Management and treatment outcome of DRESS patients in Europe: An international multicentre retrospective study of 141 cases

BACKGROUND

Drug reaction with eosinophilia and systemic symptoms (DRESS) is a rare but potentially fatal drug hypersensitivity reaction.

OBJECTIVE

To explore treatment approaches across Europe and their impact on the disease course, as well as prognostic factors and culprit drugs.

METHODS

In this retrospective European multicentric study, we included patients with probable or certain DRESS (RegiSCAR score ≥ 4) between January 2016 and December 2020. Independent associations between clinical parameters and the risk of intensive care unit admission and mortality at three months were assessed using a multivariable-adjusted logistic regression model.

RESULTS

A total of 141 patients from 8 tertiary centres were included. Morbilliform exanthem was the most frequent cutaneous manifestation (78.0%). The mean affected body surface area (BSA) was 67%, 42% of the patients presented with erythroderma, and 24.8% had mucosal involvement. Based on systemic involvement, 31.9% of the patients had a severe DRESS. Anticonvulsants (24.1%) and sulphonamides (22.0%) were the most frequent causative agents. In all, 73% of the patients were treated with systemic glucocorticoids, and 25.5% received topical corticosteroids as monotherapy. Few patients received antiviral drugs or anti-IL5. No patients received intravenous immunoglobulins. The overall mortality was 7.1%. Independent predictors of mortality were older age (≥57.0 years; fully adjusted OR, 9.80; 95% CI, 1.20-79.93; p = 0.033), kidney involvement (fully adjusted OR, 4.70; 95% CI, 1.00-24.12; p = 0.049), and admission in intensive care unit (fully adjusted OR, 8.12; 95% CI, 1.90-34.67; p = 0.005). Relapse of DRESS and delayed autoimmune sequelae occurred in 8.5% and 12.1% of patients, respectively.

CONCLUSIONS

This study underlines the need for diagnostic and prognostic scores/markers as well as for prospective clinical trials of drugs with the potential to reduce mortality and complications of DRESS.

Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

Radiological diagnosis of periapical bone tissue lesions in endodontics: a systematic review

This systematic review evaluates the diagnostic accuracy of radiographic methods employed to indicate presence/absence and changes over time of periapical bone lesions. Also investigated were the leads radiographic images may give about the nature of the process and the condition of the pulp in nonendodontically treated teeth. Electronic literature search included the databases PubMed, Embase and CENTRAL from January 1950 to June 2011. All languages were accepted provided there was an abstract in English. The MeSH terms were 'Cone beam computed tomography (CBCT)', 'Radiography, panoramic', 'Periapical diseases', 'Dental pulp diseases', 'Sensitivity and specificity', 'receiver operating characteristics (ROC) curve', 'Cadaver', 'Endodontics' and 'Radiography dental'. Two reviewers independently assessed abstracts and full text articles. An article was read in full text if at least one of the two reviewers considered an abstract to be potentially relevant. Altogether, 181 articles were read in full text. The GRADE approach was used to assess the quality of evidence of each radiographic method based on studies of high or moderate quality. Twenty-six studies fulfilled criteria set for inclusion. None was of high quality; 11 were of moderate quality. There is insufficient evidence that the digital intraoral radiographic technique is diagnostically as accurate as the conventional film technique. The same applies to CBCT. No conclusions can be drawn regarding the accuracy of radiological examination in identifying various forms of periapical bone tissue changes or about the pulpal condition.

Mapping and partial characterization of proteases expressed by a CHO production cell line

The proteolytic activities expressed by a Chinese hamster ovary (CHO) cell line in the cultivation supernatant during the production of recombinant factor VIII were mapped with a broad spectrum protease assay and a series of different types of protease inhibitors. The destabilizing effect on the product emanated from a metalloproteinase, which could be effectively blocked by chelating agents to lead to product stabilization. Amino acid sequences of the isolated metalloproteinase were found to have sequence homology with matrix metalloproteinases (MMPs) MMP3, MMP10, and MMP12. Several species with metalloproteinase activity were characterized and found to be related to each other. The results indicate that an MMP pro-enzyme of >/=200 kDa was released from the CHO cells during the production phase. The enzyme expressed collagenase/gelatinase activity when activated. Due to autoproteolysis, a number of smaller, less specific MMPs were formed with the smallest form, a 19.4 kDa protein, being the most active. These results may be of particular relevance for other production processes using CHO cells for the expression of recombinant proteins.

Structural and functional characterization of B-domain deleted recombinant factor VIII

A new high-purity recombinant factor VIII preparation has been developed for the treatment of hemophilia A. Structurally, this factor VIII preparation, B-domain deleted recombinant factor VIII (BDDrFVIII), differs from other recombinant and plasma-derived factor VIII preparations in that most of the B-domain has been deleted. To ensure that BDDrFVIII contains the requisite structural and functional features, it has been subjected to detailed biochemical and biophysical characterization in comparison to the plasma-derived form of factor VIII. Laboratory studies have shown that the primary, secondary, and tertiary structures of BDDrFVIII and the posttranslational modifications are similar to those of the [80 + 90]-kd form of plasma-derived factor VIII. In addition, BDDrFVIII has full biologic activity compared with full-length factor VIII preparations.

Structural and functional characteristics of the B-domain-deleted recombinant factor VIII protein, r-VIII SQ

Recombinant factor VIII SQ (r-VIII SQ), ReFacto, is a recombinant factor VIII product similar to the smallest active factor VIII protein found in plasma-derived factor VIII (p-VIII) concentrates. The protein comprises two polypeptide chains of 80 and 90 kDa and lacks the major part of the heavily glycosylated B-domain i.e. amino acids Gln744 to Ser1637. r-VIII SQ retains six potential glycosylation sites for N-linked oligosaccharides at asparagine residues 41, 239, 582, 1685, 1810 and 2118. We describe a thorough comparison of the characteristics of r-VIII SQ with those of p-VIII. The primary and secondary structures of r-VIII SQ were in good agreement with that of B-domain-deleted p-VIII (p-VIII-LMW) as shown by SDS-PAGE, Western blotting with antifactor VIII antibodies, tryptic mapping, amino acid sequence analysis and circular dichroism spectroscopy. A few divergences also existed. Thus r-VIII SQ was shown to contain a small amount of the single chain primary translation product of 170 kDa and also the product specific sequence of 14 amino acids, the SQ-link, in the C-terminal end of the 90 kDa chain. It was shown that r-VIII SQ had a high specific activity of about 14,000 IU VIII:C/mg as determined by use of a chromogenic substrate assay. The r-VIII SQ protein was comparable to p-VIII forms with a retained B-domain, in terms of potency measured by a chromogenic substrate or a two-stage clotting assay, in interactions with thrombin, and with activated protein C (APC) in combination with Protein S. The ability of r-VIII SQ to participate as a cofactor in factor Xa generation in a mixture of factors IXa and X, phospholipid and calcium was in conformity with that of p-VIII. Furthermore r-VIII SQ had a good binding capacity for phospholipid vesicles and von Willebrand factor (vWF) as shown in gel filtration studies. The same kinetics in binding to von Willebrand factor was found for r-VIII SQ and p-VIII as determined by real-time biospecific interaction analysis (BIA) with use of the BIAcore instrument. The apparent association rate constant was 4 x 10(6) M(-1)s(-1). Two dissociation rate constants were found, 1 X 10(-2)s(-1) and 4 x 10(-4)s(-1). The results extend the present knowledge that the factor VIII B-domain is dispensable for the factor VIII cofactor function in hemostasis.

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.

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.

[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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

The course of differently treated isolated ruptures of the anterior cruciate ligament as observed by prospective stress radiography

In a prospective stress radiographic study of the course of 21 isolated anterior cruciate ligament (ACL) injuries, primary suture was performed in eight patients and reconstruction due to chronic instability was performed in six patients. Seven patients were treated by exploratory arthrotomy only. After a follow-up period of seven years the anterior drawer sign had disappeared in five of the 14 patients who had shown this sign prior to operation, but in some of these patients progressive rotatory instabilities developed, so that the total abnormal instability did not improve in any of the three therapeutic groups. Only ten patients obtained a completely symptom-free knee. A well performed Jones procedure could reduce a chronic anterior drawer instability, but in several of the patients troublesome patellofemoral pain developed later. Acute suture of isolated anterior cruciate ligament injuries afforded the best results in this series and is recommended.

Prospective stress radiography in 38 old injuries of the ligaments of the knee joint

In a prospective clinical and stress radiographic study comprising 38 patients, the course of chronic ligament injuries in the knee joint was evaluated. All but five patients had isolated ligament injuries, 16 of which affected the anterior cruciate ligament. The operations were performed from 18 days to 20 years after the injury had occurred. In 13 patients primary suture could be carried out, 12 patients underwent exploratory arthrotomy, and the remainder had relevant ligament repair. After a follow-up period of 7 years the instability had been cured in all patients with medial laxity and in one of two patients with lateral laxity. Nineteen patients had a drawer sign preoperatively. The anterior drawer sign disappeared in practically all patients, while a posterior drawer sign was a constant sequel to injury affecting the posterior cruciate ligament. It was difficult to prevent the development of rotatory instability--which was present in six preoperatively and in 14 at follow-up--and the rotatory instabilities were predominantly marked (greater than 6 mm). Nevertheless, only a few patients had an annoying sensation of instability. By means of ligament reconstruction, it was possible to reduce the preoperative instability appreciably. Passive instability had completely subsided in 40 per cent (15/38). The subjective result was good, only 16 per cent (6/38) having troublesome loss of function.

Isolation and characterization of lipid-protein particles containing platelet factor 3 released from human platelets

Lipid-protein particles with platelet factor 3 measured by the Stypven clotting-time test [Hardisty & Hutton (1966) Br. J. Haematol. 12, 764-776] have been isolated from platelet-release supernatant. Starting material was washed platelets, which were released by treatment with collagen. Purification of the particles from other components in the release material was accomplished by gel filtration on Sepharose CL-4B followed by affinity chromatography on poly-L-lysine-Sepharose CL-4B gel. Chemical characterization showed that the particles were composed of 40% protein, 42% phospholipids, 13% cholesterol and 5% triacylglycerols. The phospholipid composition was 38% phosphatidylcholine, 25% phosphatidylethanolamine, 9% phosphatidylserine, 2% phosphatidic acid and 26% sphingomyelin. No carbohydrate was detected. Electron-microscopic studies revealed the presence of membranous particles with diameters between 70 and 170 nm.

Prospective stress radiographic study of knee ligament injuries in 62 patients treated by acute repair

A prospective clinical and stress radiographic study comprising 62 patients was performed to assess the value of acute repair of 35 isolated collateral ligament injuries and 27 major injuries. After a follow-up period of 6 years there was no lateral or medical instability in 42 out of 46 patients. This included 31 out of 33 patients in the group with medial collateral ligament injuries. Among the patients with major injuries 16 (60 per cent) had drawer signs, but in only 6 was there significant instability (greater than 6 mm). In the total material it proved difficult to prevent the development of rotatory instability. This was present in 10 patients preoperatively and in 19 at follow-up. However, this instability was on the whole slight and was experienced as annoying by only 4 patients. Measurement of passive instability showed that 55 per cent (34/62) had become completely stable, but this applied to only 30 per cent (8/27) of patients with major injuries. The functional end result was unsatisfactory in 8 patients (13 per cent). Although several patients could compensate muscularly for a marked passive instability, there was a significant correlation between instability and functional loss.

Levels of platelet factor 3 in citrate plasma and in whole blood as determined by a chromogenic peptide substrate assay

A newly developed sensitive method for determination of platelet factor 3 (PF 3) using a chromogenic substrate (S 2238) (Sandberg and Andersson, Thromb. Res., in press) was used for comparison of the PF 3 levels in platelet-rich plasma (PRP) in citrate with the levels in PRP in the anticoagulant EDTA/citrate/PGE 1/theophylline. It was shown that in citrate PRP, release of PF 3 was started after about 20 minutes from blood sampling. Release of β-thromboglobulin (β-tg) was found to occur simultaneously with the release of PF 3. No release of PF 3 or β-tg could be detected within 3 hours from blood sampling in PRP in the EDTA/citrate/PGE 1/theophylline anticoagulant.

The PF 3 level in whole blood was measured by a method which was a modification of the method used for plasma samples. It was found that, using the same donor, the PF 3 level of plasma and blood in the EDTA/citrate/PGE 1/theophylline anticoagulant was essentially the same. The levels of PF 3 found in blood upon standing in citrate or in EDTA/citrate/PGE 1/theophylline anticoagulant were in accordance with the levels found in plasma. Experiments with whole blood without any anticoagulant showed that release of PF 3 begin to occur simultaneously with release of β-tg, about 5 minutes before clotting. Thus the data show that PF 3 and β-tg are released in parallel.

Activation of Factor VIII by Thrombin as Measured by Competition Kinetics

It is known that the procoagulant activity of purified Factor VIII is strongly increased when incubated with concentrations of thrombin below 0.1 unit/ml. It has been assumed that this also is a mechanism of physiological importance thus that activation of Factor VIII by low concentrations of thrombin is one step in normal blood coagulation. The rate constant tor the reaction between Factor VIII and thrombin was estimated by two different methods. In one method formation of “activated” Factor VIII in a system containing thrombin, purified Factor VIII and albumin added as stabilizer was measured. In the other method the competition of purified Factor VIII as substrate for thrombin was compared with fibrinogen and a chromogenic peptide substrate. As expected it was found that thrombin had higher affinity for Factor VIII than for fibrinogen. The values calculated for the second order rate constant, using 240,000 as the molecular weight of the reactive unit in Factor VIII, were similar for the various systems, around 106s-1M-1.

Levels of Platelet Factor 3 in Citrate Plasma and in Whole Blood as Determined by A Chromogenic Peptide Substrate Assay

A newly developed sensitive method for determination of platelet factor 3 (PF 3) using a chromogenic substrate (S 2238) (Sandberg and Andersson, Thromb. Res., in press) was used for comparison of the PF 3 levels in platelet-rich plasma (PRP) in citrate with the levels in PRP in the anticoagulant EDTA/citrate/PCE 1/theophylline. It was shown that in citrate PRP, release of PF 3 was started after about 20 minutes from blood sampling. Release of β-thromboglobulin (β-tg) was found to occur simultaneously with the release of PF 3. No release of PF 3 or β-tg could be detected within 3 hours from blood sampling in PRP in the EDTA/citrate/PCE 1/theophylline anticoagulant.

The PF 3 level in whole blood was measured by a method which was a modification of the method used for plasma samples. It was found that, using the same donor, the PF 3 level of plasma and blood in the EDTA/citrate/PCE 1/theophylline anticoagulant was essentially the same. The levels of PF 3 found in blood upon standing in citrate or in EDTA/citrate/PCE 1/theophy11ine anticoagulant were in accordance with the levels found in plasma. Experiments with whole blood without any anticoagulant showed that release of PF 3 begin to occur simultaneously with release of β-tg, about 5 minutes before clotting. Thus the data show that PF 3 and βtg are released in parallel.

Studies of the thromboplastic effect of human plasma lipoproteins

Human plasma lipoprotein fractions were prepared by flotation in the ultracentrifuge. Addition of these fractions to platelet-rich, platelet-poor and platelet-free plasma affected the partial thromboplastin and Stypven clotting times to various degrees. Addtion of high density lipoprotein (HDL) to platelet-poor and platelet-free plasma shortened both the partial thromboplastin and the Stypven time, whereas addition of low density lipoprotein and very low density lipoprotein (LDL + VLDL) fractions only shortened the Stypven time. The additions had little or no effect in platelet-rich plasma. Experiments involving the addition of anti-HDL antibodies to plasmas with different platelet contents and measuring of clotting times produced results that were in good agreement with those noted when lipoprotein was added. The relation between structure and the clot-promoting activity of various phospholipid components is discussed.