G130V, a common FRDA point mutation, appears to have arisen from a common founder

Friedreich ataxia (FRDA) is the most common inherited ataxia. About 98% of mutant alleles have an expansion of a GAA trinucleotide repeat in intron 1 of the affected gene, FRDA. The other 2% are point mutations. Of the 17 point mutations so far described, three appear to be more common. One of these is the G130V mutation in exon 4 of FRDA. G130V, when present with an expanded GAA repeat on the other allele, is associated with an atypical FRDA phenotype. Haplotype analysis was undertaken on the four families who have been described with this mutation. The results suggest a common founder for this mutation. Although marked differences in extragenic marker haplotypes were seen in one family, similar intragenic haplotyping suggests the same mutation founder for this family with the differences explicable by two recombination events.

Peripheral development: position paper for the Directorate of the South African National Parks

The principle of peripheral development and its relevance to South African National Parks has been a recurring subject for debate. One viewpoint is that the principle should be applied as a general rule, and that in future all major developments of infrastructure should be on the periphery rather than the interior of national parks. The Scientific Services units of South African National Parks were asked to provide their views, and this note is the result. The consensus was that, although there is much to be said in general for the principle, there are circumstances in which developments on the periphery of a park could be deleterious. Hence, the principle does not merit the status of a rule.

The identification of markers segregating with resistance to Schistosoma mansoni infection in the snail Biomphalaria glabrata

Both snail and parasite genes determine the susceptibility of the snail Biomphalaria glabrata to infection with the trematode Schistosoma mansoni. To identify molecular markers associated with resistance to the parasite in the snail host, we performed genetic crosses between parasite-resistant and -susceptible isogenic snails. Because resistance to infection in adult snails is controlled by a single locus, DNA samples from individual F2 and F1 backcross progeny, segregating for either the resistant or susceptible phenotypes, were pooled (bulked segregant). Genotypes for both parents were determined with 205 arbitrary decamer primers by random amplified polymorphic DNA-PCR. Of the 205 primers, 144 were informative, and the relative allele frequencies between the pools for these primers were determined. Two primers, OPM-04 and OPZ-11, produced fragments in the resistant parent of one cross that were inherited in a dominant fashion in the resistant F2 and backcross-bulked segregant progeny. Subsequent typing of DNA samples of individual progeny snails showed that the 1.2-kb marker amplified by primer OPM-04 and the 1.0-kb marker produced by primer OPZ-11 segregated in the same dominant fashion with the resistant phenotype. Sequence analysis of the 1.2-kb marker showed that it corresponds to a repetitive sequence in the snail genome with no homology to existing DNA sequences in the public databases. Analysis of the 1. 0-kb marker showed that it also corresponds to a repetitive sequence in the B. glabrata genome that contains an imperfect ORF, with homology to retrovirus-related group-specific antigens (gag) polyprotein.

Circulating markers of oxidative stress are raised in normal pregnancy and pre-eclampsia

OBJECTIVE

To determine whether circulating markers of oxidative stress are elevated in pre-eclampsia when appropriate precautions are taken to prevent in vitro oxidation

DESIGN

A prospective study.

SETTING

Nuffield Department of Obstetrics and Gynaecology, Oxford and The William Harvey Institute, London.

SAMPLE

Three groups of women: those with pre-eclampsia (n = 19), control pregnant women (n = 19) matched for gestation, age and parity and a group of non pregnant individuals of reproductive age (n = 7).

METHODS

Citrated plasma was stored at -80 degrees C with 20 micromol beta hydroxytoluene to prevent auto-oxidation. Plasma samples were assayed for levels of 8 epi-prostaglandin F2alpha, lipid hydroperoxides, malondialdehyde and also the lipid soluble antioxidant vitamin E.

RESULTS

There were no differences in 8 epi-prostaglandin F2alpha, lipid peroxide or malondialdehyde levels between the groups of women with pre-eclampsia and those acting as pregnant controls. However, lipid hydroperoxides and malondialdehyde were significantly raised in both pre-eclampsia and normal pregnancy, compared with nonpregnant women. Vitamin E levels were similar in women with pre-eclampsia and those with a normal pregnancy, but in both groups levels were significantly higher than in nonpregnant women.

CONCLUSION

Circulating markers of oxidative stress are raised in normal pregnancy and pre-eclampsia.

A study of the effectiveness of an interactive computer classroom

This study examined the use of an interactive computer classroom (ICC) compared with a traditional lecture/discussion format (LD) for a nursing management course taught from fall semester 1994 through fall semester 1996. The ICC was structured around a group systems support software, a tool previously used in business settings for group decision-making activities. Structured learning activities allowed all students to participate simultaneously and anonymously. Data were collected during the second and final semesters of the study. The outcomes included academic performance, measured by course exams; class participation, measured by direct observation; and attendance records. The control group was a concurrent management course taught with the same objectives and evaluated by identical examinations. The examination scores and the frequency of class participation of the ICC group were significantly higher than those measures of the LD group. There was no significant difference in class attendance. Evaluation forms with open-ended questions were completed by the ICC students and revealed that the students believed that the process enhanced application and understanding. The negative aspects of the ICC experience were the need for increased preparation time for faculty and the students' lack of tolerance when technical difficulties caused delays.

The correlation of clinical phenotype in Friedreich ataxia with the site of point mutations in the FRDA gene

Most cases of Friedreich ataxia (FRDA) are due to expansions of a GAA trinucleotide repeat sequence in the FRDA gene coding for frataxin, a protein of poorly understood function which may regulate mitochondrial iron transport. However, between 1% and 5% of mutations are single base changes in the sequence of the FRDA gene, causing missense, nonsense, or splicing mutations. We describe three new mutations, IVS4nt2 (T to G), R165C, and L182F, which occur in patients in association with GAA expansions. These cases, and a further five reported cases of point mutations causing FRDA, demonstrate that splicing, nonsense, or initiation codon mutations (which cause a complete absence of functional frataxin) are associated with a severe phenotype. Missense mutations, even in highly evolutionally conserved amino acids, may cause a mild or severe phenotype.

Isolation and characterization of the zSSIIa and zSSIIb starch synthase cDNA clones from maize endosperm

Two starch synthase clones, zSSIIa and zSSIIb, were isolated from a cDNA library constructed from W64A maize endosperm. zSSIIa and zSSIIb are 3124 and 2480 bp in length, and contain open reading frames of 732 and 698 amino acid residues, respectively. The deduced amino acid sequences of the two clones share 58.1% sequence identity. Amino acid sequence identity between the zSSIIa and zSSIIb clones and the starch synthase II clones of potato and pea ranges between 45 to 51%. The predicted amino acid sequence from each SSII cDNA contains the KXGGL consensus motif at the putative ADP-Glc binding site. Both clones also contain putative transit peptides followed by the VRAA(E)A motif, the consensus cleavage site located at the C-terminus of chloroplast transit peptides. The identity of the zSSIIa and zSSIIb clones as starch synthases was confirmed by expression of enzyme activity in Escherichia coli. Genomic DNA blot analysis revealed two copies of zSSIIa and a single copy of zSSIIb. zSSIIa was expressed predominantly in the endosperm, while transcripts for zSSIIb were detected mainly in the leaf at low abundance. These findings establish that the zSSIIa and zSSIIb genes are characteristically distinct from genes encoding granule-bound starch synthase I (Waxy protein) and starch synthase I.

Shedding of syncytiotrophoblast microvilli into the maternal circulation in pre-eclamptic pregnancies

OBJECTIVE

To investigate whether syncytiotrophoblast microvilli (STBM) are shed into the maternal circulation in increased amounts in pre-eclamptic pregnancies as a possible cause of maternal vascular endothelial dysfunction.

DESIGN

A time-resolved fluoroimmunoassay was developed to measure STBM levels in peripheral and uterine venous plasma from normal pregnant and pre-eclamptic women. Three colour flow cytometry was used to assess the microparticulate nature of the STBM in pregnancy plasma. The effects of these plasmas on endothelial cell proliferation was compared and a correlation with the levels of STBM detected was sought.

SETTING

A laboratory investigation using clinical samples obtained from an obstetric practice in a teaching hospital.

SAMPLES

Peripheral venous plasma from 20 women with established pre-eclampsia, 20 normal pregnant women matched for age, gestation and parity, and 10 nonpregnant women of reproductive age. Paired uterine and peripheral venous plasma taken at caesarean section from 10 women with pre-eclampsia and 10 unmatched normal pregnant women.

RESULTS

STBM were detected in the plasma of pregnant women by both flow cytometry and time-resolved fluoroimmunoassay. Significantly higher levels of STBM were found in women with established pre-eclampsia (P=0.01). STBM concentrations were higher in uterine venous plasma than in concurrently sampled peripheral venous plasma, confirming their placental origin. A significant correlation was found between the amount of STBM in the plasma and endothelial cell inhibitory activity.

CONCLUSIONS

STBM are shed into the maternal circulation (microvillous deportation) and are present in significantly increased amounts in pre-eclamptic women. They may contribute to the endothelial dysfunction underlying the maternal syndrome of pre-eclampsia.

Characterization of the myoglobin and its coding gene of the mollusc Biomphalaria glabrata

A cDNA clone isolated from a Biomphalaria glabrata (Mollusca, Gastropoda) neural cDNA library was identified as encoding a myoglobin-like protein of 148 amino acids with a single domain and a calculated mass of 16,049.29. Alignment with globin sequences with known tertiary structure confirms its overall globin nature. The expressed myoglobin was identified in the radular muscle and isolated. Oxygen equilibrium measurements on the protein reveal a high oxygen affinity. Val-B10 and Gln-E7, important residues for the determination of the oxygen affinity, are strikingly different from the standard molluscan pattern (Conti, E., Moser, C., Rizzi, M., Mattevi, A., Lionetti, C., Coda, A., Ascenzi, P., Brunori, M., Bolognesi, M. (1993) J. Mol. Biol. 233, 498-508). The single gene encoding the globin chain is interrupted by three introns at positions A3.2, B12.2, and G7.0. Comparison with other nonvertebrate globin genes reveals on the one hand conservation (B12.2 and G7.0) and on the other hand variability of the insertion positions (A3.2). The Biomphalaria myoglobin sequence was used together with all other molluscan globin sequences available to assess the origin and phylogeny of the phylum. Our results confirm the doubts raised about monophyletic origin of the Mollusca, which was first observed using SSU rRNA as a molecular marker.

Mutations of the flavin-containing monooxygenase gene (FMO3) cause trimethylaminuria, a defect in detoxication

Individuals with the recessive condition trimethylaminuria exhibit variation in metabolic detoxication of xenobiotics by hepatic flavin-containing monooxygenases. We show here that mutations in the human flavin-containing monooxygenase isoform 3 gene ( FMO3 ) impair N -oxygenation of xenobiotics and are responsible for the trimethylaminuria phenotype. Three disease-causing mutations in nine Australian-born probands have been identified which share a particular polymorphic haplotype. Nonsense and missense mutations are associated with a severe phenotype and are also implicated in impaired metabolism of other nitrogen- and sulfur-containing substrates including biogenic amines, both clinically and when mutated proteins expressed from cDNA are studied in vitro . These findings illustrate the critical role played by human FMO3 in the metabolism of xenobiotic substrates and endogenous amines.

(Stearyl, Norleucine17)VIP hybrid antagonizes VIP receptors on non-small cell lung cancer cells

The effects of VIP receptor antagonists were investigated using non-small cell lung cancer (NSCLC) cells. By Northern blot and RT-PCR, VIP1 receptors were detected on NSCLC cell line NCI-H1299. VIPhybrid,(N-Stearyl-Norleucine17) VIPhybrid ((SN) VIPhybrid) and PTC4495 inhibited 125I-VIP binding to NCI-H1299 cells with IC50 values of 500, 30 and 5000 nM respectively. (SN) VIPhybrid (1 microM) had no effect on basal cAMP but strongly inhibited the increase in cAMP caused by 10 nM VIP. The order of peptide potency to inhibit cAMP was (SN) VIPhybrid > VIPhybrid > PTC4495. (SN) VIPhybrid was more potent than VIPhybrid at inhibiting NCI-H1299 colony formation. Also, (SN) VIPhybrid was more potent than VIPhybrid at inhibiting NCI-H1299 xenograft formation in nude mice. These data suggest that (SN) VIPhybrid antagonizes VIP1 receptors on NSCLC cells.

Prevalence of dental caries in Omani 6-year-old children

OBJECTIVE

To determine the prevalence of dental caries in Omani 6-year-old children.

DESIGN

Clinical caries cross-sectional survey, conducted by 16 trained and calibrated dentists.

SETTING

Omani primary schools in December 1994.

SUBJECTS

3,114 subjects, randomly selected to achieve an overall 6.6 per cent sample of Omani 6-year-old children.

OUTCOME MEASURES

Caries diagnosis based solely on clinical examination in accordance with criteria of British Association for the Study of Community Dentistry.

RESULTS

Only 484 subjects (15.5 per cent) were caries-free; regional variations ranging from 4.4 per cent to 31 per cent. Overall, the national dmft averaged 4.61; the majority of caries experienced being in the form of untreated decay, with occlusal surfaces of first primary molars being the most commonly involved site.

CONCLUSIONS

Compared with results from a survey of Omani 12-year-old children in 1993, a much smaller proportion of this 6-year-old sample were caries free, emphasising the need for continuance of existing, and the development of further, preventive programmes.

A laboratory-based approach to biological control of snails

Development of Schistosoma mansoni in the intermediate host Biomphalaria glabrata is influenced by a number of parasite and snail genes. Understanding the genetics involved in this complex host/ parasite relationship may lead to an often discussed approach of introducing resistant B. glabrata into the field as a means of biological control for the parasite. For the snail, juvenile susceptibility to the parasite is controlled by at least four genes, whereas one gene seems to be responsible for adult nonsusceptibility. Obtaining DNA from F2 progeny snails from crosses between parasite-resistant and -susceptible snails, we have searched for molecular markers that show linkage to either the resistant or susceptible phenotype. Both restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) approaches have been used. To date, using a variety of snail and heterologous species probes, no RFLP marker has been found that segregates with either the resistant or susceptible phenotype in F2 progeny snails. More promising results however have been found with the RAPD approach, where a 1.3 kb marker appears in nearly all resistant progeny, and a 1.1 kb marker appears in all susceptible progeny.

Human flavin-containing monooxygenase form 3: cDNA expression of the enzymes containing amino acid substitutions observed in individuals with trimethylaminuria

Trimethylaminuria is an autosomal recessive human disorder affecting a small part of the population as an inherited polymorphism. Individuals diagnosed with trimethylaminuria excrete relatively large amounts of trimethylamine in their urine, sweat, and breath, and this results in a fishy odor characteristic of trimethylamine. Activity of the human flavin-containing monooxygenase (FMO) has been proposed to be deficient in trimethylaminuria patients causing a decrease in the metabolism of trimethylamine that results in a fishy body odor. Cohorts of Australian, American, and British individuals suffering from trimethylaminuria have been identified. The human FMO3 cDNA was amplified from lymphocytes of affected patients. We report preliminary evidence of substitutions detected by screening of the cDNA and genomic DNA. The variant human FMO3 cDNA was constructed from wild type human FMO3 cDNA by site-directed mutagenesis as maltose-binding protein fusions. Five distinct human FMO3 mutants were expressed as fusion proteins in Escherichia coli and compared with wild type human FMO3 maltose-binding proteins (FMO3-MBP) for the N-oxygenation of 10-[(N,N-dimethylamino)pentyl]-2-(trifluoromethyl)phenothiazine, tyramine, and trimethylamine. Human Lys158 FMO3-MBP and, to a greater extent, human Glu158 FMO3-MBP efficiently N-oxygenated the three amine substrates. Human Lys158 Ile66 FMO3-MBP, Glu158 Ile66 FMO3-MBP, Lys158 Leu153 FMO3-MBP, and Glu158 Leu153 FMO3-MBP were all constructed as mutants identified as possible FMO3 variants responsible for trimethylaminuria and were found to be inactive as N-oxygenases. The results suggest that mutations at codons 66 and 153 of FMO3 can cause trimethylaminuria in humans. We observed a common polymorphism of Lys to Glu at codon 158 of FMO3 that segregated with almost equal allele frequencies in a number of control Australian and North American samples studied. The Lys158 to Glu158 human FMO3 polymorphism does not decrease trimethylamine N-oxygenation for the cDNA-expressed enzyme and thus does not appear to be causative of trimethyaminuria. The data show that the functional activity of human FMO3 can be significantly altered by amino acid changes that have been observed in individuals with clinically diagnosed trimethylaminuria.

Schistosoma mansoni: use of a subtractive cloning strategy to search for RFLPs in parasite-resistant Biomphalaria glabrata

A subtractive cloning strategy has been applied for the identification of two cDNA clones whose corresponding transcripts were elevated in Schistosoma mansoni-resistant (BS-90) compared to susceptible (M-line) snails. Clone pBS11 encoded a 1.9-kb transcript that was more elevated compared to a 500-bp transcript encoded by clone pBS12. Consequently, more attention was focused on the molecular characterization of clone pBS11. Results showed that the transcript encoded by this clone was expressed in the albumen gland and was developmentally regulated. Sequence analysis of pBS11 demonstrated the presence of an open reading frame that corresponded to a novel Biomphalaria glabrata albumen gland gene product. Comparative Southern analysis of the resistant and susceptible snail lines using pBS11 as probe indicated the presence of a BamHI and EcoRI RFLP between the two strains.

The oral health status of Omani 12-year-olds--a national survey

This study reports the first ever national oral health survey of Omani 12-year-olds. Conducted in October 1993, of the 3,435 children examined, 1,438 (41.9%) were caries-free, although regional variations ranged from 24.8% to 61.9%. Overall, the national DMFT averaged 1.53, the majority of caries experienced being in the form of untreated decay, with occlusal surfaces of first permanent molars being the most commonly involved site. Oral hygiene was poor, only 11% of those examined being scored as plaque-free.

Children's understanding of the distinction between real and apparent emotions: a training study

The effects of two types of training on 4-year-old children's understanding of the distinction between experienced positive affect and neutral or negative display were examined. One type of training provided first-hand experience of possible discrepancies between facial expression and actual affect. The other training focused on the sorts of motives that might prompt the concealment of positive affect. Compared with a control group, both experimental groups showed modest gains.

Physical association of starch biosynthetic enzymes with starch granules of maize endosperm. Granule-associated forms of starch synthase I and starch branching enzyme II

Antibodies were used to probe the degree of association of starch biosynthetic enzymes with starch granules isolated from maize (Zea mays) endosperm. Graded washings of the starch granule, followed by release of polypeptides by gelatinization in 2% sodium dodecyl sulfate, enables distinction between strongly and loosely adherent proteins. Mild aqueous washing of granules resulted in near-complete solubilization of ADP-glucose pyrophosphorylase, indicating that little, if any, ADP-glucose pyrophosphorylase is granule associated. In contrast, all of the waxy protein plus significant levels of starch synthase I and starch branching enzyme II (BEII) remained granule associated. Stringent washings using protease and detergent demonstrated that the waxy protein, more than 85% total endosperm starch synthase I protein, and more than 45% of BEII protein were strongly associated with starch granules. Rates of polypeptide accumulation within starch granules remained constant during endosperm development. Soluble and granule-derived forms of BEII yielded identical peptide maps and overlapping tryptic fragments closely aligned with deduced amino acid sequences from BEII cDNA clones. These observations provide direct evidence that BEII exits as both soluble and granule-associated entities. We conclude that each of the known starch biosynthetic enzymes in maize endosperm exhibits a differential propensity to associate with, or to become irreversibly entrapped within, the starch granule.

Use of RAPD-PCR to differentiate genetically defined lines of an intermediate host of Schistosoma mansoni, Biomphalaria glabrata

The genetic differentiation among several laboratory-maintained pedigree snail lines of Biomphalaria glabrata (with different susceptibility phenotypes to Schistosoma mansoni infection) was assessed with the random amplified polymorphic DNA method. Out of the 20 primers tested, 2 (OPA-01 and OPA-06) gave reproducible markers with either individual or bulked DNA samples from resistant (BS-90, 10-R2, LAC-line) and susceptible (M-line) snails. Arbitrary primer, OPA-01, amplification of BS-90 DNA identified a 180-bp strain-specific fragment and a 400-bp marker in the susceptible M-line stock. In the 10-R2 and LAC snail lines, OPA-01 specific markers of 200 bp and 550 bp were identified. Amplification with primer OPA-06 identified several major strain-specific markers in the BS-90 (150 bp, 400 bp, 800 bp) and M-line (1,100 bp) snails. The heritability of the RAPD markers was evaluated in progeny snails derived from a cross between the BS-90 and M-line stocks. Results showed that markers were inherited in a dominant or codominant fashion. The 1,100-bp M-line marker was inherited in all susceptible progeny snails analyzed.

The effect of nitrogen dioxide exposure on the release of surfactant isolated from neonatal rabbit type II pneumocytes in culture

Nitrogen dioxide (NO2) is a well-known environmental air toxin, produced from a variety of sources, including cigarette smoke. Because of the growing knowledge of the harmful effects of passive smoking on children, we decided to study the effect of NO2 exposure on the release of surfactant from isolated neonatal type II pulmonary epithelial cells. After isolation from 1 to 4 day old rabbits, type II epithelial cells were allowed to adhere for 18 hours, washed, media changed, and were exposed to either 5% CO2 in room air or NO2, 5 ppm, for 2 hours (all results mean +/- sd; comparisons, paired t-test). There was no difference in cell number or viability prior to exposure. Cells exposed to NO2 had an increase in LDH release [LDH activity in media/(LDH in media+cells) x 100], air 12.6 +/- 2.2%, NO2 21.7 +/- 3.7%, (p < 0.05). NO2-exposed cells also had an increase in total phospholipid (microgram/cell culture dish) in media compared to air exposed, air 170.13 +/- 7.54, NO2 195.15 +/- 11.2, (p < 0.05). 3H-choline incorporation as a precursor to disaturated phosphatidylcholine (DSPC) was also conducted during exposure to either air or NO2. Incorporation of 3H-choline into surfactant lipid was increased in media from cells after NO2 exposure compared to air, 58.23 +/- 15.16 air, 76.81 +/- 19.86 NO2 (cpm/microgram protein; p < 0.05). These results show that 2 hours of 5 ppm NO2 exposure is associated with an increase in release of surfactant from neonatal type II cells in culture.