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Biomedical subjects

V Bühren

Publications and source records attributed to V Bühren.

At least 73 records · Page 4Linked to original sources
PubMed1993

Macrophage activation and leukocyte adhesion after liver transplantation.

Reperfusion injury involving oxygen radicals, leukocyte adhesion, and Kupffer cell activation has been suggested to contribute to the failure of transplanted livers. The aim of this study was to evaluate Kupffer cell activity, leukocyte adhesion, and the effect of the calcium channel blocker nisoldipine after rat liver transplantation by means of in vivo fluorescence microscopy to further investigate the mechanism of graft failure. Inclusion of 1.4 microM nisoldipine to the University of Wisconsin cold storage solution (UW) did not improve sinusoidal perfusion and vasoconstriction after transplantation compared with UW alone (82.7 +/- 1.0% vs. 79.2 +/- 1.7% perfused sinusoids; 7.3 +/- 0.1 vs. 8.0 +/- 0.2 microns diam of sinusoids; means +/- SE). Permanent as well as temporary adhesion of leukocytes rose from 9.4 +/- 0.8 and 10.2 +/- 0.5% in sham-operated controls to 19.1 +/- 2.2 and 19.2 +/- 0.5% after liver transplantation, respectively. Inclusion of the calcium channel blocker reduced permanent (9.1 +/- 0.8%; P < 0.05) and temporary adherent leukocytes (11.3 +/- 1.0%; P < 0.05). Phagocytosis of latex beads by Kupffer cells or other phagocytic cells as a function of activity rose after transplantation (e.g., periportal area: 509 +/- 44/mm2) compared with controls (316 +/- 22/mm2). This was significantly reduced by inclusion of nisoldipine to UW (322 +/- 32/mm2). The results of this study demonstrate activation of Kupffer cells and increase of leukocyte adhesion to the sinusoidal endothelial wall during reperfusion of transplanted livers. A calcium-dependent release of mediators by Kupffer cells that promote leukocyte adhesion is suggested as an underlying mechanism.

Animals↗
PubMed1993

Comparative effects of crystalloid and small volume hypertonic hyperoncotic fluid resuscitation on hepatic microcirculation after hemorrhagic shock.

Hepatic microcirculation, leukocyte-endothelial interaction, and sinusoidal widths were studied by means of intravital microscopy in a non-heparinized fixed pressure hemorrhagic shock model in the rat. Asanguineous resuscitation was performed either with "adequate" amounts of lactated Ringer's solution (threefold shed volume/30 min) or 4 ml/kg/3 min 7.2% saline/10% Dextran 60 (HSDex) or 4 ml/kg/3 min 7.2% saline/10% hydroxyethylstarch 200/0.62 (HSHes). Hemorrhagic shock and resuscitation was paralleled by significant (P < 0.01) lumenal narrowing of sinusoids that remained largely uninfluenced by the type of fluid used for resuscitation (HSDex: 9.28 +/- 0.56; HSHes: 8.93 +/- 0.29, LR: 8.87 +/- 0.6 microns compared to 12.17 +/- 0.24 microns in controls). Whereas HSHes and LR-therapy resulted in comparably increased leukocyte adhesion to the sinusoidal wall, the dextran-containing solution led to a significant attenuation of leukocyte-endothelial interaction, suggesting involvement of dextran-binding adhesion molecules, e.g., selectins.

Animals↗
PubMed1993

[Osteosynthesis using a buttress plate--a new principle for stabilizing scaphoid pseudarthroses].

Deformity with palmar bone resorption can be observed in 20-50% of scaphoid pseudarthroses. A palmar wedge-shaped defect develops after repositioning and debridement of the pseudarthrosis. In the present paper 16 cases in which operations with cancellous bone grafting and palmar buttress plate osteosynthesis in addition were performed are presented. In all but 1, the pseudarthrosis united. All patients were pain-free at follow-up examination a minimum of 9 months (mean 28 months) only slightly reduced. Grip strength and mobility were after operation. The persisting pseudarthrosis necessitated wrist arthrodesis because of radiocarpal arthrosis. Metal slackening with erosion and rupture of the flexor pollicis longus tendon occurred in 1 patient. Palmar buttress plating is a biomechanically consistent form of osteosynthesis. It neutralizes all relevant forces. This means that cancellous bone grafts are sufficient, whereas lag screw or tension band osteosyntheses need cortico-cancellous grafts to resist compression forces. Stability and better chances of healing of pure cancellous bone grafts are the main advantages of palmar buttress plating in scaphoid pseudarthroses.

Bone Plates↗
PubMed1993

Leukocyte-endothelial cell interactions in the liver after hemorrhagic shock in the rat.

Leukocyte-endothelial cell interactions in rat livers were investigated using intravital fluorescence microscopy following hemorrhagic shock (MAP at 40 mm Hg for 60 min) and resuscitation. Thirty minutes after resuscitation, when MAP was higher than 100 mm Hg, sinusoidal perfusion was only slightly reduced (>90% of controls). Firm adhesion of leukocytes increased to 370 +/- 54 leukocytes/mm2 after shock and resuscitation compared to control animals (48 +/- 8/mm2; mean +/- SEM; P < .01). Leukocyte-endothelium adhesion was highest in the portal areas and lowest in midzonal and pericentral regions (relationship:2.0: 1.1:1.0). Pretreatment with dexamethasone (5 mg/kg bw) resulted in a dramatic rise of adherent leukocytes following hemorrhagic shock (920 +/- 62/mm2; P < .001). Pretreatment with ibuprofen (15 mg/kg bw) resulted in a similar increase of adherent leukocytes after hemorrhagic shock (750 +/- 60/mm2; P < .001), while pretreatment with MK 886(10 mg/kg), inhibitor of lipoxygenase pathway, reduced leukocyte adhesion slightly (270 +/- 38/mm2). The results reveal that leukotrienes, e.g., released by activated macrophages, are involved in the regulation of leukocyte adhesion in liver sinusoids following hemorrhagic shock and resuscitation. The negative effect of dexamethasone and ibuprofen on hepatic leukocyte adhesion, however, has to be considered for therapeutic use.

Animals↗
PubMed1992

The impact of liver preservation in HTK and UW solution on microcirculation after liver transplantation.

Severe microcirculatory disturbances due to endothelial cell damage and leukocyte adherence during reperfusion of transplanted livers are considered to contribute to early graft failure. Since the degree of reperfusion injury after liver transplantation depends on the length of preservation time and the solution used for preservation, the aim of our study was to assess three solutions with respect to microvascular perfusion and leukocyte adhesion. Therefore, rat livers were stored up to 24 h in Euro-Collins (EC), University of Wisconsin (UW), or histidin-tryphtophan-ketoglutarate (HTK) solutions prior to orthotopic transplantation. The livers were studied in situ 60 min postoperatively using intravital fluorescence video microscopy. Using simple syringe flushing (10 ml), sinusoidal perfusion decreased below 50% in EC preserved livers after 8 h preservation, in HTK preserved livers after 16 h preservation, and remained higher than 70% in livers preserved in UW up to 24 h. Permanent adhesion of leukocytes was increased more rapidly in organs after 1, 8, 16, and 24 h preservation in HTK (16%, 15%, 34%, and 49.7% +/- 4.7%) compared to those preserved in UW (15%, 18%, 17%; and 32.7% +/- 3.3%; P<0.05). Using a 10-fold volumn of the organ weight of HTK solution during the harvesting procedure, with an 8 min equilibration period, sinusoidal perfusion (39.6 +/- 4.7%) and leukocyte adhesion (42.7 +/- 3.1%) were not improved after 24 h. In contrast, equilibration with a volumn of approximately 40-times the liver weight improved sinusoidal perfusion (70.8% +/- 2.7%; P < 0.01) and leukocyte adhesion (24.9% +/- 3.1%; P < 0.01) significantly. Thus, using HTK solution, simple flushing prior to long-term cold storage resulted in microcirculatory disturbances when compared to UW solution. Larger volumns of HTK solution with an additional equilibration period of 8 min, however, reduced leukocyte adhesion and improved sinusoidal perfusion to a similar degree as UW solution.

Adenosine↗
PubMed1992

Improvement of liver preservation by the calcium channel blocker nisoldipine. An experimental study applying intravital microscopy to transplanted rat livers.

It has been shown recently that inclusion of the calcium channel blocker nisoldipine to University of Wisconsin (UW) solution significantly improves survival after rat liver transplantation. To further elucidate the mechanisms involved, rat livers were stored for 1 h in UW solution with or without the addition of 1.4 microM nisoldipine (Miles, West Haven, Conn., USA). The liver grafts were investigated in vivo 90 min after transplantation by intravital fluorescence microscopy. Sinusoidal perfusion was reduced in all sublobular regions of the liver in the UW group (e.g. portal area: 76.7 +/- 2.1%) and in the nisoldipine group (85.8 +/- 1.5%). Diameters of liver sinusoids were comparably reduced in the UW and nisoldipine groups indicating that nisoldipine did not cause vasodilatation. Adhesion of leukocytes, however, rose significantly after liver transplantation particularly in periportal regions (25.8 +/- 2.5%) compared to controls (17.1 +/- 2.8%; P < 0.05). Adhesion of leukocytes was reduced when nisoldipine was included in UW solution (13.3 +/- 1.7%; P < 0.05). Administration of latex particles, which were given in additional experimental groups, demonstrated an impressive increase in phagocytic activity of Kupffer cells after liver transplantation in periportal and pericentral areas (161 +/- 14% and 184 +/- 19% of controls). Phagocytosis was significantly reduced by nisoldipine in the periportal region (101 +/- 10%; P < 0.01). Thus, the beneficial effect of nisoldipine was most pronounced in periportal regions, where the majority of Kupffer cells are located and leukocyte adhesion was at a maximum.

Adenosine↗
PubMed1992

[A simple method for repositioning metatarsal fractures].

Because of small direct contact to the fracture fragments reduction of metatarsal fractures can be achieved only indirectly by applying traction to the toes. In this article a method for simple direct manipulation of the distal main fragment of metatarsal fractures is described: A K-wire is drilled in dorsi plantar direction across the head of the fractured metatarsal and mounted on a traction bow. In this manner the distal fracture fragment can be moved in all directions and placed exactly onto the proximal fragment. All 8 patients with multiple metatarsal fractures could be treated by closed reduction and percutaneous pinning. The described method allows simple and precise reduction of metatarsal fractures, reduced x-ray exposure of the surgeon's hand by short operation times, and manipulation for fracture reduction outside the x-ray beam.

Bone Wires↗
PubMed1992

[Thumb reconstruction with cryopreserved autogenous thumb skeleton and microneurovascular flap].

This paper describes a procedure for thumb reconstruction using autogenous cryo-conserved bone from the thumb itself. In a case of severe explosion injury, the thumb and index finger were amputated at the carpometacarpal joint level and the remaining fingers at the distal interphalangeal joint level. Severe soft tissue damage and lesion of both the superficial and deep palmar arterial arches rendered customary surgical procedures for thumb reconstruction impossible. The cryo-conserved bone was replanted following soft tissue healing and then covered with a free radial forearm flap. This procedure resulted in a stable and painfree thumb and provided satisfactory grip.

Adult↗
PubMed1992

Reduction by superoxide dismutase of leukocyte-endothelial adherence after liver transplantation.

One hour after orthotopic rat liver transplantation, hepatic microcirculation and adhesion characteristics of leukocytes to the endothelial wall were studied with intravital microscopy. Cold storage for 1 and 8 hours in Euro-Collins solution resulted in reduction of perfused sinusoids to 83% and 48% and a decrease of leukocyte velocity from 417 microns/sec in controls to 311 microns/sec and 269 microns/sec, respectively. Additionally, the number of permanently adherent leukocytes rose from 4% in controls to 33% and 43% after cold storage for 1 and 8 hours. Intravenous injection of the free radical scavenger human recombinant superoxide dismutase (40 mg/kg) during reperfusion resulted in marked improvement of the hepatic microcirculation after both 1 and 8 hours of cold storage (91% and 69% perfused sinusoids; 420 microns/sec and 350 microns/sec leukocyte velocity; p less than 0.05). Furthermore, the percentage of permanently adherent leukocytes decreased to 13% and 28% after 1 and 8 hours of cold ischemia, respectively. These results support the hypothesis that oxygen-derived free radicals contribute to leukocyte adherence and microcirculatory failure after cold liver ischemia and transplantation. Thus, application of oxygen free radical scavengers during liver transplantation procedures might be useful to improve graft function.

Animals↗
PubMed1991

Microcirculatory disturbances and leucocyte adherence in transplanted livers after cold storage in Euro-Collins, UW and HTK solutions.

Integrity of the hepatic microcirculation and maintenance of endothelial cell viability are critical components in preventing primary non-function after liver transplantation. Therefore, hepatic microcirculation and leucocyte-endothelial interaction were studied in rat livers stored for 1 h in Euro-Collins (EC), University of Wisconsin (UW), and histidine-tryptophan-ketoglutarate (HTK) solutions and subsequently transplanted. One hour after transplantation surgery, the livers were exposed under an intravital fluorescence microscope. After injection of the leucocyte marker acridine orange (1 mumol/kg), six pericentral fields were observed for 30 s and experiments were recorded continuously. The percentage of perfused sinusoids was reduced in the livers in the EC group (82.9%) in contrast to the UW (93.2%) and HTK groups (91.0%). Livers in the EC group showed a reduction in the diameters of pericentral sinusoids (7.3 +/- 0.2 microns; mean +/- SEM) compared with the UW group (9.5 +/- 0.2 microns; P less than 0.05) and HTK group (10.2 +/- 0.8 microns; P less than 0.05), indicating substantial cell swelling in livers stored in EC solution. Permanent adherence of leucocytes was most frequently observed in the EC group (33.5 +/- 1%), while this phenomenon was less pronounced in the UW group (14.5 +/- 1.1%; P less than 0.05) and HTK group (16.3 +/- 0.7%; P less than 0.05). Conversely, temporary adherence of leucocytes was reduced in the EC group (19.7 + 1.3%) compared with the UW group (30.5 + 2.1%) and the HTK group (34.4 + 0.8%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1991

Hepatic microcirculatory disturbances due to portal vein clamping in the orthotopic rat liver transplantation model.

Most modifications and applications of the orthotopic rat liver transplantation (ORLT) model require clamping of the portal vein, thus leading to ischemia of the gut. The purpose of this study was to evaluate the effect of portal vein clamping during ORLT on hepatic microcirculation and leukocyte--endothelial interaction by intravital fluorescence microscopy. ORLT were performed following 1 hr of cold storage in EuroCollins solution without (standard group) and with insertion of a portojugular shunt (shunt group) to minimize intestinal ischemia. ORLT induced reduction of perfused sinusoids (83%) and velocity of leukocytes (311 +/- 4.5 microns/sec; mean +/- SEM) compared with nontransplanted controls (99% and 417 +/- 4.9 microns/sec). Portojugular shunt during ORLT improved hepatic microvascular perfusion (89% and 355 +/- 3.4 microns/sec; P less than 0.05). Furthermore, percentage of permanent and temporary adherent leukocytes decreased significantly when a portosystemic shunt was applied (from 33.5 +/- 1% to 22.1 +/- 1% and 19.7 +/- 1.2% to 14.0 +/- 0.9%; P less than 0.05). The results of the study reveal that intestinal congestion and reperfusion results in a rise in leukocyte adhesion to the sinusoidal wall and in disturbances of the hepatic microcirculation. It seems likely that increased endotoxin concentrations in the portal vein induce an activation of hepatic macrophages that subsequently cause release of chemoattractant mediators. In conclusion, side effects of intestinal ischemia during experimental liver transplantation surgery on liver function due to release of chemoattractant mediators should be considered when experimental data are transferred to clinical settings.

Animals↗
PubMed1991

[Reconstruction of large foot sole areas with microsurgical tissue transfers].

In 14 patients with microsurgically reconstructed areas of the sole videografic gait analysis was performed. The best results are reached after reconstruction of the forefoot. Loss of more than two thirds of the sole leads to functional impairment. For all reconstructed areas and all types of flaps gait is improved significantly by shoe adaptation: elevation of the shoe under the reconstructed part of the sole directs the main load to the opposite side of the foot and by this relieves the reconstructed area. Even bone corrections can reduce load on a circumscribed area.

Foot↗
PubMed1991

Transferred triage to a level I trauma center in a mass catastrophe of patients; many of them with burns.

Three airplanes were involved in an airshow accident at the Ramstein military airbase on 28th of August 1988 causing immediate 45 dead and approximate 400 injured people. As a Level I Trauma facility we received 47 patients in different state of distress direct from airfield within an hour. The disaster plan was activated and sufficient personal and infrastructure could be mobilized.

Accidents, Aviation↗
PubMed1991

[Rupture of the tendon of the m. flexor pollicis longus--a rare complication after surgery on the scaphoid bone].

Tendon ruptures in the hand without previous direct trauma are rare. Two cases are reported on with attrition of the flexor pollicis longus tendon. The first tendon rupture was along a dislocated cortico-cancellous bone graft following a Matti-Russe procedure; the second was by attrition over the screw of an AO-plate following internal fixation in scaphoid nonunion. Immediate tendon repair by interposition of a short tendon graft or by transposition of the superficialis flexor tendon of the ring finger is the treatment of choice. Further tendon ruptures can arise if surgical intervention is delayed.

Adult↗
PubMed1991

[Experiences with continuous nerve block of the wrist].

Continuous nerve blocks are effective analgesics for physiotherapy following operative procedures on gliding tissues. In the upper extremity, continuous axillary blocks are regularly used, leading to weak muscular action and even paralysis, although active muscle action is wanted. With continuous wrist blocks, extrinsic motor function of the hand remains undisturbed. Placement of a polyethylene catheter near the nerves with instillation of a local anesthetic (carbostesine 0.5, 3-4 ml per nerve) provides complete anesthesia of the hand without loss of extrinsic motor function. After 124 nerve blocks in 60 patients, no complications (infections, nerve irritations or lesions) have been observed. Continuous wrist blocks are indicated for postoperative treatment after tenolysis, joint mobilisation or arthrolysis, open reduction and internal fixation and in certain cases of chronic pain care.

Analgesia↗