Biomedical subjects

K V Andersen

Publications and source records attributed to K V Andersen.

51 records · Page 3Linked to original sources

PubMed1991

A nuclear magnetic resonance study of the hydrogen-exchange behaviour of lysozyme in crystals and solution.

Amide hydrogen/deuterium exchange behaviour has been studied for all of the peptide amides of hen lysozyme by means of two-dimensional n.m.r. spectroscopy. The amides have been grouped into four categories on the basis of their rates of exchange in solution at pH 4.2 and 7.5. The distribution of the amides into the different categories has been examined in the light of the crystallographic structural information, considering the type of secondary structure, the nature of hydrogen bonding and the distance from the protein surface. None of these features was found to determine uniquely the pattern of hydrogen exchange rates within the protein. The exchange behaviour of the individual amides could, however, in general be rationalized by a combination of these features. Hydrogen exchange was also monitored in both tetragonal and triclinic crystals of lysozyme, by allowing exchange to take place in the crystals prior to dissolution and recording of n.m.r. spectra under conditions where further exchange was minimized. This enabled direct comparison to be made of the exchange behaviour in the crystals and solution. A reduction in exchange rate was observed in the crystalline state relative to solution for a substantial number of amides and distinct differences between exchange in the different crystals could be observed. These differences between the solution and the different crystal states do not, however, correlate in a simple manner with proximity to intermolecular contacts in the crystals. However, the existence of these contacts, which are on the surface of the protein molecule, have a profound effect on the exchange of amides in the interior of the protein. The results indicate that the spectrum of fluctuations giving rise to hydrogen exchange may be significantly altered by the intermolecular interactions present within the crystalline state.

Amides↗

PubMed1991

Accurate measurements of coupling constants from two-dimensional nuclear magnetic resonance spectra of proteins and determination of phi-angles.

A new and simple method to measure 3JHNH alpha coupling constants of proteins by adding and subtracting traces from corresponding two-dimensional nuclear Overhauser enhanced spectroscopy and two-dimensional correlated spectroscopy cross peaks after scaling is proposed. The optimal scaling for the addition and the subtraction of the two traces is obtained by minimizing an error function. The method was proven to give accurate and precise measurements of coupling constants when tested with a series of simulated spectra. The accuracy of the method was better than 0.1 Hz for all test cases including the limiting case of J = 2.0 Hz and line-width = 11.0 Hz. The accuracy of the method was better than 0.1 Hz for all test cases including The 3JHNH alpha coupling constants were measured in two-dimensional nuclear magnetic resonance spectra of the two proteins barley serine proteinase inhibitor (CI-2) and the bacterial ribonuclease (barnase) of Bacillus amyloliquefaciens. The experimentally measured coupling constants were used to calculate the constants in a Karplus equation to be: 3JHNH alpha = 6.7 cos2(phi-60) -1.3 cos(phi-60) +1.5. These constants are in good accordance with those obtained for basic pancreatic trypsin inhibitor (BPTI). In addition, special emphasis is given to the measurements of positive phi-angles, and to the contribution of molecular dynamics on the apparent coupling constants.

Bacillus↗

PubMed1991

A perinatal audit of stillbirths in three Danish countries.

All stillbirths in 1985 and 1986 in three Danish counties were assessed in a perinatal audit. The aim was to investigate if departure from generally accepted standards of satisfactory perinatal care might have contributed to stillbirths, and also to investigate if differences in the structure of antenatal care and the delivery systems might have any influence on the rate of stillbirths. 119 cases evaluated, 70 were classified as unavoidable deaths, in 48 cases a different treatment might have improved the infant's possibility of survival and in one case consensus was not reached. The most frequent cause of suboptimal care was inadequate antenatal care of obvious signs of intrauterine growth retardation. Directives for visitation between surgical and obstetric departments were essential to the rate of stillbirth. The results indicate that it might be possible to achieve a further decrease in the number of stillbirths by intensifying the postgraduate training of the professionals and by issuing guidelines for the sharing of care responsibilities.

Delivery, Obstetric↗

PubMed1991

A perinatal audit of neonatal deaths in three Danish counties.

A perinatal audit of 109 neonatal deaths was carried out in three Danish counties (A, B and C) in order to investigate whether differences in the structure of antenatal care, delivery, and neonatal service had any influence on neonatal outcome and whether departure from generally accepted standards of satisfactory perinatal and neonatal care might have contributed to neonatal deaths. In the county (C) characterised by having no intensive neonatal care unit, significantly fewer liveborn infants with a gestational age of less than 28 weeks were reported to the Birth Register. County C had also significantly more potentially avoidable deaths compared with the county (B) which had a neonatal intensive care unit with specially trained staff available around the clock. The neonatal department in county A did not have specially trained doctors available in the hospital around the clock, and some cases of suboptimal care were caused by inadequate staffing and inappropriate decisions made by inexperienced junior doctors. The results indicate that it should be possible to improve the quality by having obstetric departments with access to neonatal intensive care units staffed with qualified personnel around the clock and by intensifying the postgraduate training of professionals performing peri- and neonatal care.

Denmark↗

PubMed1989

[Preventive health examinations of pregnant women in Denmark. Structure and organization].

In Denmark, pregnant women are offered antenatal care in a nationwide programme. This programme is organized around health examinations in general practice, midwives centres and hospital outpatient departments. During the winter 1986/87 a nationwide investigation of antenatal care was carried out in Denmark. A random sample of approximately 1/3 of the general practitioners, all of the midwives who had antenatal consultations and the medical staffs of 26 departments of obstetrics and gynaecology with more than 100 deliveries in 1985 received a questionnaire about the content of a definite antenatal examination and certain conditions of organization. The obstetricians could describe three different types of antenatal examinations depending upon the place and arrangement of work. The percentage replies received were 62 for general practice, 86 for the midwives and 62, 69 and 55 from the doctors in the place of delivery. 50% of the pregnant women had been attached to the same practice for at least five years. 70% of the general practitioners performed approximately one antenatal examination weekly. Only few hospital districts had attempted to have the first examination by the midwife at the 12th week of pregnancy. 25% of the places for examination by midwives were outside hospitals, which, according to the guidelines for antenatal care, do not entirely fulfill the intentions concerning situation in the patient's immediate surroundings. All of the obstetric departments offered routine examinations in the 16th-18th weeks and a number of these also routine examinations in the third trimester.(ABSTRACT TRUNCATED AT 250 WORDS)

Denmark↗

PubMed1989

[Preventive health examinations of pregnant women in Denmark. Education, supervision and postgraduate education].

A questionnaire about the content of a concrete antenatal examination and their own qualifications was sent to a random sample consisting of 1/3 of general practitioners in Denmark, all of the midwives who had antenatal consultations, the medical staffs of 26 departments of obstetrics and gynaecology and 26 surgical departments with more than 100 deliveries in 1985. The medical staffs could describe three different types of antenatal examinations depending upon the place and function. The percentages of replies received were 62 for general practice, 86 for midwives and 63, 69 and 55 for the medical staffs of the institutions involved. 49% of the general practitioners had worked in departments of obstetrics and gynaecology for at least six months. 62% of the doctors who described antenatal examination in week 16-18 were house officers or registrars and 28% were specialists. Among the medical staff who described an antenatal examination of a woman with an at risk pregnancy, 61% were consultants or senior registrars and 49% were specialists. The commonest goal for postgraduate training where non-specialists were concerned was general practice. Supervision in one form or another was possible in all of the departments participating, as a rule because an experienced colleague was present in the outpatient department. Supervision may be improved by alterations in the working arrangements.

Denmark↗

PubMed1989

[Cesarean section under epidural anesthesia. A questionnaire study].

Seventy-four women selected at random who had been subjected to Caesarean section replied to questions about their satisfaction with epidural anaesthesia at various stages during the intervention. General discomfort increased during the intervention and pain contributed most to this. 96% of the women would recommend the method to others.

Adult↗

PubMed1989