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Biomedical subjects

B Larsen

Publications and source records attributed to B Larsen.

At least 181 records · Page 10Linked to original sources
PubMed1984

Study of alleles of the second complement component (C2) on Canadian HLA haplotypes.

Typing for genetic variation in the second complement component C2 was performed on sera from HLA haplotyped Canadian families. Part of the data has been studied and analysed as a population; in addition there is a further random collection of haplotypes bearing the C2*2 allele. In the population data there were 444 separate haplotypes from unrelated parents or other founders: 4.7% of the haplotypes carried the uncommon allele C2*2; one haplotype carried the rare C2*3. Study of C2 2-1 heterozygotes in the population data revealed 59 haplotypes which carried the common C2*1 allele and one which carried a deficiency allele C2*0. The remaining haplotypes carried either C2*1 or else an undetectable C2*0 allele. In the entire data there were 281 meioses informative for C2. The only recombinant between HLA-B and C2 showed the C2 locus to be on the DR side of the B locus. Strong allelic association between C2 *2 and Bw22 and less strong association between C2 *2 and B15 suggested the possibility of two ancestral C2 mutants. Examination of other markers on these and subsequently collected haplotypes do not conflict with this idea since the B15 haplotypes mostly carry C4A *4, C4B *2 whilst the Bw22 haplotypes mostly carry C4A *4, C4B *4. The alternative idea, that there was one original mutant which crossed over from a B15 to a Bw22 haplotype or vice versa is not excluded, however. Since approximate equilibrium has been reached between Bw22 and the HLA-A locus alleles on these C2 *2 bearing haplotypes, we conclude that this mutation is at least 5000 years old. Other haplotypes carrying C2 *2 are assumed to be ancestral recombinants; if this is true, the C2 locus map position between HLA-B and HLA-DR is confirmed. Study of C2 mutation may provide a model for understanding the genetics of some disease susceptibility genes in the HLA region.

Alleles↗
PubMed1984

Critical assessment of antibacterial properties of human amniotic fluid.

A low molecular weight fraction of human amniotic fluid was found to be rapidly bactericidal for Escherichia coli ATCC 33908. Incubation in an atmosphere of CO2 but not N2 diminished the antibacterial effect suggesting that loss of CO2 and change in pH may be partly responsible for the observed antibacterial activity of the low molecular weight fraction of amniotic fluid. Incubation in pH 8.5 buffers did not duplicate the rapid killing of bacteria observed in the low molecular weight fraction of amniotic fluid, suggesting that elevated pH and an antibacterial factor from amniotic fluid act synergistically. The pH change in amniotic fluid which occurs in room atmosphere may account for some of the antibacterial effect which has been reported for amniotic fluid incubated aerobically.

Amniotic Fluid↗
PubMed1984

Enhancement of the antibacterial property of amniotic fluid by hyperthermia.

The intrinsic ability of human amniotic fluid to prevent growth of Escherichia coli varies with the test strain employed, but is enhanced by increasing the temperature of incubation, as demonstrated by viable counts of test organisms in amniotic fluid compared with growth media at various temperatures. The antibacterial activity of amniotic fluid is reversed at all temperatures by the addition of potassium phosphate, but residual inhibition is seen at temperatures above 37C. When purified inhibitor preparations are tested, complete reversal by phosphate at the highest temperatures is seen. Thus, the augmented inhibition in whole amniotic fluid depends on the combined effects of phosphate-sensitive and -insensitive inhibitors. Test organisms in the presence of partially purified inhibitor were not adversely affected at 4C, indicating that bacteria must be metabolically active to be inhibited. It is concluded that temperatures above 37C enhance the antibacterial effect. This may enhance protection during pyrexia.

Amniotic Fluid↗
PubMed1984

Influence of estrogen and normal flora on vaginal candidiasis in the rat.

The vaginal epithelium of randomly bred albino rats normally does not contain yeast. This study demonstrated that estrogen-primed, castrated rats could be colonized by Candida albicans following intravaginal challenge, whereas rats not treated with estrogen remained resistant to colonization. The bacteriologic conditions of the vagina were also studied in yeast-colonized and non-yeast-colonized rats. No evidence of bacterial interference with yeast colonization was obtained from this study since the vaginal flora of the estrogen-treated, yeast-colonized rats was more abundant and diverse than that of the non-estrogen-treated rats, which were resistant to yeast colonization. Scanning electron microscopy of the vaginal epithelium of yeast-colonized rats showed that C. albicans entered the mycelial phase during colonization of the vagina. It also appeared that the mycelia penetrate the cornified vaginal epithelial cells.

Adult↗
PubMed1984

Effects of postcesarean section febrile morbidity on subsequent fertility.

The records of 1319 patients undergoing cesarean section were evaluated to determine the relationship between postoperative febrile morbidity and fertility during the five years after the operation. Infection was significantly more common among patients undergoing primary as compared with repeat cesarean section and was three times more frequent among patients with membranes ruptured for 12 hours or more compared with those with membranes ruptured less than 12 hours. After correction of the data for voluntary infertility, neither postcesarean section endometritis nor pelvic cellulitis had a demonstrable effect on the rate of pregnancy during the five years after cesarean delivery, but pelvic abscess was associated with an apparent reduction in fertility as reflected by the frequency of pregnancy among these individuals, which was approximately half the rate observed in other infected and noninfected individuals in this study.

Abscess↗
PubMed1983

HLA-B27 haplotypes in family studies of ankylosing spondylitis.

Although HLA-B27 carries a high relative risk for development of ankylosing spondylitis (AS), most B27 positive individuals do not have spondylitis. One interpretation of this observation is that there may be 2 types of B27, 1 which carries the risk factor and 1 which does not. If this were the case, then with the help of markers closely linked to HLA-B, it might be possible to detect differences between the B27 haplotypes in AS patients and those in healthy probands. We studied 197 members of 18 families with known AS and 110 members of 19 families in which HLA-B27 was present without any known inflammatory spinal disease. HLA antigens A, B, and C and alleles of complement components C2, C4, and Factor B and glyoxalase-1 were determined in all cases. Detailed haplotypes were assigned and their associations with development of the disease were examined. We were unable to identify any distinct HLA-B27 haplotype associated with AS; 2 common haplotypes and several miscellaneous ones were found in both groups. Thinking that the development of AS might be influenced by the other, non-B27 haplotype, we analyzed this and found that there was no detectable influence. The data do not contradict the notion that B27 in whites is a single entity and is itself the susceptibility factor predisposing to the development of ankylosing spondylitis.

Adult↗
PubMed1983

Skin perfusion pressure measured by isotope washout in legs with arterial occlusive disease. Evaluation of different tracers, comparison to segmental systolic pressure, angiography and transcutaneous oxygen tension and variations during changes in systemic blood pressure.

The skin perfusion pressure (SPP) measured as the isotope washout cessation external pressure is valuable in selection of major amputation level. Five methodological investigations important to clinical use were carried out: (1) In five normal legs and 10 legs with arterial occlusive disease (AOD), 131I- -antipyrine (131I- -a.p.) was compared to Na(131I-) and 99Tcm-pertechnetate (99Tcm). The average SPP by 131I- -a.p. and by 131I- were approximately equal, 57.0 mmHg (range 18-93) compared to 56.3 mmHg (range 13-88) (P greater than 0.1). The average SPP by 99Tcm was just slightly higher, 60.3 mmHg (range 18-98) (P less than 0.02). The average washout constant for the three different tracers were approximately equal and correlated statistically significant with the SPP; (2) In 59 legs with AOD, segmental SPP was compared to segmental systolic blood pressures on the thigh, calf, ankle and first digit (strain gauge technique). The two different methods correlated statistically significant at all four levels, but the systolic blood pressures were higher than the SPP in particular in diabetic legs; (3) Angiograms in 35 legs with AOD showed that the SPP on the ankle was only consistently decreased in legs with arterial occlusions at two levels or more; (4) In 47 legs with AOD, the SPP on the calf or on the thigh was compared with transcutaneously measured pO2. The two different methods correlated statistically significant, but the scatter was great; (5) During induced variations in systemic blood pressure in seven patients (12 legs with AOD), the segmental SPP and the segmental systolic blood pressure were found on average to vary in proportion with intra-arterial mean and systolic pressure respectively; however, this proportional relationship was not valid for the individual leg. It is concluded that 99Tcm is as suitable as the 131I- -labelled tracers in estimating the SPP. The SPP is significantly correlated to skin blood flow, to systolic blood pressure, to tc pO2 and to angiographic findings. Correction of SPP for systemic blood pressure changes can be made in proportion with the measured variations in systemic mean blood pressure, but only for groups of patients.

Angiography↗
PubMed1983

Antibacterial activity in amniotic fluid from west virginia women.

Amniotic fluids from women in West Virginia were evaluated for the presence of antibacterial activity by a bioassay technique. 41% of 32 third trimester samples were inhibitory. Evaluation of additional test organisms emphasized differences in susceptibility of various bacterial strains; two isolates of Escherichia coli were found which were more sensitive to the phosphate-sensitive antibacterial system of amniotic fluid than in the initial test organism. The stated prevalence of inhibition may therefore be considered a conservative estimate.

Amniotic Fluid↗
PubMed1983

Host defence mechanisms in obstetrics and gynaecology.

The host possesses a variety of defence mechanisms which operate in concert to prevent infection or alter the course of an infective process. The majority of infectious diseases in the gynaecological patient arise at the mucosal surfaces. Mucosal surface pathogens must compete with organisms which are members of the normal flora and with local immunity. In the surgical patient infection usually arises as a result of disruption of anatomical barriers and implantation of organisms from the host's own flora in deeper tissues. Inflammatory and phagocytic reactions provide protection in this setting but their effectiveness may be perturbed by such features of the surgical procedure as leaving devitalized tissue or excessive amounts of suture in the operative site, or by inadequate haemostasis. The pregnant patient appears to have increased phagocytic activity and certain humoral antibacterial factors are also increased. She may have slight alterations in humoral immunity and evidence for altered cell-mediated immunity is provided. Further investigation of host defence in obstetrical and gynaecological patients may produce better methods for identifying defects in resistance to infectious processes and the development of the means for augmenting the natural defences of the host.

Bacterial Infections↗
PubMed1982

Incomplete manifestations of myotonic dystrophy in a large kinship in Labrador.

In a large kinship affected by myotonic dystrophy (MyD), 133 subjects, including 21 spouses, were examined independently by a neurologist and an ophthalmologist to determine the earliest identifying evidence of the disease. Assessment included tonometry, slit-lamp examination, facial measurements, and electromyography (EMG). Thirty-two subjects, all of whom had EMG characteristics of myotonia, were definitely affected. Low intraocular tensions were a more consistent finding than lens opacities; endocrine abnormalities were absent. Twenty-seven subjects had one to five features but lacked clinical or electrographic evidence of myotonia; they were designated as having a "partial syndrome." Signs most commonly found included weakness of the upper face, brachial hyporeflexia, low intraocular tensions, and the presence of sparse colored specks at the posterior poles of the lenses. All but 2 subjects (siblings) with the partial syndrome had a parent with either MyD or the partial syndrome. Linkage studies indicated that 7 subjects should not be carrying the gene, while others could be regarded as having a minor expression of MyD. In most persons with the partial syndrome, we could not predict whether typical MyD would develop later. Transmission of the disease may depend upon more than a single autosomal dominant gene, and nongenetic influences may also be important.

Adult↗
PubMed1982

On the bovine F blood group system.

The F system of three Danish cattle breeds as determined by four specific antisera is described. In the Jersey breed three alleles are recognised. In the Danish cattle breeds there was no indication of a null allele. However, the phenotypes observed in zebu cattle by means of four reagents suggest the presence of at least six alleles in the bovine F system. Furthermore, the data show that the factors V1 and V2 do not form a linear subtype system in all cattle breeds.

Alleles↗
PubMed1982

Left-right cortical asymmetries of regional cerebral blood flow during listening to words.

1. Regional cerebral blood flow (rCBF) was measured during rest and during listening to simple words. The xenon-133 intracarotid technique was used and results were obtained from 254 regions of seven right hemispheres and seven left hemispheres. The measurements were performed just after carotid angiography, carried out to exclude space occupying lesions. In all subjects the angiogram was normal. All were right handed. 2. Mean hemispheric blood flow of both left and right hemispheres increased 10% from the resting measurement during the listening task. This increase was due in part to activation of the entire hemisphere. The focal rCBF increases were localized to the superior part of the temporal regions, the prefrontal regions, the frontal eye fields, and the orbitofrontal regions. Significant asymmetries were found in particular in the superior temporal region with the left side showing a more widespread and intense increase, averaging 29% as compared to 18% on the right side. This left-sided dominance during verbal stimulation should be compared to the right-sided dominance of rCBF during nonverbal sound discrimination reported by Roland et al. (25, 26), who used precisely the same technique as in the present study.

Adult↗