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Biomedical subjects

K Buck

Publications and source records attributed to K Buck.

12 recordsLinked to original sources
PubMed1992

Multiple forms of prolactin receptor messenger ribonucleic acid are specifically expressed and regulated in murine tissues and the mammary cell line HC11.

The expression of PRL receptor mRNA in mouse tissues was studied. Seven PRL receptor transcripts of different sizes were found. The pattern of expression was tissue specific. The PRL receptor protein exists in isoforms of approximately 300 and 600 amino acids, which differ in the sequence and length of the cytoplasmic domain. Probes specific for the lower mol wt forms of the receptor hybridized to transcripts of 1.4, 2.4, 3.5, and 4.2 kilobases (kb), which were predominantly expressed in the liver and kidney. Among the three isoforms of the small form of the receptor, PR-3 was highly expressed, PR-2 was weakly expressed, and PR-1 was undetectable. Probes specific for the higher mol wt receptor form detected transcripts of 9 and 10 kb, expressed most strongly in the ovary, mammary gland, and kidney. An additional 8.3-kb transcript was expressed in the kidney. The PRL-responsive mouse mammary epithelial cell line HC11 expressed only the 9- and 10-kb receptor mRNAs, as did the mammary gland. The transcripts for the two PRL receptor forms were independently regulated during pregnancy and lactation in a tissue-specific manner. The expression of the small receptor form in the liver increased 7-fold during pregnancy and decreased during lactation. Its expression in the kidney remained constant. Expression of the larger receptor form increased 2.5-fold in the kidney during lactation, but remained constant in the mammary gland. In the ovary the expression of the large receptor form could be elevated 4-fold after induction of hyperovulation with FSH and hCG. Thus, in the mouse there are at least two forms of the PRL receptor regulated independently in different tissues.

Animals↗
PubMed1992

Parathyroid stimulation after bleeding in man.

A role for the PTH-calcium axis in the normal bone-marrow response to bleeding or erythropoietin administration has been demonstrated in rats. We studied 20 autologous blood donors, each donating two units of blood, who served as a human bleeding model. Fifteen patients completed the study. Blood donations were followed by a significant increase in serum intact PTH (2.15 +/- 0.67 to 2.81 +/- 0.84 pmol/l; p = 0.0003) and protein-corrected total calcium (2.43 +/- 0.09 to 2.49 +/- 0.08 mmol/l; p = 0.2). All the individual values remained within the normal range. PTH weakly correlated with the reticulocyte count, but not with the corrected serum calcium. We conclude that moderate bleeding in humans is followed by a physiological increase in serum PTH and calcium.

Adolescent↗
PubMed1991

Multiple human D5 dopamine receptor genes: a functional receptor and two pseudogenes.

Three genes closely related to the D1 dopamine receptor were identified in the human genome. One of the genes lacks introns and encodes a functional human dopamine receptor, D5, whose deduced amino acid sequence is 49% identical to that of the human D1 receptor. Compared with the human D1 dopamine receptor, the D5 receptor displayed a higher affinity for dopamine and was able to stimulate a biphasic rather than a monophasic intracellular accumulation of cAMP. Neither of the other two genes was able to direct the synthesis of a receptor. Nucleotide sequence analysis revealed that these two genes are 98% identical to each other and 95% identical to the D5 sequence. Relative to the D5 sequence, both contain insertions and deletions that result in several in-frame termination codons. Premature termination of translation is the most likely explanation for the failure of these genes to produce receptors in COS-7 and 293 cells even though their messages are transcribed. We conclude that the two are pseudogenes. Blot hybridization experiments performed on rat genomic DNA suggest that there is one D5 gene in this species and that the pseudogenes may be the result of a relatively recent evolutionary event.

Amino Acid Sequence↗
PubMed1986

Mutations affecting microtubule structure in Caenorhabditis elegans.

Three types of microtubules are seen in the neuronal processes of the nematode Caenorhabditis elegans. Single cytoplasmic microtubules of most neurones have 11 protofilaments whereas those of six touch receptor cells have 15 protofilaments. The axonemes of sensory cilia have nine outer doublets with a variable number (up to seven) of singlet microtubules. Mutations in 11 genes affect the appearance of these microtubules.

Animals↗
PubMed1984

Effect of the temporal pattern of a given noise dose on TTS in guinea pigs.

To show the effect of the temporal pattern of acoustic stimulation on TTS 15 min, guinea pigs were subjected to isoenergetic noises with the same spectrum. The exposures in a first experimental series were continuous noises and noise bursts. The continuous noise was presented with different durations and levels but always with the same energy. The noise burst stimulation consisted of a constant number of bursts with different interstimulus intervals. Both duration and repetition rate were shown to affect the TTS 15 min measured for these isoenergetic stimuli. A duration of 225 to 1800 s and a repetition rate of one per second produced the greatest TTS 15 min. In a second experimental series continuous noise and acoustic impulses with the same spectrum and 100-Hz repetition rate were presented at different levels. In this case the waveform of the stimulus (phase spectrum) was shown to have an effect on TTS 15 min.

Acoustic Stimulation↗