Pathodynamics

Osteoporosis and osteoporosis-related fractures in the aging population are becoming a health care problem and a burden on health service resources available. Osteoporosis is a systemic skeletal disorder that results from an imbalance in bone remodeling, leading to a reduction in bone strength with microarchitectural disruption and skeletal fragility, increasing fracture susceptibility. Osteoporosis is considered a well-known metabolic bone disorder. Although its prevalence is more commonly seen in women than men, it is eventually seen in both genders. In the elderly population, there is an increase in disability and mortality due to osteoporotic fractures.

Ipsilateral Intertrochanteric Fracture with Posterior Dislocation of Hip

Introduction

High-energy trauma has increased the incidence of traumatic hip dislocation and dislocation is often associated with fractures. However, a hip fracture-dislocation extending to the ipsilateral femoral trochanter is exceedingly rare and only a few cases have been described. We report a case of irreducible posterior dislocation of the hip with ipsilateral intertrochanteric fracture managed by open reduction and osteosynthesis.

Case Report

A 50-year-old male presented with a history of fall from an electricity pole with pain in the left hip and an inability to bear weight on his left lower limb. Radiographs confirmed the presence of posterior dislocation of the left hip with comminuted intertrochanteric fracture on the same side.

Conclusion

Posterior dislocation of the hip with same side inter trochanteric fracture is a rare traumatic entity, with only few case being reported. Literature does not provide any classification for such rare traumatic fracture dislocation. Management of such fracture requires early diagnosis and intervention which can result in good prognosis.

Common Peroneal Nerve Splitting in Proximal Fibular Osteochondroma: A Rare Presentation

Introduction

Osteochondroma is the most common benign tumor of bone. Tumors are metaphyseal in origin and commonly involve distal femur, proximal tibia, and proximal fibula in the lower extremity. Osteochondroma located at proximal fibula can change the normal path of nerves and it may lead to the compression of vessels or peroneal nerve, leading to paralysis.

Case Report

We are reporting a case of an 18-year-old female with proximal fibular osteochondroma causing splitting of common peroneal nerve without any neuropathy.

Conclusion

We strive to make the surgeons aware that, when removing osteochondroma located at proximal fibula, care should be taken to identify the entire nerve at the site of lesion before the removal as a procedure done in a hurry in such a case can cause irreversible damage to the patient.

OC-022 MAINTAINING AN ELECTIVE ABDOMINAL WALL RECONSTRUCTION SERVICE DURING THE COVID 19 PANDEMIC

Aim

Elective surgery services suffered significantly due to the COVID-19 pandemic. The aim of this study was to analyse the impact and outcomes of abdominal wall reconstruction (AWR) performed during the COVID-19 pandemic, assessing safety and sustainability.

Material and Methods

A retrospective review of all patients undergoing AWR in a single NHS trust, multiple surgeons, between 23rd March 2020 and 22rd March 2022, the 2 years following U.K. Government imposed lockdown, was undertaken and compared with the pre-pandemic AWR activity. Procedures were initially undertaken at a cold site and when demonstrated to be safe, main site operating restarted. The primary outcome was 90 day mortality, secondary outcomes of COVID-19 infection within 7 days, length of stay, critical care requirement, and complication rate.

Results

In the study period, 173 patients underwent AWR, compared with 99 cases in a single year preceding lockdown. 90 day mortality rate was zero. No patients returned positive COVID tests to the trust within 7 days of AWR, and no patients were readmitted for COVID related symptoms. Critical care admission was required in 7 patients, 3 of these were planned admissions pre-operatively. The surgical site occurrence rate was 9.8% (17), infection 5.8% (10), seroma 2.3% (4) and haematoma 1.7% (3). There were no recurrences reported, with follow up ranging between 1 and 18 months.

Conclusion

Continuing AWR services during the COVID pandemic is feasible and safe. Peri-operative COVID infection rates are low, critical care requirements minimal, and there is no impact on patient morbidity or mortality.

P-135 FIRST EXPERIENCE WITH A NEW CLOSED INCISION NEGATIVE PRESSURE WOUND THERAPY, PREVENA™, IN ABDOMINAL WALL RECONSTRUCTION PATIENTS

Aim

Surgical site infection (SSI) contributes a significant proportion of post operative morbidity in patients undergoing abdominal wall reconstruction (AWR). Prevena™ closed incision negative pressure wound therapy (ciNPT) has been demonstrated to reduce SSI rates in the elective and emergency laparotomy setting. However, there is no evidence for Prevena™ use in AWR patients. The aim of this study was to assess the safety and feasibility of Prevena™ in AWR patients.

Materials and Method

Patients undergoing AWR at a single trust were selected at random to receive Prevena™. This was applied to the incision under sterile conditions, a continuous pressure of -125mmHg was applied for 7 days. The primary outcome measure was SSI, with secondary outcomes of 90 day mortality, complications and length of stay.

Results

10 patients received ciNPT in the study period, 8 female 2 male, mean BMI was 34.5. All patients had a Rives-Stoppa repair, with 2 patients also requiring bilateral transversus abdominal release (TAR). A vertical panniculectomy with umboplasty was used in 7 cases, fleur-de-lys panniculectomy with umboplasty in 2 cases, and a single case approached via transverse panniculectomy. There were no deaths within 90 days, median length of stay was 4 days. There was a single SSI managed with oral antibiotics, not requiring admission.

Conclusion

Prevena™ has been shown to reduce SSI rates in other patient cohorts and this small series demonstrates it is feasible and safe to use in the AWR setting. Larger studies are required to demonstrate SSI rate reduction in AWR patients.

Single piece artificial urinary sphincter for secondary incontinence following successful repair of post traumatic urethral injury

Post traumatic urethral injury is uncommon in children. The management of this condition is dependent on the severity of injury. Initial suprapubic cystostomy with delayed repair is the conventional treatment. Successful reconstruction of urethral injury may be followed by urethral stricture, incontinence, impotence, and retrograde ejaculation. Successful repair of post traumatic urethral injury followed by secondary incontinence in children has not been well addressed in literature. We report the management of one such child, with satisfactory outcome with implantation of a new model of single piece artificial urinary sphincter in the bulbar urethra by perineal approach.

Gastric outlet obstruction caused by a pyloric submucosal fibroepithelial tumour

A 57 year old male patient presented to our hospital with vomiting, epigastric discomfort, and loss of appetite over a 24hr period. Subsequent investigations demonstrated a submucosal lesion causing gastric outlet obstruction. The patients deteriorating condition mandated laparotomy and a pathologic diagnosis was made of a pyloric submucosal fibroepithelial lesion from the resected distal stomach and adherent transverse colon; no malignant features were found. This is to our knowledge the first instance of a fibroepithelial neoplasm occurring within the gastrointestinal tract.

BANANAS

Today the Internet offers a single path between end-systems even though it intrinsically has a large multiplicity of paths. This paper proposes an evolutionary architectural framework "BANANAS" aimed at simplifying the introduction of multipath routing in the Internet. The framework starts with the observation that a path can be encoded as a short hash ("PathID") of a sequence of globally known identifiers. The PathID therefore has global significance (unlike MPLS or ATM labels). This property allows multipath capable nodes to autonomously compute PathIDs in a partially upgraded network without requiring an explicit signaling protocol for path setup. We show that this framework allows the introduction of sophisticated explicit routing and multipath capabilities within the context of widely deployed connectionless routing protocols (e.g. OSPF, IS-IS, BGP) or overlay networks. We establish these characteristics through the development of PathID encoding and route-computation schemes. The BANANAS framework also allows considerable flexibility in terms of architectural function placement and complexity management. To illustrate this feature, we develop an efficient variable-length hashing scheme that moves control-plane complexity and state over-heads to network edges, allowing a very simple interior node design. All the schemes have been evaluated using both sizable SSFNet simulations and Linux/Zebra implementation evaluated on Utah's Emulab testbed facility.

The role of Mac-1 (CD11b/CD18) in antigen-induced airway eosinophilia in mice

Mac-1 (CD11b/CD18) is an important adhesion molecule involved in the migration of leukocytes, cell signaling, and subsequent secretory responses. Its precise role in eosinophil recruitment and activation in vivo is not entirely clear. We wished to directly examine the role of Mac-1 in eosinophil migration in a murine model of allergic pulmonary inflammation. Briefly, wild-type (C57Bl/6) and Mac-1-deficient/knockout (Mac-1 KO) mice were intraperitoneally sensitized with ovalbumin (OVA) and alum (AlOH) on Days 0 and 14, and intranasally challenged with OVA either once on Day 14 or five times on Days 14 and 25 through 28. Control animals were challenged with saline. Bronchial hyperresponsiveness was measured, bronchoalveolar lavage (BAL) fluid was collected, and lungs were harvested for histology 24 h after the last challenge. The data demonstrate that wild-type (WT) mice do not respond to one OVA challenge but do develop bronchial hyperreactivity and airway and tissue eosinophilia after five OVA challenges. Conversely, Mac-1 KO mice develop significant airway eosinophilia after one OVA challenge, and the degree of airway inflammation is comparable to that observed in allergic WT mice after five challenges. In Mac-1 KO mice, after five challenges, bronchial hyperreactivity and airway inflammation was significantly enhanced compared with their wild-type counterparts. Administration of an anti-Mac-1 antibody to WT mice, before each of five intranasal OVA challenges, significantly reduces the airway eosinophilia but has no effect on tissue eosinophilia or bronchial hyperresponsiveness. Intravenous injection of interleukin-5 induced a significant blood eosinophilia in both WT and Mac-1 KO mice. Intranasal eotaxin administration induced similar levels of eosinophil migration into the lung tissues and airways of both WT and Mac-1 KO mice. In conclusion, Mac-1-deficient mice develop enhanced eosinophilic inflammation in the lung in response to allergic antigen challenge.

Protective effect of N-acetylcysteine in isoniazid induced hepatic injury in growing rats

Status of oxidative/antioxidative profile was the mechanistic approach to inumerate the nature of protection by N-acetylcysteine (NAC) in isoniazid (INH) exposed experimental animals. Analysis of lipid peroxidation, thiol levels, cytochrome P450, superoxide dismutase (SOD), catalase, glutathione peroxidase, reductase and transferase were estimated in liver along with the body and liver weight of animals and histological observations. Isoniazid exposure to animals resulted in no change in body and liver weights. Thiols, lipid peroxidation, catalase, SOD glutathione peroxidase, reductase, transferase and cytochrome P450 levels were altered with INH exposure. Supplementation of NAC with INH protected the animals against hepatotoxic reactions by minimizing the free radical induced tissue injury and overall maintenance of the endogenous scavengers of free radicals.

Antiorthostatic suspension for 14 days does not diminish the oxidative response of neutrophils in mice

The effects of long-term spaceflight on inflammatory responses have not been well-studied in either humans or animals. It is thus important to determine if the functions of immune and inflammatory cells are altered in models of spaceflight. One such animal model is antiorthostatic suspension (AOS), in which the experimental animal is subjected to a head-down tilt that mimics both the stress and the cephalad fluid shift experienced in spaceflight. A previous study reported that the peritoneal neutrophils from mice experiencing AOS generated less superoxide than unsuspended controls. We expanded on this study using several different stimuli and measuring the oxidative response of murine neutrophils in a variety of ways. These responses included the rate, lag period, and dose/response characteristics for superoxide generation, FACS analysis with dihydrodichlorofluorescein as a substrate, and a chemiluminescence response with luminol as a substrate. We also examined phagocytosis of three different microorganisms. While some effects of orthostatic suspension (attributable to the stress of the apparatus) were observed, no clear effects of AOS on oxidative function of the peritoneal neutrophils were seen.

E/P-selectin-deficient mice: an optimal mutation for abrogating antigen but not tumor necrosis factor-alpha-induced immune responses

Leukocyte recruitment in cremaster microcirculation was visualized by intravital microscopy, either in ovalbumin sensitized and challenged animals, or in response to TNF-alpha. In antigen-challenged mice a significant increase in leukocyte rolling (approximately 50 to 200-300 cells/min) and adhesion (2 to 15-20 cells/100 microm), and a very dramatic increase in emigration ( approximately 1 to >40 cells/field) was observed over 24 h. Although rolling and adhesion was dramatically blunted in P-selectin- or P selectin/ICAM-1-deficient mice, emigrated cell number was similar to that observed in wild-type mice. Leukocyte rolling, adhesion and emigration was almost entirely abrogated over 24 h in E/P-selectin-deficient mice, demonstrating that antigen-induced leukocyte recruitment can be entirely disrupted in the absence of both endothelial selectins. However, E/P-selectin-deficient mice were able to recruit leukocytes at 24 h after TNF-alpha challenge. Rolling 24 h post-TNF-alpha in E/P-selectin-deficient mice was not inhibitable with anti-L-selectin antibody, suggesting an entirely selectin-independent pathway of rolling. We identified this pathway to be alpha (4)-integrin dependent and demonstrated that VCAM-1 expression was increased only in mice challenged with TNF-alpha. These data demonstrate that, in vivo, sufficient amounts of TNF-alpha can recruit leukocytes independently of selectins, whereas inhibition of endothelial selectins is the optimal intervention in reducing the immune response to antigen.

Lack of correlation between failure of gut barrier function and septic complications after major upper gastrointestinal surgery

OBJECTIVE

To determine the influence of abnormal gut barrier function on the risk of septic complications in patients undergoing major resectional surgery for upper gastrointestinal cancer.

SUMMARY BACKGROUND DATA

A failure of the gut mucosal barrier to exclude bacteria and endotoxin from the portal and systemic circulation is incriminated in the development of sepsis and multiple organ failure. Although the experimental data is compelling, corroborative evidence from studies in humans is sparse. This study attempted to correlate both preoperative gut barrier dysfunction and the pattern of change after surgery with septic outcome.

METHODS

Sixty-eight patients undergoing curative resectional surgery for upper gastrointestinal cancer were monitored for 30-day septic morbidity (intraabdominal abscesses/empyema and pneumonia). Intestinal permeability, serum IgM and IgG anti-endotoxin antibodies (EndoCAb), and serum C-reactive protein were measured before surgery and on postoperative days 1 and 7.

RESULTS

Increased intestinal permeability before surgery did not predict septic outcome. Major surgery was associated with increased intestinal permeability and evidence of endotoxin exposure. Comparing sepsis and nonsepsis groups, however, there was no significant difference in intestinal permeability, endotoxin exposure, and the acute phase response after surgery.

CONCLUSIONS

This study demonstrates that gut barrier dysfunction occurs after surgery, but the magnitude of change does not differentiate patients in whom sepsis develops and those in whom it does not. Preoperative increased intestinal permeability had no predictive value for sepsis. This study failed to support the thesis that gut barrier dysfunction is directly linked to sepsis.

Overlapping roles for L-selectin and P-selectin in antigen-induced immune responses in the microvasculature

Although L-selectin mediates lymphocyte attachment to endothelial venules of peripheral lymph nodes, its role in leukocyte recruitment into tissues following Ag challenge is less well established. The objective of this study was to systematically examine the role of L-selectin in leukocyte rolling in the peripheral microvasculature during the first 24 h of an immune response. A type I hypersensitivity response was elicited in wild-type (C57BL/6) and L-selectin-deficient mice by systemic (i.p.) sensitization and intrascrotal challenge with chicken egg OVA. The cremaster microcirculation was observed in untreated and sensitized mice 4, 8, and 24 h post-Ag challenge by intravital microscopy. Leukocyte recruitment in L-selectin-deficient mice and wild-type mice treated with an L-selectin function-blocking mAb was examined at each time point. Ag challenge induced a significant increase in leukocyte rolling (60 cells/min/venule to approximately 300 cells/min/venule) in wild-type mice at 4-24 h. This response was reduced by approximately 60-70% in L-selectin-deficient mice and in wild-type mice treated with an L-selectin-blocking mAb. P-selectin blockade by Ab completely inhibited leukocyte rolling at 4-24 h in wild-type animals and also blocked the residual rolling seen in L-selectin-deficient mice. Blocking E-selectin function had no effect on leukocyte rolling flux at any time point in wild-type or L-selectin-deficient mice. Despite reduced rolling, leukocyte adhesion and emigration were not measurably reduced in the L-selectin-deficient mice in this vascular bed. In conclusion, leukocyte rolling is L-selectin-dependent post-Ag challenge with L-selectin and P-selectin sharing overlapping functions.

Varying roles of E-selectin and P-selectin in different microvascular beds in response to antigen

Expression of E-selectin and P-selectin is critical in the effector phase of leukocyte recruitment in response to Ag. Whether their relative roles differ between tissues in response to the same Ag is unknown. In this study, a type I hypersensitivity response was elicited in C57BL/6 mice by systemic sensitization with OVA. Following local Ag challenge, endothelial selectin expression was examined in the skin and cremaster muscle microvasculature using a dual-radiolabeled mAb technique. Next, the dermal and muscle microcirculations were visualized using intravital microscopy to establish roles for P-selectin and/or E-selectin. In untreated mice, leukocyte recruitment in both skin and skeletal muscle was mediated entirely by P-selectin. Following Ag challenge, leukocyte rolling flux and adhesion were dramatically increased and leukocyte rolling velocity was unchanged in muscle. Only P-selectin expression increased in muscle, and leukocyte recruitment was entirely dependent upon this selectin. In contrast, in Ag-challenged skin, leukocyte rolling flux did not increase, but rolling velocity dropped profoundly. In skin, only E-selectin expression increased, and blockade of either E-selectin or P-selectin had minimal effect on either rolling flux or rolling velocity. Blockade of both selectins reduced rolling flux by 80% and increased rolling velocity sevenfold. These data highlight striking differences in expression of the endothelial selectins in separate microvascular beds in response to the same stimulus and demonstrate that these differences underlie very different patterns of leukocyte recruitment. The data underscore the importance of studying individual microvascular beds to understand tissue-specific leukocyte recruitment in vivo.

An absolute requirement for P-selectin in ischemia/reperfusion-induced leukocyte recruitment in cremaster muscle

OBJECTIVE

To systematically examine a role for P-selectin in a model of striated muscle ischemia/reperfusion (I/R).

METHODS

Ischemia was induced in the cremaster muscle of mice by occluding the main feeding arteriole for 30 minutes. Blood flow was then restored to allow for 60 minutes of reperfusion and leukocyte kinetics were assessed during the control period (before I/R) and at 5, 30, and 60 minutes of reperfusion. To study a role for P-selectin in this model, three different approaches were used: Wild-type animals received fucoidin (10 mg/kg, i.v.), an anti-P-selectin antibody (RB40.34; 20 mg/animal, i.v.) at 25 minutes of ischemia, or I/R was induced in P-selectin-deficient mice.

RESULTS

Ischemia/reperfusion induced a rapid and significant increase in leukocyte rolling, adhesion, and emigration in wild-type mice. The I/R-induced increase in leukocyte rolling was transient, inasmuch as it was reduced by approximately 50% at 30 minutes of reperfusion, and returned to control levels by 60 minutes. Both fucoidin and an anti-P-selectin antibody completely prevented the I/R-induced increase in leukocyte rolling. The P-selectin-deficient animals exhibited absolutely no baseline leukocyte rolling, adhesion, or emigration. Furthermore, I/R did not induce any increase in leukocyte recruitment in the P-selectin-deficient animals over the first 60 minutes of reperfusion.

CONCLUSION

The results from this study clearly illustrate that P-selectin is absolutely critical in both baseline and I/R-induced leukocyte infiltration in the murine-striated muscle.

Postischemic inflammation: a role for mast cells in intestine but not in skeletal muscle

The objective of this study was to directly study a role for mast cells in ischemia-reperfusion (I/R)-induced mucosal and microvascular dysfunction. I/R was induced in the intestine and skeletal muscle (gastrocnemius and cremaster muscle) of wild-type mice and mast cell-deficient mice (W/Wv). Changes in mucosal permeability (blood-to-lumen clearance of 51Cr-EDTA), leukocyte infiltration (myeloperoxidase activity in the intestine and intravital microscopy in the cremaster muscle), and vascular permeability (tissue wet-to-dry weight ratio and FITC-albumin leakage) were measured as indexes of tissue dysfunction. In wild-type animals, intestinal I/R induced a significant increase in mucosal permeability, leukocyte infiltration, and vascular permeability. Mast cell-deficient animals were completely protected from I/R-induced mucosal dysfunction. However, skeletal muscle I/R induced a significant increase in leukocyte infiltration, FITC-albumin leakage, and edema formation to the same degree in both wild-type and mast cell-deficient animals. These data suggest that mast cells may be important mediators of I/R-induced mucosal and microvascular dysfunction in the intestine but not of microvascular dysfunction in skeletal muscle.

Compared with parenteral nutrition, enteral feeding attenuates the acute phase response and improves disease severity in acute pancreatitis

BACKGROUND

In patients with major trauma and burns, total enteral nutrition (TEN) significantly decreases the acute phase response and incidence of septic complications when compared with total parenteral nutrition (TPN). Poor outcome in acute pancreatitis is associated with a high incidence of systemic inflammatory response syndrome (SIRS) and sepsis.

AIMS

To determine whether TEN can attenuate the acute phase response and improve clinical disease severity in patients with acute pancreatitis.

METHODS

Glasgow score, Apache II, computed tomography (CT) scan score, C reactive protein (CRP), serum IgM antiendotoxin antibodies (EndoCAb), and total antioxidant capacity (TAC) were determined on admission in 34 patients with acute pancreatitis. Patients were stratified according to disease severity and randomised to receive either TPN or TEN for seven days and then re-evaluated.

RESULTS

SIRS, sepsis, organ failure, and ITU stay, were globally improved in the enterally fed patients. The acute phase response and disease severity scores were significantly improved following enteral nutrition (CRP: 156 (117-222) to 84 (50-141), p < 0.005; APACHE II scores 8 (6-10) to 6 (4-8), p < 0.0001) without change in the CT scan scores. In parenterally fed patients these parameters did not change but there was an increase in EndoCAb antibody levels and a fall in TAC. Enterally fed patients showed no change in the level of EndoCAb antibodies and an increase in TAC.

CONCLUSION

TEN moderates the acute phase response, and improves disease severity and clinical outcome despite unchanged pancreatic injury on CT scan. Reduced systemic exposure to endotoxin and reduced oxidant stress also occurred in the TEN group. Enteral feeding modulates the inflammatory and sepsis response in acute pancreatitis and is clinically beneficial.

1997 Harry M. Vars Research Award. Does the route of feeding modify gut barrier function and clinical outcome in patients after major upper gastrointestinal surgery?

BACKGROUND

Direct experimental evidence suggests that total enteral nutrition (TEN) reduces septic morbidity compared with bowel rest and total parenteral nutrition (TPN) and that mucosal support and maintenance of gut barrier function is a key mechanism. This effect is supported indirectly by clinical studies, but this question has not previously been investigated directly in the postoperative patient. This study examined the hypothesis that early enteral feeding after major upper gastrointestinal surgery may modulate gut barrier function and decrease the risk of major infective complications compared with bowel rest and parenteral nutrition.

METHODS

A randomized clinical trial of 67 patients (TPN = 34; TEN = 33) fed postoperatively for 7 days was performed. Thirty-day major morbidity and mortality were monitored. Intestinal permeability was measured using the lactulose/mannitol test preoperatively and on postoperative days 1 and 7. Systemic anti-endotoxin core immunoglobulin G and M antibodies and serum albumin and C-reactive protein were quantified at these time points.

RESULTS

No clinical benefit was observed in patients fed enterally compared with the parenterally fed group. Intestinal permeability was increased on the 1st postoperative day in association with evidence of endotoxin exposure. By day 7, enteral feeding compared with parenteral feeding had failed to significantly influence any of the gut barrier or systemic parameters.

CONCLUSIONS

This randomized controlled trial of TEN vs TPN after major upper gastrointestinal surgery failed to show a clinical benefit for the enteral route. Moreover, enteral nutrition did not modulate gut barrier function postoperatively.

The association between alpha4-integrin, P-selectin, and E-selectin in an allergic model of inflammation

In this study, we examined the relationship between the endothelial selectins (P-selectin and E-selectin) and whether they are critical for alpha4-integrin-dependent leukocyte recruitment in inflamed (late phase response), cremasteric postcapillary venules. Animals were systemically sensitized and 2 wk later challenged intrascrotally with chicken ovalbumin. Leukocyte rolling flux, adhesion, and emigration were assessed at baseline and 4 and 8 h postantigen challenge. There was a significant increase in leukocyte rolling flux, adhesion, and emigration in sensitized and challenged mice at both 4 and 8 h. At 8 h, the increase in leukocyte rolling flux was approximately 50% inhibitable by an anti-alpha4-integrin antibody, 98% inhibitable by fucoidin (a selectin-binding carbohydrate), and 100% inhibitable by an anti-P-selectin antibody. P-selectin-deficient animals displayed no leukocyte rolling or adhesion at 8 h after challenge. However, at 8 h there were many emigrated leukocytes in the perivascular space suggesting P-selectin-independent rolling at an earlier time point. Indeed, at 4 h postantigen challenge in P-selectin-deficient mice, there was increased leukocyte rolling, adhesion, and emigration. The rolling in the P-selectin-deficient mice at 4 h was largely alpha4-integrin dependent. However, there was an essential E-selectin-dependent component inasmuch as an anti-E-selectin antibody completely reversed the rolling, and in E-selectin and P-selectin double deficient mice rolling, adhesion and emigration were completely absent. These results illustrate that P-selectin underlies all of the antigen-induced rolling with a brief transient contribution from E-selectin in the P-selectin-deficient animals. Finally, the antigen-induced alpha4-integrin-mediated leukocyte recruitment is entirely dependent upon endothelial selectins.

Hydrogen peroxide induces leukocyte rolling: modulation by endogenous antioxidant mechanisms including NO

In this study, intravital microscopy was used to examine the mechanisms that regulate H2O2-induced leukocyte rolling within rat mesenteric venules in vivo. H2O2 elicited leukocyte rolling within a narrow response window between 10 and 500 microM H2O2. Continuous superfusion with 100 microM H2O2 induced a large but transient increase in the flux of rolling leukocytes, whereas a short 5-min pulse elicited a sustained increase in rolling flux. Both treatments caused increases in leukocyte adhesion. H2O2-induced increases in leukocyte flux and adhesion could be prevented with an anti-P-selectin antibody. Inhibition of endogenous catalase (aminotriazole), glutathione (diethyl maleate), or nitric oxide (NG-nitro-L-arginine methyl ester) shifted the effective concentration of H2O2; continuous superfusion with 10 microM H2O2 now elicited large and sustained increases in leukocyte rolling flux, whereas 100 microM H2O2 elicited less than optimal responses. Dual antioxidant inhibition further reduced the effective H2O2 concentration to 1 microM H2O2. A nitric oxide donor prevented the increased rolling flux induced by 100 microM H2O2. These findings suggest that endogenous antioxidants are important regulators of H2O2-induced, P-selectin-dependent leukocyte rolling in vivo.

Nitric oxide synthase activity in portal-hypertensive and cirrhotic rats

BACKGROUND/AIMS

The hyperdynamic circulation of cirrhosis and portal hypertension has been postulated to be due to the vasodilatory effects of nitric oxide. However, studies using pharmacological inhibitors of nitric oxide synthase have yielded conflicting results. We aimed to measure nitric oxide synthase activity in tissues from two different rat models of cirrhosis and portal hypertension.

METHODS

Cirrhosis was induced by chronic bile duct ligation, and prehepatic portal hypertension by portal vein stenosis. Controls were sham-operated. A fourth group was treated with lipopolysaccharide endotoxin. Ca(2+)-dependent and Ca(2+)-independent nitric oxide synthase activity was assayed by measuring the conversion rate of 14C-arginine to 14C-citrulline in homogenates of stomach, jejunum, liver, kidney and aorta.

RESULTS

Jejunal homogenates from the portal vein-stenosed rats showed a significant 10-fold elevation of Ca(2+)-dependent nitric oxide synthase activity. Cirrhotic rat kidney showed significantly decreased Ca(2+)-dependent and Ca(2+)-independent nitric oxide synthase activity. Endotoxin treatment increased Ca(2+)-independent nitric oxide synthase activity in jejunum and liver. There was no increase in Ca(2+)-independent nitric oxide synthase activity in any tissues from cirrhotic or portal hypertensive rats.

CONCLUSIONS

We conclude that the lack of increase in Ca(2+)-independent nitric oxide synthase activity does not support the hypothesis that nitric oxide is the major cause of hyperdynamic circulation in cirrhosis.

Leukotriene C4/D4 induces P-selectin and sialyl Lewis(x)-dependent alterations in leukocyte kinetics in vivo

The objective of this study was to assess the effect of leukotriene C4 (LTC4) on the flux of rolling leukocytes, leukocyte rolling velocity, and leukocyte adhesion in postcapillary venules in vivo and to study the underlying molecular mechanisms involved. LTC4 (20 nmol/L) induced a rapid and significant increase in leukocyte rolling flux that was inhibitable by an anti-P-selectin antibody and soluble sialyl Lewis(x) (sLe(x)). LTC4 also induced a significant reduction in leukocyte rolling velocity, an event that was independent of P-selectin but entirely dependent on sLe(x). This LTC4-induced reduction in leukocyte rolling velocity was independent of any hemodynamic alterations. Another P-selectin effector, histamine, did not affect leukocyte rolling velocity even at > 5000 times the concentration of LTC4. Treatment with an anti-L-selectin antibody had no effect on the LTC4-induced increase in leukocyte rolling or reduction in rolling velocity. Inhibition of LTC4 bioconversion to LTD4 by pretreatment with L-serine (100 mumol/L) prevented the LTC4-induced increase in leukocyte rolling flux and the LTC4-induced reduction in leukocyte rolling velocity. A subtle, yet significant, increase in leukocyte adhesion was also observed with LTC4. Pretreatment with a platelet-activating factor receptor antagonist returned the LTC4-induced leukocyte rolling velocity to baseline levels. The addition of a very low concentration of platelet-activating factor (1 nmol/L) induced significant leukocyte adhesion in the presence of LTC4 but not histamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Desmopressin induces endothelial P-selectin expression and leukocyte rolling in postcapillary venules

Desmopressin, (DDAVP; 1-desamino-8-D-arginine vasopressin) increases the release and activity of von Willebrand factor (vWF); however, its effects on the other major constituent of endothelial Weibel-Palade bodies, P-selectin, has not been investigated. DDAVP-induced P-selectin expression may explain DDAVP's efficacy in bleeding disorders in which vWF levels are normal. Therefore, the objective of this study is to assess the effect of DDAVP on P-selectin expression on endothelial cells of postcapillary venules in vivo and on human umbilical vein endothelium in vitro, and to determine whether DDAVP has direct effects on leukocyte behavior in postcapillary venules. DDAVP (0.1 and 1.0 microgram/mL) induced a significant but transient increase in P-selectin expression on human umbilical vein endothelial cells as well as on rat and human platelets. Immunohistochemical analysis of rat postcapillary venules showed that in contrast to saline, DDAVP injection (1 microgram/kg, intravenous) induced significant endothelial P-selectin expression. DDAVP administration also induced a rapid and significant increase in leukocyte rolling in rat mesenteric venules in vivo. This response was entirely dependent on P-selectin, as an anti-P-selectin antibody rapidly reversed the DDAVP-induced increase in leukocyte rolling. DDAVP induced leukocyte rolling in medium (20 to 40 microns) and large (> 40 microns), but not small (< 20 microns), postcapillary venules. In animals that were treated with DDAVP, there was a steady and significant increase in leukocyte adhesion. This study shows that DDAVP can directly induce P-selectin expression on endothelium in vitro and in vivo and that the latter response is capable of supporting prolonged leukocyte rolling in rat postcapillary venules.

Neutrophil adhesion is impaired in rat model of cholestasis

BACKGROUND & AIMS

A high incidence of septic complications has been documented in patients with obstructive jaundice undergoing surgery. Because neutrophils play a central role in the response to infection, the aim of this study was to investigate neutrophil function in a rat model of acute cholestasis induced by bile duct resection.

METHODS

Neutrophil function was assessed using both in vivo and in vitro techniques.

RESULTS

The inflammatory response was defective in vivo in bile duct-resected (BDR) rats compared with sham-resected controls. Furthermore, proinflammatory stimulus-induced neutrophil adherence and emigration from mesenteric values, assessed in vivo using intravital microscopy, was attenuated in BDR vs. sham rats. Neutrophils isolated from BDR and sham rats studied in vitro adhered to a rat biological substratum similarly. However, stimulated neutrophil adherence was eliminated in the presence of BDR but not sham plasma. Similar findings were observed using plasma obtained from a patient with obstructive cholestasis. Experiments performed to further characterize this antiadhesive factor in BDR plasma suggest that the factor is probably a heat-stable glycoprotein.

CONCLUSIONS

Cholestasis in the rat is associated with a defective acute inflammatory response that appears, at least in part, to be caused by a constituent of cholestatic plasma that is antiadhesive to neutrophils.

Nitric oxide is an antiadhesive molecule for leukocytes

There is growing evidence that nitric oxide (NO.), a biologically active gas continuously produced by endothelium, is a homeostatic regulator of leukocyte adhesion in the microcirculation. Inhibition of NO. production leads to increased leukocyte rolling and adhesion in various vascular beds and two adhesion molecules, P-selectin and CD11/CD18, have been implicated in these processes. The role of mast cells and mast cell-derived mediators as potential contributors to the increased adhesion are discussed in this review. Moreover, oxidants may initiate the leukocyte recruitment after NO. synthesis inhibition. Recent data demonstrating increased oxidative stress in endothelium deprived of NO. are summarized. The role of NO. as an anti-inflammatory and antiadhesive modulator in postischemic venules of various organs is also discussed. The beneficial effect of NO. donors in this inflammatory condition is summarized. Finally, the potential use of NO. donating drugs in concert with available pharmaceutical compounds to reduce inflammation is reviewed.

Ischemia/reperfusion-induced granulocyte influx is a multistep process mediated by mast cells

OBJECTIVE

The influx of polymorphonuclear leukocytes (PMNs) that occurs at the onset of reperfusion of postischemic tissue is a multistep mechanism that includes initial rolling of PMNs, a progressive reduction in PMN rolling velocity, and ultimately PMN adhesion and emigration. In this study we assessed whether mast cells play a role in reperfusion-induced PMN recruitment with emphasis on PMN rolling, adhesion, and emigration.

METHODS

Cat small intestinal venules were visualized using intravital microscopy during control, 60 min of ischemia (intestinal blood flow 20% of control), and 60 min of reperfusion in untreated and cromolyn- (mast cell stabilizer) pretreated animals.

RESULTS

Between 1 and 5 min of reperfusion, there was a very dramatic rise in PMN rolling which persisted for the next 60 min. In cromolyn-pretreated animals, the flux of rolling PMNs increased in the very early (5 min) reperfusion period, but by 10 min the number of rolling leukocytes was significantly reduced, an event that persisted for the next 60 min. PMNs rolled at a velocity of 40% of control values for the first 10 min of reperfusion without a change in hemodynamic values but returned toward control values by 60 min of reperfusion. An identical velocity profile was observed for the cromolyn-treated animals. In untreated animals, PMN adhesion and emigration was significantly increased throughout the reperfusion period, whereas the cromolyn-pretreated animals had reduced adhesion (60 min of reperfusion) and a reduced rate of emigration throughout the reperfusion period.

CONCLUSION

Interstitial mast cells contribute significantly to the multistep recruitment (rolling, adhesion, and emigration) of PMNs from blood to postischemic tissues and raise the possibility that antiallergy agents such as cromolyn may be a useful form of therapy in the postischemic intestine.

Mast cells contribute to ischemia-reperfusion-induced granulocyte infiltration and intestinal dysfunction

The objective of this study was to determine whether ischemia-reperfusion (I/R) of the small bowel activated mast cells and, if so, to determine whether this event contributed to granulocyte infiltration and mucosal barrier dysfunction. Autoperfused segments of the jejunum were exposed to 30 min of ischemia followed by 60 min of reperfusion. Epithelial permeability was assessed by the clearance of 51Cr-labeled EDTA from plasma to lumen. Plasma rat mast cell protease II (RMCP II) was measured and used as an index of mucosal mast cell degranulation, whereas myeloperoxidase (MPO) activity was used as an index of granulocyte infiltration. I/R caused a significant increase in plasma RMCP II levels, MPO activity, and epithelial permeability. The mucosal mast cell stabilizer doxantrazole prevented the I/R-induced increase in all three parameters. The connective tissue mast cell stabilizer ketotifen had no effect. To determine whether oxidants were involved in mast cell degranulation, some animals were pretreated with superoxide dismutase and catalase. This regimen completely abolished the I/R-induced rise in plasma RMCP II levels and attenuated mucosal MPO activity and epithelial permeability. Selective inhibitors of two mast cell-derived mediators, platelet-activating factor and histamine, did not attenuate the rise in epithelial permeability. These data suggest that oxidant-induced mucosal mast cell degranulation is a key event in the granulocyte infiltration and tissue dysfunction associated with reperfusion of the ischemic intestine.

Histamine induces leukocyte rolling in post-capillary venules. A P-selectin-mediated event

The objective of this study was to systematically assess the molecular mechanisms and kinetics of histamine-induced leukocyte rolling in rat mesenteric venules using intravital microscopy. A complicating factor in these studies is surgical preparation-induced leukocyte rolling (spontaneous rolling), which leads to a lack of effect of histamine on this parameter. Therefore, we identified the source of the surgery-induced leukocyte rolling (partial mast cell degranulation) and established that pretreatment of animals with sodium cromoglycate (connective tissue mast cell stabilizer) inhibited spontaneous leukocyte rolling. Superfusion of the mast cell-stabilized rat mesentery with histamine caused a profound increase in leukocyte rolling which persisted for the entire hour of experimentation. Diphenhydramine (H1-receptor antagonist) but not cimetidine (H2-receptor antagonist) prevented the rise in histamine-induced leukocyte rolling. An anti-P-selectin Ab but not an anti-CD18 Ab reversed the histamine-induced leukocyte rolling in a dose-dependent fashion. In this model of low base line rolling, exposure of the mesentery to the chemotactic agent platelet-activating factor did not induce leukocyte rolling or adhesion. However, co-administration of histamine with platelet-activating factor did indeed promote leukocyte adhesion suggesting that the presence of at least one effector of P-selectin is a minimal requirement for chemotactically-stimulated leukocytes to adhere to postcapillary venules. This study demonstrates for the first time that histamine induces leukocyte rolling via a P-selectin-dependent mechanism in vivo. This is a prolonged, H1 receptor-mediated event that may contribute significantly to the early phase of inflammation.

Histamine induces leukocyte rolling in post-capillary venules. A P-selectin-mediated event

The objective of this study was to systematically assess the molecular mechanisms and kinetics of histamine-induced leukocyte rolling in rat mesenteric venules using intravital microscopy. A complicating factor in these studies is surgical preparation-induced leukocyte rolling (spontaneous rolling), which leads to a lack of effect of histamine on this parameter. Therefore, we identified the source of the surgery-induced leukocyte rolling (partial mast cell degranulation) and established that pretreatment of animals with sodium cromoglycate (connective tissue mast cell stabilizer) inhibited spontaneous leukocyte rolling. Superfusion of the mast cell-stabilized rat mesentery with histamine caused a profound increase in leukocyte rolling which persisted for the entire hour of experimentation. Diphenhydramine (H1-receptor antagonist) but not cimetidine (H2-receptor antagonist) prevented the rise in histamine-induced leukocyte rolling. An anti-P-selectin Ab but not an anti-CD18 Ab reversed the histamine-induced leukocyte rolling in a dose-dependent fashion. In this model of low base line rolling, exposure of the mesentery to the chemotactic agent platelet-activating factor did not induce leukocyte rolling or adhesion. However, co-administration of histamine with platelet-activating factor did indeed promote leukocyte adhesion suggesting that the presence of at least one effector of P-selectin is a minimal requirement for chemotactically-stimulated leukocytes to adhere to postcapillary venules. This study demonstrates for the first time that histamine induces leukocyte rolling via a P-selectin-dependent mechanism in vivo. This is a prolonged, H1 receptor-mediated event that may contribute significantly to the early phase of inflammation.

Time course of nitric oxide production and epithelial dysfunction during ischemia/reperfusion of the feline small intestine

The objective of this study was to correlate nitric oxide production with time of reperfusion of the post-ischemic feline small intestine. Epithelial permeability, quantitated as blood-to-lumen clearance of 51Cr-EDTA, following 1 hr of ischemia and 4 hr of reperfusion of the small intestine, increased approximately 10-fold. This increase was further augmented by L-NAME infusion between 60 and 120 min but not at 240 min. Ca(2+)-dependent nitric oxide synthase activity was reduced by approximately 50% at 3 and 4 hr of reperfusion, whereas Ca(2+)-independent nitric oxide synthase activity was undetectable throughout the experiment. Administration of L-arginine at the start of reperfusion attenuated the reperfusion-induced epithelial barrier dysfunction for the first 120 min but not at 180 or 240 min. Continuous infusion of a nitric oxide donor (CAS 754) following 1 hr of reperfusion reduced epithelial permeability at 4 hr of reperfusion. In conclusion, a reduction in nitric oxide production was observed with time of reperfusion, possibly due to reduced nitric oxide synthase levels.

Nitric oxide synthesis inhibition increases epithelial permeability via mast cells

In this study, we assessed the involvement of mast cells and mast cell-derived mediators in the enhanced epithelial permeability associated with nitric oxide synthesis inhibition. Permeability of the small bowel was assessed by measuring the clearance of a small marker (51Cr-labeled EDTA) from blood to lumen in the presence of the nitric oxide synthesis inhibitor, NG-nitro-L-arginine methyl ester (L-NAME). L-NAME caused a very rapid (10 min) increase in epithelial permeability, reaching peak values (sixfold increase) within 20 min. Two mast cell stabilizers, doxantrazole and lodoxamide, greatly attenuated the rise in mucosal permeability. Rat mast cell protease II activity (marker of mucosal mast cell degranulation) was increased significantly only in the plasma of L-NAME-treated animals. Chronic dexamethasone administration depleted rats of mucosal mast cells and also prevented the L-NAME-induced rise in mucosal permeability. The increase in epithelial permeability was mediated by a number of mediators: platelet-activating factor caused the early rise in epithelial permeability, and histamine caused the later increase in epithelial permeability. Superoxide dismutase attenuated the L-NAME-induced rise in epithelial permeability, suggesting an important and continuous role for superoxide. Transepithelial flux of 51Cr-EDTA across rat intestinal epithelial cell monolayers did not increase in the presence of L-NAME, suggesting that inhibition of nitric oxide does not directly cause epithelial permeability alterations, whereas the in vivo data implicate a potential role for the mast cell. In conclusion, nitric oxide synthesis inhibition activates mast cells in the mucosa and consequently increases epithelial permeability.

Decreased contact factor mediated fibrinolysis in cirrhosis

We studied extrinsic and intrinsic fibrinolysis in 20 patients with cirrhosis (nine mild/moderate, group 1; 11 severe, group 2) and 19 normal controls to define the role of intrinsic (contact factor medaited) fibrinolysis in cirrhosis. Global plasma fibrinolytic activity (fibrin plate lysis) was similar in all groups. Dextran sulphate activated contact factor mediated fibrinolysis was decreased in group 2 (median 95.2%) compared with group 1 (121.0%) and controls (131.7%). Tissue plasminogen activator antigen (t-PA Ag) levels were increased in group 2 (28.2 ng/ml) compared both with group 1 (8.5 ng/ml) and controls (5.9 ng/ml). Plasma t-PA activity was raised in group 2 (5.50 IU/ml) and group 1 (5.25 IU/ml) versus controls (0.82 IU/ml). Plasminogen activator inhibitor-1 (PAI-1 Ag) levels were raised in group 2 (28.0 IU/ml) versus controls (8.5 IU/ml) but PAI activity was similar in all groups. Factor XII activity was decreased in group 2 (48.76 u/dl), but not group 1, versus controls (89.1 u/dl). Prekallikrein activity was decreased both in group 2 (27.27 u/dl) and group 1 (33.01 u/dl) versus controls (108.59 u/dl) and was lower in group 2 than group 1. C1-esterase inhibitor chromogenic activity was decreased in group 1 (102.30 u/dl) and group 2 (58.76 u/dl) versus controls (116.24 u/dl). The normal global fibrinolytic activity despite increased t-PA activity may be due to a concomitant increase in PAI. The decreased intrinsic fibrinolysis in severe cirrhosis, unaccompanied by a rise in C1-esterase inhibitor, may be explained by the decreased factor XII and prekallikrein activity. These changes are probably due to reduced liver cell mass.

Nitric oxide synthesis inhibition induces leukocyte adhesion via superoxide and mast cells

Recent work has demonstrated that inhibition of nitric oxide production with various nitric oxide synthesis inhibitors (L-NAME, L-NMMA) initiate leukocyte adhesion to postcapillary venules. The objective of this study was to elucidate the mechanism (or mechanisms) that promote the L-NAME-induced leukocyte response. Intravital microscopy was used to examine 25-40 microns venules in the rat mesentery. Nitric oxide synthesis was inhibited with L-NAME and leukocyte adhesion was observed over the first 60 min. The fourfold increase in leukocyte adhesion was independent of alterations in venular red blood cell velocity. The adhesion was superoxide-mediated inasmuch as superoxide dismutase (SOD) abolished the rise in leukocyte adhesion associated with nitric oxide synthesis inhibition. Ketotifen, a mast cell stabilizer, also abolished the rise in leukocyte adhesion induced by L-NAME. Histology revealed that mast cell degranulation occurred only in animals treated with L-NAME but not in animals pretreated with SOD or ketotifen. This observation suggests that mast cells become activated in the absence of nitric oxide production and superoxide contributes to the mast cell activation. The L-NAME-induced leukocyte adhesion could be reproduced by infusing hypoxanthine/xanthine oxidase (a superoxide generating system) or compound 48/80 (an activator of mast cells) and both responses were attenuated by ketotifen. These data suggest that inhibition of nitric oxide synthesis results in a superoxide and mast cell-dependent leukocyte adhesion.

Effects of human neutrophil elastase (HNE) on neutrophil function in vitro and in inflamed microvessels

The primary objective of this study was to test the hypothesis that human neutrophil elastase (HNE) affects neutrophil infiltration (adhesion and emigration) into inflamed vessels. To determine whether HNE contributes to neutrophil adhesion in vivo, intravital microscopy was used to study neutrophil-endothelial cell interactions in single inflamed postcapillary venules. Superfusion of platelet-activating factor (PAF) (100 nmol/L) onto the mesentery caused an increase in neutrophil-neutrophil interactions, neutrophil adhesion to postcapillary venules, and cellular emigration out of the vasculature. Both L658 758 (an elastase-specific inhibitor), and Eglin C (an elastase and cathepsin G inhibitor) significantly attenuated all of these parameters in vivo. To further characterize the mechanism(s) involved, various in vitro parameters were assessed. HNE, but not trypsin, caused a dose-dependent (0.01 to 1.0 microgram/mL) increase in the expression of the beta subunit (CD18) of the CD11/CD18 adhesive glycoprotein complex on neutrophils. An HNE-dependent increase in CD11b expression was also observed; however, HNE did not affect the expression of other neutrophil adhesion molecules (L-selectin), superoxide production, or degranulation. PAF-enhanced CD18 expression on neutrophils and neutrophil migration were both abolished by L658 758 but PAF-induced neutrophil adhesion to endothelial monolayers was not affected by the antiproteinase. The in vitro data suggest that the antiproteinases do not directly prevent neutrophil adhesion in vivo but may be important in other CD18-dependent events such as neutrophil-neutrophil interaction or neutrophil infiltration (chemotaxis). These results translate into an important, rate-limiting role for elastase in the process of leukocyte infiltration and accumulation in inflamed microvessels.

Ladder injuries

A series of 66 patients injured in falls from ladders was studied prospectively to assess the mode of fall, whether or not the fall was preventable, and the range of injuries sustained. Of the patients, 47 (71 per cent) fell because their ladder fell, and up to 90 per cent of these injuries were preventable. A wide spectrum of injuries was noted, and the importance of a thorough examination of such patients is emphasized. The need for a public education programme to prevent such injuries has also been highlighted.

Early life of the 'battered child'

The obstetric histories and early lives of 28 subsequently abused children are reviewed. The youngest child, more often male, was shown to be most 'at risk' especially of the mother was pregnant. Reduced antenatal care, separation of mother and child during the neonatal peroid, illness, poor features. It is felt that these and other difficulties may be regarded as 'environmental pressures' leading to child abuse by susceptible indivisuals, early recognition of such situations could lead to preventive and supportive measures.