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Biomedical subjects

A Vestergaard

Publications and source records attributed to A Vestergaard.

At least 19 recordsLinked to original sources
PubMed2000

Skin damage probabilities using fixation materials in high-energy photon beams.

INTRODUCTION: Patient fixation, such as thermoplastic masks, carbon-fibre support plates and polystyrene bead vacuum cradles, is used to reproduce patient positioning in radiotherapy. Consequently low-density materials may be introduced in high-energy photon beams. The aim of the this study was to measure the increase in skin dose when low-density materials are present and calculate the radiobiological consequences in terms of probabilities of early and late skin damage. METHOD: An experimental thin-windowed plane-parallel ion chamber was used. Skin doses were measured using various overlaying low-density fixation materials. A fixed geometry of a 10x10 cm field, a SSD=100 cm and photon energies of 4, 6 and 10 MV on Varian Clinac 2100C accelerators were used for all measurements. Radiobiological consequences of introducing these materials into the high-energy photon beams were evaluated in terms of early and late damage of the skin based on the measured surface doses and the LQ-model. RESULTS: The experimental ion chamber gave results consistent with other studies. A relationship between skin dose and material thickness in mg/cm(2) was established and used to calculate skin doses in scenarios assuming radiotherapy treatment with opposed fields. CONCLUSION: Conventional radiotherapy may apply mid-point doses up to 60-66 Gy in daily 2-Gy fractions opposed fields. Using thermoplastic fixation and high-energy photons as low as 4 MV do increase the dose to the skin considerably. However, using thermoplastic materials with thickness less than 100 mg/cm(2) skin doses are comparable with those produced by variation in source to skin distance, field size or blocking trays within clinical treatment set-ups. The use of polystyrene cradles and carbon-fibre materials with thickness less than 100 mg/cm(2) should be avoided at 4 MV at doses above 54-60 Gy.

Erythema↗
PubMed1997

Structural brain abnormalities in schizophrenia: a family study.

Structural brain abnormalities such as ventricular enlargement are robust correlates of schizophrenia, but the degree of difference compared with unrelated normal controls is only moderate (< 1 standard deviation), and only 40% of patients have values on these measures that fall outside of the normal distribution. Family studies can help to clarify the meaning of this overlap by controlling for some of the non-schizophrenia-related genetic variation in neuroanatomical traits. Computerized tomographic scans of the brain were used to measure ventricular and sulcal cerebrospinal fluid (CSF) to brain ratios (VBR and SBR) for each hemisphere in 16 pairs of discordant siblings from the Copenhagen Schizophrenia High-Risk Project. Schizophrenics' values for VBR and SBR exceeded those of their nonschizophrenic siblings in 75% of the pairs; on average, patients' values on these measures were 1 and 5 standard deviations larger, respectively, than those of their nonschizophrenic siblings. Sulcal and left hemisphere effects were significantly more pronounced than ventricular and right hemisphere effects. After controlling for between-family variation, structural brain abnormalities appear to be more prevalent and more pronounced in schizophrenia than has previously been assumed, with relatively greater deviation observed for cortical and left hemisphere measures of CSF space enlargement.

Adult↗
PubMed1996

Improvement of upper airway obstruction after 131I-treatment of multinodular nontoxic goiter evaluated by flow volume loop curves.

Symptoms of tracheal-esophageal compression are often related to a large nontoxic goiter. The aim of the present study was to evaluate to what degree upper airway obstruction, as measured by flow volume loops, FIF50% and FEF50%/FIF50% (Forced Expiratory Flow at 50% of the vital capacity/ Forced Inspiratory Flow at 50% of the vital capacity) exists in nontoxic multinodular goiter, and whether changes occur after 131I-treatment. Thirteen patients with large multinodular nontoxic goiters were evaluated by estimation of FIF50%, FEF50%/FIF50% ratio and a graphic plot of the flow volume loop curve before and three, six and 12 months after treatment with 131I. FIF50% increased over 12 months from median 1.79 l/sec (range 1.46-3.02) to 2.84 l/sec (1.13-5.69) (p = 0.01). A progressive increase was seen over time (p = 0.001, trend analysis). The FEF50%/FIF50% ratio decreased from in 1.45 (0.32-2.26) to 1.03 (0.43-2.13) 12 months after treatment (p < 0.001). A progressive decrease was seen over time (p = 0.001, trend analysis). By visual evaluation 11 had a flow volume loop curve typical for an upper airway obstruction and in 9 patients the FEF50%/FIF50% ratio was > 1.2. In conclusion we found that upper airway obstruction is present in patients with multinodular nontoxic goiter, and seems to be reduced after 131I-treatment. Flow volume loop curves and measurement of FEF50% and FIF50% are important estimates for upper airway obstruction in these patients.

Aged↗
PubMed1994

Bovine histidine-rich glycoprotein is a substrate for bovine plasma factor XIIIa.

Histidine-rich glycoprotein was purified from bovine plasma and the identity of the protein confirmed through amino acid sequencing. Activated bovine factor XIIIa catalyzed the incorporation of 1 nmol of 1,4-[14C]putrescine into 1 nmol of bovine histidine-rich glycoprotein, showing that histidine-rich glycoprotein has the ability to participate in transglutaminase-catalyzed reactions in vivo.

Amino Acid Sequence↗
PubMed1994

Developmental brain abnormalities in the offspring of schizophrenic mothers. II. Structural brain characteristics of schizophrenia and schizotypal personality disorder.

BACKGROUND: We examined differences in ventricular and sulcal cerebrospinal fluid-to-brain ratios as a function of lifetime psychiatric diagnosis in the offspring of schizophrenic mothers (high-risk sample) and in the offspring of normal parents (low-risk sample). METHODS: We used a cohort analytic study of 17 high-risk individuals with schizophrenia, 31 high-risk individuals with schizotypal personality disorder, 33 high-risk individuals with nonschizophrenia-spectrum psychiatric disorders, 45 high-risk individuals with no disorders, 31 low-risk individuals with psychiatric disorders of all types, and 46 low-risk individuals with no disorders, evaluated initially in 1962 when they were a mean age of 15 years, and reexamined from 1986 through 1989 with psychiatric interviews and computed tomographic scans of the brain. RESULTS: High-risk individuals with schizophrenia and schizotypal personality disorder evidenced an equivalent degree of cortical sulcal enlargement, and both groups evidenced significantly greater sulcal enlargement than did high-risk individuals with nonschizophrenia-spectrum disorders and no disorders and low-risk individuals with psychiatric disorders and no disorders. High-risk individuals with schizophrenia evidenced significantly greater ventricular enlargement than did high-risk and low-risk subjects with other disorders and no disorders, including those with schizotypal personality disorder. These differences were independent of age, gender, history of substance dependence, and history of organic brain syndromes and head injuries. CONCLUSIONS: Among the offspring of schizophrenic parents, cortical abnormalities are expressed equally across the range of syndromes in the schizophrenia spectrum. Subcortical abnormalities (ie, ventricular enlargement) are more pronounced in the more severe syndrome (ie, schizophrenia).

Adult↗
PubMed1994

The influence of parental socioeconomic status on CT studies of schizophrenia.

A sample of 19 DSM-III-R schizophrenics and 94 controls with no mental illness from the Copenhagen high-risk project was used to test the hypothesis that social class of origin is related to adult CT measures of ventricular, sulcal, Sylvian fissure and anterior interhemispheric fissure enlargement, cerebellar pathology, and brain volume. The schizophrenics and controls were divided into high and low SES-of-origin. No significant differences emerged between the high and low SES-of-origin subjects within the schizophrenic and control groups on any of the six CT measures.

Adolescent↗
PubMed1993

Developmental brain abnormalities in the offspring of schizophrenic mothers. I. Contributions of genetic and perinatal factors.

OBJECTIVE: We examined the contributions of genetic risk for schizophrenia and obstetric complications to brain morphological abnormalities in the offspring of schizophrenic and normal patents. METHODS: We used a cohort analytic study of 60, 72, and 25 individuals with neither, one, or two parents, respectively, who were affected with schizophrenia spectrum disorders, evaluated initially in 1962 when they were on average 15 years old, and reexamined from 1986 through 1989 with psychiatric interviews and computed tomographic scans of the brain. RESULTS: After controlling for the effects of age, gender, substance abuse, and history of organic brain syndromes and head injuries, there were significant stepwise, linear increases in cortical and ventricular cerebrospinal fluid-brain ratios with increasing level of genetic risk for schizophrenia. Genetic risk for schizophrenia also interacted with prospectively assessed birth complications in predicting selectively to enlargement of the ventricular system; ie, the effect of birth complications on ventricular enlargement was greater among those with two affected parents compared with those with one affected parent, and greater among those with one affected parent compared with those with normal parents. Perinatal exposure to ether anesthesia was associated with a generalized increase in brain abnormality, which varied in severity according to level of genetic risk for schizophrenia. CONCLUSIONS: The type and degree of brain abnormalities shown by adult offspring of schizophrenic and normal parents are strongly predicted by the independent and interacting influences of genetic risk for schizophrenia and obstetric complications. The findings further substantiate the hypothesis that structural brain abnormalities in schizophrenia are at least in part neurodevelopmental in origin.

Adolescent↗
PubMed1992

Quality of urography and renal clearance of ionic and nonionic contrast media.

The authors evaluated whether urographic quality correlated with patient hydration and the level of their renal function, depending on whether they received ionic or nonionic contrast media. One hundred patients with normal serum creatinine levels were randomly assigned to receive intravenous urography with either an ionic high-osmolar or a nonionic low-osmolar contrast medium. Patient hydration was evaluated by measuring urine osmolality in a sample voided just before the examination. The plasma concentration of iodine was determined in a single blood sample drawn approximately 3 hours later. From these determinations the plasma clearance of contrast medium was calculated. The urograms were assessed blindly with regard to nephrographic and pyelographic opacification, as well as overall diagnostic quality. The clearance varied between 42 and 115 mL x minutes-1 x 1.73 m-2. No systematic correlation of practical significance was found between the clearances and the urogram quality. A high urinary osmolality before the examination tended to improve quality with both media. It is not possible to assess glomerular filtration rate from nephrographic and pyelographic opacification, or from overall quality of routine urograms in patients with normal serum creatinine levels.

Adult↗
PubMed1992

One or two samples for determination of total plasma clearance of a nonionic contrast medium in patients undergoing enhanced CT.

Plasma clearance of nonionic iopamidol (300 mg I/ml) was measured in 50 patients in connection with enhanced CT. Before injection of either 50 or 100 ml of the contrast medium, S-creatinine and urine osmolality were measured. Employing Renalyzer PRX 90, the plasma concentration of iodine was determined in blood samples drawn approximately 3 and 4 h after injection of iopamidol. The glomerular filtration rate was calculated by the Renalyzer using 2 different formulas, one requiring only a single sample, and one requiring at least 2 samples (standard). Both the 3- and 4-h single sample values correlated well with the glomerular filtration rate expressed by the standard sample value. The result was independent of whether 50 or 100 ml had been administered and whether or not water soluble contrast medium had been given orally before CT. As could be expected S-creatinine and urine osmolality correlated poorly with the clearance values. It is concluded that in patients receiving either 50 or 100 ml contrast medium for enhanced CT, the glomerular filtration rate can be determined in a single sample as well as with 2 samples taken between 3 and 4 h after contrast medium injection.

Adult↗
PubMed1991

Renal clearance of an ionic high-osmolar and a nonionic low-osmolar contrast medium.

One hundred patients with normal serum creatinine concentration underwent intravenous urography with either an ionic high-osmolar (diatrizoate) or a nonionic low-osmolar (iopamidol) contrast medium after randomization. Before injection of the contrast medium, a blood sample was drawn for determinating serum creatinine concentration, and a urine sample for measurement of urine osmolality. Using x-ray fluorescence, the plasma concentration of iodine (contrast medium) was determined on blood samples drawn approximately 3 and 4 hours after injection of the contrast medium. The glomerular filtration rate was calculated by two different formulas: one requiring only a single sample and one requiring at least two samples (standard). There were poor correlations between the standard contrast medium clearance and the serum creatinine concentration, the estimated creatinine clearance (calculated from a nomogram), as well as the urine osmolality. The 3-hour and the 4-hour single-sample values correlated well with the two-sample values for both contrast media. In patients with normal serum creatinine, the glomerular filtration rate determined by measuring the contrast medium concentration in a single plasma sample obtained at 3 hours, is almost identical to the value determined from two samples. Consequently, two samples are unnecessary.

Adult↗
PubMed1991

Central nervous system reactions to cervical myelography.

In a double blind prospective study of side effects to cervical myelography 38 patients were evaluated with neurologic examination, electroencephalography (EEG), brainstem evoked response (BER), somatosensory evoked responses (SSER), and continuous reaction times prior to and at 6 h and 24 h after myelography with either metrizamide or iohexol. A difference in the incidence of side effects (for example headache, dizziness, nausea, and neck pain) to the two different contrast media indicated that the inconveniences related to myelography were not only due to the spinal puncture. A contrast medium effect on the central nervous system varying from one agent to another was present. A high frequency of EEG deteriorations among patients with adverse clinical reactions and on only discrete affection upon BER indicated the reaction to be located to the cerebral cortex. Weakened tendon reflexes and reduced strength in the upper extremities were probably caused by blockade in the motor roots as SSER were normal indicating no affection of the sensory pathways. This hypothesis is in agreement with the fact that the patients were in the prone position in the first phase of the investigation causing the highest concentration of contrast medium around the motor roots and the anterior part of the spinal cord. Difference in metabolic effect may explain differences in side effects of metrizamide and iohexol.

Adult↗
PubMed1990

Magnetic resonance imaging, computed tomography, and myelography in the diagnosis of recurrent lumbar disc herniation.

Thirteen patients with recurrent symptoms after lumbar discectomy were evaluated. All the patients were enrolled in the study on the basis of clinical symptoms and signs only. The patients were examined with MRI, CT, and myelography in order to compare a) the clinical findings with the imaging investigations, b) the predictive value of the different investigations, and c) the clinical and investigative results with the operative findings. All patients were operated upon according to the clinical findings, and the surgical results were used as the final diagnosis. In six patients a new disc herniation was detected. In the remaining cases surgery revealed either scar tissue or nothing to explain the recurrence of the symptoms. The three imaging modalities were analysed by receiver operating characteristic (ROC) curves. The areas under the ROC curves were 0.68 for MRI, 0.83 for CT, and 0.43 for myelography. The difference in areas between CT and myelography was significant (p less than 0.05). The results indicate that CT has the highest predictive value for demonstrating the recurrence of a lumbar disc herniation.

Adult↗
PubMed1990

The limited value of routine chest X-ray in the follow-up of stage II breast cancer.

In 280 patients with stage II breast cancer, chest X-ray was performed at 6 and 12 months and yearly thereafter to the 6th year or until recurrence, another cancer was detected, the patient refused further follow-up or died. Among 1289 scheduled chest X-rays, malignant changes were found in 20 patients, of which only 3 had pulmonary symptoms. In a further 14 patients malignant changes were suspected, but follow-up examinations could not prove malignancy. 26 patients presented within 12 months after the last scheduled X-ray with pulmonary symptoms and a work-up chest X-ray revealed malignant changes. Thus, in only 1.3% of the scheduled X-rays were unsuspected malignant changes diagnosed. Median survival of patients with malignant chest X-rays found at scheduled controls versus between scheduled controls did not differ significantly (P = 0.26). It is concluded that routine chest X-ray is not indicated in patients with stage II breast cancer.

Adult↗
PubMed1989

The value of yearly chest X-ray in patients with stage I breast cancer.

In 263 patients with stage I breast cancer, i.e. tumour less than 5 cm in diameter, no invasion of skin and deep fascia, and no involvement of axillary lymph nodes, X-rays of the chest were performed at 6, 12 months and yearly thereafter to the 6th year or until recurrence, another cancer was detected, the patient refused further follow-up or died. Among 1599 examinations, in only 0.25% (four patients) were unsuspected malignant changes observed. Due to this low cost/benefit ratio a fixed routine schedule of repeated chest X-rays in stage I cancer patients, otherwise apparently free of disease, is not justified.

Breast Neoplasms↗
PubMed1989

High density lipoprotein cholesterol and arteriography in intermittent claudication.

Overnight fasting plasma lipoprotein and lipid concentrations were measured in a group of 76 patients with peripheral arterial disease (PAD)--main symptom: intermittent claudication--and compared to those of 21 controls, matched with the patients according to age, sex, body-mass index, alcohol and tobacco consumption, but without any signs of peripheral arterial disease. Significantly lower median values of high density lipoprotein cholesterols (HDL-C) (P less than 0.01), and significantly higher median values of low density lipoprotein cholesterols (LDL-C) (P less than 0.05) were found in the PAD group. The results also showed significantly lower ratios of HDL-C/LDL-C and HDL-C/total cholesterol in the PAD group when compared to the controls (both P less than 0.005). No significant differences were demonstrated concerning very low density lipoprotein, total cholesterol, or triglyceride plasma concentrations. Evaluation of arteriograms showed a significant negative correlation between HDL-C concentrations and the extent of arteriosclerotic lesions in the lower extremities (P less than 0.05). Thus, not only were the HDL-C and LDL-C levels different in the PAD group, but we also found a correlation between HDL-C and the severity of vascular disease.

Adult↗
PubMed1987

Contact thermography, 99mTc-plasmin scintimetry and 99mTc-plasmin scintigraphy as screening methods for deep venous thrombosis following major hip surgery.

Fifty-six patients scheduled for total hip alloplasty were screened for deep venous thrombosis by means of 99mTc-plasmin scintimetry, 99mTc-plasmin scintigraphy and contact thermography. Investigations were performed on the seventh postoperative day, and a total of 112 legs were examined. Bilateral ascending phlebography was used as reference procedure, and the criteria for deep venous thrombosis were intraluminal filling defects at phlebography. Six patients developed unilateral deep venous thrombosis. All three screening procedures revealed many false positive and several false negative results. The nosographic sensitivity/specificity was 33%/75% for scintimetry, 50%/91% for scintigraphy and 33%/87% for contact thermography, respectively. It is concluded that all three tests are of no value as screening methods for deep venous thrombosis following major elective hip surgery.

False Negative Reactions↗