Exploring clinically relevant risk profiles in patients undergoing lumbar spinal fusion: a cohort study.

PURPOSE: To explore risk profiles of patients scheduled for lumbar spinal fusion (LSF) and their association with short-term recovery of patient after surgery. METHODS: Forty-nine patients scheduled for elective 1-3 level LSF between March 2019 and June 2020 were included. Patients underwent a preoperative risk screening, consisting of an anamnesis, questionnaires and physical performance tests. A latent profile analysis (LPA) was used to identify possible risk profiles within this population. RESULTS: Two risk profiles could be established: a fit and deconditioned risk profile. A significant between-profile difference was found in smoking status (p = 0.007), RAND36-PCS (p < 0.001), Timed Up and Go (TUG) (p < 0.001), de Morton Morbidity Index (DEMMI) (p < 0.001), finger floor distance (p = 0.050), motor control (p = 0.020) and steep ramp test (p = 0.005). Moreover, the fit risk profile had a significant shorter time to functional recovery (3.65 days versus 4.89 days, p = 0.013) and length of hospital stay (5.06 days versus 6.00 days, p = 0.008) compared to the deconditioned risk profile. No differences in complication rates between both risk profiles could be established. Allocation to a risk profile was associated with the functional recovery rate (p = 0.042), but not with LOS or complications. CONCLUSION: This study found a fit and deconditioned risk profile. The patients with a fit risk profile perceived a better quality of life, performed better in mobility, motor control, cardiopulmonary tests and showed also a significant shorter stay in the hospital and a shorter time to functional recovery. Preoperatively establishing a patient's risk profile could aid in perioperative care planning and preoperative decision-making.

Intra- and inter-observer reliability of Cobb angle measurements in patients with adolescent idiopathic scoliosis.

PURPOSE: The Cobb angle method is used to determine the severity of scoliosis. Therapeutic decisions for adolescent idiopathic scoliosis (AIS) are guided by the Cobb angle. Therefore, high reliability is crucial. The objective of this study was to determine the intra- and inter-observer reliability of the digital Cobb angle measurements and the definition of end vertebrae in patients with AIS. Moreover, the influence of the observer's medical specialty and experience on Cobb angle measurement was evaluated. METHODS: Intra- and inter-observer reliability of the digital Cobb angle and end vertebrae is assessed in postero-anterior radiographs of 39 patients with AIS. Measurements were performed blinded and twice by six observers, with a two to 3 week interval. Intra- and inter-observer reliability was analysed by means of intraclass correlation coefficients (ICC). RESULTS: Both intra- and inter-observer reliability analyses resulted in ICC's higher than 0.864 for the Cobb angle and definition of end vertebrae. In addition, for the observer's experience and medical specialty group the inter-observer ICC's were higher than 0.984. The average inter-observer variability for the Cobb angle were 3°, and 1.1-1.6 levels for the cranial and caudal end vertebrae selection. The variability in measured Cobb angle was 1° for the experience group and 2° for the medical specialty group. Cronbach's alpha varied from 0.990 to 0.996. Bland-Altman plots showed moderate variation with a few outliers. CONCLUSIONS: The digital Cobb angle measurement as well as the definition of end vertebrae show excellent reliability. According to our results, medical specialty and experience do not affect Cobb angle measurements and definition of end vertebrae.

Activation of protein kinase C enhances the infection of endothelial cells by human cytomegalovirus.

The infection of cultured endothelial cells with human cytomegalovirus (HCMV) is generally limited to less than 10% of the cells in contrast to HCMV infection of fibroblasts, where essentially all cells can be infected. It is known that HCMV infection influences a number of signal transduction pathways of infected cells. We therefore questioned whether, conversely, the infectivity of human umbilical vein endothelial cells could be influenced by the deliberate activation of these pathways. When endothelial cells were treated prior to infection with phorbol myristoyl acetate, an activator of protein kinase C, the number of HCMV-positive cells increased two to three times. On the other hand, pretreatment of the cells with RO 31-8220, a specific protein kinase C inhibitor, or with staurosporine, a general protein kinase inhibitor, resulted in a decreased infection level and in abolishment of the PMA-induced effect. Pretreatment with the protein phosphatase inhibitor, okadaic acid, caused a slight increase in infectivity, whereas pretreatment with the protein tyrosine kinase inhibitor, genistein, was without effect. Furthermore, neither forskolin and ilomedine, compounds known to activate the endothelial adenylate cyclase, nor the calcium ionophore A23187 were able to influence HCMV infectivity. It is concluded that: (a) the HCMV infection level of unstimulated endothelial cells is influenced by the basal level of protein kinase C; and (b) stimulation of protein kinase C prior to infection results in an increase of infection by HCMV.

Effects of positive and negative exercise on ventilatory CO2 sensitivity.

Investigations in our laboratory have shown an increased slope of the ventilatory response curve to CO2 (CO2 sensitivity) during positive and negative exercise as compared with the resting condition. CO2 sensitivity during positive and negative exercise did not differ in spite of differences in metabolism (VO2, VCO2) and type of muscle contraction (concentric or eccentric). Various aspects of positive and negative exercise were examined in order to find out whether they can explain the identical CO2 sensitivity. Cardiac output, oxygen consumption, rectal temperature and venous catecholamine concentration appeared to be higher in positive exercise than in negative exercise, and higher in negative exercise than at rest. However, these differences between the two types of exercise contrast with the identical CO2 sensitivity and thus cannot be of major importance in determining CO2 sensitivity. It is hypothesized that one or more of these variables might be responsible for increased CO2 sensitivity during exercise as compared with rest. The CO2 sensitivity, once increased, seems to be unaffected by further increases in these variables.

Three successive steady-state CO2-response curves. No change of sensitivity of the ventilatory controlling system for CO2.

Three successive steady-state CO2-response curves, with 10-minute intervals, were taken in seven healthy subjects at rest in normoxia. No systematic difference in the slopes between the three curves could be found. The results suggest that a previous steady-state CO2-response curve does not change the sensitivity of the ventilatory controlling system for CO2.