Definition, willingness-to-pay, and ranking of quality attributes of U.S. pork as defined by importers in Asia and Mexico.

A survey was conducted from November 2009 to April 2010 to determine how importers of pork define 7 predetermined quality categories (food safety, customer service, eating quality, product specification, packaging, visual characteristics, and production history) and to estimate willingness-to-pay (WTP) and establish best-worst (B/W) scaling (rank) for the 7 quality categories. Interviews were conducted in Hong Kong/China (n = 83), Japan (n = 48), Mexico (n = 70) and Russia (n = 54) with importers of U.S. pork or those who had purchased U.S. pork from distributors in the last 3 yr. Interviews used dynamic routing software and were structured such that economic factors for purchase were addressed first, allowing all responses to focus on quality. Questions about WTP and B/W were asked and then each respondent was asked to define what each quality category meant to them. Generalized linear mixed models were used to analyze frequency data. Over 70% of interviewees in Hong Kong/China, Japan, and Mexico responded that purchase price was influential in deciding whether or not to purchase imported pork. This number was lower in Russia, where respondents stated tariff rates were also important, indicating market access was a larger issue in Russia. Food safety was the most important quality category (price was not included as a part of quality) for imported pork followed by specifications. Respondents indicated some form of government inspection was how they defined food safety, whereas product size, weight, and subcutaneous fat were all included in the definition of specifications. Interviewees were more likely to pay premiums for customer service and less likely to pay premiums for packaging (P < 0.05). The premiums that were willing to be paid for guarantees of quality for imported pork variety meats were numerically lower than for whole muscle cuts or processed products. A guarantee associated with food safety of processed pork products was found to be the quality attribute for which importers would be willing to pay the highest premium. Production history was found to be the least important quality attribute for importers of all types of U.S. pork, except those in Japan. Exporters could increase profitability if a guarantee of customer service was made. Price, tariffs, and exchange rates are important to pork importers; these results indicated that if certain quality attributes could be guaranteed, exporters could increase profitability.

Electrospray ionization and low energy tandem mass spectrometry of polyhydroxy unsaturated fatty acids.

Negative ion electrospray ionization, fast-atom bombardment, and low energy tandem mass spectrometry were used for the analysis of dihydroxy-eicosatrienoic acids, which contain a vicinol diol and three nonconjugated double bonds, dihydroxy-eicosatetraenoic acids, which contain a conjugated triene structure, and trihydroxy-eicosatetraenoic acids, which contain a vicinol diol and a conjugated tetraene structure. In general, the product ion spectra were qualitatively similar for both modes of ionization, but electrospray ionization was strikingly more efficient in generation of abundant carboxylate anions that could be collisionally activated to yield product ion spectra. Collision-induced dissociation fragmentation mechanisms were described generally by α-hydroxy fragmentations directed by relative positions of double bonds and were consistent with stable isotope labeling studies. Rearrangement of the conjugated triene system in dihydroxy-eicosatetraenoic acids may be described by formation of a cyclohexadiene structure. Fragmentations that involve a two-proton transfer were described best by intramolecular oxidation of a hydroxy substituent to an enolate that resulted in an extended conjugated system. Collision-induced dissociation spectra obtained for the polyhydroxy unsaturated fatty acids, which are isobaric within each class, were uniquely descriptive of individual structures.

Development of a cyanobacterial biolarvicide.

Results of studies on a larvicidal cyanobacterium that expresses a Bti cryIVD gene fusion are reported. Genetically altered Agmenellum quadruplicatum PR-6 is shown to be toxic to larvae of three major genera of disease-bearing mosquitos. Factors affecting expression of Bti genes in cyanobacteria are discussed.

Analysis of hydroxy fatty acids as pentafluorobenzyl ester, trimethylsilyl ether derivatives by electron ionization gas chromatography/mass spectrometry.

Electron ionization (EI) gas chromatography/mass spectrometry (GC/MS) analysis of pentafluorobenzyl ester-trimethyl sllyl ether (PFB-TMS) derivatives of hydroxy-subshtuted fatty acids provides structural information comparable to that obtained in analysis of methyl ester-trimethyl silyl ether (Me-TMS) derivatives. Use of this derivative eliminates the need to prepare two separate derivatives, the PFB-TMS derivative for molecular weight determination by electron capture ionization (negative ions) analysis and the Me-TMS derivative for structural determination by EI GC/MS analysis. The relative abundance of fragment ions observed during EI GC/MS analysis of these derivatized unsaturated fatty acids indicates the location of the -OTMS substituents relative to double bond positions in those cases studied. The most abundant fragment ions are observed when the compound contains an unsaturation two carbon atoms removed from the -OTMS ether carbon (the ß-OTMS position). The "saddle effect" observed in the GC/MS analyses of some derivatized monohy- droxy unsaturated fatty acids is suggested to be due to a thermally allowed pericyclic double bond rearrangement and indicates the presence of a conjugated diene one carbon atom removed from the -OTMS ether carbon (the α-OTMS position). The saddle effect is most prominent for fatty acids that contain additional unsaturation separated by a single methylene unit from the conjugated diene moiety.

Optimal management of inguinal vascular graft infections.

Vascular graft infections demand serious attention due to the potential for mortality or limb loss. Management modalities range from conservative wound debridement and drainage to graft resection and extra-anatomical revascularization. A retrospective chart review was conducted to evaluate wound complications in patients who underwent inguinal vascular bypass in an attempt to define the incidence of wound complications and guidelines for their management. Vascular operations involving femoral anastomoses were performed on 1,637 patients; 58 wound infections occurred in 57 patients (3.5%) over an 8-year period at our institution. There were 16 graft infections in 15 of these 57 patients (0.92%). Ten patients were treated with local muscle flaps, 1 with a fasciocutaneous thigh flap, and 5 with graft excision and either extra-anatomical bypass or amputation. Local flap coverage appears to be as effective as graft excision for the treatment of inguinal vascular graft infections. An algorithm for optimal management of these infections is presented.

Major neurovascular complications of endoscopic carpal tunnel release.

Endoscopic carpal tunnel release is becoming an increasingly popular method of surgically correcting median nerve compression. Several complications have been suggested as possibilities following the technique; however, to date, there have been only isolated reports of iatrogenic injury to major neurovascular structures in the hand. We report both a case of transection of the median nerve and a pseudoaneurysm of the superficial palmar arch following endoscopic carpal tunnel release.

Extradigital glomus tumor as a cause of knee pain.

Although there exists much debate in the dermatohistopathologic literature about the exact characterization of the glomus tumor, this case illustrates what should be considered the sine qua non indications of clinically significant glomus tumors, i.e., exquisite pain and complete relief of pain with surgical excision. One should not, therefore, limit the inclusion of glomus tumors to the differential diagnosis of severe localized pain only in the upper extremity.

A barrier technique for pulsed irrigation of cavitary wounds.

A technique for barrier protection during pulsed irrigation of cavitary wounds is presented. The method is discussed within the context of current concerns regarding intraoperative viral transmission.

Magnetic resonance imaging in the evaluation of persistent carpal tunnel syndrome.

Magnetic resonance imaging was used to assess nine median nerves in the wrists of seven patients who had signs and symptoms of persistent compressive median neuropathy despite previous carpal tunnel release. Intraoperative findings were then correlated in eight surgically treated cases with both MRI findings and postoperative results. Magnetic resonance imaging suggested a potential abnormality in each of eight operative cases. These findings correlated very well with both intraoperative observations and postoperative results, which indicated that some abnormality involving either the median nerve or the transverse carpal ligament had been present in all cases. Magnetic resonance imaging proved to be a sensitive and specific tool in the evaluation of persistent postoperative median nerve compression.

Time-dependent utilization of platelet arachidonic acid by the neutrophil in formation of 5-lipoxygenase products in platelet-neutrophil co-incubations.

The biosynthesis of leukotrienes is known to occur through a series of complex processes which, in part, can be influenced by cell-cell interactions. Several studies have suggested that arachidonic acid availability is a major limiting step for leukotriene biosynthesis and that its transfer between cells can represent a significant source of this precursor. Accordingly, effect of time and source of arachidonic acid on transcellular leukotriene synthesis was studied in mixed platelet/neutrophil populations challenged with the calcium ionophore A23187. A time-dependent contribution of platelet-derived as well as neutrophil-derived arachidonate was found in the selective formation of neutrophil 5-lipoxygenase metabolites. Utilization of platelet or neutrophil arachidonate was followed by incorporation of radiolabeled arachidonic acid into platelet or neutrophil phospholipids prior to stimulation. Specific activity of liberated arachidonic acid along with numerous 5-lipoxygenase products (including LTB4, 20-hydroxy-LTB4, 5-HETE and LTC4) was determined in order to follow mass and radiolabel. A large amount of platelet-derived arachidonic acid was released in the first 1.5 min, whereas 10 min platelet-derived arachidonate was much lower in amount but significantly higher in specific activity, suggesting different precursor pools. The platelet-derived arachidonate was heavily utilized by the neutrophils at the early time points for formation of 5-HETE and delta 6-trans-LTB4 isomers, but appeared to contribute only marginally to the constitutive metabolism of neutrophil arachidonate into LTB4. Results from these experiments suggest different pools of 5-lipoxygenase in the neutrophil and indicate a time and source dependent modulation of arachidonate metabolism in mixed cell interactions.

Visual symptoms associated with choroidal neovascularization. Photopsias and the Charles Bonnet syndrome.

One hundred consecutive patients with macular choroidal neovascularization were studied in a cross-sectional fashion. Evidence of bilateral choroidal neovascularization was present in 31 patients. Among the 100 subjects, 59% related a history of seeing flickering or flashing lights (photopsias) in the affected eye or eyes. The colors varied, but in 59% of instances the lights were white. Twelve subjects experienced formed hallucinations (Charles Bonnet syndrome); in nine (75%) of these patients, the sequelae of choroidal neovascularization were bilateral. Symptoms that are commonly attributed to vitreoretinal tractional phenomena as well as neurologic and/or psychiatric disease are also frequently encountered in patients with macular degeneration associated with choroidal neovascularization.

Molecular species analysis of arachidonate containing glycerophosphocholines by tandem mass spectrometry.

Carboxylate anions arising from collision-induced dissociation (CID) of the [M - 15](-) ion produced by fast atom bombardment (FAB) of glycerophosphocholine (GPCho) were previously shown to be produced in an abundance ratio of 1:3 for the carboxylic acids esterified at sn - 1 and sn - 2, respectively. This observation has been confirmed in a series of 13 synthetic GPCho molecular species. A good correlation was found between the isomeric purity of GPCho molecular species as determined by negative-ion FAB/CID analysis and the isomeric purity of the sn - 2 fatty acid using a phospholipase A2 assay. Negative-ion FAB mass spectra of several 1-0-alkyl-2-acyl-GPCho molecular species were found to be similar to those of diacyl GPCho. However, the cm spectra from the major high-mass ions are different from those of the diacyl species in that the [M - 15](-) ion yields only one carboxylate anion and the [M - 86](-) undergoes a neutral loss of the sn - 2 carboxylic acid as a major decomposition product. These results suggest several rules useful for structural characterization of GPCho molecular species by negative-ion tandem mass spectrometry (MS/MS): (1) For diacyl species, the mass of the two carboxyl anions plus the mass of the GPeho backbone (minus a methyl group) must correspond to the mass of the [M - 15] anion; (2) for diacyl species there is a carboxylate anion ratio approximately 1:3 for the substituents at sn - 1 and sn - 2; and (3) for alkylether species, only one fatty acyl group is present, and the difference between the [M - 15] ion and the GPCho backbone (minus methyl) plus the fatty acyl group at sn - 2 corresponds to an alkylether substituent. (4) Assignment of ether-linked molecular species can be made from the [M - 86](-) ion, which has a strong neutral loss of the sn - 2 fatty acid.Analysis of GPCho isolated from human neutrophils by total lipid extraction and normal-phase HPLC was carried out by negative-ion FABand MS/MS. The major arachidonate-eontaining molecular species, which comprise only 5% of total GPCho, were identified by using precursor ion scans for the arachidonate anion, m/ z 303. Decomposition of identified. precursor ions permitted the assignment of those molecular species of GPCho that contain arachidonate at sn - 2 and identification of the substituent at the sn - 1 position. These results were compared to previously identified molecular species from human neutrophils. Several minor arachidonate-containing molecular species were tentatively identified.

Negative ion tandem mass spectrometry of leukotriene E4, and LTE 4, metabolites: Identification of LTE 4, in human urine.

The sulfidopeptide leukotrienes, leukotriene E4, (LTE4,) and its N-acetyl derivative and several ω- and ß-oxidized metabolites of LTE4, have been analyzed by tandem mass spectrometry. [M-H](-) ions were produced by continuous flow fast atom bombardment, and collision-induced dissociation of these ions was studied by using a triple quadrupole instrument. The product ion spectra obtained were characteristic of the structure of LTE4, and mechanisms of ion formation were investigated by using deuterated compounds. ß-Elimination of the peptide portion of LTE4, by loss of CO2, and ethylene amine leaves the C-l carboxyl group ionized in the most abundant fragment ion for LTE4, and all metabolites. Tandem mass spectrometry of fast atom bombardment-generated anions from ω- and ß-oxidized metabolites of LTE4, produced similar ions with only a minor influence of the third carboxyl group at the omega terminus evident. Tandem mass spectrometry was used to identify unequivocally the presence of unmodified LTE4, in a high performance liquid chromatography-purified fraction of urine from a normal healthy volunteer after infusion with LTE4.

Fast atom bombardment and collision-induced dissociation of prostaglandins and thromboxanes: Some examples of charge remote fragmentation.

The mass spectra of products found by collisional activation of selected prostaglandins and thromboxanes were studied by tandem mass spectrometry as barium carboxylate salts and as carboxylate anions. Collision-induced dissociation (CID) of these closed shell ions generated by fast atom bombardment mass spectrometry reveals a wealth of structural information for these hydroxy acids. Decomposition reactions were found to be dependent upon the eicosanoid ring structure and the type of ion being studied, either positive or negative ion. The bariated carboxylate salts undergo reactions by processes that are similar to those previously characterized as charge remote mechanisms in which neutral species are lost as in thermal and photolytic decompositions. The most abundant ion is formed by loss of water from each of the hydroxyl groups present on the prostaglandin or thromboxane structure. For these multifunctionalized eicosanoids, typical patterns of decomposition emerge as characteristic of the oxygen substituents present along the carbon chain of the eicosanoid structure. The structural information obtained from the barium salts along with those from the carboxylate anions is substantially different, yet the structural information from each process is complementary. The CIDs of positive ions (metalated salts) provide structural information concerning the substituents between the carboxyl group and C12 of the eicosanoid structure, whereas the decompositions of the carboxylate anions (negative ion mode) provide data concerning structure alterations of the eicosanoid structure between C15 and C20.

Pharmacokinetics of zidovudine administered intravenously and orally in children with human immunodeficiency virus infection.

Zidovudine pharmacokinetics were determined in 16 children with human immunodeficiency virus infection who were being treated intravenously and orally on an intermittent schedule (every 6 hours). The intravenous doses studied were 80 (n = 3), 120 (n = 4), and 160 (n = 5) mg/m2/dose, infused over 1 hour. Fourteen patients were monitored after an oral dose of zidovudine at 120 (n = 2), 180 (n = 7), or 240 (n = 5) mg/m2/dose. Zidovudine was assayed with a reverse-phase high-pressure liquid chromatography method. Zidovudine disappearance after intravenous administration was rapid and biexponential, with half-lives of 14 and 90 minutes and a total clearance of 641 +/- 161 ml/min/m2. The volume of distribution at steady state was 45 +/- 28 L/m2. These pharmacokinetics parameters are very similar to those reported in adults. When administered orally, zidovudine was rapidly absorbed. The fraction of the oral dose that was bioavailable was 0.68 +/- 0.25, so that a 50% increment in the dose, in the conversion from intravenous to oral administration, resulted in plasma zidovudine concentrations after oral dosing that were nearly identical to those achieved with the 1-hour intravenous infusion. However, a dose of 180 mg/m2 given orally every 6 hours maintained plasma zidovudine concentrations in the target range of 1 mumol/L for less than half of the dosing interval. Other schedules, routes of administration, or oral drug formulations may have to be considered if sustained continuous exposure to micromolar zidovudine concentrations is desired.

Congenital rickets associated with magnesium sulfate infusion for tocolysis.

The records of five neonates born to mothers treated with intravenously administered magnesium sulfate for tocolysis were retrospectively reviewed to assess the presence of radiographic, clinical, and biochemical abnormalities. Two infants had radiographic bony abnormalities; one had frank rachitic changes and dental enamel hypoplasia. One of these patients, as well as an additional infant, had transient hypocalcemia. We hypothesize that prolonged infusion of magnesium sulfate, especially when initiated during the second trimester, may lead to fetal parathyroid gland suppression with consequent abnormalities resembling rickets.