Enhanced HIV infectivity and changes in GP120 conformation associated with viral incorporation of human leucocyte antigen class I molecules.

BACKGROUND: Assembly of human immunodeficiency virus type 1 (HIV-1) occurs at the level of the plasma membrane of the host cell. During this process HIV incorporates significant quantities of cell surface-derived molecules into its lipid bilayer including human leucocyte antigen (HLA) class I and II, intercellular adhesion molecule-1 and lymphocyte function antigen-1. Several studies indicate that virion-bound host-cell-derived molecules are functional and affect the biological properties of HIV-1. Virion-associated HLA class II and intercellular adhesion molecule-1 enhance the infectivity of T-cell line-adapted (TCLA) viruses. No role for virion-associated HLA class I molecules has yet been identified. OBJECTIVE: To investigate the role of HLA class I molecules in HIV replication and infectivity. METHODS: HLA class I negative human cells lines transfected with the HLA Cw4 gene were infected with different TCLA viruses as well as primary X4 isolates. The infectivity of HLA Cw4 positive and negative viruses was determined on indicator cell lines and on phytohaemagglutinin-activated peripheral blood mononuclear cells. An entry polymerase chain reaction assay was used to determine differences in entry-competence of Cw4 positive and negative viruses. The expression of selected gp120 epitopes on native Env molecules derived from Cw4 positive and negative viruses was determined by a monoclonal antibody-based enzyme-linked immunosorbent assay. Immunoprecipitation experiments were performed to investigate the presence of gp120/HLA Cw4 complexes. Neutralization assays determined the differences in susceptibility to neutralization between HLA Cw4 negative and positive viruses. RESULTS AND CONCLUSIONS: The infectivity of primary HIV-1 X4 isolates and of TCLA viruses is increased upon viral incorporation of HLA Cw4 molecules. This effect is associated with changes in viral envelope proteins conformation including an enhanced expression of the V3 loop of gp120, and of epitopes that are exposed upon CD4 binding. The gp120 conformational changes are consistent with the formation of a multimolecular complex between HLA class I and gp120/160. HLA Cw4 incorporation is also associated to a lower susceptibility to antibody neutralization. These findings have important implications for understanding the immune response to cryptic and conformational epitopes of the viral envelope.     

Influence of extracellular osmolarity and mechanical stimulation on gene expression of intervertebral disc cells.

Intervertebral discs (IVD) have a higher extracellular osmolarity than most other tissues; moreover their osmolarity changes by around 25% during each diurnal cycle. In this study, changes in aggrecan, collagen I and collagen II expression of IVD cells were examined after exposure to osmotic environment alterations or mechanical stimulation under different osmotic conditions. Human and bovine IVD cells seeded in three-dimensional (3D) collagen type I matrices were cultured under hypo-osmotic (300 mOsm), iso-osmotic (400 mOsm), or hyperosmotic (500 mOsm) conditions. Osmolarity-induced changes in gene expression of IVD cells were measured after 5 days. Load-induced changes in gene expression under the different osmotic conditions were measured after application of hydrostatic pressure (0.25 MPa, 0.1 Hz, 30 min) or cyclic strain (4%, 1 Hz, 24 h). The results showed that IVD cells respond strongly to changes in the osmotic environment by altering mRNA expression. Human cells cultured over 5 days increased expression of aggrecan and collagen II in both nucleus and annulus cells under increasing osmolarity. In contrast, collagen I expression was inhibited at high osmolarity in both cell types. Mechanically induced alterations in gene expression appear to have only modest effects on matrix protein expression, but the same stimulus partly resulted in an inhibition or stimulation of gene expression, depending on the osmotic conditions. This study showed that the osmotic environment does not only have an appreciable effect on gene expression but also affects responses to mechanical stimuli. This suggests that the osmotic conditions cannot be ignored when examining physiological and pathological behavior of IVD cells.     

Trends in sports injuries, 1982-1988: an in-depth study on four types of sport.

In this study, we analyzed the records of both inpatients and outpatients which were treated for acute sports injuries in the Trauma Department of the University of Groningen (The Netherlands) during the years 1982 to 1988. We examined whether there was a trend in sports injuries in this time period. The study comprised four types of sports, i.e., soccer, volleyball, gymnastics, and martial arts. The absolutely highest rates of injuries across the seven years were found in soccer, followed by gymnastics, volleyball, and martial arts. Injuries sustained at participating in soccer, volleyball, and gymnastics involved for the major part the lower extremities, followed by injuries of the upper extremities, whereas the reverse pattern was observed for patients who participated in martial arts. For all four types of sport, the ankle and foot were the most frequently site of injury of the lower extremities. Sprains and strains were the major types of injury. Most injuries were seen at ages between 10 and 30 years. The ratio of male to female patients within age groups did not differ significantly across the seven years. We concluded that, except for martial arts, the increased participation in sports in the last decade was not accompanied with a change in the patterns of sports injuries by the patients' age, sex, and number and nature of the injury. This consistency in results can be used to guide the development of prevention programs aimed at a reduction of injuries in specific sports.     

Colonization of burns and the duration of hospital stay of severely burned patients.

In a retrospective study the influence of several factors on the length of hospital stay of severely burned patients (at least 24% total body surface area) has been investigated. The influence of these factors was studied by means of the Cox model survival analysis with time-varying covariates. Seventy-one patients were included in this study. The mean age was 32 years (range 1-82 years), the mean total body surface area burned 40% (range 24-80%) and the mean full-thickness area burned 32% (range 10-70%). The length of hospital stay was positively correlated with the extent of the burned area and with the age of the patient. Wound colonization with Enterobacteriaceae or with a combination of Pseudomonas spp. and Staphylococcus aureus was also associated with a prolonged stay in hospital.     

Fractures of the intercondylar eminence in children and adolescents

The treatment of choice of completely dislocated fractures of the intercondylar eminence is controversial. Recently, Zifko and Gaudernak [14] introduced a new classification in which they distinguish between two different types of intercondylar fractures: Type A: isolated avulsion of the anterior cruciate ligament Type B: fractures including the intercondylar eminence In order to assess whether this new classification could lead to a better selection of patients requiring open reduction, 19 children were reviewed 2-16 years after they had sustained a fracture of the intercondylar eminence. All patients with incompletely displaced fragments had an excellent or good ultimate result, independent of the kind of initial treatment received. Eleven patients sustained a complete displaced fracture. Of these, two had a poor result. Both had been treated conservatively for isolated avulsion of the anterior cruciate ligament. All conservatively treated type-B fractures had an excellent or good result. It is concluded that completely displaced type-A fractures require operative treatment by open reduction and fixation of the avulsed fragment.     

Effects of avian viruses on cultured chicken bone-marrow-derived macrophages

Cultured chicken bone-marrow-derived macrophages have been assayed for their susceptibility to infection with various avian viruses. Three criteria of infection were employed: (1) Virus-induced alterations in cell morphology ; (2) presence of intracellular viral antigens detectable by immunofluorescence; (3) kinetics of virus release by infected macrophages. Macrophages proved to be resistant to Marek's disease virus (MDV), herpesvirus of turkeys (HVT-FC126), infectious bronchitis virus (IBV) and reticuloendotheliosis virus (REV). MDV included the pathogenic HPRS-16 strain prepared from feather follicles, and the apathogenic HPRS-24 strain adapted to growth in chick embryo fibroblast cultures. IBV included both embryo-propagated and tissue culture-adapted variants of the apathogenic Beaudette strain and a pathogenic Massachusetts-type strain. REV comprised the strains REV-C, CSV and oncogenic virus of the REV-F strain. Adenovirus, infectious laryngotracheitis (ILT) virus, reovirus, infectious bursal disease virus (IBDV) and Newcastle disease virus (NDV) replicated in macrophages causing different but characteristic cytopathic effects, or alterations in cell morphology associated with macrophage activation. The most prominent effect of IBDV and lentogenic NDV infection were morphological signs of macrophage activation, i.e. enlargement or 'transformation' of cells which tended to survive in infected cultures and were usually free of detectable amounts of immunofluorescent viral antigens. Macrophage cultures were less susceptible to infection with adenovirus (OTE strain), pathogenic ILT virus and lentogenic NDV (B1 strain) than permissive chicken kidney cell (CKC) cultures. In contrast, macrophage cultures were significantly more susceptible to infection with reovirus than CKC cultures, indicating that bone-marrow-derived macrophages might be the major target cells of this virus species. Virus restriction by cultured bone-marrow-derived macrophages was expressed to various degrees among the different avian virus species and among different strains of the same virus species, however, it was not generally correlated with the pathogenicity of these viruses in chickens.     

German version of the Strength and Difficulties Questionnaire (SDQ-German)--overview and evaluation of initial validation and normative results

The Strengths and Difficulties Questionnaire (SDQ) is a short behavioural screening questionnaire which can be completed in about five minutes by parents and teachers of 4- to 16-year-olds or as self-report by 11- to 16-year-olds. The English original has already been fully evaluated and is widely used in research and clinical practice. The instrument was translated into German in 1997, and several evaluative studies have since been completed. The present paper gives an overview of this novel instrument and summarizes the normative and validation studies to date. A normative study on a field sample of 930 children demonstrated that the distributions of raw scores in the German parent SDQ closely resemble those found in the English version, while a factor analysis of the German data yielded a pattern of loadings which convincingly replicated the original scale structure. Initial validation studies showed that the parent-, teacher-, and self-completed SDQ-Deu correlates well with the considerably longer German versions of the Child Behavior Checklist (CBCL) and respective teacher and self-report derivatives (TRF, YSR). Both parent-rated instruments are equally able to distinguish between a community and a clinic sample, and between subgroups with and without specified categories of disorders within a clinic sample. After discussing possible uses of the SDQ-Deu as well as similarities and differences to other scales, we conclude that the German SDQ is just as useful and valid an instrument for many clinical and research purposes as the English original.     

Differing incidences of relevant hypotension with combined spinal-epidural anesthesia and spinal anesthesia

In this investigation we assessed whether patients receiving spinal anesthesia (SPA) as part of combined spinal-epidural anesthesia (CSE) more often experience relevant hypotension than patients receiving SPA alone. From January 1, 1997, until August 5, 2000, electronic anesthesia records from 1596 patients having received SPA and 1023 patients having received CSE for elective surgery were collected by using a computerized anesthesia record-keeping system. Relevant hypotension was defined as a decrease of mean arterial blood pressure of more than 30% within a 10-min interval and a therapeutic action of the attending anesthesiologist within 20 min after onset. Electronic patient charts were reviewed by using logistic regression with a forward stepwise algorithm to identify independent risk factors that were associated with an increased incidence of hypotension after CSE. Univariate analysis was performed to assess differences in biometric data and relevant risk factors for hypotension between the two procedures. The incidence of relevant hypotension was more frequent with CSE than with SPA alone (10.9% versus 5.0%; P < 0.001). In the multivariate analysis, arterial hypertension (odds ratio, 1.83; 95% confidence interval, 1.21-2.78) and sensory block height >T6 (odds ratio, 2.81; 95% confidence interval, 1.88-4.22) were found to be factors associated with hypotension in the CSE group. Compared with patients receiving SPA alone, patients undergoing CSE had a significantly more frequent prevalence of arterial hypertension and higher sensory block levels (P < 0.01) despite smaller amounts of local anesthetics. In this study, patients receiving CSE had an increased risk for relevant hypotension as compared with patients with SPA alone. Part of this effect seems to be due to the procedure alone and not only because this population is at higher risk. IMPLICATIONS: This study, based on a large number of patients with a retrospective design by using on-line recorded data, suggests that spinal anesthesia as part of combined spinal-epidural anesthesia may more often lead to relevant hypotension than spinal anesthesia alone. Preexisting arterial hypertension and a sensory block height exceeding T6 are major risk factors for the development of this complication.     

Ulnar-shortening osteotomy after fracture of the distal radius

Summary The ulnar impingement syndrome due to a relatively long ulna is one of the complications of a fracture of the distal radius. We performed ten ulnar-shortening osteotomies to restore distal radioulnar joint congruity. The mean relative ulna length was 4–5 mm. In-sufficient bone healing was encountered in four osteotomies. Replating and cancellous bone grafting was necessary in two cases because of nonunion. The functional outcomes were good in six, fair in two, and poor in two cases. Nonunion and poor functional outcome were related to a malunion of the radius with a volar radiocarpal angle of 20° or 25°. It appeared that incongruity of the distal radioulnar joint favored nonunion.     

Influence of S. aureus and Str. pyogenes wound colonization on bacterial translocation in a burn model

Summary Bacterial translocation (BT) and release of endotoxin from the gut may contribute to septic complications in severely burned patients. In earlier experiments, it was shown in a burn model that BT exceeded the role of wound dissemination when burn wounds were colonized with Pseudomonas aeruginosa. Burn wound colonization with Pseudomonas aeruginosa also enhanced BT. It was concluded that endotoxin from gram-negative micro-organisms colonizing the burn wound appeared to play a role in the increased BT. In this study, the contribution of burn wound colonization with the gram-positive micro-organisms S. aureus and Str. pyogenes to BT and endotoxemia has been examined in Escherichia coli monoassociated mice with a 30% scald. The animals were sacrificed two days post-burn. The peritoneal cavity, the heart, one lung, the liver, the spleen and the cecum were cultured. Endotoxin in plasma was determined by means of the Limulus amoebocyte lysate assay. It appeared that dissemination of E. coli from the gut played a more important role than S. aureus or Str. pyogenes dissemination from the burn wound in this model. In only one of the 15 surviving Str. pyogenes contaminated animals dissemination had taken place from the burn wound. Dissemination of S. aureus was not seen in the S. aureus contaminated group. The incidence of E. coli translocation two days postburn, to the spleen (p<0.05) and liver (p<0.01) was enhanced in the Str. pyogenes group compares to the control group. Wound colonization by S. aureus did not increase the incidence of E. coli translocation. Endotoxemia was found in three of the 15 Str. pyogenes and in none of the S. aureus contaminated animals. In one of the 15 control animals, endotoxin was detected in plasma. These differences are not significant. The cause of the enhanced BT to the spleen and the liver in the Str. pyogenes contaminated group remains as yet unclear.Abbreviations BT bacterial translocation - SPF specific pathogen free - CFU colony forming unit - GI gastrointestinal - BHI brain heart infusion - LPS Lipopolysaccharide