Impact of feeding method on overall activity of indoor, client-owned dogs

OBJECTIVE

To compare the total daily activity time, walking time and running time using food-dispensing toys versus bowls in a group of client-owned, primarily indoor dogs.

MATERIALS AND METHODS

A two-way, two period, randomised repeated measures mixed-effects crossover study performed on 26 client-owned, primarily indoor dogs.

RESULTS

Toy feeding increased average daily total activity time by 12% and walking time by 26%. Average daily total activity time and walking time were reduced by 8 and 7% respectively with each increase in year of age. Gender, body condition and muscle condition had no significant effect on average daily total activity or walking time. Toy feeding, time, their interaction, age, gender, body condition and muscle condition had no significant effect on average daily running time.

CLINICAL SIGNIFICANCE

Feeding toys may be helpful during weight loss programs to achieve the goal of increasing daily exercise duration in dogs that need to lose weight.

Cone beam CT analysis of Haller cells: prevalence and clinical significance

OBJECTIVES

Haller cells are anterior ethmoid air cells located in the medial orbital floor immediately lateral to the maxillary infundibulum. The purpose of this study was to demonstrate the prevalence and relationship between the existence and size of these cells with ipsilateral maxillary sinusitis and orbital floor dehiscence as visualized on cone beam CT (CBCT) images.

METHODS

CBCT image volumes of 50 patients were retrieved and analysed. All CBCT images were acquired with a 9-inch field of view scan. χ(2) and Cochran-Mantel-Haenszel tests were used for statistical analysis of the obtained data, and p-values of <0.05 were considered to be statistically significant.

RESULTS

There was no statistically significant association between the existence and size of Haller cells and maxillary sinusitis. There was a significant association between Haller cells and orbital floor dehiscence.

CONCLUSIONS

The explanation of maxillary sinusitis on the basis of mechanical obstruction is unlikely. This study provides evidence for the usefulness of CBCT scan in delineation of the sinonasal anatomy.

Effective distribution of domestic wastewater effluent between percolation trenches in on-site treatment systems

On-site treatment systems discharging to groundwater rely on the effective distribution of effluent across a percolation area to provide an appropriate loading rate for the subsoil. In Ireland, this is achieved in a distribution box which splits the effluent evenly between the requisite number of percolation pipes. The flow regime experienced at four different distribution boxes was monitored continuously over twelve month periods which established that the most common flow rates at the distribution unit were in the range 1-4 litres/minute for a four to five person dwelling. In addition, the average flow rate from the four sites was only 100 litres per person per day, compared to recommended design value of 180 litres per person per day. Two distribution boxes were also tested in the laboratory to assess their distribution efficiency over a range of loading rates. The most commonly installed unit was found to significantly favour two out of the four trenches and both units were shown to perform particularly poorly at a range of different off-level installation angles. Modifications to the boxes were also tested, involving plastic V-notch inserts which were shown to greatly improve the hydraulic distribution and make the unit much less sensitive to off-level installation or subsidence.

Cerebrospinal fluid levels of nitric oxide metabolites predict response to methylprednisolone treatment in multiple sclerosis and optic neuritis

The role of nitric oxide (NO) in multiple sclerosis (MS) is not clear. We found increased cerebrospinal fluid concentrations of the NO degradation products nitrate (NO(x)) in clinically definite MS but not in clinically isolated syndromes. High CSF concentrations of NO(x) correlated with long attack duration. Patients carrying the truncated CC chemokine receptor allele CCR5 Delta32 had lower serum concentration of NO(x) at later attack stages. NO(x) concentrations did not change after methylprednisolone treatment but high concentrations were associated with more pronounced treatment responses. These findings suggest an association of high CSF levels of NO(x) with more severe disease activity in relapsing-remitting MS.

Regulation of fibroblast growth factor 2 and fibroblast growth factor receptors by transforming growth factor beta in human osteoblastic MG-63 cells

Fibroblast growth factor 2 (FGF-2) and its receptors (FGFRs) are important regulators of bone cell function. Although FGF-2 is a major modulator of bone cell function, its expression and regulation in human osteoblasts have not been investigated. We examined FGF-2 messenger RNA (mRNA) expression and regulation in the human osteosarcoma MG-63 cells. Northern analysis revealed that MG-63 cells expressed FGF-2 mRNA transcripts of 7, 4, 2.2, and 1.3 kilobases (kb). In the absence of serum, treatment with transforming growth factor beta (TGF-beta; 0.1-10 ng/ml) increased all FGF-2 mRNA transcripts. Maximal increase was seen with 1 ng/ml of TGF-beta. TGF-beta increased FGF-2 mRNA expression within 2 h and this was sustained for 24 h. Phorbal myristate acetate (PMA; 1 microM) also increased FGF-2 mRNA at 6 h. Time course studies showed that TGF-beta did not significantly alter FGFR1 or FGFR2 mRNA expression in MG-63 cells. Western blotting with anti-human FGF-2 revealed that MG-63 cells synthesize three isoforms of FGF-2 protein of approximately 18, 22/23, and 24 kDa, which were increased after either 6 h or 24 h of treatment with TGF-beta. Increased FGF-2 mRNA and protein expression in response to TGF-beta was markedly reduced by the protein kinase A (PKA) inhibitor H-89. Immunogold labeling of MG-63 cells treated with TGF-beta showed increased labeling for FGF-2 and FGFR2 in the nuclei. In contrast, TGF-beta treatment significantly decreased FGFR1 labeling in the nuclei. These data show that TGF-beta regulates FGF-2 gene expression in human osteosarcoma cells. Furthermore, TGF-beta modulates the cellular localization of FGF-2 and its receptors.

Sympathectomy decreases and adrenergic stimulation increases the release of tissue plasminogen activator (t-PA) from blood vessels: functional evidence for a neurologic regulation of plasmin production within vessel walls and other tissue matrices

Our recent morphologic studies indicated that peripheral nervous system (PNS) adrenergic neurons synthesize, transport, and store the serene protease, tissue plasminogen activator (t-PA) in axon terminals, many of which innervate vessel walls. Sympathoadrenal stimulation induces a surge of t-PA from vessel walls into the blood. The vascular endothelium, which constitutively secretes t-PA into blood also has long been widely assumed to be the principal source of this stress-induced release, but has not been verified as such. A neurologically regulated release from adrenergic stores could thus augment the known constitutive endothelial release. To functionally test this possibility, we quantitated the effects of guanethidine-induced systemic sympathectomy on the basal and stimulated release of t-PA from isolated vessel explants in superfused organ cultures. Moment-to-moment changes in the release rate were plotted from serial assays of the t-PA free activity. The effects of endothelial and adventitial nerve plexus ablations were also tested. Sympathectomy induced 30-50% reductions in t-PA release from both arterial and microvascular explants. An acute release induced by alpha-1 adrenergic receptor stimulations was also strongly suppressed, as were basal levels of the circulating enzyme in vivo. Adventitial and endothelial ablations from normal large vessel explants produced greater reductions than small vessel endothelial ablations. Ganglion electrical stimulation also induced an acute microvascular release in vivo. These and past morphologic findings indicate a physiological infusion of t-PA into the vessel walls, blood, and other innervated matrices by sympathetic neurons.

Trafficking, assembly, and function of a connexin43-green fluorescent protein chimera in live mammalian cells

To examine the trafficking, assembly, and turnover of connexin43 (Cx43) in living cells, we used an enhanced red-shifted mutant of green fluorescent protein (GFP) to construct a Cx43-GFP chimera. When cDNA encoding Cx43-GFP was transfected into communication-competent normal rat kidney cells, Cx43-negative Madin-Darby canine kidney (MDCK) cells, or communication-deficient Neuro2A or HeLa cells, the fusion protein of predicted length was expressed, transported, and assembled into gap junctions that exhibited the classical pentalaminar profile. Dye transfer studies showed that Cx43-GFP formed functional gap junction channels when transfected into otherwise communication-deficient HeLa or Neuro2A cells. Live imaging of Cx43-GFP in MDCK cells revealed that many gap junction plaques remained relatively immobile, whereas others coalesced laterally within the plasma membrane. Time-lapse imaging of live MDCK cells also revealed that Cx43-GFP was transported via highly mobile transport intermediates that could be divided into two size classes of <0.5 microm and 0.5-1.5 microm. In some cases, the larger intracellular Cx43-GFP transport intermediates were observed to form from the internalization of gap junctions, whereas the smaller transport intermediates may represent other routes of trafficking to or from the plasma membrane. The localization of Cx43-GFP in two transport compartments suggests that the dynamic formation and turnover of connexins may involve at least two distinct pathways.

Biologically active Fas antigen and its cognate ligand are expressed on plasma membrane-derived extracellular vesicles

Exfoliation of plasma membrane components is a directed process that consumes energy and requires active cell metabolism. Proteins involved in regulating the survival and proliferation of eukaryotic cells are released on exfoliated vesicles. We examine here whether the Fas receptor and its cognate ligand (FasL) are present on vesicles shed from high metastatic potential CX-1 cells and low metastatic potential MIP-101 cells and from HuT 78 cells, respectively. Rates of exfoliation at 2 hours and cumulative levels of extracellular vesicles in serum-free medium conditioned by CX-1 cells are increased by 1.8-fold and 1.6-fold, respectively, relative to that in medium conditioned by MIP-101 cells. Although vesicles shed from both cancer cell lines contain Fas antigen, the amount of Fas per vesicle and the percentage of vesicles containing Fas are increased for vesicles isolated from MIP-101 cells, relative to those from CX-1 cells, as determined by immunogold particle labeling and electron microscopy and by immunofluorescence microscopy and flow cytometry. Results of metabolic labeling with 35S-methionine indicate that Fas biosynthesis is reduced by up to 3.3-fold for CX-1 cells, relative to that of MIP-101 cells, consistent with the finding of decreased Fas on vesicles shed from the plasma membrane of CX-1 cells. Although mRNA for soluble Fas receptor is detectable in both cell lines, depletion of shed vesicles from serum-free medium by ultracentrifugation removes all detectable biological activity. FasL is detected on vesicles exfoliated from HuT 78 cells by immunoelectron microscopy and Western blot analysis. FasL-bearing vesicles induce apoptosis of Fas-expressing cancer cells at the same level as observed by treatment with monoclonal anti-Fas antibody. Furthermore, Fas-bearing extracellular vesicles from MIP-101 but not from CX-1 cells protect the CX-1 cell line from FasL-induced and anti-Fas-mediated apoptosis, indicating that Fas present on shed vesicles is biologically active. We conclude that the Fas antigen and its cognate ligand are exfoliated from the cell surface in a bioactive configuration. Exfoliation may provide a mechanism for long-range signal-directed apoptosis while maintaining Fas/FasL on a membrane surface.

Interferon-induced growth arrest is mediated by membrane structural changes

Interferon-gamma (IFN-gamma) is an immunomodulator shown to augment the expression of major histocompatibility (MHC) class I/class II antigens on the cell surface. In previous studies, we have demonstrated that the enhanced expression of these antigens on the cell surface is in part due to IFN-gamma-mediated abrogation of antigen shedding. In this study, we demonstrate that IFN-gamma induces structural changes in the cell membrane by altering the cholesterol/phospholipid ratio. Furthermore, such changes not only mediate enhanced expression of antigen on the cell surface but may drive the cells to growth arrest and apoptosis. These results were obtained by employing x-ray diffraction, electron microscopy, and DNA analysis.

Structure-activity studies of rapamycin analogs: evidence that the C-7 methoxy group is part of the effector domain and positioned at the FKBP12-FRAP interface

BACKGROUND

Rapamycin is an immunosuppressant natural product, which blocks T-cell mitogenesis and yeast proliferation. In the cytoplasm, rapamycin binds to the immunophilin FKBP12 and the complex of these two molecules binds to a recently discovered protein, FRAP. The rapamycin molecule has two functional domains, defined by their interaction with FKBP12 (binding domain) or with FRAP (effector domain). We previously showed that the allylic methoxy group at C-7 of rapamycin could be replaced by a variety of different substituents. We set out to examine the effects of such substitutions on FKBP12 binding and on biological activity.

RESULTS

Rapamycin C-7-modified analogs of both R and S configurations were shown to have high affinities for FKBP12, yet these congeners displayed a wide range of potencies in splenocyte and yeast proliferation assays. The X-ray crystal structures of four rapamycin analogs in complexes with FKBP12 were determined and revealed that protein and ligand backbone conformations were essentially the same as those observed for the parent rapamycin-FKBP12 complex and that the C-7 group remained exposed to solvent. We then prepared a rapamycin analog with a photoreactive functionality as part of the C-7 substituent. This compound specifically labeled, in an FKBP12-dependent manner, a protein of approximately 250 kDa, which comigrates with recombinant FRAP.

CONCLUSIONS

We conclude that the C-7 methoxy group of rapamycin is part of the effector domain. In the ternary complex, this group is situated in close proximity to FRAP, at the interface between FRAP and FKBP12.

Interferon (IFN)-alpha and IFN-gamma in combination with methotrexate: in vitro sensitivity studies in four human mesothelioma cell lines

Mesothelioma is a malignant tumor of the serous surfaces in the thorax and abdomen, which has proved exceptionally resistant to treatment. A recent phase II trial of a high-dose methotrexate regime on 63 Norwegian patients has, however, achieved a response rate of 37%. Some responses have also been achieved using interferon (IFN)-gamma administered intrapleurally or recombinant (r) IFN-alpha administered subcutaneously. Our earlier in vitro sensitivity studies of mesothelioma cell lines showed that IFN augments the response to chemotherapeutic agents in mesothelioma. The aim of this study was to assess the response of four mesothelioma cell lines, derived from diffuse asbestos-related pleural malignant mesothelioma, to methotrexate alone and in combination with recombinant IFN-alpha and IFN-gamma. Anti-proliferative effects were assayed by vital dye exclusion. A combination of IFN-alpha and IFN-gamma consistently augmented the response of the cell lines to methotrexate, by as much as 75% for one cell line, although the response to the individual IFNs was variable. We were also able to compare the effects of natural IFN-beta with those of IFN-alpha and IFN-gamma. The IFN-beta sensitivity profile for each of the four cell lines was similar to that of IFN-alpha. In two cell lines, the combination of IFN-beta and IFN-gamma produced a similar effect to the IFN-alpha and IFN-gamma combination.

Human macrophage colony-stimulating factor is expressed at and shed from the cell surface

Surface membrane-associated growth factors are being recognized as important for developmental processes, including cell assembly, differentiation, and growth. To investigate the role of membrane-bound macrophage colony-stimulating factor (M-CSF) in myelopoiesis, and whether this factor is released from the cell surface in association with shed membrane-derived vesicles, COS-1 cells were transfected with cDNAs for M-CSF-tau (containing the transmembrane domain) or a soluble mutant form of the molecule lacking the transmembrane domain ([s]M-CSF-alpha). COS-1 cells transfected with either cDNA released activity into the spent culture medium. Conditioned medium was separated by centrifugation into supernatants and pellets were found to contain plasma membrane-derived vesicles by transmission electron microscopy. When medium fractions were assayed in marrow cultures, activity was localized to shed plasma membrane-derived vesicles in medium conditioned by cells transfected with cDNA for M-CSF-tau and in the vesicle-free supernatants of medium conditioned by cells transfected with cDNA for [s]M-CSF-alpha. In addition, nuclear, mitochondrial, and plasma membrane subfractions of stably transfected cells were prepared and assayed for activity. Concentration-dependent stimulation of macrophage colony formation was observed with purified plasma membranes (but not nuclear or cytosolic proteins) from cells transfected with cDNA for M-CSF-tau. By contrast, membranes from untransfected cells and cells transfected with cDNA for [s]M-CSF-alpha or control DNA expressed no activity. Together, the data indicate that human M-CSF is expressed at the cell surface and exfoliated in association with surface membrane-derived vesicles.

Interferon-alpha and interferon-gamma combined with chemotherapy: in vitro sensitivity studies in non-small cell lung cancer cell lines

Non-small cell lung cancers (NSCLC) are often resistant to chemotherapy. Cisplatin has shown the most activity against all the histological subtypes and is now used in most combined treatment programmes. Interferon (IFN)-alpha has been shown to potentiate cisplatin and other drugs experimentally and in clinical trials involving NSCLC. We are looking at the responses of different NSCLC cell lines to cisplatin (P), etoposide (VP-16) and IFN [recombinant human IFN-alpha 2c (IFN-alpha) and IFN-gamma 1b (IFN-gamma)], individually and in combination. We then compare the results with those from a clinical trial of etoposide and cisplatin with interferon in advanced NSCLC. We report here the results from the first of our cell lines, established from a large cell anaplastic carcinoma. We have confirmed earlier findings that NSCLC cell lines are not sensitive to either IFN-alpha or IFN-gamma alone. However a combination of IFN-alpha and IFN-gamma does reduce cell proliferation in our cell lines. This IFN combination potentiates the response of the cells to etoposide far more than to cisplatin. There is a trend towards greater activity when a combination of cisplatin and etoposide is used, compared with the activity of either drug alone. This effect is further increased by the interferon combination.

Gap junction formation in human myometrium: a key to preterm labor?

OBJECTIVE

The purpose of this study was to determine if gap junctions are a necessary component of the human laboring uterus and if their presence in myometrium is a prerequisite for both term and preterm labor.

STUDY DESIGN

We obtained 27 human myometrial samples at cesarean section or nongravid hysterectomy. Gap junction formation was analyzed in a blind fashion by freeze fracture and indirect immunofluorescence. Six samples were obtained from term patients with no labor, six from term patients in labor, six from preterm patients with no labor, six from patients in preterm labor, and three from nongravid hysterectomy specimens.

RESULTS

Gap junction structures were identified in the human myometrium of patients in term and in preterm labor but not in the other patient samples. In addition, evidence was obtained for the expression of (alpha 1) gap junction ribonucleic acid and (alpha 1) gap junction protein in term samples of human myometrium.

CONCLUSION

Gap junctions are a necessary component of the human myometrium during term and preterm labor. The formation of gap junctions may be a final common event for the development of labor, and inhibition of gap junction activity could be a novel approach for the treatment of preterm labor.

Pyridinyl imidazoles inhibit IL-1 and TNF production at the protein level

The mechanism by which SK&F 86002 and other pyridinyl imidazoles inhibit the production of IL-1 and TNF from LPS-stimulated human monocytes was examined. Inhibition of IL-1 and TNF production was found to depend on the time of addition of SK&F 86002, with diminishing effect when added more than 2 h after LPS stimulation. Analysis of Western blots confirmed that both intracellular IL-1 beta and extracellular TNF were significantly reduced in response to SK&F 86002, but these reductions were not paralleled by changes in IL-1 and TNF mRNA. 35S methionine pulse and pulse-chase studies on IL-1 biosynthesis suggest that significant inhibition by SK&F 86002 and related compounds occurs at the translational level.

Regulation of ICAM-1 expression and function in human dermal fibroblasts by IL-4

ICAM-1 is found on the surface of many hematopoietic and nonhematopoietic cells and can function as an adhesive ligand for the integrin, leukocyte function-associated molecule-1 (LFA-1, CD11a/CD18). ICAM-1/leukocyte function-associated molecule-1 interaction has been shown to be of importance in many immune-mediated cell-cell adhesion reactions. In vitro, unstimulated human fibroblast cell cultures express low levels of ICAM-1. Using ELISA, cytofluorography, electron microscopy, Northern analysis, and an in vitro cell adherence assay, we demonstrate that treatment of human dermal fibroblasts with the cytokine IL-4 leads to an increase in cell surface ICAM-1 expression that is under transcriptional control as well as increased fibroblast adhesion to LFA-1-bearing T lymphocytes. The kinetics of increased ICAM-1 expression induced by IL-4 paralleled the increase in ICAM-1-dependent T lymphocyte adhesion. The increase in T cell adhesion was determined to be due to the effects of IL-4 on the fibroblasts and not the adhering T cells. Treatment of fibroblasts with IL-4 also resulted in enhanced binding of human rhinovirus, a recently reported additional ligand for ICAM-1. Virus binding was IL-4 dose dependent and could be inhibited with mAb to ICAM-1. Both the expression of ICAM-1 and the ICAM-1-dependent increase in T lymphocyte adhesion that was induced by IL-4 could be inhibited by preexposure of the fibroblasts to either IL-1 or IL-6, suggesting that multiple cytokines can have both positive and negative effects on human fibroblast ICAM-1 expression and function.

Regulation of ICAM-1 expression and function in human dermal fibroblasts by IL-4

ICAM-1 is found on the surface of many hematopoietic and nonhematopoietic cells and can function as an adhesive ligand for the integrin, leukocyte function-associated molecule-1 (LFA-1, CD11a/CD18). ICAM-1/leukocyte function-associated molecule-1 interaction has been shown to be of importance in many immune-mediated cell-cell adhesion reactions. In vitro, unstimulated human fibroblast cell cultures express low levels of ICAM-1. Using ELISA, cytofluorography, electron microscopy, Northern analysis, and an in vitro cell adherence assay, we demonstrate that treatment of human dermal fibroblasts with the cytokine IL-4 leads to an increase in cell surface ICAM-1 expression that is under transcriptional control as well as increased fibroblast adhesion to LFA-1-bearing T lymphocytes. The kinetics of increased ICAM-1 expression induced by IL-4 paralleled the increase in ICAM-1-dependent T lymphocyte adhesion. The increase in T cell adhesion was determined to be due to the effects of IL-4 on the fibroblasts and not the adhering T cells. Treatment of fibroblasts with IL-4 also resulted in enhanced binding of human rhinovirus, a recently reported additional ligand for ICAM-1. Virus binding was IL-4 dose dependent and could be inhibited with mAb to ICAM-1. Both the expression of ICAM-1 and the ICAM-1-dependent increase in T lymphocyte adhesion that was induced by IL-4 could be inhibited by preexposure of the fibroblasts to either IL-1 or IL-6, suggesting that multiple cytokines can have both positive and negative effects on human fibroblast ICAM-1 expression and function.

Saliva secretion from the rat submandibular gland after retrograde infusion of radiographic contrast media

Rat submandibular saliva was collected at various times after retrograde infusion of water-soluble (Renografin 60%) or lipid-soluble (Lipiodol UF) radiographic contrast medium. Significant alterations in flow rate occurred following heavy parenchymal filling with both types of contrast media. Occasional changes in protein concentration, lactoperoxidase activity, and K+ levels were also noted. These changes were relatively mild and transient, and gland function had generally returned to normal by one wk after infusion. No alterations in glandular function were detected after infusion of contrast medium to a degree (ductal filling) comparable to that usually employed in clinical sialography.