PubMed Health⌕ Search

Biomedical subjects

F W Peter

Publications and source records attributed to F W Peter.

At least 19 recordsLinked to original sources
PubMed2002

The effect of wound ointments on tissue microcirculation and leucocyte behaviour.

An intact microcirculation is essential for normal healing to occur. Wound repair may be impaired by various endogenous and exogenous factors, such as reduced microvascular perfusion, infection and debris. In the nonhealing wound, radical surgical debridement is critical. To supplement healing, various ointments are used in clinical practice. Little is known about their effects on tissue perfusion. We have therefore selected two substances widely used, the antiseptic Betadine and the enzyme combination Elase and investigated their impact on the microcirculation and on leucocyte activity, using the cremaster muscle as a model. We found that functional capillary density and arteriolar diameters were significantly reduced by Betadine, whereas leucocyte activity was not affected. In the Elase group, capillary flow and arteriolar diameters were significantly increased, and again leucocyte activity was not changed. The mechanism by which Betadine reduces microvascular flow is believed to be the same as in reperfusion injury. The positive effect of Elase on the microcirculation might be attributed to plasmin, which has been shown to dilate blood vessels.

Analysis of Variance↗
PubMed2002

[Direct visualization of microcirculation in burn wounds with OPS imaging--is determination of depth of burns possible?].

Adjunct diagnostic techniques might help surgeons to accurately analyse the depth of a burn. However, despite all technical innovations an ideal device for such an application has not been established for routine use as yet. OPS imaging implemented into the CYTOSCAN A/R is a new, recently introduced technique which allows to obtain high contrast images of the microcirculation without the necessity for fluorescent dyes. The aim of the study was to validate OPS imaging as a tool to study microcirculation in skin after burn injury. OPS imaging was applied by no-touch technique and capillary blood flow was videotaped. Subsequent measurements of the microcirculation were performed at the identical site of the burn. Quantitative analysis of the microcirculation was performed off-line using CapImage. OPS imaging produces high quality images of the microcirculation in a burn wound. Data is given as the number of perfused capillaries per observation area (functional capillary density; FCD) [n/cm2]. OPS imaging allows for direct in vivo visualization and quantification of the microcirculation in burned skin. Our preliminary results of the use of OPS imaging in assessing the microcirculation in burns appear promising, and we hope that this novel technique will allow to improve the knowledge of the dynamics of the microcirculation in the pathophysiology of thermal injury.

Blood Flow Velocity↗
PubMed2000

Method for intraoperative positioning of the nipple-areola complex in vertical scar reduction mammaplasty.

The desired shape and position of the nipple-areola complex may be difficult to achieve in vertical scar reduction mammaplasty when using the standard technique of preoperative marking of the so-called mosque-shaped areolar pattern of excision. We describe our modified approach of intraoperative final positioning of the nipple-areola complex by hiding the nipple-areola complex behind the closed vertical incision. Individual positioning at the final part of the operation allows for more predictable results and also for a calculated lower positioning, which enables balance of the potential bottoming-out of the breast, particularly in previously large ptotic breasts. We believe that this modification helps to further improve the results of vertical scar reduction mammaplasty by adding more possibilities for shaping and "last-minute" modifications intraoperatively.

Adult↗
PubMed1999

Microcirculatory changes following different temperature washouts in a free flap model.

In spite of the extensive experimental work on vascular washout in free flap surgery, an optimal temperature for the washout solution has not been established. This study was designed to determine the effect of the washout solution temperature on the degree to which the microcirculation is cleared of blood. The cremaster muscle flap in the rat was used, in which the microcirculation can be directly viewed and the presence of blood and perfusion parameters within various vessels can be measured during and after washout. Washout was started with a single, high-pressure infusion and continued at 130 mmHg for 15 minutes. The temperature of the washout solution was either 2-3, 20-22, or 35 degrees C. In all three groups, washout cleared the microcirculation almost completely within the first minute. However, we observed that a cold or room temperature washout cleared the microcirculation more completely than a warm washout did. The temperature of the washout solution did not effect post washout capillary perfusion and/or arterial diameters.

Animals↗
PubMed1999

Leukocyte-endothelium interaction in arterioles after ischemia and reperfusion.

Leukocyte-endothelium interaction in postcapillary venules plays an important role in reperfusion injury, inflammation, shock, and sepsis. This phenomenon is poorly described in precapillary arterioles. In fact, many researchers have reported no evidence of leukocyte adherence in arterioles whatsoever. Most research has focused on venules of larger rodents, in which observation of the microcirculation, especially arterioles, is limited. We have developed a model which provides a clearer view of these microvessels using the mouse cremaster muscle. This muscle has an approximate thickness of 100 microm allowing images produced by transillumination to be very clear. After vascular isolation, the right cremaster muscle was subjected to 4 h of ischemia, followed by 2 h of reperfusion. The left muscle was not rendered ischemic, thereby allowing it to serve as the animal's own internal control. We observed leukocyte rolling in arterioles in both the ischemic and the nonischemic muscles. Leukocyte sticking was seen in arterioles and venules on both sides, except in control arterioles. The number of rolling and sticking leukocytes on the ischemic side was significantly higher than in controls (P < 0.05) for both arterioles and venules. During the reperfusion period, this number did not change significantly. Transmigration of leukocytes was observed only in venules, but not in arterioles. The number of perfused capillaries was reduced on the ischemic side compared to controls and did not change significantly during the 2 h of reperfusion. Our results demonstrate that leukocyte-endothelium interaction occurs in muscle arterioles of mice. This phenomenon is more pronounced after ischemia and reperfusion, i.e., depends on the extent of tissue insult.

Animals↗
PubMed1999

The effect of severe burn injury on proinflammatory cytokines and leukocyte behavior: its modulation with granulocyte colony-stimulating factor.

Severe injury causes immunosuppression. The main contributors are impaired leukocyte function and a cytokine dysbalance. GCSF increases PMN count, function and modulates the inflammatory response. However GCSF may overactivate leukocytes. The purpose of this study is to investigate whether GCSF is able to restore immune competence after severe injury. Lewis rats were divided into three groups: 30% TBSA burn + vehicle; 30% TBSA burn + GCSF (150 microg rhGCSF); Control. Blood samples were taken for total white cell count, PMNs, TNFalpha and IFNgamma. Leukocyte rolling and sticking were measured in the cremaster muscle microcirculation. Leukocyte diapedesis was investigated by lavage of the abdominal cavity and the lungs. Total white cell and PMN counts in the burn + GCSF group were significantly higher (P<0.001) than in burn+vehicle animals. Leukocyte adherence and diapedesis were not elevated in the burn + GCSF group as compared to the burn + vehicle group. TNFalpha (P<0.05) and IFNgamma (P<0.001) levels were significantly increased in the burn + vehicle animals compared to the burn + GCSF animals. GCSF modifies the immune system, as shown by an increase in white cell and PMN counts and by balancing the overall immune response from proinflammatory to normal, as shown by decreased TNFalpha and IFNgamma levels. GCSF does not overactivate PMNs.

Abdomen↗
PubMed1998

Do leukocytes contribute to impaired microvascular tissue perfusion after arterial repair?

Impaired capillary perfusion may result in flap failure. Platelet emboli, polymorphonuclear leukocytes (PMNs), and/or vasospasm have been identified as possible causes. This study investigates the role of PMNs in causing impaired capillary perfusion in a free flap model. PMN concentrations were depleted using antineutrophil serum. The cremaster muscles of 20 Sprague-Dawley rats were isolated on a single neurovascular pedicle and after a simulated technically poor arterial anastomosis upstream and reperfusion, capillary perfusion was measured each hour for 6 hours. Even though the number of PMNs was significantly reduced in the animals treated with antineutrophil serum, capillary perfusion was not changed compared with controls. These results demonstrate that depleting circulating PMNs does not protect capillary perfusion in our model. These findings suggest that reduced capillary perfusion downstream from an anastomotic repair is not mediated by the presence of PMNs in the microcirculation.

Anastomosis, Surgical↗
PubMed1998

Leukocyte behavior in a free-flap model following chemotherapy and application of granulocyte colony-stimulating factor (GCSF).

Free-flap reconstruction following tumor resection and chemotherapy is used increasingly in sarcoma patients. Granulocyte colony-stimulating factor (GCSF) is used to stimulate polymorphnuclear leukocytes (PMNs). In this study we used a free-flap model to investigate PMN behavior after chemotherapy and GCSF stimulation. Eighteen Lewis rats were divided into three groups: (1) chemotherapy + vehicle; (2) chemotherapy + GCSF; and (3) control. Group 1 received vinblastine; group 2 received vinblastine plus 300 microg rhGCSF. Blood was drawn for total white cell and PMN counts for 9 days. Free-flap surgery was simulated by isolating the cremaster muscle on its pedicle and anastomosing the artery. Leukocyte-endothelium interaction was assessed by observation of leukocytes rolling and sticking. Leukocyte sequestration was measured by counting leukocytes in the lungs and the abdomen. We found that leukocyte rolling and sticking were significantly increased, while sequestration was decreased in the chemotherapy + GCSF group. We conclude that leukocytes-endothelium interaction after chemotherapy and GCSF administration is increased in the microcirculation. This augments the risk of microvascular compromise and subsequent flap failure, as capillary flow may be altered.

Animals↗
PubMed1998

[Prospects of tissue transfer and tissue culture].

Posttraumatic lesions of joints and extremities create a major challenge for an anatomic plastic reconstruction. The experimental and clinical progress in the field of tissue engineering, immunosuppression of allografts and xenografting including methods of genetic engineering provides a potential basis for the reconstruction of whole limbs or anatomical segments with living tissue.

Animals↗
PubMed1998

[Use of growth factors in therapy of chronic wounds. Experimental, clinical and financial aspects].

Clinical trials on exogenous application of polypeptide growth factors in chronic wounds have not fulfilled the high expectations derived from results of experimental studies. There is no convincing evidence that growth factors may substitute for good wound care and efficient surgical approaches to wound closure. The ultimate goal of treatment of chronic ulcerations remains reconstitution of a durable skin envelope without unstable scarring. Therefore, optimization of current methods of wound therapy, including reconstructive vascular and plastic surgery and adequate metabolic and wound control, should be employed before any adjuvant growth factor therapy is attempted. As long as efficient and inexpensive therapy of chronic wounds by growth factors has not been demonstrated, empincal growth factor treatment should be rejected on scientific and economic grounds. Current use appears to be reasonable only under a regime of controlled clinical studies comparing growth factor treatment with conventional wound therapy and operative measures according to the rules of "good clinical practice".

Administration, Topical↗
PubMed1998

Effect of granulocytes on the microcirculation in free-flap surgery.

INTRODUCTION: Impaired capillary perfusion may result in flap failure. Platelet emboli, vasospasm and/or polymorphonuclear leukocytes (PMNs) have been identified as possible causes. This study investigates the role of PMNs in causing impaired capillary perfusion in a free-flap model. METHODS: Sprague-Dawley rats were injected with either anti-neutrophil serum or saline. Their cremaster muscle was isolated on its pedicle. After arterial repair and reperfusion, capillary perfusion was counted each hour for 6 h. RESULTS: The number of PMNs was significantly reduced in the animals treated with anti-neutrophil serum. However, capillary perfusion did not improve in this group. CONCLUSIONS: These results demonstrate that depleting circulating PMNs does not counterbalance the reduction of perfused capillaries, i.e., does not increase their number. It is suggested that reduced capillary perfusion downstream from an anastomotic repair is not mediated by the presence of PMNs in the microcirculation.

Anastomosis, Surgical↗
PubMed1998

[What is the function of neutrophilic granulocytes in microcirculatory disorders in free tissue transfer?].

In a free flap model capillary perfusion in the downstream tissue, i.e. the flap is significantly decreased after one hour of ischemia. This decrease occurs even though circulating PMN's have been depleted and are not available to mediate this phenomenon. It is suggested that PMN's do not mediate the mechanism responsible for reduced capillary perfusion and possible microvascular failure.

Animals↗
PubMed1998

[Plastic reconstruction of the irradiated thoracic wall].

Chest-wall reconstruction following irradiation requires a surgical approach that addresses the specific healing disorders associated with irradiation: (1) biopsy of any open wound to rule out recurrence or persistence of tumor; (2) aggressive debridement of all necrotic or infected tissue, especially osteonecrosis of the chest wall; (3) reconstruction with well-vascularized muscle or musculocutaneous flaps. Coverage with muscle flaps provides a very reliable and effective single-stage reconstruction. Most types of flaps employed involve the latissimus, rectus abdominis and pectoralis muscle or musculocutaneous flaps. Rarely, stabilization of the thoracic wall is required, mostly facilitated by nonresorbable mesh. Respecting these principles, the irradiated chest wall can be reconstructed safely and with low morbidity. Plastic reconstructive techniques may also be employed safely to reconstruct the breast simultaneously in irradiated tissue by use of latissimus or rectus abdominis flaps.

Adult↗
PubMed1997

Lack of nitric oxide contributes to vasospasm during ischemia/reperfusion injury.

Vasospasm can be a complication after free tissue transfer and replant operations. Recent studies suggest that vasospasm may be due to endothelium dysfunction, resulting in impairment of nitric oxide production. The present experiment was designed to investigate acute responses of the microcirculation of skeletal muscle to local interarterial infusion of sodium nitroprusside (a direct donor of nitric oxide and thus an endothelium-independent vasodilator) or acetylcholine chloride (which stimulates endothelium release of endogenous nitric oxide) during reperfusion after 4 hours of warm ischemia. Male Sprague-Dawley rats, each weighing 100 to 120 gm, were anesthetized with sodium pentobarbitone and were surgically prepared with vascular isolated and denervated cremaster muscles that were subjected to 4 hours warm ischemia and 2 hours of reperfusion. Sodium nitroprusside (10(-3) M), acetylcholine chloride (10(-4) M), or normal saline (eight rats for each group) were administered by local infusion (0.1 ml/hour) through the femoral artery into the natural blood flow of the cremaster. The arterial tree in the cremaster was observed and arteriole diameters (A1-A4) were measured using intravital microscopy. The number of arteriole branches having temporary stoppage of flow were counted in each cremaster. The results from this study show that local infusion of sodium nitroprusside, but not acetylcholine chloride, prevents ischemia/reperfusion vasoconstriction in A3 and A4 arterioles and thus improves microvascular blood flow. Generalized vasoconstriction caused by topically applied norepinephrine (10(-6) M) to sham ischemia cremasters could be completely reversed by the local infusion of 10(-4) M acetylcholine chloride. These results indicate that vasospasm after ischemia/reperfusion may be related to temporary endothelial cell dysfunction, resulting in the inability to produce sufficient nitric oxide during early reperfusion. Vascular smooth muscle, however, is responsive to locally administered sodium nitroprusside infusion (which is thought to provide exogenous nitric oxide).

Acetylcholine↗
PubMed1997

Effect of low dose aspirin on thrombus formation at arterial and venous microanastomoses and on the tissue microcirculation.

In free flap/replantation surgery, failure is usually associated with thrombotic occlusion of a microvascular anastomosis (risk zone I) or, on occasion, flow impairment in the microcirculation of the transferred or replanted tissue (risk zone II). The objective of this study is to describe the effect of low dose aspirin on blood flow at both risk zones in microvascular surgery. Risk zone I: In rat femoral arteries and veins, thrombus formation was measured at the anastomoses using transillumination and videomicroscopy. Forty male Wistar rats were assigned in equal numbers to four groups: either arterial or venous injury with either aspirin (5 mg/kg systemically) or saline treatment. We found that aspirin significantly reduces thrombus formation at the venous anastomosis (p = 0.001). Risk zone II: In the isolated rat cremaster muscle downstream from an arterial anastomosis, we measured capillary perfusion, arteriolar diameters, and the appearance of platelet emboli for 6 hours in the muscle microcirculation. Sixteen male Wistar rats in two equal groups received either aspirin (5 mg/kg systemically) or saline. We found that in aspirin-treated animals, capillary perfusion is significantly (p = 0.002) improved, whereas arteriolar diameters and emboli only slightly increased. In conclusion, low dose aspirin inhibits anastomotic venous thrombosis and improves microcirculatory perfusion in our rat model. These studies provide quantitative data confirming and clarifying the beneficial effects of low dose aspirin in microvascular surgery.

Anastomosis, Surgical↗
PubMed1997

[Thrombosis and tissue protection in microvascular surgery--an overview].

Although microvascular surgery has become a safer procedure in recent years, failure still occurs. The main cause of failure is thrombosis of the anastomosed vessels. Thrombosis involves the vascular wall, platelets and the coagulation system. Sometimes the transferred tissue dies with the anastomoses open. This is caused by an insufficient perfusion at the microcirculatory level, e.g. a reduction of capillary inflow by arteriolar vasoconstriction. Tissue damage also occurs after ischemia and reperfusion. Oxygen free radicals and activated leukocytes are responsible for this phenomenon. Thrombosis can be reduced by antiplatelet and anticoagulant drugs, substances increasing fibrinolysis and other agents. In the clinical situation, aspirin, heparin and dextrane have proven reliable. The microcirculation can be protected by aspirin. Reperfusion injury is affected with superoxide-dismutase, allopurinol and perfusion solutions. Future developments in this field will include locally applied antithrombotic agents and substances acting more specifically.

Anastomosis, Surgical↗