NOTES ON THE OXYGEN ELECTRODE

Using the Clark type of electrode it was observed that the ratioof the current obtained for water equilibrated with air to thezero or background current is a constant. From this it was shownthat a series of calibration curves for the same electrode hasa common point of intersection on the ordinate which is termedthe electrode constant. It is suggested that when this valuehas been determined for a particular electrode, rapid calibrationis possible by use of the constant and the current obtainedfrom water equilibrated with air. The experimental proof andpossible theoretical background for this procedure are presented.     

PREMATURE URACHAL CLOSURE INDUCES HYDROURETERONEPHROSIS IN MALE FETUSES

Purpose

Congenital hydronephrosis is more common in male individuals. We investigate whether an alteration in fetal bladder function induced by premature urachal closure contributes to fetal hydronephrosis, consequently explaining this male predominance.

Materials and Methods

The urachus was clipped in 8 male and 4 female ovine fetuses at 95 days of gestation (term 140 days). Subjects were sacrificed, and the urinary tract was assessed at 109 and 116 days of gestation in 3 and 1 male fetuses, respectively, and at term in 4 male and 4 female lambs.

Results

At 109 and 116 days of gestation 3 of the 4 male fetuses had upper tract dilatation. At term no female but 4 male lambs had hydroureteronephrosis, including some with marked pelvic dilatation and parenchymal thinning. At term mean bladder weight in the male animals with urachal clipping was 5.28 gm. (range 3.5 to 8.2), which was significantly greater than normal (p = 0.02). Bladder weight at term in the female lambs with urachal clipping was not different from normal values. Histological evaluation of the kidneys in the male lambs revealed cortical thinning and loss of medullary tissue, while the overall renal architecture was well preserved.

Conclusions

Our observations indicate that normal ovine fetal urinary tract function and drainage depend on urachal function and the timing of urachal closure. Therefore, fetal hydronephrosis is associated with this alteration in bladder function but it may also be associated with other factors, such as bladder sphincter maturation or prostate development. Our experiment shows that hydroureteronephrosis develops in ovine fetuses when all bladder drainage occurs via the urethra. This condition may be an amplification of the differences in bladder outlet resistance in human fetuses, which may explain the male predominance in the various forms of hydroureteronephrosis.     

Recombinant human G-CSF-mobilized peripheral blood stem cells for second allogeneic transplant after bone marrow graft rejection in children

Two children affected by severe aplastic anaemia and sickle cell anaemia rejected the allogeneic bone marrow transplantation from an HLA-matched unrelated volunteer and an HLA-identical sibling, respectively. In both cases a second transplant using granulocyte-colony stimulating factor (G-CSF) mobilized peripheral blood stem cells (PBSC) was performed. Donors were the HLA-haploidentical mother and the same HLA-identical sibling who was employed for the first marrow allograft, respectively. Treatment with G-CSF and PBSC collection were well tolerated. Both patients had engraftment of donor haemopoiesis and did not experience severe graft-versus-host disease. These cases confirm that PBSC transplant should be considered as a feasible treatment to reverse graft failure in paediatric patients.     

The 35/50 kDa surface antigen of Trypanosoma cruzi metacyclic trypomastigotes, an adhesion molecule involved in host cell invasion

We have previously shown that monoclonal antibodies directed to the 90 kDa glycoprotein and the 35/50 kDa glycoconjugate, present on the surface of Trypansoma cruzi metacyclic trypomastigotes, inhibited host cell invasion. Here we investigated whether these molecules could be the ligands for the target cell receptor. Binding assays were performed by incubating Vero cells with sonicated parasite extract. Detection of bound parasite components was carried out by using monoclonal antibodies (MoAbs) 1G7 and 10D8, which recognize the 90 kDa and the 35/50 kDa antigens respectively. These experiments revealed that the 35/50 kDa glycoconjugate of metacyclic forms, but not the 1G7-reactive antigen, binds to Vero cells. The purified 35/50 kDa antigen bound to Vero cells and inhibited the entry of metacyclic forms in a dose-dependent manner. Although to a lesser extent, an immunologically related 35/50 kDa antigen of non-infective epimastigotes also bound to Vero cells but it was unable to inhibit parasite penetration at a concentration (100 μg/ml) in which metacyclic antigen exhibited more than 60% inhibition. All these data suggest that the metacyclic 35/50 kDa surface glycoconjugate is a ligand to the host cell in the process ofT. cruzi invasion.