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Biomedical subjects

J Konecny

Publications and source records attributed to J Konecny.

10 recordsLinked to original sources
PubMed2002

Radical D2 surgery for patients with gastric cancer.

UNLABELLED: The authors analyzed and prepared a report concerning 18 radical surgeries for gastric cancer that were performed between 1999-2001. Overall, 55 operation were performed, 32 radical, 18 palliative and 5 explorative laparatomies. D2 resections were performed 18 times, while D1 type 14 times. The group undergoing D2 surgery comprised of 10 men and 8 women with average age of 64.3. D2 resection included partial (8 times), or total (10) gastrectomy and lymfadenectomy of perigastric nodes, supra and infrapyloric nodes and nodes along common hepatic artery, truncus coeliacus, lienal artery, left paracardial nodes and removing capsula of pancreas. Splenectomy was performed twice. On average, 37.5 lymphnodes were removed for every operation (25-69). Operative mortality was none (0%) and morbidity was 22%. As of January 1, 2002 relaps was noted in six patients, and 5 patients died. CONCLUSION: D2 resection surgeries performed by an experienced surgeon show low morbidity as well as better outcome and higher perspective for long-term survival in patients with gastric cancer. (Tab. 1, Ref. 19.).

Carcinoma↗
PubMed2000

Concurrent neutral evolution of mRNA secondary structures and encoded proteins.

Messenger RNA sequences often have to preserve functional secondary structure elements in addition to coding for proteins. We present a statistical analysis of retroviral mRNA which supports the hypothesis that the natural genetic code is adapted to such complementary coding. These sequences are still able to explore efficiently the space of possible proteins by point mutations. This is borne out by the observation that, in stem regions of retroviral mRNA foldings, silent mutations on one strand are preferentially accompanied by conservative mutations on the other. Distances between amino acids based on physicochemical properties are used to quantify the conservation of protein function under the constraint of maintained RNA secondary structure. We find that preservation of RNA secondary structure by compensatory mutations is evolutionary compatible with the efficient search for new variants on the protein level.

Base Sequence↗
PubMed1995

Complementary coding conforms to the primeval comma-less code.

The hypothesis that the universal genetic code is adapted to double-strand coding is supported by its remarkable compatibility with the RNY comma-less hypothesis. Coding by a triplet code on a polynucleotide double-strand allows for enciphering of five additional messages with reference to a chosen primary reading frame. Assuming the acceptance of coupled mutations on both strands, the best codon register for two overlapping messages can be inferred. The idea of evolutionarily compatible coding of two proteins by one nucleotide double-strand is extended to complementary coding for one protein in folded, single-stranded RNA.

Animals↗
PubMed1993

Neutral adaptation of the genetic code to double-strand coding.

We lay new foundations to the hypothesis that the genetic code is adapted to evolutionary retention of information in the antisense strands of natural DNA/RNA sequences. In particular, we show that the genetic code exhibits, beyond the neutral replacement patterns of amino acid substitutions, optimal properties by favoring simultaneous evolution of proteins encoded in DNA/RNA sense-antisense strands. This is borne out in the sense-antisense transformations of the codons of every amino acid which target amino acids physicochemically similar to each other. Moreover, silent mutations in the sense strand generate conservative ones in its antisense counterpart and vice versa. Coevolution of proteins coded by complementary strands is shown to be a definite possibility, a result which does not depend on any physical interaction between the coevolving proteins. Likewise, the degree to which the present genetic code is dedicated to evolutionary sense-antisense tolerance is demonstrated by comparison with many randomized codes. Double-strand coding is quantified from an information-theoretical point of view.

Adaptation, Biological↗
PubMed1978

Alkalimetric microassay of cephalosporins.

Alkalimetric pH-stat titrations of cephalosporin C, cephacetril and their deacetyl derivatives using an acetyl esterase and beta-lactamase are described. The esterase was used to assay highly purified samples of cephalosporin C and cephacetril, and also to prepare analytically defined solutions of the deacetyl cephalosporins. Lactamase-catalyzed hydrolysis of the parent compounds was then found to generate exactly 2 equivalents of acid per mole; that of the deacetyl derivatives exactly 1 equivalent.

Acetylesterase↗
PubMed1977

Effects of carrier morphology and buffer diffusion on the expression of enzymatic activity.

A very stable esterase (EC 3.1.1.-), which hydrolyses ethyl acetate, cephalosporin C and other acetyl esters with a maximum turnover number of 3-10(2) s-1, was isolated from Bacillus subtilis ATCC 6633 and immobilized on two supports: controlled-pore glass and powdered brick, a representative of carriers having a wide pore-size distribution. Carrier morphology determines diffusion rates and the expression of activity. Rate-limiting mass transfer of buffer leads to apparent losses of activity, gross distortions of molecular pH vs. activity profiles and to apparent deviations from Michaelis-Menten kinetics.

Bacillus subtilis↗