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Biomedical subjects

K Friedrich

Publications and source records attributed to K Friedrich.

At least 73 records · Page 4Linked to original sources
PubMed1991

[Assessment of diagnostic lung function and diagnostic laboratory parameters in workers exposed to diesel exhaust below ground in comparison with non-exposed workers].

Toxic gases caused by the use of large Diesel-driven devices in underground mines may lead to impairment of health, especially in the respiratory system. By means of occupational hygiene supervision it may be checked if the effectiveness of accomplished occupational hygiene measures are sufficient. By an enlarged examination programme of the respiratory function and laboratory diagnostic investigation miners exposed to Diesel-exhaust-gas were compared within the above mentioned supervision with a non-exposed population. In this study was not found any difference between the respiratory results attributed to influence of Diesel-exhaust-gas. Among the laboratory parameters the exposition to Diesel-exhaust-gas will only affect the mercapturic acid, however, which also may be influenced by other factors. Under the conditions of the measured low degree of exposition was not found any correlation between the level of mercapturic acids and the duration of exposure as well as to the actual degree of exhaust-gas exposition.

Adult↗
PubMed1990

Romanowsky dyes and Romanowsky-Giemsa effect. 5. Structural investigations of the purple DNA-AB-EY dye complexes of Romanowsky-Giemsa staining.

A reproducible Romanowsky-Giemsa staining (RGS) can be carried out with standardized staining solutions containing the two dyes azure B (AB) and eosin Y (EY). After staining, cell nuclei have a purple coloration generated by DNA-AB-EY complexes. The microspectra of cell nuclei have a sharp and intense absorption band at 18,100 cm-1 (552 nm), the so called Romanowsky band (RB), which is due to the EY chromophore of the dye complexes. Other absorption bands can be assigned to the DNA-bound AB cations. Artificial DNA-AB-EY complexes can be prepared outside the cell by subsequent staining of DNA with AB and EY. In the first step of our staining experiments we prepared thin films of blue DNA-AB complexes on microslides with 1:1 composition: each anionic phosphodiester residue of the nucleic acid was occupied by one AB cation. Microspectrophotometric investigations of the dye preparations demonstrated that, besides monomers and dimers, mainly higher AB aggregates are bound to DNA by electrostatic and hydrophobic interactions. These DNA-AB complexes are insoluble in water. Therefore it was possible to stain the DNA-AB films with aqueous EY solutions and also to prepare insoluble DNA-AB-EY films in the second step of the staining experiments. After the reaction with EY, thin sites within the dye preparations were purple. The microspectra of the purple spots show a strong Romanowsky band at 18,100 cm-1. Using a special technique it was possible to estimate the composition of the purple dye complexes. The ratio of the two dyes was approximately EY:AB approximately 1:3. The EY anions are mainly bound by hydrophobic interaction to the AB framework of the electrical neutral DNA-AB complexes. The EY absorption is red shifted by the interaction of EY with the AB framework of DNA-AB-EY. We suppose that this red shift is caused by a dielectric polarization of the bound EY dianions. The DNA chains in the DNA-AB complexes can mechanically be aligned in a preferred direction k. Highly oriented dye complexes prepared on microslides were birefringent and dichroic. The orientation is maintained during subsequent staining with aqueous EY solutions. In this way we also prepared highly orientated purple DNA-AB-EY complexes on microslides. The light absorption of both types of dye complexes was studied by means of a microspectrophotometer equipped with a polarizer and an analyser. The sites of best orientation within the dye preparations were selected under crossed nicols according to the quality of birefringence.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

[Occupational medicine analysis and evaluation of spinal load in the mining process].

The calculations of the spinal column loading of miners are based on working time studies in operations with predominantly physical heavy work and elevated mechanical load. An elaborated model for the mining of ores, the applicability to underground workers and the comparability of loading quantities, based on the dosage measurement, are described.

Biomechanical Phenomena↗
PubMed1990

[Significance of the iron and copper content of the liver for the differential diagnosis of chronic liver diseases].

Liver iron and copper concentrations were estimated in 395 patients undergoing hepatological examination. Relations to clinical, morphological and laboratory data were evaluated. Liver iron concentrations were not significantly different in chronic hepatitis of viral, toxic or immunological origin. Liver iron levels exceeding 100 mg/100 g dry liver tissue (normal range up to 300 mg/100 g) were only found in idiopathic hemochromatosis (n = 8), in a patient with prophyria cutanea tarda and in a multiple transfused patient who suffered from aplastic anemia. Liver copper content was significantly increased in primary biliary cirrhosis compared to chronic hepatitis of other origin. Apart from untreated Wilson's disease (n = 3) copper levels higher than 25 mg/100 g dry liver tissue (normal range up to 6 mg/100 g) were measured in chronic active hepatitis B (n = 2), primary biliary cirrhosis (n = 9) and in chronic hepatitis of uncertain origin (n = 3). Therefore excess accumulation of copper in the liver was typical of Wilson's disease but less diagnostic than severely elevated liver iron stores of idiopathic hemochromatosis.

Adolescent↗
PubMed1989

[Model investigations on the structure of the purple dye complex of Giemsa staining].

Nuclei of Giemsa stained cells show a purple coloration, which is generated by a complex of DNA, azure B (AB) and eosin Y (EY). The structure of this complex is unknown. Its absorption spectrum shows a sharp and strong band at 18,100 cm-1 (552 nm), the so called Romanowsky band (RB). It is possible to produce the complex outside of the cell, but it is cubersome to handle. Easier to handle is a purple complex composed of chondroitin sulfate (CHS), AB and EY, which also shows a sharp and strong RB at 18,100 cm-1 in the absorption spectrum. This CHS-AB-EY complex is a model for the DNA-AB-EY complex of Giemsa stained cell nuclei. We tried to investigate its structure. In the first step of the staining procedure CHS binds AB cations forming a stable CHS-AB complex. In the case of saturation each anionic SO4- and COO- -binding site of CHS is occupied by one dye cation and the complex has 1:1 composition. It has a strong and broad absorption band with its maximum at ca. 18,000 cm-1 (556 nm). In the second step the CHS-AB complex additionally binds EY dianions forming the purple CHS-AB-EY complex with its RB at 18,100 cm-1. This band can be clearly distinguished from the broad absorption of the bound AB cations. RB is generated by the EY chromophore, whose absorption is shifted to longer wavelength by the interaction with the CHS-AB framework.

Azure Stains↗
PubMed1988

2',3'-Dideoxy-N6-cyclohexyladenosine: an adenosine derivative with antagonist properties at adenosine receptors.

The 2',3'-dideoxy analogue of the potent A1 receptor agonist, N6-cyclohexyladenosine (CHA), was synthesized as a potential antagonist for the A1 adenosine receptor. In studies on adenylate cyclase 2',3'-dideoxy-N6-cyclohexyladenosine (ddCHA) did not show agonist properties at A1 or at A2 receptors. However, it antagonized the inhibition by R-PIA of adenylate cyclase activity of fat cell membranes via A1 receptors with a Ki value of 13 microM. ddCHA competed for the binding of the selective A1 receptor antagonist, [3H]8-cyclopentyl-1,3-dipropylxanthine ([3H]DPCPX), to rat brain membranes with a Ki value of 4.8 microM; GTP did not affect the competition curve. In contrast to the marked stereoselectivity of the A1 receptor for the alpha- and the natural beta-anomer of adenosine, the alpha-anomer of ddCHA showed a comparable affinity for the A1 receptor (K1 value 13.9 microM). These data indicate that the 2'- and 3'-hydroxy groups of adenosine and its derivatives are required for agonist activity at and high affinity binding to A1 adenosine receptors and for the distinction between the alpha- and beta-forms.

Adenylyl Cyclases↗
PubMed1988

[Changes in 99mTc uptake by the thyroid gland and serum triiodothyronine and thyrotropin concentrations following completion of alimentary iodine administration].

In the current number of patients examined of a nuclear-medical institution the TdTU-, TT3- and TSH-values of various groups of diagnosis were compared in a defined period before and after prophylaxis of struma with iodide (IP). After prophylaxis with iodide the results show a better diagnostic evaluability of the TcTU and a regression of the TSH mean value of the euthyroid group of patients. Possible consequences for the diagnostic practice are shown.

Humans↗
PubMed1988

Electrostatic potential of macromolecules measured by pKa shift of a fluorophore. 1. The 3' terminus of 16S RNA.

We have investigated the use of the pH-sensitive fluorescein label as a probe for electrostatic potential in macromolecules. The practicality of this technique is demonstrated by its application to the 16S RNA molecule. The dependence of the electrostatic potential upon ionic conditions and upon the presence of ribosomal proteins and the state of the RNA was studied. The combination of electrostatic and anisotropy data emphasizes the rôle of the 30S ribosomal proteins, rather than of the renaturation of the 16S RNA or the presence of the 50S subunit, in shaping the environment of the 3' terminus of the 16S RNA in the active ribosome.

Electrochemistry↗
PubMed1988

Electrostatic potential of macromolecules measured by pKa shift of a fluorophore. 2. Transfer RNA.

The procedures developed earlier (Friedrich and Woolley, preceding paper in this journal) for probing electrostatic potential with the fluorescein label were applied to transfer RNA. By using tRNA species that contain chemically reactive bases we were able to label these bases with fluorescein derivatives and thus to 'map' the electrostatic potential around the molecule. Both the electrostatic potential and the fluorescence emission anisotropy data that were obtained at the same time could be understood in terms of the well-known, paradigmatic crystal structure of tRNA(Phe). However, within the distribution of the various tRNA species, tRNA(Met)f appeared to occupy an extreme position, which suggests a relation between the conformation in solution and the initiation function of this molecule. Comparison with theoretical predictions by others of the electrostatic potential map of tRNA showed agreement in respect of trends, but the values of the potentials measured were orders of magnitude lower than predicted. This we attribute primarily to solvation.

Electrochemistry↗
PubMed1988

Proteins from the prokaryotic nucleoid. Interaction of nucleic acids with the 15 kDa Escherichia coli histone-like protein H-NS.

The interaction between nucleic acids and Escherichia coli H-NS, an abundant 15 kDa histone-like protein, has been studied by affinity chromatography, nitrocellulose filtration and fluorescence spectroscopy. Intrinsic fluorescence studies showed that the single Trp residue of H-NS (position 108) has a restricted mobility and is located within an hydrophobic region inaccessible to both anionic and cationic quenchers. Binding of H-NS to nucleic acids, however, results in a change of the microenvironment of the Trp residue and fluorescence quenching; from the titration curves obtained with addition of increasing amounts of poly(dA)-poly(dT) and poly(dC)-poly(dG) it can be estimated that an H-NS dimer in 1.5 x SSC binds DNA with an apparent Ka approximately equal to 1.1 x 10(4) M-1.bp-1. H-NS binds to double-stranded DNA with a higher affinity than the more abundant histone-like protein NS(HU) and, unlike NS, prefers double-stranded to single-stranded DNA and DNA to RNA; both monovalent and divalent cations are required for optimal binding.

Bacterial Proteins↗
PubMed1988

Fluorimetric distance determination by resonance energy transfer. Ribosome-bound transfer RNA.

Using the technique of singlet-singlet (Förster-type) resonance energy transfer, we have determined five distances in the programmed ribosome, either with the P site or with both the A and the P sites occupied. Two of the distances are new and two agree with earlier measurements; the fifth showed disagreement in detail with earlier results of others, but a consistent general trend. The distances substantiate a current model for the location of ribosomally bound tRNA, except in regard of the position of the 3' end of P-site tRNA, which seems according to our results to lie too far away from the 3' terminus of the 16 S RNA to be accommodated in the model. We present new evidence for the hypothesis that anomalously charged tRNA does not bind to the cognately programmed A site in the same way as does tRNA charged with an amino acid. Occupation of the A site restricts mobility of the 3' end of tRNA in the P site.

Energy Transfer↗
PubMed1988

Identification, cloning and sequence of the Streptococcus faecium infB (translational initiation factor IF2) gene.

The structural gene for translational initiation factor IF2 (infB) from Streptococcus faecium was identified by cross-hybridization with DNA probes derived from the corresponding gene of Bacillus stearothermophilus. The entire infB gene (ca. 2.8 kb) was cloned and sequenced. The amino acid sequence deduced from the nucleotide sequence shows that S. faecium initiation factor IF2 (785 amino acids, Mr 86,415) displays extensive homology (ca. 69% and 53%) with the region comprising three-quarters of the molecule from the carboxy-terminus of B. stearothermophilus and Escherichia coli IF2, respectively. The region comprising one-quarter of the molecule from the amino-terminus, on the other hand, does not display any significant homology.

Amino Acid Sequence↗
PubMed1988

The importance of variant insertions of the ligamentum teres hepatis in the Cruveilhier-Baumgarten syndrome.

Within the framework of a prospective study, we were able to establish that in 50 per cent of 220 patients submitted to laparoscopy, the ligamentum teres hepatis did not run from the porta hepatis directly to the umbilicus, but to a point of insertion craniad to the umbilicus in the median line of the anterior abdominal wall. As a rule, this topographic variant has no clinical relevance. It is, however, of importance in patients with cirrhosis of the liver and portocaval collateral channels. In our group, 25 per cent of the patients revealed complete cirrhotic transformation of the liver; in a quarter of these, the Cruveilhier-Baumgarten syndrome presented, and thus also the possibility that large-caliber porto-femoral "umbilical" vessels might be running a course to the left of the umbilicus. The danger of injuring such a vessel during laparoscopy can, however, be prevented: in seven out of eight patients with portofemoral collaterals, this situation was established by ultrasonic examination, and in three cases, the periumbilical course of these vessels was accurately determined prior to carrying out the procedure. In our opinion, the definition of the Cruveilhier-Baumgarten syndrome needs to be extended. The results of our investigation show that, within the framework of portal neo-vascularisation, direct umbilical vein recanalisation is a relatively rare occurrence (approximately 15 per cent), while porto-femoral collateral formation is considerably more common (about 70 per cent).

Abdominal Muscles↗
PubMed1988

Cloning and expression of the CAMP factor of group B streptococci in Escherichia coli.

The genetic determinant of the CAMP factor from a strain of group B streptococcus (GBS; Streptococcus agalactiae) was cloned in Escherichia coli. Total cell DNA from the GBS strain R268 was used to construct a gene bank with bacteriophage lambda EMBL4 in the E. coli K-12 strain LE392. Recombinant phage plaques were detected by immunoblots by using a specific antiserum raised against purified CAMP factor. Two hybrid phages showing expression of CAMP factor were identified. Subcloning the CAMP gene (cfb) into the high-copy-number vector pUC8 resulted in highly unstable plasmids. Therefore, subcloning was performed with the low-copy-number vector pLG339 resulting in the stable recombinant plasmids pCO61 and pCO62 which lead to expression of CAMP protein first identified by colony immunoblotting. Western blot (immunoblot) analysis revealed a similar CAMP protein pattern in lambda EMBL4 recombinant phage lysates (molecular weight, 22,000 to 24,000) as compared to that obtained from a GBS culture supernatant (molecular weight, 22,000 to 26,000) but a different CAMP protein pattern (molecular weight, 20,000 to 23,000) from lysates of E. coli carrying pCO61 or pCO62. To study the excretion of the CAMP protein we performed a semi-quantitative dot blot analysis of proteins recovered from cell fractions and supernatants of the E. coli recombinant clones. In contrast to GBS R268, where the CAMP factor is readily excreted, the CAMP protein is not excreted in E. coli clones containing pCO61 and pCO62 but is found associated with the cell fractions.

Antigens, Bacterial↗
PubMed1988

[Kwashiorkor syndrome in exudative enteropathy].

We report on a case of a 45 years old man suffering from ulcerative colitis accompanied by a protein-loosing-syndrome (hypoalbuminaemia). The significant decrease of cholinesterase (CHE) and quick level, edemas of the legs and forearms, pleural effusion and ascites had been misinterpreted as signs of liver insufficiency. Low protein diet was given and, thus, the full picture of kwashiorkor developed soon as a logical consequence. Liver-induced fluid dysbalance was assumed and the low-protein diet continued. We describe the difficulties of treatment and the favourable outcome of the disease.

Biopsy↗