Therapeutic apheresis in low weight patients: technical feasibility, tolerance, compliance, and risks.

The use of therapeutic apheresis in very low weight patients is generally thought to have limitations, because of possible severe adverse reactions, potential risk related to the extracorporeal procedure, due to the low weight of the young patients. A careful therapeutic approach using appropriate precautions, and also introducing modifications to the standard procedure, can minimise the risk without compromising the efficacy of the plasmapheresis. The aim of the study was to evaluate apheresis tolerance and acceptability in children [Artif. Organs. 21 (1997) 1126] and infants [J. Clin. Apheresis 5 (1989) 21] with inherited lipid metabolism disorder, familial hypercholesterolemia (FH), primary hyperlipoproteinemia (lipoprotein phenotype I), and acute leukemia, weighing on average 20.55 kg. One thousand one hundred twenty three aphereses were completed. Three types of apheresis were performed: leukapheresis, plasma exchange, dextran sulphate cellulose (DSC) low density lipoprotein (LDL)-apheresis. Three different types of continuous flow systems were used. Technical adaptation depending on patients blood volume, body mass index, hematocrit, type of system used, permitted us to perform complete aphereses, obtaining a high degree of tolerance and acceptability of the treatment. The use of plasmapheresis is regarded to be an extreme therapeutic measure in children. However, when the need for such treatment is undebatable, plasmapheresis must be done. A well-trained and experienced team can overcome the technical difficulties in order to complete the procedures without complications. The most frequently observed adverse effects are vascular relative access insufficiency (2.0%), and mild hypotension (2.0%).     

Non-immune therapy of IgA glomerulonephritis

Summary: The involvement of the IgA immune system and complement components in IgA glomerulonephritis (IgAGN) has prompted the use of immunosuppressive drugs in therapy, but none has so far been shown to alter the natural course of the disease. Because most patients with IgAGN present during the chronic phase of their illness, at the time when the initiating immune events may no longer be active, nonimmune therapy which targets the common pathway of progressive renal injury is likely to be more useful. There is increasing evidence that angiotensin-converting enzyme inhibitors (ACEI) reduce proteinuria and renal injury in patients with IgAGN, and this effect may be observed in both normotensive and hypertensive patients. Yet to be determined is whether this effect is specific for ACEI and whatever other effective antihypertensive drugs may achieve a similar result. Fish oil has recently been shown to retard the progression of renal failure in patients with aggressive IgAGN, but a narrow therapeutic window appears to exist for this form of treatment. Antiplatelet agents on their own appear to be ineffective but in combination with anticoagulation (low dose warfarin) have been shown to have an antiproteinuric effect and may preserve renal function in patients with progressive disease. Future directions of non-immune therapy of IgAGN include evaluation of the renoprotective effect of angiotensin II receptor antagonists, free-radical scavengers and antilipid drugs. More work should also be done to identify factors which put the patients at risk of developing progressive disease and which predict therapeutic response, as has been done recently with the identification of the deletion polymorphism of the angiotensin-converting enzyme gene as a marker of progressive disease and therapeutic response to ACEI in patients with IgAGN.     

Myosin VIIA gene: heterogeneity of the mutations responsible for Usher syndrome type IB

Usher syndrome is recognized as the most frequent cause of hereditary deaf-blindness. Usher syndrome type I (USH1), the most severe form of the disease, is characterized by profound congenital sensorineural deafness, constant vestibular dysfunction, and retinitis pigmentosa of prepubertal onset. This form is genetically heterogeneous and five loci (USH1A-E) have been mapped thusfar. However, only the gene responsible for USH1 B (which accounts for approximately 75% of USH1 cases) has been characterized. It encodes a long-tailed unconventional myosin, myosin VIIA, with a predicted 2215 amino acid sequence. Primers covering the complete myosin VIIA coding sequence as well as the 3' non coding sequence were designed, allowing direct sequence analysis of each of the 48 coding exons and flanking splice sites in seven patients affected by USH1. Four novel mutations were thereby identified. The possibility should now be considered of a sequence-based prenatal diagnosis in some of the families affected by this very severe form of Usher syndrome.      

Cloning and characterization of two catechol 1,2-dioxygenase genes from Acinetobacter radioresistens S13

Two novel catechol 1,2-dioxygenase (C 1,2-O) genes have been isolated from an Acinetobacter radioresistens strain that grows on phenol or benzoate as sole carbon and energy source. Designated as catA(A) and catA(B), they encode proteins composed of 314 and 306 amino acids, whose deduced sequences indicate that they have approximately 53% identity, whereas their NH2-terminal and COOH-terminal regions have no sequences in common. This may explain their different thermal and pH stability. Polyclonal antibodies raised against an amino-terminal CatA(A) peptide or the whole CatA(B) protein were used to establish their inducible and differential expression patterns upon bacterial growth in phenol or benzoate. The CatA(A) protein (IsoA) was induced by both phenol and benzoate though with different kinetics, whereas the catA(B) product (IsoB) was constitutively produced at low levels that increased only during growth in the presence of benzoate.     

Production of immune interferon is regulated by more than one T cell subset: Lyt-1,2,3 and Qat-5 phenotypes of murine T lymphocytes involved in IFN-γ production in primary and secondary mixed lymphocyte reaction

Lymphocytes responsible for the production of IFN-γ (immune interferon) in primary and secondary mixed lymphocyte reactions have been characterized with antisera specific for the Lyt-1,2,3 and Qat-5 alloantigens. A comparison was made between selected T cell subsets with respect to their ability to proliferate, generate cytolytic activity and produce IFN-γ in response to H-2 alloantigens. The data indicate that (a) in primary mixed lymphocyte reactions, IFN-γ is produced by Lyt-1⁺, Qat-5⁺ and by Lyt-123⁺, Qat-5⁺ T cells, (b) in secondary mixed lymphocyte reactions, an additional T cell subset, which is Lyt-23⁺, Qat-5^?, participates in the generation of IFN-γ and (c) the production of IFN-γ does not correlate with either proliferation or the generation of cytotoxic lymphocytes.