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Biomedical subjects

E Cheng

Publications and source records attributed to E Cheng.

At least 91 records · Page 5Linked to original sources
PubMed1984

Effect of human saliva and serum on ion transport by dog tracheal mucosa. Comparison of normal subjects with cystic fibrosis patients.

It has been proposed that cystic fibrosis (CF) saliva or serum contains factors that alter ion transport in various tissues. Since CF frequently affects the lungs, and disturbances in epithelial ion transport has been proposed to contribute to the pathophysiology of pulmonary disease in CF, we investigated whether saliva or serum from CF patients could alter ion transport across airways epithelium. Canine tracheal mucosae were mounted in lucite chamber and perfused on both sides with Krebs-Henseleit solution at 37 degrees C and pH 7.4. Unidirectional fluxes of 22Na and 36Cl were measured in pairs of mucosal tissues under short circuit conditions. Saliva from 5 CF patients stimulated short circuit current (SCC) by 33 +/- 8 microA/cm2 and net Cl secretion by 1.10 +/- 0.33 muEq/cm2 X h (mean +/- SE; p less than 0.05). No change occurred in net Na absorption. Saliva from normal subjects raised SCC by 34 +/- 7 microA/cm2 and increased net Cl secretion by 1.29 +/- 0.46 muEq/cm2 X h (n = 9; p less than 0.02). Serum from both CF patients and control subjects briefly stimulated SCC. Exposure of tracheal mucosa to normal as well as CF saliva, such as by aspiration, or to serum, such as by transudation, stimulates Cl secretion, and therefore water secretion into airway lumen. There appears to be no difference in the effect exerted by CF saliva or serum and that of normal subjects. These findings argue against the presence of a specific circulating or secreted CF factor that could alter ion transport across respiratory epithelia in a way that might contribute to lung disease in CF.

Adolescent↗
PubMed1983

Phase II evaluation of m-AMSA (4'-(9-acridinylamino)-methanesulfon-m-anisidide) in patients with adenocarcinoma of the pancreas.

m-AMSA (4'-(9-acridinylamino)-methanesulfon-m-anisidide, a substituted acridine derivative, was administered to 27 patients with adenocarcinoma of the pancreas. The dose ranged from 90-210 mg/m2/course. The toxic effects were primarily hematologic. Twenty-four of the patients were evaluable for response. These patients received a median of 2 doses (range 1-7). The median time from diagnosis to therapy was 2 months (range 0-16). Two patients achieved an MR lasting 4 and 2 months, respectively. Two patients had stabilization for 6 and 3 months. The median survival for all patients was 3 months. Survival distribution for patients with prior chemotherapy versus no previous therapy was not significantly different (p = 0.5). This study suggests that m-AMSA has little value as a single agent in the treatment of adenocarcinoma of the pancreas.

Adenocarcinoma↗
PubMed1983

Alteration of the pharmacokinetics of high-dose ara-C by its metabolite, high ara-U in patients with acute leukemia.

The pharmacokinetics of high-dose cytosine arabinoside (HiDAC) given as a three-hour intravenous infusion at 3 g/m2 were studied in five patients with acute leukemia during relapse and/or remission of their disease. Apparent steady state plasma levels of ara-C during 13 infusions averaged 115 +/- 32 microM. Upon cessation of the infusion, cytosine arabinoside (ara-C) was rapidly cleared from the plasma. The apparent postinfusion kinetics of ara-C were triexponential with a distribution half-life of 16 minutes and elimination half-lives of 1.8 hours and six hours. Total clearance averaged 86 L per hour and mean residence time averaged 0.47 hours. Disease status (relapse or remission) had no apparent effect on the pharmacokinetic characteristics of ara-C. Peak levels of ara-U averaged 310 microM and the metabolite had an average apparent elimination half-life of 3.75 hours. Despite the persistence of ara-U at about 100 microM at the time of administration of subsequent infusions of ara-C, there was no further accumulation of ara-U in the plasma with repetitive infusions of HiDAC. In vitro studies indicate that ara-U can exert an inhibitory effect on deoxycytidine (dCyd) deaminase activity. The ratio of the Ki of ara-U to the Km of ara-C for cytidine (Cyd)-dCyd deaminase is 40:1; however, during the gamma phase of ara-C elimination, the ratio of ara-U:ara-C in plasma is at least 100:1. Thus, a retardation of systemic catabolism of ara-C by ara-U is possible. Two to three hours after the termination of the HiDAC infusion, the ara-C cerebrospinal fluid: plasma ratio is 1-3:1, a feature of potential therapeutic significance. The slower elimination of ara-C from the CSF may also contribute to the plasma gamma half-life.

Acute Disease↗
PubMed1983

Vindesine in the treatment of malignant mesothelioma: a phase II study.

Vindesine (VDS) is a new semisynthetic vinca alkaloid which has demonstrated therapeutic activity against a variety of solid tumors. A phase II trial of this agent was performed in patients with advanced malignant mesothelioma. VDS at a dose of 3 mg/m2 was given iv once weekly for 4-6 weeks and then every 2 weeks thereafter. Only one of 17 evaluable patients had a partial remission, lasting 5 months (95% confidence limits, 0%-17%). Toxic effects of VDS included leukopenia, peripheral neuropathy, and alopecia. VDS has minimal activity in malignant mesothelioma.

Adult↗
PubMed1982

Pharmacokinetics of cisplatin regional hepatic infusions.

Cisplatin (DDP), a potent antineoplastic agent, is usually administered via a peripheral vein. Recently, there has been considerable interest in intraarterial regional infusions of DDP. The pharmacokinetics of DDP when administered by this technique have not been explored in detail. We studied DDP pharmacokinetics in dogs given DDP by infusion and bolus injection in the hepatic artery (H.A.), portal vein (portal V), and peripheral vein (P.V.). Blood and biliary platinum concentrations ([Pt]) were assayed by flameless atomic absorption spectrophotometry. During an infusion into the H.S., peak [Pt] in the vessel were markedly higher (mean value 19 micrograms/ml) than those found, simultaneously, in the portal V or superior vena cava. Following a bolus injection of DDP into the H.A., higher H.A. [Pt] were also seen, but [Pt] rapidly (within 5-10 minutes) equilibrated in all sites sampled. During the H.A. infusion, most [Pt] was in its free (active) form. Bile and hepatic tissue were also sampled. Hepatic artery infusions of DDP give high drug concentrations in the perfusing blood, while systemic [Pt] are much lower. During the infusion, the majority of DDP is in its active (unbound) state.

Animals↗
PubMed1982

Cisplatin, doxorubicin, cyclophosphamide, and vindesine combination chemotherapy for non-small cell lung cancer.

Seventy-four patients with non-small cell lung cancer were treated in a prospective, randomized trial either with a four-drug combination of cisplatin, doxorubicin, cyclophosphamide, and vindesine (PACE) or with a three-drug combination of cisplatin, cyclophosphamide, and vindesine (PCE). None of these patients had received prior chemotherapy, and all had a Karnofsky performance status of at least 60. Of 68 evaluable patients, 21 (31%) had complete or partial remissions. Response rates for PACE and PCE were similar, and there was no difference in response rates for patients with adenocarcinoma or epidermoid cancer. The median duration of remission was 10 months (range, 2-26+); five patients are still in remission (median, 18+ months; range, 17+ to 26+). The median duration of survival for responding patients (complete or partial) was 18 months. Toxic effects, including mild to moderate myelosuppression, peripheral neuropathy, and nephrotoxicity, were manageable in general. The response rates and remission durations for PACE and PCE are similar to those seen with the two-drug combination of cisplatin and vindesine, and toxic effects are similar. Thus, the addition of doxorubicin and/or cyclophosphamide adds no advantage to the use of the cisplatin and vindesine combination alone.

Adenocarcinoma↗
PubMed1981

VAB-3 combination chemotherapy of metastatic testicular cancer.

The initial response and long-term follow-up of 74 evaluable patients who received combination chemotherapy for metastatic nonseminomatous testicular cancer are reported. Patients were treated with a protocol (VAB-3) including vinblastine, actinomycin-D, bleomycin, and cis-dichlorodiammine platinum (DDP). VAB-3 alone caused complete remission (CR) in 54% (40/74) and partial remission (PR) in 26% (1974). Five patients with less than CR to chemotherapy achieved CR following surgical excision of residual mature teratoma after starting VAB-3 protocol, resulting in an overall CR rate of 61% (45/74). With a minimum follow-up of 24+ months, and a median follow-up of 35+ months for those still living, 45% (33/74) of the patients are living free of evidence of disease, 4% (3/74) are living with disease, and 51% (38/74) are dead. Response to VAB-3 protocol was examined with respect to performance status, histology, prior therapy, extent of disease, tumor markers, and duration of disease from diagnosis. No one died because of toxicity of VAB-3, and life-threatening toxicity was uncommon. Long survival is significantly associated (P less than 0.001) with achievement of CR. The treatment goal for metastatic testicular cancer is cure. The achievement of CR, using aggressive combination chemotherapy and surgery, is essential in reaching this goal.

Adolescent↗
PubMed1981

VAB-4 combination chemotherapy in the treatment of metastatic testis tumors.

Forty-two patients with advanced testis carcinoma without previous chemotherapy were treated with VAB-4, and 41 were evaluable. The program consisted of three in-hospital inductions 16 weeks apart, and outpatient treatments every three weeks. Of the patients, 80% achieved complete remissions (CR). Chemotherapy alone induced CR in 61%, partial remissions (PR), in 24% and minor response (MR), in 15%. An additional 20% of patients (six PRs and 2 MRs) achieved CR following resection of residual tumor deposits. With a median follow-up of 27 months, the median duration of CR has not been reached. Of those achieving CR to chemotherapy alone, 12% had relapses. Bulk and extent of metastatic disease, histology of primary tumor, and tumor markers at the beginning of therapy influenced the frequency of CR. Of those with minimal disease, 90% achieved CR. The CR rate was 67% for those with advanced thoracic disease and 29% for those with advanced abdominal disease. Patients who had embryonal carcinoma and those who had no elevation of alpha-fetoprotein had a higher frequency of CRs. Myelosuppression with a leukocyte count drop less than 1000/mm3 occurred in three patients, and no patient had chronic renal failure or pulmonary fibrosis. One patient died from sepsis while in complete remission.

Adolescent↗
PubMed1981

Prenatal diagnosis of neural tube defects: predictive value of AF-AFP in a low-risk population.

Amniotic fluid alpha-fetoprotein (AF-AFP) determinations were performed on 1,215 women who were at low risk for fetal neural tube defects and who were undergoing mid-trimester amniocentesis for cytogenetic indications, primarily age-related aneuploidy. Maternal sera obtained before amniocentesis and amniotic fluids were assayed in duplicate for alpha-fetoprotein by radioimmunoassay. Of the 1,215 low-risk women, eight (0.7%) had significant elevations of AF-AFP (greater than or equal to +5 SD). In none of the cases was the elevation associated with a fetal neural tube defect. Two cases with elevated AF-AFP were associated with chromosome aberrations; one with impending fetal demise; one with fetal blood contamination; and one case was due to a laboratory error. In one case, no source for the elevated AFP was found, and a normal infant was delivered at term. In the final two cases, the cause of the elevated AF-AFP was a fetal abdominal wall defect (one gastroschisis and one omphalocele). The predictive value of an elevated AFP varies with the population screened, and is reduced by routine ultrasonography before amniocentesis, which at least identifies anencephaly. In a low-risk population, an elevated AF-AFP is most often not associated with a fetal neural tube defect. Because of the low predictive value and the nonspecificity of AF-AFP, genetic counselors should reconsider the recommendation of routine AF-AFP in low-risk maternal populations.

Amniocentesis↗
PubMed1981

Surgical implications of antithrombin III deficiency.

Antithrombin III is a potent coagulant inhibitor in plasma. Congenital deficiency of antithrombin III may predispose to thrombotic events and may complicate surgical management. We describe a patient with congenital antithrombin III deficiency who developed superior mesenteric vein thrombosis after the cessation of warfarin therapy which resulted in venous gangrene of the small intestine. Initial treatment of this deficiency with fresh frozen plasma and subsequent long-term management with warfarin therapy has been effective in avoiding further thrombotic events.

Adult↗
PubMed1981

Intracranial pressure telemetry system. I. Hardware development.

Results in the development of intracranial pressure(ICP) telemetry systems are reported. Included are a single-channel ICP system and a two-channel ICP and temperature system. The unit used hybrid-integrated circuits housed in a Kovar flatpack and packaged with polyurethane or Hysol epoxy. Battery and radio frequency (RF) induction power supplies were tested. The two-channel systems used RF power at 3.5 MHz and transmitted signals around 120 MHz. The package measures 3 x 2 x 0.8 cm and weighs 9 g. The pressure range is -20 to +100 mm Hg with accuracy to 1.0 mm Hg. The implant measures absolute pressure and has a baseline stability of better than +/- 2 mm Hg/month. 17 dogs and 4 goats were used for in vivo evaluation. A summary of results is presented. Detailed evaluation is given in section II of this paper.

Animals↗
PubMed1981

Intracranial pressure telemetry system. II. Animal testing.

A small, implantable, telemetric device for the long-term monitoring of intracranial pressure has been described in part I of this article. This portion of the study is designed to demonstrate the in vivo operational characteristics of that implant device in experimental animals. Results indicate that this system can provide long-term in vivo operation with rapid and accurate responses to acute changes in pressure. Data also indicate some drift in the baseline measurement of pressure. No signs of abnormal body reactions to the units were observed.

Animals↗
PubMed1980

Computer calculation of the dose distribution in the electron build-up region.

A procedure has been developed for producing accurate computer-calculated dose distributions at the air-tissue boundaries for oblique incidence of a photon beam. Measurements of the dose distribution under conditions of tangential incidence are presented for a Siemens 6 MV linear accelerator. These measurements have been compared with calculated distributions using the standard Cunningham-Clarkson calculation technique. Based on this comparison, two changes are suggested for improving the accuracy of the calculation. The grid spacing for the calculation is decreased in order that the rapid dose variations that occur at the boundary may be better followed. Furthermore, the dose calculation scheme is modified to take into account the differences in the amount of electron build-up which occurs. An algorithm is presented for making this modification. Also, the calculated dose at the exit surface had to be modified to handle the deficit of scatter material behind the calculation points. The results of these changes are shown as a comparison of a typical chest wall irradiation treatment plan using two opposing tangential fields.

Computers↗