Wound healing and revascularization: a histologic observation of experimental tooth root fracture

We used dogs as an animal model to generate tooth root fracture and to observe the wound-healing process of the fracture. Histologic examination of the specimens revealed that the early reaction of the wound healing was infiltration of inflammatory cells particularly at the coronal part of the fracture, whereas less inflammation but more abundant collagen fibers were seen at the apical part of the fracture (15 and 30 days). Inflammation lasted for more than 90 days and then subsided. At day 180, bone tissue healing was observed. Revascularization of the pulp tissues reached a high level at the same stage that bone healing took place. Our data suggest that in tooth root fracture, the regeneration of blood vessels is important in the wound-healing process and the revascularization is synchronized with the fracture wound healing. In this animal model the complete hard tissue healing could take as long as 6 months.

Beneficial effects of growth hormone and insulin-like growth factor-1 in experimental heart failure in rats treated with chronic ACE inhibition

The effects of growth hormone (GH) plus insulin-like growth factor-1 (IGF-1) were tested in an experimental model of cardiac failure treated with chronic angiotensin-converting enzyme (ACE) inhibition. Myocardial infarction was induced in rats by left coronary artery ligation. Two weeks after ligation, the animals received either captopril (2 g/L in drinking water) or water for 3 months. The rats were then given either GH (2 mg/kg/day) plus IGF-1 (2 mg/kg/day) or vehicle for 14 days. Captopril treatment decreased mean arterial pressure (MAP), left ventricular end-diastolic pressure (LVEDP) and systemic vascular resistance (SVR) (p < 0.05), and increased cardiac index (CI) and stroke volume index (SVI) (p < 0.05). GH/IGF-1 or captopril+GH/IGF-1 treatment decreased MAP, LVEDP, and SVR (p < 0.05), and increased left ventricular maximum dP/dt, CI, and SVI (p < 0.05). The increases in CI and SVI were significantly greater in the captopril+GH/IGF-1-treated animals than in those treated with captopril alone (p < 0.05). The beneficial effect of captopril in reducing cardiac hypertrophy was preserved in the captopril+GH/IGF-1 group. The results indicate that GH/IGF-1 and captopril can improve cardiac performance in congestive heart failure by independent and complementary mechanisms.

[Effects of demineral-resistant of Lanthanum,Cerium and Fluoride on human root surface:A comparative study in vitro]

An in vitro acid-resistant and remineralized study on human root surface with 500ppm lanthanum,Cerium and Fluoride accidulate buffer was carried out in a pH-cy-cling system.The results of quantitative chemical and energy spectrometry analyses showed that all these three elements had the demineral-resistant effects,although fluoride showed a better effect,Furthermore,the mechanisms of lanthanum,Cerium and Fluoride on demineral-resistant were discussed from the viewpoint of crystal physicochemistry.

Transcription of a recombinant bunyavirus RNA template by transiently expressed bunyavirus proteins

We describe a convenient system for analyzing bunyavirus transcription using a recombinant RNA template derived from the plasmid pBUNSCAT, which comprises a negative-sense reporter gene (chloramphenicol acetyltransferase or CAT) flanked by the exact 5' and 3' untranslated regions of the Bunyamwera virus (BUN) S RNA segment. When cells which expressed bunyavirus proteins (either by recombinant vaccinia viruses or by the vaccinia virus-T7 system) were transfected with BUNSCAT RNA, CAT activity could be measured, indicating transcription of the negative-sense reporter RNA into mRNA. The system permits investigation of both the protein and RNA sequence requirements for transcription. Extensions of 2 bases at the 5' end or 11 or 35 bases at the 3' end of BUNSCAT RNA allowed transcription but a lower level than the wild-type template. Deletion of the 5 nucleotides at the 3' end of BUNSCAT RNA reduced CAT activity by > 99%. Investigation of the viral protein requirements of the system showed that only the bunyavirus L and N proteins were needed for CAT activity. The BUN L protein was also able to transcribe the reporter RNA in concert with the N proteins of closely related bunyaviruses such as Batai, Cache Valley, Maguari, Main Drain, and Northway, but only inefficiently with those of Kairi, Guaroa, or Lumbo viruses. When BUN L proteins containing specific mutations were expressed CAT activity was only observed using those mutated L proteins previously reported to be active in a nucleocapsid transfection assay (H. Jin and R. M. Elliott, 1992, J. Gen. Virol. 73, 2235-2244). These results illustrate the utility of this system for a detailed genetic analysis of the factors involved in bunyavirus transcription.

Characterization of a novel protein regulated during the critical period for song learning in the zebra finch

A male zebra finch learns a song by listening to a tutor, but song learning is normally restricted to a critical period in juvenile development. Here we identify an RNA whose expression in the song control circuit is altered during this critical period. The RNA encodes a soluble presynaptic protein that forms a predicted amphipathic alpha helix typical of the lipid-binding domain in apolipoproteins. We show this protein, which we call synelfin, to be the homolog of the human non-A beta component (and its precursor) recently purified from Alzheimer's disease amyloid. We suggest this highly conserved protein may serve a novel function critical to the regulation of vertebrate neural plasticity.

Ryanodine receptor-ankyrin interaction regulates internal Ca2+ release in mouse T-lymphoma cells

In this study, we have identified and partially characterized a mouse T-lymphoma ryanodine receptor on a unique type of internal vesicle which bands at the relatively light density of 1.07 g/ml. Analysis of the binding of [3H]ryanodine to these internal vesicles reveals the presence of a single, low affinity binding site with a dissociation constant (Kd) of 200 nM. The second messenger, cyclic ADP-ribose, was found to increase the binding affinity of [3H]ryanodine to its vesicle receptor at least 5-fold (Kd approximately 40 nM). In addition, cADP-ribose appears to be a potent activator of internal Ca2+ release in T-lymphoma cells and is capable of overriding ryanodine-mediated inhibition of internal Ca2+ release. Immunoblot analyses using a monoclonal mouse antiryanodine receptor antibody indicate that mouse T-lymphoma cells contain a 500-kDa polypeptide similar to the ryanodine receptor found in skeletal muscle, cardiac muscle, and brain tissues. Double immunofluorescence staining and laser confocal microscopic analysis show that the ryanodine receptor is preferentially accumulated underneath surface receptor-capped structures. T-lymphoma ryanodine receptor was isolated (with an apparent sedimentation coefficient of 30 S) by extraction of the light density vesicles with 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (CHAPS) in 1 M NaCl followed by sucrose gradient centrifugation. Further analysis indicates that specific, high affinity binding occurs between ankyrin and this 30 S lymphoma ryanodine receptor (Kd = 0.075 nM). Most importantly, the binding of ankyrin to the light density vesicles significantly blocks ryanodine binding and ryanodine-mediated inhibition of internal Ca2+ release. These findings suggest that the cytoskeleton plays a pivotal role in the regulation of ryanodine receptor-mediated internal Ca2+ release during lymphocyte activation.

Growth hormone improves cardiac performance in experimental heart failure

BACKGROUND

Growth hormone has been shown to increase maximum isometric active force of the left ventricular papillary muscle of rats in vitro. Administration of growth hormone causes an increase in myocardial contractility in normal humans. Our preliminary study suggests that treatment with growth hormone results in increased ventricular contractility in rats with left ventricular dysfunction. In the present study, the effects of growth hormone on cardiac function, including cardiac output, stroke volume, and peripheral vascular resistance, were determined in a rat model of heart failure.

METHODS AND RESULTS

Ligation of the left coronary artery or sham operation was performed; 4 weeks after surgery, recombinant human growth hormone (2 mg/kg per day SC) or vehicle then was administered for 15 days. The animals were catheterized after 13 days of the treatment. Cardiac output, measured by a thermodilution method, and other hemodynamic parameters were measured in the conscious animals 2 days after catheterization. The infarct sizes induced by left coronary ligation were comparable between growth hormone-treated and vehicle-treated rats. Six weeks after ligation, rats treated with vehicle exhibited significant decreases in cardiac index, stroke volume index, and left ventricular maximum dP/dt and increases in left ventricular end-diastolic pressure compared with sham rats. In the ligated rats, treatment with growth hormone increased cardiac index, stroke volume index, and left ventricular maximum dP/dt (P < .05) and reduced left ventricular end-diastolic pressure and systemic vascular resistance (P < .05). In sham rats, growth hormone slightly reduced arterial pressure but did not significantly alter cardiac performance. There was no significant difference in heart rate between the experimental groups.

CONCLUSIONS

These results suggest that growth hormone treatment may improve cardiac function by both increased myocardial contractility and decreased peripheral vascular resistance in heart failure.

Effect of acidosis on hydrogen peroxide injury to the isolated perfused rat heart

We observed that both low and high doses of H2O2 (100 microM and 1 mM, respectively) caused significant and irreversible injury to cardiac contractile function in the isolated perfused heart model. Using 31P-nuclear magnetic resonance spectroscopy, we observed marked metabolic changes following exposure to H2O2, especially at the 1 mM dose. Most remarkable were the increases in the intensity of the phosphomonoester resonance that occurred immediately after exposure to H2O2. The major phosphomonoester species accumulating in hearts exposed to 1 mM H2O2 appears to be AMP. Exposure of hearts to H2O2 in the setting of metabolic acidosis did not significantly alter the functional response of isolated hearts to H2O2. However, the increases in phosphomonoester peak intensity following both doses of H2O2 and the decreases in tissue ATP and total phosphates following 1 mM H2O2 were attenuated by metabolic acidosis.

Stereochemical Aspects of the anti-HCMV Activity of Cytidine Nucleoside Analogues

The remarkable selectivity of the β-L enantiomers of 2′,3′-dideoxycytidine analogues against the viral polymerases of HIV and HBV has stimulated our interest in targeting β-L enantiomers of anti-HCMV cytidine analogues. Indeed, Ara-C, FIAC and DMDC are cytidine analogues with β-D configuration that show significant potency as anti-HCMV agents but lack selectivity. β-L enantiomers have therefore been synthesized and evaluated together with four other nucleoside analogues, and the β-L. enantiomers were found not to be inhibitory to HCMV replication. However, the three α-L isomers, α-L-Ara-C, α-L-Xylo-C and α-L-FMAU, emerged with activity against HCMV and have provided new approaches for the treatment of viral diseases with nucleoside analogues possessing the unusual L-configuration.

[Inhibitory effect of heparin on glomerular mesangial cell]

The pure mesangial cells (MsC) were isolated from the culture of rat glomeruli. After identification, they were divided into heparin-treatment group and control group. It was found that heparin profoundly inhibited the growth of MsC with 75.9% inhibitory rate by means of direct counting MsC. MTT method proved that the inhibitory effect of heparin on MsC was dose-dependent. Electronmicroscopic observation revealed dilated endoplasmic reticulum and Golgi vesicles, more secondary lysosomes, prominent myelin figures and decreased microfilaments in the cytoplasm of the MsC exposed to heparin. Immunocytochemical studies showed that the amounts of FN and LM in the cytoplasm of MsC decreased after heparin treatment. Immunocytochemical investigation also confirmed that heparin could inhibit the expression of nuclear oncogene c-fos and c-jun in the MsC stimulated by PMA. The significance and possible mechanism of inhibitory effect of heparin on MsC were discussed.

Drug resistance and gene amplification potential regulated by transforming growth factor beta 1 gene expression

Transforming growth factor beta 1 (TGF-beta 1) regulates a multitude of diverse biological functions in mammalian cells, and there is good evidence that aberrant expression of this growth factor can play an important role in mechanisms of malignant progression. We show that a TGF-beta 1-overexpressing mouse 10T1/2 cell line transfected with a TGF-beta 1 sequence that allows the synthesis of bioactive growth factor exhibits reduced sensitivity to the cytotoxic effects of the drug N-(phosphonacetyl)-L-aspartate (PALA) in colony-forming experiments. Furthermore, six independent 10T1/2 TGF-beta 1-transfected cell lines containing TGF-beta 1 gene expression under the control of a zinc sulfate-responsive metallothionein promoter were selected. In all cases, sensitivity to PALA cytotoxic effects was significantly reduced when cells were cultured under conditions that led to elevated levels of TGF-beta 1 gene expression when compared to cells containing basal levels of this growth factor. Fluctuation analysis to determine the rate of PALA resistance was performed with several TGF-beta 1-transfected cell lines in which growth factor expression was regulated by the metallothionein promoter. We observed significantly higher rates of PALA resistance/cell/generation in cell populations expressing high levels of TGF-beta 1 than in the same cells expressing relatively low levels of this growth factor. The only mechanism known for PALA resistance in mouse cells involves the amplification of the gene coding for the protein target of PALA, CAD, a multifunctional polypeptide containing carbamyl phosphate synthetase, aspartate transcarbamylase, and dihydroorotase. Southern blot analysis of colonies that survived normally cytotoxic concentrations of PALA exhibited CAD gene amplification. In total, these observations indicate that aberrant expression of TGF-beta 1 gene expression decreases the genetic stability of 10T1/2 cells, leading to increased rates of drug resistance and elevated gene amplification potential. The results of this study indicate a new malignancy related function for TGF-beta 1 alterations and suggest a novel role for aberrant expression of this growth factor in mechanisms of drug resistance and tumor progression.

Identification of Btk mutations in 20 unrelated patients with X-linked agammaglobulinaemia (XLA)

X-linked agammaglobulinaemia (XLA) is an inherited immunodeficiency resulting from mutations in the gene for a cytoplasmic protein tyrosine kinase (Btk). We have utilised reverse-transcription-based PCR in combination with the chemical cleavage and mismatch technique (CCM) to screen for Btk mutations in 42 unrelated patients having classical XLA or 'leaky' XLA-like phenotypes. A variety of mutations, including point mutations, large deletions and splicing defects were detected using this strategy. In total, 20 mutations were found in these patients. All the mutations were different with the exception of three unrelated patients who all showed the same Arg-->His amino acid substitution (R641H) at a highly-conserved residue in the kinase domain. We have also used structural modelling of the Btk kinase domain to predict how two different amino acid substitution mutations at highly-conserved residues are likely to affect the Btk kinase activity.

Protection against endotoxic shock by bactericidal/permeability-increasing protein in rats

Bactericidal/permeability-increasing protein (BPI) is a neutrophil primary granule protein that inhibits effects of LPS in vitro. The current study examined the effects of BPI on hemodynamics, mortality, and circulating endotoxin and cytokines in conscious rats with endotoxic shock. Catheters were implanted into the right femoral artery and vein. 1 d later, human recombinant BPI (10 mg/kg) or vehicle was intravenously injected immediately, 30 min, or 2 h after intravenous injection of LPS (7.5 mg/kg). Mean arterial pressure (MAP) and heart rate were monitored and blood was collected before and after injection. BPI given immediately or 30 min after LPS prevented the LPS-induced reduction in MAP at 4-8 h and markedly reduced mortality. BPI given 2 h after LPS injection had no protective effect. BPI treated immediately after LPS reduced the circulating levels of endotoxin and IL-6 but increased the circulating levels of TNF. We propose that BPI exerts its protective effect through a TNF-independent mechanism, by inhibiting endotoxin-stimulated production of IL-6.

Pressor and bradycardic effects of centrally administered relaxin in conscious rats

The current study tested the hypothesis that centrally administered relaxin elevates arterial pressure in conscious rats and that this hypertensive effect is mediated, at least in part, by central or peripheral vasopressin. Injection of human relaxin (0.068 or 0.34 microgram in 200 nL artificial cerebrospinal fluid) into the right lateral ventricle of conscious, unrestrained Sprague-Dawley rats caused significant dose-related increases in arterial pressure and decreases in heart rat. The pressor and bradycardic responses to intracerebroventricular injections of relaxin were significantly blunted by pretreatment with either intracerebroventricular or intravenous injection of a vasopressin receptor (V1) antagonist, suggesting that the cardiovascular effects of central relaxin are mediated, at least in part, by V1 receptors in the brain and perhaps also by vasopressin released into the peripheral circulation. Neither intracerebroventricular injection of the vehicle alone nor intravenous injection of relaxin (0.34 microgram) altered arterial pressure or heart rate. In contrast to the above, intravenous injections of relaxin (40 micrograms/kg) elicited pressor and tachycardic responses that were not blunted by pretreatment with either intracerebroventricular or intravenous injection of the V1 receptor antagonist. Together, these data suggest that in the central nervous system relaxin contributes to the regulation of cardiovascular function and that the mechanisms for the cardiovascular effects of central and peripheral relaxin are distinct.

Identification of the ankyrin-binding domain of the mouse T-lymphoma cell inositol 1,4,5-trisphosphate (IP3) receptor and its role in the regulation of IP3-mediated internal Ca2+ release

In this study we have used several complementary techniques to explore the interaction between the membrane linker molecule, ankyrin, and the inositol 1,4,5-trisphosphate (IP3) receptor in mouse T-lymphoma cells. Using double immunolabeling and laser confocal microscopy, we have found that both cytoplasmic IP3 receptor and ankyrin are preferentially accumulated within ligand-induced lymphocyte receptor-capped structures. The binding between ankyrin and IP3 receptor appears to be very specific. Further analyses indicate that the amino acid sequence GGVGDVLRKPS in the IP3 receptor shares a great deal of structural homology with the ankyrin-binding domain located in certain well characterized ankyrin-binding proteins such as the cell adhesion molecule, CD44. Biochemical studies using competition binding assays and a synthetic peptide identical to GGVGDVLRKPS (a sequence detected in rat brain IP3 receptor (amino acids 2548-2558) and mouse brain IP3 receptor (amino acids 2546-2556)) indicate that this 11-amino acid peptide binds specifically to ankyrin (but not fodrin or spectrin). Furthermore, this peptide competes effectively for ankyrin binding to IP3 receptor-containing vesicles and/or purified IP3 receptor, and it blocks ankyrin-induced inhibitory effects on IP3 binding and IP3-mediated internal Ca2+ release in mouse T-lymphoma cells. These findings suggest that this amino acid sequence, GGVGDVLRKPS, which is located close to the C terminus of the IP3 receptor, resides on the cytoplasmic side (not the luminal side) of IP3 receptor-containing vesicles. This unique region appears to be an important part of the IP3 receptor ankyrin-binding domain and may play an important role in the regulation of IP3 receptor-mediated internal Ca2+ release during lymphocyte activation.

Effects of growth hormone in rats with postinfarction left ventricular dysfunction

Growth hormone may affect cardiac function. In rats, chronic hypersecretion of growth hormone leads to increased maximum isometric contractile force of the left ventricular papillary muscle in vitro. In humans, administration of growth hormone can increase myocardial contractility. However, cardiac effects of growth hormone in heart failure or cardiac dysfunction have not been studied to date. The current study was to evaluate the cardiac effects of growth hormone in conscious rats with postinfarction left ventricular dysfunction and sham controls. Ligation of the left coronary artery or sham operation was performed, then 4 weeks after surgery, recombinant human growth hormone (2 mg/kg/day, SC) or vehicle was administered for 15 days. Catheters were implanted 13 days after treatment with growth hormone or vehicle. Hemodynamic parameters were measured in conscious rats 2 days after catheterization. In vehicle-treated rats, left ventricular systolic pressure, maximum dP/dt, and arterial pressure were significantly decreased and left ventricular end-diastolic pressure was significantly increased in the ligation group compared with sham controls. Growth hormone treatment increased left ventricular systolic pressure (p < 0.05) and dP/dt (p < 0.05) and reduced left ventricular end-diastolic pressure (p < 0.05), significantly in the ligated rats. In sham rats, growth hormone tended to decrease arterial pressure but did not alter ventricular contractility. Neither ligation nor growth hormone significantly altered heart rate and right atrial pressure. These results suggest that growth hormone treatment may improve cardiac function by increasing myocardial contractility in cardiac dysfunction or heart failure.

Genomic organization of mouse and human Bruton's agammaglobulinemia tyrosine kinase (Btk) loci

Btk is a cytoplasmic protein tyrosine kinase (PTK) that has been directly implicated in the pathogenesis of X-linked agammaglobulinaemia (XLA) in humans and X-linked immunodeficiency (Xid) in mice. We have isolated phage and cosmid clones that allowed us to deduce the genomic structure of mouse and human Btk loci. The mouse and human genes are contained within genomic regions that span approximately 43.5 kb and 37.5 kb, respectively. Both loci contain 18 coding exons ranging between 55 and 560 bp in size with introns ranging in size from 164 bp to approximately 9 kb. The 5'-untranslated regions are encoded by single exons located approximately 9 kb upstream of the first coding exon. Exon 18 encodes for the last 23 carboxyl-terminal amino acids and the entire 3'-untranslated region. The location of intron/exon boundaries in the catalytic domains of the mouse and human Btk loci differs from that found in other described sub-families of intracellular PTKs, namely that of Src, Fes/Fer, Csk, and Abl/Arg. This observation is consistent with the classification of Btk together with the recently characterized kinases, Tec and Itk, into a separate sub-family of cytoplasmic PTKs. Putative transcription initiation sites in the mouse and human Btk loci have been determined by using the rapid amplification of cDNA ends assay. Similar to many other PTK specific genes, the putative Btk promoters lack obvious TATAA and CAAAT motifs. Putative initiator elements and potential binding sites for Ets (PEA-3), zeste, and PuF transcription factors are located within the 300 bp which are located upstream of the major transcription start site in both species. These sequences can mediate promoter activity when placed upstream of a promotorless chloramphenicol acetyl transferase reporter gene in an orientation-dependent manner. The present analysis will significantly facilitate the mutational analyses of patients with XLA and the further characterization of the function and regulation of the Btk molecule.