Joseph F. Weiss

Breathing 100% oxygen after global brain ischemia in Mongolian Gerbils results in increased lipid peroxidation and increased mortality.

Exposure of Mongolian gerbils to a 100% oxygen atmosphere after 15 minutes of global brain ischemia resulted in a marked increase in the production of pentane, an in vivo product of lipid peroxidation. Much less pentane production occurred in animals subjected to global brain ischemia then exposed to an air atmosphere and in animals exposed to a 100% oxygen atmosphere without ischemia. Gerbils placed in 100% oxygen for 3-6 hours after 15 minutes of ischemia also had a threefold increase in 14-day mortality compared with gerbils subjected to ischemia and then placed in an air atmosphere. These findings raise a serious question about the use of oxygen-enriched atmospheres during reperfusion following ischemia.

Advances in Radioprotection through the Use of Combined Agent Regimens

The most effective radioprotective agents exhibit toxicities that can limit their usefulness. It may be possible to use combinations of agents with different radioprotective mechanisms of action at less toxic doses, or to reduce the toxicity of the major protective compound by adding another agent. With regard to the latter possibility, improved radioprotection and reduced lethal toxicity of the phosphorothioate WR-2721 was observed when it was administered in combination with metals (selenium, zinc or copper). The known mechanisms of action of potential radioprotective agents and varying effects of different doses and times of administration in relation to radiation exposure must be considered when using combined-agent regimens. A number of receptor-mediated protectors and other biological compounds, including endotoxin, eicosanoids and cytokines, have at least an additive effect when administered with thiol protectors. Eicosanoids and other bioactive lipids must be administered before radiation exposure, whereas some immunomodulators have activity when administered either before or after radiation exposure. For example, the cytokine interleukin-1 administered simultaneously with WR-2721 before irradiation or after irradiation enhances the radioprotective efficacy of WR-2721. The most effective single agents or combinations of protectors result in a decrement in locomotor activity, an index of behavioral toxicity. Recent evidence indicates that administration of the CNS stimulant caffeine mitigates the behavioral toxicity of an effective radioprotective dose of the phosphorothioate WR-3689 without altering its radioprotective efficacy. These examples indicate that the use of combinations of agents is a promising approach for maximizing radioprotection with minimal adverse effects.

Radioprotection by vitamin E: injectable vitamin E administered alone or with WR-3689 enhances survival of irradiated mice.

Radioprotection by injectable vitamin E (alpha-tocopherol) was investigated in mice exposed to 60Co radiation (0.2 Gy/min). Vitamin E injected subcutaneously either 1 hr before or within 15 min after irradiation significantly increased 30-day postirradiation survival in CD2F1 male mice. A dose reduction factor (DRF) of 1.11 (95% confidence interval [1.08, 1.14]) was observed for vitamin E at a dose of 100 IU/kg body weight administered within 15 min after irradiation. Combination studies with the phosphorothioate WR-3689 (S-2([3-methylaminopropyl]amino)ethylphosphorothioic acid) were undertaken to determine whether radioprotection by WR-3689 could be enhanced by vitamin E. Mice were given WR-3689 (150-225 mg/kg, intraperitoneally) 30 min before irradiation and were given vitamin E (100 IU/kg) either 1 hr before or within 15 min after irradiation. Survival was significantly increased in mice given vitamin E and WR-3689 before irradiation as compared to mice given WR-3689 alone: the DRF for WR-3689 (150 mg) was 1.35 [1.32, 1.38]; for WR-3689 combined with vitamin E (100 IU), the DRF was 1.49 [1.45, 1.53].

Serum glycoproteins in cancer patients: First report of correlations with in vitro and in vivo parameters of cellular immunity

Serum levels of proteins previously shown to be elevated [acute‐phase proteins (APP)—haptoglobin, α1‐acid glycoprotein, α1‐antitrypsin] or depressed (α2HS‐glycoprotein, prealbumin, albumin) in cancer patients were correlated with tumor extent, in vitro lymphocyte reactivity (LR) to phytohemagglutinin (PHA), and quantitative delayed hypersensitivity (DH) to dinitrochlorobenzene (DNCB) in 147 pre‐operative patients with operable solid malignancies either confined to the primary site or with regional spread only. Compared to 58 normal controls, levels of the APP were significantly elevated, α2HS‐glycoprotein and prealbumin depressed, and albumin levels unchanged in patients with either local or regional tumors. In patients with normal DH to DNCB, the APP were higher and prealbumin was lower than in controls; in patients with impaired DH to DNCB, haptoglobin and α1‐acid glycoprotein were higher and α2HS‐glycoprotein and prealbumin lower than in patients with normal DH to DNCB. Albumin levels did not differ from normals in any of the groups. Serum protein levels appeared to be more related to the immune status of the patient than to tumor extent. The levels of the three APP correlated directly with each other but inversely with α2HS‐glycoprotein and prealbumin; levels of α2HS‐glycoprotein and prealbumin correlated directly with each other. Levels of haptoglobin and α1‐acid glycoprotein correlated inversely with LR to PHA; however, levels of α2HS‐glycoprotein correlated directly with LR to PHA, and uniquely the levels of α2HS‐glycoprotein and LR to PHA both showed similar changes for each of the four quantitative levels of DH to DNCB measured in the cancer patients. The data show that the proteins studied, except for albumin, correlate inversely (APP) or directly (α2HS‐glycoprotein and prealbumin) with in vitro and in vivo parameters of cellular immunity. The results provide a rationale for attempts to improve depressed cellular immunity by lowering circulating levels of APP, as is being attempted in ongoing trials using plasmapheresis, and assessing the effect of exogenous α2HS‐glycoprotein or prealbumin in patients with low levels of these glycoproteins and depressed cellular immunity. The correlations between serum glycoprotein levels and in vitro and in vivo parameters of cellular immunity lend rationale to investigations of the interactions of serum glycoproteins and blood cells having immunologic function that determine the level of cellular immunity expressed in vivo.

Correlations among serum protein-bound carbohydrates, serum glycoproteins, lymphocyte reactivity, and tumor burden in cancer patients

Levels of glycoprotein‐associated carbohydrates (neutral hexoses, hexosamine, sialic acid and fucose) were determined in the serum of patients with either local, regional or metastatic cancer, patients clinically cured of cancer, and controls (smokers and nonsmokers). Total protein‐bound carbohydrates were compared with levels of 17 normal serum glycoproteins, carcinoembryonic antigen (CEA),and with lymphocyte reactivity to phytohemagglutinin (PHA). Tumor burden was directly related to protein‐bound carbohydrate levels in patient groups. Levels of bound carbohydrates reflect the sum of all the changes in serum glycoproteins, but primarily changes in the acute‐phase proteins (α‐ acid glycoprotein, α‐antitrypsin, haptoglobin, ceruloplasmin) found in the α ‐globulin fraction of serum. Increases in protein‐bound carbohydrates in tumor‐bearers were not related to increases in CEA. Increased levels of the acute‐phase proteins occurred in individuals with depressed in vitro lymphocyte reactivity to PHA. A significant positive correlation was found between lymphocyte reactivity and levels of α2HS‐glycoprotein. The results suggest that serum protein‐bound carbohydrates or glycoproteins may be of adjunctive value in assessing tumor burden and immune reactivity in cancer patients.

Combined Modality Radioprotection: The Use of Glucan and Selenium with WR-2721

Glucan, WR-2721, and selenium, three agents with distinct radioprotective mechanisms, were evaluated in C3H/HeN mice for survival-enhancing and hemopoietic-regenerating effects when administered alone or in combinations before exposure to 60Co radiation. At LD50/30 radiation doses (radiation doses lethal for 50% of mice within 30 days postexposure), dose reduction factors of 1.21, 1.02, 1.37, 1.51, and 1.66 were obtained following glucan (75 mg/kg i.v., -20 hr), selenium (0.8 mg/kg, i.p., -20 hr), WR-2721 (200 mg/kg, i.p., -30 min), glucan + WR-2721, and glucan + selenium + WR-2721 treatments, respectively. All treatments increased numbers of hemopoietic stem cells as measured by the day 12 endogenous spleen colony-forming unit (E-CFU) assay; the most significant E-CFU effects, however, were observed following glucan + WR-2721 and glucan + selenium + WR-2721 treatments. Combined modality treatments were also more effective than single-agent treatments at accelerating bone marrow and splenic granulocyte-macrophage colony-forming cell (GM-CFC) regeneration. These results demonstrate the value of multiple-agent radioprotectants.

Serum glycoproteins in head and neck squamous carcinoma: Correlations with tumor extent, clinical tumor stage, and T-cell levels during chemotherapy

Abstract In patients with solid malignancies, serum levels of specific acute phase proteins (haptoglobin, α 1 -acid glycoprotein, and α 1 -antitrypsin) have been correlated with parameters of both tumor extent and cellular immunity, while α 2 HS-glycoprotein and prealbumin have been correlated with parameters of cellular immunity. To determine the relation of the glycoproteins to these parameters in head and neck squamous carcinoma, serum levels were measured in 90 untreated patients, 51 cured patients, 11 patients with recurrent carcinoma, and 20 patients during preoperative chemotherapy. The control patients were 139 chronic cigarette smokers. Haptoglobin levels were significantly increased in patients with stage I through IV tumors (AJC-1977), but levels were similar for each stage. Serum levels of α 1 -antitrypsin and α 1 -acid glycoprotein increased progressively with increasing tumor stage. Serum α 2 HS-glycoprotein, prealbumin, and albumin levels were decreased in all patients, and α 1 HS-glycoprotein levels decreased progressively with increasing tumor stage. When patients were classified into those with local tumors only and those with regional metastases, and further subclassified by extent of local or regional tumor, the acute phase proteins generally increased with increasing local or regional tumor extent and α 2 HS-glycoprotein levels tended to decrease in the same groups. In cured patients, haptoglobin and α 1 -acid glycoprotein levels were significantly lower and α 2 HS-glycoprotein and prealbumin significantly higher than in untreated patients. Protein levels in patients with recurrent tumors were similar to levels in untreated patients. During acute immunosuppressive chemotherapy, levels of T-cells and α 2 HS-glycoprotein decreased significantly and similarly, and after completion of chemotherapy, rebounded to pretreatment levels, while α 1 -antitrypsin levels increased and haptoglobin and α 1 -acid glycoprotein levels did not change. The data show that α 1 -antitrypsin and α 1 -acid glycoprotein correlate better with AJC tumor stage than cellular immune parameters previously studied and that α 2 HS-glycoprotein levels may be as useful as T-cell levels for monitoring immune reactivity in patients with squamous cancer of the head and neck. These results suggest the potential of these biologic parameters as adjuncts in the derivation of improved staging systems and as indicators of tumor status and immune reactivity in patients with squamous carcinoma of the head and neck.

Behavioral Toxicity and Efficacy of WR-2721 as a Radioprotectant

S-2-(3-Aminopropylamino)ethylphosphorothioic acid (WR-2721) is a promising protectant for radiation-induced lethality. However, treatment with WR-2721 also produces nausea, vomiting, diarrhea, and hypotension, which implies severe functional consequences. Three studies were conducted to assess the effects of WR-2721 on rat motor performance and weight and to assess the ability of WR-2721 to mitigate the early performance decrement (PD) produced by ionizing radiation. In the first study, rats trained on the accelerod motor performance task were give 200, 300, or 400 mg/kg WR-2721 intraperitoneally (ip). The highest dose used referenced the maximum tolerated dose in the rat, which is two-thirds the median lethal dose (590 mg/kg). The subjects were tested immediately after treatment, at 30-min intervals for 3 h, and again at 24 h. All groups (N = 6/group) demonstrated a significant decrease in accelerod performance compared to control levels across the eight test trials, which ranged from 24 to 44% in the 200 and 400 mg/kg dose groups, respectively. Performance returned to baseline levels at 24 h. Some deaths occurred at all dose levels. In the second study, motor performance was measured after exposure to radiation alone or a drug/radiation combination (N = 8/group). WR-2721 was administered 30 min before exposure to 130 Gy of gamma radiation from a 60Co source at a dose rate of 20 Gy/min. Rats were tested on the accelerod immediately after WR-2721 treatment and at 10, 15, 30, 60, and 120 min and 24 h following radiation. Performance was significantly depressed compared to control throughout the 24 h following radiation exposure, with and without WR-2721. The decrement produced by WR-2721 and radiation alone appeared to add up to the combined drug/radiation decrement found over the 15- to 120-min test periods. In the third study assessing the effects of WR-2721 on weight, untrained rats treated with 200 or 400 mg/kg WR-2721 exhibited significant weight loss that lasted up to 3 days. Weight returned to pretreatment levels in 15 days, and no deaths occurred. In summary, the data suggest that in the rat (1) WR-2721 is behaviorally toxic at doses relevant to radioprotection, (2) WR-2721 treatment along with the stress of motor performance may combine to lower the level at which lethalities occur, (3) WR-2721 does not protect for radiation-induced PD, and (4) WR-2721 combined with radiation disrupts performance more severely than either radiation or WR-2721 alone.

Behavioral toxicity of selected radioprotectors

Effective radioprotection with minimal behavioral disruption is essential for the selection of protective agents to be used in manned spaceflight. This overview summarizes the studies on the behavioral toxicity of selected radioprotectors classified as phosphorothioates (WR-2721, WR-3689), bioactive lipids (16, 16 dimethylprostaglandin E2(DiPGE2), platelet activating factor (PAF), leukotriene C4), and immunomodulators (glucan, synthetic trehalose dicorynomycolate, and interleukin-1). Behavioral toxicity was examined in laboratory mice using a locomotor activity test. For all compounds tested, there was a dose-dependent decrease in locomotor behavior that paralleled the dose-dependent increase in radioprotection. While combinations of radioprotective compounds (DiPGE2 plus WR-2721) increased radioprotection, they also decreased locomotor activity. The central nervous system stimulant, caffeine, was able to mitigate the locomotor decrement produced by WR-3689 or PAF.

Dose and time relationships of the radioprotector WR-2721 on locomotor activity in mice

The effects of the radioprotector S-2-(3-aminopropylamino)ethylphosphorothioic acid (WR-2721) on locomotor activity were evaluated in CD2F1 male mice. Separate groups of animals (N = 10/group) received an IP injection of vehicle, 25, 50, 100, 200, or 400 mg/kg of WR-2721 immediately before testing. Horizontal and vertical activity were measured using a Digiscan automated animal activity monitor. The latency to onset and duration of action of each dose of the radioprotector were recorded. For both behavioral measures, a significant reduction was observed in activity at doses of 200 and 400 mg/kg. A dose of 200 mg/kg had a 12- to 14-min latency to onset and significantly reduced behavioral activity for 3 hr. Mice injected with 400 mg/kg exhibited locomotor deficits within 8-10 min and were affected for up to 9 hr. The ED50 for horizontal and vertical activities at 1 hr postinjection were determined to be 271 and 105 mg/kg, respectively. The results demonstrate that significant reductions in locomotor activity are exhibited at doses of 200 mg/kg or more and that vertical activity was more sensitive to the disruptive effects of WR-2721 than was horizontal activity.