Consecutive hydroconversion of acetic acid (AA) to ethanol was compared over monometallic and novel bimetallic (containing In as guest metal) catalysts on alumina and silica supports (inter alia ...highly ordered SBA-15) of different porosity and pore structure.
The transformation was studied in a fixed bed, flow-through reactor in the temperature range of 220–380°C using hydrogen flow at 21 bar total pressure. AA hydroconversion activity of Cu and Pt catalysts and the yield of selectively produced alcohol were increased drastically by applying SBA-15 as highly ordered, mesoporous silica support instead of alumina. The most active nickel catalysts do not allow the selective addition of hydrogen to carbon-oxygen bonds independently of supports producing mainly CH4; however, indium doping can completely eliminate the hydrodecarbonylation activity as found in earlier studies. The textural properties of studied silica supports of various textures such as SBA-15, CAB-O-SIL, and Grace Sylobead have a profound impact on the catalytic performance of Ni and Ni2In particles.
Background and purpose
In its initial stages, Guillain–Barré syndrome (GBS) is difficult to identify, because diagnostic criteria may not always be fulfilled. With this retrospective study, we wanted ...to identify the most common electrophysiological abnormalities seen on neurophysiological examination of GBS patients and its variants in the early phases.
Methods
We reviewed the clinical records of patients admitted to our Neurology Unit with a confirmed diagnosis of GBS. The study sample was divided in two subgroups according to whether the neurophysiological examination was performed: within 7 days (very early group) or within 7–15 days (early group). H reflex, F waves, and motor and sensory conduction parameters were judged abnormal if they were outside the normal range for at least two nerves. We evaluated neurophysiological findings in Miller–Fisher syndrome (MFS) separately.
Results
The study sample comprised 36 patients. In GBS, the most frequent abnormal neurophysiological parameter was the bilateral absence of the H reflex, followed by F wave abnormalities. Motor conduction parameters were altered in less than 50% of patients, and even less common were sensory nerve action potential reduction and the "sural‐sparing" pattern. In MFS, H reflex was absent bilaterally in 100% of patients, followed by a predominant peripheral sensory involvement, whereas motor conduction parameters were frequently normal.
Conclusions
Bilateral absence of the H reflex is the most sensitive parameter in early diagnosis of GBS and its variants.
Electrodiagnostic findings in GBS and MFS patients: percentage of patients with abnormal results in at least two nerves. When patients were excluded due to the lack of CMAPs, SNAPs or normal sural nerve SNAP, frequencies are calculated based on the number of patients reported in brackets. MCV: motor conduction velocity. DML: distal motor latency. CMAP Dur: compound motor action potential duration. CMAP A: compound motor action potential amplitude. SNAP A: sensory nerve action potential amplitude. SCV: sensory conduction velocity.
Background
Cerebellar mutism can occur in a third of children undergoing cerebellar resections. Recent evidence proposes it may arise from uni- or bilateral damage of cerebellar efferents to the ...cortex along the cerebello-dento-thalamo-cortical pathway. At present, no neurophysiological procedure is available to monitor this pathway intraoperatively. Here, we specifically aimed at filling this gap.
Methods
We assessed 10 patients undergoing posterior fossa surgery using a conditioning-test stimulus paradigm. Electrical conditioning stimuli (cStim) were delivered to the exposed cerebellar cortex at interstimulus intervals (ISIs) of 8–24 ms prior to transcranial electric stimulation of the motor cortex, which served as test stimulus (tStim). The variation of motor-evoked potentials (MEP) to cStim + tStim compared with tStim alone was taken as a measure of cerebello-cortical connectivity.
Results
cStim alone did not produce any MEP. cStim preceding tStim produced a significant inhibition at 8 ms (
p
< 0.0001) compared with other ISIs when applied to the lobules IV-V-VI in the anterior cerebellum and the lobule VIIB in the posterior cerebellum. Mixed effects of decrease and increase in MEP amplitude were observed in these areas for longer ISIs.
Conclusions
The inhibition exerted by cStim at 8 ms on the motor cortex excitability is likely to be the product of activity along the cerebello-dento-thalamo-cortical pathway. We show that monitoring efferent cerebellar pathways to the motor cortex is feasible in intraoperative settings. This study has promising implications for pediatric posterior fossa surgery with the aim to preserve the cerebello-cortical pathways and thus prevent cerebellar mutism.
Introduction
Nerve cross‐sectional area (CSA) is larger than normal in Charcot–Marie–Tooth disease 1A (CMT1A), although to a variable extent. We explored whether CSA is correlated with CMT clinical ...severity measured with neuropathy score version 2 (CMTNS2) and its examination subscore (CMTES2) in CMT1A.
Methods
We assessed 56 patients with CMT1A (42 families). They underwent nerve conduction study (NCS) and nerve high‐resolution ultrasound (HRUS) of the left median, ulnar, and fibular nerves.
Results
Univariate analysis showed NCS and HRUS variables to be significantly correlated with CMTNS2 and CMTES2 and with each other. Multivariate analysis showed that ulnar motor nerve conduction velocity (β: −0.19) and fibular compound muscle action potential amplitude (−1.50) significantly influenced CMTNS2 and that median forearm CSA significantly influenced CMTNS2 (β: 5.29) and CMTES2 (4.28).
Discussion
Nerve size is significantly associated with clinical scores in CMT1A, which suggests that it might represent a potential biomarker of CMT damage and progression.
•Nerve cross sectional area (CSA) is heterogenous across demyelinating CMTs.•Average nerve CSA is significantly enlarged in CMT1A vs. other demyelinating CMTs.•The large CSA spectrum in CMT1A may be ...related to its clinical variability.
Ulnar/median motor nerve conduction velocity (MNCV) is ≤38 m/s in demyelinating Charcot-Marie-Tooth disease (CMT). Previous nerve high resolution ultrasound (HRUS) studies explored demyelinating CMT assuming it as a homogeneous genetic/pathological entity or focused on CMT1A.
To explore the spectrum of nerve HRUS findings in demyelinating CMTs, we recruited patients with CMT1A (N = 44), CMT1B (N = 9), CMTX (N = 8) and CMT4C (N = 4). They underwent nerve conduction study (NCS) and HRUS of the median, ulnar, peroneal nerve, and the brachial plexus.
Median, ulnar and peroneal MNCV significantly differed across CMT subtypes. Cross sectional area (CSA) was markedly and diffusely enlarged at all sites, except entrapment ones, in CMT1A, while it was slightly enlarged or within normal range in the other CMTs. No significant right-to-left difference was found. Age had limited effect on CSA. CSAs of some CMT1A patients largely overlapped with those of other demyelinating CMTs. A combination of three median CSA measures could separate CMT1A from other demyelinating CMTs.
Nerve HRUS findings are heterogeneous in demyelinating CMTs.
Nerve HRUS may separate CMT1A from other demyelinating CMTs. The large demyelinating CMTs HRUS spectrum may be related to its pathophysiological variability.
Mivel a fosszilis energia- és szénforrások egyre nehezebben elérhetők, egyre nagyobb szükség van olyan technológiák fejlesztésére, melyekkel a megújuló szénforrások vegyi anyagokká, cseppfolyós vagy ...gázállapotú energiahordozókká alakíthatók. A jelentős mennyiségben rendelkezésre álló biomassza, többek között a különböző állati melléktermékek, mint a hús- és csontliszt (MBM) a folyékony üzemanyagok előállításának potenciális, megújuló alapanyagai lehetnek. A biomassza-átalakítás egyik előnyös módja a pirolízis, amellyel kondenzálható, cseppfolyós termékek, úgynevezett bio-olajok állíthatók elő. Az állati melléktermék eredetű bio-olajokat energetikai célú hasznosításukhoz finomítani kell, mivel általában magas nitrogén tartalmú, kémiailag instabilis, poláris, viszkózus, korrozív folyadékok, melyek a hagyományos szénhidrogén üzemanyagokat nem helyettesítik, azokkal nem elegyíthetők. A nyers bio-olajok átalakítása energiahordozókká olyan katalitikus eljárásokkal valósítható meg, mint a vízgőzös reformálás, hidrogénező finomítás, krakkolás, dekarboxilezés/ oligomerizáció és az észterezés. Annak ellenére, hogy a kőolajiparban léteznek katalitikus, hidrogénező, finomítási eljárások a különböző nyersanyagok heteroatom tartalmának eltávolítására, ezek a megoldások nem feltétlenül alkalmasak a bio-olajok hidrogénező finomítására, mivel ezek jelentősen eltérő koncentrációban és minőségben tartalmazhatnak heteroatom-tartalmú vegyületeket, mint a nyersolajok. A kőolajipari alapanyagoknak magas a S (max. 7%) és alacsony a N (kevesebb, mint 2%) tartalma, s ezek a heteroatomok főleg aromás, heterociklusos vegyületekben vannak jelen. Ezzel ellentétben a csontlisztből származó pirolízisolaj ~10 % N és ~5 % O mellett S atomot elhanyagolható mennyiségben tartalmaz, a nitrogéntartalmú vegyületei pedig főleg alifás nitrilek, aminok és amidok. Katalitikus hidrogénező nitrogénmentesítéssel (HDN) a pirolízisolajok nitrogén heteroatomja eltávolítható, melynek során szénhidrogént és ammóniát kapunk. Ez utóbbi termékek az üzemanyag- és műtrágyagyártás hasznos alapanyagai lehetnek. A kőolajipari technológiákban átmenetifém-szulfid katalizátorokat használnak a hidrogénezési reakciókhoz, ahol a kén jelenlétének fontos szerepe van a katalizátor aktivitásának megőrzésében. A katalíziskutatásban az utóbbi évtized egyik jelentős tudományos felismerése, hogy a katalizátorok egy új csoportja, az átmenetifém-foszfidok is nagy aktivitást mutatnak a hidrogénező finomításban. Ezek közül kiemelkedőek a nikkel-foszfid (Ni2P) katalizátorok, melyek jóval aktívabbak a szimultán HDS és HDN reakciókban, mint a hagyományos szulfid katalizátorok, ugyanakkor kéntartalmú vegyületek jelenléte nélkül is megőrzik HDN aktivitásukat.Jelen munka állati eredetű biomasszák, elsősorban hús- és csontliszt pirolízisekor kapott, nagy nitrogéntartalmú (8-12 % N) bio-olajok átalakítására alkalmas technológia tudományos megalapozására irányult. Legfontosabb célunk a katalizátorszerkezet és -aktivitás közötti összefüggések feltárása és a HDN reakció mechanizmusának mélyebb megértése volt. Kísérleti munkánk során a bio-olajok alifás amin és nitril vegyületeire jellemző propil-amin és propionitril katalitikus HDN reakcióját vizsgáltuk. A vizsgálatokhoz oxidhordozós (szilikagél, szilikalit-1, SBA-15, laponit és szilícium-dioxiddal pillérezett laponit) Ni2P katalizátorokat, valamint szilikagél hordozós Ni referencia katalizátort állítottunk elő. A katalizátorok összetételét, szerkezetét és fizikai-kémiai tulajdonságait kémiai analízissel (ICP-OES), röntgendiffrakciós (XRD), transzmissziós elektronmikroszkópiai (TEM), hőmérséklet-programozott redukciós és deszorpciós (H2-TPR és H2-TPD), CO kemiszorpciós és N2 adszorpciós vizsgálatokkal jellemeztük. A katalitikus tulajdonságokat átáramlásos csőreaktorban, rendszerint 200-400°C hőmérséklet-tartományban, 30 bar nyomáson, 10-es H2/reaktáns mólarány mellett vizsgáltuk. A reakció során a katalizátorok felületén kialakuló, aktív és inaktív képződményeket operandodiffúz reflexiós, Fourier-transzformációs, infravörös spektroszkópiai (DRIFTS) módszerrel követtük nyomon.
Snake venom contains a variety of toxins with a range of biological activity, among these toxins cysteine-rich secreted proteins (CRISPs) can be found. The proteins of this family have masses of ...20-30 kDa and display homologous amino acid sequences containing 16 cysteine residues, forming eight disulfide bonds. Some of these proteins have been explored, characterized, and described in terms of their activity; however, little is known about their range of activities. A search for new antimicrobial molecules is ongoing, as the number of microbial strains resistant to available antibiotics is increasing. We identified antimicrobial activity in the secretion of Duvernoy's gland of the rear-fanged
. Fractions of this venom were subjected to reverse-phase high performance liquid chromatography and analyzed to determine their antimicrobial activity with a liquid broth inhibition assay. One of the fractions presented activity against a Gram-negative bacterium and a filamentous fungus. This fraction was analyzed with LC-MS/MS, and a protein of 24,848.8 Da was identified. Database searches allowed us to identify it as a CRISP due to the presence of some unique fragments in the molecule. We called it patagonin-CRISP, as the same protein in the venom of
.
had previously been characterized as having a different biological activity. Patagonin-CRISP presented activity at very low concentrations and showed no cytotoxic activity. This is the first time that antimicrobial activity has been identified for
.
venom or for a CRISP family protein.
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