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Biomedical subjects

P Hasler

Publications and source records attributed to P Hasler.

32 records · Page 2Linked to original sources
PubMed1993

Quality assurance and quality control methods for animal and human applications of no-carrier-added 6-[18F]fluorodopa for PET investigations of dopaminergic systems.

No-Carrier-Added (NCA) 6-[18F]fluoro-L-dopa (6-FDOPA) is being produced routinely for PET investigations of dopaminergic systems at our Institute. We describe here in detail the quality assurance methods involved in its multi-step developmental stage as a radiopharmaceutical. A method to remove toxic copper ions to prepare an injectable solution is described. The stability and shelf-life of NCA 6-FDOPA was also examined and results are discussed. Quality control involved three major aspects: (a) chemical purity, (b) radiochemical purity and (c) enantiomeric excess. A method for quick quality control of individual batch preparations is described.

Animals↗
PubMed1993

In vitro and in vivo testing of the dopamine D1 ligand [123I]SCH 23982 with respect to its potential application in SPET investigations.

[123I]SCH 23982, a dopamine D1 ligand, was labelled in a large scale process and then tested in vitro for binding to rat brain sections and membranes. Because of the promising values of KD = 1.5 x 10(-10) M and Bmax = 0.7 x 10(-11) mol/g, in vivo evaluation was performed on rats and normal volunteers to test its possible usefulness for SPET imaging. In competition experiments, a higher binding in the presence of sulpiride was found while ketanserin displaced [123I]SCH 23982 only at a 10,000-fold excess. Differences between rats and men were seen with respect to their metabolism. SPET investigations failed because the washout of [123I]SCH 23982 was too rapid.

Aged↗
PubMed1993

Insufficiency fractures of the sacrum. Twenty cases and review of the literature.

Over the past 10 years, 231 insufficiency fractures of the sacrum have been reported in the literature. These fractures, which are due to osteopenia, form a distinct subgroup of pathologic fractures. In 1.8% (n = 20) of the older-than-55-years female patients (total = 1,015) admitted to the authors' Rheumatology department between 1989 and 1991, a fracture of the sacrum was diagnosed. In all cases the diagnosis was confirmed with computed tomography. Frequency, age, sex, diagnosis, underlying diseases, and associated fractures of the 20 cases of insufficiency fractures of the sacrum are described and compared with those previously reported. Insufficiency sacral fracture as a cause of low-back pain in women older than 55 years of age is concluded to be a clinical entity.

Aged↗
PubMed1992

Human T lymphocyte cAMP-dependent protein kinase: subcellular distributions and activity ranges of type I and type II isozymes.

The role of the type I and type II protein kinase A isozymes in the regulation of human T lymphocyte immune effector functions has not been ascertained. To approach this question, we first characterized the distribution and enzyme activities of the type I and type II protein kinase A (PKA) isozymes in normal, human T lymphocytes. T cells possess both type I and type II isozymes with an activity ratio of 5.0:1 +/- 0.71 (mean +/- SD). The type I isozyme associates predominately with the plasma membrane whereas the type II isozyme localizes primarily to the cytosol. Analyses of isozyme activities demonstrated that T cells from approximately one-third of 16 healthy donors exhibited significantly higher type II isozyme activities (higher type II, type IIH) than the remaining donors (lower type II, type IIL) (mean = 605 +/- 75 pmol.min-1.mg protein-1, P less than 0.001). Scatchard analyses of [3H]cAMP binding in the cytosolic fraction demonstrated similar Kd values (type IIH, 1.1 x 10(-7) M; type IIL, 9.0 x 10(-8) M); however, the Bmax (maximal binding) of the type IIH was 400 fmol/mg protein compared to the Bmax of the type IIL of 126 fmol/mg protein. Scatchard analysis of [3H]cAMP binding to the type I isozyme associated with membrane fragments had a Kd of 5.6 x 10(-8) M and a Bmax of 283 fmol/mg protein. Eadie-Hofstee plots of type IIH and type IIL gave a Km and Vmax of 2.3 mg/ml and 1.5 nmol.mg-1.min-1, and 2.1 mg/ml and 1.6 nmol.mg-1.min-1, respectively. The 3.2-fold higher maximal binding of the type II isozyme in one-third of healthy donors may reflect a greater amount of isozyme protein. The compartmentalization of type I PKA isozyme to the plasma membrane and type II PKA isozyme to the cytosol may serve to localize the isozymes to their respective substrates in T lymphocytes.

Adult↗
PubMed1991

Ribosomal proteins P0, P1, and P2 are phosphorylated by casein kinase II at their conserved carboxyl termini.

A potential casein kinase II (CK II) recognition site is located within the conserved carboxyl (COOH) terminus of the ribosomal P (phospho) proteins P0, P1, and P2. To determine whether the COOH termini of the P proteins are physiological substrates for CK II, we studied the phosphorylation of the P proteins in vitro and in intact cells. The results show that the addition of exogenous purified CK II and ATP to intact ribosomes in vitro resulted in the relatively selective phosphorylation of all three P proteins. A synthetic peptide corresponding to the COOH-terminal 22 amino acids of P2 (C-22) was also phosphorylated by CK II with a Km of 13.4 microM. An endogenous ribosome-associated, CK II-like enzyme also phosphorylated the P proteins relatively selectively in the presence of 10 mM Mg2+ and ATP. The endogenous kinase was inhibited by heparin, utilized either ATP or GTP as a phosphate donor, and phosphorylated casein. A CK II-specific peptide (Arg-Arg-Arg-Glu-Glu-Glu-Thr-Glu-Glu-Glu) and the C-22 peptide inhibited the phosphorylation of the P proteins by the endogenous kinase, providing further evidence for its CK II-like properties and for localization of the CK II phosphorylation site to the COOH termini of the P proteins. Tryptic phosphopeptide maps of P1 and P2 phosphorylated by exogenous CK II and the endogenous ribosome-bound kinase were virtually identical. These phosphopeptides comigrated with the tryptic digest of C-22 and with the tryptic phosphopeptides derived from P1 and P2 isolated from intact cells metabolically labeled with [32P]orthophosphate in vivo. These studies demonstrate that exogenous CK II and a ribosome-bound, CK II-like enzyme phosphorylate the ribosomal P proteins in vitro and localize the target site for phosphorylation to the COOH terminus. The incorporation of phosphate into the same target site in intact cells indicates that the P proteins are in vivo substrates of CK II.

Amino Acid Sequence↗
PubMed1991

[Is iodination of cooking salt still necessary? Current studies on iodine supply in Switzerland].

Salt with 3.75 mg iodide per kg was introduced in Switzerland stepwise in the individual cantons between 1922 and 1952. The iodide content was raised to 7.5 mg in 1962 and to 15 mg per kg in 1980. 92% of retail salt and 78% of all salt for human consumption (including salt used in industrial food processing) was iodized in 1989. Under this measure, prevalence of grade 1b or larger goiter dropped continuously to a present value of 1.3% in school-children and 0.3% in male army recruits. Endemic cretinism has disappeared completely. Urinary iodine has reached the desired range of 150 +/- 77 (SD) micrograms per g creatinine. The following facts prove that iodization of salt (and not other changes of food habits) have corrected the iodine deficiency in Switzerland: 1. Urinary iodine is highly correlated with urinary sodium. Backward extrapolation yields a theoretical urinary iodine of 30 micrograms per g creatinine in the absence of iodized salt, a value typical of severe deficiency. 2. Goiter prevalence declined later in those cantons which introduced iodized salt last. 3. Surrounding countries without iodized salt (France, Italy, Federal Republic of Germany, Spain) suffer from considerable iodine deficiency with areas of high goiter prevalence and even endemic cretinism. The new data underscore the absolute and continued need for iodized salt in Switzerland.

Adolescent↗
PubMed1990

Defective cAMP-dependent phosphorylation of intact T lymphocytes in active systemic lupus erythematosus.

The present study was undertaken to establish whether cAMP-dependent phosphorylation of endogenous substrates is impaired in T lymphocytes from subjects with active systemic lupus erythematosus (SLE). In normal human T lymphocytes, the cell-permeable cAMP analog, N6,O2'-dibutyryladenosine 3',5'-cyclic monophosphate, induced phosphorylation of substrates with molecular masses of 17.5, 23/25, 33.5 kDa on one-dimensional SDS/PAGE. Maximal phosphorylation occurred at 60 min. In contrast to healthy T cells, the extent of substrate phosphorylation achieved in active SLE T cells (n = 8) was only 15% at 60 min in the 17.5-kDa substrate, 21% in the 23/25-kDa substrate, and 9% in the 33.5-kDa substrate. The rheumatic disease controls (rheumatoid arthritis; primary Sjögren syndrome; n = 8) exhibited a mean 72%, 124%, and 85%, respectively, of phosphorylation observed in healthy T cells. Because the only known mechanism by which cAMP acts is via cAMP-dependent protein kinase (protein kinase A), these data raise the possibility of a defect at the level of this kinase in SLE T lymphocytes.

Adult↗
PubMed1978

The susceptibility of Vero cell cultures for human adenoviruses.

Human adenoviruses 1 to 28 were shown to produce a cytopathic effect in Vero cell cultures. Viruses of subgroups III and IV (Ad 1, 2, 5, 6, 12, and 18) were readily passaged in Vero cell cultures and were produced in high amounts. This was also found for Ad 11, 16, and 21, while Ad 3, 4, and 7 showed a lower degree of multiplication and Ad 14 could not be passed serially. For Ad 8, 26, 27, 20, 25, and 28, a multiplication in Vero cells could not be proved, while the remaining serotypes of subgroup II showed a moderate degree of multiplication. The sensitivity of Vero cells to small amounts of virus was lower than that of HeLa cells. No adaption of adenoviruses to Vero cells after 5 Vero passages was observed. Attempts to enhance virus multiplication by coinfection with SV40 failed.

Adenoviridae↗
PubMedDate not supplied

The effect of nonsteroidal anti-inflammatory drugs on cAMP-dependent protein kinase-mediated phosphorylation by human chondrocytes in culture.

Although a principal pharmacological action of nonsteroidal anti-inflammatory drugs (NSAIDs) is to blunt eicosanoid synthesis by inhibiting cyclooxygenase, recent evidence indicates that NSAIDs may also interact directly with proteins that control the activity of adenylyl cyclase. Since the only physiological mechanism governing the action of cyclic AMP occurs via activation of its receptor, cyclic AMP-dependent protein kinase (cAMPPk; Kinase A), we determined whether NSAIDs affect intracellular substrate phosphorylation dependent on cAMPPk. The incorporation of 32Pi into cellular proteins that are substrates for cAMPPk was determined in intact human non-arthritic, aged non-arthritic and osteoarthritic chondrocytes in the presence or absence of NSAIDs, namely, sodium meclofenamate, indomethacin, tiaprofenic acid and sodium salicyclate. The transfer of [32P]-ATP was employed to identify phosphoproteins in a membrane fraction prepared from chondrocyte homogenates in the presence or absence of these NSAIDs. The lowest concentration of NSAID was similar to NSAID concentrations achieved during therapy for the arthritides. In intact human chondrocyte strains, activation of cAMPPk by dibutyryl cAMP (dBcAMP) resulted in the phosphorylation of intracellular substrates with an apparent M(r) of 55kD, 42kD, 26kD, 25kD, 22kD, 21.5kD, 20.5kD, and 17kD when examined by autoradiography after 12.5% SDS/PAGE. The NSAIDs augmented or potentiated phosphorylation of these proteins which were cAMPPk-dependent. In the chondrocyte membrane fraction, protein phosphorylation by cAMP was mimicked by isobutylmethylxanthine or by the purified catalytic subunit of bovine cAMPPk. NSAIDs augmented chondrocyte phosphorylation in the chondrocyte membrane fraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗