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Biomedical subjects

C C Chao

Publications and source records attributed to C C Chao.

At least 199 records · Page 11Linked to original sources
PubMed1989

Monospecific antibodies against a synthetic peptide predicted from the alpha-3 nicotinic receptor cDNA inhibit binding of [3H]nicotine to rat brain nicotinic cholinergic receptor.

Polyclonal antibodies were raised against a synthetic decapeptide (designated S3) predicted from a segment of the alpha-3 subunit cDNA (amino acid residues 130-139) encoding the rat brain nicotinic cholinergic receptor. This segment was selected because it may be proximate to the nicotine/acetylcholine-binding site of the receptor (1). By radioligand binding assays and sucrose density gradient centrifugation, these monospecific antibodies were shown to inhibit the binding of [3H]nicotine to both the large molecular weight rat brain receptor (240 kDa) and to an SDS-disaggregated nicotine-binding subunit species (80 kDa), in a dose-dependent manner. The neutralizing effect of the anti-S3 antibodies supports the view that this region of the protein is closely related to the agonist binding site.

Amino Acid Sequence↗
PubMed1989

Detection of a Thy-1 precursor in human T lymphoma cell lines.

In an attempt to gain insight into the biosynthesis and processing of human Thy-1, rabbit antisera (R alpha TP) were raised against a synthetic peptide (TP) of 13 amino acid residues of identical amino acid sequence to that of residues 110-122 of the putative Thy-1 precursor deduced from the cDNA sequencing. Immunoblotting assay showed that the IgG fraction of R alpha TP (R alpha TP-IgG) recognized the synthetic peptide without demonstrable cross-reactivity with isolated human brain Thy-1 and detergent-solubilized membrane proteins of human brain cells. Immunohistochemical studies showed that both R alpha TP-IgG and HB-2S-1 (a monoclonal antibody which reacts with both membrane-bound Thy-1 on viable cells and detergent-solubilized Thy-1) stained cells of two human T lymphoma cell lines (HUT-78 and HUT-102) but they did not stain cells of a human B lymphoma cell line (Raji). In contrast, in cell surface indirect immunofluorescence assay, HB-2S-1 reacted with HUT-78 and HUT-102 cells while R alpha TP-IgG did not. Taken together, these data indicate the existence of a precursor form of human Thy-1 which is processed prior to anchoring to the cell surface.

Antigens, Surface↗
PubMed1989

The ocular surface in cystic fibrosis.

Seventeen patients with cystic fibrosis and 17 age-, race-, and sex-matched controls were examined under standardized conditions. Testing included slit-lamp biomicroscopy, fluorescein staining, rose bengal staining, Schirmer's basic tear test, tear film break-up time, tear pH, tear lysozyme, tear protein, lid and conjunctival cultures, and conjunctival impression cytology. Cystic fibrosis patients showed a statistically significant increase in the incidence of fluorescein staining and clinical blepharitis, as well as significantly decreased Schirmer testing and tear lysozyme. Ocular surface abnormalities in these patients may be attributable to aqueous and lipid tear film deficiencies. Cystic fibrosis patients showed normal conjunctival epithelial cell morphology, grew no pathogenic organisms, and had a decreased incidence of conjunctival bacterial colonization.

Adolescent↗
PubMed1989

Evaluation of microleakage due to cuffs of endotracheal tubes during positive end-expiratory pressure ventilation.

Mallinkrodt tubes (internal diameter 8.0 mm) with high residual volume and low pressure cuffs were used to evaluate the influence of positive end-expiratory pressure (PEEP) on leakage from cuffed endotracheal tubes. A thin smooth epidural catheter (Portex) was placed immediately above the cuff to monitor visually whether methylene blue dye solution (2-3 ml) passed through the cuff and stained the trachea. One hundred male patients undergoing elective orthopedic surgical procedures were randomly divided into five groups: a control group and groups using 2.5, 5.0, 7.5, and 10 cm H2O of PEEP during nitrous oxide-oxygen-isoflurane anesthesia. The cuff pressure was set to 25 cm H2O in each group. The cuff pressure was recalibrated and evidence of staining below the cuff was sought with a fiberscope every twenty minutes for a total of three times. Leakage increased with PEEP level but the amount was not statistically significant and the difference between groups was not significant.

Humans↗
PubMed1989

Hemodynamic response to ketamine and diazepam in dogs with acute cardiac tamponade.

Induction of anesthesia may produce a significant hazard to patients with critical cardiovascular status. Ketamine has been advocated as the drug of choice for maintaining cardiovascular performance during induction of anesthesia in high-risk surgical patients. There is no detailed information on the use of ketamine in patients with acute cardiac tamponade. The purpose of this study was to assess the safety of ketamine in acute cardiac tamponade in dogs. Sixteen dogs were studied and a Swan-Ganz catheter was inserted through the right external jugular vein to measure hemodynamic parameters. Data obtained before tamponade was used as the control, then, tamponade was accomplished by infusing a mixture of saline and blood from the same dog through a catheter into the pericardial sac. Ketamine, 2 mg/kg intravenously resulted in an improvement of cardiac output from 1.2 +/- 0.5 L/min to 2.2 +/- 0.3 L/min (p less than 0.05). The addition of diazepam 0.3-0.5 mg/kg blunted the ketamine-induced cardiostimulation and resulted in a fall in cardiac output from 2.2 +/- 0.3 L/min to 1.7 +/- 0.2 L/min (p less than 0.05). Five dogs with intrapericardial pressure above 10 mmHg did not respond to ketamine. Diazepam did not blunt any more to these decompensated dogs. This study demonstrated that ketamine plays a beneficial role in acute cardiac tamponade as a safe induction agent. Limitation still existed when using ketamine in dogs with high intrapericardial pressure because they showed only negative inotropic effect during decompensation. Diazepam inhibited the cardiostimulant effects of ketamine in dogs with tamponade, but could not elicit a negative inotropic effect during decompensation. The practical application of ketamine and diazepam in patients with acute cardiac tamponade could be determined by evaluation of intrapericardial pressure through a needle-transducer kit.

Acute Disease↗
PubMed1989

Retrospective evaluation of general anesthesia for oral and maxillofacial surgery during a 10-year period (1976-1985).

Anesthetic cases of oral and maxillofacial surgery during the period 1976-1985 were reviewed. There was a total of 653 cases, and the most frequently performed operation in this series was open reduction of maxillofacial bone fracture (22.8%). Special clinical problems were encountered in the 72 cases (11.02%) who underwent surgery for osteoradionecrosis, because most of them suffered from trismus and stiff neck. Nasotracheal intubation was more commonly used (84.69%). Sixty six cases received tracheostomy since they suffered from serious trismus and/or severe maxillofacial fracture. The recently introduced method of induction using etomidate and fentanyl seemed effective in maintaining hemodynamic stability. In 147 cases (22.51%), the anesthesia lasted more than 4 hours. In 366 cases (56.04%), a local infiltration of the operation field was performed with 1:100,000 epinephrine. Of these, 76 cases developed cardiac arrhythmia, mainly VPC (ventricular premature contraction) 12 of whom had a history of preoperative cardiac arrhythmias. The incidence of preoperative medical disease was 10.27%, the most common being cardiovascular (32.84%) and respiratory (26.87%) disease. Complications occurred during anesthesia in 122 cases (18.69%) with a high incidence of cardiac arrhythmia (67.21%).

Adolescent↗
PubMed1989

The optimal dose of atropine via the endotracheal route.

Fifty ASA class I or II patients, undergoing general or gynecological surgery under general anesthesia with endotracheal intubation, were randomly divided into five groups. Group I received 10 ug/kg atropine intravenously, group II to V received 10 ug/kg, 20 ug/kg, 30 ug/kg, 40 ug/kg, respectively via endotracheal route through an epidural catheter. All were given five manual deep breaths after the injection of atropine. The maximum increase in heart rate (MIHR) and the time to maximum heart rate (TMHR) were evaluated. There was no marked MIHR in group II. Group III had a MIHR similar to that of group I (17.5/min vs 20/min, p greater than 0.05), but had a longer TMHR than group I (120 sec vs 82.5 sec, p less than 0.005). Groups IV and V had greater MIHR than group I (28.7 and 29.5 vs 20/min, p less than 0.005), and a TMHR similar to that of group I (85 and 90.2 vs 82.5 sec, p greater than 0.05). For emergency procedures, if atropine must be given without an intravenous catheter, 30 ug/kg or more given endotracheally can achieve an effect comparable to that of 10 ug/kg given intravenously.

Adult↗
PubMed1989

Epidural anesthesia for major abdominal surgery complicated by muscular dystrophy--a case report.

Anesthesia for patients with muscular dystrophy is a great challenge to the anesthesiologists. A 56-year-old female with muscular dystrophy was diagnosed as having colon cancer. Since surgical intervention was indicated, epidural anesthesia with double catheters was performed. The entire anesthetic course was uneventful. Based on the experience obtained, it is concluded that epidural anesthesia offers a good alternative to general anesthesia for major abdominal surgery complicated by muscular dystrophy.

Anesthesia, Epidural↗
PubMed1989

Prevention of hypothermia during abdominal surgery: comparison of thermal tube and blanket.

Twenty patients who received elective abdominal surgery for more than two hours were randomly assigned into two groups. Group 1 was warmed by using "EXACON" thermal therapy system model TT8200. Group 2 was warmed by using a thermal blanket of aquamatic K-thermia (electronic control), model PK-600 of American Hamilton medical systems. Other variables were kept constant, and the theater temperature was maintained at 24 degrees C. Core temperature was recorded every five minutes in a two hour period. There were statistically significant differences between these two groups intra-operatively. Decrease of temperature between these two groups had significant changes from 30 minutes to 2 hours (p less than 0.05). The warming effect of esophageal thermal tube was well controlled by directly warming the central compartment. However, the effect of blanket was unpredictable due to wet dressing and superficial warming of surgical fields. There were no side effects during the study.

Abdomen↗
PubMed1989

The effect of low dose intravenous lidocaine in tracheal intubation with atracurium.

This study investigated the effect of low dose intravenous lidocaine during tracheal intubation with atracurium. Forty patients were studied in double blind, randomized groups. Intravenous lidocaine, 1 mg/kg, or saline was given to the patients three minutes before induction. This result showed there is no difference about the intubation condition between these groups. The changes in mean arterial blood pressure and heart rate after laryngoscopy and intubation were similar in both groups. However, the lidocaine group had a shorter time to have 75% twitch depression (when the first twitch of train of four equals 25% of the original height) than the control group (p less than 0.05). The addition of intravenous lidocaine 1 mg/kg during induction has no significant advantage although it can shorten the intubation time.

Adult↗
PubMed1988

Uncoupling of translocation across microsomal membranes from biosynthesis of influenza virus hemagglutinin.

This communication presents our recent studies on the biosynthesis of influenza virus hemagglutinin (HA) in a mammalian-cell-free system and its translocation across microsomal membranes. RNAs coding for wild-type (full-length) and mutant (truncated) forms of HA were generated by in vitro transcription by using bacteriophage T7 DNA-dependent RNA polymerase. These RNAs were translated in a rabbit reticulocyte system that was supplemented with dog pancreas membranes, either before translation was initiated or after it had been artificially terminated with the antibiotic cycloheximide. All forms of HA could be cotranslationally translocated. However, only truncated molecules (83% of full length) could translocate after protein synthesis had been terminated. Posttranslational translocation was dependent on the presence of a functional N-terminal signal sequence and occurred only in the presence of ribosomes. The molecular mechanism of protein targeting and translocation across the membrane of the endoplasmic reticulum is discussed based on the signal hypothesis.

Animals↗
PubMed1988

Studies on the isolation and composition of human ocular mucin.

A method for the isolation and purification of human ocular mucin from the brief saline extract of human ocular mucus is reported. Initial purification of ocular mucin was achieved by sequential chromatography of the saline-soluble mucus extract from an individual donor's mucus pool on columns of Sephadex G-50 and Sepharose CL-4B. A portion of such mucin isolate was subjected to quantitative analysis of the O-seryl (threonyl)-N-acetylgalactosaminyl linkage, characteristic of mucins, by alkaline beta-elimination and tritiated borohydride reduction. Following Bio-Gel P-2 filtration, the mucin isolate whose cleaved oligosaccharides contained tritiated galactosaminitol greater than 0.5 microCi mg-1, a value that represents at least 64% of that observed for bovine and ovine submaxillary reference mucins, was considered to be mucin-rich. These isolates were subjected to further purification on Sephacryl S-500 and DEAE-Trisacryl M column chromatographies. The purified mucin had a minimum molecular weight of 120 kDa. It consisted of 25-30% protein and 54-55% carbohydrate. Its amino acid and carbohydrate compositions are characteristic of a mucin structure. The purity of the mucin was verified by SDS-gradient PAGE. Upon isoelectric focusing, polydispersity/microheterogeneity were exhibited in the pI range 5.0-6.6.

Amino Acids↗
PubMed1988

A cellular basis for functionally releasable pools in somatotropes.

In an attempt to define the cellular basis for the phenomenon of releasable pools, we compared the effects of two growth hormone (GH)-releasing peptides which differentially influence the dynamics of GH release. Monodispersed anterior pituitary cells from neonatal male rats were subjected to reverse hemolytic plaque assays for GH in the presence or absence of GH-releasing peptide (GHRP-6, an enkephalin-like hexapeptide) and rat GH-releasing factor (GRF). GRF increased the rate of plaque formation (an index of the rate of hormone release) from almost all somatotropes, whereas GHRP-6 influenced only half of these cells. Analysis of plaque sizes (which provides a relative index of the cumulative amount of hormone released per cell) revealed that GRF produced a bimodal frequency distribution of plaque sizes, demonstrating that some somatotropes released more hormone than others after treatment with a maximal dose of this secretagogue. This pattern contrasted with those of untreated and GHRP-6 treated somatotropes which each produced unimodal frequency distributions that were skewed to the left (toward smaller plaques) and were virtually superimposable at the end of a 4 h incubation. However, GHRP-6 greatly accelerated the rate at which the final size distribution pattern was attained. Taken together, these results suggest that GHRP-6 causes the immediate release of a limited pool of GH which is present only in a discrete subpopulation of somatotropes that respond to GRF. This pool may be identical to that which is released over a more prolonged period under basal conditions. Moreover, GRF appears to access a more substantial pool of hormone which is not released by GHRP-6. This pool is present in a small minority of somatotropes but probably accounts for a larger portion of the GH released by pituitaries stimulated with GRF.

Animals↗
PubMed1988

Association of serum albumin with tear prealbumin in human ocular mucus.

Tear prealbumin previously isolated from the saline-extractable human ocular mucus was further examined for microheterogeneities using crossed-immunoelectrophoresis through development with antiserum to the isolate. The isolate was examined following the final two stages of its chromatographic purification by DEAE ion exchange and Sephadex G-75. The crossed-immunoelectrophoretic pattern of the tear prealbumin isolate, recovered following DEAE ion exchange chromatography, indicated the existence of two types of minor degrees of binding between tear prealbumin and serum albumin. One type appeared to be tightly associated while the other was interpreted as weakly bound, where serum albumin was separable from tear prealbumin in an electric field. The total association of serum albumin with tear prealbumin in this isolate was estimated to be about 3-7%. Crossed immunoelectrophoresis of the isolate after its final stage of purification on Sephadex G-75 chromatography showed the absence of the weakly bound serum albumin. However, the tight tear prealbumin/serum albumin association remained, estimated to be 1-3%.

Chromatography, Ion Exchange↗