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Biomedical subjects

U Johnson

Publications and source records attributed to U Johnson.

At least 19 recordsLinked to original sources
PubMed2006

Factors influencing factor VIII activity in frozen plasma.

BACKGROUNDS AND OBJECTIVES: Fresh frozen human plasma is an important raw material in the production of coagulation factor concentrates used in patients with haemorrhagic disorders. The aim of the study was to determine how the handling of plasma influences the recovery of coagulation factor VIII activity (FVIII:C), i.e. the influence of time between donation and freezing, of the freezing time and of the ice front velocity. We also studied a tentative eutectic point in human plasma. MATERIALS AND METHODS: Aliquots of plasma from 12 different donors were kept at room temperature for 2, 4 and 6 h before start of freezing. We achieved fast freezing with a freezer that blows cooled air at a high velocity on the plasma containers. Freezing times were 0.5, 1, 4 and 24 h. Temperature was registered continuously during freezing. Plasma and NaCl solutions were frozen slowly to investigate the eutectic point. RESULTS: Storage at room temperature for 6 h caused a small but statistically significant decrease in FVIII:C. Slow freezing with programmed freezing times of 4 and 24 h caused a more pronounced drop in FVIII:C as compared to that of 30 and 60 min. We found no eutectic point in plasma or in plasma with addition of 2 % (w/v) NaCl. CONCLUSION: For an optimal yield of FVIII, freezing should start within 4 h after plasma donation. We propose the use of the term 'ice front velocity' instead of 'freezing speed', taking into consideration that the volume and shape of plasma containers may differ. We found only a marginal loss of FVIII:C when the ice front velocity was 26 mm/h or faster, but a significant loss when it was 9 mm/h or slower. We recommend freezing times of 60 min or shorter. We were not able to demonstrate any eutectic point in human plasma. We therefore recommend that the term eutectic point should not be used as a reference temperature in guidelines on plasma handling.

Blood Coagulation Tests↗
PubMed2001

HLA-DR4 and salivary immunoglobulin A reactions to oral streptococci.

The aim of this study was to describe and compare salivary immunoglobulin A (IgA) antibody reactions to extracts of strains of three oral streptococci in human leukocyte antigen (HLA)-DR4-positive and -DR4-negative subjects. Whole paraffin-stimulated saliva samples were collected from 27 apparently healthy subjects. Previous HLA typing showed that 20 subjects were DR4 positive and 7 were DR4 negative. HLA-DRB1*04 subtyping was performed among the DR4-positive subjects. Whole-cell antigen extracts from Streptococcus mutans (KPSK 2), Streptococcus sobrinus (OMZ 65) and Streptococcus parasanguis (Nt 62) were separated in SDS-PAGE. The antigens were immunoblotted with diluted saliva (Western blot), scanned and analyzed in a computer system. All immunoblot bands were recorded in DR4-positive and DR4-negative saliva pools, and bands with an optical density >or=0.1 were selected for analysis in individual salivas. The DR4-negative subjects in general had more immunoblot bands and more distinct bands than did the DR4-positive subjects. A higher concentration of total IgA in saliva was correlated with more bands, especially to antigens separated from S. mutans. When the number of bands was calculated per IgA unit, significant differences were observed between DR4-positive and DR4-negative salivas. This was particularly seen for S. mutans and S. parasanguis. As the number of bands was analyzed in relation to DR4 subgroups, DRB1*04, there was a lower salivary IgA activity to S. mutans in the DRB1*0401 and *0404. The variable level of correlation previously demonstrated for S. mutans colonisation and serologically defined DR4 positive subjects might be explained by the heterogeneity in this group, and the relation should be sought on a subgroup level.

Antibodies, Bacterial↗
PubMed2001

Anorectal irradiation in pelvic radiotherapy: an assessment using in-vivo dosimetry.

The objectives of this study were to measure by in-vivo techniques the radiation doses received by the anorectum during pelvic radiotherapy and compare these with doses predicted by a GE TARGET treatment planning system. Nine patients with cancers of the prostate, bladder, cervix or uterus were planned with computed tomography (CT) using the TARGET system. A Scanditronix rectal probe containing five n-type photon-detecting diodes was placed in the anorectum during the planning CT scans. The probe position was standardized with the five diodes at 2 cm intervals from the anal verge. The probe diodes were calibrated for 10 MV photons. Doses were measured for each diode for two consecutive fractions in the first four patients and for five consecutive fractions in the remaining five. Thermoluminescent dosimeters were used initially to verify diode doses. The TARGET and diode measured doses were compared. In all patients diodes situated in the target volume were within 7% of predicted doses. This improved to 2.5% after measurement on five fractions. At the edges of the target volume, wide variability existed between measured and predicted doses (measured dose range -68% to +68% of predicted dose). Outside the target volume, considerable doses (up to 0.3 Gy per fraction) were measured in the anal canal, which were not predicted by TARGET. We conclude that TARGET planned doses are accurate within the confines of the target volume. The greatest variability was seen at the edges of the target volume, where dose can vary by 50% across a 1 cm distance in the anterior-posterior plane. TARGET does not account for scattered dose beyond the field edges and therefore underestimates the dose received by the anal canal.

Female↗
PubMed2000

Evaluation of compensation in breast radiotherapy: a planning study using multiple static fields.

PURPOSE: A method that uses electronic portal imaging to design intensity-modulated beams for compensation in breast radiotherapy was implemented using multiple static fields in a planning study. We present the results of the study to verify the algorithm, and to assess improvements to the dosimetry. METHODS AND MATERIALS: Fourteen patients were imaged with computed tomography (CT) and on a treatment unit using an electronic portal imager. The portal imaging data were used to design intensity-modulated beams to give an ideal dose distribution in the breast. These beams were implemented as multiple static fields added to standard wedged tangential fields. Planning of these treatments was performed on a commercial treatment planning system (Target 2, IGE Medical Systems, Slough, U.K.) using the CT data for each patient. Dose-volume histogram (DVH) analysis of the plans with and without multileaf collimator (MLC) compensation was carried out. This work has been used as the basis for a randomized clinical trial investigating whether improvements in dosimetry are correlated with the reduction of long-term side effects from breast radiotherapy. RESULTS: The planning analysis showed a mean increase in target volume receiving 95-105% of prescribed dose of 7.5% (range -0.8% to 15.9%) when additional MLC compensation was applied. There was no change to the minimum dose for all 14 patient data sets. The change in the volume of breast tissue receiving over 105% of prescribed dose, when applying MLC compensation, was between -1.4% and 11.9%, with positive numbers indicating an improvement. These effects showed a correlation with breast size; the larger the breast the greater the amount of improvement. CONCLUSIONS: The method for designing compensation for breast treatments using an electronic portal imager has been verified using planning on CT data for 14 patients. An improvement was seen in planning when applying MLC compensation and this effect was greater the larger the breast size.

Algorithms↗
PubMed1997

HLA DRB1* typing and cartilage oligomeric matrix protein (COMP) as predictors of joint destruction in recent-onset rheumatoid arthritis.

The carriage of a characteristic sequence of amino acids at position 67-72 in the third hypervariable region of the HLA DRB1 chain has been linked to susceptibility to rheumatoid arthritis (RA). Whether this epitope is also a predictor of more severe disease remains controversial. Cartilage oligomeric matrix protein (COMP) is a protein, the serum levels of which have been found to correlate with large joint destructive disease in previous work. In this paper, we compare DRB1* typing and serum COMP levels in a prospectively observed group of RA patients with or without early hip joint destruction. The COMP levels at study inclusion, median 11 months from onset of symptoms, were significantly higher in the patients with early hip joint destruction compared to the patients in the more benign group. There was no difference in the number of disease susceptibility-related epitopes between the groups. DRB1*04, in contrast, was found among 8/8 patients with hip destruction, but also in 5/8 more benign cases. We conclude that in this type of RA patient, COMP serum levels are more informative predictors of aggressive disease than HLA DRB1* typing.

Alleles↗
PubMed1997

Coping strategies among long-term injured competitive athletes. A study of 81 men and women in team and individual sports.

Differences in personality, mood and coping ability between athletes of a high competitive level with long-term injuries (n = 81), with a mean age of 24.4 years, and a matched non-injured group (n = 64), with a mean age of 24.2 years, were investigated. Three self-rating scales were employed: mood adjective check-list, general coping questionnaire and Karolinska scales of personality. Although no differences in basic personality traits were found, being injured was found to result in a depressed mood state and in the activation of coping strategies directed at receiving help. Comparisons were made between injured male and female athletes as well as between team-sport and individual-sport athletes. Women were found to become more anxious and tense and to have a stronger inclination to use emotion-focused coping strategies. Team-sport athletes were found to cope more in terms of 'passive acceptance' of help from others, whereas individual athletes were found to activate 'problem-solving' strategies in face of a stressor. The results suggest that social aspects of rehabilitative work are important and support the concept that rehabilitative work with long-term injured athletes should be individualized to be maximally effective. They also support the usefulness of cognitive models of the injured athlete's experience of being long-term injured. Such models, however, do not account for differences between the sexes or between individual and team athletes.

Adaptation, Psychological↗
PubMed1997

HLA-DR4 and number of mutans streptococci in saliva among dental students and staff.

Our aim was to corroborate previous findings that HLA-DR4 carriers are characterized by higher levels of mutans streptococci in saliva than are individuals expressing other HLA-DR types. Of 68 subjects (dental students, staff, and faculty) who were sampled for salivary counts of mutants streptococci, 13 subjects with the lowest counts of mutans streptococci and 15 subjects with the highest counts were selected for HLA-typing. Of the 13 who expressed HLA-DR4, 8 were heavily colonized by mutants streptococci. Although a trend towards a relationship was found between HLA-DR4 carriage and high levels of mutans streptococci, it was not statistically significant. In this selected population, knowledge of how to minimize the risk of caries and mutans streptococci level may have influenced the results.

Adult↗
PubMed1996

Development of radiographic damage during the first 5-6 yr of rheumatoid arthritis. A prospective follow-up study of a Swedish cohort.

The objective of this study was to describe the development of radiographic damage in patients with RA and to search for predictors of radiographic progression over 5 yr. One hundred and thirteen patients, 75 female and 38 male, mean age 53 yr, with definite RA and mean disease duration of 11.4 months, were followed prospectively for 5 yr at an out-patient clinic. Radiographs of the hands and feet were performed annually, and evaluated according to Larsen. The predictive value of demographic, clinical and laboratory variables at study start was evaluated. A stepwise logistic regression model was applied. We found that radiological joint damage occurred early and was significantly progressive during the 5 study years. The rate of progression was most prominent during the first 2 yr. At study start, 53% of the patients had no detectable erosions, but only 11% remained non-erosive. Twenty-six per cent of the patients with the initial presence of erosions did not progress substantially and needed no aggressive therapy. High joint damage progression during the first year, female gender and high baseline ESR could predict 57% of the patients with high total radiographic progression. Age, disease duration, rheumatoid factor, genetic factors, active joint count and the presence of erosions at study start had no predictive value.

Antirheumatic Agents↗
PubMed1996

Associations of HLA-DRB and -DQB genes with two and five year outcome in rheumatoid arthritis.

OBJECTIVE: To evaluate the clinical usefulness of genomic HLA typing during the first five years of established rheumatoid arthritis (RA). METHODS: The HLA-DRB and -DQB alleles were determined by restriction length polymorphisms and polymerase chain reaction amplification with sequence specific primers in 99 Swedish patients with RA. Clinical features after two and five years disease duration were related to the genetic pattern. Seventy four patients were seropositive, 25 had nodules, 90 developed erosions, and 15 required joint replacements. Twelve patients were in remission after five years. Disability was assessed by health assessment questionnaire, and radiographic damage in hands and feet by the Larsen method. RESULTS: Eighty seven per cent of the patients carried the conserved third hypervariable region sequence (HVR3), 32% had DRB1*04 on one allele, and 26% had DRB1*04 on both alleles (all frequencies significantly greater than in controls). Frequencies of DRB1*04 associated DQB*0301 and *0302 were normal. Patients carrying DRB1*04 on both alleles tended to have more radiographic changes after two years, but this difference had diminished after five years. Disability did not vary with regard to the genotype. Homozygous HVR3 patients had about three times greater risk of undergoing joint replacement. Homozygosity for HVR3 and presence of DQB*0302 both tended to be associated with erosive disease. CONCLUSIONS: We confirmed a strong association of disease with the presence of the shared epitope on one or two alleles. However, genotype was not strongly associated with disease severity after two and five years disease duration, and thus the value of genomic typing to select patients for early aggressive therapy is questionable.

Adult↗
PubMed1994

HLA frequency in patients with chronic secretory otitis media.

It is well established that relationships exist between the frequencies of certain HLA antigens and various disease entities. In an earlier study we found a significant correlation between the frequency of HLA-A2 and HLA-A3 and recurrent acute otitis media (rAOM). Of 34 HLA antigens analysed, HLA-A2 occurred in 80.0% and HLA-A3 in only 11.1% of children with rAOM as compared to 55.9% and 27.5%, respectively, in healthy controls. In the present study we investigated the frequencies of the same 34 HLA antigens in 40 children who had been regularly controlled at our clinic for chronic secretory otitis media (SOM) for at least 6 years. HLA-A2 was found in 52.0% (21/40) and HLA-A3 in 27.5% (11/40) of these children, figures on a par with those of healthy controls. The HLA-A2 frequency was significantly lower in chronic SOM patients than in rAOM children. Some other non-significant differences were also found between these two groups. The results indicate a difference in hereditary influence on the pathogenesis of rAOM and that of chronic SOM.

Acute Disease↗
PubMed1993

HLA-DR antigens, Gm allotypes and antiallotypes in early rheumatoid arthritis--their relation to disease progression.

OBJECTIVE: Evaluation of the prognostic value of immunogenetic markers in early rheumatoid arthritis (RA). METHODS: Ninety-nine patients with definite RA and disease duration 24 months or less were followed with standardized assessment. Disability was assessed by the HAQ index and radiographic changes in hands and feet by the Larsen method. The frequencies of HLA-DR genes were determined by serological typing, Gm allotype distribution by classical hemagglutination inhibition test, and occurrence of anti-Gm allotypes by use of anti-Rh coats. The immunogenetic findings were related to disease severity after 2 years' followup. RESULTS: Functional capacity was well preserved, disease activity was less, but radiographic changes in hands and feet had increased considerably at study finish. A group of 13 patients had developed rapidly progressive changes of hip and/or shoulder joints, all requiring arthroplasty. There was a significantly increased frequency of HLA-DR4. Twenty-seven of the 68 HLA-DR4 positive patients were putatively homozygous. HLA-DR4 was not related to disability or to severe small joint destruction. However, progressive large joint damage was significantly more prevalent in homozygous patients (p < 0.01). Gm allotype distribution was normal and not related to clinical findings. Anti-Gm antibodies were common and frequently specific for nonhost Gm allotype. Fifty-six patients carried anti-G1m(a), and occurrence of this antibody was significantly associated with radiographic progression of small joints (p = 0.01), presence of nodules (p < 0.01) and number of active joints (p = 0.001). CONCLUSION: Immunogenetic markers aided in identifying patients with early RA with more severe disease.

Adult↗
PubMed1992

HLA antigens and recurrent acute otitis media.

The frequencies of a number of HLA antigens were investigated in 45 individuals with clinical recurrent acute otitis media (rAOM), defined as six or more episodes of AOM during a 12-month period, and were compared to those in a control group from the same district. HLA-A2 was found to occur in 80% of the rAOM group, as compared to 55.9% of controls (p less than 0.01). HLA-A3 antigen occurred in only 11.1% of the rAOM group in contrast to 27.5% of controls (p less than 0.05). Among 22 prospectively followed children without any AOM during their first 3 years of life, the frequencies of HLA-A2 and HLA-A3 antigens were comparable with those among controls.

Acute Disease↗
PubMed1991

HLA frequency in patients with recurrent acute otitis media.

Clinical data suggest the involvement of hereditary factors in children susceptible to recurrent acute otitis media. That relationships of varying degree exist between the frequencies of certain HLA antigens and various disease entities is well established. In the present study, we investigated the frequencies of a number of HLA antigens in 45 patients with clinical recurrent acute otitis media and compared these frequencies with those in a control group from the same district. The HLA-A2 antigen occurred in 80% (36/45) of the group with recurrent acute otitis media, as compared with 56% of controls. Of a subgroup of 11 children with recurrent acute otitis media who were prospectively followed up, 10 (91%) were HLA-A2 positive. The HLA-A3 antigen occurred in only 11% (5/45) of the group with recurrent acute otitis media as a whole (n = 45) in comparison with 28% of controls. Among 22 prospectively followed up children without any episode of acute otitis media during the first 3 years of life, the frequency of HLA-A2 was 45% (10/22) and that of HLA-A3, 32% (7/22). The results indicate the existence of a relationship between recurrent acute otitis media and the HLA-A locus, suggesting the involvement of genetic factors in the disease.

Acute Disease↗
PubMed1991

Human leukocyte antigens in relation to colonization by mutans streptococci in the oral cavity.

Mutans streptococci are well established as caries-inducing microorganisms in man. Most humans carry the bacteria, but in highly different numbers. This cannot be explained by environmental factors only. The aim of this study was to investigate a possible association between levels of colonization by mutans streptococci and the presence of certain B and DR human leukocyte antigens (HLA). Altogether, 170 subjects who had their HLA antigens determined (76 renal transplant patients and 94 healthy blood donors) were selected for the investigation. Paraffin-stimulated saliva samples were taken using the wooden spatula method with subsequent cultivation of mutans streptococci on mitis salivarius bacitracin agar plates. An association between the absence of HLA-DR 4 antigens and low, or undetectable, levels of mutans streptococci was found. This was statistically significant for the immunosuppressed renal transplant subjects. The same trend was observed among the healthy blood donors.

Adult↗
PubMed1991

Alloimmunization to human immunoglobulin genetic markers is frequent in early rheumatoid arthritis.

HLA and Gm allotypes of 99 consecutive Swedish patients with rheumatoid arthritis were determined. Ninety-two of the 198 haplotypes contained DR4, a significant increase. The patients' sera from 3 different occasions were studied for anti-immunoglobulin profile as judged by 6 selected anti-Rh coats, 4 of them being monoclonal anti-Ds restricted as to allotype. Ninety-two of the patients were reactive with a polyclonal anti-Rh Ri as against 10 with the monoclonal carrying the G1m(f) allotype. Antibodies to Ig coats carrying defined allotypes were more frequently observed in patients not carrying the allotype in question than in those individuals possessing it. The difference was significant or highly significant as regards presence/absence of G1m(a), G3m(b) and G3m(g), respectively. Anti-G1m(a) and anti-G3m(g) cooccurred in 17 of the patients. Results consistent with presence/absence of particular anti-immunoglobulins at the 3 examinations were observed in 74 of the patients. Gm allotypes or antiallotypes were not statistically related with DR4 status. In conclusion, alloimmunization to Gm markers frequently occurs in early rheumatoid arthritis.

Adult↗