CO2 sensing at room temperature using carbon nanotubes coated core fiber Bragg grating.

The sensing of carbon dioxide (CO2) at room temperature, which has potential applications in environmental monitoring, healthcare, mining, biotechnology, food industry, etc., is a challenge for the scientific community due to the relative inertness of CO2. Here, we propose a novel gas sensor based on clad-etched Fiber Bragg Grating (FBG) with polyallylamine-amino-carbon nanotube coated on the surface of the core for detecting the concentrations of CO2 gas at room temperature, in ppm levels over a wide range (1000 ppm-4000 ppm). The limit of detection observed in polyallylamine-amino-carbon nanotube coated core-FBG has been found to be about 75 ppm. In this approach, when CO2 gas molecules interact with the polyallylamine-amino-carbon nanotube coated FBG, the effective refractive index of the fiber core changes, resulting in a shift in Bragg wavelength. The experimental data show a linear response of Bragg wavelength shift for increase in concentration of CO2 gas. Besides being reproducible and repeatable, the technique is fast, compact, and highly sensitive.

Dissolution, solubility, XRD, and DSC studies on flurbiprofen-nicotinamide solid dispersions.

Flurbiprofen-nicotinamide solid dispersions were prepared by the fusion method. The solid dispersions were evaluated for dissolution rate. The drug-carrier interaction in the liquid and solid states were studied by using phase solubility analysis, phase diagram, X-ray diffraction (XRD), and differential scanning calorimentry (DSC). Solid dispersions gave fast and rapid dissolution of flurbiprofen compared with the pure drug and the physical mixture. Phase diagram and DSC indicated that flurbiprofen and nicotinamide form a eutectic mixture. The aqueous solubility of flurbiprofen was enhanced in the presence of nicotinamide.

Spinning-disk self-referencing interferometry of antigen-antibody recognition.

A gold ridge microstructure fabricated to a height of lambda/8 on a high-reflectivity substrate behaves as a wave-front-splitting self-referencing interferometer in phase quadrature when illuminated by a Gaussian laser beam and observed in the far field along the optic axis. When immuno-gammaglobulin (IgG) antibodies are selectively immobilized on the gold microstructure, they recognize and bind to a specific antigen, which shifts the relative optical phase of the interferometer and modifies the far-field diffracted intensity. We detect bound antigen interferometrically on spinning disks at a sampling rate of 100 kHz and verify the interferometric nature of the signal by using two quadratures of opposite sign to rule out effects of dynamic light scattering. Strong molecular recognition is demonstrated by the absence of binding to nontarget molecules but strong signal change in response to a specific antigen. This BioCD has the potential to be applied as a spinning-disk interferometric immunoassay and biosensor.

Neuroendocrine effects of toxic and low blood lead levels in children.

From 3 million to 4 million children in America have lead poisoning. This environmental toxin affects 1 in every 6 children younger than 6 years of age in the United States. The marked effects of lead toxicity on the central nervous system are well known, ie, lowering IQ and impairing memory, reaction time, and the ability to concentrate. Children are at greatest risk for the central nervous system effects of lead because the central nervous system is at its peak in development during the first few years of life. The negative correlation of stature and blood lead level (bPb) found in the National Health and Nutrition Examination Survey directed the authors to evaluate the possible neuroendocrine effects of this toxin in children. Twelve children were studied during toxic (greater than or equal to 40 micrograms/dL) and low bPb (less than 40 micrograms/dL). Classic provocative stimuli, L-dopa (15 mg/kg by mouth) and insulin (0.1 U/kg given intravenously), were used to determine human growth hormone (hGH) responses during toxic bPb and after chelation therapy in six of the subjects. An additional four subjects were studied during low bPb. In two patients LGH levels were determined every 20 minutes for 24 hours during toxic bPb. Thyroid-stimulating hormone and prolactin responses to thyrotropin-releasing hormone were also determined. All children studied showed growth retardation during toxic bPb. Mean peak hGH responses to provocative stimuli were lower during toxic bPb, but the responses were all within normal limits.(ABSTRACT TRUNCATED AT 250 WORDS)

Reproductive hormones and bone mineral density in women runners.

We examined the relationships among reproductive hormone concentrations and bone mineral density (BMD) in 43 women runners classified as eumenorrheic (n = 24), oligomenorrheic (n = 8), or amenorrheic (n = 11). Results were compared with a eumenorrheic nonrunner control group (n = 11). Serum 17 beta-estradiol, progesterone, and dehydroepiandrosterone sulfate concentrations were determined in daily blood samples for 21 days, and integrated concentrations (areas under the curve) were calculated. BMD was assessed at the lumbar spine and proximal femur by dual-photon absorptiometry. As expected, 17 beta-estradiol, progesterone, and lumbar spine BMD were higher in the control and eumenorrheic runner groups than in the oligomenorrheic and amenorrheic runner groups (P less than 0.05). Progesterone concentration was significantly correlated with lumbar spine BMD in the eumenorrheic runners (r = 0.61). None of the steroid hormones was significantly related to BMD in the oligomenorrheic/amenorrheic group. The present data suggest that circulating levels of gonadal steroid hormones affect axial BMD in eumenorrheic runners.

In vitro mutagenicity of water contaminants in complex mixtures.

Trihalomethanes, Carbon tetrachloride and trichloroethylene were tested in single, binary and multi-complex mixtures using standard tester strains TA1535, TA1537, TA98 and TA100 of Salmonella typhimurium with and without addition of an in vitro metabolizing fraction S-9. Chloroform (CHCl3) was found to be mutagenic in all strains without S-9 activation. However, when tested with Bromoform (15%), which was nonmutagenic singly, the combined effect of the mixture was nonmutagenic. CCl4 was a direct mutagen (without S-9) in all strains except TA 1535. When combined with 85% CHCl3, only strains TA1535 and TA1537 were mutagenic. When tested with mammalian activation (S-9), CCl4 was mutagenic in all strains. However, when tested with CHCl3 (CHCl3 and CCl4-85:15), the mutagenic capability was lost. With or without S-9 Activation multi-complex mixture of CHCl3, CCl4 and TCE (85:8:7) was mutagenic for a narrow range of doses in all strains.

Theophylline treatment in the neonate with apnea: effect on growth hormone, thyroid hormone and TRH induced TSH secretion.

Caffeine has been shown to markedly alter growth hormone (GH), thyroid stimulating hormone (TSH), and thyroid hormones in animal studies. Similar studies in the human are lacking. To determine the effect of theophylline treatment on endocrine function in neonates with apnea, 10 infants were studied prospectively pretreatment, immediately following therapeutic blood levels of theophylline, at 2, 4, and 6 weeks thereafter and finally 2 weeks after discontinuation of theophylline. T4, free T4, T3, GH, and basal and stimulated TSH were measured at each study period. Results show no significant difference consequent to theophylline therapy on basal thyroid or GH secretion and thyrotropin-releasing hormone (TRH) induced TSH response at any study interval. We conclude there is no evidence to suspect abnormality occurring in growth, thyroid function and GH secretion in neonates receiving theophylline for breathing disorders.

Volvulus of the small intestine.

A series of seventy-five cases of volvulus of the small intestine are reviewed. There is a 14.2% incidence of this condition among cases of acute intestinal obstruction. It is more common than cecal volvulus but less common than sigmoid volvulus. The patients are usually healthy, poor, adult villagers whose diet is heavy and vegetarian with a high roughage content; they mainly do hard manual work. It is difficult to make a correct preoperative diagnosis. In this series, the percentage of primary volvulus is 73.33% and of secondary is 26.66%. The etiology, incidence, symptomatology and mortality are studied.

Thyroid-stimulating hormone and prolactin responses to thyrotropin-releasing hormone during infusion of epinephrine and propranolol in man.

Male volunteers were administered 100 microgram thyrotropin-releasing hormone (TRH) intravenously during control (saline) and drug (epinephrine-propranolol) infusions. There were no differences in the thyroid-stimulating hormone (TSH) or prolactin responses to TRH during the epinephrine-propranolol infusion periods. There were no significant differences in growth hormone (GH) responses to epinephrine-propranolol infusions. Epinephrine-propranolol had no detectable effect on basal TSH, prolactin and GH concentrations. We conclude that the alpha-adrenergic system does not play any role at the pituitary level in modulating the effect of TRH-stimulated TSH or prolactin secretion in male volunteers.

Comparison of native and microwave irradiated DNA.

Chemical changes induced in the testicular DNA of irradiated Swiss male mice are described. Parameters quantified were hyperchromocity and melting temperature. The data supports the possibility that microwave causes strand separation.

Treatment of congenital virilizing adrenal hyperplasia patients with single and multiple daily doses of prednisone.

Six patients with congenital virilizing adrenal hyperplasia were evaluated on single- and multiple-dose prednisone schedules. Each of the treatment periods was for one month. Patients were evaluated by 24-hour urinary excretion of 17-ketosteroids and pregnanetriol, as well as 0900 plasma concentrations of 17-hydroxyprogesterone, progesterone, and testosterone. By the criteria of urinary excretion of KS and PNT appropriate for chronologic age, three of the six patients were adequately controlled on prednisone given once a day. Prednisone administered twice daily at 12-hourly intervals either in equally divided doses or with a larger dose in the evening, however, resulted in adequate suppression in all patients. Because of the marked diurnal variation of plasma 17-OHP, the time of day that the sample is drawn is critical. Afternoon samples are often misleadingly low. Plasma 17-OHP concentration may reflect escape from therapeutic control sooner than urinary KS and PNT excretion. There was no correlation between 17-OHP and P values. Plasma concentration of T was not a reliable indicator of good control, since T values were often at prepubertal levels when urinary KS and PNT were elevated.

Effect of prolactin on adrenocortical and gonadal function in normal men.

Dehydroepiandrosterone (DHA), dehydroepiandrosterone sulfate (DHAS), androstenedione (A), testosterone (T), estrone (E1), estradiol (E2) and gonadotropins were measured in 3 normal adult men before and after administration of 50 mg ovine prolactin for 5 days. No significant change as a result of ovine prolactin administration was observed in any of the parameters examined.

Effect of cyproheptadine on TRH-stimulated prolactin and TSH release in man.

TRH-stimulated prolactin release was determined in four male volunteers with and without pre-treatment with cyproheptadine. All showed a marked increase in the TRH-mediated prolactin rise and a marked decrease in the TRH-mediated TSH rise when receiving cyproheptadine pre-treatment.