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Biomedical subjects

G Gerber

Publications and source records attributed to G Gerber.

At least 37 records · Page 2Linked to original sources
PubMed1998

Review of recent placebo-controlled trials utilizing phytotherapeutic agents for treatment of BPH.

BACKGROUND: In order to assess the efficacy of phytotherapeutic agents for the treatment of benign prostatic hyperplasia (BPH), a review of recently published double-blind placebo-controlled trials was undertaken. METHODS: Only those studies reviewed by the Other Medical Therapies Committee of the Fourth International Consultation on BPH were included. RESULTS: These studies suggest a possible benefit for the use of phytotherapeutic preparations in the treatment of BPH. CONCLUSIONS: These studies need to be confirmed in larger long-term placebo-controlled studies in order to ascertain the true efficacy of these agents.

Anti-Bacterial Agents↗
PubMed1998

Control of chemical reactions by feedback-optimized phase-shaped femtosecond laser pulses

Tailored femtosecond laser pulses from a computer-controlled pulse shaper were used to optimize the branching ratios of different organometallic photodissociation reaction channels. The optimization procedure is based on the feedback from reaction product quantities in a learning evolutionary algorithm that iteratively improves the phase of the applied femtosecond laser pulse. In the case of CpFe(CO)2Cl, it is shown that two different bond-cleaving reactions can be selected, resulting in chemically different products. At least in this case, the method works automatically and finds optimal solutions without previous knowledge of the molecular system and the experimental environment.

Journal Article↗
PubMed1998

No evidence for involvement of the leptin gene in anorexia nervosa, bulimia nervosa, underweight or early onset extreme obesity: identification of two novel mutations in the coding sequence and a novel polymorphism in the leptin gene linked upstream region.

Mutations in the leptin gene can result in profound obesity in both rodents and humans. In humans, serum leptin levels correlate with body mass index (BMI: kg m(-2)). However, in patients with anorexia nervosa (AN) leptin levels are lower than in BMI-matched healthy controls. We had previously argued that genes involved in weight regulation should be considered as candidate genes for AN. To investigate this hypothesis we screened the coding region of the leptin gene and part of the leptin gene linked upstream region (LEGLUR) in 49 patients with AN and 315 children and adolescents with extreme obesity. Two novel mutations in the coding region (Ser-91-Ser; Glu-126-Gln), each found in a single proband, and a novel polymorphism in the LEGLUR (position -1387 G/A; frequency of both alleles approximately 0.50) were identified. Tests for association of LEGLUR polymorphism alleles were negative by comparing allele frequencies between 115 AN patients, 71 bulimia nervosa patients, 315 extremely obese children and adolescents, 141 healthy underweights and 50 controls that were not selected for body weight. Tests for transmission disequilibrium were also negative. Hence, an influence of variations in the leptin gene on eating disorders or extreme early onset obesity could not be detected.

Adolescent↗
PubMed1997

Further support for linkage of extreme obesity to the obese gene in a study group of obese children and adolescents.

The role of the obese gene in human obesity is presently unclear. Evidence for linkage of markers flanking the gene to obesity has been found in some but not all studies. We investigated transmission disequilibrium between two highly polymorphic microsatellite markers (D7S504 and D7S1875) flanking the human obese gene (OB) and extreme obesity in a study group of German children and adolescents. Due to the early onset and severity of obesity in the ob/ob mouse we hypothesized that especially children and adolescents with extreme obesity are enriched for possible mutations in the human OB. The analysis of 88 trios (index probands and both parents) for transmission disequilibrium of a haplotype which has previously been determined to be linked to extreme obesity (Reed et al., 1996) revealed a one-sided transmission disequilibrium test (TDT) p-value of 0.039. Post hoc analyses revealed one-sided TDT p-values of 0.015 for the 214 bp allele of D7S1875 (corrected p-value = 0.03) and 0.215 for the 145 bp allele of D7S504 (corrected p-value = 0.43). These findings substantiate the evidence for linkage of extreme obesity to OB.

Adolescent↗
PubMed1995

Morphine selectively depresses the slowest, NMDA-independent component of C-fibre-evoked synaptic activity in the rat spinal cord in vitro.

The effects of morphine on the depolarizing synaptic responses produced in motoneurons by electrical stimulation of primary sensory neurones have been recorded in hemisected spinal cord preparations (8- to 12-day-old rat pups). Morphine at concentrations of 0.1-20 microM reduced a slow, long-lasting (latency greater than 1 s, duration up to 10 s) component of the ventral root potential (VRP) evoked by C-fibre strength stimulation of the dorsal root. At 2 microM the reduction in area of this slow synaptic potential was 71.7 +/- 0.9% of control values (n = 15). The earliest components of the C-fibre strength VRP (the first 100 ms) and the responses to A beta strength stimuli were unaffected by the opioid even at 10-20 microM. The intermediate, NMDA receptor antagonist (D-AP5, 40 microM)-sensitive component (which lasts 100-1000 ms) was reduced by 34 +/- 2.2% of control (n = 15), which was significantly less than the reduction of the later NMDA-independent component (P < 0.001). Morphine (0.1-20 microM) also depressed the cumulative depolarization generated by the temporal summation of synaptic responses evoked by brief trains of C-fibre strength stimuli (1 or 10 Hz). A significantly greater reduction at the lower frequency of stimulation (56.3 +/- 2.0%) than at the higher (20.3 +/- 1.69%, n = 10, measured at 2 microM morphine) was found (P < 0.005). The effects of morphine were reversible upon wash-out or superfusion with the opioid receptor antagonist naloxone (2 microM).(ABSTRACT TRUNCATED AT 250 WORDS)

2-Amino-5-phosphonovalerate↗
PubMed1993

Risk prediction in operatively treated fractures of the hip.

There have appeared no objective means by which preoperative risk in patients with fractures of the hip can be quantitatively predicted. The developed risk's core is based on medical history, physical examination, chest radiograph, and screening laboratory data. This system reproducibly assigns patients into one of three groups. Three hundred seventeen patients with surgically treated hip fractures (93 femoral head, 166 neck, 58 intertrochanteric fractures) were analyzed in this study. Surgical treatment included 102 Ender-pinnings, 43 Böhler-nails, 79 dynamic hip screws, and 93 endoprostheses of the hip (according to fracture type). Overall mortality rate during hospitalization was 9.5%. The mortality rate in Group I was 2.5%; in Group II, 11.9%; and in Group III, 44.1%. The medical complications in Group I were 12.6%; in Group II, 28.6%; and in Group III, 67.6%. The difference for each group was significant. This preoperative risk assessment appears effective in more accurately identifying patient risk.

Aged↗
PubMed1992

Long duration ventral root potentials in the neonatal rat spinal cord in vitro; the effects of ionotropic and metabotropic excitatory amino acid receptor antagonists.

Long duration, primary afferent evoked ventral root potentials (VRP's) have been recorded in vitro from hemisected spinal cords prepared from 8-12-day-old rat pups. Single shock stimulation of a dorsal root at stimulus strengths sufficient to recruit C/group IV afferent fibres evoked a long duration (11.9 +/- 1.2 s) ipsilateral VRP in all preparations. This long duration VRP consisted of two components, (i) a slow wave, time to peak 137.0 +/- 5.1 ms, the amplitude of which was reduced to 8.7% of mean control value in the presence of the N-methyl-D-aspartate (NMDA) antagonist D-AP5 (40 microM), (ii) a prolonged wave with a time to peak of 2.0 +/- 0.2 s which was partially resistant to D-AP5 (40 microM). Both the slow and the prolonged waves were unaffected following superfusion with the metabotropic excitatory amino acid (EAA) receptor antagonist L-AP3 (100-200 microM). Low frequency (1-10 Hz) repetitive stimulation (20 s duration) of high threshold dorsal root afferents evoked a temporal summation of synaptic activity which generated a progressively depolarizing VRP. This cumulative VRP was graded with frequency of stimulation (0.89 +/- 0.13 to 1.25 +/- 0.19 mV). The cumulative VRP was followed by a post-stimulus depolarization which outlasted the period of repetitive stimulation by tens of seconds (47.6 +/- 8.4 to 91.2 +/- 19.9 s). In the presence of AP5 the amplitude of the cumulative VRP was depressed to 54.5 +/- 11.5% of control values when low frequency (1.0 Hz) stimulation was used. The proportion of the cumulative VRP resistant to D-AP5 increased as the frequency of stimulation was increased to 10 Hz. The decay time of the post-stimulus depolarization was unaffected by AP5. Neither the amplitude nor the post-stimulus depolarization of the cumulative VRP was affected by 200 microM L-AP3. It is suggested that both an AP5 sensitive and AP5 insensitive potential contribute to the long duration VRP evoked in the neonatal rat spinal cord following single shock high threshold afferent stimulation. Moreover, the AP5 insensitive prolonged depolarization is manifest following sustained low frequency stimuli and higher frequency inputs.

2-Amino-5-phosphonovalerate↗
PubMed1992

Changed purine nucleotide concentrations and enzyme activities in erythrocytes of haemodialysis patients undergoing erythropoietin therapy.

Therapy of renal anaemia in haemodialysis patients with chronic renal failure by application of recombinant human erythropoietin leads to an increase of the haematocrit. Rejuvenation of the erythrocyte population results in a decrease of the median density (D50), an increase of cell age-dependent enzyme activities, such as aspartate aminotransferase, and elevated concentrations of purine nucleotides in the erythrocytes. After density gradient separation of erythrocyte populations into cell age-dependent fractions, the concentrations of adenosine-5'-triphosphate, guanosine-5'-triphosphate and guanosine-5'-diphosphate were be found to be elevated by 25-100% in all cell fractions from haemodialysis patients, compared with a healthy control group. Therapy of haemodialysis patients with recombinant human erythropoietin leads to further increase (65%) of ATP in the younger (low density) cells, but not in the older (high density) cells. The elevated concentrations of ATP and total adenine nucleotides during recombinant human erythropoietin therapy possibly result in improved deformability of erythrocytes. The data point to an enhancement of the proportion of younger erythrocytes, but not to an improvement of the reduced life span of erythrocytes of haemodialysis patients during therapy with recombinant human erythropoietin.

Adenosine Diphosphate↗
PubMed1992

Protective influence of oxypurinol on the trinitrobenzene sulfonic acid(TNB) model of inflammatory bowel disease in rats.

Chronic inflammation of the colon and the rectum was induced by intracolonic administration of 25 mg trinitrobenzoic sulfonic acid (TNB) in 0.25 ml 30% ethanol. Three weeks after TNB administration the colon and the rectum showed transmural, granulomatous inflammation which had many similarities to Crohn's disease and furthermore to the morphological and functional changes which occur in early phases of postischemic intestinal damage. In the colon of TNB-treated animals the ATP and GTP levels were markedly decreased. The accumulation of thiobarbituric acid-reactive substances (TBA-RS) demonstrated a free radical-mediated component of the tissue damage. Treatment with oxypurinol radical scavenger and xanthine oxidoreductase inhibitor diminished the morphological changes, the loss of energy-rich nucleotides and the TBA-RS accumulation.

Animals↗
PubMed1991

Participation of excitatory amino acid receptors in the slow excitatory synaptic transmission in rat spinal dorsal horn.

In a rat spinal slice preparation the participation of excitatory amino acid (EAA) receptors in the responses of deep dorsal horn neurons to repetitive stimulation of lumbar dorsal roots was investigated using 3 EAA receptor antagonists, kynurenic acid, D-(-)-2-amino-4-phosphonovaleric acid (D-APV) and 6-cyano-2,3-dihydroxy-7-nitroquinoxaline (CNQX) and current-clamp and voltage-clamp techniques. We found that the slow excitatory synaptic response evoked by 10-20 Hz electrical stimulation of primary afferent fibers consisted of two depolarizing components: an initial component lasting 1-5 s and a late one of 1-3 min duration. The initial and late components of the slow excitatory synaptic response can also be distinguished on the basis of their voltage-dependence and sensitivity to Mg2+ ions, kynurenate, D-APV and CNQX. In the presence of Mg2+, the initial component of the slow excitatory synaptic response increased with membrane hyperpolarization, whereas the late component decreased in most of the cells examined. In a zero-Mg2+ medium, the initial component was potentiated, but the late component was reduced. In both transverse and longitudinal spinal cord slices perfused with 1.2 mM Mg(2+)-containing medium, bath application of kynurenic acid (0.1-0.5 mM), D-APV (0.05-0.1 mM) and CNQX (5-7 microM) caused a reversible reduction of the peak amplitude of the initial slow depolarizing component that was greater in transverse (kynurenic acid: by 92.6 +/- 5.0%; D-APV: by 69.1 +/- 7.8%; CNQX: by 76.6 +/- 9.8%) than in longitudinal slices (kynurenic acid: by 53.3 +/- 1.3%; D-APV: by 31.5 +/- 9.1%; CNQX: by 35.3 +/- 11.1%). In contrast, all 3 antagonists of EAA receptors produced no consistent change in the peak amplitude or half-duration of the late depolarizing component of the slow excitatory synaptic response. Our results obtained with EAA receptor antagonists, at resting membrane potentials, in the absence and presence of Mg2+ and synaptic inhibition, indicate that the synaptic activation of the NMDA- and non-NMDA-receptor systems of deep spinal dorsal horn neurons by repetitive stimulation of primary afferent fibers may be selectively involved in the mediation of the initial, but not the late depolarizing component of the slow excitatory synaptic response.

2-Amino-5-phosphonovalerate↗
PubMed1991

Determination of the ultraviolet absorbance and radioactivity of purine compounds separated by high-performance liquid chromatography. Application to metabolic flux rate analysis.

A double detection system for the determination of adenine metabolism in biological tissues using isocratic ion-pair reversed-phase chromatography is presented. Two isocratic ion-pair separations were used: (i) 10 mM NH4H2PO4, 2 mM tetrabutylammonium phosphate (PIC reagent A) and 18% acetonitrile for the determination of nucleotides and (ii) 50 mM KH2PO4, 1 mM PIC reagent A and 1% acetonitrile for the determination of monophosphorylated nucleotides, nucleosides and nucleobases. The parallel detection of ultraviolet absorbance at 254 nm and the radioactivity of separated purine compounds allows the detection of pool sizes and of the specific radioactivities in tracer kinetic experiments. The high-performance liquid chromatography methods were applied to the determination of flux rates during adenine nucleotide metabolism in suspensions of Ehrlich mouse ascites tumour cells. The pathways of adenine metabolism in cells during the proliferation and plateau phases of tumour growth were compared.

Animals↗
PubMed1991

Purine and pyrimidine compounds in murine peritoneal macrophages cultured in vitro.

Extracts of murine peritoneal macrophages were analysed by ion-pair reversed-phase high-performance liquid chromatography during incubation at 37 degrees C in vitro. Four-step gradient elution was applied to an ODS column (250 x 4.6 mm I.D.) at a flow-rate of 1.3 ml/min, allowing the separation of hypoxanthine, inosine, guanosine, adenosine, IMP, CDP, AMP, GDP, UDP, ADP, CTP, GTP, UTP and ATP within 50 min. Samples of 0.4 . 10(6)-0.5 . 10(6) cells were washed twice with RPMI 1640 medium and extracted with perchloric acid. Nucleotide concentrations of murine peritoneal macrophages did not change during incubation for 4 days in vitro.

Animals↗
PubMed1991

Changes of nucleotide patterns in liver, muscle and blood during the growth of Ehrlich ascites cells: application of the reversed-phase and ion-pair reversed-phase high-performance liquid chromatography with radial compression column.

The pool of purine compounds was analysed in liver, skeletal muscle and blood of mice during the growth of Ehrlich ascites tumour cells. Three fast isocratic high-performance liquid chromatographic methods were used. (1) Determination of nucleotides by an isocratic ion-pair reversed-phase chromatography with a 10 mM ammonium phosphate buffer containing acetonitrile and tetrabutylammonium phosphate. (2) Separation of nucleosides and nucleobases in cell extracts by a reversed-phase system with methanol and 50 mM potassium phosphate buffer as eluent. (3) Nucleosides and nucleobases in body fluids were analysed by a reversed-phase system with 10 mM potassium phosphate containing methanol. These methods allow the rapid determination of purine compounds in small biological samples from various cell types and body fluids, with high accuracy and sensitivity. The pool of cellular nucleotides increased during the exponential phase of tumour growth. Adenosine accumulated significantly in all tissues in the stationary phase of tumour growth.

Animals↗