Elicitation of allergic asthma by immunoglobulin free light chains

The observation that only 50% of patients with adult asthma manifest atopy indicates that other inflammatory mechanisms are likely involved in producing the characteristic features of this disorder; namely reversible airway obstruction, hyperresponsiveness, and pulmonary inflammation. Our recent discovery that antigen-specific Ig free light chains (LCs) mediate hypersensitivity-like responses suggests that these molecules may be of import in the pathophysiology of asthma. Using a murine experimental model of nonatopic asthma, we now have shown that an LC antagonist, the 9-mer peptide F991, can abrogate the development of airway obstruction, hyperresponsiveness, and pulmonary inflammation. Further, passive immunization with antigen-specific LCs and subsequent airway challenge can elicit a mast cell-dependent reaction leading to acute bronchoconstriction. These findings, and the demonstration that the concentration of free kappa LCs in the sera of patients with adult asthma were significantly increased (as compared with age-matched nonasthmatic individuals), provide previously undescribed insight into the pathogenesis of asthma. In addition, the ability to inhibit pharmacologically LC-induced mast cell activation provides a therapeutic means to prevent or ameliorate the adverse bronchopulmonary manifestations of this incapacitating disorder.     

Mice deficient in glutathione transferase zeta/maleylacetoacetate isomerase exhibit a range of pathological changes and elevated expression of alpha, mu, and pi class glutathione transferases

Glutathione transferase zeta (GSTZ1-1) is the major enzyme that catalyzes the metabolism of alpha-halo acids such as dichloroacetic acid, a carcinogenic contaminant of chlorinated water. GSTZ1-1 is identical with maleylacetoacetate isomerase, which catalyzes the penultimate step in the catabolic pathways for phenylalanine and tyrosine. In this study we have deleted the Gstz1 gene in BALB/c mice and characterized their phenotype. Gstz1(-/-) mice do not have demonstrable activity with maleylacetone and alpha-halo acid substrates, and other GSTs do not compensate for the loss of this enzyme. When fed a standard diet, the GSTZ1-1-deficient mice showed enlarged liver and kidneys as well as splenic atrophy. Light and electron microscopic examination revealed multifocal hepatitis and ultrastructural changes in the kidney. The addition of 3% (w/v) phenylalanine to the drinking water was lethal for young mice (<28 days old) and caused liver necrosis, macrovesicular steatosis, splenic atrophy, and a significant loss of circulating leukocytes in older surviving mice. GSTZ1-1-deficient mice showed constitutive induction of alpha, mu, and pi class GSTs as well as NAD(P)H:quinone oxidoreductase 1. The overall response is consistent with the chronic accumulation of a toxic metabolite(s). We detected the accumulation of succinylacetone in the serum of deficient mice but cannot exclude the possibility that maleylacetoacetate and maleylacetone may also accumulate.     

RNA analysis reveals splicing mutations and loss of expression defects in MLH1 and BRCA1

The classical paradigm of mutation screening seeks to relate alterations in DNA sequence to their effect at the protein level. However, the majority of missense mutations are problematic as their pathological significance is often unclear. In order to test the hypothesis that many missense mutations primarily cause defects at the RNA rather than the protein level, we have performed retrospective RNA analysis of 12 individuals carrying missense mutations in the cancer predisposition genes APC, BRCA1, BRCA2, MLH1, and MSH2. RNA was extracted from peripheral blood samples and RT-PCR performed in order to assess the splicing and expression of the mutant allele in each case. Four of the 12 missense mutations analysed were associated with RNA defects. We detected two cases of exon skipping and one case of partial intron inclusion with activation of a cryptic intronic splice site in MLH1. A fourth case was associated with monoallelic expression of BRCA1. In addition, allele-specific analysis of common coding polymorphisms identified a further case of monoallelic BRCA1 expression in one of two individuals who had previously screened as mutation-negative. Although we were unable to identify the underlying cause of this loss of expression, it strongly suggests the presence of a pathogenic defect in BRCA1 in this case, highlighting the use of allelic expression studies as a method of mutation scanning. Finally, we used our dataset to test the ability of several in silico sequence analysis tools to identify splicing defects. Our results suggest that a significant number of missense mutations in cancer predisposition genes are associated with defects of RNA splicing, and that the use of gene- and splice site prediction software can aid in identifying such mutations.     

Lipid effects on neutrophil calcium signaling induced by opsonized particles: platelet activating factor is only part of the story

BACKGROUND & METHODS: Total parenteral nutrition is frequently used in clinical practice to improve the nutritional status of patients. However, the risk for infectious complications remains a drawback in which immune-modulating effects of the lipid component may play a role. To characterize these lipid effects we investigated neutrophil activation by opsonized yeast particles under influence of lipid emulsions derived from fish oil (VLCT), olive oil (LCT-MUFA), soybean oil (LCT), and a physical mixture of coconut and soybean oil (LCT-MCT). RESULTS: Serum-treated zymosan (STZ) evoked a biphasic increase in cytosolic Ca2+ concentration ([Ca2+]c) with an initial slow rise that turned into a second fast rise until a plateau was reached. LCT-MCT (5 mM) pretreatment markedly increased the rate of [Ca2+]c rise during the initial phase, abolished the second phase and lowered the plateau. These effects of LCT-MCT were mimicked by the protein kinase C (PKC) activating phorbol ester PMA. LCT, LCT-MUFA and VLCT, on the other hand, decreased the rate of [Ca2+]c rise during both phases and lowered the plateau. The platelet-activating factor (PAF) receptor antagonist WEB 2086 inhibited the second phase, demonstrating that PAF acts as an intercellular messenger in STZ-induced Ca2+ mobilization, but did not interfere with the stimulatory effect of LCT-MCT or PMA on the initial rate of [Ca2+]c rise. CONCLUSIONS: Structurally different lipids act only in part through PAF to distinctively modulate neutrophil calcium signaling in response to activation by opsonized particles.     

Use of insulin like growth factor binding protein-1 in the diagnosis of ruptured fetal membranes

OBJECTIVE: The benefit of insulin like growth factor binding protein-1 (IGFBP-1) in diagnosing ruptured fetal membranes in cases in which the diagnosis is clinically doubtful, is investigated. DESIGN: A total of 83 patients with clinically doubtful rupture of fetal membranes were included, and treated as usual. The clinical diagnosis, the amniotic fluid crystallization test, and IGFBP-1 detection were performed on all patients and compared with the defined gold standard. The sensitivity, specificity, positive predictive value, and negative predictive value of each test were calculated. RESULTS: In all, 27 patients (33%) had ruptured fetal membranes at the time of inclusion. The clinical diagnosis of the attending obstetrician showed a higher predictive value of both a positive and negative test result than both IGFBP-1 detection, and the amniotic fluid crystallization test. CONCLUSIONS: As the clinical diagnosis showed the highest sensitivity and specificity, IGFBP-1 detection has no additional benefit to ascertain the diagnosis of ruptured fetal membranes in cases in which the diagnosis was clinically doubtful.     

Allogeneic hematopoietic stem cell transplantation in the active duty military population: 1987-2001

Wilford Hall Medical Center at Lackland Air Force Base is the only military medical center in the United States at which allogeneic hematopoietic stem cell transplants (HSCT) are performed. Through May 2001, 367 patients, including 163 active duty service members, have received allogeneic HSCT from related donors. We performed a retrospective review of the outcomes of allogeneic HSCT in active duty members to determine what proportion was returned to full-time military service after HSCT and to delineate the factors associated with successful return to military service. Twenty-one percent of service members who received allogeneic HSCT were returned to active duty at some point after treatment. Age, sex, branch of service, and rank had no significant influence on return to duty status. When adjusted for age and rank, the only significant predictor of successful return to active duty was a diagnosis of chronic myelogenous leukemia. Although individuals with good risk diseases such as aplastic anemia, myelodysplastic syndrome, paroxymal nocturnal hemoglobinuria, and acute myelogenous leukemia in first complete remission have also been returned active duty after HSCT, these diagnoses were not statistically predictive of a return to active duty. We conclude that it may be possible to predict which service members will return to active duty after allogeneic HSCT based on the disease for which HSCT is being performed. Most importantly, active duty service members need not be a priori medically retired after HSCT, and each return to duty decision must be individualized.     

Neonatal intraventricular haemorrhage associated with maternal use of paroxetine

Selective serotonin reuptake inhibitors (SSRIs) have been reported to inhibit serotonin uptake into platelets, resulting in decreased platelet function. We report a case of a large intraventricular haemorrhage in a 6-h-old boy, whose mother used paroxetine during pregnancy.