The effects of alginate composition on encapsulated betaTC3 cells

The effects of alginate composition on the growth of murine insulinoma betaTC3 cells encapsulated in alginate/poly-L-lysine/alginate (APA) beads, and on the overall metabolic and secretory characteristics of the encapsulated cell system, were investigated for four different types of alginate. Two of the alginates used had a high guluronic acid content (73% in guluronic acid residues) with varying molecular weight, while the other two had a high mannuronic acid content (68% in mannuronic acid residues) with varying molecular weight. Each composition was tested using two different polymer concentrations. Our data show that betaTC3 cells encapsulated in alginates with a high guluronic acid content experienced a transient hindrance in their metabolic and secretory activity because of growth inhibition. Conversely, betaTC3 cells encapsulated in alginates with a high mannuronic acid content experienced a rapid increase in metabolic and secretory activity as a result of rapid cell growth. Our data also demonstrate that an increase in either molecular weight or concentration of high mannuronic acid alginates did not alter the behavior of the encapsulated betaTC3 cells. Conversely, an increase in molecular weight and concentration of high guluronic acid alginates prolonged the hindrance of glucose metabolism, insulin secretion and cell growth. These observations can be best interpreted by changes in the microstructure of the alginate matrix, i.e., interaction between the contiguous guluronic acid residues and the Ca2+ ions, as a result of the different compositions.

Evaluation of soluble P-selectin as a marker for the diagnosis of deep venous thrombosis

OBJECTIVE

The combination of D-dimer and Wells score can exclude, but not confirm, the diagnosis of deep venous thrombosis (DVT). Since thrombosis and inflammation are interrelated, we evaluated the combination of soluble P-selectin (sPsel) with other inflammatory biomarkers for the diagnosis of DVT.

METHODS

Sixty-two positive and one hundred and sixteen patients with negative DVT, by duplex scan, were prospectively evaluated for sPsel, D-dimer, C-reactive protein (CRP), microparticles (MPs; total, leukocyte, and platelet-derived and tissue factor positive microparticles), and clinical Wells score.

RESULTS

Biomarkers and clinical scores that differentiated DVT positives from negatives were sPsel (87.3 vs 53.4 ng/mL, P < .0001), D-dimer (5.8 vs 2.1 mg/ L, P < .0001), CRP (2.1 vs 0.8 μg/mL, P < .0005), and Wells score (3.2 vs 2.0, P < .0001). For MP analysis, platelet-derived MPs were found to differentiate DVT from negatives. Using multivariable logistic regression, a combination of sPsel and Wells score could establish the diagnosis of DVT (cut point ≥ 90 ng/mL + Wells ≥ 2), with a specificity of 96% and positive predictive value (PPV) of 100%, and could exclude DVT diagnosis (cut point ≤ 60 ng/mL and Wells <2) with a sensitivity of 99%, a specificity of 33%, and a negative predictive value (NPV) of 96%.

CONCLUSION

This study establishes a biomarker and clinical profile combination that can both confirm and exclude the diagnosis of DVT.

Soluble P-selectin for the diagnosis of lower extremity deep venous thrombosis

OBJECTIVE

Although duplex ultrasound is the standard for the diagnosis of lower extremity deep venous thrombosis (LE-DVT), imaging is not always available. The use of D-dimer can exclude (high-sensitivity), but not rule in (low-specificity) LE-DVT. Previously, we demonstrated that soluble P-selectin (sP-sel) in combination with the Wells score, establishes the diagnosis of LE-DVT with a specificity of 96% and a positive predictive value of 100%. In order to validate our previous results, we applied the model to a separate but similar patient cohort. Additionally, we analyzed the role of biomarkers for diagnosing upper extremity DVT (UE-DVT).

METHODS

Between April 2009 and March 2012, all patients presenting for a duplex ultrasound exam with concern of DVT were screened. Demographics, clinical data, D-dimer, sP-sel, C-reactive protein, a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13, and von Willebrand factor levels were prospectively collected in 279 patients (234 LE-DVT, 45 UE-DVT). Continuous and categorical variables among patients with DVT were compared with patients without DVT. The diagnostic sensitivity, specificity, positive predictive value, and negative predictive value were then calculated using our previously derived cut points to rule in or exclude DVT.

RESULTS

Among 234 patients evaluated for LE-DVT, 112 (48%) patients had a confirmed LE-DVT with significant differences in all biomarkers. When Wells score ≥2, sP-sel could rule in LE-DVT with a specificity of 97.5% and a positive predictive value of 91%, which was more accurate than Wells score ≥2 and D-dimer (specificity, 65%; positive predictive value, 69%). When Wells score was <2, D-dimer was superior to sP-sel for excluding the diagnosis of LE-DVT (sensitivity, 98%; negative predictive value, 95% vs sensitivity, 91%; negative predictive value, 79%). The use of additional biomarkers did not increase accuracy. Had imaging not been available, we could have correctly ruled in or ruled out LE-DVT in 29% (67/234) of patients. The use of sP-sel in UE-DVT was nondiagnostic.

CONCLUSIONS

We demonstrate that when Wells score ≥2, sP-sel is an excellent biomarker to rule in LE-DVT. Different from our previous study, D-dimer and a Wells score <2 was most sensitive at excluding a diagnosis of LE-DVT. Combined, Wells score, sP-sel, and D-dimer can both rule in and exclude LE-DVT in approximately one-third of patients.

Outcomes associated with ablation compared to combined ablation and transilluminated powered phlebectomy in the treatment of venous varicosities

BACKGROUND

Patients with painful varicose veins and venous insufficiency can be treated by eliminating axial reflux only or by eliminating axial reflux plus phlebectomy with transilluminated powered phlebectomy. This study was undertaken with the aim of determining and improving signs and symptoms of venous disease (measured by venous clinical severity score) and complications (by routine surveillance ultrasound and long-term post-operative follow up) for each treatment strategy.

METHODS

We performed a retrospective evaluation of prospectively collected data from 979 limbs undergoing procedures for significant varicose veins and venous insufficiency from March 2008 until June 2014 performed at a single tertiary referral hospital. Patient demographics, Clinical Etiology Anatomy and Pathophysiology classification, venous clinical severity scores pre- and post-procedure, treatment chosen, and peri-operative complications were collected; descriptive statistics were calculated and unadjusted surgical outcomes for patients stratified by the procedure performed. Multivariable logistic regression was used to evaluate the relationship between procedure type and thrombotic complications after adjusting for patient characteristics, severity of disease, pre-operative anticoagulation, and post-operative compression.

RESULT

Venous clinical severity scores improved more with radiofrequency ablation + transilluminated powered phlebectomy as compared to radiofrequency ablation alone (3.8 ± 3.4 vs. 3.2 ± 3.1, p = 0.018). Regarding deep venous thrombosis, there was no significant difference between radiofrequency ablation + transilluminated powered phlebectomy vs. radiofrequency ablation alone. There was no statistical difference in asymptomatic endovenous heat-induced thrombosis or infection, although there were slightly more hematomas and cases of asymptomatic superficial thrombophlebitis with combined therapy. On multivariable analysis, only procedure type predicted thrombotic complications.

CONCLUSION

Ablation of axial reflux plus transilluminated powered phlebectomy produces improved outcomes as measured by venous clinical severity score, with slight increases in minor post-operative complications and should be strongly considered as initial therapy when patients present with significant symptomatic varicose veins and superficial venous insufficiency. Implementation of a standardized thromboprophylaxis protocol with individual risk assessment results in few significant thrombotic complications amongst high-risk patients, thus potentially obviating the need for routine post-operative duplex.

Feasibility of localized immunosuppression: 1. Exploratory studies with glucocorticoids in a biohybrid device designed for cell transplantation

Emerging biotechnologies, such as the use of biohybrid devices for cellular therapies, are showing increasing therapeutic promise for the treatment of various diseases, including type 1 diabetes mellitus. The functionality of such devices could be greatly enhanced if successful localized immunosuppression regimens could be established, since they would eliminate the many otherwise unavoidable side effects of currently used systemic immunosuppressive therapies. The existence of local immune privilege at some specialized tissues, such as the eye, CNS, or pregnant uterus, supports the feasibility of localized immunomodulation, and such an approach is particularly well-suited for cell transplant therapies where all transplanted tissue is localized within a device. Following the success of syngeneic transplantation in a subcutaneous prevascularized device as a bioartificial pancreas in a rodent model, we now report the first results of exploratory in vivo islet allograft studies in rats using locally delivered glucocorticoids (dexamethasone phosphate and the soft steroid loteprednol etabonate). Following in vitro assessments, in silico drug distribution models were used to establish tentative therapeutic dose ranges. Sustained local delivery was achieved via implantable osmotic mini-pumps through a central sprinkler, as well as with a sustained-delivery formulation for loteprednol etabonate using poly(D,L-lactic) acid (PLA) microspheres. Doses delivered locally were approximately hundred-fold smaller than those typically used in systemic treatments. While several solubility, stability, and implantation problems still remain to be addressed, both compounds showed promise in their ability to prolong graft survival after tapering of systemic immunosuppression, compared to control groups.

Impact of a province-wide nurses' strike on medical care in a regional referral centre

A 4-week, province-wide nurses' strike in Alberta in 1982 caused the closure of 57% of the acute care beds, including 47% of the intensive care beds, in Calgary. The effects of the strike on patient care at Foothills Provincial General Hospital, where nurses did not strike, were assessed. The number of emergency admissions, severity of illness and rate of death in the intensive care unit increased. On the other hand, the rate of death, length of stay and number of unexpected deaths on the medical wards were similar to those in the control periods before and after the strike. A subjective perception by hospital personnel of deteriorating patient care caused much anxiety; however, the results of analysis of measurable aspects of care suggested that the patients admitted to hospital received care during the strike that was comparable to care given before or after the strike. The inconvenience and potential harm to the patients not admitted because they had less severe illness were not measured.

Thromboembolic outcomes are decreased with the use of a standardized venous thromboembolism risk assessment and prophylaxis protocol for patients undergoing superficial venous procedures

OBJECTIVE

Patients with venous insufficiency can be treated with ablation or phlebectomy, or both. Patients undergoing superficial venous procedures have an elevated risk of deep vein thrombosis (DVT) and pulmonary embolism (PE). At our institution, we initiated a standardized protocol in which patients with a Caprini score (2005 version) of ≥8 are treated with 1 week of prophylactic anticoagulation after the procedure. Duplex ultrasound was performed at 1 week and then within 90 days after the procedure. This aim of the present study was to determine the thrombotic and clinical outcomes after superficial vein procedures using a standardized protocol for DVT/PE risk assessment and prophylaxis.

METHODS

We performed a retrospective analysis of prospectively collected data of superficial vein procedures from 2015 to 2021 at a single center. The patient demographics, CEAP (Clinical-Etiology-Anatomy-Pathophysiology) clinical class, venous clinical severity score, patient-reported outcomes, treatment type, Caprini scores, pre- and postoperative anticoagulation use, and outcomes were collected. Descriptive statistics were used for the patient demographics, procedure details, and unadjusted surgical outcomes. Multivariable logistic regression was used to evaluate the relationship between procedure type and DVT and PE after adjusting for patient characteristics, disease severity, periprocedural anticoagulation, and Caprini score.

RESULTS

A total of 1738 limbs were treated with ablation (n = 820), phlebectomy (n = 181), or ablation and phlebectomy (n = 737). More patients were women (67.1%) and White (90.9%). The overall incidence of DVT/PE was 1.4%. Patients undergoing ablation with phlebectomy had higher rates of DVT/PE (2.7%) than those undergoing ablation (0.2%) or phlebectomy alone (1.7%; P < .01). However, only 30% of DVTs were above the knee. On multivariate analysis, only the procedure type predicted for DVT/PE. However, patients undergoing ablation and phlebectomy achieved better patient-reported outcomes (Caprini score, 5.9) compared with those undergoing ablation (Caprini score, 7.2) or phlebectomy (Caprini score, 7.9) alone (P < .01). The best improvement in the venous clinical severity score was seen with phlebectomy alone.

CONCLUSIONS

The expected difference in the DVT/PE rates between high- and low-risk groups did not materialize in our patients, perhaps secondary to the additional chemoprophylaxis prescribed for the high-risk cohort (Caprini score, ≥8). These results call for a randomized trial to assess the efficacy of a standardized protocol in the reduction of DVT/PE after superficial vein procedures.