[Learning curve in laparoscopic rectum surgery]. / Lernkurve in der laparoskopischen Rektumchirurgie.

Laparoscopic colorectal surgery has become increasingly more common since first being described in a publication in 1990. Despite a multitude of studies about the learning curve in laparoscopic colon surgery, there are almost no such studies with regard to laparoscopic rectum surgery. This paper aims to describe a surgeon's learning curve with regard to laparoscopic rectum surgery. Based on data collected in a prospective observational study of 180  patients, it can be established that a surgeon experienced in open colorectal surgery, with basic experience in laparoscopic surgery, after suitable preparation and having a personal interest in minimally invasive surgery, needs to perform about 35  laparoscopic rectum resections within 200  laparoscopic colon resections until selection rate, operating time and rates of general and surgical complications reach a plateau. A selection of cases suited to a surgeon's personal level of operating experience, is a prerequisite for a low rate of conversions and complications and for oncological long-term results comparable to those achieved through open surgery. However, the learning curve is dependent on a multitude of factors that are partly unknown at this point. Its duration most certainly varies between individual surgeons. Every surgeon is required to critically evaluate his or her own laparoscopic experience and select cases accordingly. Supervision by surgeons more experienced in laparoscopic colorectal surgery prevents disadvantages for patients in the early phases of the surgeon's learning curve. Training in laparoscopic colorectal surgery should take place only in institutions with a sufficient number of cases treated and a continuity in experienced teachers. CAMIC's efforts in establishing centres of competence and reference are therefore to be commended and supported.

[Laparoscopic recovery continuity after the Hartmann procedure]. / Die laparoskopische Wiederanschlussoperation nach Hartmann-Resektion.

In the period from January 2003 to June 2009 923 complex laparoscopic colorectal procedures were performed by one surgeon. Data was as­sessed prospectively in a database including 152 variables. In 15 patients (10 f, 5 m), with a median age of 61 years (range: 35-83 years), discontinuity resection of the colon was performed including 3 patients with open discontinuity resection of the sigma and 12 patients with laparoscopic Hartmann procedures. In all cases continuity of the ­colon was recovered laparoscopically. Median op­er­ation time was 100 min, conversion to an open procedure was not necessary. No intra-operative complications occurred and only one wound infection (6.6 %) was recorded postoperatively with a median postoperative stay of 8 days. Although the laparoscopic approach to recover continuity of the colon is technically challenging, we con­clude that the experienced bowel surgeon is able to perform the laparoscopic approach with a low morbidity and mortality by retaining the well known advantages of laparoscopic colonic sur­gery.

[Intrathoracic thoracoscopic anastomosis in minimally invasive oesophageal resection - technical tips]. / Intrathorakale thorakoskopische Anastomose nach minimalinvasiver Osophagusresektion - ein operationstechnischer Hinweis.

INTRODUCTION: Minimally invasive oesophageal resections are being increasingly propagated. However, a leakage of the cervical anastomosis, occurring in up to 30 % of the cases, remains a severe disadvantage. By means of a case report, a new alternative technique of intrathoracic thoracoscopic anastomosis is described. PATIENT AND METHOD: After the customary laparoscopic abdominal performance of lymph-node dissection, a gastric conduit was performed in a 73-year-old patient with an adenocarcinoma of the gastro-oesophageal junction. After that the oesophagus had been resected thoracoscopically and an intrathoracic side-to-side/functional end-to-end anastomosis between the gastric conduit and oesophagus was performed with linear staplers. RESULTS: There were no postoperative complications. CONCLUSION: The intrathoracic thoracoscopic oesophagogastrostomy seems to be an oncologically adequate procedure that has less complications than the other laparoscopic-thoracoscopic techniques described so far. However, further studies are necessary to prove this conclusively.

[Sense or nonsense of a prophylactic drainage after laparoscopic colorectal surgery - a prospective study]. / Sinn oder Unsinn einer prophylaktischen Drainage nach laparoskopischer Kolonresektion - eine prospektive Untersuchung.

INTRODUCTION: A growing number of studies do not show an advantage of prophylactic drainage in intraabdominal surgery any more. Especially against the background of "fast-track" surgery, this study aimed at an analysis of the influence of drainage on the patient's outcome in elective laparoscopic colorectal surgery. METHOD: Within a 50-month period, 569 laparoscopic colorectal operations were carried out at the Klinikum Bremerhaven Reinkenheide, a centre for minimally invasive surgery. Of these, 505 patients were operated by one surgeon. For this prospective study, the data of 299 elective colon resections because of carcinoma or diverticulitis of the sigmoid colon in Hinchey stages 0-II, out of these 505 patients, have been analysed. RESULTS: Before May 2006, a drainage was always used (n = 163, group A). Since May 2006, no drainage was used in 103 patients (group B). In another 33 patients (group C), drainage was used in complicated cases. The operation time was significantly reduced in patients with no drainage (99 min in group B vs. 120 min in group A) and there was a significantly reduced postoperative stay (6 days in group B vs. 11 days in group A). Furthermore, patients without drainage suffered less surgical and general complications than patients with drainage (6 vs. 10 % surgical complications; 1 vs. 6 % general complications). Infections of the wound occurred in 8.6 vs. 4.9 % of the cases when a drainage was used. CONCLUSION: According to our experience, prophylactic drainage does not seem to be necessary in elective colon surgery. Overall, drainage was accompanied by a higher rate of surgical and general complications. Therefore it does not fit into the concept of "fast-track" surgery.

[Influenceable surgical and anesthesiological risk factors for the development of cardiac and pulmonary complications in laparoscopic surgery of the colon]. / Beeinflussbare chirurgische und anästhesiologische risikofaktoren für die entwicklung kardialer und pulmonaler komplikationen nach laparoskopischer kolonchirurgie.

INTRODUCTION: Due to the demographic shift in the age structure of the population, increasingly older, multimorbid patients are operated who have a substantially higher risk for the occurrence of intra- and postoperative complications. Apart from the identification of patient-referred, hardly influenceable risk factors, influenceable intraoperative surgical and anesthesiological risk factors have hardly ever been examined. The aim of this investigation was therefore to identify influenceable risk factors for the development of post-operative morbidity. METHODS: In a period of 44 months, we performed a laparoscopic colon resection in 157 men and 209 women with a mean age of 63 years. The ASA classification, POSSUM score, status of the anesthesiologist, change of the anesthesiologist, intraoperative monitoring, kind of anaesthesia, fluctuations of blood pressure and pulse during the operation, shock-index > 1, substitution of erythrocyte concentrates and FFPs as well as intraoperative surgical complications were documented prospectively. Postoperative general complications requiring therapy, in particular, cardiac and pulmonal problems as well as surgical complications, in particular, infections and hemorrhages, were documented. The data analysis was performed using the program package SPSS. RESULTS: Intraoperative monitoring was more frequently used in higher ASA stages, whereas for ASA stage IV no central venous line was used in 17 % and no arterial catheter was placed in 33 %. a similar tendency concerning the POSSUM score could not be determined. Patients cared for by junior surgeons exhibited cardiac complications in 6.7 % and 13.1 % had to be mechanically ventilated postoperatively versus 2 % of cardiac complications and 9 % mechanical ventilation among those managed by specialists. An increase in postoperative complications could also be found when a change in anesthesia took place. During treatment by an assistant in case of emergencies, in cases where intraoperative substitution of erythrocytes or an operation lasting more than two hours, more cardiac complications and a higher rate of mechanical respiration was observed than during treatment by a specialist. A mechanical respiration was significantly more necessary in higher ASA stages (p < 0.01), in an operation lasting more than 2 hours (p < 0.01), in cases with the occurrence of intraoperative bleeding complications (p < 0.01), procedures with a lower status of the anesthesiologist (p < 0.01) and in procedures with a change of the anesthesiologist (p < 0.05). CONCLUSION: Factors such as overweight, ASA classification or urgency cannot be changed. Surgical factors such as a standardisation of the operation technique with reduction of the operating time and careful staunching of bleeding can help to reduce postoperative complications. Anesthesiologists can also help by avoiding a change of the anesthesiologist as well as by preference of specialists in patients with higher ASA stages and in emergency cases.

Minimally invasive transhiatal and transthoracic esophagectomy.

BACKGROUND: Standard esophagectomy requires either a laparotomy with transhiatal removal of the esophagus or a combination of laparotomy and thoracotomy. Currently, it still is associated with a high rate of morbidity and mortality. Complications leading to greater morbidity and mortality are rarely seen after minimally invasive surgery. The authors present their experience with 25 minimally invasive esophageal resections. METHODS: Between August 1st, 2003 and November 30th, 2005, the authors performed 25 minimally invasive esophageal resections for 4 woman and 21 men. Data were acquired prospectively. RESULTS: In this series, a laparoscopic transhiatal approach was performed in 9 cases, a combined laparoscopic-thoracoscopic procedure in 12 cases, and laparoscopic creation of a gastric tube combined with thoracotomy in 4 cases. No conversion became necessary. The mean operation time was 165 min (range, 150-180 min) for the laparoscopic transhiatal approach and 300 min (range, 240-360 min) for both combination approaches. Using the combined laparoscopic-thoracoscopic procedure, 23 lymph nodes (range, 19-26 lymph nodes) were removed, and using the laparoscopic transhiatal approach, 14 lymph nodes (range, 12-17 lymph nodes) were removed. The median stay in the intensive care unit was 1.5 days (range, 1-22 days), and the overall postoperative stay was 10 days (range, 7-153 days). Two intraoperative complications and two cervical anastomotic leakages were observed. The 30-day mortality rate was 0%. CONCLUSION: The findings demonstrate that laparoscopic transhiatal and combined laparoscopic/thoracoscopic esophagectomy are feasible and can be performed with low rates of morbidity and mortality. Due to an equal extent of lymph node dissection, there should be no difference in long-term survival between minimally invasive surgery and open surgery.

[Laparoscopic resection with primary anastomosis in Hinchey stages I and II without previous abscess drainage]. / Laparoskopische Resektion mit primärer Anastomose im Hinchey-Stadium I und II ohne vorherige Abszessdrainage. Eine prospektive Untersuchung.

INTRODUCTION: Intra-abdominal abscesses in diverticulitis so far have been drained percutaneously until the acute inflammation subsides and colon resection can be carried out for restoration of continence. However this method is successful in only about half of patients and lavage lasts for 2 to 3 weeks. Therefore it has to be decided whether an early operation without prior interventional drainage can attain results similar to those of the elective operation. METHODS: We performed primary laparoscopic surgery without prior interventional drainage or colon lavage in 72 patients in Hinchey stages I and II within 12 h of hospital admission. The peri- and postoperative processes were analyzed prospectively using 115 parameters. RESULTS: There was no difference in the postoperative course of patients receiving elective surgery for recurrent diverticular disease and those undergoing surgery for acute diverticulitis (Hinchey stages I and II). The rates of surgical and general complications were identical (7.7% vs 9.6% and 9% vs 3.6%, respectively). Wound infections were noted in 7.7% and 7.2%, respectively. No case of anastomotic leakage was observed. CONSEQUENCE: Based on our prospective data (grade of evidence II), we consider laparoscopic sigmoid resection with primary anastomosis (in continuity) in Hinchey stages I and II without prior interventional drainage and colon preparation to be justified.

Implementation and evaluation of a new workflow for registration and segmentation of pulmonary MRI data for regional lung perfusion assessment.

Recently it has been shown that regional lung perfusion can be assessed using time-resolved contrast-enhanced magnetic resonance (MR) imaging. Quantification of the perfusion images has been attempted, based on definition of small regions of interest (ROIs). Use of complete lung segmentations instead of ROIs could possibly increase quantification accuracy. Due to the low signal-to-noise ratio, automatic segmentation algorithms cannot be applied. On the other hand, manual segmentation of the lung tissue is very time consuming and can become inaccurate, as the borders of the lung to adjacent tissues are not always clearly visible. We propose a new workflow for semi-automatic segmentation of the lung from additionally acquired morphological HASTE MR images. First the lung is delineated semi-automatically in the HASTE image. Next the HASTE image is automatically registered with the perfusion images. Finally, the transformation resulting from the registration is used to align the lung segmentation from the morphological dataset with the perfusion images. We evaluated rigid, affine and locally elastic transformations, suitable optimizers and different implementations of mutual information (MI) metrics to determine the best possible registration algorithm. We located the shortcomings of the registration procedure and under which conditions automatic registration will succeed or fail. Segmentation results were evaluated using overlap and distance measures. Integration of the new workflow reduces the time needed for post-processing of the data, simplifies the perfusion quantification and reduces interobserver variability in the segmentation process. In addition, the matched morphological data set can be used to identify morphologic changes as the source for the perfusion abnormalities.

[Laparoscopic blunt esophageal dissection with abdominal and mediastinal lymph node dissection in Barrett carcinoma]. / Laparoskopische stumpfe Osophagusdissektion mit abdomineller und mediastinaler Lymphknotendissektion beim Barrett-Karzinom.

Esophageal resection has still a high morbidity and mortality. Minimal-invasive procedures don't have such complications. We describe a case of a patient with a Barrett-Carcinoma who was operated on by laparoscopic blunt esophageal dissection with abdominal and mediastinal lymph node dissection (tumor stage: pT3pN1 (2/16) G2). The postoperative course was without any complications.

Permissive and suppressive effects of dexamethasone on enzyme induction in hepatocyte co-cultures.

1. Steroids are known to act as permissive factors in hepatocytes. This study shows that dexamethasone (DEX) is a permissive factor for induction of CYP2B1/2, CYP3A1, CYP2A1 and probably also CYP2C11 in cultures with primary rat hepatocytes. 2. The induction factor of phenobarbital (PB)-induced formation of 16beta-hydroxytestosterone (OHT), a testosterone biotransformation product predominantly formed by CYP2B1, is increased 18-fold by the addition of 32 nM DEX to the culture medium. Interestingly, higher concentrations of DEX up to 1000 nM led to a concentration-dependent maximally 5-fold decrease (p = 0.002) of phenobarbital-induced 16beta-OHT formation compared with the effect observed with 32 nM DEX. Thus, DEX shows permissive and suppressive effects on enzyme induction depending on the concentration of the glucocorticoid. 3. Qualitatively similar but smaller permissive and suppressive effects of DEX were observed for PB-induced CYP3A1 activity as evidenced by formation of 2beta-, 6beta- and 15beta-OHT. 4. DEX is a permissive factor for induction of CYP2A1 activity by 3-methylcholanthrene (3MC), as evidenced by the formation of 7alpha-OHT. Without addition of DEX, 3MC did not induce formation of 7alpha-OHT, whereas an almost 3-fold induction occurred in the presence of DEX. In contrast to CYP2B and CYP3A, concentrations up to 1000 nM DEX were not suppressive for the induction of CYP2A1. 5. We described recently a technique that allows preparation of cultures from cryopreserved hepatocytes. An almost identical influence of dexamethasone on enzyme induction was observed here in cultures from cryopreserved compared with freshly isolated hepatocytes. 6. Cultures with primary hepatocyte cultures represent a well-established technique for the study of drug-drug interactions. However, a large interlaboratory variation is known. Our study provides evidence that differences in glucocorticoid concentration in the culture medium contribute to this variation.

[Hereditary pancreatitis - a clinically relevant cause of pancreatic adenocarcinoma?]. / Hereditäre Pankreatitis - Eine klinisch relevante Ursache des Pankreaskarzinoms? -

UNLABELLED: Hereditary pancreatitis is an autosomal dominant disease. Recently, the genetic defect has been mapped to chromosome 7q35 and consists mainly of a point mutation in exon 3 of the cationic trypsinogen gene which causes an Arg(CGC)-His(CAC) substitution at residue 117. In patients with hereditary pancreatitis the estimated cumulative risk for pancreatic carcinoma to age 70 approaches 40 %. Thus, the role of hereditary pancreatitis in the pathogenesis of pancreatic carcinoma is of interest. PATIENTS AND METHODS: DNA was extracted from peripheral blood (n = 16), fresh tumor tissue (n = 29) and formalin fixed and paraffin embedded tumor tissue (n = 5) of 50 patients with ductal adenocarcinoma of the pancreas. We specifically amplified exon 3 and the intronic flanking sequences of the cationic trypsinogen gene by nested PCR and performed restriction fragment length polymorphism analysis using the restriction enzyme Afl III. In patients with hereditary pancreatitis the G : A point mutation creates a recognition site for Afl III which is not present in unaffected individuals. RESULTS: None of the 50 patients with ductal adenocarcinoma of the pancreas revealed the G : A point mutation in exon 3 of the cationic trypsinogen gene which is characteristic of hereditary pancreatitis. In addition sequencing of exon 3 did not reveal any other mutations in the DNA of patients with pancreatic adenocarcinoma. CONCLUSION: Although hereditary pancreatitis markedly increases the risk for pancreatic cancer, it is rare and probably of little significance with respect to the pathogenesis of the majority of pancreatic adenocarcinomas.

[Surgical therapy of carcinoid tumors of the gastrointestinal tract]. / Chirurgische Therapie bei Karzinoiden des Gastrointestinaltraktes.

More than 70% of all carcinoids are localized in the gastrointestinal tract. Carcinoids of the upper, middle and lower intestines have to be distinguished ontogenetically. The classification according to Capella takes into account the size of the tumor (< 0.9 cm; 1-2 cm; > 2 cm), the grade of invasion of other structures, the grade of angioinvasion, the biologic behaviour, the grade of differentiation and the hormonal activity of the tumor. A carcinoid-syndrome is rarely found. Carcinoids of the small intestine occur multiple in 30-50% and in 20-30% a second malignant tumor is seen. In carcinoids of the colon this percentage is even higher (25-40%). The therapy of carcinoids depends on the size of the tumor and consecutively on the risk of metastasis. A local excision or non-oncologic radical operative procedure is justified in carcinoids smaller than 1 cm. In tumors 1-2 cm in size an individual decision has to be made. Larger tumors should be operated according to oncologic standards. Palliative resections, even of the liver, may be indicated to relieve the symptoms of a carcinoid-syndrome or, to prevent ileus or bleeding in the gastrointestinal tract. The prognosis of gastrointestinal carcinoids is heterogenous: The five-year-survival-rate of appendix-carcinoids is 85.9% over all stages. In rectal carcinoids this rate amounts to 72.2%, in carcinoids of the small intestines to 55.4% and in colon-carcinoids to 41.6%. Carcinoids of the stomach have a five-year-survival-rate of 64.3% in the absence of metastases. Within carcinoids of the stomach type III-tumors have the worst prognosis with a median survival time of 6.5 months.

[Surgical treatment and outcome in insulinoma]. / Operative Therapie und Ergebnisse beim Insulinom.

In the therapy of organic hyperinsulinism, interest is mainly focussed on the surgical removal of the hyperactive tissue. In spite of these progresses, the surgical treatment is not devoid of problems. These comprise the primary untraceable insulinoma, multiple insulinomas, nesidioblastosis and reoperation. The development of laparoscopic surgery leads to new opportunities the rating of which must be defined. Solitary adenomas are causal for primary hyperinsulinism in 80% to 90% of cases. Intraoperative 87.5% of the tumors are palpable and 83% are detectable by ultrasound. By combination of both methods it is possible to remove 97% of the solitary tumors. Occult adenomas, which cannot be represented by preoperative imaging diagnostics are detectable through intraoperative methods in over 80% of cases by palpation or ultrasound respectively. By combination of both methods, 97% of these occult adenomas can be removed. This reliability of the intraoperative detection makes the preoperative localizing diagnostics unnecessary if no MEN-syndrome is present. If a MEN-syndrome is present, multiple adenomas are common. In 60% of cases multiple adenomas are responsible for the persistency of the syndrome after an unsuccessful primary operation. Therefore a preoperative localizing diagnostics is advisable in case of a MEN-syndrome. Multiple adenomas are treated by left-pancreatic resection with enucleation of remaining adenomas in the pancreatic head region. In case of an untraceable adenoma, the possibility of the rare nesidioblastosis should be considered. This rare occurrence can be detected by fresh frozen sectioning. The resection of 75% to 80% of the pancreas is recommended. The attempt of a laparoscopic removal of solitary adenomas may be indicated, taking into account all contraindications. The preliminary requisite for this is an experienced center in endocrine surgery as well as an experienced laparoscopic surgeon. Contraindications for the laparoscopic procedure are: a tumor localized in the head of the pancreas or in the dorsal parts of the organ, multiple adenomas and nesidioblastosis. In case of occult adenomas, laparoscopic therapy is problematic, as they are also difficult to detect intraoperatively through laparoscopy. The incidence of postoperative complications is still high with 30% and a mortality of 2%. Most often pancreatic fistulas (10%) and septic complications were seen.

The impact of clinical types of disease manifestation on the risk of early postoperative recurrence in Crohn's disease.

BACKGROUND/AIMS: Surgery for Crohn's disease is frequently followed by symptomatic recurrence, which in up to 40% requires reoperation within 6 years. Whilst there is evidence that postoperative medical prophylaxis can be efficient, the results of clinical trials are inconsistent regarding the achieved benefit for the patient. Several parameters have been claimed to indicate an increased intrinsic risk of early surgical recurrence. METHODOLOGY: Patient charts of 287 patients who had undergone abdominal surgery for Crohn's disease were reviewed. Mean follow-up was 4.4 years. Recurrence-free intervals were calculated by the Kaplan-Meier method. A uni- and multivariate analysis was conducted to assess the impact of possible indicators of the need of repeated surgery. RESULTS: Patients with fistulizing type of symptoms, extraintestinal manifestations, corticosteroid treatment or male gender experienced significantly earlier reoperation. Recurrent disease, histologic evidence of inflamed resection margins, patient's age at the time of primary diagnosis and operation and the presence of epitheloid granulomas did not show significant influence on recurrence-free intervals. CONCLUSIONS: We conclude that the natural course of disease after intestinal resection in patients with one or more of these risk factors tends towards earlier recurrence requiring surgical intervention. The risk factors identified in this trial may be useful for patient stratification for randomized trials on the efficacy of medical prophylaxis.

Changes in the extracellular matrix of the vein wall--the cause of primary varicosis?

BACKGROUND: Conflicting theories on the development of primary varicosis have led to the molecular biological investigation of the vein wall or, more accurately, of the extracellular matrix. It was the aim of this study to quantify matrix expression and to compare pathological changes in the vein wall with valve-orientated staging of varicosis, in order to determine indicators of the primary cause of varicosis. MATERIALS AND METHODS: Three hundred seventy-two tissue specimens of greater saphenous veins were obtained from 17 patients with varicosities and categorised according to Hach stage and procurement site. The specimens were compared with 36 specimens collected from six patients without varicosities, incubated with fluorescence-stained antibodies for collagen 4, laminin, fibronectin and tenascin prior to being assessed with confocal laser scan microscopy. In addition, 22 vein specimens (16 varicose, 6 normal veins) serving as negative controls were investigated. RESULTS: Image analysis and statistical evaluation showed that compared with normal veins, varicose veins are associated with a significant increase in matrix protein expression for collagen 4, laminin and tenascin. A trend towards an increase in matrix expression was further observed for fibronectin. There was, however, no difference between varicose veins and clinically healthy vein segments inferior to a varicose segment. CONCLUSION: If the findings of the present investigation can be confirmed by other studies, alterations in the vein wall may be regarded as the primary cause of varicosis and valvular insufficiency as the result of these changes.

Cryotherapy for liver metastases.

Cryotherapy is undergoing a renaissance in the treatment of nonresectable liver tumors. In a prospective case control study we assessed the morbidity, mortality, and efficacy of hepatic cryotherapy for liver metastases. Between January 1996 and September 1999 a total of 54 cryosurgical procedures were performed on 49 patients (median age 66 years, 21 women) with liver metastases. Patient, tumor, and operative details were recorded prospectively. Liver metastases originated from colorectal cancer (n=37), gastric cancer (n=3), renal cell carcinoma (n=2), and other primaries (n=7). Median follow-up was 13 months (1-32). The median number of liver metastases was 3 (range 1-10) with a median diameter of 3.9 cm (range 1.5-11). Twenty-one patients (43%) had cryoablation only, and 28 (57%) had liver resection in combination with cryoablation. One patient (2%) died within 30 postoperative days. Another 13 patients (27%) developed reversible complications. In 19 of 25 patients (76%) with preoperatively elevated serum CEA and colorectal metastases it returned to the normal range postoperatively. Twenty-eight patients (57%) developed tumor recurrence, eight of which with involvement of the cryosite. Overall median survival patients was 23 months, and survival in patients with colorectal metastases was 29 months. Hepatic cryotherapy is associated with tolerable morbidity and mortality. Efficacy is demonstrated by tumor marker results. Survival data are promising; however, long-term results must be provided to allow comparison with other treatment modalities.

[Primary varicose veins--changes in the venous wall and elastic behavior]. / Primäre Varicosis--Veränderungen in der Venenwand und im elastischen Verhalten.

The aetiology of varicosis is still unclear. Investigation of changes in normal veins which result in the formation of varicosis led to examination of elastic properties and histomorphological alterations in the region of the extracellular matrix in the vessel wall of the long saphenous vein in normal and varicose veins. The rigidity of varicose veins was higher than that of normal veins; there was no difference between the varicose vein above a competent valve and the "normal" vein below this competent valve. The matrix proteins demonstrated an increase in total fibres, whereas the elastic fibres were reduced and fragmented, explained the rigidity of varices. These results suggest that the role of the venous valves in the development of varicose veins is secondary to changes of the vein wall.

Cultures with cryopreserved hepatocytes: applicability for studies of enzyme induction.

The use of hepatocyte cultures is well established for the study of drug-drug interactions. However, the major hindrance for the use of human hepatocyte cultures is that human hepatocytes are only occasionally available. This problem could be overcome by cryopreservation. Although cryopreserved hepatocytes have been recommended for short term applications in suspension, studies on induction of enzyme activity, requiring a more prolonged maintenance of cryopreserved hepatocytes in culture, represent a new field of research. In the present study, we established a technique that allows preparation of rat hepatocyte co-cultures, using cryopreserved hepatocytes. After incubation with phenobarbital (0.75 mM; 72 h) induction factors for the isoenzyme-dependent regio and stereoselective testosterone hydroxylations were 1.6, 2.2, 1.0, 2.1, 5.6, 2.4, 3.6, 4.5 and 0.9 for 2alpha-, 2beta-, 6alpha-, 6beta-, 7alpha-, 15beta-, 16alpha- and 16beta-hydroxytestosterone and 4-androsten-3,17 dione. Regarding induction factors of less than 2-fold, as questionable these induction factors were similar to those of cultures with freshly isolated hepatocytes and the induction pattern of the individual hydroxylation products was similar to the in vivo situation. In addition 3-methylcholanthrene (5 microM; 72 h) induced exclusively the formation of 7alpha-hydroxytestosterone (6.6-fold) in cultures with cryopreserved hepatocytes. This specificity also correlates to that obtained in rats. Although these induction factors were clearly satisfactory in cryopreserved cultures, the absolute activities of the main testosterone hydroxylation products were reduced when compared to fresh cultures. For instance, 6beta-hydroxytestosterone, the main metabolite in solvent controls was reduced to 79%, 7alpha-hydroxytestosterone, the main metabolite after induction with 3-MC, was reduced to 66% and 16beta-hydroxytestosterone, the main metabolite after induction with PB, was reduced to 52%. Similarly, EROD activity after induction with 3-methylcholanthrene in cryopreserved cultures was reduced to 62%, compared with that in fresh cultures. Although further optimization and validation is required, the data show that cytochrome P450 activities can clearly be induced in co-cultures of cryopreserved hepatocytes, in a fashion which for the investigated inducers, is similar to that in cultures from freshly isolated hepatocytes and similar to the in vivo situation.

Cryopreserved primary hepatocytes as a constantly available in vitro model for the evaluation of human and animal drug metabolism and enzyme induction.

The use of primary hepatocytes is now well established for both studies of drug metabolism and enzyme induction. Cryopreservation of primary hepatocytes decreases the need for fresh liver tissue. This is especially important for research with human hepatocytes because availability of human liver tissue is limited. In this review, we summarize our research on optimization and validation of cryopreservation techniques. The critical elements for successful cryopreservation of hepatocytes are (1) the freezing protocol, (2) the concentration of the cryoprotectant [10% dimethyl-sulfoxide (DMSO)], (3) slow addition and removal of DMSO, (4) carbogen equilibration during isolation of hepatocytes and before cryopreservation, and (5) removal of unvital hepatocytes by Percoll centrifugation after thawing. Hepatocytes of human, monkey, dog, rat, and mouse isolated and cryopreserved by our standard procedure have a viability > or = 80%. Metabolic capacity of cryopreserved hepatocytes determined by testosterone hydroxylation, 7-ethoxyresorufin-O-de-ethylase (EROD), 7-ethoxycoumarin-O-deethylase (ECOD), glutathione S-transferase, UDP-glucuronosyl transferase, sulfotransferase, and epoxide hydrolase activities is > or = 60% of freshly isolated cells. Cryopreserved hepatocytes in suspension were successfully applied in short-term metabolism studies and as a metabolizing system in mutagenicity investigations. For instance, the complex pattern of benzo[a]pyrene metabolites including phase II metabolites formed by freshly isolated and cryopreserved hepatocytes was almost identical. For the study of enzyme induction, a longer time period and therefore cryopreserved hepatocyte cultures are required. We present a technique with cryopreserved hepatocytes that allows the induction of testosterone metabolism with similar induction factors as for fresh cultures. However, enzyme activities of induced hepatocytes and solvent controls were smaller in the cryopreserved cells. In conclusion, cryopreserved hepatocytes held in suspension can be recommended for short-term metabolism or toxicity studies. Systems with cryopreserved hepatocyte cultures that could be applied for studies of enzyme induction are already in a state allowing practical application, but may be further optimized.

Prognostic factors following liver resection for hepatic metastases from colorectal cancer.

BACKGROUND/AIMS: We aimed to identify prognostic factors that may allow better patient selection for liver resection for colorectal liver metastases. METHODOLOGY: A retrospective analysis of the files of 120 patients undergoing liver resection for colorectal metastases between 9/85 and 12/96 was performed. Survival and disease-free survival were calculated, and a uni- and multivariate analysis for the prognostic impact of various perioperative factors on survival was performed. RESULTS: Perioperative morbidity and mortality were 28.3% and 5.8% respectively. Median overall survival was 30 months with a 5-year survival rate of 31%. Radicality was the prime prognostic determinant. In patients with R0-resection, a liver metastasis of > 3.5 cm in diameter was the only independent factor associated with an adverse prognosis. CONCLUSIONS: Liver resection for colorectal liver metastases should be attempted if complete resection with clear margins is feasible and may be especially beneficial in patients with small (< or = 3.5 cm) lesions.