PubMed Health⌕ Search

Biomedical subjects

A Rolfs

Publications and source records attributed to A Rolfs.

At least 19 recordsLinked to original sources
PubMed2006

Nitric oxide synthase-containing neurons in the amygdaloid nuclear complex of the rat.

The nitric oxide-producing neurons in the rat amygdala (Am) were studied, using reduced nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) histochemistry. Almost all nuclei of the Am contained NADPHd-positive neurons and fibers, but the somatodendritic morphology and the intensity of staining of different subpopulations varied. The strongly stained neurons displayed labeling of the perikaryon and the dendritic tree with Golgi impregnation-like quality, whilst the dendrites of the lightly stained neurons were less successfully followed. Many strongly positive neurons were located in the external capsule and within the intraamygdaloid fiber bundles. A large number of small, strongly stained cells was present in the amygdalostriatal transition area. In the Am proper, a condensation of deeply stained cells occurred in the lateral amygdaloid nucleus. In the basolateral nucleus, the strongly NADPHd-positive neurons were few, and were located mainly along the lateral border of the nucleus. These cells clearly differed from the large, pyramidal, and efferent cells. The basomedial nucleus contained numerous positive cells but most of them were only lightly labeled. A moderate number of strongly stained neurons appeared in the medial division of the central nucleus, and a larger accumulation of strongly positive cells was present in the lateral and the capsular divisions. The medial amygdaloid nucleus contained numerous moderately stained neurons and displayed the strongest diffuse neuropil staining in Am. In the nucleus of the lateral olfactory tract, the first layer contained only NADPHd-stained axons, in the second layer, there were numerous moderately stained cells, and in the third layer, a few but deeply stained neurons. From the cortical nuclei, the most appreciable number of stained neurons was seen in the anterior cortical nucleus. The anterior amygdaloid area contained numerous NADPHd-positive neurons; in its dorsal part the majority of cells were only moderately stained, whereas in the ventral part the neurons were very strongly stained. The intercalated amygdaloid nucleus lacked NADPHd-positive neurons but an appreciable plexus of fine, tortuous axons was present. In the intra-amygdaloid part of the bed nucleus of the stria terminalis (st) some lightly stained cells were seen but along the entire course of st strongly stained neurons were observed. Some Am nuclei, and especially the central lateral nucleus and the intercalated nucleus, display considerable species differences when compared with the primate Am. The age-related changes of the nitrergic Am neurons, as well as their involvement in neurodegenerative diseases is discussed.

Amygdala↗
PubMed2006

Brain stem afferent connections of the amygdala in the rat with special references to a projection from the parabigeminal nucleus: a fluorescent retrograde tracing study.

A recently revealed important function of the amygdala (Am) is that it acts as the brain's "lighthouse", which constantly monitors the environment for stimuli which signal a threat to the organism. The data from patients with extensive lesions of the striate cortex indicate that "unseen" fearful and fear-conditioned faces elicit increased Am responses. Thus, also extrageniculostriate pathways are involved. A multisynaptic pathway from the retina to the Am via the superior colliculus (SC) and the pulvinar was recently suggested. We here present data based on retrograde neuronal labeling following injection of the fluorescent tracer Fluoro-Gold in the rat Am that the parabigeminal nucleus (Pbg) emits a substantial, bilateral projection to the Am. This small cholinergic nucleus (Ch8 group) in the midbrain tegmentum is a subcortical relay visual center that is reciprocally connected with the SC. We suggest the existence of a second extrageniculostriate multisynaptic connection to Am: retina-SC-Pbg-Am, that might be very effective since all tracts listed above are bilateral. In addition, we present hodological details on other brainstem afferent connections of the Am, some of which are only recently described, and some others that still remain equivocal. Following selective injections of Fluoro-Gold in the Am, retrogradely labeled neurons were observed in parasubthalamic nucleus, peripeduncular nucleus, periaqueductal gray, dopaminergic nuclear complex (substantia nigra pars lateralis and pars compacta, paranigral, parabrachial pigmented and interfascicular nuclei, rostral and caudal linear nuclei, retrorubral area), deep mesencephalic nucleus, serotoninergic structures (dorsal, median and pontine raphe nuclei), laterodorsal and pedunculopontine tegmental nuclei (Ch6 and Ch5 groups), parabrachial nuclear complex, locus coeruleus, nucleus incertus, ventrolateral pontine tegmentum (A5 group), dorsomedial medulla (nucleus of the solitary tract, A2 group), ventrolateral medulla (A1/C1 group), and pars caudalis of the spinal trigeminal nucleus. A bilateral labeling of the upper cervical spinal cord was also observed.

Amygdala↗
PubMed2006

Morphological basis for the spectrum of clinical deficits in spinocerebellar ataxia 17 (SCA17).

Spinocerebellar ataxia 17 (SCA17) is a rare genetic disorder characterized by cerebellar, extrapyramidal, pyramidal as well as psychiatric signs. The pathoanatomical basis of this disorder is still not well known. A total of 12 patients and 12 age- and sex-matched controls were examined by in vivo MRI voxel-based morphometry (VBM). Besides general patterns of disease-related brain atrophy, characteristic syndrome-related morphological changes in SCA17 patients were studied. In comparison with normal controls, SCA17 patients showed a pattern of degeneration of the grey matter centred around mesial cerebellar structures, occipito-parietal structures, the anterior putamen bilaterally, the thalamus and other parts of the motor network, reflecting the cerebellar, pyramidal and extrapyramidal signs. A correlation analysis revealed a clear association between the clinical cerebellar, extrapyramidal and psychiatric scores and degeneration in specific areas. Two degeneration patterns were found as follows: regarding motor dysfunction, atrophy of the grey matter involved mainly the cerebellum and other motor networks, in particular the basal ganglia. In contrast, correlations with psychiatric scores revealed grey matter degeneration patterns in the frontal and temporal lobe, the cuneus and cingulum. Most interestingly, there was a highly significant correlation between the clinical Mini-Mental State Examination scores and atrophy of the nucleus accumbens, probably accounting for the leading psychiatric signs.

Adult↗
PubMed2003

The role of the iminosugar N-butyldeoxynojirimycin (miglustat) in the management of type I (non-neuronopathic) Gaucher disease: a position statement.

N-Butyldeoxynojirimycin (NB-DNJ, miglustat 'Zavesca') is an orally active iminosugar which inhibits the biosynthesis of macromolecular substrates that accumulate pathologically in glycosphingolipidoses. Clinical trials of NB-DNJ in patients with Gaucher's disease demonstrate the therapeutic potential of such substrate inhibitors in the glycolipid storage disorders. However, macrophage-targetted enzyme replacement using intravenous mannose-terminated human glucocerebrosidase (imiglucerase, Cerezyme) is highly effective in ameliorating many of the manifestations of Gaucher's disease and is a treatment in widespread use. Given that imiglucerase and miglustat are now both licensed for the treatment of Gaucher's disease, there is a need to review their therapeutic status. Here the treatment of type 1 (non-neuronopathic) Gaucher disease is evaluated with particular reference to the emerging role of oral N-butyldeoxynojirimycin (miglustat) as a substrate-reducing agent. This position statement represents the consensus viewpoint of an independent international advisory council to the European Working Group on Gaucher Disease.

Clinical Trials as Topic↗
PubMed2003

Niemann-Pick disease type A and B are clinically but also enzymatically heterogeneous: pitfall in the laboratory diagnosis of sphingomyelinase deficiency associated with the mutation Q292 K.

This study describes a diagnostic pitfall in the laboratory diagnosis of patients with sphingomyelinase deficiency (SMD; Niemann-Pick disease types A and B; NPA and NPB), in cases where sphingomyelinase activity was not determined with sphingomyelin as the natural enzymic substrate. Four of 24 SMD patients studied had falsely normal or enhanced activity, when a so-called artificial sphingomyelinase substrate, 2-N-(hexadecanoyl)-amino-4-nitrophenyl phosphorylcholine (HNP), was used, whereas SMD was clear with the sphingomyelin substrate. Those four patients had the Q292 K mutation of the acid sphingomyelinase gene (SMPD1) on at least one allele. Three of the four patients (no data available from one) experienced only late-infantile or juvenile, though distinct, neurological involvement, where learning disabilities, hypo- or areflexia or mild ataxia were initial signs. The laboratory pitfall with HNP substrate, which is used in many laboratories, raises the risk that some SMD patients are overlooked, and it prevents the consideration of a late-manifesting neurological course in some patients as well as the planning of enzyme substitution therapy in non-neurological SMD (NPB) patients. Since classical NPB is very rare, it is suggested that SMD patients with late- or mild-manifesting neurological symptoms should better be assigned to additional SMD subgroups than grouped with NPB.

Adolescent↗
PubMed2001

An iron-regulated ferric reductase associated with the absorption of dietary iron.

The ability of intestinal mucosa to absorb dietary ferric iron is attributed to the presence of a brush-border membrane reductase activity that displays adaptive responses to iron status. We have isolated a complementary DNA, Dcytb (for duodenal cytochrome b), which encoded a putative plasma membrane di-heme protein in mouse duodenal mucosa. Dcytb shared between 45 and 50% similarity to the cytochrome b561 family of plasma membrane reductases, was highly expressed in the brush-border membrane of duodenal enterocytes, and induced ferric reductase activity when expressed in Xenopus oocytes and cultured cells. Duodenal expression levels of Dcytb messenger RNA and protein were regulated by changes in physiological modulators of iron absorption. Thus, Dcytb provides an important element in the iron absorption pathway.

Amino Acid Sequence↗
PubMed2001

[Diagnosis and therapy of Gaucher disease. Current recommendations of German therapy centers in the year 2000].

BACKGROUND: Gaucher's disease is the autosomally recessively inherited deficiency of the lysosomal enzyme glucocerebrosidase. Increasing storage of glucocerebrosides leads to a multisystem disease, the prevalence of which is about 1:40,000 in central Europe and up to 1:2,000 in some other countries (e.g. Israel). The acute and chronic neuronopathic forms of the disease (formerly defined as Gaucher types 2 and 3) account for only 5 to 10% of all Gaucher patients in Central Europe and Germany and are thus less frequent than the non-neuronopathic disease (formerly defined as Gaucher type 1). Gaucher's disease is usually associated with spleno- and hepatomegaly, fatigue, skeletal complications, and several corresponding hematological and laboratory abnormalities. In 5 to 10% of the patients there are also central nervous symptoms such as myoclonic seizures, oculomotoric apraxia and a slight mental retardation. METHODS: Four specialized centers care for more than 2/3 of all German Gaucher patients today. These centers present their consensus recommendations for state-of-the-art diagnosis and treatment of Gaucher's disease. RESULTS: Recent epidemiological data indicate that only 10 to 20% of all Gaucher patients are correctly diagnosed (and treated) in Germany. The diagnosis today can be done in all patients by noninvasive methods, i.e. determination of the glucocerebrosidase activity in peripheral leukocytes and of the genetic defect. The current enzyme replacement therapy with glucocerebrosidase has proven effective to improve and often normalize hematological abnormalities, hepatosplenomegaly, skeletal complications and quality of life, provided that the therapy is started early and is given at adequate dosages. CONCLUSION: In view of the availability of an effective therapy, efforts should be made to increase the awareness of Gaucher's disease in differential diagnosis, to help to diagnose the disease with noninvasive techniques at early stages, and to provide practical guidelines for adequate treatment.

Chromosome Aberrations↗
PubMed2001

Whole-cell patch-clamp: true perforated or spontaneous conventional recordings?

Perforated whole-cell patch-clamp recordings obtained with nystatin are frequently used to preserve intracellular integrity. However, the perforated-patch configuration may sometimes undergo a spontaneous change into the conventional whole-cell configuration, especially when lymphocytes are investigated. The electrophysiological criteria-- previously described--for establishing the existence of the perforated whole-cell configuration have been shown to be insufficient. Thus, the dye eosin, applied to the pipette solution, was tested as a tool for discriminating between the perforated and the conventional whole-cell configurations on rat T-lymphocytes. The dye never entered the cell from the pipette during the entire measurement in the perforated whole-cell configuration. In contrast, all cells in the conventional whole-cell configuration became red immediately after membrane rupture. Eosin barely changed the currents studied. The results suggest that eosin is a dye of choice for verifying a true perforated-patch configuration.

Animals↗
PubMed2001

Gene expression profiling of the nervous system in murine experimental autoimmune encephalomyelitis.

Multiple sclerosis is thought to be a polygenic disease driven by dysregulation of the immune system leading to an autoimmune response against one or several antigens of cerebral white matter tissue. Experimental autoimmune encephalomyelitis (EAE) is a mouse model that is used to study the aetiology and pathogenesis of multiple sclerosis and new therapeutic approaches. We used oligonucleotide microarrays to determine gene expression profiles of the inflamed spinal cords of EAE mice at the onset and at the peak of the disease. Of the approximately 11 000 genes studied, 213 were regulated differentially and 100 showed consistent differential regulation throughout the disease. Inflammation resulted in a profile of increased gene expression of immune-related molecules, extracellular matrix and cell adhesion molecules and molecules involved in cell division and transcription, and differential regulation of molecules involved in signal transduction, protein synthesis and metabolism. Of the 104 genes with defined chromosomal locations, 51 mapped to known EAE-linked quantitative trait loci and as such are putative candidate genes for susceptibility to EAE.

Animals↗
PubMed2000

Long-term therapeutic drug monitoring of clozapine and metabolites in psychiatric in- and outpatients.

RATIONALE: Clozapine is a unique antipsychotic drug, outstanding for its lack of extrapyramidal side-effects and its superior efficacy in refractory schizophrenia. However, an unambiguous concentration-response relationship has not yet been established. OBJECTIVE: We investigated serum concentrations of clozapine, norclozapine and clozapine-N-oxide in psychiatric in- and outpatients to identify particular metabolic patterns in clozapine responders and non-responders and putative threshold levels for clozapine response. METHODS: Psychiatric assessments, CYP2D6 genotype, and weekly serum concentrations of clozapine, norclozapine and clozapine-N-oxide were obtained in 34 adult schizophrenic in-and outpatients (18 men, 16 women) during 10 weeks of clozapine treatment with a naturalistic dose design. RESULTS: Responders (n=21) displayed significantly lower serum concentrations of clozapine corrected for dose compared to non-responders (n=13; P<0.05), while none of the other parameters (absolute clozapine concentration, metabolite ratios, gender) were different. Smokers had significantly lower dose-corrected clozapine concentrations. A positive correlation was observed between age and average steady state clozapine concentrations. CONCLUSIONS: These findings indicate a possible link between CYP activity and response to clozapine that is not mediated through differences in serum concentrations. No clinically meaningful pattern in serum parameters could be identified that differentiates responders from non-responders. Thus, clozapine TDM seems ineffective for predicting clinical response. Smoking behavior is a major determinant of clozapine clearance while CYP2D6 genotype does not impact clozapine disposition.

Adult↗
PubMed2000

K(+) channel-blocking alkoxypsoralens inhibit the immune response of encephalitogenic T line cells and lymphocytes from Lewis rats challenged for experimental autoimmune encephalomyelitis.

Alkoxypsoralens, known as DNA photomodifying agents, have been shown to block voltage-dependent K(+) channels (Kv) as well as to alleviate functional deficits in certain multiple sclerosis (MS) patients in a manner similar to 4-aminopyridine. Since Kv channel blockers are known to inhibit T cell-mediated immune responses both in vitro and in vivo, we investigated the effects of three alkoxypsoralens, 5-methoxypsoralen (5-MOP), 8-methoxypsoralen (8-MOP), and 5,8-diethoxypsoralen (H37), on the following parameters: (1) whole-cell K(+) currents of encephalitogenic, myelin basic protein-specific memory T cell line cells (MBP-TCLC) derived from Lewis rats as measured by patch-clamp technique, (2) proliferation of MBP-TCLC and lymph node cells (LNC) from Lewis rats challenged for experimental autoimmune encephalomyelitis (EAE) by immunisation with spinal cord homogenate as measured by 3H-thymidine incorporation, (3) interferon-gamma (IFN-gamma) secretion of MBP-TCLC as measured by ELISA, and (4) IFN-gamma gene expression of LNC as measured by quantitative reverse transcription polymerase chain reaction (RT-PCR) with ELISA-detection. The examined alkoxypsoralens exhibited suppressive effects on the measured parameters with the same sequence of efficacy: H37>5-MOP>8-MOP. We, therefore, conclude that Kv channel-blocking alkoxypsoralens interfere with voltage-controlled signal transduction in lymphocytes and might thereby suppress immune responses in autoimmune diseases of the central nervous system and most likely also in other autoimmune disorders. Thus, alkoxypsoralens, especially the non-phototoxic substance H37, are new candidates for further studies on K(+) channel blocking immunosuppressive drugs. The agents may exert a dual beneficial effect on demyelinating diseases like MS, because they could attenuate the inflammatory process and improve axonal conductivity.

4-Aminopyridine↗
PubMed2000

A novel duodenal iron-regulated transporter, IREG1, implicated in the basolateral transfer of iron to the circulation.

Iron absorption by the duodenal mucosa is initiated by uptake of ferrous Fe(II) iron across the brush border membrane and culminates in transfer of the metal across the basolateral membrane to the portal vein circulation by an unknown mechanism. We describe here the isolation and characterization of a novel cDNA (Ireg1) encoding a duodenal protein that is localized to the basolateral membrane of polarized epithelial cells. Ireg1 mRNA and protein expression are increased under conditions of increased iron absorption, and the 5' UTR of the Ireg1 mRNA contains a functional iron-responsive element (IRE). IREG1 stimulates iron efflux following expression in Xenopus oocytes. We conclude that IREG1 represents the long-sought duodenal iron export protein and is upregulated in the iron overload disease, hereditary hemochromatosis.

Amino Acid Sequence↗
PubMed2000

Clozapine-induced agranulocytosis and hereditary polymorphisms of clozapine metabolizing enzymes: no association with myeloperoxidase and cytochrome P4502D6.

The pathomechanisms of most drug-induced agranulocytoses are unclear; however, there are some studies pointing to genetic determinants. Some drug-induced agranulocytoses such as clozapine-induced agranulocytosis (CA) may be regarded as an idiosyncratic drug reaction because of its preclinical and clinical characteristics. To study some aspects of the genetic background of CA further, polymorphisms of specific metabolizing enzyme systems of clozapine were examined. Thirty-one schizophrenic patients with CA and 77 schizophrenic comparison subjects without this adverse effect underwent genotyping of a recently discovered G(-463)A polymorphism of myeloperoxidase (MPO) gene and cytochrome P4502D6. Neither the MPO mutation nor specific genotypes of cytochrome P4502D6 were associated with CA. Both were equally distributed among CA patients and controls. Thus, our data suggest lack of evidence of an association of CA and genetically variable activity of these specific drug metabolizing enzymes; however, this may be due to statistical reasons only. Thus, further studies with greater CA samples are necessary to draw final conclusions about these genetically based hypotheses.

Adult↗
PubMed2000

Immunocytochemical characterization of in vitro PKH26-labelled and intracerebrally transplanted neonatal cells.

The lipophilic dye PKH26 that binds irreversibly to cell membranes has been used to label various cell types in vitro prior to transplantation in order to recognize grafted cells posttransplantationally in the host tissue by fluorescence microscopy. The purpose of the present study was to optimize immunocytochemical staining procedures for PKH26-containing specimens in cell culture and after transplantation into rat brain. We demonstrated that freeze-thawing allowed for proper immunostaining of intracellular epitopes whereas PKH26-labelling was preserved. PKH26-labelled donor cells were detectable at least up to 4 months after transplantation in the host brain.

Animals↗