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Biomedical subjects

H Koenig

Publications and source records attributed to H Koenig.

At least 37 records · Page 2Linked to original sources
PubMed1992

[Trichosporon capitatum septicemia. Apropos of 5 cases].

Invasive Trichosporon capitatum infections are seldom reported. We present here five cases of septicemia. All patients had an acute myeloblastic leukemia and were severely neutropenic. They have also been treated before the onset of the fungal infection with broad-spectrum antibiotherapy and also with an oral azole antifungal agent. The role of this antifungal therapy in the development of T. capitatum infection is discussed. The prognosis of T. capitatum infections is severe. Eight of the 10 published cases had a fatal outcome and one of our patients died of the fungal infection in spite of the treatment.

Adult↗
PubMed1991

[Multicenter study of 435 yeast strains isolated from 116,000 hemocultures].

During a multicentric study on the diagnosis of yeast septicemia, 5 blood culture media have been compared. 435 yeast strains have been isolated from 116,372 blood cultures received during year 1989 in the mycological laboratories of 5 university hospitals from east of France. The results show that Candida albicans is always the first septicemia agent with 52% of yeasts isolation from blood. C. parapsilosis comes next with 17%, then C. glabrata, 6.2%. The average delay of yeasts isolation is 2.3 days for Bactec NR and Sabouraud media, 3.7 days for other bacteriological media. Compared with polyvalent media, Sabouraud diphasic medium is significantly the best for yeasts isolation. It is recommended to add chloramphenicol in the medium, to culture 10 ml of blood and to keep blood cultures for at least 8 days, better 15 days.

Candidiasis↗
PubMed1991

Cunninghamella bertholletiae: an uncommon agent of opportunistic fungal infection. Case report and review.

Cunninghamella bertholletiae is a fungus of the Zygomycetes class, Mucorales order. Only very few cases of disseminated infection have been reported. We observed a new case in a 19 years old man with severe aplastic anemia, due to pulmonary primoinfection and hematologic dissemination. This aplastic anemia failed to respond first to an antithymocyte globulin and steroid treatment and then to cyclosporine A. Deferoxamine was infused weekly to prevent iron overload. During a second antithymocyte globulin and steroid treatment, the patient developed bilateral pneumonia. Culture of the broncho-alveolar washing fluid established the diagnosis by isolation of C. bertholletiae. Despite amphotericin B and 5-fluorocytosine intravenous therapy, the patient died of disseminated infection six days after diagnosis, which was confirmed by necropsy. Underlying conditions, diagnosis and treatment are discussed, together with a review of the literature.

Adult↗
PubMed1990

Brain polyamines are controlled by N-methyl-D-aspartate receptors during ischemia and recirculation.

We studied the time course and molecular mechanisms of changes in brain polyamines and their rate-regulatory synthetic enzyme ornithine decarboxylase during reversible forebrain ischemia and recirculation in the gerbil. Bilateral carotid occlusion induced an acute (less than 2 minutes), transient increase in ornithine decarboxylase activity and putrescine level. After 15 minutes of ischemia, recirculation evoked an immediate (less than 1 minute) increase in ornithine decarboxylase activity and putrescine concentration that progressed over a 15-minute period. A small rise in spermidine and spermine also was observed. A secondary increase in ornithine decarboxylase activity and the levels of putrescine and spermidine commenced after 6 hours of recirculation. Pretreatment with a-difluoromethylornithine, a specific suicide inhibitor of ornithine decarboxylase, or MK-801, a noncompetitive N-methyl-D-aspartate receptor antagonist, abolished all early and delayed increases in ornithine decarboxylase activity and polyamine levels. This is the first demonstration that both ischemia and postischemic recirculation evoke rapid, transient increases in the activity of ornithine decarboxylase and the levels of polyamines, most notably the ornithine decarboxylase product, putrescine. Our results indicate that N-methyl-D-aspartate receptor activation (by an ischemically induced elevation of extracellular glutamate) is responsible for initiating the early and the delayed stimulation of ornithine decarboxylase activity. Ornithine decarboxylase activation causes the rapid rise in the levels of putrescine and higher polyamines observed in the acute response to ischemia and the acute and delayed response to postischemic recirculation. These polyamine changes may be involved in the pathophysiology of Ca2+ entry and neuronal death after brain ischemia.

Animals↗
PubMed1990

Disseminated Trichosporon capitatum infection in a patient with acute leukemia undergoing bone marrow transplantation.

A case of disseminated infection with Trichosporon capitatum is reported in a 23-year-old patient with acute myeloid leukemia undergoing HLA-mismatched bone marrow transplantation. He was receiving immunosuppressive therapy with cyclosporine and corticosteroids for acute graft-versus-host disease and he was severely neutropenic. While being treated with fluconazole for 28 days for an oropharyngeal candidiasis the patient developed a T. capitatum septicemia. He died despite receiving amphotericin B therapy. Autopsy revealed widespread infection with T. capitatum. The portal of entry was probably the digestive tract in this patient as T. capitatum had been first isolated in the stools.

Adult↗
PubMed1990

[Trichosporon capitatum septicemia in immunosuppressed patients].

Disseminated Trichosporon capitatum infections are seldom reported. We observed 3 cases in leukemic patients within 4 months. All 3 patients were granulocytopenic. One of them was also treated with cyclosporine and methyl-prednisolone after an allogenic bone marrow transplant. The portal of entry was certainly the digestive tract as Tr. capitatum have been isolated in the stool before the septicemia. All 3 patients were previously treated with an azole antifungal compound. The part of this treatment in the emergence of Tr. capitatum in the digestive tract and in the occurrence of the septicemia must be considered. As Tr. capitatum are usually sensitive to the azole compounds the explanation may be a too low daily dosage for the treatment of severely immunocompromised hosts.

Adult↗
PubMed1989

Polyamines mediate the reversible opening of the blood-brain barrier by the intracarotid infusion of hyperosmolal mannitol.

The blood-brain barrier (BBB) can be opened transiently by infusing a hyperosmolal solution of a non-electrolyte into the internal carotid artery. We investigated the hypothesis that capillary polyamines and their rate-regulating synthetic enzyme, ornithine decarboxylase (ODC), may be involved in mediating BBB breakdown in this model, as they are in BBB breakdown by focal cold injury. The intracarotid infusion of 1.6 M mannitol induced a prompt (less than 2 min) increase in ODC activity and the levels of polyamines in the ipsilateral hemisphere. Isolated cerebral capillary preparations and neural elements showed similar increases in ODC activity. The rank order of increase at 2 min, ODC (170%) greater than putrescine (90%) greater than spermidine (15%) greater than spermine (7%), was consistent with an activation of the ODC-regulated pathway of polyamine synthesis. The specific ODC inhibitor alpha-difluoromethylornithine (DFMO) blocked the 1.6 M mannitol-induced increase in ODC activity and the accumulation of polyamines, and concurrently prevented BBB breakdown, monitored by transport of intravenously administered Evans blue and alpha-[3H]aminoisobutyrate into cerebral tissue. Exogenous putrescine, the product of ODC activity, replenished brain polyamines and negated DFMO protection allowing BBB breakdown by 1.6 M mannitol. These experiments support the hypothesis that BBB breakdown induced by the intracarotid infusion of hyperosmolal mannitol is mediated by rapid, ODC-regulated synthesis of microvascular polyamines. In addition, increases in ODC-controlled polyamine synthesis in nerve cells may play a significant role in the pathophysiology of the reversible neuronal dysfunction, e.g. diazepam-sensitive seizure-like activity, enhanced glucose utilization, evoked by the intracarotid infusion of hyperosmolal mannitol.

Blood-Brain Barrier↗
PubMed1989

Polyamines and Ca2+ mediate hyperosmolal opening of the blood-brain barrier: in vitro studies in isolated rat cerebral capillaries.

We recently presented evidence that the reversible opening of the blood-brain barrier (BBB) by the infusion of 1.6 M mannitol into the rat internal carotid artery is mediated by a rapid stimulation of ornithine decarboxylase (ODC) activity and putrescine synthesis in cerebral capillaries. We have now investigated this hypothesis further, using isolated rat cerebral capillaries as an in vitro model of the BBB. The ODC activity of cerebral capillary preparations was enriched up to 15-fold over that of the cerebral homogenate. Hyperosmolal mannitol in physiological buffer evoked a rapid (less than 15 s), concentration- and time-dependent increase in capillary ODC activity and an accumulation of putrescine and spermidine which was blocked by the specific ODC inhibitor, alpha-difluoromethylornithine (DFMO, 10 mM). Mannitol (1 M), as well as 2 M urea, evoked a two- to fivefold increase in the temperature-sensitive influx of 45Ca2+ and uptake of horseradish peroxidase (HRP) and 2-deoxy-D-[1-3H]glucose (DG), but not alpha-[1-14C]aminoisobutyrate, during a 2-min incubation. DFMO (10 mM) abolished 1 M mannitol-mediated stimulation of 45Ca2+ influx and uptake of HRP and DG, whereas 1 mM putrescine replenished capillary polyamines and reversed the DFMO effects. Mannitol (1 M)-induced stimulation of ODC activity and membrane transport processes was Ca2+-dependent and verapamil- and nisoldipine-sensitive. Phorbol myristate acetate (PMA, 10 nM), a protein kinase C activator, also evoked a two- to threefold stimulation of 45Ca2+ transport and HRP and DG uptake. This PMA effect was abolished by DFMO, suggesting involvement of rapid, ODC-controlled polyamine synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminoisobutyric Acids↗
PubMed1989

Blood-brain barrier breakdown in cold-injured brain is linked to a biphasic stimulation of ornithine decarboxylase activity and polyamine synthesis: both are coordinately inhibited by verapamil, dexamethasone, and aspirin.

An early increase in ornithine decarboxylase (ODC) activity and polyamine levels in rat cerebral capillaries was previously implicated in the mediation of blood-brain barrier (BBB) breakdown in cold-injured brain. A time course study in rat cerebrum indicated that cold injury evokes a biphasic increase in ODC activity and polyamine levels in perilesional cortex. ODC activity rose sharply (fourfold) within 1 min, remained elevated for 5 min, and then returned to the basal level by 10 min. A transient rise in polyamine concentration followed in the rank order of putrescine greater than spermidine greater than spermine. A secondary rise in ODC activity commenced in perilesional tissue at 2-6 h and peaked (8.8-fold) at 48 h. Major increases in the content of putrescine (330%), spermidine (103%), and spermine (50%) developed at 48-72 h. alpha-Difluoromethylornithine (DFMO), a specific irreversible inhibitor of ODC, suppressed the evoked increase in ODC activity and abolished the associated increase in content of polyamines, findings indicating that the accumulation of polyamines in cryoinjured brain reflects enhanced synthesis resulting from an ODC-mediated increase in putrescine content. Cycloheximide and actinomycin D were without effect on the early increase in ODC activity but inhibited the delayed increase in ODC activity, an observation suggesting that the initial increase in activity reflects an activation of a cryptic ODC via a posttranslational process, whereas the delayed increase in activity results from ODC synthesis mainly under transcriptional control.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Polyamines mediate androgenic stimulation of calcium fluxes and membrane transport in rat heart myocytes.

The androgenic steroid hormone testosterone induced an early (less than 30-60 seconds) stimulation of endocytosis, hexose transport, and amino acid transport, monitored by the temperature-sensitive uptake of horseradish peroxidase, 2-deoxyglucose, and alpha-aminoisobutyrate, respectively, in rat ventricle cubes and acutely isolated ventricular myocytes. This stimulation was time- and concentration-dependent and was maximal at 10(-9) to 10(-8) M testosterone, consistent with androgen-receptor mediation. EGTA (2.5 mM), La3+ (1 mM), and verapamil (100 microM) ablated the hormonal response. The calcium ionophore A23187 (10 microM) induced an acute stimulation of endocytosis, amino acid transport, and hexose transport which was not further increased by testosterone (10(-8) M), suggesting a common effector pathway. Testosterone (10(-8) M) also evoked a rapid (less than 30 seconds) stimulation of 45Ca influx and efflux. Testosterone (10(-8) M) induced a rapid (less than 5 seconds) transient increase in ornithine decarboxylase (ODC) activity peaking (twofold to threefold) at 60 seconds, and an early (15 seconds) transient accumulation of polyamines peaking at 60 seconds in isolated myocytes. The specific, irreversible ODC inhibitor alpha-difluoromethylornithine (DFMO, 5-10 mM) blocked the testosterone-evoked increase in ODC activity and polyamine levels and the stimulation of Ca2+ fluxes, endocytosis, hexose transport, and amino acid transport. Putrescine (0.5-1 mM), the ODC product, reversed DFMO inhibition and restored the increase in polyamines, 45Ca fluxes, and Ca2+-dependent membrane transport processes. These results demonstrate that rapid, transient ODC-regulated polyamine synthesis is essential for androgenic stimulation of Ca2+ fluxes and membrane transport processes in ventricular myocytes. These findings support a model for signal transduction in which newly synthesized polyamines serve as intracellular messengers to regulate transmembrane Ca2+ movements, Ca2+-dependent membrane transport functions, and other Ca2+- and polyamine-sensitive processes in cardiac myocytes.

Amino Acids↗
PubMed1989

[Axon regeneration in the Trembler mouse, with mutation affecting Schwann cells].

Elongation, branching and regeneration rate of axons are increased (two folds) in Trembler tibial nerve after local freezing and control grafting (NNN; TrTrTr). After chimera transplantation (NTrN), normal regenerating axons are increased by 50% when they grow within a mutant (Tr) as compared to a normal (N) graft. Our results emphasize the influence of the density of Schwann cells and multi-layered basal laminas which characterize Trembler peripheral nerves.

Animals↗
PubMed1988

Polyamines are intracellular messengers in the beta-adrenergic regulation of Ca2+ fluxes, [Ca2+]i and membrane transport in rat heart myocytes.

The beta-adrenergic agonist 1-isoproterenol (0.1 microM) evokes an acute (less than 5-10 sec) transient increase in the activity of ornithine decarboxylase (ODC), and the levels of polyamines (putrescine, spermidine, spermine) in acutely isolated rat ventricular myocytes. Isoproterenol rapidly (less than 15 sec) increases 45Ca influx and efflux, decreases [Ca2+]i, and stimulates Ca2+-dependent membrane transport (endocytosis, hexose transport, amino acid transport). The beta-adrenergic antagonist propranolol blocks isoproterenol-induced membrane transport. The ODC inhibitor alpha-difluoromethylornithine (DFMO, 5-10 mM) blocks the isoproterenol-evoked increase in ODC activity and polyamine levels and the changes in 45Ca fluxes, [Ca2+]i and membrane transport. Putrescine (0.5-1 mM) replenishes cellular polyamines and reverses the DFMO effect. These data exclude an increase in [Ca2+]i in stimulus-transport coupling, and support the hypothesis that polyamines are messengers in beta-adrenoceptor-mediated regulation of transmembrane Ca2+ fluxes, [Ca2+]i, and Ca2+-dependent membrane transport.

Amino Acids↗
PubMed1988

The role of polyamines in beta-adrenergic stimulation of calcium influx and membrane transport in rat heart.

The beta-adrenergic agonist 1-isoproterenol induced an early (less than 1 min) stimulation of endocytosis, amino acid transport and hexose transport, monitored by the temperature-sensitive uptake of horseradish peroxidase, alpha-aminoisobutyrate and 2-deoxyglucose, respectively, in rat ventricle cubes. This stimulation was time- and concentration-dependent and was maximum at 10(-8) M isoproterenol. The beta-adrenergic antagonist propranolol blocked isoproterenol stimulation of membrane transport, thereby confirming beta-adrenoceptor mediation; 2.5 mM EGTA, 1 mM LaCl2 and 100 microM verapamil blocked the hormonal response without affecting basal transport. The calcium ionophore A23187 caused an acute stimulation of endocytosis, hexose and amino acid transport. Isoproterenol rapidly (less than 30 s) stimulated 45Ca2+ influx. These data suggest that stimulus-response (stimulus-"transport") coupling is mediated by a rise in cytosolic Ca2+ concentration. A rapid (less than 30 to 60 s) increase in ornithine decarboxylase (ODC) activity, followed by an early (less than 1 to 2 min), sustained increase in putrescine, spermidine and spermine concentrations was evoked by 10(-7) M isoproterenol. The ODC inhibitor alpha-difluoromethylornithine (DFMO, 5 mM) suppressed the isoproterenol-induced increase in ODC and polyamine levels and the stimulation of 45Ca influx, endocytosis, hexose transport, and amino acid transport. Putrescine (0.5 mM) negated DFMO inhibition and restored the increase in polyamines, 45Ca influx, endocytosis, and transport of hexose and amino acid. These data suggest that polyamine synthesis is involved in isoproterenol stimulation of Ca2+ influx and membrane transport functions in ventricular myocardium. These findings are consistent with a model for signal transduction and stimulus-response coupling in which polyamines function as intracellular messengers to generate cytosolic Ca2+ signals by stimulating Ca2+ influx.

Aminoisobutyric Acids↗
PubMed1987

Polyamines mediate uncontrolled calcium entry and cell damage in rat heart in the calcium paradox.

Brief perfusion of heart with calcium-free medium renders myocardial cells calcium-sensitive so that readmission of calcium results in uncontrolled Ca2+ entry and acute massive cell injury (calcium paradox). We investigated the hypothesis that polyamines may be involved in the mediation of abnormal Ca2+ influx and cell damage in the calcium paradox. The isolated perfused rat heart was used for these studies. Calcium-free perfusion promptly (less than 5 min) decreased the levels of polyamines and the activity of their rate-regulating synthetic enzyme, ornithine decarboxylase (ODC), and calcium reperfusion abruptly (less than 15-180 s) increased these components. alpha-Difluoromethylornithine (DFMO), a specific suicide inhibitor of ODC, suppressed the calcium reperfusion-induced increase in polyamines and the concomitant increase in myocardial cellular 45Ca influx, loss of contractility, release of cytosolic enzymes, myoglobin, and protein, and structural lesions. Putrescine, the product of ODC activity, nullified DFMO inhibition and restored the calcium reperfusion-induced increment in polyamines and the full expression of the calcium paradox. Putrescine itself enhanced the reperfusion-evoked release of myoglobin and protein in the absence of DFMO. Hypothermia blocked the changes in heart ODC and polyamines induced by calcium-free perfusion and calcium reperfusion and prevented the calcium paradox. These results indicate that rapid Ca2+-directed changes in ODC activity and polyamine levels are essential for triggering excessive transsarcolemmal transport of Ca2+ and explosive myocardial cell injury in the calcium paradox.

Animals↗
PubMed1987

[Septicemias caused by Candida and other yeasts. Study of cases observed for 5 years at the University Hospital Center in Strasbourg].

Seventy one files of patients with yeasts septicemia have been studied. This study indicates the influence of factors like age (greater than 50 years), health condition, surgery mainly digestive, severe associated bacterial infections, iatrogenic factors (polyantibiotherapy, catheters, intubation), in the occurrence of these septicemia). Clinical symptoms appear to be mainly fever (93%) accompanied with shudders (26%) and toxi-infectious shock (45%). Diagnosis is made by the isolation of yeasts from the blood cultivated on Sabouraud-Chloramphenicol diphasic medium. Among the responsible yeasts, the genus Candida is predominant (82.2%) with C. albicans (59%) followed by the genera Torulopsis (13.7%) and Trichosporon (2.7%). Medical treatment must associate Amphotericin B and 5 Fluorocytosine.

Adolescent↗
PubMed1986

Temporal bone region: high-resolution MR imaging using surface coils.

Specially designed surface coils for the region of the temporal bone enable high-resolution magnetic resonance (MR) imaging of the structures of the inner ear. Eight healthy volunteers and 21 patients (six with cholesteatomas, five with acoustic neuromas, five with glomus tumors, and five with mastoiditis) were examined using a 0.5-T MR imager. The demarcation of tumor extent with MR imaging was better than with computed tomography because of improved soft-tissue contrast and because the surrounding bony tissue did not generate any signal. High-resolution MR imaging is particularly useful for small acoustic neuromas because of its higher specificity compared with gas cisternography.

Brain Neoplasms↗
PubMed1986

The wrist: a preliminary report on high-resolution MR imaging.

Excellent spatial resolution is required to demonstrate the complex region of the wrist, with its diverse structures comprising bone, cartilage, and ligaments. Magnetic resonance (MR) imaging was done with a Magnetom imaging system operating at 1.0 T. Use of a flat surface coil enabled excellent spatial resolution and a section thickness of 4 mm. Twenty-nine patients with navicular nonunion or pseudarthrosis, rheumatoid arthritis, recent fractures, soft-tissue alterations, and bone tumors were examined. All patients had undergone radiography and bone scintigraphy. In this limited sampling, MR was found to detect and characterize marrow and articular alterations more accurately, and earlier, than either of those modalities.

Bone Diseases↗