Epithelial cell shedding and barrier function: a matter of life and death at the small intestinal villus tip

The intestinal epithelium is a critical component of the gut barrier. Composed of a single layer of intestinal epithelial cells (IECs) held together by tight junctions, this delicate structure prevents the transfer of harmful microorganisms, antigens, and toxins from the gut lumen into the circulation. The equilibrium between the rate of apoptosis and shedding of senescent epithelial cells at the villus tip, and the generation of new cells in the crypt, is key to maintaining tissue homeostasis. However, in both localized and systemic inflammation, this balance may be disturbed as a result of pathological IEC shedding. Shedding of IECs from the epithelial monolayer may cause transient gaps or microerosions in the epithelial barrier, resulting in increased intestinal permeability. Although pathological IEC shedding has been observed in mouse models of inflammation and human intestinal conditions such as inflammatory bowel disease, understanding of the underlying mechanisms remains limited. This process may also be an important contributor to systemic and intestinal inflammatory diseases and gut barrier dysfunction in domestic animal species. This review aims to summarize current knowledge about intestinal epithelial cell shedding, its significance in gut barrier dysfunction and host-microbial interactions, and where research in this field is directed.

Simvastatin preserves the ischemic-reperfused myocardium in normocholesterolemic rat hearts

BACKGROUND

Ischemia followed by reperfusion in the presence of polymorphonuclear leukocytes (PMNs) results in cardiac contractile dysfunction as well as cardiomyocyte injury. These deleterious effects are due in large part to endothelial dysfunction leading to the upregulation of cell adhesion molecules and subsequent neutrophil-endothelium interaction. At clinically relevant doses, simvastatin, an HMG-CoA reductase inhibitor, has been shown to lower serum cholesterol levels and normalize endothelial cell function. We wanted to test the effects of simvastatin on neutrophil-mediated cardiac dysfunction in a controlled model of myocardial ischemia-reperfusion.

METHODS AND RESULTS

This study examines the effects of simvastatin in a neutrophil-dependent isolated perfused rat heart model of ischemia (I) (20 minutes) and reperfusion (R) (45 minutes) injury. Administration of simvastatin 25 micrograms/rat improved coronary flow and preserved left ventricular developed pressure (LVDP) and dP/dtmax, indexes of cardiac contractile function. Final LVDP was 95+/-5 mm Hg in I/R hearts perfused with PMNs and simvastatin, compared with 49+/-4 mm Hg in PMN-perfused I/R hearts receiving only vehicle (P<0.001). In addition, simvastatin significantly reduced PMN accumulation in the ischemic myocardium (P<0.01). In PMN-perfused rat hearts after I/R, simvastatin also significantly attenuated P-selectin expression, CD18 upregulation in rat PMNs, and PMN adherence to rat vascular endothelium. Significant, although less potent, effects were obtained with pravastatin.

CONCLUSIONS

These results provide evidence that HMG-CoA reductase inhibitors are potent and effective cardioprotective agents that inhibit leukocyte-endothelial cell interactions and preserve cardiac contractile function and coronary perfusion after myocardial ischemia and reperfusion. Moreover, these effects are unrelated to the cholesterol-lowering action of this agent and appear to be mediated by enhanced endothelial release of NO.

Sperm DNA fragmentation is increased in couples with unexplained recurrent pregnancy loss

Previous studies have indicated that sperm quality may be related to unexplained recurrent pregnancy loss. This study evaluated the degree of sperm DNA fragmentation using the TUNEL assay on sperm from 24 couples with unexplained recurrent pregnancy loss (RPL) compared to sperm from 2 control groups: donors of known fertility and unscreened men from the general population. The percentage of sperm staining positive for DNA fragmentation was increased (p < .001) in the RPL group (38 +/- 4.2) compared to the donor (11.9 +/- 1.0) or general population (22 +/- 2.0) control groups. In the RPL group, no correlation was observed between semen quality parameters and the TUNEL data. These data indicate that some RPL patients have a significant increase of sperm DNA fragmentation, which may be causative of pregnancy loss in some patients.

Characteristics of unsatisfactory shoulder arthroplasties

Failure of shoulder arthroplasty is often defined as a complication or the need for revision, but it may also be viewed as a result that does not meet the expectations of the patient. To enhance our understanding of failed shoulder arthroplasties, we identified the characteristics common to a series of 139 consecutive patients who came to our shoulder consultation service because of dissatisfaction with the result of their shoulder arthroplasty. Primary osteoarthritis (28%) and proximal humeral fractures (26%) were the most common indications for the initial arthroplasty. Seventy-three shoulders (fifty-two percent) had at least one surgery before arthroplasty was performed. Seventy-four percent of the shoulders were stiff, 35% were unstable, and in the total shoulders, 59% of the glenoids were loose. Components were substantially malpositioned in 23%. Forty-two percent of shoulders with a failed hemiarthroplasty had substantial glenoid erosion, and 43% of shoulders that had undergone a hemiarthroplasty for fracture had nonunion of the tuberosities. Patients demonstrated impaired shoulder function; on average, they could perform only 2 of 12 shoulder functions. The rate of revision underestimated the rate of failure, as 23% of arthroplasties did not undergo revision. The challenge of achieving patient satisfaction after arthroplasty may be greater than previously recognized. Many of these unsatisfactory shoulder arthroplasties did not meet the criteria for failure used in previously published series. These observations suggest that greater attention to achieving proper component position, postoperative motion, and in fracture cases, fixation of the tuberosities may lead to increased patient satisfaction after shoulder arthroplasty.

Peroxynitrite inhibits leukocyte-endothelial cell interactions and protects against ischemia-reperfusion injury in rats

Peroxynitrite (ONOO-) anion, formed by the interaction of superoxide with nitric oxide (NO), has previously been implicated as a cytotoxic agent. However, the effects of this free radical species on neutrophil (PMN)-endothelial cell interactions is largely unknown. We investigated the direct actions of ONOO- on PMN adhesion to endothelial cells in vitro and in vivo, as well as the effects of ONOO- on PMN-mediated myocardial ischemia-reperfusion injury. In vitro, peroxynitrite (100-1,000 nM) inhibited the adhesion of rat PMNs to the endothelium of isolated thrombin- or H2O2-stimulated rat mesenteric artery (P < 0.01 vs. thrombin or H2O2 alone). In vivo, in the rat mesentery, thrombin (0.5 U/ml) or N(G)-nitro-L-arginine-methyl ester (50 microM) significantly increased venular leukocyte rolling and adherence, which were also significantly (P < 0.01) attenuated by ONOO (800 nM) accompanied by reduced P-selectin expression on the endothelial cell surface. Isolated perfused rat hearts were subjected to global ischemia and reperfusion with rat PMNs (10(8) cells), which resulted in profound cardiac depression (i.e., a marked reduction in left ventricular developed pressure and maximal rate of development of left ventricular pressure). Infusion of ONOO- reversed the myocardial contractile dysfunction of ischemic-reperfused rat hearts to near baseline levels, and markedly attenuated the accumulation of PMNs in the postischemic heart. The present study provides strong evidence that nanomolar concentrations of ONOO- both inhibit leukocyte-endothelial cell interactions and exert cytoprotective effects in myocardial ischemia-reperfusion injury. Furthermore, our results suggest that the inhibition of P-selectin expression by peroxynitrite is a key mechanism of the modulatory actions of ONOO- on leukocyte-endothelial cell interactions.

Somatic gene editing ameliorates skeletal and cardiac muscle failure in pig and human models of Duchenne muscular dystrophy

Frameshift mutations in the DMD gene, encoding dystrophin, cause Duchenne muscular dystrophy (DMD), leading to terminal muscle and heart failure in patients. Somatic gene editing by sequence-specific nucleases offers new options for restoring the DMD reading frame, resulting in expression of a shortened but largely functional dystrophin protein. Here, we validated this approach in a pig model of DMD lacking exon 52 of DMD (DMDΔ52), as well as in a corresponding patient-derived induced pluripotent stem cell model. In DMDΔ52 pigs1, intramuscular injection of adeno-associated viral vectors of serotype 9 carrying an intein-split Cas9 (ref. 2) and a pair of guide RNAs targeting sequences flanking exon 51 (AAV9-Cas9-gE51) induced expression of a shortened dystrophin (DMDΔ51-52) and improved skeletal muscle function. Moreover, systemic application of AAV9-Cas9-gE51 led to widespread dystrophin expression in muscle, including diaphragm and heart, prolonging survival and reducing arrhythmogenic vulnerability. Similarly, in induced pluripotent stem cell-derived myoblasts and cardiomyocytes of a patient lacking DMDΔ52, AAV6-Cas9-g51-mediated excision of exon 51 restored dystrophin expression and amelioreate skeletal myotube formation as well as abnormal cardiomyocyte Ca2+ handling and arrhythmogenic susceptibility. The ability of Cas9-mediated exon excision to improve DMD pathology in these translational models paves the way for new treatment approaches in patients with this devastating disease.

Inverse relationship between electrode size and lesion size during radiofrequency ablation with active electrode cooling

BACKGROUND

Clinical efficacy has driven the use of larger electrodes (7F, length > or =4 mm) for radiofrequency ablation, which reduces electrogram resolution and causes variability in tissue contact depending on electrode orientation. With active cooling, ablation electrode size may be reduced. The purpose of this study was to examine the effect of electrode length on tissue temperature and lesion size with saline irrigation used for active cooling.

METHODS AND RESULTS

In 11 anesthetized dogs, the thigh muscle was exposed and bathed with heparinized canine blood. A 7F ablation catheter with a 2- or 5-mm irrigated tip electrode was positioned perpendicular or parallel to the thigh muscle. Radiofrequency current was delivered at constant voltage (50 V) for 30 seconds during saline irrigation (20 mL/min) to 148 sites. Tissue temperature at depths of 3.5 and 7 mm and lesion size were measured. In the perpendicular electrode-tissue orientation, radiofrequency applications at 50 V with the 2-mm electrode compared with the 5-mm electrode resulted in lower power at 50 V (26 versus 36 W) but higher tissue temperatures, larger lesion depth (8.0 versus 5.4 mm), and greater diameter (12.4 mm versus 8.4 mm). Also, in the parallel orientation, overall power was lower with the 2-mm electrode (25 versus 33 W), but tissue temperatures were higher and lesions were deeper (7.3 versus 6.9 mm). Lesion diameter was similar (11.1 versus 11.3 mm) for both electrodes.

CONCLUSIONS

The smaller electrode resulted in transmission of a greater fraction of the radiofrequency power to the tissue and resulted in higher tissue temperature, larger lesions, and lower dependency of lesion size on the electrode orientation.

State preservation by repetitive error detection in a superconducting quantum circuit

Quantum computing becomes viable when a quantum state can be protected from environment-induced error. If quantum bits (qubits) are sufficiently reliable, errors are sparse and quantum error correction (QEC) is capable of identifying and correcting them. Adding more qubits improves the preservation of states by guaranteeing that increasingly larger clusters of errors will not cause logical failure-a key requirement for large-scale systems. Using QEC to extend the qubit lifetime remains one of the outstanding experimental challenges in quantum computing. Here we report the protection of classical states from environmental bit-flip errors and demonstrate the suppression of these errors with increasing system size. We use a linear array of nine qubits, which is a natural step towards the two-dimensional surface code QEC scheme, and track errors as they occur by repeatedly performing projective quantum non-demolition parity measurements. Relative to a single physical qubit, we reduce the failure rate in retrieving an input state by a factor of 2.7 when using five of our nine qubits and by a factor of 8.5 when using all nine qubits after eight cycles. Additionally, we tomographically verify preservation of the non-classical Greenberger-Horne-Zeilinger state. The successful suppression of environment-induced errors will motivate further research into the many challenges associated with building a large-scale superconducting quantum computer.

Verbal episodic memory impairment in Alzheimer's disease: a combined structural and functional MRI study

Anatomical and functional MRI images were acquired in a group of healthy elderly subjects (n = 11) and a group of patients diagnosed with probable Alzheimer's disease, from mild to moderate severity (n = 8). During functional sessions, verbal episodic Encoding and Recognition tasks were presented to subjects. Both groups were compared in terms of gray matter volume and cerebral activation. Furthermore, in the AD group, correlations between hippocampal gray matter volume and whole-brain activations were examined. When compared to healthy controls, AD patients presented significant gray matter atrophy as well as reduced activations during Encoding and Recognition in the medial temporal lobes and inferior parietal/superior temporal associative areas. In the same regions, the fMRI activity elicited by the Recognition task was positively correlated with hippocampal gray matter volume. Moreover, an increase of left prefrontal activity during Encoding and Recognition was observed in AD patients relative to controls and was correlated with memory performance. This additional activity elicited by episodic memory processes was not found to correlate with the degree of medial temporal atrophy in our group of patients. Our study shows that function in brain regions critical to episodic memory is altered in AD. During episodic Recognition, these functional changes may closely correlate with the progressive structural changes observed in the hippocampal region.

Platelet aggregation and sphingomyelinase D activity of a purified toxin from the venom of Loxosceles reclusa

A facile and quantitative assay for measuring the activity of sphingomyelinase D in recluse spider venom has been developed using L-alpha-[palmitoyl-1-14C]lysophosphatidylcholine as substrate. This assay avoids the problem of substrate insolubility that occurs when sphingomyelin and other insoluble lipids are used as substrates. This assay has been employed in gel filtration and isoelectric focusing isolation techniques to purify sphingomyelinase D from spider venom. The purified sphingomyelinase exhibits four active enzyme forms in isoelectric focusing with pI values of 8.7, 8.4, 8.2, and 7.8. Each active form when examined in SDS-polyacrylamide gel electrophoresis gave an estimated molecular weight of 32 000. The four active enzyme forms were immunologically cross-reactive with each other as demonstrated with radioimmune assays using an antiserum developed to one of the active forms. Each active form hydrolysed sphingomyelin to release choline and produce N-acylsphingosine phosphate. One of the active enzyme forms was characterized further in dermonecrosis and platelet aggregation measurements. This purified sphingomyelinase D was identified as a poisonous toxin that can developed typical dermonecrotic spider lesions when injected into experimental animals at levels expected to be delivered in a normal bite. Furthermore, the purified toxin acts to aggregate human blood platelets. The toxin-induced platelet aggregation has been related to serotonin release as aggregation occurs, and it has been shown to be inhibited by EDTA over the range of 0.6 yo 3.0 mM EDTA. It is suggested that spider-induced dermonecrosis could result in part from platelet aggregation at and near the site of envenomation.

Growth and phylogenetic properties of novel bacteria belonging to the epsilon subdivision of the Proteobacteria enriched from Alvinella pompejana and deep-sea hydrothermal vents

Recent molecular characterizations of microbial communities from deep-sea hydrothermal sites indicate the predominance of bacteria belonging to the epsilon subdivision of Proteobacteria (epsilon Proteobacteria). Here, we report the first enrichments and characterizations of four epsilon Proteobacteria that are directly associated with Alvinella pompejana, a deep sea hydrothermal vent polychete, or with hydrothermal vent chimney samples. These novel bacteria were moderately thermophilic sulfur-reducing heterotrophs growing on formate as the energy and carbon source. In addition, two of them (Am-H and Ex-18.2) could grow on sulfur lithoautrotrophically using hydrogen as the electron donor. Optimal growth temperatures of the bacteria ranged from 41 to 45 degrees C. Phylogenetic analysis of the small-subunit ribosomal gene of the two heterotrophic bacteria demonstrated 95% similarity to Sulfurospirillum arcachonense, an epsilon Proteobacteria isolated from an oxidized marine surface sediment. The autotrophic bacteria grouped within a deeply branching clade of the epsilon Proteobacteria, to date composed only of uncultured bacteria detected in a sample from a hydrothermal vent along the mid-Atlantic ridge. A molecular survey of various hydrothermal vent environments demonstrated the presence of two of these bacteria (Am-N and Am-H) in more than one geographic location and habitat. These results suggest that certain epsilon Proteobacteria likely fill important niches in the environmental habitats of deep-sea hydrothermal vents, where they contribute to overall carbon and sulfur cycling at moderate thermophilic temperatures.

Direct demonstration of increased expression of Thomsen-Friedenreich (TF) antigen in colonic adenocarcinoma and ulcerative colitis mucin and its concealment in normal mucin

Increased binding of the lectin peanut agglutinin is a common feature in epithelial malignancy and hyperplasia. This may have considerable functional importance in the intestine by allowing interaction between the epithelium and mitogenic lectins of dietary or microbial origin. Peanut agglutinin binds the disaccharide Thomsen-Friedenreich (TF, T or core 1) blood group antigen, Gal beta (1-3) GalNAc alpha-, but is not totally specific for this site. Consequently, there has been controversy about the presence of this structure in colon cancer; studies with anti-TF monoclonal antibodies have failed to detect it. We have examined the presence of TF antigen in colonic mucus glycoprotein (mucin) using endo-alpha-N-acetylgalactosaminidase (O-Glycanase), which specifically catalyzes the hydrolysis of TF antigen from glycoconjugates. Samples of adenocarcinoma, inflammatory bowel disease (ulcerative colitis), and normal mucin were treated with O-glycanase, the liberated disaccharide was separated from the glycoprotein and analyzed using dual CarboPac PA-100 column high performance anion-exchange chromatography coupled with pulsed amperometric detection. O-Glycanase treatment released increased amounts of TF antigen from both colonic adenocarcinoma (8.0 +/- 3.9 ng/micrograms protein, n = 11; P < 0.0001 ANOVA) and ulcerative colitis mucin (3.3 +/- 0.3 ng/micrograms protein, n = 5; P = 0.04) compared with mucin samples from histologically normal mucosa distant from carcinoma (1.5 +/- 1.1 ng/micrograms protein, n = 9). However, after mild acid treatment to remove sialic acids and fucose, releasable TF antigen was increased in all nine of these histologically normal mucin samples (5.5 +/- 2.6 ng/micrograms protein, P < 0.0002). We conclude that TF antigen is an oncofetal antigen which is expressed in colon cancer, but is concealed by further glycosylation (sialylation and/or fucosylation) in the normal colonic mucosa.

A molecularly cloned, pathogenic, neutralization-resistant simian immunodeficiency virus, SIVsmE543-3

An infectious molecular clone of simian immunodeficiency virus SIVsm was derived from a biological isolate obtained late in disease from an immunodeficient rhesus macaque (E543) with SIV-induced encephalitis. The molecularly cloned virus, SIVsmE543-3, replicated well in macaque peripheral blood mononuclear cells and monocyte-derived macrophages and resisted neutralization by heterologous sera which broadly neutralized genetically diverse SIV variants in vitro. SIVsmE543-3 was infectious and induced AIDS when inoculated intravenously into pig-tailed macaques (Macaca nemestrina). Two of four infected macaques developed no measurable SIV-specific antibody and succumbed to a wasting syndrome and SIV-induced meningoencephalitis by 14 and 33 weeks postinfection. The other two macaques developed antibodies reactive in Western blot and virus neutralization assays. One macaque was sacrificed at 1 year postinoculation, and the survivor has evidence of immunodeficiency, characterized by persistently low CD4 lymphocyte subsets in the peripheral blood. Plasma samples from these latter animals neutralized SIVsmE543-3 but with much lower efficiency than neutralization of other related SIV strains, confirming the difficulty by which this molecularly cloned virus is neutralized in vitro. SIVsmE543-3 will provide a valuable reagent for studying SIV-induced encephalitis, mapping determinants of neutralization, and determining the in vivo significance of resistance to neutralization in vitro.

Previtellogenic oocyte growth in salmon: relationships among body growth, plasma insulin-like growth factor-1, estradiol-17beta, follicle-stimulating hormone and expression of ovarian genes for insulin-like growth factors, steroidogenic-acute regulatory protein and receptors for gonadotropins, growth hormone, and somatolactin

Body growth during critical periods is known to be an important factor in determining the age of maturity and fecundity in fish. However, the endocrine mechanisms controlling oogenesis in fish and the effects of growth on this process are poorly understood. In this study interactions between the growth and reproductive systems were examined by monitoring changes in various components of the FSH-ovary axis, plasma insulin-like growth factor 1 (Igf1), and ovarian gene expression in relation to body and previtellogenic oocyte growth in coho salmon. Samples were collected from females during two hypothesized critical periods when growth influences maturation in this species. Body growth during the fall-spring months was strongly related to the degree of oocyte development, with larger fish possessing more advanced oocytes than smaller, slower growing fish. The accumulation of cortical alveoli in the oocytes was associated with increases in plasma and pituitary FSH, plasma estradiol-17beta, and ovarian steroidogenic acute regulatory protein (star) gene expression, whereas ovarian transcripts for growth hormone receptor and somatolactin receptor decreased. As oocytes accumulated lipid droplets, a general increase occurred in plasma Igf1 and components of the FSH-ovary axis, including plasma FSH, estradiol-17beta, and ovarian mRNAs for gonadotropin receptors, star, igf1, and igf2. A consistent positive relationship between plasma Igf1, estradiol-17beta, and pituitary FSH during growth in the spring suggests that these factors are important links in the mechanism by which body growth influences the rate of oocyte development.

Synergism between platelets and neutrophils in provoking cardiac dysfunction after ischemia and reperfusion: role of selectins

BACKGROUND

Neutrophils (PMNs) are known to contribute to both cardiac dysfunction and myocardial necrosis after reperfusion of an ischemic heart. Moreover, platelets are also important blood cells that can aggravate myocardial ischemic injury. This study was designed to test the effects of PMNs and platelets separately and together in provoking cardiac dysfunction in isolated perfused rat hearts after ischemia and reperfusion.

METHODS AND RESULTS

Control rat hearts not subjected to ischemia were perfused without blood cells for 80 minutes. Additional control rat hearts were perfused with 75x106 PMNs, with 100x106 platelets, or with 75x106 PMNs+100x106 platelets over a 5-minute perfusion followed by a 75-minute observation period. No significant reduction in coronary flow, left ventricular developed pressure (LVDP), or the first derivative of LVDP (dP/dtmax) was observed at the end of the observation period in any nonischemic group. Similarly, global ischemia (I) for 20 minutes followed by 45 minutes of reperfusion (R) produced no sustained effects on the final recovery of any of these parameters in any group of hearts perfused in the absence of blood cells. However, I/R hearts perfused with either PMNs or platelets alone exhibited decreases in these variables of 10% to 12% (P<0.05 from control). Furthermore, I/R hearts perfused with both PMNs and platelets exhibited decreases of 50% to 60% in all measurements of cardiac function (P<0.001). These dual-cell-perfused I/R hearts also exhibited marked increases in cardiac myeloperoxidase (MPO) activity, indicating a significant PMN infiltration, and enhanced P-selectin expression on the coronary microvascular endothelium. All cardiodynamic effects as well as MPO accumulation and PMN infiltration were markedly attenuated by a sialyl LewisX-oligosaccharide or a recombinant soluble P-selectin ligand, which inhibits selectin-mediated cell adhesion.

CONCLUSIONS

These results provide evidence that platelets and neutrophils act synergistically in provoking postreperfusion cardiac dysfunction and that this may be largely due to cell-to-cell interactions mediated by P-selectin. These findings may help explain the reperfusion injury phenomenon.

Randomized controlled trial and cost-effectiveness analysis of silver-donating antimicrobial dressings for venous leg ulcers (VULCAN trial)

BACKGROUND

Antimicrobial silver dressings are used beneath graduated compression in the treatment of venous ulceration. There is little information on whether their use is effective. This was a prospective randomized trial and cost-effectiveness analysis of silver-donating versus non-silver low-adherence dressings in the treatment of venous leg ulcers.

METHODS

Patients were randomized between the two types of dressing. The primary outcome measure was complete ulcer healing at 12 weeks. Secondary outcomes included time to healing, quality of life and cost-effectiveness.

RESULTS

A total of 213 patients were recruited. There was no difference between the dressings in the proportion of ulcers healed at 12 weeks (59.6 per cent for silver and 56.7 per cent for control dressings). Mean utility scores for the EuroQol 5D and Short Form 6D were similar in both groups at 1, 3, 6 and 12 months. Compared with the control group the antimicrobial group had an incremental cost of pounds sterling 97.85 and an incremental quality-adjusted life year gain of 0.0002, giving an incremental cost-effectiveness ratio of pounds sterling 489 250 for the antimicrobial dressings.

CONCLUSION

No significant differences were found in either primary or secondary endpoints. There was no evidence to support the routine use of silver-donating dressings beneath compression for venous ulceration.

REGISTRATION NUMBER

ISRCTN 72485131 (http://www.controlled-trials.com).

Altered glycosylation in inflammatory bowel disease: a possible role in cancer development

Ulcerative colitis and Crohn's disease (together known as Inflammatory Bowel Disease or IBD) are both associated with increased risk for colorectal cancer. Although it is conventional to emphasise differences between IBD-associated and sporadic colon cancer, such as a lower rate of Adenomatosis Polyposis Coli mutations and earlier p53 mutations, IBD-associated cancer has a similar dysplasia-cancer sequence to sporadic colon cancer, similar frequencies of major chromosomal abnormalities and of microsatellite instability and similar glycosylation changes. This suggests that IBD-associated colon cancer and sporadic colon cancer might have similar pathogenic mechanisms. Because the normal colon is arguably in a continual state of low-grade inflammation in response to its microbial flora, it is reasonable to suggest that both IBD-associated and sporadic colon cancer may be the consequence of bacteria-induced inflammation. We have speculated that the glycosylation changes might result in recruitment to the mucosa of bacterial and dietary lectins that might otherwise pass harmlessly though the gut lumen. These could then lead to increased inflammation and/or proliferation and thence to ulceration or cancer. The glycosylation changes include increased expression of onco-fetal carbohydrates, such as the galactose-terminated Thomsen-Friedenreich antigen (Gal beta1,3GalNAc alpha-), increased sialylation of terminal structures and reduced sulphation. These changes cannot readily be explained by alterations in glycosyltransferase activity but similar changes can be induced in vitro by alkalinisation of the Golgi lumen. Consequences of these changes may be relevant not only for cell-surface glycoconjugates but also for intracellular glycoconjugates.

Factors related to the oxygen tolerance of anaerobic bacteria

The effect of atmospheric oxygen on the viability of 13 strains of anaerobic bacteria, two strains of facultative bacteria, and one aerobic organism was examined. There were great variations in oxygen tolerance among the bacteria. All facultative bacteria survived more than 72 h of exposure to atmospheric oxygen. The survival time for anaerobes ranged from less than 45 min for Peptostreptococcus anaerobius to more than 72 h for two Clostridium perfringens strains. An effort was made to relate the degree of oxygen tolerance to the activities of superoxide dismutase, catalase, and peroxidases in cell-free extracts of the bacteria. All facultative bacteria and a number of anaerobic bacteria possessed superoxide dismutase. There was a correlation between superoxide dismutase activity and oxygen tolerance, but there were notable exceptions. Polyacrylamide gel electropherograms stained for superoxide dismutase indicated that many of the anaerobic bacteria contained at least two electrophoretically distinct enzymes with superoxide dismutase activity. All facultative bacteria contained peroxidase, whereas none of the anaerobic bacteria possessed measurable amounts of this enzyme. Catalase activity was variable among the bacteria and showed no relationship to oxygen tolerance. The ability of the bacteria to reduce oxygen was also examined and related to enzyme content and oxygen tolerance. In general, organisms that survived for relatively long periods of time in the presence of oxygen but demonstrated little superoxide dismutase activity reduced little oxygen. The effects of medium composition and conditions of growth were examined for their influence on the level of the three enzymes. Bacteria grown on the surface of an enriched blood agar medium generally had more enzyme activity than bacteria grown in a liquid medium. The data indicate that superoxide dismutase activity and oxygen reduction rates are important determinants related to the tolerance of anaerobic bacteria to oxygen.

Recombinant soluble P-selectin glycoprotein ligand-1 protects against myocardial ischemic reperfusion injury in cats

OBJECTIVE

Neutrophils (PMNs) contribute importantly to the tissue injury associated with ischemia and subsequent reperfusion of a vascular bed. The effects of a recombinant soluble human form of P-selectin glycoprotein ligand-1 (rsPSGL.Ig) on PMN-endothelial cell interactions were investigated in a well established model of feline myocardial-ischemia reperfusion injury.

METHODS

Cats were subjected to 90 min of myocardial ischemia followed by 270 min of reperfusion.

RESULTS

Administration of rsPSGL.Ig (1 mg/kg) just prior to reperfusion resulted in a significant reduction in myocardial necrosis compared to that in cats administered a low affinity mutant form of rsPSGL.Ig (1 mg/kg) (16 +/- 3 vs. 42 +/- 7% of area-at-risk, P < 0.01). Cardioprotective effects were confirmed by significant (P < 0.05) reductions in plasma creatine kinase activity in cats treated with rsPSGL.Ig. Inhibition of PMN-endothelial cell interactions was evidenced by a significant attenuation in cardiac myeloperoxidase activity (P < 0.01) and reduced PMN adherence to ischemic-reperfused coronary endothelium (P < 0.001). In addition, rsPSGL.Ig treatment significantly (P < 0.01) preserved endothelium-dependent vasorelaxation in ischemic-reperfused coronary arteries.

CONCLUSION

These results demonstrate that the administration of a recombinant soluble PSGL-1 reduces myocardial reperfusion injury and preserves vascular endothelial function, which is largely the result of reduced PMN-endothelial cell interactions.

Lesch-Nyhan syndrome: rapid detection of heterozygotes by use of hair follicles

A method is described which permits rapid phenotypic diagnosis of the Lesch-Nyhan heterozygote by direct assay of hypoxanthine guanine phosphori-bosyltransferase activity in single hair follicles obtained from the scalp.

Adrenoleukodystrophy: oleic acid lowers fibroblast saturated C22-26 fatty acids

Monounsaturated fatty acids, especially oleic acid (C18:1), decreased the content of saturated very-long-chain fatty acids (VLFA) in cultured skin fibroblasts from patients with adrenoleukodystrophy (ALD) and controls. When confluent ALD fibroblasts were incubated with oleic acid for 5 days in lipid-free medium, which eliminates uptake of exogenous VLFA, the mean cell content of C26:0 was decreased by 33.7 +/- 10.1%. Oleic acid inhibited C26:0 synthesis in ALD fibroblasts by 58% and total fatty acid synthesis by 68 to 78%. Therefore, the elevated C26:0 levels in ALD cells may be lowered by inhibiting fatty acid biosynthesis, and inhibition of saturated VLFA synthesis by oleate may be useful in treating ALD.

Cardioprotective effects of a novel proteasome inhibitor following ischemia and reperfusion in the isolated perfused rat heart

Ischemia followed by reperfusion in the presence of polymorphonuclear leukocytes (PMNs) results in cardiac contractile dysfunction as well as myocardial injury. These effects are due in large part to endothelial dysfunction leading to an upregulation of cell adhesion molecules and subsequent neutrophil induced cardiac injury. The proteasome inhibitor, PS-519, has been shown to attenuate leukocyte-endothelial cell interactions. We tested the effects of PS-519 on neutrophil mediated cardiac dysfunction in ischemia/reperfusion. This study examines the effects of PS-519 in a neutrophil dependent isolated perfused rat heart model of ischemia (I) (20 min) and reperfusion (R) (45 min). Administration of PS-519 (0.01, 0.1, 0.3, 1.0 mg/kg) to I/R hearts perfused with PMNs improved coronary flow, and preserved left ventricular developed pressure (LVDP) and + dP/dt max as indices of cardiac contractile function. At 1.0 mg/kg, PS-519 treated hearts exhibited a final LVDP of 98 +/- 3% of initial compared to 52 +/- 8% in I/R hearts receiving only vehicle (P < 0.001). In addition, PS-519 significantly reduced PMN accumulation in the ischemic myocardium from 25.1 +/- 2.1 PMNs/mm2 in untreated hearts to 7.3 PMNs/mm2, and attenuated P-selectin surface expression on coronary vascular endothelium from 7.1 +/- 0.3% to 1.4 +/- 0.2% (P < 0.01). These results provide evidence that PS-519 is a potent and effective cardioprotective agent that inhibits P-selectin leukocyte-endothelial cell interactions and preserves cardiac contractile function and coronary perfusion following myocardial ischemia and reperfusion.