[Pneumonias in childhood. Their age dependence, forms and therapeutic consequences].
Explore the source record for details and available documents.
Adolescent↗
Biomedical subjects
H Hahn
Publications and source records attributed to H Hahn.
HPLC determination of clofazimine in tissues and serum of mice after intravenous administration of nanocrystalline or liposomal formulations.
A simple HPLC method is described for the determination of clofazimine in mouse tissues and in serum. The main application of the method was the determination of the drug in mouse tissues after i.v. administration of nanocrystalline suspensions or liposomal encapsulated clofazimine. Tissues were extracted with a 10-fold (w/v) volume of an extraction solution consisting of methanol/glacial acetic acid 9:1 (v/v). Serum proteins were precipitated with a 2-fold volume of acetonitrile. Isocratic chromatography was performed using an anion exchange column (Nucleosil 100-5 SA, Macherey & Nagel) for separation. The mobile phase was a mixture of acetonitrile and 0.1 mol/l aqueous phosphoric acid (75:25, v/v), adjusted to pH 2.9 with sodium hydroxide solution. Absorption of the eluate was monitored at 495 nm. The assay was precise, simple to perform and fast. Recovery from tissues was > or = 98%, from nanoparticles > or = 98%, and from liposomes > or = 96%. No interference was observed in extracts from mouse liver, spleen, lungs and human serum.
Animals↗
[Ultrasound appendix imaging in mucoviscidosis patients].
PURPOSE: The aim of this study was to determine the presentation of the appendix in patients with cystic fibrosis (CF) compared to a healthy control group and patients with acute appendicitis using high resolution graded compression sonography. METHOD: 59 CF patients (mean age 11 years), 54 healthy children (mean age 9 years) and 322 patients with histologically proven acute appendicitis were evaluated by sonography. A blind ending tubular structure in longitudinal sections and a target-like figure in cross sections without peristalsis was considered as appendix. The maximum distance between the outer echolucent layers was calculated as diameter. RESULTS: In 20%, 67% and 90% of the cases, the appendix was identified in the CF-group, healthy children, and patients with acute appendicitis. The mean diameters were 9.8, 3.9, and 10.9 mm respectively. These differences were statistically significant (p < 0.001 and p < 0.012). CONCLUSION: The appendiceal mucocele in cystic fibrosis is an uncommon but important differential diagnosis of the acute appendicitis.
Acute Disease↗
[Animal nutrition in veterinary medicine--an actual case: high incidence of constipation in calf rearing].
A high frequency of constipation was observed in calves with an average body weight of 150 kg. Eleven out of 200 animals died, at necropsy intestinal obstruction was identified due to agglomeration of stone like particles, identified as shell fragments of palm kernels. The calves were fed 3 kg maize silage, 1.5 kg of a commercial mixed feed, 0.5 kg soya meal, and 50 g of a mineral supplement. Hay was offered ad libitum, all animals had free access to drinking water. The composition of the mixed diet was estimated by microscopy and was completely different from the label as provided by the manufacturer. A palm kernel product with high amounts of stone shells was identified in a concentration of 25% of the mixed feed, confirming the findings in the necropsied calves. The pathogenesis of the obstruction seemed to be influenced by a concurrent infectious disease, which might have had negative effects on the gastro-intestinal motility.
Animal Feed↗
pH-dependent gating of ROMK (Kir1.1) channels involves conformational changes in both N and C termini.
ROMK channels (Kir1.1) are members of the superfamily of inward rectifier potassium channels (Kir) and represent the channels underlying K+ secretion in the kidney. As their native counterparts, Kir1.1 channels are gated by intracellular pH, with acidification leading to channel closure. Although a lysine residue (Lys80) close to the first hydrophobic segment M1 has been identified as the pH sensor, little is known about how opening and closing of the channel is accomplished. Here we investigate the gating process of Kir1.1 channels exploiting their state-dependent modification by water-soluble oxidants and sulfhydryl reagents. Mutagenesis of all intracellular cysteines either alone or in combination revealed two residues targeted by these reagents, one in the N terminus (Cys49) and one in the C terminus (Cys308) of the channel protein. Both sites reacted with the thiol reagents only in the closed state and not in the open state. These results indicate that pH-dependent gating of Kir1.1 channels involves movement of protein domains in both N and C termini of the Kir1.1 protein.
Amino Acid Substitution↗
Interaction of permeant and blocking ions in cloned inward-rectifier K+ channels.
Blocking cloned inward-rectifier potassium (Kir) channels from the cytoplasmic side was analyzed with a rapid application system exchanging the intracellular solution on giant inside-out patches from Xenopus oocytes in <2 ms. Dependence of the pore-block on interaction of the blocking molecule with permeant and impermeant ions on either side of the membrane was investigated in Kir1.1 (ROMK1) channels blocked by ammonium derivatives and in Kir4.1 (BIR10) channels blocked by spermine. The blocking reaction in both systems showed first-order kinetics and allowed separate determination of on- and off-rates. The off-rates of block were strongly dependent on the concentration of internal and external bulk ions, but almost independent of the ion species at the cytoplasmic side of the membrane. With K+ as the only cation on both sides of the membrane, off-rates exhibited strong coupling to the K+ reversal potential (E(K)) and increased and decreased with reduction in intra and extracellular K+ concentration, respectively. The on-rates showed significant dependence on concentration and species of internal bulk ions. This control of rate-constants by interaction of permeant and impermeant internal and external ions governs the steady-state current-voltage relation (I-V) of Kir channels and determines their physiological function under various conditions.
Animals↗
Craf-1 protein kinase is essential for mouse development.
The three mammalian Raf serine/threonine protein kinases mediate the transduction of proliferative and differentiative signals from a variety of cell surface receptors to the nucleus. We report here that Craf-1 is essential for mouse development, as its mutation results in embryonic lethality. Developmental defects are found in mutant placentas as well as in the skin and in the lungs of mutant embryos. Craf-1 mutants also display a generalized growth retardation which is consistent with the ubiquitous expression of Craf-1 and which could be due to the reduced proliferation of mutant cells. Interestingly, the time-point of embryonal death varies depending on the genetic background. This suggests that Craf-1-mediated signaling is affected by genetic background-specific alleles of other genes.
Abnormalities, Multiple↗
Rhabdomyosarcomas and radiation hypersensitivity in a mouse model of Gorlin syndrome.
Gorlin (or nevoid basal cell carcinoma) syndrome is characterized by a variety of clinical problems including generalized overgrowth of the body, cysts, developmental abnormalities of the skeleton and a predisposition to benign and malignant tumors. The syndrome results from germline mutations of the human homolog of the drosophila segment polarity gene patched (ptc). Here we report that mice heterozygous for ptc develop many of the features characteristic of Gorlin syndrome and that they exhibit a high incidence of rhabdomyosarcomas (RMS), the most common soft-tissue sarcoma in children. The downstream signalling partner of ptc, gli1, was overexpressed in all RMSs analyzed, indicating that abnormal signalling of the ptc-gli1 pathway may be common for the various tumors associated with the syndrome. igf2, implicated in the formation of RMSs, was also overexpressed, suggesting cross-talk between the ptc and igf2 pathways in tumorigenesis. Developmental defects in Gorlin syndrome resemble those induced by ionizing radiation. We show that ptc heterozygous mice exhibit increased incidence of radiation-induced teratogenesis. This suggests a role for ptc in the response to ionizing radiation and provides a model for both the systemic (developmental) and stochastic (cancer) abnormalities observed in Gorlin syndrome.
Animals↗
Characterization of Bartonella henselae isolated from bacillary angiomatosis lesions in a human immunodeficiency virus-infected patient in Germany.
Infections with Bartonella (Rochalimaea) henselae can result in a variety of clinical entities, including bacillary angiomatosis in immunocompromised hosts. The fastidious nature of this bacterium has so far prevented the culture of many clinical isolates. We report the recovery of the first European B. henselae isolate associated with bacillary angiomatosis. The isolate was cultured in a frozen skin biopsy specimen from a human immunodeficiency virus (HIV)-infected patient and was characterized by means of biochemical, bacteriologic, immunologic, and molecular biological methods including pulsed-field gel electrophoresis. This strain was compared with two B. henselae strains isolated in the United States to determine the relationship between the isolates. We found that it was phenotypically and genotypically indiscernible from B. henselae Houston-1, a blood culture isolate from an HIV-infected patient in Houston. These data suggest that one B. henselae clone is associated with human infections in Europe and the United States.
AIDS-Related Opportunistic Infections↗
Detection of specific cellular immune response to Bartonella henselae in a patient with cat scratch disease.
Explore the source record for details and available documents.
Adult↗
Cerebral syncope: loss of consciousness associated with cerebral vasoconstriction in the absence of systemic hypotension.
Transcranial Doppler (TCD) ultrasonography done during head-upright tilt induced neurocardiogenic syncope has demonstrated that cerebral vasoconstriction occurs concomitant with (or precedes) loss of consciousness. This article demonstrates evidence that cerebral blood flow changes alone (vasoconstriction), in the absence of systemic hypotension, may result in syncope. Five patients (4 men, 1 woman; mean age 41 +/- 17 years) with recurrent unexplained syncope were evaluated by use of an upright tilt table test for 45 minutes with or without an infusion of low dose isoproterenol. TCDoppler ultrasonography was used to assess middle cerebral artery systolic velocity (Vs); diastolic velocity (Vd); mean velocity (Vm); and pulsatility index (PI = Vs = Vd/Vmean). Syncope occurred in five patients during the baseline tilt and in one patient during isoproterenol infusion. During tilt induced syncope, at an average mean arterial pressure of 89 +/- 16 mmHg, TCD sonography showed a 2% +/- 10% increase in systolic velocity; a 51% +/- 27% decrease in diastolic velocity; and a 131% +/- 87% increase in pulsatility index. One patient underwent continuous electroencephalographic recording during tilt, which demonstrated diffuse slow wave activity (indicating cerebral hypoxia) at the time of syncope concomitant with the aforementioned TCD changes in the absence of systemic hypotension. These findings reflect an increase in cerebrovascular resistance secondary to arteriolar vasoconstriction distal to the insonation point of the middle cerebral artery, that occurred concomitant with loss of consciousness and in the absence of systemic hypotension. We conclude that in some individuals abnormal baroreceptor responses triggered during orthostatic stress may result in a derangement of cerebral autoregulation leading to cerebral vasoconstriction with resultant cerebral hypoxia in the absence of systemic hypotension.
Adolescent↗
Rationale for and efficacy of prolonged-interval treatment using liposome-encapsulated amikacin in experimental Mycobacterium avium infection.
The potential of liposome-encapsulated antibiotics for prolonging drug application intervals was investigated by using a murine model of chronic lethal Mycobacterium avium infection. Liposomal encapsulation of amikacin, but not of ciprofloxacin, resulted in high and sustained drug levels in infected tissues, exceeding the minimal inhibitory concentration for M. avium for at least 28 days. As a consequence, once-weekly and even once-monthly treatments with liposomal amikacin significantly reduced bacterial replication in infected tissues and extended the survival time of infected mice.
Amikacin↗
Murine model of Bartonella henselae infection in the immunocompetent host.
Bartonella henselae is an emerging pathogen causing cat scratch disease, bacillary angiomatosis, and peliosis hepatis. Progress in understanding the pathogenesis of and the immune response to these infections has been limited by the lack of an animal model. Following intraperitoneal infection of C57BL/6 mice with B. henselae, organs were cleared of cultivatable bacteria within 6 days. In contrast, B. henselae DNA could be detected in liver tissue for at least 3 months. Liver tissue showed granulomatous inflammation reaching its highest degree of intensity during the fourth week of infection and resolving within 12 weeks postinfection. This mouse model is applicable to the study of the pathogenesis of B. henselae and the immune response to this pathogen in the immunocompetent host.
AIDS-Related Opportunistic Infections↗
Rapamycin and wortmannin enhance replication of a defective encephalomyocarditis virus.
Inhibitors of the phosphatidylinositol 3-kinase (PI3 kinase)-FKBP-rapamycin-associated protein (FRAP) pathway, such as rapamycin and wortmannin, induce dephosphorylation and activation of the suppressor of cap-dependent translation, 4E-BP1. Encephalomyocarditis virus (EMCV) infection leads to activation of 4E-BP1 at the time of host translation shutoff. Consistent with these data, rapamycin mildly enhances the synthesis of viral proteins and the shutoff of host cell protein synthesis after EMCV infection. In this study, two defective EMCV strains were generated by deleting portions of the 2A coding region of an infectious cDNA clone. These deletions dramatically decreased the efficiency of viral protein synthesis and abolished the virus-induced shutoff of host translation after infection of BHK-21 cells. Both translation and processing of the P1-2A capsid precursor polypeptide are impaired by the deletions in 2A. The translation and yield of mutant viruses were increased significantly by the presence of rapamycin and wortmannin during infection. Thus, inhibition of the PI3 kinase-FRAP signaling pathway partly complements mutations in 2A protein and reverses a slow-virus phenotype.
Androstadienes↗
Surface-modified amikacin-liposomes: organ distribution and interaction with plasma proteins.
Amikacin-loaded liposomes were produced and surface-modified by adsorption of PEG 4000, Tween 80, poloxamer 407 and gelatin. The organ distribution was studied in mice by analysing the amikacin content in liver, spleen, lung, kidneys and serum. Highest serum levels were obtained with the PEG- and Tween 80 modified liposomes (at 2 hours p.inj.). Modification of the liposomes with gelatin as opsonization promoting agent distinctly increased the amikacin concentration in the liver from 36 to 66 mg/kg. Highest spleen concentrations were observed with non-modified and poloxamer 407 liposomes (242 mg/kg and 248 mg/kg, respectively). The data suggest that modification by a simple adsorption process is sufficient to effectively alter the organ distribution. The liposomes differing in organ distribution exhibited also different plasma protein adsorption patterns, up to 115 spots were detected by 2-D PAGE. Hydrophilic albumin was present in a conc. of appr. 80% on liposomes modified with ethoxylated compounds. On the gelatin liposomes, 14% of alpha-2-Macroglobulin were adsorbed which is a protein typically found on particles rapidly cleared by the RES. IgM, Apo A-I, Apo C-II and alpha-1-Antitrypsin were other detected proteins.
Amikacin↗
Bactericidal activity of lansoprazole and omeprazole against Helicobacter pylori in vitro.
The minimum inhibitory concentrations of 39 Helicobacter pylori strains against antibiotics (ampicillin, tetracycline, metronidazole), colloidal bismuth subcitrate and proton pump inhibitors were assessed by the agar dilution method. 20.5% of the strains were metronidazole resistent. The comparison of the bactericidal action of omeprazole and lansoprazole in a killing curve assay showed a dose-dependent reduction of viable bacteria after 24 h, lansoprazole being more effective than omeprazole. Under varying pH conditions, the antibacterial activity of lansoprazole was limited to a pH range of 6-7, reducing bacterial numbers up to 4 logarithmical steps within 24 h.
2-Pyridinylmethylsulfinylbenzimidazoles↗
[Antimicrobial therapy in neutropenia].
Explore the source record for details and available documents.
Anti-Infective Agents↗
Efficacy of different methods for detection of low Cryptosporidium parvum oocyst numbers or antigen concentrations in stool specimens.
The detection of Cryptosporidium parvum oocysts in stool specimens by acid-fast (AF) stains or immunofluorescence assays (IFA) requires the presence of large numbers of oocysts. To determine whether new commercially available enzyme immunoassays (EIAs) are more sensitive alternatives, three EIAs, a direct IFA, and the modified cold Kinyoun AF stain were compared, particularly with respect to detection of low oocyst numbers or antigen concentrations. Thirty-one negative and 31 calf stool-enriched human stool specimens were tested. One EIA method detected only nine positive specimens, demonstrating a sensitivity significantly less (p < 0.0001) than that of the IFA, the AF stain, and the other two EIAs. No differences could be found with respect to specificity. In addition, serial dilutions of 28 patients' stool samples containing cryptosporidian oocysts were prepared and examined using two EIAs, IFA, and the AF stain. One EIA yielded significantly inferior results (p < 0.0001), whereas the other one and the two microscopic methods did not differ significantly in either part of the study. The results indicate that the new EIAs do not exhibit higher sensitivities for detection of Cryptosporidium parvum than the two routinely used microscopic methods. Thus, for most laboratories, the IFA or AF stain may still represent the preferred method for the diagnosis of cryptosporidiosis.
AIDS-Related Opportunistic Infections↗