Biomedical subjects

C L Chang

Publications and source records attributed to C L Chang.

At least 145 records · Page 8Linked to original sources

PubMed1991

Effects of high-dose fentanyl combined with diazepam on patients after coronary artery bypass graft surgery.

High-dose fentanyl has become a popular anesthetic agent for cardiac anesthesia because of its cardiac stability. Little attention has yet been paid to the relationship between the dose and problems during the early postoperative period. This study was designed to investigate whether higher doses of fentanyl combined with diazepam would influence the early-stage of postoperative conditions. Sixteen patients scheduled for elective coronary artery bypass graft (CABG) surgery were studied. All of them had adequate cardiac performance, and were randomly divided into two groups, 9 in Group I and 7 in Group II. Group I received fentanyl (less than 100 micrograms/kg) combined with diazepam (less than 0.2 mg/kg). In Group II the doses of both drugs were greater than that used in Group I. The cardiovascular changes, the maximal infusion rates of dopamine, nitroglycerin (NTG), and sodium nitroprusside (Nipride) were observed. Meanwhile, the awakening time from anesthesia, the time of extubation, and the duration of stay in the intensive care unit (ICU) were also recorded. The results showed that there were no significant differences between both groups regarding the factors studied except the maximal infusion rate of Nipride and the awakening time of post-anesthesia. We suggest that higher doses of fentanyl combined with diazepam can reduce the dosage of vasodilator but do not prolong the time of extubation and stay in ICU.

Blood Pressure↗

PubMed1991

Hypercarbia is not the determinant factor of systemic arterial hypertension during carboperitoneum in laparoscopy.

Laparoscopy performed with carboperitoneum in 30 women of infertility was studied to evaluate the changes of systemic blood pressure and end-tidal carbon dioxide (CO2) and their relationship. The patients were randomly divided into 2 groups. In group I (n = 15), the patient's respiration was set to maintain a nearly constant end-tidal CO2 by adjusting the minute ventilation. In group II (n = 15), the minute ventilation was kept constant to monitor the changes of end-tidal CO2. Perioperative measurements included end-tidal CO2, systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) which were recorded the moment just before intra-abdominal CO2 administration and every 2 min thereafter for at least 10 min. The data showed that in both groups there were time-related changes of blood pressure with a maximum increase about 20-30% of baseline level found at 6 min later after the beginning of intra-peritoneal CO2 insufflation, and no significant change of HR was noted. The intergroup comparisons of SBP, DBP and HR were not statistically significant. With regard to end-tidal CO2 change in group II, it also appeared in a time-related fashion. A maximum increase was found 6 min later after the intra-abdominal CO2 administration. Our results disclosed that carboperitoneum during laparoscopy might consistently induce systemic arterial hypertension, and hypercarbia might not be the major determinant factor of hypertension.

Adult↗

PubMed1991

Renal oncocytoma: report of two cases and review of literature.

Renal oncocytoma was previously reported as a benign tumor arising from proximal tubular epithelial cells, but malignant potential with local invasion and distant metastasis has been emphasized in recent literature. It is difficult to differentiate it from renal cell carcinoma, but four typical angiographical signs may give suggestive evidence of the tumor. Radical nephrectomy with lymphadenectomy may be the choice of treatment, except in solitary kidney, bilateral tumors, or contralateral renal cell carcinoma. We report two female patients who were found incidentally to have renal tumors during a survey of right upper quadrant pain. Typical angiographic signs were found incidentally to have renal tumors during a survey of right upper quadrant pain. Typical angiographic signs were found in one patient, and atypical signs in the other. Three and eight years after radical nephrectomy with para-aortic lymphadenectomy, there has been no evidence of local recurrence or distant metastasis.

Adenoma↗

PubMed1991

Primary retroperitoneal sarcomas--a report of 16 cases.

From November 1982 to August 1990, 16 patients with primary retroperitoneal sarcoma were treated in our hospital. The most frequent types of tumor were liposarcoma (6), malignant fibrous histiocytoma (3). The commonest clinical findings were palpable abdominal mass (14/16). In management of these patients; nine patients underwent complete resection of the tumor; three patients underwent partial resection of the tumor and four patients underwent biopsy only. The histology of tumor appeared to have prognostic significance. Patients suffering from liposarcoma (3/5) and malignant fibrous histiocytoma (1/2) survived the longest. With a mean follow up of 25.0 months, the three year overall survival rate of complete resection group was 50 per cent. No patients with partial resection and biopsy only group survive three years and the total three-years overall survival rate was 29%. The mean survival for patients after adjuvant chemotherapy and/or radiotherapy was similar to that after a radical operation alone. The prognosis of primary retroperitoneal sarcoma is grave and complete resection of the tumor as initial treatment seems to provide the only chance of cure for these patients.

Adolescent↗

PubMed1990

Two-step isolation of bacterial ribonucleic acid without using a chaotropic agent or cesium chloride centrifugation.

A simple RNA isolation method was developed to purify bacterial RNAs from a large number of samples simultaneously in an hour. The method is based on boiling the cells in the presence of Triton X-100 and lysozyme, and then preferential RNA precipitation with ammonium acetate. There is no CsCl centrifugation required. For the nitrogen-fixing bacterium Klebsiella pneumoniae, the depression condition can be maintained during the cell-harvesting process. The intact isolated RNAs appeared to be free of protein, with a yield of 100 micrograms RNA from a 4-ml cell culture of 100 Klett units (10(9) cells/ml). Any DNA present was in a form that did not react with a nifH probe following Northern blotting to nitrocellulose (i.e., was not single-stranded).

Acetates↗

PubMed1990

Metabolic evaluation of urolithiasis.

After detailed instruction, 62 patients with urolithiasis treated at Taichung Veterans General Hospital entered this program, which ran from September 1987 to November 1988. Based on Pak's classification, there were 13 cases (21.0%) of absorptive hypercalciuria, type I (AH-I); 12 cases (19.4%) of absorptive hypercalciuria, type II (AH-II); 16 cases (25.8%) of renal hypercalciuria (RH); 3 cases (4.8%) of hyperuricosuric calcium urolithiasis (HUCU); 11 cases (17.7%) of hypocitraturia (Hypocit); 3 cases (4.8%) of hyperoxluria (HO); one case (1.6%) of primary hyperparathyroidism (PHPT) and one case (1.6%) of infectious lithiasis. Two cases (3.2%) with no metabolic abnormalities were found. Hypocitraturia, HUCU, and HO can be the primary abnormal findings, but more often coexist with various forms of hypercalciuria as a second factor. If the coexistence is considered, hypocitraturia (33 cases, 53.2%) and HUCU (24 cases, 38.7%) were the most prevalent categories. Meanwhile, 24 cases (38.7%) had only one physiological derangement, 25 cases (40.3%) had two derangements, and 13 cases (21.0%) had three. This study indicates that metabolic evaluation can elucidate the physiological derangements of urolithiasis, so that further medical treatment can be administered selectively.

Adult↗

PubMed1990

[Renal effect of isoflurane].

Isoflurane is a pentafluorinated methyl ether and can be metabolized to inorganic fluoride in man. Nephrotoxicity may be developed after it's administration. The present study was carried out to evaluate the effects of isoflurane on renal hemodynamic and excretory function in 15 patients. The systolic, diastolic and mean arterial pressure and renal function were measured before, during and after induction of anesthesia by isoflurane. Renal plasma flow (RPF) and glomerular filtration rate (GFR) were estimated by the clearances of paraaminohippuric acid and inulin, respectively. The results showed that a slight reduction in systolic pressure but no significant change in diastolic and mean blood pressures were found during anesthesia. There were 30% and 50% reductions in RPF and GFR, respectively. The filtration fraction increased significantly. Simultaneous decreases in urine flow, absolute and fractional excretions of sodium, absolute excretion of potassium, osmolar clearance and free water reabsorption rate were observed during isoflurane anesthesia. However, the blood pressure and renal function returned to pre-anesthesia levels 30-60 minutes after termination of anesthesia. These data suggest that isoflurane induces renal depressive effect which is reversible and temporary.

Adult↗

PubMed1990

The rate of end-tidal CO2 elevation after intraabdominal CO2 insufflation in laparoscopy.

Twenty-two female adults were under study by monitoring the end-tidal CO2 during laparoscopy in order to define the rate of CO2 elevation. Experimental results showed that under the intraabdominal pressure of 14.5 cm H2O (ranging from 12 to 18 cm H2O), the elevated CO2 level varied from 3 mmHg to 19 mmHg with a mean value of 8.3 +/- 3.7 mmHg (P less than 0.001). It took 10.5 +/- 1.9 min to reach peak level.

Abdomen↗

PubMed1990

Effects of PGE1 on platelet deformability.

Prostaglandin E1 (PGE1) is frequently used as a stabilizing agent while isolating platelets. The platelet-stabilizing effect of PGE1 is mediate through the PGE1 receptor and the consequent increase of intracellular cAMP. The discoid shape of platelet is thus maintained. Recently, we have studied the effect of PGE1 on platelet deformability with micropipette aspiration technics, using pipettes with radii (Rp) of 0.26-0.36 micron. Platelets, obtained from platelet-rich plasma, and suspended in Hank's buffer containing BSA, glucose, adenosine and theophylline, were subjected for micropipette aspiration test within 2 hr after sampling. In general, PGE1 treated platelets (greater than 75%) remained as non-activated form as revealed under video microscopy and maintained their discoid shape for as long as 6 hr. The time course of the extension length (Dp, in micron) of the platelets in response to aspiration with a negative pressure of 5 cm H2O (tension = 0.15 dynes/cm) was analyzed by using a digital image analyzer system (IRIS 3120 with IP-512, with a resolution of 0.076 microns). A computer program based on the algorithm of real-time reading of image intensity was developed to facilitate real-time data acquisition. The data of Dp/Rp vs time (sec) were fitted by using a second-order equation. The deformability of PGE1 (0.1 microM) treated platelet was decreased significantly as compared with control. These results indicate that the platelet stabilization by PGE1 is accompanied by a decrease in platelet deformability.

Alprostadil↗

PubMed1990

Study of plasma neuropeptide Y (NPY) and catecholamines levels during spinal anesthesia.

Plasma levels of neuropeptide Y (NPY) and catecholamines were investigated during spinal anesthesia. Ten ASA physical status I-II patients were studied after obtaining institutional approval and informed contents. All patients were free from endocrine and metabolic disease underwent elective low risk operation. No premedication was given before operation. Spinal anesthesia was performed on lateral position from L3-4 interspace with 15 mg tetracaine without added epinephrine. The analgesic level was about at T6 dermatone. Blood samples were obtained from radial artery catheter, 15 minutes before spinal anesthesia and 5', 15', 30', 60', 120', during operative period and 30' after operation in postanesthesia recovery room. The results showed that there were significant elevation in plasma level of NPY during spinal anesthesia compared with the level before anesthesia. However, no statistically significant changes of plasma catecholamines were found.

Adolescent↗

PubMed1990

Cardiovascular responses to tracheal intubation after thiopentone or propofol.

The hemodynamic responses to laryngoscopy and intubation were compared in forth patients of ASA class I-II undergoing various surgical procedures without premedication were randomly divided into two groups and given propofol (2.5 mg/kg) or thiopentone (5 mg/kg) for induction, and succinylcholine (1.5 mg/kg) for facilitating laryngoscopy and intubation. Each group consisted 20 patients. Baseline data has no significant difference between the two groups. After induction systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP) heart rate (HR), cardiac output (CO), cardiac index (CI) were all lower in the propofol group than thiopentone group. It indicate that propofol (2.5 mg/kg) has more cardiovascular depressive effects than thiopentone (5 mg/kg). Local injection pain was complained by every patient.

Adult↗

PubMed1990

Study of plasma neuropeptide Y (NPY) and catecholamines levels during isoflurane anesthesia.

Twelve ASA physical status I-II patients were studied after obtaining institutional approval and informed contents. All patients were free from endocrine and metabolic disease undergoing elective low risk operation. Pethidine 1 mg/kg i.m. and benzodiazepine 0.01 mg/kg p.o. were given as premedication one hour before anesthesia. Anesthesia was induced with thiopental 4 mg/kg and succinylcholine 1.5 mg/kg for tracheal intubation. Anesthesia was maintained with 2% isoflurane and 50% N2O in oxygen. Ventilation was controlled and adjusted to maintain an end-tidal CO2 concentration of 25-35 torr. Atracurium 0.4 mg/kg was given as muscle relaxant. Blood samples were obtained from radial arterial catheter, 15 minutes before induction of anesthesia and 5 min after anesthesia, 15 min, 30 min, 60 min during operation and 30 min after operation in postanesthesia recovery room. The results showed that there were no statistically significant changes in plasma levels of NPY and catecholamines during operation underwent isoflurane anesthetic technique. This result indicates that isoflurane anesthesia can block the plasma NPY as well as catecholamines during surgical stress.

Adult↗

PubMed1990

[The distance from the skin to the epidural space in general population].

Epidural block is a common regional anesthetic technique in surgical procedures. The depth of the epidural space beneath the skin surface varies at different levels of the spinal column in the same patient. It also varies from patient to patient at the same vertebral level. We studied the distance from the skin to the different lumbar epidural space in general population to determine whether there is any systematic relationship between patient age, height, weight and the distance from the skin to the epidural space. Data were gathered from 159 patients (excluded all obstetric cases) having epidural anesthesia for surgical procedures. All blocks were performed using a midline approach with lateral and knee-chest position. They divided into 3 group according to different lumbar area: (1) Group A: L1-2 interspace, 33 cases; (2) Group B:L3-4 interspace, 54 cases; (3) Group C: L4-5 interspace, 72 cases. Data were analyzed by single linear regression and one-way ANOVA with p less than 0.05 considered statistically significant. The results revealed that: In Group A, there were relationship between patient age [r2 = 0.137, p less than 0.05], weight [r2 = 0.35, P less than 0.0003] and weight-height ratio.[r2 = 0.36, P less than 0.0002] with the distance from the skin to the epidural space (depth); but no relationship between body height.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1990

[Value of chest CT scans for predicting surgical resectability of lung cancer].

In order to find out the correlation between chest CT scanning and operative finding, a series of 102 patients with lung cancer were analysed. Lobectomy was performed in 88 cases and exploration in 14 cases because the lesion infiltrated the ipsilateral mediastinal lymph nodes. The operations confirmed that there were 28 cases with mediastinal pleural invasion of carcinoma, 20 cases with spread to the chest wall or pleura, 43 cases with enlarged mediastinal lymph nodes (greater than or equal to 1.0cm) and 37 cases with microscopic metastasis. The preoperative chest CT of these patients showed that the carcinoma involved mediastinum and pleura in 25 and 16 cases respectively, and the enlarged mediastinal lymph nodes were present in 37 cases besides 6 cases of pseudonegative shadow. The sensitivity of metastatic mediastinal lymph nodes diagnosed by chest CT was 86%, specificity 89.3%, and accuracy 88%. We believe that the chest CT scanning is valuable in diagnosis of lung cancer and prediction of surgical resectability of the lesion.

Adenocarcinoma↗

PubMed1990

[ARDS complicated severe chest trauma: a review of 12 cases].

A total of 140 patients of thoracic trauma were admitted and treated in our hospital from 1970 to 1988. Thirty cases conformed the diagnosis of severe chest injury. Among them 12 patients (40%) were complicated by the adult respiratory distress syndrome (ARDS) with two deaths (16.7%). The diagnosis and treatment of ARDS following severe chest trauma was often-times delayed by the overlapping clinical manifestations of severe chest injury. Patient's condition usually deteriorates rapidly. Authors suggest early tracheotomy and appropriate mechanical ventilation as one of the major measures to decrease mortality.

Adult↗

PubMed1989

Hormone and substrate regulation of glycogen accumulation in primary cultures of rat hepatocytes.

Hormonal and substrate regulation of hepatic glycogen accumulation was evaluated in primary cultures of hepatocytes prepared from 1-day-fasted rats. Hepatocytes were cultured in media containing 5 mM-glucose and 10 mM-lactate and then exposed to 100 nM-dexamethasone for 4 h before an increase in glucose concentration and the addition of insulin. When this protocol was used to mimic the post-prandial state in vivo, net glycogen accumulation (over 2 h) and insulin (10 nM) effects were linear at physiological (5-10 mM) and supraphysiological (20-30 mM) glucose concentrations. To define the role of substrates in glycogen accumulation, hepatocytes were incubated in a buffered salt solution containing 10 mM-glucose and either 10 mM-lactate or 5 mM-glutamine, or both. In the absence of hormones, net glycogen accumulation was increased by 59%, 83%, and 127% by the addition of lactate, glutamine, and lactate plus glutamine respectively, compared with incubations with glucose alone, and 6-fold in the presence of substrates, insulin and dexamethasone. Labelling with [3-3H]glucose and [U-14C]glucose showed that in the absence of hormones approx. 50% of glycogen formation came from glucose via the direct pathway and the remainder from glucose via the indirect pathway or from non-glucose precursors, or both. Insulin-dependent enhancement of glycogen formation is through stimulation of both the direct and indirect pathways, and dexamethasone-dependent stimulation occurs through stimulation of both these pathways of glycogen formation from glucose as well as from non-glucose precursors. Lactate serves as a gluconeogenic C3 precursor for the observed enhanced glycogen formation, whereas glutamine-dependent enhancement of glycogen accumulation occurs primarily through a stimulation of the direct and indirect pathways of glycogen formation from glucose.

Animals↗

PubMed1989

Substitution of histidine for arginine-101 of dinitrogenase reductase disrupts electron transfer to dinitrogenase.

Dinitrogenase reductase from Klebsiella pneumoniae strain UN1041 has a histidine residue substituted for arginine at position 101. The mutant dinitrogenase reductase was purified and characterized in order to determine the importance of arginine-101 in the interaction between dinitrogenase and dinitrogenase reductase during electron transfer. Purified dinitrogenase reductase from UN1041 is a dimer of 67 kDa, contains a functional 4Fe-4S cluster, undergoes a MgATP-dependent conformational change, and is competent for ATP hydrolysis uncoupled from substrate reduction in the presence of dinitrogenase. However, the mutant protein is unable to support the reduction of protons or acetylene by dinitrogenase. A 100-fold molar excess of Kp2 from UN1041 does not inhibit electron transfer from wild-type dinitrogenase reductase to dinitrogenase. It is concluded that the interaction of dinitrogenase reductase with dinitrogenase during reductant-independent ATP hydrolysis is different than the interaction between the two proteins during electron transfer; the substitution of histidine for arginine at position 101 disrupts only the latter interaction. The same conclusions are reached using wild-type dinitrogenase reductase which has been ADP-ribosylated at arginine-101.

Adenosine Triphosphate↗

PubMed1989

Subunit associations in the mammalian pyruvate dehydrogenase complex. Structure and role of protein X and the pyruvate dehydrogenase component binding domain of the dihydrolipoyl transacetylase component.

We have further distinguished the structures and roles of the two lipoyl-bearing components of the pyruvate dehydrogenase complex, the dihydrolipoyl transacetylase (E2) component and the component designated as protein X. The amino acid sequences of the NH2-terminal regions of the lipoyl-bearing domain of the E2 component and protein X are different but related. The dihydrolipoyl dehydrogenase (E3) component but not the pyruvate dehydrogenase (E1) component protected protein X against proteolytic degradation by trypsin and protease Arg C. Protein X-specific polyclonal antibodies inhibit reconstitution of the overall reaction catalyzed by the complex (E2-X subcomplex recombined with the E1 and E3 components). The rate of development of this inhibition was reduced by pretreatment of E2-X subcomplex with the E3 component. These data strongly suggest the E3 component associates with protein X. The E1 component (an alpha 2 beta 2 tetramer), but not the E3 component, reduced trypsin cleavage of E2 subunits at 4 degrees C and altered the patterns of cleavage at 22 degrees C. At 22 degrees C a large (Mr congruent to 49,000) outer domain (E2LB) of the E2 component was produced. E2LB had the same NH2-terminal amino acid sequence as the smaller (Mr congruent to 38,000) lipoyl-bearing domain (E2L). E2LB, in contrast to E2L, interacted with both the E1 component and the beta subunit of the E1 component. Thus the E1 component is bound through an E1-binding domain that is located in E2 subunits between the inner domain and the outer, lipoyl-bearing domain.

Acetyltransferases↗