Prophylaxis with FEIBA in paediatric patients with haemophilia A and inhibitors.

The benefits shown with factor VIII (FVIII) prophylaxis relating to joint health and quality of life (QoL) provide the rationale for FEIBA prophylaxis in haemophilia A patients with persistent FVIII inhibitors. FEIBA has previously shown efficacy in preventing bleeds in inhibitor patients who failed to respond to, or were ineligible for immune tolerance induction (ITI). The study examined the outcome of paediatric patients undergoing long-term FEIBA prophylaxis. A retrospective chart review included severe haemophilia A patients with persistent inhibitors aged ≤13 years at the start of FEIBA prophylaxis. Baseline characteristics captured dose, frequency of prophylaxis, history of inhibitor development, including baseline titre, historical peak titre and history of ITI. Outcome measurements included annual bleed rate before and during FEIBA prophylaxis, joint status and school days missed. Sixteen cases of FEIBA prophylaxis from two centres are presented. The mean age of subjects at prophylaxis initiation was 7.5 ± 3.6 years and median baseline inhibitor titre was 23 (range 3.1-170) BU. Prior to prophylaxis initiation, median annual joint bleeds among all patients was 4 (0-48), which dropped significantly after the first year of prophylaxis, to a median annual joint bleed rate of 1 (0-7; P = 0.0179). Subsequent years (median = 9) of prophylaxis therapy demonstrated similarly low annual joint bleed rates. There were no life-threatening bleeds, no viral seroconversions or thrombotic events during FEIBA prophylaxis treatment. FEIBA prophylaxis was effective for preventing joint bleeds and subsequent joint damage, delaying arthropathy and improving outcomes in children with haemophilia A and inhibitors to FVIII, who failed or were ineligible for ITI.

Consequences of switching from prophylactic treatment to on-demand treatment in late teens and early adults with severe haemophilia A: the TEEN/TWEN study.

Although many people with haemophilia discontinue prophylaxis in their late teens or early adulthood, the consequences of this decision are largely not known. This 18-month, observational, case-controlled, multicentre study evaluated long-term prophylaxis and the consequences of switching from prophylaxis to on-demand treatment in late teens and young adults with severe haemophilia A. Participants with haemophilia (aged 14-29 years) on prophylaxis ≥ 60% of the time for the 5 years before study entry were enrolled into 1 of 2 prospective or 1 retrospective group. Group 1 was prophylaxis, group 2 had voluntarily discontinued prophylaxis ≤ 12 months before study entry and group 3 had voluntarily discontinued prophylaxis ≥ 13 months before study entry. Assessments included bleeding frequency (primary endpoint), Haemo-QoL-A health-related quality of life (HRQoL) scores, Gilbert score, development of target joints, Haemophilia Activities List, Godin Leisure-Time, treatment satisfaction and State-Trait Anxiety Inventory (secondary and exploratory endpoints). Descriptive statistics were provided for all variables. Thirty-eight participants (group 1, n = 22; group 2, n = 5; group 3, n = 11; median age, 19.5 years) were enrolled. The median annualized number of bleeding events was 0, 4.8 and 24 in groups 1, 2 and 3 respectively. HRQoL was lower in participants who discontinued prophylaxis vs. those who remained on prophylaxis. Changes in the remaining secondary and exploratory variables were small, but were generally worse in participants who discontinued prophylaxis. Following a switch from prophylaxis to on-demand therapy, the number of bleeding events increased and HRQoL worsened in late teens and young adults with severe haemophilia A.

Understanding FVIII/VWF complex--report from a symposium of XXIX WFH meeting 2010.

von Willebrand factor (VWF) has the capacity to form a complex with factor VIII (FVIII) which may modulate the immunogenicity of FVIII. It has been proposed that a significant fraction of recombinant FVIII (rFVIII) is unable to bind VWF. In an experimental model studied at the McMaster University in Canada, this VWF-unbound rFVIII fraction showed no coagulant function. Sulphation of FVIII tyrosine (Tyr) 1680 has been reported as essential for the interaction with VWF. In a study performed at the Grifols and CNS-CSIC in Spain, Tyr1680 sulphation was observed to be incomplete in rFVIII and complete in plasma-derived FVIII (pdFVIII). This could explain the incapability of some rFVIII molecules to bind VWF. Experience with immune tolerance induction (ITI) at the Bonn Haemophilia Centre indicates that only eradication of FVIII inhibitors allows safe haemostasis control and the option of prophylactic treatment. Various clinical trials were planned to evaluate the clinical role VWF-containing FVIII concentrates (FVIII/VWF). RES.I.ST (an acronym for REScue Immunotolerance STudy) is an international, prospective study aimed at assessing whether FVIII/VWF can induce ITI in high-risk haemophilia patients (RES.I.ST naïve) and whether patients who previously failed ITI with FVIII alone can be rescued with FVIII/VWF (RES.I.ST experienced). Enrolment started in November 2009. In the FAIReSt.Will (Fanhdi and Alphanate Italian Retrospective Study in Willebrand disease) study, 120 von Willebrand disease (VWD) patients treated with Fanhdi(®) or Alphanate(®) were retrospectively analysed. Efficacy was excellent and no side effects were reported. The ongoing PRO.Will study is a prospective, multicenter trial aimed at assessing the efficacy, safety and pharmacoeconomics of secondary long-term prophylaxis in patients with severe inherited VWD.

Identifying non-responsive bleeding episodes in patients with haemophilia and inhibitors: a consensus definition.

Assessing response to treatment with bypassing agents presents a substantial challenge in the treatment of patients with haemophilia and inhibitors. Rapid and accurate identification of bleeding episodes that are non-responsive to bypassing therapy with either Factor Eight Inhibitor Bypassing Activity (FEIBA; Baxter AG) or recombinant activated factor VII (rFVIIa; NovoSeven® , Novo Nordisk A/S) is essential to guide treatment decisions and optimize patient outcomes through early intervention. Although both bypassing agents are effective, differential responses to therapy necessitate multiple therapeutic options. This article provides a consensus definition for non-life-threatening joint and muscle bleeds that are non-responsive to bypassing agents. An international panel of seven physicians met in December 2008 to develop the consensus definition using a modified National Institutes of Health Consensus Development Conference method. The consequent definition of non-life-threatening bleeding episodes that are non-responsive to bypassing treatment provides a global picture of the condition of the patient during such an event. Identification of non-responsiveness is based on various criteria: pain, swelling/tension, mobility, patient perception and laboratory parameters. Criteria can be assessed subjectively by the patient/parent and/or objectively by the clinician. Although the precise timing of each determination should be at the discretion of the physician, bleeds should be considered non-responsive if the clinical situation meets the specified criteria 24 h from the start of treatment. Although it is not intended to replace clinical judgment, this definition can guide the optimal course of treatment for patients with haemophilia and inhibitors.

Experience with a third generation recombinant factor VIII concentrate (Advate) for immune tolerance induction in patients with haemophilia A.

The development of an inhibitor represents one of the most challenging complications in patients with haemophilia A. Optimal management is immune tolerance induction (ITI), typically through the administration of high doses of factor VIII (FVIII) concentrate. Among 12 patients who underwent ITI using Advate, a third-generation recombinant FVIII product that is free of animal and human protein additives, tolerance was achieved in nine (75%), including seven of 10 patients (70%) with high-titre inhibitors. ITI is ongoing in two patients and not yet successful; immune tolerance failed in the third patient. The median time to success was 4.0 months for group as a whole and for patients with high-titre inhibitors. Treatment was well tolerated, and no adverse events were observed. Advate was found to be equivalent to other FVIII products with regard to both ITI success rates and the incidence of adverse effects when used in these immune tolerance regimens.

Transfusion of multiple units of Js(b+) red blood cells in the presence of anti-Jsb in a patient with sickle beta-thalassemia disease and a review of the literature.

Jsb is a high-frequency antigen. Anti-Jsb is a rare alloantibody, and its clinical significance is poorly documented. We report a case in which a 12-year-old boy of Nigerian descent with sickle beta- thalassemia presented with multiple alloantibodies, including a panagglutinin and acute chest syndrome, necessitating the emergent transfusion of five units of phenotype-similar, crossmatchincompatible RBCs, four of which were given during an exchange transfusion. The patient was later found to have anti-Jsb. In addition to routine serologic methods to study the patient's RBCs and plasma, a monocyte monolayer assay (MMA) was performed on the patient's samples obtained 2 and 9 days after transfusion of the Js(b+) RBCs to determine the potential clinical significance of the anti-Jsb. Various laboratory parameters including quantitative hemoglobin fraction analyses were used to monitor for increased RBC destruction. The MMA reactivity of the patient's anti-Jsb increased from 2.3 percent on day 2 after transfusion to strongly positive at 88 percent and 66.5 percent (with and without the addition of fresh serum) 1 week later. MMA reactivity of greater than 5 percent is associated with increased RBC destruction. There was no clinical or laboratory evidence of increased hemolysis above baseline. However, decreased RBC survival was suggested by the relatively brisk decrease of the HbA1 fraction after the transfusions. The current case and others reported in the literature suggest that anti-Jsb may have limited potential for causing overt hemolysis. However, in patients with underlying hematologic disease, even mildly increased RBC destruction may pose problems clinically,and thus transfusion of Js(b+) RBCs should be avoided. In emergent situations, the potential of adverse effects of transfusing incompatible units should be balanced against the risk of withholding transfusion. Family members, especially siblings, should be considered as potential designated donors for patients with antibodies directed against high-frequency antigens. Available reports on anti-Jsb in the literature are also reviewed.

Prophylactic treatment with activated prothrombin complex concentrate (FEIBA) reduces the frequency of bleeding episodes in paediatric patients with haemophilia A and inhibitors.

Orthopaedic complications are among the most disabling sequelae occurring in patients with haemophilia and inhibitors. Recurrent or refractory joint bleeds can lead to joint damage, limiting mobility and causing permanent disability. Activated prothrombin complex concentrates (aPCCs) are effective in controlling acute, intraoperative and postoperative bleeding in patients with haemophilia and inhibitors. The relatively long, dosing interval and safety profile distinguish aPCCs as a well-suited option for prophylaxis. Therefore, it is postulated that long-term routine aPCC administration will decrease the frequency of recurrent bleeds, prevent damage to normal joints, and slow the progression of existing joint disease in patients with inhibitors. To test this hypothesis, a retrospective chart audit was performed. In four treatment centres, five patients were identified who received aPCC [Factor Eight Inhibitor Bypassing Activity, Anti-Inhibitor Coagulant Complex (FEIBA); Baxter AG, Vienna, Austria] prophylactically for > or = 6 months to prevent or reduce further joint deterioration, reduce bleeding and prevent postsurgical bleeding. Median treatment duration was 15 months and included administration of >1300 doses of aPCC. Dosages ranged from 50 to 75 U kg(-1) three times per week in four patients; one patient received 100 U kg(-1) daily. Orthopaedic status was maintained in four patients and improved in one; the frequency of bleeding episodes was reduced in all patients. No adverse events or thrombotic complications were reported. This case series demonstrates that routine aPCC administration may be used safely and effectively to reduce the occurrence of bleeding episodes and to maintain or improve clinical joint status in some patients.

Gas-phase basicities for ions from bradykinin and its des-arginine analogues.

Apparent gas-phase basicities (GB(app)s) for [M + H]+ of bradykinin, des-Arg1-bradykinin and des-Arg9-bradykinin have been assigned by deprotonation reactions of [M + 2H]2+ in a Fourier transform ion cyclotron resonance mass spectrometer. With a GB(app) of 225.8 +/- 4.2 kcal x mol(-1), bradykinin [M + H]+ is the most basic of the ions studied. Ions from des-Arg1-bradykinin and des-Arg9-bradykinin have GB(app) values of 222.8 +/- 4.3 kcal x mol(-1) and 214.9 +/- 2.3 kcal x mol(-1), respectively. One purpose of this work was to determine a suitable reaction efficiency 'break point' for assigning GB(app) values to peptide ions using the bracketing method. An efficiency value of 0.1 (i.e. approximately 10% of all collisions resulting in a deprotonation reaction) was used to assign GB(app)s. Support for this criterion is provided by the fact that our GB(app) values for des-Arg1-bradykinin and des-Arg9-bradykinin are identical, within experimental error, to literature values obtained using a modified kinetic method. However, the GB(app)s for bradykinin ions from the two studies differ by 10.3 kcal x mol(-1). The reason for this is not clear, but may involve conformation differences produced by experimental conditions. The results may be influenced by salt-bridge conformers and/or by conformational changes caused by the use of a proton-bound heterodimer in the kinetic method. Factors affecting the basicities of these peptide ions are also discussed, and molecular modeling is used to provide information on protonation sites and conformations. The presence of two highly basic arginine residues on bradykinin results in its high GB(app), while the basicity of des-Arg1-bradykinin ions is increased by the presence of two proline residues at the N-terminus. The proline residue in the second position folds the peptide chain in a manner that increases intramolecular hydrogen bonding to the protonated N-terminal amino group of the proline at the first position.

Therapeutic choices for patients with hemophilia and high-titer inhibitors.

Effective treatment of bleeding episodes in hemophilia with high titer inhibitors (HTI) remains a challenge, despite the fact that the therapeutic armamentarium has expanded considerably over the past few years. Treatment safety has improved with the availability of porcine factor VIII (FVIII) and bypassing products such as recombinant factor VIIa (rFVIIa), and plasma-derived activated Prothrombin Complex Concentrates (aPCCs) that are virally inactivated. The major drawbacks of rFVIIa and aPCCs are their unpredictable hemostatic effect, lack of laboratory assays to monitor efficacy and dosing frequency, and the risk of thrombosis. The proceedings of a one-day workshop of physicians who specialized in treating patients with hemophilia held in Vienna on May 13, 2000 have been summarized. In making a decision regarding the choice of product, physicians often consider the type of bleeding episode (life or limb threatening), age of the patient, volume of the reconstituted product, previous exposure to plasma derived products, cost, efficacy, and safety. For plasma naïve patients, to achieve rapid hemostasis a majority of the panelists used porcine FVIII (for patients who lack porcine inhibitory antibodies) or rFVIIa. For patients previously treated with plasma derived factors, in addition to the above concentrates, aPCCs were recommended. Although no data exists regarding safety and efficacy, switching products was routinely practiced either because of availability or cost. Furthermore, the panelists were uncertain about the efficacy of bypassing agents in the prevention of joint disease in inhibitor patients. The workshop participants felt that future research offers the best solution to resolve some of the dilemmas faced by clinicians and may help individualise treatment in a hemophilia patient with a high titer inhibitor.

Dissociation of multiply charged negative ions for hirudin (54-65), fibrinopeptide B, and insulin A (oxidized).

Collision-induced dissociation (CID) was performed on multiply deprotonated ions from three commercial peptides: hirudin (54-65), fibrinopeptide B, and oxidized insulin chain A. Ions were produced by electrospray ionization in a Fourier transform ion cyclotron resonance mass spectrometer. Each of these peptides contains multiple acidic residues, which makes them very difficult to ionize in the positive mode. However, the peptides deprotonate readily making negative ion studies a viable alternative. The CID spectra indicated that the likely deprotonation sites are acidic residues (aspartic, glutamic, and cysteic acids) and the C-terminus. The spectra are rife with c, y, and internal ions, although some a, b, x, and z ions form. Many of the fragment ions were formed from cleavage adjacent to acidic residues, both N- and C-terminal to the acidic site. In addition, neutral loss (e.g., NH3, CH3, H2O, and CO2) was prevalent from both the parent ions and from fragment ions. These neutral eliminations were often indicative of specific amino acid residues. The fragmentation patterns from several charge states of the parent ions, when combined, provide significant primary sequence information. These results suggest that negative mode CID of multiply deprotonated ions provides useful structural information and can be worthwhile for highly acidic peptides that do not form positive ions in abundance.

Evolution of the ascidian anural larva: evidence from embryos and molecules.

Most ascidians pass through a tadpole (urodele) larval stage, although some species have derived a tailless (anural) larva. New insights into the evolution of anural larvae in the Roscovita clade of molgulid ascidians were obtained from studing embryonic development of the transitional anural species Molgula bleizi and from phylogenetic analysis based on muscle and cytoskeletal actin gene sequences. By observing in vitro fertilized eggs, we found that M. bleizi, previously described as a typical anural developer, actually forms a short immotile tail during embryogenesis. The short tail contains notochord lineage cells, which undergo abbreviated morphogenetic movements but eventually arrest in development. Molgula bleizi tail muscle lineage cells produce the muscle enzyme acetylcholinesterase (AChE) but do not express muscle actin genes. The presence of a short tail, a vestigial notochord, and AChE-positive muscle cells suggest that M. bleizi is a recently derived anural species. An M. bleizi larval muscle actin gene (MbMA1) was isolated, sequenced, and shown to be a pseudogene based on critical deletions in its coding region that would result in a nonfunctional actin protein. The mutations in MbMA1 are distinct from and have evolved independent of the larval muscle actin pseudogenes MoccMA1a and MoccMA1b in Molgula occulta, another anural developer in the Roscovita clade. Pseudogene formation explains the absence of muscle actin mRNA in M. bleizi embryos. The 3' untranslated region of an M. bleizi cytoskeletal actin gene was also isolated and sequenced. Phylogenetic trees reconstructed using muscle and cytoskeletal actin sequences suggest that the anural developer M. bleizi evolved prior to the divergence of the urodele developer Molgula oculata and the anural developer M. occulta in the Roscovita clade. Since M. bleizi lives attached to hard substrata in the tidal zone, whereas M. oculata and M. occulta live buried in subtidal sand flats, our results suggest that the anural larva evolved at least twice in the Roscovita clade of molgulid ascidians as an adaptation to different habitats.

A nod factor binding lectin with apyrase activity from legume roots.

A lectin isolated from the roots of the legume, Dolichos biflorus, binds to Nod factors produced by rhizobial strains that nodulate this plant and has a deduced amino acid sequence with no significant homology to any lectin reported to date. This lectin also is an enzyme that catalyzes the hydrolysis of phosphoanhydride bonds of nucleoside di- and triphosphates; the enzyme activity is increased in the presence of carbohydrate ligands. This lectin-nucleotide phosphohydrolase (LNP) has a substrate specificity characteristic of the apyrase category of phosphohydrolases, and its sequence contains four motifs characteristic of this category of enzymes. LNP is present on the surface of the root hairs, and treatment of roots with antiserum to LNP inhibits their ability to undergo root hair deformation and to form nodules on exposure to rhizobia. These properties suggest that this protein may play a role in the rhizobium-legume symbiosis and/or in a related carbohydrate recognition event endogenous to the plant.

Cerebral vasculopathy in sickle cell anemia: diagnostic contribution of positron emission tomography.

Children with sickle cell anemia (SS) have an increased risk for cerebral vasculopathy with stroke (CVA) and cognitive impairment. The present study examines the extent to which adding positron emission tomography (PET) to magnetic resonance imaging (MRI) can improve the detection of cerebral vasculopathy. Whereas MRI has been the prime modality for showing anatomical lesions, PET excels at assessing the functional metabolic state through glucose utilization 2-deoxy-2 [18F] fluoro-D-glucose (FDG) and microvascular blood flow ([15O]H2O). Forty-nine SS children were studied. Among them, 19 had clinically overt CVA, 20 had life-threatening hypoxic episodes or soft neurologic signs, and 10 were normal based on neurological history and examination. For the entire sample of 49 subjects, 30 (61%) had abnormal MRI findings, 36 (73%) had abnormal PET findings, and 44 (90%) showed abnormalities on either the MRI or the PET or both. Of the 19 subjects with overt CVA, 17 had abnormal MRI (89%), 17 had abnormal PET (89%), and 19 (100%) had either abnormal MRI or PET or both. Among the 20 subjects with soft neurologic signs, 10 (50%) had abnormal MRI, 13 (65%) had abnormal PET, and 17 (85%) had abnormal MRI and/or PET. Six (60%) of the 10 neurologically normal subjects had abnormal PET. Among the 30 subjects with no overt CVA, 25 (83%) demonstrated imaging abnormalities based on either MRI or PET or both, thus, silent ischemia. Lower than average full-scale intelligence quotient (FSIQ) was associated with either overt CVA or silent ischemic lesions. Four subjects who received chronic red blood cell transfusion showed improved metabolic and perfusion status on repeat PET scans. In conclusion, (1) the addition of PET to MRI identified a much greater proportion of SS children with neuroimaging abnormalities, particularly in those who had no history of overt neurologic events. (2) PET lesions are more extensive, often bihemispheric, as compared with MRI abnormalities. (3) PET may be useful in management as a tool to evaluate metabolic improvement after therapeutic interventions, and (4) the correlation of PET abnormalities to subsequent stroke or progressive neurologic dysfunction requires further study.

Cytoskeletal actin genes function downstream of HNF-3beta in ascidian notochord development.

We have examined the expression and regulation of cytoskeletal actin genes in ascidians with tailed (Molgula oculata) and tailless larvae (Molgula occulta). Four cDNA clones were isolated representing two pairs of orthologous cytoskeletal actin genes (CA1 and CA2), which encode proteins differing by five amino acids in the tailed and tailless species. The CA1 and CA2 genes are present in one or two copies, although several related genes may also be present in both species. Maternal CA1 and CA2 mRNA is present in small oocytes but transcript levels later decline, suggesting a role in early oogenesis. In the tailed species, embryonic CA1 and CA2 mRNAs first appear in the presumptive mesenchyme and muscle cells during gastrulation, subsequently accumulate in the presumptive notochord cells, and can be detected in these tissues through the tadpole stage. CA1 mRNAs accumulate initially in the same tissues in the tailless species but subsequently disappear, in concert with the arrest of notochord and tail development. In contrast, CA2 mRNAs were not detected in embryos of the tailless species. Fertilization of eggs of the tailless species with sperm of the tailed species, which restores the notochord and the tail, also results in the upregulation of CA1 and CA2 gene expression in hybrid embryos. Antisense oligodeoxynucleotide experiments suggest that CA1 and CA2 expression in the notochord, but not in the muscle cells, is dependent on prior expression of Mocc FHI, an ascidian HNF-3beta-like gene. The expression of the CA1 and CA2 genes in the notochord in the tailed species, downregulation in the tailless species, upregulation in interspecific hybrids, and dependence on HNF-3beta activity is consistent with a role of these genes in development of the ascidian notochord.

Determination of the gas-phase basicities of proline and its di- and tripeptides with glycine: the enhanced basicity of prolylproline.

The gas-phase basicity (GB) of proline, which is the only imino acid and is reported to play a significant role in protein folding, was determined by deprotonation reactions in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Protonated peptide ions were generated by fast atom bombardment in an external ion source. The GB of proline was found to be 213.3 kcal/mol. Among the dipeptides studied, the GB of glycylproline (GlyPro) was determined to be 214.8 kcal/mol, while prolyglycine (ProGly) was 4.2 kcal/mol more basic (GB = 219.0 kcal/mol). The basicity of the tripeptide prolylglycylglycine (ProGlyGly, GB = 219.0 kcal/mol) is 2 kcal/mol higher than the basicities of glycylglycylproline (GlyGlyPro) and glycylprolylglycine (GlyProGly), both of which have GB = 217.0 kcal/mol. The enhanced basicity of ProGlyGly is consistent with the protonation site being the terminal amino nitrogen with enhanced stabilization of the charge by the nearby bulkier residue. Interestingly, prolyproline (ProPro), which has a GB of 223.3 kcal/mol, is more basic than the other di- and tripeptides studied. Consequently, semi-empirical AM1 calculations were employed to probe the structural characteristics and intramolecular hydrogen bonding interactions for ProPro, GlyPro, ProGly and glycylglycine (GlyGly). ProPro was found to have a unique structure with two potential hydrogen bonds between amino hydrogens and both carbonyl oxygens.

Localization of the Darier disease gene to a 2-cM portion of 12q23-24.1.

Positional cloning with microsatellite markers allowed further localization of the Darier disease gene to a 2-cM interval of chromosome 12, 12q23-24.1, between the polymorphic loci D12S234 and D12S129. A region this size is suitable for construction of a contig to identify the Darier disease gene. Use of a polymorphic intronic marker for nitric oxide synthetase 1 gene, which maps to the same chromosomal area as the Darier gene, allowed exclusion of that gene as the Darier disease gene.

Induction of immune tolerance, the future of the Registry.

Factor VIII (FVIII) inhibitors are IgG antibodies that neutralize the procoagulant activity of FVIII, rendering hemorrhages difficult to manage. There may exist a genetic predisposition with consequent imbalance of T and B cell function. Efforts at inhibitor eradication in the last 20 years have produced a multitude of immune tolerance induction (IIT) protocols with variable outcome. Data derived from the International Registry indicate that inhibitor titer at outset of IIT and dose of FVIII concentrate used are important predictors of success. Future Registry activities should identify optimally standardized IIT regimens designed on the basis of patient likelihood to achieve tolerance and should provide further understanding of T and B cell interaction in the treatment process.

Assessment of the number and expression of P-type H(+)-ATPase genes in tomato.

Seven genomic fragments encoding isoforms of tomato (Lycopersicon esculentum) plasma membrane H(+)-ATPase were cloned and characterized. Genomic DNA gel-blot analysis indicated that probes corresponding to LHA1 through LHA7 hybridized to a common set of seven to nine restriction fragments at moderate stringency and to single, distinct fragments at high stringency. RNA gel-blot and polymerase chain reaction (PCR)-based RNA analyses indicated that LHA1, LHA2, and LHA4 transcripts were present in all organs examined (roots, hypocotyls, stems, immature leaves, mature leaves, green fruit, and red ripe fruit). LHA1 mRNA was present at similar abundance in all organs, LHA2 mRNA was most abundant in hypocotyls and leaves, and LHA4 mRNA was most abundant in roots and hypocotyls. RNA gel-blot and RNA-based PCR assays indicated that LHA3, LHA5, LHA6, and LHA7 mRNA was present at very low or nondetectable levels in all organs, suggesting that these genes are either expressed at very low levels or in organs not examined or that they are regulated by hormonal or environmental cues that were not tested. Indoleacetic acid (IAA) treatment of tomato hypocotyl segments resulted in modest changes in abundance of LHA1, LHA2, and LHA4 transcripts, but these changes were not correlated with the time course of IAA-induced growth. In addition, constitutively silent LHA genes were not activated by IAA. These results indicate that at least seven genomic sequences are present in tomato that may encode plasma membrane H(+)-ATPases, at least three of which are expressed relatively abundantly at the mRNA level.