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1.
Clin Oncol (R Coll Radiol) ; 32(4): 250-258, 2020 04.
Article in English | MEDLINE | ID: mdl-31607611

ABSTRACT

AIMS: Stereotactic ablative body radiotherapy doses for peripheral lung lesions caused high toxicity when used for central non-small cell lung cancer (NSCLC). To determine a safe stereotactic ablative body radiotherapy dose for central tumours, the phase I/II Radiation Therapy Oncology Group RTOG 0813 trial used 50 Gy/five fractions as a baseline. From 2013, 50 Gy/five fractions was adopted at the Beatson West of Scotland Cancer Centre for inoperable early stage central NSCLC. We report our prospectively collected toxicity and efficacy data. MATERIALS AND METHODS: Patient and treatment characteristics were obtained from electronic medical records. Tumours were classed as moderately central or ultra-central tumours using published definitions. Toxicity was assessed in a centralised follow-up clinic at 2 weeks, 6 weeks, 3 months, 6 months, 1 year and 2 years after treatment. RESULTS: Fifty patients (31 women, 19 men, median age 75.1 years) were identified with T1-2N0M0 moderately central NSCLC; one patient had both an ultra-central and a moderately central tumour. Eighty-four per cent were medically unfit for surgery. Forty per cent had biopsy-proven NSCLC and 60% were diagnosed radiologically using 18-fluorodeoxyglucose positron emission tomography/computed tomography imaging. Fifty-six per cent of patients were Eastern Cooperative Oncology Group (ECOG) performance status 2 or worse. All patients received 50 Gy/five fractions on alternate days on schedule. Two patients died within 90 days of treatment, one from a chest infection, the other cause of death was unknown. There was one episode of early grade 3 oesophagitis and one grade 3 late dyspnoea. There was no grade 4 toxicity. Over a median follow-up of 25.2 months (range 1-70 months), there were 34 deaths: 18 unrelated to cancer and 16 due to cancer recurrence. The median overall survival was 27.0 months (95% confidence interval 20.6-35.9) and cancer-specific survival was 39.8 months (95% confidence interval 28.6, not reached). CONCLUSION: This study has shown that 50 Gy/five fractions is a safe dose and fractionation for early stage inoperable moderately central NSCLC, with outcomes comparable with other series, even with patients with a poor performance status.


Subject(s)
Carcinoma, Non-Small-Cell Lung/radiotherapy , Lung Neoplasms/radiotherapy , Radiosurgery/methods , Aged , Aged, 80 and over , Carcinoma, Non-Small-Cell Lung/pathology , Dose Fractionation, Radiation , Female , Humans , Lung Neoplasms/pathology , Male , Middle Aged , Prospective Studies
2.
J Chem Phys ; 140(3): 034315, 2014 Jan 21.
Article in English | MEDLINE | ID: mdl-25669387

ABSTRACT

Velocity-mapped imaging and theoretical calculations have been used to study the angular distribution of the products of NO predissociation following its excitation to the 11s, 10p, 11p, and 9f Rydberg levels based on the NO(+) (X (2)Σ(+)) core. The Rydberg states were reached from the NO (A (2)Σ(+), v = 0, N = 2, J = 1.5) level prepared with strong alignment by excitation with linear polarization from NO (X (2)Π, v = 0, N = 1, J = 0.5). Ion dip spectra of the Rydberg states were recorded along with velocity-mapped images at the major peaks. The results are compared to calculations based on a previous theoretical approach modified to include transitions to states of Hund's case (d) coupling. The reasonable agreement shows the predictive value of the theory. The theory has also been used to reassess and explain previous results and to understand variations in the rate of photodissociation with components of the 10p and 11p Rydberg states.

3.
J Phys Chem A ; 117(46): 12011-9, 2013 Nov 21.
Article in English | MEDLINE | ID: mdl-23795961

ABSTRACT

Product imaging of O((3)P2) following dissociation of ozone has been used to determine the relative yields of the product channels O((3)P2) + O2(X (3)Σg(-)) of ozone. All three channels are prominent at all wavelengths investigated. O2 vibrational distributions for each channel and each wavelength are also estimated assuming Boltzmann rotational distributions. Averaged over wavelength in the measured range, the yields of the O((3)P2) + O2(X (3)Σg(-)), O((3)P2) + O2(a (1)Δg), and O((3)P2) + O2(b (1)Σg(+)) channels are 0.36, 0.31,and 0.34, respectively. Photofragment distributions in the spin-allowed channel O((3)P) + O2(X (3)Σg(-)) are compared with the results of quantum mechanical calculations on the vibronically coupled PESs of the singlet states B (optically bright) and R (repulsive). The experiments suggest that considerably more vibrational excitation and less rotational excitation occur than predicted by the quantum calculations. The rotational distributions, adjusted to fit the experimental images, suggest that the dissociation takes place from a more linear configuration than the Franck-Condon bending angle of 117°. The dissociation at most wavelengths results in a positive value of the anisotropy parameter, ß, both in the experiment and in the calculations. Calculations indicate that both nonadiabatic transitions and intersystem crossings substantially reduce ß below the nominal value of 2.

4.
Dalton Trans ; 41(14): 3985-94, 2012 Apr 14.
Article in English | MEDLINE | ID: mdl-22373939

ABSTRACT

The ligand 4,4'-dipiperidine-N,N'-bis(methylenephosphonic acid), H(4)L, has been reacted with divalent metal salts under solvothermal conditions to yield seven new metal phosphonate coordination polymers. The compounds have been characterized by elemental analyses and their structures determined by single-crystal X-ray diffraction. Zn(2)(L)(H(2)O)(2) and Co(2)(L)(H(2)O)(2) have (different) layered structures, while Mn(2)(L)(H(2)O)(3) has a chain motif. In these compounds, the N atoms of the ligand bind to the metal ions. α-Co(2)Cl(2)(H(2)L), formed from CoCl(2)·6H(2)O and H(4)L in ethanol, is also layered but the N atoms of the ligand are protonated. The Co atoms are tetrahedral, coordinated by three phosphonate oxygen atoms and a chloride ion. A polymorph of this compound, ß-Co(2)Cl(2)(H(2)L), was obtained from a mixed ionic liquid under microwave irradiation. The primary difference between the polymorphs is the orientation of the phosphonate group relative to the dipiperidine. When reacted hydrothermally with Sn(II)C(2)O(4), H(4)L partially decomposes, producing phosphate ions which are incorporated into the structure of Sn(6)O(2)(H(2)L)(PO(4))(2)·4H(2)O. In this compound, the N atoms of the ligand are protonated, and two oxide anions are incorporated for charge balance. A second phase is obtained from the same reaction, which was determined to be Sn(7)O(L)(3). This compound has a layered structure which contains relatively large voids within the inorganic portion of the layer. These structures are discussed, as well as factors influencing the state of protonation in the final compounds. The choice of solvent and temperature were found to have a significant influence on the type of structure obtained.

6.
J Phys Chem A ; 114(42): 11292-7, 2010 Oct 28.
Article in English | MEDLINE | ID: mdl-20735039

ABSTRACT

The O((1)D) + N(2)O → 2NO(X (2)Π) reaction has been studied in a molecular beam experiment in which O(3) and N(2)O were coexpanded. The precursor O((1)D) was prepared by O(3) photodissociation at 266 nm, and the NO(X (2)Π) molecules born from the reaction as the O((1)D) recoiled out of the beam were detected by 1+1 REMPI over the 220-246 nm probe laser wavelength range. The resulting spectrum was simulated to extract rotational and vibrational distributions of the NO(X (2)Π) molecules. The product rotational distribution is found to be characterized by a constant rotational temperature of ≈4500 K for all observed bands, v = 0-9. An inverted vibrational distribution is observed. A consistent explanation of this and previous experimental results is possible if there are two channels for the reaction, one producing a nearly statistical vibrational distribution for low O((1)D)-N(2)O relative velocity collisions and a second producing the inverted distribution observed here for high relative velocity collisions. The former might correspond to an insertion/complex-formation reaction, while the latter might correspond to a stripping reaction. Velocity relaxation of the O((1)D) is argued to compete strongly with reaction in most bulb studies, so that these studies see predominantly the nearly statistical distribution. In contrast, the beam experiments do not detect the part of the vibrational distribution produced in low relative velocity reactions because the O((1)D) is not relaxed from its initial velocity before it either reacts or leaves the beam.

7.
Bull Math Biol ; 72(3): 645-80, 2010 Apr.
Article in English | MEDLINE | ID: mdl-20107923

ABSTRACT

Planar cell polarity (PCP) occurs in the epithelia of many animals and can lead to the alignment of hairs, bristles, and feathers. Here, we present two approaches to modelling this phenomenon. The aim is to discover the basic mechanisms that drive PCP, while keeping the models mathematically tractable. We present a feedback and diffusion model, in which adjacent cell sides of neighbouring cells are coupled by a negative feedback loop and diffusion acts within the cell. This approach can give rise to polarity, but also to period two patterns. Polarisation arises via an instability provided a sufficiently strong feedback and sufficiently weak diffusion. Moreover, we discuss a conservative model in which proteins within a cell are redistributed depending on the amount of proteins in the neighbouring cells, coupled with intracellular diffusion. In this case, polarity can arise from weakly polarised initial conditions or via a wave provided the diffusion is weak enough. Both models can overcome small anomalies in the initial conditions. Furthermore, the range of the effects of groups of cells with different properties than the surrounding cells depends on the strength of the initial global cue and the intracellular diffusion.


Subject(s)
Cell Polarity/physiology , Drosophila Proteins/physiology , Drosophila melanogaster/physiology , Models, Biological , Wings, Animal/physiology , Animals , Body Patterning , Feedback
8.
J Chem Phys ; 128(15): 151101, 2008 Apr 21.
Article in English | MEDLINE | ID: mdl-18433182

ABSTRACT

The competition between rearrangement of the excited allyl radical via a 1,3 sigmatropic shift versus sequential 1,2 shifts has been observed and characterized using isotopic substitution, laser excitation, and molecular beam techniques. Both rearrangements produce a 1-propenyl radical that subsequently dissociates to methyl plus acetylene. The 1,3 shift and 1,2 shift mechanisms are equally probable for CH(2)CHCH(2), whereas the 1,3 shift is favored by a factor of 1.6 in CH(2)CDCH(2). The translational energy distributions for the methyl and acetylene products of these two mechanisms are substantially different. Both of these allyl dissociation channels are minor pathways compared to hydrogen atom loss.


Subject(s)
Allyl Compounds/chemistry , Carbon/chemistry , Free Radicals/chemistry , Hydrogen/chemistry , Models, Chemical , Models, Molecular , Computer Simulation , Molecular Conformation
9.
J Neuroendocrinol ; 20(3): 309-22, 2008 Mar.
Article in English | MEDLINE | ID: mdl-18208550

ABSTRACT

The elevation in baseline circulating growth hormone (GH) that occurs in pregnant rats is thought to arise from increased pituitary GH secretion, but the underlying mechanism remains unclear. Distribution, Fourier and algorithmic analyses confirmed that the pregnancy-induced increase in circulating GH in 3-week pregnant rats was due to a 13-fold increase in baseline circulating GH (P < 0.01), without any significant alteration in the parameters of episodic secretion. Electron microscopy revealed that pregnancy resulted in a reduction in the proportion of mammosomatotrophs (P < 0.01) and an increase in type II lactotrophs (P < 0.05), without any significant change in the somatotroph population. However, the density of the secretory granules in somatotrophs from 3-week pregnant rats was reduced (P < 0.05), and their distribution markedly polarised; the granules being grouped nearest the vasculature. Pituitary GH content was not increased, but steady-state GH mRNA levels declined progressively during pregnancy (P < 0.05). In situ hybridisation revealed that pregnancy was accompanied by a suppression of GH-releasing hormone mRNA expression in the arcuate nuclei (P < 0.05) and enhanced somatostatin mRNA expression in the periventricular nuclei (P < 0.05), an expression pattern normally associated with increased GH feedback. Although gastric ghrelin mRNA expression was elevated by 50% in 3-week pregnant rats (P < 0.01), circulating ghrelin, GH-secretagogue receptor mRNA expression and the GH response to a bolus i.v. injection of exogenous ghrelin were all largely unaffected during pregnancy. Although trace amounts of 'pituitary' GH could be detected in the placenta with radioimmunoassay, significant GH-immunoreactivity could not be observed by immunohistochemistry, indicating that rat placenta itself does not produce 'pituitary' GH. Although not excluding the possibility that the pregnancy-associated elevation in baseline circulating GH could arise from alternative extra-pituitary sources (e.g. the ovary), our data indicate that this phenomenon is most likely to result from a direct alteration of somatotroph function.


Subject(s)
Ghrelin/physiology , Growth Hormone/blood , Pregnancy, Animal , Adiposity/physiology , Animals , Antibodies, Monoclonal/metabolism , Body Weight/physiology , Female , Ghrelin/genetics , Ghrelin/metabolism , Ghrelin/pharmacology , Growth Hormone/genetics , Growth Hormone/metabolism , Growth and Development/physiology , Hypothalamic Hormones/metabolism , Male , Placenta/metabolism , Pregnancy , Rats , Rats, Sprague-Dawley , Receptors, Ghrelin/genetics , Receptors, Ghrelin/metabolism , Somatotrophs/physiology , Time Factors , Up-Regulation
10.
J Chem Phys ; 127(14): 144309, 2007 Oct 14.
Article in English | MEDLINE | ID: mdl-17935397

ABSTRACT

The formation of high-n Rydberg atoms from the neutral dissociation of superexcited states of I(2) formed by resonant two-photon excitation of molecular iodine using an ArF laser has been investigated. The high-n Rydberg atoms I* are formed by predissociation of the optically excited molecular Rydberg states I*(2)[R(B (2)Sigma(g) (+))] converging on the I(2) (+)(B (2)Sigma(g) (+)) state of the ion. Measurement of the kinetic energy release of the Rydberg I* fragments allowed the identification of the asymptotic channels as I*[R((3)P(J))]+I((2)P(32)), where the I*[R((3)P(J))] are Rydberg atoms converging on the I(+)((3)P(J)) states of the ion with J=2, 1, and 0. In the case of the I*[R((3)P(2))] fragments, the average Rydberg lifetime is observed to be 325+/-25 micros. Based on experiments on the variation of the Rydberg atom signal with the field ionizing strength, the distribution of Rydberg levels peaks at about 25-50 cm(-1) below the ionization limit.

11.
J Chem Phys ; 125(13): 133316, 2006 Oct 07.
Article in English | MEDLINE | ID: mdl-17029469

ABSTRACT

Quantum mechanical calculations of photofragment angular distributions have been performed as a function of the frequency of excitation, the lifetime of the dissociative state, the rotational level, and the rotational constant. In the limit of high J values and white, incoherent excitation, the general results are found to agree exactly with both those of Mukamel and Jortner [J. Chem. Phys. 61, 5348 (1974)] and those of Jonah [J. Chem. Phys. 55, 1915 (1971)]. Example calculations describe how the anisotropy is dependent on the degree of broadening, the rotational constant, the initial rotational level, and the frequency of excitation. Applications are also made to interpret experimental results on the photodissociation of ClO via the 11-0, 10-0, and 6-0 bands of the A 2Pi3/2 -X 2Pi3/2 transition and on the photodissociation of O2 via the 0-0 band of the E 3Sigmau- -X 3Sigmag- transition.

12.
Proc Natl Acad Sci U S A ; 103(44): 16079-82, 2006 Oct 31.
Article in English | MEDLINE | ID: mdl-17047035

ABSTRACT

Product state distributions of the CO produced in the 308-nm photolysis of acetaldehyde show clear evidence of two dissociation mechanisms. One is attributed to the conventional transition state mechanism predicted by theory, with high rotational and translational energy of the CO and a pronounced v(perpendicular)J vector correlation. However, as much as 15% of the reaction flux proceeds via another pathway that produces low CO rotational and translational energy, very high CH(4) internal energy, and no correlation between the CO velocity and angular momentum vectors. The attributes of this channel are dynamically similar to the recently reported "roaming atom" mechanism in formaldehyde. We therefore speculate that the second pathway in acetaldehyde also occurs via a roaming mechanism in the CH(3) + HCO exit channel that decays into the CH(4) + CO channel.


Subject(s)
Acetaldehyde/chemistry , Photochemistry , Carbon Monoxide/chemistry , Models, Chemical
13.
Int J Obes (Lond) ; 30(3): 430-8, 2006 Mar.
Article in English | MEDLINE | ID: mdl-16172617

ABSTRACT

OBJECTIVE: Abnormalities of the melanocortin system produce obesity and increased linear growth. While the obesity phenotype is well characterised, the mechanism responsible for increased linear growth is unclear. The somatotrophic axis was studied in the obese agouti (A(y)/a) mouse as a model of a perturbed melanocortin system. DESIGN: Adult obese A(y)/a mice were compared to age- and sex-matched wild-type (WT) controls. Weight and body length (nose-anus) were recorded. Plasma growth hormone (GH), insulin-like growth factor-I (IGFI), insulin and leptin were measured using radioimmunoassay. Since ghrelin is a potent GH secretagogue, plasma ghrelin, stomach ghrelin peptide and stomach ghrelin mRNA expression were studied. Hypothalamic periventricular (PeVN) somatostatin neurones and arcuate (Arc) neuropeptide Y (NPY) neurones inhibit the growth axis, whereas Arc growth hormone-releasing hormone (GHRH) neurones are stimulatory. Therefore, specific hypothalamic expression of somatostatin, NPY and GHRH was measured using quantitative in situ hybridisation. RESULTS: Obese A(y)/a mice were significantly heavier and longer than WT controls. Plasma IGFI concentrations were 30% greater in obese A(y)/a mice. Obese A(y) /a mice were hyperinsulinaemic and hyperleptinaemic, yet plasma ghrelin, and stomach ghrelin peptide and mRNA were significantly reduced. In obese A(y)/a mice, PeVN somatostatin and Arc NPY mRNA expression were reduced by 50% compared to WT controls, whereas Arc GHRH mRNA expression was unchanged. CONCLUSION: Increased body length in adult obese A(y)/a mice may result from reduced Arc NPY and PeVN somatostatin mRNA expression, which in turn, may increase plasma IGFI concentrations and upregulate the somatotrophic axis.


Subject(s)
Growth Disorders/physiopathology , Melanocyte-Stimulating Hormones/physiology , Obesity/physiopathology , Agouti Signaling Protein , Animals , Biometry , Body Weight , Gastric Mucosa/metabolism , Gene Expression , Ghrelin , Growth Disorders/metabolism , Growth Hormone/blood , Hypothalamus/metabolism , Insulin/blood , Insulin-Like Growth Factor I/metabolism , Intercellular Signaling Peptides and Proteins/genetics , Leptin/blood , Male , Mice , Mice, Inbred C57BL , Mice, Obese , Obesity/metabolism , Peptide Hormones/metabolism , Pituitary Gland, Anterior/metabolism , Pituitary Gland, Anterior/physiopathology , RNA, Messenger/genetics , Signal Transduction , Somatostatin/biosynthesis , Somatostatin/genetics
14.
J Chem Phys ; 122(17): 174304, 2005 May 01.
Article in English | MEDLINE | ID: mdl-15910029

ABSTRACT

The photodissociation of N(2)O at wavelengths near 130 nm has been investigated by velocity-mapped product imaging. In all, five dissociation channels have been detected, leading to the following products: O((1)S)+N(2)(X (1)Sigma), N((2)D)+NO(X (2)Pi), N((2)P)+NO(X (2)Pi), O((3)P) + N(2)(A (3)Sigma(+) (u)), and O((3)P) + N(2)(B (3)Pi(g)). The most significant channel is to the products O((1)S) + N(2)(X(1)Sigma), with strong vibrational excitation in the N(2). The O((3)P) + N(2)(A,B):N((2)D,(2)P) + NO branching ratio is measured to be 1.4 +/- 0.5, while the N(2)(A) + O((3)P(J)):N(2)(B) + O((3)P(J)) branching ratio is determined to be 0.84+/-0.09. The spin-orbit distributions for the O((3)P(J)), N((2)P(J)), and N((2)D(J)) products were also determined. The angular distributions of the products are in qualitative agreement with excitation to the N(2)O(D (1)Sigma(+)) state, with participation as well by the (3)Pi(v) state.


Subject(s)
Models, Chemical , Models, Molecular , Nitric Oxide/chemistry , Nitrogen/chemistry , Oxygen/chemistry , Photochemistry/methods , Computer Simulation , Dose-Response Relationship, Radiation , Kinetics , Light , Nitric Oxide/radiation effects , Nitrogen/radiation effects , Oxygen/radiation effects , Radiation Dosage
15.
J Chem Phys ; 121(21): 10437-46, 2004 Dec 01.
Article in English | MEDLINE | ID: mdl-15549924

ABSTRACT

The photodissociation of O(2) in the region from 120-133 nm has been investigated using product imaging. The spectrum in this region is dominated by transitions from the ground state to the first three vibrational levels of the E (3)Sigma(u) (-) state. The O((1)D)+O((3)P) channel is the only product channel observed by product imaging for dissociation at either 124.4 nm or 120.4 nm. The O((1)D(2)) product is aligned in the molecular frame in such a way that its J vector is perpendicular to the relative velocity vector between the O((1)D) and the O((3)P). The variation in the anisotropy of dissociation is approximately predicted by considering transitions on individual lines and then taking into account the coherent excitation of overlapping resonances. At 132.7 nm, both the O((1)D)+O((3)P) and the O((3)P)+O((3)P) channels are observed with branching ratios of 0.40+/-0.08 and 0.60+/-0.09, respectively. At 130.2 nm, the quantum yield for production of O((1)D) is 0.76+/-0.28.


Subject(s)
Models, Chemical , Models, Molecular , Oxygen/chemistry , Oxygen/radiation effects , Photochemistry/methods , Computer Simulation , Dose-Response Relationship, Radiation , Light , Quantum Theory , Radiation Dosage
16.
Aust Dent J ; 48(4): 267, 2003 Dec.
Article in English | MEDLINE | ID: mdl-14738131
17.
News Physiol Sci ; 16: 208-13, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11572922

ABSTRACT

Destruction of bone tissue due to disease and inefficient bone healing after traumatic injury may be addressed by tissue engineering techniques. Growth factor, cytokine protein, and gene therapies will be developed, which, in conjunction with suitable carriers, will regenerate missing bone or help in cases of defective healing.


Subject(s)
Bone Regeneration/physiology , Fractures, Bone/physiopathology , Fractures, Bone/therapy , Tissue Engineering/methods , Animals , Genetic Therapy , Humans
18.
Anesthesiology ; 95(2): 343-8, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11506104

ABSTRACT

BACKGROUND: With increasing pressure to use operating room time efficiently, opportunities for residents to learn fiberoptic orotracheal intubation in the operating room have declined. The purpose of this study was to determine whether fiberoptic orotracheal intubation skills learned outside the operating room on a simple model could be transferred into the clinical setting. METHODS: First-year anesthesiology residents and first- and second-year internal medicine residents were recruited. Subjects were randomized to a didactic-teaching-only group (n = 12) or a model-training group (n = 12). The didactic-teaching group received a detailed lecture from an expert bronchoscopist. The model-training group was guided, by experts, through tasks performed on a simple model designed to refine fiberoptic manipulation skills. After the training session, subjects performed a fiberoptic orotracheal intubation on healthy, consenting, anesthetized, paralyzed female patients undergoing elective surgery with predicted "easy" laryngoscopic intubations. Two blinded anesthesiologists evaluated each subject. RESULTS: After the training session, the model group significantly outperformed the didactic group in the operating room when evaluated with a global rating scale (P < 0.01)and checklist (P0.05). Model-trained subjects completed the fiberoptic orotracheal intubation significantly faster than didactic-trained subjects (P < 0.01). Model-trained subjects were also more successful at achieving tracheal intubation than the didactic group (P < 0.005). CONCLUSION: Fiberoptic orotracheal intubation skills training on a simple model is more effective than conventional didactic instruction for transfer to the clinical setting. Incorporating an extraoperative model into the training of fiberoptic orotracheal intubation may greatly reduce the time and pressures that accompany teaching this skill in the operating room.


Subject(s)
Anesthesia, Inhalation , Intubation, Intratracheal/methods , Adult , Audiovisual Aids , Clinical Competence , Female , Fiber Optic Technology , Humans , Models, Anatomic , Teaching
19.
J Neuroendocrinol ; 13(6): 496-504, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11412336

ABSTRACT

The transgenic growth retarded (Tgr) rat is the first genetic model of growth hormone (GH) deficiency whose growth can be accelerated with exogenous GH secretagogues (GHSs). In this study, we have demonstrated that GHS-receptor (GHS-R) mRNA expression in the arcuate nucleus of Tgr rats was not significantly different to that in wild-type littermates. We have confirmed that GHS-induced elevation in body weight gain was accompanied by acceleration of skeletal growth, and that the effects of the GHS, GHRP-6, were both dose- and pattern-dependent. The growth response with continuous infusion of GHRP-6 was transient, accompanied by suppression of GH and corticosterone responses to bolus injection of GHRP-6. This desensitization occurred without downregulation of arcuate GHS-R mRNA expression, but was accompanied by elevated periventricular somatostatin mRNA expression. In contrast, pulsatile (3-hourly) infusion of GHRP-6 produced sustained growth and GH responses, which were accompanied by suppression of corticosterone responses and elevated arcuate GH-releasing factor (GRF) mRNA expression. Skeletal growth was further accelerated by coinfusion of GRF, but significant depletion of pituitary GH stores suggested that this growth rate may not be sustainable. These experiments confirm the importance of the Tgr rat for investigating the growth promoting potential of the GHSs in the context of GH-deficient dwarfism, and suggest that elevated somatostatin expression may mediate the suppression of the GRF-GH and hypothalamo-pituitary-adrenal axes following continuous GHRP-6 treatment.


Subject(s)
Bone Development/drug effects , Growth Hormone-Releasing Hormone/pharmacology , Growth Hormone/deficiency , Oligopeptides/pharmacology , Peptide Hormones , Receptors, G-Protein-Coupled , Animals , Animals, Genetically Modified , Arcuate Nucleus of Hypothalamus/chemistry , Corticosterone/metabolism , Female , Ghrelin , Growth Hormone/genetics , Growth Hormone/metabolism , Growth Hormone-Releasing Hormone/genetics , Hormones/pharmacology , Kinetics , Male , Neuropeptide Y/genetics , Peptides/pharmacology , Pituitary Gland/chemistry , Pituitary Gland/metabolism , RNA, Messenger/analysis , Rats , Receptors, Cell Surface/genetics , Receptors, Ghrelin , Somatostatin/genetics
20.
Biochem Biophys Res Commun ; 283(2): 480-6, 2001 May 04.
Article in English | MEDLINE | ID: mdl-11327726

ABSTRACT

Effective tissue repair results from a rapid, temporally orchestrated series of events. At the site of local tissue injury, the production of many growth factors and cytokines is, in part, stimulated by the early growth response transcription factors such as Egr-1. Egr-1 protein binds to a family of corepressor proteins called NAB which function to block or limit Egr-1 trans-activation of cognate target genes. NAB2 blocks Egr-1 activation of the tissue factor (TF) promoter, Egr-1 stimulated production of PDGF-AB, HGF, TGFbeta(1), and VEGF and the endogenous expression of PDGF-AB and TGFbeta(1). Expression of a wild-type NAB2 but not a dominant negative NAB2 mutant abrogates Egr-1 driven TF promoter activity and tubule formation in an in vitro model of angiogenesis. These findings may have importance in any tissue that is subject to scarring after acute or chronic injury.


Subject(s)
DNA-Binding Proteins/metabolism , Growth Substances/biosynthesis , Immediate-Early Proteins , Neoplasm Proteins , Neovascularization, Physiologic/drug effects , Repressor Proteins/pharmacology , Transcription Factors/metabolism , Cells, Cultured , Early Growth Response Protein 1 , Gene Expression/drug effects , Humans , Muscle, Smooth, Vascular/drug effects , Muscle, Smooth, Vascular/metabolism , Promoter Regions, Genetic , Repressor Proteins/genetics , Repressor Proteins/metabolism , Thromboplastin/genetics , Wound Healing/drug effects
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