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Biomedical subjects

P Hall

Publications and source records attributed to P Hall.

At least 73 records · Page 4Linked to original sources
PubMed1998

Radiation-associated thyroid cancer--facts and fiction.

Thyroid cancer is a rare and complex disease and the thyroid contains various cell types from which specific diseases arise. The malignancies range from indolent to extremely aggressive. Several risk factors for thyroid cancers have been suggested, but only ionizing radiation has been found to have a causative effect. With the exception of tobacco, ionizing radiation is probably the most studied carcinogen there is. It is not yet possible to determine whether or not a specific cancer was induced by radiation and epidemiological studies therefore provide the primary data on cancer risk in man after exposure to ionizing radiation. The current epidemiological knowledge on radiation-associated thyroid cancer is reviewed, focusing on the sharply increased risks recently found among children in the Chernobyl area.

Adult↗
PubMed1998

Acute ischemic stroke.

To optimize the recovery outcome of those with acute ischemic stroke, several steps need to be taken and strengthened by the public and medical personnel. These include immediate identification of stroke symptoms and appropriate actions, quick access to EMS, rapid EMS response, treatment and evacuation, early communication to the medical facility, rapid diagnosis and interventions, specialized treatment, evaluation of complications, precipitating and accompanying factors, and appropriate rehabilitation when applicable.

Acute Disease↗
PubMed1998

Validation of several methods of estimating maximal oxygen uptake in young men.

The purpose of this study was to identify the most accurate predictor of VO2max from a variety of running tests. 32 young adult male undergraduates of (mean +/- SE) age 20.14 +/- 0.34 yr., height 179.4 +/- 1.8 cm, weight 73.7 +/- 2.8 kg, and VO2max 57.89 +/- 1.1 ml.kg-1.min.-1 were randomly tested on four different predictive VO2max running tests to assess their actual VO2max, based on a continuous, progressive treadmill protocol and obtained via gas analysis. The four tests consisted of a treadmill jogging test, 1.5 mile run, Cooper's 12-min. run, and the 20-m progressive shuttle-run test. An analysis of variance applied to means indicated significance. Post hoc analysis between the means with correction by Scheffé showed significant difference between the predictive submaximal treadmill jogging test and the 12-min. run but no other differences. The strength of the relationship between predictive tests and VO2max varied, with the 12-min. run having the highest correlation of .87, followed by the 1.5 mile run .87, 20-m progressive shuttle run .82, and the treadmill jogging test .50. The 12-min. run had the highest correlation of all tests with VO2max in young men, with active to trained levels of fitness. The 1.5 mile and 20-m shuttle run also provided accurate predictions of VO2max and so should be used for an accurate prediction of young men's VO2max.

Adult↗
PubMed1997

Risk of second malignant neoplasms among long-term survivors of testicular cancer.

BACKGROUND: We have quantified the site-specific risk of second malignant neoplasms among nearly 29,000 survivors (> or = 1 year) of testicular cancer, taking into account the histologic type of initial cancer and the primary therapy used to treat it. METHODS: The study cohort consisted of 28,843 men identified within 16 population-based tumor registries in North America and Europe; over 3300 men had survived more than 20 years. New invasive cancers were identified through a search of registry files. RESULTS: Second cancers were reported in 1406 men (observed-to-expected ratio [O/E] = 1.43; 95% confidence interval = 1.36-1.51), with statistically significant excesses noted for acute lymphoblastic leukemia (O/E = 5.20), acute nonlymphocytic leukemia (O/E = 3.07), melanoma (O/E = 1.69), non-Hodgkin's lymphoma (O/E = 1.88), and cancers of the stomach (O/E = 1.95), colon (O/E = 1.27), rectum (O/E = 1.41), pancreas (O/E = 2.21), prostate (O/E = 1.26), kidney (O/E = 1.50), bladder (O/E = 2.02), thyroid (O/E = 2.92), and connective tissue (O/E = 3.16). Overall risk was similar after seminomas (O/E = 1.42) or nonseminomatous tumors (O/E = 1.50). Risk of solid tumors increased with time since the diagnosis of testicular cancer, yielding an O/E = 1.54 (O = 369) among 20-year survivors (two-sided P for trend = .00002). Secondary leukemia was associated with both radiotherapy and chemotherapy, whereas excess cancers of the stomach, bladder, and, possibly, pancreas were associated mainly with radiotherapy. CONCLUSIONS: Men with testicular cancer continue to be at significantly elevated risk of second malignant neoplasms for more than two decades following initial diagnosis. Patterns of excess second cancers suggest that many factors may be involved, although the precise roles of treatment, natural history, diagnostic surveillance, and other influences are yet to be clarified.

Antineoplastic Agents↗
PubMed1997

Results of a consecutive series of patients receiving only antiplatelet therapy after optimized stent implantation. Comparison of aspirin alone versus combined ticlopidine and aspirin therapy.

BACKGROUND: Previous studies have shown that stents can be inserted in coronary arteries of patients who are subsequently treated safely with antiplatelet therapy only (ticlopidine and/or aspirin) with a low incidence of stent thrombosis, provided that stent expansion is adequate and there are no other flow-limiting lesions present. However, it is unknown whether ticlopidine combined with aspirin is superior to aspirin alone in preventing stent thrombosis. METHODS AND RESULTS: From March 1993 through July 1995, 801 consecutive patients assigned to receive either aspirin therapy alone (ASA, 264 patients, 348 lesions) or a combination of ticlopidine and aspirin (TIC-ASA, 537 patients, 737 lesions) after a successful stent insertion, in most accomplished with intravascular ultrasound guidance, were evaluated retrospectively. At 1 month, there was no difference in the ASA group compared with the TIC-ASA group in the rate of any stent thrombosis (1.9% versus 1.9%; P = 1), subacute stent thrombosis (1.9% versus 1.3%; P = .5), cumulative major adverse clinical events (1.9% versus 2.0%; P = 1), and peripheral vascular complications (0.5% versus 0.2%; P = .3). Medication side effects that required termination of antiplatelet therapy occurred only in 1.9% of patients in the TIC-ASA group (P = .04). CONCLUSIONS: At 1-month clinical follow-up, stent thrombosis and other adverse clinical outcomes were not significantly different between the ASA and TIC-ASA groups. Medication side effects occurred only in patients treated with ticlopidine. These results provide further evidence of the safety of treatment with antiplatelet therapy only after optimal stent implantation and support the efficacy of aspirin alone in preventing stent thrombosis.

Angioplasty, Balloon↗
PubMed1997

Introductory study of the once-a-month, injectable contraceptive Cyclofem in Brazil, Chile, Colombia, and Peru.

An introductory trial with the injectable contraceptive Cyclofem was carried out in Brazil, Chile, Colombia, and Peru, with participation by 3,183 women. Women were followed-up for up to 2 years of use and the data were evaluated by life table analysis. A total of 29,676 women-months were accumulated for up to 2 years. No pregnancies were observed in the 2 years. The discontinuation rates for amenorrhea in the first year ranged from 3.4 in Brazil to 8.1 in Colombia, and for menstrual disturbances from 5.1 in Chile to 9.2 in Brazil. The discontinuation rates for other medical reasons ranged from 7.8 in Brazil to 26.3 in Colombia, and for personal reasons from 17.2 in Chile to 23.5 in Brazil. Continuation rates ranged from 42.3 in Colombia to 52 in Chile. In the second year of observation the rates of discontinuation were lower than those observed in the first year, with the exception of personal reasons in Brazil, which were the same as those observed in the first year. Continuation rates ranged from 19.4 in Brazil to 36.8 in Chile. The comparison of reasons for discontinuation in selected clinics showed that the rate for amenorrhea in one clinic in Chile was more than three times that in others and in Peru was seven times more in one clinic than in another. Regarding menstrual disturbances, in Peru one clinic presented a rate three times higher than the others. The main reasons for discontinuation due to other medical reasons were headache and weight gain. In conclusion, Cyclofem presented a high contraceptive efficacy and an acceptable rate of continuation and discontinuation for up to 2 years in the four countries.

Adult↗
PubMed1997

Ricin fusion toxin targeted to the human granulocyte-macrophage colony stimulating factor receptor is selectively toxic to acute myeloid leukemia cells.

Treatment failure of patients with acute myelogenous leukemia (AML) is frequently due to the development of multidrug resistance phenotype blasts. We have expressed a fusion protein consisting of human granulocyte-macrophage colony stimulating factor (GMCSF) fused to the N-terminus of a lectin-deficient ricin toxin B chain (RTB) in Spodoptera frugiperda insect cells. The fusion protein was purified by immunoaffinity chromatography and reassociated with chemically deglycosylated ricin toxin A chain (RTA). The resulting fusion toxin was found to react with antibodies to GMCSF, RTB and RTA and had the predicted molecular mass of 80 kDa. GMCSF-ricin bound poorly to asialofetuin (Kd = 10(6) M-1) and receptor negative cells indicating loss of lectin activity, but bound strongly to GMCSF receptor positive HL60 cells. Ligand displacement assays showed fusion toxin affinity 2.6-fold less than native GMCSF. Selective inhibition of protein synthesis was observed on receptor positive cells. Induction of apoptosis was also observed on receptor positive cells. Cells expressing multidrug resistance gene products (P-gp, Bcl2 and BclXL) were also sensitive to fusion toxin. These results suggest that GMCSF-ricin deserves further preclinical development.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

High pressure assisted coronary stent implantation accomplished without intravascular ultrasound guidance and subsequent anticoagulation.

OBJECTIVES: The purpose of this study was to determine the efficacy of treatment with antiplatelet therapy and no anticoagulation after high pressure assisted coronary stent implantation performed without intravascular ultrasound (IVUS) guidance. BACKGROUND: Previous studies have shown that during IVUS-guided Palmaz-Schatz coronary stenting, it is safe to withhold anticoagulation when stent expansion has been optimized by high pressure balloon dilation. METHODS: Patients that had successful coronary stenting without IVUS guidance were treated with ticlopidine, 500 mg/day, and aspirin, 325 mg/day, for 1 month and then received only aspirin, 325 mg/day, indefinitely. Patients were not treated with warfarin (Coumadin) or heparin after successful stenting. Clinical and angiographic events were assessed at 1 month. RESULTS: A total of 201 intracoronary stents were implanted in 127 patients with 137 lesions. The average number of stents per lesion was 1.4 +/- 0.8, and the average number of stents per patient was 1.6 +/- 1.1. Stent deployment was performed for elective indications in 79% of procedures and for emergency indications in 21%. There were four stent thrombosis events for a per patient event rate of 3.1% and a per lesion event rate of 2.9%. CONCLUSIONS: After high pressure assisted stenting performed without IVUS guidance, there was an acceptable incidence of 3.1% of stent thrombosis with the combination of short-term ticlopidine and aspirin therapy and no anticoagulation. Although the study involved only 127 patients, the results support the relative safety of stenting without IVUS guidance and with antiplatelet therapy only in comparison to historical trials on stenting performed with postprocedure anticoagulation.

Anticoagulants↗
PubMed1997

Potential for hostility and faking-good in high-hostile men.

We investigated if Type A Structured Interview (SI)-assessed hostility (PoHo) is subject to voluntary underreporting, or faking-good, by hostile subjects. Sixteen men who previously scored above the clinical cutoff of 3 on SI hostility were randomly assigned to an experimental (N = 8) or control (N = 8) group. Both groups underwent a second videotaped SI, prior to which experimental subjects were asked to present themselves in a favorable light. Repeated-measures ANOVA revealed that experimental subjects were able successfully to decrease their global PoHo scores when instructed to do so (38% scored below the clinical cutoff score). The SI-derived hostility score is vulnerable to faking-good, and attention should be paid to both the motivational set of subjects and the instructions given prior to the SI.

Adult↗
PubMed1997

Late consequences of radioiodine for diagnosis and therapy in Sweden.

With the exception of tobacco, ionizing radiation is probably the most studied carcinogen; however, it is not yet possible to determine whether a specific cancer was induced by radiation. Epidemiologic studies provide the primary data on cancer risk in humans after exposure to ionizing radiation. The present paper reviews the current epidemiologic knowledge on radiation-induced cancer, focusing on exposure to radioiodines, and describes the latest findings from the Swedish iodine cohorts.

Cohort Studies↗
PubMed1997

Reconstruction of vascular networks using three-dimensional models.

Reconstructing vasculature in three dimensions is a challenging problem. Early approaches concentrated on coronary vasculature in X-ray images, recent work uses magnetic resonance imagery of cerebral vasculature. In both cases a priori information has been used, and often the way this is represented has proven limiting to the scope of applications supported. For example, a particular representation may be useful only for X-ray images. This paper addresses two issues: 1) representing a collection of vasculature and 2) the reconstruction of individual vasculature from images. Our representation learns the variations in branching structures and vessel shapes that occur between individuals. It supports a vascular catalogue containing three-dimensional (3-D) anatomical models. The representation is task independent; here we use it to reconstruct vasculature from images. Our algorithm has four features to which we draw attention: 1) it is not premised wholly upon X-ray images (though that is our focus here); 2) it produces several feasible solutions rather than one; 3) it can generalize from the catalogue to reconstruct instances not yet learned; 4) it exhibits polynomial time complexity, reasonable memory consumption, and is reliable. Both our representation and reconstruction algorithm are new and useful approaches. In support of these claims, we present results gathered from X-rays of both simulated and real vasculature.

Algorithms↗
PubMed1997

Intracoronary stent implantation in native coronary arteries and saphenous vein grafts: a consecutive experience with six types of stents without prolonged anticoagulation.

OBJECTIVE: To analyze the results of implantation of six different intracoronary stents without the use of prolonged anticoagulation. MATERIAL AND METHODS: Between Mar. 30, 1993, and Jun. 30, 1995, 889 patients with 1,194 coronary or vein graft lesions underwent implantation of one of six types of stents-Palmaz-Schatz, Gianturco-Roubin, Wiktor, Micro, Cordis, or Wallstent. The patients were classified into seven groups on the basis of the type of stent that was implanted, including one group with combined use of two or more types of stents. Among the 851 patients with successful stent delivery and without major complications, 801 received only antiplatelet therapy, and 50 received a standard anticoagulation regimen. One-month clinical followup data were obtained in all patients, and clinical events were investigated. RESULTS: The mean number of stents was 1.8 per lesion and 2.4 per patient. Procedural success was achieved in 93% of the lesions. The clinical success rate at 1 month was 90%. Intravascular ultrasound assessment was performed in 90% of the lesions. The final minimal luminal cross-sectional area of the stent increased from 6.8 to 7.8 mm2 after intravascular ultrasound-guided optimization. Within 1 month, 16 stent thrombosis events (1.9%) occurred. No significant differences were noted in stent thrombosis rates among the various stent cohorts. Multivariate logistic regression analysis revealed that the final stent minimal luminal diameter measured by intravascular ultrasonography was the only variable associated with stent thrombosis. CONCLUSION: This study showed that six different stents could possibly be inserted without subsequent anticoagulation if optimal stent expansion and total lesion coverage were achieved.

Anticoagulants↗
PubMed1997

The SCID-D diagnostic interview and treatment planning in dissociative disorders.

With the development of reliable diagnostic tools for the dissociative disorders, earlier implementation of appropriate therapy is now possible. The Structured Clinical Interview for DSM-IV Dissociative Disorders-Revised (SCID-D) (Steinberg, 1994b), an extensively field-tested semistructured interview, can assist clinicians with treatment planning as well as diagnosis. This article discusses the diagnostic interview process, the importance of feedback interviews, specific questions regarding consultation and referral, and the use of hypnosis. The final section correlates the five dissociative symptoms assessed by the SCID-D with different phases of treatment planning.

Dissociative Disorders↗
PubMed1997

The strategic approach to contraceptive introduction.

The introduction of new contraceptive technologies has great potential for expanding contraceptive choice, but in practice, benefits have not always materialized as new methods have been added to public-sector programs. In response to lessons from the past, the UNDP/UNFPA/WHO/World Bank Special Programme of Research, Development, and Research Training in Human Reproduction (HRP) has taken major steps to develop a new approach and to support governments interested in its implementation. After reviewing previous experience with contraceptive introduction, the article outlines the strategic approach and discusses lessons from eight countries. This new approach shifts attention from promotion of a particular technology to an emphasis on the method mix, the capacity to provide services with quality of care, reproductive choice, and users' perspectives and needs. It also suggests that technology choice should be undertaken through a participatory process that begins with an assessment of the need for contraceptive introduction and is followed by research and policy and program development. Initial results from Bolivia, Brazil, Burkina Faso, Chile, Myanmar, South Africa, Vietnam, and Zambia confirm the value of the new approach.

Africa↗