the phosphorylation of dihydropyridine-sensitive Ca2+ channels in intact newborn chick skeletal muscle. In situ treatment with the beta-adrenergic receptor agonist isoproterenol resulted in the phosphorylation of the 170-kDa alpha 1 subunit in the intact cells, as evidenced by a marked decrease in the ability of the alpha 1 peptide to serve as a substrate in in vitro back phosphorylation reactions with [gamma-32P]ATP and the purified catalytic subunit of cAMP-dependent protein kinase. The phosphorylation of the 52-kDa beta subunit was not affected. The effects of isoproterenol were time- and concentration-dependent and were mimicked by other cAMP elevating agents but not by the Ca2+ ionophore A23187 or a protein kinase C activator. To test for functional effects of the observed phosphorylation, purified channels were reconstituted into liposomes containing entrapped fluo-3, and depolarization-sensitive and dihydropyridine-sensitive Ca2+ influx was measured. Channels from isoproterenol-treated muscle exhibited an increased rate and extent of Ca2+ influx compared to control preparations. The effects of isoproterenol pretreatment could be mimicked by phosphorylating the channels with cAMP-dependent protein kinase in vitro. These results demonstrate that the alpha 1 subunit of the dihydropyridine-sensitive Ca2(+)-channels is the primary target of cAMP-dependent phosphorylation in intact muscle and that the phosphorylation of this protein leads to activation of channel activity.

Animals↗
PubMed1991

Hamartoma of spleen: a case report.

Hamartoma of the spleen is a rare benign tumor. Only about 105 cases in English-writing literature were reported after first description by Rokitansky in 1861. We reported one case of asymptomatic splenic hamartoma in Taiwan which was found incidentally by ultrasonographic examination. Ultrasonography of abdomen revealed a slightly hypoechoic and nearly isoechoic tumor mass in the spleen. Computed tomography of the abdomen revealed a well-defined, low-attenuation mass in the spleen, which became isodense after contrast injection. Celiac arteriography and superselective splenic arteriography revealed a hypervascular mass with fine tumor vessels and tumor stains in the spleen. Splenectomy was performed and the microscopic examinations revealed typical red-pulp type hamartoma of the spleen.

Adult↗
PubMed1991

The single-hospital county: is its hospital at risk?

This article focuses on a hospital group that has not received adequate attention in the literature: the sole provider of short-term, acute hospital care located in a county. In Tennessee, SPHs (single provider hospitals) are fewer in number but are present in more counties than multiprovider hospitals (MPHs). They are smaller in size, less labor and capital intensive, more likely to be a government hospital, and more likely to be in a rural area with low income and limited health care resources. SPHs operate with lower costs, charge patients less, and have lower revenue write-offs than MPHs. As a result, their cash flow is sufficient to fund their depreciation and they consistently earn modest returns. Between 1982 and 1988, a total of 16 hospitals failed in Tennessee but only 3 were SPHs. While SPHs have not been profitable enough to make them ideal candidates for takeover by major hospital systems, they are not a population that is unduly at risk.

Bed Occupancy↗
PubMed1991

A proposal to redistribute the cost of hospital charity care.

Policy analysts debate whether providers of hospital services should share the responsibility of financing care for those who cannot pay for it. Many nonprofit and public hospitals, meanwhile, find it necessary to fund some of the services they deliver. A proposal to redistribute the costs of charity care more equitably is offered, taking into account the benefits an institution receives and its ability to pay. Hospitals would be required to quantify the charity care they provide and to make this information publicly available; in reviewing the information, legislatures are encouraged to set priorities on how much unmet need each state and each hospital should finance.

Charities↗
PubMed1990

A combined non-denaturing and denaturing gel electrophoretic analysis of the subunit composition of a membrane protein: the skeletal muscle L-type calcium channel.

Using a non-denaturing digitonin-based polyacrylamide gradient gel electrophoretic system we identified the dihydropyridine-sensitive Ca2+ channel from skeletal muscle as a high molecular weight protein of greater than 700 kDa. When this protein was excised from the native gels and re-electrophoresed into SDS gels, it dissociated into the alpha 1, alpha 2, beta, gamma and delta peptides previously suggested to be putative subunits of these Ca2+ channels. The stoichiometry of the alpha 1:alpha 2:beta:gamma peptides was (-)1:1:1:1. The presence of the alpha 1 and alpha 2 peptides in the high molecular weight native complex was directly demonstrated with anti-alpha 1 and anti-alpha 2 antibodies. The apparent specific association of the peptides was demonstrated by the finding that the previously separated alpha 1 and alpha 2 peptides did not co-migrate with the native complex in non-denaturing gels. The results of this previously untried analysis support the concept that the skeletal muscle Ca2+ channels are multisubunit proteins. The combined non-denaturing and denaturing gel analyses may be of general utility for the analysis of other membrane proteins.

Animals↗
PubMed1990

The distribution of indigent care among hospitals: in search of the fair share.

Although the magnitude and consequences of indigent care are well known, the terms and methods used to define and assess such care are less clear--yet these measures are vital to any solution of the problem. Using data from 151 Tennessee hospitals, two economists analyze the problems, concepts, views, and trends of indigent care and its distribution among hospitals.

Charities↗
PubMed1990

Who bears the burden of uncompensated hospital care?

This paper considers the question of who bears the burden of uncompensated hospital care. The thesis is that the hospital that provides the services received by indigent patients may not be the one that eventually bears the financial burden. The various sources of funds available for the payment of indigent care are identified and the incidence of financial burden discussed. The paper ends by addressing several considerations that should be taken into account in evaluating how fairly the indigent care burden is distributed.

Cost Allocation↗
PubMed1990

The effect of volume of epidural morphine on postoperative analgesia in patients undergoing cesarean section.

Ninety paturients undergoing elective cesarean section were included in this randomized study to compare the influence of the injected volume of epidural morphine (EM) on postoperative analgesia. Three similar groups of patients (n = 30 each) received 2 mg EM in 2 ml, 10 ml, and 20 ml saline respectively one hour after the last dose of 2% lidocaine. Pain scores (0-10) at rest (including uterine contraction pain) at the 2nd, 4th, 8th, 12th, 18th, and 24th h were compared among the three groups. There were no statistically significant differences of pain score among the three groups although lower pain score was present in the 20 ml group since the 8th h and thereafter. Regarding the number of patients who requested additional meperidine for pain relief 3 in 2 ml group, 2 in 10 ml group and 1 in 20 ml group respectively. The result may suggest that the influence of the injected volume of EM on postcesarean analgesia is not obvious.

Adult↗
PubMed1990

Diclofenac sodium and low dose epidural morphine for postcesarean analgesia.

A randomized double-blind study of parturients after Cesarean section was undertaken to assess the efficacy of the combination of single dose intramuscular diclofenac sodium and low dose epidural morphine (EM) for postoperative analgesia. 50 parturients under epidural anesthesia were divided into 2 treatment groups: group A received 2 mg EM 30 min after the last dose of lidocaine and 3 ml normal saline i.m. at recovery room; group B received the same EM and 75 mg diclofenac i.m. postoperatively. Pain scores were compared at the 2nd, 4th, 8th, 12th, 18th, and 24th h. Results showed that group B was superior to group A in analgesic quality from the 8th h and thereafter (P less than 0.05) and 100% patients in group B were in the excellent to good analgesia categories at the 8th and 12th h record compared to 92% and 72% patients in group A respectively. Side effects were similar in both groups. The combination of NSAIDs with low dose EM could improve the analgesic quality after Cesarean section.

Adult↗
PubMed1989

Luteinizing hormone concentrations in serum of postpartum beef cows injected with microencapsulated luteinizing hormone-releasing hormone analog.

Twenty-five cows were divided equally into five groups to determine whether [D-Trp6]-luteinizing hormone releasing hormone (LHRH-A) microencapsulated in poly (DL-lactide co-glycolide) would increase basal serum concentrations of LH during the postpartum period. On d 5 postpartum, cows were injected i.m. with 2 ml of vehicle alone (Group 1) or vehicle containing microcapsules calculated to release .4, 1.6, 6.4 or 25.6 micrograms LHRH-A per day for approximately 30 d (Groups 2, 3, 4 and 5, respectively). Cows were bled every 15 min for 4 h immediately before and after injection and every 15 min for 4 h at weekly intervals for the next 4 wk to evaluate serum profiles of LH. Estrus was determined by twice daily observations and confirmed by serum progesterone. More cows in Groups 2, 3, 4 and 5 exhibited pulsatile patterns of LH after LHRH-A injection than in Group 1 (P less than .06). More pulses of LH were observed after LHRH-A injection in Groups 4 and 5 than in Group 1 (P less than .01). Mean concentrations of LH within treatment groups did not change during the initial injection, except in Group 5. All cows in Group 5 had a surge of LH immediately after injection. The induced surge of LH in two cows in Group 5 cows resulted in progesterone profiles similar to those during a normal luteal phase. Days to first postpartum estrus were not different among the five treatment groups. Microencapsulated LHRH-A given at a dose estimated to release 25 micrograms LHRH-A/d was effective in elevating LH concentrations following injection. However, effectiveness of this hormonal treatment in shortening postpartum anestrus was not substantiated.

Anestrus↗
PubMed1989

Vaccines against endogenous hormones: a possible future tool in animal production.

Vaccines have been widely used by the livestock industry to control and prevent disease. New technologies now permit development of vaccines against hormones that control reproduction, growth, and lactation in domestic farm animals. Results of research projects studying passive and active immunization against such hormones as estrogen, testosterone, LH, FSH, and somatotropin have demonstrated that reproductive efficiencies and growth can be altered through vaccination. Although immunizations against most of the hormones studied have proven effective in most cases, there remain problems related to longevity, consistency, and efficiency of response both within and between animals. When these areas have been clearly defined for individual hormones, standardized immunization regimens can be developed that will optimize antibody production in the animal, thus providing the animal agriculture industry with a powerful and profitable production tool.

Animals↗
PubMed1988

Cryo electron microscopy of unstained, unfixed RecA-cssDNA complexes.

Complexes of RecA protein with phi X174 circular single-stranded DNA (cssDNA) with and without ATP gamma S were rapidly frozen and embedded in a thin layer of vitreous ice. The electron micrographs of these frozen-hydrated complexes clearly show visible helicity. Quantitative image analyses of these micrographs reveal the helical pitch and the axial rise between DNA bases of these complexes. Both of these structural parameters of RecA-cssDNA complexes increase significantly when ATP gamma S is present. These observations agree qualitatively but not quantitatively with those from negative stained specimens and confirm the general model that the interactions among RecA molecules and between RecA and DNA could change according to the functional states of the RecA-cssDNA complex.

DNA, Single-Stranded↗
PubMed1988

The profits of not-for-profit hospitals.

This paper explores the profits of not-for-profit (NFP) hospitals and identifies the factors that determine whether such profits are adequate. A model which relates hospital charges to surpluses is used to derive NFP surplus from gross patient charges and operating costs. This is done to identify the items contributing to surpluses and to explore the dispersion of NFP surpluses. We first discuss why the literature is relatively silent on NFP profitability. We then present the model and use Tennessee hospital data to identify how its components vary by hospital type and through time. The dispersion of surpluses among NFPs is then examined. We next propose three rate of return measures of profitability and use these to relate NFP profits to select characteristics of hospitals and their environments. Several alternative profit levels of NFP are discussed, and the factors that are relevant to the issue of determining the adequate level of profit are identified. The paper ends with a plea for better data on NFP profits.

Costs and Cost Analysis↗
PubMed1988

Active immunization of heifers against luteinizing hormone-releasing hormone, human chorionic gonadotropin and bovine luteinizing hormone.

Seventy crossbred heifers were allotted randomly to 10 treatment groups. Treatments consisted of active immunization against ovalbumin (OV) conjugates of luteinizing hormone-releasing hormone (LHRH), human chorionic gonadotropin (hCG) and bovine luteinizing hormone (bLH) with each of three adjuvants. The adjuvants were complete Freund's adjuvant (CFA), M103(6) and 6VR6. Control animals were immunized against OV alone using CFA. Bulls were placed with the heifers following immunization to allow comparison of pregnancy rates between groups. Blood samples were collected weekly for 14 wk to determine antibody concentrations. Significant levels of circulating LH or LHRH antibodies were detected in heifers immunized with each of the hormone conjugates. Complete Freund's adjuvant was the most effective for stimulating antibody response to these antigens; however, M103 was equally effective when used with bLH or hCG conjugates. None of the heifers in the bLH-OV-CFA, bLH-OV-M103 or LHRH-OV-CFA immunization groups was pregnant at slaughter, whereas 71% of the OV-CFA control heifers were pregnant. Fertility suppression may be achieved in the bovine by active immunization against any of these three hormone conjugates. However, the duration of this study (8 wk after immunization) does not allow evaluation of the duration of effectiveness of each of the treatments.

Adjuvants, Immunologic↗
PubMed1988

The determination of the profits of not-for-profit hospitals.

When challenged, hospital administrators may find themselves faced with the responsibility of defending both the existence and use of the profits of the hospital. This issue of DRG Monitor explores the reasons for the recent interest in the profits of not-for-profit (NOPRO) hospitals, analyzes the factors that determine hospital profits, and considers the different ways of using NOPRO profits and their implications in the context of the changing health care environment.

Accounts Payable and Receivable↗
PubMed1987

Active immunization of heifers against prostaglandin F2 alpha: potential as a sterilization vaccine.

Four experiments were conducted with 210 heifers in an attempt to develop a sterilization vaccine by active immunization against prostaglandin F2 alpha (PGF2 alpha) and to evaluate feedlot performance following immunization against the combination of PGF2 alpha and estrogens. The objectives were: development of a PGF2 alpha-ovalbumin conjugate that would induce antibody formation when used with complete Freund's adjuvant (CFA); comparison of CFA with other adjuvants in relation to PGF2 alpha antibody binding and maintenance of the corpus luteum; examination of growth performance in immunized heifers against both PGF2 alpha and estradiol-17 beta and evaluation of sterilization in PGF2 alpha-immunized heifers maintained with bulls. A PGF2 alpha-ovalbumin conjugate was developed that resulted in antibody production against PGF2 alpha, although antibody binding was quite low. The antibody response in heifers was higher in Exp. I and II than in Exp. III and IV (P less than .05). Complete Freund's adjuvant was the best adjuvant in inducing antibody formation compared with all other adjuvants tested (P less than .01). Corpus luteum (CL) function was maintained for 2.5 mo and ovulation was apparently blocked in Exp. I. The results of Exp. II confirmed those of Exp. I. Fewer than half of the heifers in Exp. III and IV had prolonged estrous cycles. In Exp. IV, immunized heifers became sterile for at least 4 mo when kept with bulls, although the success rate was only 37%. The low levels of antibody titers to PGF2 alpha in Exp. III and IV may be the reason for the failure to maintain CL function in some heifers.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗