Biomedical subjects

D Palmes

Publications and source records attributed to D Palmes.

22 records · Page 2Linked to original sources

PubMedDate not supplied

A new clamping technique for biomechanical testing of tendons in small animals. aprobst@uni-muenster.de.

When biomechanical properties of tendons are studied, the technique of clamping the tendons in the testing machine presents a methodological challenge, especially when murine tendons are examined. These short tendons tend to rupture at the transition line to the fixation, leading to false interpretations. Therefore a new clamping technique for investigation of healthy murine Achilles tendons (n = 50) was developed, in which the intramuscular tendon fibers were fixed between two paper strips and the calcaneus was wedged into a conical slot in a wooden block and then mounted in the testing machine (n = 20). This technique was compared with the conventional clamping technique that fixes both ends of the tendon by clamps (n = 15) and an earlier described method that used glue or plastic cement for the fixation of the intramuscular tendon fibers and calcaneus in the testing machine (n = 15). When tested by the new clamping technique, 17 tendons ruptured intratendinously at a mean tensile force of 8.4 +/- 1.1 N. Three Achilles tendons (17%) tore at the site of paper fixation and had to be excluded from investigation. Data from 73% of the measurements fixed by gluing had to be excluded because slippage of the proximal tendon fibers and contamination of the tendon with glue occurred. All the conventionally clamped tendons ruptured at the site of fixation at a mean tensile force of 6.1 +/- 2.3 N (p < .05). This was 30% lower than with the new clamping technique. Thus, the newly developed clamping technique enables investigators to obtain more valid biomechanical studies of the murine Achilles tendon.

Achilles Tendon↗

PubMedDate not supplied

Laparoscopic fluorometry: a new minimally invasive tool for investigation of the intestinal microcirculation.

The aim of this study was to develop and establish a new system of laparoscopic fluorometry for the purpose of investigating the intestinal microcirculation. In 25 pigs (German Landrace, 16-25 kg body weight), ischemia was established in two segments (A, irreversible; B, reversible ischemia; C, internal control) of the small intestine by a laparoscopic technique. Microcirculation in the segments was assessed by laparoscopy at a second-look operation 24 h later by means of the fluorescence system Endoscan. The fluorescence of the three bowel segments was measured by arbitrary dye fluorescence units (DFU) 15 min after starting reperfusion, before and after injection of sodium fluorescein (NaFlu, 0.25 mg/kg body weight). The dividing line between viable and nonviable bowel tissue was established from the inflow and outflow rates of NaFlu with the aid of ROC (receiver operating characteristic) curves. The specificity and sensitivity of the new method were evaluated by correlating the results with the viability of each intestinal segment as predicted by three laparoscopically experienced surgeons and by histological examination. By means of the calculated separation sharpness (fluorescence index at 2 min >0.5, outflow factor of NaFlu at 10 min >20%), the overall predictions of intestinal viability in all 25 animals achieved a sensitivity of 93.5% and a specificity of 94.1% by laparoscopic fluorometry, versus a sensitivity of 70.8% and a specificity of 87.5% for the prediction of bowel viability by ordinary laparoscopic technique. Used as an adjunct to conventional laparoscopy, laparoscopic fluorometry brought significant gains in sensitivity and specificity in the distinction between reversible and irreversible intestinal ischemia.

Animals↗

PubMedDate not supplied

Surgical techniques of orthotopic rat liver transplantation.

Liver transplantation in rats is frequently used as a transplantation model. Although liver transplantation in larger laboratory animals such as dogs and pigs is technically easier, the rat has become the most important subject for experimental liver transplantation because of the availability of genetically defined animals. Numerous surgical techniques have been developed that permit the investigator to carry out studies with high clinical relevance. In this article the principal models of orthotopic rat liver transplantation and their technical modifications of vessel anastomoses, rearterialization, and bile duct reconstruction techniques are reviewed. More than 20 transplantation models are described in detail and demonstrated with clear illustrations. Finally, the advantages and uses of all the surgical procedures (e.g., suture and cuff anastomoses, bile duct anastomoses, and rearterialization techniques), specific problems, and survival criteria are discussed and the experiences of investigators who applied these techniques are analyzed. In conclusion, an overview and critical evaluation of all surgical techniques of orthotopic rat liver transplantation are given, together with instructions for learning these techniques.

Animals↗

PubMedDate not supplied

Hepatic vein catheterization: a new technique in rats.

Blood samples taken directly from the hepatic veins are often required for evaluation of liver function or ischemia/reperfusion injury and for direct determination of metabolic products of the liver. In the rat, blood samples are usually obtained by direct puncture of the hepatic veins. Successful catheterization of these small vessels is only possible under direct vision because great dexterity is needed to persuade the catheter to enter the hepatic vein. In this report a procedure for hepatic vein catheterization under direct vision is described in the rat. After performing a median laparotomy, a flexible catheter (Buchbinder, 3.0 F/1 mm, as used in cardiology) with a bent end is inserted into the infrahepatic vena cava. Under direct vision through the thin walls of the inferior vena cava the bent end of the catheter is slowly pushed up until the tip slides into a hepatic vein, which opens into the inferior vena cava at a right angle. Selective catheterization of the desired hepatic vein is possible by rotating the catheter and changing the position of its tip. This is a reliable new technique of hepatic vein catheterization in rats, by which blood samples can be collected directly from the hepatic veins.

Animals↗