Long saphenous vein stripping reduces local level of reactive oxygen metabolites in patients with varicose disease of the lower limbs

Long saphenous vein (LSV) stripping is the most common surgical procedure in patients affected by varicose disease of the lower limbs. Reactive oxygen metabolites (ROM) generation plays a crucial role in chronic venous insufficiency (CVI). The aim of this study was to investigate whether ROM generation is increased in patients affected by varicose disease versus healthy controls and whether LSV stripping has a positive effect on the local production of ROM. The local production of ROM was assessed measuring hydroperoxides in the blood collected from the leg of 30 patients consecutively undergoing LSV stripping and 30 controls. In both the patient group and the control group, the test was repeated 30 days later. We found that ROM levels before surgery are higher in varicose vein patients than in controls ( p <.0001) and that ROM are significantly reduced 30 days after LSV stripping ( p <.0001). At that time point, no significant differences between patients and controls was found. We also found that sex and age do not affect ROM concentration in patients and controls, either before or after surgery. In conclusion, our data indicate that CVI is characterized by significant oxidative stress and that LSV stripping is able to normalize local production of ROM in patients with varicose disease of the lower limbs. We suggest that measurement of ROM might be useful to test the positive effects of LSV stripping in these patients.

Single copy of variant CYP2A6 alleles does not confer susceptibility to liver dysfunction in patients treated with coumarin

OBJECTIVE

Coumarin, used in the treatment of chronic venous diseases, is mainly metabolized to non-toxic 7-hydroxy-coumarin by CYP2A6. At least, 3 variant alleles, CYP2A6*2, CYP2A6*3 and CYP2A6*4A, have been shown to encode catalytically defective proteins. Sporadic elevation of liver enzymes has been reported on the chronic administration ofcoumarin. We sought to determine if susceptibility to coumarin-associated liver dysfunction is genetically determined by polymorphism in CYP2A6 and impairment of the 7-hydroxylation ofcoumarin. Additionally, we were interested in the effect of polymorphism on smoking because of the predominant role of CYP2A6 in the metabolism of nicotine.

METHODS

The investigation was performed prospectively within a randomized double-blind clinical trial of the coumarin-containing drug SB-LOT (90 mg coumarin + 540 mg troxerutin/d) vs. placebo in 231 German patients with chronic venous insufficiency. Monitoring of the hepatic status involved regular measurements of liver function during the 16-week treatment. Genotyping of CYP2A6 was carried out by means of PCR and confirmed by DNA sequencing analysis.

RESULTS

The allelic frequencies of the variant CYP2A6*2 and CYP2A6*3 alleles were 0.023 and 0.014, respectively. There was no significant difference in the incidence of liver dysfunction between heterozygotes with CYP2A6*2, CYP2A6*3 and wild-type homozygotes. CYP2A6 polymorphism had no significant effect on smoking behavior.

CONCLUSION

No evidence was obtained that the studied polymorphism in CYP2A6 is a determinant of the coumarin-associated liver dysfunction.

Inflammatory mechanisms involving neutrophils in chronic venous insufficiency of lower limbs

BACKGROUND

It is supposed that an inflammatory reaction is one of the major factors responsible for the chronic venous insufficiency (CVI) of lower limbs which cause leg ulcers.

OBJECTIVES

The main objective of the present study was to determine the differences in the levels of typical inflammatory mediators and markers produced by neutrophils of patients with CVI and normal control subjects.

SUBJECTS AND METHODS

26 patients with CVI and 39 clinically healthy subjects were included in the study. In peripheral neutrophils of both groups the production of superoxide, total reactive oxygen intermediates and activities of lysosomal enzymes were measured together with the expression of 8 adhesion molecules.

RESULTS

Increased formation of superoxide by patient neutrophils and activities of elastase in both neutrophils and serum of patients were demonstrated. On the contrary, activities of myeloperoxidase and beta-D-glucuronidase were decreased in patient neutrophils. Comparing to control group adhesion molecules CD11b, CD18, CD31, CD49d, CD54 and CD62L were increased on the surface of patient neutrophils whereas no differences were observed in the expression of CD11a abd CD15.

CONCLUSION

The neutrophils of patients with CVI are primed and/or activated because they are able to release higher amount of superoxide, lysosomal enzymes and express elevated number of adhesion molecules. It may serve as one of the important evidences of an inflammatory mechanism involved in the pathogenesis of chronic venous insufficiency. (Tab. 3, Ref. 27.)

Role of matrix metalloproteinases 1, 2, and 9 and tissue inhibitor of matrix metalloproteinase-1 in chronic venous insufficiency

PURPOSE

Increased transforming growth factor-beta(1) (TGF-beta(1)) activity is associated with chronic venous insufficiency (CVI) disease progression and dermal skin pathology. Because TGF-beta(1) stimulates collagen synthesis and alters the levels of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs), we investigated the hypothesis that increased TGF-beta(1) activity is associated with differences in messenger RNA and protein levels of MMPs and TIMP-1 in patients with CVI.

METHODS

One hundred ten biopsies of the lower calf and lower thigh in 73 patients were snap frozen in liquid nitrogen and stratified into six groups according to the clinical etiologic anatomic distribution pathophysiology disease classification. One set of lower-calf and lower-thigh biopsies were analyzed for MMP-1 and TIMP-1 gene expression with quantitative reverse transcription and competitive polymerase chain reaction. A second set of biopsies was analyzed for the active and latent forms of MMP-1, MMP-2, and MMP-9 as well as for TIMP-1 by western blotting, gelatin zymography, and tissue localization by immunohistochemistry (IHC).

RESULTS

Compared with the control, MMP-1 messenger RNA was increased in class-4 and class-6 patients (P < or =.01), whereas TIMP-1 was increased in class-6 patients only (P < or =.05). However, there were no differences in total protein between MMP-1 and TIMP-1. Active MMP-2 protein increased in class-4 and class-5 patients compared with active MMP-1 and TIMP-1 (P < or =.01). Western blotting did not identify the active component of MMP-9. Similarly, only the latent form of MMP-9 was observed by gelatin zymography, whereas both the latent and active forms of MMP-2 were observed. IHC demonstrated MMP-1 and MMP-2 in dermal fibroblasts and in perivascular leukocytes. TIMP-1 was observed in basal-layer keratinocytes of the epidermis only. MMP-9 was not detected by IHC.

CONCLUSION

MMP synthesis is regulated at both the transcriptional and post-transcriptional levels in CVI. Our data suggest that post-translational modifications are key to functional regulation. Dermal fibroblasts and migrating leukocytes are probable cellular sources of MMPs. Increased active MMP-2 levels in class-4 and class-5 patients indicate tissue remodeling caused by pre-ulcer and postulcer environmental stimuli. These data suggest that alterations in MMP-2 activity, in conjunction with TGF-beta(1)-mediated events, cause an imbalance in tissue remodeling leading to a pro-ulcer-forming environment.

Regulation of adhesion molecules: a new target for the treatment of chronic venous insufficiency

As more insight into the mechanisms leading to chronic venous insufficiency (CVI) is gained, novel targets for drug treatment of the disease, or of its complications, become available. Studies using chemical entities capable of inhibiting leukocyte adhesion in postcapillary venules have led to the discovery of selective inhibitors of cell adhesion mechanisms. The aim of the current review is to describe the pharmacology, biochemistry, and molecular biology studies performed with some new inhibitors of adhesion molecule expression. Compounds such as hydroxy triallyl farnisine (S 17834) may offer new and efficient treatment of the microcirculatory complications that accompany chronic venous disease.

Could gut-liver function derangements cause chronic venous insufficiency?

Upregulation of adhesion molecules and neutrophil infiltration of venous valve cusps may be risk factors for chronic venous insufficiency. But studies that focus on the target organ (vein) fail to consider the influence of systemic inflammation on WBC behavior in the microcirculation. This study probes the gut-liver axis as a potential source of gut-derived oxidative stress and free radical production leading to white blood cell activation in chronic venous insufficiency. Venous hemodynamics (ambulatory venous pressure, air plethysmography, duplex) and gut-derived oxidative stress markers were studied in nine patients with chronic venous insufficiency (group I) and nine age- and sex-matched control subjects with no venous disease (group II). Group I had healed venous ulcers (class 5, CEAP) but near-normal ambulatory venous pressure, to eliminate high ambulatory venous pressure as a chronic venous insufficiency risk factor. Markers of gut-derived oxidative stress included: stool analysis; intestinal permeability; hepatic detoxification challenges with caffeine, salicylate, and acetaminophen; and urine lipid peroxides. Ambulatory venous pressure did not significantly differ (group I, 42.5 +/- 5.3 mm Hg; group II, 35.5 +/- 5.5 mm Hg; p = NS). Candida overgrowth in stool distinguished group I from group II (7/9 pts vs 1/9 pts, respectively; p = 0.015). Increased intestinal permeability (lactulose/mannitol ratio) was prevalent in both groups (group I 0.07 +/- 0.02, group II 0.17 +/- 0.08, p = NS; normal range, 0.01-0.03). Both groups showed similar incidence of elevated urine lipid peroxides (5/9 pts vs 6/9 pts, respectively; p = NS), yet group I exhibited underfunction of both sulfation (group I 16.8 +/- 2.9%, group II 43.3 +/- 11%, p<0.03; normal acetaminophen recovery 16-36%) and glucuronidation (group I 30.4 +/- 4.1%, group II 64.1 +/- 14.4%, p<0.04; normal acetaminophen recovery 27%-56%) relative to oxidative stress, perhaps an indicator of diminished antioxidant capacity in patients with chronic venous insufficiency. Gut dysbiosis (as indicated by stool yeast) and hepatic detoxification challenge pathway exhaustion may lead to subclinical, systemic inflammation and peripheral white blood cell adhesion in chronic venous insufficiency. Further exploration of the relationship between oxidative stress and venous disease is needed.

Expression of adhesion molecules and cytokines on saphenous veins in chronic venous insufficiency

The objective of this study was to assess the relationship of signaling molecules to monocyte/ macrophages as a precursor to venous valve and venous wall dysfunction in patients with varicose veins. One of the hallmarks of venous dysfunction is destruction of venous valves with subsequent reflux and elevation of distal venous pressure. We recently observed that monocytes/macrophages migrate into the venous walls and valves of patients with venous insufficiency. There, they may play a role in the pathogenesis of primary venous insufficiency. If so, an important element in their performance would be the interaction between the monocytes and the endothelium as a precursor of damage to venous valves and the venous wall. To explore this interaction, immunohistochemistry was carried out to detect adhesion molecules and cytokines in surgical specimens removed during surgical therapy. Twenty-four surgical specimens consisting of proximal saphenous vein and subterminal valve were obtained using minimally traumatic technique in 6 males and 18 females who ranged in age from 31 to 79 years. Reflux was confirmed preoperatively by duplex technique, and severity was classified by the CEAP classification of the American Venous Forum. Ten patient limbs were class 2, eight were class 3, four were class 4, and two were class 6. The venous specimens were labeled using monoclonal antibody against ICAM-1, E-selectin, IL-1alpha, and TNF-alpha. CD68 was used for detection of monocytes/macrophages. Our results indicate that not only luminal venous endothelium but also endothelium in the vasa vasora of refluxing saphenous veins is activated, as indicated by the up-regulation of ICAM-1. However, IL-1alpha and TNF-alpha were increased in only selected specimens and are mainly detected in the vein wall. The factors that serve as trigger mechanisms to activate cells in the pathogenesis of primary venous dysfunction remain to be explored.

Effect of oral micronized purified flavonoid fraction treatment on leukocyte adhesion molecule expression in patients with chronic venous disease: a pilot study

PURPOSE

The purpose of this study was to determine the effects of a micronized purified flavonoid fraction treatment on surface expression of leukocyte adhesion molecules in chronic venous disease (CVD).

METHODS

Twenty patients with chronic venous disease were assessed with the use of clinical and Duplex scanning criteria. Consenting patients were treated for 60 days with a micronized purified flavonoid fraction treatment (500 mg twice daily). Blood was collected from a foot vein immediately before the start of treatment and within 1 week after the treatment was stopped. Neutrophil and monocyte surface adhesion molecule expression was determined by flow cytometry using the monoclonal antibodies to CD11b and CD62L.

RESULTS

Neutrophil CD11b (248:212), monocyte CD11B (204:190), neutrophil CD62L (130:97 [P =.002]), and monocyte CD62L (170:121 [P =.03]) were determined, respectively, before and after treatment. All values are arbitrary units and represent median values.

CONCLUSION

Micronized purified flavonoid fraction treatment for 60 days seems to decrease the surface expression of CD62L by neutrophils and by monocytes. The clinical significance of this finding needs to be explored further. It is feasible to use changes in the levels of these molecules as a marker for response to therapy in chronic venous disease.

Local oxygen content in the skin is increased in chronic venous incompetence

In skin lesions of chronic venous incompetence (CVI) transcutaneous oxygen pressure (tcpO(2)) at the ankle is often reduced. However, in some CVI patients the tcpO(2) during suprasystolic occlusion remains significantly higher than in healthy subjects. The aim of the present study was to investigate which kind of CVI patients develop this phenomenon and whether the higher tcpO(2) during occlusion is caused by a smaller oxygen consumption of the skin or by an increased local oxygen content. The oxygen consumption of the skin was measured by the pO(2) decrease (DeltatcpO(2)/Deltat) after stopping the arterial oxygen supply when the hemoglobin was saturated by oxygen inhalation, i.e., at tcpO(2) values above 120-130 mmHg. By multiplying the tcpO(2) with the mean oxygen solubility coefficient of the skin the content of physically dissolved oxygen is obtained. The decrease of tcpO(2) in the 55- to 45-mmHg range indicates the consumption of oxygen physically dissolved and chemically bound to hemoglobin. It gave a parameter for estimating the local hemoglobin content of the skin. These values and the minimal tcpO(2) after a 5-min arterial occlusion were measured in 14 healthy subjects, in 13 patients with varicose veins, but no skin lesions, in 10 patients with CVI lesions like white atrophy and lipodermatosclerosis and in 16 CVI patients with open venous ulcers. During suprasystolic occlusion tcpO(2) at the ankle remained significantly higher in CVI patients with skin lesions than in the healthy control subjects (25.6 +/- 18.9 versus 8.0 +/- 7.0 mmHg). The steepness of the tcpO(2) decrease caused by cutaneous oxygen consumption in healthy subjects was not significantly different from the CVI patients. In contrast, the decrease of tcpO(2) at the ankle between 55 and 45 mmHg was 1.9 +/- 2.0 mmHg/s in the control group and 0.7 +/- 0.5 mmHg/s in the group with open venous ulcers. These results indicate a higher hemoglobin content in the skin of the CVI patients than in healthy subjects. Obviously, the hemoglobin bound oxygen content in the skin of CVI patients is increased. Thus, a lack of oxygen is unlikely to be the primary reason for the development of skin lesions in CVI.

The effect of passage number on fibroblast cellular senescence in patients with chronic venous insufficiency with and without ulcer

BACKGROUND

Fibroblasts (fb) cultured from venous ulcer patients and patients with venous reflux disease without ulcer demonstrate characteristics of cellular senescence, such as increased fibronectin level and senescence-associated beta-galactosidase (SA beta-gal) positive cells. Cellular senescence is an in vitro event characterized by the progressive loss of proliferative capacity with increased passage number, and has been associated with impaired healing in vivo. This report examines progressive stages of cellular senescence in fb from the distal area (du-fb) and proximal fb (pu-fb) of patients with venous ulcer, as well as in distal fb (dr-fb) and proximal fb (pr-fb) from patients with venous reflux without ulcer, by comparing the population doubling time (T) and percent SA beta-gal expression.

RESULTS

The mean value of T over 6 passages for fb in the ulcer group was 132.5 +/- 29.0 hours for pu-fb and 492.9 +/- 146.2 hours for du-fb (P = 0.0009). For fb in the reflux group the mean value of T over 5 passages was 79.3 +/- 12.8 hours for pr-fb and 94.2 +/- 16.8 hours for dr-fb (P = 0.8). Comparing ulcer and reflux fb, no difference in T was observed between pu-fb and pr-fb (P = 0.6), but a difference was noted between du-fb and dr-fb (P = 0.0004). The mean percent SA beta-gal activity for fb in the ulcer group was 11.2% +/- 3.1% for pu-fb and 63.8% +/- 8.9% for du-fb (P = 0.0001). Individual passages demonstrated significant difference (P <0.05) in SA beta-gal activity between pu-fb and du-fb at early and late passages. No difference was noted in SA beta-gal activity for fb in the reflux group or between pu-fb and pr-fb, but comparison between du-fb and dr-fb was significant (63.8% +/- 8.9% versus 7.8% +/- 2.9%; P = 0.0001).

CONCLUSIONS

The in vitro passage of du-fb and pu-fb in chronic venous ulcer patients has an effect on T and cellular senescence as measured by SA beta-gal activity. Our data further suggest that du-fb are at a more progressive stage of cellular senescence when compared with pu-fb, and more importantly with fb cultured from patients with venous reflux without ulcer. These findings are consistent with impaired wound healing of venous stasis ulcer. The accumulation of senescent fb and a more advanced stage of cellular senescence of du-fb may explain why repeated episodes of venous ulceration are resistant to conservative treatment and require more aggressive measures of therapy.

Expression of the adhesion molecules ICAM-1, VCAM-1, LFA-1 and VLA-4 in the skin is modulated in progressing stages of chronic venous insufficiency

In inflammation and wound healing, dynamic changes in cell adhesion and migration are fundamental properties of the cells involved. Disturbed interaction of leukocytes with microvascular endothelial cells has been proposed to be a central pathogenic factor in chronic venous insufficiency. This disease may therefore serve to elucidate dysregulated modulation of adhesion molecule expression in conditions of chronic inflammation and impaired wound healing. In this study, we determined how the expression of ICAM-1/VCAM-1 on endothelial cells and their ligands LFA-1/VLA-4 on leukocytes is modulated in skin of progressing stages of chronic venous insufficiency. Immunohistochemical staining of skin biopsies revealed an increase in the expression of ICAM-1 and VCAM-1 on endothelial cells in an early stage of venous disease such as stasis dermatitis. Such protein expression correlated with an increase of corresponding mRNA in skin biopsies. Expression of these CAMs on endothelial cells was accompanied by the occurrence of a marked perivascular infiltration of leukocytes, which expressed increased levels of LFA-1 and VLA-4. In progressing stages of chronic venous insufficiency, characterized by hyperpigmentation and lipodermatosclerosis, which precede skin ulceration, all these CAMs remained upregulated on endothelial cells and infiltrating leukocytes. Our findings indicate that following an initial peak expression during stasis dermatitis, vascular ICAM-1 and VCAM-1 expression is not downmodulated to baseline levels, but remains upregulated. This possibly promotes tissue damage by a perpetuated, upregulated influx of activated leukocytes, finally leading to skin ulceration.

Comparison of IL-10 levels in chronic venous insufficiency ulcers and autologous donor tissue

In previous immunohistochemical studies, chronic venous insufficiency (CVI) ulcers have been shown to display positive staining for interleukin-10 (IL-10), while other wounds (including autologous donor wound tissue) show a reduced staining level. IL-10 inhibits the synthesis of many proinflammatory cytokines, while also inhibiting antigen presentation by antigen-presenting cells. It is possible that abnormally high amounts of IL-10 in chronic wounds may be related to the failure of these wounds to progress to final wound healing. The purpose of this study was to quantify the levels of IL-10 in CVI ulcers and autologous donor tissue using Western blotting. Extracts were prepared from frozen wound tissue samples and equal amounts of protein were concentrated by immune-precipitation for Western blot analysis. Densitometric analysis was performed on nonsaturated chemilumigraphs and normalized to an IL-10 standard run on each gel. The quantity of IL-10 in CVI ulcers was found to be 490% of the quantity in autologous donor tissue. This study provides confirmatory quantitative data which supports previous immunohistochemical findings showing elevated levels of IL-10 in CVI ulcers.

Patterns of epidermal growth factor receptor, basic fibroblast growth factor and transforming growth factor-beta3 expression in skin with chronic venous insufficiency

Growth factors which act as signalling peptides through specific cell surface receptors are involved in functions such as cell proliferation, migration, and differentiation. Here, we report on alterations of the epidermal growth factor receptor (EGFR), basic fibroblast growth factor (bFGF) and transforming growth factor beta3 (TGF-beta3) expression patterns in the skin at various stages of chronic venous insufficiency (CVI). Thirty punch biopsies were taken from patients with CVI and growth factors or the growth factor receptor were detected by indirect immunofluorescence and immunoperoxidase techniques. EGFR, bFGF, and TGF-beta3 expression is strongly increased in the stroma of venous eczema and in leg ulcer skin, and to a lesser extent in the dermis of patients with lipodermatosclerosis. Venous eczema and lipodermatosclerosis epidermis show an elevated EGFR and bFGF synthesis throughout all strata. In the different CVI stages, telangiectases and reticular veins and pigmentation EGFR and bFGF staining are limited to the basal layer. We conclude that the alterations in the expression of EGFR, bFGF and TGF-beta3 precede changes in the affected skin within progressing stages of CVI. The exact mechanisms of growth factor involvement in the pathogenesis of venous ulceration remain to be resolved.

Increased expression of platelet-derived growth factor receptor alpha and beta and vascular endothelial growth factor in the skin of patients with chronic venous insufficiency

Growth factors produced by a variety of cells act as signalling peptides through specific cell surface receptor pathways. Functions such as cell proliferation, migration and differentiation have been assigned to each of them. Here, we report alterations of platelet-derived growth factor receptor alpha (PDGFR-alpha) and beta (PDGFR-beta) and vascular endothelial growth factor (VEGF) expression patterns in the progressive clinical stages of chronic venous insufficiency (CVI). A total of 30 punch biopsies were taken from patients with CVI, and VEGF and PDGFR were detected by indirect immunofluorescence and immunoperoxidase techniques. PDGFR-alpha and PDGFR-beta expression was strongly increased in endothelial cells of capillaries, pericapillary cells and connective tissue cells in the stroma of the skin of venous eczema and venous leg ulcer patients, and to a smaller extend in the dermis of those with lipodermatosclerosis. VEGF staining showed a similar expression pattern in the progressive CVI stages. However, staining of vessels in particular might simply reflect binding of VEGF, secreted by keratinocytes or fibroblasts, to its receptors. Growth factor and receptor expression in specimens from telangiectases and reticular veins, and from pigmented areas, resembled that of normal skin. We conclude that PDGFR-alpha, PDGFR-beta and VEGF play an important role in mediating inflammation and epithelial hyperproliferation in venous eczema, inducing connective tissue sclerosis in lipodermatosclerosis, and causing the reduced reepithelialization tendency in venous ulcers. We speculate that endothelial proliferation with chronic venous hypertension might be mediated by these growth factors.

Levels of the inhibitor of PMN-elastase in venous blood reflowing from chronically affected veins: the role of venous stasis

BACKGROUND

Attention has recently been paid to the cell and biochemical disorders involved in chronic venous insufficiency (CVI) and to their possible relationship to the endothelium.

METHODS

In the present study, carried out in 14 patients with CVI, we evaluated the levels of the inhibitor of elastase (I-EL) generated by polymorphonucleate cells in the blood reflowing from affected superficial veins of legs both at rest and after prolonged venous stasis (1 hour in standing position).

RESULTS

We evaluated the I-EL both as percentage of activity (baseline 82.3+/-24.5%; after stasis 100.7+/-37.8%) and as absolute values (0.67+/-0.26 U/ml; after stasis 0.79+/-0.39 U/ml). In blood samples taken after venous stasis we found a tendency toward a trapping of white blood cells and an increase of the haematocrit over baseline. The difference in the percentages of activity of I-EL was statistically significant, but only a trend was observed for the absolute values.

CONCLUSIONS

We believe that the typical haemodynamic disorders of patient with CVI increased by prolonged venous stasis can modify the function of white blood cells, which are closely linked with venous hypertension, thus playing an important role in the pathogenesis of skin ulcers.

Use of lightguide spectrophotometry to investigate the effect of postural changes on skin oxygenation in deep venous insufficiency

BACKGROUND

Postural changes play an important role in the development of venous disease. The aim of this study was to investigate skin oxygenation in patients with deep venous insufficiency.

METHODS

Haemoglobin oxygen saturation (SO2) was measured with macro- and micro-lightguide spectrophotometry in clinically normal skin at the gaiter area with the leg in the supine position, raised to 45 degrees and on standing. Similarly, transcutaneous oxygen tension (PtcO2) and laser Dopper flux (LDF) values were obtained. SO2 was also measured after heating the skin to 44 degrees C in the supine and standing positions.

RESULTS

SO2 and PtcO2 decreased on leg raising (P < 0.05 and P < 0.01 respectively). SO2 fell on standing (P < 0.05) while PtcO2 rose (P < 0.05). On heating the skin, SO2 increased (P < 0.05) on standing. LDF fell on standing (P < 0.005) but increased on leg raising (P < 0.05).

CONCLUSION

Lightguide spectrophotometry showed a profound decrease in skin oxygenation on standing and leg raising; PtcO2 measurements may miss the role of vasoconstriction with postural changes.

Clinical histochemical and immunohistochemical investigation of the capillary basal membrane in chronic venous insufficiency

Present investigations regarding the pathogenesis of chronic venous insufficiency (CVI) are focusing on microvascular changes. The aim of our investigation was to examine the correlation between the thickness of pericapillary type IV collagen depositions, basal membrane alterations and transcutaneous oxygen tension (TcPO2) in CVI-patients. Histochemical and immunohistochemical investigation of the capillary basal membrane was performed on 15 biopsies from normal controls, as well as 30 patients with CVI stage I and III (classification by Widmer & Stähelin). In all subjects TcPO2 was measured just prior to biopsy procedures in exactly the same area where the specimen was subsequently excised. The microscopically measured thickness of the collagen IV layer and the basal membrane was increased significantly in patients with CVI. Specimens from normal controls showed a collagen IV layer thinner than 0.1 micron. Patients with CVI stage III revealed strong collagen IV depositions between 0.2 and 0.3 microns. Comparison between TcPO2 and histological findings in the measured ares showed oxygen pressure varying from 62 mmHg (SEM 4.94 mmHg) in normal controls, down to 13 mmHg (SEM 3.39 mmHg) in patients with thick collagen IV layers. Besides an increased collagen IV layer, microvascular thrombosis and a thickened basal membrane have to be considered for impaired capillary perfusion.

Differential release of endothelin in myocutaneous island flaps in response to gradually insetting venous stasis or arterial ischemia

Endothelin (ET) provokes strong and sustained contraction in preparations of isolated vascular smooth muscle, and the production of ET is thought to increase secondary to increased wall shear stress and hypoxia. The release of ET and blood flow distribution between arteriovenous shunts and capillaries were studied in autoperfused myocutaneous pig island flaps during graded arterial or venous blood flow reduction (N = 12). A group comprising four flaps was not exposed to blood flow reduction and served as controls. Total flap blood flow (venous outflow [VO]) was reduced in 1-hour periods to 50%, 25%, and 0%. Downregulation of VO caused a lower capillary blood flow (CBF) at 25% (P < .05) and at 50% (P < .05) in flaps exposed to venous stasis as compared with flaps with arterial ischemia. The reduction in blood flow was paralleled by decreasing oxygen consumption, although flaps with venous stasis had lower oxygen consumption than flaps exposed to arterial ischemia (P < .05). ET was found to be released from these island flaps before blood flow was reduced. Gradual arterial clamping caused a statistically significant (P < .05) decrease in the release of ET from 8.7 +/- 1.3 fmol/min before ischemia to 4.1 +/- 1.7 at 50% blood flow and 4.1 +/- 1.0 at 25% blood flow. In contrast, the release of ET with venous stasis remained unchanged at a level of 7.5 +/- 1.6 fmol/min before blood flow reduction, 7.3 +/- 0.7 at 50% blood flow, and 8.5 +/- 1.6 at 25% blood flow. These data suggest a relationship between CBF, intravascular pressure, and ET production.(ABSTRACT TRUNCATED AT 250 WORDS)

[Microcirculation and rheology]

Microvessels, especially in the skin and muscles are organized in functional units. These units are controlled by the adrenergic system and hormones but also have autonomous metabolic and myogenic regulatory systems independent of vasomotion. Microcirculatory blood flow is affected by special rheologic properties: a low arteriolar haematocrit rises to the systemic level in the venules. The flow rate in the venules is low, and together with the raised haematocrit, explains the microvenular sensitivity to hyperviscosity. Capillarovenular microangiopathy, recently described by standard and fluorescent capillaroscopy, develops during chronic venous insufficiency. The capillary loops appear dilated and knotted together with fibrous deposits and pericapillary oedema. Venous hyperpressure is the cause of this microangiopathy. Together these phenomena disrupt normal haemodynamics and physiology of the microcirculatory unit: baseline hyperhaemia, lowered vasomotor and vasomotion reactivity, development of rheologic disorders (haemoconcentration, hyperfibrinogenaemia, erythrocyte agregation) and decreased fibrinolysis. Modifications in the transcapillary exchange is related to hypoxia and is aggravated by depressed lymphatic drainage. The main consequence is oedema. Inflammation, a characteristic of these microangiopathies could occur when the endothelium is activated by the hypoxia. The classical mediators of inflammation would activate interactions between the different cells: endothelium, granulocytes, monocytes and platelets. Several pharmacological models have been developed for the analysis of these data including exploration of the permeability and capillary resistance and rheological analysis. Objective observation of the microangiopathy with capillaroscopy, together with modern haemodynamical, biological and pharmacological methods are essential for a better understanding of microvascular disorders in chronic venous insufficiency.

[The relation between venous stasis and the occurrence of pain]

Venous stasis is a situation encountered commonly in varicose disorders. The potential implications of this decrease in oxygen levels in terms of the status of the cells of the vein were assessed. When endothelial cells are subjected to hypoxia, there is stimulation of the cells which shows itself as increased synthesis of prostaglandins and of PAF (Platelet Activating Factor). The synthesis of these typical mediators of inflammation results from activation by the calcium of phospholipase A2 which releases the arachidonic acid of phospholipids and this increase in intracellular calcium results itself from a fall in efficacy of calcium pumps due to the fall in ATP caused by hypoxia. Thus the fall in oxygen leads to the production of mediators of inflammation which activate leucocytes and result in local micro-inflammation which can be very rapidly eliminated if the circulation is restored but which can also cause irreversible damage to the vein by changes in venous tissue due to activated leucocytes which release proteases and free radicals after having penetrated the intima of the vein. These processes offer an explanation for the histological changes seen in varicose veins and the onset of localised pain during the development of such disease.

[Inflammation and subcutaneous calcification of venous origins]

There have been few descriptions up to now of calcifications in chronic venous insufficiency, other than in cases where venous insufficiency is complicated be severe trophic disorders and in particular ulcers. It was therefore felt to be of interest to assess the presence of calcifications in venous insufficiency without trophic disorders. This study was based upon 40 cases recruited in the phlebology out-patient clinic of the Notre Dame de Bon Secours Hospital. Calcifications of the lower limbs were found in 7 patients, either by palpation, routine X-rays or ultrasonography. The etiopathogenic mechanisms of this occurrence not having been elucidated, a number of hypotheses are put forward on the basis of acquired data concerning: the process of formation of ectopic calcifications, changes in subcutaneous tissue, the ultimate consequences of venous stasis and of raised venous pressure, due essentially to anoxia and inflammation. One hypothesis can thus be put forward: that of inflammation. The release of cells and mediators of inflammation, the production of free radicals, causing damage to the cells of connective tissue and to the organic framework (collagen fibres) and changes in the chemical environment could combine to result in the formation of calcifications in subcutaneous tissue. However, inflammation has not been proven to be the primary etiological factor.

Edema-preventing mechanisms in rat gingiva

The long-term effect of increased local venous pressure (Pv) on interstitial fluid pressure (Pi), colloid osmotic pressure (COPi), and fractional removal rate of 125I-labeled human serum albumin (kAlb) was studied in rat gingiva. Measurements were performed on experimental animals and sham-operated controls up to 4 days after ligation of jugular veins. On the day of ligation Pv in the facial veins rose from 2.5 +/- 0.3 (SD) to 15.8 +/- 2.8 mm Hg and stayed at about this level for 2 days before a decrease to 7.4 +/- 0.9 mm Hg on day 4. In free gingiva Pi rose from an average of 3.5 +/- 0.4 to a maximum of 6.3 +/- 0.7 mm Hg, whereas in attached gingiva the corresponding increase in Pi was from 6.0 +/- 0.7 to 11.1 +/- 2.1 mm Hg. One day after the ligation COPi in wick fluid from gingiva was reduced from the control level of 10.6 +/- 1.4 to 4.5 +/- 0.9 mm Hg. COP in plasma and COPi in subcutaneous tissue on the back were unaffected. The removal rate of 125I-labeled albumin (kAlb) from the gingiva showed a nearly threefold increase after venous ligation, from 0.073 +/- 0.01 to 0.211 +/- 0.06 h-1. It is concluded that in free and attached gingiva, both a rise in Pi and a decrease in COPi will counteract the increased filtration pressure and thus prevent edema formation during venous stasis. The fall in COPi is most likely due to increased lymph flow and not dilution, as venous stasis significantly increased kAlb without any visible increase in gingival volume.

Tissue concentrations of ofloxacin in necrotic lesions in patients with peripheral vascular disease and in diabetics

In a pilot study six patients (three diabetics with gangrenous lesions of the lower limbs, mean age 74 years, three patients with peripheral vascular disease stage IV according to Fontaine, mean age 70 years) were treated with 200 mg ofloxacin orally b.i.d. The tissue concentrations of ofloxacin in the necrotic material (1.6 to 6.4 mg/kg) were in the same range as the plasma levels (2.3 to 5.9 mg/l) or even higher. In conclusion, besides local therapy, ofloxacin seems to be effective in the systemic treatment of infected necrotic and gangrenous lesions.