Thiomers: Inhibition of cytochrome P450 activity

The aim of the present study was to investigate the potential of different thiolated polymers (thiomers) on the catalytic activity of CYP450s on one hand and to explore new inhibitors for CYP activity on the other hand. Several thiolated polymers including poly(acrylic acid)-cysteine (PAA-cysteine), chitosan-thioglycolic acid (chitosan-TGA), and thiolated PEG-g-PEI copolymer along with brij® 35, myrj® 52 and the well-established CYPP450 inhibitor verapamil were screened for their CYP3A4 and CYP2A6 inhibitory activity, and their IC₅₀ values were determined. Both enzyme inhibition assays were performed in 96-well microtiter plates. 7-Benzyloxy-4-(trifluoromethyl)-coumarin (BFC) and 7-hydroxycoumarin (7-HC) were used as fluorescent substrates in order to determine CYP3A4 and CYP2A6 catalytic activity, respectively. All investigated compounds inhibited CYP3A4 as well as CYP2A6 activity. All tested (thiolated) polymers were found to be more potent inhibitors of CYP3A4 than of CYP2A6 catalytic activity. Apart from verapamil that is a known CYP3A4 inhibitor, brij® 35 and myrj® 52 were explored as potent inhibitors of CYP3A4 and CYP2A6 catalytic activity. Among the tested polymers, the rank order for CYP3A4 inhibition was PAA-cysteine (100 kDa) > brij® 35 > thiolated PEG-g-PEI copolymer (16 kDa) > myrj® 52 > PAA (100 kDa) > PAA-cysteine (450 kDa) > verapamil > PAA (450 kDa) > chitosan-TGA (150 kDa) > chitosan (150 kDa). On the other hand, the rank order of CYP2A6 inhibition was brij® 35 > PAA-cysteine (100 kDa) > chitosan-TGA (150 kDa) > PAA (100 kDa) > thiolated PEG-g-PEI copolymer (16 kDa) > PAA-cysteine (450 kDa) > chitosan (150 kDa) > verapamil > PAA (450 kDa) > myrj® 52. Thus, this study suggests that (thiolated) polymers display a promising potential to inhibit cytochrome P450s activity and might turn out to be potentially valuable tools for improving the oral bioavailability of actively secreted compounds by avoiding intestinal metabolism.     

Carpal tunnel syndrome secondary to an accessory flexor digitorum superficialis muscle belly: case report and review of the literature

Anomalous muscles usually do not cause symptoms but are of academic interest mainly discovered during cadaveric dissection. An aberrant muscle belly arising from the index finger flexor digitorum superficialis tendon causing carpal tunnel syndrome is rare. The management of such an anatomical variant is dependent on whether the median nerve compression is associated with a palpable mass. A brief case highlighting important management principles along with a complete literature review is reported.     

The association of the Friesinger score and pulse pressure in an urban South Asian patient population: pulse pressure,an independent predictor of coronary artery disease

Increase in pulse pressure has been shown to be predisposing factor for Coronary Artery Disease (CAD) in diverse patient populations but its relationship with the severity of CAD, particularly in the South Asians immigrant population of United States has not been demonstrated. We performed a single-center, cross-sectional study. Pulse pressure was calculated by the difference between the systolic and diastolic brachial blood pressures, and the Friesinger score (FS) was used to quantify the severity of CAD with the score of 5 used as a cutoff for extensive disease. We also sought to assess the correlation between the Friesinger score and the 10-year cardiovascular event (CVD) risk as calculated by the Framingham score. Odds ratios and 95% confidence intervals for the associations between explanatory variables and a high Friesinger score were estimated using multivariate logistic regression models. P values below .05 were considered to be statistically significant. Statistical analysis was performed using STATA version 10 software package (College Station, TX). The mean pulse pressure was significantly higher in participants with an FS of ≥5 compared with participants with an FS of <5 (63 vs. 46 mm Hg; P = .004). In univariate analysis, a pulse pressure ≥40 mm Hg was associated with a five-fold increased odds of a higher FS compared with a pulse pressure <40 mm Hg (P = .039), which was unchanged in multivariate analysis. In multivariate analysis, even after adjustment for presence of hypertension, a 10 mm Hg increase in pulse pressure was associated with a 1.97-fold increased odds of a higher FS (95% CI 1.22–3.71, P = .009). The mean Framingham score was higher in participants with a higher FS, but this difference was not significant (32.7 vs. 20.3; P = .1139). Our study demonstrates that pulse pressure, a well-established marker of vascular health, is a significant independent predictor of the severity of CAD as assessed by coronary angiography in South Asians.     

High Skp2 expression characterizes high-risk neuroblastomas independent of MYCN status.

PURPOSE: Amplified MYCN oncogene defines a subgroup of neuroblastomas with poor outcome. However, a substantial number of MYCN single-copy neuroblastomas exhibits an aggressive phenotype similar to that of MYCN-amplified neuroblastomas even in the absence of high MYCN mRNA and/or protein levels. EXPERIMENTAL DESIGN: To identify shared molecular mechanisms that mediate the aggressive phenotype in MYCN-amplified and single-copy high-risk neuroblastomas, we defined genetic programs evoked by ectopically expressed MYCN in vitro and analyzed them in high-risk versus low-risk neuroblastoma tumors (n = 49) using cDNA microarrays. Candidate gene expression was validated in a separate cohort of 117 patients using quantitative PCR, and protein expression was analyzed in neuroblastoma tumors by immunoblotting and immunohistochemistry. RESULTS: We identified a genetic signature characterized by a subset of MYCN/MYC and E2F targets, including Skp2, encoding the F-box protein of the SCF(Skp2) E3-ligase, to be highly expressed in high-risk neuroblastomas independent of amplified MYCN. We validated the findings for Skp2 and analyzed its expression in relation to MYCN and E2F-1 expression in a separate cohort (n = 117) using quantitative PCR. High Skp2 expression proved to be a highly significant marker of dire prognosis independent of both MYCN status and disease stage, on the basis of multivariate analysis of event-free survival (hazard ratio, 3.54; 95% confidence interval, 1.56-8.00; P = 0.002). Skp2 protein expression was inversely correlated with expression of p27, the primary target of the SCF(Skp2) E3-ligase, in neuroblastoma tumors. CONCLUSION: Skp2 may have a key role in the progression of neuroblastomas and should make an attractive target for therapeutic approaches.     

Left ventricular assist device implantation via left thoracotomy: alternative to repeat sternotomy

Repeat sternotomy for left ventricular assist device insertion may result in injury to the right heart or patent coronary grafts, complicating intraoperative and postoperative management. In 4 critically ill patients, left thoracotomy was used as an alternative to repeat sternotomy. Anastomosis of the outflow conduit to the descending thoracic aorta provided satisfactory hemodynamic support.     

Syndrome of cerebrospinal fluid hypovolemia following lumbar puncture cerebrospinal fluid leak in a patient with idiopathic intracranial hypertension

An 11-year-old girl presented with headache of 3 months' duration. There was bilateral disc edema. The cerebrospinal fluid pressure was 50 cm of water with normal cerebrospinal fluid cytology and biochemistry. She developed severe headache (different and disabling), dizziness, vomiting, and backache on sitting up 6 hours after lumbar puncture, and lying supine relieved all of her symptoms. Intravenous fluids, analgesics, and complete bed rest did not relieve her symptoms over the next 72 hours. She was completely relieved of her symptoms on receiving two tablets of Caffergot containing 200 mg of caffeine and 2 mg of ergotamine 72 hours after lumbar puncture. The symptoms recurred 48 hours later, and a repeat dose of Caffergot was required. Magnetic resonance imaging (MRI) done 96 hours after lumbar puncture revealed the entire dura overlying the brain, including the posterior fossa, showing intense enhancement on contrast injection with leak at the lumbar puncture site. Oral caffeine (coffee, three times a day) was advised over 1 week. The patient remained asymptomatic, and a repeat MRI scan after 10 days showed complete clearing of the cerebrospinal fluid leak with no dural enhancement. The syndrome of cerebrospinal fluid hypovolemia following lumbar puncture is reported in a girl with idiopathic intracranial hypertension.     

A modified live Mycoplasma gallisepticum vaccine to protect chickens from respiratory disease

The aim of this study was to assess the efficacy of a modified live Mycoplasma gallisepticum vaccine (GT5) for the protection of chickens against infection and respiratory disease. GT5 was constructed by the reconstitution of the avirulent high passage R (R(high)) strain with the gene encoding the major cytadhesin GapA. GT5 expressed GapA on its surface yet retained the phenotypic characteristics of the parental R(high) strain. Birds vaccinated with GT5 were protected upon challenge with the virulent low passage R (R(low)) strain as evidenced by a complete absence of tracheal lesions 2 and 4 weeks post-challenge, in contrast to sham immunized/challenged control birds. Modest amounts of IgG, and little, if any secretory IgA or IgM anti-M. gallisepticum were found in tracheal washings following vaccination. However, copious amounts of specific IgA were found following challenge, especially in sham immunized birds. This suggests that the tracheal IgG elicited by GT5 vaccination may have been responsible for blocking the initial colonization of R(low), thereby resulting in protection.