Biomedical subjects

T J Galla

Publications and source records attributed to T J Galla.

At least 19 recordsLinked to original sources

PubMed2002

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.

Adipose Tissue↗

PubMed2001

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.

Animals↗

PubMed2001

[Reconstruction of abdominal-wall midline defects--The Abdominal-Wall Components Separation].

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.

Adult↗

PubMed2001

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.

Animals↗

PubMed2000

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.

Animals↗

PubMed2000

[Gene therapy perspectives in modulation of wound healing].

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.

Animals↗

PubMed1999

[Pedicled versus free TRAM flap for breast reconstruction].

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.

Adult↗

PubMed1999

[Breast reconstruction with the deep inferior epigastric perforator vein flap].

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.

Adult↗

PubMed1999

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.

Abdominal Muscles↗

PubMed1998

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.

Epigastric Arteries↗

PubMed1994

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.

Animals↗

PubMed1994

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)

Animals↗

PubMed1993

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.

Animals↗

PubMed1992

Impact of ischemia on tissue oxygenation and wound healing: improvement by vasoactive medication.

The influence of vasoactive medication on tissue oxygenation and wound healing was investigated in the ear model of the hairless mouse. Ischemia was induced to the ears by ligating 2 of the 3 main vessel bundels and verified by measurements of tcpO2. Reduced tissue oxygenation was followed by a prolongation of the time required for complete healing of standardized wounds. Treatment with the vasoactive drug Buflomedil (3 mg/kg/day iv.) resulted in enhanced recovery of the tissue from reduced oxygenation and likewise reversed the adverse effects of ischemia on wound healing. These results warrant the use of the drug in patients suffering from delayed wound healing due to peripheral arterial disease.

Animals↗

PubMed1992

[Use of vasoactive substances in prevention of skin necroses].

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)

Animals↗

PubMed1991

A new model for studying microcirculatory changes during dermal wound healing.

Intact blood supply by microcirculation to a wounded site is an indispensable prerequisite for normal tissue regeneration. However, microvascular changes taking place in the healing process of skin wounds are not understood due to the fact that only few models allow chronic in vivo studies on skin microcirculation. Therefore, we have modified the hairless mouse ear model with the purpose of a quantitative in vivo study of microhemodynamic changes throughout the healing process. Following the creation of a standardized skin wound on the ear of the homozygous hairless mouse (hr/hr), microvessel diameters, red blood cell velocities, wet weight, and leucocyte content of the ear tissue were determined. Surface area of the wound was assessed until complete closure was achieved. By repeated measurements at identical sites over the entire healing period, a distinct pattern of microvascular changes could be observed: microvessel diameters increased to a maximum a few days after wound creation, whereas red blood cell velocities reached their highest values at a later point in time and were still elevated after complete reepithelization of the wounds. Edema and leucocyte content of the ear tissue was most prominent in the early healing phase and gradually decreased to normal values thereafter. These results demonstrate changes of the microvasculature of the hairless mouse ear to injury, which are in accordance to other more indirect studies on this topic. Therefore, we conclude that the model presented is suitable for prolonged quantitative analysis of microcirculation during normal wound healing and may be used to assess microvascular changes taking place during wound healing in pathologically altered tissue.

Animals↗

PubMed1991

Increase in skin-flap survival by the vasoactive drug buflomedil.

The effect of buflomedil to protect skin tissue from ischemia and necrosis was studied in random cutaneous flaps. Measurements were performed by intravital microscopy on the microcirculatory level of capillary perfusion in a flap model in the hairless mouse. In 30 hairless mice, single-pedicle flaps measuring 6 x 16 mm were raised perpendicular to the spine of the animal. This flap develops a reliable amount of necrosis at its distal edge over a period of 7 days. A group of 10 mice received intravenous injections of buflomedil in doses of 3 mg/kg per day diluted in 0.1 ml normal saline beginning 4 hours before flap elevation and for 6 consecutive days postoperatively. In addition, 10 further animals received the same treatment except that it was started 5 minutes after flap elevation. In 10 mice serving as controls, normal saline in equal volumes as in the experimental groups was applied. By means of intravital microscopy, functional vessel density (FVD) was determined in 2.5-mm increments from the flap's base to its distal edge at 1, 6, and 24 hours after elevation. Skin-flap survival was quantified by measuring the necrotic area on day 7 by means of digital planimetry. Functional vessel density was preserved in the distal flap of animals pretreated with buflomedil, revealing a higher functional vessel density at 10.0 mm (p less than 0.01), 12.5 mm (p less than 0.05), and 15.0 mm (p less than 0.001) from the flap's base as compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Direct monitoring of capillary perfusion following normovolemic hemodilution in an experimental skin-flap model.

The effects of normovolemic hemodilution on skin flap survival are studied in a recently developed skin-flap model (homozygous hairless mouse ear) in which nutritional capillary flow is monitored directly by means of intravital microscopy from the time of flap creation throughout the establishment of necrosis. Two diluting agents (dextran 60 and hydroxyethyl starch 200) are utilized. Our quantitative findings demonstrate that the amount of nonperfused tissue following flap creation in both the dextran (n = 23) and starch (n = 13) groups was significantly decreased as compared with controls (n = 19). Our qualitative observations suggest that improved hemorrheologic properties at the microcirculatory level are responsible for the observed decreased necrosis. Various mechanisms by which hemodilution may act to prevent necrosis are discussed.

Animals↗