N omega-nitro-L-arginine, an inhibitor of nitric oxide synthesis, increases blood pressure in rats and reverses the pregnancy-induced refractoriness to vasopressor agents.

OBJECTIVE: With N omega-nitro-L-arginine, a potent inhibitor of nitric oxide synthesis, we tested the hypothesis that nitric oxide plays a functional role in the blunted pressor responsiveness seen during pregnancy. STUDY DESIGN: A group of six pregnant rats were instrumented on the fourteenth day of gestation and studied on days 19 and 20, as well as 7 days post partum. Another group of six virgin rats were similarly prepared and used 5 days after surgery. Blood pressure and heart rate were monitored in conscious freely moving animals before and during the administration of drugs or placebo. Results were analyzed, by one-way repeated-measures analysis of variance, with Dunnett's t test, or by paired t test where applicable. RESULTS: Basal mean arterial pressure and heart rate were 90.8 +/- 3.0 mm Hg and 330 +/- 6 beats/min in pregnant animals and 107.1 +/- 3.2 mm Hg and 315 +/- 7 beats/min in nonpregnant animals. Pressor responses to angiotensin II, vasopressin, and norepinephrine were attenuated in gravid animals. Infusion of N omega-nitro-L-arginine significantly and in a dose-dependent manner increased mean arterial pressure and reduced heart rate. These effects could be completely reversed by L-arginine administration. Changes in mean arterial pressure were higher during pregnancy as compared with postpartum values. N omega-nitro-L-arginine infusion potentiated pressor responses to all three vasopressors, resulting in dose-response curves that were significantly shifted to the left, making them virtually identical in pregnant and postpartum rats. CONCLUSION: Our data support the emerging view that nitric oxide plays a key role in the regulation of blood pressure during pregnancy.     

Biochemical, clinical and genetic analysis of various aminoacidopathies (non-ketotic hyperglycemia, maple syrup urine disease, histidinemia, tyrosinemia)]

The genetical types were classified according to the clinical findings and biochemical results in cases of 13 newborn/children suffering from various aminoacidopathies. The genetical types were: 3 neonatal and 4 infantile types were found out of 7 non-ketotic disease (MSUD) patient was infantile type with 9.1 per cent keto acid decarboxylase activity in leukocyte homogenate. Among the 3 histidinemic patients 1 was severe neonatal type and 2 cases were chronic types. The 2 treated tyrosinemic children proved to be type III. (chronic with rickets).     

Interaction of tick/borne encephalitis virus with mouse peritoneal macrophages. The effect of antiviral antibody and lectin.

The interaction between tick-borne encephalitis (TBE) virus strain Hypr and mouse peritoneal macrophages was followed in vitro. Macrophages from juvenile mice (8-11 days old) were more permissive for virus infection than macrophages from adults (25-30 days old). Anti-TBE antibody in the subneutralizing dose increased the number of infected macrophages as well as virus release into the culture medium. Concanavalin A (con A), which bound to the virus as well as to the surface of macrophages, increased the uptake of the virus, but it neither enhanced the number of infected cells nor increased the virus release into medium. Antibody and lectin can modify the interaction between TBE virus and macrophages. Nevertheless, the Fc receptor-mediated endocytosis seems to be a necessary prerequisite for enhancing the effect of a ligand.     

New aspects of the biology of Entamoeba histolytica]

To determine the mechanism of mitosis in E. histolytica, a study was carried out with axenic cultures of trophozoites in Coplin jars with glass slides to stain them in situ with Giemsa and fluorescent antibodies for actin. Tobuline and myosin. Sedimented amoeba of cultures were used also for ultrastructural studies after glutaraldehyde fixation, and inclusion in spon-araldite. Giemsa stained trophozoites showed duplication by budding or fission with production of polykaryons, mononuclei, micronuclei and apparent polyploidy and DNA reduction. Tubuline was present in nuclei and cytoplasm, actin and myosin had a peripheral distribution with low contents of the latter in large amoeba, resulting in polynucleated cells. The findings are suggestive of endomeiosis with chromosomal recombination which would render virulent and non virulent strains producing either invasive or asymptomatic amoebiasis.     

Characterization, localization and actions of endothelins in umbilical vessels and placenta of man.

Endothelin-like immunoreactivity was observed in the endothelial lining of umbilical vein and artery as well as in the epithelium of the amniotic membrane. High levels of endothelin-like immunoreactivity (0.4-1.4 pmol g-1) were detected in human amniotic membrane, umbilical vessels and placenta. The concentration of endothelin-like immunoreactivity in the amniotic fluid was much higher (77 pmol l-1) than in umbilical cord plasma (10 pmol l-1). Characterization by reverse phase HPLC revealed that most of the endothelin-like immunoreactivity eluted in the position of synthetic endothelin-1 or oxidized endothelin-1. Specific, high affinity binding sites for endothelin-1 were present in placenta and umbilical artery. Endothelin binding sites were also found in cultured smooth muscle cells from the umbilical artery and vein. In the placenta, endothelin-1 and -3 were almost equipotent as competing ligands for endothelin-1 binding sites, whereas in the umbilical artery endothelin-3 was much less potent than endothelin-1. Scatchard analysis of the binding for placental membranes displayed a straight line (r = -0.994) indicating a single class of endothelin receptors with a Kd-value of 80 pmol l-1 and Bmax of 113 fmol mg-1. Endothelin-1 caused potent contractions of umbilical arteries and veins with threshold effects at 10 pmol l-1 while endothelin-3 had no contractile effect up to 10(-7) mol l-1. It is concluded that endothelin-1 predominates over other endothelins in umbilical vessels, amnion and placenta, and high levels of endothelin-1 was observed in foetal circulation and amniotic fluid. Endothelin-receptors seem to be of different types in placenta (ETB type) and umbilical vessels (ETA type).     

Successful surgical correction of persistent truncus arteriosus by an aortic homograft]

After palliative procedure a 2 years old girl with congenital heart disease was corrected with aortic homograft. Truncus arteriosus is a rare congenital heart disease and this is the first successfully corrected case in our country. Using homograft in this age group improves the early and late result of this type of corrective surgery.