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M Ovecka

Publications and source records attributed to M Ovecka.

At least 19 recordsLinked to original sources
PubMed2002

Mapping the C terminal epitope of the Alzheimer's disease specific antibody MN423.

The mapping of monoclonal antibody epitopes is now predominantly carried out using molecular diversity techniques, phage display in particular. However, until very recently, phage display methods have been inappropriate for the analysis of epitopes that require a free carboxy terminus. Here we describe the use of two different techniques to analyze the known C terminal epitope specificity of MN423, a monoclonal antibody specifically staining truncated tau in Alzheimer's brain. Using a lambda phage based C-terminal random peptide library, and an intracellular expression library based on truncated tau, we show that this antibody has an absolute requirement for a glycine at position -3 with respect to the C terminus. Both methods give similar results, and identify other important residues in the binding site. However, affinity analysis of synthetic peptides revealed that the affinity of the antibody for identified tripeptides was far lower than the pentapeptide sequence in the native target, and that this in turn was considerably below the affinity for the native target itself. This suggests that molecular diversity methods may define minimum, but not necessarily complete epitopes. The methods described here have a general application to the analysis of antibody epitopes suspected to be found at the C terminus.

Aged↗
PubMed1994

Idiotypic vaccination against human B-cell lymphoma. Rescue of variable region gene sequences from biopsy material for assembly as single-chain Fv personal vaccines.

Idiotypic determinants on neoplastic B cells could provide tumor antigens for vaccination of patients with B-cell tumors. Because this approach requires an individual vaccine for each patient, simple methods for obtaining idiotypic antigen are desirable. Using polymerase chain reaction (PCR) with family-based V-gene and J-region primers, the variable region genes of heavy and light chains (VH and VL) of Ig have been obtained from biopsy material from 13 patients with B-cell tumors. In each case, analysis of random clones derived from the PCR product showed repeated, clonally-related sequences, whereas normal lymphoid tissue generated no repeated sequences. In 3/3 cases, the repeated sequences were found to be the same as those in a tumor-derived hybridoma. Mutational patterns in the V-genes differed among the tumors, with follicular lymphoma tending to be more highly mutated. The individual VH and VL sequences have been assembled with a flexible linker sequence to encode single-chain Fv (scFv). The scFv sequences can be cloned into bacterial expression vectors to produce protein, or into vectors suitable for direct vaccination using naked DNA. In a model system, expressed scFv protein retained all idiotypic determinants defined by a panel of five anti-idiotypic monoclonal antibodies (MoAbs). Similarly, expressed scFv proteins from two patients were shown to react with anti-idiotypic antibodies. This approach allows production of potential vaccines from surgical biopsies within 2 to 3 weeks.

Amino Acid Sequence↗
PubMed1990

[Obesity and hyperlipoproteinemia. I. Changes in lipid levels in obese persons].

The authors investigated changes in serum lipid levels in 115 obese men and 172 obese women. The body mass index (BMI) of the subjects was 29-50 kg/m2. The group was subdivided by sex and age as follows: 15-18 years, 19-25 years, 26-35 years, 36-55 years. It was revealed that with advancing age and increasing body weight the mean tiacylglycerol levels in men increased from 1.74 mmol/l to 4.40 mmol/l, in women from 1.37 mmol/l to 1.84 mmol/l. The mean levels of total serum cholesterol increased in men from 4.58 mmol/l to 6.82 mmol/l, in women from 5.09 mmol/l to 5.96 mmol/l. In the rise of serum cholesterol in men the LDL and VLDL fractions participated, in women mainly the LDL fraction. Conversely the HDL fraction declined in men from 1.60 mmol/l to 1.20 mmol/l, in women from 1.71 mmol/l to 1.26 mmol/l. The mean value of the atherogenic index in men increased from 2.88 to 5.68, in women from 2.99 to 4.73. The results indicate the adverse changes of serum lipid levels in obese subjects which appear in men already after the age of 25 years, in women 10-20 years later. The authors discuss the causes of hyperlipoproteinaemia and the risk of atherosclerosis in obesity.

Adolescent↗
PubMed1990

[Obesity and hyperlipoproteinemia. II. The effect of a low energy diet on lipid levels in the blood of obese persons].

In 287 obese men and women with BMI values of 29-50 kg/m2, divided by sex and age, the effect of a low-energy diet on triacylglycerol (TG), total cholesterol (TC) and HDL-cholesterol (HDL-C) serum levels was investigated. On a diet of 2500 kJ/day (4 weeks) and 4000-7000 kJ/day (6 weeks) the body weight declined by 10-11% from the initial value. There was a significant drop of TG in obese men above 25 years and in obese women above 35 years of age. The mean TC values did not change significantly after weight reduction. The mean HDL-C levels increased significantly after weight reduction, as compared with initial values in both sexes in the groups aged 26-35 years. In this group there was also an increase of the relative ratio of HDL-C in TC and the value of the atherogenic index declined. The authors draw attention to the fact that with regard to preserving normal blood lipid levels, in particular in obese men, it is necessary to reduce or normalize body weight in the course of the third decade.

Adolescent↗
PubMed1982

Adaptability of pancreatic enzymes activity to various food nutritive values in man. Influence of high protein diet.

The effect of varying dietary protein content on the activity of human pancreatic proteinases was studied in healthy volunteers. Following the consumption of food with a higher protein content, proteinases activities in duodenal aspirate after pancreozymin and secretin stimulation showed an increasing trend only for a period of 14 days and then returned to their original values. Chymotrypsin is more sensitive and its activity increased significantly. Trypsin activity increased without statistical significance. No evidence of changing other parameter (volume, bicarbonate concentration, amylase and lipase activities) was observed.

Adult↗