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Biomedical subjects

R Maier

Publications and source records attributed to R Maier.

At least 109 records · Page 6Linked to original sources
PubMed1990

[A femur head preserving osteosynthesis procedure in para-articular femoral fracture of the hip in cardiopulmonary at-risk patients].

A series of 224 patients with fractures near the hip joint underwent internal fixation with conservation of the femoral head. Between January 1983 and December 1987 the operations with conservation of the femoral head were performed with Ender pins and Böhler nails. From January 1988 to December 1988 dynamic hip screws (DHS) were used exclusively for conservation of the femoral head. The patients were divided into three risk groups by preoperative cardiac and pulmonary risk score. In a retrospective study we compared different osteosyntheses for lethality, complications and duration of stay in hospital. The lethality with DHS was lower in risk groups II and III. The complication rate was significantly lower (P less than 0.05) in the group with DHS. The duration of hospital stay was significantly shorter (P less than 0.001) in the group in which DHS were used.

Aged↗
PubMed1989

The possible role of histamine-mediated cAMP formation as a link between H2-receptor stimulation and ultrastructural changes in guinea-pig oxyntic cells.

Guinea-pig oxyntic cell tubulin has been isolated and in vitro aggregation has been studied. The spontaneous assembly of isolated tubulin was significantly accelerated and increased by 1 mmol/l GTP. Histamine and forskolin increased tubulin polymerization only when detergent dispersed oxyntic cells or crude membranes were added. The forskolin response occurred very rapidly with an EC50 of approximately 30 mumol/l and did not require GTP. Histamine promoted tubulin aggregation with an EC50 of about 5 mumol/l only in the presence of GTP. Ranitidine completely inhibited the effects of histamine. From these data it is suggested that, in the oxyntic cell, histamine H2-receptor activated adenylate cyclase and the corresponding increase in cAMP play a role in eliciting characteristic ultrastructural changes by initiating formation of microtubules as a first step in the cascade of events leading to an increase in the secretory surface area.

Animals↗
PubMed1989

Binding site for IgE of the human lymphocyte low-affinity Fc epsilon receptor (Fc epsilon RII/CD23) is confined to the domain homologous with animal lectins.

The lymphocyte low-affinity receptor for IgE (Fc epsilon RII) is involved in two seemingly unrelated processes: (i) promotion of general B-cell growth and (ii) isotype-specific IgE synthesis. To characterize domains of Fc epsilon RII important for effector function, we have expressed Fc epsilon RII mutants in mammalian cells. The results show that the IgE-binding region of Fc epsilon RII corresponds almost exactly to a domain of 123 amino acid residues homologous with the carbohydrate-binding domain of C-type animal lectins. With the recent demonstration that Fc epsilon RII binds to IgE independently of any lectin-like activity [Vercelli, D., Helm, B., Marsh, P., Padlan, E., Geha, R.S. & Gould, H. (1989) Nature (London) 338, 649-651], it is now clear that, in this case, the lectin module has evolved to interact with a protein rather than a carbohydrate moiety. The epitopes of several independent monoclonal antibodies that inhibit the binding of IgE to Fc epsilon RII are clustered within the lectin-like domain. Some of these antibodies are also known to suppress, isotype-specifically, the interleukin 4-promoted IgE synthesis from peripheral blood mononuclear cells or the spontaneous synthesis of IgE by B cells isolated from atopic donors. The epitope of MHM6, an anti-F epsilon RII monoclonal antibody delivering an epitope-restricted growth-promoting effect on B cells, is also located within the lectin-like domain. Thus, the lectin module of Fc epsilon RII not only acts as a carbohydrate-independent, isotype-specific Fc receptor but may also participate in the general regulation of B-cell growth.

Animals↗
PubMed1988

Separation of the protein-tyrosine kinase and phosphatidylinositol kinase activities of the human placental insulin receptor.

On immunoprecipitation using a specific antiphosphotyrosine antibody, phosphatidylinositol kinase (EC 2.7.1.67) activity was separated from the protein-tyrosine kinase (EC 2.7.1.112) activity of the wheat germ agglutinin (WGA) -purified insulin receptor from human placenta. This clearly indicates that protein-tyrosine kinase and phosphatidylinositol kinase activity do not reside on the same polypeptide chain as previously has been suggested. Quantitatively, the fraction of phosphatidylinositol kinase that was bound to WGA sepharose and eluted together with the insulin receptor amounted to 2% of the Triton X-100 soluble phosphatidylinositol kinase. The apparent Km values of the bound and unbound phosphatidylinositol kinase with respect to PI and ATP were very similar (0.4 and 0.3 mmol/l and 8 and 7 mumol/l, respectively) suggesting that the WGA-bound phosphatidylinositol kinase is not a different enzyme, but rather represents a small portion of the bulk Triton X-100-soluble phosphatidylinositol kinase that is bound to the lectin tightly associated with the insulin receptor. The synthetic polymer (Glu80Tyr20)n, a model substrate of the insulin receptor tyrosine kinase, at 0.5 mmol/l, inhibited phosphatidylinositol kinase of WGA-purified insulin receptor by 70-90%. This inhibition was not overcome by increasing the concentrations of ATP or PI as one would expect if a functional interrelationship of the protein-tyrosine kinase and the phosphatidylinositol kinase would exist.

1-Phosphatidylinositol 4-Kinase↗
PubMed1987

Congenital nephrogenic diabetes insipidus-vasopressin and prostaglandins in response to treatment with hydrochlorothiazide and indomethacin.

In four boys with congenital nephrogenic diabetes insipidus, plasma arginine-vasopressin (AVP) and urinary excretion of prostaglandins were studied in response to treatment with hydrochlorothiazide and indomethacin. An abnormal relationship between AVP and urine osmolality was demonstrated in all patients. In the first patient, treatment with indomethacin (3 mg/kg per day) resulted in a drop of the insulin and paraminohippurate clearances. In the other three patients urinary excretion of PGE2 was raised, and fell during treatment with hydrochlorothiazide (2 mg/kg per day) and indomethacin (2 mg/kg per day). Urine flow, free water clearance and osmolar clearance decreased during treatment. A combination of both drugs is more effective than hydrochlorothiazide alone and the effect appears to be additive.

Child↗
PubMed1987

Analysis of lipids containing hydroxy fatty acids.

Lipids containing hydroxy fatty acids or hydroxyacyl moieties are acetylated with [1-14C]acetic anhydride or [3H]acetic anhydride, and the content of hydroxy fatty acids or hydroxyacyl moieties is estimated from the specific radioactivity of the acetylated products with respect to that of radioactive standards, such as radioacetylated ricinoleic acid or triricinoleoylglycerol. Mixtures of triacylglycerols containing one, two and three hydroxyl groups per molecule are derivatized in a similar manner, and the resulting acetates are fractionated by thin layer chromatography according to the number of acetate groups per molecule. The relative proportion of each type of triacylglycerols in the mixture is estimated from the distribution of radioactivity in the various fractions. Applications of these techniques are demonstrated by the analysis of several seed lipids.

Hydroxy Acids↗
PubMed1987

Long-term observations in mild forms of cardiomyopathy.

24 patients suffering from a mild cardiomyopathy with normal or nearly normal ejection fraction and histologic evidence of cardiac fiber hypertrophy were followed-up over 5.5 +/- 1.9 years. Patients presented predominantly with dyspnea, angina and palpitations. During the observation period, the severity of symptoms increased only slightly. The ECG showed atrial arrhythmias in 34% and premature ventricular beats or conduction disturbances in the majority. During the 5.5 year follow-up period four patients had developed an intermittent III AV-block and two patients a bundle branch block. The heart volume determined by X-ray increased insignificantly (893 +/- 224 to 933 +/- 245 ml/1.73 m2; n.s.), while left ventricle end-diastolic (5.5 +/- 1.1 to 5.6 +/- 0.6 cm) and end-systolic (3.9 +/- 1.2 to 3.7 +/- 0.7 cm) diameter remained nearly constant. Pulmonary artery pressure at rest (18 +/- 5.9 to 17.8 +/- 4 mm Hg) and during exercise (40.5 +/- 9.5 to 37.4 +/- 7.8 mm Hg) showed no significant change. However, cardiac output decreased significantly at rest from 5.6 +/- 1.6 l/min/1.73 m2 to 4.5 +/- 0.7 l/min/1.73 m2 (p less than 0.01) and during exercise from 13 +/- 4.1 l/min/1.73 m2 to 10.4 +/- 2.3 l/min/1.73 m2 (p less than 0.05). It is concluded that patients with this mild cardiomyopathy show only minor changes over a period of 5.5 years. The prognosis seems to be promising in most cases.

Adult↗
PubMed1986

Elastase-producing microorganisms in horse lungs: their possible role in the pathogenesis of chronic pulmonary disease in the horse.

Seventeen out of 21 horses had pulmonary microbial organisms which reached considerable numbers in seven cases. Elastase-producing microorganisms from the environment (Streptomyces species and to a lesser extent Bacillus species) constituted 22 per cent to 99 per cent (mean 79 per cent) of the total growth. There was a considerable number of microorganisms with in vitro-produced elastases which were not or only slightly affected by horse serum. There was no correlation between numbers of organisms and pulmonary histopathological findings thus the significance of these microorganisms in the pathogenesis of alveolar emphysema is unknown. The growth of a strain of Streptomyces collinus/diastatochromogus isolated from the lungs was suppressed by fresh horse serum but not by decomplemented horse serum. Complement activation in response to this organism could contribute to airway inflammation through the production of mediators.

Animals↗
PubMed1986

Synthesis and antimicrobial activity of 7 alpha-methoxypyrimidinyl-ureidocephalosporins.

The synthesis of a series of 7 alpha-methoxy-7-[(R)-2-[3-[5-pyrimidinyl]ureido]-2-(4-hydroxyphenyl) acetamido]-3-cephem-4-carboxylates 2 is described. 7-[(R)-2-[3-[2-(p-Aminosulfonyl)-anilino-4-hydroxy-5-pyrimidinyl]ureido- 2-(4-hydroxyphenyl)acetamido]-7 alpha-methoxy-3-[(1-methyl-1H-tetrazol-5 -yl)thio]methyl-3-cephem-4-carboxylic acid, sodium salt (2k, UG-FA 132), has exhibited a broad range of antimicrobial activity. UG-FA 132 is highly active against Gram-positive and Gram-negative organisms, including Pseudomonas and lactamase producers, and shows potent activity against anaerobes. The high efficacy of UG-FA 132 was confirmed by in vivo experiments in mice.

Animals↗
PubMed1985

Synthesis and antibacterial activity of pyrimidinylureidopenicillins.

The 6R-[(R)-2-[3-[5-pyrimidinyl]ureido]-2-(4-hydroxyphenyl) acetamido]-penicillanic acids (10), prepared by two synthetic routes, exhibit broad antimicrobial activity against Gram-positive and Gram-negative bacteria. Their structure activity relationships are discussed. 6R-[(R)-2-[3-[2-(p-Aminosulfonyl)anilino-4-hydroxy-5-pyrimidinyl] ureido]-2-(4-hydroxyphenyl)acetamido]-penicillanic acid, sodium salt (VX-VC 43, 10m), the most active compound, shows very low MIC (minimal inhibitory concentration) values against clinically important Gram-negative bacteria, primarily Pseudomonas aeruginosa.

Gram-Negative Bacteria↗
PubMed1985

Synthesis and antimicrobial activity of pyrimidinylureidocephalosporins.

The synthesis of a series of 7R-[(R)-2-[3-[5-pyrimidinyl]ureido]-2-(aryl)acetamido]-3-cephem-4- carboxylates is described. Variation of the substituents at the 3-position in the cephem nucleus, at the 2-position of the pyrimidine ring, and of the phenyl residue in the acyl side chain is carried out. Qualitative structure-activity relationships in this series are discussed. VX-VD 2, the most interesting compound, exhibits broad antimicrobial activity against Gram-negative bacteria, including Pseudomonas aeruginosa.

Bacteria↗
PubMed1984

Effects of dynorphin A (1-17), dynorphin A (1-13) and D-ala2-D-leu5-enkephalin on the excitability of pyramidal cells in CA1 and CA2 of the rat hippocampus in vitro.

The effects of D-ala2-D-leu5-enkephalin (DADL), dynorphin (DYN) A (1-17), and DYN A (1-13) on the excitability of hippocampal (HC) pyramidal cells in CA1 and CA2 were compared in an in vitro preparation of the rat. DADL and DYN A (1-13) increased the size of the population spike (PS) evoked in CA1 and CA2 by stimulation of the stratum radiatum. Paired-pulse stimulation showed that both peptides decreased the inhibition produced by the conditioning stimulus. These effects were naloxone-reversible. DYN A (1-17) decreased the PS in CA2 and increased the inhibition evoked by the conditioning stimulus. When applied in the same concentration-range, the depressant effects of DYN A (1-17) were more pronounced in CA1 than in CA2 and not naloxone-reversible. DYN A (1-17) reduced the excitatory effects of DADL. Low concentrations of DYN A (1-17) (0.1 nM) produced, like DYN A (1-13) and DADL, an increase in the PS in CA1 in the majority of tests. The present data suggest that DYN A (1-17) shows the excitatory action of other opioids HC pyramidal cells only at low concentration.

Animals↗
PubMed1984

2-[N-[(S)-1-ethoxycarbonyl-3-phenylpropyl]-L-alanyl]-(1S,3S,5S) -2-azabicyclo[3.3.0]octane-3-carboxylic acid (Hoe 498)--a new and highly effective angiotensin I converting enzyme inhibitor.

2-[N-[(S)-1-Ethoxycarbonyl-3-phenylpropyl]-L-alanyl] - (1S,3S,5S) -2-azabicyclo [3.3.0] octane-3-carboxylic acid (Hoe 498) is a new, very effective and long lasting, nonsulfhydryl angiotensin I converting enzyme inhibitor. Using hip-his-leu as substrate, the IC50-values for Hoe 498 and its diacid derivative were 26 or 4.2 nmol/l, respectively. Hoe 498 acts as a prodrug. It is hydrolyzed by an esterase into its active diacid derivative. Sera contain high esterase activities. In comparison to sera from man, dog and rabbit, rat sera have the highest esterase activity. Hoe 498 or its diacid derivative do not modulate the membrane bound adenylatecyclase system of tissues under investigation. The results are discussed in respect of the regulation of the angiotensin II-synthesis and to the regulation of Ca2+-channels in membranes.

Adenylyl Cyclase Inhibitors↗
PubMed1984

[Postnatal enlargement of the foramina rotundum, ovale et spinosum and their topographical changes].

In the newborn the Canalis (Foramen) rotundus is about 2.5 mm and in 15-til 17-year-old about 3 mm in length. The Apertura interna postnatal develops in width from 2.06 to 3.50 mm and in height from 1.8 to 2.73 mm. From the median sagittal plane the medial rim of the Apertura interna is distant about 11.0 mm in newborns and in adults 16.47 mm on the right side and 17.63 mm on the left side. Moreover the angular distance of the axis of the Canalis rotundus just across the median plane and also just across the frankfurt plane were determined. In the newborn the Foramen ovale is about 3.85 mm and in the adults about 7.2 mm in length. The width extend from 1.81 mm in the newborn to 3.7 mm in adults. In the newborn the distance from the medial rim to the median sagittal plane is about 3.9 mm, in the adults at the right side 20.9 mm and at the left side 22.5 mm in length. In the newborn the Foramen venosum (Vesalii) is about 1.0 mm in length and in the adults at the right side about 2 mm and at the left side 1.4 mm. The width increases from 1.0 to 1.14 mm at the right side and to 1.3 mm at the left side. The mean distance opposite to the median sagittal plane increases between newborn time and the adults from 10.0 mm at the right side to 15.78 mm and at the left side from 10.75 to 17.62 mm. In the newborn the Foramen spinosum is about 2.25 mm and in the adults about 2.56 mm in length. The width extends from 1.05 mm to about 2.1 mm in the adults. The distance opposite to the median sagittal plane in the newborn run to about 18.2 mm and in the adults 28.08 mm at the right side and 29.76 mm at the left side. The maximum length of the "Canalis spinosus" increases from 2.85 mm in the newborn to 7.35 mm in the adults. The lateral rim of the Foramen rotundum has a mean distance of 20.0 mm opposite to the upper edge of the Processus zygomaticus above the Tuberculum articulare in the newborn and about 43.5 mm in the adults. The mean distance from the cited reference area to the lateral rim of the Foramen ovale increases from about 15 to 34.33 mm, and from that of the Foramen spinosum from 15.3 to 31.4 mm.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1984

[State dependent modification of auditory brain stem potentials].

It is well known, amplitudes and latencies of auditory brain stem potentials are almost independent of viligance state. Contrary to that, simple cognitive requirements effect amplitude changes (enhancement of variance, amplitude reduction) in a part 2/3) of the subjects.

Adolescent↗
PubMed1983

A new bioactive form of human calcitonin.

Distinct immunoreactive forms of calcitonin (CT), extracted with 2 M acetic acid from two pancreatic tumors, were characterized and identified by gel permeation chromatography and by reverse-phase high-performance liquid chromatography. The extracted CT forms were compared to CT obtained from medullary thyroid carcinoma and from normal thyroid glands, and were, furthermore, analyzed in a rat hypocalcemic bioassay. On gel filtration analysis, two broad peaks coeluting with synthetic human CT-(1-32) and extracted dimeric CT, respectively, were found in variable amounts. An acetonitrile gradient high-performance liquid chromatography system revealed two to three predominant CT peaks. Biologically active monomeric and dimeric CT and the biologically inactive sulfoxide form of human CT-(1-32) have been identified. Moreover, we have detected for the first time a new biologically active CT-like component which was most prominently recognized in a benign pancreatic tumor.

Aged↗