Neuromuscular defects in a Drosophila survival motor neuron gene mutant

Autosomal recessive spinal muscular atrophy (SMA) is linked to mutations in the survival motor neuron (SMN) gene. The SMN protein has been implicated at several levels of mRNA biogenesis and is expressed ubiquitously. Studies in various model organisms have shown that the loss of function of the SMN gene leads to embryonic lethality. The human contains two genes encoding for SMN protein and in patients one of these is disrupted. It is thought the remaining low levels of protein produced by the second SMN gene do not suffice and result in the observed specific loss of lower motor neurons and muscle wasting. The early lethality in the animal mutants has made it difficult to understand why primarily these tissues are affected. We have isolated a Drosophila smn mutant. The fly alleles contain point mutations in smn similar to those found in SMA patients. We find that zygotic smn mutant animals show abnormal motor behavior and that smn gene activity is required in both neurons and muscle to alleviate this phenotype. Physiological experiments on the fly smn mutants show that excitatory post-synaptic currents are reduced while synaptic motor neuron boutons are disorganized, indicating defects at the neuromuscular junction. Clustering of a neurotransmitter receptor subunit in the muscle at the neuromuscular junction is severely reduced. This new Drosophila model for SMA thus proposes a functional role for SMN at the neuromuscular junction in the generation of neuromuscular defects.     

Sequence Analysis of the Washington/1964 Strain of Human Parainfluenza Virus Type 1 (HPIV1) and Recovery and Characterization of Wild-Type Recombinant HPIV1 Produced by Reverse Genetics

A complete consensus sequence was determined for the genomic RNA of human parainfluenza virus type 1 (HPIV1) strain Washington/20993/1964 (HPIV1 WASH/64), a clinical isolate that previously was shown to be virulent in adults. The sequence exhibited a high degree of relatedness to both Sendai virus, a PIV1 virus recovered from mice, and human PIV3 (HPIV3) with regard to cis-acting regulatory regions and protein-coding sequences. This consensus sequence was used to generate a full-length antigenomic cDNA and to recover a recombinant wild-type HPIV1 (rHPIV1). Interestingly, the rHPIV1 could be rescued from full-length antigenomic rHPIV1 cDNA using HPIV3 support plasmids, HPIV1 support plasmids, or a mixture thereof. The replication of rHPIV1 in vitro and in the respiratory tract of hamsters was similar to that of its biologically derived parent virus. The similar biological properties of rHPIV1 and HPIV1 WASH/64 in vitro and in vivo, together with the previous demonstration of the virulence of this specific isolate in humans, authenticates the rHPIV1 sequence as that of a wild-type virus. This rHPIV1 can now be used to study the biological properties of HPIV1 and as a substrate to introduce attenuating mutations for the generation of live-attenuated HPIV1 vaccine candidates.An erratum to this article can be found at     

An eighth locus for autosomal dominant retinitis pigmentosa is linked to chromosome 17q

Retinitis pigmentosa is one of the most common causes of severevisual handicap in middle to late life. Prior to this report,seven loci had previously been mapped for the autosomal dominantform of this disorder (adRP). We now report the identificationof a novel adRP locus on chromosome 17q. To map the new locus,we performed linkage analysis with microsatellite markers ina large South African kindred. After exclusion of 13 RP candidategene loci (including rhodopsin and peripherin-RDS), we obtainedsignificant positive lod scores at zero recombination fraction(     

Profiles of HIV voluntary counseling and testing of clients at a district hospital,Chiang Mai Province,northern Thailand,from 1995 to 1999

Voluntary HIV counseling and testing (VCT) is a central component of comprehensive HIV prevention strategies targeting individual risk reduction. VCT data are essential for planning and improving HIV/AIDS intervention strategies. The objective of this study is to describe demographic profiles, reasons for seeking HIV counseling and testing, rate of declining HIV testing after pretest counseling, rate of failure to return for HIV test results, and HIV prevalence and associations among 3570 clients who sought VCT at Sansai Hospital in northern Thailand from 1995 to 1999. Data were abstracted retrospectively from client-level data recorded by the hospital counselors on a standard form. HIV prevalence was 29% and remained high throughout the study period. Reasons for seeking VCT for men and women were markedly different and highly correlated with rates of declining the test, failure to return for test results, and HIV prevalence. Declining VCT and failing to return were high among uneducated clients (p <.001). Failure to return among men was associated with HIV prevalence (OR = 1.72, p =.003), particularly for those who had risk behaviors (OR = 5.92, p <.001) and those who wanted to know their HIV serostatus (OR = 4.44, p =.002). Overall, VCT acceptance and returning for test results were high. VCT services at the community level can reach high-risk individuals, especially male partners of women tested as part of routine prenatal care.     

Anti-high endothelial venule monoclonal antibody HECA-452 recognizes plasmacytoid T cells and delineates an ”extranodular“ compartment in the reactive lymph node

So-called plasmacytoid T cells represent a subset of monocyte related cells, which share with endothelium the CD36⁺CD11b⁻ (OKM5⁺OKM1⁻) phenotype. The reactivity of plasmacytoid T cells with rat monoclonal antibody HECA-452, highly specific for high endothelial venules, was analyzed in reactive lymph nodes. In all cases, HECA-452 not only labelled the endothelium of high endothelial venules, but also strongly reacted with singular and clustered plasmacytoid T cells. The HECA-452 positivity for high endothelial venules and plasmacytoid T cells visualized a lymph node compartment extending from the subcapsular sinus to the corticomedullary junction. This compartment surrounded the composite nodule and was designated the ”extranodular“ compartment. The cooccurrence of plasmacytoid T cells and high endothelial venules in this extranodular compartment, together with their immunophenotypical similarities, may be indicative of functional co-operations.     

Minimally immunogenic decellularized porcine valve provides in situ recellularization as a stentless bioprosthetic valve

Currently used bioprosthetic valves have several limitations such as calcification and functional deterioration, and revitalization through cellular ingrowth is impossible. To overcome these obstacles, we have developed a minimally immunogenic tissue-engineered valve that consists of an unfixed, decellularized porcine valve scaffold capable of being spontaneously revitalized in vivo after implantation. Porcine aortic root tissue was decellularized using detergents such as sodium lauryl sulfate and Triton X-100. The porcine valve was treated very gently and plenty of time was allowed for constituents to diffuse in and out of the matrix. In a preliminary study, a piece of decellularized porcine valve tissue was implanted into the rat subdermal space for 14 and 60 days and the structural integrity and calcification were evaluated. As an in vivo valve replacement model, the decellularized porcine valve was implanted in the pulmonary valve position in dogs and functional and histological evaluation was performed after 1, 2, and 6 months. Histological examination showed that the newly developed detergent treatment effectively removed cellular debris from the porcine aortic tissue. Decellularized porcine valve tissue implanted subdermally in rats showed minimal inflammatory cell infiltration and calcification. In the valve replacement model, spontaneous reendothelialization and repopulation of the medial cells were observed within 2 months, and good valve function without regurgitation was observed by echocardiography up to 6 months. The minimally immunogenic decellularized porcine valve proved effective in mitigating postimplant calcification and provided a suitable matrix for revitalizing prostheses through in situ recellularization, cellular ingrowth, and tissue remodeling.