Conditioning hypoxia causes protection against ischemia in the CA 1-region of hippocampal slices

PURPOSE: At present the mechanisms of ischemic or hypoxic tolerance are not fully understood at the cellular level. METHODS: In order to further characterize the effects of conditioning hypoxia on the synaptic transmission in the hippocampal area CA1, rats were exposed to a moderate normobaric hypoxia for 8 h. Transverse hippocampal slices were prepared 1, 7 or 14 days after this conditioning hypoxia and evoked field potentials were recorded in the CA 1 region upon stimulation of the Schaffer collaterals before, during and up to 4 h after ischemia in vitro (hypoxia and reduced glucose). RESULTS and CONCLUSIONS: The time to disappearance of the evoked potential during ischemia was significantly prolonged after seven, but not after one or 14 days in slices taken from conditioned animals. In addition the input/output (I/O) curves of evoked potentials were not altered 4 h after the ischemia. In contrast, the time to disappearance of the evoked potentials was shorter and the I/O curves were diminished in slices from control animals. Possible mechanisms of the protective effect are discussed.     

An indirect method for the estimation of osteoporotic fractures from injury and fracture profiles

Summary Study objective was to develop a valid epidemiological method for the estimation of osteoporotic fracture risk, using administrative databases and accounting for variable baseline risks of injury. Design is the secondary analysis of inpatient and outpatient utilization data. A baseline injury risk was estimated by the incidence of primary utilization of medical services for soft tissue injuries (ICD-9 diagnostic codes 910–929), and the risk profile was compared after normalization with the overall primary utilization rate for fractures (ICD-9 diagnostic codes 800–829). The setting is a county with approximately 100,000 inhabitants in the former East Germany. Participants were all inhabitants of the county who had a physician contact (inpatient or outpatient) during 1987–1988, as well as hospital inpatients for all of Germany in 1989. The number of fractures increased with age, especially in women, when compared to the number of fractures expected from the incidence of soft tissue injury. Similar patterns were identified in hospitalization data from East and West Germany. Estimating the prevalence of osteoporosis directly from certain osteoporotic fracture types associated with higher age is potentially biased, since it neglects the underlying risk of injury. Our model distinguished the osteoporotic fracture risk as the excess risk over an expected injury-related fracture risk for a given age and sex, and may allow a more valid quantification of osteoporotic fractures in different populations.

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Zusammenfassung Studienziel war die Entwicklung einer validen Methode zur Abschätzung des osteoporotischen Frakturrisikos unter Verwendung administrativer Daten und unter Berücksichtigung eines variablen Hintergrundrisikos für Unfälle. Studiendesign ist die sekundäre Analyse von Daten zur stationären und ambulanten Inanspruchnahme. Das Hintergrundrisiko für Unfälle wurde aus der Inzidenz der primären Inanspruchnahme der medizinischen Versorgung für Weichteilverletzungen (ICD-9 Kodierungen 910–929) geschätzt, und das Risikoprofil nach Normalisierung mit der allgemeinen primären Inanspruchnahme wegen Frakturen (ICD-9 Kodierungen 800–829) verglichen. Studienort war ein Landkreis mit etwa 100 000 Einwohnern in der ehemaligen DDR. Studienteilnehmer waren alle Einwohner des Kreises, welche 1987–1988 einen ambulanten oder stationären Arztkontakt hatten, sowie Krankenhausfälle in beiden deutschen Staaten im Jahr 1989. Die Anzahl der Knochenbrüche nahm mit dem Lebensalter zu, vor allem bei Frauen, verglichen mit der Anzahl, welche aus der Inzidenz der Weichteilverletzungen zu erwarten gewesen wäre. Ein ähnliches Muster war bei den Krankenhausfällen in Ost- und Westdeutschland zu beobachten. Die direkte Schätzung der Prävalenz der Osteoporose aus bestimmten osteoporotischen Frakturtypen, welche mit dem höheren Lebensalter verbunden sind, enthält potentiell einen systematischen Fehler, da ein Hintergrundrisiko für Unfälle vernachlässigt wird. Unser Modell identifiziert ein osteoporotisches Frakturrisiko als überschiessendes Risiko über ein nach Alter und Geschlecht zu erwartendes unfallbedingtes Frakturrisiko, und erlaubt potentiell eine validere Quantifizierung osteoporotischer Frakturen in verschiedenen Populationen.

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Résumé L'objective de la recherche était le développement d'une méthode valide pour l'estimation du risque d'une fracture ostéoporotique, utilisant données administratives et tenant compte des risques basales variables concernant les accidents. Le désigne de l'étude est l'analyse secondaire des données hospitalières et ambulatoires. Le risque basale des accidents fut estimé par l'incidence de l'utilisation première des services médicaux pour des blessures non-skeletals (ICD-9 codes 910–929) et cette risque fut comparé après normalisation avec la rate d'utilisation pour des fractures (ICD-9 codes 800–829). La recherche se concentrait sur un département de l'Allemagne de l'Est avec a peu près 100000 habitants. Les participants étaient tous les habitants du département qui avaient un contact avec un médecin (a l'hôpital ou ambulatoire) pendant les années 1987–1988, ainsi que tous les cas hospitalisés dans toute l'Allemagne en 1989. Le nombre de fractures augmentait avec l'âge, en particulier parmi les femmes, comparé avec le nombre attendu de l'incidence des blessures. Des profils de risque pareils ont pu être observés parmi les cas hospitalisés de l'Allemagne de l'Ouest et de l'Est. L'estimation directe de la prévalence de l'ostéoporose a la base de certains types «ostéoporotiques» des fractures, associés avec le troisième âge, peut être incorrecte, parce qu'il néglige le risque basale pour les accidents. Notre modèle distingue le risque ostéoporotique de fracture comme un risque plus haut que le risque de l'accident attendu pour un certain âge et gendre, et permet une quantification plus valide des fractures ostéoporotiques parmi des populations différentes.

     

Management of complications after operations for acute pancreatitis

After early operation in 49 patients and delayed operation in 114 patients, all with acute hemorrhagic-necrotizing pancreatitis, 65% of patients developed local or general complications. Local complications were abscesses, peritonitis, bleeding, gastrointestinal fistulae or stenoses, and external pancreatic fistulae. Their cause can be traced to the large wound cavity with the tryptic wound surface as well as residual necrosis. The general postoperative complications were shock, acute renal failure, cardiorespiratory insufficiency, gastrointestinal bleeding, ileus, coagulopathy, and sepsis. These may have resulted from the local complications, or may even have been present before operation. If local septic complications do not respond to conservative treatment, they require reoperation. For gastrointestinal fistulae or stenoses, or for pancreatic fistulae, a wait and see attitude is recommended. Generalized complications call for aggressive intensive medical care.Despite the frequency of postoperative complications, the total mortality rate in our series was 30% in patients with partial pancreatic necrosis operated on early, and in patients who received delayed operations for acute hemorrhagic-necrotizing pancreatitis. The 74% mortality rate in early operations of subtotal and total pancreatic necroses was admittedly high. Operative results in those patients who were under our care from the beginning, however, were more encouraging (mortality rate of 50%) and demonstrate that the correct treatment for severe acute hemorrhagic-necrotizing pancreatitis is surgery.

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Résumé Cent soixante trois malades atteints de pancréatite aigüe nécrotico-hémorragique ont subi une opération précoce (49 cas) ou retardée (114 cas): 65% d'entre eux ont développé des complications locales ou générales. Les complications locales ont été des abcès, des péritonites, des hémorragies, des fistules ou sténoses digestives, des fistules pancréatiques externes. La cause en est la large cavité résiduelle postopératoire avec ses surfaces pancréatiques cruentées et ses nécroses résiduelles. Les complications générales ont été des états de choc, des insuffisances rénales aigües, des défaillances cardio-respiratoires, des hémorragies digestives, des iléus, des troubles de la coagulation et des infections. Elles peuvent être la conséquence des complications locales ou peuvent être apparues avant l'opération. Lorsque les complications infectieuses locales ne répondent pas au traitement conservateur, elles doivent être opérées. Pour les fistules et sténoses digestives, pour les fistules pancréatiques, nous recommandons l'expectative. Les complications générales exigent un traitement médical aggressif.Malgré la fréquence des complications postopératoires, la mortalité globale, dans notre série de patients, a été de 30% pour les pancréatites nécrosantes opérées précocement et pour les pancréatites nécrotico-hémorragiques ayant subi une opération retardée. La mortalité de 74% pour les opérations précoces dans les nécroses pancréatiques subtotales ou totales est trop lourde. Mais les résultats obtenus chez les patients qui ont été traités dans notre service dès le début de la maladie ont été plus encourageants (mortalité 50%): ils montrent que la chirurgie est le traitement adéquat de la pancréatite aigüe nécrotico-hémorragique grave.

     

Comparison of oval cells induced in rat liver by feeding N-2-fluorenylacetamide in a choline-devoid diet and bile duct cells induced by feeding 4,4'-diaminodiphenylmethane

Oval cells and duct-like structures produced in the livers of rats fed N-2-fluorenylacetamide in a choline-devoid diet differ from bile ducts produced after feeding 4,4'-diaminodiphenylmethane. Rapid elevations of serum alpha-fetoprotein (AFP) occur after feeding N-2-fluorenylacetamide in a choline-devoid diet; no elevations of AFP are seen during 4,4'-diaminodiphenylmethane feeding. The duct-like structures associated with oval cells frequently contain AFP and albumin and are faintly delineated by laminin, whereas normal bile ducts and ducts induced by 4,4'-diaminodiphenylmethane do not contain AFP or albumin and are delineated by an intensely staining layer of laminin. Zones of oval cell proliferation label intensely for fibronectin, whereas zones of bile duct proliferation label much less intensely. It is concluded that the "tubuloform degeneration" seen after carcinogen exposure does not necessarily represent differentiation to true bile duct structures and that oval cells may neither derive from nor differentiate into bile ducts. Oval cells have characteristics more like fetal hepatocytes than ductular cells and may represent a "stem cell"-like population with potential for loss of growth control and malignant transformation.     

Intraoperative retinal light damage reflected in electrophysiologic data

In a series of 30 unilaterally pseudophakic patients, electroretinograms and electrooculograms were recorded 6 months postoperatively. The unoperated on fellow eyes served as controls High intraoperative retinal light exposure (3.4–7.3 mW/cm², Zeiss OPMI 6 operating microscope) caused a substantial reduction of electrophysiologic potentials. Light protection prevented deterioration of electroretinogram and electro-oculogram potentials; reducing the bulb voltage, tilting the axis of illumination, filtering short wavelengths and the use of light shields resulted in 4-log-unit lower intensities (0.8–3.7 W/cm²).Abbreviations ACL anterior chamber lens - ECCE extracapsular cataract extraction - ICCE intracapsular cataract extraction - PCL posterior chamber lens     

Nigericin enhances mafosfamide cytotoxicity at low extracellular pH

Summary The cytotoxicity of many alkylating anticancer drugs is increased at reduced intracellular pH (pH_i). The therapeutic index of such agents could therefore be improved by lowering pH_i in the target cells prior to their application. We have previously demonstrated that the formation of lactic acid can be selectively enhanced in malignant tissues via glucose-mediated stimulation of tumor cell glycolysis. However, the resulting reduction in pH_i is partly compensated by the extrusion of H⁺ equivalents into the extracellular space, with pH_i remaining closer to the physiological value than extracellular pH (pH_e). For full exploitation of the proton-mediated increase in the cytotoxicity of alkylating agents, pH_i should therefore be equilibrated with pH_e in lactic acid-producing cells. In the present study we investigated the question as to whether nigericin, an H⁺/K⁺ antiporter enabling the entry into cells of H⁺ ions at low pH_e, can be used to enhance the cytotoxic effect of mafosfamide (MAFO; a precursor of activated cyclophosphamide) on cultured M1R rat mammary carcinoma cells. At pH_e 7.4, the cytotoxic effect of combined treatment with MAFO and nigericin was not superior to treatment with MAFO alone. At acidic pH_e, however, MAFO cytotoxicity was potentiated by nigericin as indicated by the colony-forming capacity of M1R cells. For example, at pH_e 6.2 (corresponding to the approximate mean aggregated pH in actively glycolyzing tumors), the colonyforming fraction of cells treated with a combination of MAFO and nigericin was 3×10^–5 that of controls, as compared with a value of 5×10^–2 found for cells exposed to MAFO alone. These results suggest that agents counteracting cellular mechanisms that control pH_i may be candidate compounds for investigations aimed at the enhancement of alkylating drug cytotoxicity following glucosemediated pH reduction in malignant tumors in vivo.This work was supported by grants from the Dr. Mildred Scheel-Stiftung für Krebsforschung and by the Federal Ministry for Research and Technology (0318849 A)     

Expression of the ELAV-like protein HuR is associated with higher tumor grade and increased cyclooxygenase-2 expression in human breast carcinoma.

PURPOSE: The human ELAV (embryonic lethal abnormal vision)-like protein HuR stabilizes a certain group of cellular mRNAs that contain AU-rich elements in their 3'-untranslated region. Cell culture studies have shown that the mRNA of cyclooxygenase (COX)-2 can be stabilized by HuR. EXPERIMENTAL DESIGN: To investigate a possible contribution of dysregulation of mRNA stability to the progression of cancer and to overexpression of COX-2, we studied expression of HuR in 208 primary breast carcinomas by immunohistochemistry. RESULTS: There were two different staining patterns of HuR in tumor tissue of breast carcinomas: nuclear expression was seen in 61% of cases; and an additional cytoplasmic expression was seen in 30% of cases. Expression of HuR was significantly associated with increased COX-2 expression; this association was particularly significant for cytoplasmic HuR expression (P < 0.0005). We further observed a significant association of cytoplasmic (P = 0.002) or nuclear HuR (P = 0.027) expression with increased tumor grade. Only 13% of the grade 1 carcinomas showed cytoplasmic expression of HuR, compared with 46% of the grade 3 carcinomas. There was no significant correlation between HuR expression and other clinicopathological parameters such as histological type, tumor size, or nodal status as well as patient survival. CONCLUSIONS: Our results suggest that overexpression of HuR in tumor tissue may be part of a regulatory pathway that controls the mRNA stability of several important targets in tumor biology, such as COX-2. Based on our results, additional studies are necessary to investigate whether HuR might be a potential target for molecular tumor therapy.     

Levels of soluble vascular endothelial growth factor (VEGF) receptor 1 in astrocytic tumors and its relation to malignancy, vascularity, and VEGF-A.

PURPOSE: Vascular endothelial growth factor (VEGF)-A isa key mediator of angiogenesis in malignant gliomas. Soluble VEGF receptor 1 (sVEGFR-1) can complex VEGF-A and reduce its bioavailability. In several animal models sVEGFR-1 inhibited angiogenesis and tumor growth. We analyzed the levels of endogenous sVEGFR-1 in gliomas of different malignancy grades in relation to tumor vascularity and VEGF-A. EXPERIMENTAL DESIGN: The concentration of sVEGFR-1 was determined by ELISA in 104 gliomas and normal brain. Levels of sVEGFR-1 were compared with malignancy grade, microvessel density, and VEGF-A concentration. Effects of sVEGFR-1 on glioma extract-induced endothelial cell chemotaxis were analyzed in vitro. RESULTS: The concentration of sVEGFR-1 correlated with the malignancy grade and was 12-fold higher in glioblastomas than in diffuse astrocytomas (P < 0.001), with intermediate levels for anaplastic astrocytomas. VEGF-A levels were 30-fold higher (P < 0.001) in glioblastomas than in diffuse astrocytomas. The sVEGFR-1:VEGF-A ratio was 0.27 in glioblastomas and 0.70 in diffuse astrocytomas. Both sVEGFR-1 and VEGF-A correlated with microvessel density (P < 0.001) and with each other (P < 0.001); sVEGFR-1 and VEGF-A also correlated with each other when only glioblastomas were analyzed (P = 0.001). In vitro, recombinant sVEGFR-1 inhibited endothelial cell chemotaxis induced by tumor extracts. CONCLUSIONS: Although absolute levels of sVEGFR-1 are increased in the more malignant gliomas, the sVEGFR-1:VEGF-A ratio is decreased 2.6-fold in glioblastomas compared with diffuse astrocytomas, suggesting that the ensuing increased bioavailability of VEGF-A favors angiogenesis. The inhibition of tumor extract-induced endothelial chemotaxis by sVEGFR-1 suggests that sVEGFR-1 could be useful as an angiogenesis inhibitor in the specific context of human gliomas.