Biomedical subjects
Publications and source records attributed to M Karlsson.
By exposure measurements in an alcohol-water mixture simulating breast tissue, the absorbed dose, and dose distribution in the breast at the radiation qualities commonly used in mammary radiography have been calculated. The absorbed doses for different recording media have been compared at those radiation qualities which result in similar image qualities in the different recording media.
Anileridine and pethidine were established by gas and thin layer chromatography and mass spectroscopy. In the mass spectrum the main peak of anileridine is found at m/e 246 and that of pethidine at m/e 71. The determination was made by gas chromatography from the blood, urine, liver, muscle and stomach contents.
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Peripheral lymphocytes from patients with urinary bladder carcinoma and controls have been separated on the basis of rosette formation with sheep erythrocytes. The fractions were tested for tumor-specific cytotoxicity. The E rosette-forming cells of purity 90% respond well in PHA-induced cytotoxicity but are totally inactive in the tumor assay. The non-E rosette-forming cells (purity 91%) give enhanced activity in the tumor-specific cytotoxicity as well as in antibody-mediated target cell lysis in a model system. These data support the notion that the effector cells in cell-mediated immunity to carcinoma of the urinary bladder are members of the nonthymus-derived population of peripheral lymphocytes.
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A fully automated method for quantitation of levosimendan, (R)-(-)-[[4-(1,4,5,6-tetrahydro-4-methyl-6-oxo-3-pyridazinyl) phenyl]hydrazono]propanedinitrile, in human plasma is described. The method involves on-line dialysis of the samples, trace enrichment of the dialysates, and reversed-phase high-performance liquid chromatography with UV detection at 380 nm. An internal standard was used to compensate for variations in the dialysis rate caused by temperature fluctuations. The precision and accuracy of the method were good. The between-day variation (RSD) was 2.7% at a plasma concentration of 15 ng/mL and 1.7% at 450 ng/mL. The limit of quantitation was 5 ng/mL with an RSD of 4.0%. The completion time of the assay was 19 min.
The hemispheric proximal isovelocity surface area method for quantification of mitral regurgitant flow (i.e., Qc = 2 pi r2v), where 2 pi r2 is the surface area and v is the velocity at radius r, was investigated as distance from the orifice was increased. Computer simulations and steady flow model experiments were performed for orifices of 4, 6, and 8 mm. Flow rates derived from the centerline velocity and hemispheric assumption were compared with true flow rates. Proximal isovelocity surface area shape varied as distance from each orifice was increased and could only be approximated from the hemispheric equation when a certain distance was exceeded: > 7, > 10, and > 12 mm for the 4, 6, and 8 mm orifices, respectively. Prediction of relative error showed that the best radial zone at which to make measurements was 5 to 9, 6 to 14 and 7 to 17 mm for the 4, 6, and 8 mm orifices, respectively. Although effects of a nonhemispheric shape could be compensated for by use of a correction factor, a radius of 8 to 9 mm can be recommended without the use of a correction factor over all orifices studied if a deviation in calculated as compared with true flow of 15% is considered acceptable. These measurements therefore have implications for the technique in clinical practice.
The purpose of this study was to investigate the prognostic importance of clinical and histopathologic factors, including malignancy grading systems (MGS), partial index (PI), invasive front grading (IFG), and microvessel density. A complete geographic series of 172 early stage (FIGO I-II) cervical carcinomas treated by Wertheim-Meigs surgery during the period 1965-1990 was studied. The patients were followed up for at least 10 years. Significant prognostic factors for disease-free survival were lymph node status (P < 0.0000001), radical surgical margins (P = 0.00003), and tumor size (P = 0.008). In a multivariate Cox analysis it was shown that lymph node status was the single most important prognostic factor with regard to disease-free survival. The total MGS and the PI scores were highly significantly (P = 0.0001) associated with pelvic lymph node metastases and disease-free survival rate in squamous cell carcinomas. The MGS and the PI systems were superior to the IFG system in predicting lymph node metastases. The total IFG score was also a statistically highly significant (P = 0.003) prognostic factor with regard to disease-free survival in both univariate and multivariate analyses. Microvessel density was a nonsignificant prognostic factor. There was a highly significant (P = 0.002) association between vascular space invasion of tumor cells and the presence of lymph node metastases. In conclusion, histopathologic malignancy grading systems provide valuable prognostic information in patients with early stage squamous cell carcinomas of the uterine cervix.
This study evaluated the prognostic importance of a new grading system focusing on the invasive tumor front, DNA profile, and the proliferation marker MIB-1. A complete geographic series of 172 women treated with radical hysterectomy (Wertheim-Meigs) for FIGO stage I-II cervical carcinomas was the target population. The analyses were performed on 141 (82%) squamous cell carcinomas of the complete series. During the period of observation (mean 222 months), 17 recurrences (12.1%) were encountered. Prognostic factors for disease-free survival were lymph node status (P < 0.000001), radical surgical margins (P = 0.00004), and tumor size (P = 0.002). The complete score of the invasive front grading system (IFG), and the individual scores of two variables-pattern of invasion and host response-were all significantly (P = 0.002, P = 0.007, P = 0.0001) associated with pelvic lymph node metastases. Host response was the single most important factor in the IFG system, and it was superior to the complete score in predicting lymph node metastases. The total IFG score was also a significant (P = 0.003) prognostic factor for disease-free survival. DNA ploidy, S-phase fraction, and MIB-1 expression were nonsignificant factors in predicting pelvic lymph node metastases and disease-free survival of the patient. The IFG in the original or modified versions could predict low- and high-risk groups of tumors and therefore be of value in treatment planning for these patients.
The objective of this study was to assess the value of p53, bcl-2, and p21(WAF1/CIP1) immunoreactivity as predictors of pelvic lymph node metastases (LNM), recurrences, and death due to the disease in early stage (FIGO I-II) cervical carcinomas. FIGO stage, type of histopathology, and tumor grade were also evaluated in this series of patients treated by radical hysterectomy (Wertheim-Meigs) between 1965 and 1990. A total of 172 patients were included. A tumor was regarded as positive when more than 30% of the neoplastic cells exhibited immunoreactivity. Positive immunostaining was found in 8.9% for p53, in 43.5% for bcl-2, and in 25.0% for p21(WAF1/CIP1). None of them was able to predict LNM or clinical outcome. Presence of LNM, tumor recurrence, and death from disease were significantly associated with the FIGO stage (P = 0.014, P = 0.009, and P = 0.001, respectively). The 5-year cancer-specific survival rate was 91.6% and the overall survival rate was 90.5%. It was concluded that immunohistochemically detected p53, bcl-2, and p21(WAF1/CIP1) appeared to be of no predictive value with regard to LNM, tumor recurrences, or long-term survival in early cervical carcinomas.
Bio-heat equations (BHEs) are necessary for predicting tissue temperature during thermal treatment. For some applications, however, existing BHEs describe the convective heat transfer by the blood perfusion in an unsatisfactory way. The two most frequently used equations, the BHE of Pennes and the k(eff) equation, use for instance either a heat sink or an increased thermal conductivity in order to account for the blood perfusion. Both these methods introduce modelling inaccuracies when applied to an ordinary tissue continuum with a variety of vessel sizes. In this study, a hybrid equation that includes both an increased thermal conductivity and a heat sink is proposed. The equation relies on the different thermal characteristics associated with small, intermediate and large sized vessels together with the possibilities of modelling these vessels using an effective thermal conductivity in combination with a heat sink. The relative importance of these two terms is accounted for by a coefficient beta. For beta = 0 and beta = 1, the hybrid equation coincides with the BHE of Pennes and the k(eff) equation, respectively. The hybrid equation is used here in order to simulate temperature fields for two tissue models. The temperature field is greatly affected by beta, and the effect is dependent on, e.g. the boundary conditions and the power supply. Since the BHE of Pennes and the k(eff) equation are included in the hybrid equation, this equation can also be useful for evaluation of the included equations. Both these heat transfer modes are included in the proposed equation, which enables implementation in standard thermal simulation programmes.
Microdialysis was investigated as a tool for the determination of the extracellular concentration of the pigment metabolite 5-S-cysteinyldopa in human melanoma transplanted to athymic mice. Histology of the tumour with the microdialysis probes in situ showed no tissue damage. With probes equipped with polycarbonate membranes (20 kD) extraction (relative recovery) was approximately 50% at pH 4.0 and flow rates of 1 microliter/min, but at pH 7.0 recoveries were markedly lower, particularly from serum. In a first series of human melanomas transplanted to athymic mice low concentrations of 5-S-cysteinyldopa were detected in only two out of ten dialysates and were not detected in the other eight. Utilizing devices constructed for comparison of membrane characteristics in vitro we found about 4-fold higher recoveries with cuprophane and polyamide membranes than with polycarbonate membranes. Therefore newly constructed microdialysis probes (CMA/11) with cuprophane membranes were tested in vitro and gave recoveries of 38-48% from Ringer-Acetate solutions and 22-31% from serum, and the pH effects were low. When these probes were utilized in a second series of melanomas transplanted to athymic mice, 5-S-cysteinyldopa could easily be quantified in 10/10 experiments. A steady-state level of the dialysate 5-S-cysteinyldopa concentration was reached after 45 min.
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The present study was designed to analyze the relationship of human papillomavirus (HPV)-DNA, microvessel density, and their impact on clinical outcome in early cervical carcinoma. HPV-DNA was evaluated in 171 cases of cervical carcinoma treated from 1965 to 1990. In 110 cases, the analyses could be performed. A polymerase chain reaction technique was used on paraffin-embedded specimens obtained before the start of therapy. HPV-DNA of any type was detected in 78% (86/110) of all evaluable tumors. HPV16 was the predominant type and was detected in 56% (62/110), HPV18 in 8% (9/110), and HPV35 in 21% (23/110). Patients with tumors containing HPV16 or HPV18 were significantly (P = 0.011) younger than patients with tumors not containing either of these two subtypes. Vascular space invasion and lymph node metastases were observed more frequently in tumors expressing HPV16 and HPV18 (P = 0.002, P = 0.047) than in tumors negative for these HPV strains. Tumors containing HPV16 and HPV18 were significantly (P = 0.012) larger and more frequently (P = 0.005) associated with higher FIGO stages. The cancer-specific survival rate was lower for patients with HPV16- and HPV18-positive tumors, but the difference was not statistically significant. The microvessel density was a non-significant prognostic factor. The overall 5-year survival rate of the complete series was 91%. It was concluded that HPV-DNA was a prognostic factor in early-stage cervical cancer and was associated with the age of the patient, vascular space invasion, lymph node metastases, tumor size, and FIGO stage.
Electron beams in the MM50 racetrack microtron are generated by computer controlled scanning of a well-focused electron pencil beam. The treatment head is optimized to give a minimum of scatter between the source position and the collimator plane by a general minimization of all scattering material in the beam and by replacement of the air in the treatment head by helium, which has a much lower linear scattering power than air. A double-focused multileaf collimator with a 31-cm collimator to patient distance is used both for electron and photon collimation. In general, no extra electron collimation is needed for the standard SSD of 100 cm. To make irregular field collimation at a distance this far from the patient possible, a number of requirements have to be fulfilled regarding the virtual source position and the spatial and angular distribution of the initial electron beam. The virtual source position has been found to be at a fixed position for different irradiation parameters. This is important for the use of the light field in electron beam treatment but also for achieving a high degree of accuracy in the dosimetry. Scatter from the multileaf collimator has not been found to give any significant contribution to the radiation field or to the monitor output factor of the MM50. Experimental dose distribution data on the MM50 have been compared to data both from other types of treatment units and to Monte Carlo simulations.