Cross-language synonyms in the lexicons of bilingual infants: one language or two?

This study tests the widely-cited claim from Volterra & Taeschner (1978), which is reinforced by Clark's PRINCIPLE OF CONTRAST (1987), that young simultaneous bilingual children reject cross-language synonyms in their earliest lexicons. The rejection of translation equivalents is taken by Volterra & Taeschner as support for the idea that the bilingual child possesses a single-language system which includes elements from both languages. We examine first the accuracy of the empirical claim and then its adequacy as support for the argument that bilingual children do not have independent lexical systems in each language. The vocabularies of 27 developing bilinguals were recorded at varying intervals between ages 0;8 and 2;6 using the MacArthur CDI, a standardized parent report form in English and Spanish. The two single-language vocabularies of each bilingual child were compared to determine how many pairs of translation equivalents (TEs) were reported for each child at different stages of development. TEs were observed for all children but one, with an average of 30% of all words coded in the two languages, both at early stages (in vocabularies of 2-12 words) and later (up to 500 words). Thus, Volterra & Taeschner's empirical claim was not upheld. Further, the number of TEs in the bilinguals' two lexicons was shown to be similar to the number of lexical items which co-occurred in the monolingual lexicons of two different children, as observed in 34 random pairings for between-child comparisons. It remains to be shown, therefore, that the bilinguals' lexicons are not composed of two independent systems at a very early age. Furthermore, the results appear to rule out the operation of a strong principle of contrast across languages in early bilingualism.     

Polycyclic aromatic hydrocarbon-DNA adducts in human placenta and modulation by CYP1A1 induction and genotype

This study investigated the relationship in human placenta between polycyclic aromatic hydrocabon (PAH)-DNA adduct levels and two biomarkers of cytochrome P4501A1 (CYP1A1): gene induction evidenced by CYP1A1 mRNA, and a genetic polymorphism, the CYP1A1 MspI RFLP. CYP1A1 codes for an inducible enzyme system that catalyzes the bioactivation of PAHs. Prior research found a high correlation in human lung tissue between CYP1A1 activity and DNA damage from PAHs. The CYP1A1 Mspi RFLP has been linked in some studies to risk of lung cancer. The relationships in human placenta between DNA damage, CYP1A1 activity and genotype have not been well characterized and may be relevant to risks from transplacental PAH exposure. The study cohort consisted of 70 newborns from Krakow, Poland, a city with elevated air pollution, and 90 newborns from nearby Limanowa, an area with lower air pollution but greater indoor coal use. Contrary to results seen previously in lung tissue, CYP1A1 mRNA was not significantly correlated with PAH-DNA adduct levels in the placenta. Smoking (self-reported maternal and infant plasma cotinine) was significantly associated with CYP1A1 mRNA levels (P < 0.01), but not with PAH-DNA adduct levels. Placental PAH-DNA adduct levels were significantly higher in infants with the CYP1A1 MspI restriction site compared with infants without the restriction site (P < 0.01), implicating a genetic factor in inter-individual variation in DNA damage in human placenta. Further studies are needed to determine the relevance of this finding to risk of transplacental carcinogenesis.     

Isolation of type II epithelial cells from rabbit fetal lungs by adherence on an IgG-coated surface

The lung is comprised of about 40 different cell types, of which only 15% are type II cells. These are the major, if not the sole, source of synthesis and secretion of lung surfactant. To date a large number of methods have been described for the isolation of pure populations of type II cells using a wide variety of techniques, but most of these have employed differential centrifugation methods and have used adult rodents. The present study reports the isolation of type II cells from fetal rabbit lungs by the immunoglobin G plating method. Pure populations of fetal type II cells in high yield and with good viability were obtained by the procedure for the first time from rabbit fetal tissue.     

Influence of solvent composition and degree of reaction on the formation of surface microtopography in a thermoset siloxane-urethane system

The effects of solvent composition and degree of reaction prior to film formation leading to the formation of a biphasic microtopographical surface in a crosslinked siloxane-urethane coating system were explored. For the solvent composition study, a D-optimal mixture design study was carried out using methyl n-amyl ketone (MAK), toluene, ethyl 3-ethoxypropionate (EEP), butyl acetate (BA) and isopropyl alcohol (IPA) as solvents. The study revealed that the presence of slow evaporating solvents MAK, EEP and the absence of fast evaporating solvent IPA in the solvent composition with a minimal amount of BA favored formation of a structured surface. Control over the domain size could be obtained by varying the MAK:EEP ratio in solvent compositions having a fixed amount of BA. The effect of mixing time on the formation of surface domains was studied. At short mixing times (<2 h) and long mixing times (>7 h), no surface phase separation is observed, while at intermediate times a ‘window’ was found where surface microdomains of similar size are generated. Doubling the level of catalyst halves the mixing time required to generate surfaces with microdomains. Scanning electron microscopy (SEM) studies with energy dispersive X-ray mapping and dynamic mechanical analysis (DMA) were done in order to understand the development of the phases in the PDMS-polyurethane system.     

Switching and memory devices based on a polythiophene derivative for data-storage applications

In this article, we report electrical characteristics of devices based on oriented and unoriented films of a polymer, namely poly[3-(6-methoxyhexyl)thiophene]. The current–voltage characteristics of sandwiched devices, based on unoriented polymer, showed hysteresis behavior, while oriented versions exhibited switching characteristics, i.e. presence of two conducting states depending on sweep direction of voltage scans. The ratio between the device current of two conducting states has been as high as 10⁵. This is comparable, if not better, than the results reported so far with complicated device architecture or doped polymeric materials. We have also demonstrated that the switching devices have an associated memory effect for data-storage applications.     

Muscle Rad expression and human metabolism: potential role of the novel Ras-related GTPase in energy expenditure and body composition

Ras associated with diabetes (Rad), a new ras-related GTPase, was recently identified by subtractive cloning as an mRNA in skeletal muscle that is overexpressed in NIDDM. To better understand its metabolic significance, we measured skeletal muscle Rad expression in well-characterized insulin sensitive (IS) and insulin resistant (IR) subjects with normal glucose tolerance and in untreated NIDDM patients. We found no differences in expression of Rad mRNA levels among IS, IR, and NIDDM groups using a ribonuclease protection assay (0.22 +/- 0.06, 0.13 +/- 0.01, and 0.16 +/- 0.02 relative units, respectively; NS) and no differences in Rad protein expression using a specific anti-peptide Rad antibody (1.05 +/- 0.18, 1.14 +/- 0.08, and 1.08 +/- 0.21 units/mg protein, respectively; NS). However, Rad protein levels were positively correlated with BMI (r = 0.43, P = 0.03) and percentage body fat (r = 0.55, P < 0.005), two independent measures of obesity, and negatively correlated with resting metabolic rate (r = 0.49, P = 0.01). In multiple regression analyses, percentage body fat and resting metabolic rate independently accounted for 30 and 10% of individual variability in muscle Rad protein expression. In conclusion, Rad expression in skeletal muscle is not altered as a function of insulin resistance or NIDDM in humans. However, these data, for the first time, implicate a role for Rad in regulating body composition and energy expenditure and provide a framework for studies designed to elucidate Rad's cellular functions.     

The incidence of low-pressure urethra as a function of prolapse-reducing technique in patients with massive pelvic organ prolapse (maximum descent at all vaginal sites)

OBJECTIVE: Our aims were to compare several prolapse-reducing techniques during urodynamic evaluation and prospectively evaluate their usefulness in identifying the incidence of low urethral closure pressure in continent patients with massive prolapse. STUDY DESIGN: This preoperative, prospective, repeated-measures urodynamic study evaluated the maximum urethral closure pressure with the use of four different techniques in 30 consecutive continent patients with grade 4 prolapse at all vaginal sites. Twenty patients with grade 0 prolapse served as the control group. All patients from the prolapse group underwent surgical treatment and were followed up clinically for a minimum of 1 year. RESULTS: Use of the Scopette (Birchwood Laboratories, Eden Prairie, Minn.) reduction technique to reduce the prolapse in a linear orientation during multichannel urodynamics revealed a 56% incidence of low-pressure urethra and an overall genuine stress urinary incontinence of 83% in patients with massive pelvic organ prolapse but without clinical urinary incontinence. CONCLUSIONS: There may be an increased indication for sling urethropexy in patients with massive prolapse.     

Paediatric upper gastrointestinal endoscopy: a 2-year review

OBJECTIVE: To review the paediatric upper gastrointestinal endoscopy service in a paediatric department in Hong Kong. METHODS: Records of all endoscopies undertaken in this department from May 1995 to January 1996 were retrieved and analysed. RESULTS: The commonest indication for upper endoscopy was dyspepsia with 88% positive histological findings. Helicobacter pylori (H. pylori) was found in 25% of this group of children. CONCLUSION: Paediatric upper gastrointestinal endoscopy service is invaluable in a paediatric department by providing useful diagnostic information which would otherwise be missed.     

Detection of oxidative stress in heart by estimating the dinitrophenylhydrazine derivative of malonaldehyde

Accurate estimation of the oxidative stress in heart is necessary because the pathogenesis of many heart diseases are believed to be mediated at least in part from the development of oxidative stress resulting from the generation of oxygen free radicals and reduced antioxidant defense system. The most widely used method for this purpose has been the estimation of malonaldehyde (MDA), a lipid peroxidation product, by the thiobarbituric acid (TBA) reaction method. However, because of the nonspecificity of this method, the results are often erroneous. The present report describes a method using high-performance liquid chromatography (HPLC) to estimate MDA. To develop the oxidative stress, two different models were used: ischaemic-reperfused heart and perfusing the heart with a hydroxyl radical (OH+) generating system. The coronary effluents obtained from the isolated rat heart before ischaemia and during the reperfusion of ischaemic heart, as well as during the perfusion of the heart with the OH+ generating system were collected, derivatized with 2,4-dinitrophenylhydrazine (DNPH) and extracted with pentane. Aliquots of 25 microliters in acetonitrile were injected onto a Beckman Ultrasphere C18 (3 microns) column. The products were eluted isocratically with a mobile phase containing acetonitrile-water-acetic acid (40:60:0.1, v/v/v), measured at 307 nm using a Waters M-490 multichannel UV detector and collected for gas chromatography-mass spectrometry (GC-MS). The peaks were identified by co-chromatography with DNPH derivatives of authentic standards, peak addition, and by GC-MS. The retention time for MDA-DNPH was 5.3 min.(ABSTRACT TRUNCATED AT 250 WORDS)