Non-equilibrium x-ray spectroscopy using direct quantum dynamics.

Advances in experimental methodology aligned with technological developments, such as 3rd generation light sources, X-ray Free Electron Lasers, and High Harmonic Generation, have led to a paradigm shift in the capability of X-ray spectroscopy to deliver high temporal and spectral resolution on an extremely broad range of samples in a wide array of different environments. Importantly, the complex nature and high information content of this class of techniques mean that detailed theoretical studies are often essential to provide a firm link between the spectroscopic observables and the underlying molecular structure and dynamics. In this paper, we present approaches for simulating dynamical processes in X-ray spectroscopy based upon on-the-fly quantum dynamics with a Gaussian basis set. We show that it is possible to provide a fully quantum description of X-ray spectra without the need of precomputing highly multidimensional potential energy surfaces. It is applied to study two different dynamical situations, namely, the core-hole lifetime dynamics of the water monomer and the dissociation of C F 4 + recently studied using pump-probe X-ray spectroscopy. Our results compare favourably to previous experiments, while reducing the computational effort, providing the scope to apply them to larger systems.

TIMP3 is Regulated by Pericytes upon Shear Stress Detection Leading to a Modified Endothelial Cell Response.

OBJECTIVES: Atherosclerosis is a hallmark of cardiovascular disease. Shear stress on endothelial cells has been linked to atherogenesis and to fibrous cap thinning and rupture. Pericytes reside in the sub-endothelial space of vessels and have vasoprotective effects. They are subjected to shear stress when endothelial cell integrity is disrupted. The aim was to investigate the susceptibility and response of pericytes to shear stress. METHODS: Endothelial cells and pericytes were seeded in two dimensional monocultures and co-cultures, and in a novel three dimensional co-culture system and were subjected to no, low and high shear stress (0, 10, 30 dyne/cm2) for 48 h. The morphological response to flow was assessed by histology and the expression of extracellular matrix proteins was analysed using quantitative polymerase chain reaction, immunoblotting, and ELISA. RESULTS: While endothelial cells aligned into flow direction, pericytes aligned perpendicularly (p < .001), indicating that they must be capable of sensing flow. When pericytes were embedded into a 3D matrix they showed similar alignment and pericytes built long processes towards the lumen. Under shear stress endothelial cells upregulated "a disintegrin and metalloproteinase with thrombospondin motif 1" (ADAMTS-1) (p < .01) and pericytes upregulated "tissue inhibitor of matrix metalloproteinase" (TIMP) 3 (p < .05), an inhibitor of ADAMTS-1, meanwhile differential expression of extracellular matrix (ECM) proteins could be detected in co-cultures of both cells. For TIMP3 expression direct cell-cell contact between endothelial cells and pericytes was required. CONCLUSION: The experiments highlight that pericytes are able to sense direct flow thereby regulating ECM proteins known to be involved in vascular remodelling. Furthermore, pericytes counter-regulate endothelial ADAMTS-1 by protective TIMP3 expression to prevent matrix degradation and maintain vascular stability. For this protective effect direct cell contact was necessary. This observation might represent an adaptive, protective mechanism of pericytes to counteract endothelial damage in the onset of atherosclerosis.

The effect of placental restriction on insulin signaling and lipogenic pathways in omental adipose tissue in the postnatal lamb.

Intrauterine growth restriction (IUGR) followed by accelerated growth after birth is associated with an increased risk of abdominal (visceral) obesity and insulin resistance in adult life. The aim of the present study was to determine the impact of IUGR on mRNA expression and protein abundance of insulin signaling molecules in one of the major visceral fat depots, the omental adipose depot. IUGR was induced by placental restriction, and samples of omental adipose tissue were collected from IUGR (n = 9, 5 males, 4 females) and Control (n = 14, 8 males, 6 females) neonatal lambs at 21 days of age. The mRNA expression of the insulin signaling molecules, AMP-kinase (AMPK) and adipogenic/lipogenic genes was determined by qRT-PCR, and protein abundance by Western Blotting. AMPKα2 mRNA expression was increased in male IUGR lambs (0.015 ± 0.002 v. 0.0075 ± 0.0009, P < 0.001). The proportion of the AMPK pool that was phosphorylated (%P-AMPK) was lower in IUGR lambs compared with Controls independent of sex (39 ± 9% v. 100 ± 18%, P < 0.001). The mRNA expression and protein abundance of insulin signaling proteins and adipogenic/lipogenic genes was not different between groups. Thus, IUGR is associated with sex-specific alterations in the mRNA expression of AMPKα2 and a reduction in the percentage of the total AMPK pool that is phosphorylated in the omental adipose tissue of neonatal lambs, before the onset of visceral obesity. These molecular changes would be expected to promote lipid accumulation in the omental adipose depot and may therefore contribute to the onset of visceral adiposity in IUGR animals later in life.

Kidney pericytes: a novel therapeutic target in interstitial fibrosis.

Chronic Kidney Disease affects approximately 8% of the population and contributes considerably to premature morbidity and mortality. Recently reported studies have highlighted an important role for resident microvascular pericytes in the pathogenesis of kidney fibrosis. Pericytes are emerging as the predominant source of the activated, matrix depositing, stromal cell population seen in progressive fibrosis. Further, pericyte activation leads to their detachment from the vasculature, triggers unstable microvasculature and leads to rarefaction. Strategies to modulate pericyte function in these processes are therefore therapeutically attractive. In this review we will first describe our current understanding of the structure and function of the pericyte and the role these cells play in angiogenesis and the pathogenesis of renal fibrosis. Novel therapeutic approaches targeting pericytes in murine models of renal disease will then be considered.

The transition from fetal growth restriction to accelerated postnatal growth: a potential role for insulin signalling in skeletal muscle.

A world-wide series of epidemiological and experimental studies have demonstrated that there is an association between being small at birth, accelerated growth in early postnatal life and the emergence of insulin resistance in adult life. The aim of this study was to investigate why accelerated growth occurs in postnatal life after in utero growth restriction. Samples of quadriceps muscle were collected at approximately 140 days gestation (term approximately 150 days gestation) from normally grown fetal lambs (Control, n = 7) and from growth restricted fetal lambs (placentally restricted: PR, n = 8) and from Control (n = 14) and PR (n = 9) lambs at 21 days after birth. The abundance of the insulin and IGF1 receptor protein was higher in the quadriceps muscle of the PR fetus, but there was a lower abundance of the insulin signalling molecule PKC, and GLUT4 protein in the PR group. At 21 days of postnatal age, insulin receptor abundance remained higher in the muscle of the PR lamb, and there was also an up-regulation of the insulin signalling molecules, PI3Kinase p85, Akt1 and Akt2 and of the GLUT4 protein in the PR group. Fetal growth restriction therefore results in an increased abundance of the insulin receptor in skeletal muscle, which persists after birth when it is associated with an upregulation of insulin signalling molecules and the glucose transporter, GLUT4. These data provide evidence that the origins of the accelerated growth experienced by the small baby after birth lie in the adaptive response of the growth restricted fetus to its low placental substrate supply.

Maternal overnutrition suppresses the phosphorylation of 5'-AMP-activated protein kinase in liver, but not skeletal muscle, in the fetal and neonatal sheep.

Epidemiological studies have shown that infants exposed to an increased supply of nutrients before birth are at increased risk of type 2 diabetes in later life. We have investigated the hypothesis that fetal overnutrition results in reduced expression and phosphorylation of the cellular fuel sensor, AMP-activated kinase (AMPK) in liver and skeletal muscle before and after birth. From 115 days gestation, ewes were fed either at or approximately 55% above maintenance energy requirements. Postmortem was performed on lamb fetuses at 139-141 days gestation (n = 14) and lambs at 30 days of postnatal age (n = 21), and liver and quadriceps muscle were collected at each time point. The expression of AMPKalpha1 and AMPKalpha2 mRNA was determined by quantitative RT-PCR (qRT-PCR). The abundance of AMPKalpha and phospho-AMPKalpha (P-AMPKalpha) was determined by Western blot analysis, and the proportion of the total AMPKalpha pool that was phosphorylated in each sample (%P-AMPKalpha) was determined. The ratio of AMPKalpha2 to AMPKalpha1 mRNA expression was lower in fetuses compared with lambs in both liver and muscle, independent of maternal nutrition. Hepatic %P-AMPKalpha was lower in both fetuses and lambs in the Overfed group and %P-AMPKalpha in the lamb liver was inversely related to plasma glucose concentrations in the first 24 h after birth (r = 0.73, P < 0.025). There was no effect of maternal overnutrition on total AMPKalpha or P-AMPKalpha abundance in liver or skeletal muscle. We have, therefore, demonstrated that AMPKalpha responds to signals of increased nutrient availability in the fetal liver. Suppression of hepatic AMPK phosphorylation may contribute to increased glucose production, and basal hyperglycemia, present in lambs of overfed ewes in early postnatal life.

Birth weight and gender determine expression of adipogenic, lipogenic and adipokine genes in perirenal adipose tissue in the young adult sheep.

Epidemiological studies have demonstrated that low birth weight is associated with an increased incidence of visceral obesity and metabolic disorders in later life. In the present study, we have determined the impact of birth weight and gender on gene expression in visceral adipose tissue (VAT) in the young adult sheep. Lambs (n=19, birth weight range 2.6-7.55 kg) were born at term and growth monitored for 22.4+/-0.2 weeks, when body composition was determined by Dual X-ray Absorptiometry (DXA) and samples of VAT and subcutaneous (SCAT) adipose tissue collected. Plasma samples were collected at post-mortem for the determination of free fatty acids (FFA), glucose and insulin concentrations. Peroxisome-Proliferator Activated Receptor-gamma (PPARgamma), glycerol-3-phosphate dehydrogenase (G3PDH), lipoprotein lipase (LPL), adiponectin and leptin mRNA expression was determined by qRT-PCR. Fractional growth rate in postnatal weeks 1-3 was inversely related to birth weight in both males and females (R2=0.22, P<0.05, n=19). PPARgamma mRNA expression in VAT, but not SCAT, was inversely related to birth weight (R2=0.60, P<0.01, n=18). In males, but not females, PPARgamma mRNA in VAT was directly related to G3PDH mRNA expression (R2=0.69, P<0.01, n=9). Plasma FFA concentrations were inversely related to birth weight in both males and females (R2=0.22, P<0.05, n=19). These findings demonstrate that low birth weight is associated with an increased expression of a key adipogenic factor in visceral adipose tissue in young adulthood. In males, this is associated with an increased expression of lipogenic genes, and this may contribute to the increased propensity for visceral obesity in low birth weight males compared to females.

Increased maternal nutrition increases leptin expression in perirenal and subcutaneous adipose tissue in the postnatal lamb.

The present study tested the hypothesis that exposure to an increased level of maternal nutrition before birth results in altered expression of adipogenic, lipogenic, and adipokine genes in adipose tissue in early postnatal life. Pregnant ewes were fed either at or approximately 50% above maintenance energy requirements during late pregnancy, and quantitative RT-PCR was used to measure peroxisome proliferator-activated receptor (PPAR)-gamma, lipoprotein lipase (LPL), glycerol-3-phosphate-dehydrogenase (G3PDH), adiponectin, and leptin mRNA expression in perirenal (PAT) and sc adipose tissue (SCAT) in the offspring on postnatal d 30. Relative SCAT mass was higher in lambs of well-fed ewes (40.0 +/- 4.0 vs. 22.8 +/- 3.3 g/kg, P < 0.05) and was directly related to plasma insulin in the first 24 h after birth and to G3PDH and LPL expression. The expression of leptin mRNA in both the SCAT and PAT depots was higher (P < 0.05) in lambs of well-fed ewes. PPARgamma adiponectin, LPL, and G3PDH mRNA expression were not, however, different between well-fed and control groups in either depot. Relative PPARgamma expression in SCAT was directly related to plasma insulin concentrations in the first 24 h after birth (r(2) = 0.23; P < 0.05), and G3PDH and LPL expressions were also positively correlated with PPARgamma expression (r(2) = 0.27; P < 0.05). We have demonstrated that exposure to increased prenatal nutrition increases leptin expression at 1 month of age in both PAT and SCAT. The results of this study provide evidence that the nutritional environment before and immediately after birth can influence the development of adipose tissue in early postnatal life.

Increased maternal nutrition stimulates peroxisome proliferator activated receptor-gamma, adiponectin, and leptin messenger ribonucleic acid expression in adipose tissue before birth.

During fetal life, adipose tissue is predominantly comprised of brown or thermogenic adipocytes and there is a transition to white, lipid-storing adipocytes after birth concomitant with the onset of suckling. In pregnancies complicated by gestational diabetes, the fetus is hyperglycemic, has an increased fat mass, and is at increased risk of obesity in later life. In the present study, we have investigated the hypothesis that exposure to increased maternal nutrition during late gestation results in increased expression of genes that regulate adipogenesis and lipogenesis in perirenal fat in fetal sheep. Pregnant ewes were fed either at or approximately 55% above maintenance energy requirements during late pregnancy and quantitative RT-PCR was used to measure peroxisome proliferator-activated receptor gamma, lipoprotein lipase, glycerol-3-phosphate dehydrogenase, adiponectin, and leptin mRNA expression. We report that exposure to metabolic and hormonal signals of increased nutrition before birth results in an increase in the expression of the adipogenic factor, peroxisome proliferator-activated receptor gamma, and in lipoprotein lipase, adiponectin, and leptin mRNA expression in fetal perirenal fat. We propose that an increase in maternal, and hence fetal, nutrition results in a precocial increase in adipogenic, lipogenic, and adipokine gene expression in adipose tissue and that these changes may be important in the development of obesity in later life.

Renal stem cells in recovery from acute kidney injury.

The kidney has a dramatic capacity to regenerate after injury. Whether stem cells are the source of the epithelial progenitors replacing injured and dying tubular epithelium is currently an area of intense investigation. Studies from our laboratory and others have supported a model whereby many surviving renal epithelial cells after injury become dedifferentiated and take on mesenchymal characteristics. These cells proliferate to restore the integrity of the denuded basement membrane, and subsequently redifferentiate into a functional epithelium. An alternative possibility is that a minority of surviving intratubular cells possess stem cell properties and selectively proliferate after damage to neighboring cells. Some evidence exists to support this hypothesis but it has not yet been rigorously evaluated. A third hypothesis is that extratubular cells contribute to repair of damaged epithelium. Bone marrow-derived stem cells have been proposed to contribute to this process but our work and work of others indicates that the vast majority of tubular cells derive from an intrarenal source. Recent evidence suggests that interstitial cells may represent another extratubular stem cell niche. The fundamental unanswered questions in this field include whether renal stem cells exist in the adult, and if they do where are they located (interstitium, tubule, cortex, medulla) and what markers can be relied upon for the isolation and purification of these putative renal stem cells. In this review we focus on our current understanding of the potential role of renal and extrarenal stem cells in repair of the adult kidney and highlight some of the controversies in this field.

Increased maternal nutrition alters development of the appetite-regulating network in the brain.

Individuals exposed to an increased nutrient supply before birth have a high risk of becoming obese children and adults. It has been proposed that exposure of the fetus to high maternal nutrient intake results in permanent changes within the central appetite regulatory network. No studies, however, have investigated the impact of increased maternal nutrition on the appetite regulatory network in species in which this network develops before birth, as in the human. In the present study, pregnant ewes were fed a diet which provided 100% (control, n = 8) or approximately 160% (well-fed, n = 8) of metabolizable energy requirements. Ewes were allowed to lamb spontaneously, and lambs were sacrificed at 30 days of postnatal age. All fat depots were dissected and weighed, and expression of the appetite-regulating neuropeptides and the leptin receptor (OBRb) were determined by in situ hybridization. Lambs of well-fed ewes had higher glucose (Glc) concentrations during early postnatal life (F = 5.93, P<0.01) and a higher relative subcutaneous (s.c.) fat mass at 30 days of age (34.9+/-4.7 g/kg vs. 22.8+/-3.3 g/kg; P<0.05). The hypothalamic expression of pro-opiomelanocortin was higher in lambs of well-fed ewes (0.48+/-0.09 vs. 0.28+/-0.04, P<0.05). In lambs of overnourished mothers, but not in controls, the expression of OBRb was inversely related to total relative fat mass (r2 = 0.50, P = 0.05, n = 8), and the direct relationship between the expression of the central appetite inhibitor CART and fat mass was lost. The expression of neuropeptide Y and AGRP was inversely related to total relative fat mass (NPY, r2 = 0.28, P<0.05; agouti-related peptide, r2 = 0.39, P<0.01). These findings suggest that exposure to increased nutrition before birth alters the responses of the central appetite regulatory system to signals of increased adiposity after birth.

Regulation of leptin synthesis and secretion before birth: implications for the early programming of adult obesity.

A series of epidemiological, clinical and experimental studies have shown that there are associations between the fetal and neonatal nutritional environment and the amount and distribution of adipose tissue in adult life. This review considers the evidence for these relationships and discusses the potential impact of the prenatal nutritional experience on the development of the endocrine and neuroendocrine systems that regulate energy balance, with a particular emphasis on the role of the adipocyte-derived hormone, leptin. In the rodent, leptin derived from the mother may exert an important influence on the development of the appetite regulatory neural network and on the subsequent regulation of leptin synthesis and the risk for obesity in the offspring. In species such as the human and sheep, there is also recent evidence that the synthesis and secretion of adipocyte-derived hormones, such as leptin, are regulated in fetal life. Furthermore, the hypothalamic neuropeptides that regulate energy intake and expenditure in adult life are also present within the fetal brain and may be regulated by the prevailing level of maternal and hence fetal nutrient and hormonal signals, including leptin. This work is important in determining those initiating mechanisms within the 'fat-brain' axis in early life that precede the development of adult obesity.

Renal stem cells in recovery from acute kidney injury.

The kidney has a dramatic capacity to regenerate after injury. Whether stem cells are the source of the epithelial progenitors replacing injured and dying tubular epithelium is currently an area of intense investigation. Studies from our laboratory and others have supported a model whereby many surviving renal epithelial cells after injury become dedifferentiated and take on mesenchymal characteristics. These cells proliferate to restore the integrity of the denuded basement membrane, and subsequently redifferentiate into a functional epithelium. An alternative possibility is that a minority of surviving intratubular cells possess stem cell properties and selectively proliferate after damage to neighboring cells. Some evidence exists to support this hypothesis but it has not yet been rigorously evaluated. A third hypothesis is that extratubular cells contribute to repair of damaged epithelium. Bone marrow-derived stem cells have been proposed to contribute to this process but our work and work of others indicates that the vast majority of tubular cells derive from an intrarenal source. Recent evidence suggests that interstitial cells may represent another extratubular stem cell niche. The fundamental unanswered questions in this field include whether renal stem cells exist in the adult, and if they do where are they located (interstitium, tubule, cortex, medulla) and what markers can be relied upon for the isolation and purification of these putative renal stem cells. In this review we focus on our current understanding of the potential role of renal and extrarenal stem cells in repair of the adult kidney and highlight some of the controversies in this field.

In vitro models for oral malodor.

A model is a representation of some real phenomena and contains aspects or elements of the real system to be modeled. The model reflects (or duplicates) the type of behavior (or mechanisms) seen in the real system. The main characteristic of any model is the mapping of elements or parameters found in the system being studied (e.g. tongue dorsum biofilm in situ) on to the model being devised (e.g. laboratory perfusion biofilm). Such parameters include correct physico-chemical (abiotic) conditions as well as biotic conditions that occur in both model and reality. The main purpose of a model is to provide information that better explains the processes observed or thought to occur in the real system. Such models can be abstract (mental, conceptual, theoretical, mathematical or computational) or 'physical', e.g. in the form of a real disaggregated in vitro system or laboratory model. A wide range of different model systems have been used in oral biofilm research. These will be briefly reviewed with special emphasis on those models that have contributed most to knowledge in breath odor research. The different model systems used in breath odor research are compared. Finally, the requirements for developing an overall 'bad breath model' from considering the processes as a whole (real oral cavity, substrates in saliva, biotransformation by tongue microflora, odor gases in the breath) and extending this to the detection of malodor by the human nose will be outlined and discussed.

Use of n-butanol as an odorant to standardize the organoleptic scale of breath odour judges.

OBJECTIVE: The alcohol n-butanol has been recommended for use as a standard odorant by various groups for the training or standardization of breath odour judges and sensory evaluation panels. The objective of this study is to assess the use of n-butanol as a suitable odorant for organoleptic training of breath judges. METHODS: One judge with full smell acuity was trained in the method of organoleptic assessment using odorant solutions of main chemical classes (acids, amines, indole and sulphides) with the exception of alcohols. The subject was proficient in scoring odorant solutions, standard gas mixtures and human breath using the Rosenberg 0-5 organoleptic scale. A wide range of n-butanol solutions were prepared from 0 to 90 000 ppm and dispensed as replicate 12-ml volumes in Universal bottles (24 ml) leaving a headspace of 12 ml. Sets of odorants were prepared, labelled by code, randomized and presented to the judge in a completely blind fashion. The judge scored each concentration. This process was repeated on 32 occasions over a period of 12 weeks. Mean values of data for each determination for each concentration series were plotted against the log concentrations of odorant. Linear regression slope analysis was used to measure slope, the 95% CI of slope and the scatter of points (R2 value). Headspace concentrations of odorant were determined using gas chromatography (GC) analysis. RESULTS: The n-butanol regression slope gave a high R(2) value (0.971) and low scatter. However, the data did not correspond to other published work using an ASTM method where the range of recommended butanol concentrations was insufficient at both the high and low ends to determine the top and threshold. Moreover, headspace analysis using GC confirmed the published gas concentrations to be in error by a factor of 100. It was also observed that high concentrations of odorants were irritant causing desensitization if used for prolonged periods. CONCLUSION: The published method had erroneous headspace calculations listed and n-butanol could not be recommended as a training odorant because of its irritancy.

Prenatal programming of postnatal obesity: fetal nutrition and the regulation of leptin synthesis and secretion before birth.

Exposure to either an increased or decreased level of intrauterine nutrition can result in an increase in adiposity and in circulating leptin concentrations in later life. In animals such as the sheep and pig in which fat is deposited before birth, leptin is synthesised in fetal adipose tissue and is present in the fetal circulation throughout late gestation. In the sheep a moderate increase or decrease in the level of maternal nutrition does not alter fetal plasma leptin concentrations, but there is evidence that chronic fetal hyperglycaemia and hyperinsulinaemia increase fetal fat mass and leptin synthesis within fetal fat depots. Importantly, there is a positive relationship between the relative mass of the 'unilocular' component of fetal perirenal and interscapular adipose tissue and circulating fetal leptin concentrations in the sheep. Thus, as in the neonate and adult, circulating leptin concentrations may be a signal of fat mass in fetal life. There is also evidence that leptin can act to regulate the lipid storage, leptin synthetic capacity and potential thermogenic functions of fat before birth. Thus, leptin may act as a signal of energy supply and have a 'lipostatic' role before birth. Future studies are clearly required to determine whether the intrauterine and early postnatal nutrient environment programme the endocrine feedback loop between adipose tissue and the central and peripheral neuroendocrine systems that regulate energy balance, resulting in an enhanced risk of obesity in adult life.

Study on the organoleptic intensity scale for measuring oral malodor.

The 0-5 organoleptic scale is used widely in breath research and in trials to measure the efficacy of anti-odor agents. However, the precise relationship between odor scores and gas concentrations of target odorants is unknown. The purpose of this study was to relate mean organoleptic scores from odor judges (n = 7) for pure odorants (n = 8) representative of those found in oral malodor. Judges used a common 0-5 scale to report the odor intensity of sample sets in random order of concentration. Regression analysis of data showed that odor score was proportional to the log concentration of odorant, and comparison of slopes showed H(2)S to be the most significant in terms of odor power. Detection thresholds (mol.dm(-3)) were: Skatole (7.2 x 10(-13)) < methylmercaptan (1.0 x 10(-11)) < trimethylamine (1.8 x 10(-11)) < isovalerate (1.8 x 10(-11)) < butyrate (2.3 x 10(-10)) < hydrogen sulphide (6.4 x 10(-10)) < putrescine (9.1 x 10(-10)) < dimethyl disulphide (5.9 x 10(-8)). The study demonstrates the exponential nature of the olfactory response and shows that any single compound's contribution to malodor depends on odor power and threshold in addition to concentration.

Suppression by apoptotic cells defines tumor necrosis factor-mediated induction of glomerular mesangial cell apoptosis by activated macrophages.

Activated macrophages (M(phi)) isolated from inflamed glomeruli or generated by interferon-gamma and lipopolysaccharide treatment in vitro induce glomerular mesangial cell apoptosis by hitherto incompletely understood mechanisms. In this report we demonstrate that nitric oxide-independent killing of co-cultured mesangial cells by interferon-gamma/lipopolysaccharide-activated M(phi) is suppressed by binding/ingestion of apoptotic cells and is mediated by tumor necrosis factor (TNF). Thus, soluble TNF receptor-1 significantly inhibited induction of mesangial cell apoptosis by 1) rodent M(phi) in the presence of nitric oxide synthase inhibitors or 2) human M(phi), both situations in which nitric oxide release was minimal. Furthermore, murine TNF knockout M(phi) were completely unable to induce mesangial cell apoptosis in the presence of nitric oxide synthase inhibitors. We conclude that TNF-restricted M(phi)-directed apoptosis of glomerular mesangial cells can be down-regulated by M(phi) binding/ingestion of apoptotic cells, suggesting a new mechanism for negative feedback regulation of M(phi) controls on resident cell number at inflamed sites.

Synthesis of (7S,15S)- and (7R,15S)-dolatrienoic acid.

The stereospecific synthesis of (7S,15S)- and (7R,15S)-dolatrienoic acids (2) was achieved using an approach consisting of 16 linear steps. The C-11--C-16 unit was prepared in seven steps from ethyl (S)-lactate and coupled using a trans-selective Wittig--Schlosser reaction to the C-7--C-10 fragment. Chirality at the C-7 position was introduced using an Evan's-type chiral auxiliary in a cobalt-mediated Reformatsky reaction to give the (3S,11S)-aldehyde 24. Subsequent Wittig reaction with a phosphonium salt derived in three steps from tiglic acid gave (7S,15S)-dolatrienoic acid, one of the four possible diastereoisomers of the nonpeptide portion of the strong cancer cell growth inhibitory cyclodepsipeptide dolastatin 14 (1). A second diastereoisomer, (7R,15S)-dolatrienoic acid, was synthesized employing chiral oxazolidinone 21 by an analogous synthetic route.