Fourier transform infrared evidence for connectivity between CuB and glutamic acid 286 in cytochrome bo3 from Escherichia coli

Photodissociation of fully reduced, carbonmonoxy cytochrome bo3 causes ultrafast transfer of carbon monoxide (C triple bond O) from heme iron to CuB in the binuclear site. At low temperatures, the C triple bond O remains bound to CuB for extended times. Here, we show that the binding of C triple bond O to CuB perturbs the IR stretch of an un-ionized carboxylic acid residue, which is identified as Glu286 by mutation to Asp or to Cys. Before photodissociation, the carbonyl (C=O)-stretching frequency of this carboxylic acid residue is 1726 cm-1 for Glu286 and 1759 cm-1 for Glu286Asp. These frequencies are definitive evidence for un-ionized R-COOH and suggest that the carboxylic acids are hydrogen-bonded, though more extensively in Glu286. In Glu286Cys, this IR feature is lost altogether. We ascribe the frequency shifts in the C=O IR absorptions to the effects of binding photodissociated C triple bond O to CuB, which are relay ed to the 286 locus. Conversely, the 2065 cm-1 C triple bond O stretch of CuB-CO is markedly affected by both mutations. These effects are ascribed to changes in the Lewis acidity of CuB, or to displacement of a CuB histidine ligand by C triple bond O. C triple bond O binding to CuB also induces a downshift of an IR band which can be attributed to an aromatic C-H stretch, possibly of histidine imidazole, at about 3140 cm-1. The results suggest an easily polarizable, through-bond connectivity between one of the histidine CuB ligands and the carboxylic group of Glu286. A chain of bound water molecules may provide such a connection, which is of interest in the context of the proton pump mechanism of the heme-copper oxidases.     

High-frequency developmental abnormalities in p53-deficient mice

BACKGROUND: Several strains of mice carrying null mutations of the tumour suppressor gene p53 have been developed. It has been reported that homozygous mice from all of these strains develop normally to birth, but then succumb rapidly to neoplasia. RESULTS: Here, we report that a significant proportion of female p53-/- mice die during embryogenesis or in the period between birth and weaning, being subject to a spectrum of abnormalities. In a significant proportion (23%) of p53-/- female embryos, the normal process of neural tube closure failed, leading to exencephaly and subsequent anencephaly. Although this phenomenon was predominantly associated with females, we observed one affected male embryo. In addition to a spectrum of neural tube defects, many of these embryos exhibited a range of craniofacial malformations, including ocular abnormalities and defects in upper incisor tooth formation. We observed a significant reduction in the number of p53-/- female progeny of p53+/- x p53+/- matings, and also in an in utero analysis of the p53+/- female progeny of p53-/- x p53+/+ matings. When male mice were exposed to irradiation prior to mating, a significant increase in the rate of abnormality was seen in the progeny, which was specifically associated with p53 deficiency. CONCLUSIONS: We have identified a high rate of developmental abnormalities associated with p53 deficiency. This manifests itself as a spectrum of lesions, predominantly female-associated defects in neural tube closure. These defects may arise either because p53 plays a physiological role at the time of neural tube closure, or because of an abnormally high frequency of mutation within the haploid gametes of p53-null parents.     

Synthesis and glutathione S-transferase structure-affinity relationships of nonpeptide and peptidase-stable glutathione analogues

A series of nonpeptidic glutathione analogues where the peptide bonds were replaced by simple carbon-carbon bonds or isosteric E double bonds were prepared. The optimal length for the two alkyl chains on either side of the mercaptomethyl group was evaluated using structure-affinity relationships. Affinities of the analogues 14a-f, 23, and 25 were evaluated for a recombinant GST enzyme using a new affinity chromatography method previously developed in our laboratory. Analysis of these analogues gives an additional understanding for GST affinity requirements: (a) the carbon skeleton must conserve that of glutathione since analogue 14a showed the best affinity (IC50 = 5.2 microM); (b) the GST G site is not able to accommodate a chain length elongation of one methylene group (no affinity for analogues 14c,f); (c) a one-methylene group chain length reduction is tolerated, much more for the "Glu side" (14d, IC50 = 10.1 microM) than for the "Gly side" (14b, IC50 = 1800 microM); (d) the mercaptomethyl group must remain at position 5 as shown from the null affinity of the 6-mercaptomethyl analogue 14e; (e) the additional peptide isosteric E double bond (25) or hydroxyl derivative (23) in 14e did not help to retrieve affinity. This work reveals useful information for the design of new selective nonpeptidic and peptidase-stable glutathione analogues.     

Roles for laminin in embryogenesis: exencephaly, syndactyly, and placentopathy in mice lacking the laminin alpha5 chain

Laminins are the major noncollagenous glycoproteins of all basal laminae (BLs). They are alpha/beta/gamma heterotrimers assembled from 10 known chains, and they subserve both structural and signaling roles. Previously described mutations in laminin chain genes result in diverse disorders that are manifested postnatally and therefore provide little insight into laminin's roles in embryonic development. Here, we show that the laminin alpha5 chain is required during embryogenesis. The alpha5 chain is present in virtually all BLs of early somite stage embryos and then becomes restricted to specific BLs as development proceeds, including those of the surface ectoderm and placental vasculature. BLs that lose alpha5 retain or acquire other alpha chains. Embryos lacking laminin alpha5 die late in embryogenesis. They exhibit multiple developmental defects, including failure of anterior neural tube closure (exencephaly), failure of digit septation (syndactyly), and dysmorphogenesis of the placental labyrinth. These defects are all attributable to defects in BLs that are alpha5 positive in controls and that appear ultrastructurally abnormal in its absence. Other laminin alpha chains accumulate in these BLs, but this compensation is apparently functionally inadequate. Our results identify new roles for laminins and BLs in diverse developmental processes.     

Sodium valproate augments spontaneous neural tube defects and axial skeletal malformations in TO mouse fetuses [corrected

The TO mouse exhibits a low incidence (3.65%) of spontaneous exencephaly at birth. The objectives of this study were to determine if sodium valproate (VPA) would augment this background frequency of exencephaly and to characterize its gross and histologic bases. Single doses of 200, 400, or 600 mg/kg of VPA were administered on one of gestation days (GD) 7 to 10 and fetuses were collected on GD 18. Significant augmentation of the background incidence of exencephaly was observed in the GD 7 and 8 treatment groups. Absence of the skull vault, hemorrhage, and degeneration of the exposed brain, polyhydramnios, and a female excess characterized the abnormality. Exencephalic embryos were markedly growth retarded. In addition to craniofacial and urogenital anomalies, severe axial skeletal malformations were found to be consistently associated with exencephaly. Morphometric evaluation of the alizarin red-stained skeleton confirmed significant skeletal growth inhibition. Histologic sections of GD 10 embryos revealed early onset of treatment-related growth retardation. Arrest of closure appeared to affect intermittent segments of the neural tube. The closure defect sometimes only involved the surface ectoderm of the dorsal midline. The unclosed neural tube was at times covered by a continuous layer of surface ectoderm. Cell death per se was not pronounced in the neuroepithelium. The mesenchyme was generally sparse and edema was obvious in embryos with partial closure. Growth inhibition of the optic and otic primordia was marked by pronounced cell death in these structures as well as in the otic and trigeminal ganglia and in the pharyngeal arch mesenchyme. Evidence for neural crest cell migration was also recorded. These data indicate that VPA interacts with genetic susceptibility, augments the frequency of exencephaly, and also induces other malformations in the TO mouse. The widespread malformations of the cranifacial structures are suggestive of the preferential effect of VPA on the neural crest or its derivatives.     

Growth hormone treatment of children with neural tube defects: results from 6 months to 6 years

OBJECTIVE: Patients with neural tube defects (myelomeningocele) have severe growth retardation, and treatment with recombinant human growth hormone (rHGH) for 6 months accelerates growth velocity. We examined patients treated for longer periods to determine whether accelerated growth persists, and whether patients demonstrated to be growth hormone deficient have a greater response to rHGH therapy. METHODS: We retrospectively evaluated the growth rate and length standard deviation score (SDS) of 22 patients in response to treatment with 0.3 mg/kg per week of rHGH for 7 to 72 months. Nine of 22 patients were growth hormone deficient (nocturnal and provocative growth hormone responses < 7 ng/ml). Treatment success was defined as an increase of length SDS of > 0.2 SD per year. RESULTS: Fourteen patients (64%) had treatment successes, and eight had treatment failures. Length SDS improved from a pretreatment value of -2.9 (+/- 1.2) to the most recent length SDS of -1.9 (+/- 1.4) (p < 0.001). The growth rate was significantly increased through year 4 of treatment. The annualized growth rate after 6 months of rHGH treatment was significantly different for the success and failure groups (11.0 +/- 2.6 cm/yr vs 5.1 +/- 3 cm/yr, p < 0.001). The annualized 6-month growth rate during treatment was related to the probability of treatment success. CONCLUSION: Treatment with rHGH significantly improves the growth rate and length SDS of children with neural tube defects. The 6-month annualized growth velocity during treatment was predictive of long-term treatment response. The effect on adult stature is unknown.     

Structural dependence of the allosteric interaction of semi-rigid verapamil analogues with dihydropyridine-binding in kitten heart

Structural determinants of the allosteric interaction of semi-rigid verapamil analogues with dihydropyridine binding were investigated in kitten heart using [3H](+)-isradipine as radioligand. Chemical variations were performed in the alkyl chain of verapamil and include introduction of unsaturation (double or triple bonds) or the insertion of cyclohexyl moieties. Introduction of unsaturation generally reduces the allosteric interaction in the case of 'double bond'-and abolishes it in the case of 'triple bond'-derivatives. Also the introduction of cyclohexyl moieties diminishes the potency of allosteric interaction: derivatives with the phenylethylamino side chain in an equatorial position exhibit the allosteric interaction, while it is lacking in derivatives with the basic side chain in axial position. Thus, the reduced conformational flexibility of the new verapamil congeners reduces or abolishes their ability to allosterically interfere with dihydropyridine binding. A molecular interpretation was approached by molecular modelling studies. The strategy was to find low energy conformations common to the active congeners, but not shared by the inactive ones. Structural features discriminating allosterically active and inactive congeners comprise: 1) the position of the nitrogen, 2) the volume occupied by the N-methyl groups, 3) the direction of the N-H bond and 4) the position of the phenyl ring in the basic side chain.     

Study on the "signal" constituents for the evaluation of animal crude drugs. V. The "signal" constituents for the identification of Lumbricus in cold medicines

Cell death was analyzed in neurulating mouse embryos after in vivo doses of 2-methoxyethanol (2-ME) that produce anterior neural tube defects. Characterization of 2-ME-induced cell death was performed by evaluating: (1) vital fluorochrome staining in whole embryos applying confocal laser scanning microscopy; (2) characteristics of cell debris in conventional histological sections revealed by light microscopy; and (3) Apoptag in situ immunohistochemical staining for apoptosis using light microscopy. Methods for quantification of cell death identified by these three techniques were explored using computerized image analysis. Physiological cell death in control embryos primarily occurred in the neural crest region during neural fold elevation. Embryos exposed to 2-ME had expanded areas of cell death in the neural crest and also new areas of cell death in medial regions of the anterior neural tube. Both physiological and 2-ME-induced embryonic cell death had morphological, immunohistochemical, and fluorochrome staining characteristics of apoptosis. When fluorescence data from confocal microscopic analysis of vital fluorochrome-stained embryos were analyzed, a dose-dependent increase was found in embryos exposed to 2-ME. Similar results were obtained when cell death was analyzed in either conventional histological sections or sections prepared for immunohistochemical detection of apoptosis. The cell death data obtained in this study correlate with previously observed near-term malformation rates, suggesting that a quantitative relationship exists between 2-ME-induced embryonic cell death and neural tube defects.     

Considering Mycobacterium haemophilum in the differential diagnosis for lytic bone lesions in AIDS patients who present with ulcerating skin lesions

Incidence of neural tube defects in Poland in the 90's was 2.68 in 1000 births. The value of incidence has not been changed within last twenty years. Mortality caused by neural tube defects in Poland is much higher than in many other European countries and the United States. High rates of incidence of neural tube defects in Poland is probably caused by low utilisation of methods of secondary prevention in a group of low-risk pregnant women. Since methods of primary prevention of neural-tube defects are available; primary prevention with folic acid, should be immediately implemented in Poland.     

An assessment of the developmental toxicity of inorganic arsenic

A critical analysis of the literature base regarding the reproductive and developmental toxicity of arsenic compounds, with emphasis on inorganic arsenicals, was conducted. The analysis was stimulated by the great number of papers that have purported to have shown an association between exposure of pregnant laboratory animals to arsenic compounds and the occurrence of offspring with cranial neural tube defects, particularly exencephaly. For the most part, the literature reports of arsenic developmental toxicity in experimental animals are inadequate for human risk assessment purposes. Despite the shortcomings of the experimental database, several conclusions are readily apparent when the animal studies are viewed collectively. First, cranial neural tube defects are induced in rodents only when arsenic exposure has occurred early in gestation (on Days 7 [hamster, mouse], 8 [mouse], or 9 [rat]). Second, arsenic exposures that cause cranial neural tube defects are single doses that are so high as to be lethal (or nearly so) to the pregnant animal. Third, the effective routes of exposure are by injection directly into the venous system or the peritoneal cavity; even massive oral exposures do not cause increases in the incidence of total gross malformations. Fourth, repetition of similar study designs employing exaggerated parenteral doses is the source of the large number of papers reporting neural tube defects associated with prenatal arsenic exposure. Fifth, in five repeated dose studies carried out following EPA Guidelines for assessing developmental toxicity, arsenic was not teratogenic in rats (AsIII, 101 micromol/kg/d, oral gavage; 101 micromol/m3, inhalation), mice (AsV, 338 micromol/kg/d, oral gavage; est. 402 micromol/kg/d, diet), or rabbits (AsV, 21 micromol/kg/d, oral gavage). Data regarding arsenic exposure and adverse outcomes of pregnancy in humans are limited to several ecologic epidemiology studies of drinking water, airborne dusts, and smelter environs. These studies failed to (1) obtain accurate measurements of maternal exposure during the critical period of organogenesis and (2) control for recognized confounders. The lone study that examined maternal arsenic exposure during pregnancy and the presence of neural tube defects in progeny failed to confirm a relationship between the two. It is concluded that under environmentally relevant exposure scenarios (e.g., 100 ppm in soil), inorganic arsenic is unlikely to pose a risk to pregnant women and their offspring.     

Blood folic acid and vitamin B12 in relation to neural tube defects

OBJECTIVE: To determine the relation between blood folic acid and serum vitamin B12 in neural tube defect pregnancies using data from the MRC Vitamin Study and a literature review of all studies. DESIGN: Stored blood samples collected as part of a randomised trial of vitamin supplementation in the prevention of neural tube defects were retrieved from affected pregnancies (cases) and unaffected pregnancies (controls). Four controls were matched with each case by centre, maternal age and duration of storage of the blood sample. The samples had been collected from women at entry to the trial, immediately before the women became pregnant, and at around 12 weeks of pregnancy. Our results were combined with those already published from other studies to obtain an overall assessment of blood folic acid and vitamin B12 in relation to neural tube defects. SETTING: Blood samples were collected as part of the MRC Vitamin Study. The collaborating centres were in the United Kingdom, Hungary, Israel, Australia, Canada and Russia. PARTICIPANTS: Twenty-seven women with neural tube defect pregnancies and 108 matched controls with unaffected pregnancies. RESULTS: Serum and red cell folic acid and serum vitamin B12 levels were lower in the cases than in controls at each of the three occasions when blood samples were collected, but no comparison was significant (P > 0.05). A systematic review of all studies from the literature showed that on average, during the 1st trimester of pregnancy, serum folic acid was 0.6 ng/ml lower in neural tube defect pregnancies (P < 0.01), red cell folic acid was 77 ng/ml lower (P < 0.001) and serum vitamin B12 was 38 ng/l lower (P < 0.001). A logistic regression showed no association between serum B12 and neural tube defects after allowing for serum folic acid. CONCLUSION: our results are consistent with other evidence that folic acid and vitamin B12 levels are lower in women with neural tube defect pregnancies and consistent with evidence from randomised trials which showed that folic acid is protective.     

Induction of sister-chromatid exchanges by styrene analogues in cultured human lymphocytes

Styrene and 11 styrene analogues were tested for their ability to induce sister-chromatid exchanges (SCEs) by a 48-h treatment in human whole-blood lymphocyte cultures (72 h). Styrene, its methyl-substituted derivatives (substituted at 2-, 3-, 4-, 3,5- or beta-position) and two styrene oxides (3,5-dimethylstyrene-7,8-oxide and 4-nitrostyrene-7,8-oxide) induced a distinct dose-dependent increase in SCEs. Also, 4-methylstyrene-7,8-oxide and alpha-methylstyrene showed a positive effect, but were not able to double the mean number of SCEs/cell at the concentration ranges available. Ethylbenzene had a marginal effect on SCEs at the highest dose tested. 2-Phenylethanol did not increase SCEs. The results indicate that styrene and methylstyrenes are converted into reactive metabolites in the whole-blood lymphocyte cultures. The negative or weak effects of styrene analogues without a double bond in the side-chain (ethylbenzene and 2-phenylethanol) suggest that the reactive metabolites are derived from the conversion of the vinyl group and are styrene-7,8-oxides.     

Ribosomal structure: RNA-protein and protein-protein interactions

Vitamin A and its derivatives have been postulated to play an important role in renal tubulogenesis and compensatory hypertrophy. This study examined the effects of two carboxylic derivatives of vitamin A on Lewis lung carcinoma-porcine kidney-1 (LLC-PK1) renal tubular epithelial cell mito- and motogenesis and cell size. It was found that all-trans and 13-cis retinoic acids exerted modest, dose-dependent effects to stimulate incorporation of 3H-thymidine into acid-precipitable material of LLC-PK1 cells. The effects of all-trans retinoic acid to promote 3H-thymidine uptake in LLC-PK1 cells modestly enhanced that seen with acidic fibroblastic growth factor. Similar findings of these two retinoic acid derivatives to promote 3H-thymidine uptake and to enhance 3H-thymidine uptake stimulated by another growth factor (platelet-derived growth factor BB) were also observed in cultured bovine aortic smooth muscle cells. Both retinoic acids promoted healing of denuded areas made within confluent monolayers of serum-starved LLC-PK1 cells. All-trans retinoic acid also stimulated recovery of mechanically denuded areas within bovine aortic smooth muscle monolayers. Neither all-trans nor 13-cis retinoic acids s affected cell size as assessed by forward light scatter with flow cytometry, suggesting lack of effect to induce hypertrophy. These results demonstrate that two carboxylic acid derivatives of vitamin A are capable of stimulation of basal and growth factor-induced incorporation of 3H-thymidine uptake into acid-precipitable material and healing of denuded areas in disparate cell types. These findings are compatible with a role for vitamin A and its analogues in the tissue repair process.     

Structural requirements for inhibition of cytokine-induced endothelial activation by unsaturated fatty acids

Dietary long-chain fatty acids (FA) may influence pathological processes involving endothelial activation, including inflammation and atherosclerosis. We have previously shown that the n-3 FA docosahexaenoate (DHA) inhibits endothelial activation in the range of nutritionally achievable plasma concentrations. The present study assessed structural determinants for this effect. Saturated, monounsaturated, and n-6 and n-3 polyunsaturated FA were incubated with cultured endothelial cells for 24-72 h alone, and then in the presence of interleukin-1, tumor necrosis factor, or bacterial lipopolysaccharide for an additional 24 h before assessing the expression of the vascular cell adhesion molecule-1 (VCAM-1) or other products of endothelial activation. No FA tested per se elicited endothelial activation. While saturated FA did not inhibit cytokine-induced expression of adhesion molecules, a progressively increasing inhibitory activity was observed, for the same chain length, with an increase in double bonds. Comparison of FA with the same length and number of unsaturation and only differing for the double bond position or for the cis/trans configuration indicated no difference in inhibitory potency, indicating no effect of the double bond position or configuration. As judged by Northern analysis, these latter FA also inhibited VCAM-1 messenger RNA steady state levels to the same extent, indicating a pre-translational site of action attributable to the single double bond. Thus the double bond is the minimum necessary and sufficient requirement for FA inhibition of endothelial activation. These properties are likely relevant to the anti-atherogenic and anti-inflammatory properties ascribed to n-3 FA, which are able to accommodate the highest number of double bonds in a fatty acid of given chain length.     

Auxiliary agents for the peroral administration of peptide and protein drugs: synthesis and evaluation of novel pepstatin analogues

The peroral administration of (poly)peptide drugs requires the development of delivery systems, which provide a protective effect toward a gastrointestinal enzymatic attack. A promising strategy for such systems represents polymer-enzyme inhibitor conjugates in which the embedded therapeutic agent is protected. However, the practical use of polymer-inhibitor conjugates has so far been limited by high production costs of these auxiliary agents. To solve this problem for delivery systems shielding from pepsinic degradation, structurally simplified analogues of the pepsin inhibitor pepstatin A have been synthesized. The synthesis of tripeptide analogues, described by McConnell et al., led us to pursue further modifications varying the C-terminus. Our target to attach a spacer moiety-enabling the free access of pepsin to the inhibitor-should be combined with an attractive synthetic approach providing low production costs in large-scale preparation. Structure modifications comprised either the side chain of the third amino acid which served as starting compound designing the C-terminus (L-leucine, L-isoleucine, L-norvaline) as the length of the spacer link, simulated by a linear alkyl group (n-butyl, n-hexyl, and n-octyl). The inhibitory activities which have been evaluated by an enzyme assay were significantly dependent on the nature of the side chain, whereas the length of the spacer had no influence on the inhibitory effect. Analogues bearing the isobutyl or n-propyl moiety as side chain displayed a strong inhibitory effect which was comparable to that pepstatin A. These congeners represent promising auxiliary agents for the peroral administration of (poly)peptide drugs.     

铜管在羧酸环境下的腐蚀行为和腐蚀机理研究

铜管是空调及制冷行业用热交换器的核心部件,在服役过程中常由于蚁穴腐蚀导致设备提前失效。本文采用蒸气腐蚀、电化学腐蚀方法研究了铜管在羧酸环境下的腐蚀行为,通过金相显微镜（OM）、扫描电镜（SEM）、 X射线粉末衍射仪（XRD）观察和分析了表面腐蚀形貌和腐蚀产物的结构,通过接触角测量仪研究了羧酸与铜管的界面行为。结果表明,与CH3COOH蒸气腐蚀相比,铜管在HCOOH蒸气环境下的腐蚀速度慢,腐蚀产物更致密。在HCOOH蒸气环境下,铜管容易出现蚁穴腐蚀。铜管表面的腐蚀产物主要由羧酸铜和氧化亚铜组成。蚁穴腐蚀属于电化学腐蚀,腐蚀机理复杂。腐蚀初期,表面氧化膜被聚集在铜管表面的羧酸溶解,暴露的铜基体作为微观阳极,之后,腐蚀坑内产生的微裂纹的尖端作为微观阳极,使腐蚀加速,直至贯穿管壁。     

Amygdalar area involved in predatory behavior in cats

Cytochalasin D, a mold metabolite identified in food, was injected intraperitoneally in doses of 0.4 to 0.9 mg per kilogram on gestational days 7 through 11 and produced evidence of teratogenicity in two out of three strains of mice. Exencephaly, hypognathia and axial skeletal defects were found in strains C57BL/6J and BALB/c while no increase in defects was observed in the Swiss Webster strain. In all three strains, a significantly increased resorption rate was found. Oral doses of approximately 7.0 mg per kg on days 7 through 11 in the BALB/c produced exencephaly in the offspring. Autoclaved cytochalasin D retained its teratogenic potential.     

Effects of folic acid and combinations of folic acid and vitamin B-12 on plasma homocysteine concentrations in healthy, young women

BACKGROUND: Elevated plasma homocysteine concentrations are considered to be a risk factor for vascular disease and fetal malformations such as neural tube defects. Recent studies have shown that plasma homocysteine can be lowered by folic acid in amounts corresponding to 1-2 times the recommended dietary allowance. Preliminary evidence indicates that vitamin B-12 may be beneficial when included in supplements or in a food-fortification regimen together with folic acid. OBJECTIVE: We aimed to compare the homocysteine-lowering potential of a folic acid supplement with that of 2 supplements containing different doses of vitamin B-12 in addition to folic acid. DESIGN: Female volunteers of childbearing age (n = 150) received a placebo for 4 wk followed by a 4-wk treatment with either 400 microg folic acid, 400 microg folic acid + 6 microg vitamin B-12, or 400 microg folic acid + 400 microg vitamin B-12. RESULTS: Significant reductions (P < 0.001) in plasma homocysteine were observed in all groups receiving vitamin treatment. The effect observed with the combination of folic acid + 400 microg vitamin B-12 (total homocysteine, -18%) was significantly larger than that with a supplement containing folic acid alone (total homocysteine, -11%) (P < 0.05). Folic acid in combination with a low vitamin B-12 dose (6 microg) affected homocysteine as well (-15%). CONCLUSIONS: These results suggest that the addition of vitamin B-12 to folic acid supplements or enriched foods maximizes the reduction of homocysteine and may thus increase the benefits of the proposed measures in the prevention of vascular disease and neural tube defects.     

Treatment of distal femoral fractures in the elderly. Results with the retrograde intramedullary supracondylar nail

The incidence of neural tube defects including myelomeningocele, which is one of the most common causes of infant and childhood disability, can be substantially reduced by folic acid supplementation to the diet of women before and during the early stages of pregnancy. All females of childbearing age should be taking folic acid supplements of 0.4 mg/day (400 micrograms/day) and consuming a diet rich in folate. Because many pregnancies are unplanned, supplementation should not await plans for pregnancy. Because pediatric nurse practitioners are in frequent contact with both adolescent patients and patients whose mothers are of childbearing age, and because pediatric nurse practitioners have an interest in preventing neural tube defects in future pediatric patients, they are in a good position to provide the necessary anticipatory guidance regarding the critical need for adequate folic acid intake by females of childbearing age. This article discusses and includes guidelines for providing this anticipatory guidance.     

Ataxia and a cerebellar defect in the exencephaly-prone SELH/Bc mouse stock

SELH/Bc inbred mice have an abnormal mechanism of anterior neural tube closure and 10-20% of embryos have a lethal neural tube closure defect, exencephaly. Our previous studies have focused on this multifactorial threshold trait. However, SELH mice are also characterized by another trait that also shows non-Mendelian transmission ratios, an ataxia recognized in juvenile and adult mice. Here we report our first genetic and morphological studies of the ataxia trait. Recent pedigree records for the SELH colony showed that 7% of the 467 weaned progeny from normal breeding pairs were ataxic; 17 of the 20 pairs produced ataxic progeny. This result was statistically consistent with the hypothesis that all SELH mice have the ataxic genotype, which is expressed in only 7% of them. Genetic studies of an outcross to a normal strain and the subsequent F2 and testcross of the F2 were also done. The results were consistent with a one or two gene locus cause of liability to ataxia in SELH mice. The genetic correlation between exencephaly production and ataxia production for a sample of nine F2 males was 0.35, as expected if both traits are caused by the same genes, but was not statistically significant. In another approach, we examined the morphology of brains from normal and ataxic adult SELH mice. All 20 brains from non-ataxic SELH mice were morphologically normal. In all 18 brains from ataxic SELH mice the cerebellum was abnormal, lacking the vermis, and characterized by a midline fissure. This phenotype in mice has previously been known in Mendelian mutants at the Wnt-1 locus.(ABSTRACT TRUNCATED AT 250 WORDS)