Conception and validation of a protocol for reuse of non-irrigated electrophysiology catheters in a Brazilian teaching hospital

Purpose

Since the Brazilian current legislation permits the reuse of single-use devices under a validated processing protocol, the main purpose of our study was to develop and validate a method for reusing non-irrigated electrophysiology catheter (EC).

Methods

Manual and mechanical processing by ultrasonic washer was associated with the use of enzymatic solution and hydrogen peroxide with a final rinse with filtered water. Validation of the cleaning process, as well as catheter integrity, was done by observing the ECs in stereoscopic microscope at ×60 magnification, followed by HemoCheck-S® (HCS) test to monitor the presence of residual blood on their surfaces. Ethylene oxide (EO) was used for sterilization, and the final validations of the processing were performed by assays of sterility, pyrogenicity, and EO residuals. Lastly, a cost-minimization study was performed.

Results

Cleaning process demonstrated absence of organic material detectable by HCS at the surfaces of the ECs. Assays for sterility were negative, and assays of EO residuals and endotoxins showed levels under established standards. The number of reuses was settled to a maximum of seven uses for the ECs with handle and ten uses for ECS without handle. The cost-minimization study showed an 84% savings, when considering seven reuses.

Conclusions

Processing of ECs was validated at all stages. Therefore, reuse of ECs under the conditions that we designed was considered safe for patients and cost-effective for our institution.

     

Myeloid but not lymphoid cells carry the 5q deletion: polymerase chain reaction analysis of loss of heterozygosity using mini-repeat sequences on highly purified cell fractions

Interstitial deletions of the long arm of chromosome 5 are among the most characteristic abnormalities observed in myeloid disorders. To assess the lineage involvement of peripheral blood cells from patients with a 5q--anomaly, purified neutrophils, monocytes, T lymphocytes, and B lymphocytes were analyzed for loss of heterozygosity using six different highly polymorphic mininucleotide and dinucleotide (CA) repeat sequences from the 5q31 to 5q33 region. Ten patients were screened by polymerase chain reaction (PCR) amplification and proved to be informative for at least one marker. Six patients showed a complete or partial disappearance of an allele in myeloid cells, whereas cells of lymphoid lineages exhibited full heterozygosity. The other patients displayed no allelic loss, indicating that the informative markers were located outside the deleted chromosomal segments. In addition, three female patients who were also polymorphic for the BstXI site in the PGK- 1 gene were analyzed for the methylation status of this gene. Clonality of hematopoiesis, as determined by non-random X-chromosome inactivation, followed the same cell pattern as the 5q-specific allelic losses. In conclusion, using tumor-specific and clonal markers, we have demonstrated that the 5q- anomaly is restricted to cells of myeloid origin, leaving lymphoid cells unaffected.     

Rapid reductions and millennial-scale variability in Nordic Seas sea ice cover during abrupt glacial climate changes

Constraining the past sea ice variability in the Nordic Seas is critical for a comprehensive understanding of the abrupt Dansgaard-Oeschger (D-O) climate changes during the last glacial. Here we present unprecedentedly detailed sea ice proxy evidence from two Norwegian Sea sediment cores and an East Greenland ice core to resolve and constrain sea ice variations during four D-O events between 32 and 41 ka. Our independent sea ice records consistently reveal a millennial-scale variability and threshold response between an extensive seasonal sea ice cover in the Nordic Seas during cold stadials and reduced seasonal sea ice conditions during warmer interstadials. They document substantial and rapid sea ice reductions that may have happened within 250 y or less, concomitant with reinvigoration of deep convection in the Nordic Seas and the abrupt warming transitions in Greenland. Our empirical evidence thus underpins the cardinal role of rapid sea ice decline and related feedbacks to trigger abrupt and large-amplitude climate change of the glacial D-O events.

Sea ice is a critical component of the global climate system as it affects Earth’s albedo, phytoplankton productivity, ocean-atmosphere heat and gas exchange, and ocean circulation (1). Rapid sea ice retreat, as observed in the modern Arctic Ocean, exerts important climate feedbacks that may lead to an accelerated climate warming at northern high latitudes (2). While many climate models have difficulties in reproducing the currently observed Arctic sea ice decline (3), the rates of ongoing atmospheric warming in some Arctic regions are already comparable with those of prominent abrupt climate changes that occurred during the last glacial period (4). The latter are referred to as Dansgaard–Oeschger (D-O) climate events and known from Greenland ice core records as abrupt shifts between cold Greenland stadials (GS) and warmer Greenland interstadials (GI) occurring repeatedly ∼10–110 ka (5, 6). The millennial-scale glacial climate variability was a global phenomenon with different characteristics in the northern and southern hemispheres, but the most striking feature of the D-O events is an extremely abrupt climate transition that includes an atmospheric warming of 5–16.5 °C over the Greenland ice sheet happening in just a few decades (7). Analogous to the modern and future sea ice retreat and resulting warming in the Arctic, the abrupt D-O climate transitions are widely believed to have been amplified by rapid sea ice retreat in the Nordic Seas (8–15).Today, the Nordic Seas are largely ice-free, and warm Atlantic surface waters flow into the Norwegian Sea as far north as Svalbard at ∼80°N (Fig. 1), where the Arctic sea ice cover is being eroded, in particular in the Barents Sea. The warm Atlantic surface waters release heat to the atmosphere as it flows northward, which is accompanied by convective intermediate and deep-water formation between Norway and Greenland, feeding the lower limb of the Atlantic Meridional Overturning Circulation (AMOC) (16). A portion of the Atlantic waters continues flowing into the stratified Arctic Ocean as subsurface waters (17). While the pattern of ocean circulation during GI was fairly comparable to that today, proxy data indicate that the glacial Nordic Seas exhibited a stable surface stratification during GS, similar to the modern Arctic Ocean (13, 18). The AMOC and associated northward surface heat transport into the Nordic Seas were weakened during GS, with most extreme weakening related to Heinrich events signified by massive iceberg discharges to the North Atlantic (19, 20). Intermediate and deep waters in the stadial Nordic Seas were 2–4 °C warmer as compared with GI or modern conditions, resulting from a stable halocline and reduced open-ocean convection (21, 22). Contemporaneously, an extended sea ice cover reaching at least as far south as the Greenland–Scotland Ridge at ∼60°N insulated the high-latitude atmosphere from the deep oceanic heat reservoir (23, 24). Model simulations support a subsurface warming scenario under extended sea ice during GS (22, 25, 26) and suggest that a rapid removal of the sea ice cover might have caused the abrupt and high-amplitude D-O climate warming (11, 12, 14, 15).Open in a separate windowFig. 1.Core sites and regional context of the study area. Yellow diamonds mark the core sites investigated in this study. The map shows the core-top P_BIP₂₅ distribution (42, 43, 63), illustrating the great potential of the biomarker approach for sea ice reconstruction. Orange, yellow, and green dots mark core-top sites north, east, and south of Greenland, respectively, data of which are investigated in this study. Small black dots indicate locations of published core-top data. Purple lines mark the modern sea ice extent during September (dashed) and March (solid), averaged between A.D. 1981 and 2010 (https://nsidc.org/; ref. 64). The thin blue line shows the P_BIP₂₅ = 0.2 isoline, representing best the modern winter/spring sea ice extent. Red arrows illustrate the warm and saline North Atlantic Current (NAC). The map was produced with Ocean Data View software (65).Although there is some evidence of millennial-scale sea ice fluctuations during the last glacial, the few available sea ice proxy records (23, 24, 27–31) are mostly restricted to the southern Norwegian Sea and the Arctic Ocean, often have a limited temporal resolution, and partly reflect opposing trends regarding stadial–interstadial sea ice changes depending on the proxies used. Here we present high-resolution sea ice biomarker records from two key sites that form a North–South transect within the Atlantic inflow region in the Norwegian Sea and are thus ideally suited to record spatiotemporal shifts in sea ice cover in both the entrance and the interior of the ocean basin, oceanic fronts, and Atlantic water inflow during the last glacial (Fig. 1). Furthermore, we combine these marine sea ice proxy records with an independent sea ice record based on bromine-enrichment (Br_enr) values from an East Greenland ice core, which significantly enhances the spatial coverage, the robustness of results, and temporal constraint of the sea ice reconstruction. We focus on five representative glacial D-O cycles between 32 and 41 ka, which comprise long- and short-lasting GI as well as several GS, one of which includes Heinrich Event 4. The application of the cryptotephra-based chronological constraints provides a level of robustness as to the timing, duration, and nature of the events unfolding during abrupt climate changes. Our study provides robust empirical evidence that resolves rapid and widespread sea ice retreat in the Nordic Seas and its role in initiating and amplifying the abrupt climate change of the glacial D-O events.     

New Alcohol Markers—How Useful Are They in Population Studies: The Svalbard Study 1988–89

Regular high consumption of alcohol in selected populations have, with high precision, been identified by two new alcohol markers; carbohydrate-deficient transferrin and mitochondrial aspartate aminotransferase. To test these markers in an unselected population, gamma-glutamyltransferase (GGT), carbohydrate-deficient transferrin (CDT), and mitochondrial aspartate aminotransferase (mAST) were measured in the Norwegian population, 310 males and 171 females, aged 18 to 60 years, living at Svalbard. Using self-reported alcohol intake as gold standard, sensitivity, specificity, positive predictive value, and likelihood-ratio were estimated according to different cutoff-points for alcohol intake and for the tests. In contrast to earlier studies, the sensitivity was in general low. With a specificity of 90% or higher, the sensitivity did not exceed 26% for any of the tests. Whereas CDT showed its best discriminatory power at lower intake of alcohol, GGT discriminated best at higher levels. Parallel and serial analysis of CDT and GGT indicated a conditional independence between the tests, as well as at higher and at lower levels of alcohol consumption. mAST was judged as not suitable in population studies.     

Influence of exercise order on repetition performance during low-intensity resistance exercise

The purpose of this study was to compare repetition maximum performance and ratings of perceived exertion during resistance exercise sessions conducted at a low intensity (i.e., 20 RM) and in different exercise orders. Twenty-one recreationally trained men performed two total body resistance exercise sessions in opposite orders; each exercise was performed for three sets with 2 minutes passive rest between sets and exercises. The results indicated significantly greater total repetitions for each exercise when performed near the beginning of a sequence and for the first set of each exercise, irrespective of the sequence. The ratings of perceived exertion, however, were not significantly different between sequences. In conclusion, repetition maximum performance for resistance exercise sessions conducted at a low intensity is significantly different based on exercise order. Therefore, when performing high repetitions with relatively low intensity loads, exercises should be prioritized based on individual needs and sports-specific movement patterns for greater volume and potential for the desired neuromuscular adaptations.     

VEGF Improves Skeletal Muscle Regeneration After Acute Trauma and Reconstruction of the Limb in a Rabbit Model

Background

Complicated tibial fractures with severe soft tissue trauma are challenging to treat. Frequently associated acute compartment syndrome can result in scarring of muscles with impaired function. Several studies have shown a relationship between angiogenesis and more effective muscle regeneration. Vascular endothelial growth factor (VEGF) is associated with angiogenesis but it is not clear whether it would restore muscle force, reduce scarring, and aid in muscle regeneration after acute musculoskeletal trauma.

Questions/purposes

Therefore, we asked whether local application of VEGF (1) restores muscle force, (2) reduces scar tissue formation, and (3) regenerates muscle tissue.

Methods

We generated acute soft tissue trauma with increased compartment pressure in 22 rabbits and shortened the limbs to simulate fracture débridement. In the test group (n = 11), a VEGF-coated collagen matrix was applied locally around the osteotomy site. After 10 days of limb shortening, gradual distraction of 0.5 mm per 12 hours was performed to restore the original length. Muscle force was measured before trauma and on every fifth day after trauma. Forty days after shortening we euthanized the animals and histologically determined the percentage of connective and muscle tissue.

Results

Recovery of preinjury muscle strength was greater in the VEGF group (2.4 N; 73%) when compared with the control (1.8 N; 53%) with less connective and more muscle tissue in the VEGF group. The recovery of force was related to the percentage of connective tissue versus muscle fibers.

Conclusions

Local application of VEGF may improve restoration of muscle force by reducing connective tissue and increasing the relative amount of muscle fibers.

Clinical Relevance

VEGF may be useful to improve skeletal muscle repair by modulating muscle tissue regeneration and fibrosis reduction after acute trauma.     

Systemic treatment with pulsed electromagnetic fields do not affect bone microarchitecture in osteoporotic rats

Purpose

Pulsed electromagnetic fields (PEMF) are currently used in the treatment of spinal fusions and non-unions. There are indications that PEMF might also be effective in the treatment of osteoporosis. In this study we examined whether whole-body PEMF treatment affects the bone microarchitecture in an osteoporotic rat model.

Methods

Twenty-week-old female rats were ovariectomised (n = 20). Four different PEMF treatment protocols based on previous experimental studies and based on clinically used PEMF signals were examined (2 h/day, 5 days/week). A control group did not receive PEMF. At zero, three and six weeks cancellous and cortical bone architectural changes at the proximal tibia were evaluated using in vivo microCT scanning.

Results

PEMF treatment did not induce any changes in cancellous or cortical bone compared to untreated controls.

Conclusions

Although previous studies have shown strong effects of PEMF in osteoporosis we were unable to demonstrate this in any of the treatment protocols. Using in vivo microCT scanning we were able to identify small bone changes in time. Subtle differences in the experimental set-up might explain the differences in study outcomes in the literature. Since PEMF treatment is safe, future experimental studies on the effect of PEMF on bone can better be performed directly on humans, eliminating the potential translation issues between animals and humans. In this study we found no support for the use of PEMF in the treatment of osteoporosis.