Caveolin-1 null mice are viable but show evidence of hyperproliferative and vascular abnormalities

Caveolin-1 is the principal structural protein of caveolae membranes in fibroblasts and endothelia. Recently, we have shown that the human CAV-1 gene is localized to a suspected tumor suppressor locus, and mutations in Cav-1 have been implicated in human cancer. Here, we created a caveolin-1 null (CAV-1 -/-) mouse model, using standard homologous recombination techniques, to assess the role of caveolin-1 in caveolae biogenesis, endocytosis, cell proliferation, and endothelial nitric-oxide synthase (eNOS) signaling. Surprisingly, Cav-1 null mice are viable. We show that these mice lack caveolin-1 protein expression and plasmalemmal caveolae. In addition, analysis of cultured fibroblasts from Cav-1 null embryos reveals the following: (i) a loss of caveolin-2 protein expression; (ii) defects in the endocytosis of a known caveolar ligand, i.e. fluorescein isothiocyanate-albumin; and (iii) a hyperproliferative phenotype. Importantly, these phenotypic changes are reversed by recombinant expression of the caveolin-1 cDNA. Furthermore, examination of the lung parenchyma (an endothelial-rich tissue) shows hypercellularity with thickened alveolar septa and an increase in the number of vascular endothelial growth factor receptor (Flk-1)-positive endothelial cells. As predicted, endothelial cells from Cav-1 null mice lack caveolae membranes. Finally, we examined eNOS signaling by measuring the physiological response of aortic rings to various stimuli. Our results indicate that eNOS activity is up-regulated in Cav-1 null animals, and this activity can be blunted by using a specific NOS inhibitor, nitro-l-arginine methyl ester. These findings are in accordance with previous in vitro studies showing that caveolin-1 is an endogenous inhibitor of eNOS. Thus, caveolin-1 expression is required to stabilize the caveolin-2 protein product, to mediate the caveolar endocytosis of specific ligands, to negatively regulate the proliferation of certain cell types, and to provide tonic inhibition of eNOS activity in endothelial cells.

Caveolin-1 regulates transforming growth factor (TGF)-beta/SMAD signaling through an interaction with the TGF-beta type I receptor

Transforming growth factor-beta (TGF-beta) signaling proceeds from the cell membrane to the nucleus through the cooperation of the type I and II serine/threonine kinase receptors and their downstream SMAD effectors. Although various regulatory proteins affecting TGF-beta-mediated events have been described, relatively little is known about receptor interactions at the level of the plasma membrane. Caveolae are cholesterol-rich membrane microdomains that, along with their marker protein caveolin-1 (Cav-1), have been implicated in the compartmentalization and regulation of certain signaling events. Here, we demonstrate that specific components of the TGF-beta cascade are associated with caveolin-1 in caveolae and that Cav-1 interacts with the Type I TGF-beta receptor. Additionally, Cav-1 is able to suppress TGF-beta-mediated phosphorylation of Smad-2 and subsequent downstream events. We localize the Type I TGF-beta receptor interaction to the scaffolding domain of Cav-1 and show that it occurs in a physiologically relevant time frame, acting to rapidly dampen signaling initiated by the TGF-beta receptor complex.

Plasma glucose levels and diabetes are independent predictors for mortality and morbidity in patients with SARS

AIMS

To investigate the relationships between a known history of diabetes and ambient fasting plasma glucose (FPG) levels with death and morbidity rates in patients with severe acute respiratory syndrome (SARS).

METHODS

In this retrospective analysis, the clinical and biochemical characteristics of 135 patients who had died from SARS, 385 survivors of SARS and 19 patients with non-SARS pneumonia were compared.

RESULTS

All patients were treated according to a predefined protocol. Before steroid treatment, the mean FPG level was significantly higher in the SARS group (deceased vs. survivors vs. non-SARS pneumonia group: 9.7 +/- 5.2 vs. 6.5 +/- 3.0 vs. 5.1 +/- 1.0 mmol/l, P < 0.01). In the SARS group, the percentage of patients with a known history of diabetes was significantly higher in the deceased patients than in the survivors (21.5% vs. 3.9%, P < 0.01). Among patients with no known history of diabetes and before commencement of steroid therapy, those who had hypoxaemia (SaO(2) < 93%) had higher FPG levels than those who did not have hypoxia in both the survivor (8.7 +/- 4.9 vs. 6.3 +/- 2.1 mmol/l, P < 0.001) and deceased (9.8 +/- 4.8 vs. 7.2 +/- 1.5 mmol/l, P < 0.001) groups. A known history of diabetes [odds ratio (OR) 3.0, 95% confidence interval (CI) 1.4, 6.3; P = 0.005] and FPG > or = 7.0 mmol/l before steroid treatment (OR 3.3, 95% CI 1.4, 7.7, P = 0.006) were independent predictors of death. During the course of the illness, FPG levels were negatively associated with SaO(2) (beta =-0.682 +/- 0.305, P = 0.025, general estimation equation model) in SARS patients. Survival analysis showed that FPG was independently associated with an increased hazard ratio (HR) of mortality (HR = 1.1, 95% CI 1.0, 1.1, P = 0.001) and hypoxia (HR = 1.1, 95% CI 1.0, 1.1, P = 0.002) after controlling for age and gender.

CONCLUSIONS

A known history of diabetes and ambient hyperglycaemia were independent predictors for death and morbidity in SARS patients. Metabolic control may improve the prognosis of SARS patients.

Caveolin-3 null mice show a loss of caveolae, changes in the microdomain distribution of the dystrophin-glycoprotein complex, and t-tubule abnormalities

Caveolin-3, a muscle-specific caveolin-related protein, is the principal structural protein of caveolae membrane domains in striated muscle cells. Recently, we identified a novel autosomal dominant form of limb-girdle muscular dystrophy (LGMD-1C) in humans that is due to mutations within the coding sequence of the human caveolin-3 gene (3p25). These LGMD-1C mutations lead to an approximately 95% reduction in caveolin-3 protein expression, i.e. a caveolin-3 deficiency. Here, we created a caveolin-3 null (CAV3 -/-) mouse model, using standard homologous recombination techniques, to mimic a caveolin-3 deficiency. We show that these mice lack caveolin-3 protein expression and sarcolemmal caveolae membranes. In addition, analysis of skeletal muscle tissue from these caveolin-3 null mice reveals: (i) mild myopathic changes; (ii) an exclusion of the dystrophin-glycoprotein complex from lipid raft domains; and (iii) abnormalities in the organization of the T-tubule system, with dilated and longitudinally oriented T-tubules. These results have clear mechanistic implications for understanding the pathogenesis of LGMD-1C at a molecular level.

Source diagnostics of polycyclic aromatic hydrocarbons based on species ratios: a multimedia approach

Often, the sources of polycyclic aromatic hydrocarbons (PAHs) in environmental media can be identified by comparing the ratios of concentrations of selected pairs of PAH congeners in the source emissions to the ratios in the contaminated environmental media. However, these ratios can be altered significantly due to differences in the transport of the PAH compounds in a multimedia environment. To examine such changes, a fugacity model was applied to PAH ratios in a model environment. A linear relationship between the rate of emission and the bulk media concentration was identified for each PAH compound in an environmental medium at steady state and was quantified by a receptor-to-source ratio (RRS). It was demonstrated that the RRS values of the two congeners usually differ significantly. Consequentially, PAH ratios changed remarkably from the source emissions to various environmental media. A site-specific rectification factor (RF) was defined as the ratio of the two RRS values of the paired congeners for a specific PAH ratio in a given medium, which can be applied to account for the ratio changes in a multimedia environment. The PAH ratio changes were further verified with the surface soil data collected from Tianjin, China, and the observed changes of PAH ratios were compared favorably with the model predictions. The sensitivity analysis revealed that PAH ratios of the low molecular weight compounds were less stable. The most influential parameters controlling PAH ratios were those pertaining to dry precipitation, surface-to-air diffusion, degradation in air and water, and exchange between water and sediment.

Genes encoding human caveolin-1 and -2 are co-localized to the D7S522 locus (7q31.1), a known fragile site (FRA7G) that is frequently deleted in human cancers

The (CA)n microsatellite repeat marker D7S522 is located on human chromosome 7q31.1 and is frequently deleted in a variety of human cancers, including squamous cell carcinomas of the head and neck, prostate cancers, renal cell carcinomas, ovarian adenocarcinomas, colon carcinomas, and breast cancers. In addition, D7S522 spans FRA7G, a known common fragile site on human chromosome 7. Based on these studies, it has been proposed that an as yet unidentified tumor suppressor gene (or genes) is contained within or located in close proximity to this locus. However, the identity of the candidate tumor suppressor gene at the D7S522 locus remains unknown. Here, we show that the human genes encoding caveolins 1 and 2 are contained within the same human genomic BAC clones and co-localize to the q31.1-q31.2 region of human chromosome 7, as seen by FISH analysis. In addition, we determined the intron-exon boundaries of the human caveolin-1 and -2 genes. The human caveolin-1 gene contains three exons, while the human caveolin-2 gene contains two exons. Interestingly, the boundary of the last exon of the human caveolin-1 and caveolin-2 genes are analogous, suggesting that they arose through gene duplication at this locus. (CA)n microsatellite repeat marker analysis of these caveolin genomic clones indicates they contain the marker D7S522 (located at 7q31.1), but not other microsatellite repeat markers tested. The close proximity of caveolins 1 and 2 to the D7S522 locus was independently confirmed by using a panel of MIT/Whitehead human STS markers that are known to map in the neighborhood of the D7S522 locus. As it has been previously shown that caveolin 1 possesses transformation suppressor activity (Koleske, A.J., Baltimore, D. and M.P. Lisanti (1995) Proc. Natl. Acad. Sci. USA 92, 1381-1385; Engelman, J.A. et al. (1997) J. Biol. Chem. 272, 16374-16381), we propose that the caveolin-1 gene may represent the candidate tumor suppressor gene at the D7S522 locus on human chromosome 7q31.1.

Primitive deuterostomes from the Chengjiang Lagerstätte (Lower Cambrian, China)

Cambrian fossil-Lagerstätten (sites of exceptional fossil preservation), such as those from Chengjiang (Lower Cambrian) and the Burgess Shale (Middle Cambrian), provide our best window into the Cambrian 'explosion'. Such faunas are known from about 40 localities, and have yielded a widely disparate series of taxa ranging from ctenophores to agnathan fish. Recent excavations of the Chengjiang fossil-Lagerstätte, known from a series of sites near Kunming in Yunnan, south China, have resulted in the discovery of several new forms. In conjunction with material described earlier, these provide evidence for a new group of metazoans, the vetulicolians. Several features, notably a series of gill slits, suggest that this group can throw light on an early stage of deuterostome diversification.

Keratinocyte growth factor modulates alveolar epithelial cell phenotype in vitro: expression of aquaporin 5

We investigated the role of keratinocyte growth factor (KGF) in regulation of alveolar epithelial cell (AEC) phenotype in vitro. Effects of KGF on cell morphology, expression of surfactant apoproteins A, B, and C (SP-A, -B, and -C), and expression of aquaporin 5 (AQP5), a water channel present in situ on the apical surface of alveolar type I (AT1) cells but not expressed in alveolar type II (AT2) cells, were evaluated in AECs grown in primary culture. Observations were made on AEC monolayers grown in serum-free medium without KGF (control) or grown continuously in the presence of KGF (10 ng/ml) from either Day 0 (i.e., the time of plating) or Day 4 or 6 through Day 8 in culture. AECs monolayers express AQP5 only on their apical surfaces as determined by cell surface biotinylation studies. Control AECs grown in the absence of KGF through Day 8 express increasing levels of AQP5, consistent with transition toward the AT1 cell phenotype. Exposure of AECs to KGF from Day 0 results in decreased AQP5 expression, retention of a cuboidal morphology, and greater numbers of lamellar bodies relative to control on Day 8 in culture. AECs treated with KGF from Day 4 or 6 exhibit a decrease in AQP5 expression through subsequent days in culture, as well as an increase in expression of surfactant apoproteins. These data, showing that KGF both prevents and reverses the increase in AQP5 (and decrease in surfactant apoprotein) expression that accompanies progression of the AT2 toward the AT1 cell phenotype, support the concepts that transdifferentiation between AT2 and AT1 cell phenotypes is at least partially reversible and that KGF may play a major role in modulating AEC phenotype.

In vivo 31P magnetic resonance spectroscopy of human brain at 7 T: an initial experience

In vivo (31)P spectra were acquired from the human primary visual cortex at 7 T. The relaxation times of the cerebral metabolites, intracellular pH, rate constant (k(f)) of the creatine kinase (CK) reaction, and nuclear Overhauser enhancement (NOE) on the detected phosphorus moieties from irradiation of the water spins were measured from normal subjects. With a 5-cm-diameter surface coil, 3D (31)P chemical shift imaging was performed with a spatial resolution of 7.5 ml and an acquisition resolution of 8 min, resulting in a signal-to-noise ratio (SNR) for phosphocreatine (PCr) resonance of 32. The apparent T(1) and T(2) of PCr measured at 7 T were 3.37 +/- 0.29 s and 132.0 +/- 12.8 ms, respectively, which were considerably longer than those of adenosine triphosphate (ATP) (T(1): 1.02-1.27 s; T(2): 25-26 ms). The NOE measured in this study was 24.3% +/- 1.6% for PCr, and 10% for ATP. The k(f) measured in the human primary visual cortex was 0.24 +/- 0.03 s(-1). The results from this study suggest that ultra-high-field strength is advantageous for performing in vivo (31)P magnetic resonance spectroscopy (MRS) in the human brain.

p42/44 MAP kinase-dependent and -independent signaling pathways regulate caveolin-1 gene expression. Activation of Ras-MAP kinase and protein kinase a signaling cascades transcriptionally down-regulates caveolin-1 promoter activity

Caveolin-1 is a principal component of caveolae membranes in vivo. Caveolin-1 mRNA and protein expression are down-regulated in NIH 3T3 cells in response to transformation by activated oncogenes, such as H-Ras(G12V) and v-Abl. The mechanisms governing this down-regulation event remain unknown. Here, we show that caveolin-1 gene expression is directly regulated by activation of the Ras-p42/44 MAP kinase cascade. Down regulation of caveolin-1 protein expression by Ras is independent of (i) the type of activating mutation (G12V versus Q61L) and (ii) the form of activated Ras transfected (H-Ras versus K-Ras versus N-Ras). Treatment of Ras or Raf-transformed NIH 3T3 cells with a well characterized MEK inhibitor (PD 98059) restores caveolin-1 protein expression. In contrast, treatment of v-Src and v-Abl transformed NIH 3T3 cells with PD 98059 does not restore caveolin-1 expression. Thus, there must be at least two pathways for down-regulating caveolin-1 expression: one that is p42/44 MAP kinase-dependent and another that is p42/44 MAP kinase-independent. We focused our efforts on the p42/44 MAP kinase-dependent pathway. The activity of a panel of caveolin-1 promoter constructs was evaluated using transient expression in H-Ras(G12V) transformed NIH 3T3 cells. We show that caveolin-1 promoter activity is up-regulated approximately 5-fold by inhibition of the p42/44 MAP kinase cascade. Using electrophoretic mobility shift assays we provide evidence that the caveolin-1 promoter (from -156 to -561) is differentially bound by transcription factors in normal and H-Ras(G12V)-transformed cells. We also show that activation of protein kinase A (PKA) signaling is sufficient to down-regulate caveolin-1 protein expression and promoter activity. Thus, we have identified two signaling pathways (Ras-p42/44 MAP kinase and PKA) that transcriptionally down-regulate caveolin-1 gene expression.

Demonstration of a neutral atom controlled-NOT quantum gate

We present the first demonstration of a CNOT gate between two individually addressed neutral atoms. Our implementation of the CNOT uses Rydberg blockade interactions between neutral atoms held in optical traps separated by >8 microm. Using two different gate protocols we measure CNOT fidelities of F=0.73 and 0.72 based on truth table probabilities. The gate was used to generate Bell states with fidelity F=0.48+/-0.06. After correcting for atom loss we obtain an a posteriori entanglement fidelity of F=0.58.

Crowded little caves: structure and function of caveolae

Caveolae are small vesicular invaginations of the cell membrane. It is within this organelle that cells perform transcytosis, potocytosis and signal transduction. These "little caves" are composed of a mixture of lipids and proteins unlike those found in the plasma membrane proper. The chief structural proteins of caveolae are caveolins. To date, three caveolins (Cav-1, -2 and -3) with unique tissue distributions have been identified. Caveolins form a scaffold onto which many signalling molecules can assemble, to generate pre-assembled signalling complexes. In addition to concentrating these signal transducers within a distinct region of the plasma membrane, caveolin binding may functionally regulate the activation state of caveolae-associated signalling molecules.

Sequence and detailed organization of the human caveolin-1 and -2 genes located near the D7S522 locus (7q31.1). Methylation of a CpG island in the 5' promoter region of the caveolin-1 gene in human breast cancer cell lines

The CA microsatellite repeat marker, D7S522, is located at the center of a approximately 1000 kb smallest common deleted region that is lost in many forms of human cancer. It has been proposed that a putative tumor suppressor gene lies in close proximity to D7S522, within this smallest common deleted region. However, the genes located in proximity to D7S522 have remained elusive. Recently, we identified five independent BAC clones (approximately 100-200 kb) containing D7S522 and the human genes encoding caveolins 1 and 2. Here, we present the detailed organization of the caveolin locus and its relationship to D7S522, as deduced using a shot-gun sequencing approach. We derived two adjacent contigs for a total coverage of approximately 250 kb. Analysis of these contigs reveals that D7S522 is located approximately 67 kb upstream of the caveolin-2 gene and that the caveolin-2 gene is located approximately 19 kb upstream of the caveolin-1 gene, providing for the first time a detailed genetic map of this region. Further sequence analysis reveals many interesting features of the caveolin genes; these include the intron-exon boundaries and several previously unrecognized CA repeats that lie within or in close proximity to the caveolin genes. The first and second exons of both caveolin genes are embedded within CpG islands. These results suggest that regulation of caveolin gene expression may be controlled, in part, by methylation of these CpG regions. In support of this notion, we show here that the CGs in the 5' promoter region of the caveolin-1 gene are functionally methylated in two human breast cancer cell lines (MCF7 and T-47D) that fail to express the caveolin-1 protein. In contrast, the same CGs in cultured normal human mammary epithelial cells (NHMECs) are non-methylated and these cells express high levels of the caveolin-1 protein. Comparison of the human locus with the same locus in the pufferfish Fugu rubripes reveals that the overall organization of the caveolin-1/-2 locus is conserved from pufferfish to man. In conclusion, our current studies provide a systematic basis for diagnostically evaluating the potential deletion, mutation, or methylation of the caveolin genes in a variety of human tumors.

Chromosomal localization, genomic organization, and developmental expression of the murine caveolin gene family (Cav-1, -2, and -3). Cav-1 and Cav-2 genes map to a known tumor suppressor locus (6-A2/7q31)

Caveolins (Cav-1, -2, and -3) are a gene family of cytoplasmic membrane-anchored scaffolding proteins that: (i) help to sculpt caveolae membranes from the plasma membrane proper; and (ii) participate in the sequestration of inactive signaling molecules. In the adult, caveolin-1 and -2 are co-expressed and are most abundant in type I pneumocytes, endothelia, fibroblastic cells and adipocytes, while the expression of caveolin-3 is restricted to striated muscle cells. However, little is known regarding the genomic organization and developmental expression of the caveolin gene family. Here, using the mouse as a model system, we examine the chromosomal localization, the detailed intron-exon organization, and developmental expression pattern of the caveolin gene family. cDNAs encoding caveolin-1, -2, and -3 were used as probes to isolate murine genomic clones containing these genes. Fluorescence in situ hybridization (FISH) analysis using these genomic clones as probes reveals that all three caveolin genes are localized to murine chromosome 6. Specifically, caveolin-1 and -2 co-localize to chromosomal region 6-A2, while caveolin-3 is located within the chromosomal region 6-E1. Searches of the NCBI Human/Mouse Homology map indicate that murine region 6-A2 corresponds to human chromosome 7q31. As this region (6-A2/7q31) is the site of an as yet unidentified tumor suppressor gene(s), our mapping studies clearly define caveolin-1 and caveolin-2 as candidate genes that may be deleted at these loci. All three caveolin genes show similar intron-exon organization, with the last exon of each gene encoding the bulk of the known caveolin functional domains. The boundary position of the last exon is essentially identical in all three caveolin genes, suggesting that they may have arisen through gene duplication events. Developmentally, all three caveolins were expressed late during mouse embryogenesis as assessed by Northern and Western blot analysis. We examined the localization of the caveolin proteins in sections of day 16 mouse embryos using a well-characterized panel of antibody probes. Caveolin-1 and -2 were most abundantly expressed in the developing lung parenchyma, while caveolin-3 was most abundantly expressed in developing tissues that consist primarily of skeletal muscle cells. As the expression of all three caveolins in the adult is highest in terminally differentiated cell types, this is consistent with the idea that caveolins may be viewed as late markers of differentiation during embryogenesis.

Event related potentials during object recognition tasks

In our previous studies, we have demonstrated an ERP correlate of visual memory with a modified delayed matching-to-sample paradigm using a series of nonsense line drawings or faces as stimuli. In this experiment, we employed pictures of objects to determine whether the ERP can reflect the object recognition process and whether visual stimuli with a verbal label would result in a different topographic distribution from past topography obtained with visual stimuli without a verbal label. The results of this study suggest that the amplitude of the ERP component (c247) to repeated (primed) pictures of common objects was significantly decreased as compared to the unrepeated (unprimed) pictures; the latency for the peak of c247 was decreased for the repeated compared to the unrepeated, and the response time was also significantly shorter to the repeated picture stimuli than to the unrepeated; the topographical distribution of c247 was mainly located in the occipitotemporal areas of the brain. However, the source energy density map showed that the topographic involvement of the brain regions to the c247 was different in the matching and nonmatching trials.

Salmonella enterica serovar typhi uses type IVB pili to enter human intestinal epithelial cells

DNA sequencing upstream of the Salmonella enterica serovar Typhi pilV and rci genes previously identified in the ca. 118-kb major pathogenicity island (X.-L. Zhang, C. Morris, and J. Hackett, Gene 202:139-146, 1997) identified a further 10 pil genes apparently forming a pil operon. The product of the pilS gene, prePilS protein (a putative type IVB structural prepilin) was purified, and an anti-prePilS antiserum was raised in mice. Mutants of serovar Typhi either lacking the whole pil operon or with an insertion mutation in the pilS gene were constructed, as was a strain in which the pilN to pilV genes were driven by the tac promoter. The pil(+) strains synthesized type IVB pili, as judged by (i) visualization in the electron microscope of thin pili in culture supernatants of one such strain and (ii) the presence of PilS protein (smaller than the prePilS protein by removal of the leader peptide) on immunoblotting of material pelleted by high-speed centrifugation of either the culture supernatant or sonicates of pil(+) strains. Control pil mutants did not express the PilS protein. A pilS mutant of serovar Typhi entered human intestinal INT407 cells in culture to levels only 5 to 25% of those of the wild-type strain, and serovar Typhi entry was strongly inhibited by soluble prePilS protein (50% inhibition of entry at 1.4 microM prePilS).

An Early Cambrian tunicate from China

Like the Burgess Shales of Canada, the Chengjiang Lagerstätte from the Lower Cambrian of China is renowned for the detailed preservation as fossils of delicate, soft-bodied creatures, providing an insight into the Cambrian explosion. The fossils of possible hemichordate chordates and vertebrates have attracted particular attention. Tunicates, or urochordates, comprise the most basal chordate clade, and details of their evolution could be important in understanding the sequence of character acquisition that led to the emergence of chordates and vertebrates. However, definitive fossils of tunicates from the Cambrian are scarce or debatable. Here we report a probable tunicate Cheungkongella ancestralis from the Chengjiang fauna. It resembles the extant ascidian tunicate genus Styela whose morphology could be useful in understanding the origin of the vertebrates.

A new species of yunnanozoan with implications for deuterostome evolution

Yunnanozoans are a distinctive clade of Lower Cambrian metazoans. Although widely accepted as deuterostomes, their exact placement within this superphylum is controversial. Here we describe a new species of Haikouella (H. jianshanensis) from the Chengjiang Lagerstätte (Yunnan, China) with exceptional preservation of a number of features. These include external gills, which suggest that the origin of the pharyngeal clefts was independent of the gills. The diagnostic branchial arches of chordates may, therefore, be composite structures. No evidence was found for the chordate-like structures that have been described in other yunnanozoans. We propose that yunnanozoans are stem-group deuterostomes, allied to the vetulicolians.

NMR studies of defensin antimicrobial peptides. 2. Three-dimensional structures of rabbit NP-2 and human HNP-1

The solution structure of two homologous naturally occurring antimicrobial peptides, rabbit defensin NP-2 and human defensin HNP-1, have been determined by two-dimensional nuclear magnetic resonance spectroscopy, distance geometry, and restrained molecular dynamics calculations. The structure of these defensins consists of an antiparallel beta-sheet in a hairpin conformation, a short region of triple-stranded beta-sheet, several tight turns, and a loop region that has a well-defined local structure but with a global orientation that is not well-defined with respect to the rest of the molecule. The solution structures of these two peptides are compared with the solution and crystal structures of two other homologous defensins. The structures for the defensins are also compared with known structures of other naturally occurring antimicrobial peptides.

Vitamin D prevents podocyte injury via regulation of macrophage M1/M2 phenotype in diabetic nephropathy rats

Increasing evidence suggests the heterogeneity of macrophage phenotype and function ultimately determines the outcome of diabetic nephropathy (DN). This study aimed to investigate the effects of vitamin D on macrophage M1/M2 phenotype and its role in preventing podocyte impairment in streptozotocin-induced DN rats. Calcitriol, a bioactive 1,25-dihydroxyvitamin D3, ameliorated proteinuria and renal damage as well as reversed the decline of both nephrin and podocin, crucial structural proteins in podocytes. DN rats showed increased infiltrating macrophages with M1 phenotype characterized by elevated expression of inducible nitric oxide synthase and TNF-α in glomeruli and interstitium, which were inhibited after calcitriol treatment. Interestingly, calcitriol promoted M2 macrophage activation with enhanced expression of CD163, arginase-1, and mannose receptor at week 18 but not at week 8 or 14. The ratio of CD163 to CD68, considered as the proportion of M2 macrophages, was about 2.9-fold higher at week 18 after calcitriol treatment. Furthermore, the protein expression of inducible nitric oxide synthase, a crucial marker of M1 macrophages, was negatively correlated with the expression of either nephrin or podocin, whereas CD163, indicating M2 macrophages, was positively correlated. In vitro, 1,25-dihydroxyvitamin D3 switched high-glucose-induced M1 macrophages toward an M2 phenotype in either U937-derived macrophages or RAW264.7 cells. Our results suggest that vitamin D not only reduces macrophage infiltration and inhibits M1 macrophage activation but also enhances M2 macrophage phenotype to protect against podocyte injury.

Repairing of goat tibial bone defects with BMP-2 gene-modified tissue-engineered bone

Bone defects larger than a critical size are major challenges in orthopedic medicine. We combined tissue-engineered bone and gene therapy to provide osteoprogenitor cells, osteoinductive factors, and osteo-conductive carrier for ideal bone regeneration in critical-sized bone defects. Goat diaphyseal bone defects were repaired with tissue and genetically engineered bone implants, composed of biphasic calcined bone (BCB) and autologous bone marrow derived mesenchymal stem cells (BMSC) transduced with human bone morphogenetic protein-2 (hBMP-2). Twenty six goats with tibial bone defects were divided into groups receiving implants by using a combination of BCB and BMSCs with or without the hBMP-2 gene. In eight goats that were treated with BCB that contained hBMP-2 transduced BMSC, five had complete healing and three showed partial healing. Goats in other experimental groups had only slight or no healing. Furthermore, the area and biochemical strength of the callus in the bone defects were significantly better in animals treated with genetically engineered implants. We concluded that the combination of genetic and tissue engineering provides an innovative way for treating critical-sized bone defects.

Propofol prevents cerebral ischemia-triggered autophagy activation and cell death in the rat hippocampus through the NF-κB/p53 signaling pathway

Propofol (2,6-diisopropylphenol) has been shown to attenuate neuronal injury under a number of experimental conditions; however, the mechanisms involved in its neuroprotective effects remain unclear. We therefore investigated whether inhibition of p53 induction by propofol contributes to the neuroprotection of cerebral ischemic cell death through both autophagic and apoptotic mechanisms. A transient global cerebral ischemia-reperfusion (I/R) model was produced with a 10-min, 2-vessel occlusion. The change in target genes including damage-regulated autophagy modulator (DRAM), microtubule-associated protein 1 light chain 3 (LC3), Beclin 1, cathepsin D, cathepsin B, p53-upregulated modulator of apoptosis (PUMA), Bax and Bcl-2 upon p53 inhibition was assessed with the co-administration of the intravenous anesthetic propofol and 3-methyladenine (3-MA), Pifithrin-alpha (PFT-α) or SN50. The I/R-induced increases of protein levels of p53 and LC3-II were significantly inhibited by treatment with propofol, 3-MA or PFT-α. The I/R-induced increases of protein levels of DRAM, Beclin 1, active cathepsin D and cathepsin B were significantly inhibited by treatment with propofol, PFT-α or SN50. The negative effects of the I/R-induced up-regulation of PUMA and Bax and the down-regulation of Bcl-2 in the rat hippocampus were all blocked by treatment with propofol, PFT-α or SN50. Our results suggest that cerebral I/R can induce nuclear factor-kappa B-dependent expression of p53. The autophagic and apoptotic mechanisms participate in programed cell death by regulating the p53-mediated pathway. Our results are the first to show that propofol, at clinically relevant concentrations, attenuated cell death through both autophagic and apoptotic mechanisms in the rat hippocampus after a cerebral I/R insult.

Influence of hemodynamic factors on rupture of intracranial aneurysms: patient-specific 3D mirror aneurysms model computational fluid dynamics simulation

BACKGROUND AND PURPOSE

Hemodynamics factors play an important role in the rupture of cerebral aneurysms. The purpose of this study was to evaluate the impact of hemodynamic factors on the rupture of the MANs with 3D reconstruction model CFD simulation.

MATERIALS AND METHODS

RDSA was performed in 9 pairs of intracranial MANs. Each pair was divided into ruptured and unruptured groups. The hemodynamic factors of the aneurysms and their parent arteries were compared.

RESULTS

There was a significant difference in the WSS at peak systole between the regions of the aneurysms and their parent arteries in the ruptured group (ie, 6.49 ± 3.48 Pa versus 8.78 ± 3.57 Pa, P =.015) but not in the unruptured group (ie, 9.80 ± 4.12 Pa versus 10.17 ± 7.48 Pa, P =.678). The proportion of the low WSS area to the whole area of the aneurysms was 12.20 ± 18.08% in the ruptured group and 3.96 ± 6.91% in the unruptured group; the difference between the 2 groups was statistically significant (P =.015). The OSI was 0.0879 ± 0.0764 in the ruptured group, which was significantly higher than that of the unruptured group (ie, 0.0183 ± 0.0191, P =.008).

CONCLUSIONS

MANs may be a useful disease model to investigate possible causes linked to ruptured aneurysms. The ruptured aneurysms manifested lower WSS compared with their parent arteries, a higher proportion of the low WSS area to the whole area of aneurysm, and higher OSI compared with the unruptured aneurysms.