Search PubMed⌕ Search

Biomedical subjects

P Band

Publications and source records attributed to P Band.

At least 19 recordsLinked to original sources
PubMed2000

Visualizing the function computed by a feedforward neural network.

A method for visualizing the function computed by a feedforward neural network is presented. It is most suitable for models with continuous inputs and a small number of outputs, where the output function is reasonably smooth, as in regression and probabilistic classification tasks. The visualization makes readily apparent the effects of each input and the way in which the functions deviate from a linear function. The visualization can also assist in identifying interactions in the fitted model. The method uses only the input-output relationship and thus can be applied to any predictive statistical model, including bagged and committee models, which are otherwise difficult to interpret. The visualization method is demonstrated on a neural network model of how the risk of lung cancer is affected by smoking and drinking.

Alcohol Drinking↗
PubMed1999

Local tumor recurrence or emergence of a new primary lesion? A molecular analysis.

The distinction between a new primary oral tumor and recurrence may bear significant prognostic implications. Currently, this differentiation relies mainly on tumor location: when both lesions are at or near the same site, the new one is regarded as a recurrence; when the two are at different sites, the second lesion is regarded as a new primary. Recent investigations using molecular analysis have demonstrated that some oral squamous cell carcinomas (SCC) arising from different sites show the same clonogenical changes. In this case report, we studied the clonality of three SCC (one primary, two apparent recurrences) from the right lateral tongue of a young, non-smoking woman by using microsatellite analysis for loss of heterozygosity. The results showed that while the first two tumors were clonogenically similar, the third tumor was clonogenically different and was consistent with the development of a new primary. This result indicates that location of tumors alone is not always reliable in determining whether a new tumor is a recurrence or a new primary lesion.

Adult↗
PubMed1998

Industrial hygiene aspects of a sampling survey at a bleached-kraft pulp mill in British Columbia.

To validate exposure estimates used to investigate correlations between exposure and cancer risk, 1678 personal measurements were collected for 46 job titles during 73 day shifts at a bleached-kraft pulp mill. Measurements included shift-long average and short-term exposures to carbon monoxide, chlorine dioxide (ClO2), and hydrogen sulfide; and shift-long average exposures to calcium oxide and wood dust (WD). Overall results indicate low levels of exposure with a few noteworthy exceptions. Although ClO2 was the exclusive bleaching agent, 77 area samples indicated that chlorine (Cl2), not ClO2 was present in all areas apart from the chemical preparation area (chem-prep) and during a pulp spill. The highest shift-long exposures to Cl2 were measured in the chip yard and are attributed to uncontrolled stack emissions. Finally, WD samples collected from several laborers significantly exceeded regulatory limits, with the highest exposures measured in the steam and recovery area. For short-term exposures to ClO2 in chem-prep, 12 of 17 data-logging electro-chemical sensor sample results showed at least one peak that exceeded the short-term exposure limit of 0.3 ppm. The use of data-logging equipment quantified short-term exposures that previously had been characterized only anecdotally. The peaks were correlated with tasks and upset conditions and, given their transient nature, these exceedances could not have been detected using shift-long average-based sampling devices. Since the respiratory effects of significant short-term exposures to irritant gases such as Cl2 and ClO2 are well-documented, data-logging instruments are necessary to characterize exposures in the pulp and paper industry.

Air Pollutants, Occupational↗
PubMed1998

Long term disability rates in a cohort of Air Canada pilots.

Causes of long term disability (LTD) were collected between January 1, 1981 and December 31, 1990 among all active pilots in a cohort of Air Canada pilots. During this 10-yr period, 474 (20.9%) of the 2271 pilots had LTD; there were 1107 cases of LTD corresponding to a total duration of leave of absence of 4161 mo. Frequencies of the main diagnostic categories were: injuries: 249 (22.5%); mental disorders: 175 (15.8%); circulatory system: 157 (14.2%); digestive system: 128 (11.6%); and musculoskeletal system: 121 (10.9%). LTD rates increased with age, ranging from 1.86-9.22 per 1000 pilots per year from the younger (20-29 yr) to the older age group (50-59 yr), respectively. Several causes of LTD could be potentially preventable, in particular injuries which accounted for 63.6% of all causes in the younger age group and remained a significant condition at subsequent ages.

Absenteeism↗
PubMed1993

Small bowel cancer in western Canada.

Based on incident cases of small intestinal cancers in the four western Canadian provinces reported in the population-based cancer registries of British Columbia, Alberta, Saskatchewan and Manitoba we evaluated the descriptive epidemiological characteristics such as age, sex and subsite distribution of adenocarcinomas, carcinoids, lymphomas and sarcomas for the period 1975-1989. The distribution of adenocarcinomas, carcinoids and lymphomas presented a clear trend along the length of the small bowel. Most of the adenocarcinomas (54.7%) occurred in the duodenum and their relative frequency decreased in aboral direction: 29.9% in the jejunum and 16.0% in the ileum. The carcinoids showed an opposite trend, an increasing relative frequency in aboral direction: 3.9% in the duodenum, 9.2% in the jejunum and 86.7% in the ileum. Lymphomas were more frequent in the ileum (49.5%) compared to jejunum (29.4%) and duodenum (21.0%). Most sarcomas occurred along the jejunum (46.7%). The mean and median ages of lymphoma and sarcoma patients were significantly lower compared to adenocarcinoma and carcinoid cases. There was no difference in mean and median age by gender in the adenocarcinoma and carcinoid categories, but in the lymphoma and sarcoma groups males were significantly younger than females.

Adenocarcinoma↗
PubMed1992

Lung cancer following Hodgkin's disease: a case-control study.

It is recognized that survivors of Hodgkin's disease are at a substantially increased risk of lung cancer. A collaborative group of population-based cancer registries and major treatment centers carried out a case-control study, in which 98 cases of lung cancer were identified in patients who had survived at least 1 year following a diagnosis of Hodgkin's disease. A total of 259 matched controls were selected from patients with Hodgkin's disease who did not develop subsequent lung cancer, and for both cases and controls detailed information was abstracted from medical records concerning stage and treatment of Hodgkin's disease. Patients treated with chemotherapy alone had about twice the risk of developing lung cancer than those treated by radiotherapy alone or both modalities. There was no increase in risk with cumulative number of cycles of chemotherapy. Among patients treated with radiotherapy alone, there was an increase in risk related to estimated radiation dose to the lung. There was also a strong association between cigarette smoking and the risk of lung cancer. The finding of a higher risk following chemotherapy than following radiotherapy was unexpected, but could not be explained by any identified methodological flaws. A plausible inference from the study is that all forms of Hodgkin's disease therapy are carcinogenic to the lung and that, in particular, chemotherapy is associated with an increase in risk which is at least comparable to and perhaps higher than the risk produced by radiotherapy.

Antineoplastic Agents↗
PubMed1991

Radon exposure, cigarette smoking, and other mining experience in the beaverlodge uranium miners cohort.

A nested case-control study within the Beaverlodge Uranium Miners Cohort was undertaken to assess any possible contribution of confounding by smoking and other mining experience to the risk estimate derived from the original cohort study. Next of kin have been interviewed for 46 lung cancer cases and 95 controls enrolled in the Beaverlodge Uranium Miners Cohort Study who died between 1950 and 1980. Confounding by cigarette smoking and other mining experience appears unlikely to have contributed to the relative risk coefficient for exposure to Rn decay products derived in the parent study. Data for smoking and exposure to Rn decay products are consistent with a multiplicative model, although considerable caution must be applied to this interpretation.

Case-Control Studies↗
PubMed1990

Leukemia following Hodgkin's disease.

To investigate the effect of different treatments for Hodgkin's disease on the risk of leukemia, we used an international collaborative group of cancer registries and hospitals to perform a case-control study of 163 cases of leukemia following treatment for Hodgkin's disease. For each case patient with leukemia, three matched controls were chosen who had been treated for Hodgkin's disease but in whom leukemia did not develop. The use of chemotherapy alone to treat Hodgkin's disease was associated with a relative risk of leukemia of 9.0 (95 percent confidence interval, 4.1 to 20) as compared with the use of radiotherapy alone. Patients treated with both had a relative risk of 7.7 (95 percent confidence interval, 3.9 to 15). After treatment with more than six cycles of combinations including procarbazine and mechlorethamine, the risk of leukemia was 14-fold higher than after radiotherapy alone. The use of radiotherapy in combination with chemotherapy did not increase the risk of leukemia above that produced by the use of chemotherapy alone, but there was a dose-related increase in the risk of leukemia in patients who received radiotherapy alone. The peak in the risk of leukemia came about five years after chemotherapy began, and a large excess persisted for at least eight years after it ended. After adjusting for drug regimen, we found that patients who had undergone splenectomy had at least double the risk of leukemia of patients who had not, and an advanced stage of Hodgkin's disease carried a somewhat higher risk of leukemia than Stage I disease. We conclude that chemotherapy for Hodgkin's disease greatly increases the risk of leukemia and that this increased risk appears to be dose-related and unaffected by concomitant radiotherapy. In addition, the risk is greater for patients with more advanced stages of Hodgkin's disease and for those who undergo splenectomy.

Antineoplastic Agents↗
PubMed1987

Second malignancies following testicular cancer, ovarian cancer and Hodgkin's disease: an international collaborative study among cancer registries.

Eleven population-based cancer registries tabulated second cancers among 133,411 patients diagnosed with testicular cancer, ovarian cancer or Hodgkin's disease between 1945 and 1984. Overall, 3,157 second cancers were observed, as compared with 2,420 expected at least one year after the first cancer. Survivors of testicular and ovarian cancer experienced 30% and 20% more cancers respectively than the general population comparison group, and patients previously diagnosed with Hodgkin's disease had an 80% excess of cancer. No information was available either on treatment for the first cancer, or other risk factors. However, temporal patterns in the risk of specific second cancers were analysed, with particular reference to the possible role of therapy for the first cancer. Leukaemia of the acute or non-lymphatic type, which has been previously linked to alkylating agent therapy, occurred in excess following all 3 first cancers, as did non-Hodgkin's lymphoma (overall relative risks of 6.1 and 1.8 respectively, with considerably higher relative risks following Hodgkin's disease). Other cancers for which important and plausibly therapy-induced excesses occurred were lung cancer following Hodgkin's disease (relative risk 1.9), breast cancer following Hodgkin's disease (relative risk 1.4) and bladder cancer following ovarian cancer and Hodgkin's disease (relative risks 1.7 and 2.2 in women, respectively). Rarer sites at which striking excesses occurred were the salivary gland, thyroid, bone and connective tissue. There were smaller, but clear excesses for cancers of the rectum and colon following ovarian cancer and testicular cancer, skin cancer following Hodgkin's disease, and kidney cancer following ovarian cancer. Overdiagnosis, misclassification of metastases and confounding by other risk factors were all considered as explanations of observed excesses. Nonetheless, it appeared that there are clear excess risks for cancers other than acute leukaemia which must be ascribed to therapy for the first cancer, especially in view of the possible under-reporting in registry material. Case-control studies are under way to provide information on the role of specific aspects of therapy.

Breast Neoplasms↗
PubMed1987

Phase II study of lonidamine in patients with small cell carcinoma of the lung.

Lonidamine, a substituted indazole carboxylic acid that inhibits cellular respiration, was given in an escalating oral schedule to 20 evaluable patients with measurable extensive small cell carcinoma of the lung. Two partial responses occurred. Reversible acceptable toxicity included myalgia, nausea, hyperesthesia, photophobia, somnolence, and testicular pain. The drug was not myelosuppressive. Lonidamine has modest activity in small cell lung cancer and further studies are warranted.

Adult↗
PubMed1986

Alternating chemotherapy and thoracic radiotherapy with concurrent cisplatin-etoposide for limited-stage small-cell carcinoma of the lung.

Seventy patients with limited-stage small-cell lung cancer (SCLC) were given six courses of chemotherapy alternating two drug combinations: a combination of cyclophosphamide, doxorubicin (Adriamycin [Adria Laboratories, Columbus OH]) and vincristine (CAV) was alternated with cisplatin and etoposide at 3-week intervals. Thoracic radiotherapy was administered concurrently with the first cisplatin-etoposide chemotherapy. Prophylactic cranial irradiation (PCI) was administered after the completion of all chemotherapy. No maintenance treatment was used. Seventy-six percent of patients achieved a complete clinical response. The median survival was 78 weeks and the 2-year survival rate was 32% with an average follow-up of 3 1/2 years. Seventeen percent are currently alive and disease free. Cisplatin and etoposide can be administered concurrently with thoracic irradiation with acceptable toxicity. Our results justify further clinical research using alternating chemotherapy and concurrent thoracic irradiation and cisplatin-etoposide chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1985

Single-dose pharmacokinetic study of 13-cis-retinoic acid in man.

A pharmacokinetic study of 13-cis-retinoic acid was performed in nine patients following administration of a single oral dose of 80 mg. An average lag time of 1.2 hours was observed, followed by fast absorption, with a mean half-life of 0.5 hour. Peak plasmatic concentration of 733 ng/ml occurred at 2.3 hours. The disposition profile showed a rapid distribution half-life of 1.3 hours and a terminal elimination half-life of 24.7 hours. No 13-cis-retinoic acid was detected unchanged in urine. An important interpatient variability was noted.

Administration, Oral↗
PubMed1984

Hormones as cancer growth factors.

It is postulated that some hormones may regulate proliferation of cancer cells in the same way as growth factors produced by cellular oncogenes. The gene coding for the hormone's specific receptor would also act as a cellular oncogene. Normal adult breast cells show few if any oestrogen receptors. In the model put forward the oestrogen receptors in breast cancer cells should not be regarded as a marker of differentiation but as a survival advantage for the tumour when oestrogens are present. Prolactin and somatomedin may also behave as growth factors. In relation to the antitumour effects of hormone antagonists such as tamoxifen, it is postulated that cancer cells are immortalised and prevented from full differentiation by the presence of growth factors and their receptors. If receptor genes are re-expressed through the process of neoplastic transformation, their presence in cancers from unresponsive normal tissues should be regarded as a common event.

Breast Neoplasms↗