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Biomedical subjects

B Bengtsson

Publications and source records attributed to B Bengtsson.

At least 19 recordsLinked to original sources
PubMed1992

Correction of optic disc measurements on fundus photographs.

If defined as diameter of image/diameter of object, the magnification M of the eye-camera system is kB, where k is a camera constant and B represents the vergence of the internal axis of the eye. The magnification may be assessed (1) from the length l of the eye, using the formula 1.336 k/(l-0.0016); (2) from the glass refraction G, using the formula kD/(1-G/D), in which D is the "normal" refractive power of the eye; or (3) from the principal point refraction A and the deviation delta D1 from the "normal" refractive power of the cornea, using the formula kD.(1 + delta B/D), where delta B = A + 0.84 delta D1. If k is 0.042 m, as in the Zeiss camera, and D is about 60 dpt, the formulas may be written as (1) M = 0.056/(l-0.0016); (2) M = 2.5/(1-0.017 G); and (3) M = 2.5.(1 + 0.017 delta B).

Fundus Oculi↗
PubMed1992

Mathematical description of the concentration of oxytetracycline and penicillin-G in tissue cages in calves as related to the serum concentration.

A mathematical model based on Fick's laws of diffusion describing the concentration of drug in tissue cage models was elaborated. The model takes into account differences in protein binding, tissue cage geometry and serum pharmacokinetics. The validity of the model was tested against experimental data obtained from a tissue cage model in calves by simultaneous fitting to serum and tissue cage fluid (TCF) data in a non-linear least-squares regression computer program. Concentrations of penicillin-G (pen-G) in serum and TCF following intravenous (i.v.) administration of potassium pen-G were adequately described by the mathematical model. Concentrations in TCF after intramuscular (i.m.) administration of the same drug and of procaine pen-G could be predicted by the mathematical model. Concentrations of oxytetracycline (OTC) in serum and TCF following i.v. administration and continuous i.v. infusions were also adequately described by the model, and TCF concentrations after i.m. administration of the same drug could be roughly predicted. The results indicate that pen-G and OTC have the same permeability coefficient for transport from serum to TCF.

Animals↗
PubMed1992

Changes with age in Schiötz and Goldmann readings.

Three thousand one hundred and fifteen paired Schiötz and Goldmann readings in persons aged 10-79 years were re-examined. There was first a drop and then a rise in IOP with increasing age. The two methods gave very similar results up to age 50. After the age of 50 Goldmann pressures rose faster than Schiötz pressures. Changes in Schiötz readings do not reliably reflect true changes in IOP over time within the same eye or between different age groups within the same population.

Adolescent↗
PubMed1991

Distribution of penicillin-G and spiramycin to tissue cages and subcutaneous tissue fluid in calves.

Antibacterial drug concentrations in serum, tissue cage fluid (TCF) and subcutaneous tissue fluid (SF), sampled either by filter paper discs or by microcapillaries, were measured after single intramuscular injections of potassium penicillin-G (KPG), procaine penicillin-G (PPG) and spiramycin adipate in calves. Concentration-time curves had essentially similar profiles in serum and SF, but peak levels were lower and occurred later in SF. From approximately four hours after drug administration, penicillin-G levels in SF were similar to levels in serum after KPG as well as after PPG administration. Elimination half-life (t1/2) of penicillin-G in serum was similar to t1/2 in SF after PPG administration but was longer in SF than in serum after KPG administration. Spiramycin concentrations were higher in SF than in serum and the t1/2 of spiramycin in SF was longer than in serum. For all three drugs, the t1/2 was longer in TCF than in serum and concentration-time curves in TCF were characterised by a slow rise and decline. The two methods of sampling SF, by filter paper discs and by microcapillaries, gave similar but not identical results. Penetration into SF and TCF, measured as the total area under curve ratio, was better for spiramycin than for penicillin-G, but the latter drug had a higher penetration ratio to TCF in the first 12 hours.

Animals↗
PubMed1991

Back pain: a study of twins.

To evaluate the relationship between genetic factors and back pain, 5029 MZ and 7876 DZ twin pairs were investigated by a questionnaire. The data were analyzed with regard to physical symptoms, eg, back pain, and certain work conditions. Pain was reported by about 17% of the male and 13% of the female twins in the material. The occurrence of back pain was strongly associated with work load, especially among the male twins. Twin concordance regarding back pain was considerably higher in MZ than in DZ twins. Of four groups who were studied, statistically significant differences between the two twin categories were observed in three cases. This result supports the assumption that a relationship exists between genetic factors and the occurrence of back pain. Official registrations for sick-leave pay in a sample of 247 twins confirmed the interview information on back pain. Just a few cases were wrongly classified, ie, they were sick-listed because of back pain but had stated no back pain in the questionnaire.

Adolescent↗
PubMed1991

Distribution of oxytetracycline to tissue cages and granuloma pouches in calves and effect of acute inflammation on distribution to tissue cages.

The effect of acute inflammation on oxytetracycline (OTC) distribution was studied in a tissue cage model in calves. An acute inflammatory reaction was induced in tissue cages by injecting lipopolysaccharide (LPS) from Salmonella typhimurium. The distribution of OTC to tissue cage fluid (TCF) was also compared with distribution to fluid from granuloma pouches (GPF). Tissue from LPS-injected cages showed histological changes indicating an acute inflammatory reaction. Concentrations of OTC were higher in LPS cages than in controls; at 1, 2, 4 and 10 h the difference was statistically significant (P less than 0.05). Numerically the overall elimination rate constant (kel) was larger, elimination half-life (t1/2) shorter, peak concentration (Cmax) higher, and time of peak concentration (Tmax) shorter in LPS cages than in controls. The area under the curve (AUC) of OTC was greater and the ratio AUCTCF/AUCserum was higher in LPS cages than in controls. Although statistically significant differences were not found for all the pharmacokinetic parameters, it was concluded that distribution to and elimination from LPS cages were both faster than in controls. Concentration-time profiles of OTC were similar in TCF and GPF in that concentrations were lower and elimination was more prolonged than in serum. Levels were higher in GPF than in TCF up to 3 h after injection; thereafter the relationship was reversed. Distribution to and elimination processes from GPF appeared to be faster than from TCF as numerically kel was higher, t1/2 shorter and Tmax shorter in GPF than in TCF. It was concluded that the granuloma pouch model and the tissue cage model have similarities in distribution and elimination patterns and that differences are most probably due to differences in the ratio of the surface area to the volume.

Acute Disease↗
PubMed1991

Glaucoma case detection.

In Dalby more than 1,000 residents have been followed for a decade (1977-1987) with periodic comprehensive eye examinations including family history, ophthalmoscopy, slit-lamp examination, applanation tonometry, and computerized perimetry. The large majority were followed at long intervals (2.75 and 5.65 years). Ophthalmoscopy and tonometry were used to select a minor part of the population to be followed at shorter intervals. In this way 16 out of 24 manifest glaucomas detected after the first survey were found among patients followed at shorter intervals. A closer look at the data suggested that the selection could have been further improved if the slit-lamp examination and the family history had been used in much the same way as ophthalmoscopy and tonometry. On this basis new criteria to select persons said to have 'presumptive glaucoma' are proposed.

Aged↗
PubMed1990

Optic disc haemorrhages preceding manifest glaucoma.

The Dalby population has been subjected to repeated glaucoma surveys in a deliberate effort to describe the early stages of glaucoma. A total of 28 haemorrhagic episodes were observed at 3819 examinations of persons not having manifest glaucoma. The prevalence of optic disc haemorrhages was dependent on age and residence. The mean IOP in eyes with optic disc haemorrhages was 17.0 mmHg. Only four out of 24 haemorrhages in eyes without pseudoexfoliations were associated with intraocular pressures over 20.5 mmHg. Of twelve cases followed more than six years two died and five developed manifest glaucoma. The period of latency between the detection of a haemorrhage and the development of a glaucomatous visual field defect was 2, 3, 5, 6, and 7 years, respectively.

Aged↗
PubMed1989

Characteristics of manifest glaucoma at early stages.

Intraocular pressures and optic disc hemorrhages were studied in all cases of manifest glaucoma detected in a defined population over a decade. High intraocular pressure was found to be an unreliable sign at the detection of a glaucomatous visual field defect and an unusual finding 5-10 years before. The prevalence of optic disc hemorrhages at the detection of a glaucomatous visual field defect was 33%. All but 9 of 44 persons with manifest glaucoma were found to have had at least one optic disc hemorrhage at one time or another.

Cohort Studies↗
PubMed1989

Concentrations of sulphadimidine, oxytetracycline and penicillin G in serum, synovial fluid and tissue cage fluid after parenteral administration to calves.

Drug concentrations in serum, synovial fluid and tissue cage fluid (TCF) in calves were measured after single i.m. doses of oxytetracycline hydrochloride (OTC), procaine penicillin G (PPG) and potassium penicillin G (KPG) and single i.v. doses of sulphadimidine (SDM) and OTC. For all drugs, concentration-time curves in serum and synovial fluid were not identical but they had similar profiles, with peak levels occurring at about the same time. Concurrent concentrations were lower in synovial fluid than in serum. For each drug, elimination half-lives from synovial fluid and from serum were similar, except for penicillin G after KPG administration which had a significantly longer half-life from synovial fluid than from serum (P less than 0.05). Of the two penicillin G preparations, PPG gave a significantly higher synovial fluid:serum area under curve (AUC) ratio than did KPG; 0.76 +/- 0.10 and 0.54 +/- 0.12, respectively (P less than 0.05). For OTC, the synovial fluid:serum AUC-ratio was 0.33 +/- 0.12 after i.m. and 0.34 +/- 0.08 after i.v. administration. Drug concentration-time curves of TCF had different profiles compared with serum, with relatively low and delayed peak levels and slow elimination from TCF. TCF:serum AUC-ratios did not differ significantly for i.m. and i.v. administration of OTC; 0.10 +/- 0.10 and 0.19 +/- 0.03 respectively (P greater than 0.05). Potassium penicillin G (KPG), however, gave a significantly higher TCF:serum AUC-ratio than PPG; 0.55 +/- 0.21 and 0.19 +/- 0.07, respectively (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Studies on the bioavailability of tetracycline chloride after oral administration to calves and pigs.

The serum concentrations of tetracycline (TC) were studied in calves after administration in the milk replacer and in pigs after administration in feed and drinking water. Serum concentrations of potential therapeutic value (greater than 1 microgram/ml) were obtained in the calves when TC was fed in the milk replacer at a dose of 25 mg/kg body weight twice daily. Significantly higher serum concentrations were achieved after a single oral dose (50 mg/kg) given in the milk replacer than afer the same dose given as a water drench four hours after the first daily milk feeding. The difference was explained by the fact that the calves probably consumed their daily amount of concentrate and an unknown amount of hay previous to the drench. Earlier studies showed that concentrates reduce the bioavailability of tetracyclines more than a conventional milk replacer. Serum concentrations of potential therapeutic value could not be achieved in the pigs in spite of recommended doses. The TC concentrations in the water were 400 mg/l and 800 mg/l. Tetracycline did not appear to influence the water consumption. Serum concentrations were highest in the evening and fell during the night. The highest levels after 400 mg/l water were 0.30-0.47 microgram/ml. The corresponding levels after 800 mg/l were 0.65-1.15 micrograms/ml. It was concluded that feed seriously reduced the bioavailability of TC. The influence of feeding was demonstrated in a single dose study. Fasted animals showed much higher serum levels than non-fasted ones. Very low and constant serum levels (about 0.2mg/ml occurred when TC mixed in the feed at a concentration of 1,00 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1989

Observations concerning the course of glaucoma.

Four cases with glaucomatous damage to the optic nerve head preceding a rise in intraocular pressure from normal or borderline to high values, are reported. The question of whether such cases are exceptional or typical and, therefore, best explained by a coincidence of diseases or by one disease going through successive stages is discussed on the basis of 10 further cases from a population study. Many clinicians claim that there are two groups of patients: a large one with 'ordinary' glaucomas supposedly caused by high intraocular pressures and a small one with low tension glaucomas presumed to have low perfusion pressures for other reasons. This classification circumvents the discussion on etiology and gives theoretical support to conventional treatment. Accumulated clinical observations indicate, however, that it should not be accepted without discussion. We describe here a few selected cases with glaucomatous damage to the optic nerve head preceding a rise in the intraocular pressure from normal or borderline to high values.

Aged↗
PubMed1989

Diagnosis of early glaucoma with flicker comparisons of serial disc photographs.

We evaluated flicker comparison, a technique for detecting differences in serial fundus photographs. Serial optic disc photographs and computerized threshold visual fields were obtained every 3 months for an average of 40 months in 131 eyes of 81 patients with elevated intraocular pressure and normal visual fields. Two serial monophotographs were projected, optically aligned, and superimposed; analysis was done by alternately viewing first one and then the other image. We found flicker analysis of serial disc photographs to provide results which were closely correlated with those of computerized threshold perimetry. Thus, of those 12 eyes which developed field defects, eight showed definite change and two showed highly suspected change in optic disc configuration. Only two eyes showed a definite alteration in optic disc anatomy without the development of field loss, and field defects appeared in only one of 109 eyes in which there was no change or suspected change on flicker comparison. The flicker method was more sensitive than conventional nonflickered comparisons, but changes could usually be seen also with conventional inspection once they had been detected by the flicker method. Our findings suggest that flicker analysis may offer a considerable improvement over current standard methods of analyzing serial photography and may be a useful complement to routine perimetry. However, this method requires special equipment; requires that the photographs be similarly centered; and is time-consuming. Alignment of photographs by means of computerized image analysis techniques could make the method clinically practicable.

Diagnosis, Differential↗
PubMed1988

Effects of vasopressin on the human non-pregnant uterus: studies with analogues of different vasopressor potencies.

The uterotonic effects of arginine8-vasopressin (AVP) have been studied on uterine strips from non-pregnant women. Concentration-dependent contractions could be recorded over a 10 min period in the presence of AVP (5.5.10(-10)-3.10(-7) M); the most reproducible recordings were obtained with tissue from the inner part of the myometrium. Analogues of AVP and oxytocin (OT), modified at positions 1 (2-hydroxy-3-mercaptopropionic acid, deamino-3-mercaptopropionic acid), 2 (Phe), 4 (Arg, Val), 7 (Sar) or 8 (Orn) were synthesized and tested for uterotonic activity on human and rat uterine strips, and for vasopressor and antidiuretic activity in the rat in vivo. There was a positive correlation between the activity of these analogues on non-pregnant human myometrial tissue with that in the rat vasopressor assay (r = 0.86, P less than 0.01) but none with their activity in the antidiuretic assay. For example, [Mpa1,D-Arg8]vasopressin had more than twice the antidiuretic activity of AVP but less than 0.2% of its pressor or human uterotonic potency (Mpa = 3-mercaptopropionic acid). Correspondingly, the specific pressor analogue [Hmp1,Phe2,Orn8]OT was as potent as AVP on the human uterus, but had less than 3% of its antidiuretic activity (Hmp = 2-hydroxy-3-mercaptopropionic acid). There was no correlation between the uterotonic activities of AVP or its analogues when non-pregnant human and rat tissues were compared, indicating that rat uterine tissue is a poor guide when testing analogues intended for clinical use in non-pregnant women.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗