Fluoroscopic-guided covered metallic stent placement for gastric outlet obstruction and post-operative gastroenterostomy anastomotic stricture

AIM

To evaluate the feasibility and safety of fluoroscopic-guided covered metallic stent placements in providing palliative care for patients with inoperable malignant gastric outlet obstruction.

MATERIALS AND METHODS

Under fluoroscopic guidance, placement of self-expandable, covered stents was attempted in 20 patients with inoperable or recurrent gastric cancer (age range 36-79 years). All patients had inoperable gastric outlet obstruction, 13 with native anatomy and seven with post-operative anatomy (gastrointestinal anastomotic sites). All patients had intolerance to oral alimentation and/or vomiting after ingestion. Success was defined both technically and clinically.

RESULTS

The placement of the stent was technically successful in 18 patients and failed in two patients (technical success: 90%). The cause of the technical failures was an inability to negotiate the guide wire through the obstruction sites in spite of the use of both fluoroscopic and endoscopic guidance. After stent placement, 15 patients were able to ingest at least liquids and had a markedly decreased incidence of vomiting (clinical success: 75%). During the mean follow-up of 6 weeks, there have been no stent reocclusion and no life-threatening complications except migration of two stents in one patient.

CONCLUSION

Fluoroscopically guided covered metallic stent placement appears to be valuable for the palliative treatment of malignant obstruction of gastric outlet and post-operative gastrointestinal anastomoses.

In vitro assessment of the mechanical properties of latex and non-latex orthodontic elastics

The increased incidence of latex allergies has led to the development of non-latex orthodontic products. The purpose of this study was to compare the mechanical properties of latex and non-latex orthodontic elastics. The elastics tested were from 2 manufacturers (GAC and Masel) and made of 2 materials (latex and non-latex). The properties tested included cross-sectional area, breaking force, peak load, peak stress, stiffness, modulus, hysteresis, and 24-hour load relaxation. The data were analyzed with 1-sample t tests, an analysis of variance, and the Fisher PLSD test. Between GAC and Masel, the GAC non-latex elastics had greater breaking forces than did the Masel non-latex elastics. The Masel latex elastics had greater breaking forces than did the Masel non-latex elastics. The GAC non-latex elastics showed more viscoelastic properties than both the GAC latex elastics and the Masel non-latex elastics; however, the Masel elastics were more viscoelastic than the GAC elastics. Forces generated by the elastics decreased over 24 hours to an average load approximating 75% of the manufacturers' values (GAC latex, Masel latex, and Masel non-latex elastics) and to 60% for the GAC non-latex elastics. The mechanical properties of the non-latex elastics were not comparable to those of the latex elastics. Therefore, the clinical choice of elastics should be based on the patient's medical history and the specific mechanical properties of the type of elastic.

Vertebral bone marrow perfusion evaluated with dynamic contrast-enhanced MR imaging: significance of aging and sex

PURPOSE

To investigate blood perfusion of nonfractured, normal-appearing vertebral bodies with regard to age and sex.

MATERIALS AND METHODS

Dynamic magnetic resonance imaging (160 images obtained in 80 seconds) was performed from T10 to L5 in 66 patients. Patients were assigned to three groups: group 1, those 50 years or younger without compression fracture; group 2, those older than 50 years without compression fracture; or group 3, those older than 50 years with compression fracture. Peak enhancement percentage and enhancement slope were determined from the time-intensity curve of normal (nonfractured) vertebral body. Comparisons were made between groups, and the effect of age and sex interaction was analyzed.

RESULTS

Higher peak enhancement percentage was demonstrated for group 1 compared with group 2 (58.21 +/- 44.65 [SD] vs 21.88 +/- 14.77, P <.005). Group 1 women revealed a higher enhancement percentage compared with group 1 men (87.17 +/- 54.13 vs 38.16 +/- 21.69, P <.05), which significantly decreased in those older than 50 years (from 87.17 +/- 54.13 to 17.98 +/- 13.80, P <.005). For men, this decrease in those older than 50 years was not as pronounced (from 38.16 +/- 21.69 to 25.38 +/- 15.43, P >.05). Presence of compression fracture at other levels of the spine (group 3) was not associated with a different enhancement percentage for normal vertebrae.

CONCLUSION

Rate of vertebral bone marrow perfusion revealed a significant decrease in subjects older than 50 years. Women demonstrated a higher marrow perfusion rate than men younger than 50 years and a more marked decrease than men older than 50 years.

The development of the virtual reality system for the treatment of the fears of public speaking

The fear of public speaking is a kind of social phobias. The patients having the fear of public speaking show some symptoms like shame and timidity in the daily personal relationship. They are afraid that the other person would be puzzled, feel insulted, and they also fear that they should be underestimated for their mistakes. For the treatment of the fear of public speaking, the cognitive-behavioral therapy has been generally used. The cognitive-behavioral therapy is the method that makes the patients gradually experience some situations inducing the fears and overcome those at last. Recently, the virtual reality technology has been introduced as an alternative method for providing phobic situations. In this study, we developed the public speaking simulator and the virtual environments for the treatment of the fear of public speaking. The head-mounted display, the head-tracker and the 3 dimensional sound system were used for the immersive virtual environment. The imagery of the virtual environment consists of a seminar room and 8 virtual audiences. The patient will speak in front of these virtual audiences and the therapist can control motions, facial expressions, sounds, and voices of each virtual audience.

Control of pH alters the type of cross-linking produced by 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) treatment of acellular matrix vascular grafts

Carbodiimide cross-linking of bioprosthetic materials has been shown to provide tissue stabilization equivalent to that of glutaraldehyde cross-linking, but without the risk of the release of unreacted or depolymerized cytotoxic reagent after implantation. In this study, the effects of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) treatment on acellularized ovine carotid arteries were studied under two different pH conditions: (i) pH controlled at an optimal value of 5.5; and (ii) a simpler, but industrially significant, uncontrolled pH system. A multimode approach was employed involving biochemical assays, thermomechanical, tensile, and shear mechanical testing, and in vitro enzyme degradation analyses. EDC treatment decreased the hoop tangent modulus of acellular matrix (ACM) arterial grafts measured at 20 kPa of stress regardless of pH control. Extensibility of ACM arterial grafts measured at 20 kPa of stress was reduced after EDC treatment with pH control only. In contrast, shear stiffness of ACM arterial grafts increased to a greater degree under cross-linking without pH control (21 x compared to 14 x with pH control). Thermomechanical analyses revealed that EDC cross-linking with pH control also increased the collagen denaturation temperature of ACM arteries to a greater degree (a rise of 24.3 +/- 0.6 degrees C vs. 21.7 +/- 0.7 degrees C for no pH control), whereas cross-linking without pH control consumed a larger amount of lysine residues after 3 h of treatment. Most interestingly, both EDC treatments were equally effective in stabilizing ACM arteries against multiple degradative enzymes in vitro. The observed differences between EDC treatments under different pH conditions are attributed to differences in the location and types of the exogenous cross-links formed. The absence of pH control may have favored the formation of interfibrillar or intermolecular cross-links in collagen as well as involvement of other extracellular matrix components (proteoglycans and glycosaminoglycans). Furthermore, it may be emphasized that the location or type of cross-links differentially affected the mechanical behavior of treated materials without affecting the increase in resistance to enzymatic degradation.

Phosphatidylinositol 3-kinase, not extracellular signal-regulated kinase, regulates activation of the antioxidant-responsive element in IMR-32 human neuroblastoma cells

The antioxidant-responsive element (ARE) plays an important role in the induction of phase II detoxifying enzymes including NADPH:quinone oxidoreductase (NQO1). We report herein that activation of the human NQO1-ARE (hNQO1-ARE) by tert-butylhydroquinone (tBHQ) is mediated by phosphatidylinositol 3-kinase (PI3-kinase), not extracellular signal-regulated kinase (Erk1/2), in IMR-32 human neuroblastoma cells. Treatment with tBHQ significantly increased NQO1 protein without activation of Erk1/2. In addition, PD 98059 (a selective mitogen-activated kinase/Erk kinase inhibitor) did not inhibit hNQO1-ARE-luciferase expression or NQO1 protein induction by tBHQ. Pretreatment with LY 294002 (a selective PI3-kinase inhibitor), however, inhibited both hNQO1-ARE-luciferase expression and endogenous NQO1 protein induction. In support of a role for PI3-kinase in ARE activation we show that: 1) transfection of IMR-32 cells with constitutively active PI3-kinase selectively activated the ARE in a dose-dependent manner that was completely inhibited by treatment with LY 294002; 2) pretreatment of cells with the PI3-kinase inhibitors, LY 294002 and wortmannin, significantly decreased NF-E2-related factor 2 (Nrf2) nuclear translocation induced by tBHQ; and 3) ARE activation by constitutively active PI3-kinase was blocked completely by dominant negative Nrf2. Taken together, these data clearly show that ARE activation by tBHQ depends on PI3-kinase, which lies upstream of Nrf2.

Depletion of glial cell line-derived neurotrophic factor in substantia nigra neurons of Parkinson's disease brain

The distribution of nerve growth factor (NGF), ciliary neurotrophic factor (CNTF), glial cell line-derived neurotrophic factor (GDNF), brain derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and neurotrophin-4 (NT-4) in substantia nigra pars compacta (SNc) of Parkinson's disease (PD) brains was investigated by immunofluorescence. Cases studied included four 69-77 year old neurologically normal male controls and four 72-79 year old male PD patients. Integrated optical densities (IODs) of immunofluorescence over individual neuromelanin-containing neurons and in areas of neuropil and the number of neurons on H & E stained adjacent sections were quantitated with the use of the BioQuant Image Analyzer. Data were statistically analyzed by ANOVA, including the unpaired two-tailed Student t-test and the Mann-Whitney test. The results showed 55.8% (P<0.0001) dropout of SNc neurons in PD brains compared to age-matched controls. Despite considerable neuronal dropout, immunofluorescent NTFs in the PD brains showed differential reductions that were consistent within the group as compared to age-matched controls: reductions were GDNF, 19.4%/neuron (P<0.0001), 20.2%/neuropil (P<0.0001); CNTF, 11.1%/neuron (P<0.0001), 9.4%/neuropil (P<0.0001); BDNF, 8.6%/neuron (P<0.0001), 2.5%/neuropil. NGF, NT-3 and NT-4 showed no significant differences within surviving neurons or neuropil. Since the depletion of GDNF both within surviving neurons and neuropil was twice as great as that of CNTF and BDNF and since the other NTFs showed no changes, GDNF, of the tested NTFs, is probably the most susceptible and the earliest to decrease in the surviving neurons of SNc. These observations suggest a role for decreased availability of GDNF in the process of SNc neurodegeneration in PD.

Duration of neuronal stretch correlates with functional loss

Postoperative cranial nerve weakness or paralysis is not uncommon in many otolaryngologic surgical procedures. Our study used a rat model to test the hypothesis that the length of time that a nerve is under tension may be an important variable in the amount of postoperative paresis. Forty Sprague-Dawley rats were divided into 4 groups that underwent either a sham operation or a traction injury for 1, 2, or 5 minutes. The traction injury was performed with a vessel loop placed around the sciatic nerve with 50 g of tension. Traction injury for 1 or 2 minutes did not result in any statistical differences in the motor capabilities of the lower limb. However, those animals with a stretch injury for 5 minutes had a significant loss of function (P < 0.01) when compared with all other groups. Histologic examination of nerves harvested on postoperative day 7 showed no evidence of mechanical injury. This study demonstrates that even minimal tension, if maintained for a significant amount of time, may result in postoperative weakness.

Characteristic MR findings of cervical pregnancy

The aim of this study was to define the characteristic MR findings of cervical pregnancy. Twelve patients with cervical pregnancy underwent MRI because of difficulty in the diagnosis by ultrasonography, human chorionic gonadotropin assessment, and other clinical evaluations. The assessment of MRI included size and location of the lesion, margin, MR signal intensity, rim of low-signal intensity, enhancement pattern, appearance of enhancing solid component, parametrial change, endometrial change, pelvic fluid collection, and ovarian change. All cases showed ill-marginated mass with very heterogeneous signal intensity on T2-weighted images, irregular internal high-signal intensities on T1-weighted images, a partial or circumferential rim of low-signal intensity, dense irregular peripheral enhancement and enhancing papillary solid components with accompanying tubular signal voids, and variably increased parametrial vascularities. This heterogeneous hemorrhagic mass with densely enhancing papillary solid components may be the typical MR finding for cervical pregnancy. J. Magn. Reson. Imaging 2001;13:918-922.

A case of intramuscular sparganosis in the sartorius muscle

Intramuscular sparganosis is not common, and its rarity makes it difficult to be distinguished from soft tissue tumors. A case of rare intramuscular sparganosis is reported. A 44-year-old man presented with a painful mass in the left thigh for 8 months, which was initially diagnosed a as soft tissue tumor. Ultrasonography and MRI revealed a multilobulated mass in the sartorius muscle. After the needle biopsy under the guidance of ultrasonography, sparganum was discovered under microscopic examination of the excised tissue. Surgical excision was performed, and a live larva of sparganum was removed. Sparganosis should be considered in the differential diagnosis of soft tissue tumors, especially among Koreans who have frequently ingested mountain water and consumed raw snakes or frogs.

The effect of cilostazol on glucose tolerance and insulin resistance in a rat model of non-insulin dependent diabetes mellitus

BACKGROUND

It has been reported that many peripheral vasodilating drugs might improve insulin resistance. Cilostazol, a antithrombotic agent, increases peripheral blood flow in non-insulin dependent diabetic patients. The effect of cilostazol treatment on insulin resistance in streptozotocin (STZ)-induced non-insulin dependent diabetic Wistar rats was examined.

METHODS

About a half of two-day old neonate siblings were injected intraperitoneally with STZ and maintained for six months, at which time they were compared with age-matched control rats for intraperitoneal glucose tolerance test (IPGTT) and for glucose infusion rate (GINF) in a euglycemic hyperinsulinemic glucose-clamp study. After that, these studies were also performed after feeding rat chow containing cilostazol (100 mg/kg/day) to rats with STZ-induced non-insulin dependent diabetes mellitus for four-weeks and compared with those of age-matched control rats.

RESULTS

In the intraperitoneal glucose tolerance test studies, plasma glucose levels of STZ-induced non-insulin dependent diabetic rats were significantly higher and plasma insulin levels significantly lower than those of age-matched control rats in the age of six months. Glucose infusion rate was lower in STZ-induced non-insulin dependent diabetic rats than those of age-matched control rats. However, after a four-week cilostazol treatment, glucose infusion rate of STZ-induced non-insulin dependent diabetic rats was not significantly different from that of control rats.

CONCLUSION

These findings suggested that cilostazol may improve insulin resistance in STZ-induced non-insulin dependent diabetic rats.

Systemic lupus erythematosus complicated with cerebral venous sinus thrombosis : a report of two cases

A rare manifestation of systemic lupus erythematosus (SLE) is cerebral venous sinus thrombosis (CVST), in which early diagnosis and aggressive therapy are of prime importance for favorable outcome. The pathogenesis of CVST is largely unknown, but it is thought to be caused by cerebral vasculitis, antiphospholipid antibodies or other conditions associated with enhanced coagulability. We describe two cases of SLE with CVST which were not associated with antiphospholipid antibodies. Both cases were treated with immunosuppressants (intravenous methylprednisolone and cyclophosphamide pulse therapy) and anticoagulant drugs (heparin and subsequent maintenance therapy with warfarin). There was a marked improvement of neurologic symptoms with the disappearance of thrombus in a follow-up MRI. The possibility of CVST should be considered in any patients with SLE who show neuropsychiatric manifestations.

Cellular localization and up-regulation of multidrug resistance-associated protein 3 in hepatocytes and cholangiocytes during obstructive cholestasis in rat liver

The hepatic expression of the ATP-dependent conjugate export pump multidrug resistance-associated protein 2 (Mrp2) is diminished in experimentally induced models of cholestasis. In this study we have examined the localization and expression of Mrp3, another member of the multidrug resistance-associated protein family, in normal liver and after obstructive cholestasis in the rat. Indirect immunofluorescence and confocal microscopy were used to determine the tissue localization and Western blot analysis was performed to quantitate the expression. In normal rat liver Mrp3 was found on the basolateral membrane of cholangiocytes and a single layer of hepatocytes surrounding the central vein. Three and 7 days after bile duct ligation Mrp3 expression was significantly increased, predominantly in hepatocytes in the pericentral region. By 14 days all hepatocytes showed basolateral membrane labeling for Mrp3 at a time when apical Mrp2 staining was significantly diminished. Proliferating bile ducts continued to stain positive, although the intensity of staining did not seem to vary. After 14 days Western blot quantitation showed that Mrp3 had increased approximately 30-fold in total liver membranes. Quantitation of Mrp3 in membranes from isolated hepatocytes of livers of sham and common bile duct-ligated (CBDL) animals showed a significant up-regulation beginning at 1 day and continuing to increase through 14 days postligation. This was in contrast to the progressive decrease in Mrp2 protein. Because Mrp3 is capable of transporting toxic bile acids, up-regulation of Mrp3 may compensate for the down-regulation of Mrp2 in obstructive cholestasis.

Cytologic and histologic correlation of atypical glandular cells of undetermined significance

To determine the cytologic and histologic correlation of atypical glandular cells of undetermined significance (AGUS) in Papanicolaou smears, a cytology file from January 1998 to May 1999 was reviewed. Surgical pathology files were searched to determine which patients received subsequent biopsies. One hundred thirty-two patients with AGUS were identified. Corresponding biopsies were available for 82 of these cases. AGUS has been sub-classified into 3 subtypes: 1) AGUS, favor reactive; 2) AGUS, not otherwise specified; and 3) AGUS, favor neoplasia. The pathologic findings for the respective Papanicolaou smears with the diagnosis of each subtype of AGUS through the follow-up period were as follows: benign lesions in 56.1%, 0%, and 1.2%; squamous intraepithelial lesions 2.4%, 0%, and 1.2%; glandular intraepithelial lesions 0%, 0%, and 17.1%; endometrial simple hyperplasia 1.2%, 0%, and 0%; and carcinoma 0%, 9.8%, and 11%, respectively. In conclusion, AGUS, on cervical cytologic screening, was correlated with significant pathologic findings in 41.5% of the patients (37.8% with preinvasive or invasive glandular lesions and 9.6% with combined squamous intraepithelial lesions). It is thought that intensive follow-up studies, including colposcopy, cervical biopsy, and curettage, should be recommended for complete evaluation of AGUS.

Global impact of sdiA amplification revealed by comprehensive gene expression profiling of Escherichia coli

In Escherichia coli the amplification of sdiA, a positive activator of ftsQAZ, genes that are essential for septation, results in mitomycin C resistance. To help us understand this resistance phenotype, genes whose expression was altered by increased sdiA dosage were identified using a DNA microarray-based, comprehensive transcript profiling method. The expression of 62 genes was reduced by more than threefold; of these, 41 are involved in motility and chemotaxis. Moreover, the expression of 75 genes, 36 of which had been previously characterized, was elevated at least threefold. As expected, increased sdiA dosage led to significantly elevated sdiA and 'ddlB-ftsQAZ-lpxC operon expression. Transcription of two genes, uvrY and uvrC, located downstream of sdiA and oriented in the same direction, was elevated about 10-fold, although the intervening gene, yecF, of opposite polarity was unaffected by increased sdiA dosage. Three genes (mioC and gidAB) flanking the replication origin, oriC, were transcribed more often when sdiA dosage was high, as were 12 genes within 1 min of a terminus of replication, terB. Transcription of the acrABDEF genes, mapping in three widely spaced loci, was elevated significantly, while several genes involved in DNA repair and replication (e.g., nei, recN, mioC, and mcrC) were moderately elevated in expression. Such global analysis provides a link between septation and the response to DNA-damaging agents.

Ab initio calculations of electronically excited states of cyano-substituted polyacetylene cations

The transition energies for the lowest energy pi --> pi* electronic excitations are calculated with the complete active space self-consistent field method (CASSCF) and with the complete active space second-order perturbation theory method (CASPT2) for the linear cyano-substituted polyacetylene cations, H-Cn-CN+, n = 4-11, and NC-Cn-CN+, n = 2-10. These systems are models for an important class of interstellar species. We demonstrate the utility of the theoretical calculations in assigning the experimental spectra.

Isolation and phylogeny of new endogenous retroviral sequences belonging to the HERV-F family

A new human endogenous retroviral family (HERV-F) has been identified from human chromosome 7q31.1-q31.3 that was identical to the XA34 cDNA clone isolated from a human glioma cDNA library with an ERV-9 env probe. We investigated pol gene sequences of the HERV-F family from a human monochromosomal DNA panel and analyzed these with HERV-F. The pol gene sequences of the HERV-F family were detected on chromosomes 3, 6, 7, 10, 11, 14, 19, 20, X, and Y as examined by PCR. Thirty-six pol gene sequences identified from the human chromosomes have a high degree of sequence similarity (80-99%) with that of the HERV-F. Phylogenetic analysis of pol gene sequences distinctively showed four groups, indicating that the HERV-F family could be amplified at least four times after the original integration into the human genome or represent integration events separately during hominid evolution. One clone (HFY-3) on chromosome Y shared 100% sequence identity with a clone (HF19-2) on chromosome 19, and a clone (HF20-6) on chromosome 20 suggests either a recent retrotransposition or a chromosomal translocation. The history of endogenous retroviral sequences may contribute to an understanding of evolutionary change in human genomes.

6-hydroxydopamine-induced lesions of dopaminergic neurons alter the function of postsynaptic cholinergic neurons without changing cytoskeletal proteins

The neuropathological hallmarks of many neurodegenerative diseases are intraneuronal inclusions containing cytoskeletal proteins such as neurofilaments in Lewy bodies in Parkinson's disease and tau in neurofibrillary tangles in Alzheimer's disease. Dysfunction in dopaminergic and cholinergic systems also exist in both Alzheimer's disease and Parkinson's disease. Because the primary pathology in Parkinson's disease is localized to the dopaminergic system, we set out to determine if perturbations in cholinergic systems are a consequence of dopaminergic neuron loss. Therefore, following intracerebral microinjections of 6-hydroxydopamine in rats, the activity of cholinergic neurons was measured by hemicholinium binding in cholinergic terminal fields and perturbations in cytoskeletal proteins were examined in dopaminoceptive neurons using immunocytochemistry. The 6-hydroxydopamine injections robustly reduced the number of monoaminergic cell bodies in the lateral midbrain and dramatically decreased dopamine and its major metabolites in dopaminergic projection sites. This treatment increased hemicholinium binding in the prefrontal cortex (200%) and amygdala (284%); however, despite previous reports to the contrary, there were no increases in immunoreactivity for phosphorylated neurofilaments, microtubule-associated protein (MAP) 2, tau or paired helical filament (PHF) tau. This lack of an increase in cytoskeletal proteins was observed following either injections of moderate doses of the toxin directly into the medial forebrain bundle or after high doses were administered intracerebroventricularly. These results suggest that removal of dopaminergic inputs to the forebrain results in hyperactivity of the cholinergic systems but is not sufficient to induce postsynaptic perturbations in cytoskeletal proteins which occur in neurodegenerative diseases.

Microscopic and macroscopic approaches of Cu(II) removal by FSM-16

The removal of Cu(II) by a mesoporous material, FSM-16, was studied using electron paramagnetic resonance (EPR) spectroscopy and surface complexation modeling (SCM). Free copper ions, adsorbed and precipitated Cu(II) species were qualitatively identified by in situ EPR spectroscopy of Cu-FSM-16 suspensions at room temperature and at 77 K. In addition, the adsorbed species was identified as a Cu(II) species with an axial symmetry from an analysis of the EPR spectra of "dry" Cu-FSM-16 at 77 K. On the basis of the EPR results, the removal of Cu(II) as a function of pH under various experimental conditions was successfully simulated by assuming two removal mechanisms such as surface complexation and surface precipitation. In the acidic pH range (< pH 6), free copper ions were predominant, and surface complexed then surface precipitated species became dominant as the pH increased.

Linkage between STAT regulation and Epstein-Barr virus gene expression in tumors

Epstein-Barr virus (EBV) latency gene expression in lymphoblastoid cell lines is regulated by EBNA2. However, the factors regulating viral expression in EBV-associated tumors that do not express EBNA2 are poorly understood. In EBV-associated tumors, EBNA1 and frequently LMP1 are synthesized. We found that an alternative latent membrane protein 1 (LMP1) promoter, L1-TR, located within the terminal repeats is active in both nasopharyngeal carcinoma and Hodgkin's disease tissues. Examination of the L1-TR and the standard ED-L1 LMP1 promoters in electrophoretic mobility shift assays revealed that both promoters contain functional STAT binding sites. Further, both LMP1 promoters responded in reporter assays to activation of JAK-STAT signaling. Cotransfection of JAK1 or v-Src or treatment of cells with the cytokine interleukin-6 upregulated expression from ED-L1 and L1-TR reporter plasmids. Cotransfection of a dominant negative STAT3 beta revealed that STAT3 is likely to be the biologically relevant STAT for EBNA1 Qp and LMP1 L1-TR promoter regulation. In contrast, LMP1 expression from ED-L1 was not abrogated by STAT3 beta, indicating that the two LMP1 promoters are regulated by different STAT family members. Taken together with the previous demonstration of JAK-STAT activation of Qp driven EBNA1 expression, this places two of the EBV genes most commonly expressed in tumors under the control of the same signal transduction pathway. Immunohistochemical analyses of nasopharyngeal carcinoma tumors revealed that STAT3, STAT5, and STAT1 are constitutively activated in these tumors while STAT3 is constitutively activated in the malignant cells of Hodgkin's disease. We hypothesize that chronic or aberrant STAT activation may be both a necessary and predisposing event for EBV-driven tumorigenesis in immunocompetent individuals.

A computer-controlled system for mechanostimulation of tissues in culture: a preliminary study of protein synthesis in the pericardium

During pericardial development or disease, changes in diastolic filling pressure and chamber volumes lead to changes in pericardial stress/strain state. These changes may be transduced into altered cellular synthesis of connective tissue proteins. To study the underlying mechanisms, we have constructed a system in which tissue strips may be subjected to a range of physiologically relevant load-elongation waveforms while being maintained under optimal tissue culture conditions. One sample grip is attached to a 500 g load cell and the other to a linear stepper motor. Load or stroke waveforms and feedback control are achieved under computer control. For preliminary studies, strips of fetal ovine pericardium (127-132 days gestation) and juvenile bovine pericardium (6 months) were subjected to ramp-and-hold loading for 24 hr in culture medium containing tritiated proline. At the end of the experiment, pericardial collagen and elastin were purified biochemically and assessed for tritium content. Preliminary results indicate that loading produced a significant 16% decrease in collagen synthesis (p < 0.02, cpm/mg wet weight) but no change in elastin synthesis. This novel system is a valuable tool for further studies of mechanotransduction in developing, normal, and pathological cardiac tissues.

Imposed state of deformation determines local collagen fibre orientation but not apparent mechanical properties

In a previous study, we have shown that the observed biaxial material behaviour of planar connective tissues is influenced by the sample gripping method. Commonly used suture attachments produced an apparently more compliant and extensible material compared to the same sample with clamped edges. We hypothesized that these differences were due to the imposed collagen fibre constraint under each method. In this study, we have directly compared the collagen fibre orientations which result under both gripping schemes. Small angle light scattering (SALS) was used to determine collagen fibre orientations in square bovine pericardial samples, before and after a 10% equibiaxial stretch. Local fibre distributions were determined at the sample centre and at the grip-sample interface. Resulting scattering patterns were statistically compared using repeated measures ANOVA. After stretch, collagen fibre distributions were identical at the sample centre where deformation is measured--but not at the sample boundaries. Therefore, the central fibre orientation distribution appears to be exclusively determined by the imposed deformation state. However, it is important to note that the loads necessary to achieve a given deformation depended strongly on gripping method. The resulting apparent differences in mechanical properties must be due to the method of load transmission. Indeed, fibres were observed to arc around suture attachment points, suggesting a discontinuous load transfer to the specimen which produced an apparent increase in extensibility and compliance. By contrast, only smooth transitions were observed at the clamped edges. Direct transmission of load from grip-to-grip in clamped samples (away from the sample centre) increased apparent stiffness.