Preliminary phylogenetic identification of virulent Chlamydophila pecorum strains

Chlamydophila pecorum is an obligate intracellular bacterium associated with different pathological conditions in ruminants, swine and koala, which is also found in the intestine of asymptomatic animals. A multi-virulence locus sequence typing (MVLST) system was developed using 19 C. pecorum strains (8 pathogenic and 11 non-pathogenic intestinal strains) isolated from ruminants of different geographical origins. To evaluate the ability of MVLST to distinguish the pathogenic from the non-pathogenic strains of C. pecorum, the sequences of 12 genes were analysed: 6 potential virulence genes (ompA, incA, incB, incC, mip and copN), 5 housekeeping genes (recA, hemD, aroC, efp, gap), and the ORF663 gene encoding a hypothetical protein (HP) that includes a variant 15-nucleotides coding tandem repeat (CTR). MVLST provided high discriminatory power (100%) in allowing to distinguish 6 of 8 pathogenic strains in a single group, and overall more discriminatory than MLST targeting housekeeping genes. ompA was the most polymorphic gene and the phylogenetic tree based only on its sequence differentiated 4 groups with high bootstrap values. The number of CTRs (rich in serine, proline and lysine) in ORF663 detected in the pathogenic strains was generally lower than that found in the intestinal strains. MVLST appears to be a promising method for the differential identification of virulent C. pecorum strains, and the ompA, incA and ORF663 genes appear to be good molecular markers for further epidemiological investigation of C. pecorum.     

pH-responsive polymeric micelles of poly(ethylene glycol)-b-poly(alkyl(meth)acrylate-co-methacrylic acid): influence of the copolymer composition on self-assembling properties and release of candesartan cilexetil.

The objective of the present study was to investigate the influence of chemical structure and molecular weight of pH-sensitive block copolymers on their self-assembling properties, the loading and the release of candesartan cilexetil (CDN). Block copolymers of poly(ethylene glycol) and t-butyl methacrylate, iso-butyl acrylate, n-butyl acrylate or propyl methacrylate were synthesized by atom transfer radical polymerization. pH-sensitivity was obtained by hydrolysis of t-butyl groups. The poorly water-soluble drug CDN was incorporated in the micelles and the in vitro drug release was evaluated as a function of pH. The critical aggregation concentration of hydrolyzed copolymers (pK(a)=6.2-6.6) was higher compared to the unhydrolyzed ones. Dynamic light scattering studies and atomic force microscopy images revealed uniform size micelles with aggregation numbers ranging from 60 to 160. The entrapment efficiency of CDN was generally found to be above 90%, with drug loading levels reaching approximately 20% (w/w). Differential scanning calorimetry studies showed the amorphous nature of entrapped CDN. The release of CDN from pH-sensitive micelles was triggered upon an increase in pH from 1.2 to 7.2. These findings suggest that the PEG-b-poly(alkyl(meth)acrylate-co-methacrylic acid)s can self-assemble to form micelles which exhibit high loading capacities for CDN and release the drug in a pH-dependent fashion.     

Comparison of mydriatic regimens used in screening for retinopathy of prematurity in preterm infants with dark irides

PURPOSE: To determine the mydriatic regimen that provides optimal dilation of the pupil with minimal systemic side effects for screening of retinopathy of prematurity. METHODS: This cross-sectional, randomized, double-masked clinical trial compared cyclopentolate 1% + phenylephrine 2.5%, tropicamide 1% + phenylephrine 2.5%, and a prepared combination of cyclopentolate 0.2% with phenylephrine 1% for pupillary dilation in preterm infants with dark irides. Thirteen infants were randomized to each regimen. Outcomes measured were pupillary dilation, heart rate, blood pressure, abdominal girth, and intolerance to feeds. RESULTS: All three mydriatic regimens provided adequate pupillary dilation at 45 minutes, with dilation sustained at 60 minutes. There was a significant increase in mean blood pressure in the cyclopentolate 1% + phenylephrine 2.5% and the tropicamide 1% + phenylephrine 2.5% groups. Although there was no significant change of abdominal girth in any of the three groups, a total of eight patients developed intolerance to feeds; four (50%) of these infants were from the cyclopentolate 1% + phenylephrine 2.5% group. CONCLUSION: The prepared combination of cyclopentolate 0.2% + phenylephrine 1% appears to be the mydriatic of choice for preterm infants with dark irides as it provided adequate pupillary dilation with the least systemic side effects.     

Sleep deprivation in junior doctors--house officers in Singapore

House officers are known to endure marked levels of sleep deprivation in administration of their duties. We aim to establish sleep patterns of local house officers while on the job and the impact it might have on their mood and sleepiness state. We also studied their sleep during their final year of medical school and pre-university for identification of any prior sleep deprivation. Questionnaires were used to assess sleep and mood change. Sleepiness levels on the day after call were assessed using the Stamford Sleepiness Scale. Subjects were found to sleep a median of only 1.0 (+/- 2.0) h per night on call and 6.0 h (+/- 1.0) per non-call night. They suffered median of 5 interruptions (+/- 5) during sleep on one night call. Night call was found to adversely affect mood in 89.5% of the subjects while daytime sleepiness levels following call were found to increase the more the time spent at work after call. Subjects were found to have had 6.5 h (+/- 1.0) of sleep per night during final year of medical school and 8.0 h (+/- 1.0) in final year of pre-university. House officers enter the profession chronically sleep-deprived. The call schedule and general work regime further add to the existent sleep deprivation and may have adverse consequences on patient care and doctor's health. This calls for measures to be instituted for provision of proper sleep and work hours for them.     

Pathological stage does not alter the prognosis for renal lesions determined to be stage T1 by computerized tomography

PURPOSE: Pathological stage has been the most widely used prognosticator for evaluating surgically managed cases of renal cell carcinoma. Minimally invasive surgical approaches are being increasingly used to treat small masses for which traditionally pathological information is lacking (morcellation) or absent (radio frequency ablation or cryoablation). Preoperative cross-sectional imaging by computerized tomography (CT) or magnetic resonance imaging has been used to stage renal tumors clinically but it can lead to variances with traditional pathological staging systems, particularly with respect to microscopic invasion beyond the renal capsule. In this study we assessed whether radiographically staged clinical T1 lesions that were pathological T1 behave differently than those that were clinical stage T1 and up staged to pT3a. MATERIALS AND METHODS: The records of 296 patients who underwent surgical treatment for renal cell carcinoma at The Johns Hopkins Hospital between 1990 and 1999 were retrospectively reviewed. All patients had undergone preoperative CT or magnetic resonance imaging, which was used to assign a clinical stage and size (largest diameter) to each tumor in accordance with the 1997 TNM staging system. Following surgical resection pathological stage, size and tumor grade were determined. Only the 186 patients with clinical T1 tumors were included in this analysis. RESULTS: Of the 186 patients who were clinically found to have T1 lesions 125 (67%) had pathological T1 and 57 (31%) had pathological T3a lesions. All surgical margins and lymph nodes were negative at surgical resection. Mean tumor size +/- SD was 3.9 +/- 1.5 cm for pT1 lesions and 3.8 +/- 1.5 cm for pT3a lesions. When comparing these pathological groups using Kaplan-Meier analysis, 5-year recurrence-free survival was not statistically different in patients with pT1 and pT3a lesions (90.6 and 97.5%, respectively). CONCLUSIONS: Patients in whom the initial classification of T1 renal cell carcinoma by CT was up graded to T3a on pathological analysis (invasion of fat within Gerota's fascia) showed the same recurrence-free survival rate as patients with pathologically confirmed T1 lesions. Thus, smaller tumors (less than 7 cm) that are up graded to T3a based on capsule invasion behave much like T1 tumors and exact pathological T staging does not appear to impact overall survival.     

Neuromuscular complications after percutaneous radiofrequency ablation of renal tumors

Neuromuscular complications after percutaneous renal tumor ablation have not been previously reported. In a series of 48 patients undergoing percutaneous ablation, 3 of our patients had neuromuscular complications. One patient developed permanent flank laxity and two had transient paresthesias. Neuromuscular complications are uncommon, but may occur with percutaneous renal ablative surgery.     

A power efficient electronic implant for a visual cortical neuroprosthesis

An integrated microstimulator designed for a cortical visual prosthesis is presented, along with a pixel reordering algorithm, together minimizing the peak total current and voltage required for stimulation of large numbers of electrodes at a high rate. In order to maximize the available voltage for stimulation at a given supply voltage for generating biphasic pulses, the device uses monopolar stimulation, where the return electrode voltage is dynamically varied. Thus, the voltage available for stimulation is maximized, as opposed to the conventional fixed return voltage monopolar approach, and impedance is significantly lower than can be achieved using bipolar stimulation with microelectrodes. This enables the use of a low voltage power supply, minimizing power consumption of the device. An important constraint resulting from this stimulation strategy, however, is that current generation needs to be simultaneous and in-phase for all active parallel channels, imposing heavy stress on the wireless power recovery and regulation circuitry in large electrode count systems such as a visual prosthesis. An ordering algorithm to be implemented in the external controller of the prosthesis is then proposed. Based on the data for each frame of the video signal to be transmitted to the implant, the algorithm minimizes the total generated current standard deviation between time multiplexed stimulations by determining the most appropriate combination of parallel stimulation channels to be activated simultaneously. A stimulator prototype has been implemented in CMOS technology and successfully tested. Execution of the external controller reordering algorithm on an application specific hardware architecture has been verified using a System-On-Chip development platform. A near 75% decrease in the total stimulation current standard deviation was observed with a one-pass algorithm, whereas a recursive variation of the algorithm resulted in a greater than 95% decrease of the same variable.     

Association of red blood cell 5-methyltetrahydrofolate and severity of coronary artery disease: a cross-sectional study from Shiraz, southern Iran

In this study we tested the hypothesis that red blood cell 5-methyltetrahydrofolate, a long-term marker of the folate status, is associated with the severity of coronary artery disease and whether this association is independent of homocysteine, vitamin B₁₂, plasma 5-methyltetrahydrofolate, 5,10-methyltetrahyrofolate reductase C677T genotype, and other cardiovascular risk factors. Two hundred and fifty-one angiographically documented patients aged <70 years with single, double, or triple coronary artery disease were investigated. Red blood cell 5-methyltetrahydrofolate concentrations were significantly decreased with the increasing number of diseased vessels (analysis of variance, P < 0.001). Red blood cell 5-methyltetrahydrofolate was also inversely and significantly correlated with the number of diseased vessels (r = −0.36, P < 0.001). Stepwise multiple regression analysis showed that red cell 5-methyltetrahydrofolate was a strong predictor of number of diseased vessels independent of plasma total homocysteine, 5,10-methyltetrahyrofolate reductase C677T genotype, and all other coronary artery risk factors (β = −0.002, P < 0.001, r² = 0.128). The results of this study suggest that low red blood cell 5-methyltetrahydrofolate is associated with the severity of coronary artery disease independent from plasma homocysteine and other cardiovascular risk factors.