Effects of hepatic arterial yttrium-90 microsphere administration alone and combined with regional bromodeoxyuridine infusion in dogs

Brachytherapy by embolization with radiotherapeutic microspheres following intraarterial infusion of a radiosensitizer represents an attempt to combine several selective modalities into a more potent, focused attack on regionally confined tumors. In pursuit of this goal, we examined the ability of foxhounds with surgically implanted hepatic arterial (HA) delivery systems to tolerate a clinically relevant dosage of HA yttrium-90 (Y-90) by microsphere administration either alone or preceded by a 28-day constant HA infusion of either 5-bromo-2'-deoxyuridine (BUDR) or a control solution. Five dogs received BUDR (10 mg/kg/day) and five a control buffer infusion for 28 days immediately prior to the administration of Y-90-coated 15 micron resin microspheres (equivalent of 5000 rads to the entire liver) to each dog on day 31. In all animals, blood counts, bilirubin, amylase, appetite, weight, and behavior remained unchanged. Dogs receiving the microspheres after buffer infusion alone exhibited no hepatic enzyme alanine aminotransferase or alkaline phosphatase elevation. Alanine aminotransferase and alkaline phosphatase levels both rose during the third week of BUDR infusion, and while subsequent microsphere administration further increased enzyme levels, these levels had largely normalized by necropsy on day 82. At necropsy, the type and degree of hepatic toxicity among the animals receiving radioactive microspheres was comparable to that previously described in patients receiving external beam hepatic irradiation at conventional doses (2000-3000 rads). Also noted was a radiation-induced cholecystitis (due in large part to the gallbladder's total reliance on the hepatic artery for blood supply). One resin microsphere dog exhibited a small quantity of microspheres in the lungs causing focal radiation-induced granulomas suggesting the need to assess shunting of microspheres through the liver in clinical studies. Thus, HA Y-90 microspheres with BUDR can produce acceptable, nonlethal, and tolerable toxicities in this dog model suggesting that clinical studies of this combination are not likely to be contraindicated by synergistic toxicity. Although HA BUDR did not contribute significantly to the toxicity of the Y-90 microspheres, HA BUDR by itself administered uninterrupted for 4 weeks may, like HA FUDR (clinically), cause chemical hepatitis/cholangitis. The unexpected fragmentation of the resin spheres (albeit without myelosuppression) has led us to begin studies with a recently developed nondisruptible glass microsphere (ThereSphere) in which the Y-90 is part of the glass matrix and cannot leach.(ABSTRACT TRUNCATED AT 400 WORDS)     

Detailed Diurnal Rhythm of Sensitivity to Melatonin Injections in Turkish Hamsters, Mesocricetus brandti

A diurnal rhythm of sensitivity to exogenous melatonin was defined in adult male Turkish hamsters, Mesocricetus brandti. Melatonin was administered daily by subcutaneous injections (15 micrograms in 0.1 ml 10% ethanolic saline) for 10 weeks in animals exposed to 16 L:8 D. As in golden and Djungarian hamsters, two periods of melatonin sensitivity were identified. The first, in late afternoon, persisted for 6 hr, from 7 hr to 1 hr before lights off. The second period was briefer, of only 2 hr duration in the late night, terminating at the time of lights on. Melatonin injections given during these sensitive periods promoted testicular regression in most animals; melatonin administered at other times of the day was without effect on testicular function in most animals of these groups. Gonadal regression induced by properly timed melatonin injections was rapid, in many groups nearly complete in 6 to 7 weeks. The results are discussed in relation to the function of pineal melatonin in photoperiodic time measurement in hamsters.     

Nondisease genetic testing: reporting of muscle SNPs shows effects on self-concept and health orientation scales

The purpose of this study was to assess the impact of genetic self-knowledge (nondisease genotype information) on individual self-concept and Health Orientation Scale (HOS). Adult volunteers (n=257) were recruited from an ongoing genetic association study identifying muscle quantitative trait loci (QTLs). Participants completed psychosocial assessments before and after 12 weeks of resistance training of the nondominant arm. At study exit, a genetic counselor informed participants of genetic test results on three to four genes that have an association with muscle-related traits, and counseled subjects on the potential significance of these findings. The second psychosocial assessment was performed immediately following this counseling session. The Tennessee Self-Concept Scale v.2 (TSCS:2) and the HOS showed female subjects to have a significantly greater positive change between first and second assessments, relative to male subjects. Most self-concept subscales improved significantly, when 'neutral' genotypes (no anticipated beneficial or deleterious impact) were reported, compared to positive genotypes. TSCS:2 subscales showing improvement included: total (P=0.013); physical (P=0.004); satisfaction (P=0.019); and behavioral (P=0.047). HOS subscales showing improvement included health image concern (P=0.006); and health expectations (P=0.047). In conclusion, these results suggest that genetic self-knowledge affects self-concept, consistent with the 'attribution' theory. Individuals who received neutral genetic information attributed positive changes from the exercise program to their own abilities, while those who received positive information were more likely to attribute positive changes to their genetics. This study is limited by the ability to determine the direction of the impact of nondisease genetic information presented to participants.     

Use of in vivo-induced antigen technology for identification of Escherichia coli O157:H7 proteins expressed during human infection

Using in vivo-induced antigen technology (IVIAT), a modified immunoscreening technique that circumvents the need for animal models, we directly identified immunogenic Escherichia coli O157:H7 (O157) proteins expressed either specifically during human infection but not during growth under standard laboratory conditions or at significantly higher levels in vivo than in vitro. IVIAT identified 223 O157 proteins expressed during human infection, several of which were unique to this study. These in vivo-induced (ivi) proteins, encoded by ivi genes, mapped to the backbone, O islands (OIs), and pO157. Lack of in vitro expression of O157-specific ivi proteins was confirmed by proteomic analysis of a mid-exponential-phase culture of E. coli O157 grown in LB broth. Because ivi proteins are expressed in response to specific cues during infection and might help pathogens adapt to and counter hostile in vivo environments, those identified in this study are potential targets for drug and vaccine development. Also, such proteins may be exploited as markers of O157 infection in stool specimens.     

Rapid expansion and IL-4 expression by Leishmania-specific naive helper T cells in vivo

CD4 T cells are pivotal for effective immunity, yet their initial differentiation into effector subsets after infection remains poorly defined. We examined CD4 T cells specific for the immunodominant Leishmania major LACK antigen using MHC/peptide tetramers and IL-4 reporter mice. Comprising approximately 15 cells/lymph node in naive mice, LACK-specific T cells expanded over 100-fold, and 70% acquired IL-4 expression by 96 hr. Despite their pathogenic role in susceptible mice, LACK-specific precursor frequency, expansion, and IL-4 expression were comparable between susceptible and resistant mice. When injected with unrelated antigen, Leishmania efficiently activated IL-4 expression from naive antigen-specific T cells. CD4 subset polarization in this highly characterized model occurs independently from IL-4 expression by naive T cells, which is activated indiscriminately after parasitism.     

Prostaglandin E2 synthesis and suppression of fibroblast proliferation by alveolar epithelial cells is cyclooxygenase-2-dependent

Alveolar epithelial cells (AECs) may influence neighboring fibroblasts by the elaboration of prostaglandin E(2) (PGE(2)). This prostanoid can be synthesized via "constitutive" cyclooxygenase (COX)-1 and "inducible" COX-2 enzyme isoforms. We compared AECs isolated from wild-type (WT), COX-1 knockout (KO), and COX-2 KO mice to determine the contribution of COX isoforms to AEC PGE(2) synthesis and capacity for suppression of fibroblast proliferation in co-cultures. WT AECs constitutively expressed both COX-1 and COX-2 isoforms by immunoblot analysis. COX-1 KO cells and WT cells comparably augmented PGE(2) synthesis following incubation with lipopolysaccharide or interleukin-1, whereas COX-2 KO cells were unable to do so. Surprisingly, however, constitutive generation of PGE(2) was also dramatically reduced only in COX-2 KO cells. When co-cultured with WT murine lung fibroblasts, AECs from WT and COX-1 KO animals suppressed serum-induced fibroblast proliferation, whereas COX-2-deficient AECs caused a modest enhancement in fibroblast proliferation. These results indicate that PGE(2) synthetic capacity in AECs is predominantly COX-2-dependent under both basal and stimulated conditions. They also demonstrate conclusively that AECs can modulate fibroblast function by the elaboration of suppressive prostanoids. These alterations in AEC phenotype likely contribute to the propensity for pulmonary fibrosis observed in COX-2-deficient mice.