Steroid-free induction and preemptive antiviral therapy for liver transplant recipients with hepatitis C: a preliminary report from a prospective randomized study

Recurrence of hepatitis C (HepC) has been a most difficult dilemma in liver transplantation (OLT) because the effects of immunosuppression with steroid, mycophenolate mofetil (MMF) calcineurin antagonists, and anti-interleukin-2 antibody as well as the role of preemptive antiviral therapy are uncertain. In this study, we randomized OLT recipients with HepC into two treatment arms: tacrolimus+daclizumab+MMF (study arm) versus tacrolimus+steroids+MMF (control arm). The study arm only received steroids for the treatment of biopsy-proven rejection episodes. Both arms received preemptive anti-viral therapy with Pegasys and ribavirin. The 39 enrolled patients (among 50 to be enrolled) have median follow-up of 458 days with 23 patients (8 in study arm, 15 in control arm) having reached 1 year. The incidences of rejection episodes within 0 to 3 months, 3 to 6 months, and 6 to 12 months were (study vs control): 0% vs 28%; 0% vs 6%; and 13% vs 20%; respectively (P = NS). The 1-year protocol biopsies showed advanced fibrosis (stage 3 or greater) in 20% (3 of 15) of the control arm, but none (0 of 7) of the study arm (P = NS). We compared anticipated side effects of steroids in the first 3 months (study vs control): hypertension (36% vs 58%, P = NS), PTDM (7% vs 43%, P = .02), and wound infections (14% vs 37%, P = NS). In conclusion, liver transplant recipients with HepC tolerate a steroid-free protocol. There was a trend toward reduced steroid side effects and a lower incidence of advanced fibrosis in 1-year biopsy samples among patients receiving the steroid-free protocol.

Expanded use of transplantation techniques: abdominal wall transplantation and intestinal autotransplantation

Surgical principles and techniques derived from organ transplantation surgery can provide novel applications in general surgery. We present an update on our 5-year experience with intestinal autotransplantation and abdominal wall transplantation. Nine patients underwent intestinal or multivisceral transplantation with the addition of 10 abdominal wall grafts to cover the large open areas from previous surgeries. Seven patients underwent near-total abdominal evisceration, ex vivo resection of masses at the base of the mesentery, followed by intestinal autotransplantation; 44% of the abdominal wall graft recipients are alive, but none of the fatalities were related to the graft itself. In two cases the graft had to be removed due to venous thrombosis. Of patients with intestinal autotransplants, 71% are alive with two mortalities due to recurrent metastatic malignancy. In only one case, the intestinal autograft had to be removed because of venous thrombosis. All surviving patients but one are on a regular diet; two are on supplemental enteral feeds. These results show that anastomotic and resection techniques derived from the experience in solid organ transplant can be utilized in complex wound closure, as is the case of abdominal wall transplantation, or resection of large retroperitoneal tumors with intestinal autotransplantation.

The Impact of Campath 1H Induction in Adult Liver Allotransplantation

BACKGROUND

We report our experience with Campath 1H in adult liver allotransplantation.

METHODS

Between December 2001 and February 2004, 77 patients underwent liver transplantation using Campath 1H induction and low-dose maintenance tacrolimus immunosuppression. The control group consisted of 50 patients with similar baseline characteristics and the same eligibility criteria, transplanted under our standard Tacrolimus/steroids regimen. Hepatitis C patients were excluded from the study.

RESULTS

Patient and graft survival were similar for both groups. The incidence of rejection was significantly lower in the Campath vs the control group (51% vs 65% at 12 months, P = .009). Tacrolimus trough levels and conversion from Tacrolimus or the addition of other immunosuppressive drugs due to nephrotoxicity were also significantly lower in the Campath 1H group.

CONCLUSION

Campath 1H induction with low-dose Tacrolimus maintenance immunosuppression is an effective regimen in reducing acute rejection in adult liver transplantation, while maintaining lower tacrolimus levels and less nephrotoxicity than our conventional immunosuppressive regimen.

Transcriptional regulation in cowpea bruchid guts during adaptation to a plant defence protease inhibitor

Cowpea bruchid, when fed on a diet containing the soybean cysteine protease inhibitor soyacystatin N (scN), activates an array of counter-defence genes to adapt to the negative effects of the inhibitor and regain its normal rate of feeding and development. A collection of 1920 cDNAs was obtained by differential subtraction with cDNAs prepared from guts of the 4th instar larvae of scN-adapted (reared on scN-containing diet) and scN-unadapted (reared on regular scN-free diet) cowpea bruchids. Subsequent expression profiling using DNA microarray and Northern blot analyses identified ninety-four transcript species from this collection that are responsive to dietary scN. scN-adapted insects induced genes encoding protein and carbohydrate digestive enzymes, probably to help meet their carbon and nitrogen requirements. Up-regulation of antimicrobial and detoxification protein genes may represent a generalized defence response. Genes down-regulated by scN reflected physiological adjustments of the cowpea bruchids to scN challenge. A large portion of the responsive genes, presumably involved in carrying out the counter-defence response, were of unknown function. The full-length cDNA of an scN-inducible cathepsin B-like cysteine protease was obtained. Its transcriptional response to scN during larval development contrasts with the pattern of the cathepsin L family, the major digestive enzymes. These results suggest cathepsin B-like cysteine proteases may play a crucial role in cowpea bruchid adaptation to dietary scN.

A novel synthetic method for nanosized crystalline titania for use in the decomposition of dyes

Photocatalytically active nanocrystalline titania particles were prepared using a hydrothermal process, by controlling the particle size and crystallinity. The crystalline structures and morphologies of the particles were characterized by X-ray diffraction and transmission electron microscopy. The BET method was used to determine the surface area and verify the grain size. To estimate the photocatalytic activity of the synthesized particles, a dye photodegradation experiment was carried out and the activity of the particles was compared with that of conventional titania. The results show that synthesized nanocrystalline titania particles had a higher photocatalytic activity than that of conventional titania. These findings provide a basis for the preparation of more effective and usef ul materials for use in AOP applications.

Differences in the fetal interleukin-6 response to microbial invasion of the amniotic cavity between term and preterm gestation

BACKGROUND/OBJECTIVE

Fetal inflammatory response has been implicated as a mechanism of multi-system organ injury in preterm and term neonates. Microbial invasion of the amniotic cavity (MIAC) is frequently associated with a fetal inflammatory response. However, there are no studies comparing the fetal response to MIAC in term and preterm gestations. The purpose of this study was to compare the umbilical cord plasma interleukin-6 (IL-6) concentrations in term and preterm neonates in the presence or absence of MIAC.

STUDY DESIGN

Umbilical cord blood was obtained at birth from 252 neonates whose mothers had an amniocentesis within 48 h of delivery (preterm delivery, n = 62; term delivery, n = 190). MIAC was defined as a positive amniotic fluid culture for bacteria or genital mycoplasmas. IL-6 was measured by a sensitive and specific immunoassay.

RESULTS

The median IL-6 concentration in umbilical cord plasma was significantly higher in preterm neonates than in term neonates (median 13.4 pg/ml, range 0.1-676 pg/ml vs. median 3.2 pg/ml, range 0.1-408 pg/ml; p < 0.0001). In the context of MIAC, the median umbilical cord plasma IL-6 concentration was significantly higher in preterm than in term neonates (median 31.6 pg/ml, range 1.4-676 pg/ml vs. median 11.7 pg/ml, range 1.3-82 pg/ml, respectively; p < 0.05). Neonates born to mothers with a positive amniotic fluid culture had a significantly higher median IL-6 concentration than neonates born to mothers with a negative amniotic fluid culture (preterm: median 31.6, range 1.4-676 pg/ml vs. median 8.0, range 0.1-656 pg/ml; p < 0.05 and term: median 11.7, range 1.3-82 pg/ml vs. median 3.1, range 0.1-408 pg/ml; p < 0.01, respectively).

CONCLUSIONS

The preterm fetus is capable of mounting a systemic cytokine response as measured by IL-6 in its peripheral blood. In the setting of MIAC, a fetal IL-6 response is higher in preterm than in term gestation.

Crystal structure and functional analysis of the SurE protein identify a novel phosphatase family

Homologs of the Escherichia coli surE gene are present in many eubacteria and archaea. Despite the evolutionary conservation, little information is available on the structure and function of their gene products. We have determined the crystal structure of the SurE protein from Thermotoga maritima. The structure reveals the dimeric arrangement of the subunits and an active site around a bound metal ion. We also demonstrate that the SurE protein exhibits a divalent metal ion-dependent phosphatase activity that is inhibited by vanadate or tungstate. In the vanadate- and tungstate-complexed structures, the inhibitors bind adjacent to the divalent metal ion. Our structural and functional analyses identify the SurE proteins as a novel family of metal ion-dependent phosphatases.

Reaction of oxygen with 6-hydroxydopamine catalyzed by Cu, Fe, Mn, and V complexes: identification of a thermodynamic window for effective metal catalysis

In the autoxidation of 6-hydroxydopamine, we investigated the reactivity of metals and metal complexes with a range of abilities to catalyse the reaction with oxygen. Comparing the catalytic effectiveness of aquo metals at pH 7.4, copper accelerated autoxidation 61-fold, iron 24-fold, manganese 7.3-fold, and vanadium 5.7-fold. Copper was thus the most effective catalyst despite being the weakest oxidant, indicating reduction of oxygen as rate limiting. EDTA, which decreases the reduction potential of Fe(III)/Fe(II), increased catalysis by iron 74% to almost that of aquo copper. Conversely, EDTA inhibited catalysis by copper, manganese, and vanadium. Desferrioxamine strongly inhibited catalysis by all of the metals. Histidine prevented catalysis by copper, accelerated catalysis by iron (43%), and had little effect on catalysis by manganese or vanadium. ADP and phytate inhibited catalysis by iron and manganese (50% or more), accelerated catalysis by vanadium (10-27%), and had no effect on catalysis by copper. The effects of the ligands largely reflected their influence on the reduction potential of the metal. Accordingly, addition of NaBr, which increases the reduction potential of Cu(II)/Cu(I), inhibited by 50%. In contrast, Na2SO4 augmented catalysis by copper 3-fold. Consistent with effects of OH- on reduction potentials and on metal coordination to 6-hydroxydopamine, an increase in pH to 8.0 decreased catalysis by copper and iron, but increased that of manganese 10-fold. In conclusion, the catalytic effectiveness of the metal-ligand complexes are largely attributable to their reduction potential, with steric accessibility playing secondary roles. The results delineate a window of catalytically effective potentials suitable for facile reduction and reoxidation by oxygen. By extension the results identify factors determining the pro- and antioxidant roles of ligands in metal mediated reduction of oxygen.

Structural basis of non-specific lipid binding in maize lipid-transfer protein complexes revealed by high-resolution X-ray crystallography

Non-specific lipid-transfer proteins (nsLTPs) are involved in the movement of phospholipids, glycolipids, fatty acids, and steroids between membranes. Several structures of plant nsLTPs have been determined both by X-ray crystallography and nuclear magnetic resonance. However, the detailed structural basis of the non-specific binding of hydrophobic ligands by nsLTPs is still poorly understood. In order to gain a better understanding of the structural basis of the non-specific binding of hydrophobic ligands by nsLTPs and to investigate the plasticity of the fatty acid binding cavity in nsLTPs, seven high-resolution (between 1.3 A and 1.9 A) crystal structures have been determined. These depict the nsLTP from maize seedlings in complex with an array of fatty acids.A detailed comparison of the structures of maize nsLTP in complex with various ligands reveals a new binding mode in an nsLTP-oleate complex which has not been seen before. Furthermore, in the caprate complex, the ligand binds to the protein cavity in two orientations with equal occupancy. The volume of the hydrophobic cavity in the nsLTP from maize shows some variation depending on the size of the bound ligands. The structural plasticity of the ligand binding cavity and the predominant involvement of non-specific van der Waals interactions with the hydrophobic tail of the ligands provide a structural explanation for the non-specificity of maize nsLTP. The hydrophobic cavity accommodates various ligands from C10 to C18. The C18:1 ricinoleate with its hydroxyl group hydrogen bonding to Ala68 possibly mimics cutin monomer binding which is of biological importance. Some of the myristate binding sites in human serum albumin resemble the maize nsLTP, implying the importance of a helical bundle in accommodating the non-specific binding of fatty acids.

Overexpression, crystallization and preliminary X-ray crystallographic analysis of dihydrofolate reductase from bacteriophage T4

Dihydrofolate reductase (DHFR) from bacteriophage T4 is a homodimer consisting of 193-residue subunits. It has been crystallized in the presence of the cofactor (NADPH) and an inhibitor (aminopterin) at 296 K using sodium chloride as precipitant. The crystals are tetragonal, belonging to the space group P4(1)22 (or P4(3)22), with unit-cell parameters a = b = 61.14, c = 123.23 A under cryogenic conditions. The asymmetric unit contains a single subunit, with a corresponding V(m) of 2.65 A(3) Da(-1) and a solvent content of 53. 6%. Native data have been collected from a crystal to 1.9 A resolution using synchrotron X-rays.

Crystallization and preliminary X-ray diffraction analysis of Saccharomyces cerevisiae Ygr203p, a homologue of Acr2 arsenate reductase

Ygr203p, a 148-residue protein encoded by the ygr203w gene of Saccharomyces cerevisiae, is a homologue of the yeast Acr2 arsenate reductase encoded by the acr2 (or ypr200c) gene. It also shows significant sequence similarity to the human cell-cycle control Cdc25 phosphatase family. It has been overexpressed in soluble form in Escherichia coli with a His(6) tag at its C-terminus. The recombinant protein has been crystallized at 296 K using sodium chloride as precipitant. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 40.48, b = 50.95, c = 91.95 A. The asymmetric unit contains a monomer, giving a crystal volume per protein mass (V(m)) of 2.61 A(3) Da(-1) and a solvent content of 53.8%. The crystals diffract to better than 1.9 A resolution with Cu Kalpha X-rays. They are therefore suitable for high-resolution structure determination.

Induction of G(1) cell cycle arrest and p27(KIP1) increase by panaxydol isolated from Panax ginseng

Polyacetylenic compounds of Panax ginseng roots have been shown to inhibit growth of several human malignant tumor cell lines. Panaxydol is known to be one of the cytotoxic polyacetylenic compounds of P. ginseng. In this study, we first showed that panaxydol decreased markedly the proliferation, and to a lesser extent, the number of cells in a human melanoma cell line, SK-MEL-1. Next, the effect of panaxydol on cell cycle progression and its mechanism of action were investigated. Cell cycle analysis revealed that panaxydol inhibited cell cycle progression of a human malignant melanoma cell line, SK-MEL-1, at G(1)-S transition. At the same time, panaxydol increased the protein expression of p27(KIP1) as early as 1 hr after treatment. Cyclin-dependent kinase 2 (Cdk2) activity was decreased in a dose-dependent manner after 24 hr of panaxydol treatment. Protein levels of p21(WAF1), p16(INK4a), p53, pRb (retinoblastoma protein), and E2F-1 were not changed. It was also found that cycloheximide reversed the growth inhibition induced by panaxydol and partially abrogated the increase in p27(KIP1) expression. These results indicate that panaxydol induces G(1) cell cycle arrest by decreasing Cdk2 activity and up-regulating p27(KIP1) protein expression.

Crystallization and preliminary X-ray crystallographic analysis of human nucleoside diphosphate kinase A

Human nucleoside diphosphate kinase A catalyzes phosphoryl transfer and acts as a suppressor of metastasis. It has been crystallized using 2-methyl-2,4-pentanediol as a precipitant at 288 K. The crystal is monoclinic, belonging to the space group P2(1), with unit-cell parameters a = 74.21, b = 78.11, c = 82.29 A, beta = 101. 33 degrees. The asymmetric unit contains a homohexamer, with a corresponding crystal volume per protein mass (V(m)) of 2.27 A(3) Da(-1) and a solvent content of 46%. Native X-ray data to 2.15 A resolution have been collected using synchrotron X-rays.

Crystal structure of NAD(+)-dependent DNA ligase: modular architecture and functional implications

DNA ligases catalyze the crucial step of joining the breaks in duplex DNA during DNA replication, repair and recombination, utilizing either ATP or NAD(+) as a cofactor. Despite the difference in cofactor specificity and limited overall sequence similarity, the two classes of DNA ligase share basically the same catalytic mechanism. In this study, the crystal structure of an NAD(+)-dependent DNA ligase from Thermus filiformis, a 667 residue multidomain protein, has been determined by the multiwavelength anomalous diffraction (MAD) method. It reveals highly modular architecture and a unique circular arrangement of its four distinct domains. It also provides clues for protein flexibility and DNA-binding sites. A model for the multidomain ligase action involving large conformational changes is proposed.

Crystal structure of a 16 kDa double-headed Bowman-Birk trypsin inhibitor from barley seeds at 1.9 A resolution

The Bowman-Birk trypsin inhibitor from barley seeds (BBBI) consists of 125 amino acid residues with two inhibitory loops. Its crystal structure in the free state has been determined by the multiwavelength anomalous diffraction (MAD) method and has been refined to a crystallographic R-value of 19.1 % for 8.0-1.9 A data. This is the first report on the structure of a 16 kDa double-headed Bowman-Birk inhibitor (BBI) from monocotyledonous plants and provides the highest resolution picture of a BBI to date. The BBBI structure consists of 11 beta-strands and the loops connecting these beta-strands but it lacks alpha-helices. BBBI folds into two compact domains of similar tertiary structure. Each domain shares the same overall fold with 8 kDa dicotyledonous BBIs. The five disulfide bridges in each domain are a subset of the seven disulfide bridges in 8 kDa dicotyledonous BBIs. Two buried water molecules form hydrogen bonds to backbone atoms in the core of each domain. One interesting feature of this two-domain inhibitor structure is that the two P1 residues (Arg17 and Arg76) are approximately 40 A apart, allowing the two reactive-site loops to bind to and to inhibit two trypsin molecules simultaneously and independently. The conformations of the reactive-site loops of BBBI are highly similar to those of other substrate-like inhibitors. This structure provides the framework for modeling of the 1:2 complex between BBBI and trypsin.

Insights into eukaryotic multistep phosphorelay signal transduction revealed by the crystal structure of Ypd1p from Saccharomyces cerevisiae

"Two-component" phosphorelay signal transduction systems constitute a potential target for antibacterial and antifungal agents, since they are found exclusively in prokaryotes and lower eukaryotes (yeast, fungi, slime mold, and plants) but not in mammalian organisms. Saccharomyces cerevisiae Ypd1p, a key intermediate in the osmosensing multistep phosphorelay signal transduction, catalyzes the phosphoryl group transfer between response regulators. Its 1.8 A structure, representing the first example of a eukaryotic phosphorelay protein, contains a four-helix bundle as in the HPt domain of Escherichia coli ArcB sensor kinase. However, Ypd1p has a 44-residue insertion between the last two helices of the helix bundle. The side-chain of His64, the site of phosphorylation, protrudes into the solvent. The structural resemblance between Ypd1p and ArcB HPt domain suggests that both prokaryotes and lower eukaryotes utilize the same basic protein fold for phosphorelay signal transduction. This study sheds light on the best characterized eukaryotic phosphorelay system.

Clinical significance of respiratory bronchiolitis on open lung biopsy and its relationship to smoking related interstitial lung disease

BACKGROUND

Respiratory bronchiolitis-associated interstitial lung disease (RBILD) is a rare form of interstitial lung disease which may present in similar fashion to other types of chronic interstitial pneumonia. The purpose of this study was to undertake a clinicopathological review of 10 patients with RBILD and to examine the clinical and imaging data related to its histopathological pattern, in particular the relationship of RBILD to smoking.

METHODS

Thirteen out of 168 retrospectively reviewed patients, from whom biopsy specimens were taken for suspected diffuse lung disease, were identified with a histopathological pattern of RBILD. Three cases were rejected as follow up data were unavailable. The 10 remaining cases constituted the study group and both clinical and imaging data were collected from patients' notes and referring physicians.

RESULTS

Histopathologically, four cases of RBILD overlapped with the pattern of desquamative interstitial pneumonitis (DIP) and nine also had microscopic evidence of centrilobular emphysema. Nine patients were smokers, ranging from 3 to 80 pack years. The one non-smoker had an occupational exposure to the fumes of solder flux. The sex distribution was equal with an age range of 32-65 years. Two patients were clubbed. Lung function tests showed both restrictive and obstructive patterns together with severe reductions in carbon monoxide transfer factor in seven patients. Chest radiographs showed reticular or reticulonodular infiltrates in five patients and a ground glass pattern in two. CT scans were consistent with either DIP or RBILD in six of eight patients. Although seven patients remained stable or improved, either with or without treatment, three patients deteriorated.

CONCLUSIONS

This study adds weight to the hypothesis that smoking can cause clinically significant interstitial lung disease, with deterioration in pulmonary function despite treatment. Given the overlapping histopathological patterns of RBILD and DIP and their strong association with smoking, the term "smoking related interstitial lung disease" is suggested for those patients who are smokers.

Heart rate variability of preterm neonates quantified by energy entropy

Identifying variables predictive of neurobehavioural sequelae is a key objective in the study of high-risk neonates. Examination of heart rate variability (HRV) characteristics may be a finer discriminator of the neonate's response to physiologic stressors than the mean heart rate. The energy entropy of the heart beat tachogram, computed in four different domains, was used to quantify the HRV in 13 preterm neonates. The entropies of energies were computed from 1024 interbeat time intervals obtained once per week from 26 to 35 weeks postconceptional age (PCA). The energy entropy computed in three of the domains, like the standard deviation of intervals, distinguished between the 10 neonates that were measured at 35 weeks PCA with 100% specificity and 67% sensitivity, but did not distinguish between healthy and unhealthy neonates at earlier ages. The findings suggest that energy entropy may be a discerning measure of physiologic stress in the preterm infant, although future research is needed to refine the test and determine statistical significance.

Crystallization and preliminary X-ray crystallographic analysis of deoxycytidylate hydroxymethylase from bacteriophage T4

Deoxycytidylate hydroxymethylase from bacteriophage T4 is a homodimeric enzyme in which each polypeptide chain consists of 246 amino-acid residues. It has been crystallized in the presence of its substrate, deoxycytidine monophosphate, at room temperature using sodium citrate as precipitant. The crystals are monoclinic, belonging to space group C2, with unit-cell parameters a = 174.22, b = 53.12, c = 75.17 A, beta = 115.29 degrees. The asymmetric unit contains one homodimer, with a corresponding Vm of 2.65 A3 Da-1 and solvent content of 54%. Native diffraction data to 1.6 A resolution have been collected from two crystals using synchrotron radiation.

Characterization of the gene encoding catechol 2,3-dioxygenase from Achromobacter xylosoxidans KF701

Catechol 2,3-dioxygenase (C23O) catalyzes a meta cleavage of the aromatic ring in catechol to form 2-hydroxymuconic semialdehyde. A C23O gene was cloned from chromosomal DNA of A. xylosoxidans KF701, a soil bacterium degrading biphenyl, and expressed in E. coli HB101. In substrate specificity to catechol and its analogs, the C23O exhibited the highest aromatic ring-fission activity to catechol, and its relative activity to other dihydroxylated aromatics was 4-chlorocatechol > 4-methylcatechol > 3-methylcatechol >> 2, 3-dihydroxybiphenyl. Aromatic ring-fission activity of the C23O to catechol was about 40-fold higher than that to 2,3-dihydroxybiphenyl. Nucleotide sequence analysis of the C23O gene from A. xylosoxidans KF701 revealed an open reading frame consisting of 924 base pairs, and identified a putative ribosome-binding sequence (AGGTGA) at about 10 nucleotides upstream from the initiation codon. The open reading frame can encode a polypeptide chain with molecular weight of 34 kDa containing 307 amino acid residues. The deduced amino acid sequence of the C23O exhibited the highest homology with that of C23O from Pseudomonas sp. IC with 96% identity, and the least homology with that of C23O from P. putida F1 with 22% identity among reported C23O sequences. Furthermore, comparison of the C23O sequence with other extradiol dioxygenases has led to identification of evolutionally conserved amino acid residues whose possible catalytic and structural roles are proposed.

Characterization of the gene encoding catechol 2,3-dioxygenase of Alcaligenes sp. KF711: overexpression, enzyme purification, and nucleotide sequencing

Catechol 2,3-dioxygenase (C23O) is an extradiol-type dioxygenase that catalyzes the aromatic ring fission of catechol to form 2-hydroxymuconic semialdehyde. The C23O gene of Alcaligenes sp. KF711 was overexpressed in Escherichia coli HB101 by using the lac promoter of pUC18, and its gene product was purified by using immunoaffinity chromatography. The purified C23O exhibited a 35-kDa single band on an SDS-polyacrylamide gel, and its ring-fission activity on dihydroxylated aromatics was 4-methylcatechol > 4-chlorocatechol > catechol > 3-methylcatechol >> 2,3-dihydroxybiphenyl. Nucleotide sequence analysis of the C23O gene revealed an open reading frame of 927 bp, which can encode a polypeptide of 308 amino acid residues. The predicted molecular mass of 35 kDa is in agreement with that of purified C23O on an SDS-polyacrylamide gel. The amino acid sequence of the C23O was compared with those of nine other extradiol-type dioxygenases, including 2,3-dihydroxybiphenyl dioxygenase (2,3-DHBD) and 1,2-dihydroxynaphthalene dioxygenase (1,2-DHND). The C23O of Alcaligenes sp. KF711 exhibited 80 to 94% identity in amino acid sequence with other C23Os, and 20 to 25% identity with 1,2-DHND and 2,3-DHBDs. Furthermore, sequence comparison of 10 extradiol-type dioxygenases has led to identifying 19 evolutionarily conserved amino acid residues whose possible catalytic roles are proposed.

Is respiratory sinus arrhythmia a good index of cardiac vagal tone in exercise?

To assess the relative roles of neural and nonneural mechanisms in respiratory sinus arrhythmia (RSA) at rest and during exercise (steady-state supine cycle ergometry at 25% of peak oxygen uptake), we studied 10 healthy men (mean age 21 +/- 1 yr) before (control) and during ganglion blockade (GB) with trimetaphan camsylate (3-5 mg/min i.v.). GB was confirmed by the abolition of the reflex bradycardia in response to intravenous phenylephrine and of the blood pressure rise with the cold pressor test. RSA was calculated from the power of the spectral component of the R-R interval variability centered at the breathing frequency. GB decreased but did not abolish RSA. At rest, this nonneural component of RSA was negligible, accounting for < 1% of the control RSA. During GB, exercise did not affect RSA significantly. However, because control RSA was decreased by exercise, the proportion of nonneural RSA increased by 32% (range from 17 to 75%). These results indicate that as the vagal tone decreases with exercise, an increasing proportion of RSA is due to nonneural mechanisms.

A comparison of test-retest variability of caloric induced nystagmus in a normal population using an air stimulus presented via a standard and modified irrigating probe

The caloric test has traditionally been carried out using water. Air caloric techniques have been available for some time but one of the reported disadvantages is the high variability of response (Coats et al., 1976). The aim of this study was to compare the test-retest variability of the air caloric response using a normal irrigation probe and a modified probe. The modified probe allowed observation of the placement of the probe tip within the ear canal and could be used to observe the direction of air flow during the irrigation. It was found that the variability with the modified probe is smaller than with the normal probe.

Isolation of a root-specific cDNA encoding a ns-LTP-like protein from the roots of bean (Phaseolus vulgaris L.) seedlings

A root-specific cDNA clone, PVR3, was isolated from a bean (Phaseolus vulgaris L.) root cDNA library by a differential screening procedure. The nucleotide sequence of PVR3 contains an open reading frame coding for an 11.14 kDa polypeptide of 102 amino acid residues; the first 25 amino acids correspond to the sequence characteristic of a signal peptide. Comparison of the deduced PVR3 polypeptide sequence with the polypeptide sequences of previously cloned genes indicates that PVR3 may encode a ns-LTP-like protein. Molecular modelling of the PVR3 protein predicts that it has a three-dimensional structure that is similar to the three-dimensional model determined from the maize ns-LTP. The PVR3 mRNA accumulated mainly in the roots of young seedlings. It can be detected at low levels in flowers, but it is not detected in other organs. Genomic Southern blot analysis indicates that the genomic DNA corresponding to PVR3 cDNA is encoded by a single gene or small gene family in the bean genome.

Hematopoietic potential of cryopreserved and ex vivo manipulated umbilical cord blood progenitor cells evaluated in vitro and in vivo

The hematopoietic potential of cryopreserved and ex vivo manipulated umbilical cord blood (UCB) samples was evaluated in vitro and in vivo. Phenotypic analysis shows that approximately 1% of cord blood mononuclear cells express high levels of CD34 antigen on their surface (CD34hi), but none of a panel of lineage antigens (Lin-), suggesting that they are hematopoietic progenitor cells that have not yet committed to a specific lineage. Approximately 1% of CD34hi/Lin- cells are primitive hematopoietic progenitors that produce B lymphoid and multiple myeloid progeny for up to 7 weeks in stromal cell cultures. Twenty-one percent (+/- 13%) of CD34hi/Lin- cells also express low levels of the Thy-1 antigen and are threefold to fourfold enriched over CD34hi/Lin- cells in primitive hematopoietic potential as measured by long-term culture and phenotypic analysis. One-week liquid cultures of CD34-enriched UCB progenitor cells in the presence of interleukin (IL)-3, IL-6, and stem cell factor (SCF) results in a two-fold to threefold expansion of progenitors capable of reinitiating long-term stromal cell cultures. Only the CD34hi/Thy-1+/Lin- cell population was capable of maintaining progenitors with secondary transfer potential in long-term stromal cell cultures and is thus postulated to contain all of the primitive hematopoietic stem cells in UCB. The in vivo transplantation potential of UCB was also measured. Ex vivo manipulated UCB progenitor cells were used to engraft irradiated human thymus fragments implanted in severe combined immunodeficiency (SCID) mice. Thymic engraftment with >5% donor-derived cells and a normal CD4/CD8 distribution was observed in 19 of 23 tissues tested. UCB cells from in vitro expansion cultures engrafted with efficiencies comparable to nonexpanded cells. Similar results were obtained for UCB engraftment of human bone fragments implanted in SCID mice. In all cases, engraftment was achieved in competition with endogenous competitor stem cells and across major histocompatibility barriers. Taken together, this data demonstrates that human UCB is a rich source of multipotent hematopoietic progenitors that can be cryopreserved, enriched by physical methods, and expanded in a limited fashion without measurable loss of long-term culture or in vivo engrafting potential as measured in these assays.

Taurine intake of Korean breast-fed infants during lactation

i. Taurine concentrations of human milk of nonvegetarians and lacto-ovovegetarians decreased significantly during the course of lactation. Taurine concentrations in lacto-ovovegetarians after 90 days postpartum were lower than those of nonvegetarians. Taurine concentrations of human milk by 150 days postpartum were: nonvegetarian 248-434 nmol/ml (31.0-54.4 mg/L); lacto-ovovegetarian 153-418 nmol/ml (19.1-52.3 mg/L). ii. Taurine intakes in infants of lacto-ovovegetarians decreased significantly during lactation, unlike from the pattern in infants of nonvegetarians. Taurine intakes in infants of lacto-ovovegetarians at 90, 120 and 150 days postpartum were lower, compared with those in nonvegetarians. Taurine intakes in infants by 150 days postpartum were: Infants of nonvegetarians 169-229 mumol/day (21.1-28.6 mg/day); Infants of lacto-ovovegetarians 106-210 mumol/day (21.1-28.6 mg/day). iii. This study showed that the taurine concentration in human milk and the taurine intake of infants were different during lactation between nonvegetarians and lacto-ovovegetarians, and that the intake per kg body weight decreased during lactation. Results suggest that the differences observed might be due to the effect of consumption of different types of food.

The efficiency of translation termination is determined by a synergistic interplay between upstream and downstream sequences in Saccharomyces cerevisiae

In a recent study we found that the efficiency of translation termination could be decreased several hundred fold by altering the local sequence context surrounding stop codons in the yeast Saccharomyces cerevisiae. Suppression of termination was shown to be mediated by near-cognate tRNA mispairing with the termination codon. We have now examined in greater detail how the local sequence context affects the efficiency of translation termination in this organism. Our results indicate that the sequence immediately upstream of the termination codon plays a significant role in determining the efficiency of translation termination. An extended termination sequence (containing the stop codon and the following three nucleotides) was also found to be a major determinant of termination efficiency, with effects attributable to the fourth nucleotide being largely independent of the termination codon. For the UGA and UAA stop codons, the influence of the fourth position on termination efficiency (from most efficient to least efficient termination) was found to be G > U,A > C, while for the UAG codon it was U,A > C > G. These sequence-specific effects on the efficiency of translation termination suggest that polypeptide chain release factor (or another molecule that may play a role in translation termination, such as rRNA) recognizes an extended termination sequence in yeast. A previous study found a statistically significant bias toward certain tetranucleotide sequences (containing the stop codon and the first distal nucleotide) in several organisms. We found that tetranucleotide sequences most frequently used in yeast are among the most efficient at mediating translation termination, while rare tetranucleotide sequences mediate much less efficient termination. Taken together, our results indicate that upstream and downstream components of an extended sequence context act synergistically to determine the overall efficiency of translation termination in yeast.

Cloning and sequencing of the catechol 2,3-dioxygenase gene of Alcaligenes sp. KF711

The catechol 2,3-dioxygenase is an aromatic ring-fission enzyme catalyzing the conversion of catechol to 2-hydroxymuconic semialdehyde. A catechol 2,3-dioxygenase gene has been cloned from chromosomal DNA of Alcaligenes sp. KF711, and its sequence was determined. The catechol 2,3-dioxygenase gene was consisted of 927 nucleotides with ATG initiation codon and TGA termination codon, which can encode a polypeptide of molecular weight 35 kDa containing 308 amino acid residues. G+C content of the gene was 58 mol%, and a putative ribosome-binding sequence was identified at about 10 nucleotides upstream from the ATG initiation codon. The sequence of catechol 2,3-dioxygenase from Alcaligenes sp. KF711 exhibited 81-92% homology at nucleotide level and 84-92% homology at amino acid level with those of corresponding enzymes encoded in xylE of TOL plasmid, nahH of NAH7 plasmid, and dmpB of Pseudomonas CF600.

The role of vitamin D in toxic metal absorption: a review

Vitamin D increases intestinal calcium and phosphate absorption. Not so well known, however, is that vitamin D stimulates the co-absorption of other essential minerals like magnesium, iron, and zinc; toxic metals including lead, cadmium, aluminum, and cobalt; and radioactive isotopes such as strontium and cesium. Vitamin D may contribute to the pathologies induced by toxic metals by increasing their absorption and retention. Reciprocally, lead, cadmium, aluminum, and strontium interfere with normal vitamin D metabolism by blocking renal synthesis of 1,25-dihydroxyvitamin D. This is the first review of the role of the vitamin D endocrine system in metal toxicology.

Among a range of transition metals and ligands vanadium.desferroxamine excels in accelerating reactivity of ferrocytochrome c toward molecular oxygen

Despite early knowledge of the requirement for metals in the reactions of ferrocytochrome c with oxygen, the relative effectiveness of metals and the factors that modulate effectiveness remain unknown. We have compared the catalytic power of five metals and report the effects of pH and ligand on their effectiveness as catalysts. Catalysis by metal ions was greatest at higher pH, where the rate of aerobic oxidation was lowest. Iron (Fe2+), copper (Cu2+), vanadium(V) (V(V)), manganese (Mn2+), and aluminum (Al3+) were tested in combination with EDTA, ADP, histidine, or desferrioxamine (Des) at pH 2.6, 3.2, and 4.0. At pH 2.6, only vanadium(V) increased the initial rate of the oxidation of ferrocytochrome c (by 6.2-fold). At pH 4.0, however, all the metals markedly stimulated the oxidation of cytochrome c. The order of effectiveness was V(V).Des >> Cu.ADP2+ > Fe.EDTA2+ > Mn.Des2+ > Al.EDTA3+ (where the stated ligand represents the most stimulating one for a given metal). At pH 3.2 the metal complexes had intermediate effects, with vanadium again being the most effective. The preeminence of vanadium among the metals is novel. Where the heme crevice is closed (pH 4), transition metal ions mediated almost all of the reduction of oxygen, while at the lowest pH (2.6) transition metal ions were largely unnecessary. Vanadium(V) was the most active of the metals at all values of pH and the only metal to accelerate the oxidation of ferrocytochrome c at pH 2.6. Understanding of the range of biological actions of vanadium will not be complete without a knowledge of its redox reactivity within the components of biological systems.

Laparoscopically assisted vaginal hysterectomy as definitive therapy for stage III and IV endometriosis

Operative laparoscopy combined with vaginal hysterectomy and salpingo-oophorectomy was used to treat advanced endometriosis in 40 of 46 patients. This treatment plan was abandoned in favor of laparotomy in six patients. Of the 40 patients successfully treated by laparoscopically assisted vaginal hysterectomy, 39 are completely free of symptoms. Major complications, including blood loss requiring transfusion and injury to the ureter or bowel, were sustained at acceptable rates. No serious infections occurred. The mean operating time was 191 minutes. Laparoscopically assisted vaginal hysterectomy and removal of all ovarian tissue combined with excision of all endometriosis may be used as definitive therapy for advanced endometriosis. The major complications associated with surgical therapy for high-stage endometriosis are encountered; therefore, laparoscopic treatment requires advanced laparoscopic surgical skills.

Vanadium as a modulator of cellular regulatory cascades and oncogene expression

Vanadium, a trace metal in the environment and in biological systems, influences the behavior of enzymes, mimics and regulates growth factor activity, is a potential mutagenic and carcinogenic agent, and regulates gene expression. The diverse biological actions of vanadium result from its capacity to function as an oxyanion, oxycation, or prooxidant. Vanadium is found in water, rocks, and soils in low concentration and in relatively high concentrations in coal and oil deposits. Vanadium compounds at much higher concentrations than are typically ingested are being considered in the treatment of diabetes mellitus. The actions of insulin and vanadium on the insulin receptor are similar, but the mechanisms are not identical. Vanadium modulates growth-factor-mediated signal transduction pathways. Vanadium promotes cell transformation and diminishes cell adhesion. Consistent with its mitogenic action and its capacity to mimic mitogenic growth factors, vanadium stimulates expression of protooncogenes. In particular, oxygen-derived active species are involved in the expression of the jun protooncogene in the presence of vanadium. The unique cellular activity of vanadium makes it a tool of unparalleled potential for studying mechanisms of cell growth, differentiation, and metabolism.

Effects of ligands on reduction of oxygen by vanadium(IV) and vanadium(III)

V(IV) and V(III) reduce molecular oxygen with increasing rates as the pH is raised from 6.0 to 7.4. Under all conditions tested, V(IV) is the more efficient reductant. EDTA and ATP generally inhibit the reduction of oxygen by V(III) and V(IV). In contrast, desferrioxamine accelerates the reduction of oxygen by V(IV) but with decreasing effectiveness at pH 7.4 compared to pH 6.0, while desferrioxamine accelerates the reduction of oxygen by V(III) only at pH 6.0. Histidine enhances the reduction of oxygen by V(IV) at pH 7.0 and 7.4. The observed rates of oxygen reduction by V(III) and V(IV) imply that the intracellular distribution of vanadium among its redox states reflects not an equilibrium but a steady state.