A new boronate ester-based crosslinking strategy allows the design of nonswelling and long-term stable dynamic covalent hydrogels

Dynamic hydrogels are viscoelastic materials that can be designed to be self-healing, malleable, and injectable, making them particularly interesting for a variety of biomedical applications. To design dynamic hydrogels, dynamic covalent crosslinking reactions are attracting increasing attention. However, dynamic covalent hydrogels tend to swell, and often lack stability. Boronate ester-based hydrogels, which result from the dynamic covalent reaction between a phenylboronic acid (PBA) derivative and a diol, are based on stable precursors, and can therefore address these limitations. Yet, boronate ester formation hardly occurs at physiological pH. To produce dynamic covalent hydrogels at physiological pH, we performed a molecular screening of PBA derivatives in association with a variety of diols, using hyaluronic acid as a polymer of interest. The combination of Wulff-type PBA (wPBA) and glucamine stood out as a unique couple to obtain the desired hydrogels. We showed that optimized wPBA/glucamine hydrogels are minimally- to non-swelling, stable long term (over months), tunable in terms of mechanical properties, and cytocompatible. We further characterized their viscoelastic and self-healing properties, highlighting their potential for biomedical applications.

Management of work-related common mental disorders in general practice: a cross-sectional study

BACKGROUND

General practitioners (GPs) often manage individuals with work-related common mental disorders (CMD: depressive disorders, anxiety and alcohol abuse). However, little is known about the ways in which they proceed. The aim of this study is to analyze GPs' management and patterns of referral to other health professionals of patients with work-related CMD and associated factors.

METHOD

We used data from a cross-sectional study of 2027 working patients of 121 GPs in the Nord - Pas-de-Calais region in France (April - August 2014). Statistical analyses focused on patients with work-related CMD detected by the GP and examined the ways in which GPs managed these patients' symptoms. Associations between patient, work, GP and contextual characteristics and GPs' management were explored using modified Poisson regression models with robust variance.

RESULTS

Among the 533 patients with work-related CMD in the study, GPs provided psychosocial support to 88.0%, prescribed psychotropic treatment to 82.4% and put 50.7% on sick leave. Referral rates to mental health specialists and occupational physicians were respectively 39.8 and 26.1%. Several factors including patients' characteristics (occupational and sociodemographic), GPs' characteristics and environmental data were associated with the type of management used by the GP.

CONCLUSION

Our study emphasizes the major and often lonesome role of the GP in the management of patients with work-related CMDs. Better knowledge of the way GPs manage those patients could help GPs in their practice, improve patients care and be a starting point to implement a more collaborative care approach.

[Impact of sonography simulation in the training of midwifery students]

OBJECTIVE

During their studies, French midwives need to acquire basic ultrasound skills to measure the amniotic fluid index, fetal biometry and identify fetal lie and placental positions. They have a clinical ultrasound training during their curriculum to acquire these skills. Assess the contribution that a training on an obstetrical ultrasound simulator (OUS) could make to the competence of midwives and to evaluate the best time to integrate it into their curriculum.

METHODS

Forty students in their 4th and final year in midwifery were randomized into 2 groups. Group A learned with the traditional academic course, with a clinical ultrasound training which was followed by an evaluation on an OUS (E1A). Group B was evaluated on a simulator before the clinical ultrasound training (E1B). After these initial assessments, both groups were provided with learning and training sessions on OUS, and re-evaluated in the same exercise (E2A and E2B). Group B then completed its clinical ultrasound training and was evaluated one month later on the simulator (E3B). The evaluation consisted of scoring the biometry images according to previously published quality criteria, and of assessing their competence based on a published objective and structured assessment score of ultrasound skills (OSAUS).

RESULTS

Evaluation 1 found comparable OSAUS scores (2.375/5 vs. 2.24/5 P=0.52) between the two groups (E1A vs. E1B) but a significantly higher image quality score for Group A (P=0.02). In Evaluation 2, an improvement was noted for both groups with comparable OSAUS averages between the two groups (P=0.76). After the clinical training of Group B, their OSAUS score (E3B) was significantly better than that of Group A (E1A) after their clinical training (3.45/5 vs. 2.375/5 [P=0.00017]). The same was true for the quality of their images (12.67/16 vs. 9.95/16 [P=0.003]).

CONCLUSION

Ultrasound simulation-based training, as an adjunct to ultrasound clinical training, significantly improves obstetrical ultrasound skills. The best time to train on simulators seems to be prior to clinical training on real patients.

Work intensity in men and work-related emotional demands in women are associated with increased suicidality among persons attending primary care

BACKGROUND

A large proportion of persons died by suicide are employed at the time of death and work-related factors partly contribute to suicide risk. Our aim was to examine the association between multiple aspects of work organization and suicidal ideation in a study conducted in primary care.

METHODS

Data came from a study of 2027 working patients attending a GP representative of patients in the Nord Pas-de-Calais region in France (April-August 2014). Suicidality was assessed using the MINI (Mini International Neuropsychiatric Interview). Six emergent worked-related factors were explored (work intensity, emotional demands, autonomy, social relationships at work, conflict of values, insecurity of work). Several covariates were considered: patient's and GP's characteristics, and area-level data (material and social deprivation, psychiatrist and GPs' density, suicide attempts and suicide rates).

RESULTS

8.0% of participants reported suicidal ideation in the preceding month (7.5% of men and 8.6% of women, p = .03). In multivariate analyses adjusted for covariates, suicidality was significantly associated with work intensity (OR = 1.65; 95%CI [1.18-2.31]) in men and with work-related emotional demands (OR = 1.35; 95%CI [1.01-1.80]) in women. Area-level data were not associated.

LIMITATIONS

Our cross-sectional study cannot assess the direction of the relationships under study.

CONCLUSION

Our results emphasise a central role for GPs in suicide prevention among workers and highlight the importance of work-related factors with regard to suicidality in primary care.

[Awareness and adherence to Pertussis vaccination guidelines by occupational medicine physicians in Paris healthcare institution]

OBJECTIVE

A questionnaire was used on 44 public and private hospital physicians in Paris to evaluate their knowledge of and adherence to Vaccination Guidelines, three years after their introduction.

RESULTS

Eighty per cent of the physicians answered and 92.5% were aware of the vaccination guidelines but only 2 out of 4 respected the targeted vaccination in young adults even when the vaccine was available. A policy of pertussis vaccination was applied only in 12 institutions, but even in these, the rate of vaccinated healthcare workers remained low or was not documented.

CONCLUSION

Pertussis is a potential risk to newborns not or partially vaccinated in France. Even if the vaccine is available, adherence to pertussis vaccination guidelines must be improved. Efforts should be made to better publicize and apply pertussis vaccination guidelines.

Contrasting epistatic interactions between rat quantitative trait loci controlling mammary cancer development

We previously defined quantitative trait loci (QTLs) that control susceptibility to 7,12-dimethylbenz(alpha)anthracene-induced mammary carcinoma in SPRD-Cu3 (susceptible) and WKY (resistant) rats. Two of these QTLs, assigned to chromosomes (Chr) 10 and 18, control tumor growth rate and invasiveness. In this study we characterized a congenic strain in which a large segment of WKY Chr 10 was introduced in the SPRD-Cu3 genetic background and demonstrated that this chromosome segment controls this tumor trait. The WKY allele at this QTL (Mcsta1) reduces the growth rate of the fastest growing tumors by 26%. We also previously showed that two SPRD-Cu3-WKY congenic strains containing a WKY chromosome segment derived either from Chr 5 or from Chr 18 exhibit a reduction in tumor multiplicity (QTLs Msctm1 and Mcstm2, respectively) (with no reduction in tumor growth rate in the Chr 18 congenic). In this study we generated a double congenic strain, which contains the two WKY differential segments from Chr 5 and 18, to determine how these two segments interact with one another. Interestingly, two types of epistatic interactions were found: no additive effect was seen with respect to tumor multiplicity, while a reduction in tumor growth rate was observed. It thus appears that WKY alleles located on Chr 5 and Chr 8 interact epistatically in a contrasting manner to modulate tumor multiplicity (in a nonadditive manner) and growth rate (in a synergic manner). Tumor growth rate is thus influenced by two QTLs, on Chr 10 (Mcsta1) and on Chr 18 (Mcsta2), the action of the latter being dependent on the presence of the Chr5 QTL (Mcstm1). The expression level of positional and functional candidate genes was also analyzed. On Chr 5, Pla2g2a is subject to a syntenic control while expression of the Tp53 (Chr 10) and Pmai1/Noxa (Chr 18) genes appears to be controlled by several mammary cancer resistance QTLs.

Rat gene mapping in the post-genome sequencing era: the continued utility of cell hybrids to localize rat genes (Cks2, Ephb4, Fabp5, Il13ra1, Rpl10, Ssr4)

Finding the position of a gene is now easily done when the genome sequence is available: the gene position is generally found by a simple query of genomic databases such as those available at the Ensembl browser or the NCBI. We were interested in determining the position of 125 cancer-related rat genes and we found that the position of most of these genes (110) could indeed be identified in this manner. However, in 15 cases, the gene position was not available in these databases, or the results were ambiguous. We then explored a more specialized database, namely the Rat Genome Database, and experimentally mapped these genes using standard and radiation cell hybrids. The 15 genes in question could be localized unambiguously. In four cases, the radiation cell hybrids were indispensable: the sequence of these four genes could not be found in the rat genome sequence. On the basis of the sample we examined, it thus appears that a classical gene mapping method is still required to localize about 3% of the rat genes, as if 3% of the rat gene sequences were lacking in the current rat genome sequence.

Isolation of two regions on rat chromosomes 5 and 18 affecting mammary cancer susceptibility

We previously mapped several quantitative trait loci (QTLs) controlling DMBA-induced mammary tumor development in female rats derived from a SPRD-Cu3 (susceptible strain) x WKY (resistant strain) cross. Two of these QTLs were assigned to chromosomes 5 and 18. In the present study, we generated and characterized congenic strains in which a segment of WKY chromosomes 5 or 18 was introduced in the SPRD-Cu3 genetic background, thereby physically demonstrating that each of these two chromosomes controls mammary tumor multiplicity. The chromosome 5 QTL (Mcstm1) accounts for 7 tumors per animal (versus a total of 11 tumors per SPRD-Cu3 rat). The chromosome 18 QTL (Mcstm2) accounts for 3 tumors per animal and is the first chemically-induced mammary cancer susceptibility locus assigned to this chromosome. In addition, the Mcstm1 region was shown to also controls tumor latency. These loci thus play a major role in chemically-induced mammary tumor development. QTLs controlling chemically-induced or estrogen-induced mammary tumor development have independently been identified on chromosomes 5 and 18, using susceptible strains others than SPRD-Cu3. Therefore the haplotype structure of the relevant chromosome regions was analyzed in the different strains. Some chromosome regions were found to be highly mosaic (haplotype blocks < 1 Mb), while one region showed an apparently conserved haplotype block of 7.5 Mb. This analysis points to limited regions that could harbor the causative genes and also indicates that at least Mcstm2 is a novel QTL.

Mammary cancer resistance and precocious mammary differentiation in the WKY rat: Identification of 2 quantitative trait loci

The COP and WKY rat strains are resistant to mammary cancer. It has shown previously that upon chemical carcinogen treatment, COP females exhibit mammary preneoplastic lesions which disappear within a few weeks. We show here that in similar conditions, WKY females do not exhibit any visible preneoplastic lesions. WKY females are characterized by precocious mammary tissue differentiation, including active expression of the beta-casein gene in young virgin females. This trait might be critical in resistance to mammary carcinogenesis of WKY rats. To test this hypothesis, we took advantage of 2 congenic strains that contain a limited chromosome segment of WKY origin, derived either from chromosome 5 or from chromosome 18, introgressed in the susceptible genetic background (SPRD-Cu3). Each of these congenic strains has been shown to be partially resistant to chemically induced mammary carcinogenesis (reduction in tumour multiplicity with respect to the susceptible SPRD-Cu3 rats). We show here that these 2 congenic strains also exhibit precocious mammary differentiation, though to a lower extent than the WKY females. The conclusion of this study is thus 2-fold: (i) eradication of preneoplastic lesions is not a general phenomenon in mammary cancer resistance; (ii) the same segment of rat chromosomes 5 or 18 that controls mammary cancer resistance also contains a quantitative trait locus imposing precocious mammary differentiation. These 2 traits are thus associated, supporting the hypothesis that there might be a cause-effect relationship between precocious mammary differentiation and cancer resistance.

Genetic identification of distinct loci controlling mammary tumor multiplicity, latency, and aggressiveness in the rat

The rat is considered an excellent model for studying human breast cancer. Therefore, understanding the genetic basis of susceptibility to mammary cancer in this species is of great interest. Previous studies based on crosses involving the susceptible strain WF (crossed with the resistant strains COP or WKY) and focusing on tumor multiplicity as the susceptibility phenotype led to the identification of several loci that control chemically induced mammary cancer. The present study was aimed to determine whether other loci can be identified by analyzing crosses derived from another susceptible strain on the one hand, and by including phenotypes other than tumor multiplicity on the other hand. A backcross was generated between the susceptible SPRD-Cu3 strain and the resistant WKY strain. Female progeny were genotyped with microsatellite markers covering all rat autosomes, treated with a single dose of DMBA, and phenotyped with respect to tumor latency, tumor multiplicity, and tumor aggressiveness. Seven loci controlling mammary tumor development were detected. Different loci control tumor multiplicity, latency, and aggressiveness. While some of these loci colocalize with loci identified in crosses involving the susceptible strain WF, new loci have been uncovered, indicating that the use of distinct susceptible and resistant strain pairs will help in establishing a comprehensive inventory of mammary cancer susceptibility loci.

Chromosome evolution of MMU16 and RNO11: conserved synteny associated with gene order rearrangements explicable by intrachromosomal recombinations and neocentromere emergence

Comparative mapping between the rat and mouse genomes has shown that some chromosomes are entirely or almost entirely conserved with respect to gene content. Such is the case of rat chromosome 11 (RNO11) and mouse chromosome 16 (MMU16). We determined to what extent such an extensive conservation of synteny is associated with a conserved gene order. Therefore, we regionally localized several genes on RNO11. The comparison of the gene map of RNO11 and MMU16 unambiguously shows that the gene order has not been conserved in the Murinae lineage, thereby implying the occurrence of intrachromosomal evolutionary rearrangements. The transition from one chromosome configuration to the other one can be explained either by two intrachromosomal recombinations or by a single intrachromosomal recombination accompanied by neocentromere emergence.

Importance of the lid and cap domains for the catalytic activity of gastric lipases

Human gastric lipase (HGL) is an enzyme secreted by the stomach, which is stable and active despite the highly acidic environment. It has been clearly established that this enzyme is responsible for 30% of the fat digestion processes occurring in human. This globular protein belongs to the alpha/beta hydrolase fold family and its catalytic serine is deeply buried under a domain called the extrusion domain, which is composed of a 'cap' domain and a segment consisting of 58 residues, which can be defined as a lid. The exact roles played by the cap and the lid domains during the catalytic step have not yet been elucidated. We have recently solved the crystal structure of the open form of the dog gastric lipase in complex with a covalent inhibitor. The detergent molecule and the inhibitor were mimicking a triglyceride substrate that would interact with residues belonging to both the cap and the lid domains. In this study, we have investigated the role of the cap and the lid domains, using site-directed mutagenesis procedures. We have produced truncated mutants lacking the lid and the cap. After expressing these mutants and purifying them, their activity was found to have decreased drastically in comparison with the wild type HGL. The lid and the cap domains play an important role in the catalytic reaction mechanism. Based on these results and the structural data (open form of DGL), we have pointed out the cap and the lid residues involved in the binding with the lipidic substrate.

Genetic identification of multiple susceptibility genes involved in the development of endometrial carcinoma in a rat model

There are clear indications that inheritance plays an essential role in certain cases of human endometrial cancer, and there are at least 2 forms of early-onset heritable endometrial adenocarcinomas (EACs). Females of the BDII inbred rat strain are known to be genetically predisposed to endometrial carcinoma, and we have performed a genetic analysis of susceptibility to endometrial cancer in this strain. F(2) populations were generated by crossing BDII females with males from 2 different strains with a low incidence of EAC, and the occurrence of endometrial cancer was studied. Three chromosome regions associated to EAC susceptibility were identified, and the susceptibility genes in these regions were designated Ecs1, Ecs2 and Ecs3. Our results indicate that the genes affecting susceptibility to EAC are different in the 2 crosses, suggesting that the genes behind the susceptibility in BDII animals may interact with different genes in different genetic backgrounds.

Mapping of the rat glypican genes

The glypicans compose a family of glycosylphosphatidylinositol (GPI)-anchored heparan sulfate proteoglycans that play a role in the control of cell division and growth regulation. So far, six members (GPC1-6) of this family are known in vertebrates. The rat glypican gene 3 (Gpc3) was previously assigned to chromosome Xq36 (Shen et al., 1997). Using standard and radiation cell hybrids, we localized the five other rat glypican genes.

Crystallization and preliminary crystallographic study of a recombinant phospholipase D from cowpea (Vigna unguiculata L. Walp)

The plant phospholipase D (PLD) is considered to be a key enzyme involved in various physiological processes such as signal transduction and membrane metabolism. Crystals of the PLD protein from Vigna unguiculata have been produced from the recombinant 768 amino-acid protein. The crystals belong to the monoclinic space group C2, with unit-cell parameters a = 157.7, b = 65.6, c = 90.2 A, beta = 111.5 degrees. There is one molecule in the asymmetric unit. Frozen crystals diffract to at least 1.94 A resolution using synchrotron radiation. A search for heavy-atom derivatives using ytterbium and tungstate is currently under way in order to solve the three-dimensional structure.

Identification of KLF13 and KLF14 (SP6), novel members of the SP/XKLF transcription factor family

Using the sequence of the SP1 zinc-finger DNA-binding domain as a probe to screen a mouse EST database, we identified two novel members of the SP/XKLF transcription factor family, KLF13 and KLF14. The mouse Klf13 cDNA (1310 bp in length) contains a single open reading frame of 288 amino acids with a DNA-binding domain closely related to that of the human RFLAT-1 protein and a putative transactivator N-terminal domain rich in proline and alanine residues. The mouse Klf13 gene seems to be the homologue of the human RFLAT1 gene. The mouse Klf14 sequence is homologous to a human genomic sequence from chromosome 17 that is believed to code for a protein with three zinc fingers at the end of its C-terminal domain. Using reverse transcription-polymerase chain reaction, we showed ubiquitous expression of Klf13 and Klf14 in adult mice. A third member of this family was also identified in a human EST database; this sequence was found to be identical to KLF11 (TIEG2), recently identified by Cook et al. (1998, J. Biol. Chem. 273: 25929-25936). The corresponding mouse cDNA was isolated and sequenced. The three genes were localized in the human and the rat: chromosomes 15 (human KLF13), 17q21.3-q22 (human KLF14; HGMW-approved symbol SP6), and 2p25 (human KLF11) and chromosomes 1q31-q32 (rat Klf13), 10q31-q32.1 (rat Klf14) (SP6), and 6q16-q21 (rat Klf11).

Functional expression in insect cells, one-step purification and characterization of a recombinant phospholipase D from cowpea (Vigna unguiculata L. Walp)

Phospholipase D (PLD) is an important enzyme involved in signal transduction, vesicle trafficking and membrane metabolism. In this study, large amounts of a recombinant plant PLD alpha were secreted into the culture medium of baculovirus-infected insect cells and purified to homogeneity in the form of a fully active enzyme. The transient production of recombinant PLD alpha yielded a protein (rPLD alpha a, 88 kDa) together with a shorter form (rPLD alpha b, 87 kDa), which accumulated in the medium. N-Terminal amino acid sequencing of the rPLD alpha a and rPLD alpha b showed that rPLD alpha b resulted from proteolytic cleavage at Gly8-Ile9. Immunoblotting showed that both rPLD alpha a and rPLD alpha b are recognized by a polyclonal antibody previously raised against native soybean PLD alpha. One-step calcium-dependent octyl-Sepharose chromatography was used to obtain the two highly purified forms of rPLD alpha, as attested by gel electrophoresis, N-terminal amino acid sequence and mass spectrometry. The N-terminal region of PLD alpha is homologous with the C2 domains which are present in a number of enzymes known to be involved in signal transduction and/or phospholipid metabolism. The truncated rPLD alpha b lacks the first acidic amino acid in its N-terminus, which is probably involved in the calcium binding site. The rPLD alpha b was thus easily eluted from the octyl-Sepharose column by decreasing the calcium concentration of the buffer from 50 to 30 mM, whereas, the rPLD alpha a was eluted after chelating calcium ions with EDTA. The purified rPLD alpha yield reached a level of 10 mg per liter of serum-free culture medium. The availability of baculovirus-derived rPLD alpha constitutes a valuable source of enzyme for future crystallographic studies to determine its three-dimensional structure.

Digestive lipases: from three-dimensional structure to physiology

Human gastric lipase (HGL) is a lipolytic enzyme that is secreted by the chief cells located in the fundic part of the stomach. HGL plays an important role in lipid digestion, since it promotes the subsequent hydrolytic action of pancreatic lipase in duodenal lumen. Physiological studies have shown that HGL is able of acting not only in the highly acid stomach environment but also in the duodenum in synergy with human pancreatic lipase (HPL). Recombinant HGL (r-HGL) was expressed in the baculovirus/insect cell system in the form of an active protein with a molecular mass of 45 kDa. The specific activities of r-HGL were found to be similar to that of the native enzyme when tested on various triacylglycerol (TG) substrates. The 3-D structure of r-HGL was the first solved within the mammalian acid lipase family. This globular enzyme (379 residues) shows a new feature, different from the other known lipases structures, which consists of a core domain having the alpha/beta hydrolase fold and a cap domain including a putative 'lid' of 30 residues covering the active site of the lipase (closed conformation). HPL is the major lipolytic enzyme involved in the digestion of dietary TG. HPL is a 50 kDa glycoprotein which is directly secreted as an active enzyme. HPL was the first mammalian lipase to be solved structurally, and it revealed the presence of two structural domains: a large N-terminal domain (residues 1-336) and a smaller C-terminal domain (residues 337-449). The large N-terminal domain belongs to the alpha/beta hydrolase fold and contains the active site. A surface loop called the lid domain (C237-C261) covers the active site in the closed conformation of the lipase. The 3-D structure of the lipase-procolipase complex illustrates how the procolipase might anchor the lipase at the interface in the presence of bile salts: procolipase binds to the C-terminal domain of HPL and exposes the hydrophobic tips of its fingers at the opposite site of its lipase-binding domain. These hydrophobic tips help to bring N-terminal domain into close conformation with the interface where the opening of the lid domain probably occurs. As a result of all these conformational changes, the open lid and the extremities of the procolipase form an impressive continuous hydrophobic plateau, extending over more than 50 A. This surface might able to interact strongly with a lipid-water interface. The biochemical, histochemical and clinical studies as well as the 3-D structures obtained will be a great help for a better understanding of the structure-function relationships of digestive lipases.

Localization of 54 rat genes, and definition of new synteny groups conserved in the human and the rat

In order to improve the rat gene map and comparative mapping with the human and the mouse, we determined the chromosome localization of 54 rat genes. Most genes encode transcription factors or other regulatory proteins of cancer relevance. The human homologs of four genes were also assigned to their respective chromosome. These data generated anchor points between the recently established radiation hybrid maps and the genetic and cytogenetic maps. They improve comparative mapping between the rat, the mouse, and the human gene maps, and in particular they disclose four new synteny groups conserved in the rat and the human. These new localizations should also be useful for the identification of genes involved in the control of quantitative traits such as cancer susceptibility or diabetes.

Lipoglycans are putative ligands for the human pulmonary surfactant protein A attachment to mycobacteria. Critical role of the lipids for lectin-carbohydrate recognition

The human pulmonary surfactant protein A (hSP-A) has been implicated in the early capture and phagocytosis of the pathogenic Mycobacterium tuberculosis by alveolar macrophages. In this report, we examined the interaction of alveolar proteinosis patient hSP-A with Mycobacterium bovis BCG, the vaccinating strain, as a model of pathogenic mycobacteria, and Mycobacterium smegmatis, a nonpathogenic strain. We found that hSP-A binds to the surface of M. bovis BCG, but also to a slightly lesser extent, to M. smegmatis, indicating that hSP-A does not discriminate between virulent and nonpathogenic strains. Among the various glycoconjugates isolated from the mycobacterial envelope, we found that the best ligands are the two major lipoglycans: the mannosylated lipoarabinomannan (ManLAM) and the lipomannan. In contrast, the mannose-capped arabinomannan, structurally close to the ManLAM, as well as the LAMs from the non pathogenic M. smegmatis are poorly recognized by hSP-A. These results clearly show that the presence of both the terminal mannose residues and the phophatidyl-myo-inositol anchor are necessary to achieve the highest binding affinity. Selective removal of either the terminal mannose or the acyl residues esterifying the glycerol moiety of the ManLAM abrogates the interaction with hSP-A, further supporting the notion that the hSP-A recognition of the carbohydrate epitopes of the lipoglycans is dependent of the presence of the fatty acids.

Decreased capacity of recombinant 45/47-kDa molecules (Apa) of Mycobacterium tuberculosis to stimulate T lymphocyte responses related to changes in their mannosylation pattern

The Apa molecules secreted by Mycobacterium tuberculosis, Mycobacterium bovis, or BCG have been identified as major immunodominant antigens. Mass spectrometry analysis indicated similar mannosylation, a complete pattern from 1 up to 9 hexose residues/mole of protein, of the native species from the 3 reference strains. The recombinant antigen expressed in M. smegmatis revealed a different mannosylation pattern: species containing 7 to 9 sugar residues/mole of protein were in the highest proportion, whereas species bearing a low number of sugar residues were almost absent. The 45/47-kDa recombinant antigen expressed in E. coli was devoid of sugar residues. The proteins purified from M. tuberculosis, M. bovis, or BCG have a high capacity to elicit in vivo potent delayed-type hypersensitivity (DTH) reactions and to stimulate in vitro sensitized T lymphocytes of guinea pigs immunized with living BCG. The recombinant Apa expressed in Mycobacterium smegmatis was 4-fold less potent in vivo in the DTH assay and 10-fold less active in vitro to stimulate sensitized T lymphocytes than the native proteins. The recombinant protein expressed in Escherichia coli was nearly unable to elicit DTH reactions in vivo or to stimulate T lymphocytes in vitro. Thus the observed biological effects were related to the extent of glycosylation of the antigen.

Cost of chickenpox in Canada: part I. Cost of uncomplicated cases

OBJECTIVE

The purpose of this study was to assess the direct medical costs and productivity losses associated with uncomplicated chickenpox (no hospitalization) in Canada.

METHODS

A total of 179 otherwise healthy 1- to 9-year-old children with active chickenpox were recruited from schools, day care centers, and physician offices in 5 provinces. Direct medical (physician contacts, medication, and diagnostic tests) and nonmedical (personal expenses including child care) resources expended during the illness were determined by caregiver interview. Productivity losses attributable to the disease were determined by assessing caregiver time lost from work and daily activities. Unit costs for all resources were obtained from sources in 2 provinces, and per-patient treatment costs were determined from the patient, Ministry of Health, and societal perspectives.

RESULTS

From a societal perspective, the per-case cost for children from 1 to 4 years of age and from 5 to 9 years of age was $370.2 and $236.5, respectively. Direct medical costs accounted for 10% of the total costs in both groups. The largest cost driver in patient care was caregiver productivity losses, which amounted to $316.5 in the younger age group and to $182.7 in the older age group. Based on an estimated yearly incidence of 344 656 cases of uncomplicated chickenpox in Canada, the total annual societal burden of the disease can be estimated at $109.2 million, with a cost to the Ministry of Health of $11.2 million.

CONCLUSION

Chickenpox is one of the last common childhood diseases prevalent in Canada, and the uncomplicated disease, despite its rather benign course, imparts a large annual economic burden.

Cost of chickenpox in Canada: part II. Cost of complicated cases and total economic impact. The Immunization Monitoring Program-Active (IMPACT)

OBJECTIVE

Primarily, to determine the direct medical costs and productivity losses associated with complicated chickenpox (hospitalized cases) and, secondarily, to quantify the overall economic burden of chickenpox in Canada.

METHODS

Direct medical resource consumption patterns were determined by chart review of 160 otherwise healthy children and 40 children with leukemia hospitalized for chickenpox. Children were selected from the database of the Immunization Monitoring Program Active (IMPACT), a network of 11 tertiary-care hospitals in Canada that collected information at the time of hospitalization from January 1991 to March 1996. An additional 26 healthy children hospitalized were recruited prospectively by IMPACT. Productivity losses (time lost from work and daily activities) were assessed by caregiver interviews. Treatment costs were determined from the patient, Ministry of Health, and societal perspectives.

RESULTS

The average societal per case cost for complicated chickenpox in healthy children was $7060 and $8398, respectively, from the retrospective and prospective assessments. For children with leukemia, the direct medical cost was estimated at $7228. These costs were combined with a cost established previously for uncomplicated chickenpox. The estimated yearly overall economic impact of chickenpox in Canada was $122.4 million, with $24.0 million attributable to Ministry of Health costs, assuming an estimated yearly incidence of 346 527 cases and a 0.54% rate of hospitalization for healthy children.

CONCLUSIONS

Direct medical costs are the major cost driver in the care of complicated chickenpox. However, in the context of the overall economic burden of the disease, uncomplicated chickenpox is the major cost driver, contributing 89% to the total cost.

Crystal structure of human gastric lipase and model of lysosomal acid lipase, two lipolytic enzymes of medical interest

Fat digestion in humans requires not only the classical pancreatic lipase but also gastric lipase, which is stable and active despite the highly acidic stomach environment. We report here the structure of recombinant human gastric lipase at 3.0-A resolution, the first structure to be described within the mammalian acid lipase family. This globular enzyme (379 residues) consists of a core domain belonging to the alpha/beta hydrolase-fold family and a "cap" domain, which is analogous to that present in serine carboxypeptidases. It possesses a classical catalytic triad (Ser-153, His-353, Asp-324) and an oxyanion hole (NH groups of Gln-154 and Leu-67). Four N-glycosylation sites were identified on the electron density maps. The catalytic serine is deeply buried under a segment consisting of 30 residues, which can be defined as a lid and belonging to the cap domain. The displacement of the lid is necessary for the substrates to have access to Ser-153. A phosphonate inhibitor was positioned in the active site that clearly suggests the location of the hydrophobic substrate binding site. The lysosomal acid lipase was modeled by homology, and possible explanations for some previously reported mutations leading to the cholesterol ester storage disease are given based on the present model.

Site-directed removal of N-glycosylation sites in human gastric lipase

Human gastric lipase (HGL) is a highly glycosylated protein, as glycan chains account for about 15% of the molecular mass of the native HGL. Four potential N-glycosylation consensus sites (Asn15, 80, 252 and 308) can be identified from the HGL amino acid sequence. We studied the functional role of the individual N-linked oligosaccharide chains by removing one by one all the N-glycosylation sites, via Ala residue replacement by site-directed mutagenesis of Ser and Thr residues from the consensus sequences Asn-X-Ser/Thr. Mutagenized cDNA constructs were heterologously expressed in the baculovirus/insect cell system. Removal of oligosaccharides either at Asn15, 80 or 252 was found to have no significant influence on the enzymatic activity measured in vitro. However, the absence of glycosylation at Asn308, as well as a total deglycosylation, reduced the specific enzymatic activity of recombinant HGL (r-HGL), measured on short- and long-chain triglycerides, to about 50% of normal values. Furthermore, biosynthesis and secretion of r-HGL markedly dropped when all four potential glycosylation sites were mutated. The kinetics of the interfacial adsorption of r-HGL and the completely deglycosylated r-HGL (four-site mutant) were found to be identical when recording the changes with time of the surface pressure either at the air-water interface or in the presence of an egg phosphatidylcholine (PtdCho) monomolecular film spread at various initial surface pressures. This indicates that both recombinant HGLs are identical, as far as recognition of phospholipid film and adsorption on PtdCho are concerned. The N-glycosylation of HGL may contribute to the enzyme stability in the stomach, as under acidic conditions the degradation by pepsin of the unglycosylated r-HGL is increased.

The revised Canadian Guidelines for the Economic Evaluation of Pharmaceuticals

The first edition of the Guidelines for Economic Evaluation of Pharmaceuticals: Canada was published in November 1994. At that time, the Canadian Coordinating Office for Health Technology Assessment (CCOHTA) was assigned the task of maintaining and regularly updating the Canadian Guidelines. Since their introduction, a great deal of experience has been gained with the practical application of the guidelines. Their role has also evolved over time, from being a framework for pharmacoeconomic research to the point where a wide variety of decision-makers use economic evaluations based on the principles set out in the guidelines as a means of facilitating their formulary decisions. In addition, methodologies in certain areas (and the body of related research literature in general) have developed considerably over time. Given these changes in the science and the experience gained, CCOHTA convened a multi-disciplinary committee to address the need for revisions to the guidelines. The underlying principles of the review process were to keep the guidance nature of the document, to focus on the needs of 'doers' (so as to meet the information needs of 'users') and to provide information and advice in areas of controversy, with sound direction in areas of general agreement. The purpose of this review is three-fold: (i) to outline the process which lead to the revision of the Canadian Guidelines; (ii) to describe the major changes made to the second edition of this document; and (iii) to consider the 'next steps' as they relate to the impact of such guidelines and the measurement of outcomes related to economic assessments of pharmaceuticals in general.

The cysteine residues of recombinant human gastric lipase

Recombinant human gastric lipase (rHGL) and three of its cysteine mutants (cysteine 227, 236, and 244 substitued for threonine or serine) were expressed in the baculovirus/insect cell system and purified to homogeneity by performing a two-step procedure. Substituting Ser for Cys 227 and Cys 236 resulted in mutant lipases with a significantly lower level of activity (30% and 22%, respectively) on a short chain triglyceride (tribuyrin) substrate, while the mutation at position 244 only slightly reduced the activity. Using 4, 4'-dithiopyridine (4-PDS) as a sulfhydryl reagent on the above mutants, it was possible to clearly identify the single sulfhydryl residue at position 244 and consequently, the disulfide bridge at position 227-236. No potential disulfide bridges were formed during the protein folding between cysteines 227-244 or between cysteines 236-244, as thought to occur in the case of rabbit gastric lipase (RGL). The present results are consistent with the recently determined 3D-structure of rHGL.

Rat Chromosome 2: assignment of the genes encoding cyclin B1, interleukin 6 signal transducer, and proprotein convertase 1 to the Mcs1-containing region and identification of new microsatellite markers

The rat Chromosome (Chr) 2 harbors several genes controlling tumor growth or development, blood pressure, and non-insulin-dependent diabetes mellitus. We report that the region (2q1) containing the mammary susceptibility cancer gene Mcs1 also harbors the genes encoding cyclin B1, interleukin 6 signal transducer (gp130), and proprotein convertase 1. We also generated 13 new anonymous microsatellite markers from Chr 2-sorted DNA. These markers, as well as a microsatellite marker in the cyclin B1 gene, were genetically mapped in combination with known markers. A cyclin B1-related gene was also cytogenetically assigned to rat Chr 11q22-q23.

[Synthesis of multifunctional surfactants for elaboration of micellar model systems of enzymes]

In order to provide a closer analogy between micelles and enzymes, the design of functionalized micellar systems have been undertaken. This paper presents the synthesis of surfactant cationic molecules which contains either a free or a protected aldehyde group. An ammonium quaternary surfactant with two functional groups, aldehyde dimethyl acetal and imidazole, has also been synthesized.

Purification and interfacial behavior of recombinant human gastric lipase produced from insect cells in a bioreactor

Recombinant human gastric lipase (rHGL) (EC 3.1.1.3) was produced on a large scale (5-13 mg/liter) from recombinant baculovirus-infected insect cells using a bioreactor apparatus. Here an improved procedure is described for purifying rHGL involving the use of cation exchange chromatography followed by immunoaffinity column methods, which gives a total yield of 62% and a purification factor of 464, using 10% isopropanol in all the purification buffers. The presence of isopropanol was necessary to preserve the stability of the enzyme during the chromatographic separation steps. The specific activity of rHGL on tributyroylglycerol (700 U/mg) was lower than that of native HGL (nHGL) (1080 U/mg). The rHGL interfacial adsorption kinetics were studied by recording the changes in the surface pressure with time in the presence or absence of an egg phosphatidycholine monomolecular film spread at the air/water interface at various initial surface pressures. The surface behavior of rHGL was similar to that of nHGL. It can be concluded that the lipid binding affinity of rHGL is identical to that of the native lipase and, consequently, that the presence of detergents and lipids in the insect cell culture media did not affect the interfacial behavior of the purified rHGL. It will be therefore possible to specifically study the binding step of HGL mutants to a lipid monolayer.

The rat microphthalmia-associated transcription factor gene (Mitf) maps at 4q34-q41 and is mutated in the mib rats

The rat gene encoding the microphthalmia-associated transcription factor (Mitf) was assigned to rat Chromosome (Chr) 4q34-q41, as well as the Gata2 and Mem1 genes. Rat Chr 4 is homologous to mouse Chr 6 and human Chr 3, which carry the Mitf (MITF) gene in these species (MMU 6, 40.0 cM, and HSA 3p14.1-p12.3). mib/mib rats, which are characterized by depigmentation, microphtalmy, osteopetrosis, and neurological disorders were shown to bear a deletion covering several kilobases of genomic DNA in the Mitf gene and to lack Mitf mRNA. The Mitf mutation in the mib/mib rats is thus very likely to be a Mitf null mutation, causing a phenotype similar to the one observed in the miVGA-9 mice, but including osteopetrosis as an additional feature.

Kzf1 - a novel KRAB zinc finger protein encoding gene expressed during rat spermatogenesis

Two novel KRAB (Krüppel associated box) type zinc finger protein encoding cDNAs, named Kzf1 and Kzf2 (Kzf for KRAB zinc finger), were identified by screening of a rat embryonic brain cDNA library with a human ZNF91 KRAB probe. Kzf1 and Kzf2 encode proteins with an amino-terminal KRAB domain and a carboxy-terminal zinc finger cluster containing 9 and 13 zinc finger units, respectively. While Kzf2 appears to be ubiquitously expressed, Kzf1 is preferentially expressed in the testis. Within the testis, Kzf1 mRNA is restricted to germ cells. The Kzf1 protein exhibits DNA binding activity and its KRAB domain can function as a repressor module in transcription. Using somatic cell hybrid analysis, the Kzf1 gene was mapped to chromosome 6.

Newly found 2-N-acetyl-2,6-dideoxy-beta-glucopyranose containing methyl glucose polysaccharides in M.bovis BCG: revised structure of the mycobacterial methyl glucose lipopolysaccharides

The specific mycobacterial methyl polysaccharides 3- O -methyl mannose polysaccharide (MMP) and the 6- O -methyl glucose lipopolysaccharides (MGLPs) were shown to modulate the fatty acid biosynthesis by the mycobacterial fatty acid synthetase I (FAS I). This activity is attributed to their fatty acid complexing properties allowing the release of the neo synthesized fatty acyl chain from the enzyme and probably their transport in the cell. To elucidate, at a molecular level, the mechanism of this unusual kind of polysaccharide-lipid biological interaction, we first analyzed, by mass spectrometry and proton nuclear magnetic resonance (1H NMR) spectroscopy, the structure of the polysaccharidic backbone (MGPs) of the MGLPs from Mycobacterium bovis BCG. This work reveals that this strain produces a new kind of MGP containing an unusual monosaccharide never described in the mycobacterial genus: a 2- N -acetyl-2,6-dideoxy-beta-glucopyranosyl. In addition,1H NMR data afforded evidence for the revision of three glycosidic linkages described previously. These modifications affect mainly the reducing end tetrasaccharide and have great consequences on the previously proposed molecular model of the MGP.

Direct evidence of methylglucose lipopolysaccharides/palmitoyl-CoA noncovalent complexes by capillary zone electrophoresis-electrospray/mass spectrometry

Mycobacterial methylglucose lipopolysaccharides (MGLPs) play an important regulatory role in the biosynthesis of long-chain fatty acids by forming complexes with neosynthesized acyl-CoA fatty acid derivatives. The MGLPs from Mycobacterium smegmatis were purified by high-performance anion-exchange chromatography and characterized by LSIMS and CE/ESI-MS. We investigated their interaction with palmitoyl-CoA using capillary zone electrophoresis with both direct and indirect UV detection. In the latter mode, the signal of the UV-transparent MGLPs decreased upon addition of increasing amounts of palmitoyl-CoA; while using direct UV detection, the addition of palmitoyl-CoA to the MGLPs revealed characteristic profiles. The major peak was assigned to the noncovalent MGLP/palmitoyl-CoA complex on the basis of its electrophoretic mobility. The abundance of the complex was found to increase until the MGLP/palmitoyl-CoA molar ratio reached a 1/1 stoichiometry. The existence of and the stoichiometry of this complex were assessed by CE/ESI mass spectrum analysis, showing pseudomolecular ions of the MGLP/palmitoyl-CoA complex. These results confirm that CE/ESI-MS is a powerful tool to characterize noncovalent molecular association.

Characterization and sugar-binding properties of arcelin-1, an insecticidal lectin-like protein isolated from kidney bean (Phaseolus vulgaris L. cv. RAZ-2) seeds

Arcelin-1 is a lectin-like protein found in the seeds of wild varieties of the kidney bean (Phaseolus vulgaris). This protein displays insecticidal properties, but the mechanism of action is as yet unknown. In the present study we investigated the biochemical and biophysical properties of arcelin-1 from Phaseolus vulgaris cv. RAZ-2. Native arcelin-1 is a dimeric glycoprotein of 60 kDa, built from the non-covalent association of two identical monomers. This dimer resists dissociation by chaotropic agents and is highly resistant to proteolytic enzymes. Each subunit contains 10% (w/w) neutral sugars which belong to the high-mannose and complex-type glycans attached to three glycosylation sites. No interaction of the protein with simple sugars could be detected, but arcelin-1 displays an intrinsic specificity in binding complex glycans. Arcelin-1 therefore differs from the closely related phytohaemagglutinin lectins and alpha-amylase inhibitor in several respects: oligomerization states, sugar-binding affinities and the type and number of glycan chains. These features may be related to the toxicity of arcelin-1.