Surgery for deep venous incompetence.

BACKGROUND: Chronic deep venous incompetence (DVI) is caused by incompetent vein valves and/or the blockage of large calibre leg veins, with a range of symptoms including recurrent ulcers, pain and swelling. OBJECTIVES: To establish the effectiveness of various surgical procedures for treating DVI. SEARCH STRATEGY: Trials were identified through the Cochrane Peripheral Vascular Diseases Group's trials register, reference lists of relevant studies, and contact with principal investigators of identified trials and world experts in deep venous surgery. SELECTION CRITERIA: Randomised controlled trials of surgical treatment for patients with DVI. DATA COLLECTION AND ANALYSIS: Reviewers extracted data independently. Outcome measures included ambulatory venous pressure (AVP) and venous refill time (VRT). MAIN RESULTS: Three trials were included, one trial was excluded. Two trials compared external valvuloplasty using limited anterior plication (LAP) in combination with ligation (L) of incompetent superficial veins (L+LAP) against ligation only (L). The other trial compared external valvuloplasty and ligation (V+L) of incompetent superficial veins against ligation only (L). Trial participants had primary valvular incompetence with mild to moderate symptoms but no venous ulcers.L+LAP produced significant improvement in AVP: the mean difference between L+LAP and L groups was -15 mm Hg (95% confidence interval (CI) -20.9 to -9.0) at one year and -15 mm Hg (95% CI -21 to -8.9) at ten years.AVP values after surgery remained relatively high. Nine of eleven valves repaired remained competent after two years of follow up. No complications occurred. The overall mean score for clinical outcome was +2 (moderate improvement) in the L+LAP group compared with +1 (mild improvement) in the L group. Patients with deteriorating clinical dynamics over the five years preceding surgery had a significantly higher rate of improvement in clinical condition in V+L compared to L (81% versus 51%; p < 0.05) after seven years follow-up. Patients with stable preoperative clinical dynamics demonstrated a similar rate of improvement in both groups (96% versus 90%; p> 0.1). AVPs were not performed. REVIEWERS' CONCLUSIONS: These results indicate that ligation and valvuloplasty may have produced a moderate and sustained improvement for seven to ten years after surgery, in patients with mild to moderate DVI caused by primary valvular incompetence. However, there is insufficient evidence to recommend the treatment to this subgroup of patients, as the trials were small, used different methods of valvuloplasty and different methods of assessment.

Skeletal muscle ischaemia-reperfusion injury: further characterisation of a rodent model.

BACKGROUND: Postischaemic damage in skeletal muscle may be reflected in changes to microvascular blood flow, vascular permeability, and subsequent tissue viability. Previous preclinical studies have not addressed all these parameters, and have not used periods of ischaemia and reperfusion relevant to the clinical setting. This study aimed to develop an animal model hindlimb ischaemia-reperfusion to simulate acute lower limb ischaemia. METHODS: A rodent model of hindlimb tourniquet-induced ischaemia-reperfusion was employed. Gastrocnemius muscle blood flow (GMBF; radio-labelled microspheres), oedema (GMO; using a wet:dry ratio method) and viability (GMV; histochemistry and computerised planimetry) were quantified. RESULTS: 6 h ischaemia per seresulted in neither muscle oedema nor loss of viability, but these changes were apparent following 4 h reperfusion. Early reperfusion at 10 min demonstrated low reflow, with GMBF improving at 120 min before declining sharply at 240 min. CONCLUSION: Prolonged hindlimb ischaemia followed by reperfusion in this rodent model caused significant reductions in gastrocnemius muscle blood flow, associated with muscle oedema and necrosis. These three parameters have not been previously reported together in the same model. This reproducible model could be used in the evaluation of potential therapeutic intervention strategies aimed at ameliorating skeletal muscle reperfusion injury.

Leptin activation of ATP-sensitive K+ (KATP) channels in rat CRI-G1 insulinoma cells involves disruption of the actin cytoskeleton.

1. The role of the cytoskeleton in leptin-induced activation of ATP-sensitive K+ (KATP) channels was examined in rat CRI-G1 insulin-secreting cells using patch clamp and fluorescence imaging techniques. 2. In whole cell recordings, dialysis with the actin filament stabiliser phalloidin (10 microM) prevented KATP channel activation by leptin. 3. Application of the actin filament destabilising agents deoxyribonuclease type 1 (DNase 1; 50 microg ml-1) or cytochalasin B (10 microM) to intact cells or inside-out membrane patches also increased KATP channel activity in a phalloidin-dependent manner. 4. The anti-microtubule agents nocodazole (10 microM) and colchicine (100 microM) had no effect on KATP channel activity. 5. Fluorescence staining of the cells with rhodamine-conjugated phalloidin revealed rapid disassembly of actin filaments by cytochalasin B and leptin, the latter action being prevented by the phosphoinositide 3 (PI 3)-kinase inhibitor LY 294002. 6. Activation of KATP channels by the PI 3-kinase product phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) was also prevented by phalloidin. This is consistent with the notion that leptin activates KATP channels in these cells by an increase in PtdIns(3,4,5)P3 or a similar 3-phosphorylated phosphoinositol lipid, resulting in actin filament disruption.

Surgery for deep venous incompetence.

BACKGROUND: Chronic deep venous incompetence (DVI) is a troublesome condition with a range of symptoms in the legs including recurrent ulcers, pain and swelling. It is caused by incompetent vein valves and/or the blockage of large-calibre leg veins. OBJECTIVES: To establish the effectiveness of various surgical procedures for treating DVI. SEARCH STRATEGY: Trials were identified from the Cochrane Peripheral Vascular Diseases Group's Specialised Trials Register, reference lists of relevant studies, and through contact with principal investigators of identified trials and world experts in deep venous surgery. SELECTION CRITERIA: Randomised controlled trials of surgical treatment for patients with DVI. Trials were selected by AA and checked by SCH. DATA COLLECTION AND ANALYSIS: The reviewers extracted the data independently. A variety of outcome measures were reported including ambulatory venous pressure (AVP) and venous refill time (VRT). MAIN RESULTS: Only one trial met the inclusion criteria, none was excluded. The trial compared external valvuloplasty using limited anterior plication (LAP) in combination with ligature of incompetent superficial veins (ligation and LAP) against ligation only. The trial participants had primary valvular incompetence with mild to moderate symptoms but no venous ulcers. Ligation and LAP produced significant improvement in AVP: the mean difference between the Ligation and LAP group and the Ligation only group was -15 torr (weighted mean difference [WMD] -20.9, -9.0, confidence interval [CI] 95% fixed) at one year and -15 torr (WMD -21, -8.9, 95% CI fixed) at two years. However, there was no statistically significant improvement in VRT, the mean difference between the groups at one year was 2 seconds (WMD -2.7, 6.7; 95% CI fixed) and at two years was 4 seconds (WMD -0.7, 8.7; 95% CI fixed). AVP values after surgery remained relatively high. Nine out of eleven valves repaired remained competent after two years of follow up. No complications occurred. The overall mean score for clinical outcome was +2 (moderate improvement) in the Ligation and LAP group. This compared with +1 (mild improvement) in the Ligation only group. REVIEWER'S CONCLUSIONS: The results of one small trial showed that ligation and LAP produced a moderate improvement for two years after surgery, in patients with mild to moderate DVI caused by primary valvular incompetence. However, there is not sufficient evidence to recommend the treatment to this subgroup of patients with DVI.

Dual actions of the metabolic inhibitor, sodium azide on K(ATP) channel currents in the rat CRI-G1 insulinoma cell line.

1. The effects of various inhibitors of the mitochondrial electron transport chain on the activity of ATP-sensitive K+ channels were examined in the Cambridge rat insulinoma G1 (CRI-G1) cell line using a combination of whole cell and single channel recording techniques. 2. Whole cell current clamp recordings, with 5 mM ATP in the pipette, demonstrate that the mitochondrial uncoupler sodium azide (3 mM) rapidly hyperpolarizes CRI-G1 cells with a concomitant increase in K+ conductance. This is due to activation of K(ATP) channels as the sulphonylurea tolbutamide (100 microM) completely reversed the actions of azide. Other inhibitors of the mitochondrial electron transport chain, rotenone (10 microM) or oligomycin (2 microM) did not hyperpolarize CRI-G1 cells or increase K+ conductance. 3. In cell-attached recordings, bath application of 3 mM sodium azide (in the absence of glucose) resulted in a rapid increase in K(ATP) channel activity, an action readily reversible by tolbutamide (100 microM). Application of sodium azide (3 mM), in the presence of Mg-ATP, to the intracellular surface of excised inside-out patches also increased K(ATP) channel activity, in a reversible manner. 4. In contrast, rotenone (10 microM) or oligomycin (2 microM) did not increase K(ATP) channel activity in either cell-attached, in the absence of glucose, or inside-out membrane patch recordings. 5. Addition of sodium azide (3 mM) to the intracellular surface of inside-out membrane patches in the presence of Mg-free ATP or the non-hydrolysable analogue 5'-adenylylimidodiphosphate (AMP-PNP) inhibited, rather than increased, K(ATP) channel activity. 6. In conclusion, sodium azide, but not rotenone or oligomycin, directly activates K(ATP) channels in CRI-G1 insulin secreting cells. This action of azide is similar to that reported previously for diazoxide.

Liver dihydropyrimidine dehydrogenase activity in human, cynomolgus monkey, rhesus monkey, dog, rat and mouse.

Interspecies differences in dihydropyrimidine dehydrogenase (DPD), the initial and rate-limiting enzyme in pyrimidine degradation, were assessed in cytosol from livers isolated from human, monkey, dog, rat, and mouse. Hepatic DPD activity was measured by an HPLC assay with on-line radioactivity detection, using 14C-5-fluorouracil as a substrate. Activity was highly variable within each species and significant interspecies differences in liver DPD activity were observed. The order of activity was mouse > rat > human > dog > or = cynomolgus monkey > rhesus monkey. These data suggest that careful selection must be made when choosing in vivo models of human DPD for the preclinical development of novel fluoropyrimidine anticancer agents and DPD inhibitors.

Autoregulation of 5-fluorouracil metabolism.

5-Fluorouracil (5-FU) is a commonly used anticancer agent for the treatment of gastrointestinal, head and neck, and breast tumours. This study determined the influence of 5-FU on dihydropyrimidine dehydrogenase (DPD) activity, the enzyme responsible for its in vivo degradation. DPD activity was measured in mononuclear cells obtained prior to and after the administration of 5-FU in 20 patients with colorectal cancer. Following the results from the human studies, DPD activity was measured in Sprague-Dawley rat liver up to 72 h after administration of 5-FU 200 mg/kg as a single injection. Total liver P450 content and the production of testosterone metabolites (indicative of CYP3A activity) were also analysed to determine the specificity of 5-FU-associated alteration in rat liver metabolism. Human mononuclear cell DPD activity decreased by a median of 38.7% following the administration of 5-FU (P = 0.001). 5-FU-induced alterations in rat liver DPD were also observed, with the lowest activity occurring 48 h after injection (50% of control activity; P = 0.009). Rat liver DPD activity returned to near control values by 72 h postinjection. Rat liver total P450 content and CYP3A activity were not significantly different in 5-FU treated or control tissues. Thus, 5-FU demonstrates autoregulation of its metabolism through inhibition of DPD activity. Although this inhibition appears to be specific for DPD, the mechanism for enzyme inhibition is not clear. These findings may aid in the design of 5-FU treatment regimens and provide the basis for further studies into the regulation of DPD.

Neutrophil activation in jugular venous blood during carotid endarterectomy.

OBJECTIVES: Neutrophils may play an important role in cerebral ischaemia. We investigated whether neutrophil activation can be detected in cerebral venous blood during the mild cerebral hypoxia and reperfusion that occurs during carotid cross clamping and declamping for endarterectomy. DESIGN, SETTING AND MATERIALS: The ipsilateral jugular bulb was cannulated at operation in 16 patients undergoing carotid endarterectomy. Blood was taken immediately prior to and 30 seconds following internal carotid cross clamping; then immediately prior to, 30 s and 2 m following declamping. Blood was also taken from a peripheral vein in the foot. Intracerebral oxygen saturation (CsO2) was measured continuously by near infrared cerebral spectroscopy. Neutrophil activation was measured by flow cytometric detection of fluorescence to hydrogen peroxide in unstimulated cells and phorbol myristate acetate stimulated cells, and expressed as mean fluorescent intensity (MFI). OUTCOME MEASURES: Neutrophil activation and cerebral oxygenation. MAIN RESULTS: CsO2 fell from 68% (95% Confidence interval 64%-72%) to 63% (59%-68%) following carotid cross clamping (p < 0.05, repeated measures analysis of variance). This recovered slightly during the cross clamp period to 64% but only returned to preclamp levels following declamping (p > 0.05). Neutrophil hydrogen peroxide generation by stimulated neutrophils rose significantly from 0.79 mean fluorescent intensity (0.53-1.19) to 1.46 (0.98-2.20) but no there was no further rise following cross clamp release. There was no significant neutrophil activation in the peripheral samples. CONCLUSIONS: These results indicate that even mild cerebral hypoxia is associated with priming of neutrophils in cerebral venous blood.

Fat and cholesterol in the diet of infants and young children: implications for growth, development, and long-term health.

Fat is necessary in the diets of infants and young children because of their extraordinary energy needs and limited dietary capacity. In addition, essential fatty acids provide the substrates for arachidonic acid, docosahexaenoic acid, and their metabolites. Deficiencies in the amounts of these long-chain fatty acids in the diet during infancy may affect the maturation of the central nervous system, including visual development and intelligence. Efforts to link the diet in infancy and early childhood to the development of chronic diseases in adulthood are hampered by a lack of supportive epidemiologic and clinical data. Serum cholesterol and lipid levels during childhood correlate only weakly with their levels at maturity. Studies in twins suggest that there is a large genetic component to serum lipid levels. Similarly, the correlation between obesity in early childhood and in adulthood is weak. Young children who receive fat-restricted diets in which fat accounts for 30% or less of their intake appear to grow normally but are more likely not to consume the recommended dietary allowances of many nutrients. Therefore fat should not be restricted in the diets of infants and young children. Restricting fat to approximately 30% of the calories consumed is reasonable after the age of 2 years, but the benefits of this recommendation remain to be proved.

Cerebral hypoxia detected by near infrared spectroscopy.

Near infrared spectroscopy is a relatively new technique for monitoring intracerebral oxygen saturation. Using the technique, three episodes of cerebral hypoxia were detected during elective carotid endarterectomy which were not reliably recorded by more standard monitoring of cerebral perfusion. In one case, cerebral hypoxia was related to slippage of the tracheal tube into the right main bronchus and in the other two to episodes of hypotension. Near infrared spectroscopy is a reliable indicator of peripheral cortical perfusion and provides continuous and noninvasive monitoring of intracerebral oxygen saturation.

Primary antral gastritis in young American children. Low prevalence of Helicobacter pylori infections.

Although Helicobacter pylori (H. pylori) is considered by many to be the major cause of primary antral gastritis (PAG), several important questions concerning its pathogenetic role remain unanswered. The most basic unresolved issue relates to the low prevalence of H. pylori in children in developed countries. If H. pylori is the cause of PAG, the prevalence of PAG should also be low, but previous studies have not provided data on this issue. To answer this question, we prospectively studied 408 children who underwent esophagogastroduodenoscopy and biopsy from January 1, 1988, to December 31, 1990, for symptoms consistent with peptic disease or immunocompromise. Although the prevalence of PAG was similar (about 20%) in the four age groups of patients studied (< 5, 5-9, 10-14, and 15-20 years), the prevalence of H. pylori infections was significantly greater in the oldest age group (67%, P < 0.0001). Only four of 39 children < 10 years old with PAG had evidence of H. pylori. H. pylori is an uncommon finding in our population of young American children with PAG, indicating that it does not play an important role in the pathogenesis of this disorder in this age group.

The superior mediastinal approach to hepatic malignancy.

A 26-year-old man presented with superior vena caval obstruction. He underwent excision of a malignant teratoma which contained benign hepatic tissue. Three years later he represented with a recurrence and underwent a second resection. Histology of the resected specimen demonstrated hepatocellular carcinoma arising in the hepatic component of the recurrent malignant teratoma intermediate.

A prospective randomized clinical trial of liver preservation using high-sodium versus high-potassium lactobionate/raffinose solution.

High-sodium as opposed to high-potassium lactobionate/raffinose preservation solution offers potential advantages in improving the quality of liver storage by reducing potassium-induced vasoconstriction and preventing hyperkalaemia on reperfusion. In our study we evaluated in a prospective trial (encompassing 40 consecutive cadaver donor hepatic retrievals and subsequent transplants) the efficacy of a high-sodium formulation versus the standard high-potassium solution. Quality of preservation was assessed by clinical indices of liver function in the intraoperative and early postoperative phases, including measurements of requirements for blood and blood products and potassium, circulating liver enzymes and bilirubin. Frequencies of acute rejection episodes and primary non-function were also recorded. No significant differences were evident in any of the measured parameters. Thus a sodium-based solution can be used for hepatic preservation, advancing the possibility that it may be possible to develop a single storage solution for clinical multi-organ donor operations.

Reversal of the post-ischaemic changes in skeletal muscle blood flow and viability by a novel inhibitor of lipid peroxidation.

The role of a novel inhibitor of lipid peroxidation (U74500A) in modifying post-ischaemic changes in skeletal muscle blood flow, viability and oedema has been investigated in a rat model of 6 h unilateral hindlimb ischaemia followed by 4 h reperfusion. During reperfusion, gastrocnemius muscle blood flow (GMBF) was measured (radiolabelled microspheres) at 10, 120 and 240 min and a perfusion index (PI) calculated between the reperfused and contralateral normal limb. Muscle viability (GMV--nitroblue tetrazolium) and oedema (wet:dry weight ratio, reperfused: contralateral limb) were assessed after 4 h reperfusion. GMBF in untreated controls, compared to normal animals, demonstrated a triphasic pattern of low reflow at 10 min [PI 0.08 (0.01-0.13) vs. 1.05 (0.68-1.18), p < 0.01], relative reperfusion at 120 min [PI 0.29 (0.09-0.59) vs. 0.97 (0.79-1.13), p < 0.05] and reperfusion injury at 240 min [PI 0.05 (0.01-0.14) vs. 1.01 (0.73-1.16), p < 0.01] with a median GMV at 240 min of 52.9% (33.3-61.4), p < 0.01 vs. normals and 6 h ischaemia alone (GMV 100% in all limbs) and an oedema index of 1.23 (1.09-1.37 p < 0.01 vs. normal. In contrast, rats receiving U74500A (2 mg/kg i.v. infusion commencing 30 min prior to revascularisation) exhibited enhanced GMBF throughout reperfusion [PI 10 min: 3.26 (2.56-3.63); 120 min: 2.03 (1.73-2.25); 240 min: 2.13 (1.75-2.44), p < 0.01 vs. controls and normals] with complete muscle salvage [GMV 100% in all reperfused muscles, p < 0.01 vs. controls, not significant (NS) vs. normals and 6 h ischaemia].(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of free radical scavenging on skeletal muscle blood flow during postischaemic reperfusion.

After 6-h tourniquet ischaemia of one hindlimb in male Sprague-Dawley rats, gastrocnemius muscle blood flow was measured following 10, 120 and 240 min of reperfusion using radiolabelled microspheres. A perfusion index was calculated (experimental limb: contralateral limb) for each of these times. Comparison of perfusion indices in ten control animals (6 h ischaemia, 4 h reperfusion) with similar measurements in ten normal rats with no ischaemia and in ten ischaemic animals with the tourniquet in situ demonstrated low median (interquartile range (i.q.r.)) reflow after 10 min (control 0.12 (0.02-0.43), ischaemia 0.04 (0.00-0.07), normal 1.05 (0.68-1.18); control versus ischaemia, P not significant; control versus normal, P < 0.01). Relative reperfusion occurred at 120 min (control 0.48 (0.11-0.70), ischaemia 0.02 (0.01-0.07), normal 0.97 (0.79-1.13); control versus ischaemia, P < 0.05; control versus normal, P < 0.05) and reperfusion injury after 240 min of revascularization, with muscle blood flow being little different from that in the ischaemic group (control 0.05 (0.01-0.38), ischaemia 0.03 (0.00-0.07), normal 1.01 (0.73-1.16); control versus ischaemia, P not significant; control versus normal, P < 0.01). Two groups of 12 rats were given either intravenous superoxide dismutase and catalase or dimethylthiourea 30 min before tourniquet release, continuing throughout the period of reperfusion. Superoxide dismutase and catalase reversed low reflow, producing a median (i.q.r.) perfusion index of 0.94 (0.54-1.12) (P < 0.01 versus control, P not significant versus normal), but had no effect on relative reperfusion (0.66 (0.42-1.01), P not significant versus control) or on reperfusion injury (0.27 (0.01-0.35), P not significant versus control). In contrast, dimethylthiourea had no effect on perfusion at either 10 min (0.10 (0.03-0.15), P not significant versus control) or 240 min (0.04 (0.00-0.11), P not significant versus control), but abolished the phase of relative reperfusion at 120 min (0.04 (0.02-0.21), P < 0.01 versus control). These results indicate that, although superoxide radicals are harmful during postischaemic reperfusion, hydroxyl radicals may be beneficial.

Localization of nuclear matrix proteins (NMPs) in multiple tissue types with NM-200.4 (an antibody strongly reactive with NMPs found in breast carcinoma).

Nuclear matrix proteins (NMP) are nonhistone proteins found in the nucleus of many eukaryotic cells. Furthermore certain NMPs are reported to be cell-type specific and expressed differentially by malignant cells. To study the specificity of NM-200.4 (an antibody reactive to NMPs extracted from cultured breast carcinoma cells of the T-47D line), cancers and benign tissues from multiple body sites were surveyed. All 17 breast carcinomas showed strong reactivity to tumor cell nuclei. Also nuclei from one of two lung carcinomas, a papillary thyroid carcinoma, an ovarian fibroma, and a lymphoma were strongly reactive. One leiomyosarcoma and a dermoid cyst were negative. Although 1 benign breast with duct hyperplasia showed moderate reactivity, only 1 of 10 benign breast biopsies without hyperplasia showed reactivity. Three of 4 skin biopsies, 2 liver biopsies, 6 of 9 kidney biopsies, and 5 of 10 gastrointestinal mucosal biopsies showed reactivity in benign nuclei. It is concluded that, although breast carcinoma nuclei showed the most consistent reactivity for NM-200.4, both benign and malignant nuclei from other body sites also show reactivity.

Pharmacological manipulation of gastrocnemius muscle blood flow in an animal model of reperfusion injury.

Despite technically satisfactory surgery for acute lower limb ischaemia reperfusion injury may result in failure of limb salvage and the need for amputation. An animal model using the rat hind limb has been developed which demonstrates this complication. A tourniquet was applied to one hind limb for 6 h and then released. Gastrocnemius muscle blood flow in both hind limbs was assessed using radiolabelled microspheres and a perfusion index calculated between the revascularized and normal hind limbs and the results compared with similar measurements in control animals and rats with a tourniquet still in situ (ischaemic). Following 10 min the median perfusion index in reperfused animals was significantly less than that in control animals (0.12 +/- 2 inter-quartile range 0.02-0.43) versus 1.05 (0.68-1.18), P less than 0.01) but similar to the results in rats with a tourniquet still in situ [0.04 (0.00-0.07), ns], thus demonstrating low reflow following tourniquet release. After 120 min revascularization a phase of relative reperfusion occurred with perfusion indices becoming higher than those in animals with a tourniquet in situ (0.48 (0.11-0.70) versus 0.02 (0.01-0.07), P less than 0.05) but remaining lower than those in control rats [0.97 (0.79-1.13), P less than 0.05]. Finally after 240 min, reperfusion injury occurred with perfusion being similar to that in animals with a tourniquet applied [0.05 [0.01-0.38) versus 0.03 (0.00-0.07), ns] and less than that in the normal rats [1.01 (0.73-1.16), P less than 0.01].(ABSTRACT TRUNCATED AT 250 WORDS)