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PubMed2006

Redox regulation of human OGG1 activity in response to cellular oxidative stress.

8-Oxoguanine (8-oxoG), a common and mutagenic form of oxidized guanine in DNA, is eliminated mainly through base excision repair. In human cells its repair is initiated by human OGG1 (hOGG1), an 8-oxoG DNA glycosylase. We investigated the effects of an acute cadmium exposure of human lymphoblastoid cells on the activity of hOGG1. We show that coinciding with alteration of the redox cellular status, the 8-oxoG DNA glycosylase activity of hOGG1 was nearly completely inhibited. However, the hOGG1 activity returned to normal levels once the redox cellular status was normalized. In vitro, the activity of purified hOGG1 was abolished by cadmium and could not be recovered by EDTA. In cells, however, the reversible inactivation of OGG1 activity by cadmium was strictly associated with reversible oxidation of the protein. Moreover, the 8-oxoG DNA glycosylase activity of purified OGG1 and that from crude extracts were modulated by cysteine-modifying agents. Oxidation of OGG1 by the thiol oxidant diamide led to inhibition of the activity and a protein migration pattern similar to that seen in cadmium-treated cells. These results suggest that cadmium inhibits hOGG1 activity mainly by indirect oxidation of critical cysteine residues and that excretion of the metal from the cells leads to normalization of the redox cell status and restoration of an active hOGG1. The results presented here unveil a novel redox-dependent mechanism for the regulation of OGG1 activity.

Cadmium↗
PubMed1995

Adhesion molecule CD18 on polymorphonuclear cells correlates to the lung injury caused by continuous infusion of endotoxin in sheep.

We investigated the mechanisms of increase in the pulmonary vascular permeability, focusing on the changes in the peripheral white blood cell (WBC) counts and the surface expression of CD18 on polymorphonuclear cells (PMNs). Anesthetized sheep with chronic lung lymph fistulas were used in this study. We infused synthetic endotoxin (LPS) at a rate of 10 ng/kg/min (i.v.) continuously for 24 hr. We measured lung lymph flow, lymph-to-plasma protein concentration ratio and WBC counts in blood and lung lymph, and the PMNs' surface expression of CD18 before and at 2, 10 and 24 hr after the start of endotoxin infusion, respectively. CD18 was analyzed by flow cytometry using monoclonal anti-CD18 antibody. We found that the pulmonary vascular permeability increased during 2-4 hr after the start of endotoxin infusion, and returned to the baseline over 10 hr. At time 2 hr period, the number of WBCs in the lung lymph increased, the number of peripheral WBCs, mostly PMNs, decreased and the surface expression of CD18 on the peripheral PMNs was up-regulated. At time 10 and 24 hr, the number of WBCs in lung lymph decreased, the number of peripheral WBCs increased and CD18 expression was down-regulated. These data indicate that up-regulation of CD18 expression promotes the PMN adherence to the pulmonary endothelium, migration into the lung and increases the pulmonary vascular permeability. We conclude that the continuous endotoxin infusion up-regulates CD18, which contributes to the PMN migration into the lung.

Animals↗
PubMed1990

Mechanical characteristics of an upper-extremity external fixator.

Static and fatigue tests of the small Orthofix unilateral external fixator frame and its main components were performed. The use of six pins increased torsional rigidity, but this configuration failed at lower bending loads when compared to the four-pin configuration, reflecting the uneven holding strength of the pin clamp on three pins. The ball joint maximum torsional resistance was reduced by 27.2%, and the maximum bending resistance was decreased by 35.2% after first failure loading of a fatigue test. The strength of the ball joint returned to the normal level after replacement of the cam and bushing with new components. The locking strength of the fixator body telescoping mechanism was high and did not change during repetitive failure loading. Hence, the fixator should be applied under the four-pin configuration, placing pins in the outer slots of the clamps as recommended by the manufacturer. The frame stability is governed by the performance of the ball joint, and its locking cam should be tightened periodically. If the ball joint locking position starts to migrate from its initial position, the cam and bushing should be replaced.

Arm↗
PubMedDate not supplied

Malfunctioning peritoneal dialysis catheter repaired by laparoscopic surgery.

OBJECTIVES: To review peritoneal dialysis catheter failures and to describe a technique of repairing malpositioned catheters. DESIGN: Two prospective case reports utilizing this technique are reported. SETTING: A tertiary care hospital. PATIENTS: Two patients on chronic peritoneal dialysis with malfunctioning catheters. INTERVENTION: Both patients underwent reposition of their malpositioned continuous ambulatory peritoneal dialysis catheters by laparoscopic suture technique. MAIN OUTCOME MEASURES: Outcome was measured by the successful return of adequate peritoneal dialysis. RESULTS: Both case studies show correction of malpositioned catheters with the return of successful peritoneal dialysis. CONCLUSION: The repositioning and suture application of malpositioned Tenckhoff catheters by laparoscopic surgery is a viable technique that can salvage the majority of malpositioned catheters and save the patients additional hospital time and recovery.

Abdominal Muscles↗
PubMed1994

Interleukin-3 administration enhances human monocyte function in vivo.

In addition to its haemopoietic effects, interleukin-3 (IL-3) enhances leucocyte function in vitro. In this study we examined the effects on haematological variables and monocyte function of a single IL-3 infusion in five haematologically normal individuals. There was a rapid fall in circulating monocyte (to 24 +/- 6% of pre-infusion value) and eosinophil numbers (to 3 +/- 2%) with a nadir at 30 min and gradual return to baseline over 6 h. No significant changes in monocyte expression of the adhesion molecules CD11b or L-selectin or of monocyte respiratory burst activity were detected. There was a significant increase in monocyte phagocytosis and killing of Candida after IL-3 infusion: the percentage of monocytes which had ingested Candida increased from 39 +/- 10% to 62 +/- 12% and the total number of Candida killed per 100 monocytes increased from 63 +/- 34 to 210 +/- 59 (P < 0.05 and P < 0.01 respectively). There was no inhibition of neutrophil migration into a 'skin window' site and monocyte migration was moderately enhanced (peak increase of 260 +/- 47%). These results show that IL-3 has significant effects on monocyte function in vivo and could be of use in augmenting host defence mechanisms in immunocompromised patients.

CD11 Antigens↗
PubMed1988

Effect of selenium supplementation on the distribution of selenium in plasma proteins of healthy subjects.

The influence of an increased intake of selenium on the distribution of this element among plasma proteins was studied. 200 micrograms of yeast selenium was given to healthy subjects daily for 8 weeks, and then the subjects refrained from selenium supplementation for 16 weeks. Plasma selenium increased almost two-fold during supplementation, and most of the increase occurred during the first 4-week-period. Plasma glutathione peroxidase activity increased only marginally. At all times studied, most of the selenium in plasma was located in proteins, migrating close to immunoglobulin G on gel filtration. The selenium content of this fraction was only moderately increased after supplementation for 8 weeks, and instead more marked increases occurred in the regions for high-molecular-weight proteins and albumin. This change implied that the distribution of selenium approached that of total protein, and we therefore conclude that most of the increase in plasma selenium occurred via unspecific incorporation of selenium into a wide variety of proteins. Sixteen weeks after the end of supplementation the selenium distribution had essentially returned to that before supplementation.

Adult↗
PubMed1993

Immunological analysis of GLUT4-enriched vesicles. Identification of novel proteins regulated by insulin and diabetes.

In adipocytes and muscle, insulin stimulates the translocation of glucose transporter proteins from an intracellular vesicle pool to the plasma membrane. To study the molecular basis of this process, we used the anti-GLUT4 antibody 1F8 to isolate intracellular vesicles from rat adipocytes that are enriched in the muscle/fat glucose transporter isoform. These vesicles were then used as immunogens to generate monoclonal antibodies against their protein components. We isolated an antibody, 3F8, that recognizes three polypeptides, designated GTV3, migrating in the 36-40-kDa range as analyzed by SDS-polyacrylamide gel electrophoresis and Western blotting. These proteins are enriched in GLUT4-containing vesicles, and the two smallest of the polypeptides recognized by 3F8 translocate to the cell surface in response to insulin. GTV3 proteins are also present in plasma membranes of fat cells and liver as well as in a wide number of tissues, red blood cells being the only exception. In adipocytes from streptozotocin-induced diabetic rats, GTV3 protein levels decrease dramatically and return to normal levels when animals are treated with insulin. The localization of GTV3 in glucose transporter-containing vesicles as well as their wide tissue distribution suggests that these proteins may be involved in vesicle mediated transport and regulated trafficking between membrane compartments.

Adipose Tissue↗
PubMed1995

Regulation of neutrophil adhesion molecules and shedding of Staphylococcus aureus in milk of cortisol- and dexamethasone-treated cows.

The effects of 3 days of glucocorticoid administration on bovine blood neutrophil expression of L-selectin and CD18, and on the health status of mammary glands subclinically infected with Staphylococcus aureus were measured in 9 lactating Holsteins. The experiment was a 3 x 3 Latin square cross-over design, with 3 glucocorticoid treatments switched among groups of 3 cows/treatment during 3 periods. Treatments consisted of a vehicle (control, 10 ml of excipient/cow/d), cortisol (7.5, 15, and 7.5 mg/cow on days 1, 2, and 3, respectively), and dexamethasone (0.04 mg/kg of body weight/cow/d for total daily dosages that ranged from 21.6 to 33.2 mg). Blood samples for immunostaining and flow cytometric analysis of L-selectin and CD18 and leukograms, as well as foremilk samples for determination of S aureus shedding, somatic cell counts, protein and fat percentages, and daily milk yields were collected repeatedly before, during, and after treatment days. Dexamethasone caused a profound, acute, short-lived down-regulation of L-selectin on neutrophils, which correlated in time to leukocytosis, mature and immature neutrophilias, increased shedding of S aureus in infected glands, and onset of high percentages of fat and protein and decreased milk yields. Dexamethasone also caused profound but delayed down-regulation of neutrophil CD18, which reached nadir simultaneously with reappearance of L-selectin-bearing neutrophils, normalized blood neutrophil counts, markedly high foremilk somatic cell counts and protein percentage, decreased S aureus shedding in milk, and finally, expression of clinical mastitis in some infected quarters. Each of these variables had returned to control (vehicle) values by the ninth (and last) sample collection day. Although cortisol treatment also decreased expression of L-selectin and CD18 on neutrophils, dosages used in this study were not sufficient to alter the number of circulating cells or to convert subclinical mammary gland infections to clinical mastitis. These results suggest that mammary gland health status can be altered by sudden exposure of blood neutrophils to glucocorticoids, because these steroid hormones caused profound down-regulation of the adhesion molecules that direct neutrophil margination and migration through the vascular endothelium. The results also reinforce the potential disease risk of treating infected animals with potent synthetic glucocorticoids, such as dexamethasone.

Analysis of Variance↗
PubMedDate not supplied

Biodegradable screw presents as a loose intra-articular body after anterior cruciate ligament reconstruction.

We report a case of intra-articular movement of a broken piece of a poly-L-lactide (PLLA) bioabsorbable interference screw from the femoral tunnel in anterior cruciate ligament (ACL) reconstruction with quadrupled semi-tendinosus and gracilis tendon grafts. Eleven months after initially successful ACL surgery, the patient felt a sudden locking of the knee without associated trauma or injury. The patient experienced pain and swelling episodes after heavy lifting with knee flexion at work, but without symptoms of giving way or locking. On revision arthroscopy, a broken part of a bioabsorbable interference screw was seen in the lateral compartment, which was subsequently removed without incident. The semitendinosus-gracilis graft appeared intact without disruption. After revision surgery, the patient's recovery was uneventful, with return to activity within a few months. This case further shows the problem of biointerference screw breakage in ACL reconstructive surgery and the need to bury the femoral bioabsorbable interference screw on graft fixation.

Absorbable Implants↗
PubMed1997

The leukocyte response to fluid stress.

Leukocyte migration from a hemopoietic pool across marrow endothelium requires active pseudopod formation and adhesion. Leukocytes rarely show pseudopod formation while in circulation. At question then is the mechanism that serves to minimize leukocyte pseudopod formation in the circulation. We tested the hypothesis that fluid shear stress acts to prevent pseudopod formation. When individual human leukocytes (neutrophils, monocytes) spreading on glass surfaces in vitro were subjected to fluid shear stress ( approximately 1 dyn/cm2), an instantaneous retraction of pseudopods was observed. Removal of the fluid shear stress in turn led to the return of pseudopod projection and cell spreading. When steady shear stress was prolonged over several minutes, leukocyte swelling occurs together with an enhanced random motion of cytoplasmic granules and a reduction of cytoplasmic stiffness. The response to shear stress could be suppressed by K+ channel blockers and chelation of external Ca2+. In rat mesentery microvessels after occlusion, circulating leukocytes project pseudopods in free suspension or when attached to the endothelium, even though immediately after occlusion only few pseudopods were present. When flow was restored, pseudopods on adhering leukocytes were retracted and then the cells began to roll and detach from the endothelium. In conclusion, plasma shear stress in the circulation serves to reduce pseudopod projection and adhesion of circulating leukocytes and vice versa reduction of shear stress leads to pseudopod projection and spreading of leukocytes on the endothelium.

Amiloride↗
PubMed1974

The role of microtubules in the movement of pigment granules in teleost melanophores.

When microtubules in teleost melanophores are disrupted with antimitotic agents, colchicine, high hydrostatic pressure, low temperature, and vinblastine, the alignment and movement of the pigment granules in these cells disappear; during recovery, the return of alignment and movement corresponds in both time and space with the repolymerization of microtubules. Furthermore, analysis of nearest neighbor distances in untreated melanophores reveals that pigment granules are closely associated with microtubules. Other structures such as microfilaments, the endoplasmic reticulum, and the cytoplasmic matrix do not appear to be involved. Thus we conclude that microtubules determine the alignment and are essential for the selective movements of the pigment granules in these cells. Investigations of the mechanism of movement show that microtubules are required for both centrifugal and centripetal migrations and that they do not change in number or location during redistribution of pigment. Our results further indicate that microtubules in melanophores behave as semistable organelles as determined by investigation with colchicine and hydrostatic pressure. These observations and others rule out a push-pull mechanism based on the polymerization and depolymerization of microtubules or one which distinguishes two operationally different sets of microtubules. We propose instead that particles move by sliding along a fixed array of microtubules.

Animals↗
PubMed2003

Island-finding ability of marine turtles.

Green turtles (Chelonia mydas) swim from foraging grounds along the Brazilian coast to Ascension Island to nest, over 2200 km distant in the middle of the equatorial Atlantic. To test the hypothesis that turtles use wind-borne cues to locate Ascension Island we found turtles that had just completed nesting and then moved three individuals 50 km northwest (downwind) of the island and three individuals 50 km southeast (upwind). Their subsequent movements were tracked by satellite. Turtles released downwind returned to Ascension Island within 1, 2 and 4 days, respectively. By contrast, those released upwind had far more difficulty in relocating Ascension Island, two eventually returning after 10 and 27 days and the third heading back to Brazil after failing to find its way back to the island. These findings strongly support the hypothesis that wind-borne cues are used by turtles to locate Ascension Island.

Animal Migration↗
PubMed2004

Immunolocalization of CXC chemokine and recruitment of polymorphonuclear leukocytes in the rat molar periodontal tissue after topical application of lipopolysaccharide.

This study investigated the recruitment of polymorphonuclear leukocytes (PMNs) and the immunolocalization of CXC chemokines, including macrophage inflammatory protein-2 (MIP-2) and cytokine-induced neutrophil chemoattractant-2 (CINC-2) in rat periodontal tissue after topical application of lipopolysaccharide (LPS; 5 mg/ml) from Escherichia coli into the rat molar gingival sulcus. In normal periodontal tissues, a small number of MIP-2- and CINC-2-positive cells were seen in junctional epithelium (JE), especially in its coronal half. After topical application of LPS, a prominent increase of MIP-2- and CINC-2-positive JE cells was observed. Almost all JE cells strongly expressed them at day 1 and day 2, and then the number of chemokine-positive cells returned to normal at day 7. Corresponding to these chemokine expressions, LPS application induced a significant increase in the number of PMNs in the sub-JE area from 1 h to 2 days and a significant increase in JE area from 3 h to 5 days, indicating a dynamic flow of PMNs from the sub-JE area into JE. These findings indicated that JE cells produced MIP-2 and CINC-2 in response to LPS stimulation and suggested that MIP-2 and CINC-2 may be responsible for PMN migration toward the periodontal pathogen and may play an important role in the initiation of inflammation and subsequent periodontal tissue destruction.

Administration, Topical↗
PubMed1986

Schistosoma mansoni: dynamics of migration through the vascular system of the mouse.

Autoradiography of compressed mouse tissues has been used to estimate the numbers of 75Se-labelled schistosomula present in different mouse organs. Day 7 parasites extracted from the lungs of donor mice were delivered by injection to the lungs, systemic organs and liver of recipient mice as a discrete pulse. The numbers detected in various locations with time post-injection were then used to analyse the dynamics of intravascular migration. Approximately 98% of cercaria-associated label was lost during the first 14 days of parasite life, two-thirds of this in the first 7 h post-infection. Nevertheless, 99-113% of schistosomula could be detected 30 min post-injection into the locations chosen. The efficiency of the parasite delivery system was 95%. The time required for the number of foci in the lungs to decline to 50%, after injection of parasites via the femoral vein, was 55 h. Adjustment of this data to allow for parasites returning to the lungs after passage round the systemic vasculature gave a value of 30-35 h for the true mean time of lung transit. The distribution of parasites to systemic organs after their exit from the lungs was proportional to the fractional distribution of cardiac output. The probability (P) of a schistosomulum being distributed to splanchnic beds was estimated at 0.32 and its P of being trapped in the hepatic portal distributaries within the liver as 0.72-0.86. On this basis, the entire hepatic portal population of adult schistosomes would be recruited during 2-3 circuits of parasites around the pulmonary--systemic vasculature. The mean transit time of schistosomula through intestinal capillaries was 6.5 h whilst that through other systemic organs combined (muscles, kidneys, brain, etc) was 16 h, considerably more rapid than lung transit. The time taken for schistosomula to pass between organs, in arterial and venous blood, was shown to be less than 30 min in both cases (probably much less).

Animals↗
PubMed1998

Polyamines are required for microtubule formation during gastric mucosal healing.

Polyamines are essential for the repair of gastric and duodenal erosions. Concentrated NaCl (3.4 M) given intragastrically damages the oxyntic gland mucosa and increases the activity of gastric mucosal ornithine decarboxylase (ODC), the first rate-limiting enzyme in polyamine synthesis. The nature of the process of restitution of damaged mucosa is not well known, except that cell migration and the actin cytoskeleton play a prominent role. Microtubules are cytoskeletal components essential for cell migration. The present investigation determines the relationship between polyamines, the distribution of microtubules, and gastric healing in mucosa damaged with hypertonic NaCl solution. Rats were fasted for 22 h and then given 1.0 ml of 3.4 M NaCl intragastrically. Animals were killed 1, 2, 4, 8, and 10 h after 3.4 M NaCl. The oxyntic gland mucosa was removed, and tubulin was visualized by immunofluorescence. Microtubule density was increased around and below the damaged mucosa in the upper one-third of the glandular epithelium at 2 and 4 h and returned to near control levels by 10 h. In rats damaged with 3.4 M NaCl and pretreated intraperitoneally with alpha-difluoromethylornithine (DFMO), a specific inhibitor of ODC, microtubule content was reduced significantly at all time points after NaCl treatment. Addition of spermidine after pretreatment with DFMO and 3.4 M NaCl significantly prevented the effects of DFMO. Colchicine, a potent microtubule-disrupting drug, significantly delayed normal gastric mucosal healing with no effect on ODC activity. These data show that polyamines influence the distribution of microtubules during damage in vivo and indicate a partial mechanism for the dependency of mucosal healing on polyamines.

Animals↗
PubMed2001

"Accordion" deformity of a tortuous external iliac artery after stent-graft placement.

PURPOSE: To identify a complication of endograft deployment in aneurysmal iliac arteries. CASE REPORT: A 71-year-old man was referred for endovascular treatment of a 60-mm-diameter right common iliac artery aneurysm; however, deployment of a homemade covered stent (Palmaz-Schatz and polytetrafluoroethylene) induced shortening of the tortuous external iliac artery, causing an "accordion" deformity. The anomaly proved difficult to treat with serial Wallstent deployment, because the convolution tightened and migrated caudally with each stent deployed, threatening outflow. Finally, after 3 Wallstents were implanted, the contour of the external iliac artery was straight, and flow was unimpeded. However, 3 weeks later, the external iliac artery had recoiled to its original redundant appearance, but flow remained satisfactory. The aneurysm remains excluded, with satisfactory distal flow after 24 months. CONCLUSIONS: Implanting endografts in redundant, tortuous arterial segments may prove problematic, since induced straightening by the device precipitates kinking in the redundant system. Although treatment may be required in some situations, the vessels may return to a noncompressed state by removing the delivery system and guidewire.

Aged↗
PubMed2005

Results from the prospective registry of endovascular treatment of abdominal aortic aneurysms (RETA): mid term results to five years.

OBJECTIVES: To assess the mid-term outcomes up to 5 years following endovascular repair of abdominal aortic aneurysms (EVAR), following its initial introduction into practice in the UK. DESIGN: A prospective voluntary Registry of Endovascular Treatment of Aneurysms (RETA) collected demographic and risk factor data, short term (30 day) outcomes and follow up outcomes up to 5 years from the 41 centres that initially undertook EVAR in the UK. RESULTS: Short term outcomes (30 days): 90.4% of aneurysms were successfully excluded, 6.1% had persistent endoleaks and 5.8% of patients had died. Follow up was obtained from 30 days up to 5 years (mean 3.1 years). Returns rates for requested follow up data were 87% at 1 year and 77, 65, 52 and 51% at 2, 3, 4 and 5 years, respectively. Ninety percent of deaths at follow up were unrelated to the stent-graft or aneurysm. Persistent proximal type I endoleak was associated with significant mortality both from attempted open repair or from rupture if untreated. Other endoleaks were more benign. Complications related to the aneurysm or device occurred at an average rate of 15% per annum. The most common complications were secondary endoleaks or graft migration. Endovascular treatment was preferred if treatment was necessary for graft complications. The cumulative freedom from secondary procedure (Kaplan-Meier) were 87, 77, 70, 65 and 62% at 1, 2, 3, 4 and 5 years of follow up, respectively. CONCLUSIONS: Registry data provides useful information to guide the design of more formal trials. Collecting follow up from voluntarily submitted data is difficult. The registry data remains well ahead of the trial data, but indicate that long term follow up is required in these trials, because of the high rate of complications seen at follow up.

Angioplasty, Balloon↗
PubMed1995

Evidence for hydrodynamic orientation by spiny lobsters in a patch reef environment

Western Atlantic spiny lobsters (Panulirus argus) are superb underwater navigators. Spiny lobsters perform dramatic seasonal offshore migrations and have also been shown to locate and home to specific den sites within the elaborate coral reef environment in which they live. How these animals perform such complex orientation tasks is not known. The study reported here was designed to explore the sensory mechanisms that spiny lobsters use to orient in and around a familiar patch reef environment. Our results show that, in the absence of visual cues, lobsters displaced a short (50 m) distance off the reef do not initially (i.e. within 20 min) travel towards their dens or return to the patch reef where their dens are located. Instead, the headings lobsters follow are significantly correlated to the direction of local hydrodynamic cues and, specifically, to the direction of approaching wave surge. Results from ultrasonic tracking experiments over longer periods (24 h) suggest that displaced lobsters are able to relocate the reef where they were captured, even without visual cues. These results suggest that hydrodynamic cues may provide useful and immediate directional information to lobsters within the local environment of the home reef.

Journal Article↗