[Is the discipline associated with self-confidence in handling rational antibiotic prescription? : Results from the MR2 study in German hospitals]. / Ist die Fachrichtung assoziiert mit der Selbstsicherheit im Umgang mit rationaler Antibiotikaverordnung? : Ergebnisse der MR2-Studien an deutschen Kliniken.

BACKGROUND: Besides public awareness and specialist knowledge and training of physicians, their self-confidence plays a key role for clinical decision-making in the respective area. OBJECTIVE: This exploratory study investigated the influence of the discipline on differences in self-confidence in dealing with antibiotics and in the self-rated knowledge. METHODS: In 2015 the multi-institutional reconnaissance of practice with multiresistant bacteria (MR2) questionnaire containing items on antibiotic prescription and multiresistant pathogens was sent out to 1061 physicians working in departments for internal medicine, general surgery, gynecology and obstetrics and urology. In 2017 a similar MR2 survey was sent to 1268 specialist and assistant physicians in anesthesiology in Germany. Besides demographic data 4 items on self-confidence in the use of antibiotic treatment and 11 items concerning self-rated knowledge about rational antibiotic therapy and multiresistant pathogens were included in the present analysis. Logistic regression analysis, the χ2-test and the Kruskal-Wallis test were used for statistical analysis of the influence of the discipline on these items. RESULTS: The response rates were 43% (456 out of 1061) from the non-anesthetists and 56% (705 out of 1268) from the anesthetists. Of the non-anesthetists 44% and 57% of the anesthetists had had no advanced training on antibiotic stewardship during the year before the study. In the overall analysis anesthetists (mean±SD: 2.53±0.54) were significantly less self-confident about antibiotics than colleagues from other departments (internal medicine: 3.10±0.50, general surgery: 2.97±0.44, gynecology and obstetrics: 3.12±0.42 and urology: 3.15±0.44) in the unadjusted (all p<0.001) and adjusted comparison. The analysis of self-rated knowledge about rational antibiotic prescription showed similar results. Senior consultant status and advanced training in infectiology were significantly associated with self-confidence and self-rated knowledge about antibiotics. CONCLUSION: Anesthetists showed significantly less self-confidence in dealing with antibiotics than colleagues from other disciplines. Advanced training on a rational prescription of antibiotics was associated with a greater self-confidence, so that the implementation of compulsory courses on rational antibiotic stewardship in the respective residency curriculum needs to be considered.

A novel pretherapeutic gene expression-based risk score for treatment guidance in gastric cancer.

Background: Perioperative chemotherapy is an established treatment of advanced gastric cancer patients. Treatment selection is based on clinical staging (cT). We aimed to establish and validate a prognostic score including clinical and molecular factors, to optimize treatment decisions for these patients. Patients and methods: We analyzed 626 carcinomas of the stomach and of the gastro-esophageal junction from two academic centers including primarily resected and pre-/perioperatively treated patients. Patients were divided into a training (N = 269) and validation (N = 357) set. Expression of 11 target genes was measured by quantitative PCR in resected tumors. A risk score to predict overall survival (OS) was generated and validated. Intra-tumoral heterogeneity was assessed by analyzing 50 tumor areas from 10 patients. Results: A risk score including the expression of CCL5, CTNNB1, EXOSC3 and LZTR1 and the clinical parameters cT, tumor localization and histopathologic type suggested two groups with a significant difference in OS [hazard ratio (HR) 0.30; 95% confidence interval (CI) 0.17-0.52]. The risk score was successfully validated in an independent cohort (HR 0.32; 95% CI 0.21-0.51; P < 0.001) as well as in subgroups of primarily resected (HR 0.30; 95% CI 0.17-0.54; P < 0.001) and pre-/perioperatively treated patients (HR 0.37; 95% CI 0.17-0.81; P = 0.009). A significant difference in OS of high- and low-risk patients was also found in primarily resected patients with intestinal (HR 0.45; 95% CI 0.23-0.90; P = 0.020) and nonintestinal-type carcinomas (HR 0.1; 95% CI 0.02-0.42; P < 0.001). Intra-tumor heterogeneity analysis indicated a classification reliability of 95% for a supposed analysis of three biopsies. Conclusion: The identified risk score could substantially contribute to an improved management of gastric cancer patients in the context of perioperative chemotherapy.

Cisplatin and oxaliplatin surface contamination in intensive care units (ICUs) and hospital wards during attendance of HIPEC patients.

PURPOSE: The aim of this pilot study was to evaluate surface contamination by platinum drugs in the environment of patients in ICUs and wards treated by hyperthermic intraperitoneal chemotherapy (HIPEC). METHODS: The monitoring included 12 HIPEC treatments from four hospitals during the following 3 days after perfusion. A total of 33 urine and 33 drainage fluids from HIPEC patients and 160 wipe samples from several surfaces (urine/drainage bags, floors, gloves) were taken during the study period. RESULTS: In urine, the highest platinum concentrations were measured on the first day after perfusion. Median platinum concentrations were 1260 ng/ml for patients after cisplatin perfusion and 11,000 ng/ml for oxaliplatin treatment. Concentrations decreased until day three to 413 ng/ml cisplatin and 529 ng/ml oxaliplatin, respectively. In drainage liquids, platinum concentrations were generally lower. Platinum concentrations from surfaces of bags and floors ranged from 0.01 to 439 pg/cm(2) (median: urine bag 2.77 pg/cm(2), drainage bag 0.22 pg/cm(2), floor left 0.14 pg/cm(2), floor right 0.24 pg/cm(2)), with the highest contamination found on the outer surface of the urine bags. Samples from nurses' protective gloves ranged between 0.03 and 12 pg/cm(2) (median: 0.2 pg/cm(2)). CONCLUSIONS: High platinum-drug concentrations in urine and drainage liquids are the main source of contamination. Therefore, safe handling of these liquids is the best way to avoid cross-contamination on surfaces in wards and ICUs. Our results show that it is possible to take care of HIPEC patients without high contaminations during the first 3 days.

Echocardiography predictors of sustained sinus rhythm after cardioversion of supraventricular arrhythmia in patients with septic shock.

PURPOSE: The echocardiography parameters may predict the maintenance of sinus rhythm after cardioversion of a supraventricular arrhythmia (SVA). MATERIALS AND METHODS: Patients in septic shock with onset of an SVA, normal to moderately reduced LV systolic function (EF_LV˃̳35%) and on a continuous noradrenaline of <1.0 µg/kg.min were included. Echocardiography was performed at the arrhythmia onset, 1 h and 4 h post cardioversion on an infusion of propafenone or amiodarone. RESULTS: Cardioversion was achieved in 96% of the 209 patients within a median time of 6(1.8-15.6)h, 134(64.1%) patients experienced at least one SVA recurrence after cardioversion. At 4 h the left atrial emptying fraction (LA_EF, cut-off 38.4%, AUC 0.69,p˂0.001), and transmitral A wave velocity-time-integral (Avti, cut-off 6.8 cm, AUC 0.65,p = 0.001) showed as limited predictors of a single arrhythmia recurrence. The LA_EF 44(36,49)%, (p = 0.005) and the Avti 8.65(7.13,9.50)cm, (p < 0.001) were associated with sustained sinus rhythm and decreased proportionally to increasing numbers of arrhythmia recurrences (p < 0.001 and p = 0.007, respectively). The enlarged left atrial end-systolic diameter at the arrhythmia onset (p = 0.04) and elevated systolic pulmonary artery pressure at 4 h (p = 0.007) were weak predictors of multiple(˃3) recurrences. CONCLUSION: The LA_EF and Avti are related to arrhythmia recurrences post-cardioversion suggesting potential guidance to the choice between rhythm and rate control strategies. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03029169, registered on 24th of January 2017.

[Long-term therapy of idiopathic inflammatory bowel disease]. / Dlouhodobá udrzovací lécba idiopatických strevních zánetu.

Crohns disease and ulcerative colitis are chronic inflammatory diseases of the gastrointestinal tract. Both can be treated with medications that induce and maintain remission. The choice of medication is influenced by the balance between drug potency and potential side-effects, previous response to treatment, and the presence of extraintestinal manifestations or complications. After remission has been achieved, the goal of treatment is to maintain the symptom-free status. 5-aminosalicylic acid derivatives have efficacy for maintenance of remission in patients with distal disease. Thiopurines are recommended for the long-term therapy. For the patients who do not have a response to immunosuppressive therapy or cannot tolerate it, anti-TNF-α agents are gradually being adopted. Effective in the remission maintenance are thiopurines, infliximab and adalimumab.

[The importance of microbiological results for the treatment of complicated appendicitis-a monocentric case-control study]. / Die Bedeutung mikrobiologischer Ergebnisse für die Therapie der komplizierten Appendizitis ­ eine monozentrische Fall-Kontroll-Studie.

BACKGROUND: Patients with complicated appendicitis frequently develop postoperative septic complications. There are no uniform standards for the choice of perioperative antibiotic prophylaxis and the duration of postoperative antibiotic treatment. The purpose of this study was to investigate associations between microbiological samples and postoperative complications. METHODS: Patients with appendectomy and positive intraoperative swabs during 2013-2018 were included in this case-control study. Pathogen classes and their resistance patterns were evaluated in initial and follow-up swabs and compared in each of the groups with and without complications. RESULTS: A total of 870 patients underwent surgery during the period studied. Pathogen detection succeeded in 102 of 210 cases (48.6%) with suspected bacterial peritoneal contamination. Conversion from laparoscopic to open intra-abdominal perforation and the presence of an abscess were independent risk factors for wound infections in the multivariate analysis. The combination of different classes of pathogens resulted in significantly increased overall resistance to ampicillin/sulbactam in both the initial swabs (57%) and the follow-up swabs (73%). Resistant E. coli strains combined with certain anaerobes were also regularly detected in postoperative intra-abdominal abscesses. Piperacillin/tazobactam was effective against 83% of positive swabs in our resistance tests. CONCLUSION: Surgical treatment for complicated appendicitis remains the central therapeutic column. A regular review of the existing resistance patterns in perforated appendicitis can help to adjust and improve antibiotic treatment. Piperacillin/tazobactam should be used cautiously as a reserve antibiotic. A valid alternative is second or third generation cephalosporins in combination with metronidazole.

The impact of obesity on the outcome of severe SARS-CoV-2 ARDS in a high volume ECMO centre: ECMO and corticosteroids support the obesity paradox.

PURPOSE: The aim was to verify the impact of obesity on the long-term outcome of patients with severe SARS-CoV-2 ARDS. MATERIALS AND METHODS: The retrospective study included patients admitted to the high-volume ECMO centre between March 2020 and March 2022. The impact of body mass index (BMI), co-morbidities and therapeutic measures on the short and 90-day outcomes was analysed. RESULTS: 292 patients were included, of whom 119(40.8%) were treated with veno-venous ECMO cannulated mostly (73%) in a local hospital. 58.5% were obese (64.7% on ECMO), the ECMO was most frequent in BMI > 40(49%). The ICU mortality (36.8% for obese vs 33.9% for the non-obese, p = 0.58) was related to ECMO only for the non-obese (p = 0.04). The 90-day mortalities (48.5% obese vs 45.5% non-obese, p = 0.603) of the ECMO and non-ECMO patients were not significantly influenced by BMI (p = 0.47, p = 0.771, respectively). The obesity associated risk factors for adverse outcome were age <50 (RR 2.14) and history of chronic immunosuppressive therapy (RR 2.11, p = 0.009). The higher dosage of steroids (RR 0.57, p = 0.05) associated with a better outcome. CONCLUSIONS: The high incidence of obesity was not associated with worse short and long-term outcomes. ECMO in obese patients together with the use of steroids in the later stage of ARDS may improve survival.

[Diagnosis and surgical treatment of pancreatic cancer].

Despite sustained efforts, intensive research has not been proven successful to reveal risk factors, which relevantly influence early diagnostics or effective treatment of pancreatic carcinoma. Principally, it must be noted, that currently no ideal tumor marker exists for the (early) detection of pancreatic carcinoma. The most important imaging modalities are high-resolution computed tomography, abdominal ultrasound, and endosonography. Surgical procedures in therapy have become more and more standardised and lead to a decrease in morbidity and mortality on the one hand and to an increase in resectability on the other hand. Pylorus-preserving partial pancreaticoduodenectomy is the treatment of choice for a tumor of the pancreatic head, whereas resection of the left pancreas (including splenectomy) is the standard therapy for carcinomas of the pancreatic tail. In all cases, a local systematic lymphadenectomy is mandatory; hence the prognostic gain of an extended lymphadenectomy remains indeterminate. An infiltration of mesenteric and portal veins does not prevent respectability, as long as by venous resection an R0 status can be achieved. However arterial involvement in general excludes resection. Patients with marginally resectable or locally non-resectable tumors should be recruited into neoadjuvant radiochemotherapy trials since one third of these patients could be considered for potentially curative resection. However the majority of pancreatic cancer patients show locally unresectable or metastasized disease and therefore palliative treatment concepts are needed. Both, endoscopic or percutaneous stenting procedures and operative bypass surgery, are safe and reach high success rates.

Influence of the surgical technique on survival in the treatment of carcinomas of the true cardia (Siewert Type II) - Right thoracoabdominal vs. transhiatal-abdominal approach.

INTRODUCTION: It is still a matter of debate whether subtotal esophagectomy via a right thoracoabdominal approach (RTA) or extended gastrectomy using a transhiatal-abdominal approach (TH) is the favorable technique in the treatment of Siewert type II esophago-gastric junction adenocarcinoma (EJA). MATERIALS AND METHODS: Patients undergoing RTA or TH for EJA at our institution between 2000 and 2013 were extracted from a prospective database. Of 270 patients 91 (33.7%) underwent RTA and 179 (66.3%) were treated by TH. Differences in baseline characteristics, 30d mortality and complications were investigated using the χ2-test or exact testing. Survival analysis was performed using the Kaplan-Meier method and log rank testing. Median survival and hazard ratios were calculated and multivariable analysis of predictors was performed using a Cox model. Confounders were balanced using propensity score matching (PSM). RESULTS: No significant difference between the two procedures was detected regarding overall-survival (OS) and disease-free survival (DFS). 30d mortality rates were 1.1% in the RTA group and 4.5% in the TH group (p = 0.134). Morbidity was 34.1% in the RTA and 24.6% in the TH group (p = 0.006). Cox regression analysis identified age, ASA class and UICC stage as independent prognostic factors for OS. After PSM survival curves (OS + PFS) showed no significant difference. CONCLUSION: The present study could not detect a difference between RTA and TH from the oncologic point of view; RTA was not associated with higher 30d mortality. RTA for Siewert Type II EJA is justified whenever the oral tumor margin cannot be safely reached via a transhiatal approach.

Outcome of living donor renal transplantation in obese recipients.

The increasing prevalence of obesity among patients with end-stage renal disease accompanies more common renal transplantation from living donors. Since several studies have shown a negative impact of recipient obesity on renal transplantation outcomes, we investigated the influence of recipient-weight and donor-recipient-weight ratio on the outcome of living related renal transplantations. From October 2000 until December 2004, we performed 81 living donor renal transplantation with 30.8% (n = 25) of recipients with a body mass index >25 donor. In this group 6 patients lost their grafts (1-year survival rate, =76%). Among 56 recipients of normal body weight only 3 patients lost their graft (1-year graft survival rate, 94.6%; P < .001). Upon multivariate analysis body mass index was an independent risk factor for graft loss within the first year. When the body weights of the donor and recipient were analyzed in detail the quotient (body weight recipient(2)/ body weight donor) was also an independent risk factor. This study confirmed the results of larger analyses suggesting that body weight matching could significantly improve the outcomes in living donor renal transplantation. As a result of this study, in our institutional policy has changed; recipients of living donor grafts are only accepted when their body mass index is <25.

Noninvasive therapy of incidental de novo renal cell carcinoma in a kidney allograft 12 years after transplantation: report of a case and review of literature.

BACKGROUND: Immunosuppressive therapy increases the incidence of posttransplantation cancer. Primary renal cell carcinoma (RCC) represents 4.6% of all cancers in transplant recipients. The treatment options for RCC in a renal allograft include radical nephrectomy or nephron-sparing surgery. We report the case of a patient who underwent percutaneous radiofrequency ablation (RFA) of a RCC in the grafted kidney. PATIENT AND METHODS: Twelve years after undergoing heterotopic, allogenic kidney transplantation, a de novo lesion was diagnosed in the upper pole of the kidney graft in a 77-year-old patient during routine duplex ultrasonography. The magnetic resonance image showed a spherical lesion of 17 mm in diameter, which undoubtedly showed radiological signs of a RCC. After adequately informing the patient about alternative treatment strategies and the associated risks, we made an interdisciplinary decision for a percutaneous RFA of the lesion. RESULTS: After the intervention, graft function remained unchanged and is still good at 6 months with no signs of local recurrence on follow-up MRI. A small coagulation defect at the site of the former lesion was the only morphological change. There was also no evidence of distant tumor spread. CONCLUSION: Percutaneous RFA seems an acceptable, allograft-preserving treatment option associated with low morbidity and mortality for RCC in a renal allograft considering the significant risks associated with open partial nephrectomy in a kidney graft.

The effect of selective inhibition of inducible nitric oxide synthase on cytochrome P450 after liver transplantation in a rat model.

BACKGROUND: Activity levels of cytochrome P450 (CYP) provide markers for liver function and graft rejection episodes after orthotopic liver transplantation (OLT). Some in vitro studies have shown decreased CYP activation of inducible nitric oxide synthase (iNOS) in rejecting liver grafts. The aim of this study was to evaluate CYP isoenzyme activity changes in vivo and to examine histopathologic aspects during inhibition of iNOS after treatment with aminoguanidine (AG) using OLT in the rat. MATERIALS AND METHODS: Thirty DA-(RT1av1) rats that served as donors and LEWIS-(RT(1)) rats as recipients were divided into three groups: group I (controls, syngeneic rats; n = 6), group II (allogeneic rats without immunosupression; n = 11), and group III (allogeneic rats with AG treatment; n = 13). On postoperative days 5, 8, and 10 we performed laboratory investigations and liver biopsies for histopathologic investigations. RESULTS: On postoperative day 5, activities of CYP-1A1 and -3A4 were significantly lower (P = .022) in group III and the activity of CYP-1A2 higher (P < .05) compared with group II. At postoperative days 8 and 10, the activities of all CYP isoenzymes were significant higher in AG-treated rats (group III) in contrast with group II after allogeneic OLT without immunosuppression. Histopathologic findings revealed less distinct rejection signs in group III specimens after AG treatment compared with group II. CONCLUSION: Summarizing our results, we concluded that AG treatment led to increased CYP activity and less distinction of graft rejection after OLT in rats.

Labor analgesia in Czech Republic and Slovakia: a 2015 national survey.

BACKGROUND: The purpose of this international survey was to describe the current practices and techniques of labor analgesia in the Czech Republic (CZE) and Slovakia (SVK). METHODS: All Czech and Slovak departments that provide obstetric anesthesia were invited to participate in a one-month (November 2015) prospective study that monitored in detail all peripartum anesthetic procedures delivered by anesthesiologists. Participating centers recorded all data on-line in the CLADE-IS database (Masaryk University, CZE). RESULTS: The response rate was 71% (70 of 95 departments in CZE, 35 of 54 centers in SVK). Participating centers represented 87.7% of all births in CZE and 66.4% of all births in SVK during the study period. Analgesia for labor, administered by anesthesiologists, was recorded in 12.5% of deliveries (CZE 12.1%, SVK 13.4%). Epidural analgesia was used in most of the cases (CZE 97.2%, SVK 99.1%) whereas spinal (CZE 1.4%, SVK 0.9%) or combined spinal-epidural (CZE 0.5%, SVK 0.0%) and intravenous remifentanil analgesia (CZE 2.4%, SVK 0.0%) were used infrequently. One fifth of the labors with analgesia administered by anesthesiologists (CZE 20.2%, SVK 20.5%) terminated in cesarean section. CONCLUSIONS: Although labor analgesia was available in all Czech and Slovak obstetric centers, only a small proportion of parturients received an effective method of labor pain relief (regional or intravenous analgesia).

High-risk constellation in living renal transplantation.

There is only limited information about recipient risk factors for graft survival in living- donor kidney transplantation. This study aimed to investigate prognostic factors and their impact on living-related and unrelated renal transplant recipients. From October 2000 until October 2004, 81 adult living-related renal transplantations were performed at our institution. Using multivariate analysis, the association of the following variables with kidney graft outcome was studied: ages of donors and recipients, gender and body mass index, cold and warm ischemia, HLA mismatches, identity and compatibility of blood group, duration of dialysis, cytomegalovirus (CMV) status, recipient original disease, surgical and general complications, and status of retransplantation. Multivariate analysis revealed significant reduction of graft function and graft survival in recipients with retransplantation, more than 4 mismatches, and a high body mass index. Thus, living-donor kidney transplantation can be regarded as a safe and standardized operation relating to surgical technique, but further consideration of the recipient body mass index and the number of mismatches are recommended during the preparation for transplantation.

[R1 resection in the surgery of upper gastrointestinal tumors: relevance and therapeutic consequences]. / R1-Resektion in der Chirurgie des oberen Gastrointestinaltrakts: Bedeutung und therapeutische Konsequenzen.

Microscopically involved tumor margins are an important problem in the surgery of locally advanced esophageal and gastric carcinomas. We conducted a systematic review of the literature and a specific analysis of our own patient database. This article summarizes current knowledge of the incidence and prognosis of R1 resections in upper gastrointestinal cancers. Preoperative strategies for reducing the rate of R1 resections are presented, and the surgical options in case of R1 resection are discussed.

[Lymphadenectomy with tumors of the upper gastrointestinal tract]. / Lymphadenektomie bei Tumoren des oberen Gastrointestinaltraktes.

In surgical therapy for upper gastrointestinal cancer, adequate lymphadenectomy together with R0 resection of the primary tumour is one of the most important prognostic factors which can be influenced by the surgeon. Recommendations for localization- and stage-adapted lymphadenectomy can be made according to histopathologic and anatomic investigations of the patient collectives of large centres. After neoadjuvant radiochemotherapy in cancer of the cervical oesophagus, the absence of lymph nodes on the resected specimen seems to be of less prognostic value. In squamous cell cancer of the suprabifurcal oesophagus, radical lymphadenectomy is recommended. Despite significant morbidity, in specialized centres this procedure yields good results with low mortality. For infrabifurcal oesophageal cancer, two-field lymphadenectomy during the so-called Ivor-Lewis operation is the method of choice. Locally advanced Barrett carcinoma is also an indication for classic two-field lymphadenectomy together with abdominothoracic oesophagectomy and creation of a stomach tube with intrathoracic anastomosis. The lymphadenectomy should however include the area of retroperitoneal lymphatic drainage at the pedicle of the left kidney. Submucosal cancer in this area can be treated with luminal limited resection of the oesophagogastric junction with adequate lymphadenectomy. Adenocarcinoma of the cardia and subcardial gastric cancer including the cardia both require lymphadenectomy analogous to that performed in gastric cancer, with special attention paid to the retroperitoneal lymphatic drainage towards the left kidney pedicle. For therapy of gastric cancer, a systematic D2 lymphadenectomy should always be performed.

[Incidence of hiatal hernias in the current endoscopic praxis]. / Výskyt hiátové hernie v bezné endoskopické praxi.

BACKGROUND: Hiatal hernia represents penetration of the oral part of stomach together with the distal part of oesophagus via oesophageal hiatus into the thoracic cavity. On the basis of endoscopic examination hiatal hernia is defined as circular pull out of the gastric mucosa longer then 2 cm from the diaphragm to Z line, measured at the end of examination during removing the endoscope. Hiatal hernia is usually an acquired state which can worsen oesophagitis by holding refluxate and thus by prolonging the duration of purgation. METHODS AND RESULTS: Endoscopic and radiological studies show that 50 to 94 % of patients with gastroesophageal reflux disease have an axial hiatal hernia while in control persons the incidence fluctuates between 13 % and 59 %. Hiatal hernia is a frequent finding during upper gastrointestinal endoscopy. Hernia can contribute to the development of reflux into the proximal oesophagus. A cohort of one thousand patients (18 to 94 years) who underwent upper gastrointestinal endoscopy was analysed retrospectively. Endoscopy was performed between January and June 2005 at the Endoscopic center of the 4th Medical Department of the University Hospital in Prague. CONCLUSIONS: Presented study has shown that in patients who underwent endoscopy, hiatal hernia occurs in 16.6%, more frequently in men (53.6%). The most common type is an axial hiatal hernia with incidence of 94.58%. In 50% of patients with hiatal hernia the reflux oesophagitis of various degrees was diagnosed.

Isolation, culture, and transplantation of human hepatocytes.

The in situ two-step collagenase perfusion technique used for the isolation of hepatocytes from rat liver was adapted into a procedure applicable to pieces of human liver obtainable from surgical procedures. Human hepatocytes obtained by this method were maintained in primary culture for 10 days. The cellular changes observed at the light microscopic and electron microscopic levels are described. The changes in microsomal enzymes as a function of the age of the cultures were also measured. Exposure of the human hepatocytes to procarcinogens known to be metabolized by rodent liver resulted in unscheduled DNA synthesis. The isolated hepatocytes were also transplanted into two-thirds partially hepatectomized athymic nude mice. The transplanted cells formed nodules with characteristic hepatic architecture. These studies demonstrate that hepatocytes obtained from human liver by the described modified collagenase technique can be used for in vitro studies in chemical carcinogenesis.

Liver regeneration studies with rat hepatocytes in primary culture.

Adult rat parenchymal hepatocytes in primary culture can be induced to enter into DNA synthesis and mitosis. The optimal conditions for hepatocyte replication are low plating density (less than 10,000 cells/sq cm) and 50% serum from two-thirds partially hepatectomized rats (48 hr after hepatectomy). Approximately 80% of the hepatocytes enter the cell cycle, and most of these cells go through mitosis. The replicating hepatocytes remain positive for glucose-6-phosphatase and negative for gamma-glutamyl transpeptidase, and they accumulate fat, in analogy to regenerating liver. Most of the replicating hepatocytes enter into multiple consecutive rounds of DNA synthesis. Dose-response studies between control animal serum and hepatocyte labeling index indicate that in unoperated animals the serum contains substances stimulatory as well as inhibitory for hepatic growth, with the inhibitory effect prevailing at high concentrations. After partial hepatectomy, the inhibitory activity disappears whereas the hepatopoietin activity reaches almost 90% of maximal biological effectiveness at 25% serum concentration. Addition of hormones to the system shows that the hepatopoietin activity is not identical to epidermal growth factor, platelet-derived growth factor, thyroxine, glucagon, or hydrocortisone. Norepinephrine abolishes the difference between control and hepatectomized serum but does not restore hepatopoietin activity when added to heat-inactivated serum. The results show that this system of replicating hepatocytes can be used to investigate the trophic factors that control growth of normal and neoplastic hepatocytes.

Promoting effect of nicotinamide on the development of renal tubular cell tumors in rats initiated with diethylnitrosamine.

Nicotinamide administered in the drinking water of male Fischer 344 rats increased the number of renal tubular cell tumors of rats treated with an i.p. injection of diethylnitrosamine (DEN) (25-mg/kg body weight). The incidence of kidneys with tumors in rats treated with DEN alone was 5%. In rats which received DEN and then were promoted with either 30 or 6.7 mM nicotinamide in their drinking water, the incidence of kidneys with tumors rose to 59 and 28%, respectively. Rats which were on 30 mM nicotinamide but did not receive DEN had no kidney tumors present. These results show that nicotinamide promoted DEN-induced renal tubular cell tumorigenesis.