βKlotho Is Required for Fibroblast Growth Factor 21 Effects on Growth and Metabolism

Fibroblast growth factor 21 (FGF21) is a fasting-induced hepatokine that has potent pharmacologic effects in mice, which include improving insulin sensitivity and blunting growth. The single-transmembrane protein βKlotho functions as a coreceptor for FGF21 in?vitro. To determine if βKlotho is required for FGF21 action in?vivo, we generated whole-body and adipose tissue-selective βKlotho-knockout mice. All of the effects of FGF21 on growth and metabolism were lost in whole-body βKlotho-knockout mice. Selective elimination of βKlotho in adipose tissue blocked the acute insulin-sensitizing effects of FGF21. Taken together, these data demonstrate that βKlotho is essential for FGF21 activity and that βKlotho in adipose tissue contributes to the beneficial metabolic actions of FGF21.     

Insulin-Like Growth Factor I (IGF-1) Ec/Mechano Growth Factor – A Splice Variant of IGF-1 within the Growth Plate

Human insulin-like growth factor 1 Ec (IGF-1Ec), also called mechano growth factor (MGF), is a splice variant of insulin-like growth factor 1 (IGF-1), which has been shown in vitro as well as in vivo to induce growth and hypertrophy in mechanically stimulated or damaged muscle. Growth, hypertrophy and responses to mechanical stimulation are important reactions of cartilaginous tissues, especially those in growth plates. Therefore, we wanted to ascertain if MGF is expressed in growth plate cartilage and if it influences proliferation of chondrocytes, as it does in musculoskeletal tissues. MGF expression was analyzed in growth plate and control tissue samples from piglets aged 3 to 6 weeks. Furthermore, growth plate chondrocyte cell culture was used to evaluate the effects of the MGF peptide on proliferation. We showed that MGF is expressed in considerable amounts in the tissues evaluated. We found the MGF peptide to be primarily located in the cytoplasm, and in some instances, it was also found in the nucleus of the cells. Addition of MGF peptides was not associated with growth plate chondrocyte proliferation.     

What Image Properties Regulate Eye Growth?

The growth of the eye, unlike other parts of the body, is not ballistic. It is guided by visual feedback with the eventual aim being optimal focus of the retinal image or emmetropization . It has been shown in animal models that interference with the quality of the retinal image leads to a disruption to the normal growth pattern, resulting in the development of refractive errors and defocused retinal images . While it is clear that retinal images rich in pattern information are needed to control eye growth, it is unclear what particular aspect of image structure is relevant. Retinal images comprise a range of spatial frequencies at different absolute and relative contrasts and in different degrees of spatial alignment. Here we show, by using synthetic images, that it is not the local edge structure produced by relative spatial frequency alignments within an image but rather the spatial frequency composition per se that is used to regulate the growth of the eye. Furthermore, it is the absolute energy at high spatial frequencies regardless of the spectral slope that is most effective. Neither result would be expected from currently accepted ideas of how human observers judge the degree of image "blur" in a scene where both phase alignments and the relative energy distribution across spatial frequency (i.e., spectral slope) are important.     

Roles of Pectin Methylesterases in Pollen-Tube Growth

Elongation of the pollen tube in pistil is essential for delivering sperms into the female gametophyte in sexual plant reproduction. Recently, a group of cell wall enzymes, pectin methylesterases （PMEs）, have been identified as playing an important role in this process. This article reviews the new understanding of the roles of PMEs in regulating pollen tube growth.     

Growth in Crustacea – twenty years on

Developments during the past 20 years are reviewed for four aspects of crustacean growth. These are the hormonal control of moulting, the effects of external factors on growth rate, the patterns of growth and the determination of age. Hormonal control. The nature and structure of Moult Inhibiting Hormone has been determined, though the mechanism by which it inhibits crustecdysone production is still unclear. A role in moult control by Crustacean Hyperglycaemic Hormone has been demonstrated, but needs clarification. Methyl farnesoate, a juvenile hormone like substance, occurs in Crustacea: however, a clear function as a juvenile hormone has yet to be shown. External factors. The effect of increased temperature in reducing moult increments is supported by further data. Reduced food supply causes smaller moult increments and longer intermoult periods: the latter effect is generally proportionately greater. A role for CHH in this process is hypothesised. Patterns of growth. Little advance has occurred in understanding the rationale for the diversity of growth patterns. Computer modelling offers promise, but is constrained by lack of data on natural mortality for validation. Determination of age. The basic methods available remain size frequency analysis and tagging programmes. There have been advances in technology and methods of analysis, but no major breakthrough. Novel methods include radionuclide ratios (expensive, complex and give only duration of current intermoult), lipofuschin pigment assay (promising, but needs further validation), and annular structures in the infra-cerebral organ (still very speculative).     

Nicotine Acts on Growth Plate Chondrocytes to Delay Skeletal Growth through the α7 Neuronal Nicotinic Acetylcholine Receptor

Background

Cigarette smoking adversely affects endochondral ossification during the course of skeletal growth. Among a plethora of cigarette chemicals, nicotine is one of the primary candidate compounds responsible for the cause of smoking-induced delayed skeletal growth. However, the possible mechanism of delayed skeletal growth caused by nicotine remains unclarified. In the last decade, localization of neuronal nicotinic acetylcholine receptor (nAChR), a specific receptor of nicotine, has been widely detected in non-excitable cells. Therefore, we hypothesized that nicotine affect growth plate chondrocytes directly and specifically through nAChR to delay skeletal growth.

Methodology/Principal Findings

We investigated the effect of nicotine on human growth plate chondrocytes, a major component of endochondral ossification. The chondrocytes were derived from extra human fingers. Nicotine inhibited matrix synthesis and hypertrophic differentiation in human growth plate chondrocytes in suspension culture in a concentration-dependent manner. Both human and murine growth plate chondrocytes expressed alpha7 nAChR, which constitutes functional homopentameric receptors. Methyllycaconitine (MLA), a specific antagonist of alpha7 nAChR, reversed the inhibition of matrix synthesis and functional calcium signal by nicotine in human growth plate chondrocytes in vitro. To study the effect of nicotine on growth plate in vivo, ovulation-controlled pregnant alpha7 nAChR +/− mice were given drinking water with or without nicotine during pregnancy, and skeletal growth of their fetuses was observed. Maternal nicotine exposure resulted in delayed skeletal growth of alpha7 nAChR +/+ fetuses but not in alpha7 nAChR −/− fetuses, implying that skeletal growth retardation by nicotine is specifically mediated via fetal alpha7 nAChR.

Conclusions/Significance

These results suggest that nicotine, from cigarette smoking, acts directly on growth plate chondrocytes to decrease matrix synthesis, suppress hypertrophic differentiation via alpha7 nAChR, leading to delayed skeletal growth.     

Patients with Encapsulating Peritoneal Sclerosis Have Increased Peritoneal Expression of Connective Tissue Growth Factor (CCN2), Transforming Growth Factor-β1, and Vascular Endothelial Growth Factor

Introduction

Encapsulating peritoneal sclerosis (EPS) is a devastating complication of peritoneal dialysis (PD). The pathogenesis is not exactly known and no preventive strategy or targeted medical therapy is available. CCN2 has both pro-fibrotic and pro-angiogenic actions and appears an attractive target. Therefore, we studied peritoneal expression of CCN2, as well as TGFβ1 and VEGF, in different stages of peritoneal fibrosis.

Materials and methods

Sixteen PD patients were investigated and compared to 12 hemodialysis patients and four pre-emptively transplanted patients. Furthermore, expression was investigated in 12 EPS patients in comparison with 13 PD and 12 non-PD patients without EPS. Peritoneal tissue was taken during kidney transplantation procedure or during EPS surgery. In a subset of patients, CCN2 protein levels in peritoneal effluent and plasma were determined. Samples were examined by qPCR, histology, immunohistochemistry, and ELISA.

Results

Peritoneal CCN2 expression was 5-fold higher in PD patients compared to pre-emptively transplanted patients (P<0.05), but did not differ from hemodialysis patients. Peritoneal expression of TGFβ1 and VEGF were not different between the three groups; neither was peritoneal thickness. Peritoneum of EPS patients exhibited increased expression of CCN2 (35-fold, P<0.001), TGFβ1 (24-fold, P<0.05), and VEGF (77-fold, P<0.001) compared to PD patients without EPS. In EPS patients, CCN2 protein was mainly localized in peritoneal endothelial cells and fibroblasts. CCN2 protein levels were significantly higher in peritoneal effluent of EPS patients compared to levels in dialysate of PD patients (12.0±4.5 vs. 0.91±0.92 ng/ml, P<0.01), while plasma CCN2 levels were not increased.

Conclusions

Peritoneal expression of CCN2, TGFβ1, and VEGF are significantly increased in EPS patients. In early stages of peritoneal fibrosis, only CCN2 expression is slightly increased. Peritoneal CCN2 overexpression in EPS patients is a locally driven response. The potential of CCN2 as biomarker and target for CCN2-inhibiting agents to prevent or treat EPS warrants further study.     

Economies of Growth or Ecologies of Survival?

ABSTRACT

The article presents the analytical framework, notably Bateson’s concepts of the double-bind and flexibility, in the context of a discussion of the Anthropocene, and outlines the subsequent articles and their internal relationships.     

Growth kinetics and competition — some contemporary comments

Results of competition experiments with one growth-limiting factor under idealized experimental conditions have been reported extensively, and usually provide ample support for the conclusion that complete competitors cannot coexist. However, under conditions of multiple substrate limitation and discontinuous or alternating supply of nutrients, coexistence of species is quite common. Since such patterns of nutrient supply may be expected to prevail in many natural environments the mechanisms ruling the survival and growth of bacteria under such conditions need to be understood. However, it appears that surprisingly little is known of the physiological state of individual competing species grown in mixed cultures. Unfortunately, basic information such as the actual concentration of limiting nutrients is lacking in most cases. But perhaps the recent development of new and powerful techniques to explore the physiological properties even of individual cells will further stimulate studies into the mechanisms behind the competitiveness of microbial species.     

Does Caspase Inhibition Promote Clonogenic Tumor Growth?

Defects in the control of cell death are a major cause of resistance to tumor therapy. Until recently, components of the intrinsic apoptotic pathway that act downstream of mitochondria, such as the caspases, have been apportioned only a minor share in this business. Thus, defects in mitochondrial caspase activation were suggested to cause apoptosis inhibition but not to confer clonogenic survival. This assumption was based on the finding that chemotherapeutic agents provoke mitochondrial damage even the absence of caspases, resulting in the release various toxic mediators and a subsequent caspase-independent cell death. In contrast to these earlier observations, we recently showed that in the absence of active caspases tumor cells do not necessarily undergo caspase-independent cell death but may even survive a chemotherapeutic insult. Our findings suggest that caspase inhibition can indeed promote clonogenic tumor growth which might be not only relevant for tumor therapy but should be also considered when evaluating the safety of therapeutic caspases inhibitors.     

Transforming Growth Factor-β and Ischemic Brain Injury

1. Necrosis and apoptosis are the two fundamental hallmarks of neuronal death in stroke. Nevertheless, thrombolysis, by using the recombinant serine protease t-PA, remains until now the only approved treatment of stroke in man.2. Over the last years, the cytokine termed Transforming Growth Factor-1 (TGF-1) has been found to be strongly up-regulated in the central nervous system following ischemia-induced brain damage.3. Recent studies have shown a neuroprotective activity of TGF-1 against ischemia-induced neuronal death. In vitro, TGF-1 protects neurons against excitotoxicity by inhibiting the t-PA-potentiated NMDA-induced neuronal death through a mechanism involving the up-regulation of the type-1 plasminogen activator inhibitor (PAI-1) in astrocytes.4. In addition, TGF-1 has been recently characterized as an antiapoptotic factor in a model of staurosporine-induced neuronal death through a mechanism involving activation of the extracellular signal-regulated kinase 1/2 (Erk1/2) and a concomitant increase phosphorylation of the antiapoptotic protein Bad.5. Altogether, these observations suggest that either TGF- signaling or TGF-1-modulated genes could be good targets for the development of new therapeutic strategies for stroke in man.     

Genetic Analysis of Connective Tissue Growth Factor as an Effector of Transforming Growth Factor β Signaling and Cardiac Remodeling

The matricellular secreted protein connective tissue growth factor (CTGF) is upregulated in response to cardiac injury or with transforming growth factor β (TGF-β) stimulation, where it has been suggested to function as a fibrotic effector. Here we generated transgenic mice with inducible heart-specific CTGF overexpression, mice with heart-specific expression of an activated TGF-β mutant protein, mice with heart-specific deletion of Ctgf, and mice in which Ctgf was also deleted from fibroblasts in the heart. Remarkably, neither gain nor loss of CTGF in the heart affected cardiac pathology and propensity toward early lethality due to TGF-β overactivation in the heart. Also, neither heart-specific Ctgf deletion nor CTGF overexpression altered cardiac remodeling and function with aging or after multiple acute stress stimuli. Cardiac fibrosis was also unchanged by modulation of CTGF levels in the heart with aging, pressure overload, agonist infusion, or TGF-β overexpression. However, CTGF mildly altered the overall cardiac response to TGF-β when pressure overload stimulation was applied. CTGF has been proposed to function as a critical TGF-β effector in underlying tissue remodeling and fibrosis throughout the body, although our results suggest that CTGF is of minimal importance and is an unlikely therapeutic vantage point for the heart.     

Identification and Growth Characteristics of α-Galactosidase-producing Microorganisms

Two kinds of α-galactosidase-producing microorganisms, strain No. 31–2 and strain No. 7–5, have been isolated from soil and subjected to a determinative study. On the basis of the morphological and physiological characters, the strain No. 31–2 was identified to be belonged to genus Micrococcus and the strain No. 7–5 to genus Bacillus. The former strain, Micrococcus sp. No. 31–2, produced exclusively an intracellular α-galactosidase, and the latter one, Bacillus sp. No. 7–5, secreted the enzyme into culture medium. The cell growth and enzyme production of both strains were observed to reach the maximum under an alkaline culture condition. The intracellular α-galactosidase of Micrococcus sp. No. 31–2 was inducible by galactose, melibiose, and raffinose, while the α-galactosidase of Bacillus sp. No. 7–5 was produced constitutively.     

N,N′-Dicyclohexylcarbodiimide Inhibition of Dunaliella Growth,and Restoration by Some Adenine Nucleotides and Plant Growth Regulators

N,N′-Dicyclohexylcarbodiimide (DCCD), an inhibitor of membrane-bound ATPase, strongly inhibited the growth, as measured by an increase in cell number, of Dunaliella tertiolecta. However, this inhibition was reversed by simultaneous application of adenosine 5′-triphosphate (ATP) or adenosine 2′-monophosphate (2′-AMP). Adenosine and adenosine 5′-diphosphate (ADP) were ineffective in restroration of the DCCD-inhibited growth. Gibberellin A₃ (GA₃) and 2,4- dichlorophenoxyacetic acid (2,4-D) also reversed the inhibition of DCCD on D. tertiolecta growth, although these plant growth regulators did not promote an increase in cell number.     

Involvement of β1-Integrin Up-regulation in Basic Fibroblast Growth Factor- and Epidermal Growth Factor-induced Proliferation of Mouse Neuroepithelial Cells

In neural stem cells, basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) promote cell proliferation and self-renewal. In the bFGF- and EGF-responsive neural stem cells, β1-integrin also plays important roles in crucial cellular processes, including proliferation, migration, and apoptosis. The cross-talk of the signaling pathways mediated by these growth factors and β1-integrin, however, has not been fully elucidated. Here we report a novel molecular mechanism through which bFGF or EGF promotes the proliferation of mouse neuroepithelial cells (NECs). In the NECs, total β1-integrin expression levels and proliferation were dose-dependently increased by bFGF but not by EGF. EGF rather than bFGF strongly induced the increase of β1-integrin localization on the NEC surface. bFGF- and EGF-induced β1-integrin up-regulation and proliferation were inhibited after treatment with a mitogen-activated protein kinase kinase inhibitor, U0126, which indicates the dependence on the mitogen-activated protein kinase pathway. Involvement of β1-integrin in bFGF- and EGF-induced proliferation was confirmed by the finding that NEC proliferation and adhesion to fibronectin-coated dishes were inhibited by knockdown of β1-integrin using small interfering RNA. On the other hand, apoptosis was induced in NECs treated with RGD peptide, a small β1-integrin inhibitor peptide with the Arg-Gly-Asp motif, but it was independent of β1-integrin expression levels. Those results suggest that regulation of β1-integrin expression/localization is involved in cellular processes, such as proliferation, induced by bFGF and EGF in NECs. The mechanism underlying the proliferation through β1-integrin would not be expected to be completely identical, however, for bFGF and EGF.     

Modified Clonidine Testing for Growth Hormone Stimulation Reveals α2-Adrenoreceptor Sub Sensitivity in Children with Idiopathic Growth Hormone Deficiency

Introduction

The association between short stature and increased risk of ischemic heart disease has been subject to studies for decades. The recent discussion of cardiovascular risk during growth hormone therapy has given new importance to this question. We have hypothesized that the autonomic system is a crucial element relating to this subject.

Methods

Heart rate variability calculated from 24-hour electrocardiogram data is providing insight into the regulatory state of the autonomous nervous system and is an approved surrogate parameter for estimating cardiovascular risk. We have calculated heart rate variability during clonidine testing for growth hormone stimulation of 56 children. As clonidine is a well-known effector of the autonomous system, stimulating vagal tone and decreasing sympathetic activity, we compared the autonomous reactions of children with constitutional growth delay (CGD), growth hormone deficiency (GHD) and former small for gestational age (SGA).

Results

During clonidine testing children with CGD showed the expected α₂-adrenoreceptor mediated autonomous response of vagal stimulation for several hours. This vagal reaction was significantly reduced in the SGA group and nearly non- existent in the GHD group.

Discussion

Children with GHD show a reduced autonomous response to clonidine indicating α₂-adrenoreceptor sub sensitivity. This can be found prior to the start of growth hormone treatment. Since reduction of HRV is an approved surrogate parameter, increased cardiovascular risk has to be assumed for patients with GHD. In the SGA group a similar but less severe reduction of the autonomous response to clonidine was found. These findings may enrich the interpretation of the data on growth hormone therapy, which are being collected by the SAGhE study group.     

Modeling the Epidermal Growth Factor—Epidermal Growth Factor Receptor L2 Domain Interaction: Implications for the Ligand Binding Process

Abstract

Signaling from the epidermal growth factor (EGF) receptor is triggered by the binding of lig-ands such as EGF or transforming growth factor alpha (TGF-α) and subsequent receptor dimerization. An understanding of these processes has been hindered by the lack of structural information about the ligand-bound, dimerized EGF receptor. Using an NMR-derived structure of EGF and a homology model of the major ligand binding domain of the EGF receptor and experimental data, we modeled the binding of EGF to this EGF receptor fragment. In this low resolution model of the complex, EGF sits across the second face of the EGF receptor L2 domain and EGF residues 10–16, 36–37, 40–47 bind to this face. The structural model is largely consistent with previously published NMR data describing the residues of TGF-α which interact strongly with the EGF receptor. Other EGF residues implicated in receptor binding are accounted by our proposal that the ligand binding is a two-step process with the EGF binding to at least one other site of the receptor. This three-dimensional model is expected to be useful in the design of ligand-based antagonists of the receptor.     

Bacterial Growth Rate and Marine Virus–Host Dynamics

Abstract The dynamics of a marine virus–host system were investigated at different steady state growth rates in chemostat cultures and the data were analyzed using a simple model. The virus–host interactions showed strong dependence on host cell growth rate. The duration of the infection cycle and the virus burst size were found to depend on bacterial growth rate, and the rate of cell lysis and virus production were positively correlated with steady state growth rate in the cultures (r ² > 0.96, p < 0.05). At bacterial growth rates of 0.02 to 0.10 h⁻¹ in the chemostats the virus burst size increased from 12 ± 4 to 56 ± 4, and the latent period decreased from 2.0 to 1.7 h. Resistant clones of the host strain were present in the cultures from the beginning of the experiment and replaced the sensitive host cells following viral lysis in the cultures. Regrowth of resistant cells correlated significantly (r ²= 1.000, p < 0.02) with the lysis rate of sensitive cells, indicating that release of viral lysates stimulated growth of the non-infected, resistant cells. The constructed model was suitable for simulating the observed dynamics of the sensitive host cells, viruses and resistant clones in the cultures. The model was therefore used in an attempt to predict the dynamics of this virus–host interaction in a natural marine environment during a certain set of growth conditions. The simulation indicated that a steady state relationship between the specific viruses and sensitive and resistant bacterial clones may occur at densities that are reasonable to assume for natural environments. The study demonstrates that basic characterization and modeling of specific virus–host interactions may improve our understanding of the behavior of bacteria and viruses in natural systems. Received: 12 November 1999; Accepted: 2 May 2000; Online Publication: 11 August 2000