Selenium-72 formation via nat Br(p,x) induced by 100 MeV protons: steps towards a novel 72Se/72As generator system.

Selenium-72 production by the proton bombardment of a natural NaBr target has been successfully demonstrated at the Los Alamos National Laboratory Isotope Production Facility (LANL-IPF). Arsenic-72 (half life 26 h) is a medium-lived positron emitting radionuclide with the major advantage of being formed as the daughter of another "generator" radioisotope (Se-72, 8.5 d). A (72)Se/(72)As generator would be the preferred mechanism for clinical utilization of (72)As for positron emission tomography (PET). No portable (72)Se/(72)As generator system has been demonstrated for convenient, repeated (72)As elution ("milking"). In this work, we describe (72)Se production and recovery from irradiated NaBr targets using a 100 MeV proton beam. We also introduce an (72)As generator principle based on (72)Se chelation followed by liquid-liquid extraction, which will be transferred to a solid-phase sorption/elution system.

The "common cold" in frail older persons: impact of rhinovirus and coronavirus in a senior daycare center.

OBJECTIVE: To evaluate the incidence and impact of rhinovirus and coronavirus infections in older persons attending daycare. DESIGN: Prospective descriptive study. SETTING: Three senior daycare centers in Rochester, New York. PATIENTS: Frail older persons and staff members of the daycare centers who developed signs or symptoms of an acute respiratory illness. MEASUREMENTS: Demographic, medical, and physical findings were recorded on subjects at baseline and during respiratory illness. Nasopharyngeal specimens for viral culture as well as acute and convalescent sera for coronavirus 229E enzyme immunoassay (EIA) were obtained for all illnesses. RESULTS: During the 44 months of study, 352 older persons experienced 522 illnesses. Thirty-five (7%) of 522 cultures were positive for rhinovirus and 37 (8%) of 451 serologies were positive for coronavirus 229E infection. The clinical syndromes associated with rhinovirus and coronavirus infection were similar and characterized by nasal congestion, cough, and constitutional symptoms. No patient died or was hospitalized, but approximately 50% had evidence of lower respiratory tract involvement. The average illness lasted 14 days. During the same period, 113 staff developed 338 respiratory illnesses. Eight percent were identified as coronavirus and 9% as rhinovirus. Cough, sputum production, and constitutional symptoms were significantly more common among older persons. CONCLUSIONS: Rhinovirus and coronavirus 229E are common causes of moderately debilitating acute respiratory illnesses among older persons attending daycare.

Endocrine consequences of continuous antiestrogen therapy with tamoxifen in premenopausal women.

Daily administration of estrogen antagonists to premenopausal women has been incorporated into the adjuvant treatment of breast cancer. We have studied the changes in reproductive hormones, pituitary responses to hypothalamic-releasing hormones, and endometrial histology during treatment with the antiestrogen tamoxifen in five healthy, premenopausal women. These studies were carried out during one menstrual cycle before and during two cycles of antiestrogen treatment. All subjects continued to have regular menses with biphasic basal body temperature records. During treatment, estradiol (E2) levels were increased but followed the usual pattern reflecting follicular maturation and corpus luteum formation. The mean E2 concentration at the midcycle peak and during the luteal phase was twice that observed during the non-treatment cycle. By contrast, the concentrations and secretory patterns of luteinizing hormone and follicle-stimulating hormone were not greatly changed, and the gonadotropin responses to gonadotropin-releasing hormone were not suppressed. Endometrial biopsies obtained during the follicular phase of control and tamoxifen treatment cycles showed no differences whereas biopsies obtained during the luteal phase of tamoxifen cycles uniformly showed a lack of changes attributed to progesterone action with no progression of histologic changes beyond those expected on day 7-8 of the luteal phase. These observations are consistent with maturation of multiple ovarian follicles, a surprising finding considering the normal gonadotropin concentrations. The retarded development of the endometrium in the presence of supranormal serum E2 and progesterone concentrations is a morphologic demonstration of the antiprogestational effect of antiestrogens. The lack of gonadotropin suppression in the presence of hyperestrogenemia suggests a major antiestrogen action on the hypothalmus and pituitary gland.

PIP: Administration of antiestrogen has recently been incorporated into the management of breast cancer. To explore the endocrine consequences of this therapy 5 healthy premenopausal volunteers were observed and treated with daily administration of the antiestrogen Tamoxifen. During the treatment period all subjects continued to have regular menses and basal body temperature; estradiol (E2) levels increased but followed a regular pattern, and its concentration at midcycle and during the luteal phase were twice as high as during nontreatment. On the other hand, concentrations of LH and of ESH were not greatly changed. In the presence of higher concentrations of E2 and of progesterone the endometrium showed a retarded development, thus demonstrating the antiprogestational effect of Tamoxifen. The lack of gonadotropin suppression also suggests a major antiestrogen action on the hypotalamus and pituitary glands.

Distributed laboratory computing. Integration of a laboratory computer into a hospital information system.

The University of Iowa Hospitals and Clinics, a large teaching hospital and tertiary care referral center, has implemented a vendor-supplied laboratory computer package operating on a dedicated minicomputer. A high-speed communications link allows the laboratory computer to share patient administrative, census, and test result data with the central hospital information system on an interactive basis. Operational characteristics of the system are discussed, and special attention is given to the critical problems and advantages of interfacing two computers.

Paraquat lung injury in rabbits.

An aerosol model for the study of paraquat (PQ) toxicity was developed using a 134 litre chamber and an ultrasonic nebuliser. Three groups of New Zealand white rabbits weighing 2-3 kg were studied. Group I (n = 6) was exposed to 10 g PQ/100 ml double-distilled water (DDW), Group II (n = 24) was exposed to 200 mg PQ/100 Ml DDW and a control group (n = 6) was exposed to 100 ml DDW. In a second experiment ten animals (Group III) were exposed to 10 mg PQ/100 ML DDW over a three-month period together with a control group (n = 5). Group I animals died with extensive haemorrhagic pneumonitis 38 hours after the last challenge. Most animals in Group II surviving more than three exposures had a significant reduction (P less than 0.001) in arterial oxygen tension (PaO2) and an increase (P less than 0.001) in the alveolar-arterial O2 gradient. Specific compliance decreased (P less than 0.005) and functional residual capacity and breathing frequency increased (P less than 0.05). Tissue PQ values showed even pulmonary distribution, with evidence of PQ accumulation after repeated inhalation. The lungs showed focal interstitial fibrosis, interstitial thickening, proliferation of macrophages in the alveoli, epithelioid changes in the interstitium, Type II cell hyperplasia, and foci of acute inflammation with consolidation. Controls and Group III animals were normal. This indicates that repeated inhalation of paraquat aerosol induces dose-related interstitial pneumonitis and fibrosis in rabbits.