T2 mapping with magnetization‐prepared 3D TSE based on a modified BIR‐4 T2 preparation

The purpose of this work was to investigate the performance of the modified BIR‐4 T₂ preparation for T₂ mapping and propose a method to remove T₂ quantification errors in the presence of large B₁ and B₀ offsets. The theoretical investigation of the magnetization evolution during the T₂ preparation in the presence of B₁ and B₀ offsets showed deviations from a mono‐exponential T₂ decay (two parameter fit). A three parameter fit was used to improve T₂ accuracy. Furthermore, a two parameter fit with an additional saturation preparation scan was proposed to improve T₂ accuracy and precision. These three fitting methods were compared based on simulations, phantom measurements and an in vivo healthy volunteer study of the neck musculature using a 3D TSE readout. The results based upon the pure two parameter fit overestimated T₂ in regions with high B₀ offsets (up to 40% in phantoms). The three parameter fit T₂ values were robust to B₀ offsets but with higher standard deviation (up to 40% in simulations). The two parameter fit with the saturation preparation yielded high robustness towards B₀ offsets with a noise performance comparable to that of the two parameter fit. In the volunteer study the T₂ values obtained by the pure two parameter fit showed a dependence on the field inhomogeneities, whereas the T₂ values from the proposed fitting approach were shown to be insensitive to B₀ offsets. The proposed method enabled accurate and precise T₂ mapping in the presence of large B₁ and B₀ offsets.     

Cutaneous perforators of the peroneal artery: Cadaveric study with implications in the design of the osteocutaneous free fibular flap

Bilateral dissection of 15 formalin embalmed cadaver legs was performed in order to study the anatomic pattern of the peroneal artery (PA) and its cutaneous perforating vessels (CB). The total number of CB from the PA was 125 or an average of 4.17 branches per leg. CB were distributed in the superoinferior axis between 18.25 and 84.25% of the length of the fibula and their average length was 5 ± 1.8 cm. 86/125 (68.8%) of the CB were classified as myocutaneous branches (MC) that penetrated muscle before reaching the skin, whereas 39/125 (31.2%) were septocutaneous branches (SC) that passed through the intermuscular septum. The mean distance between the posterior border of the fibula and the site where the perforators emerged was 1.88 ± 0.79 cm for the SC and 1.21 ± 0.87 cm for the MC. These anatomic findings should encourage the surgeon to design the skin paddle in the boundary between the middle and the distal third of the fibular length about 2 cm behind the posterior fibular border on the posterolateral leg, where the number of CB is maximal. Clin. Anat. 22:826–833, 2009. © 2009 Wiley‐Liss, Inc.     

Early benefit from structured care with atorvastatin in patients with coronary heart disease and diabetes mellitus

This is a prospective evaluation of the effect of structured care of dyslipidemia with atorvastatin (strict implementation of guidelines) versus usual care (physician's standard of care) on morbidity and mortality of patients with coronary heart disease (CHD) and diabetes mellitus (DM). From 1600 consecutive CHD patients randomized to either form of care in the GREek Atorvastatin and CHD Evaluation Study (GREACE), 313 had DM: 161 in the structured care arm and 152 in the usual care arm. All patients were followed up for a mean of 3 years. In the structured care group, patients were treated with atorvastatin to achieve the National Cholesterol Education Program (NCEP) low-density lipoprotein cholesterol (LDL-C) treatment goal of <2.6 mmol/L (100 mg/dL). Primary endpoints were all-cause and coronary mortality, coronary morbidity, and stroke. In the structured care group, 156 patients (97%) were taking atorvastatin (10-80 mg/day; mean, 23.7 mg/day) throughout the study; the NCEP LDL-C treatment goal was reached by 150 patients (93%). Only 17% (n=26) of the usual care patients were on long-term hypolipidemic drug treatment and 4% (n=6) reached the NCEP LDL-C treatment goal. During the study, 46 of 152 (30.3%) CHD patients with DM on usual care experienced a major vascular event or died versus 20 of 161 (12.5%) patients on structured care; relative risk reduction (RRR) 58%, p<0.0001. RRR for all-cause mortality was 52%, p=0.049; coronary mortality 62%, p=0.042; coronary morbidity 59%, p<0.002; and stroke 68%, p=0.046. Event rate curves started deviating from the sixth treatment month and the RRR was almost 60% by the 12th month. RRRs remained at that level until the end of the study, when they became statistically significant. The cost/life-year gained with structured care was estimated at 6200 US dollars. In CHD patients with DM, structured care of dyslipidemia with atorvastatin to achieve the NCEP LDL-C treatment goal, reduces all-cause and coronary mortality, coronary morbidity, and stroke by more than one half within a 3-year period, in comparison to usual care. Clinical benefit is manifested as early as the sixth month of treatment.     

Coronary and peripheral blood flow changes following biventricular pacing and their relation to heart failure improvement.

AIMS: To study the effect of cardiac resynchronization therapy (CRT) on coronary and peripheral arterial circulation and to assess whether their changes are related to the improvement in patients' functional capacity and prognostically important biochemical markers. METHODS AND RESULTS: Twenty-five patients were studied (New York Heart Association classes III and IV, left ventricular ejection fraction <35%, QRS>120 ms, mean age 66 +/- 2.1 years). Coronary blood flow (CBF), forearm blood flow (FBF), and their reserve were measured by transoesophageal echocardiography (in cm/s) and venous occlusion plethysmography (in mL/100 mL/min) at baseline and following 3 months of CRT. N-terminal-pro-brain natriuretic peptide (Nt-pro-BNP) and serum adhesion molecules, sICAM-1 and sVCAM-1 levels were also assessed. CRT induced a non-significant increase in resting CBF (baseline vs. CRT: 52.1 +/- 5.5 vs. 58.2 +/- 3.6, P: NS), whereas hyperaemic CBF was increased by CRT (baseline vs. CRT: 67.8 +/- 6.8 vs. 79.8 +/- 6.2, P < 0.05). Significant increases were observed in resting FBF (baseline vs. CRT: 1.6 +/- 0.2 vs. 2.6 +/- 0.2, P < 0.05) and hyperaemic FBF (baseline vs. CRT: 2.1 +/- 0.2 vs. 3.2 +/- 0.3, P < 0.05). The per cent difference in hyperaemic FBF was related to the per cent change in Nt-pro-BNP (r = -0.71, P < 0.05) and the per cent improvement in exercise duration (r = 0.80, P < 0.05). CONCLUSION: CRT induces favourable changes in coronary and peripheral arterial function. Changes in peripheral blood flow are related to patients' improvement and may be prognostically significant.     

Rapid dark aging of biomass burning as an overlooked source of oxidized organic aerosol

Oxidized organic aerosol (OOA) is a major component of ambient particulate matter, substantially impacting climate, human health, and ecosystems. OOA is readily produced in the presence of sunlight, and requires days of photooxidation to reach the levels observed in the atmosphere. High concentrations of OOA are thus expected in the summer; however, our current mechanistic understanding fails to explain elevated OOA during wintertime periods of low photochemical activity that coincide with periods of intense biomass burning. As a result, atmospheric models underpredict OOA concentrations by a factor of 3 to 5. Here we show that fresh emissions from biomass burning exposed to NO₂ and O₃ (precursors to the NO₃ radical) rapidly form OOA in the laboratory over a few hours and without any sunlight. The extent of oxidation is sensitive to relative humidity. The resulting OOA chemical composition is consistent with the observed OOA in field studies in major urban areas. Additionally, this dark chemical processing leads to significant enhancements in secondary nitrate aerosol, of which 50 to 60% is estimated to be organic. Simulations that include this understanding of dark chemical processing show that over 70% of organic aerosol from biomass burning is substantially influenced by dark oxidation. This rapid and extensive dark oxidation elevates the importance of nocturnal chemistry and biomass burning as a global source of OOA.

Highly oxidized organic aerosol (OOA) is a dominant component of particulate matter air pollution globally (1–3); however, sources of OOA remain uncertain, limiting the ability of models to accurately represent OOA and thus predict the associated climate, ecosystem, and health implications (4, 5). The current conceptual model of OOA formation suggests that anthropogenic OOA predominantly originates from the oxidation of volatile (VOCs), intermediate volatility (IVOCs), and semivolatile (SVOCs) organic compounds by the OH radical, resulting in lower-volatility products that condense to the particle phase (6). As the OH radical is formed through photolysis and has a very short atmospheric lifetime [less than a second (7)], this oxidation mechanism only occurs in the presence of sunlight. Further, the time scale for OOA formation through oxidation with OH in models is on the order of a few days (8). While this understanding is sufficient in explaining OOA concentrations in summer or periods with high solar radiation, atmospheric models fail to reproduce the observed concentration of OOA in the ambient atmosphere during winter and low-light conditions (9, 10). Fountoukis et al. (9) found simulated OOA concentrations significantly underestimated in wintertime Paris. Tsimpidi et al. (10) also reported an underprediction of simulated OOA globally in winter, suggesting missing sources of both primary OA (POA) and secondary formation pathways. This underproduction suggests a possible overlooked conversion pathway of organic vapors or particles to OOA that is not accounted for in current chemical transport and climate models.As stricter controls on fossil fuel combustion are implemented, residential biomass burning (BB) as a source of heating or cooking is becoming an increasingly important source of OA in urban environments (1, 11, 12). Further, increasing rates of wildfires from climate change are increasing the frequency of smoke-impacted days in urban areas (12–14). BB emissions include high concentrations of POA, SVOCs, IVOCs, and VOCs (15, 16), thus making BB a key source of OOA. Previous research has focused on quantifying the concentration of OOA formed through photochemical oxidation reactions (i.e., OH) with BB emissions (17, 18). However, oxidation of BB emissions in low or no sunlight is less well understood and is not included in chemical transport models. As opposed to OH, the NO₃ radical is formed through reactions with NO₂ and O₃ and is rapidly lost in the presence of sunlight (19). Thus, the NO₃ radical is only available in significant concentrations at night or other low-light conditions (20, 21). Previous research has established that biogenic VOCs may undergo oxidation at night when mixed with anthropogenic emissions containing NO₂ and O₃ (19, 22–27). There have been only a few studies that consider that nighttime oxidation of residential wood combustion may proceed through similar pathways (28–31); however, the magnitude and relevance to observed OOA in the ambient atmosphere has not yet been established. By combining laboratory experiments and ambient observations to inform a chemical transport model, we present strong evidence that nighttime oxidation of BB plumes (proceeding through reactions with O₃ and the NO₃ radical) is an important source of OOA.     

Prophylactic total gastrectomy in the management of hereditary tumor syndromes

Purpose

Germline mutations in several genes confer a relevant lifetime risk of gastric cancer. In this context, an increasing involvement of a surgeon can be seen, mainly with the question of performing a prophylactic operation.

Methods

Patients with hereditary tumor syndromes predisposing for gastric cancer who received care leading to prophylactic total gastrectomy in our Center for Hereditary Tumor Syndromes were analyzed. For each patient, the multidisciplinary decision-making process, the perioperative course, and the histopathologic findings were assessed. Short-term morbidity was evaluated based on the medical reports.

Results

The analysis includes nine patients (six female, three male) with a median age of 41.6 (range 23–60) years. Indication for prophylactic total gastrectomy was based on family history and genetic analysis (eight patients with a germline mutation of the CDH1 gene and one patient with a SMAD4 mutation). Removal of the entire gastric mucosa was documented intraoperatively by fresh frozen section examination. Extended (DII) lymphadenectomy was performed in four patients. Histopathologic examination of gastrectomy specimens revealed six patients (6/9, 67 %) with multifocal signet ring cell carcinomas. In our series, prophylactic total gastrectomy was a safe procedure without mortality and low morbidity.

Conclusions

Patients with hereditary syndromes predisposing for gastric cancer should be evaluated for this curative procedure in a specialized center. Further research is necessary, and the implementation of nationwide registers including patients with prophylactic gastrointestinal operations due to hereditary tumor syndrome is advisable.

     

Hyperlipidemia prevents the expected reduction of myocardial ischemia on repeated balloon inflations during angioplasty

BACKGROUND: Controversy exists regarding inhibition of ischemic preconditioning in hyperlipidemic animals. In this study, we tested the hypothesis that hyperlipidemia inhibits the normal reduction of myocardial ischemia on repeated balloon inflations (BIs) during angioplasty. METHODS: We studied 33 patients undergoing coronary angioplasty. All underwent a minimum of three BIs. Patients were grouped according to the following plasma cholesterol levels: 13 patients had total cholesterol levels < 200 mg/dL (the normal cholesterol group); and 20 patients had total cholesterol levels > or = 200 mg/dL (the elevated cholesterol group). Surface ST-segment elevations were recorded at the end of each BI. RESULTS: In the normal cholesterol group, the mean (+/- SD) ST-segment elevation decreased from 0.21 +/- 0.15 mV during the first BI to 0.11 +/- 0.11 mV during the third BI (p < 0.05). In the elevated cholesterol group, the respective decrease was from 0.18 +/- 0.16 to 0.14 +/- 0.15 mV (p = not significant) [between-group comparisons: F = 3.97; p = 0.02]. The decrease in ST-segment elevation was correlated with the total cholesterol levels (r = -0.48; p = 0.005), the low-density lipoprotein (LDL) cholesterol levels (r = -0.50; p = 0.003), and the high-density lipoprotein/LDL levels (r = 0.44; p = 0.01). CONCLUSION: Hyperlipidemia prevents the normal reduction of myocardial ischemia on repeated BIs during angioplasty. This leads to the clinical implication that reduction of cholesterol plasma levels, apart from its other known benefits, could also have a beneficial effect on cardioprotection.