In contrast to HIV, KIR3DS1 does not influence outcome in HTLV-1 retroviral infection

While most carriers of human T-cell leukemia virus type 1 (HTLV-1) remain asymptomatic throughout their lifetime, infection is associated with the development of adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The exact parameters that determine these outcomes are unknown but are believed to include host genetic factors that control the immune response to infection. Host response to fellow retroviridae member HIV is influenced by the expression of members of the Killer Immunoglobulin Receptor (KIR) family including KIR3DS1. In this study we examined the association of KIR3DS1 with the outcome of HTLV-1 infection in three geographically distinct cohorts (Jamaican, Japanese and Brazilian). Despite increased prevalence of KIR3DS1 in the HAM/TSP patients of the Jamaican cohort, we found no evidence for a role of KIR3DS1 in influencing control of proviral load or disease outcome. This suggests that unlike HIV, KIR3DS1-mediated regulation of HTLV-1 infection does not occur, or is ineffective.

Defining the transcriptional signature of skeletal muscle stem cells

Satellite cells, the main source of myoblasts in postnatal muscle, are located beneath the myofiber basal lamina. The myogenic potential of satellite cells was initially documented based on their capacity to produce progeny that fused into myotubes. More recently, molecular markers of resident satellite cells were identified, further contributing to defining these cells as myogenic stem cells that produce differentiating progeny and self-renew. Herein, we discuss aspects of the satellite cell transcriptional milieu that have been intensively investigated in our research. We elaborate on the expression patterns of the paired box (Pax) transcription factors Pax3 and Pax7, and on the myogenic regulatory factors myogenic factor 5 (Myf5), myogenic determination factor 1 (MyoD), and myogenin. We also introduce original data on MyoD upregulation in newly activated satellite cells, which precedes the first round of cell proliferation. Such MyoD upregulation occurred even when parent myofibers with their associated satellite cells were exposed to pharmacological inhibitors of hepatocyte growth factor and fibroblast growth factor receptors, which are typically involved in promoting satellite cell proliferation. These observations support the hypothesis that most satellite cells in adult muscle are committed to rapidly entering myogenesis. We also detected expression of serum response factor in resident satellite cells prior to MyoD expression, which may facilitate the rapid upregulation of MyoD. Aspects of satellite cell self-renewal based on the reemergence of cells expressing Pax7, but not MyoD, in myogenic cultures are discussed further herein. We conclude by describing our recent studies using transgenic mice in which satellite cells are traced and isolated based on their expression of green fluorescence protein driven by regulatory elements of the nestin promoter (nestin-green fluorescence protein). This feature provides us with a novel means of studying satellite cell transcriptional signatures, heterogeneity among muscle groups, and the role of the myogenic niche in directing satellite cell self-renewal.

Cloning and functional expression of a novel human connexin-25 gene

Gap junctions are intercellular, water-filled channels composed of transmembrane proteins called connexins, six of which are arranged radially and dock with six homologous proteins in an adjacent cell to form an approximate 16 A pore. Through this pore cell-to-cell transfer of small water-soluble molecules up to about 1000 daltons occurs along concentration gradients. Connexins comprise a multigene family that share consensus sequences in the trans-membrane domains and the first and second extracellular loops. Comparison of the protein sequences of known human connexins with the draft nucleotide sequence of the human genome revealed two clones from chromosome 6 which showed strong similarity to highly conserved connexin sequences. Detailed analysis revealed the presence of a 672 nt open reading frame in these clones, encoding a 223 amino acid polypeptide with a predicted molecular weight of about 25 kD. This is smaller than other known human connexins. The ORF of the potential connexin25 was amplified by semi-nested PCR using human genomic DNA as a template. To confirm that this new gene encodes a connexin, Cx25 was transfected into a gap junction deficient subclone of the human HeLa cell line. After selection of transformants, cells were microinjected with the fluorescent dye Lucifer yellow. Transfectants but not controls successfully transferred dye, demonstrating that this new gene encodes a functional connexin.

Tubed gastro-omental free flap for pharyngoesophageal reconstruction

BACKGROUND

Malignant lesions of the pharyngoesophagus often require total laryngopharyngectomy and mediastinal dissection. As a result of the current treatment paradigms for advanced laryngopharyngeal cancers, it is common that the surgical field has been previously irradiated or exposed to systemic chemotherapy, resulting in fistula rates as high as 78% and mortality as high as 8%. The free vascularized tubed gastric antrum and the accompanying greater omentum offer a single-staged method of pharyngoesophageal reconstruction, with the added benefit of protection of the great vessels, the tracheal stump, and the mediastinal contents in a high-risk surgical field.

OBJECTIVE

To assess the gastro-omental free flap as a method of pharyngoesophageal reconstruction in patients who have been previously treated with multimodality therapy.

METHODS

Five consecutive cases of gastro-omental free flap reconstruction after total laryngopharyngectomy were retrospectively reviewed. Each case was assessed for intraoperative, perioperative, and postoperative complications at the primary site of reconstruction and the donor site. Patients were also evaluated for their ability to maintain an oral diet. Patients were followed up for a minimum of 6 months after surgery.

RESULTS

Five patients aged 44 to 70 years (mean, 59 years) underwent gastro-omental free flap reconstruction after total laryngopharyngectomy. Five patients had received previous external beam irradiation, 2 had received systemic chemotherapy, and 4 had undergone previous surgery. There were no fistulae or flap complications. Three patients were successfully treated with esophageal dilation for strictures sustained 2 to 5 months after surgery, and a third patient was successfully treated with conservative management for a partial gastric outlet obstruction sustained 2 months after surgery. One patient died 3 months after surgery of distant metastatic disease. The remaining 4 patients currently tolerate an oral diet.

CONCLUSION

The tubed gastro-omental free flap offers a safe method of reconstructing the pharyngoesophageal segment in a surgical field compromised by previous multimodality therapy.