Characterization of electroluminescent structures based on gallium arsenide ion-implanted with ytterbium and oxygen

Light-emitting diodes based on GaAs crystals ion-implanted with ytterbium and oxygen were fabricated. The current-voltage and capacitance-voltage characteristics of these diodes were analyzed. The deep-level centers were studied by the deep-level transient spectroscopy. The electroluminescence spectra of the structures include the emission lines related to optical transitions within the 4f shell of Yb³⁺ ions.     

Respiratory disease in workers exposed to colophony solder flux fumes: continuing health concerns

The objectives of this study were to establish the prevalence of respiratory, eye, nose and throat symptoms of likely work-relation in workers exposed to colophony solder flux fumes and to assess their lung function. A cross-sectional study was conducted in four medium-sized electronics firms in which control measures to capture solder flux fume were absent or visibly ineffective. All female solders and women working adjacent to soldering stations completed an administered questionnaire concerning symptoms, work history and current soldering frequency. Measurements were made of their forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) during the course of a working shift, using a Vitallograph-Compact portable spirometer. Using weekly hours of soldering as a crude index of current exposure, workers were classified into high (> or = 37 h/wk) and low (< or = 20 h/wk) exposure groups, and their health responses were compared in the analysis. Individuals with symptoms suggestive of work-related asthma were also asked to provide serial peak flow measurements over a further 2-week period, and adequate returns were charted and read by two physicians experienced in the diagnosis of occupational asthma. Data were collected on 152 female workers (overall participation rate = 97%). Symptoms of recurrent, persistent wheeze and/or chest tightness were reported by 75 (49%) of interviewees; 36 (24%) gave a history typical of occupational asthma and six more (4%) a history of pre-existing asthma worsened at work. Twenty-one (14%) of the workforce complained of recurrent breathlessness on moderate exertion; 41 workers (27%) had work-related symptoms of the nose or throat and 25 (16%) had work-related eye symptoms. The odds ratios for 'all wheeze', shortness of breath, and work-related eye, nose and chest symptoms were all significantly greater (raised about 4-5 fold) in women who soldered > or = 37 h/wk when compared with those soldering < or = 20 h/wk. After adjustment by logistic regression for atopy, age and smoking status even higher risk estimates were generally obtained. The odds ratios (OR) and 95% confidence intervals (CI) for high vs. low were: for 'all wheeze', OR = 7.2, CI = 2.5-20.7; for work-related eye symptoms, OR = 5.2, CI = 1.4-19.8; for work-related nasal symptoms, OR = 4.0, CI = 1.4-11.1 and for occupational asthma symptoms, OR = 5.2, CI = 1.4-14.2. Mean FEV1 and FVC percentage difference from expected were slightly lower in full-time solderers than in part-time solderers, but the differences were not significant. Thirty-seven of the 51 workers (73%) who were asked to carry out serial peak flow measurements completed an adequate return: 27 of these records confirmed the presence of asthma, and in all of the cases the history suggested onset post-dating employment in soldering. Eleven peak flow records were indicative of occupational asthma. The health problems associated with colophony solder flux were documented over 18 years ago, but are still clearly apparent in situations where adequate control has not been achieved.     

Reactive oxygen species and antioxidants in signal transduction and gene expression

Reactive oxygen species (ROS) are produced by cellular metabolic reactions, and have been implicated in the pathogenesis of several diseases, including atherosclerosis, cancer, and Alzheimer's disease. Interestingly, clinical and epidemiologic studies have, in some cases, indicated that antioxidant nutrients may be effective in disease prevention. However, the efficacy of specific antioxidants in disease prevention is often both controversial and inconclusive. In an effort to elucidate the role of ROS and antioxidants in disease development and prevention, the chemistries of ROS and antioxidants have been examined extensively. Recently, molecular and cellular approaches have demonstrated that ROS and antioxidants can directly affect the cellular signaling apparatus and, consequently, the control of gene expression. This new research provides the link between ROS and antioxidant chemistries and the mechanisms of disease processes and prevention. This review illustrates how ROS function as potential intracellular and extracellular signaling molecules and how antioxidants can affect this process.     

Cognitive functioning in older depressed outpatients: Relationship of presence and severity of depression to neuropsychological test scores.

Neuropsychological evaluation of 73 older healthy, unmedicated outpatients with major depression and 110 controls suggested that relatively distinct cognitive profiles may correspond to the presence vs. severity of depression. Specifically, the presence of depression was associated with subtle weaknesses in visual memory and nonverbal intelligence, with sparing of verbal skills (verbal intelligence, language, and verbal memory), constructional ability, attention, information processing speed, and executive functions. In contrast, increasing severity of depression was associated with mild weaknesses, primarily in information-processing speed and executive skills, but was essentially unrelated to memory (verbal or visual), intelligence, language skills, constructional ability, or basic attention. Findings are discussed in terms of a possible state vs. trait model of depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Management considerations for treating vesicoureteral reflux in children with solitary kidneys

OBJECTIVES: To evaluate the management approach for vesicoureteral reflux (reflux) into a solitary kidney. METHODS: Outcomes of all children with solitary kidneys and reflux managed between 1981 and 1996 were reviewed. Solitary kidneys were documented by nuclear renography and ultrasonography; reflux was graded after cystography. Management consisted of observation and antimicrobial prophylaxis or surgery by ureteroneocystostomy or subureteric injection of polytetrafluoroethylene (STING). Follow-up ranged from 3 months to 14 years and included serial cystography, sonography, and serum creatinine measurement. RESULTS: Twenty-one patients with a median follow-up of 26 months were identified. Etiologies included contralateral renal agenesis (14 children), multicystic dysplastic kidney (5 children), or nonfunctioning ureteropelvic junction obstruction (2 children). Low-grade (I to II) reflux was identified in 6 children, and high grade (III to V) was identified in 15. Reflux resolved in 20 patients. Five children with low-grade reflux were managed without surgery and demonstrated reflux resolution after a mean of 20.5 months. Renal function deteriorated in only 1 child. Ureteroneocystostomy was performed in 13 children with grades III to V reflux, and STING was performed in 1 child with grade II reflux. Every surgical patient maintained stable renal function and was infection-free during a mean follow-up of 56 months. Management by observation in 2 children with grades IV to V reflux resulted in spontaneous resolution in one and stable grade IV in the other. CONCLUSIONS: Reflux into the solitary functioning kidney may be managed by the same strategies used to manage unilateral reflux in children with two normally functioning kidneys: low-grade reflux by observation/ chemoprophylaxis until spontaneous resolution occurs, and higher grades by surgery to protect renal function; however, chemoprophylaxis and serial imaging may be used until well-defined indications for surgery are satisfied. Renal function should be monitored diligently.     

Localization of ROMK channels in the rat kidney

Renal potassium secretion occurs in the distal segments of the nephron through apically located secretory potassium (SK) channels. SK may correspond to the ROMK channels cloned from rat kidney. In this study, the localization of ROMK at the cellular level in the rat kidney was examined using an affinity-purified polyclonal antibody raised against a C-terminal peptide of ROMK. The specificity of the antibody was demonstrated by immunoblots of membranes of Xenopus oocytes expressing ROMK2. Immunoblots of homogenates from rat renal outer medulla and cortex revealed predominant bands of 70 to 75 kD, which were ablated by preadsorption with an excess of peptide. These bands were specific for the rat kidney. Immunolocalization studies revealed that ROMK is expressed in specific nephron segments in both the cortex and medulla. In the cortex, ROMK was found in the apical domain of the thick ascending limb of Henle's loop, the connecting tubule, and in some, but not all, cells of cortical collecting tubules. In the medulla, expression in the apical membrane of the thick ascending limbs of Henle's loop was strong, whereas outer medullary collecting ducts were weakly stained. Expression in the thick ascending limb was also heterogeneous; some cells that expressed the Na-K-Cl cotransporter were weakly stained with the anti-ROMK antibody. No staining of glomeruli, proximal tubules, or inner medullary collecting ducts was found. The localization of ROMK agrees well with the findings of SK in patch-clamp studies and supports the view that ROMK is the SK channel of the distal segments of the nephron.     

Six-month outcome of critically ill patients given glutamine-supplemented parenteral nutrition

Tetrahydrobiopterin is an essential cofactor required for activity of nitric oxide synthases. Existing evidence suggests that, during activation of constitutive and inducible isoforms of nitric oxide synthase, tetrahydrobiopterin is needed for allosteric and redox activation of enzymatic activity. However, precise mechanisms underlying the role of tetrahydrobiopterin in regulation of nitric oxide formation is not fully understood. In cerebral and peripheral arteries, increased availability of tetrahydrobiopterin can augment production of nitric oxide. In contrast, in arteries depleted of tetrahydrobiopterin, production of nitric oxide is impaired. Proinflammatory cytokines enhance mRNA expression of the rate-limiting enzyme of tetrahydrobiopterin biosynthesis, GTP cyclohydrolase I and stimulate production of tetrahydrobiopterin. The ability of vascular tissues to synthesize tetrahydrobiopterin plays an important role in regulation of nitric oxide synthase under physiological conditions as well as during inflammation and sepsis. More recent studies concerning expression and function of recombinant nitric oxide synthases suggest that availability of tetrahydrobiopterin is important for production of nitric oxide in genetically engineered blood vessels. In this review, mechanisms regulating availability of intracellular tetrahydrobiopterin and its role in control of vascular tone under physiological and pathological conditions will be discussed.     

Timing of in vivo maturation of equine preovulatory oocytes and competence for in vitro maturation of immature oocytes collected simultaneously

The objects of this study were to monitor the development of the cumulus complex and nuclear maturation in oocytes recovered from preovulatory follicles following treatment to induce ovulation and to investigate the in vitro maturation competence of oocytes recovered from smaller nonpreovulatory follicles of varying size. All follicles > or =5 mm in pony mares were individually punctured at 0, 6, 12, 24 and 35 h after an injection of LH to induce ovulation. The recovery rates of oocytes were 64% from 55 preovulatory follicles, 22% from 32 subordinate follicles and 52% from 227 small follicles. Cumulus expansion of the preovulatory oocytes occurred at 12 h post LH treatment while the metaphase I and II components of nuclear maturation were not completed until 24 and 35 h post LH respectively. For nonpreovulatory follicles, the frequency of atresia and oocyte competence for in vitro nuclear maturation both increased with increasing follicular size.     

Extent of radial sarcomere coupling revealed in passively stretched cardiac myocytes

We report a simple method, the PinPoint assay, for detecting and identifying single-base variations (polymorphisms) at specific locations within DNA sequences. An oligonucleotide primer is annealed to the target DNA immediately upstream of the polymorphic site and is extended by a single base in the presence of all four dideoxynucleotide triphosphates and a thermostable DNA polymerase. The extension products are desalted, concentrated, and subjected to delayed-extraction MALDI-TOF mass spectrometry. The base at the polymorphic site is identified by the mass added onto the primer. Heterozygous targets produce two mass-resolved species that represent the addition of both bases complementary to those at the polymorphic site. The assay is suitable for double-stranded PCR products without purification or strand separation. More than one primer can be simultaneously extended and then mass-analyzed. The mass spectrometric method thus shows promise for high-volume diagnostic or genotyping applications.     

Speech recognition for the disabled

A simple and inexpensive system for telephone communication that includes a modular speech recognition device developed for use by a disabled person is presented. User considerations are reviewed, and hardware details are given. The complete automatic speech recognition (ASR) system consists of five main blocks: a TCM29C18 codec (analog interface for the digital signal processor), an SRS-1 speech recognizer, an LED display, a dual-tone multifrequency generator, and tone enable plus data input circuitry. Results of a semiqualitative assessment in terms of recognition success for the limited vocabulary of numbers and commands from the user are reported. The results are described in chronological order, beginning with testing of the SRS-1 and the codec working as a stand-alone recognizer system, and leading to the testing of the recognition system combined with the tone generator. Finally, results were obtained when the whole ASR system was interfaced to the telephone line. Some further work is suggested.