Biomedical subjects

L Eriksson

Publications and source records attributed to L Eriksson.

At least 19 recordsLinked to original sources

PubMed1992

Positron emission tomographic studies of central cholinergic nerve terminals.

The aim of this study was to develop a quantitative method for the study of cholinergic nerve terminals in vivo. An 18F-labeled analogue of vesamicol ([18F]FMV) that binds with high affinity to synaptic vesicles from Torpedo electric organ was synthesized and evaluated in vivo in rats and monkeys by positron emission tomography (PET). In rats, the tracer was rapidly cleared from the blood and highly extracted into the brain, where it was specifically and irreversibly bound. In monkeys, a specific binding of the tracer was observed in brain regions known to contain cholinergic nerve terminals. Preinjection of non-labeled vesamicol prevented the cerebral binding of [18F]FMV to a high affinity site in both species. Our results are a major step towards quantitative human in vivo studies of presynaptic cholinergic functions.

Animals↗

PubMed1992

Immunohistochemical evidence of endothelin-1 in human choroid plexus.

An immunohistochemical investigation was carried out on 17 specimens of human choroid plexus obtained post mortem, 1 biopsy of normal choroid plexus including part of the lateral ventricle and 1 papilloma of the choroid plexus removed surgically. The material was fixed in formalin. Paraffin and cryostat sections were used. A polyclonal antiserum to endothelin-1 served as a primary antibody. The avidin-biotin-peroxidase method was applied to demonstrate the immunoreaction. The epithelial cells of the choroid plexuses, the choroid papilloma and most ependymal cells of the lateral ventricle showed a distinct brown reaction product in their cytoplasm indicating antigenic sites to endothelin-1. The reaction was of lesser intensity in the ependymal cells. The connective tissue in choroid plexus was unstained. A positive immunoreaction was present in the walls of some vessels in the choroid plexus in cryostat sections. This is the first report on the presence of antigenic sites to endothelin-1 in the epithelial cells of the human choroid plexus. The role of endothelin in these cells should be investigated to ascertain if the cells synthesize this biologically active peptide or if it is merely bound to receptors in them.

Adult↗

PubMed1992

In vivo distribution of [11C]-busulfan in cynomolgus monkey and in the brain of a human patient.

The in vivo distribution of the antileukemic agent busulfan labeled with the positron-emitting radionuclide carbon 11 was investigated in cynomolgus monkeys and in a human patient using positron emission tomography. After i.v. injection of the radiotracer, its regional uptake was monitored for about 1 h in the monkey's body and, in a separate experiment, in the monkey's brain. The concentration of radioactivity in the liver, which showed the highest levels of all the organs scanned, increased throughout the experiment and was 9-fold that in the brain at the end of the experiment. [11C]-Busulfan rapidly crossed the blood-brain barrier. The radioactivity peaked in both the cortex and the white matter showing a ratio of 1.25, at 3 min but declined quickly to yield a ratio of approximately 1 after 30 min. In the human brain, radioactivity in the cerebellum, cortex, and white matter reached a maximum within 5 min showing a cortex:white matter ratio of 1.6. The activity in the cortex declined to yield a ratio of 1 within 30 min. Of the delivered dose, 20% penetrated into the brain.

Adult↗

PubMed1992

Gamma-aminobutyrate aminotransferase activity in brains of schizophrenic patients.

The activity of gamma-aminobutyrate aminotransferase (GABA-T) was estimated in twelve regions of brains from 22 control subjects and 6 cases with schizophrenia. In the controls, no significant correlation was found between the enzyme activity and age or postmortem interval (PMI) in any of the brain regions studied. In experiments on rat brains, the enzyme activity decreased about 20% during the first 2 hours of storage at room temperature and at 4 degrees C but remained steady thereafter. A similar initial decline in activity in the human brain material cannot be excluded. In the human brains, a slightly lower activity was found in the group below 75 years (n = 8) when compared with the group above 75 years (n = 8). A tendency to higher activities was found in female brains (n = 10) compared with male brains (n = 12). No significant difference in the enzyme activity was found between schizophrenic brains, in any of the regions studied, when compared to controls, matched for age, sex and PMI.

4-Aminobutyrate Transaminase↗

PubMed1992

Temporomandibular joint disk displacement without reduction. Treatment with flat occlusal splint versus no treatment.

A flat occlusal splint has been extensively used in the treatment of patients with temporomandibular joint disk displacement without reduction, but no studies with untreated controls have assessed its effect. We randomly assigned 51 patients with temporomandibular joint pain and arthrographically verified disk displacement without reduction to be treated with a flat occlusal splint or to serve as untreated control subjects in a 12-month clinical trial. Pain symptoms disappeared in about one third of the patients in each group. Another third of the patients in the control group improved. Sixteen percent of the patients in the control group and 40% of the patients treated with a flat occlusal splint were worse at the end than at the beginning of the study. Joint pain and muscle tenderness decreased more frequently in the nontreatment controls than in the treatment group. A statistically significant benefit of a flat occlusal splint over nontreatment control subjects could not be identified in this study of patients with painful disk displacement without reduction. The use of a flat occlusal splint in this patient group should therefore be reconsidered.

Adolescent↗

PubMed1992

Temporomandibular joint diskectomy. No positive effect of temporary silicone implant in a 5-year follow-up.

The purpose of this study was to evaluate the long-term clinical and radiologic effects of a temporary silicone implant after diskectomy of the temporomandibular joint. Forty-three temporomandibular joints in 43 patients with painful disk displacement underwent a diskectomy. A sheet of medical-grade silicone was temporarily placed in 22 patients; 21 patients did not receive an implant. The patients were clinically and radiologically examined 5 years after surgery. On the basis of symptoms and jaw function, they were classified as having good (30 patients), acceptable (8 patients), and bad (5 patients) results. All the patients with bad results and five of the eight patients with acceptable results had received implants. Erosive changes of the condyle or fossa were seen radiographically at follow-up in eight patients, each of whom had received an implant. No positive clinical or radiologic effects of the implants could be identified. The use of a temporary silicone implant after diskectomy of the temporomandibular joint in patients with internal derangement should be seriously questioned.

Adult↗

PubMed1992

Prevalence of osseous changes in the temporomandibular joint of asymptomatic persons without internal derangement.

There is a controversy in the literature regarding the prevalence of osseous changes in the temporomandibular joint (TMJ) of asymptomatic persons. Using cephalometrically corrected tomograms, we assessed one TMJ of each of 34 asymptomatic persons who had no arthrographic or magnetic resonance imaging evidence of internal derangement. Minimal flattening of the condyle or articular eminence was seen in 12 joints (35%). More advanced osseous changes such as erosion, osteophytosis, or sclerosis were not seen in any joint. The findings suggest that generally no osseous changes occur in the TMJ in asymptomatic persons without internal derangement. When osseous changes occur, they are confined to minimal flattenings. Minimal flattening is probably of no clinical significance because the persons were asymptomatic, and arthrography and magnetic resonance imaging showed no evidence of abnormalities in the soft tissues.

Adolescent↗

PubMed1992

Magnetic resonance evaluation after temporomandibular joint diskectomy.

The aim of this study was to investigate the value of magnetic resonance imaging after diskectomy of the temporomandibular joint. Magnetic resonance images were obtained before and 12 months after unilateral diskectomy without disk replacement. Magnetic resonance findings at follow-up were correlated to residual pain. At the follow-up, 20 of 28 patients were free of pain in the joint that had been surgically treated, four patients had mild pain, and four patients had significant residual pain. The magnetic resonance images at follow-up showed that the joint space was filled with soft tissue after diskectomy. In patients without pain at follow-up, this soft tissue had a magnetic resonance signal that was equal or higher than that of the muscles. In the four patients with significant residual pain and in one patient with mild residual pain, the soft tissue in the joint space between the condyle and glenoid fossa had a magnetic resonance signal intensity that was lower than the muscle. On the basis of findings in a previous study, the areas of low signal intensity were interpreted as fibrous adhesions. The study suggests that areas of low signal intensity in the joint space appear to be associated with residual pain and that magnetic resonance imaging could be a valuable tool for assessment of the temporomandibular joint after diskectomy.

Cartilage, Articular↗

PubMed1992

Creation of disc displacement in human temporomandibular joint autopsy specimens.

The purpose of this study was to investigate the possibility of iatrogenically creating disc displacement in the human temporomandibular joint (TMJ). Fourteen fresh TMJ autopsy specimens with superior disc position were selected for the study. The upper and lower joint spaces were exposed via a preauricular incision and two to three superficial mediolateral incisions were made in the inferior surface of the posterior disc attachment (ie, retrodiscal tissue). After these incisions were made it was possible to manually displace the disc anteriorly. To maintain the disc in the anterior position the condyle was positioned against the posterior disc attachment in a manner corresponding to the closed mouth position. The joints were then fixed in this relationship and magnetic resonance imaging (MRI) was repeated using the same scanning plane and scanning parameters as before intervention. After imaging, the joints were cryosectioned to show the degree of disc displacement. Histologic analysis was made of the posterior disc attachment. Postoperative MR images and cryosections showed the disc to be displaced anteriorly in 12 of the 14 joints. Displacement of the disc was complete in eight joints (the entire mediolateral dimension of the joint) and partial (only in the lateral part of the joint) in four joints. The disc remained in a superior position in two joints. Cryosections and histologic analysis showed the incisions in the inferior aspect of the posterior disc attachment to be superficial. The results of this study suggest that the integrity of the inferior aspect of the posterior attachment of the disc to the condyle is essential for keeping the disc in its position superior to the condyle.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1992

The role of white cells in the transmission of Yersinia enterocolitica in blood components.

The mechanism for the transmission of Yersinia enterocolitica in blood components has been studied experimentally. One hypothesis is that, during a Yersinia infection in the blood donor, bacteria are phagocytosed by white cells (WBCs), but are not killed. After collection of blood from such a donor and component production, the bacteria are present in WBCs for some time, during which the unit appears sterile. Later, when the WBCs disintegrate, the bacteria are released and multiply in the unit. Aliquots of whole blood and buffy coat were inoculated with 100 colony-forming units (CFU) per mL of a Y. enterocolitica strain of type O:3 and left at room temperature for 5 hours. Some aliquots were then WBC-reduced by filtration, while others retained their WBC contents. All aliquots were kept at 4 degrees C for 6 weeks. Meat extract broth culture medium was used as a control. Growth in the range of 2000 CFU per mL was obtained in the broth control by 24 hours, whereas the whole blood and buffy coat units appeared sterile for the first days of storage. After 1 week, a trace of bacteria and, after 4 weeks, massive growth were found in the WBC-containing units but not in the WBC-reduced units. The likely explanation is that the bacteria had been phagocytosed by the WBCs and were thereby hidden and not available for bacterial culture during the first phase of storage. When the WBCs spontaneously disintegrated, bacteria were released and multiplied in the blood units.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Preservation↗

PubMed1992

Atrial natriuretic peptide attenuates pressor but enhances natriuretic responses to angiotensin II in pregnant conscious goats.

This study was designed to examine the actions of ANP in acute, ANGII-mediated hypertension during pregnancy. Effects on blood pressure, blood volume, and renal Na and K excretion were evaluated in conscious goats (n = 6). ANP (2 micrograms min-1), ANGII (0.5 microgram min-1), or ANGII+ANP (doses the same as for each peptide alone) was infused intravenously for 60 min. The pressor response to ANGII was reduced in pregnant goats. This reduction was seen in systolic, but not in diastolic pressure. ANP decreased pressure by 5-10 mmHg both in pregnancy and in non-pregnancy. When ANGII+ANP was infused, blood pressure initially rose as with ANGII but then declined. ANP suppressed only the elevated systolic pressure. Plasma protein concentration and haematocrit was reduced by ANGII but increased by ANP alone or together with ANGII, thereby implying fluid shift into the vasculature by ANGII and opposite movement by ANP. ANGII increased renal Na excretion to 1500 mumol min-1 in non-pregnancy, but only to half of that in pregnancy. ANP alone caused small natriuresis, but enhanced ANGII-induced natriuresis to near 3000 mumol min-1 in both non-pregnant and pregnant goats. In summary, ANP further attenuated the blunted blood-pressure rise due to ANGII in pregnant goats, and reduced plasma volume, but enhanced renal Na excretion as in non-pregnant goats. This implies that with the present combination ANP and ANGII caused a near maximal natriuretic response that was not modified by the systemic cardiovascular changes occurring in pregnant goats.

Angiotensin II↗

PubMed1992

Osteocalcin 24-hour profiles during normal pregnancy.

The interpretation of previous data on osteocalcin during pregnancy has been complicated by the fact that serum levels, at least in nonpregnant women, display a significant circadian variation. In the present study, serum concentrations of osteocalcin were recorded for 24 h in 12 individual women. In 4 nonpregnant women, there were striking diurnal fluctuations during the sampling period, with values ranging from 0.5 to 4.0 ng/ml. One woman who was investigated in the 11th week of pregnancy showed similar fluctuations in osteocalcin concentrations whereas in the 15th and 17th week values were much lower with minor fluctuations. In 4 women investigated during late pregnancy (weeks 34-38), osteocalcin serum levels were extremely low (range 0.2-0.4 ng/ml), often below the detection limit of the assay, and there was no diurnal variation. Also, in 1 lactating woman, osteocalcin serum levels were low (0.3-0.8 ng/ml) and stable. Low osteocalcin values during pregnancy may indicate a reduced bone turnover possibly mediated via an altered estrogen and growth hormone secretion.

Bone Remodeling↗

PubMed1992

Automated blood component preparation with the Opti system: three years' experience.

Removal of buffy coat from the red cell preparations reduces the content of microaggregates and leukocytes and decreases transfusion side effects. However, buffy coat removal is difficult to standardize when performed manually. An automated method using a new type of plastic container system, the Optipac, and a new type of device, the Optipress, greatly improves blood component production. An initial hard centrifugation of the original whole blood provides the best results, leaving approximately 20 ml of plasma and 0.5 x 10(9) leukocytes per unit of red cells suspended in 100 ml of an additive solution (SAG-M). Improved quality and standardization of the products, reduced technician time and better working conditions for the technician are the major advantages as compared to traditional manual technique.

Blood Component Removal↗

PubMed1991

GABA-transaminase activity in rat and human brain: regional, age and sex-related differences.

The activity of 4-aminobutyrate:2-oxoglutarate transaminase (GABA-T) has been investigated in the rat and human brain. Both rat and human brain GABA-T retained its full activity for at least 2 months and with a loss of less than 10% after 6 months when frozen at -20 degrees C as tissue parts. There was a loss of activity of mouse brain GABA-T of about 15% per 24 hours postmortem. In the rat brain, GABA-T activity varied from low values in cortex and hippocampus to high in brain stem and cerebellum. There was a significant increase of GABA-T activity with age from 1 to 6 weeks and a significant reduction of the activity with age thereafter. Male rats had significant higher activity than female rats. In the human brain, GABA-T activities were measured in twelve regions of autopsied brains from 10 adult control subjects. No difference was found between the activities in the left and right sides. There is considerable variation in enzyme activity across the brain, with low activities in e.g. pons and medulla oblongata and high activities in e.g. caudatus, substantia nigra and hypothalamus. The activity of the enzyme is significantly different both between brain regions and between individuals.

4-Aminobutyrate Transaminase↗

PubMed1991

Osseous and muscular changes after vertical ramus osteotomy. A magnetic resonance imaging study.

Magnetic resonance (MR) imaging was performed about 2 years after vertical ramus osteotomy of 10 patients to study changes in the mandibular condyle, cortical and cancellous bone of the proximal fragment, and muscles of mastication. MR imaging observations of the surgically treated patients were compared with findings in 10 asymptomatic untreated control subjects. The results showed that the MR appearance of bone marrow of the mandibular condyle was normal in all patients and in all control subjects. No MR evidence of avascular necrosis of the mandibular condyle was found. MR imaging artifacts from microscopic metallic particles were seen in all surgically treated regions. Thickening of the buccal and lingual cortical bone with narrowing of the bone marrow space was seen bilaterally in eight patients and unilaterally in two patients. Slight medial tipping of the mandibular condyle was seen unilaterally in two patients. Atrophic changes with decreased muscle volume and fatty replacement of muscle tissue was seen unilaterally in eight patients. None of these alterations were seen in the control subjects. MR imaging appears to be an excellent method to study morphologic changes of the muscles of mastication and osseous fragments after orthognathic surgery of the mandible. Thickening of the cortical bone and narrowing of the bone marrow space of the proximal fragment was frequently seen after vertical ramus osteotomy of the mandible and most likely represents remodeling associated with normal healing.

Adolescent↗

PubMed1991

Rapid feasibility studies of tracers for positron emission tomography: high-resolution PET in small animals with kinetic analysis.

The development of methods for production of a radiotracer for use in human studies with positron emission tomography (PET) is often a time-consuming process of optimizing radiolabelling yields and handling procedures. Sometimes the radiotracer is not the original drug, but rather a derivative with unknown in vivo pharmacological properties. We have developed a fast and simple method of testing putative new PET tracers in vivo in small animals. The procedure has been validated in rats with different PET tracers with known kinetic and pharmacological properties ([2-18F]2-fluoro-2-deoxy-D-glucose, [N-methyl-11C]Ro 15-1788, and [15O]butanol). The tracer concentration in arterial blood was continuously measured to obtain the brain input function. Following image reconstruction of the scans, time-activity curves of selected regions of interest were generated. Estimations of CMRglc (1.0 +/- 0.2 mumol g-1 min-1), CBF (1.4 +/- 0.4 ml g-1 min-1) and transport rate constants for [N-methyl-11C]Ro 15-1788 (K1 = 0.44 +/- 0.01 ml g-1 min-1 and k2 = 0.099 +/- 0.005 min-1) as well as calculated first pass extraction (0.32 +/- 0.1) are in reasonable agreement with literature values. Small animal studies require minimal amounts of radioactivity and can be performed without sterility and toxicology tests. They may serve as a preliminary basis for radiation safety calculations because whole body scans can be performed even with a head scanner.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Specification and selection of regions of interest (ROIs) in a computerized brain atlas.

The computerized individually adjustable brain atlas (CBA) has been further developed. The atlas was primarily designed for anatomical localization and quantitative evaluation of data in positron emission tomography (PET), but may also be employed for other neuroimaging modalities, such as transmission computed tomography (CT) and magnetic resonance imaging (MRI). The atlas is based on anatomical information obtained from digitized cryosectioned brains. Using spatially standardized and then averaged MRI images, we demonstrate the high localization accuracy and precision of the brain atlas. This is a prerequisite for obtaining accuracy when using the atlas in the localization and the quantitative evaluation of PET data. The specification and the selection of region of interests (ROIs) by the CBA are presented and discussed.

Brain↗

PubMed1991

Storage of saline-adenine-glucose-mannitol-suspended red cells in a new plastic container: polyvinylchloride plasticized with butyryl-n-trihexyl-citrate.

Blood collection and component preparation have been performed in integrally connected multiple plastic containers made with a new plastic. This polyvinylchloride (PVC) container plasticized with butyryl-n-trihexyl-citrate (BTHC) is a new material for blood storage; it contains no di(2-ethylhexyl)phthalate (DEHP). After removal of plasma and buffy coat, the red cells were suspended in saline-adenine-glucose-mannitol (SAGM) medium. After 42-day refrigerator storage, the total adenine nucleotide concentration remained the same as the initial concentration in the red cells, whereas ATP levels had decreased to 61 percent of the initial value. The 2,3 DPG concentration was 62 percent of normal on Day 7 and 21 percent on Day 14. Glucose consumption, lactate production, potassium leakage from red cells, and pH levels were similar to those found after storage in DEHP-plasticized containers under the same conditions. After 42 days, hemolysis levels were 0.56 +/- 0.21 percent and 0.42 +/- 0.17 percent in two series of units mixed weekly and 0.70 +/- 0.27 percent in units stored unmixed. Although even higher levels of hemolysis were observed in the units stored unmixed and used for 24-hour posttransfusion survival, the autologous red cell recovery results were excellent (83.2 +/- 5.1%, n = 8). BTHC-plasticized PVC is found to be a suitable material for 42-day storage of red cells in SAGM solution.

2,3-Diphosphoglycerate↗