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Biomedical subjects

L Eriksson

Publications and source records attributed to L Eriksson.

At least 163 records · Page 9Linked to original sources
PubMed1990

High condylar shave of the temporomandibular joint with preservation of the articular soft tissue cover: an experimental study on rabbits.

The high condylar shave has the disadvantage of removing the articular soft tissue cover together with the underlying condylar bone. In an attempt to overcome this disadvantage, we elevated the articular soft tissue cover, shaved the condylar head, and replaced the articular soft tissue cover in its original position in nine adult rabbit temporomandibular joints. On the contralateral joints, the same amount of bone was shaved together with the articular soft tissue cover. The rabbits were killed after 3 months, and the condyles were macroscopically and histologically evaluated. All condyles were covered with an articular soft tissue layer in the area operated on. This surface was smoother when the articular soft tissue cover was preserved. Histologically, the subarticular layer of cartilage cells was continuous in the joints with preservation of the articular soft tissue cover but was frequently interrupted in the joints where this cover was removed. The incision made in the posterior part of the articular surface for elevating the articular soft tissue cover frequently caused a deformity of the condyle and an interruption of the subarticular layer of cartilage. The results suggest that preservation of the articular soft tissue cover on the mandibular condyle might be one way to improve the postoperative morphology after high condylar shave. The technique in its present state has obvious drawbacks and should be further refined before it is considered for clinical application.

Animals↗
PubMed1990

Osteoplasty of the mandibular condyle with preservation of the articular soft tissue cover: comparison of fibrin sealant and sutures for fixation of the articular soft tissue cover in rabbits.

Fibrin sealant and sutures were compared for fixation of the articular soft tissue cover after it had been raised in association with osteoplasty of the mandibular condyle. Nine adult rabbits were operated on bilaterally with the use of fibrin sealant on one joint and sutures on the other joint. The rabbits were killed after 3 months. Macroscopic and histologic evaluations of the condyles did not reveal any appreciable differences between the two techniques. Fibrin sealant was, however, technically easier to apply than the sutures. It was concluded that fibrin sealant might be an alternative to sutures for fixation of the articular soft tissue cover after it has been raised in association with osteoplasty of the mandibular condyle.

Animals↗
PubMed1990

Temporomandibular joint: variation of normal arthrographic anatomy.

The arthrograms of 34 individuals with asymptomatic, clinically and arthrographically normal temporomandibular joints were analyzed. The results showed a substantial variation of the dimensions and configuration of the joint compartments. Thus the anterior recess of the lower joint compartment was small in 15 joints (44%), medium-size in 16 joints (47%), and large in three joints (9%). The upper margin of this recess was flat or convex in 24 joints (71%) and concave in 10 joints (29%). These observations contradict previous assumptions about a strict association between the configuration and dimension of the anterior recess of the lower joint compartment and the position of the disk. It was concluded that dimension and configuration of the joint compartments should not be used as the only criteria for diagnosis of the position of the disk.

Adolescent↗
PubMed1990

Selective flocculation with chitosan in Escherichia coli disintegrates: effects of pH and nuclease treatment.

The flocculation of cell debris from a beta-galactosidase constitutive E. coli with chitosan as a flocculant was studied to investigate the possibility of obtaining a selective flocculation in cell disintegrates with high product recoveries. The flocculation removed 98% of the cell debris by 30 min sedimentation under gravity, which should be compared to a separation of the cell debris without flocculation of only 70% by centrifugation at 15,000 g. Optimal flocculation dosages varied between 12 and 43 mg chitosan g-1 dry weight of cells, depending on pH. The yield of the product beta-galactosidase reached 60% at optimal pH. Hydrolysis of the nucleic acids by DNAase and RNAase decreased the optimal flocculation dosages considerably. The study showed that the flocculation is somewhat selective, since chitosan also removed 85% of the nucleic acids and 50% of the proteins, which contributed to the purification of the protein solution.

Bacterial Proteins↗
PubMed1990

Amyloid inclusions in choroid plexus epithelial cells. A simple autopsy method to rapidly obtain information on the age of an unknown dead person.

Different methods such as X-ray examination of the skeleton and inspection of the teeth have been described for estimation of the age of an unidentified dead person. These methods are more or less exact but the results will not be available until many days after the autopsy. In the present paper, we present a fairly simple method to obtain information on the age of a deceased using amyloid inclusions in the choroid plexus epithelial cells.

Adult↗
PubMed1990

Accuracy and precision of the computerized brain atlas programme for localization and quantification in positron emission tomography.

The computerized brain atlas programme (CBA) provides a powerful tool for the anatomical analysis of functional images obtained with positron emission tomography (PET). With a repertoire of simple transformations, the data base of the CBA is first adapted to the anatomy of the subject's brain represented as a set of magnetic resonance (MR) or computed tomography (CT) images. After this, it is possible to spatially standardize (reformat) any set of tomographic images related to the subject, PET images, as well as CT and MR images, by applying the inverse atlas transformations. From these reformatted images, statistical images, such as average images and associated error images corresponding to different groups of subjects, may be produced. In all these images, anatomical structures can be localized using the atlas data base and the functional values can be evaluated quantitatively. The purpose of this study was to determine the spatial and quantitative accuracy and precision of the calculated regional mean values. Therefore, the CBA was applied to regional CBF (rCBF) measurements with [11C]fluoromethane and PET on 26 healthy male volunteers during rest and during three different physiological stimulation tasks. First, the spatial accuracy and precision of the reformation process were determined by measuring the spread of defined anatomical structures in the reformatted MR images of the subjects. Second, the mean global CBF and the mean rCBF in the average PET images were compared with the global CBF and rCBF in the original PET images. Our results demonstrate that the reformation process accurately transformed the individual brains of the subjects into the standard brain anatomy of the CBA. The precision of the reformation process had an SD of approximately 1 mm for the lateral dislocation of midline structures and approximately 2-3 mm for the dislocation of the inner and outer brain surfaces. The quantitative rCBF values of the original PET images were accurately represented in the reformatted PET images. Moreover, this study shows that the application of the CBA improves the analysis of functional PET images: (a) The average PET images had a low background noise [0.4 ml/100 g/min +/- 0.7 (SD)] compared to the mean rCBF changes specifically induced by physiological stimulation. (b) The reformatted PET images had a voxel volume of 10.9 mm3. Owing to this high sampling resolution, it was possible to differentiate the mean rCBF changes in adjacent activated fields such as the left motor hand area from the sensory hand area and the left premotor cortex.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1990

Positron emission tomography--a new technique for studies of the central nervous system.

Positron emission tomography (PET) has become an important tool to study the central nervous system. Examples of such studies are cerebral blood flow and metabolism and determination of receptor characteristics of the brain. In the following the basic principles and the physics behind PET are given. Different aspects are discussed such as detector design, image reconstructions and data analyses. Since quantification is essential in PET, data have to be corrected for absorption, scatter and random coincidences. These corrections and their influence on image data are discussed. A review of state-of-the-art PET research of the brain is given.

Brain↗
PubMed1990

Platelet concentrates in an additive solution prepared from pooled buffy coats. 1. In vitro studies.

A new method for the preparation of platelet concentrates (PCs) is described. The source material is buffy coat (BC), prepared after keeping standard CPD whole-blood units at room temperature for 6-12 h, followed by centrifugation at 3,500 rpm for 10 min (first series) or 4,000 rpm for 12.5 min (second series). BC, separated from plasma and red cells, was kept at room temperature for a further 8-12 h without agitation. Pools of 6 (first series) and 4 (second series) BCs were prepared using a sterile docking device and suspended in a platelet-additive solution (PAS) containing sodium/potassium chloride, citrate, phosphate, and mannitol. After gentle centrifugation, the platelet-rich supernatant was expressed to and stored in one (first series) or two (second series) 1-liter polyolefine (PL-732) containers. In the first series, the total number of platelets was 316 +/- 59 x 10(9) per PC (yield 65%). However, when the method was applied at a routine scale, the yield varied considerably and was shown to be strongly dependent on the hematocrit of the BCs. A number of steps were taken to standardize the technique which resulted in an improved yield (77.3 +/- 8.7%) with 316 +/- 52 x 10(9) platelets (mean +/- SD, range 203-490, n = 134), obtained from 4 BC pools and lower leukocyte contamination than before, 18 +/- 17 X 10(6) per preparation (range 1-73, microscopic counting, n = 38). The storage medium consisted of a mixture of plasma and PAS.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1990

Baroreceptor reflex enhancement by chronic intracerebroventricular infusion of enalapril in normotensive rats.

Involvement of the brain renin-angiotensin system in baroreceptor reflex regulation was assessed by recording reflex heart rate and sympathetic nerve responses in normotensive rats that had been infused intracerebroventricularly with the converting enzyme inhibitor enalapril for 15 days. Reflex bradycardia and sympathetic nerve inhibition during pressor responses to phenylephrine were larger in rats with intracerebroventricularly infused enalapril than in control rats similarly infused either intracerebroventricularly with saline or intravenously with enalapril. In contrast, opposite reflex responses to sodium nitroprusside-induced hypotension were mostly unaffected. Because depressor, bradycardic, and sympathoinhibitory responses to electrical stimulation of the central cut end of the left aortic depressor nerve were also enhanced, intracerebroventricularly infused enalapril must be affecting the baroreceptor reflex arc centrally. These results are compatible with the interpretation that intracerebroventricularly infused enalapril enhanced baroreceptor reflex sensitivity by reducing endogenous angiotensin II levels in the brain through converting enzyme inhibition.

Afferent Pathways↗
PubMed1990

Baroreceptor reflex impairment and mild hypertension in rats with dietary-induced obesity.

Cardiovascular dysfunction associated with obesity was assessed by comparing rats that had been maintained on a regular or high fat diet since weaning. Rats on the high fat diet not only gained weight faster than age-matched controls but also had higher systolic and mean pressures. Development of mild hypertension in obese rats was first detected by indirect tail-cuff measurement and confirmed later by recording intra-arterial pressures directly from indwelling femoral catheters. To assess baroreceptor reflex sensitivity, reflex heart rate responses were elicited by lowering blood pressure with sodium nitroprusside or elevating it with phenylephrine. Initial tests showed that, although reflex tachycardia during depressor responses to sodium nitroprusside did not differ between groups, reflex bradycardia during pressor responses to phenylephrine was weaker in obese than in control rats. Underlying autonomic mechanisms were then examined by repetition of baroreceptor reflex tests after cholinergic blockade with methylatropine or beta-adrenergic blockade with propranolol. Reflex tachycardia was equally inhibited in both groups by either antagonist. By contrast, reflex bradycardia was reduced more in obese than in control rats by beta-adrenergic blockade but was equally reduced by cholinergic blockade. Because residual responses after beta-adrenergic blockade would represent remaining parasympathetic mediation, these results indicate that reflex bradycardia was selectively impaired because of deficient parasympathetic mediation. Considered collectively, our results suggest that impaired parasympathetic mediation of reflex bradycardia could either result from or contribute to the blood pressure elevation in obese rats.

Adrenergic beta-Antagonists↗
PubMed1990

Peptide QSAR on substance P analogues, enkephalins and bradykinins containing L- and D-amino acids.

Peptide QSARs are constructed for substance P analogues, enkephalins (two examples) and bradykinins containing both L- and D-amino acids. As descriptors in the QSARs, the previously developed descriptors z1 (hydrophobicity), z2 (bulk) and z3 (electronic effect) are used together with a qualitative variable coding for variation in chirality. Two parametrizations of the peptide sequences are tested. In the first no chiral description is used at all, and in the second chirality is described by the qualitative variable. It is concluded that for the current series of peptides, the biological response to variation in amino acid sequence and chirality can be modelled.

Amino Acid Sequence↗
PubMed1990

Optimizing blood component preparation: qualitative, logistic and economic aspects.

The changing pattern in transfusion medicine with emphasis on the collection of plasma for fractionation and Factor VIII production, an increased use of platelets, and needs to reduce virus transmission and leukocyte immunogenicity, has made it important to optimize the procedures used in the preparation of blood components. The anticoagulant solution should allow sufficient time between collection and component preparation without considerable loss of quality. Whenever possible, red cells and platelets should be stored in special storage media, thus allowing a maximum volume of plasma to be collected and fractionated into plasma products. Some examples of procedures in current use or under development and their practical and economical consequences are given in this brief review.

Blood Coagulation↗
PubMed1990

Age-related accumulation of amyloid inclusions in adrenal cortical cells.

Cytoplasmic fine fibrillar inclusions with properties of amyloid occur as neurofibrillary tangles in the brain and in the aging choroid plexus. In the present study we show that inclusions, similar but not identical to those in the choroid plexus, are common in the adrenal cortex of elderly persons. The inclusions consist of aggregates of parallel fine fibrils, often in contact with lipid droplets and partially limited by a membrane. The inclusions have affinity for Congo red and exhibit a bright green birefringence after this staining. Therefore, the inclusions can be regarded as a form of senile amyloid.

Adrenal Cortex↗
PubMed1989

Diffuse pigmented villonodular synovitis of the temporomandibular joint diagnosed by fine-needle aspiration cytology.

Diffuse pigmented villonodular synovitis is a rare tumor in the temporomandibular joint region. This article deals with a 32-yr-old male who suffered from pain and swelling in the right temporomandibular joint region associated with restricted mouth opening. Computed tomography showed a tumor lateral to the temporomandibular joint. Arthrography revealed a displaced temporomandibular joint disk. Fine-needle aspiration cytology showed characteristic cellular changes, including rounded or oval cells with abundant cytoplasm and intracytoplasmatic hemosiderin deposits and numerous multinucleated giant cells without nuclear atypia. A benign mesenchymal lesion suggestive for pigmented villonodular synovitis was diagnosed and later verified at histologic examination. Fine-needle aspiration cytology seems to be useful for this diagnosis.

Adult↗
PubMed1989

A computerized adjustable brain atlas.

A computerized brain atlas, adjustable to the patients anatomy, has been developed. It is primarily intended for use in positron emission tomography, but may also be employed in other fields utilizing neuro imaging, such as stereotactic surgery, transmission computerized tomography (CT) and magnetic resonance imaging (MRI). The atlas is based on anatomical information obtained from a digitized cryosectioned brain. It can be adjusted to fit a wide range of images from individual brains with normal anatomy. The corresponding transformation is chosen so that the modified atlas agrees with a set of CT or NMR images of the patient. The computerized atlas can be used to improve the quantification and evaluation of PET data by: Aiding and improving the selection of regions of interests. Facilitating comparisons of functional image data from different individuals or groups of individuals. Facilitating the comparison of different examinations of the same patient, thus reducing the need of reproducible fixation systems. Providing external a priori anatomical information to be used in the image reconstruction. Improving the attenuation and scatter corrections. Aiding in selecting a suitable patient orientation during the PET study. By applying the inverse atlas transformation to PET data set it is possible to relate the PET information to the anatomy of the reference atlas. Thus reformatted PET data from different patients can be averaged, and averages from different categories of patients can be compared. This procedure will facilitate the identification of statistically significant differences in the PET information from different groups of patients.

Brain↗
PubMed1989

A preliminary evaluation of the Scanditronix PC2048-15B brain scanner.

The PC2048-15B is the brain version of the new generation of Scanditronix positron camera systems. It is based on a detection unit with 16 scintillating crystals mounted on 2 dual photomultiplier tubes. A system description is given and preliminary test results including spatial resolution, sensitivity to true and random coincidences, scatter correction, and count rate linearity are presented.

Brain↗
PubMed1989

Scatter fraction: measurement and correction.

The concept of scatter in Positron Emission Tomography is reviewed regarding origin and influence on data. Different ways to measure and correct for scatter are discussed.

Scattering, Radiation↗