60-W average power in 810-fs pulses from a thin-disk Yb:YAG laser

We demonstrate a passively mode-locked diode-pumped thin-disk Yb:YAG laser generating 810-fs pulses at 1030 nm with as much as 60 W of average output power (without using an amplifier). At a pulse repetition rate of 34.3 MHz, the pulse energy is 1.75 microJ and the peak power is as high as 1.9 MW. The beam quality is close to the diffraction limit, with M2 < 1.1.

Passively Q-switched 0.1-mJ fiber laser system at 1.53 mum

We demonstrate a passively Q-switched fiber laser system generating pulses with as much as 0.1 mJ of pulse energy at 1.53 mum and a >1-kHz repetition rate. These results were achieved with a simple master oscillator-power amplifier scheme with a single pump source, realized with large-mode-area fiber and multiple reflections upon a semiconductor saturable-absorber mirror.

Surgical therapy of gastrointestinal non-Hodgkin's lymphomas

Within a period of 13 years 39 patients underwent surgery for primary gastrointestinal non-Hodgkin's lymphoma. The stomach was the most frequent site of involvement (26 cases) followed by the small intestine (10 cases) and the large bowel (three cases). Operative procedures included: total gastrectomy (n = 19), subtotal gastrectomy (n = 5), partial gastrectomy (n = 2), small bowel resection (n = 7), right hemicolectomy (n = 5) and sigmoid resection (n = 1). According to Musshoff's modification of the Ann Arbor system, we found stage I in nine, stage II in 12, stage III in two and stage IV in 16 patients. Histological typing according to the Kiel classification showed low-grade malignancy in 11 cases and high-grade in 28. Twenty-eight patients received chemotherapy and/or radiation in accordance with the tumour staging and type of malignancy. The follow-up data were analysed by the method of Kaplan and Meier. Including five patients who died post-operatively from perforated or bleeding lymphomas, the overall 5-year survival rate was 53.8%.

Somatostatin receptor subtypes in neuroendocrine tumor cell lines and tumor tissues

Somatostatin receptor scintigraphy (SRS) is positive in approximately 80% of all patients who have been found to have neuroendocrine (NE) gastroenteropancreatic (GEP) tumors. The reasons for negative results are unclear. The aim of the present study was identification of the specific somatostatin receptor (SSTR) subtypes that are responsible for the in vivo binding of the widely used somatostatin (SST) analogues octreotide and lanreotide in human neuroendocrine gastroenteropancreatic tumors. Ten patients were subjected to SRS with radiolabeled octreotide. Following surgical resection, tumor tissues were analyzed for SSTR subtype mRNA expression by the reverse transcription-polymerase chain reaction (RT-PCR). In addition, SSTR subtype transcripts were investigated by Northern blot analysis and RT-PCR in neuroendocrine tumor cell lines. Expression of SSTR at the protein level was studied by chemical cross-linking experiments. Three patients were negative by SRS. However, RT-PCR revealed most prominently SSTR 2 expression in all tumor specimens. In addition, all tumor tissues analyzed by chemical crosslinking exhibited SST-14 binding sites, indicating that at least some NE tumors were false-negative on SRS.

Hybrid scanning transmission electron/scanning tunneling microscope system for the preparation and investigation of biomolecules

A hybrid scanning transmission electron/scanning tunneling microscope vacuum system is introduced, which allows freeze drying and metal coating of biological samples and their simultaneous observation by scanning transmission electron microscopy and scanning tunnelling microscopy (STM). Different metal coatings and STM tips were analysed to obtain the highest possible resolution for such a system. Bovine liver catalase was used as a test sample and the STM results are compared to a molecular scale model.

[Vascular malformations in the gastric fundus as a rare cause of fundus variceal hemorrhage]

In the differential diagnosis of the aetiology of portal hypertension arterio-portal fistulas as a rare cause have to be taken in account. The case of a 70-year-old male presenting with massive upper gastrointestinal bleeding secondary to gastric varices caused by a vascular malformation of the gastric fundus is reported and the problem of non-cirrhotic portal hypertension is discussed. In case of variceal bleeding aetiology of portal hypertension has to be clarified exactly before any kind of therapeutic intervention to avoid therapeutic pitfall.

High-density lipoprotein reduces epidermal growth factor-induced DNA synthesis in vascular smooth muscle cells

High concentrations of high-density lipoprotein (HDL) are known to decrease the risk of coronary artery disease. In order to study the underlying cellular mechanisms, the influence of HDL on the epidermal growth factor (EGF)-induced vascular smooth muscle cell (VSMC) proliferation was investigated. Approximately 40% of the EGF-induced increase of the cell DNA synthesis was abolished in the presence of 30 micrograms/ml HDL. The EGF-induced dose-dependent (10 pg/ml to 100 ng/ml) increase in DNA synthesis was blunted by 30 micrograms/ml HDL. In addition HDL (3-300 micrograms/ml) caused a dose-dependent inhibition of EGF (20 ng/ml)-induced DNA synthesis, yielding a half maximal effective dose (ED50) of 30 micrograms/ml. Similar experiments with the HDL-protein and HDL-lipid fraction indicated that the HDL-protein fraction is most probably responsible for the observed inhibiting effects of HDL. This was confirmed by using purified apolipoprotein (apo) A-I and apo A-II. Both induced an approximately 80% inhibition of the EGF-induced DNA synthesis. These results may help to explain the observed beneficial effects of HDL on cardiovascular diseases that are described in many epidemiological studies.

[Experiences with intraoperative radiotherapy in gastric carcinoma (Berlin method)]

The aim of our pilot study is to determine whether intraoperative radiotherapy in gastric cancer cannot only prevent a local relapse but also improve the survival rate. Since November 1987, 26 patients with resectable gastric cancer were irradiated intraoperatively with the linear accelerator using fast electrons (single dose: 12 to 16 Gy). Percutaneous radiotherapy was performed postoperatively with 24 to 38 Gy (4 x 2 Gy per week). For intraoperative and percutaneous radiotherapy the target absorbed dose was selected in a way that their combined effect on the tumor was approximately equivalent to that of a total dose of 60 Gy in the usual fractionating. Up to now, the median survival time for stage III patients (UICC 1987) has been twelve months. In five patients who died of a relapse or of peritoneal carcinosis, histologic evaluation revealed in every case a diffuse tumor type according to Lauren-classification. All relapses occurred within the first eight months. The two-year survival rate according to Kaplan-Meier is 67% for stage III. Advanced resectable gastric cancer of the intestinal tumor type seems to profit from adjuvant intraoperative radiotherapy. The results warrant further research within the framework of a prospective randomized multicenter study.

Evaluation of endosonography in TN staging of oesophageal cancer

Strategies for the treatment of cancer of the oesophagus depend on the tumour stage at the time of diagnosis. Resection, the only curative treatment, is confined to early tumour stages. Tumours with local infiltration are usually unresectable and require palliative treatment. Computed tomography has been widely used for preoperative staging but often fails to define this correctly. Endoscopic ultrasound allows direct visualisation of the parietal wall and may be useful in staging gastrointestinal tumours. In a comparative prospective study, 52 patients with tumours of the oesophagus were investigated preoperatively both by endoscopic ultrasound and computed tomography to determine the stage of tumour infiltration and local lymph node involvement. Thirty seven of these patients underwent operation, resection, or dissection and entered the study. The intraoperative findings or the histopathological assessment, or both, were taken as a reference. For all TN stages of oesophageal tumours, correct preoperative staging was accomplished by endoscopic ultrasound in 89% for T stage and 69% for N stage compared with 51% and 51% respectively by computed tomography (highly significant using Fisher's exact test). This study shows that endoscopic ultrasound is useful in preoperative TN staging of tumours of the oesophagus.

[Injuries of the small and large intestine following blunt abdominal trauma]

From 1979 to 1987 1428 patients with blunt abdominal trauma were treated in the Department of Surgery of the University of Freiburg; 119 patients had intestinal injuries. They were mainly young adults who had sustained a car accident. 71.3% of the small bowel injuries were overseen, 14.2% needed resection, and in 14.5% an operative procedure was not necessary. The surgical procedure for colonic injuries has to be chosen with regard to the age and general condition of the patient, to the severity of the trauma, to associated injuries and to the stage of peritonitis. Accordingly, 18% of the patients were treated with and 58% without a protective colostomy, 24% could be treated conservatively. Mortality and morbidity correlated with the severity of associated injuries. Morbidity was also dependent on the time interval between accident and operative therapy.

[Significance of ultrasonic-guided pleural punctures/thoracic drainage after abdominal procedures and blunt abdominal/thoracic trauma]

The sensitivity of ultrasonographic diagnosis of pleural fluid accumulations and the value of ultrasonographically guided thoracentesis were studied prospectively. One hundred ten patients were examined after abdominal operations and chest trauma. Most of the examinations were performed in a half-sitting position. Pleural fluid of clinical relevance, diagnosed by real-time ultrasonography, was treated by thoracentesis under ultrasonographic guidance in 38 cases. The amount of aspirated fluid ranged from 150 to 1350 ml. The sensitivity of the method was 97.1%. The complication rate was 2.6%. There are now 240 patients treated by ultrasonographically guided thoracentesis and 160 cases with pleural drainage. In our view, ultrasonographically guided thoracentesis represents the method of choice in critically ill and immobile patients.

[Endotoxinemia and bacteremia in manual oral decompression of ileus]

In the framework of the present clinical prospective study using a randomly selected patient collective, the question was pursued whether manual oral decompression (MOD), done in connection with surgical intervention in severely ill patients with ileus of the large and small intestine, leads to detectable bacteremia or higher concentrations of endotoxin in serum. From October, 1985 to March, 1987, bacteriological tests were conducted and the endotoxin concentrations in serum were measured in a total of 31 patients. 71% of the patients were female and 29% were male, aged 18-89. The endotoxin measurement was conducted with the aid of the limulus-amoebocyte-lysate (LAL) test, modified according to Piotrowicz. Additionally, bacteriological tests were done of the operation sites and the decompressed gastro-intestinal secretions. Simultaneously, cultures from the central blood stream were prepared. The tests showed that bacteremia and endotoxinemia occur in connection with manual oral decompression (MOD). Neither of the two, however, has any clinically relevant influence on the further post-operative course. Thus, manual oral decompression continues to represent an indispensable maneuver in the surgical management of an ileus.

[Esophagitis--hiatal hernia--indications and choice of procedure: fundoplication]

The fundoplication, described by Nissen in 1956, is still an excellent and the most frequently applied antireflux operation in cases of refluxesophagitis. Accurate preoperative evaluation and subtile operative technique are imperative, however. Typical postoperative syndromes will be discussed. Details of the results will be given with particular regard to 214 fundoplications carried out on our own patients: mortality rate 0%, recurrence rate 4.7%, content with the result of the operation 88%.

Perioperative antibiotic prophylaxis in bile-duct interventions: results of two prospective randomized studies

The success of perioperative prophylaxis in gallbladder surgery was examined in two prospective randomized studies with a total of 326 patients. Postoperative wound-healing impairments did not occur in any of the patients receiving a single preoperative application of an antibiotic with a high biliary elimination rate (ceftriaxone or apalcillin). 11% of a control group without prophylactic antibiotic application evidenced infectious wound-healing disturbances.

[Prevention of thromboembolism with heparin-DHE--safety and trends]

Perioperative thrombosis prophylaxis with low dose heparin-DHE. Efficiently protects against thromboembolic complications. Side effect such as haemorrhage or vasospasms are rarely seen. The known contraindications of DHE have been respected strictly. The latest development is low molecular heparin which has been tried out and evaluated on the ground of a controlled double blind study of 259 patients undergoing general surgery. The study shows the following advantages: thrombosis prophylaxis by one injection pro die only. This means less work for the staff and lower costs. Further studies on low molecular heparin are necessary.

Low molecular weight heparin plus dihydroergotamine for prophylaxis of postoperative deep vein thrombosis

In a prospective, double-blind investigation of the prophylaxis of deep vein thrombosis (DVT) in patients undergoing elective major abdominal surgery, 269 patients were randomized into two groups. One hundred and thirty-two patients received a fixed combination of heparin sodium 5000 units plus dihydroergotamine mesylate 0.5 mg (H/DHE) twice a day and 137 patients received a fixed combination of low molecular weight heparin 1500 units plus dihydroergotamine mesylate 0.5 mg (LMWH/DHE) once a day as well as one injection of placebo per day. Treatment was initiated 2 h pre-operatively in both groups and continued for 7-10 days. The frequency of DVT determined by the 125I-labelled fibrinogen uptake test and phlebography was 10.3 per cent in patients receiving H/DHE and 10.4 per cent in those receiving LMWH/DHE. DVT of the femoral vein was detected in four patients of the H/DHE group and in none of the LMWH/DHE group. Intra- and postoperative blood loss did not differ significantly between both groups. Also no difference in the development of wound haematoma and injection site haematoma was found. While intra-operative volume substitution was comparable in both groups, significantly more patients under H/DHE prophylaxis received volume substitution during the postoperative phase. These results show that once-daily prophylaxis with the combination of low molecular weight heparin and dihydroergotamine is equally as effective and as safe as the twice-daily regimen using a combination of unfractionated heparin and dihydroergotamine in patients undergoing elective, major abdominal surgery. The advantages of the once-daily regimen of LMWH/DHE include greater patient acceptance, less nursing time and greater cost effectiveness, provided the new combination can be sold at a cost which maintains this advantage.

[Systemic antibiotic prophylaxis with metronidazole in elective colonic and rectal surgery. Results of a clinical controlled study and a critical literature review]

The pathogen spectrum of wound infections in colon surgery is composed almost exclusively of facultatively aerobic and obligatorily anaerobic intestinal flora. A study was performed in which a one-shot prophylaxis was carried out by applying metronidazole, 500 mg i.v., or latamoxef (lamoxactam) 2 g i.v., on induction of anesthesia. The metronidazole group evidenced a 26.3% incidence of infections due exclusively to aerobic pathogens. In the latamoxef (lamoxactam) group, it was possible to achieve a reduction of the postoperative rate of wound infections to 11.1%. The study was prematurely terminated because of the high rate of wound infections in the metronidazole group and the exclusive selecting of aerobic pathogens.

[Where and when does surgery achieve cancer prevention? Precancerous conditions of the stomach]

The early diagnosis of stomach diseases, that are high risk factors for cancer is of paramount importance, because the early cancer can be healed nowadays. Distinguish between precancerous lesions (adenoma, borderline-lesion, dysplasia III) and precancerous conditions (chronical atrophic gastritis, pernicious anemia, Ménétrier syndrome, hyperplasiogene polyps, the operated stomach, rarely ulcus ventriculi). Whereas precancerous lesions must be removed by diathermy-biopsy or operation, precancerous conditions need thorough endoscopic control. In operations for ulcerous disease the operation tactics must be chosen with the aim to avoid a carcinoma after gastric resection.

Antibiotic infection prophylaxis in gallbladder surgery--a prospective randomized study

In the course of 1 year, 180 patients undergoing elective surgery for confirmed cholelithiasis were included in a prospective randomized study in which they either received 2 g of preoperatively applied ceftriaxon intravenously at the beginning of anesthesia or, as an alternative, no antibiotic at all. Infectious wound-healing disturbances occurred postoperatively in 11% in the control group and in no case in the prophylaxis group. The difference is statistically significant.

[Stress tolerance of the patient in abdominal surgery: stomach cancer]

Patients with gastric cancer undergoing surgery have much to endure and are accompanied by many risks. These risks depend on localization and extent of the tumor, the patients' general condition (nutritional and immune status), age, coexistent diseases and the extent of the required operation. In view of these facts, the principle of radical surgery must be weighed against the tolerance capability of the patient, especially in old people. Extensive diagnostic procedures are necessary to explore those risks. The preoperative treatment (hyperalimentation), the well considered indication for surgery, the choice of operation with lowest risk and the perioperative measurements are of great importance in limiting the risk for the patient.

[Peritoneovenous shunt in the treatment of therapy resistant ascites. Results of 7 years' experience]

In recent years, implantation of a peritoneo-venous shunt has proven effective in the treatment of therapy-resistant ascites. From 1976 till 1983, a total of 63 shunt systems (Le Veen-, Agishi -, Denver system) were implanted in 55 patients with a mean age of 52.3 years. The most common cause for ascites was hepatic cirrhosis. The average functional period amounted to 21.7 months and the longest implantation time to nearly 7 years. The postoperative complication rate is considerable: 19 patients died in the postoperative course. The most dreaded complication is shunt infection and intravascular thrombopathy . In spite of the high complication rate, the establishment of a peritoneo-venous shunt is recommendable for combatting therapy-resistant ascites.

Effects of angiotensin II and ACTH on normal and tumourous human adrenocortical cells

Isolated adrenocortical cells from 6 patients with a 'normal' zona fasciculata, 4 patients with a 'normal' zona glomerulosa, and tumour cells from 1 adrenocortical adenoma and 1 carcinoma were incubated with and without increasing concentrations of ACTH 1-24 (10(-13) M to 10(-9) M) or Asp1-Ile5-angiotensin II (10(-11) M to 10(-7) M). In 4/5 'normal' cases, cortisol was clearly stimulated by 10(-13) M ACTH. The maximum of the dose-response curve (5-fold stimulation) was reached at 10(-10) M ACTH. Angiotensin II (AII) started to stimulate 'normal' cells at 10(-11) M with a maximum (2-fold stimulation) at 10(-9) M. Aldosterone production by 'normal' cells was less markedly stimulated by ACTH and AII, although the threshold doses for both peptides were similar to those of the cortisol response curves. The cells of the adrenocortical adenoma from a patient with Cushing's syndrome produced large amounts of cortisol and small amounts of aldosterone, both steroids being clearly stimulated by ACTH and AII. The adrenocortical carcinoma cells produced small amounts of cortisol and no aldosterone. Cortisol production responded to ACTH, but not to AII. The results suggest that an activated renin-angiotensin system may stimulate the zona fasciculata, since 10(-11) M AII (= 10 pg AII/ml) is a normal plasma AII concentration on an unrestricted diet. Clinical evidence supporting this thesis is reviewed. However, cortisol production itself will rarely be increased by AII in vivo, since a down-regulation of ACTH would occur.

[Functional evaluation of islet cells following pancreatic duct occlusion--a long-term study]

The transduodenal occlusion of the pancreatic duct with Prolamin (Ethibloc) was carried out in an experiment with 38 Göttinger minipigs. Occlusion of the pancreatic duct leads to selective atrophy of the excretory pancreatic parenchyma. Up until now it has not been clear whether the endocrine functional capacity of the gland stays intact in a long-term experiment or whether the islands of Langerhans are also altered by the pancreatic duct occlusion. The following tests were carried out by us to determine the endocrine status: 1. Intravenous glucose tolerance test (i.v. GTT); 2. Glucose assimilation analysis after CONARD (K-value); 3. Insulin analysis during i.v. GTT; 4. Intravenous Tolbutamid test. Twelve months after the occlusion, reduced glucose tolerance and a reduction in insulin secretion were detected in the intravenous glucose tolerance test. Glucose assimilation (K-value) was not changed significantly. Fasting blood sugar and basic insulin level remained unchanged. Only a small blood-sugar decrease was measured after selective B-cell stimulation with Tolbutamid. The fibrosclerosis produced by the occlusion of the pancreatic duct with Prolamin also seemed to attack the cells of the islands and lead to their partial destruction.

[Prevention of postoperative thrombotic complications with heparin and dihydroergotamine. A randomized double-blind study]

In a randomized double-blind study of 660 patients with predominantly abdominal-surgical procedures the thrombosis-preventing effect of the following was compared: heparin 5000 (low-dose heparin), heparin 2500, a combination of heparin 2500 and 0.5 mg dihydroergotamine (HDHE 2500), 0.5 mg dihydroergotamine (DHE), and placebo. All preparations were administered three times daily. Radiofibrinogen test gave the following thrombosis incidence: heparin 5000-15.4%; heparin 2500-24%; HDHE 2500-13.2%; DHE-24.6%; placebo-28.9%. Bleeding complications, included postoperative blood loss (more than 500 ml), unusually marked bleeding from drains, seroma, wound haematoma, and re-operation. The rate of these complications was 18.5% with heparin 5000, 7.8% with placebo, 5.6% with DHE, 4% with heparin 2500 and 3.1% with HDHE 2500. The non-specific tolerance to the various preparations was good, especially in that there was no increased risk of coronary complications with HDHE or DHE, and there was no pointer to peripheral vasospasms. This study confirms the synergistic thrombosis-preventing effect of combined heparin-dihydroergotamine.

[Diagnosis of suture insufficiency--clinical, laboratory and x-ray findings and special examinations]

Early recognition of a suture insufficiency in the small or large intestine is important for systematic therapy. Apart from consideration of drainage secretion, assessment of general condition and of the abdomen are the most important diagnostic measures. These can be supplemented by laboratory findings of leucocytosis, thrombocytopenia, and respiratory alkalosis. Additional measures are Gastrografin tests, endoradiography, digital and rectoscopic examination, and possibly also computer tomography and sonography.

[Percutaneous transluminal angioplasty before exposure in stage IV of arteriosclerotic occlusion disease (author's transl)]

In 1979 and 80, 34 stage IV patients, whose vascular situation could not be sufficiently visualized by angiography, underwent exploratory exposure. In 15 patients primary amputation had to be performed, in 19 patients reconstruction was possible. 7 of these patients had to undergo secondary amputation. During the same period of time, we performed PTA in 29 stage IV patients, in whom vascular reconstruction was not practicable. In 14 patients PTA was successful, in 15 patients its performance was technically impossible or rethrombosis occurred. Although the two patient groups are not comparable because of different vascular situation, on the basis of positive experience, we recommend that a PTA be performed before exploratory exposure or amputation in stage IV.