Search PubMed⌕ Search

Biomedical subjects

B Meister

Publications and source records attributed to B Meister.

At least 145 records · Page 8Linked to original sources
PubMed1988

Glutamic acid decarboxylase- and gamma-aminobutyric acid-like immunoreactivities in corticotropin-releasing factor-containing parvocellular neurons of the hypothalamic paraventricular nucleus.

The indirect immunofluorescence technique was used to study the relation between corticotropin-releasing factor (CRF) and GABAergic neurons in the rat hypothalamic paraventricular nucleus (PVN). In colchicine-pretreated animals, glutamic acid decarboxylase (GAD)- and GABA-immunoreactive (IR) neurons were observed within the medial part of the parvocellular division of the PVN as well as surrounding the nucleus itself. In general, the GAD antiserum, as compared to the GABA antiserum, revealed stronger IR cells and a higher number of cells in the PVN. CRF-IR cells were observed throughout the whole rostrocaudal extension of the PVN, but predominantly in its dorsal medial parvocellular part. Adjacent sections stained, respectively, with antisera against CRF, GAD or GABA, revealed overlapping distributional patterns within the parvocellular part of the PVN. Employing a direct double-staining technique with sheep GAD and rabbit CRF antisera, it was demonstrated that both GAD and CRF immunoreactivities occurred in the same neurons, particularly in the dorsomedial aspect of the parvocellular PVN. GAD-positive neurons located in the ventromedial parvocellular PVN, periventricular nucleus and surrounding the PVN lacked CRF immunoreactivity. In addition, with an elution-restaining technique it was possible to demonstrate that also GABA immunoreactivity was present in some CRF neurons in the dorsomedial parvocellular PVN. Intravenous injection of the retrograde tracer Fast Blue resulted in labelling of neurons in the periventricular area and in both the parvocellular and magnocellular division of the PVN. After processing the sections for GAD/CRF immunohistochemistry, it was possible to demonstrate the presence of retrogradely labelled GAD/CRF cells, pointing at a PVN median eminence projection for these neurons. The present findings demonstrate that a subpopulation of the CRF-containing neurons in the parvocellular division of the PVN in addition are GABAergic, thereby indicating a possible corelease of these compounds, presumably in the median eminence. Possible interactions of GABA within the hypothalamo-pituitary-adrenal axis are discussed.

Animals↗
PubMed1988

Three-color immunofluorescence histochemistry allowing triple labeling within a single section.

We describe a procedure for simultaneous immunohistochemical localization of three different neuropeptides, neurotransmitters, or neurotransmitter enzymes within one and the same tissue section and present a number of examples of its application within the brain and periphery. Primary antibodies from three different species were bound to three different neurochemical substances within the same section and were then reacted with three appropriate species-specific antisera conjugated with fluorescein, rhodamine/Texas red, or biotin. The biotinylated secondary antiserum was subsequently reacted with diethylaminocoumarin (DAMC) conjugated to avidin. This combination resulted in green, red, and blue fluorescent labeling of each antigen, respectively. Each fluorescent marker was viewed and photographed discretely using appropriate excitation and suppression filter combinations. The method is well suited for analyzing instances of multiple coexistence at both the level of the cell soma and within terminal regions. More broadly, the feasibility of three-color immunofluorescence histochemistry extends the range with which antigen localization can be used to investigate the morphological bases of relationships and interactions between immunohistochemically characterized neuronal elements.

Animals↗
PubMed1987

Coexistence of peptides with classical neurotransmitters.

In the present article the fact is emphasized that neuropeptides often are located in the same neurons as classical transmitters such as acetylcholine, 5-hydroxy-tryptamine, catecholamines, gamma-aminobutyric acid (GABA) etc. This raises the possibility that neurons produce, store and release more than one messenger molecule. The exact functional role of such coexisting peptides is often difficult to evaluate, especially in the central nervous system. In the periphery some studies indicate apparently meaningful interactions of different types with the classical transmitter, but other types of actions including trophic effects have been observed. More recently it has been shown that some neurons contain more than one classical transmitter, e.g. 5-HT plus GABA, further underlining the view that transfer of information across synapses may be more complex than perhaps hitherto assumed.

Animals↗
PubMed1987

Glutamic acid decarboxylase- and peptide-immunoreactive neurons in cortex cerebri following development in isolation: evidence of homotypic and disturbed patterns in intraocular grafts.

Fetal parietal cerebral cortex was transplanted to the anterior eye chamber of adult Sprague-Dawley rats. After two to three months the grafts, with or without colchicine treatment, were subjected to immunohistochemical analysis using antibodies against cholecystokinin (CCK), somatostatin (SOM), neuropeptide tyrosine (NPY), vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI) and the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD). Cerebral cortex in situ of untreated and colchicine-treated rats was always analyzed in parallel. A dense plexus of CCK-immunoreactive fibers was distributed in all parts of the transplants, and after colchicine treatment a large number of CCK-positive cells was observed. These cells were markedly increased in number as compared to normal cortical tissue in colchicine-pretreated rats. The amount of NPY-immunoreactive cells was also markedly increased, whereas somatostatin-positive cells were found in numbers similar to those seen in cortex in situ. In the grafts only a few VIP- and PHI-positive fibers were seen with a few VIP-positive cell bodies, but no clearly discernible PHI-positive cells. A very dense plexus of GAD-positive fibers with an even distribution throughout the grafts was observed. Cortex in situ exhibited a lower density of GAD-immunoreactive fibers. Even after colchicine treatment the number of GAD-positive cells in the grafts was low. Using double-staining techniques, it was found that most of the few GAD-positive cells in the grafts were also NPY-positive, SOM-positive or, to a minor extent, CCK-positive. The present results demonstrate that several peptides and transmitter markers are expressed in cortical grafts in oculo, but marked differences in their expression can be observed in cortical tissue that has developed in isolation. Thus, the intraocular cortex graft, alone and in combination with other brain areas, should provide a useful model in which to study factors that regulate brain development.

Animals↗
PubMed1987

Comparison between transcutaneous PO2 and pulse oximetry for monitoring O2-treatment in newborns.

213 paired tcpO2/paO2-data and 186 paired tcSO2/SaO2-data measured in 25 newborns (10 term, 15 prematures) were compared. The correlation coefficient for tcpO2/paO2 was 0.796, for tcSO2/SaO2 0.944. Sensitivity for discriminating between normo- and hypoxemia (paO2 less than 50 torr) was 82% for the tcpO2- and 88% for the tcSO2-method. Positive predictive values for discriminating between normo- and hypoxemia were 88% for both methods. Sensitivity for discrimination between normo- and hyperoxemia (paO2 greater than 100 torr) was 85% for the tcpO2- and 100% for the tcSO2-method. Positive predictive values for the discrimination between normo- and hyperoxemia were 58% and 25% for tcpO2- and tcSO2 respectively. Pulse oximetry proved to be less cumbersome than the tcpO2-method. However, as tcpO2, it could not be used in some very immature newborns and in those with circulatory instability. In conclusion, these preliminary results show a similar discrimination between normoxemia and hypo-hyperoxemia for both methods. A better sensitivity of pulse oximetry for hyperoxemia is counteracted by a lesser positive predictive value.

Blood Gas Monitoring, Transcutaneous↗
PubMed1987

Dopaminergic cells in the caudal A13 cell group express somatostatin-like immunoreactivity.

The caudal extension of the hypothalamic A13 dopamine cell group (A13c) was studied in the rat brain with immunohistochemical techniques using antibodies raised against the dopamine synthesizing enzymes tyrosine hydroxylase (TH) and aromatic L-amino acid decarboxylase (AADC). Adjacent sections revealed that the TH- and AADC-staining patterns exhibited a clear overlap with that for somatostatin (SOM). Employing a double-labelling method with SOM- and AADC-antisera and subsequent elution and restaining of the same section with TH-antiserum, it was found that all immunoreactivities occurred in the same cell bodies. This study gives the first evidence for the presence of SOM-immunoreactivity in dopamine neurons.

Animals↗
PubMed1987

Analysis of peptide histidine-isoleucine/vasoactive intestinal polypeptide-immunoreactive neurons in the central nervous system with special reference to their relation to corticotropin releasing factor- and enkephalin-like immunoreactivities in the paraventricular hypothalamic nucleus.

The distribution of peptide histidine-isoleucine (PHI) and vasoactive intestinal polypeptide (VIP), two peptides derived from the same precursor molecule, was analysed with immunohistochemistry in the central nervous system of the rat, and to a limited extent in some other species including sheep, monkey and man. Special attention was focused on possible cross-reactivity between PHI antisera and corticotropin releasing factor in parvocellular neurons in the hypothalamic paraventricular nucleus projecting to the external layer of the median eminence. (1) Characterization of the PHI and VIP antisera revealed that they recognized different sequences of the peptide molecules. One of the PHI antisera (PHI-N), although mainly N-terminally directed, also probably contained an antibody population directed against the C-terminal amino acid in PHI which is an amidated isoleucine. Rat and human corticotropin releasing factor but not ovine also have an amidated isoleucine in C-terminal position. (2) PHI- and VIP-like immunoreactivity were found with parallel and overlapping distribution in all areas investigated in the rat central nervous system. In many cases coexistence of the two immunoreactivities could be directly demonstrated. PHI neurons were found in some areas so far not know to contain PHI/VIP neurons, including the dorsal septum, the septofimbrial nucleus, the stria terminalis and lamina V of the spinal cord. (3) Using an antiserum directed against the amino acid sequence 111-122 of the VIP/PHI precursor, immunoreactive cell bodies were seen in some areas containing VIP and PHI neurons. PHI- and VIP-like immunoreactivity were expressed in parallel in increasing amounts in the superficial laminae of the dorsal horn after transection of the sciatic nerve [G. P. McGregor et al. (1984) Neuroscience 13, 207-216; S. A. S. Shehab and M. E. Atkinson (1984) J. Anat. 139, 725; S. A. S. Shehab and M. E. Atkinson (1986) Expl Brain Res. 62, 422-430]. (5) The PHI-N antiserum stains large numbers of immunoreactive cells in the parvocellular part of the paraventricular nucleus and these cells are mostly identical with corticotropin releasing factor-positive neurons. Absorption experiments suggested that this PHI-N-like immunoreactivity to a large extent represented cross-reactivity with rat CRF and that earlier demonstration of many PHI-positive neurons in the paraventricular nucleus probably represents an artefact as proposed by F. Berkenbosch et al. (Neuroendocrinology 44, 338-346). However, some cells did, in fact, contain VIP- as well as PHI-like immunoreactivity as was shown with antisera not cross-reacting with corticotropin releasing factor.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Influence of coexisting hypothalamic messengers on growth hormone secretion from rat anterior pituitary cells in vitro.

An increasing number of messengers have recently been found to coexist with growth hormone (GH)-releasing factor (GRF) in hypothalamic neurons. In view of a possible cosecretion of these substances with GRF into the portal circulation, the effect of synthetic rat hypothalamic GRF(1-43) alone, or together with dopamine (DA), L-dopa, gamma-aminobutyric acid (GABA), neurotensin (NT) or galanin (GAL) on GH release was investigated by using dispersed rat anterior pituitary cells in monolayer culture. GRF in concentrations of 10(-16)-10(-7) M stimulated GH release from somatotrophs in a dose-related manner. DA (10(-5) M), L-dopa (10(-8) and 10(-5) M) and GABA (10(-9) and 10(-5) M) did not affect basal GH release, whereas DA, but not L-dopa or GABA, significantly suppressed GRF-induced GH secretion. However, the inhibitory effect of DA on GRF-stimulated GH secretion was not observed in the presence of somatostatin (10(-6) M). NT (10(-6) M) and GAL (10(-6) M) did not change basal GH release. GAL, but not NT, inhibited GRF-stimulated GH release, but the addition of NT abolished the inhibitory actions of both GAL and DA. These results indicate that substances, probably coreleased with GRF from the same nerve endings, interact in the regulation of GH secretion at the pituitary level.

Animals↗
PubMed1987

Adrenergic receptors and sodium reabsorption in normotensive subjects as related to salt sensitivity.

We have studied proximal tubular sodium reabsorption as measured by lithium clearance, alpha-2 and beta-2 adrenergic receptors on circulating platelets and lymphocytes, respectively, and urinary aldosterone after variations of sodium intake in 24 normotensive volunteers. Fractional lithium clearance was 14.8% +/- 2.64 under a high salt diet of 200 mmol per day. After a low salt diet of 50 mmol/d for two weeks fractional lithium clearance did not change significantly (13.3% +/- 3.35). There were no correlations between alpha-2 adrenergic receptors, beta-2 adrenergic receptors or the alpha-2/beta-2 ratio and fractional lithium clearance, irrespective of the high or low salt diet. In contrast, a significant correlation was found between urinary aldosterone excretion and alpha-2 receptor densities under low salt diet (r = -0.55, n = 17, p less than 0.02). There were no correlations between beta-2 adrenoceptor density, alpha-2/beta-2 ratio and urinary aldosterone during high or low salt diet. Whereas our results are inconclusive about the value of lithium clearance determinations as a measure of proximal tubular sodium reabsorption during variations of sodium intake, we conclude, that alpha-adrenoceptor density, as measured on circulating blood cells, may possibly be representative for alpha-adrenergic equipment of the kidney. The inverse correlation between urinary aldosterone excretion in subjects equilibrated on a low salt diet of 50 mmol/d and alpha-2 adrenoceptor densities could be interpreted as an indirect evidence, that those subjects with a high alpha-2 adrenoceptor equipment show a high proximal tubular sodium reabsorption and thus can afford a low rate of aldosterone mediated distal tubular sodium reabsorption to maintain sodium balance. Our results are thus in accord with our previous hypothesis, that different receptor equipment of individual subjects may cause marked differences in sodium handling by the kidney. These differences may be responsible, at least in part, for the degree of salt sensitivity in individual subjects.

Absorption↗
PubMed1986

Characterization of viruses infecting a eukaryotic Chlorella-like green alga.

Nineteen plaque-forming viruses of the unicellular, eukaryotic Chlorella-like green alga, strain NC64A, were isolated from various geographic regions in the United States and characterized. Like the previously described virus, PBCV-1, all of the new viruses were large polyhedrons, sensitive to chloroform, and contained large dsDNA genomes of ca. 300 kbp. All of the viral DNAs contained 5-methyldeoxycytidine which varied from 0.1 to 47% of the deoxycytidine. In addition, 10 of the viral DNAs contained N6-methyldeoxyadenosine which varied from 8.1 to 37% of the deoxyadenosine. These viruses, along with 11 previously described viruses which replicate in the same Chlorella host, were grouped into 11 classes based on at least one of the following properties: plaque size, reaction with PBCV-1 antiserum, or the nature and abundance of methylated bases in their genomic DNA.

Base Composition↗
PubMed1986

Intrapulmonary gas distribution in healthy children.

Distribution of ventilation was evaluated in 54 healthy children (24 boys and 30 girls), aged 7-16 years by multibreath nitrogen washout (MBNW) curves, from which the moment ratios (m1: m0, m2: m0), the lung clearance index, the Becklake index and the ventilatory efficiency index (E 90%) was computed. Functional residual capacity (FRC) was calculated from the washout curve and compared with the thoracic gas volume (TGV) plethysmographically determined, as well as with the FRC determined by helium dilution. The study shows that MBNW can easily be performed during spontaneous breathing in children and provides specific indices of ventilation. These indices show no sex difference and are age-independent. Therefore, the data of the present study contradict some previous indirect findings suggesting that the distribution of air in the lungs would become more even with age. There are in contrast more convincing direct measurement data showing that airways grow isotropically relative to the lungs.

Adolescent↗