Epidural catheter with integrated light guides for spectroscopic tissue characterization

Epidural catheters are used to deliver anesthetics and opioids for managing pain in many clinical scenarios. Currently, epidural catheter insertion is performed without information about the tissues that are directly ahead of the catheter. As a result, the catheter can be incorrectly positioned within a blood vessel, which can cause toxicity. Recent studies have shown that optical reflectance spectroscopy could be beneficial for guiding needles that are used to insert catheters. In this study, we investigate the whether this technique could benefit the placement of catheters within the epidural space. We present a novel optical epidural catheter with integrated polymer light guides that allows for optical spectra to be acquired from tissues at the distal tip. To obtain an initial indication of the information that could be obtained, reflectance values and photon penetration depth were estimated using Monte Carlo simulations, and optical reflectance spectra were acquired during a laminectomy of a swine ex vivo. Large differences between the spectra acquired from epidural adipose tissue and from venous blood were observed. The optical catheter has the potential to provide real-time detection of intravascular catheter placement that could reduce the risk of complications.

Assessing response of myeloma bone disease with diffusion-weighted MRI

OBJECTIVES

To measure apparent diffusion coefficient (ADC) values in patients with active myeloma and remission and to determine whether changes differ in those responding/progressing on treatment. The relationship between changes in marrow fat and ADC was also explored.

METHODS

20 patients were recruited. T(1 )weighted, T(2) weighted, short tau inversion-recovery, diffusion-weighted and two-point Dixon MRI of the lumbar spine and pelvis were performed at baseline, 4-6 weeks and 20 weeks.

RESULTS

ADC values of active disease (mean 761.2 ± 255×10(-6) mm(2) s(-1)) were significantly higher (p=0.047) than marrow in remission (mean 601.8 ± 459×10(-6) mm(2) s(-1)). Changes in ADC in responders showed a significant increase at 4-6 weeks (p=0.005) but no significant change between baseline and 20 weeks (p=0.733). ADCs in progressing and stable patients did not change significantly between either time point. Pearson's correlation coefficient between change in fat fraction and change in the number of pixels with an ADC of ≤655×10(-6) mm(2) s(-1) was 0.924, indicating a significant correlation (p<0.001).

CONCLUSION

ADC values in active myeloma are significantly higher than marrow in remission, indicating the potential for diffusion-weighted MRI to quantify the transition from active disease to remission and vice versa. This study confirms significant changes in ADC in patients responding to treatment and indirect evidence from two-point Dixon MRI suggests that these changes are influenced by changes in marrow fat.

ADVANCES IN KNOWLEDGE

ADC of active myeloma is significantly higher than marrow in remission; the direction of ADC changes on treatment is dependent on the timing of measurements and is influenced by changes in marrow fat.

Trachoma and ocular Chlamydia trachomatis rates in children in trachoma-endemic communities enrolled for at least three years in the Tanzania National Trachoma Control Programme

Trachoma, a blinding eye disease caused by repeated and prolonged infection with Chlamydia trachomatis, is a significant public health problem for sub-Saharan Africa. Tanzania has had a National Trachoma Task Force since 1999, working on trachoma control in endemic districts. The objective of this study was twofold: first, to determine the current status of infection and clinical trachoma in these districts in Tanzania, and second, to determine if a combination of clinical signs could be used as a surrogate for infection. We conducted a survey for trachoma and infection with C. trachomatis in 75 villages in eight districts of Kongwa, Kilosa, Mpwapwa, Bahi, Kondoa, Manyoni, Monduli and Iramba in Tanzania, which have previously been shown to be endemic. In each village, a random sample of households, and of children within households, was taken for examination. Trachoma was graded using the World Health Organization system, which we expanded, and a swab taken to determine presence of infection. The rates of trachoma ranged from 0% in Iramba District to 15.17% in Monduli District, with large variation in villages within districts. Infection rates were generally lower than trachoma rates, as expected, and most districts had villages with no infection. A combination of clinical signs of trachoma in children, when absent, showed very high specificity for identifying villages with no infection. We conclude that these signs might be useful for monitoring absence of infection in villages, and that districts with trachoma prevalence between 10% and 15% should have village level rapid surveys to avoid unnecessary mass treatment.

Pharmacokinetics and pharmacodynamics of GS-9350: a novel pharmacokinetic enhancer without anti-HIV activity

GS-9350 is a new chemical entity under development as a potent, mechanism-based inhibitor of human cytochrome P450 3A (CYP3A) isoforms. Its intended use is to increase the systemic exposure of coadministered agents that are metabolized by CYP3A enzymes. Unlike ritonavir, which is in current clinical use for this purpose, GS-9350 is devoid of anti-HIV activity. The pharmacokinetics of GS-9350 and its efficacy in increasing systemic exposure of the probe CYP3A substrate midazolam were examined in a study involving single- and multiple-dose escalations of GS-9350 from 50 to 400 mg. Single-dose escalation from 50 to 400 mg resulted in a 164-fold increase in GS-9350 exposure, whereas multiple-dose escalation in the dosage range of 50-300 mg resulted in a 47-fold increase in exposure. GS-9350 potently inhibited midazolam apparent clearance (95% reduction), similar in effect to ritonavir 100 mg. GS-9350 was generally well tolerated at all doses, and there was no evidence of dose-limiting toxicity. Establishing proof-of-concept, GS-9350 is currently under phase II development as a potential alternative to ritonavir for use with antiretroviral agents (including the HIV integrase inhibitor elvitegravir) that are often prescribed along with a "booster" drug.

Dose-response of ritonavir on hepatic CYP3A activity and elvitegravir oral exposure

Ritonavir, a potent inhibitor of cytochrome P450 isoform 3A (CYP3A) activity, is frequently used to boost the effects of protease inhibitors at doses of 100-400 mg per day; however, human data regarding the optimal dose required for boosting are limited. This study systematically evaluated the ritonavir dose-response relationship on presystemic and systemic CYP3A metabolism using the human immunodeficiency virus integrase inhibitor elvitegravir and midazolam as probe substrates. Ritonavir administered once daily with elvitegravir exhibited nonlinear pharmacokinetics, with a 119-fold increase in the area under the plasma concentration-time curve over the dosing interval over a 20- to 200-mg dose range. The 20-mg dose of ritonavir substantially reduced CYP3A-mediated clearance (CL), as evidenced by a 66% reduction in midazolam CL that plateaued to 17% of baseline activity at a 100-mg dose. Maximum inhibition of elvitegravir apparent oral CL was achieved with ritonavir doses of 50-100 mg. Elvitegravir and ritonavir were generally well tolerated in this study. These data provide a critical understanding of ritonavir's dose-response relationship for inhibition of CYP3A activity in humans.

Turnover and function of noncoding RNA polymerase II transcripts

In the past few years, especially since the discovery of RNA interference (RNAi), our understanding of the role of RNA in gene expression has undergone a significant transformation. This change has been brought about by growing evidence that RNA is more complex and transcription more promiscuous than has previously been thought. Many of the new transcripts are of so-called noncoding RNA (ncRNA); i.e., RNA that does not code for proteins such as mRNA, or intrinsic parts of the cellular machinery such as the highly structured RNA components of ribosomes (rRNA) and the small nuclear RNA (snRNA) components of the splicing machinery. It is becoming increasingly apparent that ncRNAs have very important roles in gene expression. This paper focuses on work from our laboratory in which we have investigated the roles and turnover of ncRNA located within the gene pre-mRNA, which we refer to as intragenic ncRNA. Also discussed are some investigations of intergenic ncRNA transcription and how these two classes of ncRNA may interrelate.

Long-term follow-up of porous polyethylene spherical implants after enucleation and evisceration

PURPOSE

To present long-term follow-up data on enucleations and eviscerations carried out with placement of spherical porous polyethylene implants.

METHODS

A retrospective, interventional, noncomparative case series of all patients undergoing primary evisceration or enucleation surgery from one teaching hospital ophthalmology department.

RESULTS

In total, 106 cases were identified. Eighty patients (75.5%) underwent enucleation (group A) and 26 (24.5%) underwent evisceration (group B). Patient demographics were similar in both groups. Mean implant size in group A was 20.5 mm and 17.2 mm in group B. Mean follow-up in group A was 40 months (range, 12 to 80 months). Mean follow-up in group B was 63 months (range, 12 to 72 months). Six cases (7.5%) in group A had complications (excluding implant exposure), whereas one case (3.8%) in group B had a complication (excluding implant exposure). Five patients (6.3%) in group A had implant exposure; 14 cases (53.8%) of implant exposure occurred in group B.

CONCLUSIONS

Our case series revealed a significantly higher incidence of implant exposure after evisceration than after enucleation. Our data suggest that enucleation should be the procedure of choice when removing an eye to minimize the risk of subsequent complications, particularly orbital implant exposure.