Micro-CT imaging as a method for comparing perfusion in graduated-height and single-height surgical staple lines

Background

Wound healing is a goal for advanced technology in the surgical space to benefit clinical outcomes. Surgical staplers are commonly used in a variety of open and minimally invasive abdominal and thoracic procedures. Assessment of wound healing traits, such as perfusion, has been challenging due to technical limitations. A novel technique that utilizes micro-computed tomography methodology to measure perfusion was designed to compare the micro-perfusion of staple lines between commercial stapler reloads that employ different staple height strategies.

Materials and methods

Following an Institutional Animal Care and Use Committee-approved protocol, rats were euthanized and immediately heparinized prior to a subtotal gastrectomy with either graduated-height or single-height staples. Rats were then perfused with barium, following which stomachs were removed and immediately fixed in formalin to prevent degradation. Stomachs were then imaged using micro-computed tomography and subsequent analysis was utilized to quantify fluid volume and patent vasculature proximity to staples within the staple line region for each group.

Results

Average perfusion volume was significantly higher with graduated-height staples (0.33% ± 0.18%) compared to single-height staples (0.16% ± 0.09%, P=0.011). Average vessel-to-staple line distance was not significant but trended lower with graduated-height staples (0.35±0.02 mm) compared to single-height staples (0.36±0.03 mm, P=0.18).

Discussion

Graduated-height staples had significantly higher perfusion volume than single-height staples, which likely has a downstream benefit on wound healing and clinical outcomes.

Conclusion

This study shows a higher perfusion volume around the staple lines using graduated-height staples as compared to single-height staples and this may contribute to better wound healing in patients.

Laparoscopic live donor nephrectomy: Are ten cases per year enough to reach the quality standards? A report from a single small-volume transplant center

BACKGROUND

Laparoscopic live donor nephrectomy is the preferred method of kidney donation in high-volume US transplant centers, but for small transplant programs the question of the minimal case load per year necessary to reach the quality standards is open.

PATIENTS AND METHODS

From 1996 to 2007 we performed 130 live kidney donations including 93 laparoscopic donor nephrectomies followed by transplantation in a community hospital with an average case load of 10 laparoscopic cases per year. We compared the results after 37 open and 93 laparoscopic live donor operations with respect to operating time, conversion rate, complications, and recipients' outcome.

RESULTS

There were no significant differences in terms of safe outcome of donor patients after open or laparoscopic donor nephrectomy. The mean operating time was significantly shorter (p < 0.001) in the open group (125 min, OG) than in the laparoscopic group (150 min, LG). Mean hospital stay was significantly shorter (p < 0.001) in LG (6.8 days) versus OG (9.7 days). The conversion rate was 3.2% in the LG. Postoperative complication of donors consisted of temporary nerve irritation (two patients) and retroperitoneal hematoma (one patient) in the LG, and wound infection followed by hernia formation (one patient) and ileus 1 year after organ donation (one patient) in the OG. Safe outcome of the recipients after open (RaOD) or laparoscopic donation (RaLD) was similar. Uneventful transplantation occurred in 94.6% of the RaOD and in 92.5% of the RaLD. One kidney was lost due to renal vein thrombosis (RaLD). Mean postoperative creatinine after 4 weeks showed no difference between RaOD (1.6 mg/dl) and RaLD (1.7 mg/dl).

CONCLUSION

Approximately ten cases per year may be enough to ensure safety and quality of laparoscopic live donor nephrectomy.

[The way to establish laparoscopic donor nephrectomy as the method of choice in live kidney donation--a single centre experience]

INTRODUCTION

In contrast to the USA, laparoscopic donor nephrectomy is rarely practised in German transplant centres. Safety concerns and difficulties with the learning curve of this advanced laparoscopic procedure are the main obstacles to the establishment of this operation.

PATIENTS AND METHODS

From 1998-2005, we performed laparoscopic kidney procurement in 50 live kidney donors on an intention to treat basis harvesting a total of 29 left and 21 right kidneys for transplantation.

RESULTS

Negative adverse effects on the donor side were temporary nerve irritation (2 patients) and postoperative retroperitoneal hematoma. Reasons to convert to open nephrectomy were bleeding (2 patients) and adhesions (1 patient). On the recipient side, one kidney was lost due to renal vein thrombosis. Three patients required short-time dialysis after transplantation. All other kidney transplants worked without any problems.

CONCLUSION

Laparoscopic donor nephrectomy is a safe procedure and has been established as the method of choice for live kidney donation in our hospital.

Laparoscopic live donor nephrectomy for right kidneys: Experience in a German community hospital

BACKGROUND

Laparoscopic live donor nephrectomy has become the new gold standard for kidney procurement in many high-volume transplant centres worldwide, but it is often limited to left-sided donor kidneys. Concerns about adequate anatomical renal vessel length and sufficient surgical exposure are the main obstacles to the use of the laparoscopic approach for right kidney live donors as well.

MATERIAL AND METHODS

From 1998 to 2006 we performed laparoscopic kidney procurement in 73 live kidney donors on an intention-to-treat basis, harvesting a total of 48 left (LKG) and 25 right kidneys (RKG) for transplantation. We compared these two groups with respect to operating time, conversion rate, complications, hospital stay, and recipient outcome.

RESULTS

There were no differences in outcome of donor patients after left (D-LKG) or right laparoscopic donor nephrectomy (D-RKG). Operating time was 160 min in D-RKG versus 164 min in D-LKG. Warm ischemia was below 150 s in both groups. Hospital stay was 7.0 (D-RKG) versus 6.7 days (D-LKG). Negative events on the donor site were one temporary nerve irritation in each group and one postoperative retroperitoneal hematoma in the left kidney group. Reasons to convert to open nephrectomy were bleeding in two patients in the left kidney group and adhesions in one patient in the right kidney group. The outcome of the recipients after left (R-LKG) or right kidney (R-RKG) transplantation was similar. One kidney was lost due to renal vein thrombosis (R-LKG). Postoperative ureter complications occurred in one patient of each group. One patient of the R-RKG and two patients of the R-LKG required lymphocele fenestration. All other kidney transplants worked without problems.

CONCLUSION

Laparoscopic donor nephrectomy is a safe procedure and has been established as the method of choice for live kidney donation in our clinic. Laparoscopic procurement of right and left kidneys can be performed with comparable quality and outcome for donors and recipients.

Local administration of TGF-β1 to reinforce the anterior abdominal wall in a rat model of incisional hernia

The purpose of this study was to investigate different forms of the local application of TGF-beta(1) for augmentation of the anterior abdominal wall in an appropriate model of an incisional hernia. Sixty male Sprague-Dawley rats were divided into six groups. Artificial defects of the anterior abdominal wall were closed with one of the following methods: running Prolene suture, Vicryl mesh, prolene suture followed by an intramuscular injection of 1 mug TGF-beta(1), Vicryl mesh coated with 1 mug TGF-beta(1), and prolene suture coated with 1 mug TGF-beta(1). A control group did not receive any defect and treatment. Six weeks after operation, tensile strength, collagen content, gene expression of collagen I and III, blood vessels, and thickness of collagen fibres were evaluated. Tensile strength was strongest in the controls (14.2 (10.5-18 N)). There was no increase in tensile strength due to the administration of TGF-beta(1). On the contrary, bolus injection of the growth factor resulted in a significantly decreased strength of the wound tissue when compared to the groups 1, 4, 5, and 6 (9.1 (4.2-9.1 N)). These results correlated with the gene expression of collagen I and III. Local application of TGF-beta(1) did not augment the strength of the abdominal wall after 6 weeks.

Die Technik der laparoskopisch-thorakoskopischen Ösophagusresektion beim Ösophaguskarzinom - Erste Erfahrungen

Esophageal resection for carcinoma is still associated with high mortality and morbidity. Minimally invasive techniques are regarded to reduce operative trauma. However, to date only few studies on minimally invasive esophageal resection have been published. We describe in detail the technique of combined laparoscopic and thoracoscopic esophageal resection with gastric-pull-up and conventional open cervical anastomosis for esophageal squamous carcinoma. Prone positioning of the patient with bilateral lung ventilation was used during the thoracoscopic part of the operation. Our first experiences in 5 patients confirm the feasibility of the technique. We did not observe any surgical related adverse incidences and found the typically advantages of minimally invasive surgery, such as early mobility, less pain and a comfortable cosmetic result in our patients. Although the number of procedures is to low to decide the value of minimally invasive surgery for esophageal cancer, we think it could be a promising technology to reduce mortality and morbidity for esophageal resection.

A pig hemorrhagic shock model: oxygen debt and metabolic acidemia as indicators of severity

"Uncontrolled bleeding," "a controlled prefixed bleeding volume," or "controlled decrements in blood pressure" are traditional models of experimental hemorrhagic shock. They are influenced by compensatory mechanisms and do not adequately reflect the severity of the cellular insult as a major target for therapeutic strategies. The aim of this study was to develop an animal model that uses oxygen debt (OD) and metabolic acidemia as indicators of hemorrhage severity. Twenty-five female pigs (mean weight: 23.8 kg) were anesthesized and randomized to 1 of 5 groups of increasing OD (<50 through >120 mL/kg). The predetermined OD was accrued by hemorrhage uniformly over 60 min and followed by retransfusion. The animals were allowed to recover under anesthesia for 200 min and were then observed for 3 days. The extent of metabolic derangements were quantified by arterial base excess (BE) and plasma lactate (LAC) measurements. OD, BE, and LAC were shown to be superior as predictors of outcome in comparison with traditional variables ("bleeding volume," "blood pressure," "cardiac output") in correlation and regression. Of the analyzed predictors of outcome, BE and LAC showed the highest correlation to levels of OD (r = -0.78, 0.8 respectively; P < 0.0001), and regression models were developed. The LD50 for OD was 95.0 mL/kg, for BE -15.3 mmol/L and for LAC 7.7 mmol/L. By using the developed regression models, it is possible to estimate accurately the actual level of OD from BE and LAC values obtained during hemorrhagic shock. OD, BE, and LAC appear to be optimal indicators of severity for a pig hemorrhagic shock model.

The impact of gas laparoscopy on abdominal plasminogen activator activity

BACKGROUND

The impairment of intestinal perfusion following induction of a pneumoperitoneum may lead to a reduction of peritoneal tissue plasminogen activator (tPA) activity and a concomitant increased risk of adhesion formation.

METHODS

Pigs were laparotomized to take peritoneal biopsy specimens from the cecum, the ileum, and the abdominal wall. A 15 mmHg pneumoperitoneum was established for 3 h by the insufflation of carbon dioxide (group 2, n = 6) or helium (group 3, n = 6). Group 1 (n = 7) received no gas insufflation. After a 2-h recovery period, additional tissue samples were harvested. Specific tPA activity was then determined in the tissue extracts.

RESULTS

During surgery, specific tPA activity decreased in all the samples. As compared with the control group (100%), this reduction was strongly aggravated in the cecum (-67.6%, p < 0.05) and the ileum (-70.8%) of the CO2 group but only slightly aggravated in the helium group. The parietal peritoneum was not specifically affected by gas insufflation.

CONCLUSION

The use of a pneumoperitoneum with carbon dioxide significantly affects peritoneal tPA activity and thus may represent a stimulus for adhesion formation.

Extension of ischemic tolerance of porcine livers by cold preservation including postconditioning with gaseous oxygen

BACKGROUND

Transplantation of organs from nonheartbeating donors was recommended to reduce organ shortage. In vitro experiments with rat livers have shown that the warm ischemic tolerance of the liver may be extended by persufflation with gaseous oxygen during cold storage. The qualification of this method for procurement of livers harvested after cardiac arrest was tested in an in vivo approach with pigs.

METHODS

Livers from 15 donor pigs were explanted, heparinized, flushed with and stored in University of Wisconsin solution for 4 hr at 4 degrees C, and then implanted into 15 recipients. The organs were dissected immediately after cardiac arrest (group 1) or after 60 min of warm ischemia (groups 2 and 3). Group 2 livers received 75,000 IU of superoxide dismutase together with the flush solution and were persufflated with gaseous oxygen via the venous vascular system during cold storage. Main end point was survival after 5 days. Additionally, metabolic, functional and inflammatory criteria were measured in the blood.

RESULTS

All animals of the groups 1 and 2 survived, all animals of group 3 died within 3 hr after reperfusion. In all groups the blood parameters reflected significant damage of the livers. However, the ischemic damage was comparable in the groups 1 and 2 whereas the livers of group 3 exhibited significantly higher levels of aspartate alanine aminotransferase and lactate dehydrogenase, and a significantly elongated partial thromboplastin time 1 hr after reperfusion (P=0.016).

CONCLUSIONS

Venous systemic oxygen persufflation in combination with antioxidative medication is a promising new method of resuscitating ischemically altered livers from nonheartbeating donors for successful transplantation.

Negative side-effects of retention sutures for abdominal wound closure. A prospective randomised study

OBJECTIVE

To assess the effect of retention sutures on the postoperative course of patients after major abdominal operations.

DESIGN

Prospective, randomised study.

SETTING

Teaching hospital, Germany.

SUBJECTS

95 patients who were at increased risk of wound failure after major abdominal operations.

INTERVENTION

Conventional mass closure either with (n = 44) or without (n = 51) reinforcement by wire retention sutures.

MAIN OUTCOME MEASURES

Pain intensity on postoperative days 3, 6, 9, and 12, patients' acceptance, retention-suture-related morbidity, general morbidity.

RESULTS

Postoperative pain was overall more severe with retention sutures. On day 6, 31/49 control patients but only 13/41 patients with retention sutures were pain-free (p = 0.003, 95% CI 0.12 to 0.51). Twelve of 44 patients with retention sutures developed local complications of the sutures, and 21 of the 44 had to have them removed prematurely, in most cases because of intolerable pain.

CONCLUSIONS

Retention sutures used to close abdominal wounds cause inconvenience, pain, and specific morbidity.

Risks and benefits of preoperative high dose methylprednisolone in surgical patients: a systematic review

BACKGROUND

A single preoperative high dose of methylprednisolone (15 to 30 mg/kg) has been advocated in surgery, because it may inhibit the surgical stress response and thereby improve postoperative outcome and convalescence. However, these potential clinical benefits must be weighed against possible adverse effects.

OBJECTIVE

To conduct a risk-benefit analysis using a meta-analysis, to compare complication rates and clinical advantages associated with the use of high dose methylprednisolone in surgical patients.

METHODS

Randomised controlled trials of high dose methylprednisolone in elective and trauma surgery were systematically searched for in various literature databases. Outcome data on adverse effects, postoperative pain and hospital stay were extracted and statistically pooled in fixed-effects meta-analyses.

RESULTS

We located 51 studies in elective cardiac and noncardiac surgery, as well as traumatology. Pooled data failed to show any significant increase in complication rates. In patients treated with corticosteroids, nonsignificantly more gastrointestinal bleeding and wound complications were observed; the 95% confidence interval boundaries of the numbers-needed-to-harm were 59 and 38, respectively. The only significant finding was a reduction of pulmonary complications (risk difference -3.5%; 95% confidence interval -1.0 to -6.1), mainly in trauma patients.

CONCLUSION

For patients undergoing surgical procedures, a perioperative single-shot administration of high dose methylprednisolone is not associated with a significant increase in the incidence of adverse effects. In patients with multiple fractures, limited evidence suggests promising benefits of glucocorticoids on pulmonary complications.

Plasma concentration of biologically active fibronectin and fibronectin bound to gelatin-like material in a porcine model of hyperdynamic endotoxic shock

Due to its opsonizing role, plasma fibronectin (pFN) binds to circulating degradation products deriving from collagenous structures and mediates their elimination by the reticuloendothelial system (RES). In septic shock, an overflow of this material may lead to a lack of pFN and an impaired RES activity. In fact, low pFN levels have been reported to correlate with unfavorable clinical outcome. However, dysfunction of the RES is also caused by other shock related factors, and death from septic shock also has been observed in the presence of normal FN levels. To investigate the involvement of opsonic FN in the progression of sepsis, we discriminated between biologically active FN and FN bound to gelatin-like material in pigs developing a hyperdynamic endotoxic shock. All FN determinations were performed with the immunochemical assay. Discrimination between free FN and complexed FN was achieved by separation on gelatin sepharose. A continuous decrease of total FN and free FN was observed in the septic group reaching 57% and 50% of the initial level at the end of the 5-h observation period, respectively. However, a significant difference was not detected before both the microcirculatory and macrocirculatory alterations indicative of hyperdynamic endotoxic shock were completely established. Complexed FN was increased slightly in both groups without any group specific differences. We conclude that the FN-mediated opsonization of circulating gelatine-like material does not play a critical role in early circulatory shock.

The clinical impact of warmed insufflation carbon dioxide gas for laparoscopic cholecystectomy

BACKGROUND

Reports suggest that the insufflation of cold gas to produce a pneumoperitoneum for laparoscopic surgery can lead to an intraoperative decrease in core body temperature and increased postoperative pain.

METHODS

In a randomized controlled trial with 20 patients undergoing laparoscopic cholecystectomy, the effect of insufflation using carbon dioxide gas warmed to 37 degrees C (group W) was compared with insufflation using room-temperature cold (21 degrees C) gas (group C). Intraoperative body core and intra-abdominal temperatures were determined at the beginning and end of surgery. Postoperative pain intensity was evaluated using a visual analog scale and recording the consumption of analgesics.

RESULTS

There were no significant group-specific differences during the operation, neither in body temperature (group W: 36.1 +/- 0.4 degrees C vs group C: 35.7 +/- 0.6 degrees C) nor in intra-abdominal temperature (group W: 35.9 +/- 0.3 degrees C vs group C: 35.6 +/- 0. 6 degrees C). Postoperatively, the two groups did not differ in pain susceptibility and need of analgesics.

CONCLUSION

The use of carbon dioxide gas warmed to body temperature to produce a pneumoperitoneum during short-term laparoscopic surgery has no clinically important effect.

Evaluation of the effects of a pneumoperitoneum with carbon dioxide or helium in a porcine model of endotoxemia

BACKGROUND

The expansion of the laparoscopic techniques to the critically ill patient is currently under debate. In order to evaluate the potential risks of performing laparoscopy in a body with signs of sepsis, the effects of the pneumoperitoneum were studied in a porcine model of mild endotoxemia.

METHODS

Twenty-eight pigs were separated into four groups of seven animals: untreated control (C), 2 microg/kg/h endotoxin (E), endotoxin and a pneumoperitoneum (3 h, 15 mmHg) with CO2 (EC) or with helium (EH). Hemodynamic and homeostatic variables were studied for a period of 5.5 h. Primary endpoints were arterial and mucosal pH and the ATP content of the bowel wall. Statistical evaluation was performed using analysis of variance and the Bonferroni test.

RESULTS

Endotoxin infusion induced characteristic symptoms of early sepsis: increase of arterial CO2, pulmonary arterial, portal venous, and pulmonary artery wedge pressure, and decrease of arterial pressure, cardiac output, arterial and mucosal pH. An additional pneumoperitoneum led to aggravation of all criteria with significant alterations in arterial and mucosal pH, arterial CO2, wedge and portal venous pressure. The most striking derangement of mean values was observed for mucosal pH (EC: 7.40, EH: 7.54) and arterial pH (EC: 7.15, EH: 7.18). In group EC, two animals died in septic shock.

CONCLUSION

Applying a pneumoperitoneum during an ongoing sepsis significantly deteriorates hemodynamic and homeostatic variables, thus enhancing the risk of severe complications.

Preoperative high dose methylprednisolone improves patients outcome after abdominal surgery

OBJECTIVE

To assess the effect of preoperative high dose methylprednisolone on stress response and outcome.

DESIGN

Randomised, placebo-controlled, double-blind study.

SETTING

University hospital, Germany.

SUBJECTS

20 patients listed for abdominal surgery of whom 10 had major intra-abdominal interventions and 10 had incisional hernias repaired.

INTERVENTIONS

Methylprednisolone 30 mg/kg (100 ml) was given by slow intravenous infusion 90-60 minutes before operation. The control group received the same volume of sodium chloride.

MAIN OUTCOME MEASURES

Speed of convalescence, degree of fatigue, amount of pain, consumption of analgesics, breathing capacity, and hospital stay, as well as humoral and cellular mediators of the stress response.

RESULTS

Methylprednisolone significantly improved criteria of postoperative recovery, fatigue by 47%, (day 1), convalescence by about 45% (days 1-3), and breathing capacity (FEV1) between 47% and 29% (days 5, 7) (p < 0.05, ANOVA), and led to a significant reduction of median hospital stay of 4.5 days. C-reactive protein concentration was significantly decreased (by 46% on day 3) and T-cell activation was suppressed (day 1).

CONCLUSION

Outcome of the patients after conventional abdominal surgery is substantially improved by preoperative high dose methylprednisolone. This effect is more pronounced in patients having major operations.

CO(2) pneumoperitoneum: what we know and what we need to know

The development of the laparoscopic technique in surgery was so overwhelming that scientific evaluation could not keep in step. While investigators were still discussing the effects of the pneumoperitoneum on the healthy organism, laparoscopy was already performed in patients with an acute abdomen due to trauma or disease. Therefore, there is an urgent need of further experimental and clinical studies with relevant endpoints to gain external evidence concerning the benefits of diagnostic or therapeutic laparoscopy for critically ill patients. In experiments with pigs we have shown that even in a healthy organism perfusion and energy metabolism of the small bowel is impaired by a pneumoperitoneum with carbon dioxide. Under the conditions of a systemic inflammatory response syndrome induced by infusion of endotoxin, the negative effects of the pneumoperitoneum were significantly amplified. Furthermore, we found that the increased intracranial pressure as caused by a head injury was further enhanced during a pneumoperitoneum but not by the alternative method of mechanical wall retraction. The current literature dealing with the effects of a pneumoperitoneum in critically ill patients is still controversial. Our data support the results of those authors who hold the opinion that creating a pneumoperitoneum in patients with acute abdominal problems means an additional serious burden that in single cases may lead to a disaster. As evidence is lacking, the current extension of laparoscopy into the field of intensive care medicine is still a human experiment that must be performed with high responsibility, extensive monitoring, and according to the rules of a clinical study.

Endoscopic use of fibrin adhesives: problems when injecting through long catheters

When used endoscopically fibrin adhesives are injected through twin-lumen catheters, which can reach up to 180 cm in length. Because fibrinogen solutions have a high viscosity, significant delivery forces are necessary, resulting in discomfort for the operator. Therefore, the two predominant fibrin sealants were characterized with respect to their viscosity and the force needed for their injection. Viscosity was determined at 18 degrees C, 25 degrees C, and 37 degrees C in a micro-Ostwald viscosimeter. Additionally, the maximum forces needed for injection through a 27-cm and a 160-cm catheter were determined at 25 degrees C in an Instron materials testing machine. Compared with preparation A the viscosity of preparation B was 8.0-34.5 times higher at 18 degrees C, 4.6-13.8 times higher at 25 degrees C and 3.1-6.4 times higher at 37 degrees C. In consequence, the delivery forces were 1.5-2.5 times (27 cm probe) and 3.4-4.5 times (160 cm probe) the values determined for preparation A. For preparation B a maximum load of 3.8 kg was necessary for injection. Assuming that different adhesive preparations have the same effect, a preparation of lower viscosity seems to be more suitable for use via long catheters than a preparation of high viscosity.

Endischemic oxygen persufflation to improve viability of marginally preserved donor livers

The quality of cold-stored donor livers slowly declines beyond approximately 12 h, although these organs may still be used for clinical transplantation. The aim of the present study was to improve the energetic status and viability of long-term-preserved livers by short-term gaseous oxygen insufflation prior to implantation of the organ using a technique that has already been shown to promote aerobic energy metabolism during hypothermia. Livers from ten male Wistar rats were isolated, rinsed blood-free. Five livers (group 1) were stored for 48 h at 4 degrees C in UW preservation solution, and five livers (group 2) were isolated and stored in the same manner for 47 h, and were then, during the last 60 min of the preservation period, connected to a persufflation device and gaseous oxygen was introduced into the organ via the inferior caval vein, with the liver still immersed in cold UW solution. This technique of endischemic gaseous oxygenation resulted in a significant normalization of vascular resistance upon isolated reperfusion in vitro and a reduction in hepatic efflux of alanine aminotransferase as well as glutamate dehydrogenase, which led to improved recovery of the reperfused grafts of group 2 as evidenced by an elevated energy charge potential at the end of the reperfusion period. In conclusion, the technique described seemed effective in enhancing the preoperative viability of marginal donor grafts.

Polyethylene glycol 4000 attenuates adhesion formation in rats by suppression of peritoneal inflammation and collagen incorporation

BACKGROUND

Postoperative separation of the peritoneal surfaces is a promising approach for the prevention of adhesion formation. Instillation of polyethylene glycol 4000 (PEG) was recommended as an appropriate method.

METHODS

In a time-course study in rats, efficacy and mode of action of PEG was investigated. Adhesions were induced by crushing of the cecum. Sixty animals were randomly allocated to three control groups with intraperitoneal instillation of 5 mL 0.9% NaCl and to three therapy groups treated with 5 mL 20% PEG. After 3, 7, and 21 days, adhesion grade, intraperitoneal leukocytes, and collagen incorporation into the adhesion strands were evaluated.

RESULTS

Administration of PEG resulted in a decrease of leukocytes by 43% (days 3 and 7), a reduction of the adhesion score by 85% (day 3), 77% (day 7), and 79% (day 21), and an impairment of collagen deposition by 54% (day 7) and 44% (day 21).

CONCLUSIONS

Coating the peritoneal surfaces with PEG is a highly effective measure to suppress the fatal sequence of posttraumatic inflammation, formation of initial adhesions, and their subsequent organization to strong permanent adhesion strands.

Successful transplantation of porcine livers after warm ischemic insult in situ and cold preservation including postconditioning with gaseous oxygen

BACKGROUND

In order to reduce the shortage of viable donor livers for organ transplantation, a method has been developed that allows even predamaged livers from nonheartbeating donors to be used as transplantable organs.

METHODS

Porcine livers were harvested 45 min after cardiac arrest of the nonheparinized donor, preflushed with heparinized saline solution, and subsequently rinsed with University of Wisconsin solution, to which superoxide dismutase was added as an oxygen free radical scavenger. Thereafter, the livers were persufflated with gaseous oxygen via the venous vascular system while immersed in University of Wisconsin solution at 4 degrees C for 4 to 5 hr.

RESULTS

After orthotopic transplantation, all of the livers conditioned with gaseous oxygen were able to support life-sustaining function during the whole observation period of 7 days post transplantation, while no survival of the recipients could be obtained without the described treatment.

CONCLUSIONS

The present study establishes a new perspective for the use of ischemically altered livers from nonheartbeating donors for organ transplantation under clinical circumstances.

[Evaluation of qualification regulations for medical faculties of German universities and recommendations for standardization]

The original reason for using the German "Habilitation" degree to mean that a candidade had qualified and could conduct research and teach at a university is no longer really valid, as this is being threatened by its importance to further careers. Medical faculties must discuss how this development can be curtailed. In order to check the current situation, the Habilitation degree systems of 36 medical faculties of German universities were compared with the aid of a scoring system. They differed dramatically. Conformity existed only in the demand for a doctoral dissertation, scientific publications and a lecture on approval. Concerning other criteria for qualification there was decreasing consensus in the following order: Habilitation thesis, commitment to teaching, further professional education, participation in congresses, inaugural lecture, qualification to teach, scientific activity, broad background in the discipline, and introduction to the faculty. Application of the scoring system with a maximum of 33 score points resulted in a mean value of 15.2 points and a range from 6 to 29 points. A significant decrease in the score values occurred with increasing age of the Habilitation degree (P = 0.002). Even if scoring systems are ambiguous and unfair, our analysis revealed serious differences in the quality of the Habilitation degree. Presuming that the German Habilitation degree should be maintained as a high-level qualification, we developed proposals that might be used to standardize this academic examination.

[Effect of pneumoperitoneum on hemodynamics and intestinal integrity in endotoxinemia: CO2 versus helium]

In a study in pigs pathophysiological effects of a pneumoperitoneum (PP) established during endotoxemia (2 micrograms/kg b.w./hr) were investigated. In this situation a PP with carbon dioxide (CO2) or helium induces a deterioration of systemic hemodynamics or acid-base-stability. Some of these effects threaten vital stability. PP with either gas causes a mucosal acidosis of the small bowel within the meaning of an impairment of intestinal oxygen supply. A CO2-PP adversely affects the intestinal energy metabolism and leads to significantly increased endotoxin levels in contrast to helium after desufflation of the abdominal cavity. Data of this study at least demand for a careful monitoring, if laparoscopy is performed in septic and critically ill patients.

[Effect of pneumoperitoneum on plasminogen activator activity in the abdomen]

In a study in pigs it was examined whether peritoneal plasminogen activator activity (PAA) is impaired by creation of a pneumoperitoneum (PP) with CO2 or with helium. The animals were anesthetised and laparotomised, and peritoneal biopsies were taken from the cecum, the ileum and the wound site. Then a PP of 15 mmHg was created with CO2 (Grp. 1, n = 6) or helium (Grp. 2, n = 6). Group 0 (n = 7) was left without gas insufflation. After a PP of 3 hrs and an additional observation period of 2 hrs further tissue samples were collected. In the biopsies specific PAA was determined. In all groups a decrease of specific PAA occurred. However, at the end of the experiment PAA was significantly lower in the cecum of the CO2-group (24.3 U/mg, 32.4%) when compared to the controls without gas (75.1 U/mg, 100%) or the helium group (65.1 U/mg 86.7%). Our data raise suspicion that insufflation of CO2 for laparoscopic intervention may enhance the risk of peritoneal adhesions by a suppression of PAA.

[Revitalizing donor livers after cardiovascular arrest with venous oxygen persufflation]

The experimental study investigates the resuscitation of livers procured from non heart beating donors by venous systemic oxygen persufflation in a pig transplantation model. In group 1 livers were harvested from donor animals after 60 min of potassium induced cardiac arrest. Livers were then flushed and preserved in 4 degrees C cold University of Wisconsin solution for 4 hrs. Then liver transplantation was performed in recipient animals. Animals of group 2 received the same treatment, but during hypothermic storage we applied venous systemic oxygen gas persufflation (VSOP) via the supra-hepatic vena cava. Livers of group 3 were harvested without warm ischemia and without oxygen treatment during cold ischemic storage and were then transplanted. All recipient animals of group 2 and 3 survived the five day follow-up time. All recipient animals of group 1 died a few hours after liver reperfusion due to circulatory shock or liver failure. The liver quality of group 2 recipient animals was similar to group 3 livers, because serum transaminase levels and blood coagulation test showed no significantly different values between those groups. Our data suggest that livers procured from non heart beating donors after 1 hr of cardiac arrest can be resuscitated and successfully transplanted by therapeutic treatment with VSOP.

[Analysis of the publication spectrum of 4 German-language medical specialty periodicals "Der Chirurg", "Der Unfallchirurg", "Langenbecks Archiv für Chirurgie" and "Medizinische Klinik"]

All 1994 publications of four leading journals in surgery, orthopedics and internal medicine in Germany (Der Chirurg, Der Unfallchirurg, Langenbecks Archiv für Chirurgie, Medizinische Klinik) were reviewed by means of a structured analysis. The type of article, authorship, number of references, geographical location, quality, and main conclusion (positive; neutral; negative) of each article were documented. The journals focused on clinical studies (32.2-59.6%), case reports (11.0-26.1%) and reviews (6.4-40.9%). Articles about surgical techniques were mainly found in Der Chirurg (16.9%), experimental studies in Der Unfallchirurg (14.7%) and Langenbecks Archiv für Chirurgie (25.7%). Most articles were written by university clinic personnel (62.6-81.4%). In 11.0-22.6% of all articles, the head of a clinic was the first author and the co-author in 36.5-58.7%. Women were found to be first author in 4% in surgery, and in 10.4% in internal medicine. Of a total of 495 publications, 53.9% were written in Northrhine-Westphalia, Bavaria or Baden-Württemberg and only 1.6% in the five new federal states. Of all articles 16.4% were by foreign authors, with 10.5% originating from German-speaking countries. The portion of controlled randomized trials ranged between 4.9% (Der Unfallchirurg) and 11.3% (Der Chirurg) of all published studies. Studies and case reports with negative results were found to be more evident in Der Chirurg and Langenbecks Archiv für Chirurgie (ca. 20%) as compared to Der Unfallchirurg and Medizinische Klinik (ca. 6%). All journals provided good general information about the actual developments in a variety of topics to the reader. However, some improvement concerning international contributions, participation of the new federal states, and the quality of studies is recommended.

Reduction of proteolysis by venous-systemic oxygen persufflation during rat liver preservation and improved functional outcome after transplantation

An increase of cytosolic proteolytic activity during ischemic preservation and consecutive tissue degradation have recently been recognized as a major pathogenetic factor for liver injury during ischemia/reperfusion. In the present study, we propose a method for preventing proteolytic tissue disintegration, which results in improved recovery of the liver after transplantation. Livers were harvested from rats and stored for 24 hr at 4 degrees C in University of Wisconsin solution (group A). Others were additionally persufflated with gaseous oxygen via the inferior caval vein during this time (group B). At the end of ischemic preservation, proteolysis was confirmed in group A, with significantly elevated tissue levels of free alanine and free amino groups, whereas proteolysis was prevented in group B. After transplantation, the integrity of the graft was significantly improved in group B, in which there was a 50% reduction of plasma activities of alanine amino-transferase and a twofold increase in hepatic bile production after the onset of reperfusion, as compared with group A. Moreover, venous-systemic oxygen persufflation during cold preservation significantly attenuated the rise in plasma levels of malondialdehyde (MDA) after liver transplantation. In conclusion, venous-systemic oxygen persufflation during ischemic storage prevents tissue proteolysis and reduces parenchymal injury after transplantation in vivo; this technique may, thus, represent a useful adjunct in long-term liver preservation with University of Wisconsin solution.

Influence of polyethylene glycol 4000 and dextran 70 on adhesion formation in rats

Studies on the prevention of peritoneal adhesions often address the impairment of adhesion formation by a special drug without any attempts to elucidate the working principles. In the present study PEG 4000 was compared with dextran 70 with respect to the influence on adhesion formation, inflammatory reaction, and collagen deposition. Adhesions were created in 30 rats by standardized crushing of the cecum. The animals were randomly allocated to 3 experimental groups receiving an intraabdominal instillation of 5 ml 20% PEG, dextran 70, or 0.9% NaCl. On Day 7 the adhesions were scored; additionally, the amount of leukocytes in the peritoneal cavity and the incorporation of collagen into the adhesion strands were determined. Administration of PEG resulted in a significant reduction of the adhesion score from 10.3 (NaCl) to 2.3, whereas dextran had no effect (score 11.0). This finding correlated with the leukocyte number which was reduced by 44% after PEG but was not affected by dextran. The collagen content of the adhesion strands was significantly decreased by PEG as well as by dextran when compared to the NaCl controls. In our model PEG was highly effective in the impairment of adhesion formation. The positive effect was mediated by a reduction of the inflammatory reaction which resulted in a decreased deposition of collagen into the adhesion strands.

H1-antagonism improves intestinal mucosal pH and heart function in porcine hypodynamic endotoxic shock

Porcine hypodynamic shock was induced by continuous infusion of 5 micrograms lipopolysaccharide/kg per hour. This resulted in a decrease of cardiac output from baseline values of 3.5 +/- .9 L/min to 1.5 +/- .8 L/min and a reduced left ventricular stroke work index in the endotoxin-group (n = 6 animals). Pretreatment with the H1-antagonist dimethindene (2 mg/kg) in a second group (n = 6) significantly prevented these effects. Furthermore animals pretreated with the H1-antagonist showed a stable mean arterial blood pressure, whereas the control endotoxin-treated group revealed a drastic reduction in mean arterial blood pressure (99 +/- 4.7 mmHg versus 65.8 +/- 10 mmHg after 240 min, respectively). Pulmonary function and systemic vascular resistance were not ameliorated by the H1-antagonist in hypodynamic shock. Gastrointestinal mucosal pH (pHi), which indicates oxygenation of the mucosa, was decreased by endotoxin-infusion (7.45 +/- .32 baseline value to 6.92 +/- .24 after 120 min). This parameter as well as base excess values and lactate levels were significantly improved by dimethindene-pretreatment (p < .05). These results may indicate a beneficial effect of H1-antagonist-pretreatment on endotoxin-induced deterioration of the microcirculation. Furthermore our results clearly demonstrated that only pretreatment before endotoxemia with H1-antagonism is effective, since infusion of H1-antagonist in hypodynamic shock 45 min after addition of endotoxin (n = 6 animals) did not improve the cardiovascular system or the microcirculation.

Effect of H1-antagonism on cardiovascular, pulmonary, and immunological dysfunction in porcine endotoxic shock

The definite role of histamine in early hyperdynamic septic shock is not yet clear. Therefore a randomized, controlled, blind trial was performed to investigate the effect of the H1-antagonist dimethindene in hyperdynamic porcine shock. Lipopolysaccharide (LPS) infusion (5 micrograms/kg/h) in anesthetized pigs (n = 6) in the control-group induced a hyperdynamic shock state with a decrease in mean arterial blood pressure, and systemic vascular resistance (SVR), and an increase in mean arterial pulmonary pressure and pulmonary vascular resistance (PVR). In the verum group (n = 6) dimethindene (2 mg/kg) administered 15 min before LPS application prevented the decrease in SVR significantly (p < .05) and ameliorated the increase in MPAP and PVR. The impairment in pulmonary function, as measured by the oxygenation ratio (PaO2/FiO2) in LPS-treated animals, was reduced by the H1-antagonist (p = .01). Tissue oxygenation was ameliorated by the H1-antagonist treatment, as demonstrated by plasma lactate levels and base excess values (p < .05, control group versus dimethindene group). The increase in tumor necrosis factor alpha by LPS infusion was not influenced by H1-antagonist pretreatment. The early decrease in SVR did not correlate with an enhanced nitric oxide formation, as measured by nitrate/nitrite plasma levels.

Beneficial effect of H2-agonism and H1-antagonism in rat endotoxic shock

Although histamine release is generally considered harmful in endotoxic shock, several data exist to doubt this view. Own previous studies in rats let us assume a possible beneficial effect only with H1-antagonists, however a detrimental effect on survival with H2-antagonists. Consequently H1- and H2-agonists and antagonists were studied to prove the hypothesis of a beneficial H2-agonistic and H1-antagonistic effect. Two randomized studies were performed in a standardized rat endotoxic shock model (45 mg of Escherichia coli endotoxin/kg body weight (b.w.)). In both, methylprednisolone (50 mg/kg b.w.) and saline were used as positive and negative controls, respectively. Study I compared the effects of H1- and H2-agonists (betahistine, .1 mg/kg/h, and impromidine, 100 micrograms/kg/h) with H1- and H2-antagonists (astemizole and famotidine both 1 mg/kg b.w.; 20 rats/dose). Study II was performed to estimate the dose-response relationship of a new, highly potent H2-agonist with additional H1-antagonistic features (BU-E 75: .01, .1, 1.0, 10, and 100 micrograms/kg/h; 20 rats/dose). Animals receiving impromidine or BU-E 75 all received omeprazole (1 mumol/kg b.w.) to suppress gastric acid secretion. In study I impromidine significantly increased the survival-time and -course compared to famotidine treated animals (p = .01 and p < .05). Study II showed a positive dose-response relationship of BU-E 75 with an increase in survival rates from 30% (.01 microgram/kg/h) to 70% (100 micrograms/kg/h). These data strongly support the hypothesis of a beneficial effect of H2-agonism and H1-antagonism on survival parameters in rat endotoxic shock.

Meniscal healing: a biomechanical study

Insight into the functional role of menisci has stimulated investigators to repair meniscal tears even in regions of poor vascularity. Data on scar strength resulting from different forms of therapy can be obtained applying biomechanical methods to animal models. With our new tear load propagation test, tissue strength in the scar as well as in the scar periphery was determined in rabbit medial menisci. Standardized longitudinal lesions localized in the microvascular zone II near the posterior horn were left untreated, fixed by suture, or sealed with fibrin glue. In two consecutive trials healing was determined after 6 weeks and after 12 weeks. After 6 weeks the mean scar strength was 19% (no therapy), 26% (suture), and 42.5% (fibrin glue) of the value measured in the equivalent region of the intact contralateral controls. In the peri-scar tissue in the line of the scar a section of secondary tissue weakness was discovered, which was shorter after treatment with fibrin glue. Although the scar strength was the same at Week 12, the area of tissue weakness was reduced. These biomechanical data point to the necessity of long-term studies to evaluate ultimate scar strength. They may explain the development of a bucket handle tear by extension of an initial lesion across an adjoining zone of secondary tissue weakness. The good results obtained with fibrin glue should encourage clinicians to use this therapy in clinical studies on meniscus repair in the inner zones of low healing capacity.

Meniscal healing: a histological study in rabbits

Repair of meniscal tears occurs best in the region of the capsular attachment. The further the tear from the site of capsular attachment, the less the vascularity, and healing becomes dubious. For an evaluation of healing in the poorly vascularised zone of the meniscus a histological study was performed in rabbits with standard longitudinal incisions in the posterior horn of the left medial menisci. In addition a biomechanical investigation of scar strength was performed. Three groups of animals were studied: group 1 were allowed to heal spontaneously, group 2 were sutured and group 3 were treated with fibrin glue. After 6 weeks, macroscopically, 4 out of the 10 menisci in groups 1 and 3 exhibited incomplete scar formation, whereas all menisci in group 2 looked well. This result fell short of statistical significance because 2 menisci in group 2 had to be excluded due to faulty localisation of the standard injury. In all groups the scars contained fundamental elements of healing, such as fibroblasts, blood vessels and fibrous material. Repair seemed to be significantly influenced by the proliferating synovial membrane. Histologically there was no difference between group 1 and 3. In both groups the lesions were filled with a broad strip of reparative tissue mostly consisting of plexiform collagenous fibres. Although the appearance of the menisci in group 2 was similar, the scar tissue was distinctly thinner due to the close adaptation of the wound margins, and the vascularity seemed better. In all specimens the tissue located towards the free rim of the meniscus showed signs of degeneration.(ABSTRACT TRUNCATED AT 250 WORDS)

Arthroscopic repair of traumatic longitudinal meniscal tears. A 3 to 5-year follow-up

The healing potential of the meniscal tissue has been known for a century but has only been broadly introduced into surgical treatment during the last years. Open surgical suture of the meniscus has increasingly been replaced by arthroscopic refixation. We report 34 meniscal refixations with a minimal follow-up of at least 3 years and a mean of 4 years. Using our own simple and economic surgical technique, 34 refixations were performed in 32 patients from January 1987 to December 1988. All patients had traumatic meniscal tears close to the capsule. Frequently the injury was associated with a fresh or old rupture of the anterior cruciate ligament. Without additional trauma, one meniscus had to be partially resected after 4 months; a second one was partially resected in an unstable knee. Both the clinical examination and the satisfaction of the patient demonstrate that meniscal refixation is feasible and appropriate with a correct indication.

Reversal of gelatin-impaired wound healing in rats by exogenous fibronectin

Animal experiments have shown that administration of gelatin results in a deprivation of plasma fibronectin (FN) and impaired wound healing. For further elucidation of these findings a therapy study with purified human FN was performed in rats. Fifty animals received a standard burn injury of 1% body surface and were divided into five experimental groups. Positive controls given no further treatment or treated with solvent only served for estimation of normal healing. For a negative control, 10 animals received three intraperitoneal injections of gelatin (58 mg/kg body wt) on Days 0, 1, and 2 after injury. They exhibited a striking lack of plasma FN (Day 1) and a significant delay of wound contraction (Days 7 and 14). In the therapy groups each administration of gelatin was followed by an intraperitoneal or intracardiac injection of FN (58 mg/kg body wt) 1 hr later. In these animals the negative effect of gelatin upon plasma FN and wound contraction was prevented. According to this study wound healing is menaced by FN deficiency and can be optimized by substitution of exogenous FN.

[Measurement of the biomechanical stability of the healing menisci in animals: fibrin gluing, an alternative to traditional therapy methods?]

Six weeks after spontaneous healing or suturing of standardized longitudinal lesions in zone II of the posterior horn of the rabbit medial meniscus there was no difference of any kind evident. After fibrin sealing, however, a significant higher stability of scar tissue was measured. Compared to intact menisci in all cases scar stability was diminished, hence in the elongation of the scar the tissue was also weakened. This region of weakness was significantly reduced in menisci that had been sealed. Due to these results it is of utmost necessity that the meniscus suture in zone II should be thoroughly reexamined; the application of fibrin sealant should be seriously considered.

[Effect of different fibrin sealants on fibroblast activity in skin wounds. Experimental studies in rats]

The effects of two different fibrin sealants on synthetic activity of fibroblasts in incisional skin wounds of rats were studied by tracer experiments with 14C-proline. Additionally the wounds and the subcutaneous rests of the fibrin sealants were examined histologically. When the sealants were applied immediately after wounding there was no difference to untreated controls. However, administration on day 3 after injury resulted in a significant increase of 14C-incorporation by both preparations. This stimulation of synthetic activity after retarded treatment must be caused by the direct contact between the sealants with their soluble components and the fibroblasts, which are more frequent in the wounds on day 3. Differences between the two preparations could only be observed in the histological examination of the subcutaneous fibrin clots. Preparation 2 induced stronger encapsulation, cell invasion, and fibrinolysis of the clots than preparation 1.

[The effect of subtherapeutic quantities of native gelatin and Haemaccel 35 (polygeline) on the fibronectin level and wound healing. An experimental animal study in rats with burn wounds]

Posttraumatically, opsonic plasma fibronectin is consumed by collagen-like degradation products that enter the vascular system. Additional administration of gelatin (= denatured collagen) results in an essential lack of fibronectin with subsequent retardation of wound healing even when subtherapeutic amounts are given. Therefore, in an experiment with rats we studied the question of whether similar effects are evoked by equal amounts of Haemaccel 35 (cross-linked polypeptides from degraded gelatin). The animals received standardized third degree burn injuries of about 1% of body surface. Immediately after wounding and on the following 2 days native gelatin or Haemaccel was applied intraperitoneally in 2 different dosages (61 mg/kg and 122 mg/kg). The burn injury by itself did not cause a significant decrease of plasma fibronectin. After injection of gelatin a dramatic deprivation of plasma fibronectin occurred and, in consequence, a delay of the healing process. After administration of equal amounts of Haemaccel 35, however, there was neither a depletion of plasma fibronectin nor any significant effect on wound healing.

[Biocompatibility and mechanical strength of various dura mater preparations after intraperitoneal implantation in rats]

Biocompatibility and mechanical strength of 3 different dura mater preparations were studied during 1, 2 and 4 weeks in a rat model. Two preparations produced by conventional methods did not markedly differ, whereas the third one, which had been freeze-dried after addition of glycerol, exhibited some special properties, showing higher mechanical strength throughout the whole period of implantation, and lower tendency to form adhesions, and inducing weaker leucocytic reaction. For certain surgical problems this soft, strong and compatible dura preparation could be an appropriate alternative.

[Action and biocompatibility of two collagen-based hemostatics in animal experiments]

Efficacy and biocompatibility of two collagen hemostatic wound dressings (usual agent: Collastypt, fluid-stabilised agent: Lyostypt) were compared. In a prospective randomized study the local hemostatic effect (bleeding time and blood loss) of the two agents were investigated after liver trauma of 45 rats. Liver wounds which remained untreated served as controls. Both preparations significantly reduced bleeding. The fluid-stabilised agent was significantly superior to the second collagen agent of different manufacturing.

Effect of fibronectin therapy and fibronectin deficiency on wound healing: a study in rats

Rats with standardized 3rd-degree burns of 1% body surface were treated intraperitoneally with different doses of human fibronectin or swine gelatin immediately after injury and on the following days. Controls received bovine albumin or no further treatment. Wound healing was assessed by planimetry (days 0, 2, and 7); additionally, plasma fibronectin was determined (days 3 and 7). On day 3 fibronectin levels were significantly elevated after albumin and the highest dosage of fibronectin (3 X 16 mg) and decreased after gelatin and the lowest dosage of fibronectin (3 X 4 mg). Wound healing was neither affected by albumin nor by human fibronectin, but it was significantly impaired by gelatin-induced lack of fibronectin. The data support the opinion that fibronectin is an essential factor for the post-traumatic clearance of gelatin-like tissue debris via the reticuloendothelial system (RES). Overload by gelatin results in fibronectin deficiency and RES dysfunction with risks of infection and poor wound healing.

The effect of fibronectin therapy and fibronectin deficiency on healing of rat burns and excision wounds

Rats with standardized burns and skin excision wounds were treated i.p. with human fibronectin or swine skin gelatin. Controls received bovine albumin, solvent, or no treatment. Wound healing was assessed by planimetry, additionally plasma fibronectin was determined. Solvent or albumin did not influence the healing process, neither did fibronectin. However, when opsonizing fibronectin was additionally consumed by application of gelatin, a significant retardation of wound healing was observed. The results support the opinion that fibronectin is of essential importance for posttraumatic opsonization of gelatin-like material originating from the damaged tissue.

Polarimetric assay for the determination of the native collagen content of soluble collagen

Two standardized assays for determining the amount of native collagen in a collagen solution are described which are based on polarimetric measurements. Native collagen content is calculated from the loss of optical rotation during transition from the original to the denatured conformation using constants which were obtained from standard collagen of highest available native collagen content. While Method I gives information on the content of helical collagen, Method II estimates collagen which is resistant to peptic degradation. Both methods are simple to perform and suitable for routine quality control.

[Age-related problems of wound healing]

A study on wound failures after surgical operations performed at the Dep. of Surgery, Köln-Merheim, revealed an overall rate of 10,8%. 40,3% of all complications were observed in patients aged more than 60 years, which gives a rate of 19,1% for those people. To date this significant increase of wound failures in older individuals is preferently explained by the reduced resistance of the old organism to infections. Our trials with rats as well as numerous publications of other authors on the topic of age-related changes of metabolism prove that the wound healing process is delayed in older individuals. This fact does not consequently lead to complications but the prolonged healing in connection with the repeated change of wound dressing gives an enhanced risk for infections. If special precautions are observed the age of a patient is not a principal contraindication to a great surgical operation today.

Amino acid-p-nitroanilide and -beta-naphthylamide cleaving activities in rat serum

Determination of proteolytic activities gains increasing importance for the diagnosis of various pathologic conditions. Many questions can only be solved with the aid of experiments with animals. In preparation of such studies the pattern of the enzymatic hydrolysis of 20 amino acid-p-nitroanilides and one -beta-naphthylamide by normal rat serum was measured. The pH dependences of the single reactions are reported as well as their sensitivity to the action of ethylenediaminetetraacetic acid, dithioerithrol, and puromycin. Additionally, it is shown that collecting of the blood by cardiac puncture and preparation of the native plasma is the best way to get reproducible results.

Purification and properties of a collagen peptidase (PZ-peptidase) from rabbit serum

A peptidase cleaving a synthetic substrate for collagen peptidases, 4-phenylazobenzyloxcarbonyl-L-Pro-L-Leu-Gly-L-pro-D-Arg (designated as PZ-peptide) has been purified 1200-fold from rabbit serum and characterized. The enzyme preparation is free of collagenase and unspecific proteinase activity. The natural substrates are denatured collagen and collagen peptides. The peptidase has a molecular weight of 124 000 and an isoelectric point at pH 5.1. The pH dependence curve exhibits two maxima, one at pH 7.1 and the other at pH 7.9. The enzymic reaction is completely inhibited by Zn2+ and to a slower degree by Hg2+, Mn2+ and p-hydroxymercuribenzoate. It is not affected by EDTA and KCN but totally blocked by o-phenanthroline. Phenylmethylsulfonylfluoride is completely inhibitory and points to a serine residue in the active site.

Relaxin and collagen metabolism

The influence of the peptide hormone relaxin on collagen metabolism was studied in the symphysis pubis of the mouse. In the tissue the content of water and of acid soluble collagen in relation to total collagen is increased by hormonal treatment. Total collagen calculated in relation to the dry weight is decreased. Collagenase which was also detected in the symphyses of the controls is slightly enhanced. In serum collagen peptidase and collagen peptidase inhibitor as well as cyclic AMP exhibit distinctly increased levels. The effects can be suppressed by administration of relaxin-specific antisera. The data make clear that in the symphysis relaxin activates the collagenolytic system.

N-Acetylaminoacyl-p-nitranilidase from human placenta. Purification and some properties

An enzyme hydrolyzing N-acetylaminoacyl-p-nitroanilides has been isolated from mature human placentae by a six-step procedure comprising extraction from a placenta homogenate, ammonium sulfate fractionation, treatment with isopentyl alcohol, chromatography on CM-Sephadex, protamine sulfate precipitation and gel filtration on an Ultrogel AcA 34 column. About 2500-fold enrichement was achieved from placenta homogenate. The purified enzyme preparation showed a single band on polyacrylamide disc electrophoresis. The molecular weight was estimated to be 380,000 by gel filtration. Placental extracts contain two main isoenzymes of pI 3.9 and 4.5 respectively. Activity was strongly inhibited by chloromercuribenzoate, slightly inhibited by Ca2+ and cysteine; no activation could be detected. The enzyme exhibits an exopeptidase-like activity towards acetyl-dipeptides with a certain specifity towards N-acetylalanyl-alanine; N-acetylalanine-p-nitroanilide, however, is hydrolyzed four times faster. With N-acetylalanine-p-nitroanilide as substrate the pH optimum was 8.0--8.2; Km was 2.13 mmol/l. N-Acetylleucine-p-nitroanilide and N-acetyltyrosine-p-nitroanilide were split slowly; N-acetylalanyl-alanyl-alanine-p-nitroanilide, N-butyloxycarbonyl-alanyl-alanine-p-nitroanilide, unsubstituted analogous aminoacyl-p-nitroanilides and several protein substrates were not hydrolyzed. The functions of the enzyme are still unknown.

[Inhibition of PZ-peptidases by serum (author's transl)]

The inhibition of two PZ-peptidases by several sera was studied with the aid of methods based on the PZ-peptidase assay of Wünsch and Heidrich Clostridiopeptidase A is inhibited by all sera, whilst the PZ-peptidase from the rabbit serum is inhibited only by heterologous sera. The inhibition is weak and cannot be compared with the strong serum inhibition shown by collagenases.