OKT3E, an anti-CD3 antibody that does not elicit side effects or antiidiotype responses in chimpanzees.

Chimpanzees were injected with OKT3 and two other anti-CD3 antibodies, OKT3D and OKT3E. Both of the new antibodies were of the mouse IgG2b isotype. Administration of the antibodies was identical to the clinical regimen used for OKT3 in humans: 5 mg i.v., daily for 10 consecutive days. All animals were monitored for fever during administration of the antibodies, and blood samples were taken throughout the treatment period for monitoring the effects of the antibodies on peripheral lymphocyte subsets and the appearance of circulating cytokines. OKT3 produced similar clinical effects to those observed in humans; fever (2/3), as well as elevations in cytokines were observed. As in humans, peripheral T cells were cleared with the first dose and remained absent or modulated of their T cell receptor molecules throughout treatment. OKT3D, IgG2b also produced fevers (2/3) and elevations of cytokines. Although it also cleared circulating T cells with the first dose and T cell counts remained low throughout treatment, remaining circulating T cells were coated with administered antibody and were able to reexpress the CD3 antigen. OKT3E, IgG2b produced no temperature elevations and no elevations in cytokines. Although it cleared the circulation of T cells with the first does, cells reappeared during treatment, modulated of their CD3 antigens or coated with the administered antibody. All three antibodies raised antimouse antibodies, and OKT3 and OKT3D also produced blocking antiidiotype antibodies. OKT3E treatment did not result in anti-OKT3E blocking antibodies.

Sucralose: lack of effects on sperm glycolysis and reproduction in the rat.

Certain chlorine-substituted sugars with chemical similarities to sucralose have been demonstrated previously to diminish or inhibit sperm glycolysis and fertility in the rat ([Ford]). In order to investigate this potential for sucralose, epididymal spermatozoa were recovered from rats exposed in vivo to oral doses of one of three of these substituted sugars: 6-chloroglucose (6-CG, 24mg/kg/day, positive control), sucralose (500mg/kg/day, over 300 times the expected human daily intake), or a 6'-substituted isomer of sucralose, trichloro de-oxy sucrose (TCDS, 100mg/kg/day, a potential trace impurity in commercial sucralose); distilled water served as the negative control. After incubation of the spermatozoa with D-[U-(14)C] glucose, measurements of (14)CO(2) and of ATP content showed no impairment of the glycolytic ability of spermatozoa in any of the groups except for a marked inhibition for those exposed to 6-CG, the positive control. In order to determine whether other parameters of reproduction and fertility could be affected, reproductive endpoints were examined following oral exposure of male and female rats to sucralose. Sucralose was fed in the diet at concentrations of 0, 0.3, 1.0 and 3.0% (approx. 100, 365 and 1150 times the EDI) to groups of 30 male and 30 female rats for 10 weeks prior to mating, and continued through two subsequent generations until weaning of the F(2) pups. Two litters were produced per generation. Food consumption and weight gain in the F(0) and F(1) generations were depressed in all sucralose groups before mating and in all four litters prior to weaning. The decrease in initial average weight for newborn pups probably reflects the increased litter sizes noted for sucralose-treated groups and the reduced food consumption of the dams during gestation and lactation. The latter is a result primarily of the unpalatability of sucralose to rats ([McNeil,]). Caecal enlargement (a common animal response to large doses of indigestible material) occurred in both the F(0) and F(1) parents. Increased kidney weights, possibly associated with increased water intake, were observed primarily among animals receiving 3% sucralose (no renal histopathology has been detected). Decreased thymus weights occurred in F(1) males and in both F(1) and F(2) females at the 3% level. Subsequent studies specifically designed to investigate the potential for adverse immune system effects of sucralose ([McNeil,]) showed no adverse effects. These findings are consistent with investigations by others showing that decreases in thymus weights occur in young rats in response to stressful conditions associated with reductions in weight gain. All reproductive indices (oestrous cycles, mating behaviour, fertility, gestation, maternal and foetal viability, foetal development, parturition, pup maturation and lactation) were comparable between the control and sucralose-treated groups. We conclude from these results that sucralose has no effect on sperm glycolysis or on male or female reproductive performance in the rat.

Sucralose: assessment of teratogenic potential in the rat and the rabbit.

The teratogenic potential of sucralose was examined following gavage administration to pregnant rats and rabbits during organogenesis. Groups of 20 mated rats were dosed on days 6-15 of gestation inclusive at 500, 1000 or 2000mg/kg/day; groups of 16 to 18 inseminated rabbits were dosed on days 6 to 19 of gestation inclusive at 175, 350 or 700mg/kg/day following preliminary studies at higher doses. Concurrent control groups received vehicle alone. Rats were killed on day 21 and rabbits on day 29 of gestation. Foetuses were evaluated at necropsy and after processing for possible soft tissue and skeletal alterations. There was no evidence of teratogenicity for either species. The only observed response to treatment in rats was a slight increase in water intake. Some adult rabbits receiving 700mg/kg/day exhibited marked gastrointestinal disturbance, also seen at higher doses in preliminary studies. Gastrointestinal effects such as these occur non-specifically in response to high doses of poorly absorbed compounds, and in the present study were considered to be responsible for two maternal deaths and four abortions. Full evaluation of rabbit foetuses in the main study (up to 700mg/kg/day) and necropsy of foetuses in a preliminary study with pregnant animals (up to 1000mg/kg/day) showed no evidence of adverse foetal response to sucralose. These teratology studies in both pregnant rodent and non-rodent animal models demonstrate that maternal consumption of high levels of sucralose during the period of organogenesis has no effect on normal foetal development in the rat or rabbit.

Late presenting, intrarenal haematoma as a complication of renal biopsy.

An intrarenal haematoma, necessitating surgical evacuation, is described as a novel, late presenting, complication of percutaneous renal biopsy in a patient with amyloid disease.

A review of the toxicology profile of rioprostil.

The toxicity of rioprostil was extensively investigated. Studies in rodents, dogs and monkeys indicate a low order of acute toxicity. Oral subchronic and chronic toxicity studies in rats and dogs produce effects that would be expected based on the pharmacological activity of the compound. In reproduction studies with rioprostil, male and female fertility is unaffected in rats at doses up to 2.0 mg/kg/day and there is no evidence of embryotoxicity, fetotoxicity, or teratogenicity in rats at doses up to 1.7 mg/kg/day. In rabbits a maternally toxic dose (1.5 mg/kg) also increases resorptions, reduces fetal weight, and increases the incidence of malformations. Evaluation of 24-month carcinogenicity studies in mice and rats at oral doses up to 2.0 and 1.5 mg/kg/day, respectively, are in progress. Mutagenicity studies are negative.

Adenosine as a mediator of postcontraction hyperemia in dog gracilis muscle.

The role of adenosine in postcontraction hyperemia (PCH) following sustained, maximal isometric contractions was studied in free-flowing dog gracilis muscles. The hemodynamic responses to contraction were examined in the presence and absence of dipyridamole (an adenosine transport inhibitor), erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA, an adenosine deaminase inhibitor), or alpha, beta-methyleneadenosine-5'-diphosphate (AOPCP, an inhibitor of 5'-nucleotidase). Each muscle was stimulated to contract for 1, 3, 5, and 10 s during saline and drug infusions. For each contraction, the tension-time integral (TT), excess flow (EQ), and excess oxygen consumption (EVo2) were computed. Linear regression analyses were then performed on EQ vs. TT, EVo2 vs. TT, and EQ vs. EVo2. An alteration of the PCH response by the drug was determined as any significant change from the saline control in the slope of the linear regression of EQ vs. EVo2. Dipyridamole and EHNA caused increases of 73 and 48%, respectively, in the slope of EQ vs. EVo2, whereas AOPCP decreased the slope by 41%. The changes in the PCH produced by these drugs are consistent with the hypothesis that an increase in interstitial adenosine during muscular contraction contributes to PCH.

Primary alveolar hypoventilation (Ondine's curse syndrome) in an infant without external arcuate nucleus. Case report.

A five month old boy suffered from primary alveolar hypoventilation, with attacks of apnea during sleep (Ondine's curse syndrome). The ventilation did not increase when PACO2 was increased. However, it decreased during hyperoxia. This indicates a strong peripheral chemoreceptor drive and a dysfunction of the central chemoreception. The infant died from circulatory failure following an aspiration pneumonia. Autopsy revealed the absence of the external arcuate nucleus, which may be involved in the central chemocreception.

Elimination of central chemosensitivity by coagulation of a bilateral area on the ventral medullary surface in awake cats.

Breathing and respiratory response to CO2 were observed in 6 awake cats and 1 control before and after bilateral coagulation of the formerly described area S (Schläfke and Loeschcke, 1967) on the ventral medullary surface under hyperoxic conditions. Ventilation decreased, PCO2 rose and CO2 response was almost or completely abolished in 4 cats, and moderately reduced in 2 cats. Inhalation of CO2 had an inhibitory effect on ventilation in two cases. In some instances the respiratory frequency was increased by CO2. Periodic breathing as well as spontaneous hyperventilation elicited by 'arousal' indicate parallels to the Pickwickian or Ondine's curse syndrome. No respiratory changes were produced by a lesion on the pyramidal tract medial to the area S. It is concluded that central chemosensitivity can be eliminated within the superficial layer of the area S. The loss of CO2 response seems to be correlated with complete destruction of the superficial nerve cells located within the area S (Petrovický, 1968) and degeneration within the ventral part of the nucleus paragigantocellularis.

Alternative approaches to the safety assessment of macronutrient substitutes.

Traditional toxicological procedures have only limited application to the safety assessment of macronutrient substitutes. Experience indicates that spurious effects are often encountered when macronutrients or their replacements are fed to rodents at high dietary levels. These effects may results in nutritional imbalances that lead secondarily to adverse physiological consequences including cancer, renal disease, or reproductive effects. In approaching the safety assessment of macronutrient substitutes, consideration needs to be given to designing and implementing a safety assessment program which acknowledges the physical, chemical, and biological properties of the substance. Factors such as molecular size, physical state, solvent properties, hydrolysis potential, digestibility, absorption potential, and metabolic fate must be well established prior to selection of appropriate test models. Armed with this information, many potential undesirable physiological effects of the substances can be predicted, thus precluding the need for a full spectrum of animal testing. Predicted physiological and metabolic effects, however, should be characterized using in vitro methods and confirmed with in vivo models. Initial short-term toxicity screening tests with rodents should be carried out to identify unanticipated systemic toxicity. Testing in laboratory animals and trials in humans should then proceed with more appropriate models that are specially selected to assess the significance of predicted outcomes, to characterize dose-response relationships, and to identify possible needs to modify the product to mitigate adverse physiological consequences. These might include physical changes to alter particle size, chemical changes to modify digestibility, or nutrient supplementation to overcome impacts on nutrient availability. Thoughtful selection of appropriate and relevant models based on the physical, chemical, and biological properties of test substances will provide more rational approaches to safety assessments and avoid the pitfalls of routine application of traditional tests.

Strain differences in the immune response of mice to homologous sperm-specific lactate dehydrogenase (LDH-C4).

The sperm-specific isozyme of murine lactate dehydrogenase (LDH-C4) was injected into female mice of various strains. Two regulatory phenotypes characterize the resultant immunity to LDH-C4: one is manifested by high, intermediate or low levels of response, the other by the immediate or delayed maturation of peak titer. The response of several strains can be classified as high (SWR, SJL, BABL/c, C3H/He) and intermediate to low (A, CBA, DBA/2, DBA/1, C57BL/6) according to the level of antibody production and cell mediated immunity. BALB/c, SJL and SWR strains are immediate responders while DBA/2 and C3H/He mice are clearly delayed responders. Maturation and magnitude of response do not appear to be related. Both the antibody and cell mediated responses are T-dependent, but are not obviously associated with Ig allotype or H-2 regulation.