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Biomedical subjects

B Karlsson

Publications and source records attributed to B Karlsson.

At least 55 records · Page 3Linked to original sources
PubMed1997

Prediction of obliteration after gamma knife surgery for cerebral arteriovenous malformations.

OBJECTIVE: To define the factors of importance for the obliteration of cerebral arteriovenous malformations (AVMs), thus making a prediction of the probability for obliteration possible. METHODS: In 945 AVMs of a series of 1319 patients treated with the gamma knife during 1970 to 1990, the relationship between patient, AVMs, and treatment parameters on the one hand and the obliteration of the nidus on the other was analyzed. RESULTS: The obliteration rate increased both with increased minimum (lowest periphery) and average dose and decreased with increased AVM volume. The minimum dose to the AVMs was the decisive dose factor for the treatment result. The higher the minimum dose, the higher the chance for total obliteration. The curve illustrating this relation increased logarithmically to a value of 87%. A higher average dose shortened the latency to AVM obliteration. For the obliterated cases, the larger the malformation, the lower the minimum dose used. This prompted us to relate the obliteration rate to the product minimum dose (AVM volume)1/3 (K index). The obliteration rate increased linearly with the K index up to a value of approximately 27, and for higher K values, the obliteration rate had a constant value of approximately 80%. For the group of 273 cases treated with a minimum dose of at least 25 Gy, the obliteration rate at the study end point (defined as 2-yr latency) was 80% (95% confidence interval = 75-85%). If obliterations that occurred beyond the end point are included, the obliteration rate increased to 85% (81-89%). CONCLUSION: The probability of obliteration of AVMs after gamma knife surgery is related both to the lowest dose to the AVMs and the AVM volume, and it can be predicted using the K index.

Adolescent↗
PubMed1997

Magnetic resonance imaging of obliterated arteriovenous malformations up to 23 years after radiosurgery.

The authors report outcomes in 18 patients with arteriovenous malformations (AVMs) who were treated with gamma knife radiosurgery and in whom magnetic resonance (MR) imaging was obtained a mean of 14 years (range 8-23 years) after treatment and 10 years (range 4-17 years) after confirmed obliteration of the AVM. All patients were asymptomatic after radiosurgery and during the time of the study. In five patients (28%), cyst formation was observed that corresponded to the site of the obliterated AVM. Cyst formation and contrast enhancement on MR imaging could not be statistically correlated to the radiation dose. In 11 (61%) of the 18 patients, contrast enhancement that was not related to a recanalization of the nidus was observed in the target area. In three patients (17%), an increased T2-weighted signal was detected at the site of previous AVM; this was interpreted as gliosis or demyelination, which appeared to be dose dependent. The study illustrates that cyst formation, contrast enhancement, and an increased T2-weighted signal can be observed in asymptomatic patients in the area that was targeted for AVM radiosurgery up to 23 years after the procedure. The report provides new and essential information about long-term effects on normal tissue after radiosurgery and provides a basis for the interpretation of MR studies in the follow up of small AVMs treated by radiosurgery.

Adolescent↗
PubMed1997

Tumor seeding following stereotactic biopsy of brain metastases. Report of two cases.

In a series of 22 patients treated with gamma knife surgery for brain metastasis in whom biopsy specimens were obtained via stereotactically guided procedures before the radiosurgical treatment was administered, two cases with evidence of tumor seeding were observed on subsequent follow-up examination. These findings contradict the opinion that the risk for tumor spread after a biopsy is negligible. This evidence may be explained by the fact that radiosurgery leaves the surrounding tissue unaffected by the treatment, which results in preserved anatomy around the tumor. This allows the surgeon to define the previous biopsy channel and, consequently, whether a distant tumor recurrence may have resulted from tumor seeding related to the biopsy procedure. Additionally, radiosurgical treatment leaves tumor cells that may have been spread as a result of the biopsy unaffected, giving them the potential to divide and develop into a new tumor. In contrast to this, microsurgical removal of the tumor will affect the surrounding tissue, making it impossible to detect whether new metastases are resulting from seeding. Furthermore, conventional fractionated radiation therapy will sterilize tumor cells that may have spread, thus making it impossible for these cells to regrow. The authors conclude that the risk for tumor seeding following a stereotactically guided biopsy may be higher than previously assumed.

Adult↗
PubMed1996

Influence of colostomy on in vivo and in vitro permeability of the rat colon.

PURPOSE: Barrier properties of an isolated colon loop and the remnant colon in continuity with the gastrointestinal tract after colostomy were studied in the rat. METHODS: The in vivo absorption after colonic loop administration of the marker fluorescein sodium was measured as the urinary recovery. The in vitro permeability was measured in Ussing diffusion chambers as the transmucosal passage of [14C]mannitol and of human serum albumin in the isolated and the nonexcluded colonic segments and was compared with the corresponding colonic regions from sham-operated rats at 1 to 14 days after operation. RESULTS: Body weight gain of the rats decreased and diarrhea appeared from day 2 after colostomy. Histologic examination showed mucosal atrophy with decreased villus height in the isolated colonic loop and an increased villus height in the nonexcluded colon segment. Absorption of fluorescein sodium in the isolated loop was increased at 8 and 14 days. Moreover, permeability in the isolated loop was increased for both mannitol and human serum albumin from four days after colostomy compared with the corresponding colonic segments after the sham operation, whereas a decrease in the passage of mannitol was noted in the nonexcluded colon. CONCLUSIONS: Experimentally performed colostomy diversion in the rat induced alterations of the barrier function in both the isolated colonic loop and the nonexcluded colon in continuity with the fecal stream.

Animals↗
PubMed1996

Transvaginal sonography of the endometrium in a representative sample of postmenopausal women.

The aim of this study was to assess endometrial thickness using transvaginal sonography in a representative sample of postmenopausal women and to evaluate whether the technique can be used for screening of endometrial cancer. A random sample (n = 1000) of the total population of women aged 45-80 years resident in the city of Göteborg in 1993 was invited to attend for transvaginal sonography. The only exclusion criterion was hysterectomy. Transvaginal sonography was performed in 827 women. An endometrium of < or = 4 mm was not investigated further. Women with an endometrium of 5-7 mm and non-measurable cases were re-assessed 1 year later, and women with an endometrial thickness of > or = 8 mm were investigated directly with hysteroscopy and/or dilatation and curettage. A total of 559 women were postmenopausal and 183 were taking some form of hormonal substitution (33%). One case of endometrial cancer (endometrial thickness 19 mm), 23 cases of polyps without atypia (endometrial thickness 8-18 mm) and no cases of endometrial hyperplasia were diagnosed. Endometrial thicknesses were as follows (mean +/- SEM; respectively grouped as < or = 4 mm, 5-7 mm and > or = 8 mm): total population of postmenopausal women (3.4 +/- 0.1 mm, 82%, 13% and 6%); postmenopausal women without estrogens (3.0 +/- 0.1 mm, 90%, 7% and 3%); postmenopausal women on medium-potency estrogens + gestagen (5.1 +/- 0.3 mm, 49%, 40% and 11%) and women with low-potency estrogens only (3.6 +/- 0.3 mm, 85%, 6% and 9%). The prevalence of endometrial cancer was 0.2% and for benign polyps 3.2% in this representative sample of postmenopausal women. Our results do not support generalized endometrial screening with transvaginal sonography.

Aged↗
PubMed1996

Effect of Gamma Knife surgery on the risk of rupture prior to AVM obliteration.

The incidence for hemorrhage in non-obliterated arteriovenous malformations (AVM) during the first two years following Gamma Knife (GK) surgery was compared to the calculated incidence in untreated patients. There was a decrease in the incidence of hemorrhage as compared to the natural course. This difference was statistically significant. The actual number of hemorrhages during the first two years was 49 in a series of 1604 patients. Additionally, 41 hemorrhages occurred beyond the two years following treatment over the entire follow up time span of up to 24 years. For the first two years the calculated incidence was roughly two times higher than the observed incidence. This impact on the natural history was detectable already within six months after the treatment for the malformations totally covered with at least 25 Gy. The relation between a high minimum and a high average dose on the one hand and a lower risk for hemorrhage on the other hand was statistically significant. Low treatment doses and high age correlated to a higher risk. Neither hemorrhage prior to treatment nor time interval between presenting hemorrhage and treatment seemed to influence the risk for post treatment hemorrhage. The risk for permanent neurological deficit or death due to AVM rupture during the latency period between the time of treatment and total nidus obliteration was less than 0.5% for small AVM and 2-4% for large ones during the first two years. Of the 24 patients with sequelae following AVM rupture after treatment 14 died and 10 remained with neurological deficit of different degrees. However, all survivors were self sufficient.

Adult↗
PubMed1996

Recurrence of cranial base meningiomas.

OBJECTIVE: Long-term data on the natural history of traditionally treated cranial base meningiomas are necessary to judge the benefit of modern cranial base techniques for individual patients and to understand when nonradical surgery of a meningioma is in the interest of the patient. The only available means of obtaining such data is investigation of patients treated before the present surgical era. METHODS: The records of 315 patients who were operated on at Karolinska Hospital between January 1, 1947, and December 31, 1982, were reviewed. Of the patients, 10.8% died perioperatively and 9.7% died within 10 years. The remaining patients were followed for 10 to 36 years (mean, 18 yr). RESULTS: The 5-year recurrence rate was 4% for patients undergoing radical surgery (Grades 1 and 2) and 25 to 45% for patients undergoing Grade 3 or 4 operations. Follow-up periods longer than 5 years revealed that 16% of Grade 1 and 20% of Grade 2 patients had symptomatic recurrences, whereas a majority of Grade 4 and 5 patients showed symptomatic progression. Forty-two of 69 patients who underwent Grade 4 or 5 operations died as a result of their tumors, usually within 10 years after the first operation. No patients who underwent Grade 4 or 5 operations were free from symptomatic progression after 20 years. The tumor progression or recurrence was usually detected within the 1st 10 years, but late recurrences were seen < or = 25 years after the operation. The worst outcome was found in medial sphenoid wing/clinoidal meningiomas and in tumors invading the cavernous sinus. Subfrontal tumors showed unexpectedly high recurrence rates, with a mortality rate < or = 14% in the late phase. CONCLUSION: The findings emphasized the necessity to plan the management of patients with cranial base meningiomas according to a 10- to 20-year perspective. Patients must be followed to evaluate the treatment results and to detect recurrences. Nonradical surgery must be viewed as a temporizing or palliative measure; a continued search for means of radical tumor treatment is warranted in these often surgically difficult tumors.

Combined Modality Therapy↗
PubMed1996

Positron emission tomography using 18F-fluorodeoxyglucose in patients with stereotactically irradiated brain metastases.

Thirty-one patients with intracranial metastases were examined with positron emission tomography (PET) using 18F-fluorodeoxyglucose (FDG) as a tracer. The PET study was prompted by growth of the tumor in spite of therapy, or regrowth after an initially favorable response. Increased accumulation of FDG was seen in 14 patients (group 1) and decreased in 17 (group 2). Patients in group 1 had verified tumor growth in 9 of 14 cases. The median survival after radiosurgery was 12.3 months. One patient in this group is still alive after open surgery of a recurrent metastasis. Six patients in group 2 are still alive. The median survival after radiosurgery was 19.9 months. Verified radiation reaction/necrosis was found in 5/17 and viable tumor tissue in 2. The survival time in group 2 was significantly longer than in group 1. PET is superior to computed tomography and magnetic resonance imaging in the differentiation between recurrence and radiation reaction/necrosis. However, temporary radiation effects may mask remaining tumor tissue, and repeat PET studies may sometimes be necessary.

Adult↗
PubMed1996

Prediction of results following Gamma Knife surgery for brain stem and other centrally located arteriovenous malformations: relation to natural course.

Two models for predicting the results of Gamma Knife surgery for brain stem and other centrally located arteriovenous malformations (AVMs) are presented. By using these models, the probability of total obliteration and the risk of complications can be predicted. The model to predict the probability for obliteration is based on the following two observations. First, there is a positive relationship between the minimum dose given to the AVM nidus and the incidence of obliteration. Second, there is a negative relationship between the AVM nidus volume and the minimum dose given in the obliterated cases. The risk estimation model is also based on two observations. First, centrally located AVMs carry a higher risk of complications than those located peripherally. Second, the average dose to volumes which are large for radiosurgery is related to the incidence of complications. The findings of this study may be used to estimate the consequences of Gamma Knife treatment for every individual case prior to the treatment. This makes a comparison between different treatment options and no treatment possible. The risk of hemorrhage without any treatment is also quantified.

Adolescent↗
PubMed1996

Specificity and affinity of 26 monoclonal antibodies against the CA 125 antigen: first report from the ISOBM TD-1 workshop. International Society for Oncodevelopmental Biology and Medicine.

The specificity of 26 monoclonal antibodies against the CA 125 antigen was investigated in two phases of the ISOBM TD-1 workshop. The binding specificity was studied using CA 125 immunoextracted by specific antibodies immobilized on various solid phases, or on the surface of human cell lines. Immunometric assays using all possible antibody combinations were used to study the topography of antibody binding sites on the antigen. We conclude that the CA 125 antigen carries only two major antigenic domains, which classifies the antibodies as OC125-like (group A) or M11-like (group B). One antibody, OV 197, showed binding specificity related to some of the OC125-like antibodies, but was classified into a separate group C. The OC125-like group of antibodies has four subgroups with different binding specificities. These are A1 = OC 125 and K 95, A2 = K 93, A3 = B43.13, and A4 = ZS 33, B27.1 and CCD 247. Binding of nonlabelled OC 125 or K 95 to CA 125 caused a marked increase in binding of labelled OV 197 to the complex. This conformational change was not observed with any other antibody combinations. Antibody B43.13 could form immunometric assay combinations particularly with antibodies of subgroup A4, indicating that the B43.13 epitope is in the periphery of the binding area of OC125-like antibodies. The M11-like group of antibodies is more homogenous with strong cross-inhibition between most antibodies. Only one antibody, ZR 38, would form an immunoassay combination with other M11-like antibodies and thus represents a distinct subgroup. The main group of M11-like antibodies are M 11, ZR 45, MA602-6, K 91, OV 185, K 101, K 90, K 96, K 97, K 102, CCD 242, 145-9, and 130-22. Antibody OV 197 binds to a domain designated C and is unique, as stated above. Antibody pairs from any two of the three groups may be used in immunometric assays. Three antibodies were not studied by complete cross-inhibition due to low affinity (OV 198 and K 100) or lack of material (MA602-1). OV 198 and K 100 are most likely OC125-like and MA602-1 is M11-like. Antibody affinity was estimated with labelled antigen in solution or with antigen absorbed on microtiter wells. Western blot analysis showed staining both in the stacking gel and corresponding to a molecule of 200 kDa. There was a marked difference between the antibodies in their ability to bind to CA 125 immobilized on a membrane. Strongest binding was observed with the M11-like antibodies, particularly M 11, K 96, K 97, MA602-6, 145-9. Antibodies belonging to the subgroup A4 were the only OC 125-like antibodies which reacted well with CA 125 in Western analysis. Digestion of CA 125 with proteolytic enzymes showed it to be particularly sensitive to trypsin cleavage. However, no low molecular weight fragments with preserved immunoreactivity were found.

Animals↗
PubMed1996

Prediction of complications in gamma knife radiosurgery of arteriovenous malformation.

The incidence of complications following radiosurgical treatment of arteriovenous malformations (AVM) is presented. A simple relationship exists between average dose and risk of complications, and on this basis a model is presented that gives a qualitatively correct description of this relationship. The parameters of the model have been determined using a clinical material of 862 AVM treatments to give a quantitatively correct description of the risk of complications. The dose-response curve is described by a double-exponential function. An accurate description of the dose-response curve at high dose levels is shown to be very important in radiosurgery.

Algorithms↗
PubMed1995

Repetitive industrial work and neck and upper limb disorders in females.

A cross-sectional study was performed in which physical examinations of the neck and upper limbs were conducted on 82 currently working female industrial workers with exposure to repetitive work tasks and on 64 currently working referent subjects without exposure to repetitive work tasks. Associations between results of symptom questions and physical examination were sought with variables related to the work environment and to the individuals. In a multivariate model, there were statistically significant associations between exposure to repetitive work and diagnoses in both the neck/shoulders (prevalence odds ratio, POR = 4.6) and elbows/hands (POR = 3.5). In addition, age (POR = 1.9, 75th vs. 25th percentiles), tendencies towards subjective muscular tension (POR = 2.3), and stress/worry (POR = 1.9) were also associated with diagnoses in the neck/shoulders; however, there was not an association between these variables and the prevalence of diagnoses in elbows/hands. Standardized evaluation of videotape recordings in 74 of the industrial workers revealed significant associations between neck flexion, and elevation and abduction of the arm and the prevalence of neck/shoulder diagnoses. In the multivariate model, neck flexion was significantly associated with diagnoses in the neck/shoulders (p = 0.005). In addition, low muscle strength, lack of emotional well-being at work, and a variety of psychosomatic symptoms were associated with diagnoses in the neck/shoulders (all p < 0.001). Lack of strength was also associated with disorders of elbows/hands (p = 0.007). This study demonstrated a substantial prevalence of neck and upper limb disorders associated with repetitive work performed with a flexed neck and elevated and abducted arms, as well as a possible potentiation of these ergonomic factors by certain personal traits in some workers.

Adult↗
PubMed1995

Transvaginal ultrasonography of the endometrium in women with postmenopausal bleeding--a Nordic multicenter study.

OBJECTIVE: The purpose of this study was to use transvaginal ultrasonographic measurements to find the thickness of the endometrium below which the risk of endometrial abnormality in women with postmenopausal bleeding is low. STUDY DESIGN: This multicenter study was carried out at eight clinics in four Nordic countries. The study included 1168 women with postmenopausal bleeding scheduled for curettage Before the curettage was performed, the thickness of the endometrium was measured with transvaginal ultrasonography. The measurement included both endometrial layers (double-layer technique). The transvaginal ultrasonographic measurement was compared with the histopathologic diagnosis of the curettage specimens. RESULTS: In women with atrophic endometrium the mean endometrial thickness (+/- SD) was 3.9 +/- 2.5 mm. The corresponding figures for women with endometrial cancer were 21.1 +/- 11.8 mm. No malignant endometrium was thinner than 5 mm. In 30 women (2.8%) it was not possible to measure the thickness of the endometrium; one of these women had endometrial cancer. The 95% confidence limit for the probability of excluding endometrial abnormality was 5.5% when the endometrial thickness was < or = 4 mm as measured by transvaginal ultrasonography. CONCLUSION: The risk of finding pathologic endometrium at curettage when the endometrium is < or = 4 mm as measured by transvaginal ultrasonography is 5.5%. Thus in women with postmenopausal bleeding and an endometrium < or = 4 mm it would seem justified to refrain from curettage.

Adult↗
PubMed1995

Postnatal development of the cerebral blood flow velocity response to changes in CO2 and mean arterial blood pressure in the piglet.

Cerebral blood flow velocity was studied during changes (haemorrhage) in mean arterial blood pressure or P(a)CO2 in 56 (aged 0-26 days) anaesthetized and ventilated piglets. The CO2 reactivity increased with age from 6.5% kPa-1 (< 1 day) to adult levels of 25% kPa-1 for piglets over 4 days old. The mean arterial blood pressure reactivity was reduced from 1.3% mmHg-1 (< 1 day old) to 0.0%/mmHg (> 4 days old). The reactivities were similar with two different anesthetics: chloralose/urethane or pentobarbital. To validate the cerebral blood flow velocity data, both electromagnetic flow and precerebral Doppler ultrasound velocity were recorded from the same common carotid artery with extracranial branches tied off. There were no differences between the results with these two methods nor between these results and those obtained when the cerebral blood flow velocities were recorded from an intracerebral artery and the electromagnetic flowmeter recorded from the carotid artery. The vessel diameter appears stable during these interventions. In conclusion, the autoregulatory response and the reaction to P(a)CO2 appear poorly developed in the newborn piglet, but rapidly mature during the first 4 days of life.

Age Factors↗
PubMed1994

Cellular and extracellular components at nodes of Ranvier in rat white matter.

Rat CNS nodes of Ranvier were investigated by electron microscopy and immunohistochemistry. Nodes along thin callosal axons possess tiny node gaps containing few or no astrocytic processes. Nodes along thick spinal axons exhibit spatious node gaps containing relatively few irregularly arranged astrocytic processes. Antibodies against HNK-1, chondroitin sulfate, tenascin or NSP-4 do not label small nodes but stain large nodes. We conclude that rat CNS fibers do not exhibit a strict relation between nodal complexity and fiber size comparable to that found in rat PNS fibers.

Animals↗
PubMed1994

Unpredictable food and sexual size dimorphism in insects.

The evolution of sexual size dimorphism is likely to be affected by the amount of resources each sex invests in offspring. Male nuptial gifts, occurring in many insect species, might reduce the value of large size in females and increase the value for males. For large nuptial gifts and an accompanying shift in dimorphism to evolve, males with larger gifts should be rewarded, in effect trading the larger gift for more offspring. We suggest that food variability, causing some males to have much to provide and some females to be in great need, would be conducive to the evolution of such a mating system, and we present comparative data on butterflies supporting the suggestion. In a gift-giving mating system, growing male and female juveniles should react differently to food shortage. A female maturing at small size can to some extent buffer her disadvantage through nuptial gifts, whereas a male maturing at small size will suffer from his inability to provide substantial gifts. Thus, males benefit more than females from continued growth in the face of food shortage, leading to a shift in size dimorphism. Here we confirm this prediction in a butterfly, Pieris napi, with large nuptial gifts.

Animals↗