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Biomedical subjects

M Kiessling

Publications and source records attributed to M Kiessling.

At least 37 records · Page 2Linked to original sources
PubMed1997

Effect of global system for mobile communication microwave exposure on the genomic response of the rat brain.

The acute effect of global system for mobile communication (GSM) microwave exposure on the genomic response of the central nervous system was studied in rats by measuring changes in the messenger RNAs of hsp70, the transcription factor genes c-fos and c-jun and the glial structural gene GFAP using in situ hybridization histochemistry. Protein products of transcription factors, stress proteins and marker proteins of astroglial and microglial activation were assessed by immunocytochemistry. Cell proliferation was evaluated by bromodeoxyuridine incorporation. A special GSM radiofrequency test set, connected to a commercial cellular phone operating in the discontinuous transmission mode, was used to simulate GSM exposure. The study was conducted at time averaged and brain averaged specific absorption rates of 0.3 W/kg (GSM exposure), 1.5 W/kg (GSM exposure) and 7.5 W/kg (continuous wave exposure), respectively. Immediately after exposure, in situ hybridization revealed slight induction of hsp70 messenger RNA in the cerebellum and hippocampus after 7.5 W/kg exposure, but not at lower intensities. A slightly increased expression of c-fos messenger RNA was observed in the cerebellum, neocortex and piriform cortex of all groups subjected to immobilization, but no differences were found amongst different exposure conditions. C-jun and GFAP messenger RNAs did not increase in any of the experimental groups. 24 h after exposure, immunocytochemical analysis of FOS and JUN proteins (c-FOS, FOS B, c-JUN JUN B, JUN D), of HSP70 or of KROX-20 and -24 did not reveal any alterations. Seven days after exposure, neither increased cell proliferation nor altered expression of astroglial and microglial marker proteins were observed. In conclusion, acute high intensity microwave exposure of immobilized rats may induce some minor stress response but does not result in lasting adaptive or reactive changes of the brain.

Animals↗
PubMed1997

Therapeutic alliance and transference: an exploratory study of their empirical relationship.

Transference and the formation of a therapeutic alliance were studied in 126 patients from the Berlin psychotherapy project. The working hypothesis was that the internalized mother and father image would have an influence on the therapeutic alliance. The therapist rated the development of the therapeutic alliance at two points in time. When the parents' images and the therapist image were compared by using difference and similarity measures, four mother and four father types could be constructed of which some showed significant differences in the formation of therapeutic alliance. The introduction and the discussion are focused on the question as to what extent the psychoanalytic assumptions of transference can be useful in empirical therapy research for the construction of new variables and the explanation of social interactions between the two partners.

Adult↗
PubMed1996

Characterization of genomic alterations associated with glioma progression by comparative genomic hybridization.

Genomic alterations associated with glioma progression were determined by comparative genomic hybridization (CGH) 30 tumors from 15 patients with primary gliomas of World Health Organization (WHO) grade II that on recurrence showed progression to malignant gliomas of WHO grades III or IV (five cases of astrocytoma grade II (A II) to grade III (AA III), five cases of A II to glioblastoma multiforme grade IV (GBM) and five cases of oligodendroglioma grade II (O II) to grade III (AO III)). All tumors were additionally screened for p53 mutations by single strand conformational polymorphism and heteroduplex analysis of exons 5-8, followed by direct sequencing. Mutations of p53 were found in the primary and recurrent tumors of all cases of A II progressing to GBM and three of five cases of A II recurring as AA III. Alterations identified by CGH in more than one primary A II included losses on Xp (3/10) and 5p (2/10), gains on 8q and 19p (2/10 each), and gain/amplification on 12p (2/10). Common progression associated changes found in AA III or GBM were losses on 4q, 9p, 10q, 11p, 13q (4/10 each) and gains on 1q, 6p, 20q (2/10 each). The most frequent amplification site was located on 12p13 (1/10 A II, 3/5 AA III, 1/5 GBM). Other amplified chromosomal regions were 13q32-q34 (1/10 AII, 2/5 GBM), 7q31-qter (1/5 AA III, 1/5 GBM), 12q22-qter and 18p (1/5 AA III). In contrast to the astrocytic gliomas, only one of five oligodendroglial cases showed a p53 mutation. Genetic abnormalities identified by CGH to occur more than once were restricted to four chromosomes (1, 4, 9 and 19). Our results provide a comprehensive overview of the genomic alterations associated with the progression of individual gliomas and substantiate the hypothesis that glioma progression is associated with a cumulative acquisition of multiple genetic changes.

Adult↗
PubMed1996

Recurrent gain of chromosome arm 7q in low-grade astrocytic tumors studied by comparative genomic hybridization.

Consistent tumor-specific chromosomal aberrations have not been described in low-grade astrocytic tumors. The most frequent genetic alterations are mutations of the TP53 tumor suppressor gene and/or loss of heterozygosity (LOH) on 17p that occur in about 30% of the cases in adult patients but that are uncommon in childhood tumors. We used comparative genomic hybridization (CGH) to map DNA copy number alterations in 18 primary low-grade astrocytic tumors (ten adult patients and eight children). A gain of chromosome arm 7q was the most frequent event detected in five of ten astrocytomas (50%) from adult patients, followed by DNA amplification on chromosome arm 8q and gain on 12p (two cases). Loss of chromosomal regions on 1p, 4q, and the X chromosome was observed in two of ten cases [including one patient afflicted with Turner syndrome (45,X)]. In contrast, no consistent changes were observed in low-grade astrocytomas in children. A loss of the X chromosome was the sole aberration detected in two of eight cases using DNA extracted from the normal brain tissue. The findings suggest that a gain of 7q is an early event in the initiation of astrocytomas in adult patients. The discrepant findings in low-grade astrocytic tumors in adults compared to tumors in children support the the hypothesis that there might be different mechanisms responsible for tumor development.

Adolescent↗
PubMed1996

Editing of GluR2 RNA in the gerbil hippocampus after global cerebral ischemia.

Postischemic delayed neuronal death (DND) in CA1 of the gerbil hippocampus is thought to be caused by an abnormal increase of Ca2+ influx into the cell, mediated by excessive activation of glutamate receptors. One subtype of glutamate receptors, the AMPA receptor, is not permeable to calcium ions as long as an edited form of its GluR2 subunit is present. It is possible that global ischemia interferes with the posttranscriptional editing of the GluR2 mRNA and thus leads to calcium influx via the AMPA receptor. In order to test this hypothesis, we examined the extent of GluR2 RNA editing in CA1 and CA3 microdissected from gerbil hippocampus after 5 min of global ischemia and various recirculation intervals. At each interval tested, quality and quantity of mRNA editing in the vulnerable CA1 region were the same as in CA3. Furthermore, postischemic mRNA editing in both hippocampal regions was indistinguishable from editing in untreated control animals. Our results clearly demonstrate that global ischemia does not cause impairment of GluR2 RNA editing, which is thus not responsible for the abnormal calcium permeability of the postischemic cell membrane.

Animals↗
PubMed1996

Detection of complex genetic alterations in human glioblastoma multiforme using comparative genomic hybridization.

The aim of the present study was to detect complex genetic alterations in human glioblastoma multiforme (GBM) by comparative genomic in situ hybridization (CGH). Of the 24 GBM that were examined, increased fluorescence intensities indicating chromosomal polysomy of chromosome 7 and gene amplification at chromosome 7p were found in 42% of the tumors. In addition, signal enhancement of chromosome 19 was present in 29% and at 12q13-15 in 21% of the tumors. We also detected reduction of fluorescence intensities indicating gross deletions on chromosomes 10 (58%), 9p (46%), and 13 (29%). There was a close correlation of CGH results when compared with Southern analysis of the EGFR gene localized on chromosome 7 and loss of heterozygosity detection of chromosome 9 and 10 by microsatellite PCR. A close correlation was also observed between copy number changes of chromosome 7 and deletions of chromosome 10. Amplification of chromosome 12q and deletions of chromosomes 9p and 13 seemed to be complementary in the tumors investigated in the present study.

Adult↗
PubMed1996

Clinically distinct subgroups of glioblastoma multiforme studied by comparative genomic hybridization.

Studies investigating genetic alterations potentially constituting prognostic factors in glioblastoma multiforme (GBM) have centered mainly around amplification events. Comparative genomic hybridization (CGH) is a recent molecular cytogenetic technique that allows the detection of chromosomal imbalances and amplification sites in tumor DNA prepared from fresh or archival material. A group of 94 patients with GBM underwent surgery followed by a standard course of radiotherapy. Neuroradiologic monitoring with gadolinium-enhanced serial magnetic resonance imaging was applied to study the radiologically progression-free interval (RPFI) and tumor regrowth velocity. These parameters provided a clinical estimate of the postoperative tumor regrowth kinetics and yielded two clinically distinct groups. The most pronounced cases were selected from each group, i.e., those with the most favorable and unfavorable prognosis. Two subgroups with a statistically significant difference in RPFI (p < 0.001, Mann-Whitney U test) containing 10 patients each were formed: Subgroup A (slow tumor regrowth kinetics) and subgroup B (fast tumor regrowth kinetics). For a search of chromosomal alterations that might be correlated with tumor regrowth kinetics, we applied CGH to formalin-fixed, paraffin-embedded tumor tissue from these 20 patients. Except for autosomes 18 and 21, all chromosomes were involved at least once in copy-number aberrations. Events commonly associated with GBM, i.e., gains of chromosome 7, complete and partial losses of 9p, 10, and 22q, were not distributed differently between the two subgroups. The following differences were noticeable. Gains (including amplifications) of 12q14-q21 and of 19 were observed more often in subgroup A. Losses of 6q16-qter and parts of 13, and gains of 20, were more frequent in subgroup B. RPFI was significantly shorter for patients without amplification sites than for patients with gene amplification. RPFI did not differ significantly between patients with or without 7p12 amplification, where the epidermal growth factor receptor gene is localized. New amplification sites for GEM tumors were revealed at 11q13 and 11q22-q23. Loss of chromosome 10 was restricted to bands 10q25-q26 in one case. Although differences in the copy-number karyotypes of patients with slow and fast postoperative tumor-regrowth kinetics were noted, the present CGH study did not reveal any single alteration useful as a prognostic factor. In particular, these data do not support the assumption that patients suffering from GBM with amplification events would have a poorer prognosis than others.

Adult↗
PubMed1995

Embryonic cortical neurons differentiate into various types of interneurons when heterotopically transplanted into the adult rat brain.

The adult cortex represents a heterogeneous mixture of different classes of pyramidal neurons and non-pyramidal interneurons. After grafting embryonic cortical anlage into the adult striatum, the present study investigated whether the development of different populations of interneurons in heterotopic cortical grafts is similar to the adult cortex. The presence of specific subpopulations of interneurons in grafts was assessed by immunocytochemistry using various antibodies against marker molecules for interneurons such as neuropeptides and calcium-binding proteins. These molecules are expressed to a different extent in specific subpopulations of cortical interneurons. Cortical primordia obtained on embryonic day 14 (E14) were stereotactically grafted into the center of the left striatum of adult recipient rats. After an 8-week differentiation period, host rats were perfusion fixed and immunocytochemistry was performed using antibodies against neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), somatostatin, parvalbumin and calbindin D-28k. Within the grafts, the number of immunopositive interneurons as well as the intensity of immunostaining for different marker molecules corresponded well with those of the adult cortex. In contrast, the expression pattern in the graft demonstrated clear differences when compared with the surrounding host striatum. The present study demonstrates, that at E14 at least some cells of the cortical anlage are primed to develop into different classes of interneurons independent of their normal environment and their regular synaptic connections. Thus, different interneuron progenitor cells survive transplantation and develop cell-specific morphological and cytochemical characteristics. Differentiation into various subpopulations of neurons may be a prerequisite for potential therapeutic approaches in humans.

Age Factors↗
PubMed1995

Effects of kainic acid induced seizures on immediate early gene expression in mice with a targeted mutation of the CREB gene.

The present study examined the response of immediate early genes following kainic acid induced seizures in mice lacking the alpha and delta isoforms of CREB. mRNA levels for c-fos, c-jun, and Krox-24 were measured following limbic seizure activity and were found to be induced in wild type as well as CREB mutant mice. This effect was also seen for these three mRNAs at the protein level as well as for FOS-B. Furthermore the time course of expression of FOS, JUN, KROX-24, and FOS-B proteins were essentially the same in CREB mutant mice as compared to wild-type controls. These data suggest that CREB alpha and delta are not required for the induction of immediate early genes following pharmacologically induced seizures.

Activating Transcription Factor 2↗
PubMed1995

Developmental expression of GAP-43 and SNAP-25 in heterotopic rat cortical grafts.

In situ hybridization techniques were used to assess (i) whether the temporal developmental profiles of the nervous system specific growth associated phosphoprotein (GAP-43) and the 25-kDa synaptosomal-associated protein (SNAP-25) are maintained in heterotopic cortical transplants, and (ii) whether the hybridization intensity in morphologically differentiated heterotopic transplants is comparable to that in the cortex of host animals. Cortical primordia at embryonic day 14 were stereotactically grafted into the striatum of adult recipient rats. Grafts at days 4, 7, 14, 35 and 56 after transplantation demonstrated developmental changes with a progressive decline of GAP-43 and a continuous up-regulation of SNAP-25 expression. Our data provide evidence of distinct molecular alterations during the differentiation process of cortical grafts, which are strikingly similar to previous studies investigating the temporal profile and intensity of GAP-43 and SNAP-25 gene expression in normal developing cortex of the rat.

Animals↗
PubMed1995

Quantitation of human cytomegalovirus genomes in the brain of AIDS patients.

Human cytomegalovirus (HCMV) is one of the major pathogens causing neurologic disease in the immunocompromised host. A competitive nested polymerase chain reaction (PCR) was used to determine DNA load, distribution, and sequence variability of HCMV genomes in the brain of AIDS patients with and without HCMV encephalitis confirmed by histology and immunocytochemistry. By quantitative PCR, HCMV genomes were found to be distributed diffusely in the central nervous system (CNS) of all five patients with histologically proven HCMV encephalitis, but also in the brain of five of eight AIDS patients without neuropathological evidence of HCMV encephalitis. The viral DNA load in cases with HCMV encephalitis was increased 10- to 1,000-fold as compared to patients without evidence of encephalitis. A viral load above 6,000 copies HCMV/10(6) copies beta-globin was found to be highly suggestive for HCMV encephalitis. Characterization of PCR products by temperature gradient gel electrophoresis (TGGE) and direct sequencing allowed us to detect a sequence variability of the amplified fragment of HCMV glycoprotein B (gB) among different patients, but also among different HCMV foci within the same patient. Furthermore, two of five AIDS patients with HCMV encephalitis most likely experienced double infections with different HCMV strains. The experimental procedure described in this study should also be applicable to the detection of significant HCMV DNA levels in biopsy samples.

AIDS-Related Opportunistic Infections↗
PubMed1995

c-JUN, KROX-24, and c-FOS expression in hippocampal grafts placed in excitotoxic hippocampal lesions of the rat.

Hippocampal transplants were examined for the expression of three specific immediate early gene encoded proteins in order to establish if grafted immature tissue maintains the basic molecular program necessary for gene transcription after grafting to excitotoxic (ibotenic acid-induced) lesions in adult host rat brains. The transplants were derived from newborn donor rats and were analyzed immunocytochemically for the presence of c-JUN, KROX-24, and c-FOS transcription factors 5 months after grafting. The expression and distribution patterns of these genes in the host hippocampus were identical to those in hippocampal neurons of normal untreated animals. c-JUN-, KROX-24-, and c-FOS-labeled neurons were also present in the transplants, where KROX-24 and c-FOS exhibited a distribution similar to host hippocampus. In contrast, c-JUN was more extensively expressed in the transplants, suggesting a molecular response to the grafting conditions and the actual graft-host brain interactions.

Animals↗
PubMed1995

Correlation between seizure intensity and stress protein expression after limbic epilepsy in the rat brain.

Induction of heat shock/stress proteins is a key feature of a universal mechanism of cellular defence to injury known as the "stress response". The present study investigated whether heat shock protein expression correlates with the extent of neuronal injury inflicted by increasingly intense seizure activity. Limbic epilepsy was elicited by injecting intraperitoneally 8, 10 or 12 mg/kg kainic acid in adult Sprague-Dawley rats, resulting in graded degrees of seizure intensity and duration that closely correlated with the respective dose. Stress protein expression was investigated by immunocytochemistry and western blot analysis of microdissected brain areas with specific antibodies directed against representative members of three major classes of stress proteins, i.e. heat shock protein 72, heat shock protein 90 and heat shock protein 27, respectively. Heat shock protein 72 was absent in the brains of control animals, but markedly induced after limbic seizures in neurons of the limbic system, cortex, striatum and thalamus, with peak levels at 24 h. An increasing degree of seizure intensity caused a graded increase of heat shock protein 72 levels with a sequence reflecting the rank order of kainic acid susceptible hippocampal subpopulations. In contrast to heat shock protein 72, heat shock protein 90 was markedly expressed and equally abundant in all brain areas of untreated control animals and at any time point investigated following limbic seizures. Heat shock protein 27 was not detected in the brain of untreated animals nor following epilepsy. The present investigations demonstrate that the induction threshold of heat shock protein 72 in specific neuronal subpopulations clearly correlates with seizure intensity and duration. In addition, our experiments also define a narrow range of heat shock protein 72 expression with an upper limit beyond which heat shock protein 72 synthesis sharply declines. These findings reflect the risk of hippocampal neurons to undergo limbic seizure induced neuronal degeneration. It remains to be determined whether heat shock protein 72 expression is only a valuable marker for reversible neuronal injury or actually confers a neuroprotective effect.

Animals↗
PubMed1995

Hypoglycemia-elicited immediate early gene expression in neurons and glia of the hippocampus: novel patterns of FOS, JUN, and KROX expression following excitotoxic injury.

In the hippocampus there is a graded vulnerability of neuronal subpopulations to hypoglycemia-induced degeneration, most likely due to excitotoxic activation of glutamate receptors. The present study was conducted to investigate whether the induction of transcription factors of the immediate early gene (IEG) family after hypoglycemia reflects these different grades of neuronal vulnerability. We studied the expression profile of seven IEG-coded proteins in the rat hippocampus following severe insulin-induced hypoglycemia with 30 min of EEG isoelectricity and various survival periods for up to 42 h after glucose replenishment. Immunocytochemistry was performed on vibratome sections with specific polyclonal antisera directed against c-FOS, FOS B, c-JUN, JUN B, JUN D, KROX-24, and KROX-20. To unequivocally define the type of glial cells showing IEG induction, we investigated coexpression of c-FOS and glial marker proteins (glial fibrillary acid protein [GFAP], OX-42) by confocal laser scanning microscopy. Up to 3 h after glucose replenishment, differential temporospatial induction of IEG-coded transcription factors of the FOS, JUN and KROX families were observed in moderately injured neuronal subpopulations, including the majority of dentate granule cells and CA3 neurons. At later time points, however, a delayed and persistent c-JUN expression was found in severely, but reversibly, injured CA1 neurons and in neurons in the immediate vicinity of irreversibly damaged neurons in the crest of the dentate gyrus. Similar to the results with experimental models of central and peripheral axotomy, selective c-JUN induction in these neurons may represent an initial event in the regeneration process of sublethally injured neurons. In contrast to other models of excitotoxic injury such as ischemia and epilepsy, marked glial c-FOS expression was restricted to astrocytes, as assessed by confocal laser scanning microscopy.

Animals↗
PubMed1995

Selective c-JUN expression in CA1 neurons of the gerbil hippocampus during and after acquisition of an ischemia-tolerant state.

The selective delayed neuronal death of CA1 pyramidal cells after transient global ischemia in the gerbil brain can be prevented by preconditioning with a short sublethal period of ischemia 1-7 days prior to a subsequent, usually lethal ischemia of 5 min duration. Since changes of neuronal gene expression may play a crucial role in this tolerance induction, we investigated the postischemic expression profile of the fos, jun and Krox transcription factor families. We have previously reported that a single 5 min period of cerebral ischemia does not cause a de novo synthesis of immediate early gene (IEG) encoded proteins in CA1 neurons. In the present study, two experimental groups of Mongolian gerbils were investigated: one group was subjected to a single tolerance-inducing 2.5 min period of ischemia by bilateral occlusion of the common carotid artery. The second (combined ischemia) group was subjected to 2.5 min of ischemia, followed by 5 min of ischemia 4 days later. Post-ischemic expression of c-FOS, FOS B, c-JUN, JUN B, JUN D and KROX-24 was investigated by in situ hybridization and immunocytochemistry up to 48 h of recirculation. In contrast to a single 5 min period of ischemia, 2.5 min caused a postischemic expression of c-JUN protein, but no other IEGs, in CA1 neurons (peak at 6 h). Similarly, a selective but delayed c-JUN expression (peak at 18 h) was observed in animals subjected to combined ischemia. These results indicate that the induction of an endogenous neuroprotective state in CA1 neurons is associated with the activation of a genetic program which involves the expression of specific transcription factors.

Animals↗
PubMed1994

Constitutive expression of heat shock protein 90 (HSP90) in neurons of the rat brain.

Immunoblot analysis, immunocytochemistry and immuno-electron microscopy were employed to study the expression of HSP90 protein in the adult rat brain, using a specific polyclonal antiserum. Immunoblot analysis demonstrated equal levels of HSP90 in microdissected extracts from hippocampus, cortex, striatum and cerebellum. Immunocytochemistry and immuno-electron microscopy provided evidence that HSP90 is markedly expressed throughout all neuronal subpopulations of the CNS but not in non-neuronal cells except ependyma and choroid plexus. At the ultrastructural level, HSP90 immunoreactivity was predominantly found in perikarya but to a lesser extent also in dendrites and nuclei. The constitutive expression of HSP90 in widespread neuronal cell populations suggests a functional role in the physiological molecular program of CNS neurons.

Animals↗
PubMed1994

Amplification of the epidermal-growth-factor-receptor gene correlates with different growth behaviour in human glioblastoma.

The objective of our study was to determine the frequency of EGF-receptor-gene rearrangement in relation to tumour-growth behaviour in an unselected group of glioma patients. We investigated 73 glial tumours with different grades of malignancy (17 low-grade gliomas, 14 anaplastic variants, and 42 GBM) by Southern analysis, reverse transcriptase PCR (RT-PCR) amplification of mRNA, and Western analysis. An amplification of the EGF-receptor gene was present in 19/42 GBM but in only 1 anaplastic astrocytoma. By RT-PCR, 4/19 GBM with gene amplification showed a specific amino-terminal aberrant splice mutation of 801 bp in addition to undeleted mRNA. By Western analysis, 27/42 GBM showed expression of the EGF-receptor protein. Protein levels, however, varied among individual tumours. Four GBM containing an aberrant splice mutation exhibited an immunoreactive protein of 130 kDa MW in addition to the normal EGF-receptor protein p170. All GBM patients underwent surgery followed by a standard course of radiotherapy. Neuroradiological follow-up in 31/42 GBM patients consisted of bimonthly MRI examinations. There was a statistically significant difference in the mean latency period until tumour regrowth of patients suffering from GBM with and without EGF-receptor-gene amplification (9 weeks vs. 32 weeks). Our data indicate more rapid tumour regrowth kinetics of GBM with amplified EGF receptor genes in vivo.

Adolescent↗