Control of daughter cell fates during asymmetric division: interaction of Numb and Notch

During development of the Drosophila peripheral nervous system, a sensory organ precursor (SOP) cell undergoes rounds of asymmetric divisions to generate four distinct cells of a sensory organ. Numb, a membrane-associated protein, is asymmetrically segregated into one daughter cell during SOP division and acts as an inherited determinant of cell fate. Here, we show that Notch, a transmembrane receptor mediated cell-cell communication, functions as a binary switch in cell fate specification during asymmetric divisions of the SOP and its daughter cells in embryogenesis. Moreover, numb negatively regulates Notch, probably through direct protein-protein interaction that requires the phosphotyrosine-binding (PTB) domain of Numb and either the RAM23 region or the very C-terminal end of Notch. Notch then positively regulates a transcription factor encoded by tramtrack (ttk). This leads to Ttk expression in the daughter cell that does not inherit Numb. Thus, the inherited determinant Numb bestows a bias in the machinery for cell-cell communication to allow the specification of distinct daughter cell fates.

The dendritic cell receptor for endocytosis, DEC-205, can recycle and enhance antigen presentation via major histocompatibility complex class II-positive lysosomal compartments

Many receptors for endocytosis recycle into and out of cells through early endosomes. We now find in dendritic cells that the DEC-205 multilectin receptor targets late endosomes or lysosomes rich in major histocompatibility complex class II (MHC II) products, whereas the homologous macrophage mannose receptor (MMR), as expected, is found in more peripheral endosomes. To analyze this finding, the cytosolic tails of DEC-205 and MMR were fused to the external domain of the CD16 Fcgamma receptor and studied in stable L cell transfectants. The two cytosolic domains each mediated rapid uptake of human immunoglobulin (Ig)G followed by recycling of intact CD16 to the cell surface. However, the DEC-205 tail recycled the CD16 through MHC II-positive late endosomal/lysosomal vacuoles and also mediated a 100-fold increase in antigen presentation. The mechanism of late endosomal targeting, which occurred in the absence of human IgG, involved two functional regions: a membrane-proximal region with a coated pit sequence for uptake, and a distal region with an EDE triad for the unusual deeper targeting. Therefore, the DEC-205 cytosolic domain mediates a new pathway of receptor-mediated endocytosis that entails efficient recycling through late endosomes and a greatly enhanced efficiency of antigen presentation to CD4(+) T cells.

HbA(1c) as a screening tool for detection of Type 2 diabetes: a systematic review

AIM

To assess the validity of glycated haemoglobin A(1c) (HbA(1c)) as a screening tool for early detection of Type 2 diabetes.

METHODS

Systematic review of primary cross-sectional studies of the accuracy of HbA(1c) for the detection of Type 2 diabetes using the oral glucose tolerance test as the reference standard and fasting plasma glucose as a comparison. RESULTS Nine studies met the inclusion criteria. At certain cut-off points, HbA(1c) has slightly lower sensitivity than fasting plasma glucose (FPG) in detecting diabetes, but slightly higher specificity. For HbA(1c) at a Diabetes Control and Complications Trial and UK Prospective Diabetes Study comparable cut-off point of > or = 6.1%, the sensitivity ranged from 78 to 81% and specificity 79 to 84%. For FPG at a cut-off point of > or = 6.1 mmol/l, the sensitivity ranged from 48 to 64% and specificity from 94 to 98%. Both HbA(1c) and FPG have low sensitivity for the detection of impaired glucose tolerance (around 50%). CONCLUSIONS HbA(1c) and FPG are equally effective screening tools for the detection of Type 2 diabetes. The HbA(1c) cut-off point of > 6.1% was the recommended optimum cut-off point for HbA(1c) in most reviewed studies; however, there is an argument for population-specific cut-off points as optimum cut-offs vary by ethnic group, age, gender and population prevalence of diabetes. Previous studies have demonstrated that HbA(1c) has less intra-individual variation and better predicts both micro- and macrovascular complications. Although the current cost of HbA(1c) is higher than FPG, the additional benefits in predicting costly preventable clinical complications may make this a cost-effective choice.

DNA methylation patterns in hereditary human cancers mimic sporadic tumorigenesis

Cancer cells have aberrant patterns of DNA methylation including hypermethylation of gene promoter CpG islands and global demethylation of the genome. Genes that cause familial cancer, as well as other genes, can be silenced by promoter hypermethylation in sporadic tumors, but the methylation of these genes in tumors from kindreds with inherited cancer syndromes has not been well characterized. Here, we examine CpG island methylation of 10 genes (hMLH1, BRCA1, APC, LKB1, CDH1, p16(INK4a), p14(ARF), MGMT, GSTP1 and RARbeta2) and 5-methylcytosine DNA content, in inherited (n = 342) and non-inherited (n = 215) breast and colorectal cancers. Our results show that singly retained alleles of germline mutated genes are never hypermethylated in inherited tumors. However, this epigenetic change is a frequent second "hit", associated with the wild-type copy of these genes in inherited tumors where both alleles are retained. Global hypomethylation was similar between sporadic and hereditary cases, but distinct differences existed in patterns of methylation at non-familial genes. This study demonstrates that hereditary cancers "mimic" the DNA methylation patterns present in the sporadic tumors.

Ti(IV) uptake and release by human serum transferrin and recognition of Ti(IV)-transferrin by cancer cells: understanding the mechanism of action of the anticancer drug titanocene dichloride

The organometallic anticancer agent titanocene dichloride, Cp(2)TiCl(2), is now in phase II clinical trials as an anticancer drug, but its mechanism of action is poorly understood. We show here that the interactions of Cp(2)TiCl(2) with human serum transferrin (hTF) and that of Ti(2)-hTF with adenosine triphosphate (ATP) have characteristics that could allow transferrin to act as a mediator for titanium delivery to tumor cells. Such reactions may therefore be important to the anticancer activity of this new class of drugs. Cp(2)TiCl(2) reacts rapidly with human apo-transferrin under physiological conditions (100 mM NaCl, 25 mM bicarbonate, and 4 mM phosphate, pH 7.4) with carbonate as a synergistic anion. The Cp ligands are released from the drug. Two-dimensional [(1)H, (13)C] NMR studies of epsilon-[(13)C]Met-hTF show that Ti(IV) loads the C-lobe first followed by the N-lobe and binds in the specific Fe(III) sites. The protein conformational changes induced by Ti(IV) appear to be similar to those induced by Fe(III). Carbonate can act as a synergistic anion in Ti(2)-hTF but does not appear to be essential. A specific Ti(IV)-hTF adduct is formed even in the absence of bicarbonate. When the pH of Ti(2)-hTF solutions is lowered, no Ti(IV) is released at the endosomal pH of ca. 5.0-5.5, but one Ti(IV) dissociates between pH 4.5-2.0. In contrast, in the presence of 1 mM ATP, all Ti(IV) is readily released from both lobes when the pH is lowered from 7.0 to 4.5. Moreover, Fe(III) displaces Ti(IV) rapidly from the C-lobe of Ti(2)-hTF (<5 min) but only slowly (days) from the N-lobe. Thus, the species Fe(C)Ti(N)-hTF might also provide a route for Ti(IV) entry into tumor cells via the transferrin receptor. Ti(2)-hTF effectively blocked cell uptake of radiolabeled (59)Fe-hTF into BeWo cells, a human placental choriocarcinoma cell line in culture. These results imply that titanium transferrin might be recognized by the transferrin receptor and be taken up into cancer cells.

Diorganotin(IV) antitumor agent. (C2H5)2SnCl2 (phen)/nucleotides aqueous and solid-state coordination chemistry and its DNA binding studies

This contribution reports a solution and solid-state study of the aqueous nucleotide coordination chemistry of the diethyltin(IV) antitumor agent, (C2H5)2SnCl2(phen). [trans-en2Os(eta-H2)] (CF3SO3)2, a versatile 1H NMR probe for biomolecules, is first used to investigate the interaction of (C2H5)2SnCl2(phen) with DGMP in neutral aqueous solution, and then the synthesis of mixed-ligands complexes formulated as (C2H5)2SnCl(phen)(Nu) (Nu is nucleotide) by reactions of (C2H5)2SnCl2(phen) with equimolar nucleotides under biologically relevant conditions is described. The new complexes were characterized by 500 MHz 1H, 31P NMR spectra; these spectroscopic data suggest that one of cis-chloro atoms in (C2H5)2SnCl2(phen) is substituted by nucleotide, and that Sn(IV) is directly coordinated to the phosphate group of the nucleotide. No evidence was found for the coordination via donor atoms of the base. On the basis of the above model studies, absorbance, fluorescence and cyclic voltammetric methods, viscosity determination, as well as agrose gel electrophoresis of superhelical pBR322 plasmid DNA were used to study the interaction of (C2H5)2SnCl2(phen) with DNA. The results indicate that (C2H5)2SnCl2(phen) binds to DNA by double modes. The drug first reacts electrostatically with the sugar-phosphate backbone of DNA; this results in changes of DNA conformation, and then phen ligand can intercalate into double-helix DNA and cause unwinding of the DNA.

Dosage effects on gene expression in a maize ploidy series

Previous studies on gene expression in aneuploids revealed numerous trans-acting dosage effects. Segmental aneuploidy of each varied chromosomal region exhibited predominantly inverse effects on several target genes. Here, dosage regulation was examined in a maize (Zea mays L.) ploidy series where the complete genomic complement is varied. Total RNA from leaf tissue of monoploid, diploid, triploid, and tetraploid plants (1x, 2x, 3x, and 4x, respectively) was analyzed for the expression of 18 genes. For most tested genes, the transcript level per cell is directly proportional to structural gene dosage; that is, on a per genome basis, there is approximately equal expression among the four ploidies. Exceptional cases show a negative correlation of expression with ploidy or a positive correlation greater than expected from the structural gene dosage. These studies suggest that, in general, as structural gene dosage increases in multiples of the monoploid complement, the absolute level of gene expression per cell increases. In contrast, addition or subtraction of only a single chromosome arm tends to alter gene expression patterns extensively. The combined results of the euploid and aneuploid studies suggest that aneuploid effects result from an altered stoichiometry of the factors contributing to the mechanisms of gene expression.

Cell proliferation and apoptosis

Cell proliferation and cell death are essential yet opposing cellular processes. Crosstalk between these processes promotes a balance between proliferation and death, and it limits the growth and survival of cells with oncogenic mutations. New insights into the mechanisms by which strong signals to proliferate and activation of cyclin-dependent kinases promote apoptosis have recently been published, and a novel cell cycle regulated caspase inhibitor, Survivin, has been described.

Trans-acting dosage effects on the expression of model gene systems in maize aneuploids

The reduction in vigor of aneuploids was classically thought to be due to the imbalance of gene products expressed from the varied chromosome relative to those from the remainder of the genome. In this study, the dosage of chromosomal segments was varied, but the transcript level of most genes encoded therein showed compensation for the number of copies of the gene. Genes whose dosage was not altered were affected by aneuploidy of unlinked chromosomal segments. The phenotypic effects of aneuploidy and of a substantial fraction of quantitative variation are hypothesized to be the consequence of an altered dosage-sensitive regulatory system.

The catalytic subunit of DNA-dependent protein kinase selectively regulates p53-dependent apoptosis but not cell-cycle arrest

DNA damage induced by ionizing radiation (IR) activates p53, leading to the regulation of downstream pathways that control cell-cycle progression and apoptosis. However, the mechanisms for the IR-induced p53 activation and the differential activation of pathways downstream of p53 are unclear. Here we provide evidence that the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) serves as an upstream effector for p53 activation in response to IR, linking DNA damage to apoptosis. DNA-PKcs knockout (DNA-PKcs-/-) mice were exposed to whole-body IR, and the cell-cycle and apoptotic responses were examined in their thymuses. Our data show that IR induction of apoptosis and Bax expression, both mediated via p53, was significantly suppressed in the thymocytes of DNA-PKcs-/- mice. In contrast, IR-induced cell-cycle arrest and p21 expression were normal. Thus, DNA-PKcs deficiency selectively disrupts p53-dependent apoptosis but not cell-cycle arrest. We also confirmed previous findings that p21 induction was attenuated and cell-cycle arrest was defective in the thymoctyes of whole body-irradiated Atm-/- mice, but the apoptotic response was unperturbed. Taken together, our results support a model in which the upstream effectors DNA-PKcs and Atm selectively activate p53 to differentially regulate cell-cycle and apoptotic responses. Whereas Atm selects for cell-cycle arrest but not apoptosis, DNA-PKcs selects for apoptosis but not cell-cycle arrest.

A monoclonal antibody to the DEC-205 endocytosis receptor on human dendritic cells

DEC-205 is a multilectin receptor for adsorptive endocytosis, expressed in mouse dendritic cells (DC) and some epithelia. DEC-205 is homologous to the macrophage mannose receptor (MMR). A cDNA for murine DEC-205 was used to identify 3 overlapping human DEC-205 clones from a lymphocyte library. The human homologue is a transmembrane protein of 1722 aminoacids with 10 externally disposed C-type lectin domains having 77% identity to the mouse counterpart. The NH(2) terminal cysteine-rich and fibronectin type II domains were expressed and used to immunize mice. A hybridoma, MG38, which specifically recognized the immunogen was obtained from a DEC-205 knockout mouse. The antibody precipitated a 205 kD protein from metabolically labeled, monocyte-derived DCs. MG38 labeled mature monocyte-derived DCs but showed weak or no labeling of other peripheral blood mononuclear cells. In tissue sections, MG38 identified DEC-205 on thymic cortical epithelium and DCs in the thymic medulla and tonsillar T cell areas. In contrast, an anti-MMR antibody stained DEC-205 negative, macrophages in the thymus cortex, the trabeculae of the thymus and tonsil, as well as efferent lymphatics in the tonsil. Therefore, the MG38 anti-DEC-205 antibody is useful for identifying DCs and reveals clear differences in sites where MMR and DEC-205 are expressed in lymphoid tissues.

Identification of mutations that disrupt phosphorylation-dependent nuclear export of cyclin D1

Although cyclin D1 is overexpressed in a significant number of human cancers, overexpression alone is insufficient to promote tumorigenesis. In vitro studies have revealed that inhibition of cyclin D1 nuclear export unmasks its neoplastic potential. Cyclin D1 nuclear export depends upon phosphorylation of a C-terminal residue, threonine 286, (Thr-286) which in turn promotes association with the nuclear exportin, CRM1. Mutation of Thr-286 to a non-phosphorylatable residue results in a constitutively nuclear cyclin D1 protein with significantly increased oncogenic potential. To determine whether cyclin D1 is subject to mutations that inhibit its nuclear export in human cancer, we have sequenced exon 5 of cyclin D1 in primary esophageal carcinoma samples and in cell lines derived from esophageal cancer. Our work reveals that cyclin D1 is subject to mutations in primary human cancer. The mutations identified specifically disrupt phosphorylation of cyclin D1 at Thr-286, thereby enforcing nuclear accumulation of cyclin D1. Through characterization of these mutants, we also define an acidic residue within the C-terminus of cyclin D1 that is necessary for recognition and phosphorylation of cyclin D1 by glycogen synthase kinase-3 beta. Finally, through construction of compound mutants, we demonstrate that cell transformation by the cancer-derived cyclin D1 alleles correlates with their ability to associate with and activate CDK4. Our data reveal that cyclin D1 is subject to mutations in primary human cancer that specifically disrupt phosphorylation-dependent nuclear export of cyclin D1 and suggest that such mutations contribute to the genesis and progression of neoplastic growth.

Molecular characteristics of non-small cell lung cancer

We used hierarchical clustering to examine gene expression profiles generated by serial analysis of gene expression (SAGE) in a total of nine normal lung epithelial cells and non-small cell lung cancers. Separation of normal and tumor, as well as histopathological subtypes, was evident by using the 3,921 most abundant transcript tags. This distinction remained when only 115 highly differentially expressed tags were used. Furthermore, these 115 transcript tags clustered into groups suggestive of the unique biological and pathological features of the different tissues examined. Adenocarcinomas were characterized by high-level expression of small airway-associated or immunologically related proteins, whereas squamous cell carcinomas overexpressed genes involved in cellular detoxification or antioxidation. The messages of two p53-regulated genes, p21(WAF1/CIP1) and 14-3-3final sigma, were consistently underexpressed in the adenocarcinomas, suggesting that the p53 pathway itself might be compromised in this cancer type. Gene expression patterns observed by SAGE were consistent with results obtained by quantitative real-time PCR or cDNA array analyses by using a total of 43 lung tumor and normal samples. Thus, although derived from only a few tissue libraries, gene expression profiles obtained by using SAGE most likely represent an unbiased yet distinctive molecular signature for the most common forms of human lung cancer.

tramtrack acts downstream of numb to specify distinct daughter cell fates during asymmetric cell divisions in the Drosophila PNS

Asymmetric cell divisions allow a sensory organ precursor (SOP) cell to generate a neuron and its support cells in the Drosophila PNS. We demonstrate a role of tramtrack (ttk), previously identified as a zinc finger-containing putative transcription factor, in the determination of different daughter cell fates. Both loss of function and overexpression of ttk affect the fates of the SOP progeny. Whereas loss of ttk function transforms support cells to neurons, ttk overexpression results in the reverse transformation. ttk is expressed in support cells but not in neurons. It has been shown that numb, a membrane-associated protein asymmetrically distributed during the SOP division, confers different daughter cell fates. Loss of ttk or numb function results in reciprocal cell fate transformation. Epistatic studies suggest that ttk acts downstream of numb. We propose that ttk executes the command dictated by asymmetrically localized numb to specify distinct daughter cell fates during multiple asymmetric divisions.

Blastomycosis: organ involvement and etiologic diagnosis. A review of 123 patients from Mississippi

Blastomycosis can only be diagnosed through the identification of the yeasts of Blastomyces dermatitidis in body fluids, tissues, or cultured material. The charts from 123 patients treated for blastomycosis at the University of Mississippi Medical Center from January 1980 through May 2000 were reviewed to determine the role of wet preparation, cytology, histology, and culture in diagnosing this fungal disease. Cytology uncovered the etiologic agent in 56.1% of all cases and in 71.8% of pulmonary cases. Cytology also was the first method to disclose the fungus in 57.7% of pulmonary cases. Sputum was the cytology specimen examined in 51% of the patients. In 69 patients with lung involvement, pulmonary cytology was positive in 97% of cases. Wet preparation was the second method to most commonly uncover the fungus in 37.4% of all cases. Histology was the third method with 32.5% of positive cases. Cultures were positive in 64.2% of all cases but they were the first to detect the fungus in only 3.2% of all patients. There was pulmonary involvement in 87% of patients, cutaneous involvement in 20%, osseous involvement in 15%, and central nervous involvement in 3%. In the medical literature the relative proportion of pulmonary versus disseminated disease clearly increased in series reported after 1959. Proportionally to the pattern of patients admitted to the University of Mississippi Medical Center, there is a clear predominance of black males among patients with blastomycosis followed by black females. White females constitute the sex/ethnic group least affected by this fungal disease.

Molecular characterization of a porcine enteric calicivirus genetically related to Sapporo-like human caliciviruses

Porcine enteric calicivirus (PEC) is associated with diarrhea in pigs, and to date it is the only cultivable enteric calicivirus (tissue culture-adapted [TC] PEC/Cowden). Based on sequence analysis of cDNA clones and reverse transcription-PCR products, TC PEC/Cowden has an RNA genome of 7,320 bp, excluding its 3' poly(A)(+) tail. The genome is organized in two open reading frames (ORFs), similar to the organizations of the human Sapporo-like viruses (SLVs) and the lagoviruses. ORF1 encodes the polyprotein that is fused to and contiguous with the capsid protein. ORF2 at the 3' end encodes a small basic protein of 164 amino acids. Among caliciviruses, PEC has the highest amino acid sequence identities in the putative RNA polymerase (66%), 2C helicase (49.6%), 3C-like protease (43.7%), and capsid (39%) regions with the SLVs, indicating that PEC is genetically most closely related to the SLVs. The complete RNA genome of wild-type (WT) PEC/Cowden was also sequenced. Sequence comparisons revealed that the WT and TC PEC/Cowden have 100% nucleotide sequence identities in the 5' terminus, 2C helicase, ORF2, and the 3' nontranslated region. TC PEC/Cowden has one silent mutation in its protease, two amino acid changes and a silent mutation in its RNA polymerase, and five nucleotide substitutions in its capsid that result in one distant and three clustered amino acid changes and a silent mutation. These substitutions may be associated with adaptation of TC PEC/Cowden to cell culture. The cultivable PEC should be a useful model for studies of the pathogenesis, replication, and possible rescue of uncultivable human enteric caliciviruses.

Efficient generation of multi-copy strains for optimizing secretory expression of porcine insulin precursor in yeast Pichia pastoris

AIMS

This study attempted to fully explore the expression potentials of Pichia pastoris for producing porcine insulin precursor (PIP) through PIP copy number optimization.

METHODS AND RESULTS

Multi-copy strains were screened employing a highly efficient improved in vivo method and their copy numbers were quantified by real-time qPCR. A range of Mut(+)P. pastoris strains harbouring 0, 1, 3, 6, 12, 18, 29, 52 copies of PIP were obtained. After 96 h methanol induction, a bell-shaped correlation curve was observed between gene dosage and protein yield, and the maximum PIP expression level of 181 mg l(-1) was achieved by a 12-copy strain. Specific growth rate and methanol utilization capacity were found to decrease remarkably for high copy strains (>12 copies). Transcriptional analysis of KAR2 suggested higher copy strains were suffering more from ER stress.

CONCLUSIONS

A copy number around 12 is optimal for secretory expression of PIP in P. pastoris. Excess PIP gene dosage (>12 copies) significantly impaired the growth of P. pastoris hosts.

SIGNIFICANCE AND IMPACT OF THE STUDY

The methods developed and the discoveries made by this systematical investigation will be helpful to the application and understanding of Pichia pastoris expression system for heterologous overexpression.

Comparative pathogenesis of tissue culture-adapted and wild-type Cowden porcine enteric calicivirus (PEC) in gnotobiotic pigs and induction of diarrhea by intravenous inoculation of wild-type PEC

Porcine enteric calicivirus (PEC/Cowden) causes diarrhea in pigs, grows in cell culture, and is morphologically and genetically similar to the Sapporo-like human caliciviruses. Genetic analysis revealed that the tissue culture-adapted (TC) Cowden PEC has one distant and three clustered amino acid substitutions in the capsid region and 2 amino acid changes in the RNA polymerase region compared to wild-type (WT) PEC (M. Guo, K.-O. Chang, M. E. Hardy, Q. Zhang, A. V. Parwani, and L. J. Saif, J. Virol. 73:9625-9631, 1999). In this study, the TC PEC, passaged in a porcine kidney cell line, and the WT PEC, passaged in gnotobiotic (Gn) pigs, were used to orally inoculate 13 4- to 6-day-old Gn pigs. No diarrhea developed in the TC-PEC-exposed pigs, whereas moderate diarrhea developed in the WT-PEC orally inoculated pigs, persisting for 2 to 5 days. Fecal virus shedding persisting for at least 7 days was detected by both reverse transcription (RT)-PCR and antigen-enzyme-linked immunosorbent assay (antigen-ELISA) in both TC-PEC and WT-PEC orally inoculated pigs but not in mock-inoculated pigs. The PEC particles were detected by immunoelectron microscopy (IEM) in intestinal contents from all the WT-PEC-inoculated pigs, but not from the TC-PEC-inoculated pigs. Mild (duodenum and jejunum) or no (ileum) villous atrophy was observed in histologic sections of the small intestines of TC-PEC-inoculated pigs, whereas WT PEC caused mild to severe (duodenum and jejunum) villous atrophy and fusion. Scanning electron microscopy confirmed mild shortening and blunting of villi in the duodenum and jejunum of the TC-PEC-inoculated pigs, in contrast to moderate to severe villous shortening and blunting in the duodenum and jejunum of WT-PEC-inoculated pigs. Higher numbers of PEC antigen-positive villous enterocytes were detected by immunofluorescent (IF) staining in the proximal small intestine of the WT-PEC-inoculated pigs, in contrast to low numbers of PEC antigen-positive enterocytes in only one of four TC-PEC-inoculated pigs. No PEC antigen-positive cells were observed in the colon or extraintestinal tissues of all inoculated pigs or in the small intestine of one mock-inoculated pig. Thus, the TC PEC was at least partially attenuated (no diarrhea, mild lesions) after serial passage in cell culture. In further experiments, three 4- to 6-day-old Gn pigs were intravenously (i.v.) inoculated with WT PEC, and all pigs developed diarrhea and villous atrophy in the small intestines resembling that observed in the orally inoculated pigs. Fecal viral shedding persisting for 8 days was detected by both RT-PCR and antigen-ELISA, and PEC was detected by IEM in feces or intestinal contents. The PEC RNA and antigens (at low titers) were detected in acute-phase sera from all the WT-PEC i.v.-inoculated pigs and also from seven of nine of the WT-PEC orally inoculated pigs. Oral or i.v. inoculation of four additional pigs with the PEC-positive acute-phase sera induced diarrhea, small intestinal lesions, PEC shedding in feces, and seroconversion to PEC, confirming the occurrence of viremia during PEC infection, with infectious PEC present in acute-phase sera. No diarrhea, histopathologic changes, or IF staining in the small intestine or fecal or serum detection of PEC was evident in two pigs i.v. mock-inoculated or a pig inoculated i.v. with inactivated WT PEC. To our knowledge, this is the first report of an attenuated enteric calicivirus, the induction of diarrhea, and intestinal lesions in Gn pigs caused by i.v. inoculation of WT PEC and the presence of viremia following PEC infection.

Inflammation and oxidative stress induced by cigarette smoke in Lewis rat brains

Exposure to cigarette smoke has been associated with an increased risk of neurological diseases such as stroke, Alzheimer's disease and multiple sclerosis. In these studies, serum and brain sections from Lewis rats or those exposed to cigarette smoke and control rats were examined for evidence of increased inflammation and oxidative stress. Immunocytochemical staining of brain sections from CS-exposed rats showed increased expression of class II MHC and, in ELISA, levels of IFN-gamma and TNF-α were higher than for non-exposed rats. In polymerase chain reaction assays there was increased interferon-gamma, TNF-α, IL-1α, IL-1β, IL-23, IL-6, IL-23, IL-17, IL-10, TGF-β, T-bet and FoxP3 gene expression with CS exposure. There was also markedly elevated MIP-1α/CCL3, less prominent MCP-1/CCL2 and no elevation of SDF-1α gene expression. Analysis of samples from CS-exposed and control rats for anti-oxidant expression showed no significant difference in serum levels of glutathione and, in brain, similar levels of superoxide dismutase and decreased thioredoxin gene expression. In contrast, there was increased brain gene expression for the pro-oxidants iNOS and the NADPH components NOX4, dual oxidase 1 and p22(phox). Nrf2 expression, which is typically triggered as a secondary response to oxidative stress, was also increased in brains from CS-exposed rats with nuclear translocation of this protein from cytoplasm demonstrated in astrocytes in association with increased expression of the aryl hydrocarbon receptor gene, an Nrf2 target. These studies, therefore, demonstrate that CS exposure in these animals can trigger multiple immune and oxidative responses that may have important roles in the pathogenesis of CNS inflammatory neurological diseases.

Exercise preconditioning reduces neuronal apoptosis in stroke by up-regulating heat shock protein-70 (heat shock protein-72) and extracellular-signal-regulated-kinase 1/2

Exercise preconditioning induces neuroprotection after stroke. We investigated the beneficial role of heat shock protein-70 (HSP-70) and phosphorylated extracellular-signal-regulated-kinase 1/2 (pERK 1/2), as they pertain to reducing apoptosis and their influence on Bcl-x(L), Bax, and apoptosis-inducing factor (AIF) in rats subjected to ischemia and reperfusion. Adult male Sprague-Dawley rats were subjected to 30 min of exercise on a treadmill for 1, 2, or 3 weeks. Stroke was induced by a 2-h middle cerebral artery (MCA) occlusion using an intraluminal filament. Protein levels of HSP-70, pERK 1/2, Bcl-x(L), Bax, and AIF were analyzed using Western blot. Neuroprotection was based on levels of apoptosis (TUNEL) and infarct volume (Nissl staining). Immunocytochemistry was used for cellular expression of HSP-70 and pERK 1/2. Significant (P<0.05) up-regulation of HSP-70 and pERK 1/2 after 3 weeks of exercise coincided with significant (P<0.05) reduction in neuronal apoptosis and brain infarct volume. Inhibition of either one of these two factors showed a significant (P<0.05) reversal in the neuroprotection. Bax and AIF were down-regulated, while levels of Bcl-x(L) were up-regulated in response to stroke after exercise. Inhibiting HSP-70 or pERK 1/2 reversed this resultant increase or decrease. Our results indicate that exercise diminishes neuronal injury in stroke by up-regulating HSP-70 and ERK 1/2.

Changes in Chemical Composition of Alxa Bactrian Camel Milk During Lactation

Changes in chemical composition of Alxa bactrian camels reared in Inner Mongolia (China) during lactation were investigated. Colostrum and milk samples from 10 nomadic female camels in their first season of lactation were collected periodically from parturition until 90 d postpartum (PP). The average contents of gross composition were 14.23% protein, 4.44% lactose, 0.27% fat, 0.77% ash, and 20.16% total solids in colostrum at 2 h PP, and the respective mean values were 3.55, 4.24, 5.65, 0.87, and 14.31% for regular milk on d 90. A 15-fold increase was shown in fat content during the first 24 h, whereas a sharp decrease was shown during the first 12 h of lactation in protein, ash, and total solids contents. Variation in lactose content was small (4.24 to 4.71%) throughout the study period. Total N, nonprotein N, casein N, and whey protein N were found to be 2.23, 0.06, 0.86, and 1.31 g/100 mL for the colostrum at 2 h PP; and 0.56, 0.04, 0.45, and 0.07 g/100 mL for the milk at 90 d PP. Percentages of caseins increased steadily, whereas whey proteins declined gradually until 3 mo of lactation. Gas liquid chromatography analysis of milk fat showed that the content of even-numbered saturated fatty acids (C12:0-C18:0) in camel colostrum (2 h to 7 d PP) was lower than that of regular milk (15 to 90 d PP). The predominant saturated fatty acids were C14:0, C16:0, and C18:0, regardless of the stage of lactation. There was a considerable level of polyunsaturated fatty acids (mainly C18:1) in Alxa camel's milk fat. The levels of Ca, P, Na, K, and Cl were 222.58, 153.74, 65.0, 136.5, and 141.1 mg/100 g, respectively, at 2 h PP; the values of the minerals were 154.57, 116.82, 72.0, 191.0, and 152.0 mg/100 g, respectively, for the regular milk on d 90. The levels of vitamins A, C, E, B1, B2, B6, and D were 0.97, 29.60, 1.45, 0.12, 1.24, 0.54 mg/L, and 640 IU/L, respectively, in Alxa camel milk at 90 d PP. Vitamin A and C contents were higher and vitamins E and B1 were lower than those in colostrum. Sodium dodecyl sulfate-PAGE and densitometry results demonstrated that Alxa camel colostrum is rich in immunoglobulins, serum albumin, and 2 unknown fractions, which are reduced in amount (%) within 2 d of lactation. It seems that there is lack of beta-lactoglobulin in Alxa camel milk, whereas casein and -lactalbumin start at a low level and increase gradually until they reach their regular levels in the milk.

Improvement of skin paddle survival by application of vascular endothelial growth factor in a rat TRAM flap model

The effect of vascular endothelial growth factor (VEGF) on skin flap survival and its ability to induce a pharmacological delay by promoting angiogenesis in a flap was studied in a rat transverse rectus abdominis musculocutaneous flap, using a 3 x 8-cm skin paddle with the inferior epigastric vessels as its main vascular supply. Forty-three Sprague-Dawley rats were divided into four groups. In group 1, VEGF was injected into the femoral vein after the flap was elevated. In group 2, VEGF was injected intra-arterially into the flap through the superior epigastric artery after the flap was elevated. In group 3, VEGF was injected into the subcutaneous fascial layer in the area where the flap would be dissected, and the flap was then raised 7 days after injection. In group 4, the flap was dissected and replaced, using saline injection as the control. On postoperative day 5, the survival area of each skin paddle was measured and the flap was harvested for histological analysis. The results showed that the mean survival area +/- standard deviation for the skin paddle was 6.82 +/- 4.89 cm2 (28.4 +/- 20.4% of the whole skin paddle) in the control group, and 4.2 +/- 3.0 cm2 (17.5 +/- 12.5%) and 6.02 +/- 5.97 cm2 (25.1 +/- 24.9%) in the groups with VEGF systemic and intra-arterial administration respectively. The skin survival area in the group with preoperative subcutaneous administration of VEGF was 17.85 +/- 2.88 cm2 (74.4 +/- 12%), which was significantly higher than the other three groups (p < 0.01). Histological semiquantitative analysis showed increased neovascularization in the flap treated with VEGF preoperatively. The data demonstrate that preoperative treatment with VEGF can induce angiogenesis and enhance skin paddle survival in a musculocutaneous flap.

Hypoxia-mimetic agents desferrioxamine and cobalt chloride induce leukemic cell apoptosis through different hypoxia-inducible factor-1alpha independent mechanisms

Hypoxia presents pro-apoptotic and anti-apoptotic biphasic effects that appear to be dependent upon cell types and conditions around cells. The substantial reports demonstrated that commonly used hypoxia-mimetic agents cobalt chloride (CoCl(2)) and desferrioxamine (DFO) could also induce apoptosis in many different kinds of cells, but the mechanism was poorly understood. In this work, we compare the apoptosis-inducing effects of these two hypoxia-mimetic agents with acute myeloid leukemic cell lines NB4 and U937 as in vitro models. The results show that both of them induce these leukemic cells to undergo apoptosis with a loss of mitochondrial transmembrane potentials (DeltaPsi m), the activation of caspase-3/8 and the cleavage of anti-apoptotic protein Mcl-1, together with the accumulation of hypoxia-inducible factor-1 alpha (HIF-1alpha) protein, a critical regulator for the cellular response to hypoxia. Metavanadate and sodium nitroprusside significantly abrogate DFO rather than CoCl(2)-induced mitochondrial Delta Psi m collapse, caspase-3/8 activation, Mcl-1 cleavage and apoptosis, but they fail to influence DFO and CoCl(2)-induced HIF-1alpha protein accumulation. Moreover, inducible expression of HIF-1alpha gene dose not alter DFO and CoCl(2)-induced apoptosis in U937 cells. In conclusion, these results propose that although both DFO and CoCl(2)-induced leukemic cell apoptosis by mitochondrial pathway-dependent and HIF-1alpha-independent mechanisms, DFO and CoCl(2)-induced apoptosis involves different initiating signal pathways that remain to be investigated.