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Biomedical subjects

P Bak

Publications and source records attributed to P Bak.

63 records · Page 4Linked to original sources
PubMed1985

Guillain-Barré syndrome in a Danish county.

In a retrospective population-based study, we reviewed clinical records of 51 patients with Guillain-Barré syndrome (GBS) during the years 1965 to 1982. The mean annual age-adjusted incidence rate was 1.14 per 100,000 people. Compared with reports from Israel, Danish and Swedish patients with GBS seem to have more extensive and more severe symptoms, although survival rate and recovery prognosis are probably the same.

Adolescent↗
PubMed1979

Characterization of human chromosomal unit fibers.

A structural component of mitotic chromosomes that partially explains the compaction of DNA within mitotic chromosomes is suggested on the basis of the occurrence of long, regular cylindrical structures in preparations of isolated human chromosomes. These structures, "unit fibers", of a rather constant diameter of about 4,000 A have been postulated to be formed by coiling of the 250-300 A solenoid chromatin fiber that itself is formed by coiling of the 100 A string of nucleosome fiber. The human chromatid would thus be composed by a hierarchy of helices with contraction ratios for DNA at each level of coiling of 7 (string of nucleosomes), 5 (solenoid) and 40 (4,000 A "unit fiber" or "super-solenoid") which results in an overall contraction ratio for DNA in the "unit fiber" structures of about 1,400, which is approximately 5-fold less than the final contraction of DNA in intact chromatids of condensed metaphase chromosomes. The present report concerns more detailed studies with respect to the dimensions and cytochemical properties of the "unit fiber" structures observed in preparations of isolated human mitotic chromosomes that provide direct and indirect evidence in support of their "super-solenoid" structure and relate to known properties of human mitotic chromosomes.

Cells, Cultured↗
PubMed1979

Chromosomal unit fibers in Drosophila.

Chromosomal unit fibers consisting of long, regular fibers of about 0.40 micron diameter were obtained from disintegrated, isolated chromosomes of two Drosophila melanogaster cell lines. In one cell line with an essentially normal karyotype, three clearly defined size classes of 15,13, and 11 micron length were observed corresponding to the three larger chromosomes of Drosophila. In a cell line carrying an additional translocation between the two largest chromosomes a 19 micron fiber derived from the translocation chromosome was observed. Direct determinations of the DNA content per micron length of Drosophila unit fibers show that DNA is contracted by a factor of about 1400x in agreement with calculations based on the length of the unit fibers and the known DNA content of the individual Drosophila chromosomes. These findings support our previously proposed model for the unit fiber sub-structure of chromosomes as being derived by a hierarchy of coiling with the corresponding contraction ratios being 7 (100 A string of nucleosomes), 5 to 6 (250-300 A thick nucleohistone fiber), and about 40 (unit fiber), resulting in a total contraction of DNA in unit fibers in the order of 1400x.

Animals↗
PubMedDate not supplied

Effect of scalp infiltration with lidocaine on the circulatory response to craniotomy.

BACKGROUND: The purpose of the present study was to evaluate the influence of infiltration anesthesia of the projected line of incision in the skin of head on the hemodynamic response of the circulatory system, and the essential dose of opioids in 100 patients who underwent craniotomy. MATERIAL AND METHODS: The patients were divided into 4 groups: IA - brain tumors, no infiltration anesthesia; IB - cerebral aneurysms, no infiltration anesthesia; IIA - brain tumors + infiltration anesthesia; IIB - cerebral aneurysms + infiltration anesthesia. In the patients from groups IIA and IIB, the projected line of skin incision was injected with a 1% lidocaine solution (9.94+/-1.95 ml) five minutes before commencing surgery. RESULTS: No statistically significant differences were found between the various groups in regards to their weight, the time between infusion of the first dose of fentanyl and skin incision, the mean heart rates at time points T1 (prior to induction of anesthesia), T2 (prior to skin incision) or T3 (after skin incision), or mean arterial pressure values (MAP) at time points T1 or T2. A significant increase in MAP values (P<0.05) caused by skin incision was recorded in groups IA (from 95.2+/-9.85 to 119+/-10.6 mm Hg) and IB (from 88.4+/-11.5 to 100.3+/-11.4 mm Hg). In group IIA, MAP increased insignificantly, while in group IIB the MAP values did not change. CONCLUSIONS: Infiltration anesthesia of the projected line of skin incision in the head enabled maintenance of stability in the circulatory system and lower doses of opioids administered before commencing surgery.

Administration, Topical↗