Search PubMed⌕ Search

Biomedical subjects

B Christensen

Publications and source records attributed to B Christensen.

At least 145 records · Page 8Linked to original sources
PubMed1990

Rectal compliance in the assessment of patients with fecal incontinence.

Rectal compliance (dV/dP) was studied in 31 patients with fecal incontinence, 8 patients with constipation, and 16 control subjects. Patients with fecal incontinence experienced a constant defecation urge at a lower rectal volume and also had a lower maximal tolerable volume and a lower rectal compliance than control subjects (median 126 vs. 155 ml, 170 vs. 220 ml, and 9 vs. 15 ml/mm Hg, respectively; P less than 0.05). Constipated patients had a higher constant defecation urge volume and maximal tolerable volume than controls (median, 266 ml and 300 ml; P less than 0.05). There was no differences in the parameters between patients with idiopathic fecal incontinence and patients with incontinence of traumatic origin, indicating that a poorly compliant rectum in patients with fecal incontinence may be secondary to anal incontinence due to the lack of normal reservoir function.

Adult↗
PubMed1990

Reflections during a study on family therapy with drug addicts.

This article presents ideas and reflections emerging during a project on family therapy with drug abusers. Initially inspired by the writings of Stanton and Todd on the subject, the project developed into a recursive and self-reflective process, characterized by increasing doubts about the usefulness of categorization of families, of pre-planning therapy, and of the therapist as an "expert." The limitations of approaches that emphasize the importance of understanding the family structure as the basis for changing it are discussed, particularly with respect to how they decrease therapist flexibility and may block the family's finding their own solution. Alternative approaches to practice and research are also discussed, bearing on ideas particularly formulated by theoreticians and practitioners inspired by second-order cybernetics.

Adolescent↗
PubMed1990

Just do it!

Explore the source record for details and available documents.

Health Promotion↗
PubMed1989

Chorionic villus culture for prenatal diagnosis of chromosome defects: reduction of the long-term cultivation time.

We report in detail two series of chorionic villus cultivation for prenatal chromosomal diagnosis. Chorionic villi were sampled from both first- and second-trimester pregnancies. One hundred cultures were treated with trypsin-EDTA for 2 h and collagenase overnight, (method A) and 100 were treated with trypsin-EDTA for 1 h and collagenase for 2 h (method B). Using short-term enzymatic digestion, the cultivation time was reduced from 14 days to 6 days. Sufficient amounts of metaphases of good quality were present in 93 per cent of primary cultures harvested in situ, whereas enough metaphases of sufficiently good quality were in most cases present only after subcultivation of the cultures using method A. The decrease in cultivation time obtained is probably due to a higher yield of viable cells in monocellular suspension, an increased attachment efficiency, and a more rapid attachment of single cells (within 24 h).

Chorionic Villi↗
PubMed1989

Photogating of ionic currents across a lipid bilayer.

Photoformation of metalloporphyrin cations in a lipid bilayer increases the ionic currents of negative and decreases those of positive hydrophobic ions. At low concentrations of the mobile hydrophobic ion, a 30% change in conductivity is observed that decreases with increasing concentration of positive tetraphenylphosphonium ion and increases drastically with increasing concentration of negative tetraphenylboride ion. In the region of saturated conductance of boride ion, the increase in conductivity is 3.6-fold. A 15-fold increase is observed with the protonophore carbonyl cyanide 3-chlorophenylhydrazone. In this case the net charge gated is 300 times greater than the photogenerated charge in the bilayer membrane. Thus there is a net gain in this organic field effect phototransistor. The gating can also be accomplished by continuous light or chemical oxidants. Photogating is explained as space charge effects inside the bilayer.

Indicators and Reagents↗
PubMed1989

Differences in referral rates from general practice.

There are many unexplained differences in the rates at which general practitioners make referrals to other medical specialists. This study investigated 17,586 referrals from 141 general practitioners to specialists in seven specialties in Ringkjøbing county in Denmark. As an expression of the referral rate, a referral index was estimated for every general practitioner. The referral index was the number of referrals to the specialist per 1000 patients per year, including children, standardized for age and sex to the average population in Ringkjøbing county. The following six variables were evaluated in relation to the referral index: specialists in the local area, doctors per practice, consultations per general practitioner per year, patients registered, consultations per 1000 patients per year standardized for age and sex, and supplementary procedures per consultation. Stepwise multiple regression analysis was used. The study showed that the referral index rose both with a better access to specialist and with an increasing number of consultations per practitioner per year. The referral index fell with increased numbers of patients registered. No correlation was found between the referral index and number of supplementary procedures per consultation, number of doctors per practice and number of consultations per 1000 patients per year.

Denmark↗
PubMed1989

Changes in pneumonectomy-space gas tensions.

The development of a simple and reliable method for measurement of the partial pressures of the atmospheric gases offers the possibility of both basic and clinical examination of the air in natural as well as pathological or iatrogenic cavities. From measurements in nine patients a plot of the changes in pO2 and pCO2 in the pneumonectomy space from the end of the thoracotomy to the establishment of equilibrium with the blood gases was made. pCO2 equilibrated faster than pO2 (6- and 50 h respectively). The equilibrium difference between arterial pO2 and pneumonectomy space pO2 was 6.5 kPa (2.5-12.3 kPa) and we propose that measuring this difference may be a sensitive method for the diagnosis of bronchopleural fistula. During the study period one of the patients developed a bronchopleural fistula. The suspicion was based on X-ray findings and was supported by gas analysis from the pneumonectomy space, and conclusively confirmed by bronchoscopy.

Adult↗
PubMed1989

[Urticaria in general practice].

The vast majority of cases of urticaria and angio-edema are diagnosed and treated by general practitioners. Epidemiologic investigations have shown that 2.5 percent of the population annually seek medical advice for urticaria, and of these 95 percent consult a general practitioner. The available literature, however, is mainly based on materials from specialist clinics, and outpatients hospital departments. The clinical picture of urticaria as seen by the general practitioner differs, however, is essential features from that observed in selected patient groups. Recent studies from the primary health care services have confirmed this observation.

Child↗
PubMed1988

On the alcianophilia of the drug suramin used as a tool for inducing experimental mucopolysaccharidosis.

The trypanocidal drug suramin was previously reported to induce mucopolysaccharidosis in rats; apart from the biochemical demonstration of increased tissue concentrations of sulfated glycosaminoglycans (GAGs), a strongly positive staining reaction with the cationic dye Alcian Blue was taken as indicating GAG-storage (Constantopoulos et al. 1983). The purpose of the present report is to point out a methodical pitfall. In model experiments it was found that suramin itself, being a polysulfated compound, gives a strongly positive reaction with Alcian Blue at pH 1. It is known that suramin is accumulated in the lysosomes and that high drug concentrations are retained in the tissues for weeks. Therefore a positive staining reaction with Alcian Blue observed in a given cell cannot be conclusively attributed to the storage of sulfated GAGs as has been done in the past. The present report may be a warning that, in the case of the suramin-induced animal model of mucopolysaccharidosis, the usual histochemical strategy, i.e. staining with cationic dyes, is not suitable for analysing the cellular distribution pattern of GAG-storage, since the inducing drug by itself reacts with the indicator dye.

Alcian Blue↗
PubMed1988

Channel-forming properties of cecropins and related model compounds incorporated into planar lipid membranes.

Cecropins, positively charged antibacterial peptides found in the cecropia moth, and synthetic peptide analogs form large time-variant and voltage-dependent ion channels in planar lipid membranes in the physiological range of concentration. Single-channel conductances of up to 2.5 nS (in 0.1 M NaCl) were observed, which suggests a channel diameter of 4 nm. Channels formed by the peptides cecropin AD and MP3 had a permeability ratio of Cl-/Na+ = 2:1 in 0.1 M NaCl. A comparative study of the three cecropins, cecropins A, B, and D, and of six synthetic analogs allowed determination of structural requirements for pore formation. Shorter amphipathic peptides did not form channels, although they adsorbed to the bilayer. A flexible segment between the N-terminal amphipathic region and the C-terminal more hydrophobic region of the peptide was required for the observation of a time-variant, voltage-dependent conductance. Cecropin AD was the most effective voltage-dependent pore-forming peptide and was also the most potent antibacterial peptide against several test organisms. A positive surface charge or cholesterol in the bilayer reduced the conductances caused by cecropin AD or MP3 by at least 5-fold. This behavior is consistent with the known insensitivity of eukaryotic cells to cecropins. Our observations suggest that the broad antibacterial activity of cecropins is due to formation of large pores in bacterial cell membranes.

Amino Acid Sequence↗
PubMed1988

In-the-ear hearing aids. The use and benefit in the elderly hearing-impaired.

Preliminary clinical experiences with in-the-ear hearing aids (ITE-HAs) have been promising, and a beneficial effect has been demonstrated in younger hearing-impaired subjects. However, the subjects applying for audiological examination and rehabilitation are predominantly elderly people (i.e. greater than or equal to 70 years). The present questionnaire examination was performed in order to evaluate the use and benefit of ITE-HAs also in the elderly hearing-impaired, and compare with the effect in younger subjects. An extensive questionnaire was sent 6 months after hearing aid fitting to all patients fitted with ITE-HAs. A total number of 693 subjects corresponding to 80% responded to the questionnaire. 70% of the patients are greater than or equal to 70 years and 23% are above the age of 80 years. The results demonstrate that the elderly hearing-impaired use the hearing aids predominantly in situations when listening to television and in small groups; 64% use their hearing aids the whole day and only 6% never use the aids; with increasing age were indicated increasing handling problems, both concerning change of battery, handling of volume control, and insertion of the aid into the ear canal. Only 8% of the patients were dissatisfied with the cosmetic appearance of the hearing aids, the dissatisfaction being more frequent in the young age group below 70 years (16%) than above the age of 70 years (9%). It is concluded that also the elderly hearing-impaired use and benefit from ITE-HAs.

Adolescent↗
PubMed1988

Clinical application of brain-stem audiometry.

Based on the examination of 249 consecutive patients, the usefulness of brain-stem response audiometry in a major audiological clinic was evaluated. Auditory brain-stem responses were performed either for hearing threshold determination (67 patients) or for assessment of retrocochlear hearing loss (182 patients). The results demonstrate that ABR is a reliable method for the estimation of hearing thresholds in non-cooperative subjects. The rate of false positives was 5% and no false negatives were found. In combination with caloric testing, ABR is considered a valuable testing procedure in the audiological clinic and it may form the basis for submission to brain imaging examination when a suspicion of retrocochlear hearing disorder is raised. Concerning the diagnosis of retrocochlear hearing disorder, no false negatives have yet been found, while a rate of 13% of false positives has been indicated.

Adolescent↗
PubMed1988

Referral from general practice to dermatologists.

There are many unexplained differences in the rates at which general practitioners make referrals to other medical specialists. We investigated 5,082 referrals from 141 general practitioners to dermatologists in Ringkøbing county in Denmark. As an expression of the referral rate to dermatologists an index of referral to dermatologists was estimated for every general practitioner. The index of referral to dermatologists was the number of referrals to the dermatologists per 1,000 patients per year, including children, standardized for age and sex to the average population in Ringkøbing County. The following six variables were evaluated in relation to the referral index: 1) Distance to the dermatologists, 2) number of doctors per practice, 3) number of consultations per general practitioner per year, 4) number of patients registered, 5) number of consultations per 1,000 patients per year standardized for age and sex, and 6) number of supplementary procedures per consultation. Stepwise multiple linear regression analysis was used. The study showed that the referral index to dermatologists fell both with distance to the dermatologist and with the number of supplementary procedures per consultation. No correlation was found between the referral index and the four other variables studied.

Denmark↗
PubMed1987

Time-resolved protonation dynamics of a black lipid membrane monitored by capacitative currents.

The laser-induced proton pulse (Gutman, M. (1986) Methods Enzymol. 127, 522-538) was used for transient protonation of one side of a black lipid membrane. The charging of the membrane drives an electric (voltage or current) signal selectively representing the fast proton exchange at the membrane/electrolyte interface. The sensitivity of the electric signal to the presence of buffer indicates that proton transfer is measured, not some dyes or membrane photoelectric artifact. The same event can be visualized in an analogous system consisting of a pH indicator adsorbed to neutral detergent-phospholipid mixed micelles. The time-resolved light absorption transient is equivalent to the electrically determined transient charging of the membrane surface. The sensitivity of the current measurement exceeds the spectrophotometric method by 6-8 orders of magnitudes. As little as 10(-18) mol of H+ reacting with 0.75 mm2 of the membrane surface can be monitored in a time-resolved observation. Both types of observed transients were accurately reconstructed by the numerical solution of coupled, non-linear, differential equations describing the system. The rate constants of the various proton transfer reactions were calculated and found to be of diffusion controlled reactions. There is no evidence for any barrier at the interface which either prevents protons from reaching the membrane, or keeps proton on the interface. The electric measurements can be applied for monitoring proton transfer kinetics of complex biomembrane preparations.

Hydrogen-Ion Concentration↗