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Biomedical subjects

T Solberg

Publications and source records attributed to T Solberg.

16 recordsLinked to original sources
PubMed1999

First radiotherapy of human metastatic brain tumors delivered by a computerized tomography scanner (CTRx).

PURPOSE: This Phase I study was designed to evaluate the computed tomography (CT) scanner as a device for radiation therapy of human brain tumors (CTRx). This first use in humans of a modified CT for treatment was founded on extensive research experience with canine tumors. An additional objective was to increase the therapeutic radiation dose to tumors compared to normal tissue by concentration of infused contrast material in tumors, an effect available at diagnostic x-ray energies but not at megavoltage energies. METHODS AND MATERIALS: A small metastatic brain tumor in each of eight patients received 3-5-weekly fractions of 5 Gy equivalent per fraction from a CT scanner modified to deliver radiation therapy. In each patient, one additional tumor, lying completely outside the volume treated by CTRx, served as a control. The tumor receiving CTRx was treated after infusion of iodinated x-ray contrast media (CM) for dose enhancement. Many of these patients also received conventional 40 Gy whole brain radiation, before, during, or after CTRx treatment. RESULTS: None of the patients showed adverse reactions to the CM or necrosis of the normal brain from the CTRx boost radiation. Monte Carlo calculations of the radiation dose distributions in a model tumor showed that the CTRx irradiation of tumors carrying 10 mg or more of iodine per gram of tumor was as good or better than the dose distribution from conventional 10-MV X-rays. The treated tumor in two of the patients vanished after four treatments, whereas a control tumor in one patient remained constant and grew 4-fold in another patient. CONCLUSION: The CTRx concept effectively combines a modified CT scanner as a diagnostic device, as a simulator dedicated to radiotherapy, and as a treatment machine. Thus, CTRx could be very useful for radiation oncologists in controlling CM-enhanced and other small brain tumors.

Brain Neoplasms↗
PubMed1999

[Nerve biopsy].

Nerve biopsy, if undertaken at centres with appropriate expertise, may be a valuable diagnostic procedure in selected patients with peripheral neuropathy. Sural nerve biopsy and skin biopsy for evaluation of epidermal nerves are described. Indications, surgical procedure, preparation and transport are reviewed. Usually the patient has to be admitted to a hospital with the necessary resources for a comprehensive battery of nerve tissue processing, including teasing and electron microscopical examination, and other investigative procedures. Another option, when practically and economically feasible, is to obtain sural nerve biopsy from several (2-4) patients performed by a skilled surgeon at the local (central) hospital. A technician from a neuromuscular centre or laboratory of neuropathology should be at the site to provide immediate and proper preparation and transport of the tissue samples. An example of peripheral nerve vasculitis with teased nerve fibers in early and late axonal degeneration is presented as an illustration. Sural nerve biopsy is useful in selected cases, particularly in order to demonstrate peripheral nerve vasculitis. For detection of small fiber neuropathy in the investigation of painful neuropathies, skin biopsy for evaluation of epidermal nerves may be an appropriate alternative.

Biopsy↗
PubMed1999

Postoperative nerve root displacement and scar tissue. A prospective cohort study with contrast-enhanced MR imaging one year after microdiscectomy.

PURPOSE: To investigate the association between postoperative nerve root displacement and epidural scar tissue. MATERIAL AND METHODS: One hundred patients who had undergone lumbar microdiscectomy were included in a prospective cohort study with a 1-year follow-up. The patients were classified as failures or successes at the 12-month follow-up according to a clinical score. Patients with signs of recurrent disc herniation on MR were excluded from the study. All the 13 patients classified as failures were investigated with MR at the 1-year follow-up, and 40 patients classified as successes were picked at random for MR imaging; thus MR was performed in 53 patients. The MR images were independently evaluated by two neuroradiologists. The images were rated according to the presence or absence of nerve root displacement at the surgically treated disc interspace. Scar formation was rated according to two different classification systems. RESULTS: Nerve root displacement was observed in 13 patients. No evidence of scar formation was found in 4 patients, a small amount in 11, intermediate in 37 and extensive scar formation in 1 patient. No association between nerve root displacement and the amount of scar tissue was found. CONCLUSION: Postoperative nerve root displacement seems to be an independent clinical entity not associated to postoperative scar tissue.

Adult↗
PubMed1998

The request.

Explore the source record for details and available documents.

Human-Animal Bond↗
PubMed1997

X-ray phototherapy for canine brain masses.

Brain masses diagnosed in 47 pet dogs as tumors by CT scans, and confirmed in 12 dogs by necropsies, were injected with iodinated contrast media and treated by a modified CT scanner, the CTRx. Twenty-six dogs that received six or more weekly treatments of about 5.6 Gy per fraction, of which about 25% was contributed by radiation from the iodine, for a median total dose of 39 Gy, had a median survival of 230 days. This compares well with the 150 days reported for 25 dogs given 46-48 Gy of cobalt-60 radiation to the whole brain, and is significantly greater than the 6 to 13 days in untreated historic controls.

Animals↗
PubMed1994

Application of stereotactic radiosurgery to the head and neck region.

Nasopharyngeal carcinoma recurrent following primary radiation therapy has been treated with surgery and reirradiation. Reirradiation is often limited by the tolerance of structures previously treated. Radiosurgery was used to boost the recurrent site while avoiding critical structures. Seven patients were evaluated for treatment. Three patients met requirements for treatment. The lesions invaded the parapharyngeal region, the base of skull, cavernous sinus, cranial nerves, or carotid artery. Treatment included a radiosurgery boost utilizing multiple isocenters, noncoplanar arcs, and arc weighting, to yield a plan conforming to the tumors while avoiding critical anatomical structures. The patients tolerated the procedure well with minor acute side effects. Follow-up included magnetic resonance imaging (MRI) and positron emission tomography (PET). Two lesions responded, and one had no significant change. One patient had a regional recurrence. Two patients had distance recurrence. Long term side effects include trismus, parotiditis, ear fullness, hemorrhage, and pain. Radiosurgery may improve the local control rate of such lesions, however, with the severe long term complications of single fraction radiosurgery in the head and neck region this procedure may be more beneficial if the treatment is fractionated.

Follow-Up Studies↗
PubMed1994

Acceptance testing prone stereotactic breast biopsy units.

When the Mammography Quality Standards Act becomes law in October, 1994, stereotactic breast biopsy units may require yearly physicist calibration. Upright stereotactic units can be easily tested using conventional mammography procedures and a gelatin phantom containing simulated calcifications, but prone units are difficult to assess because of the under-table tube configuration. The two current manufacturers of these units have made different design decisions which affect each unit's calibration. There are a number of important distinctions between screening and prone biopsy units. For the two currently available prone units, a pronounced heel effect makes ion chamber position critical. Focal spot measurements are particularly difficult on one unit because there is no light field. The fixed grid on the other unit must be tested with a flood film. Physicists who inspect these units before their clinical use should be aware of variations needed by this equipment for specific acceptance tests.

Biophysical Phenomena↗
PubMed1993

Radiosurgery of cavernous sinus tumors.

Stereotactic radiosurgery was applied to concentrate high dose of photon irradiation to tumors enclosed in the cavernous sinus. We have treated 10 meningiomas, five pituitary tumors, and three metastatic lesions in the past two years. Follow-up time ranges from 3 to 18 months with an average of 10 months. Tumor volume ranged from 0.92 to 53.31 cc with an average 10.79 cc. CT scans and MRIs were used to demonstrate the tumor relationship to cranial nerves and structures of the brain. One to 6 isocenters were used. Collimator size varied from 7 to 28 mm, and the dose to the margin of the tumor ranged from 1400 to 2500 cGy with an average of 1650 cGy. Maximal dose range of 1575 to 5000 cGy. The margin of the tumor was encompassed within the 50 to 95% isodose volume with an average treatment prescribed to the 57% isodose volume. Symptomatic response was seen in 12 patients, and stabilization of symptoms in three patients with progression of symptoms observed in three patients. Radiographic imaging revealed response in eight patients, unchanged in three patients and progression in three patients. This report shows the feasibility of applying linear accelerator radiosurgery to the treatment of cavernous sinus tumors. This form of therapy promises to play an important role in complementing tumor resection.

Adult↗
PubMed1993

Comparison between radiosurgery and stereotactic fractionated radiation for the treatment of brain metastases.

This study evaluates the treatment of intracerebral brain metastases with single dose stereotactic radiosurgery in comparison to stereotactic fractionated radiotherapy (SFR). Twenty six patients with 41 lesions were evaluated. Thirty four lesions in 19 patients were treated with radiosurgery, and 7 lesions in 7 patients were treated with SFR. The radiosurgery group was treated with an average number of isocenters of 1.4, and an average of 9 arcs. The average dose was 2140 cGy delivered to the 70% isodose line. The average volume of the lesions was 5.22 cc. The SFR group lesions received a mean dose to the indicated area delivered by 4 to 6 coplanar fields. The dose was 600 cGy per fraction, 2 to 3 fractions were given. The average volume of the treated lesions was 21.2 cc. Follow-up extended from 2-18 months. Twenty five lesions of the radiosurgery group had image follow-up. The overall local control was seen in 92% of the patients. Six lesions of the SFR group had image follow-up, the local control was 83%. The small number in each group, the non-randomized nature of the study, and the relatively short follow-up preclude a definitive conclusion. SFR may be the method of choice for large lesions surrounded by significant edema. The delivery of the dose in large fractions may obviate the transient acute reactions seen when radiosurgical dose is delivered to large lesions surrounded by edema. However, both forms of therapy have proven to be effective in the control of brain metastases.

Adult↗
PubMed1993

Substrate preference of isolated perfused rat hearts during hypothermia and rewarming.

Fatty acid and glucose oxidation rates were measured in isolated rat hearts undergoing hypothermia and rewarming. The hearts were perfused in the Langendorff mode with Krebs-Henseleit bicarbonate buffer containing 11.1 mM glucose plus 0.6 mM albumin-bound oleic acid as energy substrates. The hearts were stabilized at 37 degrees C and thereafter cooled progressively to 15 degrees C over a period of 60 min. The hearts were kept at this temperature for 10 min and then rewarmed to 37 degrees C during the next 30 min. Control hearts were perfused at 37 degrees C throughout the whole perfusion period. Trace amounts of [14C]glucose or [14C]oleic acid were included in the perfusate, and the rate of substrate oxidation was determined on the basis of the radioactive CO2 production. In normothermic hearts steady state oxidation rates of glucose and oleate were found to be 0.17 +/- 0.01 and 0.51 +/- 0.07 mumol min-1 g-1 dry wt, respectively (mean +/- SEM). In response to hypothermia (15 degrees C) glucose oxidation was reduced by 76% (from 0.17 +/- 0.01 to 0.04 +/- 0.01 mumol min-1 g-1 dry wt) and oleate oxidation by 47% (from 0.51 +/- 0.07 to 0.27 +/- 0.02 mumol min-1 g-1 dry wt). Upon rewarming glucose and fatty acid oxidation rates returned to essentially the same values (0.12 +/- 0.02 and 0.45 +/- 0.04 mumol min-1 g-1 dry wt) as those observed under steady state normothermic conditions. The molar ratio between glucose and fatty acid oxidation was, however, significantly (P < 0.05) lower in hypothermic than in normothermic hearts.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1986

Hypotony and retinal detachment.

The present work has been based on the assumption that the decreased intraocular pressure in eyes with retinal detachment is due to an abnormal posterior aqueous outflow, in addition to the normal anterior pathways. Subretinal fluid may leak out either through the peri-optic connective tissue or across the retinal pigment epithelium. In order to test the validity of these alternatives against clinical observations, a fluid dynamic model has been developed to calculate intraocular pressure-drop versus detached area in both cases. In contrast to the choroidal alternative, the numerical results from the peri-optic route exhibit qualitative agreement with clinical observations. It is concluded that both clinical and theoretical findings lend support to the hypothesis that the intraocular pressure-drop in eyes with retinal detachment is due to drainage of subretinal fluid via the peri-optic tissue.

Aqueous Humor↗
PubMedDate not supplied

Testing mammography equipment: evolution over a 4-year period.

The results of quality control (QC) tests on 70 mammography units in Southern California from 1986 to 1990 are reported. Thirteen facilities, selected because they housed all of the mammography units in three communities involved in a National Institutes of Health research project, had their units tested twice at an interval of 1 year. Fourteen self-selected units were also tested twice at intervals ranging from 1-3 years. Forty-three self-selected units in 31 additional facilities had testing only once. All 70 units underwent measurement of focal spot size or resolution, tube output, half-value layer (HVL), automatic exposure control (AEC) accuracy, relative kVp accuracy, mean glandular dose, and imaging of several test objects. The test results for the units tested once showed no significant differences compared to those tested twice. For the latter, once the units were tested and determined to be acceptable, retesting showed differences only in overall film optical density, dose, and AEC performance.

Ambulatory Care Facilities↗
PubMedDate not supplied

[Quality changes in iced shrimps (Pandalus borealis). I. Changes in the contents of trimethylamine oxide and volatile nitrogen bases and bacteria in raw shrimps after different storage periods compared with organoleptic examinations (author's transl)].

On the basis of two experiments on the storage of raw shrimps (Pandalus borealis) in ice and on samples taken out from different trawlers after different days at sea, we have attempted to find the criteria of choice for the lower limit of quality of raw shrimps which are meant for further processing for human consumption. A content of TVN of approximately 50 mg/100 g peeled shrimp and a content of TMA-N of approximately 10 mg/100 g peeled shrimp probably represent such an objective lower limit if a comparison with organoleptic assessment is made. Assuming suitable storage conditions, this corresponds to a maximum period of 7 days. In this paper we have also attempted to find the content of TMAO in fresh raw shrimps from different fishing grounds in the Barents sea and off the Eastern coast of Greenland. The content of TMA-N was found to vary from 166 to 211 mg/100 g peeled shrimp.

Bacteria↗
PubMedDate not supplied

[Quality changes in iced shrimps (Pandalus borealis). II Changes in the contents of trimethylamine oxide and volatile nitrogen bases during automatic boiling and peeling (author's transl)].

Post mortem trimethylamine oxide (TMAO) in marine animals is reduced to trimethylamine (TMA), and the degradation of proteins causes an increase in the ammonia (NH3) content. During ice-storage NH3 and TMA usually make up the major part of the total content of volatile nitrogen bases (TVN) which are formed during the degradation process. The formation of TMA and NH3 is probably caused mainly by bacterial enzymes. The contents of TMA and TVN in marine fish and shrimps are important objective criteria in supporting organoleptic examinations of such raw materials. During automatic boiling, peeling and rinsing processes in shrimp factories, some of these water-soluble and volatile compounds will be extracted by the boiling water and possibly evaporated. In this investigation we have attempted to estimate the loss of TMAO, TMA and TVN in shrimp muscle during this automatic processing. The investigation includes experiments in the laboratory (Table I, Figure 1) and in two factories (Table II-III, Figure 2-3). The results show that about 50% of the contents of TMAO-N, TMA-N and TVN probably will be lost from the shrimps during automatic processing. Adding approximately 100% TMA-N and TVN to the analysed contents in boiled, peeled and rinsed shrimps will therefore probably give the same level of these compounds as that found in the raw shrimps used. An accurate measurement of the TMA- and TVN-content in shrimp produced under known condition in North-Norwegian shrimps factories could give an objective indication of the quality of the raw shrimps used. In accordance with Norwegian shrimp regulations, only the fresh, healthy shrimps are allowed to be produced.

Food Handling↗
PubMedDate not supplied

[Quality changes in iced shrimps (Pandalus borealis). III. Indole and pH in shrimps caught in the Barents Sea compared with shrimps caught in the Far East (author's transl)].

The content of indole and the pH have been determined post mortem in shrimps (Pandalus borealis) caught in the Barents Sea and in shrimps caught outside Malaysia, India and Taiwan. These two criteria were compared with organoleptic assessment and the contents of volatile nitrogen bases (ammonia, trimethylamine) and living bacteria. For shrimps caught in the Barents Sea, both raw shrimps stored in ice and processed (broiled, peeled and single-frozen) shrimps were investigated. The results showed that only low levels of indole had been formed during ice-storage. Not until an advanced state of spoilage could a distinct increase in the indole content in raw and in boiled, peeled shrimps be discerned. pH increased slowly and varied in the area between acceptable and not acceptable quality. Neither the indole content nor the pH seems therefore to be a useful criterion for quality assessment either of raw shrimps caught in the Barents Sea or of such shrimps after processing (boiling and peeling). Most of the samples of boiled, peeled shrimps from the Far East were assessed organoleptically as less good-spoiled, and bacterial growth was significant. The content of trimethylamine oxide and volatile nitrogen was low, while the content of indole was high and exceeded 25 microgram/100 g in 8 or 14 samples. This is the upper limit for import in USA. The content of indole seems to be an important quality criterion for shrimps caught in warmer countries. The content of indole exceeded 25 microgram/100 g in some samples which were assessed organoleptically as acceptable. The pH was lower in brine-treated shrimps than in the others.

Animals↗