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A Pankiewicz

Publications and source records attributed to A Pankiewicz.

4 recordsLinked to original sources
PubMed2000

Comparative study of the lipogenic potential of human and rat adipose tissue.

The reported low activity of lipogenic enzymes (especially adenosine triphosphate [ATP]-citrate lyase) in human adipose tissue led to the general conclusion that in humans lipogenesis occurs primarily in the liver. However, recent studies indicate that the liver plays a minor role in de novo lipogenesis and suggest that adipose tissue may be the principal lipogenic human tissue. In an attempt to resolve these contradictions we reinvestigated the lipogenic potential of human adipose tissue and compared with adipose tissue of rats fed a high-fat diet for 2 weeks and fasted overnight before death. These conditions mimic the nutritional state of patients at the moment of tissue sampling. We found that overnight fasting of the rats maintained previously for 12 days on a high-fat diet caused a decrease of ATP-citrate lyase of about 7-fold. Thus, in human adipose tissue, the mean activity of ATP-citrate lyase was approximately 8 times lower than in rats fed a high-fat diet and fasted overnight, and about 50 times lower than in rats maintained on normal laboratory diet. Unlike ATP-citrate lyase, fatty acid synthase (FAS) activity was only slightly lower in human adipose tissue than in rats maintained on a normal laboratory diet. Comparable FAS activity was found when rats were fed a high-fat diet and fasted overnight. The average activities of human adipose tissue acetyl-coenzyme A carboxylase, malic enzyme, and glucose-6-phosphate dehydrogenase were approximately 3-, 4-, and 6-fold lower than in adipose tissue from rats fed a high-fat diet and fasted overnight before tissue sampling, while the activity of 6-phosphogluconate dehydrogenase in humans was higher than in rat adipose tissue. No significant differences in lipogenic enzyme activities were found between male and female and between lean and obese patients. The rate of fatty acid synthesis in intact pieces of human adipose tissue was approximately 5 times lower than in adipose tissue pieces of rats fed a high-fat diet and fasted overnight before tissue samples were taken. The comparison of the lipogenic potential of humans and rats (maintained on the diet to mimic the nutritional state of patients at the time of tissue sampling) suggests that human adipose tissue is an important site of fatty acid synthesis.

ATP Citrate (pro-S)-Lyase↗
PubMed1998

Escherichia coli dnaA gene function and bacteriophage lambda replication.

Allele specificity of the Escherichia coli dnaA gene function in the replication of plasmids derived from bacteriophage lambda has been demonstrated previously. Here, using a series of dnaA temperature-sensitive mutants, we investigated dnaA allele specificity of the replication of phages lambda P+ and lambda Pts 1 pi A66. We found that phage lambda P+ produces its progeny efficiently at 43 degrees C irrespective of the dnaA allele, whereas lambda Pts 1 pi A66, which is unable to develop lytically in the dnaA+ host at this temperature, can replicate with different efficiency in certain dnaA mutants. Since the main role of DnaA in lambda development seems to be stimulation of transcription from the pR promoter, we measured the activity of this promoter (using a pR-lacZ fusion) and the abundance of pR-derived transcripts (by Northern blotting analysis) in dnaA+ host and dnaA(ts) mutants at 30 and 43 degrees C. We found significant differences in the activity of pR in various dnaA(ts) mutants at 30 degrees C, which indicate different levels of stimulation of this promoter by products of particular dnaA alleles at permissive temperature. Differential levels of DnaA-mediated stimulation of pR in various dnaA(ts) mutants were also found at 43 degrees C. Stimulation of the pR promoter by DnaA is necessary for both efficient production of the lambda replication proteins, O and P, and effective transcriptional activation of ori lambda. The differences in the efficiency of pR activation observed in dnaA mutants at 30 and 43 degrees C can explain the mechanisms of allele specificity of dnaA gene function in the replication of bacteriophage lambda and plasmids derived from this phage.

Alleles↗
PubMed1996

Allele specificity of the Escherichia coli dnaA gene function in the replication of plasmids derived from phage lambda.

We demonstrate a variation in the effects of seven alleles of the Escherichia coli dnaA gene, which cause temperature sensitivity of initiation of chromosomal replication, on the replication of lambda phage-derived plasmids at 30 degrees C. These mutants showed no allele specificity of dnaA function in replication of either of two lambda pi plasmids studied. On the other hand, the inability of the lambda P+ plasmid to replicate in dnaA508, 46 and 204 cells, in dnaB (groP A15) or in cells that are temperature sensitive for the chaperone genes dnaK756, dnaJ259 and grpE280 at 30 degrees C was suppressible by a single pi mutatation. This suggests that it is a common property of the pi protein, probably its weaker interaction with DnaB helicase, that is responsible for the suppression. One can also conclude that the DnaA-regulated transcriptional activation of ori lambda acts at the step, in which all these gene products cooperate, i.e. during preprimosome loading and chaperone-mediated release of DnaB from P protein inhibition.

Bacterial Proteins↗