A confocal microscopic study of solitary pulmonary neuroendocrine cells in human airway epithelium

Background

Pulmonary neuroendocrine cells (PNEC) are specialized epithelial cells that are thought to play important roles in lung development and airway function. PNEC occur either singly or in clusters called neuroepithelial bodies. Our aim was to characterize the three dimensional morphology of PNEC, their distribution, and their relationship to the epithelial nerves in whole mounts of adult human bronchi using confocal microscopy.

Methods

Bronchi were resected from non-diseased portions of a lobe of human lung obtained from 8 thoracotomy patients (Table ​(Table1)1) undergoing surgery for the removal of lung tumors. Whole mounts were stained with antibodies to reveal all nerves (PGP 9.5), sensory nerves (calcitonin gene related peptide, CGRP), and PNEC (PGP 9.5, CGRP and gastrin releasing peptide, GRP). The analysis and rendition of the resulting three-dimensional data sets, including side-projections, was performed using NIH-Image software. Images were colorized and super-imposed using Adobe Photoshop.

Table 1

Patient Demographic Data

Canine gastrointestinal parasitic zoonoses in India

Although well recognized and studied in developed countries, canine parasitic zoonoses pose a lowly prioritized public health problem in developing countries such as India, where conditions are conducive for transmission. A study of the most recent parasite survey determining prevalence and epidemiology of canine parasitic zoonoses among tea-growing communities of northeast India demonstrated the endemicity of the problem. This particular study serves as a model using conventional, as well as molecular parasitological, tools to provide novel insights into the role of dogs as mechanical transmitters of human parasites such as Ascaris and Trichuris, and discusses the risks dogs pose with regards to zoonotic transmission of hookworms and Giardia.     

Effects of cytoplasmic polyhedrosis virus on diapausing Heliothis virescens

Laboratory studies were conducted to determine effects of cytoplasmic polyhedrosis virus on diapausing Heliothis virescens. Most virus-infected individuals died in the larval stage. Infected pupae yielded as many moths as healthy. Females from surviving virus-infected larvae produced fewer eggs than those from healthy larvae, but there was no statistical difference in longevity of adults between healthy and infected groups. Infected moths yielded lower than normal quantities of extracted fatty acids.     

Adult-derived stem cells and their potential for use in tissue repair and molecular medicine

This report reviews three categories of precursor cells present within adults. The first category of precursor cell, the epiblast-like stem cell, has the potential of forming cells from all three embryonic germ layer lineages, e.g., ectoderm, mesoderm, and endoderm. The second category of precursor cell, the germ layer lineage stem cell, consists of three separate cells. Each of the three cells is committed to form cells limited to a specific embryonic germ layer lineage. Thus the second category consists of germ layer lineage ectodermal stem cells, germ layer lineage mesodermal stem cells, and germ layer lineage endodermal stem cells. The third category of precursor cells, progenitor cells, contains a multitude of cells. These cells are committed to form specific cell and tissue types and are the immediate precursors to the differentiated cells and tissues of the adult. The three categories of precursor cells can be readily isolated from adult tissues. They can be distinguished from each other based on their size, growth in cell culture, expressed genes, cell surface markers, and potential for differentiation. This report also discusses new findings. These findings include the karyotypic analysis of germ layer lineage stem cells; the appearance of dopaminergic neurons after implantation of naive adult pluripotent stem cells into a 6-hydroxydopamine-lesioned Parkinson's model; and the use of adult stem cells as transport mechanisms for exogenous genetic material. We conclude by discussing the potential roles of adult-derived precursor cells as building blocks for tissue repair and as delivery vehicles for molecular medicine.     

Deleterious genomic mutation rate for viability in Drosophila melanogaster using concomitant sibling controls

New deleterious mutations may reduce health and fitness and are involved in the evolution and maintenance of numerous biological processes. Hence, it is important to estimate the deleterious genomic mutation rate (U) in representative higher organisms. However, these estimated rates vary widely, mainly because of inadequate experimental controls. Here we describe an experimental design (the Binscy assay) with concomitant sibling controls and estimate U for viability in Drosophila melanogaster to be 0.31. This estimate, like most published studies, focuses on viability mutations and the overall deleterious genomic mutation rate would therefore be higher.     

The zoonotic transmission of Giardia and Cryptosporidium

The molecular characterisation of Giardia and Cryptosporidium has given rise to a more epidemiological meaningful and robust taxonomy. Importantly, molecular tools are now available for 'typing' isolates of the parasites directly from clinical and environmental samples. As a consequence, information on zoonotic potential has been obtained although the frequency of zoonotic transmission is still poorly understood. Analysis of outbreaks and case-control studies, especially when coupled with genotyping data, is slowly providing information on the public health significance of zoonotic transmission. Such studies support the hypothesis that Cryptosporidium hominis is spread only between humans but that the major reservoir for Cryptosporidium parvum is domestic livestock, predominantly cattle, and that direct contact with infected cattle is a major transmission pathway along with indirect transmission through drinking water. The situation is less clearcut for Giardia duodenalis but the evidence does not, in general, support zoonotic transmission as a major risk for human infections. However, for both parasites there is a need for molecular epidemiological studies to be undertaken in well-defined foci of transmission in order to fully determine the frequency and importance of zoonotic transmission.     

FbpA-Dependent biosynthesis of trehalose dimycolate is required for the intrinsic multidrug resistance, cell wall structure, and colonial morphology of Mycobacterium smegmatis

Ligation of mycolic acids to structural components of the mycobacterial cell wall generates a hydrophobic, impermeable barrier that provides resistance to toxic compounds such as antibiotics. Secreted proteins FbpA, FbpB, and FbpC attach mycolic acids to arabinogalactan, generating mycolic acid methyl esters (MAME) or trehalose, generating alpha,alpha'-trehalose dimycolate (TDM; also called cord factor). Our studies of Mycobacterium smegmatis showed that disruption of fbpA did not affect MAME levels but resulted in a 45% reduction of TDM. The fbpA mutant displayed increased sensitivity to both front-line tuberculosis-targeted drugs as well as other broad-spectrum antibiotics widely used for antibacterial chemotherapy. The irregular, hydrophobic surface of wild-type M. smegmatis colonies became hydrophilic and smooth in the mutant. While expression of M. smegmatis fbpA restored defects of the mutant, heterologous expression of the Mycobacterium tuberculosis fbpA gene was less effective. A single mutation in the M. smegmatis FbpA esterase domain inactivated its ability to provide antibiotic resistance. These data show that production of TDM by FbpA is essential for the intrinsic antibiotic resistance and normal colonial morphology of some mycobacteria and support the concept that FbpA-specific inhibitors, alone or in combination with other antibiotics, could provide an effective treatment to tuberculosis and other mycobacterial diseases.     

Structural basis for a functional antagonist in the transforming growth factor beta superfamily

Within the transforming growth factor beta superfamily, the agonist-antagonist relationship between activin and inhibin is unique and critical to integrated reproductive function. Activin acts in the pituitary to stimulate follicle-stimulating hormone, and is antagonized by endocrine acting, gonadally derived inhibin. We have undertaken a mutational analysis of the activin betaA subunit to determine the precise structural aspects that contribute to inhibin antagonism of activin. By substituting specific amino acid residues in the activin betaA subunit with similarly aligned amino acids from the alpha subunit, we have pinpointed the residues required for activin receptor binding and activity, as well as for inhibin antagonism of activin through its receptors. Additionally, we have identified an activin mutant with a higher affinity for the activin type I receptor that provides structural evidence for the evolution of ligand-receptor interactions within the transforming growth factor beta superfamily.     

Synthetic lethal interaction of the mitochondrial phosphatidylethanolamine and cardiolipin biosynthetic pathways in Saccharomyces cerevisiae

Saccharomyces cerevisiae mitochondria contain enzymes required for synthesis of the phospholipids cardiolipin (CL) and phosphatidylethanolamine (PE), which are enriched in mitochondrial membranes. Previous studies indicated that PE may compensate for the lack of CL, and vice versa. These data suggest that PE and CL have overlapping functions and that the absence of both lipids may be lethal. To address this hypothesis, we determined whether the crd1delta mutant, which lacks CL, was viable in genetic backgrounds in which PE synthesis was genetically blocked. Deletion of the mitochondrial PE pathway gene PSD1 was synthetically lethal with the crd1delta mutant, whereas deletion of the Golgi and endoplasmic reticulum pathway genes PSD2 and DPL1 did not result in synthetic lethality. A 20-fold reduction in phosphatidylcholine did not affect the growth of crd1delta cells. Supplementation with ethanolamine, which led to increased PE synthesis, or with propanolamine, which led to synthesis of the novel phospholipid phosphatidylpropanolamine, failed to rescue the synthetic lethality of the crd1delta psd1delta cells. These results suggest that mitochondrial biosynthesis of PE is essential for the viability of yeast mutants lacking CL.