Differential Galois integrability obstructions for nonlinear three-dimensional differential systems

In this short communication, we deal with an integrability analysis of nonlinear three-dimensional differential systems. Right-hand sides of these systems are linear in one variable, which enables one to find explicitly a particular solution and to calculate variational equations along this solution. The conditions for the complete integrability with two functionally independent rational first integrals for B-integrability and the partial integrability are obtained from an analysis of properties of the differential Galois group of variational equations. They have a very simple form of numbers, which is necessary to check whether they are appropriate integers. An application of the obtained conditions to some exemplary nonlinear three-dimensional differential systems is shown.

[Effectiveness of anti-TNF alpha antibodies in treatment of fistulizing Crohn's disease]

INTRODUCTION

About 35% of patients with Crohn's disease develop fistulae. Treatment of those changes is a complicated clinical problem. Anti-TNF alpha antibodies are currently the most effective therapy of fistulizing Crohn's disease. Aim of the study is to evaluate results of anti-TNF alpha treatment in patients with fistulizing Crohn's disease.

METHODS

We evaluated results of anti-TNF alpha treatment (both with adalimumab n=10 and infliximab n=19) in 29 patients with fistulizing Crohn's disease treated in years 2008 - 2011 in Gastroenterology and Hepatology Clinic of University Hospital in Krakow.

RESULTS

Closure of over 50% of fistulas was achieved by 78,94% patients after induction therapy with infliximab and 50% with adalimumab. Long term remission, evaluated after 52 weeks of treatment, was observed in 46,15% patients treated with infliximab. Best results were observed in perianal fistulas treatment - remission was achieved in 88.2% of patients. Effectiveness of enterocutaneus fistalas therapy was lower, and their healing was observed in 28.57% of patients. We observed no correlation between duration of Crohn's disease, duration of fistulas history or previously used treatment and results of anti-TNF alpha treatment.

CONCLUSIONS

Anti-TNF alpha treatment has high effectiveness both short and long term in fistulizing Crohn's disease. Tolerance of treatment is very good. We lack clinical data about treatment other fistulas than perianal, but we suspect that effectiveness of anti-TNF alpha in this cases is lower. It is indicated to treat patients with fistulizing Crohn's disease with anti-TNF alpha, because it gives them chance for long remission and improvement of quality of life.

1.70 A resolution structure of myoglobin from yellowfin tuna. An example of a myoglobin lacking the D helix

The crystal structure of metmyoglobin from yellowfin tuna (Thunnus albacares) has been determined by molecular replacement methods and refined to a conventional R factor of 0.177 for all observed reflections in the range of 6.0-1.70 A resolution. Like other myoglobins for which a high-resolution structure is available, the polypeptide chain is organized into several helices that cooperate to form a hydrophobic pocket into which the heme prosthetic group is non-covalently bound; however, the D helix observed in other myoglobins is absent in myoglobin from yellowfin tuna and has been replaced with a random coil. As well, the A helix has a pronounced kink due to the presence of Pro16. The differences in structure between this and sperm whale myoglobin can be correlated with their reported dioxygen affinity and dissociation. The structure is in agreement with reported fluorescence data which show an increased Trp14.heme distance in yellowfin tuna compared to sperm whale myoglobin.

High and sustained transgene expression in vivo from plasmid vectors containing a hybrid ubiquitin promoter

Sustained transgene expression will be required for the successful treatment of most genetic diseases being considered for gene therapy. The initially high levels of expression attained with plasmid DNA (pDNA) vectors containing viral promoters, such as that from cytomegalovirus (CMV), decline precipitously to near-background levels within two to three weeks. Here we constructed pDNA vectors containing the human cellular UBB (encoding ubiquitin B; Ub) promoter and evaluated their expression in the mouse lung. Cationic lipid-pDNA complexes were instilled intranasally (IN) or injected intravenously (IV) into immunodeficient BALB/c mice. Chloramphenicol acetyltransferase (CAT) reporter gene expression from the UBB promoter was initially very low at day 2 post-administration, but by day 35 exceeded the level of expression attained from a CMV promoter vector by four- to ninefold. Appending a portion of the CMV enhancer 5' of the UBB promoter (CMV-Ub) increased CAT expression to nearly that of the CMV promoter and expression persisted in the lung for at least 3 months, with 50% of day 2 levels remaining at day 84. In the liver, expression from the CMV-Ub hybrid promoter was sustained for 42 days. As previous studies have shown that eliminating immunostimulatory CpG motifs in pDNA vectors reduces their toxicity, we constructed a CpG-deficient version of the CMV-Ub vector expressing alpha-galactosidase A, the enzyme deficient in Fabry disease, a lysosomal storage disorder. After IN or IV administration, levels of alpha-galactosidase A from this vector were not only undiminished but increased 500% to 1500% by day 35. Our results indicate that CpG-reduced plasmid vectors containing a CMV-Ub hybrid promoter may provide the long-term expression required for a practical gene therapeutic.

Cytotoxicity of daunorubicin in trisomic (+21) human fibroblasts: relation to drug uptake and cell membrane fluidity

The influence of daunorubicin (DNR) on survival of human normal (S-126) and trisomic, with respect to chromosome 21 (T-164; S-240), skin fibroblasts and some parameters related to it, such as intracellular drug accumulation, distribution and interaction with cell membrane, were studied. The in vitro growth-inhibition assay indicated that DNR was less cytotoxic for trisomic than for normal cells. Comparison of kinetic parameters and intracellular distribution of this compound showed that the uptake and the amount of intracellular free DNR were greater in normal than in trisomic cells. Contrary to this, there were no significant differences between the amount of DNA-bound drug in both types of cells. TMA-DPH and 12-AS fluorescence anisotropy measurements demonstrated that DNR decreased lipid fluidity in the inner hydrophobic region of plasma membrane in both cell types, but did not influence the fluidity of the outer surface of membrane. We conclude that fibroblasts derived from individuals affected with Down's syndrome are better protected from the damage induced by DNR than normal cells.

Thermosensitivity of red blood cells from Down's syndrome individuals

Biochemical disturbances of the reactive oxygen species metabolism revealed in subjects with Down's syndrome (DS), and the findings indicating that heat-induced cell alterations have been, at least, partly mediated by reactive oxygen species, made the elucidation of the response of trisomic cells to elevated temperatures of special interest. Kinetic analysis of cell-survival curves, accompanied by the flow cytometry and the scanning electron microscopy (SEM) examinations, and their relationship with the cell membrane fluidity, were undertaken. At each temperature (48-54 degrees C), Dq parameters, representing the ability to accumulate sublethal damages, were similar for both cell groups. D0 parameters (inverse leakage rates; D0 = 1/k) were greater for DS cells at each temperature below 54 degrees C. The haemolysis sensitivity ratio (HSR) showed that DS erythrocytes were, in average, 1.60 times more resistant to heat injury than those from normal subjects. Activation energies of haemolysis, calculated according to the Arrhenius equation, were similar both for normal (290.8 +/- 6.5 [kJ/mol]) and DS erythrocytes (288.0 +/- 5.5 [kJ/mol]). Flow cytometry studies showed that the scattering properties of intact DS erythrocytes (reflecting size, volume, shape and cell membrane surface morphology) were different than those of normal cells. Scanning electron micrographs and scattering diagrams obtained for cells submitted to heat stress (51 degrees C) confirmed that DS erythrocytes were more resistant, to a certain extent, to heat-induced disruption than normal cells. The steady-state fluorescence anisotropy of TMA-DPH (1-(4-trimethyl-ammoniumphenyl)-6-phenyl-1,3,5-hexatriene) showed that untreated DS erythrocytes had substantially lower fluidity (r = 0.356 +/- 0.008) of the outer monolayer of cell membranes as compared to normal cells (r = 0.324 +/- 0.011). The increase of the cell membrane fluidity during exposure to heat was observed. The greatest elevation of cell membrane fluidity occurred during the preleakage period, immediately upon the heat treatment and was considered as a rate-limiting step of heat-induced haemolysis.

Reduced inflammatory response to plasmid DNA vectors by elimination and inhibition of immunostimulatory CpG motifs

An inflammatory response is invariably associated with administration of gene transfer complexes composed of cationic lipids and plasmid DNA (pDNA). In the lung, an influx of neutrophils and elevated levels of several proinflammatory cytokines such as TNF-alpha, IFN-gamma, IL-6, and IL-12 characterize this dose-dependent response. The induction of these cytokines was shown previously to be due in part to the presence of unmethylated CpG dinucleotides in the bacterially derived pDNA. We have eliminated 270 of 526 CpG dinucleotides in a reporter plasmid (pCFA-CAT) and tested the inflammatory response to cationic lipid:pDNA complexes containing the modified vector (pGZA-CAT) after intravenous (i.v.) or intranasal (i.n.) delivery into BALB/c mice. Compared to the unmodified vector, the CpG-reduced pGZA-CAT was found to be significantly less immunostimulatory, as the levels of IL-12, IFN-gamma, and IL-6 in the serum 24 h after i.v. delivery were reduced by 40 to 75%. Similar reductions in cytokine levels were also observed in the bronchoalveolar lavage fluids (BALF) after i.n. administration, while the levels of reporter gene expression were not affected by the modifications. We have also investigated known inhibitors of the CpG signaling pathways in order to decrease the inflammatory response. Two such inhibitors, chloroquine and quinacrine, greatly reduced the induction of IL-12 from mouse spleen cells in vitro and inhibited cytokine production in the lung by approximately 50% without affecting gene expression. These results illustrate that use of a less immunostimulatory pDNA vector or inhibitors of CpG immunostimulation can reduce significantly the toxicity associated with cationic lipid:pDNA complexes thereby increasing the therapeutic index of this synthetic gene transfer vector.

Predicting porcelain thickness required for dental shade matches

STATEMENT OF PROBLEM

Production of a ceramic dental restoration that matches a target shade is dependent on porcelain thickness. Even when adequate porcelain thickness exists, clinical shade matches are difficult to achieve.

PURPOSE

This study predicted the thickness of dentin porcelain required to obtain a clinical shade match (</=3 DeltaE units) for a variety of dental porcelain systems and shades.

MATERIALS AND METHODS

Three all-ceramic crown systems (Empress, Inceram-Alumina, Inceram-Spinell) and 2 metal ceramic systems (Vintage, VMK-95) were evaluated, each in shades A1, A3, and C2. Five specimens of each porcelain, of each shade, were fabricated at thicknesses of 1.0, 1.2, 1.5, and 2.0 mm. CIE-LAB coordinates were recorded for each specimen, and for the midgingival third of corresponding shade tabs with a Minolta CR-321 colorimeter.

RESULTS

Seventy percent of the color difference between specimen and shade tab was due to high L* (Munsell value) in the specimens. At thicknesses of </=2.0 mm of dentin porcelain, the all-ceramic systems exhibited more shade matches than the metal ceramic systems.

CONCLUSIONS

Specimens made from semi-translucent all-ceramic systems exhibited clinical shade matches that were superior to those made with the metal ceramic systems. Increasing thickness of the semi-translucent systems from 1.0 to 2.0 mm did not improve shade matching.

Increased duration of transgene expression in the lung with plasmid DNA vectors harboring adenovirus E4 open reading frame 3

For gene therapy to be effective in the treatment of chronic diseases, plasmid DNA (pDNA) vectors that provide persistent expression of therapeutic levels of the transgene product are desirable. Studies in the lung with adenovirus vectors showed that products of the adenovirus E4 region can act both in cis and in trans to increase the duration of expression when transcription of the transgene was under the control of the human cytomegalovirus (CMV) promoter. To determine if these E4-encoded proteins could also effect greater persistence of expression from a nonviral vector, a complex composed of cationic lipid GL-67, a CMV promoter plasmid (pCF1-CAT), and an E4-containing adenovirus vector (Ad2/betagal-4) was instilled into the lungs of BALB/c nu/nu mice. Significant increases in the duration of transgene expression were observed for up to 10 weeks postinstillation compared with expression from mice instilled with control complexes containing an adenovirus vector deleted of most of E4 (Ad2/betagal-2). This effect could also be observed in immunodeficient NIH-rnu rats as well as in immunocompetent BALB/c mice. Studies with CMV promoter mutants indicated that a region proximal to the promoter was necessary for the E4-mediated increase in longevity of expression. In addition to the CMV promoter, a CMV enhancer-human mucin I (MUC-I) hybrid promoter also responded to these E4-encoded proteins with increased persistence of transgene expression, but a human interleukin 8 (IL-8) promoter did not. Ad2/betagal-4 could be replaced by a pDNA vector expressing only the E4 region, indicating that products of the E4 region alone were sufficient in the absence of expression from the rest of the adenovirus genome. Further analysis indicated that the protein encoded by open reading frame 3 (ORF3) alone was sufficient for conferring the increase in persistence of expression. These data indicate that expression of a single protein from the adenovirus genome can significantly improve the duration of transgene expression from pDNA vectors, and increases the feasibility of using nonviral vectors for the treatment of chronic diseases.

Crystallization of the haptoglobin-hemoglobin complex

Two orthorhombic forms of crystals of the haptoglobin-hemoglobin complex were obtained using polyethylene glycol as precipitant. These crystals did not diffract well enough for data collection and work on the complex is no longer continued. However, the description of the crystallization conditions may be useful in future endeavors to obtain suitable crystals.

Contribution of plasmid DNA to inflammation in the lung after administration of cationic lipid:pDNA complexes

Cationic lipid-mediated gene transfer to the mouse lung induces a dose-dependent inflammatory response that is characterized by an influx of leukocytes and elevated levels of the cytokines interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha), and interferon gamma (IFN-gamma). We have examined the contribution of plasmid DNA (pDNA) to this observed toxicity, specifically the role of unmethylated CpG dinucleotides, which have been previously shown to be immunostimulatory. We report here that complexes of cationic lipid GL-67 and unmethylated pDNA (pCF1-CAT) instilled into the lungs of BALB/c mice induced highly elevated levels of the cytokines TNF-alpha, IFN-gamma, IL-6, and IL-12 in the bronchoalveolar lavage fluids (BALF). In contrast, BALF of animals administered either GL-67 alone or GL-67 complexed with SssI-methylated pDNA contained low levels of these cytokines. Similar results were observed using a plasmid (pCF1-null) that does not express a transgene, demonstrating that expression of chloramphenicol acetyltransferase (CAT) was not responsible for the observed inflammation. The response observed was dose dependent, with animals receiving increasingly higher amounts of unmethylated pDNA exhibiting progressively higher levels of the cytokines. Concomitant with this increase in cytokine levels were also elevated numbers of neutrophils in the BALF, suggesting a possible cause- and-effect relationship between neutrophil influx and generation of cytokines. Consistent with this proposal is the observation that reduction of neutrophils in the lung by administration of antibodies against Mac-1alpha and LFA-1 also diminished cytokine levels. This reduction in cytokine levels in the BALF was accompanied by an increase in transgene expression. In an attempt to abate the inflammatory response, sequences in the pDNA encoding the motif RRCGYY, shown to be most immunostimulatory, were selectively mutagenized. However, instillation of a plasmid in which 14 of the 17 CpG sites were altered into BALF/c mice did not reduce the levels of cytokines in the BALF compared with the unmodified vector. This suggests that other unmethylated motifs, in addition to RRCGYY, may also contribute to the inflammatory response. Together, these findings indicate that unmethylated CpG residues in pDNA are a major contributor to the induction of specific proinflammatory cytokines associated with instillation of cationic lipid:pDNA complexes into the lung. Strategies to abate this response are warranted to improve the efficacy of this nonviral gene delivery vector system for the treatment of chronic diseases.

Cholesterol sulfate induces changes in human erythrocyte thermostability

The influence of cholesterol sulfate (CS) on human red blood cell thermosensitivity was studied by flow cytometry and scanning electron microscopy. It was found that the effect of this sterol on erythrocyte stability is biphasic. Exposure of red blood cells (RBC) to the elevated temperature (51 degrees C) induced perturbation of the cell membrane and led to haemolysis. Preincubation of cells with CS at a concentration of 1 x 10(-5) M protected them, to a certain extent, against lysis. In contrast, enrichment of RBCs with CS during the incubation with lower (0.4 x 10(-5) M) or higher (4-8 x 10(-5) M) CS concentrations substantially augmented the fragility of the cells. The fact, that at the sublytic concentrations CS stabilises the cell membrane, may be explained by the ability of this amphipathic compound to link hydrophilic and lipophilic domains of the cell membrane and to increase the degree of the lipid bilayer order. Higher CS concentrations cause cell lysis in a detergent-like manner. Our data support the conclusion that CS can be considered to be a potent thermosensitizer, which enhances the selectivity of biological drug carriers.

Positional cloning without a genome map: using 'Targeted RFLP Subtraction' to isolate dense markers tightly linked to the regA locus of Volvox carteri

The ability to isolate genes defined by mutant phenotypes has fueled the rapid progress in understanding basic biological mechanisms and the causes of inherited diseases. Positional cloning, a commonly used method for isolating genes corresponding to mutations, is most efficiently applied to the small number of model organisms for which high resolution genetic maps exist. We demonstrate a new and generally applicable positional cloning method that obviates the need for a genetic map. The technique is based on Restriction Fragment Length Polymorphism (RFLP) Subtraction, a method that isolates RFLP markers spanning an entire genome. The new method, Targeted RFLP Subtraction (TRS), isolates markers from a specific region by combining RFLP Subtraction with a phenotypic pooling strategy. We used TRS to directly isolate dense markers tightly linked to the regA gene of the eukaryotic green alga Volvox. As a generally applicable method for saturating a small targeted region with DNA markers, TRS should facilitate gene isolation from diverse organisms and accelerate the process of physically mapping specific regions in preparation for sequence analysis.

Morphological changes of human erythrocytes induced by cholesterol sulphate

OBJECTIVES

Morphological alterations of human erythrocytes induced by cholesterol sulphate (5-cholesten-3 beta-ol sulphate, CS) were studied.

DESIGN AND METHODS

Influence of CS on red blood cell stability (in isotonic conditions) by simultaneous application of flow cytometry and scanning electron microscopy was studied.

RESULTS

In isotonic medium CS induces erythrocyte size and shape changes in dose-and time-dependent manner. Incubation (in vitro) of erythrocytes with CS concentrations from 4 x 10(-5) mol/dm3 to 8 x 10(-5) mol/dm3 led to a progressive sphero-echinocitic shape transformation accompanied by a cell size decrease. In contrast to this, for CS content equal to 1 x 10(-5) mol/dm3 the maintenance of the normal biconcave shape of red blood cells was observed.

CONCLUSIONS

The results suggest that CS, similarly to numerous evaginating amphiphilic agents, induces a transformation of the erythrocyte normal discoid shape to echinocytic form. This effect may be caused, at least partly, by an asymmetric expansion of the membrane lipid bilayer due to asymmetric distribution of CS incorporated into the membrane. The echinocytic shape transformation of erythrocytes indicated that CS intercalates in the outer hemileaflet of the lipid bilayer leading to membrane externalization.

Three abundant germ line-specific transcripts in Volvox carteri encode photosynthetic proteins

Volvox carteri is a multicellular eukaryotic green alga composed of about 2000 cells of only two differentiated types: somatic and germ line. To understand how embryonic cells are assigned either to somatic or germ line fates, we are investigating the regulation of transcripts that are abundant in only one cell type. Here we report the identity of three transcripts that are coordinately expressed at high levels in germ line cells but not in somatic cells. Surprisingly, all three transcripts encode photosynthetic chloroplast proteins (light-harvesting complex protein, oxygen-evolving enhancer protein 3, and ferredoxin-NADP+ reductase) that are transcribed from nuclear genes. We discuss why these mRNAs might be required at high levels in germ line cells and present a hypothesis, suggested by our results, on the evolution of cell specialization in the Volvocales.

Estimation of cholesterol sulphate in blood plasma and in erythrocyte membranes from individuals with Down's syndrome or diabetes mellitus type I

OBJECTIVES

Plasma and erythrocyte membrane cholesterol sulphate (CS) were measured in patients suffering from diabetes and Down's syndrome.

DESIGN AND METHODS

The procedure for separation and determination of CS comprised HPTLC (high-performance thin-layer chromatography) and densitometry.

RESULTS

The mean plasma and RBC membranes CS concentrations (+/- SD) of the control group (n = 16) was 188 +/- 47 micrograms/dL and 343 +/- 57 micrograms/10(12) RBC, respectively. In 15 patients with diabetes and 12 Down's syndrome patients substantially higher CS levels were found (diabetes: plasma-348 +/- 60 micrograms/dL; RBC membranes-646 +/- 113 micrograms/10(12) RBC; Down's syndrome: plasma-245 +/- 54 micrograms/dL; RBC membranes 427 +/- 74 micrograms/10(12) RBC). Analysis of variance and multiple comparison (Newman-Keuls test) show statistically significant differences between all samples both for erythrocytes, F(2.41) = 52.24, p < 0.05, and plasma, F(2.41) = 34.92, p < 0.05.

CONCLUSIONS

It is postulated that differences in CS levels may contribute to changes of erythrocyte properties in these pathological states.

"RFLP subtraction": a method for making libraries of polymorphic markers

We developed a method, "RFLP subtraction," that isolates large numbers of unique sequence restriction fragment length polymorphisms (RFLPs) in a single experiment. The technique purifies small restriction fragments from one genome containing sequences that reside on large fragments in a related genome. We first isolate samples containing the small restriction fragments from two polymorphic strains. Subtractive hybridization then removes the fragments that are present in both samples. The remaining sequences are RFLPs: they occur on small fragments in one strain but not in the other. Here we use RFLP subtraction to make a library of hundreds of unique sequence RFLPs from two inbred mouse strains. We analyze and map a subset of the RFLPs and show that the genetic linkage of these markers can be rapidly determined by an efficient dot blot mapping technique. Several other potential applications of RFLP subtraction, including isolating region specific markers, are discussed.

Crystal structure to 2.45 A resolution of a monoclonal Fab specific for the Brucella A cell wall polysaccharide antigen

The atomic structure of an antibody antigen-binding fragment (Fab) at 2.45 A resolution shows that polysaccharide antigen conformation and Fab structure dictated by combinatorial diversity and domain association are responsible for the fine specificity of the Brucella-specific antibody, YsT9.1. It discriminates the Brucella abortus A antigen from the nearly identical Brucella melitensis M antigen by forming a groove-type binding site, lined with tyrosine residues, that accommodates the rodlike A antigen but excludes the kinked structure of the M antigen, as envisioned by a model of the antigen built into the combining site. The variable-heavy (VH) and variable-light (VL) domains are derived from genes closely related to two used in previously solved structures, M603 and R19.9, respectively. These genes combine in YsT9.1 to form an antibody of totally different specificity. Comparison of this X-ray structure with a previously built model of the YsT9.1 combining site based on these homologies highlights the importance of VL:VH association as a determinant of specificity and suggests that small changes at the VL:VH interface, unanticipated in modeling, may cause significant modulation of binding-site properties.

Thermal properties and fluidity of human erythrocyte membranes in diabetes mellitus

Exposure of human erythrocytes to elevated temperatures induces a decrease in stability of the cell membrane. Thermally induced haemolysis of erythrocytes from patients with type 1 diabetes and from healthy control individuals was measured as a function of duration of exposure to heat between 48.0 and 54.0 degrees C. Results indicate that the thermosensitivity of erythrocytes from patients with type 1 diabetes is lower than for control individuals. Activation energies for lysis were similar for both control and 'diabetic' erythrocytes, being 298.3 and 287.7 kJ/mol, respectively. The steady-state fluorescence anisotropy measurement of TMA-DPH for each step of haemolysis was employed as a parameter characterizing membrane fluidity. We found that 'diabetic' erythrocyte membranes had significantly decreased fluidity. The relationship between fluidity and rate of haemolysis indicates that the rate-limiting step in the haemolysis reaction involves the rupturing of the membrane bilayer.

Structure of oncomodulin refined at 1.85 A resolution. An example of extensive molecular aggregation via Ca2+

The crystal structure of oncomodulin, a 12,000 Mr protein isolated from rat tumours, has been determined by molecular replacement using the carp parvalbumin structure as a starting model. Refinement was performed by cycles of molecular fitting and restrained least-squares, using area-detector intensity data to 1.85 A resolution. For the 5770 reflections in the range 6.0 to 1.85 A, which were used in the refinement, the crystallographic R-factor is 0.166. The refined model includes residues 2 to 108, three Ca2+ and 87 water molecules per oncomodulin molecule. The oncomodulin backbone is closely related to that of parvalbumin; however, some differences are found after a least-squares fit of the two backbones, with root-mean-square (r.m.s.) deviations of 1 to 2 A in residues 2 to 6, 59 to 61 of the CD loop, 87, 90 and 108. The overall r.m.s. deviation of the backbone residues 5 to 108 is 0.62 A. Each of the two Ca2+ atoms that are bound to the CD and EF loops is co-ordinated to seven oxygen atoms, including one water molecule. The third Ca2+ is also seven-co-ordinated, to five oxygen atoms belonging to three different oncomodulin molecules and to two water molecules which form hydrogen bonds to a fourth oncomodulin; thus, this intermolecular Ca2+ and its equivalents interlink the molecules into zigzag layers normal to the b axis with a spacing of b/2 or 32.14 A. No such extensive molecular aggregation has been reported for any of the related Ca-binding regulatory proteins of the troponin-C family studied thus far. The Ca-O distances in all three polyhedra are in the range 2.07 A to 2.64 A, indicating tightly bound Ca polyhedra.

Preliminary crystal structure analysis of an Fab specific for a Salmonella O-polysaccharide antigen

The Fab from an IgG1, lambda murine monoclonal antibody with specificity for the O-polysaccharide antigen of Salmonella typhimurium has been crystallized in the absence and presence of hapten. The conditions for crystal growth were vapor diffusion equilibration with 16 to 23% polyethylene glycol 8000 solutions. Data have been collected from crystals of the complex in space group P212121, a = 60.6 A, b = 111.3 A, c = 61.1 A, and refinement of a molecular replacement solution is underway.

A double cell for controlling nucleation and growth of protein crystals

A simple device for protein crystallization is described that consists of two connected cells, one for the hanging- or sitting-drop vapour diffusion method and the other for changing the concentration of the reservoir solution. It has been found useful for decoupling crystal nucleation from crystal growth, for improving the size and the stability of crystals, and in the preparation of heavy-atom derivatives.

Avian thrombocyte thrombospondin

A high molecular weight glycoprotein (450,000) was obtained from thrombin-treated duck thrombocytes by barium citrate adsorption technique followed by heparin-agarose affinity chromatography. Amino acid composition (high number of acidic amino acids and cystine) as well as carbohydrate contents (1.3 per cent hexosamine, 0.9 per cent sialic acid and 1.5 per cent hexose) showed similarity to mammalian platelet thrombospondin.

The lycoctonine family of alkaloids: a stereochemical revision

A redetermination of the structure of des(oxymethylene)lycoctonine hydriodide has shown that a wrong choice had been made between the real and false mirror image peaks for the atoms of the 1-methoxyl group in the original pseudosymmetric Fourier synthesis. It has been demonstrated that lycoctonine samples from many sources are identical, and that no rearrangement took place in forming des(oxymethylene)lycoctonine. Hence all alkaloids that have been related to lycoctonine have a 1α-methoxyl group.

The crystal structure of the neuroleptic agent (±)-deoxybutaclamol and its significance for the topography of the central dopamine receptor

(±)-Deoxybutaclamol, C25H31N, crystallizes in space group P21/a with cell dimensions: a = 16.626(3), b = 10.646(2), c = 11.278(3) Å, β = 90.47(4)°. The structure was solved by direct methods using the QTAN program. The coordinates were refined by block-diagonal least-squares calculations to R = 0.052 for 3147 observed reflections.The structure of (±)-deoxybutaclamol was found to be very similar to that of equipotent (±)-butaclamol and is in agreement with that assigned on the basis of chemical, spectral, crystallographic, and pharmacological studies. This confirmation validates the coordinates of a lipophilic accessory binding site in a proposed model of the central dopamine receptor.