Acetamide degradation by a continuous-fed batch culture of Bacillus sphaericus.

The methanogenesis of acetamide occurs through a two-step reaction in methanogenic sludges. First, acetamide is hydrolyzed to acetate and ammonia by a strict aerobic bacterium (Bacillus sphaericus), then acetate is used by Bacillus as carbon source or converted to methane by methanogens. In this work, the kinetics of acetamide degradation by B. sphaericus was studied in a continuous reactor with biomass accumulation, fed with acetamide. The oxygen supplied was dissolved in the feed (6.4 mg/L) to resemble conditions in an anaerobic wastewater treatment reactor. A reaction in series model (acetamide --> acetate --> biomass) was used to find the kinetic parameters. Results show that B. sphaericus can hydrolyze acetamide in a second-order reaction with K1 = 1.1 L/g/d, implying that the amount of biomass determines the rate and that no reaction will take place at specific loading rates greater than 35 gAm/gX/d. Growth parameters on acetate, as carbon source, under limiting O2 conditions, are mu(max) = 0.102/d,Ks = 37 mg/L, Y = 0.081 gX/gAm.

[Ultrasonic measurement of the cerebellum in the newborn infant as a prognostic index of gestational age. (A preliminary study)]. / Medición del cerebelo por ultrasonido en el neonato como índice predictivo de edad gestacional. (Estudio preliminar).

This paper studies if cerebellum measurement by ultrasound is a point of prognostic value for evaluation of gestational age. Ninety-nine neonates of different age of gestation, were studied. Ultrasonographic study of the cerebellum was done in all the cases during the first 24 hours of life. It is suggested that the cerebellum measurement may be one indicator more for the evaluation of gestational age, and therefore of value to identify the products with growth disturbances.

[Genetic amniocentesis]. / Amniocentesis genética.

179 patients were studied by genetic amniocentesis (GA) in sessions of 3 punctures each. This was done in order to follow a prenatal diagnosis (PD) program and study amniotic fluid at the Hospital Regional 20 de Novembre (ISSSTE) between May 1983 and December 1987. The parameters taken were: age, indications, number of sessions, number punctures, echosonographic studies for gestational age, placental insertion, punction site, amniotic fluid volume, blood contamination, failures and handling of the patient. A low incidence of abortion is reported. We don't have cases of dripping of amniotic fluid or transvaginal haemorrhage. Multiple insertion of the needle and placental or vessel lesions of the cord, as causes of a fetal death are still argued if we have in mind avoiding chances; we didn't have those complications in our cases. The percent is low if there are not previous spontaneous abortions. 79% of the amniotic fluid samples were sent between the 15th and 17th weeks of pregnancy. For alpha fetus protein determination 12 and for biochemical studies 1, specially for beta-galactosidase level. This was done at the Biomedical Investigation Institute of the National Autonomous University of Mexico (in parents with generalized gangliosidosis GM1). Even though results were good, the technique has still risks and complications. An ultrasonic study of the procedures made by physicians with trustable experience is needed. Our country has the need to create more Prenatal Genetic Diagnosis Centers.