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Biomedical subjects

C C Liu

Publications and source records attributed to C C Liu.

At least 145 records · Page 8Linked to original sources
PubMed1995

Pulmonary nocardiosis in a child with systemic lupus erythematosus: report of a case.

Nocardiosis is an uncommon complication in children with systemic lupus erythematosus (SLE). This is a case report of pulmonary nocardiosis in a 13 year-old girl with SLE, who presented with fever, chest pain and tachypnea. She had been treated with steroids and cytotoxic agents for five months. Nocardia asteroides was isolated from a surgical specimen culture. The pulmonary nocardiosis was treated by surgical excision in combination with trimethoprim-sulfamethoxazole. Nocardia sp should be considered as a possible agent of infection in immunocompromised patients, especially those treated with corticosteroids at the time of infection.

Adolescent↗
PubMed1995

Characterization of the antiabsence effects of SCH 50911, a GABA-B receptor antagonist, in the lethargic mouse, gamma-hydroxybutyrate, and pentylenetetrazole models.

Recent studies have shown that gamma-aminobutyric acidB (GABAB) receptor antagonists suppress absence seizures in animal models. (+)-5,5-Dimethyl-2-morpholineacetic acid, hydrochloride (SCH 50911) is a new GABAB antagonist that is structurally dissimilar to previously studied GABAB antagonists such as 3-aminopropyl-diethoxymethyl-phosphinic acid (CGP 35348), 3-aminopropyl-n-butyl-phosphinic acid (CGP 36742) or 3-aminopropyl-cyclohexylmethyl-phosphinic acid (CGP 46381). In this study we measured the antiabsence effects of SCH 50911 in three animal models: the lethargic (lh/lh) mutant mouse, which has spontaneous absence seizures; and two rat models in which absence seizures were induced by administration of either gamma-hydroxybutyrate or pentylenetetrazole. SCH 50911 abolished seizures in all three models in a dose-dependent fashion (ID100 = 8-170 mumol/kg). In each model SCH 50911 was more potent (ID50 = 2-22 mumol/kg) than the following antiabsence compounds: the GABAB antagonist CGP 35348 (ID50 = 210-890 mumol/kg); ethosuximide (ID50 < or = 142-1240 mumol/kg); trimethadione (ID50 = 520-1100 mumol/kg); and valproic acid (ID50 = 900-2360 mumol/kg). SCH 50911 was equipotent with the GABAB antagonist CGP 46381 (ID50 = 20 mumol/kg) in the lh/lh mouse model. These findings suggest that antiabsence activity may be a defining feature of GABAB receptor antagonists and provide a rationale for pursuing clinical trials of GABAB receptor antagonists in human patients with absence seizures.

Animals↗
PubMed1995

Effect of chronic respiratory acidosis on calcium metabolism in the rat.

Chronic metabolic acidosis typically results in hypercalciuria and negative calcium balance. The impact of chronic respiratory acidosis on calcium metabolism has been less well studied. To address this issue, metabolic balance and static bone histomorphometric data were obtained during a 14-day exposure of rats to 10% CO2 (blood pH 7.33, PaCO2 83 mm Hg) and were compared with pair-fed controls. All rats were fed a 0.8% calcium diet. Urinary calcium excretion (mg/period, mean +/- SEM) was increased during both week 1 and week 2 (16 +/- 3 vs 9 +/- 1 and 16 +/- 2 vs 9 +/- 1, CO2 group vs controls, respectively [p < 0.05]). Net intestinal calcium absorption (intake minus fecal excretion) was increased throughout the period of hypercapnia (week 1, 213 +/- 19 mg vs 135 +/- 15 mg; week 2, 135 +/- 16 mg vs 43 +/- 14 mg; and cumulatively, 344 +/- 27 mg vs 178 +/- 20 mg, CO2 group vs controls [p < 0.01]). As a consequence of the marked increment in intestinal calcium absorption during hypercapnia, mean net calcium balance was more positive than that of controls throughout the study (week 1, 197 +/- 18 mg vs 126 +/- 15 mg; week 2, 120 +/- 15 mg vs 34 +/- 15 mg; and cumulatively, 317 +/- 25 mg vs 159 +/- 20 mg, CO2 group vs controls, respectively [p < 0.01]). There were no significant differences in calcium intake, plasma total calcium, immunoreactive parathyroid hormone, 25-hydroxyvitamin D, or creatinine clearance between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis, Respiratory↗
PubMed1995

Assessment of dose and risk to the body following conventional and spiral computed tomography.

BACKGROUND: Computed tomography (CT) is one of the most frequently used examination procedures in diagnostic radiology and the dose given to the patients is higher than in general radiographic procedures. In this study LiF chip thermoluminescent dosimeters (TLD-100) were placed in each relative organ or tissue position, including head, chest and abdomen, in a Rando phantom. CT was performed using both conventional and spiral modes, and effective dose and effective dose equivalent were assessed for each organ or tissue scanned. METHODS: The TLD reader used in this experiment was controlled at a nitrogen flow rate of 450 ml/min, preheat time of 14 seconds, reading time of 16 seconds and annealing time of 16 seconds. This CT scanner can be used to perform both conventional and spiral tomography. Operating conditions for spiral tomography were 120 kV, 80 mA for scout film, and 120 kV, 200 mA, 1 sec/slice for each scanning. However, for conventional tomography, the operating conditions were 120 kV, 80 mA for scout film and 120 kV, 160 mA, 1.5 sec/slice for each scanning. These operating conditions are satisfactory to most clinical applications, and therefore were adopted for the present studies. RESULTS: Results showed that, in both effective dose and effective dose and effective dose equivalent, conventional tomography was higher than spiral tomography. The average effective doses for each part were measured to be 1.89 and 4.95 mSv for the head, 30.01 and 40.65 mSv for the chest, and 12.85 and 19.62 mSv for the abdomen of spiral and conventional CT, respectively. Higher carcinogenic risk was assessed in organs such as liver, lung, stomach and bone marrow, other organs had a relatively lower incidence of risk. CONCLUSIONS: The main purpose of this study was to obtain distribution values of effective dose and effective dose equivalent, and to know the probability of carcinogenic effect upon each organ or tissue after CT scanning. Results showed the average effective dose for spiral CT to be less than conventional CT, and the dose in the body surface was generally lower than the dose in the central region.

Humans↗
PubMed1995

Long-term propofol infusion and airway management in a patient with Goldenhar's syndrome.

A 2-year-old patient of Goldenhar's syndrome received an operation for corneal transplantation. Difficult endotracheal intubation from the congenital anomaly was treated with laryngeal mask airway and pediatric fiberoptic laryngoscope. Long-term propofol infusion (> 10 h) for anaesthetic maintenance in this small child was used with rapid and smooth recovery.

Anesthetics, Intravenous↗
PubMed1995

Characterization of the manganese-resistant mutants derived from Vibrio parahaemolyticus.

The virulence and some related factors of Vibrio parahaemolyticus are regulated by the level of iron. In this study, five Mn-resistant mutants were selected after N-methyl-N'-nitrosoguanidine treatment and two transfers in medium containing high levels of manganese chloride. Production of siderophores and the 77-kDa iron-regulated outer-membrane protein and the bacterial growth in these Mn-resistants were deregulated, as compared with the wild-type strain. In addition, the regulation of these phenomena was partially or completely restored by the introduction of Escherichia coli fur gene. Also, the total cellular protein profiles of the wild-type and mutants showed that production of some proteins were positively or negatively regulated by iron, and expression of some of these proteins remained unaffected in these mutants. These results suggested the presence of a complicated iron regulation system, similar to the Fur system of E. coli, in this pathogen.

Bacterial Outer Membrane Proteins↗
PubMed1994

Immune function in mice lacking the perforin gene.

Mice lacking the perforin gene were generated by using targeted gene disruption in embryonal stem cells. When infected with lymphocytic choriomeningitis virus (LCMV), perforin-less (-/-) mice showed clear signs of having mounted an immune response based on activation of CD8 T cells but were unable to clear the LCMV infection. This failure to eliminate virus was accompanied by a failure to generate spleen cells capable of lysing LCMV-infected fibroblasts in vitro. Spleen cells from LCMV-infected -/- mice were able to lyse hematopoietic target cells after exposure to phorbol 12-myristate 13-acetate and ionomycin, provided the target cells expressed the Fas antigen. Spleen cells from -/- mice also responded to alloantigen in mixed leukocyte culture by blastogenesis and proliferation. The resulting cells were able to lyse hematopoietic target cells, although not as well as spleen cells from +/+ littermates sensitized in the same manner. However, lysis by -/- cells was again seen only if the target cells expressed Fas antigen. We conclude that perforin-less -/- mice retain and express the Fas lytic pathway as expressed in vitro but that this pathway is insufficient to clear an LCMV infection in vivo.

Animals↗
PubMed1994

Characterization of recombinant mouse perforin expressed in insect cells using the baculovirus system.

Perforin, a potent pore-forming protein, plays an important role in killer lymphocyte-mediated cytolysis. The studies on perforin, although already extensive, have been hampered by the limited amount of perforin naturally available from killer lymphocytes. In the present study, a full-length mouse perforin was expressed in insect cells using recombinant baculovirus. Recombinant perforin appeared to be functional in terms of lysing erythrocytes and nucleated target cells. These results suggest that the recombinant DNA approach developed in the present study may offer a new way for preparing sufficient amounts of engineered perforin for use in the studies aimed at dissecting the functional domains of the perforin molecule.

Animals↗
PubMed1994

Pressure effects and thermal stability of myosin rods and rod minifilaments: fluorescence and circular dichroism studies.

In the present study hydrostatic pressure was applied upon both skeletal myosin rod molecules and rod minifilaments to learn more of the intra- and intermolecular interaction behavior of myosin. Applied pressure disassembled the rod minifilaments into individual rod molecules and dissociated each myosin rod molecule into two chains of alpha-helix. The dissociation and disassembly profiles of these systems were obtained by measuring their fluorescent anisotropy under pressure. The mid-disassembly pressure of rod minifilaments at 0.4 mg/mL concentration was 430-490 bar. However, dissociation of two helical strands of rod molecules occurred at a much higher pressure, with a mid-disassembly pressure of 1300 bar at this concentration. These results indicate that the intramolecular interactions occurring between two alpha-helical chains of a rod molecule are much more stable under pressure than the intermolecular interactions that occur among rod molecules in a minifilament. The regions in the rod molecules involved in filament assembly were investigated through usage of both the intrinsic fluorescence of tryptophan residues and the extrinsic fluorescence of 6-acryloyl-2-(dimethylamino)naphthalene (acrylodan) labeled cysteine residues. The blue spectral shifts upon minifilament formation suggest the participation of both light meromyosin (LMM) and subfragment-2 (S-2) regions of myosin rods in the filament formation. Profiles of thermal unfolding of myosin rod molecules and rod minifilaments were obtained by circular dichroism measurement. The multiple transitions exhibited upon unfolding profiles indicated the presence of more than one structural domain, each correlating with a cooperative transition. The domain transitional temperatures were found to be 1-4 degrees C higher for rods in minifilaments than those for rod molecules in a solution of similar ionic composition, indicating that all structural domains are involved in filament assembly. Furthermore, the domain transitional temperatures for rod molecules in a buffer containing 0.6 M NaCl were 6-8 degrees C higher than those for rod molecules in 5 mM sodium pyrophosphate buffer, suggesting that each structural domain of a rod molecule becomes stabilized at 0.6 M NaCl solution.

Animals↗
PubMed1994

Kinetics of the immune response and regression of metastatic lesions following development of humoral anti-high molecular weight-melanoma associated antigen immunity in three patients with advanced malignant melanoma immunized with mouse antiidiotypic monoclonal antibody MK2-23.

Active specific immunotherapy has been implemented in patients with advanced malignant melanoma, utilizing the mouse antiidiotypic (anti-id) monoclonal antibody (mAb) MK2-23 which bears the internal image of high molecular weight-melanoma associated antigen (HMW-MAA). In a previous study, development of anti-HMW-MAA immunity in patients with advanced malignant melanoma immunized with anti-id mAb MK2-23 was found to be associated with a statistically significant survival prolongation. Since no information is available about the relationship between development of immunity and clinical response in patients immunized with anti-id mAb, the present study has characterized the kinetics of the immune response in three patients with advanced malignant melanoma who experienced regression of metastatic lesions following immunization with the anti-id mAb MK2-23. The three patients developed anti-mouse IgG antibodies, anti-anti-id antibodies and anti-HMW-MAA antibodies. The anti-HMW-MAA antibodies are mainly IgG, suggesting that the immune response elicited by anti-id mAb MK2-23 is T-cell dependent. The development of anti-HMW-MAA immunity preceded the reduction in the size of metastatic lesions. This temporal relationship suggests but does not prove that the anti-HMW-MAA immunity elicited by anti-id mAb MK2-23 has a beneficial effect on the clinical course of the disease in patients with malignant melanoma. This finding in conjunction with minor side effects associated with repeated administrations of mouse anti-id mAb MK2-23 suggest that active specific immunotherapy with anti-id mAb which bear the internal image of melanoma-associated antigen represents a viable therapeutic approach to malignant melanoma.

Aged↗
PubMed1994

Intraoperative transcranial electrical motor evoked potential monitoring during spinal surgery under intravenous ketamine or etomidate anaesthesia.

Motor evoked potentials (MEPs), monitoring the motor function directly, are superior to somatosensory evoked potentials (SSEPs) in monitoring the motor system during spinal surgery. Reliable MEPs are difficult to elicit under normal anaesthesia. Using intravenous anaesthesia with either ketamine or etomidate infusion, we performed intraoperative MEP monitoring in 12 spinal operations for 11 cases from February 1992 to May 1992. For anaesthesia, ketamine was used in 5, etomidate in 7, fentanyl was supplemented in all, muscle relaxation at 30% to 50% of pre-anaesthetic muscle power was maintained with atracurium or vencuronium infusion. Transcranial bipolar electrical stimulation was used to induce MEPs. Concomitant SSEP monitoring was performed in 3. No significant anaesthesia related side effects were noted except one episode of unpleasant dream occurred in the ketamine anaesthesia group. Successful monitoring was achieved in 10 sessions. In 5 of which warning to the surgeons was made due to sudden MEP deterioration, which recovered followed by definite management in four and persisted in one. In the other 5 sessions, no warning was made due to stationary or gradual change in MEPs. Bilateral two-channel recordings were used in 3 sessions. In 2 of which unilateral transient change was noted. Loss of SSEPs was noted in one despite unchanged MEPs, in whom only new sensory deficits occurred postoperatively. Compared to the baseline MEPs in terms of latency and amplitude, the final MEPs improved in 5 sessions, did not change significantly in 4 sessions, deteriorated in one session, and were correlated well with the immediate postoperative motor status.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Utilization of cyclosporine H to elucidate the possible mechanisms of cyclosporine A-induced osteopenia in the rat.

The immunosuppressive agent cyclosporine A (CsA) produces in vivo in the rat marked osteopenia and elevation of serum bone gla protein (BGP) that reflects the high bone turnover and increased circulating levels of 1,25-dihydroxyvitamin D [1,25(OH)2D]. Cyclosporine H (CsH), a D-N-MeVal11 analog of CsA, is not immunosuppressive, and in contrast to CsA, it neither binds to cyclophilin nor alters cytokine activity. This distinction between CsH and CsA provides a means of elucidating whether CsA exerts an effect on bone and 1,25(OH)2D via immune-mediated mechanisms. We therefore studied three groups of male Sprague-Dawley rats (300 to 350 g body weight [BW]) randomly divided to receive either cyclosporine vehicle, CsA, or CsH 15 mg/kg BW by daily gavage for 28 days. Blood samples were assayed for ionized calcium (Ca2+), serum BGP, serum parathyroid hormone (PTH), and 1,25(OH)2D by specific radioimmunoassay on days 0, 14, and 28. Histomorphometric evaluations were performed on the right tibia after tetracycline and calcein labeling and killing of the rats at the end of 28 days of treatment. In CsA-treated rats, serum BGP levels were significantly increased (155.2 +/- 30.7 ng/mL v 107.3 +/- 16.8 and 111.5 +/- 13.1 at day 28, P < .05) compared with control and CsH groups, respectively. Similarly, 1,25(OH)2D was significantly increased in CsA-treated rats versus control and CsH group (134.9 +/- 35.3 pg/mL v 70.2 +/- 16.6 and 69.8 +/- 20.6 [P < .05], respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Effects of ovariectomy and estrogen on the serum levels of insulin-like growth factor-I and insulin-like growth factor binding protein-3.

To determine the effects of ovariectomy and 17 beta-estradiol (E2) on serum IGF-I and its binding proteins, female Sprague-Dawley rats, aged 95 days, were divided into four groups. Group 1 was sham-operated; groups 2, 3, and 4 were ovariectomized. Groups 3 and 4 received daily injections of 200 ng (low dose) and 5000 ng (high dose) E2/kg body wt./day, respectively and the others were given solvent vehicle. Ovariectomy resulted in a significant increase in serum IGF-I (P < 0.001) at 30 and 35 days post-surgery; the increase was prevented in animals that received low-dose E2 while high-dose E2 reduced serum IGF-I levels below those of the sham-operated controls (P < 0.01). Serum IGF-binding proteins (IGFBPs) were determined by IGF-ligand blot analysis, and the resulting autoradiograms quantified by laser densitometry. The intensity of the IGFBP-3 bands changed in parallel with serum IGF-I levels. Ovariectomy increased, low-dose E2 restored, and high-dose E2 reduced serum IGFBP-3 levels compared to the levels for the sham-operated controls. The intensities of binding protein bands smaller than those of IGFBP-3 appeared unchanged by the treatment regimens. A Western immunoblot analysis with IGFBP-3 antiserum confirmed the ligand-blot data. The changes in the levels of IGF-I and its binding proteins were accompanied by ovariectomy-induced increase in osteoblast and osteoclast numbers and loss of cancellous bone that were attenuated by E2 administration. We conclude that there is a possible role for IGF-I in the pathogenesis of the increased bone turnover that occurs early in ovarian hormone deficiency.

Animals↗
PubMed1994

Cardiac tamponade in an infant. A rare complication of central venous catheterisation.

A 2994 g infant suffered cardiac tamponade from an infusion of total parenteral nutrition through an indwelling central venous catheter. The infant survived as a result of early diagnosis and aggressive therapeutic intervention. Cardiac tamponade secondary to central venous catheterisation is rare, but potentially lethal. Possible mechanisms are direct puncture by the catheter tip, or osmotic injury from the use of hypertonic solutions. To avoid this complication, the catheter tip should be prevented from entering the right atrium and its position should be checked periodically by chest X ray. Cardiac tamponade should be considered in any patient with a central venous catheter whose clinical condition deteriorates suddenly. Diagnostic or therapeutic pericardiocentesis should be employed as the first measure and time should not be wasted on other diagnostic procedures.

Cardiac Tamponade↗
PubMed1994

Low dose of intrathecal hyperbaric bupivacaine combined with epidural lidocaine for cesarean section--a balance block technique.

The present study was designed to develop a combined spinal/epidural anesthetic technique for cesarean section. We compared the effects of different doses of intrathecal hyperbaric bupivacaine (0.5%) combined with epidural lidocaine (2%). We attempted to interrupt somatosensory pathways with spinal anesthesia but to avoid acute high thoracic sympathetic block. The visceral afferent pathways were to be blocked relatively slowly with epidural lidocaine. Eighty term parturients were randomly divided into four groups. In Group A, 2.5 mg of bupivacaine intrathecally combined with 22.2 +/- 4.6 mL of lidocaine epidurally provided insufficient muscle relaxation. In Group B, 5 mg of bupivacaine with 10.1 +/- 2.0 mL of lidocaine resulted in satisfactory anesthesia with rapid onset and minimum side effects. Anesthesia in Group C (7.5 mg of bupivacaine) and Group D (10 mg of bupivacaine) was mostly due to spinal block. Complications included hypotension, nausea, and dyspnea. The combined spinal/epidural technique, using 5 mg of bupivacaine and with sufficient epidural lidocaine to reach a T4 level, had the advantages of both spinal and epidural anesthesia with few of the complications of either.

Adult↗
PubMed1994

Arteriovenous concentration differences of propofol during and after a stepdown infusion.

To compare the arterial and venous concentration differences of propofol, six healthy adult patients received a propofol infusion by the Bristol three-stage manual stepdown technique. Both the mean arterial and venous concentrations of propofol remained relatively stable during the 40-min infusion. Simultaneous blood sampling from the artery and vein during the infusion period resulted in arterial concentrations significantly higher than venous concentrations. This relationship was reversed after stopping the infusion. The mean +/- SD (range) venous to arterial concentration differences were -28.8% +/- 18.3% (-71% to 1.7%) during the infusion and 18.9% +/- 13.4% (-1.5% to 40.9%) after the infusion. We conclude that venous concentrations were not useful to estimate the arterial value during and after a stepdown propofol infusion. Arterial sampling is more appropriate in pharmacologic studies of propofol.

Adult↗