Clinical evidence of the nonpathogenic nature of the M34T variant in the connexin 26 gene

Mutations in GJB2 are the most common cause of congenital nonsyndromic hearing loss. The controversial allele variant M34T has been hypothesized to cause autosomal dominant or recessive nonsyndromic hearing impairment and some in vitro data has been consistent with this hypothesis. In this report, we present the clinical and genotypic study of 11 families (seven familial forms of nonsyndromic sensorineural hearing loss (NSSNHL) and four sporadic cases) in which the M34T GJB2 variant has been identified. The M34T mutation did not segregate with the deafness in six of the seven familial forms of NSSNH. Eight persons with normal audiogram presented a heterozygous M34T variation and five normal hearing individuals were composite heterozygous for M34T and another GJB2 mutation. Four normal hearing individuals with a documented audiogram were M34T/35delG and one was M34T/(GJB6-D13S1830)del. Screening a French control population of 116 subjects we have found an M34T allele frequency of 1.72%. This percentage was not significatively different from the prevalence of the M34T allele in the deaf population, which was 2.12%. All these data suggest that the M34T variant is not clinically significant in human and is a frequent polymorphism in France.     

The relative contribution of direct and indirect antigen recognition pathways to the alloresponse and graft rejection depends upon the nature of the transplant

In this study, we measured direct and indirect T-cell alloresponses mediated by CD4(+) and CD8(+) T cells in three mouse transplantation models: skin, cornea, and retina. We show that the contribution of direct and indirect antigen recognition pathways to the alloresponse to fully allogeneic grafts varies depending upon the nature of the tissue/organ transplanted. The implications of this finding for understanding the cellular mechanisms by which rejection is mediated in different transplant models are discussed.     

Growth hormone deficiency,aortic dilation,and neurocognitive issues in Feingold syndrome 2

We report three patients with Feingold 2 syndrome with the novel features of growth hormone deficiency associated with adenohypophyseal compression, aortic dilation, phalangeal joint contractures, memory, and sleep problems in addition to the typical features of microcephaly, brachymesophalangy, toe syndactyly, short stature, and cardiac anomalies. Microdeletions of chromosome 13q that include the MIR17HG gene were found in all three. One of the patients was treated successfully with growth hormone. In addition to expanding the phenotype of Feingold 2 syndrome, we suggest management of patients with Feingold 2 syndrome include echocardiography at the time of diagnosis in all patients and consideration of evaluation for growth hormone deficiency in patients with short stature.     

Type 2 nitric oxide synthase and protein nitration in chronic lung infection

Inflammation in the lung can lead to increased expression of inducible nitric oxide synthase (iNOS) and enhanced NO production. It has been postulated that the resultant highly reactive NO metabolites may have an important role in host defence, although they might also contribute to tissue damage. However, in a number of inflammatory lung diseases, including bronchiectasis, iNOS expression is increased but no elevation of airway NO can be detected. A potential explanation for this finding is that NO is rapidly scavenged by reaction with superoxide radicals, forming peroxynitrite, which is preferentially metabolized via nitration and nitrosation reactions. To test this hypothesis, anaesthetized, specific pathogen-free rats were inoculated with Pseudomonas aeruginosa incorporated into agar beads (chronically infected group) or sterile agar beads (control group). Ten to 15 days later, the lungs were isolated and fixed. Pseudomonas organisms were isolated from the lungs of the chronically infected group. These lungs showed extensive inflammatory cell infiltration and tissue damage, which were not observed in control lungs. Expression of iNOS was increased in the chronically infected group when compared with the control group. However, the mean number of cells staining for nitrotyrosine in the chronically infected group was not significantly different from that in the controls, nor was there an excess of nitrotyrosine, nitrate, nitrite or nitrosothiol concentrations in the infected lungs. Thus, no evidence was found of increased NO metabolites in chronically infected lungs, including products of the peroxynitrite pathway. These findings suggest that chronic infection does not cause increased iNOS activity in the lung, despite increased expression of iNOS.     

Animal danders

Animals release proteins into their surroundings through secretions, as excretions, or as dander. The quantity of dander that is dispersed by cats, dogs, or humans is sufficient to supply food for dust mites and to supply easily measurable quantities of proteins in dust. Fel d 1, Can f 1, and human IgA or IgG can be found in microgram quantities in dust samples. Allergens also can accumulate from the urine of wild or pet rodents. For cats and dogs, the accumulation of dander particles is not related to the cleanliness of the animals. All animals, including humans, provide a fully adequate supply of organic material for bacterial growth in a carpet, provided conditions are sufficiently humid. The authors' preliminary results in Virginia do not find a significant difference in endotoxin between homes with or without animals. The likely explanation for the nonallergic IgG and IgG4 response to cat, dog, or rat allergens is high exposure to proteins from these animals. If the highest levels of cat allergen in a home can result in immunologic tolerance, it is unlikely that primary avoidance would be successful at reducing exposure. The data showing that 80% of Swedish children with cat allergies never had lived with a cat imply that the concentrations of cat allergen in schools or in houses without a cat are sufficient to cause sensitization. Primary prevention would be possible only on a community basis, which is unlikely to occur. Sensitization to cat, rat, dog, or mouse allergens consistently is associated with asthma. In symptomatic children with positive skin test results, there is a strong case for allergen avoidance and a clear need for controlled trials. Controlled trials of avoidance should include houses without cats and schools. Controlling exposure to cat allergens with the cat in situ requires aggressive measures, such as removing reservoirs, washing the cat, and air cleaning. Many allergic or symptomatic children who live with a cat do not have positive skin test results or positive IgE antibodies to cats. Avoidance measures related to animals should be recommended only for individuals with positive skin test results. Increasing evidence shows that exposure to cats, dogs, rats, and other animals can induce a form of immunologic tolerance without causing allergic disease, and it is important to understand why this change occurs with dander allergens rather than with all allergens. The most probable explanations are related to the form and quantity of airborne allergens.     

ALG11‐CDG syndrome: Expanding the phenotype

ALG11‐Congenital Disorder of Glycosylation (ALG11‐CDG, also known as congenital disorder of glycosylation type Ip) is an inherited inborn error of metabolism due to abnormal protein and lipid glycosylation. We describe two unrelated patients with ALG11‐CDG due to novel mutations, review the literature of previously described affected individuals, and further expand the clinical phenotype. Both affected individuals reported here had severe psychomotor disabilities and epilepsy. Their fibroblasts synthesized truncated precursor glycan structures, consistent with ALG11‐CDG, while also showing hypoglycosylation of a novel biomarker, GP130. Surprisingly, one patient presented with normal transferrin glycosylation profile, a feature that has not been reported previously in patients with ALG11‐CDG. Together, our data expand the clinical and mutational spectrum of ALG11‐CDG.     

Molecular characterization of Kaposi's sarcoma associated herpesvirus (KSHV) from patients with AIDS-associated Kaposi's sarcoma in Sao Paulo, Brazil.

BACKGROUND: Kaposi's sarcoma (KS) is caused by Kaposi's sarcoma associated herpesvirus (KSHV/HHV-8), the eighth Herpesvirus found to infect humans. The molecular epidemiology of KSHV is related closely to ethnicity and geographical location of studied populations. There is little epidemiological and molecular information about KSHV strains circulating in Brazil. OBJECTIVES: To characterize KSHV strains isolated from AIDS patients with Kaposi's sarcoma (AIDS-KS) in Sao Paulo, Brazil, and to examine associations between KSHV subtypes, ethnicity and HIV risk categories. METHODS: AIDS-KS patients were recruited consecutively at the largest AIDS reference hospital in Sao Paulo. Fragments (420 bp) of the VR1 and VR2 regions of KSHV open reading frame (ORF) K1 were amplified by nested PCR and sequenced directly. RESULTS: We analysed 37 samples from 33 patients, and found subtypes A-C in 48%, 21% and 30% of patients respectively, including two patients infected with subtype A5, a first report from Brazil. Sexual orientation was associated with subtype: 12/14 (86%) patients with subtype A were male homo/bisexual, compared with 3/8 (38%) among patients infected with subtype C (P = 0.05). A higher proportion of male patients with subtype C were of Caucasian origin (7/8 (87%)), compared with 7/16 (44%) among male patients with subtype A (P = 0.08). CONCLUSIONS: This first detailed report of KSHV subtypes among AIDS-KS patients in Brazil reports the first isolation of KSHV subtype A5 in this country, and suggests KSHV strain transmission between different ethnic groups, and association of specific strains with sexual orientation.