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Biomedical subjects

A Gustafsson

Publications and source records attributed to A Gustafsson.

At least 91 records · Page 5Linked to original sources
PubMed1995

Human papillomavirus infection is transient in young women: a population-based cohort study.

The prevalence of human papillomavirus (HPV) infection in cervical cell scrapes from a cohort of 276 young women was determined by a general two-step polymerase chain reaction. HPV infection fluctuated among young women during a 2-year interval. The total prevalence of HPV infection decreased from 21% to 8.3%. The most prevalent HPV types at enrollment were HPV-16 (3.3%) and HPV-6 (2.9%). At follow-up, the most common type was HPV-16 (2.9%), while no HPV-6 was detected. In 2 women only, the same HPV type persisted. Regression of HPV infection was found in 80% of the women. A new HPV type-specific infection was detected in 7.2% of the women and was independently associated with a new sex partner or an abnormal smear since enrollment.

Adult↗
PubMed1995

Lower protein concentration in GCF from patients with periodontitis: an indicator of host-specific inflammatory reaction.

To study the local inflammatory reaction associated with gingivitis and periodontitis, the protein concentrations were measured in gingival crevicular fluid (GCF) from 3 types of site: (i) inflamed sites in patients with gingivitis alone; (ii) inflamed sites with or (iii) without tissue destruction in patients with periodontitis. The GCF was sampled with paper strips and the protein concentration was measured with the Bradford protein assay. Higher protein concentrations in GCF were found at inflamed sites in patients with gingivitis alone than at clinically similar sites without tissue destruction in patients with periodontitis. In contrast, the sites with various degrees of disease in the same periodontitis patient showed the same protein concentrations. These discrepancies indicate that the local inflammatory reaction in the gingiva is host- and not site-specific, i.e., the tissue destruction in periodontitis reflects a specific host response.

Adult↗
PubMed1995

Simultaneous optimization of dynamic multileaf collimation and scanning patterns or compensation filters using a generalized pencil beam algorithm.

A very flexible iterative method for simultaneous optimization of dynamic multileaf collimation, scanning patterns and compensation filters has been developed. The algorithm can account for and optimize almost all the degrees of freedom available in a modern radiation therapy clinic. The method has been implemented for three dimensional treatment planning. The algorithm has been tested for a number of cases where both traditional wedge filters and block collimators, and modern equipment such as scanned beams and multileaf collimators are available. It is shown that the algorithm can improve heavily on traditional uniform dose plans with respect to the probability of achieving tumor control without causing severe complications (P+) simply by finding the optimal beam weights and block collimator settings. By allowing more complex equipment to deliver the dose and by accounting for their increased flexibility during the optimization, the dose plan can be substantially improved with respect to the applied objective functions. It is demonstrated that flexible lateral collimation combined with compensators or scanned beams in most cases allow close to optimal dose delivery. Here both the calculation time and the amount of primary computer memory needed has been reduced by performing the dose calculations in a cone beam coordinate system allowing the use of approximately spatially invariant energy deposition kernels. A typical calculation time for optimization of a two-field technique in a three dimensional volume is about 20 s per iteration step on a Hewlett-Packard 735 workstation. A well converged solution is normally obtained within about 50-100 iterations or within 15-30 min.

Algorithms↗
PubMed1994

Altered relation between granulocyte elastase and alpha-2-macroglobulin in gingival crevicular fluid from sites with periodontal destruction.

Granulocyte elastase activity and alpha-2-macroglobulin (alpha-2-MG) were studied in the gingival crevicular fluid (GCF) from 3 categories of sites in 6 patients with gingivitis and 6 patients with periodontitis. 6 inflamed sites in each gingivitis patient were sampled on paper strips and 12 sites, 6 with and 6 without attachment loss and periodontal pockets, were selected in each periodontitis patient. To avoid the influence of increase GCF volume from deep pockets, the elastase activity and the alpha-2-MG were calculated per microliters of GCF. The proteolytic activity of elastase was measured with a low molecular weight substrate and the antiprotease, alpha-2-MG, with ELISA. The measured activity could be ascribed to elastase that had been released into the gingival tissues and into the GCF prior to sampling. In the periodontitis patients, the sites with tissue destruction had a significantly higher elastase activity per site and per microliters GCF and a significantly lower alpha-2-MG per microliters than the 2 other categories of sites without tissue destruction. The destructive inflammation seems to be associated with increased release of elastase, either from more numerous or from more active granulocytes and with an increased proteolytic consumption of the inhibitor accompanied by the fast elimination of the protease-inhibitor-complex. In conclusion, the study shows a strong relationship between elastase activity and tissue destruction, a finding that supports the pathogenic theory of an involvement of granulocytes and their proteolytic enzymes in the mechanism of periodontal destruction.

Adult↗
PubMed1994

Elastase and lactoferrin in gingival crevicular fluid: possible indicators of a granulocyte-associated specific host response.

Periodontitis affects a limited number of susceptible humans. The aim of this study was to determine whether there is a difference in the inflammatory reaction between patients with gingivitis and those with periodontitis. For this purpose the levels of elastase and lactoferrin were measured in gingival crevicular fluid (GCF) from three types of sites: i) inflamed sites in patients with gingivitis alone, inflamed sites both ii) with and iii) without tissue destruction in patients with periodontitis. Elastase activity, measured with a chromogenic substrate was significantly higher in the two types of sites in periodontitis patients. Lactoferrin levels, measured with ELISA were the same in the three types of sites. In vitro activation of granulocytes from healthy volunteers with Fc-receptor stimulation showed that the entire release of lactoferrin occurred immediately. In contrast, elastase release was time-dependent and continued throughout the experiment. Thus, the degranulation of the specific (lactoferrin) and azurophil granule (elastase) are under separate control and the two parameters can be combined in a ratio in order to characterize the granulocytes of a given patient. Assuming an immediate release of lactoferrin from the activated granulocytes in vivo, similar amounts of lactoferrin in the three types of sites can be regarded as reflecting similar numbers of granulocytes in the three types of sites. Consequently, a higher elastase activity in GCF from patients with periodontitis indicates a higher rate of release from the cells per se and a granulocyte-associated specific host response.

Adult↗
PubMed1994

A generalized pencil beam algorithm for optimization of radiation therapy.

An iterative pencil beam algorithm for optimization of multidimensional radiation therapy dose plans has been developed. The algorithm allows the use of both physical and radiobiological treatment objective functions and allows arbitrary sampling such as straight Cartesian grids with linear or nonlinear sampling functions or random sampling. The algorithm can account for and optimally combine almost all the degrees of freedom at an advanced radiotherapy clinic, such as different beam modalities and spectra, beam directions, beam fluence distributions, and time-dose fractionations. The algorithm allows for external charged and neutral beams as well as intracavitary and interstitial sources to be optimally combined. A quantity termed the generalized fluence vector is introduced, combining fluences and energy fluences from external beams as well as the radiation source densities of intracavitary and interstitial sources or external source distributions. The positivity constraint on the generalized fluence can therefore be applied directly during the optimization procedure. The convergence properties and the required iteration time of the algorithm are discussed. Several examples with combinations of photon and electron beams of different energies and directions of incidence are presented. The optimization has been made with the treatment objective to maximize the probability of achieving tumor control without causing severe complications in healthy normal tissues.

Algorithms↗
PubMed1994

Prognosis of patients with bilateral carcinoma of the breast.

Ninety-five patients with bilateral carcinoma of the breast treated with mastectomy (60 patients), conservation of the breast (17 patients), or both (18 patients), were studied. Cumulative five year local control rates for the 138 mastectomies was 94 percent and for the 52 breast conservations, 90 percent. Distant metastases appeared in one-third of the patients but one-half of them occurred beyond 60 months. Cumulative five year distant disease-free survival rate measured from treatment for the second carcinoma was 74 percent. Second carcinomas were diagnosed at significantly earlier stage than first carcinomas--28 percent of first carcinomas were stage I compared with 43 percent of second carcinomas (p < 0.05). Distant recurrence-free survival rates for metachronous carcinomas were better then for synchronous carcinomas, but this difference can be attributed to earlier overall staging of metachronous carcinomas. The interval between the diagnosis of first and second carcinomas had a profound effect on outcome for second carcinomas--cumulative five year distant recurrence-free survival rate of patients with second carcinomas diagnosed within five years was 58 percent compared with 95 percent for patients diagnosed more than five years after the first carcinoma.

Breast Neoplasms↗
PubMed1993

The clinical value of different treatment objectives and degrees of freedom in radiation therapy optimization.

With inverse radiation therapy planning methods, both biological and physical objective functions can be used to perform the optimization. A biological objective function, namely the probability of achieving tumor control without causing severe complications in normal tissues, P+, has been used to evaluate six different optimization methods. All six methods have been tested on two different clinically relevant treatment geometries. The results show that optimization with a physical objective function which gives the best possible agreement with the desired dose distribution in the least squares sense, may result in severe loss of complication-free tumor control due to insufficient consideration of the organs at risk. It is generally better to use a physical objective function which minimizes the over-dosage when the desired dose distribution can not be exactly reproduced. In all cases the use of physical objective functions results in a lower probability of controlling the tumor without causing severe normal tissue reactions than if the biological objective function, P+, is used. However, the results also show the importance of accurately accounting for beam divergence, dose build-up, beam attenuation, and lateral scatter during the optimization procedure, particularly when the biological objective function is used. The loss in P+ by assuming that all energy deposition kernels are identical and that all the constituent beams have fixed relative weights can be 15% or more. When lateral scatter is not accounted for during the optimization, serious injury to organs at risk may result. This problem is specially severe for organs that are partly or totally encapsulated by the target volume. For superficial target volumes accurate consideration of the dose build-up of the incident pencil beams is fundamental.

Humans↗
PubMed1993

Improved maintenance of plaque control by electrical toothbrushing in periodontitis patients with low compliance.

Patients showing low compliance with oral hygiene were selected from a population of patients referred for specialist treatment of periodontitis. The patients selected did not show an acceptable plaque control in spite of a prolonged training period. Plaque around 40% of the tooth surfaces, documented over a period of 4 to 40 months of frequent information and instructions, was found in 10 patients around the age of 40 years with a marked overrepresentation of men. Substitution of the ordinary toothbrush with an electrical toothbrush using the same working principles, resulted in a decreased plaque score of approximately 10% maintained over a considerable time period (12-36 months). A common complaint among the patients was that the oral hygiene procedures were time-consuming and cumbersome. They considered the electrical toothbrush as simple and time saving. Even if these possibilities were not investigated, merely the patients' positive attitude may have made the efforts of tooth cleaning including the proximal cleaning more tolerable, thus improving the compliance. Contributing to the improved compliance might also have been the electrical toothbrush per se. The cleaning technique allows the patient to concentrate on aiming the bristles at the gingival sulcus, while the brush makes the movements. In conclusion, it should be worthwhile recommending an electrical toothbrush with simple working technique to low compliant periodontitis patients restricting the recalls to twice a year.

Adult↗
PubMed1992

Granulocyte elastase in gingival crevicular fluid. A possible discriminator between gingivitis and periodontitis.

The granulocyte elastase activity and the immuno-reactive (antigenic) granulocyte elastase of gingival crevicular fluid (GCF) were studied in 16 periodontitis patients and in 10 gingivitis patients. The elastase activity was measured with a low molecular weight substrate specific for granulocyte elastase. The antigenic elastase was determined with specific antibodies against granulocyte elastase. Intracrevicular sampling of GCF with paper strips for 30 s seemed to provide representative values of elastase. The elastase activity correlated with probing depth and attachment loss and appeared to be a measure of the degree of tissue destruction. Antigenic elastase represents the number of granulocytes in GCF and should thus be related to the degree of inflammation. The periodontitis patients and the gingivitis patients both had a similar degree of inflammation as measured by antigenic elastase per microliter GCF and gingival index. The elastase activity per microliter GCF, however, was higher in the periodontitis group. Elevated granulocyte elastase activity in GCF seems to be independent of inflammation and could thus be an indicator of patients at risk for periodontitis.

Adult↗
PubMed1992

Comparison of a one-step and a two-step polymerase chain reaction with degenerate general primers in a population-based study of human papillomavirus infection in young Swedish women.

The prevalence of human papillomavirus (HPV) infection in cervical cell scrapes from young women was determined by polymerase chain reaction (PCR) by using general primer pairs localized within the L1 region. With a one-step general PCR, 5.9% (35 of 590) of young women in a population-based study were found to contain HPV DNA. The proportion of HPV-positive women increased with age, from 1.4% (1 of 69) among women aged 19 years to 9.2% (13 of 142) among women aged 25 years. Among the cervical scrapes from women with normal cytology, 5.6% (30 of 539) harbored HPV DNA. A total of 5 of 19 (26.3%) of the women with pathological signs were positive for HPV DNA. By a two-step PCR, using nested general primers, 20.3% (118 of 581) of all women were shown to contain HPV DNA. The proportion of HPV-positive women also increased with age, from 17.4% (12 of 69) among women aged 19 years to 31.9% (43 of 135) among women aged 25 years, when the two-step PCR was used. Some 19.2% (102 of 530) of cervical scrapes from women with normal cytology contained HPV DNA. Among the women with pathological signs, 16 of 19 (84.2%) were positive for HPV DNA. The HPV DNA-positive specimens were demonstrated to contain HPV type 6, 11, 16, 18, 31, 33, 35, 39, 40, 45, 55, or 56. The most prevalent HPV types were 6 (2.0%) and 16 (2.7%). More than one type was found in 16 specimens. Sixty HPV-positive samples could not be typed.

Adult↗
PubMed1992

Improved detection of HIV-2 DNA in clinical samples using a nested primer-based polymerase chain reaction.

A two-step polymerase chain reaction (PCR), with four double (nested) primer pairs, used for the detection of HIV-2 in clinical samples is described. With these four nested primer pairs we could detect HIV-2 DNA in 17 of 17 virus isolates and in blood mononuclear cell samples from 31 of 37 (83.7%) seropositive individuals after ethidium bromide staining of the amplified DNA. The nested primer PCR was also compared with a single primer pair-based PCR followed by hybridization. The sensitivities of the two methods were almost equal, but the nested primer PCR offered obvious technical advantages.

Adolescent↗
PubMed1991

Selection of primers of optimal sensitivity for the detection of HIV-1 from Africa and Europe by polymerase chain reaction.

In order to facilitate the detection of integrated HIV-1 proviral DNA from African as well as European patients, four new primer pairs for use in the polymerase chain reaction (PCR), localised in the gag, pol, vif and env genes of HIV-1, were constructed. The primer pairs were compared to all accessible HIV-1 sequences from African and European isolates and to some of the earlier published and most commonly used primer pairs. HIV-1 DNA was detected in blood drawn from 13 out of 13 individuals infected in Africa, in three out of three Tanzanian HIV-1 isolates and in three out of three asymptomatic Swedes infected in Europe. The new selection of primer pairs can be used as an alternative to enhance the detection of HIV-1 of different origins.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Enteral nutrition and the function of the intestinal microflora in healthy adults.

An oral feeding formula was given to 5 healthy volunteers for 8 days. Faecal samples were collected before, during and after the feeding period. The effect of enteral nutrition (EN) on the following seven intestinal microflora-associated characteristics (MACs) was studied: formation of urobilinogen, coprostanol and deoxycholic acid, degradation of mucin and beta-aspartylglycine, faecal tryptic activity, and production of short-chain fatty acids (SCFAs). None of the microbial functions studied were lost during the study. The urobilinogen level increased during EN (P < 0.05) but it seems reasonable to assume that this was a concentration effect due to a decrease in stool mass. The concentration of SCFAs decreased during EN (P < 0.05) and this reflects the absence of dietary fibre in the feed used.

Journal Article↗
PubMed1990

Antibody response after intradermal administration of recombinant hepatitis B vaccine in children.

Intradermal vaccination with recombinant hepatitis B vaccine was performed in 33 children (mean age 3.3 years). A 2 micrograms dose was given at 0, 1 and 6 months and antibody responses were determined 20 months after the initial dose. In 32/33 children, serum antibodies to HBs were demonstrated, with a geometric mean level of 26.5 IU/l, and 24 children (73%) had anti-HBs levels greater than or equal to 10 IU/l. The results indicate that intradermal vaccination with recombinant hepatitis B vaccine may be an alternative for vaccination of small children.

Child Day Care Centers↗