Functional assessment of human femoral arteries after cryopreservation

An established method for the cryopreservation of human femoral arteries for subsequent transplantation as allografts has been studied with particular attention to preservation of smooth muscle and endothelium. Human femoral arteries (HFAs) were harvested from multi-organ donors. Two groups were established; a control group of unfrozen HFAs and a group of cryopreserved HFAs. Cryopreservation was performed using RPMI solution containing dimethyl sulfoxide and the rate of cooling was 1 degrees C/min to -40 degrees C and faster thereafter until -150 degrees C was reached. The contraction and relaxation responses of unfrozen and frozen/thawed arteries were assessed by measurement of the isometric force generated by the HFAs in an organ bath. After thawing (warming was at 15 degrees C/min) the maximal contractile response to noradrenaline was 43% of the response of unfrozen HFAs. The endothelium-independent response to sodium nitroprusside was not altered, whereas the endothelium-dependent relaxation response to acetylcholine was slightly altered. The cryopreservation method used provided limited preservation of the contractility of human femoral arteries, and good preservation of both endothelium-independent and endothelium-dependent relaxation responses.     

Behavioral risk factors and prevalence of HIV and other STIs among female sex workers in Tirana, Albania

The paper presents the results of the research and a comparative analysis of findings on key indicators for the study population. The study instrument was a standardized behavior study questionnaire provided in the Family Health International published manual (Family Health International, 2000). The target group was female sex workers working in Tirana. The prevalence of biological infections was low. HIV was detected in one case. Syphilis and Hepatitis B rates resulted to be respectively 6.5% and 7.6%. The median age of the study participants is 28 years. Almost 38% of the participants were illiterate, and more than half belong to the Roma community. Almost 50% of the respondents had received money in exchange of sex for the first time 18 years earlier. Almost 65% of respondents reported two or more different sex partners in the last seven days, while almost 30% referred five or more. Condom use at last sex with a paying client was reported by almost 68%. Consistent condom use with paying clients in the last month was reported by almost 35% of the respondents.     

Stylissamide X, a new proline-rich cyclic octapeptide as an inhibitor of cell migration, from an Indonesian marine sponge of Stylissa sp

A new proline-rich cyclic octapeptide named stylissamide X (1) was isolated from an Indonesian marine sponge of Stylissa sp. as an inhibitor of cell migration from the guidance of wound-healing assay. The chemical structure of stylissamide X (1) was determined on the basis of spectroscopic analysis, and stereostructure of the amino acids were deduced by Marfey's method. Compound 1 showed inhibitory activity against migration of HeLa cells in the ranges of 0.1-10 μM concentration through both wound-healing assay and chemotaxicell chamber assay, while the cell viability was maintained more than 75% up to 10 μM concentration of 1.     

Drought-induced changes in xylem pH, ionic composition, and ABA concentration act as early signals in field-grown maize (Zea mays L.).

Early signals potentially regulating leaf growth and stomatal aperture in field-grown maize (Zea mays L.) subjected to drought were investigated. Plants grown in a field lysimeter on two soil types were subjected to progressive drought during vegetative growth. Leaf ABA content, water status, extension rate, conductance, photosynthesis, nitrogen content, and xylem sap composition were measured daily. Maize responded similarly to progressive drought on both soil types. Effects on loam were less pronounced than on sand. Relative to fully-watered controls, xylem pH increased by about 0.2 units one day after withholding irrigation (DAWI) and conductivity decreased by about 0.25 mS cm(-1) 1-3 DAWI. Xylem nitrate, ammonium, and phosphate concentrations decreased by about 50% at 1-5 DAWI and potassium concentration decreased by about 50% at 7-8 DAWI. Xylem ABA concentration consistently increased by 45-70 pmol ml(-1) at 7 DAWI. Leaf extension rate decreased 5 DAWI, after the changes in xylem chemical composition had occurred. Leaf nitrogen significantly decreased 8-16 DAWI in droughted plants. Midday leaf water potential and photosynthesis were significantly decreased in droughted plants late in the drying period. Xylem nitrate concentration was the only ionic xylem sap component significantly correlated to increasing soil moisture deficit and decreasing leaf nitrogen concentration. Predawn leaf ABA content in droughted plants increased by 100-200 ng g(-1) dry weight at 7 DAWI coinciding with a decrease in stomatal conductance before any significant decrease in midday leaf water potential was observed. Based on the observed sequence, a chain of signal events is suggested eventually leading to stomatal closure and leaf surface reduction through interactive effects of reduced nitrogen supply and plant growth regulators under drought.     

Small and valid species of Trichiurus brevis Wang and You, 1992 and T. russelli Dutt and Thankam, 1966, defined as the “T. russelli complex” (Perciformes: Trichiuridae)

 The taxonomic status of three small [probably less than ca. 600 mm in the largest total length (TL)] and poorly known species, Trichiurus brevis Wang and You, 1992 and T. minor Li, 1992, both from South China Sea, and T. russelli Dutt and Thankam, 1966, from Bengal Bay, was reexamined. Trichiurus brevis and T. russelli, being valid species, are redescribed and a neotype is designated for the latter. Trichiurus brevis is considered to be a senior synonym of T. minor, there being no significant differences in their type specimens. Both valid species, i.e., T. brevis and T. russelli, are similar to T. lepturus Linnaeus, 1758 (larger than ca. 1000 mm TL) in general appearance, but clearly differ from the latter in having the top of the supraoccipital crest situated directly above the posterior margin of eye (vs. well behind posterior margin), lower number of total vertebrae (147–155 and 149–153, respectively, in the former two species vs. 168–173 in T. lepturus), longer dorsal fin base (mean 87% and mean 84% vs. mean 76% of TL), and shorter caudal peduncle length (6% and 8% vs. 13% of TL). Furthermore, the former two species are characterized by having the anal fin origin situated below about the 32nd–35th dorsal fin ray base, whereas in T. lepturus it is situated below the 37th–41st dorsal fin ray base. We recognize that T. brevis and T. russelli together comprise a species group, defined as the “T. russelli complex,” in the genus Trichiurus, the two species differing in snout shape (strongly pointed in T. brevis vs. moderately pointed in T. russelli), snout length [mean 35% vs. mean 30% of head length (HL)], preopercle length (22% vs. 19% HL), predorsal length (70% vs. 63% HL), and dermal eye opening (16% vs. 18% HL). Received: April 26, 2001 / Revised: January 19, 2002 / Accepted: February 1, 2002     

Examination of intrinsic sulfonamide resistance in Bacillus anthracis: A novel assay for dihydropteroate synthase

Dihydropteroate synthase (DHPS) catalyzes the formation of dihydropteroate and Mg-pyrophosphate from 6-hydroxymethyl-7,8-dihydropterin diphosphate and para-aminobenzoic acid. The Bacillus anthracis DHPS is intrinsically resistant to sulfonamides. However, using a radioassay that monitors the dihydropteroate product, the enzyme was inhibited by the same sulfonamides. A continuous spectrophotometric assay for measuring the enzymatic activity of DHPS was developed and used to examine the effects of sulfonamides on the enzyme. The new assay couples the production of MgPP_i to the pyrophosphate-dependent phosphofructokinase/aldolase/triose isomerase/α-glycerophosphate dehydrogenase reactions and monitors the disappearance of NADH at 340nm. The coupled enzyme assay demonstrates that resistance of the B. anthracis DHPS results in part from the use of the sulfonamides as alternative substrates, resulting in the formation of sulfonamide-pterin adducts, and not necessarily due to an inability to bind them.     

Overexpression of yeast Hsp110 homolog Sse1p suppresses ydj1-151 thermosensitivity and restores Hsp90-dependent activity

The Saccharomyces cerevisiae heat-shock protein (Hsp)40, Ydj1p, is involved in a variety of cellular activities that control polypeptide fate, such as folding and translocation across intracellular membranes. To elucidate the mechanism of Ydj1p action, and to identify functional partners, we screened for multicopy suppressors of the temperature-sensitive ydj1-151 mutant and identified a yeast Hsp110, SSE1. Overexpression of Sse1p also suppressed the folding defect of v-Src kinase in the ydj1-151 mutant and partially reversed the alpha-factor translocation defect. SSE1-dependent suppression of ydj1-151 thermosensitivity required the wild-type ATP-binding domain of Sse1p. However, the Sse1p mutants maintained heat-denatured firefly luciferase in a folding-competent state in vitro and restored human androgen receptor folding in sse1 mutant cells. Because the folding of both v-Src kinase and human androgen receptor in yeast requires the Hsp90 complex, these data suggest that Ydj1p and Sse1p are interacting cochaperones in the Hsp90 complex and facilitate Hsp90-dependent activity.     

Apoplastic water fraction and rehydration techniques introduce significant errors in measurements of relative water content and osmotic potential in plant leaves

Relative water content (RWC) and the osmotic potential (π) of plant leaves are important plant traits that can be used to assess drought tolerance or adaptation of plants. We estimated the magnitude of errors that are introduced by dilution of π from apoplastic water in osmometry methods and the errors that occur during rehydration of leaves for RWC and π in 14 different plant species from trees, grasses and herbs. Our data indicate that rehydration technique and length of rehydration can introduce significant errors in both RWC and π. Leaves from all species were fully turgid after 1–3 h of rehydration and increasing the rehydration time resulted in a significant underprediction of RWC. Standing rehydration via the petiole introduced the least errors while rehydration via floating disks and submerging leaves for rehydration led to a greater underprediction of RWC. The same effect was also observed for π. The π values following standing rehydration could be corrected by applying a dilution factor from apoplastic water dilution using an osmometric method but not by using apoplastic water fraction (AWF) from pressure volume (PV) curves. The apoplastic water dilution error was between 5 and 18%, while the two other rehydration methods introduced much greater errors. We recommend the use of the standing rehydration method because (1) the correct rehydration time can be evaluated by measuring water potential, (2) overhydration effects were smallest, and (3) π can be accurately corrected by using osmometric methods to estimate apoplastic water dilution.     

Crystal structures of ligand-bound saccharopine dehydrogenase from Saccharomyces cerevisiae

Three structures of saccharopine dehydrogenase (l-lysine-forming) (SDH) have been determined in the presence of sulfate, adenosine monophosphate (AMP), and oxalylglycine (OxGly). In the sulfate-bound structure, a sulfate ion binds in a cleft between the two domains of SDH, occupies one of the substrate carboxylate binding sites, and results in partial closure of the active site of the enzyme due to a domain rotation of almost 12 degrees in comparison to the apoenzyme structure. In the second structure, AMP binds to the active site in an area where the NAD+ cofactor is expected to bind. All of the AMP moieties (adenine ring, ribose, and phosphate) interact with specific residues of the enzyme. In the OxGly-bound structure, carboxylates of OxGly interact with arginine residues representative of the manner in which substrate (alpha-ketoglutarate and saccharopine) may bind. The alpha-keto group of OxGly interacts with Lys77 and His96, which are candidates for acid-base catalysis. Analysis of ligand-enzyme interactions, comparative structural analysis, corroboration with kinetic data, and discussion of a ternary complex model are presented in this study.