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Biomedical subjects

C Lindqvist

Publications and source records attributed to C Lindqvist.

At least 73 records · Page 4Linked to original sources
PubMed1997

Biocompatibility of solid poly (ortho ester).

In previous studies poly (ortho ester) (POE) has shown promise as a resorbable device, a hemostatic sealant and as a carrier for drugs in bone surgery. The aim of this study was to evaluate the tissue reactions of solid poly (ortho ester) implanted into both tibiae of 17 rabbits. One half of the rods were sterilized by gamma radiation and the other half by ethylene oxide. The follow-up times were from 1 week to 21 weeks, after which the animals were killed and the bony specimens examined histologically. The connective tissue samples were examined immunohistochemically in order to study the occurrences of two extracellular matrix glycoproteins, tenascin and fibronectin. The results showed that solid poly (ortho ester)s induce a moderate inflammatory reaction for 9 weeks. Tenascin and fibronectin were present in samples from 1 week up to 4 weeks. It was also found that gamma sterilized POE was resorbed at week 7 and ethylene oxide sterilized POE at week 13.

Journal Article↗
PubMed1997

Expression of the mouse interleukin-2 receptor gamma chain in insect cells using a baculovirus expression vector--comparison with the human common gamma chain.

The gene encoding the gamma-chain of the mouse Interleukin-2 receptor was expressed in lepidopteran insect cells using the baculovirus expression vector system. The corresponding gene was inserted under the polyhedrin promoter of the Autographa californica nuclear polyhedrosis virus and expressed in the Spodoptera frugiperda insect cell line Sf9 during viral infection. The recombinant receptor protein was identified by immunoblotting in cell lysates prepared from insect cells infected with the produced recombinant virus VL1392-mIL-2R gamma. Kinetic analysis demonstrated that the corresponding protein could be detected as an approximately 50 kDa protein already at 24 h post-infection. Intrinsic labelling with [35S]-methionine/cysteine and SDS-PAGE analysis of the recombinant baculovirus infected insect cells verified the immunoblotting data. The expressed IL-2R gamma protein could also be determined on the surface of infected insect cells by flow cytometric analysis. Comparison of the molecular weights between baculovirus expressed human and mouse IL-2R gamma chains indicated differences in the glycosylation pattern despite similar numbers of N-linked glycosylation sites.

Animals↗
PubMed1997

Phage-displayed Fab fragments against anti-human interleukin-2 receptor alpha. Detection of antigen-bound phages with anti-cpIII monoclonal antibodies.

The genes encoding the VHCH1 and VLCL parts of the mouse anti-human IL-2R alpha antibody 7G7B6 were amplified by PCR and the corresponding antibody fragments displayed on the surface of filamentous phages. The expression of Fab fragments was analysed by immunoblotting using HRP-labelled goat anti-mouse Ig antisera. By traditional hybridoma technology, splenocytes from Balb/c mice, immunized with native phage particles, were fused with P3X63-Ag8.653 myeloma cells in order to yield monoclonal antibodies against filamentous phage proteins. The obtained monoclonal antibody IF8 (mu/kappa) recognized the minor coat protein III as a 65-70 kDa protein band by immunoblotting, whereas the monoclonal antibody IVC8 (mu/kappa), in addition to cpIII, recognized a protein with an approximate molecular weight of 38-43 kDa. Both antibodies were employed to determine the binding specificity of the phage-displayed anti-human IL-2R alpha Fab fragments in an ELISA using recombinant baculovirus-expressed human IL-2R alpha proteins as antigens.

Amino Acid Sequence↗
PubMed1997

Human neutrophil collagenase MMP-8 in peri-implant sulcus fluid and its inhibition by clodronate.

The exact molecular mechanisms of the loosening of a dental implant are not well-known. The characteristics of implant sulci are similar to those of periodontal sulci regarding gingival crevicular fluid (GCF) and peri-implant sulcular fluid (PISF). Proteolytic enzymes, matrix metalloproteinases (MMPs), participate in peri-implant tissue remodeling. Clodronate is a well-tolerated bisphosphonate-group drug currently used in bone-resorption-related diseases in humans. The mechanisms of bisphosphonate action are not clarified. Collagenase activity in diseased PISF was significantly higher than in the clinically healthy group. Immunoblotting disclosed that diseased PISF contained increased immunoreactives MMP-8 compared with the healthy PISF. The residual latent collagenase activity in the diseased PISF was activated by gold thioglucose and inhibited completely by 100 microM of doxycycline closely resembling pure neutrophil collagenase (MMP-8). The presence of MMP-8 in diseased but not in clinically healthy PISF may prove to be a useful biochemical indicator to monitor peri-implant health and disease. Pure human neutrophil collagenase (MMP-8) and the MMP-8 present in PISF and in the GCF of both loosening implants and periodontitis-affected teeth were efficiently inhibited in vitro by clodronate (50% inhibition [IC50] was achieved by 150 microM of clodronate), an osteoactive, antiresorptive bisphosphonate. Furthermore, the new finding suggests an extended and hitherto-undescribed potential for clodronate in preventing the loosening of both implants and teeth, based on a dual beneficial effect: prevention of both bone resorption/osteolysis and of soft tissue/dental ligament destruction. Potential new therapeutic indications based on the collagenase-inhibiting effect of clodronate provide potential new therapeutic indications for a variety of diseased involving connective tissue breakdown, such as periodontal disease, arthritides, and tumor invasion.

Adult↗
PubMed1996

Time-resolved fluorometric assay for natural killer activity using target cells labelled with a fluorescence enhancing ligand.

A time-resolved fluorometric assay for the measurement of natural killer cell activity against target cells labelled with the acetoxymethyl ester of the fluorescence enhancing ligand 2,2':6',2"-terpyridine-6,6"-dicarboxylic acid (TDA) is described. The hydrophobic esterified form of TDA (bis(acetoxymethyl) 2,2':6',2"-terpyridine-6,6"-dicarboxylate, BATDA) diffuses readily through the cell membrane of viable cells. BATDA is hydrolysed by intracellular esterases resulting in accumulation of membrane impermeable TDA inside the target cells. After incubation of labelled K-562 cells with effector cells the TDA released from lysed cells into the supernatant is chelated with Eu3+. The natural killer cell activity is then quantified by measuring the intense fluorescence of the EuTDA chelates formed. Target cells are rapidly labelled when incubated with BATDA, TDA is released from target cells faster than 51Cr, the spontaneous release permits a short-term release assay to be set up and the detection of EuTDA is fast (5 min/96 well plate). Furthermore, this non-radioactive method permits the use of complex culture media since, in contrast to methods based on prompt fluorometry, the problem with autofluorescence can be avoided by the use of time-resolved fluorometry.

2,2'-Dipyridyl↗
PubMed1996

Green fluorescent protein as a tool for screening recombinant baculoviruses.

The gene encoding the green fluorescent protein (GFP) from the jellyfish Aequorea victoria, ligated to the honeybee melittin signal peptide-encoding sequence, was inserted under transcriptional control of the polyhedrin promoter of the Autographa californica nuclear polyhedrosis virus and expressed in the Spodoptera frugiperda insect cell line Sf9 during viral infection. The recombinant green fluorescent protein was identified by SDS-PAGE gel electrophoresis followed by Coomassie blue staining of lysates from the recombinant baculovirus infected insect cells. Emission and excitation scanning of the recombinant baculovirus infected insect cells gave an emission maximum of 509 nm and excitation maximum of 398 nm. The GFP protein expressed was also detected in infected insect cells by a flow cytometer analysis.

Animals↗
PubMed1996

Fixation with reconstruction plates under critical conditions: the role of screw characteristics.

Mandibular angular ostectomy defects in 12 sheep were bridged with a titanium plate system (THORP), designed according to the screw-plate-locking principle. Two screw designs (hollow and solid) and two rough (plasma-coated, sand-blasted)-surface and one smooth (anodized)-surface structure were tested in a critical two-screw anchorage model. Fixation with two screws only per fragment was successful in only one-third of the cases. The fixation results were superior for screws with a rough surface, either sand-blasted or plasma-coated. The hollow-screw design did not seem to offer special advantages over the solid screws with identical surface structure. In the successful cases, the bone-screw contact was maintained continuously over a period of 8 weeks, and anchorage was even enhanced by reinforcement of the cancellous structures. In the unsuccessful cases, peri-implant bone resorption seemed to be related to jeopardized bone perfusion in the vicinity of the implants. It is presumed that a plating system with locked screws has the advantage that only two screws will hold a relatively short condylar process. This study proved the assumption to be questionable. However, in view of the problems related to prosthetic replacement of the temporomandibular joint, an attempt to salvage the articular portion may still be justified in selected cases, even if the chance of success is as low as 30%.

Animals↗
PubMed1996

Lag-screw fixation of mandibular parasymphyseal and angle fractures.

OBJECTIVE: This study was carried out to evaluate clinical and radiologic results after lag-screw fixation (LSF) of mandibular parasymphyseal and angular fractures was performed. STUDY DESIGN: Seven angle and 17 parasymphyseal fractures in 23 adult patients with mandibular fractures were treated by transoral reduction and LSF. Clinical and radiologic examinations were undertaken during a 3-month follow-up period RESULTS: All parasymphyseal fractures and four angular fractures went to good bone union after surgery. Infectious complications occurred in two patients with parasymphyseal fractures. These resolved with simple procedures. Three angular fractures needed refixing because of instability. Slight occlusal adjustment was needed in five patients. Postoperative neurosensory deficits were transient in every case in which they were seen. CONCLUSIONS: LSF of mandibular parasymphyseal fractures is a practical and effective way of fixing such fractures internally. It leads to good bone healing without permanent neurosensory deficit or increased risk of malocclusion. In mandibular angle fractures LSF is likely to be too technique-sensitive to allow its extensive use.

Adolescent↗
PubMed1996

Opportunistic osteomyelitis in the jaws of children on immunosuppressive chemotherapy.

PURPOSE: Four children with an osteomyelitic process in the jaw bones while on cytotoxic chemotherapy were treated by radical surgery and antimicrobial chemotherapy. PATIENTS AND METHODS: Symptoms (local swelling and pain in the jaw, necrotic gingivitis, and spontaneous loss of teeth) appeared 3 weeks, 4 weeks, and 8 months after diagnosis of leukemia, and 8 days posttransplant in a patient with severe aplastic anemia. Three had the process in the mandible and one in the maxilla. Specific diagnoses of Aspergillus flavus, Saccharomyces cerevisiae, and Actinomyces species were obtained histologically from surgical samples. Treatment was radical surgery to remove all infected and necrotic tissue: removal of a substantial part of the mandible and loss of seven to eight permanent teeth in those with mandibular lesions. Actinomycosis was treated with penicillin for 2 years. The patients with fungal lesions received amphotericin B for 2, 5, and 6 months, with adjuvant itraconazole, fluconazole, or 5-fluorocytosine for 9-12 months. Anti-cancer chemotherapy was continued. RESULTS: All the bony lesions healed. The patient with acute myeloid leukemia died in relapse 1 year postdiagnosis; her aspergillus osteomyelitis had been inactive for 8 months. The other three patients are alive and well 1.9, 2.1, and 1.9 years after termination of antimicrobial therapy. CONCLUSIONS: We emphasize the necessity of specific diagnosis from appropriate surgical samples and conclude that in patients undergoing chemotherapy bony lesions caused by opportunistic microorganisms may be curable with aggressive surgery and prolonged medication.

Actinomycosis↗
PubMed1996

Mast cell-derived tryptase in odontogenic cysts.

Inflammatory and developmental cysts of the jaws are relatively common bone destructive lesions in the human maxillofacial skeleton but their pathogenesis is still poorly understood. In this study the role of mast cells (MC), and mast cell tryptase in particular, was evaluated in the pathophysiology of bone resorption and jaw cyst formation in different types of cysts. The distribution of MC and the amount of tryptase in histological tissue sections were determined by immunohistochemistry using monoclonal antihuman tryptase antibodies and the results were quantitated by using an image analyzing system. The amount of tryptase was further studied by Western-blotting and measurement of trypsin-like activity from the neutral salt extracts obtained from different types of jaw cysts. In contrast to control tissue, high trypsin-like activities and abundant immunoreactive tryptase were observed in the extracts of all types of cysts studied (radicular, dentigerous and keratocyst). In tissue sections the highest amount of tryptase-positive staining was observed in radicular cysts (mean 6.2% of reference area) and the lowest amount in keratocysts (mean 2.1% of reference area, P < 0.01). MC were found to be located in inflammatory cell-rich tissue areas and just beneath the cyst epithelium. Importantly, MC located at the border of bone were observed to be degranulated, indicating high activity of MC and release of tryptase at the regions of early bone destruction. Based on previous findings addressing the role of mast cell tryptase in proteolytic cascades, and the known association of MC with osteoporosis, we suggest that mast cells and mast cell tryptase may contribute significantly to jaw cyst tissue remodelling during growth of a cyst, and to the destruction of the surrounding bone, resulting in jaw cyst expansion.

Adolescent↗
PubMed1996

Detection of rubella virus-specific immunoglobulin M antibodies with a baculovirus-expressed E1 protein.

The structural proteins of rubella virus (RV) were expressed in insect cells by using the baculovirus expression vector system. The recombinant E1 envelope glycoprotein was purified by immunoaffinity chromatography and used to detect RV-specific immunoglobulin M antibodies in a time-resolved fluoroimmunoassay. Correlation analysis between the reactivities of antibodies against this recombinant E1 and the reactivities against authentic RV antigen shows that purified E1 can detect RV antibodies of the immunoglobulin M type.

Antibodies, Viral↗
PubMed1996

Identification of biotinylated molecules using a baculovirus-expressed luciferase-streptavidin fusion protein.

A genetic fusion between streptavidin of Streptomyces avidinii and luciferase of Pyrophorus plagiophthalamus was constructed. The fusion protein was produced in the Sf9 insect cell line using the baculovirus expression vector system (BEVS). Sodium dodecyl sulfate polyacrylamide gel electrophoresis of the proteins from cells infected with the recombinant virus, VL1393-LucGR-StreptAv, revealed that the fusion protein migrated with an apparent molecular weight of 75 kDa. Light emission measurements showed that the infected cells produced about 255 mg of the chimeric protein per liter of cell culture (127.5 micrograms/1 x 10(6) cells). Precipitation of the LucGR-StreptAv fusion protein with biotinylated acrylic beads as well as immunoblot analyses using biotinylated immunoglobulins indicated that both fusion moieties of the chimeric protein product were functional with respect to their physical and enzymatic activities.

Animals↗
PubMed1995

Rapid Ca2+ mobilization in single LGL cells upon interaction with K562 target cells--role of the CD18 and CD16 molecules.

Changes in the intracellular Ca2+ levels of human large granular lymphocytes (LGL), loaded with the fluorescent Ca2+ indicator fura-2, have been studied upon addition of human chronic myelogenous leukemia K562 cells. The measurements, analyzed at the single-cell level using image analysis, indicate a rapid Ca2+ mobilization in the effector cell upon interaction with its target cell. This mobilization appeared to be localized to an area within the effector cell that was in physical contact with target cells. The LGL responded with different kinetics in a transient manner and about 19% of them could undergo two or more responses. Data obtained from experiments performed with anti-CD16- and anti-CD18-pretreated LGL in the presence of target cells indicate that the CD16 and CD18 molecules are not likely to be the triggers of the Ca2+ response, although they might participate in the recognition of the target cell.

Antibodies, Monoclonal↗
PubMed1995

Midfacial fractures in pediatric patients. Frequency, characteristics, and causes.

OBJECTIVE: To determine the frequency, characteristics, and causes of midfacial fractures in children. DESIGN: A retrospective review of the patients' medical charts and radiographs. SETTING: Tertiary referral center. PATIENTS: Fifty-four patients under 16 years of age, with midfacial fractures diagnosed and treated in the Helsinki (Finland) University Central Hospital from 1980 through 1992. MAIN OUTCOME MEASUREMENTS: The data examined included sex, age, time and cause of the accident, type and location of the fractures, the presence and location of associated injuries, complications, and treatment methods. RESULTS: The male-to-female ratio was 1.16:1. Motor-vehicle accident was the most common cause of injuries. The frequency of injuries was in decreasing order: (1) maxillary alveolar bone, (2) zygoma, and (3) Le Fort fractures of the maxilla. The majority of injuries occurred in subjects who were 13 to 15 years old. In children less than 6 years old, only alveolar fractures occurred. For the other age groups, no significant difference in the fracture pattern was found. No fatalities occurred in this patient series. CONCLUSIONS: Midfacial pediatric fractures are rare. A high velocity force, such as that from a motor-vehicle accident is a factor producing the injury. Owing to the high impact, associated injuries are common. The severity of the insult is more essential than the age of the patient and the development of the paranasal sinuses.

Adolescent↗
PubMed1995

Synthesis and processing of the rubella virus p110 polyprotein precursor in baculovirus-infected Spodoptera frugiperda cells.

In order to study the processing of rubella virus (RV) structural proteins (capsid protein, of 33 kDa; E2 of 42-47 kDa; and E1 of 58 kDa) in Spodoptera frugiperda (fall armyworm) cells, a 24S cDNA encoding the polyprotein precursor, p110, was inserted under the transcriptional regulation of the polyhedrin gene promoter of the Autographa californica nuclear polyhedrosis virus (AcNPV) and expressed during viral infection. By immunoblot analysis using antibodies directed against whole RV and the individual structural proteins, evidence is presented that polypeptides similar to those synthesized in RV-infected B-Vero cells are expressed in this lepidopteran insect cell line infected with the recombinant baculovirus, VL1392-RV24S. The identity of the recombinant proteins was further confirmed using human convalescent sera. By expressing the recombinant proteins in the presence and absence of tunicamycin, we have further demonstrated that the 24S transcription-translation unit of RV, is expressed and proteolytically cleaved similarly, if not identically, in Sf9 cells as compared to B-Vero cells.

Animals↗
PubMed1995

Lag-screw osteosynthesis of mandibular condyle fractures: a clinical and radiological study.

PURPOSE: This study evaluates the clinical and radiologic results after open reduction and lag-screw osteosynthesis of fractured mandibular condyles. MATERIALS AND METHODS: Eleven adult patients underwent surgery for displaced or dislocated mandibular condyle fractures via a submandibular approach. The repositioned fragments were fixed using lag screws designed by Krenkel or Eckelt. Maxillomandibular fixation was used postoperatively for 2.6 weeks on average (range, 1 to 4 weeks) in nine patients. RESULTS: Slight transient weakness of the mandibular branch of the facial nerve occurred in three cases. Occlusal adjustment was needed in another three cases. Radiologically, the fracture line disappeared at 22.5 weeks on average (range, 8 to 38 weeks). Three screws had to be removed because of loosening. There were signs that the screws had migrated caudally from their original position in seven cases. Twenty-one months on average after operation (range, 8 to 31 months), patients were satisfied with treatment. Clinically, all patients had a stable occlusion and symmetry of the face. All had greater than 5-mm symmetrical lateral jaw excursions. Ten patients had wide (> 40 mm) painless mouth opening. Healing in malposition occurred in four cases and there was considerable shortening of the mandibular ramus in four cases. CONCLUSIONS: Despite good clinical results, lag screws do not meet the needs for rigid internal fixation in the treatment of mandibular condyle fractures.

Adult↗
PubMed1995

Expression of the human interleukin-2 receptor gamma chain in insect cells using a baculovirus expression vector.

The gene encoding the gamma-chain of the human Interleukin-2 receptor was expressed in lepidopteran insect cells using the baculovirus expression vector system. The corresponding gene was inserted under the polyhedrin promoter of the Autographa californica nuclear polyhedrosis virus and expressed in the Spodoptera frugiperda insect cell line Sf9 during viral infection. The recombinant receptor protein was identified by immunoblotting in cell lysates, prepared from insect cells infected with the recombinant virus. At 40 h post infection the corresponding protein was detected as two major bands with apparent molecular weights of 50-60 kDa using a rabbit anti-human IL-2R gamma-receptor specific antiserum. Metabolic labelling with [35S]-methionine and SDS-PAGE analysis of the recombinant baculovirus infected insect cells verified the immunoblotting data. The expressed IL-2R gamma- protein could also be determined on the surface of infected insect cells by flow cytometer analysis.

Animals↗