Differential inhibition of interleukin 2- and interleukin 4-mediated human B cell proliferation by ionomycin: a possible regulatory role for apoptosis

Surface immunoglobulin (Ig) cross-linking by anti-IgM (mu) antibodies leads to B cell activation resulting in numerous early biochemical events including an increase in intracellular [Ca2+]. Furthermore, anti-mu-activated B cells become able to proliferate in response to interleukin (IL)2 and IL4. These studies examined the effect of the calcium ionophore ionomycin, an enhancer of cytoplasmic [Ca2+] levels, on IL2 and IL4-mediated proliferation of anti-mu-stimulated normal human B cells. Ionomycin inhibited the proliferative response of anti-mu-activated B cells to IL4. In contrast, IL2 and phorbol 12,13 dibutyrate (PBu2)-mediated B cell proliferation was refractory to the growth inhibitory effects of ionomycin. In an attempt to delineate a possible mechanism(s) for this differential growth effect of ionomycin, we first studied direct effects of ionomycin on activated B cells. Our data suggested that ionomycin induced DNA fragmentation in anti-mu-costimulated B cells. Interestingly, in contrast to PBu2, IL4 did not prevent ionomycin-dependent DNA fragmentation. Importantly, H7, an inhibitor of protein kinase C activation, down-regulated only the IL2 and PBu2-driven B cell proliferation but not B cell proliferative response to IL4. These results suggest that putative protein kinase C activation, either by direct treatment with phorbol ester or during IL2 signaling, counteracts the inhibitory effects of ionomycin. In contrast, IL4 signaling does not exhibit the same protective properties.     

Meningeal hemorrhage and Hermansky-Pudlak syndrome

We studied the case of a young patient affected by a Hermansky-Pudlak syndrome: oculocutaneous albinism of variable intensity with essentially an haemorrhagic diathesis due to a "pool vide" thrombopathy. In beginning the only obvious symptom was a nystagmus and an ocular albinism. Cerebrospinal hemorrhage has up to now never been reported to our knowledge. Healthy carriers can be detected by ophthalmological examination and hematological coagulation tests. Albinos must benefit of systematical coagulation tests in order to prevent drug induced haemorrhagic accident.     

Association of spheno-orbital dysplasia with plexiform neuroma in von Recklinghausen's neurofibromatosis

We report a case of plexiform neurofibroma of the upper eyelid associated with spheno-orbital dysplasia in a 18-year-old woman with von Recklinghausen neurofibromatosis. Visual acuity was 20/40 in the right eye and 20/20 in the left. Plexiform neurofibroma involving the right upper eyelid was associated with mild ptosis and ipsilateral facial hypertrophy. Biomicroscopic examination showed lisch nodules. Funduscopic examination, visual field and neurologic examinations were normal. Café au lait spots involved the trunk with neck plexiform neurofibroma. Computed tomography disclosed spheno-orbital dysplasia. The patient's status remained unchanged at 6 months follow-up. Cranial features of von Recklinghausen neurofibromatosis are found in 3 to 7% of patients. In patients with plexiform neurofibroma of the eyelid the ophthalmologist should look for associated spheno-orbital dysplasia.     

Curative treatment of non-metastatic esophageal cancer: concomitant chemoradiotherapy and high-dose-rate endoluminal curietherapy boost

OBJECTIVES: The aim of this study was to evaluate the feasibility, toxicity, and efficacy of a curative combination of chemo-radiotherapy with high-dose-rate brachytherapy (HDRB) in patients with non metastatic esophageal cancer. PATIENTS AND METHODS: Fifty-two patients with esophageal carcinoma were treated with > 50 Gy external irradiation, concomitant chemotherapy (5FU-CDDP) followed by HDRB delivering 12.5 Gy (6-20) as a boost. Twelve patients were stage I, 20 stage IIa, 5 stage IIb, and 13 stage III, 1 Tis, 1 stage N unknown. Surgery was not indicated for medical reasons. RESULTS: The response rate was 96%, with complete response rate 85%. The 1-, 3-, 5-year overall survival rates were 78%, 33%, and 22% respectively. A local failure occurred in 32%, and distant metastasis in 16%. Severe (grade 3, 4) acute toxicity occurred in 6 cases, severe late toxicity in 2 cases and there was 1 toxic death. Tumoral length > or = 5 cm and stage IIa, IIb and III versus stage 1 indicated poor prognosis. CONCLUSION: This regimen is feasible and well tolerated. The 5-year overall survival is 22%, but the local failure rate is still very high. These results are encouraging and will be prospectively evaluated with currently ongoing randomized trial.     

The molecular basis of ubiquitin-like protein NEDD8 deamidation by the bacterial effector protein Cif

The cycle inhibiting factors (Cifs) are a family of translocated effector proteins, found in diverse pathogenic bacteria, that interfere with the host cell cycle by catalyzing the deamidation of a specific glutamine residue (Gln40) in NEDD8 and the related protein ubiquitin. This modification prevents recycling of neddylated cullin-RING ligases, leading to stabilization of various cullin-RING ligase targets, and also prevents polyubiquitin chain formation. Here, we report the crystal structures of two Cif/NEDD8 complexes, revealing a conserved molecular interface that defines enzyme/substrate recognition. Mutation of residues forming the interface suggests that shape complementarity, rather than specific individual interactions, is a critical feature for complex formation. We show that Cifs from diverse bacteria bind NEDD8 in vitro and conclude that they will all interact with their substrates in the same way. The "occluding loop" in Cif gates access to Gln40 by forcing a conformational change in the C terminus of NEDD8. We used native PAGE to follow the activity of Cif from the human pathogen Yersinia pseudotuberculosis and selected variants, and the position of Gln40 in the active site has allowed us to propose a catalytic mechanism for these enzymes.