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Biomedical subjects

G Schmidt

Publications and source records attributed to G Schmidt.

At least 19 recordsLinked to original sources
PubMed1992

Isolation, crystallization, crystal structure analysis and refinement of B-phycoerythrin from the red alga Porphyridium sordidum at 2.2 A resolution.

The light-harvesting pigment-protein complex B-phycoerythrin from the red alga Porphyridium sordidum has been isolated and crystallized. B-Phycoerythrin consists of three different subunits forming an (alpha beta)6 gamma aggregate. The three-dimensional structure of the (alpha beta)6 hexamer was solved by Patterson search techniques using the molecular model of C-phycocyanin from Fremyella diplosiphon. The asymmetric unit of the crystal cell (space group P3, with a = b = 111.2 A, c = 59.9 A, alpha = beta = 90 degrees, gamma = 120 degrees) contains two (alpha beta) monomers related by a local dyad. Three asymmetric units are arranged around the crystallographic 3-fold axis building an (alpha beta)6 hexamer, as in C-phycocyanin. The crystal structure has been refined by energy-restrained crystallographic refinement and model building. The conventional R-factor of the final model was 18.9% with data to 2.2 A resolution. The molecular structures of the alpha and beta-subunits resemble those of C-phycocyanin. Major changes in comparison to phycocyanin are caused by deletion or insertion of segments involved in protein-chromophore interactions. The singly linked phycoerythrobilin chromophores alpha-84, alpha-140a, beta-84 and beta-155 are each covalently bound to a cysteine by ring A. The doubly linked chromophore beta-50/beta-61 is attached at cysteine beta-50 through ring A and at cysteine beta-61 through ring D. B-Phycoerythrin contains additionally a 30 kDa gamma-subunit, which is presumably located in the central cavity of the hexamer. It is disordered, as a consequence of crystal and local symmetry averaging.

Amino Acid Sequence↗
PubMed1992

Isolation and characterization of bacteriophages specific for capsular antigens K3, K7, K12, and K13 of Escherichia coli.

Four bacteriophages recognizing the Escherichia coli capsular antigens K3, K7, K12, and K13, respectively, were isolated from pooled sewage samples. The nucleic acid of these phages was identified as double-stranded DNA of different size (phi K3, 71.3; phi K7, 32.8; phi K12, 42.9; phi K13, 43.4 kbp). Three of these phages belonged to Bradley's morphology group C and were specific for K3, K7, and K12 antigens, respectively. The phage phi K13 (Bradley's group A) attacked not only E. coli K13 strains but also E. coli producing the closely related K20 and K23 antigens. It is suggested that the common basic repeating units occurring in these capsular polysaccharides are the primary receptor of phi K13. It could be demonstrated that the four phages were able to depolymerize enzymatically the capsular polysaccharides isolated from the respective host strains.

Antigens, Bacterial↗
PubMed1992

Is Escherichia coli invading tubuloepithelial cells?

The adhesion of Escherichia coli to host epithelium cells is the very first step of urinary tract infections followed by the internalization of the bacteria into these cells. These steps are influenced by several surface antigens or products of the pathogen, e.g. fimbriae or adhesins, K antigen, and hemolysin. The bacterial adherence and the internalization of several isogenic E. coli O18 strains differing in the expression of K5 antigen, hemolysin, and type of fimbriae were measured by using a permanent line of porcine tubuloepithelial cells (LLC-PK1). Strains with K5 antigen were reduced in their adherence and internalizability as compared to the K-negative strains. The expression of hemolysin by these strains lead to an increase of adherence and internalization. The internalization of bacteria is influenced mainly by their adherence to the epithelial cells. Thus, the engorgement of attached bacteria is rather a kind of endocytosis than an invasion of bacteria.

Animals↗
PubMed1992

[New anti-arrhythmia agents].

Use of class-I antiarrhythmic agents (encainide, flecainide or moricizine) to suppress asymptomatic ventricular premature depolarizations does not decrease, but rather increases mortality from cardiac events after myocardial infarction. These patients should not be treated with antiarrhythmic drugs until improved survival is shown in a controlled clinical trial. In other clinical conditions such as symptomatic tachyarrhythmias class-I agents should only be used if the expected benefit outweighs the risk of an adverse cardiac effect. The development of new class-I drugs does not seem promising. Esmolol is the first intravenous and ultrashort-acting beta-adrenoceptor blocker that can be used to treat supraventricular arrhythmias in the critical care setting; in addition, it displays high cardioselectivity. Specific class-III antiarrhythmic agents including sematilide and dofetilide have been shown to be effective against ventricular tachyarrythmias in preclinical studies, but their clinical value remains to be established. Torsades de pointes arrhythmia is an undesirable side-effect closely coupled to specific class-III action that may limit their future use. The known pharmacological profiles and limited controlled clinical studies make amiodarone and sotalol promising candidates for drugs that may improve survival of patients at risk for sudden cardiac death.

Adrenergic beta-Antagonists↗
PubMed1992

[Traumatic aneurysm of the hand--a rare complication of a stab injury].

This is a case report of a 22-year-old male who suffered a stab injury to his right hand. Sixteen days after primary wound closure, he complained of pain from a pulsating mass in his right palm, with numbness along the ulnar side of the middle finger. At operation, a false aneurysm was found and resected, after ligation of the common digital artery proximal and distal to the aneurysm.

Adult↗
PubMed1992

[Injuries caused by automobile safety glass].

The report initially discuss the properties and application of tempered glass (TG) and laminated glass (LG) in motor vehicles. Although the trunk and extremities are injured these injuries are seldom life threatening. In contrast, head or neck injuries present a greater threat to life. Especially serious are TG injuries resulting in blindness. The resultant vehicle damage can appear not only as isolated glass cracking, which occurs regularly accompanying injuries without loss of consciousness, but as deformation of the vehicle interior adjacent to the windscreen. In the cases where more solid structures are impacted fatal injuries are possible. This report presents detail both of some real accident investigations and of 9 simulated oblique collisions using 9 post mortem human subjects (PMHS's). In these 9 simulations the head impacted during the primary impact phase against side windows constructed from TG. A modified tempered glass construction (two plates sandwiching a 3 mm air layer) was also tested. Impact angles were 35 to 45 degrees. The severity of facial laceration was dependent on collision severity, type of glass and glass damage resulting from head impact. Minor or severe cutting injuries of the face were caused. Only through the investigation of real accidents and accident simulations can occupant safety be improved.

Acceleration↗
PubMed1992

Does physical exercise influence bowel transit time in healthy young men?

An examination was performed on 20 healthy men, who had a specific diet, to test the influence of moderate physical activity on bowel transit. During a 3-day pause and a 3-day phase of easy sports activity (jogging), oro-anal transit was measured with the help of radiopaque markers (Hinton method). While the subject was under exertion, the entire weight of stool rose significantly (743 vs. 600 g), whereas we found no significant influence on the oro-anal transit time (39 vs. 48 h) or on stool frequency (1.3 vs. 1.3 per day). Moderate physical activity had no effect on bowel transit time of healthy men under a constant diet. The effect of the so often recommended increase of physical activity on constipation remains to be elucidated.

Adult↗
PubMed1992

[On the 150th birthday of the internal medicine clinician Hermann Nothnagel (1841-1905)].

With respect to the present sub-specialization of several clinical specialties of the nineteenth century, the research work of Hermann Nothnagel is described as starting-point of cardiology, gastroenterology, clinical-experimental pharmacology and neurology. The most important topics of his main publications in these fields are enumerated chronologically in this brief presentation of his curriculum vitae. Emphasis is laid on the fact that in his person the variety of research is integrated to represent the unity of classic internal medicine. In 1901, as one of the founders of the "Gesellschaft für innere Medizin" in Vienna, Nothnagel helped to consolidate the independence of this new specialty, which at that time was a domain of general practitioners. In view of the enormous increase in knowledge nearly one century later, the mature branches have separated from the original trunk.

Germany↗
PubMed1991

Interaction of the small proteoglycan decorin with fibronectin. Involvement of the sequence NKISK of the core protein.

Decorin, an interstitial small proteoglycan, was shown to interact with fibronectin via its core protein. In a solid-phase assay, both high-affinity (KD values between 10 and 20 nM) and low-affinity (KD values between 110 and 130 nM) binding sites were found. The central position of decorin core protein is made up of several repeats containing NKISK in positions 85-89 and similar sequences in other repeats. The pentapeptide inhibited, albeit not completely, the high-affinity interaction between decorin and fibronectin in a specific charge-independent manner. Half-maximal inhibition occurred at a peptide concentration of 10 microM. Core-protein-derived peptides that had been produced by endoproteinase Lys-C digestion were not inhibitory, but endoproteinase Arg-C-generated peptides served as inhibitors of binding. These results suggest that NKISK as a component of repetitive sequences of decorin is involved in the interaction between the proteoglycan and fibronectin.

Amino Acid Sequence↗
PubMed1991

Two different Escherichia coli capsular polysaccharide depolymerases each associated with one of the coliphage phi K5 and phi K20.

The Escherichia coli capsular polysaccharides (K antigens) K5 and K20 are known as primary receptors for the coliphage phi K5 and phi K20, respectively. A host range study of the phage revealed that E. coli K5 strains were not only lysed by phi K5 but also by phi K20, and furthermore that the E. coli K95 test strain was attacked by phi K5 in addition to K5 strains. In order to find out whether the phage can degrade the K antigens, the interaction of the phage with isolated polysaccharides was studied. It could be demonstrated that phi K5 was able to depolymerize the K5 and K95 polysaccharides and that phi K20 showed degrading activity towards the antigens K20 and K5. Obviously, each of the phages was associated with two different enzyme systems which enabled them to recognize and depolymerize chemically unrelated polysaccharides.

Acetylglucosamine↗
PubMed1991

[Carcinoembryonic antigen (CEA) in ascites].

The diagnostic value of carcinoembryonic antigen (CEA) was studied prospectively in 18 patients with ascites of malignant and 28 patients with ascites of benign genesis. Both sensitivity and specificity reached 83%. With a prevalence of malignant disease of 38%, the positive and negative predictive values were 75% and 89%, respectively. In contrast to frequent false-positive CEA values in the serum of liver cirrhotics (48.3%), false-positive CEA values in the ascites of the same patients were observed in only 17.3%. It is thus recommended that if CEA determination is to be employed, it should be done in the ascites itself.

Ascites↗
PubMed1991

Nucleotide sequence of the murine prothymosin alpha cDNA and its deduced primary and secondary protein structure.

Searching for proliferation-related and cell cycle phase-specific genes we detected a full-length cDNA for the murine prothymosin alpha mRNA which was sequenced on the DNA level. The amino acid sequence deduced from the nucleotide sequence shows a high degree of positional identities with prothymosin alpha from man and rat. However, the minor differences in the primary structures largely influence predictions for the secondary structures of prothymosin alpha from different species. These differences in the secondary structure could explain the differences of activity of prothymosin alpha from different origin in immuno-protection assays.

Amino Acid Sequence↗
PubMed1991

Gastrointestinal transit of solid-liquid meal in chronic alcoholics.

Gastric emptying, mouth-to-cecum transit, and whole-gut transit of a solid-liquid meal were measured in 46 chronic alcoholics and in 30 control subjects by using scintigraphic techniques, hydrogen breath test, and stool markers. In the alcoholics various parameters such as ethanol consumption, gastrointestinal symptoms, and alcoholic neuropathy were determined and related to gastrointestinal transit times. Although there was no significant overall difference of gastric emptying, abnormally delayed gastric emptying was detected in 23.9% of the alcoholics but no control subject (P less than 0.005). Mouth-to-cecum transit was significantly prolonged in the alcoholics (P less than 0.001) with 14 alcoholics (37.8%) disclosing delayed mouth-to-cecum transit. No significant differences between both groups were detected concerning whole gut transit. In the alcoholics there was a significant correlation of dyspeptic symptoms with delayed gastric emptying (P less than 0.006), and alcoholics with diarrhea had an accelerated mouth-to-cecum transit as compared to those without diarrhea (P less than 0.05). Neither the presence of autonomic or peripheral neuropathy nor the presence of liver cirrhosis or ascites was significantly related to gastrointestinal transit times. However, the daily ethanol ingestion significantly correlated with gastric emptying (P less than 0.005). It is concluded, therefore, that in chronic alcoholics the small intestine and the stomach are most likely to be affected by gastrointestinal transit disorders and that these transit abnormalities are potentially related to toxic damage of gastrointestinal smooth muscle.

Adult↗
PubMed1991

Lateral order in binary lipid alloys and its coupling to membrane functions.

Densitometry, Raman spectroscopy and small angle neutron scattering are employed to elucidate the miscibility behavior of lipid mixtures organized as liposomal dispersions. First, temperature-composition-phase diagrams for several binary alloys of dialkyl-lecithins differing in chain lengths by an increasing number of CH2-groups are derived. A mixture of dimyristoyllecithin and distearoyllecithin (delta CH2 = 4) shows a peritectic phase behavior with a miscibility gap in the gel state. In the fluid phase, at high enough temperatures, homogeneous mixtures of the two components are formed at all molar ratios. However, upon approaching a critical point by either lowering the temperature or increasing the hydrostatic pressure, critical concentration fluctuations are observed. If one component of a binary mixture is charged, electrostatic interactions can be used to induce phase separation at constant temperature. This is demonstrated for Ca2(+)-driven demixing in alloys of lecithin and negatively charged phosphatidylglycerol. The influence of the various concepts for the induction of lateral structure formation in lipid membranes on integral functional units like ionophores is demonstrated by analysing the single channel current fluctuations of gramicidin in bimolecular lipid membranes. Ca2+, as well as polyelectrolyte-induced phase separations are shown and discussed as examples for the important (lateral) order-function relationship in biomembranes.

Electrochemistry↗