Search PubMed⌕ Search

Biomedical subjects

G Vogel

Publications and source records attributed to G Vogel.

At least 163 records · Page 9Linked to original sources
PubMed1997

Diphospho-myo-inositol phosphates from Dictyostelium identified as D-6-diphospho-myo-inositol pentakisphosphate and D-5,6-bisdiphospho-myo-inositol tetrakisphosphate.

Two diphospho-myo-inositol phosphates from Dictyostelium were recently investigated by two-dimensional 1H/31P NMR analysis and assigned to be either D-4-diphospho-myo-inositol pentakisphosphate (D-4-PP-InsP5) and D-4,5-bisdiphospho-myo-inositol tetrakisphosphate (D-4,5-bis-PP-InsP4) or their corresponding enantiomers D-6-PP-InsP5 and D-5,6-bis-PP-InsP4. In the present study the naturally occurring enantiomers were identified by using defined synthetic PP-InsP5 isomers as substrates for a partially purified PP-InsP5 5-kinase from Dictyostelium. This enzyme specifically phosphorylates the naturally occurring PP-InsP5 and the synthetic D-6-PP-InsP5, leading to D-5,6-bis-PP-InsP4. In contrast, neither D-4-PP-InsP5 nor D-1-PP-InsP5 or D-3-PP-InsP5 are converted by the enzyme.

Animals↗
PubMed1996

Abietadiene synthase from grand fir (Abies grandis). cDNA isolation, characterization, and bacterial expression of a bifunctional diterpene cyclase involved in resin acid biosynthesis.

(-)-Abietic acid, the principal diterpenoid resin acid of the wound-induced oleoresin secreted by grand fir (Abies grandis), is synthesized by the cyclization of geranylgeranyl diphosphate to (-)-abieta-7(8),13(14)-diene, followed by sequential three-step oxidation of the C-18 methyl group of the olefin to a carboxyl function. The enzyme catalyzing the cyclization reaction, abietadiene synthase, was purified from stems of wounded grand fir saplings and was digested with trypsin. Amino acid sequence information from the resulting peptides allowed construction of degenerate oligonucleotide primers, which amplified a 551-base pair fragment from a wound-induced stem cDNA library. This hybridization probe was then utilized to screen the wound-induced stem cDNA library, from which three cDNA clones were isolated that were functionally expressed in Escherichia coli, thereby confirming that a single protein catalyzes the complex, multistep cyclization of geranylgeranyl diphosphate to abietadiene. cDNA isolate Ac22.1, which yielded the highest expressed level of cyclase activity, was 2861 base pairs in length and encoded an 868-amino acid open reading frame that included a putative plastidial transit peptide. Deduced amino acid sequence comparison to other terpene cyclases revealed an amino-terminal region of the abietadiene synthase, which resembles those of enzymes that employ substrate double bond protonation to initiate the carbocationic reaction cascade, and a carboxyl-terminal region of the synthase, which resembles those of enzymes that employ ionization of the substrate allylic diphosphate ester function to initiate the cyclization reaction. This apparent fusion of segments of the two distinct terpenoid cyclase types is consistent with the novel mechanism of the bifunctional abietadiene synthase in catalyzing both protonation-initiated and ionization-initiated cyclization steps.

Abietanes↗
PubMed1996

Structures of diphospho-myo-inositol pentakisphosphate and bisdiphospho-myo-inositol tetrakisphosphate from Dictyostelium resolved by NMR analysis.

Diphospho-myo-inositol phosphates (PP-InsP5 and bis-PP-InsP4) were isolated from Dictyostelium in order to clarify the precise positional isomerism by two-dimensional 1H/31P-NMR analysis. The diphosphorylated inositol phosphates are 4-PP-Ins(1,2,3,5,6)P5 and 4,5-bis-PP-Ins(1,2,3,6)P4 or their corresponding enantiomers. The vicinal arrangement of the diphospho groups with its steric and electrostatic constraints possibly qualifies bis-PP-InsP4 as a metabolite with high phosphate-group-transfer potential in phosphotransferase reactions.

Animals↗
PubMed1996

The value of quantitative fibrin monomer determination in the early diagnosis of postoperative deep vein thrombosis.

A new test for the determination of fibrin monomer in plasma was clinically evaluated in comparison to the plasma concentration of D-D, TAT and F1,2 for the early diagnosis of prethrombotic conditions. For this purpose 129 patients who underwent abdominal surgery were followed longitudinally. 12 patients developed DVT postoperatively, proved by phlebography. The identical specificity level 73.2% was chosen for all 4 tests. At this specificity, FM had the highest sensitivity (91.7%), followed by D-D (75.0%), TAT (41.7%) and F1,2 (33.3%). All FM-positive DVT-patients had pathological FM-values at least one day prior to the clinical manifestation of thrombosis. In a group of 255 obviously healthy persons the cut-off value for the new FM test was determined at 3.6 mg/l (95th percentile). No clinically relevant influence of gender, age, smoking habits or oral anticonception could be observed. It is concluded that FM is a valuable diagnostic tool for the early diagnosis of prethrombotic conditions.

Abdomen↗
PubMed1996

Dose-dependent decrements in adult male rat sexual behavior after neonatal clorimipramine treatment.

Previous studies found that months after clorimipramine (CLI) treatment of male neonatal rats, the mature animals developed behavioral deficits and REM sleep abnormalities that modeled human endogenous depression. In the initial studies neonatal rats received CLI 30 mg/kg/IP daily from age 8 through 21 days. Diminished sexual activity of the adult rats treated neonatally in this manner was a behavioral deficit that supported the depression model. However, in subsequent studies in our laboratory, the same neonatal treatment occasionally failed to produce adult sexual deficiencies found in the initial studies. The inconsistency raised the possibility that neonatal CLI treatment was not a reliable method to produce an animal model of depression. An alternative hypothesis was that the CLI dose was too low. The present study tested this hypothesis. Placebo or one of four CLI doses was administered daily to male neonatal rats (n = 12/treatment group) from age 8 days through 21 days: 30 (the original dose), 40, 50, and 60 mg/kg/IP. Six components of adult sexual behavior were measured at age 5 months. Deficiency of each sexual behavior was found to be dose-dependent (r = 0.5, p < 0.001). The 30 mg/kg/day dose caused deficiencies in some, but not all, sexual behavior measures. Higher doses caused deficiencies in all measures of sexual behavior. The results support the hypothesis that neonatal CLI treatment at doses higher than the original 30 mg/kg/day caused reliable impairments in adult male rat sexual behavior, and therby support the reliability of neonatal CLI treatment to produce an animal model of endogenous depression.

Animals↗
PubMed1996

Effects of neonatally administered iprindole on adult behaviors of rats.

In past studies, administration of the antidepressant drugs clorimipramine, zimeldine, or desipramine to neonatal rats produced abnormalities in adult rats that modeled some behavioral and/or REM sleep features of human endogenous depression. Although these three drugs affected different neurotransmitter systems, all caused REM sleep deprivation (RSD). This suggested the hypothesis that RSD of neonatal rats caused their adult depression. One prediction of this hypothesis is that neonatally administered iprindole, an antidepressant drug that does not produce RSD, will not produce adult rats that model depression. The present study tested this hypothesis. Iprindole was administered to neonatal experimental rats and saline was administered to neonatal control rats. When the rats matured, compared with control rats, experimental rats were not significantly different in aggressive behavior (shock induced fighting), sexual behaviors, open field locomotion, and REM sleep. In our previous studies on rats, all these adult behaviors were affected in a depressive-like way by neonatally administered clorimipramine. Because iprindole does not decrease REM sleep, the present results support the hypothesis that in rats neonatal RSD causes adult depression.

Aggression↗
PubMed1996

High frequency of marked hyperphosphatemia during intravenous calcitriol therapy in hemodialysis patients with refractory hyperparathyroidism.

Efficacy and safety of intermittent intravenous calcitriol therapy were studied in 8 chronic hemodialysis patients with marked hyperparathyroidism refractory to oral therapy with calcium salts and daily vitamin D. They were followed for 20 weeks (32 weeks for 2 patients). At the start of the study, serum calcium was < 2.65 mmol/l and phosphate levels were controlled with calcium-based binders only. The phosphate content of the prescribed diet (< 1 g/day) remained unchanged during the study, and a low-calcium dialysate was used (1.38 mmol/l). The initial postdialysis calcitriol dose was 1 microgram and was increased to 2 micrograms in 6 patients. Intravenous calcitriol effectively improved hyperparathyroidism in 7 patients, with a significant decrease of the intact parathyroid hormone level from 650 +/- 433 to 195 +/- 208 pg/ml (p < 0.05). Hypercalcemia > 2.7 mmol/l occurring in 3 patients was observed in only 11% of the weekly laboratory controls and always resolved rapidly. In contrast, hyperphosphatemia > or = 2.0 mmol/l was observed in 7 patients and in 40% of the weekly laboratory controls. In 15% of the cases the phosphate values even exceeded 2.4 mmol/l. The phosphate binder therapy had to be intensified accordingly, not only by increasing the dose of calcium-based binders, but also by introducing aluminum salts in 6 patients. In summary, our data show that intravenously administered calcitriol is effective in the treatment of severe hyperparathyroidism in most hemodialysis patients resistant to oral therapy. However, its usefulness seems to be limited by frequency and severity of hyperphosphatemia, frequently necessitating additional prescription of aluminum-based binders. These undesirable secondary events may thus limit the long-term utility of intravenously administered calcitriol.

Administration, Oral↗
PubMed1995

Preparation of radioactively labeled synthetic sn-1,2-diacylglycerols for studies of lipid metabolism.

A method was developed for the synthesis of stereo-specific sn-1,2-diacylglycerols radioactively labeled on the glycerol backbone. This method includes the acylation of L-[U-14C]glycerol 3-phosphate with fatty acid anhydrides in the presence of dimethylaminopyridine and the tetraethylammonium salt of the fatty acid used for the acylation. The phosphatidic acid obtained from this synthesis was converted to sn-1,2-diacyl[U-14C]glycerol by the action of phospholipase C. When di10:0-, di-18:1-, di-18:2-, and di-22:1-diacyl[U-14C]glycerols made by this method were provided as substrates to microsome preparations from developing cotyledons of safflower (Carthamus tinctorius), they were all incorporated into phosphatidylcholine by the action of cholinephosphotransferase. The time course of the incorporation into phosphatidylcholine showed no differences for these four substrates and the initial rates were comparable.

Carbon Radioisotopes↗