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Biomedical subjects

J Gerber

Publications and source records attributed to J Gerber.

At least 19 recordsLinked to original sources

FcgammaRI (CD64) contributes substantially to severity of arthritis, hypersensitivity responses, and protection from bacterial infection.

The high-affinity receptor for IgG, FcgammaRI, shares its capacity to bind IgG2a immune complexes (IgG2a-IC) with the low-affinity receptor FcgammaRIII and complement factors, hampering the definition of its biological role. Moreover, in vivo, FcgammaRI is occupied by monomeric IgG2a, reducing its accessibility to newly formed IgG2a-IC. By using a variety of FcgammaR(-/-) mice, we demonstrate that in the absence of FcgammaRI, the IgG2a-IC-induced cellular processes of phagocytosis, cytokine release, cellular cytotoxicity, and antigen presentation are impaired. FcgammaRI(-/-) mice showed impaired hypersensitivity responses, strongly reduced cartilage destruction in an arthritis model, and impaired protection from a bacterial infection. We conclude that FcgammaRI contributes substantially to a variety of IgG2a-IC-dependent immune functions and immunopathological responses.

Animals↗

[The "Barthel Index": alternative to expertising in compulsory care insurance?].

Measuring the level of care needed is difficult and since the introduction of nursing care insurance in Germany in 1995 the assessment method applied by the MDK (Medizinischer Dienst der Krankenversicherung) has repeatedly been criticised. The method is very costly and not broadly tested for its validity and reliability. The question arises whether similar results can be obtained by applying another instrument, like the Barthel Index (BI), which is easier to use and more reliable. In this article the authors show - based on a preliminary study in 1999 - that by using the Barthel Index a discriminance analysis will show identical results in 80 % of all cases. The authors regard this identical measurement of care needs, which is reached by scoring only ten items (BI) versus thirty (MDK's assessment method) and with a presumingly higher reliability, as a major progress and reason enough for further discussion and studies of the use of the Barthel Index for care needs assessment.

Adolescent↗

Surgery of low-grade gliomas near speech-eloquent regions: brainmapping versus preoperative functional imaging.

The identification of eloquent areas is of utmost importance in the surgery of tumors located near speech-eloquent brain areas, since the classical concept of a constant localization was proven to be untrue and the spatial localization of these areas may show large interindividual differences. Some neurosurgical centers apply intraoperative electrophysiological methods that, however, necessitate the performance of surgery in the awake patient. This might be a severe burden both for the patient and the operating team in a procedure that lasts several hours; in addition, electrical stimulation may generate epileptic seizures. Alternatively, methods of functional brain imaging (e.g., PET, fMRI, MEG) may be applied, which allow individual localization of speech-eloquent areas. Matching of these image data with a conventional 3D-CT or MRI now allows the exact transfer of this information into the surgical field by neuronavigation. Whereas standards concerning electrophysiological stimulation techniques that could prevent a permanent postoperative worsening of language are available, until now it remains unclear whether the resection of regions shown to be active in functional brain imaging will cause a permanent postoperative deficit.

Brain Mapping↗

The p400 complex is an essential E1A transformation target.

Here, we report the identification of a new E1A binding protein complex that is essential for E1A-mediated transformation. Its core component is a SWI2/SNF2-related, 400 kDa protein (p400). Other components include the myc- and p/CAF-associated cofactor, TRRAP/PAF400, the DNA helicases TAP54alpha/beta, actin-like proteins, and the human homolog of the Drosophila Enhancer of Polycomb protein. An E1A mutant, defective in p400 binding, is also defective in transformation. Certain p400 fragments partially rescued this phenotype, underscoring the role of E1A-p400 complex formation in the E1A transforming process. Furthermore, E1A and c-myc each alter the subunit composition of p400 complexes, implying that physiological p400 complex formation contributes to transformation suppression.

Adaptor Proteins, Signal Transducing↗

Yeast ERV2p is the first microsomal FAD-linked sulfhydryl oxidase of the Erv1p/Alrp protein family.

Saccharomyces cerevisiae Erv2p was identified previously as a distant homologue of Erv1p, an essential mitochondrial protein exhibiting sulfhydryl oxidase activity. Expression of the ERV2 (essential for respiration and vegetative growth 2) gene from a high-copy plasmid cannot substitute for the lack of ERV1, suggesting that the two proteins perform nonredundant functions. Here, we show that the deletion of the ERV2 gene or the depletion of Erv2p by regulated gene expression is not associated with any detectable growth defects. Erv2p is located in the microsomal fraction, distinguishing it from the mitochondrial Erv1p. Despite their distinct subcellular localization, the two proteins exhibit functional similarities. Both form dimers in vivo and in vitro, contain a conserved YPCXXC motif in their carboxyl-terminal part, bind flavin adenine dinucleotide (FAD) as a cofactor, and catalyze the formation of disulfide bonds in protein substrates. The catalytic activity, the ability to form dimers, and the binding of FAD are associated with the carboxyl-terminal domain of the protein. Our findings identify Erv2p as the first microsomal member of the Erv1p/Alrp protein family of FAD-linked sulfhydryl oxidases. We propose that Erv2p functions in the generation of microsomal disulfide bonds acting in parallel with Ero1p, the essential, FAD-dependent oxidase of protein disulfide isomerase.

Amino Acid Motifs↗

Organotypic hippocampal cultures. A model of brain tissue damage in Streptococcus pneumoniae meningitis.

Hippocampal slices of newborn rats were exposed to either heat-inactivated Streptococcus pneumoniae R6 (hiR6) equivalent to 10(6) and 10(8) CFU/ml, lipoteichoic acid (LTA) (0.3 microg/ml and 30 microg/ml), peptidoglycans (PG) (0.3, 30, 50 and 100 microg/ml), pneumococcal DNA (pDNA) (0.3 and 30 microg/ml) or medium only (control). Cell injury was examined by Nissl staining, Annexin V and NeuN immunohistochemistry, and quantified by propidium iodide (PI) uptake and by determining neuron-specific enolase (NSE) concentration in the culture medium. Necrotic and apoptotic cell damage occurred in all treatment groups. Overall damage (Nissl and PI staining) was most prominent after hiR6 (10(8) CFU/ml), followed by LTA (30 microg/ml), pDNA (30 microg/ml), and not detectable after PG (30 microg/ml) exposure. PG (100 microg/ml) induced severe damage. Apoptotic cells were most frequent after exposure to LTA and hiR6. Damage in the neuronal cell layers (NeuN, NSE) was most severe after treatment with hiR6 (10(8) CFU/ml), followed by PG (100 microg/ml), pDNA (30 microg/ml), and LTA (30 microg/ml).

Animals↗

Reduced release of DNA from streptococcus pneumoniae after treatment with rifampin in comparison to spontaneous growth and ceftriaxone treatment.

In order to study the release of DNA from Streptococcus pneumoniae in vitro during spontaneous growth and treatment with ceftriaxone or rifampin, a semiquantitative polymerase chain reaction was used. During spontaneous growth, high concentrations of bacterial DNA were released. Exposure to 10 microg/ml of ceftriaxone decreased the DNA release, in median, by 19 times (P=0.03 vs. spontaneous growth). Treatment with 10 microg/ml of rifampin led to a reduction of DNA release, in median, by a factor of 49 (P=0.03 vs. ceftriaxone; six experiments performed on different days).

Base Sequence↗

A mouse model of Streptococcus pneumoniae meningitis mimicking several features of human disease.

The course of bacterial titers, meningeal inflammation, behavioral abnormalities, and neuronal damage was studied in a mouse model of Streptococcus pneumoniae meningitis. At 24 h after injection of 10(4) colony-forming units (CFU) S. pneumoniae into the right forebrain, infected mice became severely lethargic. Bacterial titers in cerebrospinal fluid and cerebellum rose to 10(9) CFU/ml, with strong granulocyte invasion into the meninges and neuronal necroses in the neocortex, striatum and hippocampal formation. Meningeal inflammation and neuronal damage in intercellular cell adhesion molecule-1- and macrophage colony-stimulating factor-deficient mice was similar to that in wild-type littermates. Untreated, the infection was fatal. Wild-type mice treated earlier than 24 h after infection with ceftriaxone (2 mg every 12 h for 3 days) survived without apparent behavioral abnormalities. Delay of treatment beyond 30 h led to the death of more than 50% of the infected mice. This mouse model is suitable for therapeutic studies and for the investigation of inflammation in knockout mice. The neuronal damage resembles morphological abnormalities observed in humans.

Animals↗

Oats and soy in lipid-lowering diets for women with hypercholesterolemia: is there synergy?

OBJECTIVES: To study possible synergistic effects of oats and soy on reducing total and low-density lipoprotein cholesterol (LDL-C) concentrations in human beings and the efficacy and feasibility of including these adjustments to a National Cholesterol Education Program Step I diet. SUBJECT/SETTING: One hundred twenty-seven postmenopausal women with moderate hypercholesterolemia were recruited from a large Midwestern workforce and senior centers in the surrounding community. Intervention and clinical visits were conducted in these same facilities. DESIGN: After a 3-week lead-in period on the Step I diet, participants were randomly assigned to 1 of 4 dietary treatments for an additional 6 weeks: an oats/milk group, a wheat/soy group, an oats/soy group, and a wheat/milk group. Clinical measurements included blood draws, body weight and height, blood pressure, and medical history data. Three-day food records were collected at baseline and Weeks 3 and 9 of the intervention. Randomization was stratified based on the status of hormone replacement therapy and was blocked with sizes 4 or 8 for group assignment. RESULTS: After 3 weeks on the Step I diet, total cholesterol, LDL-C, and triglyceride levels; total fat and saturated fat intake, dietary cholesterol intake, Keys score, and body mass index were all reduced. Following an additional 6 weeks on the Step I diet plus intervention, total cholesterol and LDL-C were further reduced for both the oats/soy group and oats/milk group. There were no significant further changes in total cholesterol, LDL-C, or high-density lipoprotein cholesterol levels in the wheat/soy and wheat/milk groups. Body mass index remained stable in all groups from Week 3 to Week 9. APPLICATIONS: Nonpharmacologic dietary interventions like the Step I diet are feasible in a community setting and can produce rapid and significant lipid-lowering benefits. Daily consumption of 2 servings of oats can contribute to further lipid alterations in this population although soy intake at this dose may not. Palatability and convenience are important considerations in achieving dietary adherence.

Aged↗

D- and L-lactate in rabbit and human bacterial meningitis.

Increased total CSF lactate is an important indicator differentiating bacterial from aseptic meningitis. Bacteria can produce D- and L-lactate; mammalian cells produce only L-lactate. We measured D- and L-lactate production of Streptococcus pneumoniae, Staphylococcus aureus, Neisseria meningitidis and Escherichia coli in vitro, of S. pneumoniae and E. coli in rabbit experimental meningitis and of various common pathogens in CSF from patients with bacterial meningitis. Despite marked in vitro production of D-lactate by S. aureus (maximum: 4.59 mmol/l; i.e. 34.9% of total lactate), N. meningitidis (4.62 mmol/l; i.e. 98.1%) and E. coli (3.14 mmol/l; i.e. 97.2%), minimal amounts were measured in human S. aureus (0.38 mmol/l; i.e. 1.3% of total lactate) or N. meningitidis (0.28 mmol/l; i.e. 3.9%) and experimental E. coli meningitis (0.75 mmol/l; i.e. 4.4%). In only 9 of 54 human CSF samples did D-lactate exceed 0.15 mmol/l. S. pneumoniae did not produce significant amounts of D-lactate in vitro (maximum: 0.55 mmol/l; i.e. 2.7% of total lactate), in experimental meningitis (0.18 mmol/l; i.e. 3%) or in human cases of meningitis (0.28 mmol/l; i.e. 1.9%). In conclusion, increased total CSF lactate in meningitis consists mainly of L-lactate and originates predominantly from host cells. CSF D-lactate is of limited diagnostic value.

Animals↗

An essential function of the mitochondrial sulfhydryl oxidase Erv1p/ALR in the maturation of cytosolic Fe/S proteins.

Biogenesis of Fe/S clusters involves a number of essential mitochondrial proteins. Here, we identify the essential Erv1p of Saccharomyces cerevisia mitochondria as a novel component that is specifically required for the maturation of Fe/S proteins in the cytosol, but not in mitochondria. Furthermore, Erv1p was found to be important for cellular iron homeostasis. The homologous mammalian protein ALR ('augmenter of liver regeneration'), also termed hepatopoietin, can functionally replace defects in Erv1p and thus represents the mammalian orthologue of yeast Erv1p. Previously, a fragment of ALR was reported to exhibit an activity as an extracellular hepatotrophic growth factor. Both Erv1p and full-length ALR are located in the mitochondrial intermembrane space and represent the first components of this compartment with a role in the biogenesis of cytosolic Fe/S proteins. It is likely that Erv1p/ALR operates downstream of the mitochondrial ABC transporter Atm1p/ABC7/Sta1, which also executes a specific task in this essential biochemical process.

Cytoplasm↗

Expression of death-related proteins in dentate granule cells in human bacterial meningitis.

Neuronal apoptosis in the dentate gyrus has been observed in animal models of bacterial meningitis and in humans dying in the course of the disease. To evaluate the mechanisms of neuronal cell death, hippocampal sections of 20 patients dying from bacterial meningitis were investigated by immunohistochemistry using antibodies against the proform of caspase-3 and the active enzyme, bcl-2, bax and p53. In the dentate granule cell layer, the median density of neurons with an apoptotic morphology was 7.6/mm2 (0-15.6/mm2). The median density of immunoreactive neurons was 2.3/mm2 (procaspase-3), 0.9/mm2 (activated caspase-3), 1.8/mm2 (bcl-2), 1.1/mm2 (bax) and 0.4/mm2 (p53). 80% of neurons immunoreactive for active caspase-3 had an apoptotic morphology, whereas only 10% of all procaspase-3 stained neurons showed signs of apoptosis. Apoptotic cell death is present in humans dying in the course of bacterial meningitis in the dentate gyrus of the Formatio hippocampi. Neuronal expression of caspase-3, bcl-2 and bax suggests an involvement of these proteins in neuronal death.

Adolescent↗

Optimal focusing by spatio-temporal inverse filter. I. Basic principles.

A focusing technique based on the inversion of the propagation operator relating an array of transducers to a set of control points inside a medium was proposed in previous work [Tanter et al., J. Acoust. Soc. Am. 108, 223-234 (2000)] and is extended here to the time domain. As the inversion of the propagation operator is achieved both in space and time, this technique allows calculation of the set of temporal signals to be emitted by each element of the array in order to optimally focus on a chosen control point. This broadband inversion process takes advantage of the singular-value decomposition of the propagation operator in the Fourier domain. The physical meaning of this decomposition is explained in a homogeneous medium. In particular, a definition of the number of degrees of freedom necessary to define the acoustic field generated by an array of limited aperture in a focal plane of limited extent is given. This number corresponds to the number of independent signals that can be created in the focal area both in space and time. In this paper, this broadband inverse-focusing technique is compared in homogeneous media with the classical focusing achieved by simple geometrical considerations but also with time-reversal focusing. It is shown that, even in a simple medium, slight differences appear between these three focusing strategies. In the companion paper [Aubry et al., J. Acoust. Soc. Am. 110, 48-58 (2001)] the three focusing techniques are compared in heterogeneous, absorbing, or complex media where classical focusing is strongly degraded. The strong improvement achieved by the spatio-temporal inverse-filter technique emphasizes the great potential of multiple-channel systems having the ability to apply completely different signal waveforms on each transducer of the array. The application of this focusing technique could be of great interest in various ultrasonic fields such as medical imaging, nondestructive testing, and underwater acoustics.

Echoencephalography↗

Optimal focusing by spatio-temporal inverse filter. II. Experiments. Application to focusing through absorbing and reverberating media.

To focus ultrasonic waves in an unknown heterogeneous medium using a phased array, one has to calculate the optimal set of signals to be applied on the transducers of the array. (In most applications of ultrasound, medical imaging, medical therapy, nondestructive testing, the first step consists of focusing a broadband ultrasound beam deeply inside the medium to be investigated.) Focusing in a homogeneous medium simply requires to compensate for the varying focus-array elements geometrical distances. Nevertheless, heterogeneities in the medium, in terms of speed of sound, density, or absorption, may strongly degrade the focusing. Different techniques have been developed in order to correct such aberrations induced by heterogeneous media (time reversal, speckle brightness, for example). In the companion to this paper, a new broadband focusing technique was investigated: the spatio-temporal inverse filter. Experimental results obtained in various media, such as reverberating and absorbing media, are presented here. In particular, intraplate echoes suppression and high-quality focusing through a human skull, as well as hyper-resolution in a reverberating medium, will be shown. It is important to notice that all these experiments were performed with fully programmable multichannel electronics whose use is required to fully exploit the spatio-temporal technique.

Echoencephalography↗

Activity of LY333328 in experimental meningitis caused by a Streptococcus pneumoniae strain susceptible to penicillin.

In a rabbit model of Streptococcus pneumoniae meningitis single doses of 10 and 2.5 mg of the glycopeptide LY333328 per kg of body weight reduced bacterial titers in cerebrospinal fluid (CSF) almost as rapidly as ceftriaxone at 10 mg/kg/h (changes in log CFU, -0.29 +/- 0.21 and -0.26 +/- 0.22 versus -0.34 +/- 0.15/ml/h). A dose of 1 mg/kg was bacteriostatic (change in log CFU, 0.01 +/- 0.11/ml/h). In two animals receiving LY333328 at a dose of 40 mg/kg the bacterial titers were reduced by 0.54 and 0.51 log CFU/ml/h. The penetration of CSF by LY333328 was 1 to 5%. The concentrations of lipoteichoic and teichoic acids in CSF and neuronal damage were similar in ceftriaxone- and LY333328-treated animals.

Animals↗

Effect of deficiency of tumor necrosis factor alpha or both of its receptors on Streptococcus pneumoniae central nervous system infection and peritonitis.

Tumor necrosis factor alpha (TNF-alpha) and TNF-beta are key mediators in bacterial inflammation. We therefore examined the role of TNF-alpha and its two receptors in murine pneumococcal central nervous system infection. TNF-alpha knockout mice and age- and sex-matched controls and TNF receptor (p55 and p75)-deficient mice and heterozygous littermates were infected intracerebrally with a Streptococcus pneumoniae type 3 strain. Mice were monitored until death or were killed 36 h after infection. Bacterial titers in blood, spleen, and brain homogenates were determined. Leukocyte infiltration and neuronal damage were assessed by histological scores. TNF-alpha-deficient mice died earlier than the controls after intracerebral infection although overall survival was similar. TNF-alpha deficiency did not inhibit leukocyte recruitment into the subarachnoid space and did not lead to an increased density of bacteria in brain homogenates. However, it caused a substantial rise of the concentration of S. pneumoniae cells in blood and spleen. Spleen bacterial titers were also increased in p55- and p75-deficient mice. TNF receptor-deficient mice showed decreased meningeal inflammation. Neuronal damage was not affected by either TNF-alpha or TNF receptor deficiency. In a murine model of pneumococcal peritonitis, 10(2) CFU of S. pneumoniae produced fatal peritonitis in TNF-alpha-deficient, but not wild-type, mice. Early leukocyte influx into the peritoneum was impaired in TNF-alpha-deficient mice. The lack of TNF-alpha or its receptors renders mice more susceptible to S. pneumoniae infections.

Adult↗

Leukocyte filtration in the early reperfusion phase on cardiopulmonary bypass reduces myocardial injury.

Improved myocardial protection and cardiopulmonary bypass (CPB) have limited, but not abolished, intraoperative myocardial damage due to surgical reperfusion injury after release of the aortic crossclamp. In this double-blind, randomized study, we evaluated whether short-term leukocyte filtration during reperfusion may further reduce myocardial damage. Thirty-eight patients with coronary artery disease were randomly assigned to CPB with (group I; n = 19) or without leukocyte filtration (group II; n = 19). There was no difference in bypass time or crossclamp time between the groups. No patient in group I required catecholamines, whereas three patients in group II were supported with adrenaline or dobutamine on the first and second postoperative day. In addition, troponin T plasma levels were lower in group I (p < 0.05), whereas other markers for tissue injury (CK, CK-MB, LDH, S-GOT and S100B) did not differ. In conclusion, leukocyte filtration during reperfusion may further improve CPB by reducing myocardial damage.

Aged↗