Search PubMed⌕ Search

Biomedical subjects

M Schubert

Publications and source records attributed to M Schubert.

At least 217 records · Page 12Linked to original sources
PubMed1968

The characterization of soluble amyloid prepared in water.

Amyloid was extracted from the spleen of a patient with primary amyloidosis by homogenizing it at high speed with water after preliminary treatments, first to remove proteins soluble in saline, and then to remove salts. The extracts containing amyloid appeared to be clear at concentrations up to 6 mg/ml of protein. The material gave little sediment on being centrifuged up to 20,000 g for 1 hr, but the protein was sedimented at 100,000 g in 1 hr. The amyloid could be precipitated from the extracts by addition of NaCl to 0.0075 mole/liter or of CaCl(2) to 0.0025 mole/liter. The protein-bound Congo red formed a red precipitate and this property was used to estimate recovery and purity of amyloid during extraction. On electronmicroscopy the isolated amyloid proved to be morphologically pure. It existed either as single filaments measuring 60-80 A in diameter or as large aggregates of these filaments.Freshly isolated amyloid in water sedimented as a single homogeneous peak with an s degrees (20,[unk]) of about 45-50S. On standing, the solution became cloudy and more rapidly sedimenting components appeared. On electrophoresis the material migrated as a homogeneous peak towards the anode. The protein had an amino acid composition different from that of all known serum proteins. It was rich in acidic amino acids and had little cysteine and methionine and no hydroxyproline. The total content of carbohydrate was less than 2%.

Amino Acids↗
PubMedDate not supplied

Effects of very low dose and enteric-coated acetylsalicylic acid on prostacyclin and thromboxane formation and on bleeding time in healthy subjects.

OBJECTIVE: Low dose acetylsalicylic acid (ASA) is widely used as an anti-aggregatory agent in the primary and secondary prevention of cardiovascular diseases. In an effort to spare prostacyclin formation and to reduce gastrointestinal side-effects, both very low doses and enteric-coated formulations of ASA have been introduced. However, it still remains unclear whether these different formulations and dosages are equally effective with respect to inhibition of platelet aggregation and thromboxane A2 (TXA2) formation. METHODS: In a randomized study, we therefore investigated the effects of 100 mg ASA plain (p), 100 mg ASA enteric-coated (ec) and 40 mg ASA (p) to 36 healthy male subjects given for 7 days on platelet aggregation and endogenous prostanoid formation rates. Platelet aggregation and platelet TXB2 release in platelet rich plasma (PRP) and serum TXB2 and 6-keto-PGF1alpha levels were determined at baseline and after 7 days of each medication. The urinary metabolites of TXA2 (2,3-dinor-TXB2) and prostacyclin (2,3-dinor-6-keto-PGF1alpha) were measured by gas chromatography/tandem mass spectrometry in 24-h-urines at baseline and on day 7 of each medication. RESULTS: Collagen-induced platelet aggregation was 73.1+/-1.6% of maximal aggregation at baseline. It was inhibited by 68.9%, 58.6% and 24.0% by ASA 100 mg plain, 100 mg enteric-coated, and 40 mg plain on day 7, respectively. Platelet TXB2 release was 11592.0+/-367.5 pg x ml(-1) PRP. It was inhibited by 90.1%, 86.5%, and 55.2% by ASA 100 mg plain, 100 mg enteric-coated, and 40 mg plain, respectively. Serum TXB2 was almost completely reduced on day 7 by 100 mg ASA, but not by 40 mg ASA; serum 6-keto-PGF1alpha was slightly, but significantly reduced in all three groups. Urinary 2,3-dinor-TXB, excretion was 196.0+/-41.5 pg x mg(-1) creatinine at baseline. It was reduced by 80.3% and 79.1% by ASA 100 mg plain and enteric-coated, respectively (each P < 0.05 versus baseline), but only by 55.4% by ASA 40 mg plain (P < 0.05 versus both formulations of ASA 100 mg). CONCLUSIONS: Our present data show that the plain and enteric-coated formulations of 100 mg ASA are equally effective in inhibiting platelet aggregation, platelet thromboxane production, and urinary 2,3-dinor-TXB2 excretion rates. In contrast, a very low dose of 40 mg ASA was significantly less effective in inhibiting these indices of platelet activation in healthy human subjects. ASA enteric-coated 100 mg may be a useful alternative to 100 mg ASA (p) in patients with gastrointestinal side-effects, whereas 40 mg ASA (p) may be too low to inhibit sufficiently platelet activity in patients with cardiovascular diseases in whom platelet activity is increased.

Adult↗
PubMedDate not supplied

AmphiPax3/7, an amphioxus paired box gene: insights into chordate myogenesis, neurogenesis, and the possible evolutionary precursor of definitive vertebrate neural crest.

Amphioxus probably has only a single gene (AmphiPax3/7) in the Pax3/7 subfamily. Like its vertebrate homologs (Pax3 and Pax7), amphioxus AmphiPax3/7 is probably involved in specifying the axial musculature and muscularized notochord. During nervous system development, AmphiPax3/7 is first expressed in bilateral anteroposterior stripes along the edges of the neural plate. This early neural expression may be comparable to the transcription of Pax3 and Pax7 in some of the anterior neural crest cells of vertebrates. Previous studies by others and ourselves have demonstrated that several genes homologous to genetic markers for vertebrate neural crest are expressed along the neural plate-epidermis boundary in embryos of tunicates and amphioxus. Taken together, the early neural expression patterns of AmphiPax3/7 and other neural crest markers of amphioxus and tunicates suggest that cell populations that eventually gave rise to definitive vertebrate neural crest may have been present in ancestral invertebrate chordates. During later neurogenesis in amphioxus, AmphiPax3/7, like its vertebrate homologs, is expressed dorsally and dorsolaterally in the neural tube and may be involved in dorsoventral patterning. However, unlike its vertebrate homologs, AmphiPax3/7 is expressed only at the anterior end of the central nervous system instead of along much of the neuraxis; this amphioxus pattern may represent the loss of a primitive chordate character.

Amino Acid Sequence↗
PubMedDate not supplied

Characterization of amphioxus AmphiWnt8: insights into the evolution of patterning of the embryonic dorsoventral axis.

The full-length sequence and developmental expression of an amphioxus Wnt gene (AmphiWnt8) are described. In amphioxus embryos, the expression patterns of AmphiWnt8 suggest patterning roles in the forebrain, in the hindgut, and in the paraxial mesoderm that gives rise to the muscular somites. Phylogenetic analysis indicates that a single Wnt8 subfamily gene in an ancestral chordate duplicated early in vertebrate evolution into a Wnt8 clade and a Wnt8b clade. Coincident with this gene duplication, the functions of the ancestral AmphiWnt8-like gene appear to have been divided between vertebrate Wnt8b (exclusively neurogenic, especially in the forebrain) and vertebrate Wnt8 (miscellaneous, especially in early somitogenesis). Amphioxus AmphiWnt8 and its vertebrate Wnt8 homologs probably play comparable roles in the early dorsoventral patterning of the embryonic body axis.

Amino Acid Sequence↗
PubMedDate not supplied

Decreased trigeminal sensitivity in anosmia.

The present study aimed to investigate intranasal trigeminal sensitivity in a large sample of patients with anosmia due to different etiologies. We investigated the trigeminal detection threshold for formic acid in healthy controls (n = 96) and patients with anosmia due to head trauma (n = 18) or sinonasal disease (n = 54). Anosmics exhibited higher thresholds compared with normosmics (p < 0.001). In addition, thresholds were found to be higher in patients with posttraumatic anosmia compared to anosmics with sinonasal disease (p < 0.001). The data indicate that (1) loss of olfactory sensitivity in humans may be associated with a decreased sensitivity towards trigeminal stimuli and (2) alteration of intranasal trigeminal function is stronger in patients with posttraumatic anosmia compared to patients with sinonasal disease. This may have implications for the medicolegal investigation of anosmic patients where trigeminal stimuli are frequently used to assess the patient's response bias.

Adolescent↗
PubMedDate not supplied

[Rational diagnosis of endocrine forms of hypertension].

Primary aldosteronism, Cushing's syndrome and pheochromocytoma are the most frequent endocrine hypertensive disorders. Following biochemical confirmation of the clinical diagnosis, mainly non-invasive imaging techniques are necessary to determine the cause of the hormone excess. Diagnosis of primary aldosteronism is confirmed by analysis of aldosterone and renin in peripheral venous blood. Differentiation between adenoma and idiopathic adrenal hyperplasia usually is achieved by computed tomography and isotope scan. A reliable test for the biochemical confirmation of Cushing's syndrome is the determination of urine-free cortisol. In patients with equivocal results the dexamethasone suppression test is performed. Differential diagnosis between ACTH-dependent Cushing's syndrome (pituitary or ectopic) and primary adrenal disorders can be made by determination of plasma-ACTH and -cortisol. Non-invasive localization procedures include computed tomography of the abdomen, computed tomography or magnetic resonance imaging of the pituitary gland, sonography and isotope scan. Diagnosis of pheochromocytoma is based on elevated catecholamine levels in urine or plasma. The tumor is localized by ultrasound, computed tomography or isotope scan.

Adrenal Gland Neoplasms↗