Biomedical subjects

B Wenzel

Publications and source records attributed to B Wenzel.

At least 19 recordsLinked to original sources

PubMed2002

mAChRs in the grasshopper brain mediate excitation by activation of the AC/PKA and the PLC second-messenger pathways.

The species-specific sound production of acoustically communicating grasshoppers can be stimulated by pressure injection of both nicotinic and muscarinic agonists into the central body complex and a small neuropil situated posterior and dorsal to it. To determine the role of muscarinic acetylcholine receptors (mAChRs) in the control of acoustic communication behavior and to identify the second-messenger pathways affected by mAChR-activation, muscarinic agonists and membrane-permeable drugs known to interfere with specific mechanisms of intracellular signaling pathways were pressure injected to identical sites in male grasshopper brains. Repeated injections of small volumes of muscarine elicited stridulation of increasing duration associated with decreased latencies. This suggested an accumulation of excitation over time that is consistent with the suggested role of mAChRs in controlling courtship behavior: to provide increasing arousal leading to higher intensity of stridulation and finally initiating a mating attempt. At sites in the brain where muscarine stimulation was effective, stridulation could be evoked by forskolin, an activator of adenylate cyclase (AC); 8-Br-cAMP-activating protein kinase A (PKA); and 3-isobuty-1-methylxanthine, leading to the accumulation of endogenously generated cAMP through inhibition of phosphodiesterases. This suggested that mAChRs mediate excitation by stimulating the AC/cAMP/PKA pathway. In addition, muscarine-stimulated stridulation was inhibited by 2'-5'-dideoxyadenonsine and SQ 22536, two inhibitors of AC; H-89 and Rp-cAMPS, two inhibitors of PKA; and by U-73122 and neomycin, two agents that inhibit phospholipase C (PLC) by independent mechanisms. Because the inhibition of AC, PKA, or PLC by various individually applied substances entirely suppressed muscarine-evoked stridulation in a number of experiments, activation of both pathways, AC/cAMP/PKA and PLC/IP(3)/diacylglycerine, appeared to be necessary to mediate the excitatory effects of mAChRs. With these studies on an intact "behaving" grasshopper preparation, we present physiological relevance for mAChR-evoked excitation mediated by sequential activation of the AC- and PLC-initiated signaling pathways that has been reported in earlier in vitro studies.

Acetylcholine↗

PubMed2001

A role for muscarinic excitation: control of specific singing behavior by activation of the adenylate cyclase pathway in the brain of grasshoppers.

Muscarinic acetylcholine receptors exert slow and prolonged synaptic effects in both vertebrate and invertebrate nervous systems. Through activation of G proteins, they typically decrease intracellular cAMP levels by inhibition of adenylate cyclase or stimulate phospholipase C and the turnover of inositol phosphates. In insects, muscarinic receptors have been credited with two main functions: inhibition of transmitter release from sensory neuron terminals and regulation of the excitability of motoneurons and interneurons. Our pharmacological studies with intact and behaving grasshoppers revealed a functional role for muscarinic acetylcholine receptors as being the basis for specific arousal in defined areas of the brain, underlying the selection and control of acoustic communication behavior. Periodic injections of acetylcholine into distinct areas of the brain elicited songs of progressively increasing duration. Coinjections of the muscarinic receptor antagonist scopolamine and periodic stimulations with muscarine identified muscarinic receptor activation as being the basis for the underlying accumulation of excitation. In contrast to reports from other studies on functional circuits, muscarinic excitation was apparently mediated by activation of the adenylate cyclase pathway. Stimulation of adenylate cyclase with forskolin and of protein kinase A with 8-Br-cAMP mimicked the stimulatory effects of muscarine whereas inhibition of adenylate cyclase with SQ22536 and of protein kinase A with H-89 and Rp-cAMPs suppressed muscarine-stimulated singing behavior. Activation of adenylate cyclase by muscarinic receptors has previously been reported from studies on membrane preparations and heterologous expression systems, but a physiological significance of this pathway remained to be demonstrated in an in vivo preparation.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed2001

Pharmacological brain stimulation releases elaborate stridulatory behaviour in gomphocerine grasshoppers--conclusions for the organization of the central nervous control.

Grasshoppers produce a variety of sounds generated by complex movements of the hindlegs. Stridulation, performed in the context of partner finding, mating and rivalry, can be released by pressure injection of cholinergic agonists into the protocerebrum. Particularly stimulation with muscarinic agonists induced long-lasting stridulation that resembled the natural behaviour to an astonishing degree, not only with respect to their temporal structure and right/left coordination, but also to changes in the song sequences according to the progress of courtship stridulation, even including accessory movements of other parts of the body. According to the complexity of their stridulatory behaviour ten gomphocerine species were chosen for this comparative study. The results indicate that the protocerebrum fulfils two important tasks in the control of stridulation: (1) it integrates sensory input relevant to stridulation that represents a certain behavioural situation and internal state of arousal, and (2) it selectively activates and deactivates the thoracic networks that generate the appropriate movement and sound patterns. With the knowledge of the natural behaviour and the accessibility to pharmacological and electrophysiological studies, the cephalic control system for stridulation in grasshoppers appears to be a suitable model for how the brain selects and controls appropriate behaviours for a given situation.

Animal Communication↗

PubMed2000

Design and evolution of the data management systems in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial.

This paper describes the design and evolution of the data management systems developed in support of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. These systems span platforms from stand-alone computers to distributed systems on local area networks to mainframes. Allowing all of these systems to share appropriate information electronically introduces integration, synchronization, testing, and support challenges. For each platform, applications were developed to handle data entry, editing, trial management, reporting, telecommunications, and data sharing. Approaches to issues such as level of data access, integration with other, existing applications, and handling the expansion of the protocol are discussed.

Colorectal Neoplasms↗

PubMed1999

Substrate inhibition and affinities of the glyoxysomal beta-oxidation of sunflower cotyledons

During the glyoxysomal beta-oxidation of long-chain acyl-CoAs, short-chain intermediates accumulate transiently (Kleiter and Gerhardt 1998, Planta 206: 125-130). The studies reported here address the underlying factors. The studies concentrated upon the aspects of (i) chain length specificity and (ii) metabolic regulation of the glyoxysomal beta-oxidation of sunflower (Helianthus annuus L.) cotyledons. (i) Concentration-rate curves of the beta-oxidation of acyl-CoAs of various chain lengths showed that the beta-oxidation activity towards long-chain acyl-CoAs was higher than that towards short-chain acyl-CoAs at substrate concentrations <20 &mgr;M. At substrate concentrations >20 &mgr;M, long-chain acyl-CoAs were beta-oxidized more slowly than short-chain acyl-CoAs because the beta-oxidation of long-chain acyl-CoAs is subject to substrate inhibition which had already started at 5-10 &mgr;M substrate concentration and results from an inhibition of the multifunctional protein (MFP) of the beta-oxidation reaction sequence. However, low concentrations of free long-chain acyl-CoAs are rather likely to exist within the glyoxysomes due to the acyl-CoA-binding capacity of proteins. Consequently, the beta-oxidation rate towards a parent long-chain acyl-CoA will prevail over that towards the short-chain intermediates. (ii) Low concentrations (</=5 &mgr;M) of a long-chain acyl-CoA exerted an inhibitory effect on the beta-oxidation rate of butyryl-CoA. Reversibility of the inhibition was observed as well as metabolization of the inhibiting long-chain acyl-CoA. Regarding the activities of the individual beta-oxidation enzymes towards their C(4) substrates in the presence of a long-chain acyl-CoA, the MFP activity exhibited strong inhibition. This inhibition appears not to be due to the detergent-like physical properties of long-chain acyl-CoAs. The results of the studies, which are consistent with the observation that short-chain intermediates accumulate transiently during complete degradation of a long-chain acyl-CoA, suggest that the substrate concentration-dependent chain-length specificity of the beta-oxidation and a metabolic regulation at the level of MFP are factors determining this transient accumulation.

Journal Article↗

PubMed1999

Neurochemical control of cricket stridulation revealed by pharmacological microinjections into the brain.

Neuroactive substances were administered into the frontal protocerebrum of tethered male Gryllus bimaculatus by pressure injections from microcapillaries. All three types of species-specific song pattern (calling song, rivalry song and courtship song) could be elicited by injection of acetylcholine and cholinergic agonists. Injection of nicotine led to short bouts of calling song that occurred after a short latency. In contrast, muscarine elicited long-lasting stridulation that took longer to develop. The pharmacologically induced song patterns showed transitions from rivalry song to calling song and from calling song to courtship song, which also occur during natural behaviour. Stridulation induced by a cholinergic agonist could be immediately blocked by microinjection of (&ggr;)-aminobutyric acid (GABA) into the same neuropile sites. Administration of picrotoxin in resting crickets led to enhanced motor activity that incorporated the three different song patterns. We propose that, in the brain of the cricket, acetylcholine and GABA are putative transmitters involved in the control of stridulation. Histological analysis located the stimulation sites to an area between the pedunculus and the (&agr;)-lobe of the mushroom body in which the command neurons for calling song have dendritic arborizations.

Journal Article↗

PubMed1998

In old age the majority of thyroid peroxidase autoantibodies are directed to a single TPO domain irrespective of thyroid function and iodine intake.

OBJECTIVE: We have examined (1) which epitopes on thyroid peroxidase (TPO) are recognized by TPO autoantibodies (TPO-Aab) in old age and to what extent? (2) Does the TPO-Aab pattern differ in euthyroid and hypothyroid elderly subjects or does it depend on their iodine intake? DESIGN: TPO-Aab positive sera obtained from a screening study of nursing-home residents living in areas of varying iodine intake were tested by competition studies with monoclonal antibodies (mAbs) recognizing different epitopes on TPO. SUBJECTS: The nursing-home residents with TPO-Aab positivity were from (A) an iodine abundant area (Eastern Hungary, median iodine excretion -MIE-: 0.462 mumol/mmol creatinine, N = 13); (B) an area of obligatory iodinated salt prophylaxis since the 1950s (Slovakia, MIE: 0.090 mumol/mmol creatinine, N = 11); (C) a moderately iodine-deficient area (Northern Hungary, MIE: 0.065 mumol/mmol creatinine, N = 13). MEASUREMENTS: Thirteen murine TPO antibodies generated against several epitopes of the four (A, B, C, D) antigenic domains on the TPO were co-incubated with the TPO-Aab positive sera on TPO coated microtitre plates. The amount of mAb bound was estimated after further incubation with goat anti-mouse antibodies, conjugated with horseradish peroxidase and tetramethylbenzidine as chromogen. The TPO-Aab positive sera were characterized by the pattern of percentage of inhibition of mAb binding caused by the TPO-Aabs. RESULTS: TPO-Aabs inhibited only the binding of mAbs raised against the antigenic domains A (mAb9, mAb2, mAb60) and B (mAb64, mAb59, mAb18, mAb15). The extent of inhibition depended upon the TPO-Aab titre but in all cases the binding of mAb9 was inhibited to the highest degree. The percentage inhibition of mAb9 was (a) 34 +/- 17% (M +/- SD) caused by sera (N = 8) with TPO-Aab titre 1/100-1/200 (higher than that of all mAbs recognizing domain B, P < 0.01-P < 0.001), (b) 76 +/- 18% caused by sera (N = 14) with TPO-Aab titre 1/1000 (higher than that of all other mAbs -P < 0.01-P < 0.001, except mAb64), (c) 99 +/- 4% caused by sera (N = 15) with TPO-Aab titre 1/4000-1/16,000 (higher than that of all other mAbs, P < 0.01-P < 0.001). Thus, only mAb9 was inhibited completely by high titres of TPO-Aabs. The qualitative and quantitative distribution pattern of mAb inhibition was similar in the subgroups of elderly hypothyroid and euthyroid subjects with comparable TPO-Aab levels, as well as in the subgroups with varying iodine intake. CONCLUSIONS: (1) In old age, there is a polyclonal TPO autoantibody response but the majority of the autoantibodies are directed to the TPO region mapped by or close to mAb9 (domain A); (2) the autoantibody response does not differ in elderly subjects with or without the clinical manifestations of autoimmune thyroid disease and does not depend on the iodine supply of the elderly subjects.

Aged↗

PubMed1995

Molecular cloning, sequencing and sequence analysis of the fox-2 gene of Neurospora crassa encoding the multifunctional beta-oxidation protein.

We present the molecular cloning and sequencing of genomic and cDNA clones of the fox-2 gene of Neurospora crassa, encoding the multifunctional beta-oxidation protein (MFP). The coding region of the fox-2 gene is interrupted by three introns, one of which appears to be inefficiently spliced out. The encoded protein comprises 894 amino acid residues and exhibits 45% and 47% sequence identity with the MFPs of Candida tropicalis and Saccharomyces cerevisiae, respectively. Sequence analysis identifies three regions of the fungal MFPs that are highly conserved. These regions are separated by two segments that resemble linkers between domains of other MFPs, suggesting a three-domain structure. The first and second conserved regions of each MFP are homologous to each other and to members of the short-chain alcohol dehydrogenase family. We discuss these homologies in view of recent findings that fungal MFPs contain enoyl-CoA hydratase 2 and D-3-hydroxyacyl-CoA dehydrogenase activities, converting trans-2-enoyl-CoA via D-3-hydroxyacyl-CoA to 3-ketoacyl-CoA. In contrast to its counterparts in yeasts, the Neurospora MFP does not have a C-terminal sequence resembling the SKL motif involved in protein targeting to microbodies.

3-Hydroxyacyl CoA Dehydrogenases↗

PubMed1994

T lymphocytes, CD68-positive cells and vascularisation in thyroid carcinomas.

Immunohistochemical detection and quantification of CD3- and CD45RO-positive lymphocytes and CD68-positive cells in 75 thyroid carcinomas of follicular cell origin revealed rising levels for these parameters associated with dedifferentiation. A parallel trend towards reduction of vascularisation, determined as CD31-positive blood vessels, with decreasing differentiation became evident, statistically only significant when well-differentiated follicular and anaplastic carcinomas were compared. Positive correlations could be demonstrated between the density of CD68-, CD3-, and CD45RO-positive cells as well as between the density of CD68-, and CD3-, and CD45RO-positive cells and vascularisation. These correlations were expected, as the interaction of CD68-positive cells and T lymphocytes results in the production of angiogenesis factors, ultimately leading to better vascularisation of the tumour. Nevertheless, the tumour cells themselves are variously capable of producing angiogenic substances. The obvious lack of positive correlation between the density of tumour-infiltrating cells determined in this study and vascularisation, despite reduced vascularisation in less differentiated tumours that contained increasing numbers of tumour-infiltrating cells, seems to be due to functional heterogeneity of morphologically similar tumours.

Antibodies, Monoclonal↗

PubMed1993

Analysis of cytokine profiles in synovial T cell clones from chlamydial reactive arthritis patients: predominance of the Th1 subset.

Subpopulations of human T cells (Th0, Th1 and Th2) can be distinguished by their cytokine-secretion pattern. Evidence is increasing from other studies that the outcome of a human disease may depend on the subpopulation of T cells that predominates at the site of inflammation. Reactive arthritis serves as a useful model of chronic inflammatory diseases, because the triggering antigen can be identified. Using this triggering antigen we raised 33 T cell clones reactive with Chlamydia trachomatis and 25 T cell clones that were not reactive, all from the synovial fluid of two patients suffering from Chlamydia-induced arthritis. Their cytokine secretion patterns for interferon-gamma (IFN-gamma), IL-2 and IL-4 were analysed, as also were mRNAs for IFN-gamma and IL-10 by in situ hybridization. Out of the 33 antigen-reactive clones 23 showed a Th1 pattern with IFN-gamma but not IL-4 secretion, while the remaining 10 exhibited a Th0 pattern. The clones that did not react with Chlamydia expressed all patterns of cytokine secretion, including a Th2 pattern, thus providing a control population that excludes bias in the sampling procedure. CD4 and CD8 clones displayed a similar cytokine-secretion pattern. In addition this study demonstrates for the first time the expression of IL-10 mRNA in T cell clones derived from synovial fluid, and this was not confined to the Th2 subset. The Th1 response that Chlamydia provoke can be regarded as appropriate for such an obligate intracellular pathogen.

Adult↗

PubMed1992

In situ hybridization of the mRNA for interferon-gamma, interferon-alpha E, interferon-beta, interleukin-1 beta and interleukin-6 and characterization of infiltrating cells in thyroid tissues.

Cytokine mRNA production in the thyroid tissues of patients with various thyroid diseases was analysed by in situ hybridization. In addition, infiltrating leukocytes were characterized by immunohistologic studies using the alkaline phosphatase anti-alkaline phosphatase (APAAP) staining technique. The following clinical material was investigated: two cases of Graves' disease, one with high and the other with a low amount of infiltrating leukocytes as well as two cases of non-toxic goitre also showing considerable quantities of infiltrating cells. The hybridization was performed on tissue sections with antisense probes for interferon-gamma (IFN-gamma), IFN-alpha E, IFN-beta, interleukin-6 (IL-6) and IL-1 beta. A small number of individual cells were found to express high levels of mRNA for IFN-gamma, IL-1 beta and measurable amounts of IL-6 throughout the tissue sections. However, IFN-alpha E or IFN-beta were not detected. Cytokine expressing cells were noted in the tissue of one patient with Graves' disease and in two cases with non-toxic goitre. In these samples a high amount of infiltrating leukocytes (CD45+) was detected, especially CD3+, CD8+, CD4+ and CD45RA+ T cells, in addition to B cells and macrophages. In one case an unusually large amount of T cell receptor gamma/delta+ (TcR gamma/delta+) cells was found. However, one sample of thyroid tissue derived from a patient with Graves' disease was poorly infiltrated and showed few cells expressing cytokines. In conclusion, using thyroid tissue as an example, our data suggest that the application of in situ hybridization with antisense RNA permits the study of cytokine production in tissues of both autoimmune and non-autoimmune origin.

Adult↗

PubMed1992

Peroxisomal multifunctional beta-oxidation protein of Saccharomyces cerevisiae. Molecular analysis of the fox2 gene and gene product.

The gene encoding the multifunctional protein (MFP) of peroxisomal beta-oxidation in Saccharomyces cerevisiae was isolated from a genomic library via functional complementation of a fox2 mutant strain. The open reading frame consists of 2700 base pairs encoding a protein of 900 amino acids. The predicted molecular weight (98,759) is in close agreement with that of the isolated polypeptide (96,000). Analysis of the deduced amino acid sequence revealed similarity to the MFPs of two other fungi but not to that of rat peroxisomes or the multifunctional subunit of the Escherichia coli beta-oxidation complex. The FOX2 gene was overexpressed from a multicopy vector (YEp352) in S. cerevisiae and the gene product purified to apparent homogeneity. A truncated version of MFP lacking 271 carboxyl-terminal amino acids was also overexpressed and purified. Experiments to study the enzymatic properties of the wild-type MFP demonstrated an absence of activities originally assigned to an MFP of S. cerevisiae (crotonase, L-3-hydroxyacyl-CoA dehydrogenase, and 3-hydroxyacyl-CoA epimerase), whereas two other activities were found: 2-enoyl-CoA hydratase 2 (converting trans-2-enoyl-CoA to D-3-hydroxyacyl-CoA) and D-3-hydroxyacyl CoA dehydrogenase (converting D-3-hydroxyacyl-CoA to 3-ketoacyl-CoA). The truncated form contained only the D-3-hydroxyacyl-CoA dehydrogenase activity. These results clearly demonstrate that the beta-oxidation of fatty acids in S. cerevisiae follows a previously unknown stereochemical course, namely it occurs via a D-3-hydroxyacyl-CoA intermediate.

3-Hydroxyacyl CoA Dehydrogenases↗

PubMed1990

Regional cerebral blood flow during focal seizures of temporal and frontocentral onset.

Ictal single photon emission computed tomography recordings were performed in 9 patients in the course of 11 seizures. Injections of radionuclide were made an average of 72 seconds after the onset of the seizure as indicated by electroencephalography. All patients also underwent interictal recordings. In 6 patients, the localization of the electroencephalographic focus and the morphological lesions corresponded with the ictal hyperperfusion. This could be seen in single photon emission computed tomography. Seizures triggered by hyperventilation, and seizures of patients with anatomical brain lesions (e.g., cysts, surgical defects, and recent injections of technetium-hexamethylene-propylene-amine-oxime) showed an absent or noncorresponding localization of the ictal recording. The ictal and interictal recording seems suitable as a confirmatory noninvasive method for the localization of the epileptogenic focus, particularly in the preoperative evaluation of epilepsy.

Adolescent↗

PubMed1990

[Direct capping of the artificial exposed pulp in teeth with deep caries].

We carried out clinical and histological investigations on teeth with superficial and deep caries in which we made an artificial exposure of the pulp to check the reactivity of the endodont. After one year we observed using clinical and x-ray methods successful treatment in 93.4% of the teeth. Histologically the number of successful treatment was 100.0% in teeth with superficial caries and 80.0% in teeth with deep caries.

Adolescent↗

PubMed1985