Solubilities of palmitic and stearic fatty acids in supercritical carbon dioxide

The solubilities of two fatty acids, namely hexadecanoic acid (palmitic acid) and octadecanoic acid (stearic acid) in supercritical carbon dioxide (SCCO2), were determined at T = (328 and 338) K from 12.8 MPa to 22.6 MPa. Three models, namely a thermodynamic model based on the Peng-Robinson equation of state with Kwak and Mansoori mixing rules, a model based on dilute solution theory proposed by Mendez-Santiago and Teja and a new reformulated Chrastil equation model, were used to correlate the solubilities. In all the models, the correlation constants are temperature independent. All the models successfully correlated the experimental results for the solubilities of hexadecanoic acid within 3%.

Stereoselective Formal Total Synthesis of (-)-Didemniserinolipid B

A formal total synthesis of (-)-didemniserinolipid B from L-(+)-tartaric acid is presented. Key features of the synthesis include construction of the bicyclic acetal core from bisdimethyl amide of tartaric acid and further elaboration by cross metathesis.

Spectroscopy of tissue triglyceride composition : In vitro and in vivo studies

Lipid analysis is commonly performed by gas chromatography (GC) in laboratory conditions. Spectroscopic techniques, however, are non-destructive and can be implemented noninvasively in vivo. Excess fat (triglycerides) in visceral adipose tissue and liver is known predispose to metabolic abnormalities, collectively known as the metabolic syndrome. Insulin resistance is the likely cause with diets high in saturated fat known to impair insulin sensitivity. Tissue triglyceride composition has been used as marker of dietary intake but it can also be influenced by tissue specific handling of fatty acids. Recent studies have shown that adipocyte insulin sensitivity correlates positively with their saturated fat content, contradicting the common view of dietary effects. A better understanding of factors affecting tissue triglyceride composition is needed to provide further insights into tissue function in lipid metabolism. In this thesis two spectroscopic techniques were developed for in vitro and in vivo analysis of tissue triglyceride composition. In vitro studies (Study I) used infrared spectroscopy (FTIR), a fast and cost effective analytical technique well suited for multivariate analysis. Infrared spectra are characterized by peak overlap leading to poorly resolved absorbances and limited analytical performance. In vivo studies (Studies II, III and IV) used proton magnetic resonance spectroscopy (1H-MRS), an established non-invasive clinical method for measuring metabolites in vivo. 1H-MRS has been limited in its ability to analyze triglyceride composition due to poorly resolved resonances. Using an attenuated total reflection accessory, we were able to obtain pure triglyceride infrared spectra from adipose tissue biopsies. Using multivariate curve resolution (MCR), we were able to resolve the overlapping double bond absorbances of monounsaturated fat and polyunsaturated fat. MCR also resolved the isolated trans double bond and conjugated linoleic acids from an overlapping background absorbance. Using oil phantoms to study the effects of different fatty acid compositions on the echo time behaviour of triglycerides, it was concluded that the use of long echo times improved peak separation with T2 weighting having a negligible impact. It was also discovered that the echo time behaviour of the methyl resonance of omega-3 fats differed from other fats due to characteristic J-coupling. This novel insight could be used to detect omega-3 fats in human adipose tissue in vivo at very long echo times (TE = 470 and 540 ms). A comparison of 1H-MRS of adipose tissue in vivo and GC of adipose tissue biopsies in humans showed that long TE spectra resulted in improved peak fitting and better correlations with GC data. The study also showed that calculation of fatty acid fractions from 1H-MRS data is unreliable and should not be used. Omega-3 fatty acid content derived from long TE in vivo spectra (TE = 540 ms) correlated with total omega-3 fatty acid concentration measured by GC. The long TE protocol used for adipose tissue studies was subsequently extended to the analysis of liver fat composition. Respiratory triggering and long TE resulted in spectra with the olefinic and tissue water resonances resolved. Conversion of the derived unsaturation to double bond content per fatty acid showed that the results were in accordance with previously published gas chromatography data on liver fat composition. In patients with metabolic syndrome, liver fat was found to be more saturated than subcutaneous or visceral adipose tissue. The higher saturation observed in liver fat may be a result of a higher rate of de-novo-lipogenesis in liver than in adipose tissue. This thesis has introduced the first non-invasive method for determining adipose tissue omega-3 fatty acid content in humans in vivo. The methods introduced here have also shown that liver fat is more saturated than adipose tissue fat.

Identification and characterization of thionucleosides in the total tRNA of cucumber cotyledons

Total tRNA isolated from cucumber cotyledons grown in the presence of radioactive sulfur was analyzed for the occurrence of thionucleosides. The analysis revealed the presence of at least five thionucleosides which were identified as 5-methylaminomethyl-2-thiouridine (mnm5s2U), 2-methylthio-N6-isopentenyladenosine (ms2i6A), 2-methylthio-N6-hydroxyisopentenyladenosine (ms2io6A), 5-methyl-2-thiouridine (m5s2U) and N-[(9-beta-ribofuranosyl-2- methylthiopurine-2-yl)-carbamoyl]-threonine (ms2t6A). A comparison of relative amounts of these thionucleosides in the total tRNAs of dark-, and light-grown cotyledons shows that the relative amounts of ms2i6A, ms2io6A and ms2t6A remain unchanged whereas mnm5s2U increases with a concomitant decrease in the relative amounts of m5s2U after light treatment of dark-grown cotyledons.

Asymmetric total synthesis of erythromycin. 2. Synthesis of an erythronolide A lactone system

In reporting a total synthesis of erythromycin (la) we described in the preceding paper1 the synthesis of the erythronolide A seco acid derivative 2 in optically active form. In this paper we wish to report a successful transformation of 2 to 12 (synthetically equivalent to erythronolide A) via lactonization and also demonstrate that the proper functionalization of a substrate is critical for the successful lactonization.

Asymmetric total synthesis of erythromycin. 3. Total synthesis of erythromycin

In the preceding paper' we described the preparation of the key lactone intermediate la in optically active form. In this paper we report the synthesis of erythromycin (2) from la. In essence,this transformation involves the glycosidation of a suitable derivative of la with L-cladinose and D-desosamine and the generation of the C-9 ketone functionality.

Total Hip and Knee Arthoplasty for Osteoarthritis : Factors Related to the Early Outcome of Surgery

Some perioperative clinical factors related to the primary cemented arthroplasty operation for osteoarthritis of the hip or knee joint are studied and discussed in this thesis. In a randomized, double-blind study, 39 patients were divided into two groups: one receiving tranexamic acid and the other not receiving it. Tranexamic acid was given in a dose of 10 mg/kg before the operation and twice thereafter, at 8-hour intervals. Total blood loss was smaller in the tranexamic acid group than in the control group. No thromboembolic complications were noticed. In a prospective, randomized study, 58 patients with hip arthroplasty and 39 patients with knee arthroplasty were divided into groups with postoperative closed-suction drainage and without drainage. There was no difference in healing of the wounds, postoperative blood transfusions, complications or range of motion. As a result of this study, the use of drains is no longer recommended. In a randomised study the effectiveness of a femoral nerve block (25 patients) was compared with other methods of pain control (24 patients) on the first postoperative day after total knee arthroplasty. The femoral block consisted of a single injection administered at patients´ bedside during the surgeon´s hospital rounds. Femoral block patients reported less pain and required half of the amount of oxycodone. Additional femoral block or continued epidural analgesia was required more frequently by the control group patients. Pain management with femoral blocks resulted in less work for nursing staff. In a retrospective study of 422 total hip and knee arthroplasty cases the C-reactive protein levels and clinical course were examined. After hip and knee arthroplasty the maximal C-reactive protein values are seen on the second and third postoperative days, after which the level decreases rapidly. There is no difference between patients with cemented or uncemented prostheses. Major postoperative complications may cause a further increase in C-reactive protein levels at one and two weeks. In-hospital and outpatient postoperative control radiographs of 200 hip and knee arthroplasties were reviewed retrospectively. If postoperative radiographs are of good quality, there seems to be no need for early repetitive radiographs. The quality and safety of follow-up is not compromised by limiting follow-up radiographs to those with clinical indications. Exposure of the patients and the staff to radiation is reduced. Reading of the radiographs by only the treating orthopaedic surgeon is enough. These factors may seem separate from each other, but linking them together may help the treating orthopaedic surgeon to adequate patient care strategy. Notable savings can be achieved.

A stereoselective total synthesis of (−)-seychellene

A stereoselective total synthesis of the tricyclic sesquiterpene (−)-seychellene, starting from (R)-carvone via (R)-3-methylcarvone has been accomplished, employing a combination of intermolecular Michael addition–intramolecular Michael addition sequence, a stereoselective hydrogenation, and an intramolecular alkylation reaction.

Chemical modifications of natural triterpenes—glycyrrhetinic and boswellic acids: evaluation of their biological activity

Synthetic analogues of naturally occurring triterpenoids; glycyrrhetinic acid, arjunolic acid, and boswellic acids, by modification of A-ring with a cyano- and enone-functionality, have been reported. A novel method of synthesis of α-cyanoenones from isoxazoles is reported. Bioassays using primary mouse macrophages and tumor cell lines indicate potent anti-inflammatory and cytotoxic activities associated with cyano-enones of boswellic acid and glycyrrhetinic acid.

QCD and total cross-sections : photons and hadrons

In this contribution, we discuss a total cross-section model which can be applied to both photon and purely hadronic processes. We find that the model can reproduce photo-production cross-sections, as well as extrapolation of gamma*p processes to gamma p using Vector Meson Dominance models, with minimal modifications from the proton case.

QCD and total cross-sections : photons and hadrons

In this contribution, we discuss a total cross-section model which can be applied to both photon and purely hadronic processes. We find that the model can reproduce photo-production cross-sections, as well as extrapolation of gamma*p processes to gamma p using Vector Meson Dominance models, with minimal modifications from the proton case.

DNA cleavage in red light promoted by copper(II) complexes of -amino acids and photoactive phenanthroline bases

Ternary copper(II) complexes [Cu(L-trp)(B)(H2O)](NO3) ( 1–3) and [Cu(L-phe)(B)(H2O)](NO3) ( 4–6) of L-tryptophan (L-trp) and L-phenylalanine (L-phe) having phenanthroline bases (B), viz. 1,10-phenanthroline (phen, 1 and 4), dipyrido[3,2-d:2,3-f]quinoxaline (dpq, 2 and 5) and dipyrido[3,2-a:2,3-c]phenazine (dppz, 3 and 6), were prepared and characterized by physico-chemical techniques. Complexes 3 and 6 were structurally characterized by X-ray crystallography and show the presence of a square pyramidal (4 + 1) CuN3O2 coordination geometry in which the N,O-donor amino acid (L-trp or L-phe) and N,N-donor phenanthroline base bind at the equatorial plane with an aqua ligand coordinated at the elongated axial site. Complex 3 shows significant distortion from the square pyramidal geometry and a strong intramolecular – stacking interaction between the pendant indole ring of L-trp and the planar dppz aromatic moiety. All the complexes display good binding propensity to the calf thymus DNA giving an order: 3, 6 (dppz) > 2, 5 (dpq) > 1, 4 (phen). The binding constant (Kb) values are in the range of 2.1 × 104–1.1 × 106 mol-1 with the binding site size (s) values of 0.17–0.63. The phen and dpq complexes are minor groove binders while the dppz analogues bind at the DNA major groove. Theoretical DNA docking studies on 2 and 3 show the close proximity of two photosensitizers, viz. the indole moiety of L-trp and the quinoxaline/phenazine of the dpq/dppz bases, to the complementary DNA strands. Complexes 2 and 3 show oxidative DNA double strand breaks (dsb) of supercoiled (SC) DNA forming a significant quantity of linear DNA along with the nicked circular (NC) form on photoexposure to UV-A light of 365 nm and red light of 647.1 nm (Ar–Kr laser). Complexes 1, 5 and 6 show only single strand breaks (ssb) forming NC DNA. The red light induced DNA cleavage involves metal-assisted photosensitization of L-trp and dpq/dppz base resulting in the formation of a reactive singlet oxygen (1O2) species.

An improved procedure for the synthesis of dehydroamino acids and dehydropeptides from the carbonate derivatives of serine and threonine using tetrabutylammonium fluoride

Dehydroamino acids are important precursors for the synthesis of a number of unnatural amino acids and are structural components in many biologically active peptide derivatives. However, efficient synthetic procedures for their production in large amounts and without side reactions are limited. We report here an improved procedure for the synthesis of dehydroalanine and dehydroamino butyric acid from the carbonate derivatives of serine and threonine using TBAF. The antiselective E-2 elimination of the carbonate derivatives of serine and threonine using TBAF is milder and more efficient than other available procedures. The elimination reaction is completed in less than 10 min with various carbonate derivatives studied and the methodology is very efficient for the synthesis of dehydroamino acids and dehydropeptides. The procedure thus provides an easy access to key synthetic precursors and can be used to introduce interesting structural elements to designed peptides. Copyright