Rat Parathyroid Hormone 1 − 34 Signals through the MEK/ERK Pathway to Induce Cardiac Hypertrophy

This study aimed to characterize the role of the mitogen-activated protein kinase (MAPK) kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway in cardiac hypertrophy induced by parathyroid hormone (PTH). Various concentrations of rat PTH1–34 were used to induce hypertrophy in neonatal rat ventricular cardiomyocytes, and the effects were compared with control cells and those treated with PD98059, a selective inhibitor of MEK1. Hypertrophy was assessed in terms of cell diameter, atrial natriuretic peptide (ANP) mRNA expression and protein synthesis; the MEK/ERK pathway was assessed by measuring levels of phosphorylated ERK1/2. Treatment with PTH1–34 at 100 nM for 24 h effectively induced cardiac hypertrophy (increased cell diameter, protein synthesis and ANP mRNA expression) and also increased levels of phosphorylated ERK1/2 compared with normal control cells. Treatment with PTH1–34 plus PD98059 significantly attenuated these changes. These results demonstrate that inhibition of the MEK/ERK pathway blocks PTH1–34-induced cardiac hypertrophy, suggesting that PTH1–34 might signal through the MAPK pathway to induce hypertrophy in cardiomyocytes.

Osteoclast differentiation during experimental tooth movement by a short-term force application: an immunohistochemical study in rats

OBJECTIVE

The origin of osteoclasts responsible for bone resorption during orthodontic tooth movement is not yet clear. Their precursors may reside within the periodontal ligament (PDL) or could be recruited from the circulation or the bone marrow. The aim of this study was to investigate the spatial and sequential distribution of osteoclast precursors during experimental tooth movement by using three differentiation markers: receptor for macrophage colony stimulating factor (c-Fms), receptor activator of nuclear factor-kappaB (RANK), and calcitonin receptor (CTR).

MATERIAL AND METHODS

Six-week-old Wistar rats were used. Elastic bands were inserted between the upper 1st and 2nd molars for 1, 2, 3, and 6 days. Immunohistochemical staining for c-Fms, RANK, or CTR was performed on parasagittal sections and positive cells were counted.

RESULTS

Before force application, many c-Fms+ and a few RANK+ precursors were present in the bone marrow. No c-Fms+ osteoclast precursors were observed in the PDL. After force application, the number of RANK+ but not c-Fms+ precursors increased rapidly in the PDL. In bone marrow, the number of c-Fms+ and RANK+ precursors also increased rapidly, as did multinuclear c-Fms+, RANK+, and CTR+ cells. Subsequently, the number of c-Fms+, RANK+, and CTR+ multinuclear cells in the PDL increased. After 6 days, the expression profiles tended to return to baseline levels.

CONCLUSION

Osteoclast precursors differentiate within the bone marrow and then migrate into the PDL during early tooth movement.

Whole cell recordings of intrinsic properties and sound-evoked responses from the inferior colliculus

Response features of inferior colliculus (IC) neurons to both current injections and tone bursts were studied with in vivo whole cell recordings in awake Mexican free-tailed bats. Of 160 cells recorded, 95% displayed one of three general types of discharge patterns in response to the injection of positive current: 1) sustained discharges; 2) adapting discharges; and 3) onset-bursting discharges. Sustained neurons were the most common type (N=78), followed by onset-bursting (N=57). The least common type was adapting (N=17). In 90 neurons the profiles of synaptic and discharge activity evoked by tones of different frequencies at 50 dB SPL were recorded. Three major tone-evoked response profiles were obtained; 1) neurons dominated by excitation (N=32) in which tones evoked excitatory post-synaptic potentials (EPSPs) or EPSPs with discharges over a range of frequencies with little or no evidence of inhibitory post-synaptic potentials (IPSPs) evoked by frequencies that flanked the excitation; 2) neurons that had an excitatory frequency region in which discharges were evoked that was flanked by frequencies that evoked predominantly IPSPs (N=26); 3) neurons in which all frequencies evoked IPSPs with little or no depolarizations (N=32). The question we asked is whether IC cells that express a particular profile of PSPs and discharges to acoustic stimulation also have the same current-evoked response profile. We show that, with one exception, the intrinsic features of an IC neuron are not correlated with the pattern of its synaptic innervation; the two features are unrelated in the majority of IC cells. The exception is a subtype of inhibitory dominated cell where most frequencies evoked IPSPs to both the onset and to the offset of the tone bursts. In those cells injected current steps always evoked an onset-bursting response.

Forced expression of hepatocyte-specific fibroblast growth factor 21 delays initiation of chemically induced hepatocarcinogenesis

Inappropriate fibroblast growth factor (FGF) signaling is involved in most tissue-specific pathologies including cancer. Previously we showed that inappropriate expression and chronic activity of FGF receptor (FGFR) 1 in hepatocytes accelerated diethylnitrosamine (DEN)-initiated hepatocarcinogenesis. Here we showed that although widely expressed FGF1 and FGF2 are frequently upregulated in hepatocellular carcinoma (HCC), germline deletion of both FGF1 and FGF2 had no effect on DEN-initiated hepatocarcinogenesis. Thus overexpression of FGF1 or FGF2 may be a consequence rather than contributor to hepatoma progression. FGF21 is the first of 22 homologues whose expression has been reported to be preferentially in the liver. We showed that similar to FGF1 and FGF2, FGF21 mRNA was upregulated in neoplastic and regenerating liver after partial hepatectomy (PH) and CCl4 administration. In situ hybridization analysis confirmed that in contrast to FGF1 and FGF2, expression of FGF21 mRNA was limited to hepatocytes. Forced overexpression of FGF21 in hepatocytes by gene targeting had no apparent impact on normal liver development and compensatory response to injury. Surprisingly, overexpression of FGF21 delayed the appearance of DEN-induced liver tumors. At 8 and 10 mo, only 10% and 30% of transgenic mice, respectively, developed adenomas compared to 50% (all adenomas) and 80% (60% adenoma/20% HCC) in the wild-type (WT) mice. However, the incidence and burden of HCC at 10 mo and later was equal in the FGF21 transgenic and WT mice. We propose that FGF21 may delay development of adenomas through activation of resident hepatocyte FGFR4 at early times, but counteracts the delay by acceleration of progression to HCC through interaction with ectopic FGFR1 once it appears in hepatoma cells. This indicates a dual function of FGF21 that may reflect changes in FGFR isotype during progression of differentiated hepatoma cells.

Preparation of highly monodisperse W/O emulsions with hydrophobically modified SPG membranes

Experimental investigations on the hydrophobic modification of SPG membranes and the preparation of monodisperse W/O (water-in-oil) emulsions using the modified membranes were carried out. Effects of the osmotic pressure of disperse phase, the average pore size of membranes, emulsifier concentrations in continuous phase and the transmembrane pressure on the average size, size distribution and size dispersion coefficient of emulsions were systematically studied. The stability of W/O emulsions was also investigated. The results showed that SPG membranes took on excellent hydrophobicity through the modification by silane coupler reagent (octyltriethoxysilane) or by silicone resin (polymethylsilsesquioxane). Monodisperse W/O emulsions with size dispersion coefficient of about 0.25, which meant high monodispersity, were successfully prepared by using the hydrophobically modified SPG membranes with average pore sizes of 1.8, 2.0, 2.5, 4.8 and 11.1 microm. When the osmotic pressure was lower than 0.855 MPa, the average size of emulsions was gradually increased while the size dispersion coefficient delta gradually decreased with the osmotic pressure; when the osmotic pressure was higher than 0.855 MPa, both the coefficients kept unvarying. When kerosene was saturated with disperse phase in advance, the average size of emulsions became larger and the monodispersity of emulsions was slightly better than that prepared using unsaturated kerosene. The smaller the pore size of SPG membranes was, the better the monodispersity of the W/O emulsions. The average size and size dispersion coefficient delta were nearly independent on the emulsifier concentrations when the PGPR concentration was in the range from 0.5 to 5.0 wt%, whereas both of them slightly increased as the PGPR concentration was below 0.5 wt%. The effect of the transmembrane pressure on size distributions was slight. Both the average size and size dispersion coefficient delta slightly increased to some extent with the increase of the transmembrane pressure in the experimental range. The stability of the W/O emulsions was dependent on the storage time. The mean size of W/O emulsions decreased gradually with the increase of storage time at the first 35 days, and then kept constant; while the size dispersion coefficient of W/O emulsions was nearly not changed.

Preparation of submicrometer-sized monodispersed thermoresponsive core-shell hydrogel microspheres

We have successfully prepared monodispersed thermoresponsive core-shell hydrogel microspheres with a mean diameter of 200-400 nm with poly(N-isopropylacrylamide-co-styrene) [P(NIPAM-co-St)] cores and poly(N-isopropylacrylamide) (PNIPAM) shells. The submicrometer-sized monodispersed P(NIPAM-co-St) core seeds were prepared by using a surfactant-free emulsion polymerization method, and the PNIPAM shell layers were fabricated onto the core seeds by using a seed polymerization method. The particle size, morphology and monodispersity, and thermoresponsive characteristics of the prepared microspheres were experimentally studied. In the preparation of P(NIPAM-co-St) seeds, with increasing the initiator dosage, the mean diameters and the dispersal coefficients were almost at the same levels at first; however, when the initiator dosage increased further to a critical amount, the mean diameters decreased drastically and the monodispersity became worse significantly. With increasing the stirring rate, the particle diameter decreased, and when the stirring rate was larger than 600 rpm, the monodispersity became worse obviously. With increasing the phase ratio, the mean diameter became larger simply, and the monodispersity became worse first and then became better again. With increasing the reaction time, the particle sizes nearly did not change, while the monodispersity gradually became better slightly. For the core-shell microspheres, with increasing the NIPAM dosage in the preparation of the PNIPAM shell layers, the mean diameters became larger simply, the monodispersity became better, and the thermoresponsive swelling ratio of the hydrodynamic diameters increased.

Phase I and pharmacokinetic study of irinotecan in combination with R115777, a farnesyl protein transferase inhibitor

The aims of this study were to determine the maximum-tolerated dose (MTD), toxicity profile, and pharmacokinetics of irinotecan given with oral R115777 (tipifarnib), a farnesyl protein transferase inhibitor. Patients were treated with escalating doses of irinotecan with interval-modulated dosing of R115777 (continuously or on days 1–14, and repeated every 21 days). In total, 35 patients were entered onto the trial for a median duration of treatment of 43 days (range, 5–224 days). Neutropenia and thrombocytopenia were the dose-limiting toxicities; other side effects were mostly mild. The MTD was established at R115777 300 mg b.i.d. for 14 consecutive days with irinotecan 350 mg m⁻² given every 3 weeks starting on day 1. Three patients had a partial response and 14 had stable disease. In the continuous schedule, the area under the curves of irinotecan and its active metabolite SN-38 were 20.0% (P=0.004) and 38.0% (P<0.001) increased by R115777, respectively. Intermittent dosing of R115777 at a dose of 300 mg b.i.d. for 14 days every 3 weeks is the recommended dose of R115777 in combination with the recommended single-agent irinotecan dose of 350 mg m⁻².

Benzodioxocin-3-ones and N-acyl-3-amino-3-buten-2-ones: novel classes of cathepsin K cysteine protease inhibitors

The design, synthesis, enzymologic, and protein mass spectrometric characterization of benzodioxocin-3-one and N-acyl-3-amino-3-buten-2-one inhibitors of the cysteine protease cathepsin K are described. The benzodioxocin-3-one ring system is chemically unstable giving rise to a mixture of N-acyl-3-amino-3-buten-2-one and hemiketals. This mixture of N-acyl-3-amino-3-buten-2-one and hemiketals potently inhibits recombinant, human cathepsin K (IC50 = 36 nM) by a time-independent, irreversible mechanism. Formation of a covalent adduct between cathepsin K and inhibitor has been confirmed by mass spectrometry.

Study of SPG membrane emulsification processes for the preparation of monodisperse core-shell microcapsules

Experimental investigations on the Shirasu-porous-glass (SPG)-membrane emulsification processes for preparing monodisperse core-shell microcapsules with porous membranes were carried out systematically. The results showed that, to get monodisperse oil-in-water (O/W) emulsions by SPG membrane emulsification, it was more important to choose an anionic surfactant than to consider hydrophile-lipophile balance (HLB) matching. Increasing the viscosity of either the disperse phase or the continuous phase or decreasing the solubility of the disperse phase in the continuous phase could improve both the monodispersity and the stability of emulsions. With increasing monomer concentration inside the disperse phase, the monodispersity of emulsions became slightly worse and the mean diameter of emulsions gradually became smaller. Monodisperse monomer-containing emulsions were obtained when the SPG membrane pore size was larger than 1.0 micro m, and from these emulsions satisfactory monodisperse core-shell microcapsules with a porous membrane were prepared. On the other hand, when the SPG membrane pore size was smaller than 1.0 mciro m, no monodisperse emulsions were obtained because of the formation and chokage of solid monomer crystals in the pores or at the end of the pores of the SPG membrane. This was due to the remarkable solvation and diffusion of the solvent in water. With increasing the emulsification time the average emulsion diameter generally decreased, and the monodispersity of the emulsions gradually became worse.