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DNA-templated nanofabrication presents an innovative approach to creating self-assembled nanoscale metal–semiconductor-based Schottky contacts, which can advance nanoelectronics. Herein, we report the successful fabrication of metal–semiconductor Schottky contacts using a DNA origami scaffold. The scaffold, consisting of DNA strands organized into a specific linear architecture, facilitates the competitive arrangement of Au and CdS nanorods, forming heterojunctions, and addresses previous limitations in low electrical conductance making DNA-templated electronics with semiconductor nanomaterials. Electroless gold plating extends the Au nanorods and makes the necessary electrical contacts. Tungsten electrical connection lines are further created by electron beam-induced deposition. Electrical characterization reveals nonlinear Schottky barrier behavior, with electrical conductance ranging from 0.5 × 10–4to 1.7 × 10–4S. The conductance of these DNA-templated junctions is several million times higher than with our prior Schottky contacts. Our research establishes an innovative self-assembly approach with applicable metal and semiconductor materials for making highly conductive nanoscale Schottky contacts, paving the way for the future development of DNA-based nanoscale electronics.

Copper(II) is known to bind in the influenza virus His37 cluster in the homotetrameric M2 proton channel and block the proton current needed for uncoating. Copper complexes based on iminodiacetate also block the M2 proton channel and show reduced cytotoxicity and zebrafish-embryo toxicity. In voltage-clamp oocyte studies using the ubiquitous amantadine-insensitive M2 S31N variant, the current block showed fast and slow phases, in contrast to the single phase found for amantadine block of wild-type M2. Here, we evaluate the mechanism of block by copper adamantyl iminodiacitate and copper cyclooctyl iminodiacitate complexes and address whether the complexes can coordinate with one or more of the His37 imidazoles. The current traces were fitted to parametrized master equations. The energetics of binding and the rate constants suggest that the first step is copper complex binding within the channel, and the slow step in the current block is the formation of a Cu-histidine coordination complex. Solution-phase isothermal titration calorimetry and density functional theory (DFT) calculations indicate that imidazole binds to the copper complexes. Structural optimization using DFT reveals that the complexes fit inside the channel and project the Cu(II) toward the His37 cluster, allowing one imidazole to form a coordination complex with Cu(II). Electrophysiology and DFT studies also show that the complexes block the G34E amantadine-resistant mutant despite some crowding in the binding site by the glutamates.

Following our call to join in the discussion over the suitability of implementing a reporting checklist for bio–nano papers, the community responds.

The character of an organization, according to this author, is rooted in its ideological orientation. He postulates four separate ideologies that determine (a) the compatibility of an organization's interests with those of its members and (b) an organization's ability to deal with the external environment. He argues, moreover, that the failure to understand ideological differences often causes conflict between organizations as well as within them. After discussing the different ideologies and the types of organizations they embody, the author presents an overall framework for determining the optimum ideological fit of organizational interests and human interests. [ABSTRACT FROM PUBLISHER]

In about the time it takes to consume the hors d'oeuvres in the business-class cabin of a modern jetliner, the traveler passes from oil-rich Saudi Arabia west across the Red [...]

It long has been axiomatic that, as a country develops, the maintenance and protection of the natural environment gives way to the development of an industrial and technological infrastructure. The [...]

Arab countries have become synonymous with oil production and wealth. With only 4.5 percent of the world's population, they control up to half the world's oil supply. Less well known, [...]

On a carefully landscaped site carved out of a wadi some 18 miles north of Riyadh stands a complex of modern buildings. Apart from the official-looking gateway, the Humanitarian City [...]

A fire fighting shaft typically provides a protected enclosure, containing a stairwell and, at each storey served by the shaft, a lobby separating the stairwell and accommodation in a fire [...]

Companies that harness their employees' personal energies do so because they elicit a shared sense of purpose. One of the most powerful tools for generating employee commitment is an agreed-upon organizational mission. Guidelines are presented for channeling employee energies into the organization. A model of a supportive corporate culture is developed and compared to power-oriented cultures, role-oriented cultures, and achievement oriented cultures. The ideal culture is a balance between achievement, role, and support orientations.

This paper describes a project designed to quantify the extent to which existing competency frameworks used for educating the public health workforce contribute to achieving the Sustainable Development Goals (SDGs) directly relevant to public health.

ABSTRACTGroup-based parent training is a well-established, empirically supported treatment for externalizing problems, but few studies have examined the outcomes of this approach in real-world, clinically representative outpatient samples. In addition, many families experience barriers to program attendance in outpatient settings. The purpose of this study was to examine pretreatment to posttreatment clinical outcomes of parent training and child social skills groups, as well as sociodemographic moderators of group outcomes, attendance, and attrition, among a large, diverse sample of families attending 8-week group treatment at an outpatient pediatric hospital. Two hundred thirty-three children ages 4–10 years and their parent reporters participated in 28 concurrent parent–child groups. Parent pretreatment and posttreatment ratings of child disruptive behavior and related parental stress were available for 158 families (Mchild age = 7.25 years, SD= 1.54; 77.8% male). Children showed significant pretreatment to posttreatment reductions in parent-reported child behavior problems and related stress, with small to medium effect sizes. Results showed little variation by sociodemographic moderators. Pretreatment maternal stress experience was associated with retention in treatment among families with both mother and father reporters attending treatment sessions, whereas across all mother reporters a higher degree of pretreatment child-related stress was associated with increased likelihood of group attrition. Medicaid insurance status was associated with increased likelihood of attrition across the full sample of families. The clinical implications of these results and related practice points for enhancing implementation of and patient retention in outpatient parent–child groups are discussed.

The bleak prognosis associated with pancreatic cancer (PDAC) drives the need for the development of novel treatment methodologies. Here, we evaluate the applicability of 3 enzyme prodrug therapies for PDAC, which are simultaneously targeted to the tumor, tumor vasculature, and metastases via annexin V. In these therapies, annexin V is fused to an enzyme, creating a fusion protein that converts nontoxic drug precursors, prodrugs, into anticancer compounds while bound to the tumor, therefore mitigating the risk of side effects.

We used heparosan (HEP) polysaccharides for controlling nanoparticle delivery to innate immune cells. Our results show that HEP-coated nanoparticles were endocytosed in a time-dependent manner by innate immune cells via both clathrin-mediated and macropinocytosis pathways. Upon endocytosis, we observed HEP-coated nanoparticles in intracellular vesicles and the cytoplasm, demonstrating the potential for nanoparticle escape from intracellular vesicles. Competition with other glycosaminoglycan types inhibited the endocytosis of HEP-coated nanoparticles only partially. We further found that nanoparticle uptake into innate immune cells can be controlled by more than 3 orders of magnitude via systematically varying the HEP surface density. Our results suggest a substantial potential for HEP-coated nanoparticles to target innate immune cells for efficient intracellular delivery, including into the cytoplasm. This HEP nanoparticle surface engineering technology may be broadly used to develop efficient nanoscale devices for drug and gene delivery as well as possibly for gene editing and immuno-engineering applications.

To evaluate the epidemiologic evidence for a causal association between tobacco smoking and primary open angle glaucoma (POAG).

ObjectiveCommunity pharmacists have a central role in provision of smoking‐cessation support. Evidence is growing that tobacco smoking is associated with development and progression of several potentially blinding eye diseases. As part of an ongoing programme of raising awareness of this link, we investigated whether community pharmacists are aware of this association and incorporate relevant advice into their smoking‐cessation guidance.

Tissue factor (TF) initiates blood coagulation, but its expression in the vascular space requires a finite period of time. We hypothesized that targeting exogenous tissue factor to sites of vascular injury could lead to accelerated hemostasis. Since phosphatidylserine (PS) is exposed on activated cells at sites of vascular injury, we cloned the cDNA for a chimeric protein consisting of the extracellular domain of TF (called soluble TF or sTF) and annexin V, a human PS-binding protein. Both the sTF and annexin V domains had ligand-binding activities consistent with their native counterparts, and the chimera accelerated factor X activation by factor VIIa. The chimera exhibited biphasic effects upon blood coagulation. At low concentrations it accelerated blood coagulation, while at higher concentrations it acted as an anticoagulant. The chimera accelerated coagulation in the presence of either unfractionated or low-molecular-weight heparins more potently than factor VIIa and shortened the bleeding time of mice treated with enoxaparin. The sTF-annexin V chimera is a targeted procoagulant protein that may be useful in accelerating thrombin generation where PS is exposed to the vasculature, such as may occur at sites of vascular injury or within the vasculature of tumors.

Sonic spray ionization mass spectrometry (SSI MS) is shown to be effective in characterizing metal-assembled cage structures that are not observed using conventional electrospray ionization mass spectrometry (ESI MS) techniques. A palladium-assembled resorcinarene-based cage containing nitrile ligands and a palladium(ii) triazine cage were characterized and their +1 molecular ion peaks were observed using this method. An N,N-bis(pyridylmethyl)amine resorcinarene cavitand–metal ion complex was observed to yield peaks corresponding to open tetranuclear complexes and closed cage complexes depending on the metal ion. Molecular ion peaks for these complexes were not detected when ESI MS was used. The soft ionization inherent in SSI MS coupled with its relatively simple design provides a powerful tool to characterize such supramolecular assemblies, which are of current interest.

Metal‐assembled resorcinarene‐based cages enclose space and entrap organic molecules from water. Addition of cobalt(II) ions to a neutral, aqueous solution of a resorcinarene that has iminodiacetic acids attached to its upper rim results in the formation of cages. These cages not only entrap organic molecules, but they do so in a selective manner. Guests with optimum size, shape, and polarity are preferentially entrapped. For example, selection of p‐xylene is twenty thousand times more favorable than that of m‐xylene. The enthalpy of resorcinarene deprotonation and cage formation was calculated by performing calorimetry studies and ranged from −305 to −348 kJ mol−1. The change in enthalpy of guest encapsulation varied by as much as 43 kJ mol−1. The differences in change in free energy of guest encapsulation varied by −16 kJ mol−1. The changes in enthalpy and free energy of guest encapsulation were used to calculate the changes in entropy, which ranged from −97 to +37 J mol−1K−1. An enthalpy–entropy compensation of guest encapsulation was observed.

In the UK, the Department of Health recognizes the importance of research activity to improve patient care, but the amount of research activity relating to primary care is scant. Few have considered managerial and organizational aspects relating to developing research capacity in primary care and none have examined this from the perspective of organizations responsible for managing primary care at a local level. Yet these organizations have a critical role in increasing the amount of appropriate health services research and developing a research culture. A qualitative analysis of focus group workshops was performed to identify issues associated with developing research capacity within a primary care trust (PCT) covering a single local authority borough in England. All staff attached to the PCT were invited to attend facilitator-led focus groups and asked to consider from an individual and organizational perspective: What will enable them to increase the use of and participation in research? What barriers exist? What opportunities exist or could exist to develop this in the PCT? Themes were identified using content analysis based on written records from the focus groups. Issues relating to developing research capacity were grouped into the following categories: What is research? Training; Resources; Managerial; and Organizational issues. Research was not seen as an integral component of the daily or routine work of most people in a health care organization. Managerial and organizational issues were a considerable barrier to developing research capacity. Lack of appreciation and support for research by managers and lack of structures to facilitate research within the organization prevented research capacity being developed. Primary care management organizations need to work with service managers to encourage the incorporation of research activity into the routine work of staff. Greater dialogue is needed between individuals, service managers and academics to ensure that appropriate research is carried out to support the organization in meeting its explicit objectives. More work is needed to understand the perceptions of research from a managers’ perspective and to develop constructive ways to gain their support for a research agenda.

XOR (xanthine oxidoreductase) purified from human milk was shown to contain 0.04 atom of Mo and 0.09 molecule of molybdopterin/subunit. On the basis of UV/visible and CD spectra, the human enzyme was approx. 30% deficient in iron-sulphur centres. Mo(V) EPR showed the presence of a weak rapid signal corresponding to the enzyme of low xanthine oxidase activity and a slow signal indicating a significant content of desulpho-form. Resulphuration experiments, together with calculations based on enzymic activity and Mo content, led to an estimate of 50–60% desulpho-form. Fe/S EPR showed, in addition to the well-known Fe/S I and Fe/S II species, the presence of a third Fe/S signal, named Fe/S III, which appears to replace partially Fe/S I. Comparison is made with similarly prepared bovine milk XOR, which has approx. 15-fold higher enzymic activity and Mo content. Taken along with evidence of low Mo content in the milk of other mammals, these findings add further support to the idea that XOR protein plays a physiological role in milk (e.g. in secretion) equal in importance to its catalytic function as an enzyme.

OBJECTIVE: Many studies have examined the role of diet in the management of established rheumatoid arthritis (RA), warranting several recent reviews. However, none have considered the possible link between diet and the onset of RA in detail. Studies investigated a possible effect of individual components of diet and the development of RA, but the lack of a systematic review means there is no unbiased assessment of the evidence. METHODS: We systematically reviewed studies with comparison groups that examined dietary intake or biological markers prior to the onset of RA. Four electronic databases were searched to identify relevant reports. Six quality criteria were agreed, against which the studies were assessed. The main outcome measure was a diagnosis of RA according to the ARA 1958 or revised ACR 1987 classification criteria. RESULTS: Fourteen reports were included in the review. There was evidence of a protective effect of higher consumption of olive oil, oil-rich fish, fruit, vegetables and β-cryptoxanthin. Lower serum concentrations of antioxidants were associated with an increased risk of RA in 3 studies. Due to the heterogeneity of study designs and analyses, the results could not be pooled. CONCLUSION: Evidence exists that diet may play a role in the etiology of RA, but it is inconclusive due to the small number of studies available and variation in study design.

Reaction of 1-phenyl 5-(aminophenyl) 9-(2-pyridyl) benzimidazole derivatives (2)with cis-Ru(bpy)2Cl2in MeCN results in the formation of N-(aryl) imidazo[1,5a] pyridine derivatives (4)and cis-[Ru(bpy)2(MeCN)2]2+(5). Crystal structures of N-(4-chlorophenyl) imidazo[1,5a] pyridine (4b)and cis-[Ru(bpy)2(MeCN)2](ClO4)2(5)are also reported.

Xanthine oxidoreductase (XOR) is progressively inactivated while catalysing the reduction of inorganic nitrite to NO by xanthine. Inactivation results from conversion of the enzyme into its desulpho-form. The rate of inactivation increases with nitrite concentration. Similar behaviour was shown when NADH replaced xanthine as reducing substrate. A kinetic model is proposed incorporating a ‘suicide’ inactivation involving an enzyme–substrate (product) complex, rather than inactivation by free NO. The model provides a good fit to progress curves of the reaction of xanthine or NADH with nitrite in the presence of the oxidase or dehydrogenase forms of the enzyme. Inorganic nitrate, like nitrite, was shown to be reduced at the molybdenum site of XOR. With xanthine as reducing substrate, nitrite was produced in essentially a 1:1 stoichiometric ratio with respect to urate. Unlike the case of nitrite, the enzyme was not significantly inactivated, implying that inactivation during nitrite reduction depends on the presence of nascent NO in its enzyme complex.

This article draws on the analysis from a 2-year empirical study of flexibility in further education. It outlines some of the major themes for managers and staff in attempts to introduce greater organisational flexibility into colleges: increased bus(i/y)ness, shifting identities, and notions of good and bad flexibility. The analysis suggests that insofar as increased 'busyness' is associated with shifting roles and responsibilities with consequent shifts in identity, for those who have worked in further education for some time there is a tendency to certain forms of nostalgic narratives about the good forms of flexibility in the past, compared with the present. The interview data suggests a complex picture of the ways in which flexibility is experienced in further education.

The air-stable complex [Fe(6-Me₃-TPA)(O₂CAr)]⁺ [1; 6-Me₃-TPA=tris(6-methyl-2-pyridylmethyl)amine] has been synthesized as a model for the iron(II) site of lipoxygenase. This iron(II) complex reacts with 0.5 equiv ROOH to form a yellow species, which has been formulated as [Fe^III(OH)(6-Me₃-TPA)(O₂CAr)]⁺ (2) by electrospray mass spectrometry. Addition of more ROOH converts 2 into a purple species, which is characterized by electrospray ionization mass spectrometry and resonance Raman spectroscopy as [Fe^III(OOR)(6-Me₃-TPA)(O₂CAr)]⁺. The purple species is metastable and decomposes via Fe-O bond homolysis to regenerate the starting iron(II) complex. These metal-centered transformations parallel the changes observed for lipoxygenase in its reaction with its product hydroperoxide.

A new 7,16‐bis(quinolin‐8‐ylmethyl)‐1,4,10,13‐tetraoxa‐7,16‐diazacyclooctadecane ligand, L, has been prepared and its crystal structure reported. In addition, the structure of the protonated ligand H2L has been determined. H2L is of interest because of interatomic interactions between the ligand and perchlorate ions. The mononuclear Ba(II) (BaL), and dinuclear Cu(II) (Cu2L) complexes of Lhave been prepared and their crystal structures determined. Stability constants and other thermodynamic data valid in methanol at 23 or 25° for these and several other complexes of Lhave been obtained. Among the metal ions studied, Lforms the most stable complex with Ba2+. In addition, Lselectively binds Cu2+over Ni2+by about 3 orders of magnitude. Some of the complexes have been studied using nmr and uv‐vis spectroscopic techniques. Crystal data are given for L, space group, P21c, a = 8.8325(14) Å, b = 13.808(3) Å, c = 13.310(3) Å; β = 94.72(2)° Z=2, R = 0.0727; for H2L, space group, P21/c, a = 14.685(3) Å, b = 15.035(6) Å, c = 17.369(4) Å, β = 90.366(12)°, Z = 4, R = 0.0781; for BaL, space group, Pbcn, a = 17.314(3) Å, b = 9.539(2) Å, c = 22.081(3) Å, Z = 4, R = 0.0354; and for Cu2L, space group, Cc, a = 19.762(2) Å, b = 14.413(2) Å, c = 14.935(2) Å, β = 98.753(12)°, Z = 4, R = 0.0564. Cu2+forms a hydroxo‐bridged dinuclear complex with Lwhile Ba2+forms a mononuclear complex with Lin which its two side arms are not involved in complexation.

Peroxynitrite, a potent oxidising, nitrating and hydroxylating agent, results from the reaction of nitric oxide with superoxide. We show that peroxynitrite can be produced by the action of a single enzyme, xanthine oxidoreductase (XOR), in the presence of inorganic nitrite, molecular oxygen and a reducing agent, such as pterin. The effects of oxygen concentration on peroxynitrite production have been examined. The physiologically predominant dehydrogenase form of the enzyme is more effective than the oxidase form under aerobic conditions. It is proposed that XOR‐derived peroxynitrite fulfils a bactericidal role in milk and in the digestive tract.

Xanthine oxidase (XO) was shown to catalyze the reduction of isoamyl and isobutyl nitrites to nitric oxide (NO) in the presence of xanthine under anaerobic conditions. NO was produced at a stoichiometric ratio of 2:1 versus urate generation, steady-state analysis of which showed Michaelis–Menten kinetics with xanthine as varied substrate and substrate inhibition with varied organic nitrite. Under the conditions of NO generation from isoamyl nitrite, XO was progressively inactivated by a mechanism involving conversion of Mo&z.dbnd;S to Mo&z.dbnd;O, yielding “desulfo” enzyme. It is proposed that XO is involved in the metabolism of organic nitrites to NO in vivo and that the observed inactivation serves to explain the phenomenon of tolerance.

Xanthine oxidase (XO) was shown to catalyze the reduction of nitrite to nitric oxide (NO), under anaerobic conditions, in the presence of either NADH or xanthine as reducing substrate. NO production was directly demonstrated by ozone chemiluminescence and showed stoichiometry of approximately 2:1 versusNADH depletion. With xanthine as reducing substrate, the kinetics of NO production were complicated by enzyme inactivation, resulting from NO-induced conversion of XO to its relatively inactive desulfo-form. Steady-state kinetic parameters were determined spectrophotometrically for urate production and NADH oxidation catalyzed by XO and xanthine dehydrogenase in the presence of nitrite under anaerobic conditions. pH optima for anaerobic NO production catalyzed by XO in the presence of nitrite were 7.0 for NADH and ≤6.0 for xanthine. Involvement of the molybdenum site of XO in nitrite reduction was shown by the fact that alloxanthine inhibits xanthine oxidation competitively with nitrite. Strong preference for Mo=S over Mo=O was shown by the relatively very low NADH-nitrite reductase activity shown by desulfo-enzyme. The FAD site of XO was shown not to influence nitrite reduction in the presence of xanthine, although it was clearly involved when NADH was the reducing substrate. Apparent production of NO decreased with increasing oxygen tensions, consistent with reaction of NO with XO-generated superoxide. It is proposed that XO-derived NO fulfills a bactericidal role in the digestive tract.

Current research efforts focus on using metal ions to bring organic molecules together and in so doing form structures that resemble large common materials, such as boxes, cages, grids, and channels. These metal-organic supramolecular structures are at the interface between molecular and macromolecular chemistry. As a contribution to this field of chemistry, we have focused on binding metal ions to cupped-shaped template molecules, which can be appended with functional groups. These resorcinarene-based molecules have four phenyl groups linked together into a ring and various functional groups attached to their upper rim. Some of the functional groups, bispyridylmethylamine (bpa) and iminodiacetic acid, are able to coordinate to metal ions. In the case of the bispyridylmethylamine resorcinarene, 2, a tetranuclear metal complex is formed when it is allowed to coordinate to copper(II). The copper centers surround the resorcinarene cavity and are not electronically coupled. In contrast to the Cu428+ complex, when cobalt(II) or iron(II) are allowed to coordinate to an iminodiacetic acid resorcinarene, 3, two resorcinarenes are bought together. The M4328- (M = Co or Fe) complexes are tetranuclear metal(II) cage compounds that assemble in aqueous solutions above pH 4 and have a cavity. These molecules are capable of encapsulating a variety of organic guest molecules, for example, nonpolar hydrocarbons, substituted phenyls, alcohols, halogen containing hydrocarbons, and polar organic molecules. The cages act as NMR shift reagents and cause substantial up-field isotropic hydrogen shifts (-30 to -40 ppm for Co2+ and -5 to -15 ppm for Fe2+) in the guest molecule and separation of the guest hydrogen chemical shifts. The solid state structures of Ba4[M432guest] (guest = 6 H2O, bromobenzene, or ethylbenzene) show bond angles independent of whether the metal ion is cobalt or iron, and bond lengths typical of metal oxygen and nitrogen bonds. The encapsulated guest does not noticeably effect the cavity dimensions, bond lengths, and bond angles.

Three native E. coli proteins—NusA, GrpE, and bacterioferritin (BFR)—were studied in fusion proteins expressed in E. coli for their ability to confer solubility on a target insoluble protein at the C-terminus of the fusion protein. These three proteins were chosen based on their favorable cytoplasmic solubility characteristics as predicted by a statistical solubility model for recombinant proteins in E. coli. Modeling predicted the probability of soluble fusion protein expression for the target insoluble protein human interleukin-3 (hIL-3) in the following order: NusA (most soluble), GrpE, BFR, and thioredoxin (least soluble). Expression experiments at 37°C showed that the NusA/hIL-3 fusion protein was expressed almost completely in the soluble fraction, while GrpE/hIL-3 and BFR/hIL-3 exhibited partial solubility at 37°C. Thioredoxin/hIL-3 was expressed almost completely in the insoluble fraction. Fusion proteins consisting of NusA and either bovine growth hormone or human interferon-γ were also expressed in E. coli at 37°C and again showed that the fusion protein was almost completely soluble. Starting with the NusA/hIL-3 fusion protein with an N-terminal histidine tag, purified hIL-3 with full biological activity was obtained using immobilized metal affinity chromatography, factor Xa protease cleavage, and anion exchange chromatography. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 65: 382–388, 1999.

Discusses the power potential of organization development (OD). Association of power with authority and position; Social trends influencing the increasing use of personal rather than positional power; Model of personal power and influence.

Subcellular localisation of xanthine oxidoreductase (XOR) was determined by indirect immunofluorescence using confocal microscopy in human endothelial and epithelial cell lines and in primary cultures of human umbilical vein endothelial cells. XOR was diffusely distributed throughout the cytoplasm but with higher intensity in the perinuclear region. In non‐permeabilised cells, XOR was clearly seen to be asymmetrically located on the outer surfaces, showing, in many cases, a higher intensity on those faces apposed by closely neighbouring cells. Such specific distribution suggests a functional role for the enzyme in cell‐cell interactions, possibly involving signalling via reactive oxygen species

We have studied the cause of inclusion body formation in Escherichia coli grown at 37°C using statistical analysis of the composition of 81 proteins that do and do not form inclusion bodies. Six composition derived parameters were used. In declining order of their correlation with inclusion body formation, the parameters are charge average, turn forming residue fraction, cysteine fraction, proline fraction, hydrophilicity, and total number of residues. The correlation with inclusion body formation is strong for the first two parameters but weak for the last four. This correlation can be used to predict the probability that a protein will form inclusion bodies using only the protein's amino acid composition as the basis for the prediction.

Abstract: Substituted enzyme (or ping-pong) mechanisms usually involve enzymes that exist in two forms that alternate during the catalytic reaction. A method is described here for determining the position of the equilibrium of a half reaction in a ping-pong enzyme mechanism that is based on the kinetics of the burst reaction which occurs upon addition of reactants that recycle the enzyme from one form to another. The theoretical basis for the analysis is developed, and the method is applied to the half reaction of the aldimine form of aspartate transaminase with difluoro-oxaloacetate.

Conventional subcellular fractionation techniques have been applied to human fetal brain (13–15 weeks gestation) and the fractions have been characterized by assaying for marker enzymes, cholinergic binding sites and electron microscopy. Fractionation of the homogenate resulted in a nuclear pellet (P1), a crude mitochrondrial pellet (P2) and a supernatant (S2). Further resolution of the P2 fraction by density gradient centrifugation resulted in two bands at the gradient interfaces and a pellet. The P2 and subsequently the P2B fraction contained intact plasma membrane profiles as judged by the predominance of adenylate cyclase activity and the presence of occluded lactate dehydrogenase which constituted over 70% of the total activity in these fractions. Morphological examination of the gradient fractions revealed that the P2B fraction contains membrane bound structures which resembie synaptosomes prepared from neonatal rat brain. These structures have a granular matrix in which mitochondria and frequently, neurofilaments were observed. Very few synaptic vesicles were present and there was no evidence for post synaptic attachments. The cholinergic markers choline acetyltransferase, acetylcholinesterase and receptor sites defined by quinuclidinyl benzilate and a-bungarotoxin binding were enriched in fractions P2 and P2B which contained the bulk of nerve ending particles. This enriched preparation of fetal synaptosomes may be valuable for functional studies on pre-synaptic terminals in developing brain.

No abstract available for this article.

S-(+)-3,4-Dihydroxybutylphosphonic acid, an isosteric analogue of sn-glycerol 3-phosphate, was synthesized stereospecifically and shown to be an effective substrate for rabbit muscle glycerol 3-phosphate dehydrogenase (sn-glycerol 3-phosphate–NAD+oxidoreductase, EC 1.1.1.8). Non-isosteric phosphonate analogues of sn-glycerol 3-phosphate showed neither substrate nor inhibitory activity with the enzyme.

A fusion protein was genetically engineered that contains an antimicrobial peptide, designated P2, at its carboxy terminus and bovine prochymosin at its amino terminus. Bovine prochymosin was chosen as the fusion partner because of its complete insolubility in Escherichia coli, a property utilized to protect the cells from the toxic effects of the antimicrobial peptide. This fusion protein was purified by centrifugation as an insoluble inclusion body. A methionine linker between prochymosin and the P2 peptide enabled P2 to be released by digestion with cyanogen bromide. Cation exchange HPLC followed by reversed-phase HPLC were used to purify the P2 peptide. The recombinant P2 peptide's molecular mass was confirmed by mass spectrometry to within 0.1% of the theoretical value (2480.9 Da), and the antimicrobial activity of the purified recombinant P2 against E. coli D31 was determined to be identical to that of the chemically synthesized peptide (minimal inhibitory concentration of 5 mg/mL). Although the yield of the fusion protein after expression by the cells was high (16% of the total cell protein), the percentage recovery of the P2 peptide in the inclusion bodies was relatively low, which appears to be due to losses in the cyanogen bromide digestion step. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 55–61, 1998.

Traditional educational design methods take little account of the indi vidual learner's needs and learning processes. Effective design involves overcoming internal forces that oppose the educator's learning goals. When it is successful, the learner is changed but has gained little ability to create and manage his or her own learning processes. Self-directed learn ing principles and practices work selectively with the learner's own needs and motives, strengthening confidence and the ability to learn indepen dently. Such learning designs permit much greater individualization in content and direction. Learners respond by undertaking greater personal risks but experience less stress in doing so. Principles of self-directed learning design include: providing a clearly articulated conceptual framework; providing equally valued alternatives for participants to choose among; using structure and direction to support the learner until he or she can move ahead independently; and giving "maximum feasible choice" at all points in the learning process.

Xanthine oxidoreductase (XOR) catalyses the reduction of the therapeutic organic nitrate, nitroglycerin (glyceryl trinitrate, GTN), as well as inorganic nitrate and nitrite, to nitric oxide (NO) under hypoxic conditions in the presence of NADH. Generation of nitric oxide is not detectable under normoxic conditions and is inhibited by the molybdenum site‐specific inhibitors, oxypurinol and (−)BOF 4272. These enzymic reactions provide a mechanism for generation of NO under hypoxic conditions where nitric oxide synthase does not function, suggesting a vasodilatory role in ischaemia.

Xanthine oxidase (XO) is conventionally known as a generator of reactive oxygen species (ROS) which contribute to hypoxic-reperfusion injury in tissues. However, this role for human XO is disputed due to its distinctive lack of activity towards xanthine, and the failure of allopurinol to suppress reperfusion injury. In this paper, we have employed native gel electrophore-sis together with activity staining to investigate the role human xanthine dehydrogenase (XD) and XO in hypoxic reperfusion injury. This approach has provided information which cannot be obtained by conventional spectrophotometric assays. We found that both XD and XO of human umbilical vein endothelial cells (HUVECs) and lymphoblastic leukaemic cells (CEMs) catalysed ROS generation by oxidising NADH, but not hypoxanthine. The conversion of XD to XO was observed in both HUVECs and CEMs in response to hypoxia, although the level of conversion varied. Purified human milk XD generated ROS more efficiently in the presence of NADH than in the presence of hypoxanthine. This NADH oxidising activity was blocked by the FAD site inhibitor, diphenyleneiodo-nium (DPI), but was not suppressible by the molybdenum site inhibitor, allopurinol. However, in the presence of both DPI and allopwinol the activities of XD/XO were completely blocked with either NADH or hypoxanthine as substrates. We conclude that both human XD and XO can oxidise NADH to generate ROS. Therefore, the conversion of XD to XO is not necessary for post-ischaemic ROS generation. The hypoxic-reperfusion injury hypothesis should be reappraised to take into account the important role played by XD and XO in oxidising NADH to yield ROS.