Impacted gutkha presenting as an intrabronchial mass lesion leading to post-obstructive pneumonia.

A 66-year-old man presented with a chief complaint of difficulty breathing and productive cough. CT scan of the chest revealed an endobronchial mass with associated "tree-in-bud" opacities. A bronchoscopic biopsy of the mass was performed due to clinical suspicion of malignancy. Microscopic examination revealed inflamed endobronchial mucosa, granulation tissue and abundant fragments of uncharacterized organic material, compatible with aspiration. Detailed history revealed a history of chewing "gutkha", a form of smokeless tobacco comprising a mixture of betel nut and other condiments. Microscopic sections of a betel nut and the "gutkha mix" processed subsequently in the histology laboratory were found to be similar to the organic material found in the mass. Thus, a diagnosis of impacted betel nut mixture leading to post-obstructive pneumonia was rendered.

Low vitamin D levels are associated with increased rejection and infections after lung transplantation.

BACKGROUND: The prevalence of vitamin D deficiency in lung disease is greater than in the general population. Vitamin D deficiency may negatively affect immune and lung function. Accordingly, we hypothesized that lung transplant recipients with vitamin D deficiency are more susceptible to rejection and infections after transplantation. METHODS: Transplant outcomes were reviewed in a retrospective cohort of 102 lung transplant recipients who had 25-hydroxyvitamin D [25(OH)D] levels drawn during the near-transplant period (100 days pre- or post-transplant). RESULTS: In the near-transplant period, 80% of recipients were 25(OH)D-deficient and 20% were not 25(OH)D-deficient. Episodes of acute cellular rejection in the deficient group were more frequent than in the non-deficient group [mean 1.27 (0.99 to 1.55) vs 0.52 (0.12 to 0.93), p = 0.006]. The rejection rate in the deficient group was more than double that of the the non-deficient group [IRR 2.43 (1.30 to 4.52), p = 0.005]. Infectious episodes were also more frequent in the deficient group than in the non-deficient group [mean 4.01 (3.24 to 4.79) vs 2.71 (1.47 to 3.96), p = 0.04]. The mortality rate of recipients who remained 25(OH)D-deficient 1 year after transplant was almost 5-fold higher than in recipients who were not 25(OH)D-deficient [IRR 4.79 (1.06 to 21.63), p = 0.04]. CONCLUSIONS: Low serum 25(OH)D levels in lung transplant recipients were associated with increased incidence of acute rejection and infection. The mortality of recipients who remained deficient 1 year post-transplant was higher than that of recipients who maintained normal vitamin D levels at 1 year post-transplant.

Phophatidylinositol-3 kinase/mammalian target of rapamycin/p70S6K regulates contractile protein accumulation in airway myocyte differentiation.

Increased airway smooth muscle in airway remodeling results from myocyte proliferation and hypertrophy. Skeletal and vascular smooth muscle hypertrophy is induced by phosphatidylinositide-3 kinase (PI(3) kinase) via mammalian target of rapamycin (mTOR) and p70S6 kinase (p70S6K). We tested the hypothesis that this pathway regulates contractile protein accumulation in cultured canine airway myocytes acquiring an elongated contractile phenotype in serum-free culture. In vitro assays revealed a sustained activation of PI(3) kinase and p70S6K during serum deprivation up to 12 d, with concomitant accumulation of SM22 and smooth muscle myosin heavy chain (smMHC) proteins. Immunocytochemistry revealed that activation of PI3K/mTOR/p70S6K occurred almost exclusively in myocytes that acquire the contractile phenotype. Inhibition of PI(3) kinase or mTOR with LY294002 or rapamycin blocked p70S6K activation, prevented formation of large elongated contractile phenotype myocytes, and blocked accumulation of SM22 and smMHC. Inhibition of MEK had no effect. Steady-state mRNA abundance for SM22 and smMHC was unaffected by blocking p70S6K activation. These studies provide primary evidence that PI(3) kinase and mTOR activate p70S6K in airway myocytes leading to the accumulation of contractile apparatus proteins, differentiation, and growth of large, elongated contractile phenotype airway smooth muscle cells.

The RhoA/Rho kinase pathway regulates nuclear localization of serum response factor.

RhoA and its downstream target Rho kinase regulate serum response factor (SRF)-dependent skeletal and smooth muscle gene expression. We previously reported that long-term serum deprivation reduces transcription of smooth muscle contractile apparatus encoding genes, by redistributing SRF out of the nucleus. Because serum components stimulate RhoA activity, these observations suggest the hypothesis that the RhoA/Rho kinase pathway regulates SRF-dependent smooth muscle gene transcription in part by controlling SRF subcellular localization. Our present results support this hypothesis: cotransfection of cultured airway myocytes with a plasmid expressing constitutively active RhoAV14 selectively enhanced transcription from the SM22 and smooth muscle myosin heavy chain promoters and from a purely SRF-dependent promoter, but had no effect on transcription from the MSV-LTR promoter or from an AP2-dependent promoter. Conversely, inhibition of the RhoA/Rho kinase pathway by cotransfection with a plasmid expressing dominant negative RhoAN19, by cotransfection with a plasmid expressing Clostridial C3 toxin, or by incubation with the Rho kinase inhibitor, Y-27632, all selectively reduced SRF-dependent smooth muscle promoter activity. Furthermore, treatment with Y-27632 selectively reduced binding of SRF from nuclear extracts to its consensus DNA target, selectively reduced nuclear SRF protein content, and partially redistributed SRF from nucleus to cytoplasm, as revealed by quantitative immunocytochemistry. Treatment of cultured airway myocytes with latrunculin B, which reduces actin polymerization, also caused partial redistribution of SRF into the cytoplasm. Together, these results demonstrate for the first time that the RhoA/Rho kinase pathway controls smooth muscle gene transcription in differentiated smooth muscle cells, in part by regulating the subcellular localization of SRF. It is conceivable that the RhoA/Rho kinase pathway influences SRF localization through its effect on actin polymerization dynamics.

Structure and transcription of the human m3 muscarinic receptor gene.

We have isolated and characterized the human m3 muscarinic receptor gene and its promoter. Using 5' rapid amplification of cDNA ends (RACE), internal polymerase chain reaction (PCR), and homology searching to identify EST clones, we determined that the cDNA encoding the m3 receptor comprises 4,559 bp in 8 exons, which are alternatively spliced to exclude exons 2, 4, 6, and/or 7; the receptor coding sequence occurs within exon 8. Analysis of P1 artificial chromosome (PAC) and bacterial artificial chromosome (BAC) clones and of PCR- amplified genomic DNA, and homology searching of human chromosome 1 sequence provided from the Sanger Centre (Hinxton, Cambridge, UK) revealed that the m3 muscarinic receptor gene spans at least 285 kb. A promoter fragment containing bp -1240 to +101 (relative to the most 5' transcription start site) exhibited considerable transcriptional activity during transient transfection in cultured subconfluent, serum-fed canine tracheal myocytes, and 5' deletion analysis of promoter function revealed the presence of positive transcriptional regulatory elements between bp -526 and -269. Sequence analysis disclosed three potential AP-2 binding sites in this region; five more AP-2 consensus binding motifs occur between bp -269 and +101. Cotransfection with a plasmid expressing human AP-2alpha substantially increased transcription from m3 receptor promoter constructs containing 526 or 269 bp of 5' flanking DNA. Furthermore, m3 receptor promoter activity was enhanced by long-term serum deprivation of canine tracheal myocytes, a treatment that is known to increase AP-2 transcription-promoting activity in these cells. Together, these data suggest that expression of the human m3 muscarinic receptor gene is regulated in part by AP-2 in airway smooth muscle.