Biomedical subjects

J Nilsson

Publications and source records attributed to J Nilsson.

337 records · Page 19Linked to original sources

PubMedDate not supplied

Multiple affinity domains for the detection, purification and immobilization of recombinant proteins.

Affinity systems based on specific molecular recognition are valuable tools for detection, purification and immobilization of recombinant proteins. Here, novel multipartite affinity fusion vectors were assembled and investigated to allow flexible binding and elution conditions. The rationale for the assembly of different combinations of affinity domains was to take advantage of the wide variety of molecular interactions of these domains for purification, solubilization, detection and immobilization. In total, seven different affinity tags representing five different types of tag-ligand interactions were studied: (i) monoclonal antibodies-peptides (T7-tag and FLAG peptide); (ii) streptavidin-peptide (Strep-tag); (iii) hexahistidyl-metal ions (His6-tag; (iv) bacterial receptors-serum proteins (staphyloccal protein A-Fc and streptococcal protein G-serum albumin); (v) streptavidin-biotin (in vivo biotinylated peptide). Selected tags were evaluated for the production and purification of Escherichia coli DNA polymerase I (Klenow fragment). On the basis of the results, a vector (pAff2c) was assembled using a novel combination of affinity domains: (i) an in vivo biotinylated peptide; (ii) a His6 sequence, and (iii) a highly soluble serum albumin binding region. Using these three affinities, a wide variety of conditions can be employed for both the binding and the elution steps.

Amino Acid Sequence↗

PubMedDate not supplied

Turnover of sulphated macromolecules in the murine endolymphatic sac after long-term kanamycin treatment.

Radioactively labeled sulphur was injected into 12 mice of the NMRI strain 20 days after pretreatment with kanamycin. The animals were decapitated after intervals ranging from 2 minutes to 24 hours after injection. After a routine autoradiographic procedure, darkly stained silver grains were detected in the endolymphatic sac (ES) and its surroundings. One hour after injection, the grains were found in the surrounding blood vessels. Eleven hours later, maximal uptake was seen in the epithelial cells of the ES in the kanamycin-treated animals. Twenty-four hours after injection, a faint S35 uptake in the ES could still be detected. An increase in the ES activity, indicated by an increased number of free-floating cells and the secretion of a sulphur-containing intraluminal substance, did not occur. The spreading pattern of sulphur, as shown in this investigation, does not support the theory that waste products from the inner ear, transported to the ES by the longitudinal flow, produces an increased activity in the sac after long pretreatment with kanamycin. In 12 control animals, no difference in the distribution of labeling was observed, but there was an additional uptake in the free intraluminal cells which was not seen in the kanamycin group.

Animals↗

PubMedDate not supplied

Stimulation of connective tissue cell growth by substance P and substance K.

Connective tissue cells proliferate actively when cultured in the presence of serum. Platelet-derived growth factor (PDGF), a basic protein of relative molecular mass approximately 30,000, has been identified as the major serum mitogen for these cells; its main physiological/pathophysiological role may be to initiate wound healing in connection with tissue injury. However, growth of cultured cells is also influenced by several other factors, including epidermal growth factor, fibroblast growth factor, insulin and somatomedins. Furthermore, Rozengurt and Sinnett-Smith recently showed that bombesin, a neuroendocrine peptide isolated from frog skin, stimulates DNA synthesis and cell division in cultures of a specific subtype of 3T3 cells. Substance P and substance K (also known as neurokinin A or neuromedin L) are mammalian peptides belonging to the tachykinin family. Substance P has been studied extensively; it is distributed widely throughout the central and peripheral nervous system, including primary sensory neurones, and can be released in the periphery from axon collaterals of stimulated pain fibres and contribute to the inflammatory response. Substance K is a member of the tachykinin family isolated from mammalian spinal cord; Nawa et al. determined the primary structure of two types of substance P precursors, one of which contained a sequence homologous to substance K, as well as the sequence of substance P. We report here that substance P and substance K stimulate DNA synthesis in cultured arterial smooth muscle cells and human skin fibroblasts, and that this stimulation is inhibited by the substance P-antagonist spantide.

Animals↗

PubMedDate not supplied

Transcranial magnetic stimulation and silent period in spasmodic torticollis.

OBJECTIVE: Our objective was to study the corticobulbar projections to neck muscles in cervical dystonia. DESIGN: We compared both the motor evoked potentials and the electromyographic silent period after transcranial magnetic stimulation from sternocleidomastoid and trapezius muscles in a group of 13 patients with spasmodic torticollis with those of 20 healthy volunteers. RESULTS: With the target muscle at rest, no changes of motor threshold, motor evoked potentials latency, and amplitude were observed in dystonic patients. With facilitation, the mean amplitude of the motor evoked potentials was increased in patients compared with controls, the significant difference being for the trapezius muscle, whereas the latency did not differ between groups. The cortical silent period was significantly shorter in dystonic patients than in healthy subjects in both muscles. The duration of the cortical silent period recorded from the sternocleidomastoid muscle showed a positive correlation with the degree of neurologic disability assessed by Tsui's scale. No abnormalities of both nerve conduction velocity and peripheral silent period by stimulation of accessory nerve were found. CONCLUSIONS: These results indicate an impairment of the mechanisms of inhibitory motor control in patients with spasmodic torticollis, which could be the result of a decrease of the basal ganglia inhibitory output over the motor cortex.

Adult↗

PubMedDate not supplied

Secretion of plasminogen activator inhibitor-1 from cultured human umbilical vein endothelial cells is induced by very low density lipoprotein.

Clinical studies have demonstrated an impaired fibrinolytic function in patients with angiographically ascertained coronary artery disease or previous myocardial infarction. This decreased fibrinolytic function is to a major extent explained by the presence of high plasma levels of plasminogen activator inhibitor-1 (PAI-1) and is most common in patients with hyperlipoproteinemias type IIB and IV. To further investigate the association between hypertriglyceridemia and elevated plasma levels of PAI-1, cultured human umbilical vein endothelial cells were exposed to purified lipoproteins isolated from normo- and hypertriglyceridemic (NTG and HTG) individuals. We found that very low density lipoprotein (VLDL) from both NTG and HTG subjects stimulated the secretion of PAI-1 from endothelial cells in a dose-dependent manner. HTG-VLDL at a concentration of 100 micrograms/ml gave rise to a 73% increase in PAI-1 secretion as compared to control cultures, whereas NTG-VLDL only gave rise to a 30% increase (p less than 0.05), indicating that HTG-VLDL is a more potent stimulus to PAI-1 secretion than is NTG-VLDL. Experiments in which endothelial cells were exposed to VLDL subfractions indicated that large VLDL particles, in particular, induce PAI-1 release. Binding experiments demonstrated a specific cellular binding of both NTG- and HTG-VLDL to the cells, but HTG-VLDL bound about four times more effectively than NTG-VLDL. Exposure of the endothelial cells to an LDL receptor antibody was found to block 75% (p less than 0.005) of the VLDL-induced secretion of PAI-1 from the cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies↗

PubMedDate not supplied

Clinical signs of familial hypercholesterolemia in patients with familial defective apolipoprotein B-100 and normal low density lipoprotein receptor function.

In a previous study (Tybjaerg-Hansen et al, Atherosclerosis 1990;80:235-242), we identified nine patients heterozygous for the apolipoprotein B (apo B) arginine-to-glutamine (Arg3,500----Gln) mutation (familial defective apolipoprotein B-100 [FDB]). Six of these had been diagnosed clinically as familial hypercholesterolemic (FH) heterozygotes. We have since examined low density lipoprotein (LDL) receptor function in the FDB index patients and in three of their families. Skin fibroblasts from seven of seven unrelated FDB patients from whom cell lines were established exhibited normal high-affinity binding and degradation of normal LDL in vitro. In the three families, a raised plasma LDL concentration did not segregate with a haplotype of two polymorphic restriction sites at the LDL receptor locus. We conclude that the clinical and biochemical signs of classical FH can occur in the presence of the FDB mutation and a normal LDL receptor gene. In a four-generation family with 11 proven or presumed FDB heterozygotes, expression of the mutation ranged from normal plasma LDL concentrations and no clinical signs in two individuals, to hypercholesterolemia and death from myocardial infarction at age 31. Variable expression of the FDB mutation could not be explained conclusively by variation in diet, body mass index, smoking habit, apo E genotype, or plasma Lp(a) concentration.

Adult↗

PubMedDate not supplied

Decreased neointimal thickening after arterial wall injury in inducible nitric oxide synthase knockout mice.

Mechanical injury in vivo results in the expression of the inducible form of nitric oxide synthase (iNOS) in vascular smooth muscle cells. However, the role of iNOS in modulating neointima formation after arterial wall injury is not clear. To determine whether the induction of iNOS gene expression promotes or attenuates the neointimal response to injury, we used a murine model of perivascular injury induced by placing a periadventitial collar around the carotid arteries in both wild-type and iNOS knockout mice (iNOS-KO mice). Periadventitial injury induced iNOS expression in the wild-type but not the iNOS-KO mice. Neointimal area and the intima/media ratio were significantly less in the iNOS-KO mice compared with the wild-type mice at 21 days. Injury-induced proliferation of medial cells and vascular cell adhesion molecule-1 expression were also attenuated in iNOS-KO mice compared with wild-type mice. The induction of iNOS and the activation of the nuclear factor-kappaB-mediated pathway were also demonstrated in an in vitro injury model. We conclude that mechanical injury in vivo and in vitro induces iNOS expression and that lack of iNOS expression attenuates neointima formation after perivascular arterial injury. Taken together, these findings suggest that iNOS expression after vascular injury may promote neointima formation.

Animals↗

PubMedDate not supplied

Functional and clinical changes in upper limb spastic patients treated with botulinum toxin (BTX).

Spasticity is a motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes (muscle tone) with exaggerated tendon jerks. In order to study the usefulness of botulinum toxin type A (BTX) as a therapy for spasticity, we studied 15 patients affected by spasticity secondary to stroke. Tests included: clinical evaluation of tone (Ashworth scale); active angles of extension and flexion at elbow and wrist; Hmax/Mmax ratio from flexor carpi radialis (FCR); Hreflex presynaptic inhibition from FCR during vibration; Task score; and video recording. Patients were injected with BTX into one or more muscles with total doses not exceeding 200 International Units (IU). The tests were performed immediately prior to injection and repeated 2 weeks afterwards. Furthermore, in eight patients, testing was also performed one month after BTX injection. Between two weeks and one month after BTX there were no statistically significant differences. A statistically significant difference in the Task and Ashworth scores before and after treatment emerged (p < 0.0014), but only 6 patients showed a clear improvement in motor performance. Overall, we observed an improvement in the angle of active extension and flexion at the wrist and elbow. There were no significant changes in the Hmax/Mmax ratio and the Hreflex presynaptic inhibition during vibration. All the patients reported a subjective improvement. The results suggest that subjective benefits can be gained from the use of BTX in patients affected by spasticity, and that the degree of motor improvement seems to depend on the motor recovery obtained before treatment.

Adult↗

PubMedDate not supplied

Masked myoclonus in corticobasal degeneration: neurophysiological study of a case.

A single case study of a 58 year-old male with right asymmetric apraxia and akinetic-rigid syndrome is described. Brainimaging scans (MRI, SPECT) indicated asymmetric cortical atrophy compatible with the diagnosis of Corticobasal Degeneration. Reflex myoclonus was absent and myoclonic discharges only appeared in response to pharmacological treatment of limb dystonia and rigidity. Electromyographic evidence of jerky movements was recorded only in the affected right hand and forearm after muscle relaxation, and myoclonus was not preceded by an EEG paroxysm. The cortical components of the correspondent SEPs were not increased in amplitude while LLRs recordings showed a late response over the muscles of the affected side. Furthermore, the duration of post MEP silent period was bilaterally reduced. This single case study report points out that sometimes myoclonus in Corticobasal Degeneration can be masked by the presence of increased muscle tone.

Apraxias↗

PubMedDate not supplied

EMGLAB: objective outcome measures in neurophysiological testing.

The aim of this work was to objectively measure and quantify the results of various neurophysiological tests and indirectly provide objective outcome measures for neurological therapy and rehabilitation. We have studied the silence of Electromyographic (EMG) activity after evoking motor potentials with magnetic cortical stimulation. Since different criteria were previously used to determine the level where the silence of muscle activity ends, an objective computer aided method was developed. This analysis was further developed to include objective testing of surface EMG, long latency reflexes, reciprocal inhibition of the H-reflex, H-reflex recovery curve and decrement testing. Responses were recorded at different sampling frequencies, depending on the application, time window, filter settings, etc. The developed software proved to be a fast and objective tool, able to standardize the determination of different neurophysiological tests, and as such a valuable tool facilitating multi-center studies and diminishing human bias. The software reduced the study time with each patient. Until date we have used the software with the Medtronic, Medelec and BTS EMG instruments.

Diagnosis, Computer-Assisted↗

PubMedDate not supplied

Management of neonatal hip instability: an analysis of the efficiency in a consistent treatment program.

The efficiency of a consistent treatment program for children with neonatal hip instability (NHI) was analyzed. Of 165 children who were referred to the orthopedic department with suspected NHI, 91 children had unstable hips and were treated with a von Rosen splint for 8 weeks; 74 children were found to have stable hips and were not treated, but were followed up in the same way as the treated children. All treated and untreated children developed clinically and radiologically normal hips. Treatment with a von Rosen splint is reliable, and with few exceptions 8 weeks is sufficient time for treatment of NHI.

Child, Preschool↗

PubMedDate not supplied

H-reflex recovery curve and reciprocal inhibition of H-reflex of the upper limbs in patients with spasticity secondary to stroke.

The H-reflex recovery curve of the lower limb is considered a useful test for the diagnosis of spasticity, and recently the reciprocal inhibition of the H-reflex has proven to be abnormal in patients affected with spasticity. We studied the H-reflex recovery curve and the reciprocal inhibition of the H-reflex in the upper limb of a group of 33 patients with different degrees of spasticity secondary to stroke. Results were compared with those of 25 controls. The aim of this study was to investigate if the two tests showed any direct correlation with the degree of spasticity and, furthermore, with other clinical measures that are present in patients with spasticity as part of an upper motoneuron syndrome (i.e., changes in muscle tone, reflexes, force, etc.). The results showed an abnormality of both tests in most patients (decrease of the three phases of inhibition in the reciprocal inhibition test and increase of the late facilitation part of the H-reflex recovery curve), and these abnormalities seem mostly to be related to muscle tone, most important being the degree of correlation between tone and changes in abnormality of the H-reflex recovery curve (P < 0.03).

Adult↗

PubMedDate not supplied

Functional correlates in the rehabilitation of occupational low back pain.

The aim of this preliminary report was to identify physiological parameters related to functional improvement in industrial workers with occupational low back pain (LBP) undergoing an intensive rehabilitation program. Four able-bodied and four LBP industrial workers were evaluated before and after a 4-week rehabilitation program. Dynamic and static strength tests, namely sustained isometric contractions, were performed in conjunction with surface electromyographic (EMG) measurements. Significant pre-rehabilitation differences were found between the two groups. Measured forces changed significantly in LBP subjects immediately after rehabilitation. No significative changes were found in the control subjects after the rehabilitation program. After rehabilitation, the slope of decay of the median frequency of the EMG power spectrum at L4 level, during a 60-sec isometric submaximal (60% MVC) contraction, decreased significantly (p < 0.02) indicating a lower fatigue level.

Adult↗