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Biomedical subjects

M Lang

Publications and source records attributed to M Lang.

At least 199 records · Page 11Linked to original sources
PubMed1985

Regulation of pro-opiomelanocortin synthesis by dopamine and cAMP in the amphibian pituitary intermediate lobe.

The modulation of pro-opiomelanocortin (POMC) synthesis in Xenopus laevis pituitary intermediate lobe (IL) during background adaptation and the role of dopamine and cAMP in mediating this effect were examined. Neurointermediate lobes (NILs) were pulselabeled in vitro with [3H]arginine and analyzed for POMC synthesis by acid-urea gel electrophoresis. After black background adaptation of the animal (7 days), POMC synthesis increased 5-6-fold, while after white background adaptation (7 days), POMC synthesis decreased by 76%. Dopamine (50 microM) suppressed POMC synthesis in NILs in culture. In the absence of dopamine, POMC synthesis was stimulated. Several experiments were conducted to determine the category of dopamine receptor in the X. laevis IL. A D-2 dopamine receptor agonist inhibited immunoreactive alpha-MSH release from the NIL in a D-2 antagonist-reversible manner. A D-1 receptor agonist or antagonist did not alter the release of immunoreactive alpha-MSH from the NIL. Dopamine (10 microM) inhibited forskolin-stimulated cAMP accumulation. In addition, dopamine inhibition of POMC synthesis in cultured ILs was reversed by 8-Br-cAMP. These studies suggest that white background adaptation results in stimulation of the X. laevis D-2 receptor, which reduces cAMP production and POMC synthesis. Conversely, during black background adaptation the IL D-2 receptor is not stimulated, leading to increased cAMP production and POMC synthesis.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1985

Comparison of kidney, lung and liver coumarin 7-hydroxylases in phenobarbital pretreated DBA/2J and C57BL/6J mice.

In this paper we describe catalytic and immunological properties of coumarin 7-hydroxylase, a cytochrome P-450 dependent enzyme activity, in the liver, kidney and lung of C57BL/67 and DBA/2J mice. Coumarin 7-hydroxylase activity was higher in D2 than in B6 mice in all three organs. For both strains of mice, liver had the highest enzyme activity when expressed per milligram of microsomal protein. However, when expressed per nmole cytochrome P-450 there was no difference in the enzyme activity between the tissues. Inhibition of microsomal coumarin 7-hydroxylase by antibodies previously developed in our laboratory against a cytochrome P-450 fraction from D2 and B6 mouse liver, associated with coumarin 7-hydroxylase, occurred as follows. In D2 mice both antibodies caused approximately 50% inhibition of the enzyme activity of all three organs. In B6 mice, however, the only organ where considerable inhibition took place was the liver, and only when antibody against B6 cytochrome P-450 was used. Ouchterlony immunodiffusion analysis revealed a 100% crossreactivity between the two strains of mice when similar organs were compared. The 100% crossreactivity was also found between the liver and lung in both strains of mice. However, only a 50% crossreactivity was found between kidney and liver or kidney and lung in B6 and between the kidney and lung in D2. The data demonstrate interorgan and interstrain differences in the immunological and catalytical properties of cytochrome(s) P-450 catalysing coumarin 7-hydroxylation.

Animals↗
PubMed1985

Neuropsychological and neuroendocrinological disturbances associated with extracerebral cysts of the anterior and middle cranial fossa.

In ten adult patients various clinical signs and symptoms led to the diagnosis of an arachnoid cyst in the anterior and middle cranial fossa. In this study a functional relationship between these cysts and disturbances of higher cognitive processes is described. In addition, neuroendocrinological impairment were caused by arachnoid cysts reaching into the suprasellar cistern. Considering the short medical history of our patients we presumed the disturbances not to be primary, but rather secondary, caused by an expansion of the cysts' volume.

Adult↗
PubMed1985

Specific staining of human chromosomes in Chinese hamster x man hybrid cell lines demonstrates interphase chromosome territories.

In spite of Carl Rabl's (1885) and Theodor Boveri's (1909) early hypothesis that chromosomes occupy discrete territories or domains within the interphase nucleus, evidence in favor pf this hypothesis has been limited and indirect so far in higher plants and animals. The alternative possibility that the chromatin fiber of single chromosomes might be extended throughout the major part of even the whole interphase nucleus has been considered for many years. In the latter case, chromosomes would only exist as discrete chromatin bodies during mitosis but not during interphase. Both possibilities are compatible with Boveri's well established paradigm of chromosome individuality. Here we show that an active human X chromosome contained as the only human chromosome in a Chinese hamster x man hybrid cell line can be visualized both in metaphase plates and in interphase nuclei after in situ hybridization with either 3H- or biotin-labeled human genomic DNA. We demonstrate that this chromosome is organized as a distinct chromatin body throughout interphase. In addition, evidence for the territorial organization of human chromosomes is also presented for another hybrid cell line containing several autosomes and the human X chromosome. These findings are discussed in the context of our present knowledge of the organization and topography of interphase chromosomes. General applications of a strategy aimed at specific staining of individual chromosomes in experimental and clinical cytogenetics are briefly considered.

Animals↗
PubMed1985

Catalytic and immunological comparison of coumarin 7-hydroxylation in different species.

Coumarin 7-hydroxylation activities were determined in the liver microsomes of eight different species: pig, mouse (three strains), rat, hamster, guinea-pig, rabbit, rainbow trout and crayfish. A high coumarin 7-hydroxylase activity was found in the microsomes of D2 mouse, rabbit, hamster and pig, an intermediate activity in case of B6 and AKR mice, rat and guinea-pig and a very low activity in rainbow trout and crayfish. In Ouchterlony immunodiffusion analysis our antibody against coumarin 7-hydroxylase specific cytochrome P-450 from D2 mice was able to form a weak precipitin line only with rat and hamster microsomes in addition to the three strains of mice (D2, B6, AKR) where the band was very sharp. Strongest inhibition by the antibody (50% or more) of microsomal coumarin 7-hydroxylase was found in the case of the three strains of mice and rabbit. In the case of the other species the inhibition was very weak or did not exist.

Animals↗
PubMed1985

Rickets of prematurity: calcium and phosphorus supplementation.

Seventy-four infants weighing less than 1500 gm at birth were fed enterally from birth until day 47. Group A (18 infants) were given SMA Gold Cap: group B (18 infants), supplementary calcium to 21 mmol/L (84 mg/dl); group C (16 infants), further calcium supplementation to 31.2 mmol/L (125 mg/dl); and group D (22 infants), milk with calcium content 31.2 mmol/L (125 mg/dl) and phosphorus supplementation to 15.7 mmol/L (49 mg/dl). The addition of calcium reduced the radiologic evidence of rickets, and combined calcium and phosphorus supplementation maintained plasma alkaline phosphatase activity within the normal range for 6 weeks.

Alkaline Phosphatase↗
PubMed1985

Organization, sequence and expression of the HLA-B27 gene: a molecular approach to analyze HLA and disease associations.

Among the numerous autoimmune diseases associated with various HLA alleles, the one with the highest relative risk so far reported has been ankylosing spondylitis with HLA-B27. To examine this relationship more directly, we have cloned the gene encoding the HLA-B27 antigen and determined its complete DNA sequence. Comparison of the HLA-B27 sequence with that of the allelic HLA-B27 shows a high level of homology. Mutations are distributed evenly between exons and introns. Exon 1 and intron 1 are the most divergent ones, and the degree of divergence distinctly declines towards the 3' end. The HLA-B57 gene when transfected into murine L cells is expressed on the cell surface and reacts with a panel of monoclonal antibodies directed against monomorphic and polymorphic determinants associated with HLA-B27 antigen. The isolation of this gene allows for the first time a search for structural features which make the HLA-B27 antigen a high risk genetic factor for a group of rheumatoid disorders, in particular ankylosing spondylitis.

Amino Acid Sequence↗
PubMed1985

Imparied atrial receptor modulation or renal nerve activity in dogs with chronic volume overload.

Left atrial receptors with vagal afferents are reset and become less sensitive in dogs with chronic high output congestive heart failure (Zucker et al J Clin Invst 1977;60:323). We determined if the normal reflex inhibition of renal sympathetic nerve activity (RNA) which occurs in response to left atrial distension is altered in dogs with chronic volume overload produced by an aorto-vena caval fistula (AVF). In addition, we examined the ability of the arterial baroreflex to alter RNA. In normal dogs, left atrial distension decreased RNA by 6.8 +/- 1.8% per mmHg change in left atrial pressure (LAP). After carotid sinus denervation (CSD), this inhibition was increased to 10.9 +/- 1.4% per mmHg change in RNA in response to left atrial distension. Vagotomy completely abolished any change in RNA in response to left atrial distension. In contrast, dogs with chronic AVF's demonstrated an increase in RNA in response to left atrial distension by 4.5 +/- 3.9% per mmHg change in LAP. The response of the AVF dogs was significantly different from the normal dogs (P less than 0.005). This was also the case after CSD. Loading and unloading of the arterial baroreceptors with norepinephrine and nitroprusside demonstrated that the modulation of RNA by arterial baroreceptors was similar in AVF dogs compared with normal dogs. The present study demonstrates that chronic volume overload results in a decrease in the peripheral sympathetic inhibitory effects of left atrial receptor stimulation at a time when arterial baroreceptor function is preserved.

Animals↗
PubMed1985

Timing function of the frontal cortex in sequential motor and learning tasks.

The timing aspects of human frontal lobe function are discussed in the light of the results of three experiments on movement-related cerebral potentials. Experiment I is based on use of a sequential tracking task and experiment II a motor learning task; experiment III deals with frontal hemispheric specialisation by comparing self-initiated writing and drawing. The Bereitschaftspotential (BP) preceding voluntary movement is maximum over the supplementary motor area (SMA) for all movements, including finger, toe, speech, and eye movements, regardless of each movement's different localisation in the brain, e.g., motor cortex, temporal lobe, or midbrain. The assumption that all motor events are governed by the primary (rolandic) motor cortex is erroneous. The motor system is widely decentralised. It is only when this decentralization is recognized that the close temporal association between the onset of all movements and the preceding Bereitschaftspotential in the SMA can be understood. A plausible explanation would be that the SMA decides on the starting time of all the various movements. The frontal function of motivation is not a single entity but has several subfunctions. It has to decide what to do, how to do and when to do. The latter is probably the task of the SMA. A comparison of different motivational situations makes this clear. In the usual BP paradigm, such as self-initiated simple finger or eye movements, only the SMA becomes active among all the frontal areas. If, however, motivation is required to modify motor programs in motor learning, as it is in experiment II, the entire convexity of the frontal lobe shows a large surface-negative potential, the amplitude of which reveals a significant positive correlation with the success in learning. On the other hand, in experiment I, which uses a manual pursuit-movement task requiring attention to unpredictable changes in stimulus direction but providing a fixed time for these changes (so that their timing is foreseeable), the SMA shows anticipatory behaviour; it takes the form of a large negative potential which ceases 0.5 s prior to the end of the directed-attention potential over parietooccipital areas. In other words, in this special situation, where the SMA can anticipate the onset of movement, it seems to delegate the final execution of the movement to the cortical area most specialised for it, in this case the parietooccipital cortex. The supervision of the tasks concerning what to do and how to do may be provided mainly by the orbital cortex and the frontolateral cortex, respectively (Kleist 1934).(ABSTRACT TRUNCATED AT 400 WORDS)

Cerebral Cortex↗
PubMed1984

C4 polymorphism in the dog: molecular heterogeneity of the C4 alpha and C4 gamma subunit chains.

Using an immunoblotting technique and goat antihuman C4, we observed five distinct electrophoretic variants of C4 in a panel of 60 random dogs. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of immunoprecipitated C4 showed that dog C4 is composed of three polypeptide subunit chains (alpha, beta, and gamma) and that structural variability occurs within the alpha- and gamma-chain regions. Two distinct molecular weight forms of both the C4 alpha- (alpha A and alpha B) and C4 gamma- (gamma A and gamma B) chain were detected. The variant forms of C4 alpha and C4 gamma were found in association with particular C4 allotypes.

Animals↗
PubMed1984

Septicemia caused by Kingella kingae.

A case of Kingella kingae septicemia following acute gastroenteritis is described. Intravenous antibiotic treatment with mezlocillin and tobramycin led to rapid and sustained recovery. The infection with Kingella kingae may have been food-borne.

Acute Disease↗
PubMed1984

Brain potentials related to voluntary hand tracking, motivation and attention.

While there are many behavioural studies available investigating human hand tracking performance, there are none that include recording of cerebral potentials. Sixteen subjects tracked a visual or a tactile target by moving a stylus with their right hand. They voluntarily started the stimulus, which moved for 1 s in a first random direction, then for 1's in another direction. The stimulus was given to the left field of vision or tactually to the left palm. Tracking was compared to no-tracking controls. The voluntary initiation was preceded by a Bereitschaftspotential (BP), the change in direction by a contingent negative variation (CNV). Both BP and CNV showed a characteristic right hemispheric parietooccipital (visual task) or centro-parietal asymmetry (tactile task) due to the attention paid to the expected stimulus event ("directed attention potential", DAP). While the DAP outlasted stimulus onset by 0.2 s, fronto-midline areas switched already to positivity 100 ms prior to stimulus onset and more than 300 ms prior to the change in direction. Large P300-like components were elicited by stimulus onset and change in direction.

Attention↗