AneuRx Device Migration: Incidence, Risk Factors, and Consequences

Success after endovascular abdominal aortic aneurysm repair (EVAR) is dependent on device positional stability. The quest for such stability has motivated different endograft designs, and the risk factors entailed remain the subject of debate. This study aims at defining the incidence, risk factors, and clinical implications of device migration after EVAR with the AneuRx® endograft. In this study we included all consecutive 109 patients submitted to primary AneuRx placement for infrarenal aortic or aortoiliac aneurysms. Preoperative computed tomography (CT) scans were reviewed for the following anatomic characteristics: neck length, diameter, angulation, calcification, and thrombus load; and sac diameter and thrombus load. Percentage of device oversizing relative to the proximal neck diameter was determined. All postoperative CT scans were reviewed, and the distance between the lowest renal artery and the craniad end of the device was measured. A 5-mm increase in such distance was considered indicative of device migration. Migration cumulative incidence was estimated by the Kaplan-Meier method, and its association with any of the preoperative anatomical characteristics was tested using Cox proportional hazards models. Median follow-up time was 9 (range, 1-31) months. Migration occurred in nine patients, corresponding to a 15.6% estimated probability of migration at 30 months (SE=5.1%). Migration was associated with the risk of proximal type I endoleak (hazard ratio=3.39, 95% confidence interval=1.46-7.87; p=0.007). This type of endoleak occurred in three of the migration-affected patients (33.3%); all of them were resolved by additional cuff placement at the proximal landing zone. No other migration-related reinterventions were performed. The only significant associations between anatomic factors and device migration probability were the protective effects of longer necks (odds ratio [OR]=0.71 for each additional 5 mm, p=0.045) and longer overlapped portions of neck and device (OR=0.56 for each additional 5 mm, p=0.003). There was a trend toward higher probability of migration among reverse-tapered necks (OR=1.75, p=0.109). Percentage of device oversizing correlated with early neck dilation (between preoperative and first postoperative diameters, correlation coefficient=0.4, p < 0.0001), but not with late neck dilatation (between first postoperative and 1.5-year scan diameters, correlation coefficient=0.29, p=0.112). There was a trend toward higher mean percentage of late dilation among migrators (11.4%, standard error of the mean [SEM] 2.6) than nonmigrators (5.7%, SEM=1) (p=0.08), but both groups had similar mean percentages of early dilation (3%, SEM=1.6%, vs. 5.5%, SEM=0.6%; p=0.365). This result indicates that device migration is not a rare event after AneuRx implantation. This phenomenon is associated with proximal type I endoleaks. Deployment of the endograft immediately below the renal arteries might help to prevent migration, since use of greater lengths of overlapped device relative to the proximal neck has a protective effect. Migration seems to be independent of the degree of device oversizing.Presented at the 29th Annual Meeting of the Peripheral Vascular Surgery Society, Anaheim, CA, June 4-5, Sergio M. Sampaio is a recipient of the Edward S. Rogers Clinical Research Fellowship in Vascular Surgery.     

The distribution of extracellular matrix vesicles in healing of rat tibial bone three days after intramedullary injury

Summary The distribution of extracellular matrix vesicles on the third day of bone healing was studied by morphometric analysis of transmission electron micrographs. Detection and grouping of the vesicles was performed according to type, diameter, and distance from the calcified front. The different types were selected as follows: vesicles with electron-lucent contents (empty), vesicles with amorphous electron-opaque contents (amorphic), vesicles containing crystalline depositions (crystal), and vesicles containing crystalline structures with ruptured membranes (rupture). The majority of vesicles were between 0.07 µm and 0.12 m in diameter and were located at less than 3 m from the calcified front. The distribution of the empty, amorphic, crystal, and rupture vesicles was 23.2%, 74%, 2.5%, and 0.3% respectively. Their sequence of arrangement according to diameter was as follows: empty, amorphic, crystal, and rupture, the empty vesicles constituting the smallest and the rupture the largest type. Distances from the calcified front were similar for the empty, amorphic, and crystal vesicles, while the rupture type was located nearest to the front. The present observations support the widely acknowledged hypothesis on the role of extracellular matrix vesicles in mineralization. It is thought that the secretion of empty vesicles from the cell is followed by intravscular accumulation of amorphous Ca and Pi to form a hydroxyapatite crystal that, in turn, ruptures the vesicle's membrane. The maturation process is accompanied by an increase of the vesicular diameter and its approximation to the calcifying front.     

Increased urinary albumin indicating urothelial leakage following intravesical bacillus Calmette-Guérin therapy for superficial bladder cancer

Summary This study on the increase in albumin in the urine of patients with superficial bladder cancer after intravesical bacillus Calmette-Guérin (BCG) treatment was initiated on the basis of two facts. First, extravasation of serum albumin could be expected as a result of the BCG-induced delayed-type hypersensitivity reaction in the bladder wall. Second, appearance of albumin in the urine was a possibility as cytokines also appear in the urine, although probably after being produced suburothelially by infiltrating leukocytes. Albumin and the cytokines interleukin (IL) 1, IL2, IL6, and tumor necrosis factor alpha (TNF) were determined in urine from 20 patients treated with 6 weekly intravesical BCG instillations, collected prior to each instillation and 2, 4, 6, 8, 12, and 24h thereafter. The mean concentration of albumin in pre-therapy specimens was 112±118 (range 2–432) g albumin/ml urine, approximating 14±14 g/ mol creatinine (creat) (n=15), which was comparable to the mean pre-instillation value of 16±32 g/mol creat (n=96). A significant increase in urinary albumin during the 6 weeks of BCG treatment was observed (P<0.001). However, a large variation existed between individual patients and in some patients no reaction was seen. Maximum albumin concentrations were observed after instillations 3–6. A significant correlation between albumin and concentration of the cytokines IL1, IL2, IL6, and TNF was found (P<0.01), correlation coefficients (r) being 0.56, 0.56, 0.67, and 0.71 (n=418), respectively. During the first 24h after instillation cytokines and albumin peaked in the following order: TNFIL2albuminIL6IL1. TNF peaked most frequently after 2–4h and IL1 after 6h, while IL2, albumin, and IL6 peaked between these time points. In conclusion, the presence of albumin in urine indicates a leakiness of the bladder wall after repeated BCG instillations. Since albumin was shown to be stable in urine and the assay is relatively simple and cheap, it may be performed in most hospitals. This will allow largescale investigations of the correlation between elevation of urinary albumin and (tumor) response on BCG therapy.     

Suppression of proliferative cholangitis in a rat model by local delivery of paclitaxel

Background. Proliferative cholangitis (PC) leads to biliary stricture, which is the main cause of hepatolithiasis, recurrent cholangitis, and biliary cirrhosis. The aim of this study was to determine whether local delivery of paclitaxel, which inhibits cell proliferation by overstabilization of microtubules, prevents PC in a rat model.Methods. PC was induced by introducing a fine nylon thread into the bile duct in a rat. Paclitaxel (100µl of 10, 100, and 1000µmol/l) or solvent vehicle was administered into the bile duct for 15min. One week after treatment, histopathologic examination and 5-bromodeoxyuridine (BrdU) labeling of the bile duct were performed.Results. In comparison with the control, the mean thickness of the bile duct was reduced by 29% in the 1000µmol/l paclitaxel-treated group (2.61 ± 0.31µm vs 3.67 ± 0.25µm, P 0.05). The luminal area increased (P 0.0001) and the grade of epithelial–glandular proliferation was decreased (P 0.01) as the dose of paclitaxel increased. Ductal fibrosis and inflammatory cell infiltration were similar in both groups. The BrdU labeling index was significantly lower in the paclitaxel-treated group (P 0.05).Conclusions. Local delivery of paclitaxel suppressed PC in a rat model by the inhibition of epithelial–glandular proliferation and may offer an effective therapeutic option for biliary stricture.     

173. Tierexperimentelle Ergebnisse mit einem voll implantierbaren Distraktionsgerät zur operativen Beinverlängerung

Zusammenfassung Zur operativen Beinverlängerung wurde ein neues Femur-Distraktionsgerät entwickelt. Das Gerät besteht aus einem elektronisch programmierbaren Distraktionsaggregat einschließlich Kraftquelle und einer zweiteiligen Führungsschiene. Das Gesamtsystem ist voll versenkbar und schafft Übungsstabilität während der Distraktionsphase. Die Funktionen Vorlauf — Stop —Rücklauf können transcutan induktiv gesteuert werden. Ein für das Tierexperiment speziell entwickelter Prototyp des Gerätes wurde an Schafen erfolgreich erprobt.     

Role of endogenous interferon gamma in murine tumor growth and tumor necrosis factor alpha antitumor efficacy

Background: The anticancer role of tumor necrosis factor-alpha (TNF-) has been limited by toxicity. These experiments evaluate blocking endogenous interferon-gamma (IFN-) activity to abrogate TNF- toxicity. Methods: C57Bl/6 mice bearing MCA 105 tumor were treated with TNF- and anti-IFN- antibody (Ab) to evaluate the effect on the acute lethality of TNF- and their efficacy as evaluated by tumor growth rate, tumor histology, and survival. Results: Anti-IFN- Ab decreased TNF- lethality. Anti-IFN- Ab alone increased tumor growth significantly more than did nonimmune IgG (p₂<0.0001). Tumor-bearing mice that received nonimmune IgG and TNF- had slower tumor growth (p₂<0.02) and a trend toward improved survival (p=0.07) compared with saline-treated controls. Anti-IFN- Ab abrogated the antitumor effect of TNF-, prevented acute tumor necrosis histologically, and resulted in tumor growth rate and host survival similar to that of controls. The findings in mice that received anti-IFN- Ab and high-dose TNF- were comparable with those in mice that received a lower, equitoxic dose of TNF- alone. Conclusions: Blocking endogenous IFN- accelerates tumor growth in this model and partially abrogates the toxic and antitumor activity of exogenous TNF- equally. This suggests that blocking endogenous IFN- activity is not a useful strategy for limiting TNF- treatment toxicity.Presented in part at the 45th Annual Cancer Symposium of The Society of Surgical Oncology, New York, New York, March 15–18, 1992.     

Hospital Readmissions Following Abdominal Aortic Aneurysm Repair

In-hospital outcomes associated with abdominal aortic aneurysm (AAA) repair are well described. However, little is known about post-discharge readmission rates, lengths of stay, associated mortality, and costs. We examined 206 consecutive patients who underwent AAA repair at two American hospitals between 1998 and 2000. Index hospitalization and 6-month readmission data were extracted from a resource and cost accounting system used by both hospitals. Among the 206 patients, 183 survived until discharge (mortality rate 11.2%). Among the surviving patients, 38 (21.0%) were readmitted within 6 months. Half of the readmissions occurred within two weeks of discharge, with patients presenting with a diverse array of complications. Nonelective repair and diabetes mellitus were independent predictors of hospital readmission (OR=2.83, 95% CI=1.25-6.40, p=0.01; OR=6.60, 95% CI=1.02-42.4, p=0.047, respectively). For each readmission, the mean length of stay was 10.7±2.5 days and the mean cost was $13,397±3,381. The cumulative number of hospital days during the 6 months post-discharge was 17.7±3.5 days for each readmitted patient and the mean per-patient total cost was $23,262±5,478. The mortality rate among readmitted patients was 13.2%. Overall, readmissions following AAA repair accounted for a cost >50% over and above the cost of the readmitted patients index hospitalization. Hospital readmissions are common during the 6 months following AAA repair. Patients who are readmitted experience long lengths of stay and high mortality rates, and their care incurs high costs.Dr. Eisenberg is a Physician-Scientist of the Quebec Foundation for Health Research. Dr. Pilote is a Physician-Scientist of the Canadian Institutes for Health Research.     

Altered Integrin Expression and the Malignant Phenotype: The Contribution of Multiple Integrated Integrin Receptors

The integrins are a family of cell surfaceadhesion receptors that mediate adhesion to eithercomponents of the extracellular matrix or to othercells. The ₁ family of integrinsrepresent the major class of cell substrate receptors withspecificities primarily for collagens, laminins, andfibronectins. The role of the integrin family of cellsurface adhesion receptors in normal mammary glandmorphogenesis and the contributions of altered integrinreceptor expression to the invasive and metastaticphenotype have been the primary focus of our lab, aswell as a number of other laboratories. The_{2 1} integrin is expressed at high levels by normaldifferentiated epithelial cells including those of thenormal breast. Using breast cancer as a model, weevaluated changes in integrin expression in malignancy. We and other investigators made the keyobservation that _{2 1}integrin expression is decreased in adenocarcinoma ofthe breast in a manner that correlates with the stage ofdifferentiation. Studies of other adenocarcinomas have yielded similarresults. When the _{2 1}integrin was reexpressed in a poorly differentiatedmammary carcinoma that expressed no detectable₂ integrin subunit, a dramatic reversion of malignant phenotype to adifferentiated epithelial phenotype was observed,indicating a critical role for₂₁ expression inmammary gland differentiation. Other laboratories using monoclonal antibodies to competitivelyinhibit _{2 1} integrinadhesion or oncogenic transformation using c-erb2 haveconfirmed the important role of that ₂₁ integrin in mammary gland morphogenesis. Re-expression of the_{2 1} integrin alsoresults in upregulation of both the ₆and ₄ integrin subunits. To determinethe contribution of enhanced ₆ and₄ integrin expression to the abrogation of the malignantphenotype by _{2 1}integrin expression, we have now separately re-expressedthe human ₆ or ₄integrin subunit in the breast cancer model.     

Beneficial Effects of Apolipoprotein A-I on Endotoxemia

Purpose. Although many studies have shown the beneficial effects of lipoproteins on animals with endotoxemia, little is known about the impact of apolipoprotein A-I (apoA-I) on tumor necrosis factor (TNF-) release in response to lipopolysaccharide (LPS). The present study was conducted to determine whether the administration of apoA-I inhibits the release of TNF- and influences the survival rate of rats with endotoxemia.Methods. Forty male Wistar rats were divided randomly into four groups. Rats in the first and second groups were given 1mg/kg LPS intraperitoneally (i.p.) and blood was collected 1h later to measure the serum levels of TNF-. Either 10mg/kg apoA-I or Tris-buffered saline was injected i.p. and the serum TNF- levels were measured again 2h later. Rats in the third and fourth groups were given 5mg/kg LPS. Following the administration of 10mg/kg apoA-I or Tris-buffered saline, animals were observed for 5 days and survival rates were determined.Results. ApoA-I inhibited the release of serum TNF- and improved the survival rates of rats with endotoxemia.Conclusion. The administration of apoA-I suppressed the TNF- release in endotoxemia and decreased the mortality rates of rats.     

Differentiation of pancreatic ductal carcinoma cells associated with selective expression of protein kinase C isoforms

Background: The signal transduction pathways important in regulating the growth and differentiation of malignant cells are poorly understood. Recent evidence has implicated activation of the protein kinase C (PKC) family of signaling proteins in pancreatic carcinoma during cytokine-induced cytostasis and differentiation. Methods: A human pancreatic adenocarcinoma (HPAC) cell line was exposed to tumor necrosis factor- (TNF-; 40 ng/ml) for 6 days. Cytostasis and viability were confirmed by daily MTT [(3(4,5)-dimethyl-thiazol-2-yl) 2,5-diphenyl-tetrazolium bromide] and trypan exclusion assay. Protein fractions were isolated daily and subjected to immunoblot analysis for the normal (terminally differentiated) pancreatic ductal cell marker carbonic anhydrase II (CA II) as well as specific PKC isoforms (, , , , and). Results: Growth arrest occurred in HPAC cells after exposure to TNF- for 48 h, with viability maintained above 90% throughout the 6-day time course. CA II immunoreactivity was not detected in untreated controls but appeared after 2 days of TNF- exposure, peaking on day 6. Concurrently, TNF- induced the selective downregulation of PKC-, whereas PKC- levels increased. PKC- and PKC- immunoreactivity did not change. The atypical PKC- isoform developed a doublet banding pattern in response to TNF-, although overall PKC- levels did not change. Conclusions: TNF--induced growth arrest and differentiation in HPAC cells is associated with the selective downregulation of PKC- and upregulation of PKC-.Presented at the 48th Annual Cancer Symposium of The Society of Surgical Oncology, Boston, Massachusetts, March 23–26, 1995.     

Rodent Osteoblastic Cells Express Voltage-Sensitive Calcium Channels Lacking a γ Subunit

Voltage-sensitive calcium channels (VSCC) open in response to external stimuli, including calcitropic hormones, that alter plasma membrane calcium (Ca²⁺) permeability. Ca²⁺ that enters the cell through these channels serves a second messenger function, eliciting cellular responses that include secretion and changes in gene expression. In osteoblasts, VSCCs serve as key regulators of Ca²⁺ permeability and are a major class of calcitropic hormone-sensitive Ca²⁺ channels present in the plasma membrane. The members of the VSCC family exist as a complex of polypeptide subunits that are comprised of a pore-forming ₁ subunit, an intracellular subunit, a dimer of disulfide-linked ₂ and subunits, and in some tissues, a subunit. Previous studies in our laboratory have shown that the major functional ₁ subunit present in osteoblasts is the _1C (Ca_V1.2). To determine the complement of auxiliary subunits present in rodent osteoblastic cells, we employed RT-PCR using a battery of subunit specific primers and appropriate tissue controls. Immunohistochemistry also was performed, using available subunit specific antibodies, to measure protein expression and localization. Cell types examined included MC3T3-E1 at various stages of differentiation, ROS 17/2.8 osteosarcoma, and primary cultures of rat calvarial osteoblasts. The results indicate that all cells expressed multiple subunit classes and ₂ dimers, but no subunits, regardless of differentiation state. We propose a structure for the functional osteoblast VSCC that consists of ₁, , ₂ subunits and is devoid of a subunit.     

Usefulness and limitations of colonoscopy in a proctological clinic

Summary Colonoscopy is a superior diagnostic tool for the detection of cancer of the colon. Its limitations include that it is not always available and there is a great deal of discomfort for the patient. It should therefore be used as effectively as possible. The goal of this retrolective cohort study was to analyze the usefulness of colonoscopy, especially by relating it to the subsequent therapeutic impact. Indication-related groups included rectal bleeding, other symptoms suggestive of malignancy, and follow-up. In 714 patients selected as a result of admission to the proctological unit of our surgical clinic, a carcinoma was discovered in 9% and an adenoma in 13.4%. Patients with rectal bleeding were found to benefit most from colonoscopy since active therapeutic management followed in 56% of the cases. On comparison, there was a direct therapeutic impact in only 10% of the colonoscopies performed for follow-up. Identification of additional factors such as mucosal proliferation markers may help to improve the efficiency of endoscopy by more specifically designating the populations at risk for colonic neoplasia.     

The reducing end of αGal oligosaccharides contributes to their efficiency in blocking natural antibodies of human and baboon sera

Synthetic galactosyl oligosaccharides were tested for their ability to inhibit the cytotoxic reaction of human and baboon natural antibodies on PK15 cells in culture. Methyl--Gal gave weak inhibition, Gal1-3Gal substantially inhibited the reaction (400 M), and Gal1-3Gal2-4GlcNAc was ten times more efficient (30 M). The modification from to anomeric configuration of the nonreducing end resulted in a complete loss of activity, while substitutions at the reducing end induced only a partial loss of activity. These observations suggest that natural anti-Gal antibodies recognize the epitope from its nonreducing end, but that substitutions at the reducing terminus can modify the antibody-binding capacity. Modified tri- and tetrasaccharides are better inhibitors than the disaccharide but not as good as Gal1-3Gal1-4GlcNAc. The reducing terminus therefore contributes some energy to the reaction, indicating that certain oligosaccharides will be of more potential clinical use than others.     

34. Akute und chronische Pankreatitis. Morphologische Grundlagen

Zusammenfassung Die akute Pankreatitis zeigt mit der jauchigen Nekrose und der Vielfalt der Fettgewebsnekrosen ein eindrucksvolles Bild. Dennoch sind einige Teilaspekte wenig bekannt und für das Verständnis der Krankheit wichtig, z. B. die häufige Aussparung des Kerns der Drüse. Die anatomischen Äquivalente von Schock, Schmerz, Ileus werden erläutert, auf das Krankheitsbild Pankreatitis ohne Pankreatitis wird kurz eingegangen. Als Komplikationen werden die Chronifizierung und die Pseudocysten dargestellt. Die chronische Pankreatitis bis zur ausgebrannten Drüse mit Stein, Diabetes und möglicherweise Carcinom wird in ihrer Entstehung anatomisch gezeigt.

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Fundamental morphological aspects of acute and chronic pancreatitis

Summary Acute pancreatitis presents an impressive picture, with autodigestic necrosis and various types of necrosis of fat tissue. Nevertheless, some side aspects are little known, although they are important to the understanding of the disease, e.g. the frequent sparing of the kernel of the gland. The anatomical equivalents of shock, pain, ileus are exvlained, and the syndrome of pancreatitis without pancreatitis will be briefly discussed. The complications of progression to a chronic state and of pseudocysts will be shown. The development of chronic pancreatitis leading to the burnt out gland with stones, diabetes and possibly carcinoma will be shown anatomically.

     

Transforming growth factor-beta localization during mouse prostate morphogenesis and in prostatic growth abnormalities

Summary Growth and morphogenesis of the prostate involves mesenchymal-epithelial interactions. Transforming growth factor-beta 1 (TGF-1) is one growth factor that may play a role in these paracrine interactions. We have localized TGF-1 by molecular and immunohistochemical analysis in the developing mouse prostate. Accumulations of TGF-1 protein were localized in the mesenchyme surrounding ductules in fetal and neonatal prostate. Previous studies in the mouse prostate reconstitution (MPR) model system have localized accumulations of TGF-1 to regions of oncogene-induced abnormalities. In surgically excised adult human prostate tissues, localized accumulations of TGF-1 are associated with prostate cancer and benign prostatic hyperplasia (BPH). Intracellular TGF-1 was more often associated with stromal cells in BPH and with neoplastic epithelial cells in prostate cancer. The production and accumulation of TGF-1 appears to involve interactions between mesenchymal and epithelial cells. Further experimental studies may clarify the relationships between TGF-1 and abnormal prostatic growth.     

82. Fragen der chirurgischen Weiterbildung: Gegenwärtiger Stand

Zusammenfassung Weiterbildung — die Einführung eines approbierten Arztes in ein anerkanntes Fachgebiet — ist im Begriff und System von Ausbildung (des Studenten) und lebenslanger Fortbildung (des fertigen Arztes) zu unterscheiden. Sie schafft das Fundament, auf dem sich Wissen und Können der Angehörigen einer Disziplin aufbauen, und setzt damit Wertmaßstäbe im eigenen Land und über die Grenzen hinaus. Weiterbildungsordnung (WO) und als Richtlinien bezeichnete Ausführungsbestimmungen regeln den Ablauf der Weiterbildung (W). Neu ist im wesentlichen die Verlängerung der Weiterbildungszeit von 5 auf 6 Jahre, die Einführung von Teilgebieten (in der Chirurgie Teilgebiet Kinder-Chirurgie und Teilgebiet Unfall-Chirurgie) mit dem Ziel, abgerundeten Subspezialitäten im Rahmen des Gesamt-Fachgebiets eine Autonomie zu geben, sowie ein umfangreicher Operations-Katalog. Die WO ist damit richtungweisend für die weitere Entwicklung des Fachgebietes und begründet erhebliche Anforderungen sowohl an den Facharzt-Aspiranten als auch an den Erfahrenen, der die W leitet. Die Einführung eines Befähigungsnachweises als einer in der ausschließlichen Kompetenz der ärztlichen Selbstverwaltung gelegenen Abschlußkontrolle wird befürwortet.

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Summary Postgraduate medical education in an approved specialty by definition and set-up differs from both undergraduate medical education and the life-long continuing medical education after completion of training. Postgraduate education in medicine is the basis for the knowledge and proficiency of a specialist and sets standards at home and abroad. Postgraduate education is laid down in principle in the Weiterbildungsordnung and regulated by the Richtlinien. Major innovations are a prolongation of training from 5 to 6 years, the introduction of subspecialties (pediatric surgery, traumatology), in order to give these established groups autonomy within the field of surgery and finally a sizable list of operations to be performed. The new Weiterbildungsordnung will guide the future development of surgery and imposes demands both on those in training and those responsible for it. An examination as "proof of competence"' is recommended, but should remain within the competence of the medical profession.

     

The choice of treatment after incomplete adenomectomy in acromegaly: Proton- versus highvoltage radiation

Summary The authors report the results of a study designed to compare the effectiveness of two different types of radiation in patients with acromegaly where surgical therapy had failed to normalize growth hormone (GH). Longterm follow-up after conventional high voltage radiation in 17 patients and proton therapy in 13 patients confirmed a similar reduction of GH levels in both groups. After 4.5 years a decrease of about 80% was achieved. After conventional radiation GH was normal in 8 (47%) and near normal in 6 (35%) while proton therapy resulted in normalization in 5 and improvement in 5 (38%).The slightly better results of conventional radiation must be attributed to lower pretreatment levels of GH. Side effects as additional pituitary deficits and oculomotor palsies were more often seen after proton treatment. Since the results of both radiation methods are similar and proton therapy has a tendency to more serious side effects we recommend conventional radiation as secondary treatment of acromegaly.This work represents part of a doctoral thesis by Barbara Lutz, M.D.     

Combined effects of Inversed Ratio Ventilation (IRV) with positive end-expiratory pressure ventilation (PEEP) on cardiorespiratory function in acute respiratory failure

Combined effects of inversed ratio ventilation (IRV) with positive end-expiratory pressure (PEEP) on cardiorespiratory function were examined in 24 patients with acute respiratory failure. Patients were divided into two groups: the IRV group (n = 12) who showed no significant increase in Pa_{O 2} with a 6cmH₂O of PEEP and PEEP group (n = 12) who were ventilated mechanically with PEEP only at maximum level of 10cmH₂O. In IRV group step-wise prolongation of the I:E ratio from 1:1.9 to 2.6:1 or 4:1 was applied as a Pa_{O 2} was improved and in PEEP group also level of PEEP was increased from 0, 5 to 10cmH₂O after one hour period irrespective of Pa_{O 2}. Inversed ratio ventilation and PEEP increased significantly Pa_{O 2}/Fi _{O 2}, the increase being observed 6hrs (I:E = 2:1) and 2hrs (10cmH₂O) after starting IRV or PEEP. Further improvement of oxygenation was not observed in IRV even if I:E ratio was prolonged up to 2.6:1 or 4:1. These results suggested that combinations of IRV with PEEP were effective and an I:E ratio of 2:1 may be optimal, and IRV is advantageous compared to PEEP, but will take more long time to improve oxygenation than PEEP.(Sari A, Toriumi T, Yamashita S, et al.: Combined effects of inversed ratio ventilation (IRV) with positive end-expiratory pressure ventilation (PEEP) on cardiorespiratory function in acute respiratory failure. J Anesth 5: 105–113, 1991)     

Changes of local brain tissue oxygen pressure after vasopressin during spontaneous circulation

Summary. Background. Brain tissue oxygen pressure (PbtO₂) correlates to cerebral blood flow (CBF) during spontaneous circulation, with one important regulator being nitric oxide (NO). Although it is established that arginine vasopressin (AVP) improves CBF and global cerebral oxygenation during cardiopulmonary resuscitation, it is unknown whether similar beneficial effects are present during spontaneous circulation. The purpose of this study was to investigate the effects of AVP with and without pre-treatment with the NO synthase inhibitor N-omega-nitro-L-arginine methyl ester (L-NAME) on local brain tissue oxygenation in a beating heart model.Methods. Following approval of the Animal Investigational Committee, nine healthy piglets underwent general anaesthesia, and were instrumented with a probe in the cerebral cortex to measure PbtO₂. Each animal was assigned to receive AVP (0.4U·kg^–1), and after a wash-out period, L-NAME (25mg·kg^–1 over 20min) followed by AVP (0.4U·kg^–1). After each AVP administration, nitroglycerine (25µg·kg^–1 over 1min) as a NO donor was infused to test the vascular reactivity independently from NOS inhibition.Findings. Three minutes after administration of AVP, PbtO₂ increased significantly (P<.05; mean±SEM, 31±11 versus 43±14mmHg, +39%), compared with baseline. After pre-treatment with L-NAME, the changes of PbtO₂ after AVP were not significant (32±11 versus 28±10, –13%) when compared with the baseline.Conclusion. In this beating heart porcine model, local brain tissue oxygenation was improved after AVP alone, but not after inhibition of NO synthesis with L-NAME.