Ionophore and Biometal Modulation of P-glycoprotein Expression and Function in Human Brain Microvascular Endothelial Cells

Purpose

Biometals such as zinc and copper have been shown to affect tight junction expression and subsequently blood-brain barrier (BBB) integrity. Whether these biometals also influence the expression and function of BBB transporters such as P-glycoprotein (P-gp) however is currently unknown.

Methods

Using the immortalised human cerebral microvascular endothelial (hCMEC/D3) cell line, an in-cell western assay (alongside western blotting) assessed relative P-gp expression after treatment with the metal ionophore clioquinol and biometals zinc and copper. The fluorescent P-gp substrate rhodamine-123 was employed to observe functional modulation, and inductively coupled plasma mass spectrometry (ICP-MS) provided information on biometal trafficking.

Results

A 24-h treatment with clioquinol, zinc and copper (0.5, 0.5 and 0.1 μM) induced a significant upregulation of P-gp (1.7-fold) assessed by in-cell western and this was confirmed with western blotting (1.8-fold increase). This same treatment resulted in a 23% decrease in rhodamine-123 accumulation over a 1 h incubation. ICP-MS demonstrated that while t8his combination treatment had no effect on intracellular zinc concentrations, the treatment significantly enhanced bioavailable copper (4.6-fold).

Conclusions

Enhanced delivery of copper to human brain microvascular endothelial cells is associated with enhanced expression and function of the important efflux pump P-gp, which may provide therapeutic opportunities for P-gp modulation.

     

Disparities in women’s cancer-related quality of life by Southern Appalachian residence

Purpose

The purpose was to determine whether Appalachian residence alone or in combination with violence was linked to poorer quality of life (QOL).

Methods

Women recently diagnosed and included in either the Kentucky or North Carolina Cancer Registries were interviewed by phone between 2009 and 2015 (n?=?3320; mean age?=?56.74). Response rates were similar by state (40.1 in Kentucky and 40.9% in North Carolina). Appalachian (N?=?990) versus non-Appalachian residents (N?=?2330) were hypothesized to have poorer QOL defined as (a) lower Functional Assessment of Cancer Therapy—General (FACT-G) scores and (b) more symptoms of depression, stress, or comorbid physical conditions. Lifetime intimate partner or sexual violence was first investigated as a moderator then mediator of regional differences. Multiple analyses of covariance (MANCOVA) models were used.

Results

Violence modified the effect of Appalachian residence on poorer QOL outcomes; FACT-G total scores (p?=?.02) were lowest for women living in Appalachia who had additionally experienced violence. Socioeconomic indicators appeared to mediate or explain differences in QOL outcomes by Appalachian residence such that when adjusting for income, education and insurance, Appalachian residence remained associated only with poorer physical QOL outcomes (p?<?.05).

Conclusions

While violence rates did not differ by residence, the combined effect of living in Appalachia and experiencing violence resulted in significantly greater impact on poorer QOL among women recently diagnosed with cancer. Clinical consideration of patients’ residence, socioeconomic status and violence experienced may help identify and mitigate the longer-term impact of these identifiable factors associated with poorer QOL.

     

A double mobility acetabular implant for primary hip arthroplasty in patients at high risk of dislocation

IntroductionDislocation following total hip replacement continues to be a problem for which no completely satisfactory solution has been found. Several methods have been proposed to reduce the incidence of hip dislocations with varying degrees of success, including elevated rim liners, constrained liners and large diameter bearings. We present our experience with the double mobility acetabular component in patients at high risk of instability.MethodsThis was a retrospective review of 65 primary total hip arthroplasties in 55 patients (15 men, 40 women), performed between October 2005 and November 2009. The majority (80%) of patients had at least two and 26% had at least three risk factors for instability. The mean age was 76 years (range: 44–92 years). The patients were followed up for a mean duration of 60 months (range: 36–85 months).ResultsFourteen patients died and one was lost to follow-up, leaving fifty hips for final assessment. Until the final follow-up appointment, no patients had dislocation and none required revision surgery. The mean Oxford hip score improved from 45.0 to 26.5 (p<0.0001). The mean Merle d’Aubigné pain score improved from 1.4 to 4.9 (p<0.0001), the walking score from 2.3 to 3.1 (p<0.07) and the absolute hip function score from 5.4 to 10.8 (p<0.0001). There were no clinical or radiographic signs of loosening.ConclusionsThe double mobility acetabular component was successful at preventing dislocation during early to medium-term follow-up. However, as data are still lacking with regard to polyethylene wear rates at the additional bearing surface, it would be prudent to restrict the use of this implant to selected patients at high risk of instability.     

Comparison of the haemodynamic effects of epoprostenol (prostacyclin) and tolazoline.

The haemodynamic effects of infusion of epoprostenol (prostacyclin) and bolus injection of tolazoline were compared in a crossover study in 11 children with pulmonary hypertension caused by pulmonary vascular disease. The children were studied during cardiac catheterisation, while they were anaesthetised, paralysed, and ventilated with 100% oxygen. The order of drug administration was not randomised because tolazoline has a half life of hours whereas epoprostenol has a half life of a few minutes. Both drugs caused pulmonary and systemic vasodilatation, and there were no significant differences between the two. The 95% confidence intervals suggest that tolazoline did not have a clinically important haemodynamic advantage over epoprostenol. Previous reports suggest that serious side effects are common when tolazoline is used in repeated doses; epoprostenol has only a few minor side effects that are rapidly reversible when the infusion is stopped. Epoprostenol is more expensive than tolazoline but this study suggests that epoprostenol is a more suitable pulmonary vasodilator if more than a single dose is required.     

In vivo validation of the origin of the esophageal electrocardiogram

Esophageal electrocardiography is a clinical and investigational technique that is useful for determining atrial conduction intervals, analyzing atrial rhythms and mapping conduction pathways. Although the left atrial origin of the esophageal electrocardiogram has long been implied, recently that origin has been questioned. In the present study, the origin of the esophageal deflection is defined by direct right and left atrial mapping studies performed with simultaneous esophageal electrograms obtained from three positions (high, mid and low). Seven patients with normal left atrial dimensions (group I) and five patients with left atrial enlargement (group II) underwent transseptal catheterization during the course of electrophysiologic study. In group I (normal left atrial dimensions), conduction time from the high right atrium to each of the three esophageal positions corresponded to conduction times to left atrial sites ranging from 1 to 3 cm lateral to the left interatrial septum. The mid- and low esophageal conduction times were all significantly longer than conduction time to the left side of the septum (p less than 0.05). In group II (enlarged left atrium), conduction times to each of the esophageal sites corresponded to conduction times to left atrial sites lying between the mid-left atrium and a point 1 cm lateral to the left side of the septum. A significant trend toward longer conduction time to the mid-esophageal position than to the left septum was noted (p less than 0.1). In both groups, conduction times measured with the esophageal catheter were significantly longer than conduction time to the right interatrial septum (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Biochemical changes in the jejunal mucosa of dogs with naturally occurring exocrine pancreatic insufficiency

The roles of extracellular and intracellular mechanisms in the degradation of brush border proteins have been investigated by studying the small intestinal mucosa of dogs with naturally occurring exocrine pancreatic insufficiency. Peroral jejunal biopsies were homogenised and the organelles separated by isopycnic centrifugation on continuous sucrose density gradients. The distributions of marker enzymes for the principal subcellular organelles were determined in the gradients and related to the specific activities in the homogenates. There were increased activities of the brush border carbohydrases zinc-resistant α-glucosidase, maltase and sucrase in the pancreatic insufficient animals, but no change in lactase activity. The activity of γ-glutamyl transferase was also higher in the affected group; the activities of two other brush border enzymes, alkaline phosphatase and leucyl-β-naphthylamidase, however, were unaltered. These findings with an increase in the modal density of the brush border from 1·20 to 1·22 are consistent with an enhanced glycoprotein content of the microvillus membrane. There were also rises in the activities of lysosomal enzymes. N-Acetyl-β-glucosaminidase activity was increased in the soluble fractions and the percentage latent enzyme activity was reduced, findings indicative of an increased fragility of the lysosomal membrane. There were no marked alterations in the activities or density gradient distributions of marker enzymes for the other organelles, stressing the specificity of the changes in the brush borders and lysosomes. These findings are compatible with the degradation of certain exposed brush border proteins by pancreatic proteases and suggest that when this is defective, intracellular degradative mechanisms may be stimulated.     

Relation between achieved heart rate and outcomes in patients with atrial fibrillation (from the Atrial Fibrillation Follow-up Investigation of Rhythm Management [AFFIRM] Study)

Many patients with atrial fibrillation (AF) are treated with rate control and anticoagulation. However, the relation between the degree of heart rate (HR) control and clinical outcome is uncertain. We assessed whether lower achieved HR at rest and/or lower achieved exercise HR was associated with improved prognosis, quality of life (QoL), and functional status among patients in the AFFIRM study. Patients in the rate control arm and who were in AF at baseline and 2 months were included. Patients were grouped by quartile of achieved HR at rest (44 to 69, 70 to 78, 79 to 87, 88 to 148 beats/min) and achieved exercise HR following a 6-minute walk (53 to 82, 83 to 92, 93 to 106, 107 to 220 beats/min). QoL measurements and functional status were also analyzed. Complete data were available for 680 patients for achieved HR at rest, 349 patients for achieved exercise HR, and 118 patients for QoL. Survival free from cardiac hospitalization and overall survival were not significantly different among quartiles of achieved HR at rest (p = 0.19 and p = 0.8, respectively) or achieved exercise HR (p = 0.77 and p = 0.14, respectively). After controlling for covariates, there remained no significant relation between either achieved HR at rest or achieved exercise HR and event-free survival (hazard ratio 0.95, p = 0.35 and hazard ratio 0.98, p = 0.81) or overall survival (hazard ratio 1.03, p = 0.70 and hazard ratio 1.22, p = 0.13). Furthermore, there was no significant association between achieved HR and QoL measurements, New York Heart Association functional class, or 6-minute walking distance. After 2 months of drug titration, neither achieved HR at rest nor achieved exercise HR predicted survival free from cardiovascular hospitalization, overall survival, QoL, or functional status among patients with AF.