Hot carrier extraction from 2D semiconductor photoelectrodes

Hot carrier-based energy conversion systems could double the efficiency of conventional solar energy technology or drive photochemical reactions that would not be possible using fully thermalized, "cool" carriers, but current strategies require expensive multijunction architectures. Using an unprecedented combination of photoelectrochemical and in situ transient absorption spectroscopy measurements, we demonstrate ultrafast (<50 fs) hot exciton and free carrier extraction under applied bias in a proof-of-concept photoelectrochemical solar cell made from earth-abundant and potentially inexpensive monolayer (ML) MoS2. Our approach facilitates ultrathin 7 Å charge transport distances over 1 cm2 areas by intimately coupling ML-MoS2 to an electron-selective solid contact and a hole-selective electrolyte contact. Our theoretical investigations of the spatial distribution of exciton states suggest greater electronic coupling between hot exciton states located on peripheral S atoms and neighboring contacts likely facilitates ultrafast charge transfer. Our work delineates future two-dimensional (2D) semiconductor design strategies for practical implementation in ultrathin photovoltaic and solar fuel applications.

[Options and Limitations in Endovascular Therapy for Acute and Chronic Mesenteric Arterial Occlusions]

BACKGROUND

The significance of endovascular therapy for mesenteric ischaemia (MI) is being debated. Despite initially lower mortality and morbidity, inconsistent early and late results led to questions concerning indications and technical applications of the procedure.

METHODS

91 patients with MI underwent endovascular treatment in a period of 11 years. In 78 (85.7 %) patients a stent was deployed and in 13 (14.3 %) an angioplasty was performed, principally of the superior mesenteric artery (n = 81/91, 89 %). Follow-up consisted of a clinical and an ultrasound examination in all cases. Mean follow-up was 4.2 years. Our results were compared to those in the literature.

RESULTS

Endovascular treatment of the intestinal arteries accounted for 0.6 % of all vascular procedures. Seven of 91 patients (7.7 %) died after an initial PTA/stenting. The overall peri-interventional morbidity was 6.6 % (n = 6/91). Medium- to long-term complications were encountered in 20 patients (22 %), primarily during the first year (85 %). Six of 91 patients developed an in-stent stenosis (6.6 %) and 14/91 patients (15.4 %) stent occlusion. Additionally 2 dislocated stents (2.2 %) and an arterial perforation with bleeding into the mesentery (1.1 %) were seen. Although 3 of these 20 patients were successfully treated with an additional PTA or stenting (15.0 %; n = 3/91, 3.3 %), surgical conversion was necessary in 9 (n = 9/20, 45 %; n = 9/91, 9.9 %). The postoperative mortality was respectively 22.2 % (n = 2/9; n = 2/91, 2.2 %). In the case of acute MI, endovascular procedures are only indicated for patients without peritonitis. In chronic MI, the indication for endovascular treatment depends on the type of occlusion and the vascular anatomy. Despite favourable early results, the outcome of endovascular treatment deteriorates with time reaching a 1-year patency rate of 63 % in a multicentre analysis. This leads to secondary procedures in 30 %. A surgical conversion carries a high mortality.

CONCLUSION

The endovascular treatment of intestinal artery disease cannot be considered the treatment of choice, it is rather an alternative method in patients with functional or local contraindications to surgery. Life-long follow-up is necessary to prevent stent complications with fatal consequences. A prospective randomised study concerning the evaluation of the advantages and disadvantages of surgical and endovascular therapy of intestinal artery occlusive disease is required.

[The future of vascular medicine]

In the future vascular medicine will still have a great impact on health of people. It should be noted that the aging of the population does not lead to a dramatic increase in patient numbers, but will be associated with a changing spectrum of co-morbidities. In addition, vascular medical research has to include the intensive care special features of vascular patients, the involvement of vascular medicine in a holistic concept of fast-track surgery, a geriatric-oriented intensive monitoring and early geriatric rehabilitation. For the future acceptance of vascular medicine as a separate subject area under delimitation of cardiology and radiology is important. On the other hand, the subject is so complex and will become more complex in future specialisations that mixing of surgery and angiology is desirable, with the aim to preserve the vascular surgical knowledge and skills on par with the medical and interventional measures and further develop them. Only large, interdisciplinary guided vascular centres will be able to provide timely diagnosis and therapy, to deal with the growing multi-morbidity of the patient, to perform complex therapies even in an acute emergency and due to sufficient number of cases to present with well-trained and experienced teams. These requirements are mandatory to decrease patients' mortality step by step.

[Ureteroarterial fistula - pathogenesis, diagnostics, and therapeutic outcome]

Although ureteroarterial fistulas are rare, they result in a high mortality because of the massive urogenital haemorrhage. The diagnosis is often difficult even when invasive measures are applied. Including the ureteroarterial fistula in the diagnostic process in cases of macrohaematuria with a positive medical history can be helpful. A ureteroarterial fistula typically develops in pa-tients who have undergone pelvic surgery and radiation as well as after long-term ureteral stents. Patients are usually multimorbid. The treatment of choice consists of fistula exclusion by stent graft deployment in the iliac artery and application of a ureteral stent or a ureterostomy. The significance of surgical treatment is diminishing. The long-term results of endovascular treatment, however, are inconsistent because of stent infections and recurrent bleeding. Therefore, close patient surveillance and cooperation among the treating specialists is necessary.·

Thoracal, abdominal and thoracoabdominal aortic aneurysm

AIM

Aortic aneurysm is a complex disease affecting males and females in a different way. We analysed gender specific differences in the abdominal (AAA), thoracal (TAA) and thoraco-abdominal (TA-AA) aortic aneurysm in patients hospitalized for aortic aneurysm (AAA) in Germany.

METHODS

Detailed lists for all patients suffering from AAA, TAA or TA-AA documented in the DRG-System as principal diagnosis in the years 2010 were provided by the Federal Statistical Office.

RESULTS

The total number of cases in males was 17,731. It was more than three time higher than in females with 4657. AAA were 6.2 time more frequent in males than in females, TAA and TA-AA only 1.6 and 1.5 times, respectively. The rates of ruptured aneurysms show a steep increase in the 9th and 10th decade which is more pronounced in females. In males there is an age dependent increase in the rate of endovascular treatment of TAA and AAA. There is no such trend in females. The rate for AAA even decreases with age. The same could be shown for more complex fenestrated or branched endoprotheses. In around 20% of all male cases with TA-AA such a design is used in the 7th to the 9th decade of life. In females such a rate is only reached in the 7th decade. In older females the rate stepwise decreased.

CONCLUSION

There are gender specific differences in the rate of rupture and endovascular treatment of AAA, TAA and TA-AA in males and females in Germany. The reasons for these differences should be elucidated in order to prove whether these differences are due to actual gender specific requirements, or simply a lack of compatibility in awareness and devices.

Study of two-neutron radioactivity in the decay of 26O

A new technique was developed to measure the lifetimes of neutron unbound nuclei in the picosecond range. The decay of 26O→24O+n+n was examined as it had been predicted to have an appreciable lifetime due to the unique structure of the neutron-rich oxygen isotopes. The half-life of 26O was extracted as 4.5(-1.5)(+1.1)(stat)±3(syst)  ps. This corresponds to 26O having a finite lifetime at an 82% confidence level and, thus, suggests the possibility of two-neutron radioactivity.

Unresolved question of the 10He ground state resonance

The ground state of (10)He was populated using a 2p2n-removal reaction from a 59 MeV/u (14)Be beam. The decay energy of the three-body system, (8)He+n+n, was measured and a resonance was observed at E=1.60(25) MeV with a 1.8(4) MeV width. This result is in agreement with previous invariant mass spectroscopy measurements, using the (11)Li(-p) reaction, but is inconsistent with recent transfer reaction results. The proposed explanation that the difference, about 500 keV, is due to the effect of the extended halo nature of (11)Li in the one-proton knockout reaction is no longer valid as the present work demonstrates that the discrepancy between the transfer reaction results persists despite using a very different reaction mechanism, (14)Be(-2p2n).

Evidence for the ground-state resonance of 26O

Evidence for the ground state of the neutron-unbound nucleus (26)O was observed for the first time in the single proton-knockout reaction from a 82 MeV/u (27)F beam. Neutrons were measured in coincidence with (24)O fragments. (26)O was determined to be unbound by 150(-150)(+50) keV from the observation of low-energy neutrons. This result agrees with recent shell-model calculations based on microscopic two- and three-nucleon forces.

Exploring the low-Z shore of the island of inversion at n=19

The technique of invariant mass spectroscopy has been used to measure, for the first time, the ground state energy of neutron-unbound (28)F, determined to be a resonance in the (27)F+n continuum at 220(50) keV. States in (28)F were populated by the reactions of a 62 MeV/u (29)Ne beam impinging on a 288 mg/cm(2) beryllium target. The measured (28)F ground state energy is in good agreement with USDA/USDB shell model predictions, indicating that pf shell intruder configurations play only a small role in the ground state structure of (28)F and establishing a low-Z boundary of the island of inversion for N=19 isotones.

Trends in lower extremity surgical and endovascular revascularization in Germany

BACKGROUND

We analyzed trends in lower extremity endovascular and open surgical procedures in hospitalized patients in Germany.

PATIENTS AND METHODS

We used national statistics (DRG statistics) published by the Federal Statistical Office including data from almost all hospitals in Germany to calculate annual procedure rates of lower extremity endovascular and open surgical procedures in the years 2005 to 2008. Detailed lists of the OPS-codes 8 - 836, 5 - 381, 5 - 393 separated by the 6th number of the code were analyzed regarding procedures representing revascularization of peripheral arteries including the aorta.

RESULTS

Between 2005 and 2008 the total number of endovascular procedures increased from 73,584 to 98,664 and the number of surgical procedures from 74,789 to 86,172 a year. Age-adjusted incidence rates of endovascular procedures in people >= 65 years increased from 325 to 432 per 100,000 while the incidence rates of all open surgical procedures increased from 315 to 351 per 100.000. Looking only at bypass surgery the incidence remained unchanged with 177 and 176 per 100,000 in the same period. Endovascular procedures other than balloon angioplasty including percutaneous atherectomy, laser recanalization or usage of cutting balloon, account for less than 1 % in Germany.

CONCLUSIONS

The numbers of endovascular procedures overweigh the numbers of open surgical procedures for treatment of lower extremity PAD in Germany today. In contrast to data from the USA we could not demonstrate a decrease of open surgical procedures in Germany in recent years.

[Chronically progressive occlusive disease of intestinal arteries - short overview from a vascular surgical perspective]

BACKGROUND

Intestinal ischaemia is quite rare among the cardiovascular diseases. However, it is increasingly diagnosed. The aim of this selective but representative short overview is to assess the impact of intestinal ischaemia in vascular and visceral medicine from a vascularsurgical perspective.

MATERIAL AND METHODS

A literature search and selection in relevant online services of the medical scientific literature was performed, in particular, of the last decade on the competent management of intestinal ischaemia combined with the clinical expertise obtained in daily vascular surgical practice including didactically prepared demonstrable cases / case reports related to typical / specific clinical problems and situations.

RESULTS AND DISCUSSION

Although the superior mesenteric artery (SMA) is most frequently responsible for the clinical presentation, usually 2 or 3  major arterial trunks are involved for a relevant clinical symptomatology. These disorders of the intestinal circulation are most frequently caused by progressive atherosclerotic occlusive disease. In chronic progressive disease, the visceral arteries show the ability to enlarge typical collateral circulation pathways, which may not always lead to a complete compensation. With a degree of stenosis of more than 70 %, mesenteric ischaemic pain and physical prostration are the major clinical findings. Intestinal infarction with a mortality rate of 60-80 % is the endpoint of the chronically progressive intestinal ischaemia. There-fore, an urgent medical treatment is highly required. CT angiography is the diagnostic procedure of choice in patients with suspected chronic intestinal ischaemia. Mesenteric angiography is subject to specific questions and / or to endovascular arteriographic treatment. Duplex scanning has been advocated as a non-invasive method of pre- and post-interventional screening. Treatment is indicated in symptomatic intestinal vascular disease. Due to the high morbidity of the majority of patients and the enormous invasivity associated with conventional surgery, arteriographic intervention is the treatment of choice, even though quality improvement is required. Surgical reconstructions are highly standardised and should be associated with perioperative mortality less than 3 %. We recommended the reconstruction of 2  vessels, for which antegrade supracoeliacal revascularisation techniques are favourable. In (threatening) septic conditions, autologous reconstructions are required. Intestinal infarction is the most serious complication of all visceral revascularisations. In recurrent occlusions of visceral arteries, it is recommended to favour and finally use a different therapeutic modality. Post-therapeutic care includes second-look operation as well as clinical examination and diagnostic imaging. Antithrombotic therapy should be initiated. The further screening of patients after intestinal revascularisation should be performed by duplex scanning.

CONCLUSION

Chronically progressive occlusive disease of intestinal arteries is considered as a complex disease with challenging diagnostic and therapeutic management, in which an interdisciplinary, partly finding- and stage-dependent (also with regard to the frequency and recurrency of the specific local finding) sequential therapeutic approach (e. g., endovascular vs. open procedure; interventionalist / endovascular specialist / vascular surgeon) becomes more and more relevant requiring a competent center of vascular medicine.

[Chronic intestinal ischemia]

Ischemic lesions of the splanchnic organs are characterized by an insidious course and therefore are often underestimated. They can result in dramatic courses of disease which even in the last decade still results in a mortality of up to 90%. The reasons for this depressing situation are various but mainly due to insufficient consideration of the symptoms and late therapy due to delayed diagnosis.The incidence of chronic splanchnic ischemia is approximately 1-2% of all abdominal diseases. In contrast to acute intestinal ischemia the course is progressive, caused by progression of the underlying atherosclerosis and polymorbidity in this aging society. On the one hand occlusions of splanchnic arteries are diagnosed more often and on the other hand the incidence has increased due to the rising number of therapy-linked vascular catheter maneuvers. Due to excellent collateralization, diffuse stenotic processes can maintain asymptomatic for a long time. Duplex sonography should be performed as this technique reveals relevant insights into the hemodynamic severity of lesions.

[Amputation of ischaemic extremities--a vascular surgeon's point of view]

The amputation surgery being one of the oldest branches of surgery itself is often times discredited since amputations are frequently considered as a result of failure of alternative therapy options. Worldwide hundreds of thousands amputations are performed annually even though especially in vascular surgery great progress in revascularisation techniques and abilities has been made. Presumably due to rising of life expectancies and increase of diabetes mellitus the number of amputations will in future even rise. Peripheral artery disease and diabetes mellitus which are often associated with a high comorbidity are the most common causes of critical limb ischemia and amputations of the lower extremity. Complications after major amputations like wound infection, development of phantom pain, severe mental distress, myocardial infarction or stroke are frequent. Survival one year after amputation range from 30-50%. The patient collective of amputees is a large group with a high degree of comorbidity in need of special attention and care. The level of amputation ( i.e.: above vs. below knee), postoperative complications, early mobilisation and use of prosthesis are important for the postoperative outcome and the amputees further fate. To regain the independence and mobility in the known social surrounding after amputation is often not to achieve but should be the highest aim of the treating persons.

Highly coherent injection-seeded 13.2 nm tabletop soft x-ray laser

We report a dramatic improvement of the spatial coherence and beam divergence (0.66 mrad) of a 13.2 nm wavelength Ni-like Cd tabletop laser by injection seeding the soft x-ray laser amplifier with high-harmonics pulses generated in a Ne gas jet. This phase coherent laser is an attractive light source for at-wavelength interferometry of extreme ultraviolet lithography optics and other applications.

Selective population and neutron decay of an excited state of 23O

We have observed a resonance in neutron-fragment coincidence measurements that is presumably the first excited state of 23O at 2.8(1) MeV excitation energy which decays into the ground state of 22O. This interpretation is consistent with theory. The reaction mechanism supports the assignment of the observed state as the 5/2+ hole state. This assignment and the recently observed 3/2+ particle state advance the understanding of 23O.

Aufgaben und Funktion des Medizinischen Dienstes der Krankenversicherung (MDK)

The German Medical Review Board of the Statutory Health Insurance (MDK) is a sociomedical service for impartial medical opinion and consultation. Together with the statutory health insurance companies it takes part in shaping the public health care system. Many recent developments are changing the german health insurance system. This article illustrates the complex sociomedical framework of MDK's activities in relation to current issues in dermatology. The article focuses on: new diagnostic and therapeutic methods, drugs (off-label-use), out-patient and in-patient dermatological rehabilitation and hospital treatment.

[Cost comparison of different graft materials in femoropopliteal bypass: experience with G-DRG]

BACKGROUND

The German DRG classification refrains from medical accuracy of different surgical procedures by concentrating mainly on economic aspects. The process cost calculation of femoropopliteal bypass should as an example illuminate the charge of a surgical procedure under hospital conditions.

METHODS

From 07/03 to 03/04 we analysed out of 71 peripheral arterial reconstructions 10 alloplastic grafts (PBP) and 10 autologous vein grafts (VBP) for femoropopliteal above-knee bypass through the process cost calculation. This required a classification of the procedure in different diagnostic and treatment sections (ward, intensive care, diagnosis, treatment (surgical procedure)).

RESULTS

The average length of hospitalisation with VBP amounted to 12.2 +/- 3.6 (7-19) days, and with PBP to 14.0 +/- 8.0 (8-35) days. The duration of the surgical procedure was almost identical with 118 +/- 26 minutes (VBP) compared to 110 +/- 31 minutes (PBP), but in average 0.4 more assistants participated in VBP. One bleeding caused revision in VBP; one PBP led to extended length of hospitalisation because of wound complication. We diagnosed one asymptomatic bypass occlusion in VBP. The average total costs in VBP amounted to 4 368.10 euro (profit: 4 468.15 euro), in PBP to 5 069.50 euro (profit: 3 802.94 euro).

CONCLUSION

The reconstruction of the superficial femoral artery with alloplastic or autologous vein graft is profitable in G-DRG. Although less medical staff in required in PBP the price of the prosthesis weakens the profit. The autologous vein graft shows furthermore a shorter length of hospitalisation. Further investigation into cost-effectiveness regarding long-term follow-up and patency rates could lead to consequences for the German health system.

High repetition rate operation of saturated tabletop soft x-ray lasers in transitions of neon-like ions near 30 nm

We report average powers exceeding 1 microwatt in laser transitions of Ne-like ions at wavelengths near 30 nm. Gain-saturated operation was obtained at a repetition rate of 5 Hz exciting solid targets with pump pulses of ~1 J energy and 8 ps duration impinging at grazing incidence of 20 degrees. Gain-length products of about 20 were obtained in the 30.4 nm and 32.6 nm transitions of Ne-like V and Ne-like Ti respectively. Strong lasing was also observed in Ne-like Cr at 28.6 nm and in the 30.1 nm line of Ne-like Ti.

Donor-specific sensitization by cadaveric venous allografts used for arterial reconstruction in peripheral arterial occlusive vascular disease

The use of allogeneic venous grafts from postmortal organ donors allows for the reconstruction of critically affected arteries in patients with peripheral occlusive vascular disease. We were interested to determine the prevalence and specificity of anti-HLA antibodies in patients after allogeneic vein transplantation. Anti-HLA class I and II alloantibodies were analyzed by flowcytometric analysis using color-coded microbeads coated with HLA antigens including recombinant single antigens. Nine out of 10 patients involving 12 venous allografts were positive for anti-HLA alloantibodies. All antibody-positive patients carried both anti-HLA class I and II alloantibodies. Anti-donor HLA specificity of the anti-HLA alloantibodies was seen in seven out of nine patients for anti-class I antibodies and in eight out of nine patients for anti-HLA class II antibodies. A high rate of donor-specific allosensitization was seen after allogeneic venous transplantation. In conclusion, allosensitization not only includes a humoral response against the constitutively expressed class I antigens but also extends to class II antigens.

[Homologous vein transplantation in cruropedal arterial reconstruction]

Allogenic venous transplantation represents an alternative procedure for preventing leg amputation. This study reviewed the question of whether immunologic monitoring and immunosuppressive therapy provide results close to those of autologous reconstructions. Twenty-eight patients received 31 homologous venous transplants. The average age in this group of 15 women and 13 men was 64.5 years. Limbs in danger of amputation could be kept longer in two thirds of them. These promising results show the superiority of this method over the use of alloplastic material in regions with cruropedal vessels. Therefore, it can be recommended in acute leg ischemia with lack of autologous vascularity. Improving guidelines for indication will be an interesting research field, and more contributions are needed.

[Interdisciplinary operative procedure-pelvis and abdomen]

Surgery for tumors in the abdomen, retroperitoneum, and pelvis requires technical skills and expertise sometimes beyond the capability of a single surgeon. This holds especially true if curative tumor resection involves replacement of arteries and veins, which needs careful planning to avoid long periods of ischemia, and the selection and provision of vascular substitutes according to anatomical position, postsurgical therapy, and adjuncts to avoid thrombosis and infection of vascular grafts. Since the works of Fortner, the value of close collaboration between general and vascular surgeons has been demonstrated, but many of the former even today continue to attempt the operation alone, although the result is not always a masterpiece. The authors refer to their experience in major tumor surgery in either the single management of vascular complications or collaboration. The potential value of close collaboration is presented by negative examples, and a plea is made for a less "eminence"-based management of these sometimes difficult cases, which is based on vast positive experience with vascular diseases of the aorta and the visceral and iliac arteries and veins, including safety measures and adjuncts.

Outcome of critical foot ischaemia in longstanding diabetic patients: a retrospective cohort study in a specialised tertiary care centre

Background: We sought to establish risk factors predicting the outcome of foot lesions in longstanding diabetic patients with critical foot ischaemia (CFI). Patients and methods: We investigated retrospectively 98 consecutive diabetic patients with ischaemic foot lesions. The patients (mean age 70 years, duration of diabetes 21 years) were jointly cared for by specialised diabetologists and vascular surgeons; 75 patients were treated by arterial revascularisation. Results: Good outcome (lesions healing) was observed in 53 patients (54%). Bad outcome was observed in 45 patients: not healing lesions (n = 5), major amputation(n = 19), and death in relation to the foot lesion (n = 21). Patients with good and bad outcome did not differ regarding age, sex, smoking status, type, duration and treatment of diabetes mellitus, presence of neuropathy, coronary heart disease, stroke, previous amputations, current revascularization, and localization of the foot lesion. The risk of bad outcome was increased 8.9 times in patients on dialysis for end-stage renal disease; 7.0 times if surgical complications were present; and 5.4 times with C-reactive protein (CRP) above the second quintile (cut-off value 8 mg/dl). Conclusion: Management of longstanding diabetic patients with ischaemic foot lesions leaves room for improvement. Dialysis treatment, elevated CRP levels and surgical complications were strongly predictive of non-healing lesions, major amputation and death.

[Reconstruction of the inferior vena cava for extended resection of malignant tumors]

OBJECTIVES

Malignant tumor invasion in the inferior vena cava (IVC) has for a long time been the limiting factor in the resection of retroperitoneal tumors. The clinical outcome in these patients depends on vascular surgical techniques, the central role of which is played by IVC reconstruction.

METHODS

Within the last 7 years, 9,085 vascular reconstructive procedures were performed in our department. Six patients suffered from retroperitoneal invasion of tumor into the IVC. After tumor resection, the involved IVC segments were replaced by polytetrafluorethylene (PTFE) grafts to restore IVC continuity. In three patients, an adjunctive arteriovenous (AV) fistula was constructed.

RESULTS

The graft patency after a mean follow-up of 30.2 months (range 1 to 79) was 83.3%. The only graft occlusion occurred in a patient without AV fistula. There were no perioperative deaths and no major complications demanding reoperation.

CONCLUSION

In patients with tumor involvement of the IVC, clinical outcome depends on vascular surgical coprocedure. After resection of the IVC, a PTFE graft should be interposed in combination with an AV fistula. Anticoagulation and CT scan are recommended after 3 months before ligation of the AV fistula.

[Current diagnosis and therapy of non-occlusive mesenteric ischemia]

PURPOSE

Non-occlusive mesenteric ischemia (NOMI) is a life threatening disease. Therapy and prognosis depend upon the length of time elapsed between primary clinical manifestation and the time of definitive diagnosis and treatment.

MATERIALS AND METHODS

NOMI was diagnosed by intraarterial selective angiography in four patients. After a bolus administration of 20 g Alprostadil (Prostavasin) into the superior mesenteric artery, intraarterial perfusion was continued with 60 microg Alprostadil/day via the catheter for three days.

RESULTS

The mesenteric ischemia resolved in all patients. One patient recovered completely. Three patients recovered from mesenteric ischemia, but died subsequently due to complications of their primary diseases.

CONCLUSION

When NOMI without perforation or necrosis of the bowel wall is suspected clinically, immediate intraarterial angiography is the diagnostic method of choice. If NOMI is confirmed, the appropriate treatment is the intraarterial application of potent vasodilators for several days. The diagnostic work-up in suspected NOMI and the impact of different radiological examinations are explained. The literature is reviewed.

[The acute mesenteric ischemia - not understood or incurable?]

PURPOSE

Despite surgical research and progress, the high mortality of acute intestinal ischemia seems to be improved insignificantly over the past fifty years. In this study we analyzed the specific diagnostic and therapeutic problems of the disease in order to improve further management of acute mesenteric ischemia.

METHODS

From 1979 until 2000 64 patients (female 31, male 33) with a mean age of 64 (30-89) years underwent operation for primary intestinal ischemia at our institution. All medical and surgical records and imaging studies were reviewed retrospectively. Follow up consisted of clinical examination and duplex sonography.

RESULTS

Only in 26 patients (41 %) a preoperative diagnostic work-up including angiography 12 and CT 14 was performed, whereas in 42 cases the intestinal ischemia was diagnosed during surgical exploration. Intestine malperfusion was caused primarily by venous thrombosis in 9 cases (14 %) and by arterial occlusive disease in 55 cases (86 %). Arterial disorders consisted of arterial thrombosis in 19 cases (30 %), arterial embolism in 18 cases (28 %), aortic or mesenteric artery dissection in 10 cases (15 %), non occlusive disease (NOD) in 5 cases (8 %), trauma 3 cases (5 %). Five different therapeutic strategies were applied: group I: Intestinal resection: 24 patients, anastomotic insufficiency 5 (39 %), mortality 11 (46 %), group II: intestinal artery revascularization: 5 patients, secondary patency rate 80 %, mortality 40 %, GROUP III: Intestinal artery revacularization and perfusion with Ringer's solution: 11 patients, mortality 8 (73 %), group IV intestinal artery revascularization and intestinal resection: 3 patients, mortality 100 %, group V intestinal artery revascularization and perfusion and intestinal resection: 3 patients, mortality 33 %. A second look operation was performed in 29 cases (40 %) and displayed malperfusion in 72 %. Only 21 of 64 patients survived the acute intestinal ischemia (in hospital mortality was 67 %). Delayed diagnostic and operation caused higher mortality (interval 10 hours: mortality 59 %, interval 37 hours mortality; 71 %, p = 0,06). Follow up after 61 (4-72) months of 21 patients (100 %) could be achieved. Ten patients (48 %) had meanwhile died, 5 patients (50) % as consequence of mesenteric ischemia, the others of unrelated reasons. Eleven patients are still alive without clinical signs of intestinal ischemia.

CONCLUSIONS

Early diagnosis before hospitalisation and in-hospital (arteriography) and operation are essential to improve the outcome of patients with acute intestinal ischemia. To avoid short bowel syndrome bowel resection should be combined with mesenteric revascularization. Resection of malperfused bowel should be done cautiously and should be followed automatically by second look operations. Special expertise and good team work of visceral and vascular surgeons are required to achieve better therapeutic results.

[Survey of therapy of deep venous thrombosis among members of the German Society of Vascular Surgery]

INTRODUCTION

In the literature of the past 15 years, deep venous thrombectomy has been rarely described. The only indications reported for thrombectomy seem to be recurrent pulmonary embolisation and phlegmasia coerulea dolens. Many contraindications and severe complications are making decisions concerning thrombolysis very difficult. At present, anticoagulation therapy is preferred over fibrinolysis. There is no conclusive concept for the standardization of treatment for deep venous thrombosis. As a first step towards achieving this, it was necessary to know what therapy is performed in hospitals throughout Germany.

METHODS

In 1999, we sent letters of enquiry to the members of the "Deutsche Gesellschaft für Gefässchirurgie". We wrote to 341 members (hospitals), and the information gained by means of a questionnaire was analysed and evaluated.

RESULTS

We received answers from 39.9% (n = 136) of the members. In all, 69% of the hospitals had an independent vascular department. In 1999, 6,718 patients underwent treatment for deep venous thrombosis, on average, 51 patients per hospital. Overall, 7,665 therapies were performed in one year (15.9% thrombectomy, 18.6% fibrinolysis, and 65.5% only anticoagulation). Only 23.5% of the hospitals had their own data about the outcome of their patients. The patency rate was 71.8% for thrombectomy and 48.9% for fibrinolysis. A severe postthrombotic syndrome was seen in 6.2% after thrombectomy, in 8.1% after fibrinolysis, and in 10.4% after singular anticoagulation.

CONCLUSION

At present, there is still no standardized concept for the treatment of patients with deep venous thrombosis. It seems that there are better results for some indications with thrombectomy than with other methods. For the establishment of a concept of treatment, a prospective randomised study is necessary.

[Aortoiliac reconstruction after kidney transplantation. Strategies to avoid ischemic damage of the transplant]

INTRODUCTION

The rising life expectancy of patients undergoing kidney transplantation and the improvement in the function rate of the allografts have led to an increasing number of patients suffering from arteriosclerosis-related diseases of the aortoiliac arteries. In these particular cases, an interruption of the blood supply of the allograft is always necessary for operative repair of the aortic and iliac arteries. This means a high risk of ischemic damage to the transplanted kidney.

PATIENTS AND METHODS

Between 1987 and 2000, 1,076 kidney transplantations were performed in our department. During this time, 14 reconstructive operations of the aortoiliac arteries were performed in 12 patients (6 women, 6 men, average age 55.2 (45-71) years). Operations were indicated in patients suffering from occlusive disease with imminent extremity or allograft loss, and symptomatic or asymptomatic aneurysms with a maximum diameter of more than 4 cm. In patients presenting with thoracoabdominal (1) and abdominal aortic aneurysms (3), protection of the transplanted kidney was performed by axilloiliac or axillofemoral bypass. Hypothermic flush-perfusion of the allograft containing PGE1 and heparin was performed in seven of nine operations for occlusive disease.

RESULTS

None of the patients presented with a permanent decrease in kidney function, six patients showed temporary creatinine elevation, and in nine patients creatinine levels at discharge were lower than they were preoperatively. None of the patients died.

CONCLUSION

Reviewing all reported methods of allograft protection, we recommend a three-step strategy including sequential clamp technique (ischemia < 30 min.), hypothermic flush-perfusion (ischemia < or = 60 min.), and temporary axilloiliac/femoral shunt (ischemia > 60 min), depending on the expected renal ischemia time.

Eurotransplant Senior Program 'old for old': results from 10 patients

More frequently there is the need for renal transplantation of older patients. Against the background of an increasing number of old donors and recipients, Eurotransplant Leiden started the Eurotransplant Senior Program (ESP) 'old for old' in 1999. The ESP works with donors and recipients both over 65 yr. The kidneys are transplanted with short cold ischaemia time regardless of the human leukocyte antigen (HLA) compatibility. Compatibility of blood groups, negative crossmatch and less than 5% cytotoxic antibodies are required. First experiences from 10 patients at Heinrich Heine University hospital are reported here. The course of 10 transplanted patients is described from January 1999 until November 1999 (28.4+/-15.8 wk). Age of donor and recipient, cause of dialysis and concomitant diseases from recipients, function of the transplanted kidney and complications are analysed. Immunosuppression consisted initially of cyclosporin A, mycophenolic acid and steroids. The results of these 10 patients were compared to 14 patients who were transplanted according to the ordinary Eurotransplant criteria (Eurotransplant Kidney Allocation System) in the same period of time. Kidneys from six donors (70.5+/-3.3 yr) were transplanted to 10 different recipients (66.9+/-2.2 yr). The control group consisted of 14 patients (47.6+/-14.4 yr) who received kidneys from 14 donors (48.3+/-10.1 yr). One double kidney transplantation was performed in the senior group, i.e. two kidneys from a marginal donor were transplanted to one recipient ('two in one'). In the ESP group, cold ischaemia time was reduced by 5 h and mean of HLA mismatches was more than doubled. Mean length of hospitalisation of ESP and control groups was 47.2+/-28.2 and 34.2+/-11.6 d, respectively. Intraoperatively, no complications were seen, post-operative care was performed on a normal ward. ESP patients suffered more often from delayed graft function, which led to further need for haemodialysis for 11.2 d. Finally, 9 of 10 patients acquired a satisfactory renal graft function. A total of 13 biopsies were performed in eight cases. Altogether seven acute rejections in 6 patients were found (four interstitial, one vascular, one interstitial+vascular, one clinical). The 9 patients with sufficient renal graft function were discharged with a mean serum creatinine level of 2.3+/-0.5 mg/dL (control: 1.9+/-0.8 mg/dL). Comparing these 10 recipients to a control group consisting of 14 patients, the results are comparable and encouraging. In conclusion, the short-term results of the ESP are promising. Nevertheless, the post-operative care requires more attention due to several complications. Though the HLA compatibility was not considered, all rejections were coped with effectively. Quality of life was improved.

Age-specific activities that support successful transition to adulthood for children with disabilities

Twenty-two activities that support transition to adulthood previously published by Blomquist et al. 1998) were explored in a focus group with parents of successful young adults with disabilities. Parents rated these activities on a 5-point Likert scale, and comments were gathered about the activities parents felt were essential for transition to adulthood. Parents rated the activities high with highest agreement being: "Do not do for them what they can do for themselves," "Assign appropriate household chores," and "Help children interact with others in varied settings." The lowest agreement ratings involved issues about school to work transitions, vocational programs within schools, and strategies assuring continuity of care with adult health care providers. Parents offered insights into the daily activities in school, home, and community that support transition to adulthood. Through review and understanding of these transition activities, health care professionals gain insight into the activities fostering a child's independence throughout their development.

Reference typing report for complement component C4

During the 7th Complement Genetics Workshop, Mainz, Germany, May 1998, a complement component C4 typing exercise took place with the aim of applying present technologies to the definition of reference C4 alleles/phenotypes and the recognition of nonexpressed (Q0) C4 alleles within expressed haplotypes. Eleven samples were submitted from 3 laboratories and tested by 14 participating laboratories with basic protein-typing technologies; in addition, each laboratory contributed data from local expertise. The samples were introduced to the reference typing for one or more characteristic allotype or for partial or total nonexpression of one isotype. The blinded samples were centrally evaluated and the results discussed among the participants at a plenum meeting. From the results, the samples could be classified into a group of common, easy to diagnose pheno-/allotypes, less common but still unanimously recognised variants, and a third group with difficult pheno-/allotypes. Within the latter group, the allotypes were either new (C4A '92'; C4B '93') and/or showed partial or total reversed antigenicity and unusual Rodgers/Chido (Rg/Ch) PCR subtypes (C4A '92'; C4A 12; C4B '35'; C4B '13'). Semiquantitative C4-alpha-chain estimates of relative isotype levels correlated well with the number of alleles seen at each locus by agarose gel electrophoresis, and were superior to other isotype quantitation methods. From the evaluation of the reference typing it was concluded that the recognition of rare, aberrant or hybrid C4 alleles with partial or total reversed Rg/Ch antigenicity or monoclonal reactivity is still difficult in most instances; besides isotype-dependent lysis, relative migration values, immunoblots with Rg- and Ch-specific monoclonal antibodies, Rg/Ch PCR typing, side-by-side comparison with already described allotypes will ultimately be required. The recognition of nonexpressed alleles within C4A and C4B expressed phenotypes remains the major obstacle in C4 genetic typing. Finally, a conclusive interpretation of DNA typing results will be achieved only in the context of complete allotyping results at the protein level, and at present cannot replace conventional protein allotyping.

An algebraic/graphical tool to compare ecosystems with respect to their pollution V: cluster analysis and Hasse diagrams

In case of large data matrices comparative evaluations of objects/regions with the technique of Hasse diagrams may be troublesome due to a messy system of lines in the graphical representation. Here fuzzy clustering leads to useful simplifications because regions with slightly different pollution pattern are grouped together. However, fuzzy clustering implies to introduce a threshold value for the membership of an object to a cluster and to select the best number of clusters. Therefore many arbitrarities evolve. Within the systematic study presented here we found that some objects are very stable against variations of the threshold value and the number of cluster whereas other objects behaves different. According to their behaviour we investigated a classification of the objects. Formal Concept Analysis shows that in some cases specific pollution pattern imply the membership to one of these classes. For example objects which are characterized by high Pb-, Zn-concentration and moderate S-concentration imply a high stability against variants of the clustering process. Further implications are described in the paper.

Surgical treatment of 50 carotid dissections: indications and results

PURPOSE

This article analyzes the course of 48 patients with 49 chronic carotid dissections (who were treated surgically at our institution after a median anticoagulation period of 9 months because of a persistent high-grade stenosis or an aneurysm) and the course of one additional patient with acute carotid dissection (who underwent early operative reconstruction 12 hours after onset because of fluctuating neurologic symptoms).

METHODS

All medical and surgical records and imaging studies were reviewed retrospectively. All histologic specimens were reevaluated by a single pathologist to assess the cause of dissection. Follow-up of 41 patients (85%) after 70 months (range, 1-190 months) consisted of an examination of the extracranial vessels in the neck by Doppler ultrasound scanning and a questionnaire about the patients' medical history and their personal appraisals of cranial nerve function.

RESULTS

Seventy percent of the dissections had developed spontaneously; 18% were caused by trauma; 12% of all patients (22% of the women) had a fibromuscular dysplasia. Indication for surgery was a high-grade persisting stenosis and a persisting or newly developed aneurysm. Flow restoration was achieved by resection and vein graft replacement in 40 cases (80%) and thromboendarterectomy and patch angioplasty in three cases (6%). Gradual dilatation was performed and effective in two cases (4%). Five internal carotid arteries (10%) had to be clipped because dissection extended into the skull base. One patient died of intracranial bleeding. Five patients (10%) experienced the development of a recurrent minor stroke (ipsilateral, 4 patients; contralateral, 1 patient). Cranial nerve damage could not be avoided in 29 cases (58%) but were transient in most of the cases. During follow-up, one patient died of unrelated reasons, and only one patient had experienced the development of a neurologic event of unknown cause.

CONCLUSION

Chronic carotid dissection can be effectively treated by surgical reconstruction to prevent further ischemic or thromboembolic complications, if medical treatment for 6 months with anticoagulation failed or if carotid aneurysms and/or high-grade carotid stenosis persisted or have newly developed.

[Controlled reperfusion of ischemic extremity musculature to prevent free radical induced lesions]

Tissue injury following reperfusion represents an essential problem of reconstructive vascular surgery. Pathogenetically toxic oxygen radicals are considered to play a pivotal role. Pharmacotherapeutical approaches are based particularly on antioxidants and vasodilators. However, a standardized regimen is not yet clinically introduced. In 48 adult Lewis-rats lower limb ischemia was induced by aortal cross-clamping. Following 3.5 hours of ischemia intravascular flushing perfusion via the distal aorta with a heparinized electrolyte solution (group B). Group C received additionally oxypurinol, group D alprostadil and group E sodium selenite into the flushing solution. At 4 hours recirculation was established. After 10 min, 30 min and 24 hours of reperfusion we determined lactate, creatine kinase, lactate dehydrogenase, urea, malondialdehyde and the laser Doppler flux. At the end of the experiments biopsies were taken from M. tibialis anterior. In comparison to control animals (group A) we observed an attenuation of reperfusion injury in the groups treated with flushing perfusion. Free oxygen radical reactions measured by malondialdehyde release were significantly reduced (30 min: A-209.1 +/- 45.4, B-127.3 +/- 36.9, C-113.2 +/- 14.1, D-99.6 +/- 24.5, E-123.6 +/- 11.2 mmol/l, p < 0.05). The laser Doppler flux measurements corresponded with the biochemical analyses (30 min: A-52.4 +/- 11.1, B-48.0 +/- 11.0, C-72.6 +/- 12.0, D-74.4 +/- 13.3, E-62.6 +/- 10.8% of baseline). Histologically, treatment with alprostadil (PGE1) and oxypurinol revealed superior results. Standardized intraarterial flushing perfusion with antioxidants and vasodilators reduces reperfusion injury. Clinical trials are urgently required to confirm the experimental findings and to optimize the therapy of extremity ischemia/reperfusion injury in humans.

[Aortic aneurysm in horseshoe kidney--special diagnosis and therapy]

The co-existence of horseshoe kidney (HSK) and abdominal aortic aneurysm (AAA) is rare and demands a special diagnostic workup and a meticulous surgical procedure. Ten patients with HSK associated with AAA are reported. All underwent aortic replacement with successful preservation of multiple renal arteries. One patient died at the 7th postoperative day from myocardial infarction. HSK does not represent a contraindication for aortic repair. Angiography for identification of aberrant renal arteries and classification into three types for surgical management is mandatory. In type I and II we recommend a standard midline transperitoneal approach. Only in type III does a thoraco-abdominal approach seem favourable. The aortic reconstruction should be performed with tube grafts, if possible. Aberrant renal arteries are reattached directly to the prosthesis. Dissection of renal isthmus should be avoided. Temporary cold renal perfusion is indicated to extend the ischemic tolerance time. As repair of a ruptured AAA in patients with HSK may be quite difficult and time consuming, we recommend more liberal indications for aneurysm surgery in patients with HSK.

[Vascular surgery operations in tumor diseases]

In a retrospective analysis covering 10 years, we examined 53 patients with malignant tumors, who had undergone 74 vascular reconstructive operations. The rate of all complications was 40%. Thirty-two patients died within a period of 3.1 years because their tumor progression; the survival rate after an average of 6.9 years was 65.6%.