goosecoid expression represses Brachyury in embryonic stem cells and affects craniofacial development in chimeric mice.

The homeobox gene goosecoid, originally identified in Xenopus, is expressed in the organizer or its equivalent during gastrulation in the frog, chick, zebrafish and mouse. To investigate the role of goosecoid in mouse development, we have generated embryonic stem cells that stably overexpress the murine homolog of goosecoid. These cells show a repression of the gastrulation-associated gene Brachyury. Interestingly, repression of Brachyury is conserved between Xenopus and mouse despite the lack of conservation of the Brachyury promoter. Further characterization of the goosecoid-overexpressing ES cells revealed that they maintain the expression of stage-specific embryonic antigen-1, and teratomas derived from goosecoid-overexpressing cells show the presence of cell types derived from all three germ layers. Some highly chimeric mice derived from goosecoid-overexpressing cells displayed skull defects. These observations suggest that goosecoid may play a role in specification of anterior mesendodermal fates and specifically in mouse craniofacial development.

Induction and differentiation of extra-embryonic mesoderm in the mouse.

Extra-embryonic mesoderm, derived at the time of gastrulation from the primitive streak, gives rise to several tissues that function to provide the embryo with nutrients, a means of waste disposal, and mechanical protection. Little is known about the differentiation of this tissue and about the growth and transcription factors involved. The present review focussed on growth and transcription factors that may be involved in differentiation of extra-embryonic mesoderm, and results from fate-mapping and transplantation studies. Methods in vitro available for assaying the effects of growth and transcription factors on development of extra-embryonic development are also discussed.

Overexpression of human glutathione S-transferase pi protects NIH 3T3 cells against (+/-)anti BPDE cytotoxicity but not tumor formation.

In order to explore the protective function of human glutathione S-transferase pi (GST-pi) in vitro and in vivo, transfected NIH 3T3 clones were examined in cytotoxicity assays using the carcinogen (+/-)anti-benzo(a)pyrene 7,8-diol-9,10-epoxide (BPDE) or inoculated into nude mice and treated with the carcinogen benzo(a)pyrene (BP) to induce tumor formation. The human GST-pi cDNA under the control of the murine alpha 2(I)collagen promoter was transfected into NIH 3T3 cells and G418 resistant clones were analyzed by Southern, northern, western, and two-dimensional analysis. Clone A2 stably expressed human GST-pi and has 2.5-fold greater activity toward the substrate 1-chloro-2,4-dinitrobenzene and a 1.7-fold increase in LD50 for BPDE in vitro when compared to control-transfected clone G3. This increase in protection, however, did not prevent the formation of BP-induced tumors in vivo.

Comparison of blood gas and electrolyte test results from the Gem-Stat and CDI-300 versus a conventional laboratory analyzer.

Continuous blood gas monitoring devices have been an aid to the perfusionist since the introduction of the oxygen saturation meters of the early 1980s. Since that time, the perfusionist has had to decide between continuous versus intermittent sampling, and on-line (an analyzer that can automatically sample either at prescribed intervals and/or on demand) versus in-line devices (monitors that continuously sample and display results). This report compares the continuous, in-line CDI-300 blood gas monitor and the Mallinckrodt Gem-Stat blood gas analyzer using intermittent sampling with the Corning 278 blood gas analyzer and 2500 Co-Oximeter. Thirty samples were taken, one per 30 patients, for comparison. Five samples were disqualified from the study. When comparing the remaining 25, the Gem-Stat results to the Corning 278 blood gas analyzer results, all measured values (arterial pH, pCO 2, pO 2, venous pO 2, Na, K and Hct) correlated greater than 0.5000 with a p value of less than 0.001. The exception was the ionized calcium value which had a correlation of 0.2473 with a p value of less than 0.232. When comparing the CDI-300 results to the Corning 278 blood gas machine results, all measured values (pH, pO 2, pCO 2, and venous pO 2) correlated greater than 0.5000 with a p value of less than 0.003 or better. When comparing the Gem-Stat results to the CDI results, all measured values (pH, pCO 2, pO 2 and venous pO 2) correlated greater than 0.5000 with a p value of less than 0.002 or better.

Reduction of canine myocardial infarct size by CI-959, an inhibitor of inflammatory cell activation.

CI-959, a cell-activation inhibitor that prevents the formation of oxygen-derived free radicals by inflammatory cells, was studied to determine its effects on myocardial infarct size and subsequent scar formation in dogs. The left circumflex coronary artery was occluded for 90 min, followed by 6 h of reperfusion. Drug infusion was started 15 min before reperfusion at a loading dose of 8 mg/kg i.v., followed immediately by 2 mg/kg i.v. infused over 80 min. The infarct size, assessed by TTC staining techniques, was significantly reduced in 12 dogs treated with CI-959 (23.3 +/- 3.6% of the area at risk) when compared to 11 vehicle-treated animals (35.5 +/- 4% of the area at risk, p less than 0.05). This reduction in infarct size was not attributed to changes in regional myocardial blood flow, as measured by radioactive microspheres, or to a reduction in myocardial oxygen demand, as estimated by changes in the rate-pressure product. The scar thickness, measured after a 6-week recovery period in 9 animals treated with CI-959, was not significantly reduced in comparison with 11 controls. In vitro, CI-959 effectively inhibited oxygen free radical formation by canine neutrophils. The results of this study show that CI-959 significantly reduces the myocardial infarct size without causing scar thinning, which might lead to ventricular aneurysm, and suggests the most likely mechanism for its beneficial action is the prevention of formation of toxic oxygen radicals.

Antihypertensive profile of the angiotensin-converting enzyme inhibitors CI-906 and CI-907.

CI-906 and CI-907, new orally active nonsulfhydryl angiotensin-converting enzyme inhibitors, were examined for antihypertensive effects in unanesthetized hypertensive rats and dogs. In two-kidney, one-clip Goldblatt hypertensive rats, single oral daily doses (0.03-30 mg/kg) produced dose-dependent decreases in blood pressure; a single 3 mg/kg oral dose lowered blood pressure to normotensive levels. In spontaneously hypertensive rats, 30 mg/(kg X day) orally administered for 5 consecutive days achieved the same blood pressure decrease as that obtained on the first day in the renal hypertensive rats. In diuretic-pretreated renal hypertensive dogs, a 10 mg/kg oral dose decreased blood pressure by 25%. No adverse side effects were observed with CI-906 and CI-907 in any of the conscious animals. These studies indicate that CI-906 and CI-907 are potent, orally active antihypertensive agents without any apparent limiting side effects.

Antihypertensive effects of CI-907 (indolapril): a novel nonsulfhydryl angiotensin converting enzyme inhibitor.

CI-907 is a new orally active nonsulfhydryl angiotensin converting enzyme (ACE) inhibitor. Monoester (prodrug) and diacid forms produced concentration related ACE inhibition in guinea-pig serum (IC50 for monoester, 1.7 X 10(-7) M and for diacid, 2.6 X 10(-9) M). In isolated rabbit aortic rings and in rat and dog autonomic studies, CI-907 is highly specific in suppressing the contractile or pressor responses to angiotensin I. In two-kidney, one-clip Goldblatt hypertensive rats, single daily doses (0.03-30 mg/kg p.o.) produced dose-dependent decreases in blood pressure; 3 mg/kg lowered blood pressure to normotensive levels. In the spontaneously hypertensive rat, subacute administration of CI-907 (30 mg/kg/day for 5 days) produced the same decrease in blood pressure as that obtained in the renal hypertensive rat. In diuretic-pretreated renal hypertensive dogs, 10 mg/kg normalized blood pressure. For equivalent drops in blood pressure, heart rate increases were less in CI-907 than in enalapril-treated renal hypertensive dogs. No side effects were observed with CI-907 in any of the conscious animals. The antihypertensive response to CI-907 (0.03-1.0 mg/kg p.o.) was found to correlate with inhibition of vascular tissue ACE, but not plasma or brain ACE in two-kidney, one-clip renal hypertensive rats. These studies indicate that CI-907 is a potent antihypertensive agent with a heart rate profile different from enalapril.