Search PubMed⌕ Search

Biomedical subjects

B Lind

Publications and source records attributed to B Lind.

At least 109 records · Page 6Linked to original sources
PubMed1987

Radiotherapeutic computed tomography with scanned photon beams.

Radiotherapeutic computed tomography is a powerful technique to generate anatomical transversal tomograms of the patient in treatment position by using the therapy beam from the treatment unit. For this purpose the treatment unit has to be equipped with a detector array that can detect the beam transmitted through the patient and a computer that analyzes the data and performs the back projection. When the treatment unit uses scanned elementary photon beams, the only practical technique available for generating high quality high energy photon beams, the operation principle and, to some extent, the image quality is similar to that of a 3rd generation CT-scanner. The optimum choice of detection geometry and type of radiation detectors for radiotherapeutic computed tomography particularly at high photon energies are discussed indicating the merits of BGO (bismuthgermanate) or CWO (cadmiumtungstate) photodiod arrays. The first tomographic images of a thorax phantom at an acceleration potential of 50 MV using such detectors are presented. The image contrast is similar to that for 300 kV X rays mainly because the considerable influence of pair production at 50 MV. Line spread and modulation transfer functions are presented indicating a resolution of the order of two millimeters using a crystal thickness of 5 mm. The advantages with radiotherapeutic computed tomography, beside forming a new general communication channel between different diagnostic techniques, dose planning, and radiation delivery, are the elimination of position errors and the provision of exact attenuation data for dose planning.

Humans↗
PubMed1987

Odontoid fractures treated with halo-vest.

In a consecutive series of 75 patients with unstable cervical spine injuries treated with halo-vest, 1976-1984, a total of 14 patients (comprising 18.7%) had odontoid fractures. Of the patients with odontoid fractures, 1 patient had an incomplete tetraparesis. All patients except 1 were treated within the first day after the trauma. A total of 50% were injured in motor vehicle accidents. The odontoid fracture was reduced by skull traction and then stabilized with a halo-vest for 12 weeks. One patient died within the first 2 weeks after the injury. There were no other serious complications during the treatment. The initial dislocation and reduction was studied. Ten patients were followed-up after 2 years. Another 2 patients died of other causes during that time. One had an Anderson-d'Alonzo Type II fracture that failed to unite. Different prognostic factors were analyzed. Fracture gap and fracture type may have contributed to nonunion. Only 1 patient was totally free from symptoms after 2 years. The halo-vest was well tolerated in all patients and assured a high percentage of healing.

Adult↗
PubMed1987

Influence of halo vest treatment on vital capacity.

Respiratory function (vital capacity) was studied in 20 consecutive patients with unstable cervical spine injuries treated with a halo vest. Eight patients were neurologically intact. Twelve patients had incomplete spinal cord injuries that were classified on a neurologic function scale (Sunny-brook) immediately and 3 months after injury. Spirometric tests were done within 1 week of halo vest fixation, after 3 months of treatment, and 1 week after dismounting of the halo vest. The results showed that initial vital capacity was smaller than predicted normal in all patients and 30% less in neurologically impaired patients. Both groups improved during the treatment and somewhat more after removal of the halo vest. In neurologically intact patients, the halo vest caused a respiratory restriction of 10%, which was fully regained after removal of the halo vest. The difference between the groups remained throughout the study. There was no evidence that the halo vest itself affects the vital capacity more in patients with incomplete cord lesions than in neurologically intact patients. All of the cervical spine injuries healed uneventfully.

Adolescent↗
PubMed1987

Intensive care: cost and benefit.

This study presents a review of 961 patients treated in the general intensive care unit (ICU) of Akershus Central Hospital (ACH) from 1978 to 1981, including also a follow-up study of the 419 patients treated in 1978 and 1979 who were observed for an average period of 20 months after admittance to the ICU. The ICU patients represented 1.7% of all the patients admitted to the referring departments. Approximately 2/3 (67.3%) of the patients were surgical patients, representing 2.9% of the patients treated in that department, 19.6% were medical patients, and 8.6% came from the department of pediatrics. Surgery was the main reason for ICU admittance in 48.1% of the patients; in 70% of these, surgery by itself made postoperative intensive care necessary. Acute or chronic cardiovascular or respiratory disorders caused or contributed to ICU admittance in 78% of the patients; disorders of the nervous system (29.0%), gastrointestinal system (25%), and severe infections (28%) came next. The average stay in the ICU was 6.2 days. The patient's need for observation, nursing and therapy was assessed daily according to a care grade scale from 1 to 5, with 5 as maximum effort. The average care grade during the stay, multiplied by the duration of stay in days, gave the care product, which was used as an expression of the patient's need for ICU resources. The sum of care products for all the patients through 1 year thus expressed the total work load on the ICU. The ICU budget for 1 year, divided by the total care product for the same year, and thereafter multiplied by the care product for single patients or patient groups, was used as the basis for calculation of ICU costs. Patients receiving mechanical ventilation required 95% of the total work load in the ICU, and 66.3% of these efforts were directly associated with the ventilator treatment period as judged by the care product. Complications to treatment were recorded in 7.3% of the patients, and four of these patients dies of such complications. Improvement by intensive care was achieved in 81.4% of the patients, 5.2% were unchanged, and 13.4% died while in the ICU. Mortality was 9.5% below and 19.3% above the age of 60 years. Of the 419 patients who were followed for an average period of 20 months after admittance to the ICU, 56 died in the ICU, 28 died later during the same stay in ACH, and another 47 died after discharge from ACH, whereas 288 (68.7%) were still alive.(ABSTRACT TRUNCATED AT 400 WORDS)

Cost-Benefit Analysis↗
PubMed1987

Mercury concentrations in the human brain and kidneys in relation to exposure from dental amalgam fillings.

Samples from the central nervous system (occipital lobe cortex, cerebellar cortex and ganglia semilunare) and kidney cortex were collected from autopsies and analysed for total mercury content using neutron activation analyses. Results from 34 individuals showed a statistically significant regression between the number of tooth surfaces containing amalgam and concentration of mercury in the occipital lobe cortex (mean 10.9, range 2.4-28.7 ng Hg/g wet weight). The regression equation y = 7.2 + 0.24x has a 95% confidence interval for the regression coefficient of 0.11-0.37. In 9 cases with suspected alcohol abuse mercury levels in the occipital lobe were, in most cases, somewhat lower than expected based on the regression line. The observations may be explained by an inhibition of oxidation of mercury vapour. The regression between amalgams and mercury levels remained after exclusion of these cases. The kidney cortex from 7 amalgam carriers (mean 433, range 48-810 ng Hg/g wet weight) showed on average a significantly higher mercury level than those of 5 amalgam-free individuals (mean 49, range 21-105 ng Hg/g wet weight). In 6 cases analysis of both inorganic and total mercury was carried out. A high proportion (mean 77% SD 17%) of inorganic mercury was found. It is concluded that the cause of the association between amalgam load and accumulation of mercury in tissues is the release of mercury vapour from amalgam fillings.

Adolescent↗
PubMed1986

Concentrations of arsenic in urine of the general population in Sweden.

The concentration of the sum of the metabolites of inorganic arsenic (inorganic arsenic, methylarsonic acid and dimethylarsinic acid) as well as the concentration of organic arsenic compounds, mainly in the form of arsenobetaine, in the urine of human subjects from two cities in Sweden have been studied. The median concentration of metabolites of inorganic arsenic was approximately 8 micrograms As/g creatinine, independent of place of residence, sex, smoking and consumption of beer and wine. However, subjects who frequently ate flatfish and crustacea had somewhat higher (1.5 times) concentrations than those who very seldom ate such food. Flatfish, mainly in the form of plaice, and crustacea were found to be the main source of organic arsenic compounds. Subjects eating this type of seafood more than once a week had approximately 40 micrograms organic As/g creatinine (median value), compared with about 12 micrograms organic As/g creatinine in subjects who very seldom ate it. Other types of seafish or freshwater fish did not give rise to elevated concentrations of arsenic in the urine. The total range of organic arsenic compounds in urine was less than 1 to 525 micrograms As/g creatinine.

Adult↗
PubMed1986

Distribution and concentration of cadmium in human kidney.

The left kidneys from twenty males, aged 30 to 59, were examined. On an average, the cortex, medulla, and the remainder (renal pelvis and adjacent fatty tissue) constituted 65, 27, and 8 percent of the whole kidney weight, respectively. The mean cadmium concentrations were 18.4, 6.9, and 3.2 micrograms Cd/g wet wt, respectively. The mean whole kidney cadmium concentration was 14.4 micrograms Cd/g wet wt. The kidney cortex concentration of cadmium can be approximated by multiplying the whole kidney concentration by a factor of 1.25, which is somewhat lower than the factor of 1.5 previously used. It may be necessary to recalculate previously reported estimates of critical concentrations for cadmium in kidney cortex based on neutron activation analyses in vivo of whole kidney.

Adipose Tissue↗
PubMed1986

Increased lead concentration in brain and potentiation of lead-induced neuronal depression in rats after combined treatment with lead and disulfiram.

The effects of disulfiram (tetraethylthiuram disulfide) on blood and brain lead levels and on lead-induced changes in growth and cerebellar Purkinje neuron excitability were assessed in adult Sprague-Dawley rats. Disulfiram is metabolized to diethyldithiocarbamate, which forms a lipophilic complex with lead, and can thereby influence the tissue distribution of lead. Pregnant rats were exposed to 0.25% lead acetate or an equimolar amount of sodium acetate in the drinking water, and these treatments were continued for 4 weeks after birth. Half of the mothers from each group were given 0.1 mmole/kg disulfiram orally twice a week until parturition, after which the treatment was continued for 4 weeks in the respective pups in the form of subcutaneous injections. Although lead exposure markedly increased blood lead levels, the increase in brain lead levels was much more modest. Disulfiram markedly increased brain lead levels while blood lead levels in this group were only slightly elevated as compared to animals receiving lead alone. In addition, the lead + disulfiram group had depressed weight gain during maturation, and Purkinje neuron firing rates were reduced. The lead alone and disulfiram alone groups were not different from controls in these respects. These data suggest that disulfiram potentiates the adverse effects of lead on growth rates and on cerebellar Purkinje neuron function by facilitating the accumulation of lead in brain tissue.

Animals↗
PubMed1986

Decreased blood lead levels in residents of Stockholm for the period 1980-1984.

A number of measures have been taken to decrease the spread of lead to ambient air and food. In a study of the effect of these and other preventive measures, blood samples from approximately 100 persons living in the inner city area of Stockholm were collected and analyzed for lead content on three different occasions, in 1980, 1983, and 1984. The same subjects were examined on at least two occasions and the analytical method, atomic absorption spectrophotometry, was carefully controlled by means of reference samples on each occasion. The blood lead levels decreased during the observation period. The average blood lead concentrations for all the examined persons were 0.37, 0.26, and 0.25 mumol/l for 1980, 1983, and 1984, respectively. The mean of the differences in individual blood lead levels for 1980 and 1984 was 0.12 mumol/l. This figure corresponds to an average decrease in blood lead of 34% for all the subjects examined in 1980. The decrease occurred mainly during the period 1980-1983 (mean 0.11 mumol/l) and, thereafter, was only slight for the period 1983-1984 (mean 0.01 mumol/l). Factors such as age, sex, and change of residence during the observation period did not influence the final results.

Adult↗
PubMed1985

Increased lead levels in brain after long-term treatment with lead and dithiocarbamate or thiuram derivatives in rats.

Lead concentrations in blood and brain were measured in rats exposed to lead via drinking water, 0.25% Pb (12 mM), and dithiocarbamate/thiuram derivatives administered by gavage singly or in combination for 6 weeks. Sodium salts of diethyldithiocarbamate (DEDTC) and dimethyldithiocarbamate (DMDTC) were given in doses of 0.2 mmol/kg and tetramethylthiuram disulfide (thiram) and tetraethylthiuram disulfide (disulfiram) in doses of 0.1 mmol/kg twice a week. In rats that received lead plus dithiocarbamate/thiuram derivatives lead concentrations in blood and brain were significantly increased; disulfiram being most effective in increasing lead levels, followed by thiram, DMDTC and DEDTC. In blood, lead levels were increased 3-fold and in brain almost 4-fold after treatment with lead plus disulfiram compared to treatment with lead alone. When rats were given DEDTC or thiram by gavage (0.1 mmol/kg/day 5 days a week for 2 weeks) after cessation of the lead treatment, there was no increase in blood lead levels but in thiram-treated rats brain lead concentration was increased 2.7-fold. In rats treated with DEDTC intraperitoneally after cessation of lead treatment, both blood and brain concentrations of lead were increased. This study suggests that combined exposure of lead and dithiocarbamate/thiuram derivatives causes a substantial increase in brain levels of lead which are not always reflected in increases of blood lead levels. This interaction effect ought to be taken into consideration when evaluating the health effects of environmental and occupational lead exposure.

Animals↗
PubMed1985

Dissolution of metals by human and rabbit alveolar macrophages.

The ability of human and rabbit alveolar macrophages to dissolve 0.1-0.5 micron MnO2 particles in vitro was compared. The amount of Mn added and dissolved from the particles over periods of nought, one, and three days was determined by flame atomic absorption spectrophotometry. The amount dissolved by human and rabbit macrophages was similar; on average 43.1% and 43.9%, respectively, were dissolved within three days. But rabbit and human macrophages dissolved significantly more Mn than was dissolved in the respective culture medium without macrophages after one and three days. It is suggested that the dissolution of particles by alveolar macrophages should be one basic component in any model of alveolar clearance of inorganic particles.

Adult↗
PubMed1984

T7 DNA polymerase is not a zinc-metalloenzyme and the polymerase and exonuclease activities are inhibited by zinc ions.

Phage T7 DNA polymerase purified to homogeneity by an antithioredoxin immunoadsorbent technique was resolved into its active subunits the gene 5 protein and Escherichia coli thioredoxin by a novel technique involving chromatography on Sephadex G-50 at pH 11.5. Analysis of the metal content of the holoenzyme by atomic absorption spectroscopy showed that it did not contain stoichiometric amounts of zinc. Determination of polymerase and exonuclease activities of the holoenzyme and the gene 5 protein in assay mixtures containing enzyme concentrations in excess of the Zn2+ concentration showed full activity. Addition of Zn2+ resulted in no stimulation and the activities were completely inhibited by 0.1 mM Zn2+. These results demonstrate that the essential T7 DNA polymerase is not a zinc-metalloenzyme and suggest that DNA polymerases show no functional requirement for Zn2+.

Chlorides↗
PubMed1984

Ability of rabbit alveolar macrophages to dissolve metals.

Manganese dioxide particles, 0.1-0.5 micron, were added to samples of 2-3 X 10(6) rabbit alveolar macrophages. The amount of manganese added and dissolved from the particles, over periods of 0, 1, 3, and 5 days, was determined by flame atomic absorption spectrophotometry. Macrophages from six rabbits received about 10 micrograms of Mn, macrophages from two rabbits about 30 micrograms, and macrophages from another two rabbits about 100 micrograms. Over periods of 1, 3, and 5 days the macrophages in all three dose groups dissolved two to three times more Mn than was dissolved in control experiments. In control experiments solubility was studied in the medium without macrophages. Macrophages cultivated 3 days before the addition of MnO2 dissolved the particles within another 2 days to an extent similar to that in the control experiments. The ability of the macrophages to dissolve MnO2 particles might be related to the low pH values in the phagosomes. Studies of the ability of macrophages from various species to dissolve metal particles as well as of pH values in their phagosomes might lead to a better understanding of alveolar clearance of metal particles.

Animals↗