Splenic contraction and cardiovascular responses are augmented during apnea compared to rebreathing in humans

The spleen contracts during apnea, releasing stored erythrocytes, thereby increasing systemic hemoglobin concentration (Hb). We compared apnea and rebreathing periods, of equal sub-maximal duration (mean 137 s; SD 30), in eighteen subjects to evaluate whether respiratory arrest or hypoxic and hypercapnic chemoreceptor stimulation is the primary elicitor of splenic contraction and cardiovascular responses during apnea. Spleen volume, Hb, cardiovascular variables, arterial (SaO₂), cerebral (ScO₂), and deltoid muscle oxygen saturations (SmO₂) were recorded during the trials and end-tidal partial pressure of oxygen (P_ETO₂) and carbon dioxide (P_ETCO₂) were measured before and after maneuvers. The spleen volume was smaller after apnea, 213 (89) mL, than after rebreathing, 239 (95) mL, corresponding to relative reductions from control by 20.8 (17.8) % and 11.6 (8.0) %, respectively. The Hb increased 2.4 (2.0) % during apnea, while there was no significant change with rebreathing. The cardiovascular responses, including bradycardia, decrease in cardiac output, and increase in total peripheral resistance, were augmented during apnea compared to during rebreathing. The P_ETO₂ was higher, and the P_ETCO₂ was lower, after apnea compared to after rebreathing. The ScO₂ was maintained during maneuvers. The SaO₂ decreased 3.8 (3.1) % during apnea, and even more, 5.4 (4.4) %, during rebreathing, while the SmO₂ decreased less during rebreathing, 2.2 (2.8) %, than during apnea, 8.3 (6.2) %. We conclude that respiratory arrest per se is an important stimulus for splenic contraction and Hb increase during apnea, as well as an important initiating factor for the apnea-associated cardiovascular responses and their oxygen-conserving effects.

Visualisation of individual dopants in a conjugated polymer: sub-nanometre 3D spatial distribution and correlation with electrical properties

While molecular doping is ubiquitous in all branches of organic electronics, little is known about the spatial distribution of dopants, especially at molecular length scales. Moreover, a homogeneous distribution is often assumed when simulating transport properties of these materials, even though the distribution is expected to be inhomogeneous. In this study, electron tomography is used to determine the position of individual molybdenum dithiolene complexes and their three-dimensional distribution in a semiconducting polymer at the sub-nanometre scale. A heterogeneous distribution is observed, the characteristics of which depend on the dopant concentration. At 5 mol% of the molybdenum dithiolene complex, the majority of the dopant species are present as isolated molecules or small clusters up to five molecules. At 20 mol% dopant concentration and higher, the dopant species form larger nanoclusters with elongated shapes. Even in case of these larger clusters, each individual dopant species is still in contact with the surrounding polymer. The electrical conductivity first strongly increases with dopant concentration and then slightly decreases for the most highly doped samples, even though no large aggregates can be observed. The decreased conductivity is instead attributed to the increased energetic disorder and lower probability of electron transfer that originates from the increased size and size variation in dopant clusters. This study highlights the importance of detailed information concerning the dopant spatial distribution at the sub-nanometre scale in three dimensions within the organic semiconductor host. The information acquired using electron tomography may facilitate more accurate simulations of charge transport in doped organic semiconductors.

Toughening of a Soft Polar Polythiophene through Copolymerization with Hard Urethane Segments

Polar polythiophenes with oligoethylene glycol side chains are exceedingly soft materials. A low glass transition temperature and low degree of crystallinity prevents their use as a bulk material. The synthesis of a copolymer comprising 1) soft polythiophene blocks with tetraethylene glycol side chains, and 2) hard urethane segments is reported. The molecular design is contrary to that of other semiconductor-insulator copolymers, which typically combine a soft nonconjugated spacer with hard conjugated segments. Copolymerization of polar polythiophenes and urethane segments results in a ductile material that can be used as a free-standing solid. The copolymer displays a storage modulus of 25 MPa at room temperature, elongation at break of 95%, and a reduced degree of swelling due to hydrogen bonding. Both chemical doping and electrochemical oxidation reveal that the introduction of urethane segments does not unduly reduce the hole charge-carrier mobility and ability to take up charge. Further, stable operation is observed when the copolymer is used as the active layer of organic electrochemical transistors.

Ground-state electron transfer in all-polymer donor-acceptor heterojunctions

Doping of organic semiconductors is crucial for the operation of organic (opto)electronic and electrochemical devices. Typically, this is achieved by adding heterogeneous dopant molecules to the polymer bulk, often resulting in poor stability and performance due to dopant sublimation or aggregation. In small-molecule donor-acceptor systems, charge transfer can yield high and stable electrical conductivities, an approach not yet explored in all-conjugated polymer systems. Here, we report ground-state electron transfer in all-polymer donor-acceptor heterojunctions. Combining low-ionization-energy polymers with high-electron-affinity counterparts yields conducting interfaces with resistivity values five to six orders of magnitude lower than the separate single-layer polymers. The large decrease in resistivity originates from two parallel quasi-two-dimensional electron and hole distributions reaching a concentration of ∼10¹³ cm^-2. Furthermore, we transfer the concept to three-dimensional bulk heterojunctions, displaying exceptional thermal stability due to the absence of molecular dopants. Our findings hold promise for electro-active composites of potential use in, for example, thermoelectrics and wearable electronics.

Management of incidental gallbladder cancer in a national cohort

Background

Incidental gallbladder cancer is a rare event, and its prognosis is largely affected by the tumour stage and treatment. The aim of this study was to analyse the management, treatment and survival of patients with incidental gallbladder cancer in a national cohort over a decade.

Methods

Patients were identified through the Swedish Registry of Gallstone Surgery (GallRiks). Data were cross-linked to the national registry for liver surgery (SweLiv) and the Cancer Registry. Medical records were collected if registry data were missing. Survival was measured as disease-specific survival. The study was divided into two intervals (2007–2011 and 2012–2016) to evaluate changes over time.

Results

In total, 249 patients were identified with incidental gallbladder cancer, of whom 92 (36·9 per cent) underwent re-resection with curative intent. For patients with pT2 and pT3 disease, median disease-specific survival improved after re-resection (12·4 versus 44·1 months for pT2, and 9·7 versus 23·0 months for pT3). Residual disease was present in 53 per cent of patients with pT2 tumours who underwent re-resection; these patients had a median disease-specific survival of 32·2 months, whereas the median was not reached in patients without residual disease. Median survival increased by 11 months for all patients between the early and late periods (P = 0·030).

Conclusion

Re-resection of pT2 and pT3 incidental gallbladder cancer was associated with improved survival, but survival was impaired when residual disease was present. A higher re-resection rate and more R0 resections in the later time period may have been associated with improved survival.

Lignin-first biomass fractionation using a hybrid organosolv - Steam explosion pretreatment technology improves the saccharification and fermentability of spruce biomass

For a transition to a sustainable society, fuels, chemicals, and materials should be produced from renewable resources. Lignocellulosic biomass constitutes an abundant and renewable feedstock; however, its successful application in a biorefinery requires efficient fractionation into its components; cellulose, hemicellulose and lignin. Here, we demonstrate that a newly established hybrid organosolv - steam explosion pretreatment can effectively fractionate spruce biomass to yield pretreated solids with high cellulose (72% w/w) and low lignin (delignification up to 79.4% w/w) content. The cellulose-rich pretreated solids present high saccharification yields (up to 61% w/w) making them ideal for subsequent bioconversion processes. Moreover, under high-gravity conditions (22% w/w) we obtained an ethanol titer of 61.7 g/L, the highest so far reported for spruce biomass. Finally, the obtained high-purity lignin is suitable for various advanced applications. In conclusion, hybrid organosolv pretreatment could offer a closed-loop biorefinery while simultaneously adding value to all biomass components.

A novel hybrid organosolv: steam explosion method for the efficient fractionation and pretreatment of birch biomass

BACKGROUND

The main role of pretreatment is to reduce the natural biomass recalcitrance and thus enhance saccharification yield. A further prerequisite for efficient utilization of all biomass components is their efficient fractionation into well-defined process streams. Currently available pretreatment methods only partially fulfill these criteria. Steam explosion, for example, excels as a pretreatment method but has limited potential for fractionation, whereas organosolv is excellent for delignification but offers poor biomass deconstruction.

RESULTS

In this article, a hybrid method combining the cooking and fractionation of conventional organosolv pretreatment with the implementation of an explosive discharge of the cooking mixture at the end of pretreatment was developed. The effects of various pretreatment parameters (ethanol content, duration, and addition of sulfuric acid) were evaluated. Pretreatment of birch at 200 °C with 60% v/v ethanol and 1% w/w_biomass H₂SO₄ was proven to be the most efficient pretreatment condition yielding pretreated solids with 77.9% w/w cellulose, 8.9% w/w hemicellulose, and 7.0 w/w lignin content. Under these conditions, high delignification of 86.2% was demonstrated. The recovered lignin was of high purity, with cellulose and hemicellulose contents not exceeding 0.31 and 3.25% w/w, respectively, and ash to be < 0.17% w/w in all cases, making it suitable for various applications. The pretreated solids presented high saccharification yields, reaching 68% at low enzyme load (6 FPU/g) and complete saccharification at high enzyme load (22.5 FPU/g). Finally, simultaneous saccharification and fermentation (SSF) at 20% w/w solids yielded an ethanol titer of 80 g/L after 192 h, corresponding to 90% of the theoretical maximum.

CONCLUSIONS

The novel hybrid method developed in this study allowed for the efficient fractionation of birch biomass and production of pretreated solids with high cellulose and low lignin contents. Moreover, the explosive discharge at the end of pretreatment had a positive effect on enzymatic saccharification, resulting in high hydrolyzability of the pretreated solids and elevated ethanol titers in the following high-gravity SSF. To the best of our knowledge, the ethanol concentration obtained with this method is the highest so far for birch biomass.

Completeness and correctness of cholecystectomy data in a national register--GallRiks

BACKGROUND AND AIMS

To validate the Swedish Register for Gallstone Surgery and Endoscopic Retrograde Cholangiopancreatography (GallRiks) concerning completeness and correctness of entered data for cholecystectomies and evaluating the effect of repeated audits. It is crucial for any register to obtain a high accuracy in order to be a credible and reliable source for quality evaluation, research, and development.

MATERIALS AND METHODS

Completeness was determined by cross-matching the register with the Swedish National Patient Register. Completeness and overall correctness were assessed by comparing registered data to medical records. Correctness for rare occasions, such as bile duct injuries, was evaluated by comparing with claims sent to the Swedish Patient Insurance.

RESULTS

Of 64,538 cholecystectomies, 82.9% of the operations were registered in GallRiks and the coverage increased over time. By random sample, 94,919 sets of data were available for comparison at the first and second audit and the entries were found to be correct in 97.2% and 98.2% cases, respectively. A 100% correctness for bile duct injuries (n = 40) was seen when the index-operation was registered in GallRiks.

CONCLUSION

GallRiks demonstrates high completeness, high correctness of entered data, and no indications of failure to report serious adverse events. Repeated audits increased the quality of registered data. GallRiks may be used for clinical evaluation on local and national level and the database enables scientific studies to be performed.

Outcomes of antibiotic prophylaxis in acute cholecystectomy in a population-based gallstone surgery registry

Background

The aim of this study was to assess the effect of antibiotic prophylaxis (AP) on postoperative infections in acute cholecystectomy.

Methods

The study was based on acute cholecystectomies registered in the nationwide Swedish Register for Gallstone Surgery and Endoscopic Retrograde Cholangiopancreatography (GallRiks) between 2006 and 2010. The association between AP and the risk of postoperative infectious complications was tested in a multivariable regression analysis, with stepwise addition of age, sex, duration of operation, indication for surgery, surgical approach (laparoscopic versus open) and American Society of Anesthesiologists (ASA) fitness grade as co-variables. Postoperative infections requiring antibiotic treatment and postoperative abscesses were defined as outcome measures.

Results

AP was given to 9549 (68·6 per cent) of 13 911 patients. Postoperative infections requiring antibiotic treatment occurred following 1070 procedures (7·7 per cent), including 805 patients (8·4 per cent) who received AP (P &lt; 0·001 versus patients without AP). Postoperative abscesses developed after 273 procedures (2·0 per cent), including 208 patients (2·2 per cent) who received AP (P = 0·007). In univariable analysis, the odds ratio for development of infectious complications necessitating treatment with antibiotics was 1·42 (95 per cent confidence interval 1·23 to 1·64) for those who received APversus those who did not, and for postoperative abscesses it was 1·47 (1·11 to 1·95). In multivariable analysis, adjusting for confounders, the odds ratios were 0·93 (0·79 to 1·10) and 0·88 (0·64 to 1·21) respectively.

Conclusion

The present study suggests that AP provides no benefit in acute cholecystectomy.

Clinical efficacy and safety of a water-soluble micellar paclitaxel (Paccal Vet) in canine mastocytomas

OBJECTIVE

To determine the clinical efficacy and safety of a cremophor-free formulation of paclitaxel (Paccal Vet, Oasmia Pharmaceuticals) in dogs with mast cell tumours.

METHODS

Paccal Vet was administered at a median dose of 145 (range, 135 to 150) mg/m(2) intravenously once every 21 days for three cycles to 29 dogs with macroscopic grade 2 or 3 mast cell tumour. Efficacy was assessed by tumour response (Response Evaluation Criteria in Solid Tumours version 1.0) and performance status score. Progression-free survival, quality of life and safety/adverse events were also evaluated. Clinical safety was assessed by clinicopathological analyses and recording of adverse events.

RESULTS

Complete or partial response was observed in 59% of dogs. Performance status score remained constant or improved for 20 dogs and decreased by one grade for 9 dogs. Median time to progression was 247 (range, 42 to 268) days. Expected, transient frequently subclinical adverse events (primarily grade 3/4 neutropenia and grade 1/2 leukopenia) were observed in the majority of dogs. Nine dogs were euthanased and one dog died due to disease progression.

CLINICAL SIGNIFICANCE

Paccal Vet appears to be a clinically safe and effective treatment for canine mast cell tumours. Further controlled confirmatory investigation is warranted.

Risk of bleeding associated with use of systemic thromboembolic prophylaxis during laparoscopic cholecystectomy

BACKGROUND

The extent to which systemic perioperative thromboembolic prophylaxis affects peroperative and postoperative bleeding during cholecystectomy is not known. This article reports on risk of bleeding in a national cohort of cholecystectomies.

METHODS

All cholecystectomies registered in the Swedish Register of Gallstone Surgery and Endoscopic Retrograde Cholangiopancreatography (GallRiks) between 2005 and 2010 were reviewed. Peroperative bleeding was defined as bleeding that could not be controlled by standard surgical techniques, necessitated conversion to an open procedure or required peroperative blood transfusion. Postoperative bleeding was defined as bleeding that necessitated reoperation, transfusion or a prolonged hospital stay. Risk estimates were performed using univariable and multiple logistic regression, and reported as odds ratios (ORs).

RESULTS

A total of 51 621 procedures were registered in GallRiks. Some 48 010 patients were included in the analyses, of whom 21 259 (44·3 per cent) received thromboembolic prophylaxis. Peroperative bleeding complications occurred in 400 (1·9 per cent) and postoperative bleeding in 296 (1·4 per cent) given thromboembolic prophylaxis, compared with 189 (0·7 per cent) and 195 (0·7 per cent) respectively without thromboprophylaxis. After adjusting for age, sex, indication for surgery, American Society of Anesthesiologists grade, mode of admission, operative approach, duration of surgery and hospital volume, the OR for peroperative or postoperative bleeding complications in the group receiving prophylaxis was 1·35 (95 per cent confidence interval 1·17 to 1·55). However, in a subgroup analysis the risk was increased in laparoscopic surgery only. At 30-day follow-up, a total of 74 patients (0·2 per cent) had developed postoperative thromboembolism, 43 (0·2 per cent) of those who received thromboembolic prophylaxis compared with 31 (0·1 per cent) of those who did not.

CONCLUSION

Thromboprophylaxis in patients undergoing laparoscopic cholecystectomy increased the risk of bleeding, but the occurrence of thromboembolic events was not significantly reduced. Identification of high- and low-risk patients is needed to guide clinical decisions regarding medical thromboprophylaxis.

Fate of excitations in conjugated polymers: single-molecule spectroscopy reveals nonemissive "dark" regions in MEH-PPV individual chains

Single chains of the conjugated polymer MEH-PPV (poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene)) were studied with wide-field fluorescence microscopy (dispersion in inert polymer matrices) and with fluorescence correlation spectroscopy (chloroform solution). The fluorescence yield of individual molecules in matrices was found to be 1-2 orders of magnitude lower than that in solution and it decreased substantially with increasing chain length. It suggests that isolation of MEH-PPV molecules in polymer matrices creates favorable conditions for photogeneration of nonemissive primary excited states.