The effect of carpal tunnel release on median nerve flattening and nerve conduction.

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy and extensive surveys have been given on the time course of electrophysiological findings pre- and postoperatively. In patients with clinical and electrophysiological confirmed diagnosis of CTS surgical decompression of the carpal tunnel is a first line treatment and has proven to be successfull in 70 to 90% of all cases. The objective of this work was to study the morphological changes of the median nerve after endoscopic release of the carpal tunnel. We used high resolution ultrasound to quantify flattening of the median nerve and to calculate a flattening ratio before endoscopic release as well as 2 weeks and 3 months postoperatively. Ten patients with clinical and electrophysiological confirmed CTS were included in the study. There was significant normalization of the calculated flattening ratio of the median nerve already 2 weeks after surgical release, whereas nerve conduction studies needed a longer period of time to normalize and thus were still abnormal 3 months postoperatively. We conclude that ultrasound is a simple and excellent objective method for visualizing the morphological recovery of the median nerve very early after decompression surgery. In complex cases with unsatisfactory outcome ultrasonography may prove useful in confirming successfull or failed decompression of the median nerve.

Fibrin/Schwann cell matrix in poly-epsilon-caprolactone conduits enhances guided nerve regeneration.

The goal of this study was to investigate if a three dimensional matrix, loaded homogeneously with Schwann cells and the neurotrophic factor LIF (leukemia inhibitory factor), enhances regeneration in a biodegradable nerve guidance channel as compared to non-structured cell suspensions. Therefore a 10 mm nerve gap in the buccal branch of the rat's facial nerve was bridged with tubular PCL (poly-epsilon-caprolactone) conduits filled with no matrix, Schwann cells, the three dimensional fibrin/Schwann cell matrix or the fibrin/Schwann cell matrix added with LIF Four weeks after the nerve defects were bridged histological and morphometric analyses of the implants were performed. In conclusion, the three dimensional fibrin/Schwann cells matrix enhanced the quantity and the quality of peripheral nerve regeneration through PCL conduits. The application of LIF prevented hyperneurotization. Therefore, tissue engineered fibrin/Schwann cells matrices are new invented biocompatible and biodegradable devices for enhancing peripheral nerve regeneration as compared to non-structured cell suspensions without neurotrophic factors.

New and rapid fully automated method for determination of tazobactam and piperacillin in fatty tissue and serum by column-switching liquid chromatography.

A sensitive and rapid HPLC assay for determining tazobactam and piperacillin in fatty tissue and serum is described. While the common methods need liquid-liquid extraction before the injection in a automated column switching HPLC, the new method works by direct injection of the filtered tissue extract or diluted serum in a automated column switching HPLC without any other pre-treatment. This was performed by the use of a NH2-precolumn and enrichment/transfer at different pH-level. During the analyses, the NH2-precolumn was automatically regenerated with acetonitrile-water. The chromatogram peaks for piperacillin and tazobactam were identified by the retention time and quantified by peak area. The calibration curve was linear between 1 and 16 microg/ml. The quantification limit of tazobactam was about 1 microg/ml in fatty tissue extracts and in diluted serum (calculated for pure serum 2 microg/ml), respectively. For piperacillin it was less. The described procedure allows sample clean-up and determination of the antibiotic within 35 min. The chromatograms with this easy sample treatment had the same quantity of matrix peaks and in contrast to liquid-liquid extraction no loss of piperacillin. Because of the automatically rinsing of the NH2-precolumn during the chromatographic separation, more than 50 different biological samples could be measured with one NH2-precolumn without loss of performance.

Tissue engineering in plastic reconstructive surgery.

Tissue engineering (TE) is a new interdisciplinary field of applied research combining engineering and biosciences together with clinical application, mainly in surgical specialities, to develop living substitutes for tissues and organs. Tissue engineering approaches can be categorized into substitutive approaches, where the aim is the ex vivo construction of a living tissue or organ similar to a transplant, vs. histioconductive or histioinductive concepts in vivo. The main successful approaches in developing tissue substitutes to date have been progresses in the understanding of cell-cell interactions, the selection of appropriate matrices (cell-matrix interaction) and chemical signalling (cytokines, growth factors) for stimulation of cell proliferation and migration within a tissue-engineered construct. So far virtually all mammalian cells can be cultured under specific culture conditions and in tissue specific matrices. Future progress in cell biology may permit the use of pluripotent stem cells for TE. The blueprint for tissue differentiation is the genome: for this it is reasonable to combine tissue engineering with gene therapy. The key to the progress of tissue engineering is an understanding between basic scientists, biochemical engineers, clinicians, and industry.

Effect of ultrasonic assisted lipectomy (UAL) on breast tissue: histological findings.

As the use of ultrasound-assisted liposuction (UAL) increases, the technique grows more popular in breast surgery, especially in reduction mammaplasty and treatment of gynecomastia. The aim of our study was to investigate the effect of UAL on breast tissue using histological examinations, and analyze the effect of this technique on a cellular level. Biopsies from 10 patients undergoing ultrasonically assisted lipectomy prior to classic reduction mammaplasty were taken from the treated areas of the breast. Biopsies were fixed in formalin and embedded in paraffin. Sections were stained with hematoxilin-eosin, and analyzed for defective adipocytes, and the effects of UAL on breast tissue. Untreated breast tissue and breast tissue that had been treated only with conventional aspiration lipectomy served as controls. Sections were analyzed using light microscopy. Compared to the breast tissue treated only with conventional lipectomy, a stronger destruction of the cellular structure of adipocytes could be detected. The destruction was visible even in areas more distant from the aspiration channel. In contrast, the breast tissue was mostly intact, no signs of ultrasonic-induced cellular destruction were visible. The glandular structure was kept intact. Beside the direct mechanical destruction by the probe and the canula, no further alterations of the cellular integrity of the glandular parts were visible. In conclusion our results indicates that UAL is also a safe technique for use in breast surgery. Besides easy handling and improved modelling, the destructive effect of the ultrasound does not include the glandular breast tissue.

Fibrin glue as matrix for cultured autologous urothelial cells in urethral reconstruction.

In the present study, we have established a technique to create an artificial urethra in a rat animal model by transplantation of in vitro-expanded urothelial cells onto an in vivo-prefabricated tube formation using tissue engineering methods. Urothelial cells from isogenic rats were harvested for culture. A silicon catheter was used to induce a connective tissue capsule-tube formation underneath the abdominal skin. Two weeks later, the cultivated urothelial cells were seeded onto the lumen of this tube using fibrin glue as delivery matrix. The histomorphological and immunohistochemical studies revealed a viable multilayered urothelium, lining the inner surface of the prior formed connective tissue tube-formation 4 weeks after grafting the cells. We have shown that cultured and in vitro-expanded urothelial cells can be successfully reimplanted onto a prefabricated tube-like structure using fibrin glue as a delivery matrix and native cell expansion vehicle. The results suggest that the creation of an artificial urethra may be achieved in vivo using tissue engineering methods, showing potential for urethral reconstruction and providing autologous urothelium for reconstructive surgery in the genitourinary tract.

[Reconstruction of abdominal-wall midline defects--The Abdominal-Wall Components Separation]. / Rekonstruktion von Mittelliniendefekten - Die Bauchwand-Komponentenseparation -

AIM OF THE STUDY: The recurrence rate of midline defects like incisional hernias is high. Alloplastic material in sublay or onlay technique is often be used if the suture tension is to high for a primary closure. Free or pedicled musculocutaneous flaps transfer denervated muscle and lack dynamic resistance against the intraabdominal pressure. The separation of the lateral abdominal wall achieves autogenous, dynamic material for a tension free closure in small and moderate midline defects. METHODS: In 1990 Ramirez described a technique, which separates parts of the lateral abdominal wall and advances it towards the midline. The innervation and blood supply of the advanced part is maintained. With this technique it is possible to close defects tension free with dynamic abdominal wall. 9 patients were treated with this technique and followed up. RESULTS: Midline defects up to 16 cm at the waistline could be closed without tension. There were no major complications (one small delayed wound healing). There were no recurrences in a follow up time of 14.2 months. CONCLUSION: The separation of parts of the lateral abdominal wall can achieve tension free closure of e.g. incisional hernias of small and moderate size. The advancement of the medial component provides well innervated muscle for dynamic resistance against the abdominal pressure.

[Gene therapy perspectives in modulation of wound healing]. / Gentherapeutische Perspektiven zur Modulation der Wundheilung.

A variety of reasons can afflict wound healing. Current research is focussed on the acceleration of wound healing by stimulating molecular processes. Gene therapy may offer completely new ways to treat chronic wounds. Possible advantages of gene therapeutic modulation of wound healing might be a long term efficiency, systemic or local regulation of gene expression and low side-effects. Current goals comprise the improvement of transfection efficiency and specificity. In vivo applications are therefore focussed on optimized inducible or even cell-type specific promotors, as well as on improved local application techniques. Studies from our laboratory demonstrate the possibility to combine modern cell culture techniques with different types of gene transfer. This enables the simultaneous grafting of manipulated cells to the wound with the continuous delivery of specific proteins of interest. Experimentally, this lead to accelerated closure of partial and full thickness animal wounds. Clinically, gene therapy for the treatment of chronic wounds seems to be a realistic goal within the next years and might be applicable for a variety of novel indications.

Acute endotoxemia protracts leukocyte / endothelium interaction after local ischemia and reperfusion in striated muscle.

Postischemic reperfusion injury and endotoxemia have been shown to promote multiple organ failure in polytraumatized patients. Both pathomechanisms comprise endothelial injury, leukocyte activation, and enhanced leukocyte/endothelium interaction in the microcirculation. Using a dorsal skinfold chamber model for intravital microscopy in striated muscle of awake hamsters, we investigated whether acute endotoxemia enhances postischemic leukocyte/endothelium interaction. - In control animals (n = 8), reperfusion after 2 hours of pressure induced ischemia elicited the rolling and adhesion of fluorescently stained leukocytes to the endothelium of postcapillary venules with a maximum at 0.5 and 2 hours after reperfusion and a decline towards preischemic values after 24 hours. Postischemic leukocyte adhesion was enhanced and protracted in animals where acute endotoxemia was induced through intravenous injection of endotoxin (Salmonella abortus equi, 0.1 microg¿kg superset-1) either 10 minutes prior to ischemia (n = 8) or to reperfusion (n = 8). - These results suggest that acute endotoxemia has the potential to aggravate the leukocyte-triggered reperfusion damage to striated muscle and presumably to vital organs and thus favours the development of multiple organ failure after primarily successful reperfusion.

[Pedicled versus free TRAM flap for breast reconstruction]. / Gestielter versus freier TRAM-Lappen zur Mammarekonstruktion.

In breast reconstruction, the free TRAM-flap offers many advantages over the pedicled TRAM-flap. Due to its superior perfusion, the free flap rarely develops necrosis. Shaping of the flap is easier due to the lack of the thick muscle pedicle. Because the rectus muscle is spared, there is minimal donor site morbidity. However, the necessary microvascular anastomoses reduced the acceptance of the free TRAM-flap. During a 13-months period, 51 breast reconstructions were performed in 41 patients, 31 unilateral and ten bilateral. 45 flaps served for delayed reconstruction and six flaps for immediate reconstruction. The operations were performed by two teams working simultaneously. The average operating time was 3.9 hours for unilateral and 6.9 hours for bilateral delayed reconstruction. For immediate reconstruction, 6.2 and 6.3 hours were required for uni- and bilateral procedures, respectively. In 38 flaps, the thoracodorsal vessels served as recipient vessels; 13 flaps were anastomosed to the internal mammary artery and vein. Postoperative complications were observed in 13 patients. Three vessel anastomoses had to be revised. In one flap, a partial necrosis occurred; in two flaps hematoma evacuation was necessary. Two patients suffered from fat necroses at the abdomen and one umbilicus was lost. Skin irritations and seromas at the abdomen occurred in five patients. Pulmonary embolism was diagnosed in one patient three weeks postoperatively. Abdominal hernias or bulging in the epigastric area were not observed up to 15 months after reconstruction. These results reveal a low complication rate for breast reconstruction with the free TRAM-flap. The advantages of this technique as compared to the pedicled technique are discussed.

Differentiation between arterial and venous vessel occlusion by simultaneous measurement with laser Doppler flowmetry and photoplethysmography.

In abdominal cutaneous island flaps of rats (n = 16), either the artery or the vein was clamped, while flap perfusion was simultaneously monitored with laser Doppler flowmetry (LDF) and photoplethysmography (PPG) to identify the occluded vessel responsible for insufficient perfusion. The LDF signal decreased promptly after arterial clamping. After venous clamping, only a slow decrease was noted. The LDF amplitude differed statistically significantly between arterial and venous clamping only up to 90 sec after onset but not thereafter, allowing no further distinction between the two types of vessel occlusion. Power spectral analysis of the LDF signal did not show clear differences in frequency ranges between arterial and venous occlusion. In contrast, PPG measurements demonstrated significant differences between both perfusion disorders throughout the entire observation period. These results suggest that dependable differentiation between prolonged arterial and venous vessel occlusion is not possible based on the amplitude or power spectral analysis of the LDF signal alone. PPG may be reliably used to differentiate between arterial and venous perfusion disorders.

[Breast reconstruction with the deep inferior epigastric perforator vein flap]. / Brustrekonstruktion mit dem Vasa epigastrica inferior-Perforanslappen.

Aside from existing advantages for reconstruction of an amputated breast with a free versus a pedicled TRAM-flap, small parts of the rectus abdominis muscle still must be sacrificed to secure blood perfusion of the flap. The deep inferior epigastric perforator flap (DIEP-flap) was recently introduced to overcome this disadvantage in autogenous breast reconstruction. Morbidity of the donor site should be minimized, since this technique avoids fascia or muscle defects. Eight patients underwent ten autogenous breast reconstructions with a DIEP-flap. Four flaps were performed for immediate and six flaps for delayed reconstructions. The internal thoracic artery and vein were used as recipient vessels in seven cases, the thoracodorsal vessels were utilized in three cases. The average operating time was 4.5 hours for unilateral and 6.9 hours for bilateral reconstructions. Two flaps developed total flap necrosis. One was due to a technical error during dissection, another flap developed an arterial thrombosis on postoperative day 5. The remaining flaps healed without problems. Subjectively, patients had far less complaints about the donor site in the lower abdomen compared to a free TRAM-flap, suggesting a lower morbidity in this area with the DIEP-flap.

Infiltration of tumescent anesthetic solution by a modified wound irrigation system.

An easily set-up, efficient infiltration system for subcutaneous infiltration of tumescent anesthetic solution is presented. It can be constructed from parts of a wound irrigation system usually available in surgical units. Thereby it is an economical means of precise and convenient infiltration procedures.

The deep inferior epigastric artery perforator flap.

This article describes the surgical technique of an autogenous breast reconstruction deep inferior epigastric artery (DIEA) perforator flap and presents clinical cases. Advantages of this technique in regard to donor site morbidity are discussed.

Visualization of nutritive perfusion following tourniquet ischemia in arterial pattern skin flaps: effect of vasoactive medication.

We present an experimental model that makes it possible to investigate the effects of global ischemia and reperfusion on microvascular perfusion and viability of ill-proportioned (poorly designed) arterial pattern skin flaps in hairless mice. Skin flaps were created on the ears of hairless mice by dissecting two of three nutritional vessel bundles at the ear base. Under these nonischemic conditions, 19 percent of the total flap area went on to necrose (as a result of poor flap design). Global ischemia was induced to the flap tissue for 6 hours with a tourniquet clamp directly after flap incision. The extension of perfused tissue area and flap viability were assessed at the microcirculatory level by intravital video microscopy at 1, 3, 6, and 18 hours and 7 days after reperfusion in animals treated with either normal saline (control) or the vasoactive drug buflomedil hydrochloride (3 mg/kg of body weight per day, i.v., starting 4 hours prior to flap creation and continued at daily intervals until the end of the experiments). In untreated animals (n = 18), 1 hour after clamp release we observed reperfusion of 39.55 percent (38.5/44.9) of total flap area. Reperfusion remained unchanged within the following 5 hours. Within the next 12 hours, reperfused flap area was dramatically reduced to 21.9 percent (15.1/58.4). Seven days thereafter, only 18.8 percent (10.9/42.2) of total flap area remained viable. In contrast, we found in buflomedil-treated animals (n = 18) that 57.3 percent (53.5/62.9) of the total flap tissue was reperfused within the first hour after clamp release (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement of skin flap perfusion by subdermal injection of recombinant human basic fibroblast growth factor.

The effect of subcutaneously injected recombinant human basic fibroblast growth factor (bFGF) was studied in an arterial skin flap model on the ear of the hairless mouse. Fifty-three male, hairless mice were randomly assigned to 4 groups and pretreated in two different time intervals with different doses of human bFGF. Microvascular perfusion of the skin flaps was determined over a 5-day period by means of intravital microscopy after intravenous injection of the fluorescence marker fluorescein isothiocyanate-dextran (M(r) 150,000). Human bFGF (2,700 ng) injected 6 days before flap creation could not improve perfusion of the flap (n = 10) when compared with controls. However, when applied 18 days before flap creation (n = 13), the same dose resulted in a significant reduction of nonperfused tissue at day 5 after flap creation (12.3% vs 26.8%, p < 0.01). Eighteen-day pretreatment with 1,200 ng (n = 10) and 480 ng (n = 10) had no significant effect on skin flap perfusion. We conclude, therefore, that successful pretreatment with bFGF for prevention of skin flap necrosis is time and dose dependent.

Basic fibroblast growth factor accelerates wound healing in chronically ischaemic tissue.

The influence of subcutaneously injected recombinant human basic fibroblast growth factor (bFGF) on wound healing in normal (n = 20) and ischaemic (n = 28) skin tissue was investigated. Standardized wounds (5 mm2) were created on the ears of hairless mice and treated for the first 3 days after wound creation with total doses of 720 ng (n = 24) and 4050 ng (n = 24) bFGF. The bFGF had no effect on wound healing in non-ischaemic tissue. In ischaemic skin, mean(s.d.) wound surface area after treatment with 720 ng bFGF was 1.6(0.9), 0.5(0.6) and 0.1(0.3) mm2 compared with 2.8(1.0), 1.4(1.0) and 0.8(0.7) mm2 for control wounds on days 7 (P < 0.04), 10 (P < 0.03) and 13 (P < 0.04) respectively. High-dose bFGF (4050 ng) reduced the mean(s.d.) wound surface area to 2.4(0.7) and 0.8(0.7) mm2 compared with 3.9(0.6) and 2.1(0.8) mm2 for control wounds on days 7 (P < 0.006) and 10 (P < 0.02) respectively. These results suggest that bFGF may be of use for the treatment of wounds in ischaemic tissue.

Impact of ischemia on tissue oxygenation and wound healing: intravital microscopic studies on the hairless mouse ear model.

To determine the effect of ischemia on tissue oxygenation and the healing of experimental wounds, chronic ischemia was induced in the ears of hairless mice by ligating 2 of the 3 main nutritional arteries. Tissue ischemia was verified by measurement of transcutaneous pO2 (tcpO2) prior to and on days 3, 6, 9, 12 and 15 after vessel ligation. TcpO2 values decreased from 24 to 6 mm Hg at day 2 after ligation, and slowly recovered to 12 mm Hg at day 12 after vessel ligation. In animals treated with the vasoactive drug buflomedil (3 mg/kg BW i.v., startling 2 days after vessel ligation) tcpO2 values were significantly higher on days 6 and 9 when compared to saline-treated control animals. In order to find out whether the enhanced tissue oxygenation resulted in enhancement of healing of wounds, we created circular wounds (diameter = 2.5 mm, depth 0.1 mm) on ischemic ears 2 days after vessel ligation. The wound surface area was measured by means of intravital fluorescence microscopy and digital planimetry at 3-day intervals until the time of wound closure. These experiments were performed on buflomedil-treated and control animals receiving equivalent amounts of saline. The reduction of wound surface area was accelerated and wound closure time was reduced from 15 days in control animals to 12 days in buflomedil-treated animals (p < 0.01). Functional capillary density as well as the microhemodynamic parameters microvessel diameter and red blood cell velocity were not different between buflomedil-treated and control animals.

Comparative analysis of tissue fluorescence as related to capillary perfusion in random pattern skin flaps.

In random pattern skin flaps of mice, tissue fluorescence measured by means of videodensitometry at 24 h after flap elevation significantly correlates with intravital microscopically measured functional vessel density and viability of skin tissue as assessed by transmission light and electron microscopy. The correlation was found reproducible in non-ischaemic flaps (r = 0.86) and flaps being rendered ischaemic for 6 h after elevation (r = 0.98), indicating that increased microvascular permeability as a result of ischaemia/reperfusion does neither affect tissue fluorescence nor the accuracy of the fluorescein dye test. In addition, tissue fluorescence at 24 h after flap elevation accurately predicts ultimate flap survival on the 7th postoperative day with a sensitivity of 0.89 and a specificity of 0.85. These results suggest that in non-ischaemic as well as in ischaemic random pattern skin flaps tissue fluorescence can be used for assessment of nutritive blood flow, viability of skin tissue and ultimate tissue survival in these flaps.

[Use of vasoactive substances in prevention of skin necroses]. / Einsatz vasoaktiver Substanzen zur Verhinderung von Hautnekrosen.

The nutritional blood flow to the tissue is the principle factor determining the outcome of reconstructive procedures in plastic surgery. Beside vasoconstriction, thrombocytes aggregation, leukocytes activation, followed by production of oxygen free radicals and release of proteases, impaired fluidity of erythrocytes and swelling of the microvascular endothelium are responsible for impaired perfusion following ischemia/reperfusion. Therefore, vasoactive drugs known to improve nutritional blood flow are of particular interest in the prevention and therapy of skin flap necrosis. Several methods have been employed to quantify nutritional blood flow in skin flaps but none of them have elucidated the mechanisms underlying potential tissue protection by these drugs. We have developed two skin flap models in the hairless mouse, in which nutritional blood flow can be directly assessed at capillary level by means of intravital microscopy. In the arterial skin flap model, the efficacy of three vasoactive drugs (naftidrofuryl [4.5 mg/kg/day], pentoxifylline [17.0 mg/kg/day] and buflomedil [3.0 mg/kg/day]) to prevent and/or reduce tissue necrosis was investigated. Buflomedil provided the most efficient tissue protection, a phenomenon also verified in a random skin flap model. It was demonstrated that preoperative application of buflomedil preserves functional vascular density in the distal part of skin flaps more efficiently compared to postoperative application. However, there were no significant differences in amount of skin necrosis between the two groups. The tissue protection effect was also observed in random pattern flaps rendered ischemic for six hours after flap elevation.(ABSTRACT TRUNCATED AT 250 WORDS)