Search PubMed⌕ Search

Biomedical subjects

J Smyth

Publications and source records attributed to J Smyth.

At least 55 records · Page 3Linked to original sources
PubMed1992

Broad spectrum neuropeptide antagonists inhibit the growth of small cell lung cancer in vivo.

The proliferation of small cell lung cancer (SCLC) cells appears sustained by multiple autocrine and paracrine circuits involving Ca2+ mobilizing neuropeptides. Consequently, broad spectrum neuropeptide antagonists which inhibit SCLC growth in vitro have been suggested as potential anticancer agents. Here we evaluated this hypothesis using xenografts of WX322 cells, a SCLC cell line that responds to multiple Ca2+ mobilizing neuropeptides. The broad spectrum neuropeptide antagonists [Arg6,D-Trp7,9,MePhe8]substance P(6-11) and [D-Arg1,D-Phe5,Trp7,9Leu11[substance P were shown to inhibit the growth of WX322 xenografts in nude mice. Similar results were obtained with xenografts of the SCLC cell line H69. The results indicate that broad spectrum neuropeptide antagonists can inhibit the growth of SCLC in vivo and suggest that these antagonists could be useful in the treatment of SCLC.

Animals↗
PubMed1992

Growth of small cell lung cancer cells: stimulation by multiple neuropeptides and inhibition by broad spectrum antagonists in vitro and in vivo.

Neuropeptides are increasingly implicated in the control of cell proliferation and their mechanisms of action are attracting intense interest. The early complex cascade of events initiated by peptides of the bombesin family including gastrin-releasing peptide is increasingly understood. The cause-effect relationships and temporal organization of these early signals and molecular events provide a paradigm for the study of other growth factors and mitogenic neuropeptides and illustrate the activation and interaction of a variety of signaling pathways. These peptides may also act as autocrine growth factors for certain small cell lung cancer cells. The results discussed here strongly suggest that the autocrine growth loop of bombesin-like peptides may be only a part of an extensive network of autocrine and paracrine interactions involving a variety of Ca(2+)-mobilizing neuropeptides in small cell lung cancer including bradykinin, cholecystokinin, galanin, neurotensin, and vasopressin. In this context, broad spectrum antagonists that prevent the function of multiple Ca(2+)-mobilizing receptors are of special interest. These antagonists block neuropeptide mediated signals and inhibit small cell lung cancer growth in vitro and in vivo. Thus, broad spectrum neuropeptide antagonists constitute potential anticancer agents.

Amino Acid Sequence↗
PubMed1992

Phase II trials of fosquidone, (GR63178A), in colorectal, renal and non-small cell lung cancer. CRC Phase II Clinical Trials Committee.

A total of 61 eligible patients with metastatic cancer have been treated in a series of Phase II trials of the novel pentacyclic pyrroloquinone, fosquidone. Tumour types were colorectal (23), renal (21), and non small cell lung (17). No patient had received prior chemotherapy. The drug was given intravenously as a 20 min infusion at the dose of 120 mg-2 on days 1 to 5 every 3 weeks. Treatment was well tolerated; the only significant side effects being mild nausea and generalised musculo-skeletal pains. Response was assessed after two cycles of therapy. No patient achieved an objective partial response. A total of nine patients demonstrated stable disease for a median duration of 11 weeks. Using this schedule of administration, fosquidone has no significant antitumour activity in this group of tumours.

Adult↗
PubMed1992

Haemodialysis-related porphyria cutanea tarda and treatment by recombinant human erythropoietin.

Haemodialysis-related porphyria cutanea tarda is a rare, but serious and mutilating skin condition, resulting from extremely high plasma porphyrin levels because of their inadequate clearance by haemodialysis. The treatment is very difficult as chloroquine is ineffective and venesection, the conventional treatment of this disease, is not always an option because of anaemia of end-stage renal disease. We report a case of haemodialysis-related porphyria cutanea tarda and her successful management by recombinant human erythropoietin treatment.

Erythropoietin↗
PubMed1992

Ondansetron compared with metoclopramide in the control of emesis and quality of life during repeated chemotherapy for breast cancer.

This was a multicentre, randomised, double-blind, parallel-group study which included female breast cancer patients, receiving their first of 6 scheduled courses of chemotherapy (cyclophosphamide greater than or equal to 500 mg/m2). Patients received an intravenous dose of 16 mg dexamethasone with either 8 mg ondansetron or 60 mg metoclopramide before chemotherapy, followed by oral dosing with 8 mg ondansetron or 20 mg metoclopramide 3 times daily for 5 days. A total of 93 patients were treated with ondansetron and 94 patients with metoclopramide. On day 1 of their first course of treatment 91 and 60% of patients in the ondansetron and metoclopramide groups respectively were free of emesis (p less than 0.001). Over the 5-day treatment period, the corresponding figures were 81 and 48% (p less than 0.001). The results for nausea also revealed highly statistically significant treatment differences (p less than 0.001) in favour of ondansetron for both day 1 and day 1-5 analyses of the first treatment course. Over the series of courses, 67% of patients receiving ondansetron completed all 6 courses with a maximum of 2 emetic episodes on their worst day, compared with 28% of patients receiving metoclopramide (p less than 0.001). A similar analysis for nausea revealed that 49% of patients receiving ondansetron completed all 6 courses with 'none' or 'mild' nausea compared with 27% of patients receiving metoclopramide (p less than 0.001). These differences were reflected in quality of life data (Rotterdam Symptom Checklist). After the first course of treatment, a statistically significant improvement (p = 0.002) in the psychological subscale scores was observed after ondansetron compared with metoclopramide. No differences were observed in the physical or functional activity subscales after the first course. However, the quality of life results over the series of courses revealed a more pronounced difference in favour of ondansetron in the psychological subscale scores (p less than 0.001) as well as trends in favour of ondansetron in the physical (p = 0.096) and functional activity (p = 0.056) subscales. Extrapyramidal symptoms were reported in 19% of patients in the metoclopramide group and resulted in 15% of patients withdrawing from their randomised anti-emetic schedule, either during or between treatment courses. Other adverse events were generally minor in nature and did not necessitate withdrawal from treatment. In conclusion, this study shows that ondansetron is significantly superior to metoclopramide (each with a single pre-treatment dose of dexamethasone) in the control of emesis over 6 courses of chemotherapy for breast cancer.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1991

A controlled trial of synthetic surfactant in infants weighing 1250 g or more with respiratory distress syndrome. The American Exosurf Neonatal Study Group I, and the Canadian Exosurf Neonatal Study Group.

BACKGROUND: Surfactant-replacement therapy is now recognized as a life-saving and safe intervention in small premature infants, but there is little evidence concerning its risks and benefits in larger premature infants. METHODS: We conducted a placebo-controlled, blinded trial in 1237 infants with respiratory distress who were enrolled at 23 hospitals in the United States and 13 hospitals in Canada. At entry all the infants weighed at least 1250 g, were receiving mechanical ventilation, and had a ratio of arterial to alveolar oxygen tension below 0.22. The initial dose of either the synthetic surfactant (Exosurf, 5 ml per kilogram of body weight) or air (the placebo) was administered less than 24 hours after birth, with a second dose given 12 hours later. A total of 614 infants were assigned to receive surfactant, and 623 to receive placebo. RESULTS: Fewer infants in the surfactant group than in the placebo group died before 28 days of age or survived at 28 days with bronchopulmonary dysplasia (7 percent vs. 12 percent, P = 0.002). In the first 28 days of life, there were fewer deaths due to respiratory distress syndrome in the surfactant group (1 percent vs. 3 percent, P = 0.043), lower overall neonatal mortality (4 percent vs. 7 percent, P = 0.04), and a lower incidence of bronchopulmonary dysplasia (3 percent vs. 6 percent, P = 0.008). There was also a significantly lower incidence of pulmonary air leaks, intraventricular hemorrhage, patent ductus arteriosus, seizures, hypotension, and pulmonary hypertension in the surfactant group. The infants treated with surfactant were weaned from oxygen and mechanical ventilation significantly sooner than those given placebo, and they less often required high-frequency ventilation or extracorporeal membrane oxygenation. The primary side effect observed more frequently among the infants who received surfactant treatment was pulmonary hemorrhage (six infants vs. one infant, P = 0.055). CONCLUSIONS: In infants weighing at least 1250 g at birth who have respiratory distress syndrome, treatment with two doses of synthetic surfactant improves survival and reduces perinatal morbidity.

Birth Weight↗
PubMed1991

Covalent coupling of doxorubicin in protein microspheres is a major determinant of tumour drug disposition.

Doxorubicin is shown to be present in albumin microspheres (10-40 microns) in two forms: the native drug and a fraction of drug covalently coupled to the protein matrix probably via glutaraldehyde. Upon trypsin digestion the fraction covalently coupled is released and can be resolved from native doxorubicin by high performance liquid chromatography and quantitated either by using 14C-labelled doxorubicin or by measuring the absorption of the doxorubicin chromophore at 480 nm. Albumin microspheres contained 6.9 micrograms/mg protein covalently bound drug versus 11.1 micrograms/mg native drug when 1% glutaraldehyde was used in microsphere preparation. The covalently bound fraction increased significantly with 2% glutaraldehyde. Albumin/polyaspartic acid microspheres lacked a covalently bound fraction when prepared under the same conditions as pure albumin microspheres (35 micrograms/mg native drug, 1% glutaraldehyde) but transferrin microspheres contained similar amounts of bound and native albumin. In vivo, albumin microspheres altered the disposition of doxorubicin in a rat mammary carcinoma (Sp107) compared to albumin/polyaspartic acid microspheres by reducing the rate of parent drug elimination from the tumour and by reducing its biotransformation to 7-deoxyaglycone metabolites. These data indicate that covalent coupling is a key component in the way doxorubicin is handled in tumours after administration of protein microspheres.

Albumins↗
PubMed1991

Development of respiratory chemoreflexes in response to alternations of fractional inspired oxygen in the newborn infant.

1. We studied the reflex respiratory response to breath-by-breath alternations of fractional inspired oxygen (FI,O2) in full-term human infants delivered either vaginally or by caesarian section at 3-10 h (n = 6), 12-24 h (n = 12), 24-48 h (n = 18), 3-4 days (n = 21) and 5-8 days (n = 7) postnatally. 2. Respiration was measured by inductance plethysmography (Respitrace) and respiratory variables for each breath were calculated on-line by a microcomputer. Test runs (with alternations of FI,O2 between 0.21 and 0.16) and control runs (with an FI,O2 of 0.21) of 50-100 breaths were carried out during quiet sleep. For each respiratory variable the magnitude of the reflex breath-by-breath alternation was compared between control and test runs. 3. There was little respiratory response during control runs at any postnatal age. However, there was a significantly greater response to test runs in all infants studied and at all ages. 4. There were no significant differences in the degree of alternation during test runs between infants of similar postnatal ages delivered by caesarean section and those born vaginally. 5. In all infants the magnitude of the respiratory response increased with postnatal age, presumably reflecting postnatal increases in the hypoxic sensitivity of the peripheral arterial chemoreceptors. 6. The results indicate that in human infants the alternate breath method can be used to detect developmental changes in peripheral chemoreflexes between birth and postnatal day 8.

Cesarean Section↗
PubMed1991

Global and depth resolved phosphorus magnetic resonance spectroscopy to predict outcome after birth asphyxia.

Twelve normal and 32 asphyxiated neonates were studied using global and depth resolved phosphorus magnetic resonance spectroscopy (31PMRS). Eight of the asphyxiated group died or survived with major neurodevelopmental abnormalities. A global phosphocreatinine/inorganic phosphate (PCr/Pi) ratio below the range of values from normal infants predicted adverse outcome after asphyxia with a positive predictive value of 64%, sensitivity 88%, and specificity 83%. Corresponding values for global inorganic orthophosphate/adenosine triphosphate (Pi/ATP) ratios were positive predictive value 88%, sensitivity 96%, and specificity 88%. Spatially localised MRS data, obtained using phase modulated rotating frame imaging, showed cerebral energy metabolism to be more abnormal in deep than superficial regions after birth asphyxia. However, in this population of full term infants none of the regional metabolite concentrations were superior to global data for prediction of outcome.

Adenosine Triphosphate↗
PubMed1990

Forecasting change.

Planning the use of resources is central to the NHS reforms. In the first of a series on forecasting the impact of change on the health service Dr Roger Beech, Jayne Thompson and John Smyth examine the use of computer modelling.

Computer Simulation↗
PubMed1990

Linkage disequilibrium between DNA polymorphisms within the porphobilinogen deaminase gene.

Three restriction fragment length polymorphisms (RFLPs) (MspI, PstI, ScrFI/BstNI) within the human porphobilinogen deaminase (PBG-D) gene have been studied in 47 unrelated patients with the autosomal dominant disorder, acute intermittent porphyria (AIP), and in 92 control subjects. Each enzyme identified a two-allele polymorphism with allele frequencies close to 0.50: however, marked linkage disequilibrium limited the number of observed haplotypes to four, of which one is uncommon. No association was detected between any haplotype and AIP.

Acute Disease↗
PubMed1989

Increased compliance in response to salbutamol in premature infants with developing bronchopulmonary dysplasia.

We compared the effect of salbutamol and placebo in a double-blind study of preterm infants with bronchopulmonary dysplasia, using a randomized, crossover design with several replicates per subject. Sixty-two tests were performed on 20 ventilator-dependent infants weighing less than 1500 gm. Patients were entered as early as the first week of life and studied for at least 4 weeks or until extubation. Each subject was his own control subject and was randomly assigned to a placebo-salbutamol or salbutamol-placebo sequence administered on 2 consecutive days of each week. Static compliance, expiratory resistance of the respiratory system, and changes in transcutaneous oxygen and carbon dioxide tension were measured. Static compliance improved by 0.240 ml/cm H2O/kg (35.3%) after salbutamol and by 0.010 ml/cm H2O/kg (2.8%) after placebo (p less than 0.0001). The presence of a predetermined decrease in carbon dioxide tension correlated with large changes in static compliance per kilogram and with the need for a high level of fractional inspired oxygen. The magnitude of the clinical and physiologic improvement observed, and the early response suggest that long-term bronchodilator therapy starting as early as the second week of life may be beneficial for very low birth weight infants with early bronchopulmonary dysplasia.

Albuterol↗
PubMed1987

The EORTC Early Clinical Trials Cooperative Group experience with 5-aza-2'-deoxycytidine (NSC 127716) in patients with colo-rectal, head and neck, renal carcinomas and malignant melanomas.

The Early Clinical Trials Cooperative Group of the EORTC conducted several phase II studies with a pyrimidine analogue of deoxycytidine, 5-aza-2'-deoxycytidine (DAC). The drug was given as three consecutive 1 h i.v. infusions of 75 mg/m2, separated by intervals of 7 h; courses were repeated every 5 weeks. A total of 101 eligible patients were studied: 42 with colo-rectal adenocarcinoma, 27 with squamous cell carcinoma of the head and neck, 18 with malignant melanoma and 14 with renal cell carcinoma. Drug-induced toxicities consisted of moderate myelosuppression, and nausea and vomiting. One single partial remission was seen in a patient with malignant melanoma. DAC given in this dose and schedule is devoid of antitumour activity in adult patients with these refractory types of carcinomas.

Adenocarcinoma↗