Management of a pregnancy complicated by pompe disease.

Background. As more women with metabolic muscle diseases reach reproductive age, knowledge of these diseases and their impact on pregnancy is necessary. Case. 23-year-old G1P0 with juvenile-onset Pompe disease (PD) delivered a viable infant by cesarean section at 32 weeks and 6 days. The pregnancy was complicated by worsening maternal pulmonary status, muscular strength, and mobility. Conclusion. The management of pregnancies complicated by Pompe disease requires a multidisciplinary approach, including expertise in neuromuscular disease, maternal-fetal medicine, biochemical genetics, pulmonology, anesthesia, and dietetics.

The influence of a hexametaphosphate-containing chewing gum on the wetting ability of salivary conditioning films in vitro and in vivo.

OBJECTIVE: Adsorbed conditioning films of salivary components on dental enamel surfaces or pellicles form the interface between teeth and the oral environment. The wetting ability of salivary conditioning films dictates biological adhesion phenomena such as plaque formation, calcification and staining, and also influences mouth perception through effects on lubricity. This study assessed the effects of hexametaphosphate release from a chewing gum matrix on the wetting ability of salivary conditioning films in vitro and in vivo. METHODOLOGY: Results obtained for hexametaphosphate chewing gum were compared with those produced by hexametaphosphate-containing dentifrice, which has been clinically proven to have efficacy for stain removal and prevention and dental calculus prevention. RESULTS: Contact angle assessments revealed that hexametaphosphate dentifrice produced markedly hydrophilic conditioning films in vitro. Hexametaphosphate chewing gums had only minor effects on surface contact angles in vitro. However, in vivo intra-oral contact angle measurements on tooth surfaces in volunteers showed that both hexametaphosphate dentifrice and chewing gum produced more hydrophilic tooth surfaces. CONCLUSION: These results support the activity of hexametaphosphate on tooth surfaces delivered both from dentifrice and chewing gum forms.

Domain bridging interactions. A necessary contribution to the function and structure of Escherichia coli aspartate transcarbamoylase.

Aspartate transcarbamoylase undergoes a domain closure in the catalytic chains upon binding of the substrates that initiates the allosteric transition. Interdomain bridging interactions between Glu(50) and both Arg(167) and Arg(234) have been shown to be critical for stabilization of the R state. A hybrid version of the enzyme has been generated in vitro containing one wild-type catalytic subunit, one catalytic subunit in which Glu(50) in each catalytic chain has been replaced by Ala (E50A), and wild-type regulatory subunits. Thus, the hybrid enzyme has one catalytic subunit capable of domain closure and one catalytic subunit incapable of domain closure. The hybrid does not behave as a simple mixture of the constituent subunits; it exhibits lower catalytic activity and higher aspartate affinity than would be expected. As opposed to the wild-type enzyme, the hybrid is inhibited allosterically by CTP at saturating substrate concentrations. As opposed to the E50A holoenzyme, the hybrid is not allosterically activated by ATP at saturating substrate concentrations. Small angle x-ray scattering showed that three of the six interdomain bridging interactions in the hybrid is sufficient to cause the global structural change to the R state, establishing the critical nature of these interactions for the allosteric transition of aspartate transcarbamoylase.

Influence of 3-methylcholanthrene pretreatment on sanguinarine toxicity in mice.

We examined the effect of 3-methylcholanthrene (3-MC) on the liver toxicity of sanguinarine in mice. Administration of 10 mg sanguinarine/kg bw ip to male mice resulted in significant decreases in liver glutathione and P450 enzymes activities, and increased in sorbitol dehydrogenase and alanine aminotransferase levels in serum suggestive of liver damage. However, pretreatment with 20 mg 3-MC/kg/d ip, an inducer of P450 enzymes, for 3 d mitigated the sanguinarine toxic effects suggesting 3-MC induced cytochrome P450 enzymes that promote detoxification of sanguinarine.

Making consignment- and vendor-managed inventory work for you.

This article will examine some of the benefits of vendor managed inventory (VMI) and consignment from a supplier's perspective. Indeed, there are benefits to both approaches, as well as costs and risks. By understanding and managing the costs, and controlling the risks through careful negotiations, one can make both consignment and VMI work not only for the customer, but for the supplier as well.

Characterization of the aspartate transcarbamoylase from Methanococcus jannaschii.

The genes from the thermophilic archaeabacterium Methanococcus jannaschii that code for the putative catalytic and regulatory chains of aspartate transcarbamoylase were expressed at high levels in Escherichia coli. Only the M. jannaschii PyrB (Mj-PyrB) gene product exhibited catalytic activity. A purification protocol was devised for the Mj-PyrB and M. jannaschii PyrI (Mj-PyrI) gene products. Molecular weight measurements of the Mj-PyrB and Mj-PyrI gene products revealed that the Mj-PyrB gene product is a trimer and the Mj-PyrI gene product is a dimer. Preliminary characterization of the aspartate transcarbamoylase from M. jannaschii cell-free extract revealed that the enzyme has a similar molecular weight to that of the E. coli holoenzyme. Kinetic analysis of the M. jannaschii aspartate transcarbamoylase from the cell-free extract indicates that the enzyme exhibited limited homotropic cooperativity and little if any regulatory properties. The purified Mj-catalytic trimer exhibited hyperbolic kinetics, with an activation energy similar to that observed for the E. coli catalytic trimer. Homology models of the Mj-PyrB and Mj-PyrI gene products were constructed based on the three-dimensional structures of the homologous E. coli proteins. The residues known to be critical for catalysis, regulation, and formation of the quaternary structure from the well characterized E. coli aspartate transcarbamoylase were compared.

Break through to success with training and teamwork.

This is a case study on the effect of training and teamwork in two different divisions within the same company. One division consisted of a nonunion manufacturing plant; the second was a unionized distribution operation. In both operations, serious problems existed--poor customer service levels, inadequate inventory turns, and insufficient profitability. These are the kinds of problems that, left untreated, can cause the death of any manufacturing or distribution operation. However, by implementing training and teamwork at both operations, impressive benefits were achieved, including customer service levels exceeding 90 percent, dramatic improvements in the inventory turnover rate, and profitability that exceeded corporate goals.

A single mutation in the regulatory chain of Escherichia coli aspartate transcarbamoylase results in an extreme T-state structure.

Kinetic analysis of a mutant version of Escherichia coli aspartate transcarbamoylase in which Thr82 in the regulatory chain (Thr82r) was replaced by Ala results in a shift in the T <==> R equilibrium towards the T-state. In order to understand the structural determinants of this T-state stabilization, the X-ray structure of the unliganded Thr82r-->Ala enzyme was determined at 2. 6 A resolution and refined to a crystallographic residual of 0.175. The structure of the mutant r1 regulatory chain is more similar to that of the r6 regulatory chain than observed for the wild-type enzyme, resulting in a more symmetric structure. Furthermore, the structural changes in the mutant enzyme appears to occur only in the r1 chain, while the r6 chain is almost identical in structure to that of the r6 chain of the wild-type enzyme. The structure of the mutant enzyme exhibits alterations in the subunit interfaces between the regulatory and catalytic chains, as well as in the interface between the allosteric and zinc domains within the regulatory chain. Moreover, the regulatory dimers are rotated around their respective 2-fold axes approximately 1 degrees beyond the rotation which occurs in the wild-type T-state enzyme. The structural analysis indicates that the enzyme is an "extreme" T-state, in which a larger rotation of the regulatory dimers is required for the T to R transition compared to the wild-type enzyme. This extreme T-state structure correlates well with the kinetic parameters determined for the mutant enzyme, showing a stabilized T-state. Furthermore, the structural analysis of the mutant enzyme suggests that replacement of Thr82r with Ala alters the local conformation of the nucleotide binding pocket and therefore offers a plausible explanation for the reduced affinity of the enzyme for nucleotides.

Development of revised Ionising Radiations Regulations.

New standards in ICRP60 led to the revision of the 1980 European Basic Safety Standards Directive, which in turn has created the necessity to revise the Ionising Radiations Regulations 1985. Proposals from the Health and Safety Commission (HSC) for revised regulations are currently out for public consultation in a formal Consultative Document. This article describes some of the background to the proposals in the Consultative Document, key influences on the revision process and the methods used to develop the proposal so that they are broadly acceptable to stakeholders. Some of the changes proposed are structural in nature, such as integration of the provision of the Outside Workers Regulations. Others are of a legal nature and include: new proposals for justification, prior authorisation and risk assessment; two options for the dose limitation system; and significant changes to the means of recognising the competence of the Radiation Protection Adviser. Following the current public consultation, final proposals need to be drawn up, approved by HSC and cleared through the European Commission under procedures required by the Euratom Treaty. If all goes according to plan, the revised regulations should be on the Statute Book about the middle of next year, with most provisions coming into force on 1 January 2000.

Self-esteem, gender, and alcohol use: relationships with HIV risk perception and behaviors in college students.

The present study examined the confluence of alcohol use and self-esteem on risky sexual behavior and perceptions of risk for female and male college students. It was predicted that higher levels of self-esteem, female gender, and lower alcohol consumption would be associated with greater condom use and lower perceptions of risk for self and partner. Results indicated that for low drinking students, those with high self-esteem reported greater condom use. In addition, low rates of alcohol use were associated with greater frequency of past condom use. Women and students low in self-esteem indicated greater perceptions of risk for themselves and their partners. These findings are discussed in terms of their implications for developing interventions aimed at reducing risky sexual behavior.

PIP: This study examined the association of alcohol use and self-esteem on HIV risk perception and behaviors in male and female college students. A series of questionnaires was given to 130 female and 130 male undergraduates aged 17-37 years from the University of Georgia. Results of the study demonstrated that risky sexual behavior and perceptions of risk vary in relation to gender, level of self-esteem, and alcohol consumption in college women and men. The results suggest the relevance of considering HIV/AIDS risk perception and risk behavior as a function of contextually related variables such as gender, self-esteem, and alcohol consumption. Low drinkers, those with high self-esteem reported greater condom use. In addition, low rates of alcohol use were associated with greater frequency of past condom use. Women and students low in self-esteem indicated greater perceptions of risk for themselves and their partners. These findings are discussed in terms of their implications for developing interventions aimed at reducing risky sexual behavior.

Threonine 82 in the regulatory chain is important for nucleotide affinity and for the allosteric stabilization of Escherichia coli aspartate transcarbamoylase.

The three-dimensional structure of Escherichia coli aspartate transcarbamoylase complexed with the allosteric effector CTP, shows an interaction between the hydroxyl of Thr-82 in the regulatory chain (Thr-82r) with the gamma-phosphate of CTP (R.P. Kosman, J.E. Gouaux, W.N. Lipscomb, Crystal structure of CTP-ligated T state aspartate transcarbamoylase at 2.5 A resolution: implications for aspartate transcarbamoylase mutants and the mechanism of negative cooperativity, Proteins Struct. Funct. Genet. 15 (1993) 147-176). In order to determine whether the Thr-82r interaction with the gamma-phosphate of CTP is important for either binding of the nucleotide effectors or their function, site-specific mutagenesis was employed. The mutant enzyme in which Thr-82r was replaced by Ala had almost the identical maximal observed specific activity as the wild-type enzyme; however, the mutant enzyme had a significantly increased [Asp]0.5, the aspartate concentration at one-half the maximal observed specific activity, as well as slightly increased homotropic cooperativity. The mutant enzyme was also activated more by ATP and inhibited less by CTP as compared to the wild-type enzyme. In addition, the nucleotide concentration required for one-half maximal effect was increased approx. 3-fold as compared to the corresponding values for the wild-type enzyme. The maximal inhibition of the mutant enzyme, in the presence of UTP and CTP was similar to that observed for the wild-type enzyme; however, higher concentrations of the nucleotides were required to achieve this level of inhibition. The reduced affinity of CTP, UTP and ATP induced by the mutation indicates that the hydrogen bonding interaction between the gamma-phosphate of the nucleotide effector and the side-chain hydroxyl of Thr-82r is important for the binding of the nucleotide effectors to the allosteric site. Furthermore, this interaction is important for the discrimination between CTP and CDP. Finally, the greater homotropic cooperativity, greater [Asp]0.5, diminished CTP inhibition and greater ATP activation of the mutant enzyme correlates with the X-ray structure of the mutant enzyme which shows that the unligated enzyme is in an 'extreme' T-state. These findings add support to the theory that the global stabilization of the enzyme is critical for both the homotropic and heterotropic properties of aspartate transcarbamoylase.

From zero to teamwork: a manufacturing journey.

This article is a case study of the implementation of employee-empowered problem-solving teams. Topics include how projects were selected, how project teams were trained, and how obstacles were overcome. Ths article concludes with 10 recommendations for organizations that would like to initiate team-based activities.

Overexpression and purification of the trimeric aspartate transcarbamoylase from Bacillus subtilis.

A procedure has been developed for the overexpression and purification of milligram quantities of the Bacillus subtilis aspartate transcarbamoylase. The plasmid pEK171, carrying the B. subtilis pyrB structural gene under the control of the Escherichia coli pyrBI promoter, was transformed into the E. coli strain EK1104 and the enzyme overexpressed to approximately 50% of total soluble protein under extreme derepression of the pyrimidine pathway. The enzyme was subsequently purified by means of ammonium sulfate fractionation, anionic exchange chromatography using Q-Sepharose Fast Flow resin, negative chromatography on Matrex Gel Red A agarose, and hydrophobic interaction chromatography using Matrex Phenyl Cellufine. The purification yields approximately 60 mg of pure enzyme per liter of bacterial culture. Kinetic analysis of the overexpressed enzyme indicated that it had kinetic properties very similar to those of the enzyme purified from B. subtilis cells.

Fructose-1,6-bisphosphatase: arginine-22 is involved in stabilization of the T allosteric state.

A comparison of the X-ray crystallographic structures of the R and T allosteric states [Ke, H. M., Liang, J.-Y., Zhang, Y., & Lipscomb, W. N. (1991) Biochemistry 30, 4412-4420] of the pig kidney fructose-1,6-bisphosphatase (EC 3.1.3.11) reveals major changes in the quaternary structure of the enzyme upon the binding of the allosteric inhibitor AMP. This change in quaternary structure involves the breaking of one set of interactions that stabilize the R state and the formation of another set of interactions that stabilize the T state of the enzyme. In particular, the interactions of Arg-22 with nearby amino acid residues are quite different in the R and T states of the enzyme. Although the crystallographic data suggest that intersubunit interactions such as those involving Arg-22 are important for stabilization of the R and/or T states, the X-ray structures do not provide direct evidence concerning the functional role of specific amino acid residues. Therefore, site-specific mutagenesis has been used to probe the function of Arg-22 in pig kidney fructose-1,6-bisphosphatase. The replacement of Arg-22 by Ala results in a mutant enzyme with enhanced catalytic efficiency compared to the wild-type, as indicated by a kinetic analysis showing a slightly lower Km and increased Vmax compared to the wild-type enzyme. In addition, the substitution enhances both substrate inhibition and the affinity of the inhibitor fructose 2,6-bisphosphate. Moreover, the replacement of Arg-22 by Ala results in a more than 10-fold loss of the ability of AMP to inhibit the enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)

Shared active sites of fructose-1,6-bisphosphatase. Arginine 243 mediates substrate binding and fructose 2,6-bisphosphate inhibition.

The active site of pig kidney fructose-1,6-bisphosphatase (EC 3.1.3.11) is shared between subunits, Arg-243 of one chain interacting with fructose-1,6-bisphosphate or fructose-2,6-bisphosphate in the active site of an adjacent chain. In this study, Arg-243 was replaced by alanine using techniques of site-specific mutagenesis and the cloned pig kidney enzyme expressed in Escherichia coli. Compared with wild-type enzyme, kinetic parameters of the altered enzyme characterizing catalytic efficiency, magnesium binding, and inhibition by AMP differed but by less than an order of magnitude; affinity for substrate fructose 1,6-bisphosphate was 10-fold poorer, and affinity for inhibitor fructose 2,6-bisphosphate was 1000-fold poorer. Molecular dynamics simulations were undertaken to determine possible alterations in active sites of the enzyme due to replacement of Arg-243 by Ala and suggested that in the mutant enzyme loss of one cationic group leads to reorganization of the active site especially involving lysine residues 269 and 274. The differences in properties of the mutant enzyme indicate the key importance of Arg-243 in the function of fructose-1,6-bisphosphatase and confirm on a functional basis the shared active site in this important metabolic enzyme.

Alfalfa yield response to inoculation with recombinant strains of Rhizobium meliloti with an extra copy of dctABD and/or modified nifA expression.

The construction of rhizobial strains which increase plant biomass under controlled conditions has been previously reported. However, there is no evidence that these newly constructed strains increase legume yield under agricultural conditions. This work tested the hypothesis that carefully manipulating expression of additional copies of nifA and dctABD in strains of Rhizobium meliloti would increase alfalfa yield in the field. The rationale for this hypothesis is based on the positive regulatory role that nifA plays in the expression of the nif regulon and the fact that a supply of dicarboxylic acids from the plant is required as a carbon and energy source for nitrogen fixation by the Rhizobium bacteroids in the nodule. These recombinant strains, as well as the wild-type strains from which they were derived, are ideal tools to examine the effects of modifying or increasing the expression of these genes on alfalfa biomass. The experimental design comprised seven recombinant strains, two wild-type strains, and an uninoculated control. Each treatment was replicated eight times and was conducted at four field sites in Wisconsin. Recombinant strain RMBPC-2, which has an additional copy of both nifA and dctABD, increased alfalfa biomass by 12.9% compared with the yield with the wild-type strain RMBPC and 17.9% over that in the uninoculated control plot at the site where soil nitrogen and organic matter content was lowest. These increases were statistically significant at the 5% confidence interval for each of the three harvests made during the growing season. Strain RMBPC-2 did increase alfalfa biomass at the Hancock site; however, no other significant increases or decreases in alfalfa biomass were observed with the seven other recombinant strains at that site. At three sites where this experiment was conducted, either native rhizobial populations or soil nitrogen concentrations were high. At these sites, none of the recombinant strains affected yield. We conclude that RMBPC -2 can increase alfalfa yields under field conditions of nitrogen limitation, low endogenous rhizobial competitors, and sufficient moisture.

Isolation and sequence analysis of the cDNA for pig kidney fructose 1,6-bisphosphatase.

A full-length clone of pig kidney fructose 1,6-bisphosphatase (D-fructose-1,6-bisphosphate 1-phosphohydrolase, EC 3.1.3.11) was isolated by screening a cDNA library for complementation of an Escherichia coli fbp deletion mutation. The open reading frame of 1011 bases corresponds to 337 amino acids, two more than have been previously reported [Marcus, F., Edelstein, I., Reardon, I. & Heinrikson, R. L. (1982) Proc. Natl. Acad. Sci. USA 79, 7161-7165]. The extra two amino acids (Ala-Lys) are located at the C-terminal end of the protein as an extension. Comparison of the deduced amino acid sequence with the reported (see above) and revised amino acid sequence [Harrsch, P. B., Kim, Y., Fox, J. L. & Marcus, F. (1985) Biochem. Biophys. Res. Commun. 133, 520-526] indicates three differences in addition to the C-terminal extension. Gln-20, Thr-96, and Asn-199 in the amino acid sequence are found to be Glu, Ser, and Asp, respectively. Since the x-ray structure of the pig kidney enzyme has been reported, the cDNA clone will allow the construction of site-specific mutants to help test possible structure-function relationships in this important metabolic enzyme.

Allan-Herndon-Dudley syndrome: clinical and linkage studies on a second family.

We restudied a family with X-linked mental retardation (XLMR) originally reported in abstract form by Davis et al. [1981]. All 8 living affected males were examined. Characteristics included severe mental retardation, spastic paraplegia, dysarthria, muscle wasting, scoliosis, broad shallow pectus excavatum, long face, large ears with minor modeling anomalies, foot deformities, joint contractures, and neck drop. Stature, OFC, testicular volume, high resolution chromosome and fragile X studies, and plasma amino acids were all normal. Their manifestations closely resemble those of a large family with XLMR originally reported by Allan et al. [1944] and restudied by Stevenson et al. [1990]. This condition has been termed the Allan-Herndon-Dudley syndrome (AHDS). As AHDS has been mapped to Xq21, mapping studies were undertaken to determine if this family maps to the same location. These studies demonstrate tight linkage to Xq21, with a maximum lod score of 2.88 obtained with probe pX65H7 (DXS72). Multipoint analysis located the mutant gene quite close to pX65H7 (multipoint Z = 4.14), slightly more proximal in Xq21 than was suggested by the data from the original AHDS family. It appears likely that this family is the second reported family with AHDS.

Intrauterine cytomegalovirus infection presenting as fetal meconium peritonitis.

Recent reports have suggested that focal hyperechoic abdominal masses detected during the second trimester may represent a normal variation in fetal intestinal development that is transient in nature and not associated with pathologic conditions. The patient described here had second-trimester ultrasonic findings of fetal meconium peritonitis without ascites, polyhydramnios, or other anomalies. Subsequent ultrasound examinations at 22, 30, and 36 weeks demonstrated no change in the abdominal appearance. At birth, this preterm male infant had clinical symptoms of congenital cytomegalovirus infection confirmed by viral culture and serologic studies. Retrospective studies of maternal serum obtained early in the second trimester confirmed a primary cytomegalovirus infection 4 weeks before the initial ultrasound examination. Although fetal hydrops and ascites have occasionally been associated with intrauterine cytomegalovirus infection, fetal meconium peritonitis has not been previously recognized in patients with congenital cytomegalovirus.