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H Sandberg

Publications and source records attributed to H Sandberg.

At least 19 recordsLinked to original sources
PubMed1998

Influence of phospholipids on the assessment of factor VIII activity.

In view of reported discrepancies between different factor VIII assays, the influence of phospholipids on the performance of one-stage clotting (OS) and chromogenic substrate (CS) assays was evaluated. The B domain deleted recombinant factor VIII, rVIII SQ, two full-length recombinant products and a plasma derived factor VIII concentrate were each diluted into severe haemophilia A plasma and assayed against a plasma standard. The one-stage activity was 50, 80, 75 and 106%, respectively, of the chromogenic result. Variations in the phospholipid concentration did not affect the chromogenic assay, except at very low levels where the apparent activity increased. In contrast, dilution of the phospholipid reagent had a substantial influence on the activity measured by OS assays, especially in the case of rVIII SQ. At low levels of phospholipid, the one-stage activity of rVIII SQ exceeded the chromogenic result. When mixtures of phosphatidylserine (PS) and phosphatidyl-choline (PC) were used as a source of phospholipid, the OS results for rVIII SQ agreed well with the CS activity as long as the content of PS was below 10%, i.e., closer to the physiological level. At higher levels of PS, as in most commercial APTT reagents, the OS activity decreased. When the APTT reagent was replaced by platelets in the OS assay, the results compared well with those obtained by the CS assay for both t-VIII SQ and full-length factor VIII products.

Biological Assay↗
PubMed1995

Novel forms of B-domain-deleted recombinant factor VIII molecules. Construction and biochemical characterization.

Recombinant molecules similar to the smallest active plasma-derived factor VIII molecule, a complex of an 80-kDa and a 90-kDa polypeptide chain lacking the B domain, have been produced using various factor VIII cDNA constructs in order to obtain primary translation products which were efficiently processed into the 80 + 90-kDa complex. Three types of single-chain cDNAs encoding B-domain-deleted derivatives factor VIII were designed, taking account of sites at Arg740 and Glu1649, assumed to be important for processing factor VIII. In the type 1 constructs, either Arg747, Arg752, or Arg776 in the N-terminal region of factor VIII B domain was fused to the N-terminus (Glu1649) of the 80-kDa subunit. In the type 2 construct r-VIII SQ, Ser743 was fused to Gln1638, creating a link of 14 amino acids between the C-terminus (Arg740) of the 90-kDa chain and N-terminus of the 80-kDa chain, whereas in type 2 r-VIII RH, Arg747 was fused to His1646. In the type 3 constructs, the B-domain was completely removed or replaced with 1-4 Arg residues. After expression in Chinese hamster ovary cells, the type 1 derivatives and the type 3 derivatives with 0-2 Arg residues inserted were found to be only partially processed and contained a large amount of the 170-kDa primary translation product. In contrast, most of the type 2 derivatives r-VIII SQ and r-VIII RH and the type 3 derivatives r-VIII R4 and r-VIII R5 containing three or four extra Arg residues preceding the N-terminus of the 80-kDa chain were processed into the desired 80 + 90-kDa chain complexes. The feature common to the most efficiently processed factor VIII deletion derivatives was that they contained the recognition motif for proteolytic cleavage by the membrane-bound subtilisin-like protease furin, which is expressed in most types of cells; that is, basic amino acid residues at positions -1 and -4 relative to the cleavage site at Glu1649. Biochemical studies of r-VIII SQ and r-VIII R5, two of the most effectively processed factor VIII derivatives, showed that both proteins had a normal factor VIII cofactor function, and had N- and C-termini of the 80-kDa and 90-kDa chains corresponding to those found in plasma-derived factor VIII.

Amino Acid Sequence↗
PubMed1994

[Partial versus total meniscectomy. A prospective, randomized study].

Two hundred patients with a meniscus lesion were peroperatively allocated to partial or total meniscectomy. The results were compared at one year and at 6.3-9.8 years (median 7.8). After one year, more patients with partial meniscectomy (90%) than with total meniscectomy (80%) had no complaints (p = 0.029). At the late review these figures were 62% and 52% respectively (p = 0.18). However, patients with partial meniscectomy had the highest functional scores. In five percent knee joint function had improved and in 35% deteriorated, in the latter group without detectable difference between partial and total meniscectomy. The incidence of lateral laxity rose from eight to 47%, most frequently seen after total meniscectomy. During the observation period radiological signs of knee joint degeneration changed from solely joint line narrowing into additional ridge formation and flattening of the femoral condyle, but unrelated to whether partial or total meniscectomy had been performed. Following partial meniscectomy posterior horn lesions had the poorest functional outcome, but only if more than one third of the meniscal surface had been removed. The amount of meniscal tissue excised was inversely correlated to the level of knee joint function except in bucket handle lesions treated with partial meniscectomy. These lesions had the largest areas of meniscal tissue removed, but higher functional scores than posterior horn lesions. Preservation of the peripheral rim of the meniscus following partial meniscectomy was essential for the functional outcome after surgery.

Adolescent↗
PubMed1992

The long term outcome of open total and partial meniscectomy related to the quantity and site of the meniscus removed.

Two hundred patients were randomly selected for either a partial or a total meniscectomy for a meniscal tear during open operation. They were followed for a median of 7.8 years after operation. After partial meniscectomy, posterior horn tears had the worst outcome, but this was only apparent when more than two-thirds of the meniscus had been removed. The amount of meniscal tissue excised was inversely related to the function of the knee, except with bucket-handle tears treated by partial meniscectomy. Patients with bucket-handle, anterior and posterior horn tears had similar functional results after total meniscectomy. Preservation of the peripheral rim of the meniscus following partial meniscectomy produces the best functional results.

Follow-Up Studies↗
PubMed1992

Partial versus total meniscectomy. A prospective, randomised study with long-term follow-up.

Two hundred patients with a meniscal lesion were peroperatively allocated to partial or total meniscectomy in a random manner. The results were compared at one year and at 6.3 to 9.8 years (median 7.8). After one year more patients with partial meniscectomy (90%) than with total meniscectomy (80%) had no complaints. At the later review these figures were 62% and 52%, respectively (p = 0.18). However, patients with partial meniscectomy had higher functional scores. The deterioration in function between the first review and the second showed no significant difference in the two treatment groups. The incidence of mediolateral instability rose from 8% to 47% and was more frequent after total than after partial meniscectomy. Between the two reviews the radiological signs of knee degeneration increased with no difference between the two treatment groups.

Follow-Up Studies↗
PubMed1990

Characterization of human factor VIII and interaction with von Willebrand factor. An electron microscopic study.

Blood coagulation factor VIII is a large glycoprotein that circulates in plasma at relative low concentration (0.1 microgram/ml). It consists of a heterogeneous mixture of a series heavy-chain peptides (90-200 kDa), each associated with a light chain of 80 kDa. To gain insight into the physical properties of the protein, we have characterized purified human factor VIII by electron microscopy and rotary shadowing. Electron microscopy of rotary shadowed factor VIII molecules showed predominantly a single globular domain structure, with a somewhat asymmetric shape, while two-domain structures were also encountered. The overall dimensions of the globular domains ranged from 4 x 6 nm to 8 x 12 nm. EDTA treatment of factor VIII reduced the overall dimensions (2.5 x 5 nm to 6 x 10 nm) while treatment with thrombin reduced the dimensions to a small extent. In complexes with von Willebrand factor, factor VIII appeared localized at the globular domains of von Willebrand factor multimers. In addition, incubation of factor VIII with Staphylococcus aureus V8 protease fragments SpII and SpIII revealed only binding to the globular domains of SpIII. In this study, the first morphological characterization of human factor VIII is presented, together with its direct localization on von Willebrand factor multimers.

Blotting, Western↗
PubMed1990

Detection and quantitation by lysis-filtration of bacteremia after different oral surgical procedures.

Patients with bacteremia after dental extraction, third-molar surgery, dental scaling, endodontic treatment, and bilateral tonsillectomy were studied by means of lysis-filtration of blood samples with subsequent aerobic and anaerobic incubation. Samples were obtained before, during, and 10 min after treatment. Bacteremia was observed in 100% of patients after dental extraction, 55% of patients after third-molar surgery, 70% of patients after dental scaling, 20% of patients after endodontic treatment, and 55% of patients after bilateral tonsillectomy. Anaerobic microorganisms were isolated more frequently than aerobic microorganisms were, and viridans group streptococci were the most commonly isolated bacteria. Ten minutes after treatment, the frequency as well as the magnitude of bacteremia showed pronounced reduction.

Adolescent↗
PubMed1989

Secretion of coagulant factor VIII activity and antigen by in vitro cultivated rat liver sinusoidal endothelial cells.

Different types of liver cells and a few extrahepatic cell types were analysed for the presence and production of factor VIII activity (VIII:C). Only freshly prepared suspensions of rat liver sinusoidal cells and pure monolayer cultures of rat liver endothelial cells (LEC) were found to contain and secrete detectable amounts of the coagulation factor. Secretion of VIII:C by cultured LEC was inhibited by cycloheximide and by monensin. Constant levels of VIII:C were produced for at least 48 h suggesting continuous synthesis rather than a burst release of stored material. VIII:C, as measured spectro-photometrically by conversion of X to Xa, was inhibited by anti-human VIII:C antiserum. Indirect immunocytochemistry using this antiserum gave positive staining only with LEC. Immunoprecipitation of metabolically labelled proteins in conditioned rat LEC medium with the anti human VIII:C antiserum revealed the presence of proteins of similar sizes to those reported for human VIII:C. These results indicate that rat LEC are an important site for production and secretion of procoagulant factor VIII and are not only a site for storage and release of the factor. The established conditions for synthesis of VIII:C in in vitro cultivated rat LEC should provide the means to study the regulation of VIII:C synthesis.

Animals↗
PubMed1986

Isolation and characterization of human factor VIII: molecular forms in commercial factor VIII concentrate, cryoprecipitate, and plasma.

Human factor VIII has been isolated from a high purity factor VIII concentrate by immunoaffinity chromatography and HPLC on Mono Q gel. Two fractions of factor VIII were obtained with a specific activity of approximately equal to 7000 units/mg. The major fraction contained eight peptide chains of 200, 180, 160, 150, 135, 130, 115, and 105 kDa plus one doublet chain of 80 kDa. The minor fraction contained one peptide chain of 90 kDa plus the chain of 80 kDa. Both fractions were activated by thrombin to the same extent. Amino-terminal amino acid sequence analysis was performed on the 180-kDa, 130-kDa, and 90-kDa chains and showed an identical amino-terminal sequence in these chains. Each chain from 200 kDa to 90 kDa was linked to one 80-kDa chain by a metal-ion bridge(s). Studies on factor VIII in plasma and cryoprecipitate, prepared and gel filtered in the presence of protease inhibitors, showed that one 200-kDa plus one 80-kDa chain were the only or dominating chains in the materials and may represent native factor VIII. The results indicated that all chains from 180 kDa to 90 kDa are fragments of the 200-kDa chain. All of these more or less fragmented chains form active factor VIII complexes with the 80-kDa chain.

Amino Acid Sequence↗
PubMed1985

Comparison of the abilities of synthetic and platelet-derived membranes to enhance thrombin formation.

The relative abilities of platelet-derived membranes and synthetic phospholipid vesicles to enhance the prothrombinase-catalyzed conversion of prothrombin to thrombin have been determined. For each type of membrane, the maximum amount of thrombin formed as a function of amount of available lipid was measured using a chromogenic substrate assay. The lipid concentration at which the amount of thrombin formed began to exceed that formed in the absence of lipid (critical phospholipid concentration) was used to compare the surfaces' abilities to support thrombin formation. For platelet-derived membranes and for equimolar, charged-lipid/phosphatidylcholine (PC) vesicles, the critical concentrations increased in the following order: platelet-derived membranes approximately equal to phosphatidylserine (PS) approximately equal to phosphatidic acid (PA) less than monomethyl PA and monoethyl PA much less than phosphatidylinositol and phosphatidylglycerol. For mixed anionic/neutral lipid vesicles above their phase transitions, measured critical concentrations were relatively insensitive to changes in lipid acyl chains, the neutral lipid component, and membrane curvature but were sensitive to changes in the anionic lipid content of the mixtures. Comparison of these data suggested that equimolar PS/PC and PA/PC vesicles can emulate reasonably well the thrombin-generating ability of platelet-derived membranes.

Blood Platelets↗
PubMed1985

Association of factor V activity with membranous vesicles released from human platelets: requirement for platelet stimulation.

The membrane-associated factor V-like activity (platelet factor 1, PF1) and the phospholipid-like catalytic surface activity (platelet factor 3, PF3) were studied in human platelets from normal and two factor V-deficient donors. Collagen stimulation or mechanical disruption of gel-filtered platelets was necessary for the expression of significant amounts of PF1 and PF3. Stimulation was also necessary for the uptake of factor V or Va by PF1-deficient platelets from the factor V-deficient donors. The activity of PF1 was also generated by association of factor V or Va with membrane-rich fractions obtained by gel filtration of the supernatant from collagen-stimulated or frozen-thawed PF1-deficient platelets. The amount of PF1 obtained by such all-or-none binding experiments was directly proportional to the amount of PF3 already expressed in the platelet preparation. These data have been summarized in terms of a hypothesis which views PF1 and PF3 to be activities associated with membranous vesicles released from platelets only after stimulation.

Blood Coagulation Factors↗
PubMed1985

Expression of coagulant activity in human platelets: release of membranous vesicles providing platelet factor 1 and platelet factor 3.

The relationship between the appearance of membrane-associated factor V-like activity (platelet factor 1, PF1) and phospholipid-like catalytic activity (platelet factor 3, PF3) has been examined, in vitro, in collagen-stimulated, human platelets. Both activities increased 7 fold upon collagen treatment relative to stirred controls. After sedimentation of stimulated platelets, 31% of total PF1 and 41% of PF3 remained in the supernatant fraction. PF1 eluted from a Sepharose CL-4B column in the same void volume fractions as PF3, phospholipid, and vesicular particles. These fractions had roughly 100 fold (lipid basis) or 1000 fold (protein basis) enhanced specific activity when compared to the stimulated platelet suspension. Freeze-fracture electron microscopy demonstrated that these void volume fractions contain two populations of membranous vesicles (80-200 nm and 400-600 nm in diameter). Upon centrifugation of the void volume fractions, PF1 and PF3 activities, phosphate-containing material, and ultraviolet-absorbing material all sedimented at the same rate, indicating that PF1 and PF3 are activities associated with one or both of the platelet-derived vesicle populations. Finally, we examined the effects of inhibitors on the appearance of PF1, PF3, platelet factor 4, total intrinsic factor V activity, and serotonin as well as on platelet aggregation. These studies suggest that the collagen-stimulated release of PF1 and PF3 is not coupled to either platelet aggregation or PF4 release but is probably a separate phase of the release reaction.

Blood Coagulation Factors↗
PubMed1985

Purified human factor VIII procoagulant protein: comparative hemostatic response after infusions into hemophilic and von Willebrand disease dogs.

The procoagulant protein F.VIII:C is noncovalently bound to von Willebrand factor (vWF) to give the factor VIII macromolecular complex. New highly purified preparations of isolated human F.VIII:C, devoid of vWF and about 500,000-fold purified, were administered to hemophilia A and von Willebrand disease (vWD) dogs to determine their hemostatic effectiveness and survival in the circulation. Two preparations of F.VIII:C were used: peak 1, with active components of Mr 185,000-280,000, and peak 2, with a single component of Mr 170,000. In hemophilic dogs, with no plasma F.VIII:C but normal vWF, both preparations immediately elevated plasma F.VIII:C to expected levels, promptly stopped induced and spontaneous hemorrhages, and gave sustained plasma levels of F.VIII:C. The isolated F.VIII:C immediately complexed with endogenous vWF in hemophilic plasma and was eliminated exponentially, with a half-life (t1/2) of about 9 hr. Survival of peak 2 F.VIII:C was longer than that of peak 1 material. In contrast, F.VIII:C complexed to vWF in a therapeutic concentrate administered to hemophilic dogs was eliminated biexponentially with first-phase t1/2 of 3.2 hr and second-phase t1/2 of 9 hr. In vWD dogs with no vWF and reduced F.VIII:C levels, the isolated F.VIII:C produced supernormal levels of F.VIII:C without effect on induced bleeding. It was rapidly eliminated from plasma with a t1/2 of about 1 hr, as was the complexed F.VIII:C in the concentrate. These data indicate that isolated F.VIII:C promptly complexes with vWF and in this form is highly effective in controlling hemophilic hemorrhages with good survival in plasma. Without endogenous vWF with which to complex, the F.VIII:C is promptly eliminated.

Animals↗
PubMed1985

Sports injuries of the knee ligaments--a prospective stress radiographic study.

Forty-six patients were entered into a prospective clinical and stress radiographic study done to assess the value of acute surgical treatment of injuries to the knee ligaments sustained during sports activities. After an average follow-up period of 5 1/2 years (range 4-6 1/2 years) medial instability was found only in two patients, both of whom were in the group with isolated rupture of the medial collateral ligament. Nine of the 29 patients in this group developed rotatory instability, but it was moderate and did not give rise to symptoms. Among the 17 patients with either injuries to the anterior cruciate ligament or combined injuries, anterior drawer instability persisted in seven, with an insufficient functional result in five. None of these 17 patients were able to resume competitive sport. Those patients who had not exercised physically just before the injury proved to have a significantly greater total instability than those who had. Therefore, routine limbering-up is recommended before sports activities.

Adolescent↗