Fredrik Huss

Assessment of incidence of severe sepsis in Sweden using different ways of abstracting International Classification of Diseases codes: difficulties with methods and interpretation of results.

Objective:To compare three International Classification of Diseases code abstraction strategies that have previously been reported to mirror severe sepsis by examining retrospective Swedish national data from 1987 to 2005 inclusive. Design:Retrospective cohort study. Setting:Swedish hospital discharge database. Patients:All hospital admissions during the period 1987 to 2005 were extracted and these patients were screened for severe sepsis using the three International Classification of Diseases code abstraction strategies, which were adapted for the Swedish version of the International Classification of Diseases. Two code abstraction strategies included both International Classification of Diseases, Ninth Revision and International Classification of Diseases, Tenth Revision codes, whereas one included International Classification of Diseases, Tenth Revision codes alone. Interventions:None. Measurements and Main Results:The three International Classification of Diseases code abstraction strategies identified 37,990, 27,655, and 12,512 patients, respectively, with severe sepsis. The incidence increased over the years, reaching 0.35 per 1000, 0.43 per 1000, and 0.13 per 1000 inhabitants, respectively. During the International Classification of Diseases, Ninth Revision period, we found 17,096 unique patients and of these, only 2789 patients (16%) met two of the code abstraction strategy lists and 14,307 (84%) met one list. The International Classification of Diseases, Tenth Revision period included 46,979 unique patients, of whom 8% met the criteria of all three International Classification of Diseases code abstraction strategies, 7% met two, and 84% met one only. Conclusions:The three different International Classification of Diseases code abstraction strategies generated three almost separate cohorts of patients with severe sepsis. Thus, the International Classification of Diseases code abstraction strategies for recording severe sepsis in use today provides an unsatisfactory way of estimating the true incidence of severe sepsis. Further studies relating International Classification of Diseases code abstraction strategies to the American College of Chest Physicians/Society of Critical Care Medicine scores are needed.

Mammary Epithelial Cell and Adipocyte Co-Culture in a 3-D Matrix: The First Step towards Tissue-Engineered Human Breast Tissue

Reconstruction of the female breast after cancer surgery is a demanding task where the methods used today suffer from several disadvantages. In the present study we have investigated the possibility to use tissue engineering methods to regenerate human autologous breast tissue. Human mammary epithelial cells and preadipocytes were derived from breast tissue biopsies from healthy women undergoing reduction mammoplasty, and the two celltypes were co-cultured with conventional cell culture methods as well as in 3-D matrices. The study shows that it is possible to harvest both human mammary epithelial cells and preadipocytes in a single session, propagate several subcultures, and that the cells maintain a normal intercellular distribution and growth-pattern when co-cultured in a 3-D collagen gel. We propose that growth and formation of a tissue closely resembling normal human breast tissue be readily obtained in the described in vitro cell culture set-up using basic tissue engineering principles. This concept may be of great importance in the development of new methods for reconstruction of the human breast.

Adipose tissue processed for lipoinjection shows increased cellular survival in vitro when tissue engineering principles are applied.

Correcting soft tissue defects by autologous fat grafting is a routine procedure in plastic surgery. Its efficacy and safety has been discussed extensively and several techniques of lipoinjection have been developed. However, one is bound to overcorrect by 30%-70% or need to repeat the procedure because of resorption of the transplant. The reasons are that many of the transplanted cells are already differentiated, and also that there is no nutritional support to the inner cell layers when they are transplanted as fragments. By culturing autologous adipocytes one can ensure that only non-differentiated, but committed, preadipocytes are transplanted and the procedure can be done in a way that ensures optimal nutritional support for the cells. In the present study we have compared our cell culture technique with two common clinical ways of processing liposuction material and found that (pre)adipocytes survive and proliferate significantly better in cell culture.

Psychometric properties of the impact of event scale-revised in patients one year after burn injury

Burn injury can be a life-threatening and traumatic event. Despite considerable risk for psychological morbidity, few outcome measures have been evaluated. The aim of this study was to examine the psychometric properties of a Swedish version of the Impact of Event Scale-Revised (IES-R) in patients 1 year after burn injury (N = 147). A principal component analysis was performed, and the results supported the three-factor structure of the IES-R. High internal consistency and intelligible associations with concurrent psychological symptoms and known risk factors for distress after trauma indicate satisfactory psychometric properties. Thus, the study supports the use of the IES-R as a screening tool for measuring traumatic distress after burn.

Use of macroporous gelatine spheres as a biodegradable scaffold for guided tissue regeneration of healthy dermis in humans: An in vivo study

If a biodegradable scaffold is applied, the dermis can be regenerated by guided tissue regeneration. Scaffolds can stimulate in-growth of cells from the surroundings that migrate into them and start to produce autologous extracellular matrix as the scaffold is degraded. Several materials are available, but most of them are in the form of sheets and need to be laid on an open wound surface. A number of injectable fillers have been developed to correct soft-tissue defects. However, none of these has been used for guided tissue regeneration. We present a new technique that could possibly be used to correct dermal defects by using macroporous gelatine spheres as a biodegradable scaffold for guided tissue regeneration. In eight healthy volunteers, intradermal injections of macroporous gelatine spheres were compared with injections of saline and hyaluronic acid (Restylane). Full-thickness skin biopsy specimens of the implants and surrounding tissue were removed 2, 8, 12 and 26 weeks after injection, and the (immuno)histological results were analysed. The Restylane merely occupied space. It shattered the dermal tissue and compressed collagen fibres and cells at the interface between the implant and the dermis. No regeneration of tissue was found with this material at any time. The macroporous gelatine spheres were populated with fibroblasts already after 2 weeks. After 8 weeks the spheres were completely populated by fibroblasts producing dermal tissue. After 12 and 26 weeks, the gelatine spheres had been more or less completely resorbed and replaced by vascularised neodermis. There were no signs of capsular formation, rejection or adverse events in any subject. Further in vivo studies in humans are needed to evaluate the effect of the macroporous spheres fully as a matrix for guided tissue regeneration with and without cellular pre-seeding. However, the results of this study indicate the possibility of using macroporous gelatine spheres as an injectable, three-dimensional, degradable matrix for guided tissue regeneration.

Hyaluronic acid, an important factor in the wound healing properties of amniotic fluid : In vitro studies of re-epithelialisation in human skin wounds

Abstract Foetal wounds are unique in their ability to heal rapidly without forming scars. The amniotic fluid, rich in nutrients, growth factors, and hyaluronic acid, surrounds the foetus and is essential to foetal wound healing. The wound healing properties of foetal wounds may be the result of high concentrations of hyaluronic acid. This study aimed to verify that amniotic fluid induces re-epithelialisation in human skin wounds in vitro and to study whether this ability is dependent on hyaluronic acid. Standard deep dermal wounds were produced in vitro in human skin. The skin samples, with a central wound, were incubated in different culture media. Varying concentrations of amniotic fluid and amniotic fluid with added hyaluronidase were tested, and re-epithelialisation was assessed at 3, 7, and 12 days using light microscopy, after staining with haematoxylin and eosin. Amniotic fluid 50% resulted in a significantly higher (p < 0.05) grade of re-epithelialisation than Dulbeccos modified Eagles medium and 10% amniotic fluid at all time points. When 50% amniotic fluid was compared with 10% foetal calf serum, no significant difference was found in grades of re-epithelialisation on days 3 and 12 and significantly higher grades of re-epithelialisation on day 7 (p < 0.05). Degradation of hyaluronic acid in the medium that contained 50% amniotic fluid gave significantly impaired re-epithelialisation (p < 0.05) on culture days 3 and 7. In conclusion, amniotic fluid promotes accelerated re-epithelialisation and hyaluronic acid is an important ingredient.

Characterization of a new degradable polymer scaffold for regeneration of the dermis : In vitro and in vivo human studies.

Full thickness skin wounds in humans heal with scars, but without regeneration of the dermis. A degradable poly(urethane urea) scaffold (PUUR), Artelon® is already used to reinforce soft tissues in orthopaedics, and for treatment of osteoarthritis of the hand, wrist, and foot. In this paper we have done in vitro experiments followed by in vivo studies to find out whether the PUUR is biocompatible and usable as a template for dermal regeneration. Human dermal fibroblasts were cultured on discs of PUUR, with different macrostructures (fibrous and porous). They adhered to and migrated into the scaffolds, and produced collagen. The porous scaffold was judged more suitable for clinical applications and 4 mm Ø, 2 mm-thick discs of porous scaffold (12% w/w or 9% w/w polymer solution) were inserted intradermally in four healthy human volunteers. The implants were well tolerated and increasing ingrowth of fibroblasts was seen over time in all subjects. The fibroblasts stained immunohistochemically for procollagen and von Willebrand factor, indicating neocollagenesis and angiogenesis within the scaffolds. The PUUR scaffold may be a suitable material to use as a template for dermal regeneration.

Matrix Metalloproteinases -8 and -9 and Tissue Inhibitor of Metalloproteinase-1 in Burn Patients. A Prospective Observational Study

Introduction Matrix metalloproteinases (MMPs) -8 and -9 are released from neutrophils in acute inflammation and may contribute to permeability changes in burn injury. In retrospective studies on sepsis, levels of MMP-8, MMP-9, and tissue inhibitor of metalloproteinase-1 (TIMP-1) differed from those of healthy controls, and TIMP-1 showed an association with outcome. Our objective was to investigate the relationship between these proteins and disease severity and outcome in burn patients. Methods In this prospective, observational, two-center study, we collected plasma samples from admission to day 21 post-burn, and burn blister fluid samples on admission. We compared MMP-8, -9, and TIMP-1 levels between TBSA<20% (N = 19) and TBSA>20% (N = 30) injured patients and healthy controls, and between 90-day survivors and non-survivors. MMP-8, -9, and TIMP-1 levels at 24-48 hours from injury, their maximal levels, and their time-adjusted means were compared between groups. Correlations with clinical parameters and the extent of burn were analyzed. MMP-8, -9, and TIMP-1 levels in burn blister fluids were also studied. Results Plasma MMP-8 and -9 were higher in patients than in healthy controls (P<0.001 and P = 0.016), but only MMP-8 differed between the TBSA<20% and TBSA>20% groups. MMP-8 and -9 were not associated with clinical severity or outcome measures. TIMP-1 differed significantly between patients and controls (P<0.001) and between TBSA<20% and TBSA>20% groups (P<0.002). TIMP-1 was associated with 90-day mortality and correlated with the extent of injury and clinical measures of disease severity. TIMP-1 may serve as a new biomarker in outcome prognostication of burn patients.

Accelerated wound healing in mice by on-site production and delivery of CXCL12 by transformed lactic acid bacteria

Significance Chronic wounds comprise a growing clinical problem that represents >3% of the health care budget in industrialized countries. Drug development is hampered by the proteolytic nature of the wounds, which greatly limits drug bioavailability. Here, we present a technology that circumvents this by on-site production and reduced chemokine degradation. Lactobacilli bacteria were transformed into CXCL12-producing vectors to bioengineer the wound microenvironment after topical application. Consequently, the immune cells driving the healing process were reinforced, which greatly accelerated wound closure in healthy mice, in mouse models of hyperglycemia and peripheral ischemia, and in a wound model using human skin disks. Initial safety studies demonstrated that neither bacteria nor the chemokine produced was detected in systemic circulation following application to open wounds. Impaired wound closure is a growing medical problem associated with metabolic diseases and aging. Immune cells play important roles in wound healing by following instructions from the microenvironment. Here, we developed a technology to bioengineer the wound microenvironment and enhance healing abilities of the immune cells. This resulted in strongly accelerated wound healing and was achieved by transforming Lactobacilli with a plasmid encoding CXCL12. CXCL12-delivering bacteria administrated topically to wounds in mice efficiently enhanced wound closure by increasing proliferation of dermal cells and macrophages, and led to increased TGF-β expression in macrophages. Bacteria-produced lactic acid reduced the local pH, which inhibited the peptidase CD26 and consequently enhanced the availability of bioactive CXCL12. Importantly, treatment with CXCL12-delivering Lactobacilli also improved wound closure in mice with hyperglycemia or peripheral ischemia, conditions associated with chronic wounds, and in a human skin wound model. Further, initial safety studies demonstrated that the topically applied transformed bacteria exerted effects restricted to the wound, as neither bacteria nor the chemokine produced could be detected in systemic circulation. Development of drugs accelerating wound healing is limited by the proteolytic nature of wounds. Our technology overcomes this by on-site chemokine production and reduced degradation, which together ensure prolonged chemokine bioavailability that instructed local immune cells and enhanced wound healing.

Simulation-assisted burn disaster planning

The aim of the study was to evaluate the Swedish medical systems response to a mass casualty burn incident in a rural area with a focus on national coordination of burn care. Data were collected from two simulations of a mass casualty incident with burns in a rural area in the mid portion of Sweden close to the Norwegian border, based on a large inventory of emergency resources available in this area as well as regional hospitals, university hospitals and burn centres in Sweden and abroad. The simulation system Emergo Train System(®) (ETS) was used and risk for preventable death and complications were used as outcome measures: simulation I, 18.5% (n=13) preventable deaths and 15.5% (n=11) preventable complications; simulation II, 11.4% (n=8) preventable deaths and 11.4% (n=8) preventable complications. The last T1 patient was evacuated after 7h in simulation I, compared with 5h in simulation II. Better national coordination of burn care and more timely distribution based on the experience from the first simulation, and possibly a learning effect, led to a better patient outcome in simulation II. The experience using a system that combines both process and outcome indicators can create important results that may support disaster planning.