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Biomedical subjects

M Carlberg

Publications and source records attributed to M Carlberg.

54 records · Page 3Linked to original sources
PubMed1993

Is nitric oxide (NO) produced by invertebrate neurones?

NADPH-diaphorase (NADPHd) is known to be identical to nitric oxide (NO) synthase in the mammalian nervous system, and is therefore used as a marker of NO-producing neurones. Using the histochemical reaction for NADPHd, we searched for such neurones in a selection of invertebrates. Special emphasis was given to molluscs. No selective neuronal staining was found in representatives of coelenterates, turbellarians, nematodes and urochordates. In all annelids, arthropods and molluscs examined, with the exception of a chiton, specific neurones were selectively stained. The reaction was particularly strong in pulmonate molluscs where scattered positive neurones were found in various ganglia and clustered symmetrically in the paired buccal ganglia. Biochemical assay of NO synthase in osphradia of the gastropod mollusc Lymnaea stagnalis revealed a formation of citrullin that was inhibited by the specific NO synthase N omega-nitro-L-arginine (NO2Arg). Both histochemical and biochemical methods indicate that NO can be used as a signal molecule by specific neurones in advanced invertebrates.

Amino Acid Oxidoreductases↗
PubMed1993

Selective killing induced by an inhibitor of N-linked glycosylation.

Treatment with a low dose (0.5 microgram/ml) of tunicamycin (an inhibitor of N-linked glycosylation) blocked the cell cycle progression of both normal Balb/c 3T3 cells (A31) and their SV40-transformed derivatives (SVA31) specifically in early G1 (0-3 h after mitosis). Upon release after an 8-h treatment the A31 cells returned to the cell cycle via a 9-h recovery phase, indicating that they were arrested in G0. The A31 cells were fully viable after this treatment. In contrast, the postmitotic SVA31 cells, which were unable to arrest in G0, did not divide after the removal of tunicamycin. Instead, these cells died but this did not occur until 22-34 h after release from the treatment. SVA31 cells that had passed the postmitotic phase of G1 survived during the parental generation and divided normally. However, a large portion of these cells died during the next cycle, and in total during a 48-h period approximately 50% of the cells were killed as a consequence of an 8-h exposure to tunicamycin. In contrast, treatment with inhibitors of protein synthesis and HMG CoA reductase activity as well as inhibitors of modification of N-linked oligosaccharide chains did not result in cell death.

Animals↗
PubMed1992

Galanin receptors in the brain of a teleost: autoradiographic distribution of binding sites in the Atlantic salmon.

The distribution of galanin (GAL) binding sites in the brain of the Atlantic salmon (Salmo salar) was investigated by means of radioligand binding in conjunction with autoradiography by using high-performance liquid chromatography (HPLC) characterized radio-iodinated porcine galanin ([125I]GAL). On slide-mounted sections of frozen salmon brain homogenate, [125I]GAL (4 nM) bound rapidly and reversibly to a single population of sites with a Kd of 1.0 +/- 0.08 nM (n = 3) and Bmax of 2.38 +/- 0.19 fmol/mg wet tissue. Specific [125I]GAL binding was found in cellular regions, in fiber tracts, and in neuropil areas throughout the brain, except for in the olfactory bulb, pineal organ, and cerebellum. Autoradiographic microdensitometric measurements revealed high total [125I]GAL binding in the ventral hypothalamus (inferior lobes; around 7-12 fmol/mg tissue), the dorsal spinal cord (between 6 and 12 fmol/mg tissue), sublayers of the optic tectum (around 8 fmol/mg), torus semicircularis (around 7 fmol/mg), and glomerular complex (around 6 fmol/mg). Intermediate densities of [125I]GAL binding (3-5 fmol/mg tissue) were found in the pituitary, telencephalon, dorsolateral thalamic nucleus, and raphe nuclei and in association with the forebrain bundles. Except for in the optic tectum, there is a good concordance of [125I]GAL binding sites and GAL-immunoreactive fiber projections in most brain areas of the salmon. The wide distribution of GAL binding sites provides further evidence that a GAL-like substance might be involved in a diversity of brain functions of teleosts. The topographic distribution of target sites in the hypothalamo-hypophyseal axis indicates that GAL-like substances may have both direct and indirect effect on pituitary functions while in extrahypothalamic areas, functional implications by GAL may include involvement in somatosensory, central gustatory, olfactory, and visual functions. This study provides evidence for the presence of a specific GAL receptor in the brain of the Atlantic salmon. Together the distribution of GAL binding and GAL-like molecules provide a covering delineation of the GAL neuronal system in the brain of the Atlantic salmon. Comparisons with mammals suggest that the GAL receptor molecule has been well preserved during evolution and that GAL-like substances may be present, and even possess similar functional properties, throughout the vertebrate phylogeny.

Animals↗
PubMed1992

Yeast SKO1 gene encodes a bZIP protein that binds to the CRE motif and acts as a repressor of transcription.

We have cloned a yeast gene, SKO1, which in high copy number suppresses lethal overexpression of cAMP-dependent protein kinase. SKO1 encodes a bZIP protein that binds to the CRE motif, TGACGTCA. We found that SKO1 also binds to a CRE-like site in SUC2, a yeast gene encoding invertase which is under positive control by cAMP. A disruption of the SKO1 gene causes a partial derepression of SUC2, indicating that SKO1 is a negative regulator of the SUC2 gene. SKO1 interacts positively with MIG1, a zinc finger protein that mediates glucose repression of SUC2. A kinetic analysis revealed a complex regulation of the SUC2 mRNA in response to glucose. First, MIG1 mediates a rapid and strong repression of SUC2, which is complete within 10 minutes. Second, a MIG1-independent process causes a further slow reduction in the mRNA. Third, in the absence of MIG1, there is also a rapid but transient glucose induction of the SUC2 mRNA. This induction is correlated with a transient loss of SKO1-dependent repression.

Amino Acid Sequence↗
PubMed1991

Specific binding of D-Tyr25 (Nle28,31)-CCK(25-33) to cortical membranes from rat brain.

The 125I-labeled sulfonated cholecystokinin (CCK) analogue, D-Tyr25(Nle28,31)-CCK(25-33), bound saturably and reversibly to membranes of rat cerebral cortex. The dissociation constant Kd was estimated to be 0.14 nM by Scatchard analysis and 0.40 nM from analyses of dissociation/association rates. Hill coefficients of 0.99, Scatchard plots and drug competition studies were consistent with a single population of binding sites. Dependence on divalent cations and inhibition by guanylyl-imidodiphosphate suggested binding to a receptor coupled to a G protein. Competition studies with CCK-analogues and non-peptide specific antagonists indicated binding to receptor sites of the B-subtype (CCKB).

Animals↗
PubMed1991

Control of yeast GAL genes by MIG1 repressor: a transcriptional cascade in the glucose response.

Glucose repression is a global regulatory mechanism in yeast. We have investigated how glucose regulates the GAL genes, which are required for galactose fermentation. We found that the GAL genes are controlled by a transcriptional cascade. Thus, GAL4, which encodes an activator of the GAL genes, is repressed by MIG1, a zinc finger protein that binds to the GAL4 promoter. MIG1 has a dual role in control of the GAL genes, since MIG1 also binds to the promoter of GAL1, a gene regulated by GAL4. A disruption of MIG1 interacts synergistically with a disruption of GAL80, a gene involved in galactose induction. This suggests that the MIG1-dependent response to glucose is amplified by down-regulation of the induction pathway.

Base Sequence↗
PubMed1991

Protein phosphatase 2A in Saccharomyces cerevisiae: effects on cell growth and bud morphogenesis.

We have cloned three genes for protein phosphatases in the yeast Saccharomyces cerevisiae. Two of the genes, PPH21 and PPH22, encode highly similar proteins that are homologs of the mammalian protein phosphatase 2A (PP2A), while the third gene, PPH3, encodes a new PP2A-related protein. Disruptions of either PPH21 or PPH22 had no effects, but spores disrupted for both genes produced very small colonies with few surviving cells. We conclude that PP2A performs an important function in yeast cells. A disruption of the third gene, PPH3, did not in itself affect growth, but it completely prevented growth of spores disrupted for both PPH21 and PPH22. Thus, PPH3 provides some PP2A-complementing activity which allows for a limited growth of PP2A-deficient cells. Strains were constructed in which we could study the phenotypes caused by either excess PP2A or total PP2A depletion. We found that the level of PP2A activity has dramatic effects on cell shape. PP2A-depleted cells develop an abnormal pear-shaped morphology which is particularly pronounced in the growing bud. In contrast, overexpression of PP2A produces more elongated cells, and high-level overexpression causes a balloonlike phenotype with huge swollen cells filled by large vacuoles.

Amino Acid Sequence↗
PubMed1990

[125I][D-Tyr25,Nle28,31]CCK-(25-33): a convenient new aminopeptidase resistant cholecystokinin analogue for radioligand binding and autoradiography.

The 125I-labeled sulfated cholecystokinin (CCK) analogue, [D-Tyr25,Nle28,31]CCK-(25-33), bound saturably to membranes from rat cerebral cortex and to brain tissue sections. Competition studies suggested binding to sites of the CCKB subtypes. The high affinity for brain membranes (Kd = 0.14 nM) and high specific binding to brain sections (80-90% specific binding), as well as its high specific radioactivity, makes it a suitable ligand for autoradiographic studies of cholecystokinin receptors.

Aminopeptidases↗
PubMed1990

3,4-Dihydroxyphenylethylamine, L-3,4-dihydroxyphenylalanine and 3,4,5-trihydroxyphenylalanine: oxidation and binding to membranes. A comparative study of a neurotransmitter, a precursor and a neurotransmitter candidate in primitive nervous systems.

At neutral (7.0) and slightly basic (8.2) pH, L-3,4-dihydroxyphenylalanine (L-DOPA), 3,4,5-trihydroxyphenylalanine (5-OH-DOPA) and 3,4-dihydroxyphenylethylamine (dopamine) undergo autoxidation. The binding of radiolabeled oxidation products of L-DOPA, 5-OH-DOPA and dopamine to membrane proteins was compared by a filtration procedure. Membranes from tentacles of the sea anemone Metridium senile bind significantly more 5-OH-DOPA than L-DOPA and dopamine. Membranes from rat brain and brains from the three-spined stickleback Gasterosteus aculeatus, bind significantly more dopamine than L-DOPA and 5-OH-DOPA. Membranes from Metridium contain an o-diphenol O2: oxidoreductase (tyrosinase). In the absence of inhibitors, enzymatic oxidation causes a fiftyfold increase in binding of L-DOPA and a more than tenfold increase in binding of dopamine, whereas the binding of 5-OH-DOPA only is increased by 10%. It is concluded than 5-OH-DOPA more easily undergo autoxidation than L-DOPA and dopamine, but its quinone form is probably less reactive with membrane proteins. The suitability of tyrosinase-mediated biosynthesis of L-DOPA and 5-OH-DOPA versus tyrosine hydroxylase-mediated biosynthesis of L-DOPA and dopamine in primitive nervous systems and in the vertebrate CNS is discussed on the basis of the cytotoxic potential through irreversible binding to membrane proteins of oxidation products of the catechol compounds formed.

Animals↗
PubMed1990

The macroeconomics of demographic unemployment.

"What are the macroeconomic consequences of an increase in labour supply? In the short run, unemployment occurs, due to both lack of aggregate demand and capital shortage. Demand-side policy and money wage restraint prove to be ineffective in this situation, owing to capital shortage. On the other hand, a reduction in working hours without wage compensation as well as a policy mix of both demand-side policy and investment policy turn out to be effective. The reduction in working hours lowers individual income and raises individual leisure, as compared to the policy mix." (SUMMARY IN GER)

Economics↗
PubMed1989

Yeast galactose permease is related to yeast and mammalian glucose transporters.

We have cloned and sequenced the GAL2 gene of Saccharomyces cerevisiae, which encodes galactose permease. The GAL2 protein is related to the yeast glucose transporter encoded by the SNF3 gene, and also to mammalian and bacterial sugar permeases. Like the other members of this protein family, GAL2 has twelve hydrophobic segments that are separated by loops of charged amino acids. A comparison of different members of this protein family shows that those parts of the polypeptides thought to be on the cytoplasmic side of the cell membrane, are more conserved than other parts of the molecules.

Amino Acid Sequence↗
PubMed1988

Presence of serotonin in early chick embryos.

With biochemical analysis and with autoradiography based on injection of 5-[3H]hydroxytryptophan, it was possible to demonstrate the presence of serotonin (5-hydroxytryptamine) in early chick embryos as early as the pre-streak stage. The biochemical analysis which covered the early developmental period (0.5-6 days of incubation) revealed an elevated concentration of serotonin at gastrulation; from then it stayed at a lower and fairly even level. Autoradiographs of embryos at the pre-streak stage, the primitive streak stage, the head fold stage and the 4-6 somites stage indicated the presence of serotonin in intracellular yolk granules and in cell nuclei. Moreover, the amine appeared associated with microfilaments and microtubules, particularly in developing neural cells. Notably the elevated concentration of serotonin at gastrulation, but also the intracellular distribution of the amine during early organogenesis, indicates a prominent role for it in cell-shape changes and morphogenesis in the early chick embryo.

5-Hydroxytryptophan↗
PubMed1988

Port-wine stain--a surgical and psychological problem.

Patients with large and small port-wine stains have been studied using an intensive interview technique. Those with large defects were shown to have reality problems in common. In addition, their experiences were found to be tempered by individual life events and personality dynamics. Those with small port-wine stains who sought treatment showed no reality problems but experienced great individual psychological problems, which in this study are proved to be the same type. The implications of these findings for prophylaxis against mental illness as well as factors to take into consideration when treating these patients are discussed.

Adult↗
PubMed1984

Enzymatic 5-hydroxylation of L-dopa by a tyrosinase isolated from the sea anemone Metridium senile.

A particulate tyrosinase has been extracted and purified from tentacles of the sea anemone Metridium senile. The purified enzyme had properties in common with both mushroom and vertebrate tyrosinase and catalyzed three different reactions: oxidation of catechols, hydroxylation of L-tyrosine with L-dopa as cofactor and 5-hydroxylation of L-dopa. 5-Hydroxylation of L-dopa by an animal tyrosinase has not been reported earlier. The reaction could be analyzed under reducing conditions when the much faster oxidation of L-dopa to dopaquinone was inhibited. The conditions required for the accumulation of L-dopa and 5-hydroxydopa observed in vivo in tentacles of Metridium are discussed.

Animals↗
PubMed1983

Evidence of dopa in the nerves of sea anemones.

An analysis of the presence of catechol-derivatives in the sea anemones Metridium senile and Tealia felina, made with the aid of high-pressure liquid chromatography (HPLC), established the presence of dopa, 5-OH-dopa, and 5-S-cysteinyldopa. In addition, 2-S-cysteinyldopa and 2.5-diSS-cysteinyldopa occurred in Metridium. Two unknown substances were found to be present in the tentacles of Metridium and in the tentacles of some specimens of Tealia. Neither catecholamines nor serotonin could be traced in detectable amounts. No dopa-decarboxylase could be demonstrated by the assay performed in this investigation. 6-OH-dopa, 6-OH-dopamine and reserpine had no effect on the formaldehyde-induced fluorescence of the subepithelial tentacular nerve net of Tealia. It is concluded that the tentacular nerve net of sea anemones contains dopa, but neither catecholamines nor serotonin. The localization of the other compounds is not yet established.

Animals↗
PubMedDate not supplied

Electrophysiological and autoradiographical evidence for cholecystokinin A receptors on rat isolated nodose ganglia.

The sulphated octapeptide, cholecystokinin (CCK-8S), is believed to be a neurotransmitter of vagal sensory neurones, and here the presence of functional receptors for CCK-8S in the rat vagus nerve has been investigated by electrophysiological and autoradiographic techniques. CCK-8S caused concentration-dependent depolarizations when superfused over the rat isolated nodose ganglion at 37 degrees C as measured by a silicone grease gap technique. Concentration-response curves to CCK-8S were shifted to the right by low concentrations of the CCKA receptor antagonist, Devazepide, but not by the CCKB receptor antagonist, L-365,260, data which indicate that receptors were of the CCKA subtype. Consistent with this notion, the CCKB agonist, unsulphated CCK-8, was without effect until high concentrations (> 1 microM) were used. A synthetic analogue of CCK-8S, D-Tyr25(Nle28,31)-CCK 25-33S, which has been reported to be more stable and peptidase-resistant than CCK-8S, was equipotent with CCK-8S in depolarizing the nodose ganglion. When D-Tyr25(Nle28,31)-CCK 25-33S was labelled with 125I, it bound to tissue sections of nodose ganglion. By light microscopic autoradiography, silver grains were found to be highly localized over cell bodies of vagal sensory neurones. An excess of CCK-8S inhibited binding as did Devazepide, but not L-365,260, confirming that binding sites were CCKA subtype receptors. These results indicate the existence of functional CCKA receptors in the nodose ganglion and strengthen the case for the involvement of vagal sensory neurones in gastric emptying and satiety.

Animals↗
PubMedDate not supplied

Role of N-linked glycosylation in cell-cycle progression and initiation of DNA synthesis in tumor-transformed human fibroblasts.

In this study we show that proliferation of cycling tumor-transformed human fibroblasts (line 90VAV1) is blocked specifically in G1 by HMG CoA reductase inhibition. This inhibition also resulted in a drastic depression of N-linked glycosylation, measured as incorporation of radioactive glucosamine into acid-insoluble material. Following addition of mevalonate to cells arrested by HMG CoA reductase inhibitors, the depression of N-linked glycosylation was overcome and the cells initiated DNA synthesis. However, if the mevalonate-induced increase in protein glycosylation was prevented, due to addition of tunicamycin (an inhibitor of N-linked glycosylation), the cells were not able to proliferate. If instead tunicamycin was added 4 h after the addition of mevalonate, the cells synthesized DNA normally. Upon addition of tunicamycin, to cycling cells the progression through G1 was blocked in a similar way to that following HMG CoA reductase inhibition. Taken together, our data provide strong evidence for involvement of N-linked glycosylation in the mevalonate-controlled cell cycle progression and growth activation of tumor-transformed human fibroblasts.

Cell Cycle↗