Biomedical subjects

M Hellström

Publications and source records attributed to M Hellström.

At least 19 recordsLinked to original sources

PubMed2006

Ultrasound assessment of detrusor thickness in children and young adults with myelomeningocele.

PURPOSE: We determine by ultrasonography the range of dT in carefully treated and followed children with myelomeningocele, and evaluate the role of such measurements for the understanding of bladder abnormalities in these patients. MATERIALS AND METHODS: We studied 66 children and young adults with MMC (34 males and 32 females, median age 8.1 years, range 1.1 to 20.1). Detrusor thickness was measured with a previously established ultrasonographic technique and the results were compared to those in normal children. The variation in detrusor thickness with degree of bladder dysfunction as well as with bladder wall trabeculation, kidney function and anticholinergic treatment was studied. RESULTS: The detrusor of the ventral wall was slightly thinner in children with MMC compared to normal. No significant variation in dT was found for different degrees of bladder dysfunction, bladder wall trabeculation, kidney function or anticholinergic treatment. Boys had thicker detrusor of the ventral wall than girls. CONCLUSIONS: Children with MMC, followed closely and treated according to international standards, do not acquire detrusor thickening as measured by ultrasonography. The detrusor thickness did not correlate with the degree of bladder dysfunction or renal function, or with anticholinergic treatment. Bladder wall trabeculation at VCU was not associated with bladder wall thickening on ultrasonography. We postulate that in a closely monitored and actively treated population of patients with MMC muscular hypertrophy and the development of connective tissue in the bladder wall is kept to a minimum.

Adolescent↗

PubMed2006

Availability, indications, and technical performance of computed tomographic colonography: a national survey.

PURPOSE: To determine the availability, indications, and technique of computed tomographic colonography (CTC) in Sweden and to investigate opinions on its future role in colon imaging. MATERIAL AND METHODS: In May 2004, a questionnaire on CTC was mailed to all Departments of Radiology in Sweden, and one year later a telephone interview was conducted with the departments that intended to start a CTC service. RESULTS: Ninety-nine departments (83%) answered the questionnaire, indicating that 23/ 99 (23.2%) offered a CTC service. Reasons for non-implementation of CTC were lack of CTC training in 34/73 (46.6%) and non-availability of multi-detector row CT scanners in 33/73 (45.2%), while 26% were awaiting further scientific documentation on CTC. Incomplete colonoscopy was the main indication for CTC in 21/23 (91.3%) departments performing CTC. Dual positioning, room air insufflation, and thin-slice collimation were used in all the responding departments. The number of CTC studies performed varied from 1-5 (26.1%) to more than 200 (17.4%). Intravenous contrast material was routinely administered by 9/23 (39.1%) departments. Out of 30 (39.5%) departments that in 2004 intended to start CTC, 9 (30%) had done so by June 2005. A total of 32/99 (32.3%) departments had therefore started CTC by June 2005. Half of the departments that replied believed that CTC would absolutely or probably replace barium enema in the future. CONCLUSION: The survey shows relatively limited diffusion of CTC practice in Sweden, with approximately one-third of radiology departments offering a CTC service, mostly on a small scale. A wider dissemination of CTC requires further scientific documentation of its capability, intensified educational efforts, and additional funding.

Colonic Diseases↗

PubMed2006

Diagnostic performance of computed tomography colonography in symptomatic patients and in patients with increased risk for colorectal disease.

PURPOSE: To evaluate the diagnostic performance (colorectal lesions) of computed tomography (CT) colonography in 111 patients, a majority of whom were at high risk for colorectal neoplasia. MATERIAL AND METHODS: After bowel preparation, CT colonography was performed, immediately followed by conventional colonoscopy. The diagnostic performance of CT colonography was analyzed relative to lesion size, histological diagnosis, and diagnostic certainty. RESULTS: The sensitivity of CT colonography increased with lesion size (P<0.001), and was 91% (21/23) for lesions > or = 10 mm. All 10 carcinomas and 86% (19/22) of adenomas > or = 5 mm were detected. Unconfirmed or false-positive CT findings were generally small and/or reported with low diagnostic certainty. The specificity of CT colonography would be 45% (30/66; 95% CI 34% to 57%) if patients with findings of any size and any diagnostic certainty were selected for follow-up, and 92% (85/92; 95% CI 85% to 96%) if only patients with CT findings > or = 10 mm classified as certain were selected. CONCLUSION: CT colonography had a high sensitivity for lesions > or = 5 mm. The diagnostic performance increased with lesion size and degree of diagnostic certainty, and was higher for adenomas.

Adult↗

PubMed2005

Evidence for pygmy and giant dipole resonances in 130Sn and 132Sn.

The dipole strength distribution above the one-neutron separation energy was measured in the unstable 130Sn and the double-magic 132Sn isotopes. The results were deduced from Coulomb dissociation of secondary Sn beams with energies around 500 MeV/nucleon, produced by in-flight fission of a primary 238U beam. In addition to the giant dipole resonance, a resonancelike structure ("pygmy resonance") is observed at a lower excitation energy around 10 MeV exhausting a few percent of the isovector E1 energy-weighted sum rule. The results are discussed in the context of a predicted new dipole mode of excess neutrons oscillating out of phase with the core nucleons.

Journal Article↗

PubMed2005

Simultaneous measurement of beta- decay to bound and continuum electron states.

We report the first measurement of a ratio lambda(beta(b))/lambda(beta(c)) of bound-state ((lambda(beta(b))) and continuum-state (lambda(beta(c))) beta(-)-decay rates for the case of bare 207Tl81+ ions. These ions were produced at the GSI fragment separator FRS by projectile fragmentation of a 208Pb beam. After in-flight separation with the Brho-deltaE-Brho method, they were injected into the experimental storage-ring ESR at an energy of 400.5A MeV, stored, and electron cooled. The number of both the 207Tl81+ ions and their bound-state beta(-)-decay daughters, hydrogen-like 207Pb81+ ions, were measured as a function of storage time by recording their Schottky-noise intensities. The experimental result, lambda(beta(b))/lambda(beta(c)) = 0.188(18), is in very good agreement with the value of 0.171(1) obtained from theory employing spectra of allowed transitions.

Journal Article↗

PubMed2005

Contrast-medium-Induced nephropathy correlated to the ratio between dose in gram iodine and estimated GFR in ml/min.

PURPOSE: To suggest a more precise tool when assessing the risk of contrast-medium-induced nephropathy (CIN), i.e. the ratio between contrast medium (CM) dose expressed in grams of iodine (g-I) and estimated glomerular filtration rate in ml/min (eGFR; based on equations using serum-creatinine (s-Cr), weight, height, age, and/or sex), here named I-dose/GFR ratio. MATERIAL AND METHODS: A Medline search of published CIN investigations reporting mean eGFR and mean dose of low-osmolality CM (LOCM) identified 10 randomized controlled prophylactic and 2 cohort coronary investigations, and 3 randomized and 1 cohort computed tomographic (CT) investigation. From the randomized trials, data were collected only from the placebo or control arms, unless there was no significant difference between the control and test groups. The mean I-dose/GFR ratio of each study was correlated with the mean frequency of CIN-1 (s-Cr rise> or =44.2 micromol/l or > or =20-25%) and CIN-2 (oliguria or requiring dialysis). A maximum dose according to an I-dose/GFR ratio= 1 in patients with s-Cr ranging from 100 to 300 micromol/l was compared with that of CIGARROA'S formula and with a "European consensus" threshold published by the European Society of Urogenital Radiology, both using s-Cr alone to predict renal function. McCullough's formula was used to assess the risk of CIN requiring dialysis at an I-dose/GFR ratio= 1 with LOCM. RESULTS: The coronary investigations revealed a linear correlation with a correlation coefficient between the I-dose/GFR ratio and the frequency of CIN-1 and CIN-2 of 0.91 (P<0.001) and 0.84 (P=0.001), respectively. At a mean I-dose/GFR ratio= 1, the regression line indicated a 10%) risk of CIN-1 and a 1% risk of CIN-2. At a mean I-dose/ GFR ratio=3, the risk of CIN-1 and CIN-2 increased to about 50% and 15%, respectively. Pooled weighted data from the CT investigations revealed a 12% risk of CIN-1 at a mean I-dose/GFR ratio = 1.1 and no cases of CIN-2. The maximum CM dose according to an I-dose/GFR ratio= 1 was about 30-50% of that of both Cigarroa's formula and the "European consensus" in elderly low-weight individuals, while it was similar for middle-aged individuals weighing about 90 kg. McCullough's formula suggests that there will be an exponentially increasing risk of CIN requiring dialysis, but at an I-dose/GFR ratio= 1 and using LOCM it will not exceed 1% until GFR decreases below 30 ml/min in diabetics and below 20 ml/min in non-diabetics. CONCLUSION: Using the I-dose/GFR ratio may be a more expedient way of improving risk assessment of CIN than today's common practice of estimating CM dose from volume alone and renal function from s-Cr alone. Prospective studies based on individual patient data are encouraged to define the risk of CIN at various I-dose/GFR ratios and correlated to type of CM, examination, risk factors, etc.

Adult↗

PubMed2005

MRI combined with MR cholangiopancreatography versus helical CT in the evaluation of patients with suspected periampullary tumors: a prospective comparative study.

PURPOSE: To establish the diagnostic accuracy of MRI including MR cholangiopancreatography (MRCP) compared with helical CT in the differentiation of malignant and benign lesions in the periampullary region. MATERIAL AND METHODS: Fifty-one patients (27 M, 24 F, mean age 66 years, range 39-86 years) with obstructive jaundice and sonographic evidence of intra- and extrahepatic bile duct dilatation (n=31) or suspicion of periampullary tumor, based on previously performed ultrasound and/or CT examination (n=20), were studied. MRI with MRCP and helical CT were reviewed blindly under standardized conditions. Lesion status (differentiation of malignant versus benign) was rated on a 5-point diagnostic confidence scale. Reference standards for comparison were findings at surgery or laparoscopy and/ or the clinical outcome. The predictive value of imaging findings was determined with multivariate logistic regression analysis. RESULTS: The areas under the receiver operating characteristic curve were 0.96 for MRI with MRCP and 0.81 for CT (P <0.05). Multivariate analysis of eight imaging variables at MRI indicated that a stricture with malignant characteristics at MRCP was the best predictor of malignancy. CONCLUSION: MRI with MRCP was significantly more accurate than CT in differentiating between malignant and benign lesions in patients with suspected periampullary tumors, mainly due to the information obtained on the MRCP images of the biliary and pancreatic duct anatomy.

Adult↗

PubMed2005

Timed barium esophagogram in the assessment of patients with achalasia: reproducibility and observer variation.

SUMMARY. The timed barium esophagogram (TBE) is a further development of the barium swallow, introducing functional and dynamic dimensions to the assessment. The purpose of our study was to assess the day to day variability of TBE parameters when scored in healthy subjects, in untreated and in previously treated patients with confirmed diagnoses of achalasia and to assess the intra- and interobserver agreement. After fasting, the subjects drank 250 mL of low-density barium sulfate suspension. Radiographs of the esophagus were exposed at 1, 2 and 5 min after the start of the barium ingestion. The heights and widths of the barium column and changes in these parameters over time (esophageal emptying) were assessed. Each subject was re-tested after a median time interval of 8 days. Healthy individuals emptied their esophagi effectively and promptly with no significant amount of contrast remaining in the lumen after 2 min. In the achalasia patients all TBE variables differed profoundly compared to the controls. There was an excellent intra- and interobserver agreement for all measured variables. The reproducibility of the static TBE variables from day-to-day was good, but not so for the functional assessment of esophageal emptying, having a correlation coefficient of only 0.50. The usefulness of TBE as a clinical and research tool in achalasia patients requires further evaluation.

Adult↗

PubMed2004

A phase I trial of DNA vaccination with a plasmid expressing prostate-specific antigen in patients with hormone-refractory prostate cancer.

Prostate-specific antigen (PSA) is a serine protease secreted at low levels by normal luminal epithelial cells of the prostate and in significantly higher levels by prostate cancer cells. Therefore, PSA is a potential target for various immunotherapeutical approaches against prostate cancer. DNA vaccination has been investigated as immunotherapy for infectious diseases in patients and for specific treatment of cancer in certain animal models. In animal studies, we have demonstrated that vaccination with plasmid vector pVAX/PSA results in PSA-specific cellular response and protection against tumour challenge. The purpose of the trial was to evaluate the safety, feasibility and biological efficacy of pVAX/PSA vaccine in the clinic. A phase I trial of pVAX/PSA, together with cytokine granulocyte/macrophage-colony stimulating factor (GM-CSF) (Molgramostim) and IL-2 (Aldesleukin) as vaccine adjuvants, was carried out in patients with hormone-refractory prostate cancer. To evaluate the biologically active dose, the vaccine was administered during five cycles in doses of 100, 300 and 900 microg, with three patients in each cohort. Eight patients were evaluable. A PSA-specific cellular immune response, measured by IFN-gamma production against recombinant PSA protein, and a rise in anti-PSA IgG were detected in two of three patients after vaccination in the highest dose cohort. A decrease in the slope of PSA was observed in the two patients exhibiting IFN-gamma production to PSA. No adverse effects (WHO grade >2) were observed in any dose cohort. We demonstrate that DNA vaccination with a PSA-coding plasmid vector, given with GM-CSF and IL-2 to patients with prostate cancer, is safe and in doses of 900 microg the vaccine can induce cellular and humoral immune responses against PSA protein.

Adenocarcinoma↗

PubMed2003

The t+n+n system and 5H.

The one-proton knockout channel from 6He (240 MeV/u) impinging on a carbon target has been investigated. The triton fragments originating from this channel were detected in coincidence with the two neutrons. A broad structure, peaked at 3 MeV above the t+2n threshold, is observed in the t+n+n-relative energy spectrum. It is shown that this structure is mainly due to a I(pi)=1/2(+) resonance as expected for the 5H ground state, and from the observed angular and energy correlations, being used for the first time in 5H studies, that the neutrons to a large extent occupy the p shell.

Journal Article↗

PubMed2002

Evidence for a new low-lying resonance state in 7He.

Low-lying resonance states in 7He(6He+n), formed after fragmentation reactions of a 227 MeV/nucleon 8He beam on a carbon target, have been studied. Coincidences between 6He nuclei and neutrons, corresponding to the one-neutron knockout channel in 8He, were selected. The relative energy spectrum in the 6He+n system shows a structure, which is interpreted as the 7He ( Ipi = 3/2(-)) ground state, unbound with 0.43(2) MeV relative to the 6He+n system and a width of Gamma = 0.15(8) MeV overlapping with an excited ( Ipi = 1/2(-)) state observed at 1.0(1) MeV with a width of Gamma = 0.75(8) MeV.

Journal Article↗

PubMed2002

Bowel wall visualisation at CT colonography.

PURPOSE: To evaluate the quality of bowel wall visualisation at CT colonography and the impact of examination in the supine and prone positions. MATERIAL AND METHODS: After bowel preparation, 111 patients underwent CT colonography. Air distension, degree of fluid redistribution with change in body position (supine and prone), influence of residual stool on bowel wall assessability, and quality of overall colon visualisation were evaluated using scales. RESULTS: Thirty of 110 patients (27%) had complete overall visualisation of the colon wall and 52 (47%) had subtotal visualisation of a limited part of the colon. The entire colon was more often air-filled in the prone position (46%) than in the supine position (18%). Joint review of supine and prone data showed that for all colon segments, except the sigmoid (86%), > or =95% of the patients had complete air filling. All patients had residual fluid. In 75% to 99%, depending on segment, fluid did not interfere with the bowel wall visualisation in the combined evaluation of supine and prone data sets. Thirty-one patients had residual stool with potential negative influence on polyp detection. CONCLUSIONS: The colon wall was completely, or almost completely, visualised in 75% of the patients, and examination in the supine and prone positions was necessary for complete visualisation.

Adult↗

PubMed2001

Lack of pericytes leads to endothelial hyperplasia and abnormal vascular morphogenesis.

The association of pericytes (PCs) to newly formed blood vessels has been suggested to regulate endothelial cell (EC) proliferation, survival, migration, differentiation, and vascular branching. Here, we addressed these issues using PDGF-B-- and PDGF receptor-beta (PDGFR-beta)--deficient mice as in vivo models of brain angiogenesis in the absence of PCs. Quantitative morphological analysis showed that these mutants have normal microvessel density, length, and number of branch points. However, absence of PCs correlates with endothelial hyperplasia, increased capillary diameter, abnormal EC shape and ultrastructure, changed cellular distribution of certain junctional proteins, and morphological signs of increased transendothelial permeability. Brain endothelial hyperplasia was observed already at embryonic day (E) 11.5 and persisted throughout development. From E 13.5, vascular endothelial growth factor-A (VEGF-A) and other genes responsive to metabolic stress became upregulated, suggesting that the abnormal microvessel architecture has systemic metabolic consequences. VEGF-A upregulation correlated temporally with the occurrence of vascular abnormalities in the placenta and dilation of the heart. Thus, although PC deficiency appears to have direct effects on EC number before E 13.5, the subsequent increased VEGF-A levels may further abrogate microvessel architecture, promote vascular permeability, and contribute to formation of the edematous phenotype observed in late gestation PDGF-B and PDGFR-beta knock out embryos.

Animals↗

PubMed2001

Basis of hematopoietic defects in platelet-derived growth factor (PDGF)-B and PDGF beta-receptor null mice.

Platelet-derived growth factor (PDGF)-B and PDGF beta-receptor (PDGFR beta) deficiency in mice is embryonic lethal and results in cardiovascular, renal, placental, and hematologic disorders. The hematologic disorders are described, and a correlation with hepatic hypocellularity is demonstrated. To explore possible causes, the colony-forming activity of fetal liver cells in vitro was assessed, and hematopoietic chimeras were demonstrated by the transplantation of mutant fetal liver cells into lethally irradiated recipients. It was found that mutant colony formation is equivalent to that of wild-type controls. Hematopoietic chimeras reconstituted with PDGF-B(-/-), PDGFR beta(-/-), or wild-type fetal liver cells show complete engraftment (greater than 98%) with donor granulocytes, monocytes, B cells, and T cells and display none of the cardiovascular or hematologic abnormalities seen in mutants. In mouse embryos, PDGF-B is expressed by vascular endothelial cells and megakaryocytes. After birth, expression is seen in macrophages and neurons. This study demonstrates that hematopoietic PDGF-B or PDGFR beta expression is not required for hematopoiesis or integrity of the cardiovascular system. It is argued that metabolic stress arising from mutant defects in the placenta, heart, or blood vessels may lead to impaired liver growth and decreased production of blood cells. The chimera models in this study will serve as valuable tools to test the role of PDGF in inflammatory and immune responses. (Blood. 2001;97:1990-1998)

Anemia↗

PubMed2001

Identification of proteins in human prostate tumor material by two-dimensional gel electrophoresis and mass spectrometry.

Protein patterns in cells collected from benign prostatic tissues and prostate carcinomas were analyzed using two-dimensional polyacrylamide gel electrophoresis and mass spectrometry. Polypeptide expression was evaluated by computer-assisted image analysis (PDQUEST). Proteins expressed by prostate tumors were identified via in-gel digestion and subsequent matrix-assisted laser desorption/ionization mass spectrometry. In addition to cytoskeletal and mitochondrial proteins, a 40-kDa protein was identified as prostatic acid phosphatase (PAP). PAP expression decreased approximately twofold between benign and malignant tissue. Increased expression of heat shock protein 70 and decreased expression of tropomyosin 1 were also observed in the malignant tissue. The analysis of prostate material by two-dimensional gel electrophoresis and mass spectrometry shows that particular proteins are of interest as markers of disease.

Acid Phosphatase↗

PubMed2001

Detrusor thickness in healthy children assessed by a standardized ultrasound method.

PURPOSE: We determine the ultrasonographic detrusor thickness in healthy infants and children. MATERIALS AND METHODS: We studied 150 healthy children, 79 boys and 71 girls, from newborns to 13 years old. The detrusor of the ventral and dorsal wall was measured with a previously established ultrasonographic technique, and the variation with age and bladder fullness was assessed. RESULTS: Detrusor thickness varied significantly with the degree of bladder fullness (thinner at higher volumes). It also increased slightly with age. At bladder fullness of 10% or greater of expected bladder capacity (EBC), calculated using the formula EBC (ml.) = age (years) x 30 + 30, a practical upper limit for the detrusor thickness of the ventral wall at all ages was 2.0 mm. at a bladder fullness up to 50% of expected bladder capacity or 1.5 mm. at a higher degree of fullness. The detrusor of the ventral wall was slightly thicker in boys than in girls and also somewhat thicker than the detrusor of the dorsal wall. CONCLUSIONS: The results indicate that ultrasonographic measurements of detrusor thickness in children may serve as a diagnostic tool and its usefulness in clinical as well as research work should be explored.

Adolescent↗

PubMed2001

Back pain and radiological changes in the thoraco-lumbar spine of athletes. A long-term follow-up.

From 1996 to 1999, back pain and radiological changes in the thoraco-lumbar spine were investigated in 134 former top athletes, representing wrestling, gymnastics, soccer and tennis (age 27-39 years) and a group of 28 non-athletes of comparable age. This is a long-term follow-up investigation of a previous radiological study of the spine with clinical correlation. Despite significantly more radiological abnormalities among the athletes, they did not report higher frequency of back pain than the non-athletes. A decrease in disc height or new disc height reduction in one or more of the intervertebral discs between the two examinations correlated significantly with back pain at follow-up.

Adolescent↗

PubMed2001

Relatively high risk of treatment failure after prostatectomy: tumour grade, histopathological stage and the preoperative serum PSA level are key prognosticators.

OBJECTIVE: Prostate cancer is the most common malignancy among males in Sweden. Any reduction in morbidity and mortality would require early detection of cases in which curative treatment is achievable. MATERIAL AND METHODS: From 1994 through 1998. 105 patients with clinically localized T1-T2 tumours were subjected to radical prostatectomy at our department. Three patients were lost to follow-up. We obtained clinical information from the patients' medical records and used pathologist reports to characterize the tumours with respect to grade and histopathological stage. We used serum PSA levels as a surrogate end-point, with a level equal to or above 0.6 ng/ml designated as treatment failure. Outcome was examined with respect to tumour grade, histopathological stage and preoperative PSA level. RESULTS: Altogether, 29% of the patients showed PSA failure during follow-up which varied between 2 and 6 years. No mortality due to prostate cancer was recorded during this time period. We found that tumour grade, histopathological staging and as well as the preoperative PSA level correlated with treatment failure (p<0.01). About 80% of the patients with a preoperative PSA <10 ng/ml showed no signs of treatment failure. The corresponding figure for those with PSA above 10 ng/ ml was 55%. The outcome for patients with a PSA between 10-20 did not seem to be better than that for patients with a preoperative PSA >20 ng/ml. CONCLUSION: Our study indicates, that the risk of treatment failure depends strongly on the grade of the tumour and increases when preoperative PSA value is greater than l0 ng/ml.

Follow-Up Studies↗