Evaluation of the fluorescein diacetate (FDA) vital dye viability test with hamster and bovine embryos

A study was undertaken to determine: (1) the potential toxicity of a fluorogenic vital dye, fluorescein diacetate (FDA), on hamster and bovine pre-implantation embryos; and (2) whether a correlation exists between the fluorescence of an embryo and its ability to continue development.For the toxicity trial, hamster eight-cell embryos were randomly assigned to one of three groups (control, FDA+UV light or UV light only), and early bovine blastocysts to either a control or FDA+UV light group. Embryos were cultured for 24 h and scored for development to the blastocyst stage. Embryos of both species developed equally well in vitro regardless of whether or not they had been exposed to FDA and UV light. Treated and untreated control embryos from both species were transferred to synchronized recipients. Similar numbers of pregnancies resulted after transfer of treated and untreated embryos from both species.In the second experiment, the proportions of fluorescing embryos were compared using two groups of hamster eight-cell embryos: (1) freshly collected embryos; and (2) cultured embryos that failed to develop. Significantly more of the fresh eight-cell embryos fluoresced than did the cultured, undeveloped embryos. No false negative results were obtained (embryos that developed but failed to fluoresce). However, approximately half of the non-developing, cultured embryos showed varying degrees of fluorescence (false positive). Embryos showing “false positive” fluorescence may be viable, but incapable of further development due to deficiencies of the culture medium.The procedures used in the FDA viability assay were not detrimental to development of late cleavage stage mammalian embryos and thus seem suitable for rapid screening of manipulated embryos for potential damage. However, further work is needed to establish the significance of the false positive results encountered in this study.     

Ethanol stimulates formation of leukotriene C4 in rat gastric mucosa

Ethanol-induced gastric mucosal damage is characterized by microcirculatory changes such as stasis and plasma leakage. Sluggish blood flow and stasis have also been observed after administration of exogenous leukotriene (LT) C4. The effect of ethanol on the release of LTC4 from rat gastric mucosa was therefore investigated. It was found that intragastric instillation of ethanol increases gastric mucosal release of LTC4 in a dose- and time-dependent manner parallel to the production of gastric lesions. The lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA) and the anti-ulcer drug carbenoxolone (CX) inhibited mucosal release of LTC4 and simultaneously protected against gastric damage caused by ethanol. It is concluded that increased formation of LTC4 and/or other 5-lipoxygenase-derived products of arachidonate metabolism may be involved in ethanol-induced gastric damage. Furthermore, inhibition of the 5-lipoxygenase pathway may be an important mechanism of action of gastric protective drugs.     

Hepatitis safety of a new prothrombin complex preparation, sterilized according to the method of LoGrippo. Results of a prospective clinical trial

In a controlled, prospective clinical trial with almost 300 patients undergoing cardiovascular surgery, the hepatitis risk was examined of a new prothrombin complex (PPSB) preparation produced from pooled plasma, which was cold sterilized according to the method of LoGrippo with beta-propiolactone and UV-light. Of 268 evaluable patients, 102 belonged to a group receiving PPSB and 166 belonged to a control group without PPSB. 25 batches of PPSB in dosages of up to 4,500 units per patient, in total, were used. The mean requirement for transfusion of blood or plasma was 10 units per patient in the group receiving PPSB and slightly more than 2 units per patient in the control group. In both of the groups, 3 hepatitis infections occurred (5 cases of non-A, non-B, 1 case of type B), corresponding to hepatitis incidences of 2.9 and 1.8%, respectively. The difference in hepatitis incidence between both groups was statistically not significant. This demonstrates, on the one hand, the hepatitis safety of the sterilized PPSB and, on the other, that multiple transfusion is no longer associated with a high risk of hepatitis when the guidelines of modern donor screening are followed.     

The effect of changes in cardiac frequency on left and right ventricular dP/dt max at different contractile states of the myocardium

In 17 canine heart-lung preparations the dependence of frequency potentiation of the right and left ventricular myocardium on the basic inotropic state of the heart was investigated. The effect of unipolar stimulation of the right atrium on dP/dt max in both ventricles was measured. The aortic pressure was maintained constant. Shortly after isolation of the heart, a stepwise increase of rate from 140 to 200 beats/min only had a very weak influence on left ventricular dP/dt max. With deterioration of the myocardium the frequency potentiation of dP/dt max increased considerably. End-diastolic pressure regularly decreased with rising cardiac frequency. Since the real positive inotropic effect is masked by the concomitant fall in diastolic loading, the end-diastolic pressure was maintained constant in a second group of 8 hearts during rate variation. The most pronounced inotropic effect was now found shortly after isolation of the heart. A rate increase of 30 beats/min resulted in a 20% rise of dP/dt max. The frequency potentiation decreased with deterioration of the heart resulting in a 12% dP/dt max increase at an estimated inotropic state of 50% of control. When the contractile state of the heart was improved above the control state by calcium application the frequency potentiation of the myocardium decreased. In the right ventricle similar results were obtained except for the fact that no significant correlation between the steepness of the frequency characteristics and the contractile state of the heart could be found when the end-diastolic pressure was kept constant.     

Genetic and endocrine studies of the pregnancy-blocking pheromone of mice.

Secretion of the pregnancy-blocking pheromone was stimulated by injection of depo-testosterone cypionate into females and males of inbred strains of mice which do not normally secrete the pheromone. Testosterone treatment of SJL males altered pheromone secretion so that pregnancies were blocked when the stud male was of the same inbred strain; an event that does not normally occur. Injection of epiandrosterone, androstenedione, androsterone or testosterone significantly increased pheromone secretion in SJL females, but progesterone and dehydroepiandrosterone were ineffective. Kidney weights were significantly increased by administration of androgen metabolites and the possibility of the kidney being the site of pheromone synthesis is discussed. The preputial gland can be excluded as the site of pheromone synthesis since males which are hemizygous for the Tabby-J gene and have no preputial glands blocked pregnancies as effectively as their normal littermates. Preliminary results are also presented concerning the isolation of the pregnancy-blocking pheromone from urine. Urine was analysed by gas chromatography and a peak was observed whose concentration could be correlated with secretion of the pheromone, although the compound(s) has not been identified or tested for biological activity.