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Biomedical subjects

T Peters

Publications and source records attributed to T Peters.

At least 325 records · Page 18Linked to original sources
PubMed1967

An artefact in radioautography due to binding of free amino acids to tissues by fixatives.

The binding of labeled free amino acids to liver and to purified protein by commonly used fixatives was investigated. Glutaraldehyde caused 25% of free leucine to be bound to serum albumin in solution, whereas formaldehyde bound only 0.5%. Liver slices were incubated for 2 min in the presence of labeled leucine and of puromycin, which permits absorption of leucine into the cell but inhibits incorporation into protein. Both counting and radioautographic techniques showed that glutaraldehyde bound 30 times, and osmic acid six times, as much free amino acid as did formaldehyde. By comparing liver slices incubated with and without puromycin for 2 min, it was calculated that in radioautographs prepared after fixation with glutaraldehyde, osmic acid, or formaldehyde 63, 25, and 4% respectively of the grains were due to binding of free amino acid. Formaldehyde, freshly prepared from paraformaldehyde, gives good preservation and is the recommended fixative for radioautography. When levels of free substrate in a tissue are high at the time fixative is added, the amount of binding of free substrate induced by the fixative should be included as a control in radioautographic experiments.

Aldehydes↗
PubMedDate not supplied

Determination of the extracellular space with nonradioactive Co3+EDTA and simultaneous estimation of Na, K, Ca, and Mg contents in isolated guinea-pig heart preparations by atomic absorption spectrometry.

A nonradioactive assay for the estimation of the size of the extracellular space (ECS) was developed utilizing Co3+EDTA as ECS marker. Co was measured by atomic absorption spectrophotometry. In a Langendorff preparation the compound was pharmacologically inert at a concentration of 3 X 10(-5) mol/l. The size of the ECS was independent of the ECS marker concentration indicating the lack of tissue adsorption. The filling of the ECS is almost completed after 3 min of perfusion. An insignificant slope of the late phase of the uptake curves in guinea-pig Langendorff heart preparations and isolated atria indicated no or very slow uptake into deep compartments. A sufficiently good estimate of the size of the ECS can be found after 15 min of equilibration. Simultaneous measurements of the size of the ECS and of ions (Na, K, Ca, Mg) can be performed within the same sample. Calculations of cellular Na, K, Mg, and Ca concentrations are in reasonable agreement with literature data.

Animals↗
PubMedDate not supplied

Amplification of unknown DNA sequences by sequence-independent nested polymerase chain reaction using a standardized adaptor without specific primers.

A new procedure for sequence-independent PCR amplification of DNA fragments is described. DNA from pUC18 plasmid was used as a test DNA. It was digested with a frequently cutting restriction enzyme (Sau3A), generating sticky ends. The DNA was ligated to a synthetic, non-phosphorylated adaptor and subsequently amplified in a nested PCR using two oligonucleotides with sequences derived from the adaptor. As little as 1 fg of pUC18 DNA could be detected by this procedure. The product was analyzed on a gel and hybridized with a pUC18-specific probe. The sequence-independent nested PCR was repeated with different amounts of pUC18 DNA in the presence of an excess of non-specific DNA. In these experiments, pUC18 DNA fragments were amplified in a concentration-dependent manner. After hybridization with a digoxigenin dUTP-labelled pUC18 DNA probe, 1 fg of pUC18 DNA could still be detected. This method allows rapid screening of blood for low titred and mutated viruses in which primer binding sites are not conserved.

Base Sequence↗
PubMedDate not supplied

A multicentre, randomized, double-blind, placebo-controlled trial of naltrexone in the treatment of alcohol dependence or abuse.

The opioid antagonist, naltrexone, is reported, in single centre studies, to improve the clinical outcome of individuals with alcohol dependence participating in outpatient psychosocial programmes. This is the first multicentre controlled study to evaluate the efficacy and safety of naltrexone as adjunctive treatment for alcohol dependence or abuse. Patients who met criteria for alcohol dependence (n = 169) or alcohol abuse (n = 6) were randomly assigned to receive double-blind oral naltrexone 50 mg daily (n = 90) or placebo (n = 85) for 12 weeks as an adjunct to psychosocial treatment. The primary efficacy variable was time to first episode of heavy drinking; secondary efficacy assessments included time to first drink, alcohol consumption, craving, and changes in the serum biological markers gamma-glutamyl transferase (GGT), and aspartate and alanine aminotransferases. Compliance was assessed by tablet counts and, in the naltrexone-treated group, by measurement of urinary concentrations of 6-ss-naltrexol. Forty-nine (58%) patients randomized to placebo and 53 (59%) randomized to naltrexone did not complete the study. In intention-to-treat analyses, there was no difference between groups on measures of drinking. The median reduction from baseline of serum GGT (P: < 0.05) and the reductions in alcohol craving (Obsessive and Compulsive Drinking Scale: OCDS) were greater in the naltrexone group (P: < 0.05), from approximately half-way through the study. Of 70 patients (35 placebo; 35 naltrexone) who met an a priori definition of compliance (80% tablet consumption, attendance at all follow-up appointments), those allocated to naltrexone reported consuming half the amount of alcohol (P: < 0.05), had greater median reduction in serum GGT activity (P: < 0.05), and greater reduction in alcohol craving (OCDS total score: P: < 0.05; Obsessive subscale score: P: < 0.05), compared to patients in the placebo group. Use of naltrexone raised no safety concerns. Naltrexone is effective in treating alcohol dependence/abuse in conjunction with psychosocial therapy, in patients who comply with treatment.

Adult↗
PubMedDate not supplied

MRI of amygdala and hippocampus in temporal lobe epilepsy.

In this study we compared the results of qualitative visual analysis of MRI with volumetric studies of the amygdala (AM) and hippocampal formation (HF) in a group of 31 patients. Twenty-six patients with temporal lobe epilepsy (TLE) and six with non-TLE had MRI studies using a 1.5 T Gyroscan following a specific protocol for scan acquisition. The MR images were interpreted by two blinded radiologists and by a third if discrepancy arose. Volumetric studies were carried out by one or two raters. The volumetric measurements of AM and HF were accurate in lateralizing the epileptogenic area in patients with TLE, concordant with the EEG in 92%; there was no false lateralization. In those patients who underwent surgery, there was a correlation between the degree of mesial temporal sclerosis demonstrated by histopathology, the amount of volume reduction, and the asymmetry. In patients with non-TLE, there was no volume asymmetry of AM or HF. The MR qualitative assessment yielded positive lateralization in patients with TLE in 56%, conflicting lateralization in 20%, and lateralization contralateral to the focus in 12%. A hyperintense signal in mesial structures was found ipsilateral to the focus in 40% and contralateral in 12% of patients with TLE. Volumetric study improves the diagnostic yield of MRI evaluation in patients with TLE not related to gross structural lesions. The interrater variability is low and the data are accurate and reproducible. Because they are quantitative, volumetric studies permit better comparison of results in different subgroups of patients with TLE.

Adolescent↗