Inflammation and metabolism gene sets in subcutaneous abdominal adipose tissue are altered 1 hour after exercise in adults with obesity.

Although the health benefits of exercise in adults with obesity are well described, the direct effects of exercise on adipose tissue that may lead to improved metabolic health are poorly understood. The primary aims of this study were to perform an unbiased analysis of the subcutaneous abdominal adipose tissue transcriptomic response to acute exercise in adults with obesity, and to compare the effects of moderate-intensity continuous exercise versus high-intensity interval exercise on this response. Twenty-nine adults with obesity performed a session of either high-intensity interval exercise (HI; 10 × 1 min at 90%HRpeak, 1 min recovery between intervals; n = 14) or moderate-intensity continuous exercise (MI; 45 min at 70%HRpeak; n = 15). Groups were well matched for BMI (HI 33 ± 3 vs. MI 33 ± 4 kg/m2), sex (HI: 9 women vs. MI: 10 women), and age (HI: 32 ± 6 vs. MI: 29 ± 5). Subcutaneous adipose tissue was collected before and 1 h after the session of HI or MI, and samples were processed for RNA sequencing. Gene set enrichment analysis revealed 7 of 21 gene sets enriched postexercise overlapped between HI and MI. Interestingly, both HI and MI upregulated gene sets involved in inflammation (IL6-JAK-STAT3 signaling, allograft rejection, TNFα signaling via NFκB, and inflammatory response; FDR q value < 0.25). Exercise also downregulated adipogenic and oxidative metabolism gene sets in both groups. Overall, these data suggest genes involved in subcutaneous adipose tissue metabolism and inflammation may be an important part of the initial response after a session of exercise.NEW & NOTEWORTHY This study compared the effects of a single session of high-intensity interval exercise versus moderate-intensity continuous exercise on transcriptional changes in subcutaneous abdominal adipose tissue collected from adults with obesity. Our novel findings indicate exercise upregulated inflammation-related gene sets, while it downregulated metabolism-related gene sets - after both high-intensity and moderate-intensity exercise. These data suggest exercise can alter the adipose tissue transcriptome 1 h after exercise in ways that may impact inflammation and metabolism.

A Study Looking at the Teaching of Peripheral Arterial Disease to Medical Personnel in Nepal: How well are we doing and how might we be able to improve?

Background There is currently no data showing the prevalence of peripheral arterial disease in Nepal, although they have a high incidence of risk factors in their population such as diabetes, hypertension, and high volume of smoke inhalation. Objective To quantify a gap in medical education curriculum in Nepal as it pertains to medical trainees that have a lack of exposure to peripheral arterial disease (PAD) in a clinical setting as well as improve lecture quality on peripheral arterial disease. Method A survey was sent out to 615 medical trainees in Nepal with a survey completion rate of 44%. The results indicate that both medical students and intern doctors feel most confident in their ability to diagnose peripheral arterial disease and comfortable ordering a workup for peripheral arterial disease when their education includes both a dedicated lecture and care of a patient. Result The self-reported ability to diagnose peripheral arterial disease increased in medical students from 21.9% in the lecture only group to 44.4% in the group who had both lecture and cared for a patient. The current curriculum at the Kathmandu University School of Medical Sciences only allows two hours in the medical school to cover all vascular topics and is taught with a traditional PowerPoint method. Conclusion To improve this area of curriculum, we recommend increasing the allotted time for lectures as well as demonstrate on live patients the evaluation for peripheral arterial disease.

The anti-viral dynamin family member MxB participates in mitochondrial integrity.

The membrane deforming dynamin family members MxA and MxB are large GTPases that convey resistance to a variety of infectious viruses. During viral infection, Mx proteins are known to show markedly increased expression via an interferon-responsive promoter to associate with nuclear pores. In this study we report that MxB is an inner mitochondrial membrane GTPase that plays an important role in the morphology and function of this organelle. Expression of mutant MxB or siRNA knockdown of MxB leads to fragmented mitochondria with disrupted inner membranes that are unable to maintain a proton gradient, while expelling their nucleoid-based genome into the cytoplasm. These findings implicate a dynamin family member in mitochondrial-based changes frequently observed during an interferon-based, anti-viral response.

Effects of low-intensity electrical stimulation and adipose derived stem cells transplantation on the time-domain analysis-based electromyographic signals in dogs with SCI.

INTRODUCTION: The application of low-intensity electrical stimulation (LIES) to neural tissue increases neurochemical factors responsible for regeneration as nerve growth factor. Stem cell (SC) therapy for patients with Spinal cord injury (SCI) promote some increase functional improvement. OBJECTIVE: Investigate the electromyographic response in paraplegic dogs undergoing LIES and SC transplantation. METHODS: 27 dogs paraplegics with SCI were divided into three groups with different types of therapy. GADSC: two SC transplants (n = 9); GLIES: LIES (n = 8); GCOMB: two SC transplants and LIES (n = 10). Adipose derived mesenchymal stem cells (ADSCs) were transplanted by lumbar puncture in the amount of 1.2 × 106 cells/50 µL. Acupuncture needles positioned in the interspinous space were used for stimulation. The electrical stimulation was applied with a mean voltage ∼30 mV and four consecutive modulated frequencies (5 Hz, 10 Hz, 15 Hz and 20 Hz) within 5 min each. The patients motor performance was evaluated before (Pre) the procedure and after 30 (Post30) and 60 (Post60) days, from electromyography root mean square (EMGRMS) registered with subcutaneous electrodes in the vastus lateralis muscle, while the animals were in quadrupedal position. RESULTS: All three groups showed a significant intra-group increase of EMGRMS (Pre vs. Post30 or Pre vs. Post60). However, there were no statistically significant differences between Post30 and Post60. The inter-group test (GADSC X GLIES X GCOMB) did not present significance when compared the instants Pre (p = 0.34), Post30 (p = 0.78) and Post60 (p = 0.64). CONCLUSION: Some dogs recovered motor activity, expressed by the EMGRMS, in all groups, in pre vs. post (30 or 60 days) comparisons.

Mechanomyography signals in spastic muscle and the correlation with the modified Ashworth scale.

The modified Ashworth scale (MAS) is the most widely used measurement technique to assess levels of spasticity. In MAS, the evaluator graduates spasticity considering his/her subjective analysis of the muscular endurance during passive stretching. Therefore, it is a subjective scale. Mechanomyography (MMG) allows registering the vibrations generated by muscle contraction and stretching events that propagate through the tissue until the surface of the skin. With this in mind, this study aimed to investigate possible correlations between MMG signal and muscle spasticity levels determined by MAS. We evaluated 34 limbs considered spastic by MAS, including upper and lower limbs of 22 individuals of both sexes. Simultaneously, the MMG signals of the spastic muscle group (agonists) were acquired. The features investigated involved, in the time domain, the median energy (MMGME) of the MMG Z-axis (perpendicular to the muscle fibers) and, in the frequency domain, the median frequency (MMGmf). The Kruskal-Wallis test (p<;0.001) determined that there were significant differences between intergroup MAS spasticity levels for MMGme. There was a high linear correlation between the MMGme and MAS (R2=0.9557) and also a high correlation as indicated by Spearman test (ρ=0.9856; p<;0.001). In spectral analysis, the Kruskal-Wallis test (p = 0.0059) showed that MMGmf did not present significant differences between MAS spasticity levels. There was moderate linear correlation between MAS and MMGmf (R2=0.4883 and Spearman test [ρ = 0.4590; p <; 0.001]). Between the two investigated features, we conclude that the median energy is the most viable feature to evaluate spasticity due to strong correlations with the MAS.

Increased expression of the large GTPase dynamin 2 potentiates metastatic migration and invasion of pancreatic ductal carcinoma.

Pancreatic ductal tumors invade local parenchyma and metastasize to distant organs. Src-mediated tyrosine kinase signaling pathways promote pancreatic ductal adenocarcinoma (PDAC) metastasis, though the molecular mechanisms supporting this invasive process are poorly understood and represent important and novel therapeutic targets. The large GTPase Dynamin 2 (Dyn2), a Src-kinase substrate, regulates membrane-cytoskeletal dynamics although it is yet to be defined if it contributes to tumor cell migration and invasion. Therefore, the goal of this study was to test if Dyn2 is upregulated in human pancreatic tumors and to define its role in cell migration and metastatic invasion using in vitro assays and nude mouse models. Histological analysis showed that 81% of 85 patients had elevated Dyn2 in PDAC. To test if Dyn2 overexpression alters metastatic properties of human pancreatic tumor cells, stable clones of BxPC-3 cells overexpressing either wild-type Dyn2 or a phosphorylation-deficient mutant Dyn2Y(231/597)F known to attenuate Dyn2 function, were generated and analyzed. Importantly, tumor cells overexpressing Dyn2 protruded lamellipodia at twice the rate, migrated faster (180%) and farther (2.5-fold greater distance) on glass and through transwell chambers (2-3-fold more cells through the filter) compared with cells expressing Dyn2Y(231/597)F or vector alone. Further, depletion of Dyn2 and dynamin inhibitors Myristyl trimethyl ammonium bromides and Dynasore significantly reduced cell migration, wound healing and invasion in transwell assays compared with controls. To test the metastatic potential conferred by increased Dyn2 expression, the BxPC-3 cell lines were implanted orthotopically into the pancreas of nude mice. Cells expressing Dyn2-green fluorescent protein exhibited a threefold increase in large distal tumors compared with cells expressing Dyn2Y(231/597)F or vector alone. Finally, histological analysis revealed that Dyn2 is upregulated in 60% of human metastatic pancreatic tumors. These findings are the first to implicate dynamin in any neoplastic condition and to directly demonstrate a role for this mechanoenzyme in invasive cell migration.

Changes in T2 relaxation times associated with maturation of the human intervertebral disk.

BACKGROUND AND PURPOSE: By calculating T2 relaxation times for intervertebral disks, we tested the hypothesis that disk water concentration increases between the first and second decades of life. MATERIALS AND METHODS: In subjects younger than 10 years old (group 1) and subjects between 19 and 20 years old (group 2), a sagittal MR image of the lumbar spine was obtained with a modified 3D fast spin-echo (FSE) multi-echo sequence. T2 relaxation times for each voxel were calculated by fitting a logarithmic regression to the signal intensity in images at 16 different echo times. T2 times were averaged for each spinal disk in each group and differences tested for statistical significance by analysis of variance (ANOVA). T2 times along the vertical axis of the disk at the midline were plotted and inspected for evidence of a central lower signal intensity region (CLSIR) in the 2 groups. We tested the differences between groups for significance with the Student t test. RESULTS: Maps of T2 relaxation times showed different patterns in groups 1 and 2. The mean T2 relaxation times in each disk level in group 1 ranged from 74-95 ms and in group 2, from 91-119 ms. Differences between the 2 groups were significant (P<.001, ANOVA, P=.0002, Student t test of means); differences between levels were not. In group 2, development of a CLSIR was significantly more common than in group 1 (P=.0001, Student t test). CONCLUSIONS: T2 increases in the intervertebral disk between the first and second decades of life.

The large GTPase dynamin regulates actin comet formation and movement in living cells.

The large GTPase dynamin (Dyn2) has been demonstrated by us and others to interact with several different actin-binding proteins. To define how Dyn2 might participate in actin dynamics in livings cells we have expressed green fluorescent protein (GFP)-tagged Dyn2 in cultured cells and observed labeling of comet-like vesicles and macropinosomes. The comet structures progressed with a constant velocity and were reminiscent of actin comets associated with motile vesicles in cells expressing type I phosphatidylinositol phosphate 5-kinases. Based on these observations we sought to determine whether Dyn2 is an integral component of actin comets. Cells expressing type I phosphatidylinositol phosphate 5-kinase and Dyn2-GFP revealed a prominent colocalization of Dyn2 and actin in comet structures. Interestingly, comet formation and motility were normal in cells expressing wild-type Dyn2-GFP but altered markedly in Dyn2 mutant-expressing cells. Dyn2K44A-GFP mutant cells displayed a significant reduction in comet number, length, velocity, and efficiency of movement. In contrast, comets in cells expressing Dyn2DeltaPRD-GFP appeared dark and did not incorporate the mutant Dyn2 protein, indicating that the proline-rich domain (PRD) is required for Dyn2 recruitment. Further, these comets were significantly longer and slower than those in control cells. These findings demonstrate a role for Dyn2 in actin-based vesicle motility.

Complications and patient satisfaction following expander/implant breast reconstruction with and without radiotherapy.

PURPOSE: To compare the rates of complications and patient satisfaction among breast cancer patients treated with mastectomy and tissue expander/implant reconstruction with and without radiotherapy. METHODS AND MATERIALS: As part of the Michigan Breast Reconstruction Outcome Study (MBROS), breast cancer patients undergoing mastectomy with reconstruction were prospectively evaluated with respect to complications, general patient satisfaction with reconstruction, and esthetic satisfaction. Included in this study was a cohort of women who underwent breast reconstruction using an expander/implant (E/I). A subset of these patients also received radiotherapy (RT). At 1 and 2 years postoperatively, a survey was administered which included 7 items assessing both general satisfaction with their reconstruction and esthetic satisfaction. Complication data were also obtained at the same time points using hospital chart review. Radiotherapy patients identified in the University of Michigan Radiation Oncology database that underwent expander/implant reconstruction but not enrolled in the MBROS study were also added to the analysis. RESULTS: Eighty-one patients underwent mastectomy and E/I reconstruction. Nineteen patients received RT and 62 underwent reconstruction without RT. The median dose delivered to the reconstructed breast/chest wall, including boost, was 60.4 Gy (range, 50.0-66.0 Gy) in 1.8- to 2.0-Gy fractions. With a median follow-up of 31 months from the date of surgery, complications occurred in 68% (13/19) of the RT patients compared to 31% (19/62) in the no RT group (p = 0.006). Twelve of 81 patients (15%) had a breast reconstruction failure. Reconstruction failure was significantly associated with experiencing a complication (p = 0.0001) and the use of radiotherapy (p = 0.005). The observed reconstruction failure rates were 37% (7/19) and 8% (5/62) for patients treated with and without radiotherapy, respectively. Tamoxifen was associated with a borderline risk of complications (p = 0.07) and a significant risk of reconstruction failure (p = 0.01). Sixty-six patients of the study group completed the satisfaction survey; 15 patients did not. To offset potential bias for patients not completing the survey, we analyzed satisfaction data assuming "dissatisfaction" scores for surveys not completed. In the analysis of patients with unilateral E/I placement, reconstruction failure was significantly associated with a lower general satisfaction (p = 0.03). Ten percent of patients experiencing a reconstruction failure were generally satisfied compared to 23% who completed E/I reconstruction. In addition, tamoxifen use was associated with a significantly decreased esthetic satisfaction (p = 0.03). Radiotherapy was not associated with significantly decreased general or esthetic satisfaction. CONCLUSION: Irradiated patients had a higher rate of expander/implant reconstruction failure and complications than nonirradiated patients. Despite these differences, our pilot data suggest that both general satisfaction and patient esthetic satisfaction were not significantly different following radiotherapy compared to patients who did not receive RT. Although statistical power was limited in the present study and larger patient numbers are needed to validate these results, this study suggests comparable patient assessment of cosmetic outcome with or without radiotherapy in women who successfully complete expander/implant reconstruction.

Regulated interactions between dynamin and the actin-binding protein cortactin modulate cell shape.

The dynamin family of large GTPases has been implicated in the formation of nascent vesicles in both the endocytic and secretory pathways. It is believed that dynamin interacts with a variety of cellular proteins to constrict membranes. The actin cytoskeleton has also been implicated in altering membrane shape and form during cell migration, endocytosis, and secretion and has been postulated to work synergistically with dynamin and coat proteins in several of these important processes. We have observed that the cytoplasmic distribution of dynamin changes dramatically in fibroblasts that have been stimulated to undergo migration with a motagen/hormone. In quiescent cells, dynamin 2 (Dyn 2) associates predominantly with clathrin-coated vesicles at the plasma membrane and the Golgi apparatus. Upon treatment with PDGF to induce cell migration, dynamin becomes markedly associated with membrane ruffles and lamellipodia. Biochemical and morphological studies using antibodies and GFP-tagged dynamin demonstrate an interaction with cortactin. Cortactin is an actin-binding protein that contains a well defined SH3 domain. Using a variety of biochemical methods we demonstrate that the cortactin-SH3 domain associates with the proline-rich domain (PRD) of dynamin. Functional studies that express wild-type and mutant forms of dynamin and/or cortactin in living cells support these in vitro observations and demonstrate that an increased expression of cortactin leads to a significant recruitment of endogenous or expressed dynamin into the cell ruffle. Further, expression of a cortactin protein lacking the interactive SH3 domain (CortDeltaSH3) significantly reduces dynamin localization to the ruffle. Accordingly, transfected cells expressing Dyn 2 lacking the PRD (Dyn 2(aa)DeltaPRD) sequester little of this protein to the cortactin-rich ruffle. Interestingly, these mutant cells are viable, but display dramatic alterations in morphology. This change in shape appears to be due, in part, to a striking increase in the number of actin stress fibers. These findings provide the first demonstration that dynamin can interact with the actin cytoskeleton to regulate actin reorganization and subsequently cell shape.

Inhibition of radiation-induced apoptosis by dexamethasone in cervical carcinoma cell lines depends upon increased HPV E6/E7.

Through a glucocorticoid-responsive promoter, glucocorticoids can regulate the transcription of the human papillomavirus (HPV) E6 and E7 viral genes which target the tumour suppressor proteins p53 and Rb respectively. In C4-1 cells, the glucocorticoid dexamethasone up-regulated HPV E6/E7 mRNA and decreased radiation-induced apoptosis. In contrast, dexamethasone had no effect on apoptosis of cells that either lack the HPV genome (C33-a) or in which HPV E6/E7 transcription is repressed by dexamethasone (SW756). Irradiated C4-1 cells showed increased p53 expression, while dexamethasone treatment prior to irradiation decreased p53 protein expression. In addition, p21 mRNA was regulated by irradiation and dexamethasone in accordance with the observed changes in p53. Overall, glucocorticoids decreased radiation-induced apoptosis in cervical carcinoma cells which exhibit increased HPV E6/E7 transcription and decreased p53 expression. Therefore, in HPV-infected cervical epithelial cells, p53-dependent apoptosis appears to depend upon the levels of HPV E6/E7 mRNA.

Disruption of Golgi structure and function in mammalian cells expressing a mutant dynamin.

The large GTPase dynamin is a mechanoenzyme that participates in the scission of nascent vesicles from the plasma membrane. Recently, dynamin has been demonstrated to associate with the Golgi apparatus in mammalian cells by morphological and biochemical methods. Additional studies using a well characterized, cell-free assay have supported these findings by demonstrating a requirement for dynamin function in the formation of clathrin-coated, and non-clathrin-coated vesicles from the trans-Golgi network (TGN). In this study, we tested if dynamin participates in Golgi function in living cells through the expression of a dominant negative dynamin construct (K44A). Cells co-transfected to express this mutant dynamin and a GFP-tagged Golgi resident protein (TGN38) exhibit Golgi structures that are either compacted, vesiculated, or tubulated. Electron microscopy of these mutant cells revealed large numbers of Golgi stacks comprised of highly tubulated cisternae and an extraordinary number of coated vesicle buds. Cells expressing mutant dynamin and GFP-tagged VSVG demonstrated a marked retention (8- to 11-fold) of the nascent viral G-protein in the Golgi compared to control cells. These observations in living cells are consistent with previous morphological and in vitro studies demonstrating a role for dynamin in the formation of secretory vesicles from the TGN.

The dynamin-like protein DLP1 is essential for normal distribution and morphology of the endoplasmic reticulum and mitochondria in mammalian cells.

The dynamin family of large GTPases has been implicated in vesicle formation from both the plasma membrane and various intracellular membrane compartments. The dynamin-like protein DLP1, recently identified in mammalian tissues, has been shown to be more closely related to the yeast dynamin proteins Vps1p and Dnm1p (42%) than to the mammalian dynamins (37%). Furthermore, DLP1 has been shown to associate with punctate vesicles that are in intimate contact with microtubules and the endoplasmic reticulum (ER) in mammalian cells. To define the function of DLP1, we have transiently expressed both wild-type and two mutant DLP1 proteins, tagged with green fluorescent protein, in cultured mammalian cells. Point mutations in the GTP-binding domain of DLP1 (K38A and D231N) dramatically changed its intracellular distribution from punctate vesicular structures to either an aggregated or a diffuse pattern. Strikingly, cells expressing DLP1 mutants or microinjected with DLP1 antibodies showed a marked reduction in ER fluorescence and a significant aggregation and tubulation of mitochondria by immunofluorescence microscopy. Consistent with these observations, electron microscopy of DLP1 mutant cells revealed a striking and quantitative change in the distribution and morphology of mitochondria and the ER. These data support very recent studies by other authors implicating DLP1 in the maintenance of mitochondrial morphology in both yeast and mammalian cells. Furthermore, this study provides the first evidence that a dynamin family member participates in the maintenance and distribution of the ER. How DLP1 might participate in the biogenesis of two presumably distinct organelle systems is discussed.

Cryptosporidium parvum is cytopathic for cultured human biliary epithelia via an apoptotic mechanism.

While the clinical features of sclerosing cholangitis secondary to opportunistic infections of the biliary tree in patients with acquired immunodeficiency syndrome (AIDS) are well known, the mechanisms by which microbial pathogens such as Cryptosporidium parvum associated with this syndrome actually cause disease are obscure. We established an in vitro model of biliary cryptosporidiosis employing a human biliary epithelial cell line. Using morphological and biochemical techniques, we examined the interaction of C. parvum with cultured human cholangiocytes. When the apical plasma membrane of polarized, confluent monolayers of human biliary epithelial cells was exposed to C. parvum oocysts that had been excysted in vitro, sporozoites attached to and invaded the cells in a time-, dose-, temperature-, and pH-dependent manner. The infectious process was both plasma membrane domain- and cell-specific, because no attachment or invasion occurred when the basolateral membrane of cholangiocytes was exposed to the parasite, or when a human hepatocyte cell line (HepG2) was used. Time-lapse video microscopy and scanning electron microscopy (SEM) showed that sporozoite attachment was rapid, involved extensive cholangiocyte membrane ruffling, and culminated in parasite penetration into a tight-fitting vacuole formed by invagination of the plasma membrane similar to those found in naturally occurring infection in vivo. Transmission electron microscopy (TEM) showed that C. parvum organisms formed parasitophorus vacuoles and were able to undergo a complete reproductive cycle, forming both asexual and sexual reproductive stages. Unexpectedly, direct cytopathic effects were noted in infected monolayers, with widespread programmed cell death (i.e., apoptosis) of biliary epithelial cells as assessed both morphologically and biochemically beginning within hours after exposure to the organism. The novel finding of specific cytopathic invasion of biliary epithelia by C. parvum may be relevant to the pathogenesis and possible therapy of the secondary sclerosing cholangitis seen in AIDS patients with biliary cryptosporidiosis.

Multiple forms of endonuclease activity linked with radiation induced apoptosis in C4-1 cervical carcinoma cells.

Irradiation of C4-1 cervical carcinoma cells induced apoptosis, as determined by their morphology and the presence of oligonucleosomal DNA fragmentation, with the formation of 5'- P and 3'-OH termini. Extracts of nuclear proteins from both control and irradiated cells possessed similar metallodependent endonucleolytic activity which cleaved target plasmid DNA with the same specificity as that found in apoptotic cells. Fractionation of the nuclear extracts revealed that the predominant endonuclease activity of unirradiated cells was a protein of approximately 40 kDa. After irradiation, the predominant activity was found to be associated with a 70 kDa fraction, with a reduction in the 40 kDa form. The activity of each endonuclease was found to be Ca2+ and Mg2+ dependent. It is proposed that the changes in molecular weight observed for these enzymes may be linked to the final step in apoptosis execution, irreversible chromatin fragmentation, and thus offer a potentially novel target for manipulating the effector pathway of apoptosis in these cells.

Dynamin-mediated internalization of caveolae.

The dynamins comprise an expanding family of ubiquitously expressed 100-kD GTPases that have been implicated in severing clathrin-coated pits during receptor-mediated endocytosis. Currently, it is unclear whether the different dynamin isoforms perform redundant functions or participate in distinct endocytic processes. To define the function of dynamin II in mammalian epithelial cells, we have generated and characterized peptide-specific antibodies to domains that either are unique to this isoform or conserved within the dynamin family. When microinjected into cultured hepatocytes these affinity-purified antibodies inhibited clathrin-mediated endocytosis and induced the formation of long plasmalemmal invaginations with attached clathrin-coated pits. In addition, clusters of distinct, nonclathrin-coated, flask-shaped invaginations resembling caveolae accumulated at the plasma membrane of antibody-injected cells. In support of this, caveola-mediated endocytosis of labeled cholera toxin B was inhibited in antibody-injected hepatocytes. Using immunoisolation techniques an anti-dynamin antibody isolated caveolar membranes directly from a hepatocyte postnuclear membrane fraction. Finally, double label immunofluorescence microscopy revealed a striking colocalization between dynamin and the caveolar coat protein caveolin. Thus, functional in vivo studies as well as ultrastructural and biochemical analyses indicate that dynamin mediates both clathrin-dependent endocytosis and the internalization of caveolae in mammalian cells.

Ethanol-induced alterations of the microtubule cytoskeleton in hepatocytes.

Ethanol has been predicted to alter vesicle-based protein traffic in hepatocytes, in part, via a disruption of the microtubule (MT) cytoskeleton. However, information on the effects of chronic ethanol exposure on MT function in vivo is sparse. Therefore the goal of this study was to test for ethanol-induced changes in rat liver tubulin expression, assembly, and cellular organization, using molecular, biochemical and morphological methods. The results of this study showed that tubulin mRNA and protein levels were not altered by ethanol. Tubulin, isolated from control and ethanol-fed rats, showed similar polymerization characteristics as assessed by calculation of the critical concentration for assembly and morphological structure. In contrast, the total amount of assembly-competent tubulin was reduced in livers from ethanol-fed rats compared with control rats when assessed by quantitative immunoblot analysis using a tubulin antibody. In addition, we observed that MT regrowth and organization in cultured hepatocytes treated with cold and nocodazole was markedly impaired by chronic ethanol exposure. In summary, these results indicate that tubulin levels in liver are not reduced by ethanol exposure. While there is a substantial amount of tubulin protein capable of assembling into functional MTs in ethanol-damaged livers, a marked portion of this tubulin is polymerization incompetent. This may explain why these hepatocytes exhibit a reduced number of MTs with an altered organization.

Ultrastructural study of human herpesvirus-7 replication in tissue culture.

Human herpesvirus 7 (HHV-7) was grown in a CD4+ lymphoblastic cell line (SupT1) and in cord blood mononuclear cells (CBMC). Virus infection was demonstrated by immunohistology with positive control sera, with monoclonal antibodies and by in situ hybridization for viral DNA. Cytopathic effects following HHV-7 infection generally resemble those after HHV-6 infection but are less pronounced. The ultrastructural appearance of HHV-7 and the replicative stages were similar to those described by Kramarsky and Sander for HHV-6. There were some minor discrepancies, including quite an extensive and space-filling tegument, a slightly different structure of the nucleoid, the frequent finding of nucleocapsids without any visible core and apparently scarce or delicate spikes on the envelope. These differences may suggest HHV-7 rather than HHV-6, but this finding needs confirmation. Mature HHV-7 particles measured 170 nm in diameter, with nucleocapsids of 90-95 nm and a tegument of about 30 nm.

In vitro cytobiological effects of human herpesviruses 6 and 7: immunohistological monitoring of apoptosis, differentiation and cell proliferation.

Two human herpesviruses, HHV-6 and HHV-7, recently identified and closely related, were studied for their influence on cellular apoptosis and proliferation. Infection was monitored by viral DNA--and antigen expression. Apoptosis and cell proliferation were determined by immunocytological techniques and the markers p53, p21WAF/Cip, Bax, Bak, Bcl-2, cyclin D1 and PCNA, and also screened for signal transduction indicators such as c-H-ras, c-fos and raf-1. Cell differentiation and function was monitored by determining cell membrane receptors including Fas and CD specificities, and by ELISA tests for interleukin production. Both HHV-6 and HHV-7 readily infected their target cells, yet virus antigen expression and virus replication were less active in HHV-7 infection. Both viruses also induced GM-CFS production. Cell differentiation in terms of CD receptor expression was more pronounced in HHV-6 than in HHV-7 infection. No differences were found in the activity of signal transduction factors. There were quantitative differences in the activation of p53, Bax, p21WAF and Bcl-2 in HHV 6-infected CBC as compared to HHV-7 infection supporting the apoptosis cycle. CyclinD1 activity remained at lower levels in HHV-7 infected CBC, yet was high in similarly infected transformed SupT1 cells. In contrast, HHV-6 supported rather the p53/p21WAF apoptosis pathway in both untransformed CBC and transformed HSB1 cells. Both herpesviruses, HHV-6 and HHV-7, thus possessed similar biological activities in cultures of non-transformed susceptible cells, although with certain quantitative differences. The data reported here may further support the notion that HHV-7 is less active in inducing apoptosis thus favoring continued cell proliferation. The mechanism by which these viruses interfere with the network control of cell proliferation, differentiation and apoptosis appear more complicated than shown here and therefore afford a more detailed study, including a more sensitive technology than immunohistology.