Jelly plug dissolution in Discoglossus pictus eggs (Anura) involves peroxidase-like activity and oxidative opening of disulphide bonds

In amphibian eggs the formation of a capsular chamber is one of the most striking events occurring either upon oviposition or after fertilisation. In the egg of the anuran Discoglossus pictus a capsular chamber forms following fertilisation or activation; the egg with its vitelline envelope rotates in this chamber according to gravity. Previous work showed that the chamber is the product of plug dissolution. The plug is a lens-shaped jelly coat, typical of Discoglossus, covering only part of the animal hemisphere. Its dissolution is caused by material released from the egg about 15 min after fertilisation through exocytosis of at least two types of vacuoles. Liquefaction of the plug correlates with the reduction of disulphide bonds present in the jelly matrix. In this study we investigated the nature of the substances released from the egg and some changes occurring in the plug during liquefaction. SDS-PAGE showed that the proteic profile of the plug changes dramatically after fertilisation, confirming proteic cleavage in the plug matrix during its dissolution. Through in vitro tests and electrophoretic analysis of the Ringer solution in which the egg exudate was collected, an increase in the activity of the solution was determined in the presence of hydrogen peroxide, and peroxidase activity was depicted in the egg exudate. The presence of free thiol groups and cysteic acid residues (or cysteine sulphinic acid) in the plugs of activated eggs was established, suggesting that during plug dissolution some disulphide bonds are oxidatively opened. This suggests that enzyme(s) with peroxidase activity are released following fertilisation. We surmise that such enzymes are contained in the intraovular vacuoles the exocytosis of which triggers the onset of plug liquefaction. The possible release of hydrogen peroxide from the egg is discussed.

Post-fertilization changes in Discoglossus pictus (Anura) eggs result in the formation of a capsular chamber where the egg rotates

Discoglossus pictus is one of the few anurans with an egg where a capsular chamber forms as a consequence of fertilization; the egg with its vitelline envelope rotates in this chamber according to gravity. We investigated the formation of the capsular chamber through various experimental cytochemical and ultrastructural approaches, and found that it is the product of plug liquefaction. The plug is a lens-shaped jelly coat typical of Discoglossus, and covering only part of the egg animal half. About 15 min after fertilization, granular material coming from the egg enters the plug, which gradually dissolves and, once liquefied, reorganizes itself around the entire egg, thus forming the chamber. This process goes through stages of rearrangement of the 25-A- and 250-A-thick filaments which constitute the plug matrix. The material entering the plug derives from the exocytosis of two vacuole types, with electron transparent and granular PAS-positive contents. Liquefaction of the plug correlates with the reduction of disulfide bonds present in its matrix. Furthermore, in vitro tests showed that the substances released from the egg are active in selectively dissolving only the plug, and lose activity upon boiling.

Clinical relevance of immunological dissection in T-ALL: a report on 20 cases with stem cell (CD7+, CD4-, CD8-, CD1-) phenotype

In a prospective study on 44 cases of T-cell origin acute lymphoblastic leukemia, 20 patients were found to display an immature immunophenotype (CD7+, CD4-, CD8-, CD1-) and were classified as T-stem cell leukemia (T-SCL). Twenty-four patients expressed CD4 and/or CD8 antigens on their blast cells, designated T acute lymphoblastic leukemia (T-ALL). The T-SCL subset showed a significantly higher median age, a more frequent incidence of extramedullary leukemia, a morphology L1 in most cases, and a poor response to treatment in terms of either complete remission rate or median survival duration. In addition, significant differences between the two groups were found in evaluating the number of days of blast disappearance from peripheral blood, of CR achievement, and of neutrophils and platelets recovery. We conclude that T-SCL represents a distinct clinical entity, characterized by a poor response to ALL conventional chemotherapy. Alternative therapeutic approaches should be developed for patients suffering from this form of leukemia, to modify its severe prognosis.

Nutritional status and growth in children with chronic hepatitis B

As reported for other chronic liver diseases, hepatitis B virus (HBV) chronic infection might result in malnutrition. In order to establish whether this disease could be responsible of malnutrition and hence influence growth, 75 children, chronically infected with HBV, have been followed up for 4 years. Thirty-one of them had chronic active hepatitis (CAH), 25 chronic persistent hepatitis (CPH), 14 chronic lobular hepatitis (CLH), and five cirrhosis (three active, two inactive). The nutritional status was evaluated every 12 months, with careful physical and laboratory examinations. General nutritional status was estimated according to Waterlow criteria (13, 14). At our first observation, 50 children were following a balanced diet with a caloric intake adequate for age and weight, whereas 25 were on a low-fat diet, begun in the belief of its therapeutic value. For seven patients of this second group, the caloric intake was below the daily requirement. The latter group showed a growth failure in weight when they were first seen at our center and gained weight when the dietary intake was normalized. However, no biochemical feature of malnutrition was observed in all the 75 children. At the end of the follow-up period, the nutritional status was satisfactory for all of them.

[Report on l7 years of studies of human African trypanosomiasis caused by T. gambiense in children 0-6 years of age]

The authors present 227 cases of human African trypanosomiasis in children between 0 and 6 years, which have been observed for 17 years in the hyperendemic area of Fontem, Cameroon. These cases deal with a subject seldom described in medical literature. The authors especially insist on the velocity of both the contamination and involvement of the nervous system, as well as on the difficulty in settling a diagnosis when failing consider the notion of endemic area. On the other hand, they stress the fact that the efficiency of arsenical treatment is not more dangerous for children than for adults. Finally, they confirm the existence of congenital trypanosomiasis, which proves to be as important from the epidemiological point of view than from the strategical means to be used to identify this disease.