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Biomedical subjects

R Gordon

Publications and source records attributed to R Gordon.

At least 145 records · Page 8Linked to original sources
PubMed1989

A critical review of the physics and statistics of condoms and their role in individual versus societal survival of the AIDS epidemic.

Condom failure rates for HIV are substantially greater than for pregnancy, even for highly motivated people who may reach the limit set by allowed manufacturing imperfections. This makes condoms ineffective for lifelong protection from HIV-infected sexual partners; therefore, in general, condoms provide inadequate risk reduction for the individual. Nevertheless, they are sufficiently effective that if everyone used condoms, the AIDS epidemic would stop. Quantitative public health goals to reduce the "reproductive rate" of HIV from an estimated 4-12 people infected per infected person to below 1 are needed. Government and scientific testing of condoms could be improved statistically and by utilizing relevant physics.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Chemotherapy plus RA233 in the treatment of oat cell lung cancer.

One hundred and one patients with oat (small) cell lung cancer have been treated with CAVE [Cytoxan, Adriamycin, Vincristine, and etoposide (VP-16)] chemotherapy +/- RA233 (a platelet-inhibiting agent). There was no difference in disease-free interval, pattern of relapse, or survival between groups.

Actuarial Analysis↗
PubMed1989

Detection of early breast cancer: an overview and future prospects.

Detection and treatment of breast cancer at an early stage is the only method with proven potential for lowering the death rate from this disease. Detection of early breast cancer is promoted by the American Cancer Society, American College of Radiology, and Canadian Association of Radiologists by encouraging the regular use of three types of screening: breast self-examination, clinical breast examination, and mammography. When all factors are considered, it has been convincingly demonstrated that the potential benefits of mammography far outweigh the minimal, clinically undetected radiation risk incurred by the examination. New technologies, such as computed tomography, magnetic resonance imaging, transillumination diaphanography, ultrasound, thermography, and digital subtraction angiography might offer a wide selection for patient examination. However, none of these procedures, in its present form, is expected to replace mammography as the first-line imaging technique for the detection and diagnosis of benign and malignant breast lesions. Breast cancer is detected now, in most cases, via casual or informed breast self-examination. This first-line of detection is not sufficient, since most tumors may metastasize before they reach a palpable size. Mammography generally shows up tumors no smaller than 1-cm diameter, which in many cases have already metastasized. The more advanced imaging modalities in their current forms suffer from a number of drawbacks that give them a lower overall detection rate than mammography. Understandably, improving breast imaging modalities is a great challenge to diagnostic radiology. The purpose of this article is to provide a comprehensive overview of the detection of early breast cancer. It briefly discusses the understanding of breast cancer, its incidence, and the mortality and survival of patients with breast cancer, as well as screening programs for breast cancer. We review the developments in mammography and other breast imaging modalities over the last several years. Prospects for digital mammography, digital image enhancement, and three-dimensional digital subtraction mammography, which may someday supplant film mammography, are also discussed.

Angiography↗
PubMed1989

Erythema chronicum migrans as the presenting manifestation of juvenile chronic myelocytic leukemia.

We describe the case of a 3-year-old boy who presented with typical clinical features of Lyme disease, including erythema chronicum migrans and arthritis. Over subsequent months, however, the clinical picture evolved into juvenile chronic myelocytic leukemia. To our knowledge, the combination of Lyme disease and juvenile chronic myelocytic leukemia has not been described. Dermatologic and other relevant clinical findings are presented, and the cause and effect relationship between these two rare entities is discussed.

Child, Preschool↗
PubMed1988

Cardiopulmonary effects of celiprolol and bisoprolol in serotonin-infused cats.

The effects of celiprolol and bisoprolol on cardiopulmonary function in serotonin-infused cats were compared. Celiprolol reversed the bronchoconstrictive effect of serotonin at doses greater than or equal to 1.0 mg/kg. Also, decreases in mean arterial pressure and heart rate were noted after administration of 3-10 and 10 mg/kg celiprolol, respectively. In contrast, bisoprolol tended to induce bronchoconstriction. Reductions in mean arterial pressure and heart rate were observed with 1 or 3 mg/kg. Bisoprolol administration at 10 mg/kg was lethal. The unique ability of celiprolol to induce bronchodilation enhances its therapeutic potential.

Animals↗
PubMed1988

Hemostatic effects of hormonal stimulation in patients with metastatic prostate cancer.

Hemostatic abnormalities are common in patients with metastatic malignancy and are attributed, in part, to materials secreted by tumor cells. Tumor stimulation might therefore cause further perturbation of hemostasis. This article reports observations on the effects of androgen stimulation on multiple hemostatic parameters in patients with metastatic prostate cancer. Testosterone was given before chemotherapy in an experimental protocol designed to increase tumor sensitivity to cytotoxic agents. The following parameters were measured on day 0 (before) and days 2 and 4 of fluoxymesterone administration: PT, APTT, platelet count, plasma betathromboglobulin (BTG), platelet factor 4 (PF4), fibrinogen, fibrin(ogen) split products (FSP), factor VIII coagulant activity (VIII C), von Willebrand factor antigen (vWF Ag), fibrinopeptide A (FPA), antithrombin III (AT III), and protein C antigen (PC). Ten patients were studied during 17 cycles of hormonal stimulation. Baseline levels of BTG, PF4, fibrinogen, FSP, factor VIII C, vWF Ag, and FPA were significantly elevated compared with normal control. Although androgen stimulation resulted in elevation of BTG, FPA, and FSP levels by day 4 in many patients, the changes for the entire group were not statistically significant. Other parameters remained unchanged or were only slightly elevated. Two patients developed laboratory evidence of disseminated intravascular coagulation (DIC) but were clinically unaffected. Our data suggest that most patients with metastatic prostate cancer show evidence of ongoing activation of platelets, coagulation, and fibrinolysis. In a few individual patients, androgen stimulation of this hormonally dependent tumor may cause further activation of platelets, coagulation, and fibrinolysis.

Aged↗
PubMed1988

Pinocchio cells: morphologically atypical immunologically heterogeneous lymphocytes induced by treatment with interleukin 2.

We describe a novel cell type, the Pinocchio cell, that appears in the peripheral blood of all patients receiving treatment with interleukin 2, up to 20,000 cells/microliter. This cell is characterized by a prominent and granular proboscis with which it attaches to tumor cells and mediates tumor cell lysis. Pinocchio cells are immunologically heterogeneous and express antigens of both T and NK cells; Pinocchio cells are adherent in culture and are more cytolytic than non-adherent cells against NK-sensitive and resistant tumor cells. Incubation of normal whole human blood for 1 h induces Pinocchio morphology of mononuclear white blood cells.

Antigens, Differentiation↗
PubMed1988

Androgen priming and chemotherapy in advanced prostate cancer: evaluation of determinants of clinical outcome.

We conducted a randomized clinical trial in men with stage D2 prostate cancer to test whether androgen priming potentiates the efficacy of cytotoxic chemotherapy. Eighty-five men with progressive prostate cancer refractory to orchiectomy were treated continuously with aminoglutethimide and hydrocortisone to lower adrenal androgen secretion and were administered cyclic intravenous (IV) chemotherapy. The patients were randomized to receive either androgen priming or no additional treatment for three days before and on the day of chemotherapy. Median duration of follow-up was 43 months. Response rate (remission plus disease stabilization) was not significantly different between the stimulation and control arm when the analysis was restricted to evaluable patients (79% v 73%, respectively) or when it was extended to all patients (46% v 61%). Median duration of response was similar for the stimulation and control arm (9 and 10 months, respectively). Median survival was 10 months in the stimulation and 15 months in the control group (P = .0047). The androgen sensitivity of the tumors was supported by the greater toxicity in the stimulation arm associated with androgen administration. Factors found to be independently associated with improved clinical outcome included a high Karnofsky score and hematocrit, long duration of response to the initial castration, and normalization of an elevated serum acid phosphatase on treatment. We conclude that in this group of patients with advanced disease, androgen priming does not potentiate the efficacy of chemotherapy and is actually associated with a worse outcome. Furthermore, our data emphasize the heterogeneity of biologic behavior of prostate cancer.

Acid Phosphatase↗
PubMed1988

Comparison of beta-adrenergic agents delivered by nebulizer vs metered dose inhaler with InspirEase in hospitalized asthmatic patients.

The present study was undertaken to determine if beta-agonists delivered by nebulizer provide better clinical responses than MDI therapy in status asthmaticus. We divided 28 hospitalized asthmatic patients into three groups. Group 1 received albuterol by MDI with InspirEase. Group 2 received nebulized albuterol. Group 3 received nebulized metaproterenol. Both nebulizer regimens resulted in significant improvements in both FVC and FEV1 by 30 min after initial hospital beta-agonist treatment. No significant improvement was noted in initial spirometry in the MDI with InspirEase group. In spite of the superiority of nebulizer therapy in the initial phase of hospitalization, the daily rates of spirometric improvement and duration of hospitalization were not significantly different among the three groups. Our results indicate that nebulizer therapy provides superior spirometric improvement in the initial phase of status asthmaticus. However, both MDI and nebulizer regimens provided similar rates of spirometric improvement and duration of hospitalization.

Adult↗
PubMed1988

Islet cell tumor presenting as massive upper gastrointestinal bleeding in pregnancy.

A 27-yr-old woman presented in the 6th month of pregnancy with massive gastrointestinal bleeding due to erosion of a pancreatic islet cell tumor into the duodenum. Most islet cell tumors present with neuroendocrine manifestations; massive bleeding is a very rare presenting sign. This is the first reported case of a pregnant woman with massive bleeding from islet cell tumor erosion who underwent successful resection and delivery of a healthy term child 3 months later.

Adenoma, Islet Cell↗
PubMed1987

A multifactorial system for equitable selection of cadaver kidney recipients.

During 1986, a total of 270 cadaver renal transplantations were performed at the University of Pittsburgh. Kidneys were allocated by a point system that awarded points to recipients for waiting time, antigen matching, antibody analyses, medical urgency, and logistic practicality. Kidneys were given to patients with the highest point totals in 98% of cases. To our knowledge, this is the first such multifactorial system for cadaver kidney allocation. Possibly it may be modified for extrarenal organs.

Adolescent↗
PubMed1987

The cytoskeletal mechanics of brain morphogenesis. Cell state splitters cause primary neural induction.

There is a functional device in embryonic ectodermal cells that we propose causes them to differentiate into either neuroepithelial or epidermal tissue during the process called primary neural induction. We call this apparatus the "cell state splitter." Its main components are the apical microfilament ring and the coplanar apical mat of microtubules, which exert forces in opposite radial directions. We analyze the mechanical interaction between these cytoskeletal components and show that they are in an unstable mechanical equilibrium. The role of the cell state splitter is thus to create a mechanical instability corresponding to the embryonic state of "competence" in an otherwise mechanically stable cell. When the equilibrium of the cell state splitter is disturbed so as to produce a slight contraction of the apical end, apical contraction continues and the distinctive columnar neuroepithelial cells are produced. A slight expansion from the equilibrium state, on the other hand, results in flattened epidermal cells. The calculated forces are consistent with the known constitutive and force-generating properties and morphology of microfilaments and microtubules, and with free tubulin concentrations. There are no free parameters in the analysis. The first cells to assume the neuroepithelial state lie over the notochord. Propagation of the neuroepithelial state (homoiogenetic induction) then proceeds via stretch-induced constriction of the apical microfilament rings, until a hemisphere is covered, at which point the high rate of change of the meridional stress component necessary for further propagation vanishes. The remaining cells are stretched somewhat by this process and become epidermis. A sharp boundary between the tissues is thus formed (explaining "compartmentalization" and the binary nature of differentiation in general). Normal induction apparently involves setup of the cell state splitters in all of the ectoderm cells, perhaps synchronously timed by global embryo tension. The initial transition of cells from the ectodermal to the neuroepithelial state begins at the notoplate, where cell attachments to the notochord may both cause basal actin deposition and significantly reduce the stress induced in the ectoderm by the global tension, biasing the notoplate cell state splitters toward the neuroepithelial state. Introduction of an organizer or other solid substrate (artificial inducer) elsewhere, to which ectodermal cells can adhere, may likewise have both of these effects. Differentiation to either epidermis or neuroepithelium is thus a mechanical event followed by the synthesis of specific proteins.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗