Electrochemically deposited bimetallic SERS substrate for trace sensing of antibiotics

Electrochemically deposited bimetallic copper-gold nanoparticles on indium tin oxide (Cu-AuNPs on ITO) glass are demonstrated to be a sensitive and reproducible surface-enhanced Raman scattering (SERS) platform. An optimal signal enhancement with reasonably good degree of homogeneity was obtained by tuning the deposition parameters of the electrochemical setup. For Raman active analytes such as malachite green (MG) and rhodamine 6G (R6G), the developed SERS platform yields a limit of detection (LOD) of 0.75 nM. The usability of the proposed SERS platform has been realized through detection of two important antibiotics namely sulfamethoxazole (SFZ) and tetracycline hydrochloride (TCH) commonly used in egg farms. Furthermore, a machine learning (ML)-based model coupled with a dimensionality reduction technique-principal component analysis (PCA)-has been implemented to classify the targeted analytes in egg samples.

Detection and analysis of rotavirus in clinical stool samples using silver nanoparticle functionalized paper as SERS substrate

Among the different analytical techniques, surface-enhanced Raman scattering (SERS) approach is a widely used technique for the detection and analysis of various chemicals and biological samples. Present study reports a low-cost, sensitive SERS substrate that has an ability to detect rotavirus in clinical stool samples. The proposed SERS substrate has been fabricated through drop-casting of silver nanoparticles (AgNPs) on a printing-grade paper. Rotavirus particles were extracted from clinical stool samples. The presence of rotavirus antigen in stool samples was confirmed using enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction (PCR), and sequencing. The characteristic Raman peaks of rotavirus (RV) particles in solution were found to be significantly enhanced when Raman signals were recorded from the paper-based SERS substrates. Using the proposed SERS substrate, rotavirus samples with concentration as low as 1% could be reliably recorded by the Raman spectrometer. The paper SERS substrate reported herein is an extremely cost-efficient platform and may find applications in other research and clinical laboratories as well.

SERS determination and multivariate classification of antibiotics in chicken meat using gold nanoparticle-decorated electrospun PVA nanofibers

The fabrication of SERS substrate by gold nanoparticle-decorated polyvinyl alcohol electrospun nanofibers which has been used to detect trace sensing of two widely used poultry antibiotics doxycycline hydrochloride and enrofloxacin is demonstrated. The performance of the backscattered Raman signals from the proposed SERS substrate has been initially evaluated with two standard Raman active compounds namely malachite green and rhodamine-6G. The limit of detection of the proposed substrate is estimated to be 7.32 nM. Following this, the usability of the proposed SERS substrate has been demonstrated through the detection of the aforementioned antibiotics in chicken meat samples. The presence of antibiotics in chicken meat sample has been validated with the standard analytical tool of liquid chromatography-mass spectrometry and the results were compared with the proposed sensing technique. Further, principal component analysis has been performed to classify the antibiotics that are present in the field-collected meat samples.

Gold nanoparticle decorated blu-ray digital versatile disc as a highly reproducible surface-enhanced Raman scattering substrate for detection and analysis of rotavirus RNA in laboratory environment

Detection and estimation of various biomolecular samples are often required in research and clinical laboratory applications. Present work demonstrates the functioning of a surface-enhanced Raman scattering (SERS) substrate that has been obtained by drop-casting of citrate-reduced gold nanoparticles (AuNPs) of average dimension of 23 nm on a bare blu-ray digital versatile disc (BR-DVD) substrate. The performance of the proposed SERS substrate has been initially evaluated with standard Raman active samples, namely malachite green (MG) and 1,2-bis(4-pyridyl)ethylene (BPE). The designed SERS substrate yields an average enhancement factor of 3.2 × 10⁶ while maintaining reproducibility characteristics as good as 94% over the sensing region of the substrate. The usability of the designed SERS substrate has been demonstrated through the detection and analysis of purified rotavirus double-stranded RNA (dsRNA) samples in the laboratory environment condition. Rotavirus RNA concentrations as low as 10 ng/μL could be detected with the proposed sensing scheme.

Design, fabrication and testing of 3D printed smartphone-based device for collection of intrinsic fluorescence from human cervix

Fluorescence spectroscopy has the potential to identify discriminatory signatures, crucial for early diagnosis of cervical cancer. We demonstrate here the design, fabrication and testing of a 3D printed smartphone based spectroscopic device. Polarized fluorescence and elastic scattering spectra are captured through the device using a 405 nm laser and a white LED source respectively. The device has been calibrated by comparison of spectra of standard fluorophores (Flavin adenine dinucleotide, fluorescein, rhodamine, and porphyrin) with the corresponding spectra collected from a commercial spectrometer. A few cervical tissue spectra have also been captured for proof of its applicability as a portable, standalone device for the collection of intrinsic fluorescence spectra from human cervix.

Synergy of Adsorption and Plasmonic Photocatalysis in the Au-CeO2 Nanosystem: Experimental Validation and Plasmonic Modeling

Adsorption-mediated water treatment leaves adsorbents as secondary pollutants in the environment. However, photocatalysis aids in decomposing the contaminant into its nontoxic forms. In this context, we demonstrate an adsorption-photocatalysis pairing in Au-CeO₂ nanocomposites for a total methylene blue (MB) removal from water. We synthesized Au-CeO₂ through the citrate (cit) reduction method at different Au loading and studied its adsorption capacity with kinetics and thermodynamic models. We observe that the high adsorption capacity of Au-CeO₂ is primarily because of the presence of Ce³⁺ states in CeO₂ and citrate ligands on Au NPs. The Ce³⁺ states interact and transfer their electrons to supported Au NPs, rendering a negative charge over Au. The negatively charged Au surface and the carboxyl (-COO^-) group of citrate ligands mediate an electrostatic interaction/adsorption of cationic MB. The total removal of MB is expedited under white light and lasers. A control experiment with Au NPs shows less adsorption-photocatalysis. The size of Au NPs and Au-CeO₂ interfacial interaction is responsible for the surface plasmon resonance spectral position at 550-600 nm. Linear sweep voltammetry (LSV) and plasmonic field simulation show surface plasmon-driven photocatalysis in Au-CeO₂. LSV shows a 3-fold higher photocurrent density in Au-CeO₂ than colloidal Au NPs under white light. The simulated electric field intensity in Au-CeO₂ is maximum at SPR excitation and the closest interfacial separation (d = 0 nm). The plasmon-driven photocatalysis in colloidal Au NPs is mainly due to the interaction of hot electrons with the adsorbed MB molecule. Notably, near-field light concentration, hot electrons, and interfacial charge separation are responsible for excellent MB removal in the Au-CeO₂ nanosystem. The total MB removal through adsorption-photocatalysis pairing is 99.3% (Au-CeO₂), 30.7% (Au NPs), and 13% (CeO₂).

An affordable, handheld multimodal microscopic system with onboard cell morphology and counting features on a mobile device

A simple yet effective, handheld and flexible bright-field and fluorescence microscopic platform on a smartphone with varying optical magnifications is reported for morphological analysis and onboard cell counting features.

Turbidimetric analysis of growth kinetics of bacteria in the laboratory environment using smartphone

For different microbiological and pathological studies, it is often required to monitor the growth of bacteria in a cultured medium in the laboratory environment. UV-VIS spectrophotometer is commonly used to estimate the growth of bacterial cell population by measuring the absorbance at 600 nm over a period of time. Colony-forming unit (CFU) is another approach, which has been routinely performed to estimate the live bacterial cells on semisolid agar plates. Herein, we demonstrate an alternative yet highly reliable sensing platform on a smartphone using which growth kinetics of different bacteria can be reliably monitored. The performance of the proposed smartphone sensor has been compared with the data obtained from OD600 and CFU analysis. A good correlation of bacterial growth rates enumerated based on the proposed smartphone sensor, bench-top spectrophotometer and CFU analysis have been observed under the experimental conditions.

Knowledge and Practice of Nurses on Pediatric Pain Management in Bangladesh

Among nurses due to inadequate pain management knowledge and practice skills, children's pain is often under treated. This study aimed to examine the level of knowledge and practice on pediatric pain management among nurses in Bangladesh. This was a descriptive survey study involving total 150 clinical pediatric nurses from two Medical College Hospital and a University hospital in Bangladesh. The data collection tool consisted of demographic data form, 32-items nurses' knowledge. There were 32 true and false questions related to nurses' knowledge on pediatric pain management in Bangladesh. The response formats to each item for correct answer was 1 and incorrect answer 0. The total scores were categorized into three levels including low (0-20), moderate (21-23) and high (24 and above). The data collection tool consisted of demographic data form, 19-item practice related questionnaire on pediatric pain management. Nurses' practice on pediatric pain management contained 19 items with 5-points Likert's scale ranging from 1=Never practice to 5=constantly practice. For each item, a score of 5 was accorded for constantly and 1 for never. The score ranged from 19-95. The total scores were categorized into three levels including low (19-38), moderate (39-76) and high (77-95). The results demonstrated that most of the nurses' knowledge score on pediatric pain management was at moderate level (mean=21.50, SD=2.35). Nurses' practice on pediatric pain management was also at moderate level (mean=75.45, SD=8.24). The relationship between nurses' knowledge and practice was not significant. In addition, nurses' knowledge and practice with demographic variables; there was significant relationship between nurse's knowledge and existence of pain management protocol, nurses' practice and their current position in unit and with reading nursing journal. This study showed moderate level of knowledge and practice indicating that they need to be enhanced the knowledge and practice skills in pediatric pain management.

Design of a 3D printed smartphone microscopic system with enhanced imaging ability for biomedical applications

Portable, low-cost smartphone platform microscopic systems have emerged as a potential tool for imaging of various micron and submicron scale particles in recent years (Ozcan; Pirnstill and Coté; Breslauer et al.; Zhu et al.). In most of the reported works, it involves either the use of sophisticated optical set-ups along with a high-end computational tool for postprocessing of the captured images, or it requires a high-end configured smartphone to obtain enhanced imaging of the sample. Present work reports the working of a low-cost, field-portable 520× optical microscope using a smartphone. The proposed smartphone microscopic system has been designed by attaching a 3D printed compact optical set-up to the rear camera of a regular smartphone. By using cloud-based services, an image processing algorithm has been developed which can be accessed anytime through a mobile broadband network. Using this facility, the quality of the captured images can be further enhanced, thus obviating the need for dedicated computational tools for postprocessing of the images. With the designed microscopic system, an optical resolution ∼2 µm has been obtained. Upon postprocessing, the resolution of the captured images can be improved further. It is envisioned that with properly designed optical set-up in 3D printer and by developing an image processing application in the cloud, it is possible to obtain a low-cost, user-friendly, field-portable optical microscope on a regular smartphone that performs at par with that of a laboratory-grade microscope. LAY DESCRIPTION: With the ever-improving features both in hardware and software part, smartphone becomes ubiquitous in the modern civilised society with approximately 8.1 billion cell phone users across the world, and ∼40% of them can be considered as smartphones. This technology is undoubtedly the leading technology of the 21st century. Very recently, various researchers across the globe have utilised different sensing components embedded in the smartphone to convert it into a field-portable low-cost and user-friendly tool which can be used for different sensing and imaging purposes. By using simple optical components such as lens, pinhole, diffuser etc. and the camera of the smartphone, various groups have converted the phone into a microscopic imaging system. Again, by removing the camera lenses of the phone, holography images of microscopic particles by directly casting its shadows on the CMOS sensor on the phone has been demonstrated. The holographic images have subsequently been processed using the dedicated computational tool, and the original photos of the samples can be obtained. All the reported smartphone-based microscopic systems either suffer from relatively low field-of-view (FOV), resolution or it needs a high computational platform. Present work, demonstrate an alternative approach by which a reasonably good resolution (<2 µm) along with high optical magnification (520×) and a large FOV (150 µm) has been obtained on a regular smartphone. For postprocessing of the captured images an image processing algorithm has been developed in the cloud and the same can be accessed by the smartphone application, obviating the need of dedicated computational tool and a high-end configured smartphone for the proposed microscope. For the development of the proposed microscopic system, a simple optical set-up has been fabricated in a 3D printer. The set-up houses all the required optical components and the sample specimen with the 3D-printed XY stage, and it can be attached easily to the rear camera of the smartphone. Using the proposed microscopic system, enhanced imaging of USAF target and red blood cells have been successfully demonstrated. With the readily available optical components and a regular smartphone, the net cost involvement is significantly low (less than $250, including the smartphone). We envisioned that the designed system could be utilised for point-of-care diagnosis in resource-poor settings where access to the laboratory facilities is very limited.

Miltefosine Induced Reduced Male Fertility Capacity after Treatment of Post Kala-azar Dermal Leishmaniasis, Bangladesh

Post Kala-azar Dermal Leishmaniasis (PKDL) is the sequel of visceral leishmaniasis in Indian subcontinent and may appear among patients with or without previous history of visceral leishmaniasis (VL). The aim of the study is to understand the male reproductive safety profile of miltefosine used for the treatment of Post Kala-azar Dermal Leishmaniasis (PKDL) in Bangladesh. From January 2017 to March 2017, an exploratory study was carried out on male fertility capacity in Bangladesh among male patients above 14 years old with PKDL treated with miltefosine. Twenty nine male patients were included to observe the effect of miltefosine on reproductive health. All PKDL patients had history of visceral leishmaniasis (VL) in different time periods. Among them three (10.3%) patients were unable to ejaculate semen. In semen analysis, 3 patients (10.3%) were found azoospermia (sperm count & motility- 0, viscosity- good, pH- 7 to 8), microscopically there was presence of RBC (5-15/HPF), WBC (8-15/HPF). Another 3 patients (10.3%) were found oligospermia (sperm count- 4.2 to 15.3 million/ml, motility- 20 to 50%, viscosity- good, pH- 6 to 9, RBC- 4 to 15/HPF, WBC- 4 to 15/HPF). The study documented some important findings in evaluating male infertility and selection of drug regimens in treating PKDL patients with miltefosine for 12 weeks.

Design of a 3D printed compact interferometric system and required phone application for small angular measurements

A 3D printed smartphone based interferometric system is proposed, and its usability has been demonstrated by measuring small angular rotations. All necessary fringe processing and data analysis have been performed within the phone itself using custom designed application developed in an android platform. The main objective of the proposed work is to demonstrate the usability of modern smartphone and 3D printing technology for optical interferometric applications. The smartphone camera has been used to record the interference fringes which has been formed due to the change in the optical path difference (OPD) between light rays reflected from the top and bottom surface of a microscopic glass slide. The angular variation of the slide causes a detectable change in the OPD between the interfering beams which subsequently would cause a variation in the fringe pattern. By evaluating necessary interferometric parameters, small angular rotation can be computed within the smartphone application. With the designed smartphone based interferometric system, angular rotation as small as 0.02° can be measured accurately and reliably having a dynamic range of -3.68° to 3.68°. Due to the involvement of the smartphone as a platform for recording as well as onboard fringe processing, the designed interferometric system can be visualized as a truly field portable tool for different optical metrological applications.

Protein, enzyme and carbohydrate quantification using smartphone through colorimetric digitization technique

In this paper the utilization of smartphone as a detection platform for colorimetric quantification of biological macromolecules has been demonstrated. Using V-channel of HSV color space, the quantification of BSA protein, catalase enzyme and carbohydrate (using D-glucose) have been successfully investigated. A custom designed android application has been developed for estimating the total concentration of biological macromolecules. The results have been compared with that of a standard spectrophotometer which is generally used for colorimetric quantification in laboratory settings by measuring its absorbance at a specific wavelength. The results obtained with the designed sensor is found to be similar when compared with the spectrophotometer data. The designed sensor is low cost, robust and we envision that it could promote diverse fields of bio-analytical investigations. Schematic illustration of the smartphone sensing mechanism for colorimetric analysis of biomolecular samples.

Purification and development of ELISAs for two forms of vitellogenin in Indian walking catfish, Clarias batrachus (L.)

Two forms of vitellogenin (Vg: Vg1 and Vg2) were purified from the plasma of estradiol-17β (E₂)-treated Indian walking catfish, Clarias batrachus, by gel filtration and adsorption chromatography. Native Vg1 and Vg2 had apparent molecular masses of 375 and 450 kDa, respectively, and both Vgs resolved into two similar major bands (95 and 67 kDa) in SDS-PAGE under reducing condition. Polyclonal antisera raised against each form of Vg were absorbed with a combination of hypophysectomized male catfish serum proteins and alternate Vg to ensure specificity. Immunological analyses verified the presence of Vg1 and Vg2 in the plasma of female catfish. Homologous ELISAs were developed for Vg1 and Vg2 using their respective harvested antisera, which exhibited the detection limit of 100 ng ml^-1 for Vg1 and 40 ng ml^-1 for Vg2, and low level of cross-reactivity (not parallel to the standard) was found with alternate Vg in each assay. Treatment of male catfish with E₂ induced both Vgs showing a proportionate ratio of Vg1 to Vg2 at 5.6:1. Plasma concentrations of both Vgs measured by ELISAs at different reproductive phases of field collected female catfish increased in accordance with the ovarian development, keeping the proportionate ratio of Vg1 to Vg2 at about 2:1 in fish undergoing vitellogenesis during prespawning period and 1:20 during spawning period, suggesting that Vg1 may be the major Vg to contribute in yolk formation, whereas Vg2, besides its role in yolk formation, may facilitate other physiological functions. The present study, thus, demonstrates the occurrence of two unequally synthesized Vgs in the catfish.

Low-Cost, Robust, and Field Portable Smartphone Platform Photometric Sensor for Fluoride Level Detection in Drinking Water

Groundwater is the major source of drinking water for people living in rural areas of India. Pollutants such as fluoride in groundwater may be present in much higher concentration than the permissible limit. Fluoride does not give any visible coloration to water, and hence, no effort is made to remove or reduce the concentration of this chemical present in drinking water. This may lead to a serious health hazard for those people taking groundwater as their primary source of drinking water. Sophisticated laboratory grade tools such as ion selective electrodes (ISE) and portable spectrophotometers are commercially available for in-field detection of fluoride level in drinking water. However, such tools are generally expensive and require expertise to handle. In this paper, we demonstrate the working of a low cost, robust, and field portable smartphone platform fluoride sensor that can detect and analyze fluoride concentration level in drinking water. For development of the proposed sensor, we utilize the ambient light sensor (ALS) of the smartphone as light intensity detector and its LED flash light as an optical source. An android application "FSense" has been developed which can detect and analyze the fluoride concentration level in water samples. The custom developed application can be used for sharing of in-field sensing data from any remote location to the central water quality monitoring station. We envision that the proposed sensing technique could be useful for initiating a fluoride removal program undertaken by governmental and nongovernmental organizations here in India.

Smartphone based LSPR sensing platform for bio-conjugation detection and quantification

Localized surface plasmon resonance based sensing and biosensing has been performed using the camera of a smartphone.

Water turbidity sensing using a smartphone

Smartphone based platform turbidimeter measuring turbidity in drinking and different environmental water bodies.

Smartphone-based platform optical setup measuring π/256 optical phase difference in an interference process

Utilizing the camera of a smartphone and simple laboratory optical components, we demonstrate an optical technique that measures an optical phase difference (OPD) of π/256 in an interference process. We develop a compact optical setup for viewing circular interference fringe patterns through the camera of the smartphone. By introducing OPD between the interfering beams, variation in fringe pattern is recorded using the smartphone camera. We envision that the proposed optical setup could emerge as an ultrasensitive optical tool for measurement of inclination of a given surface.

Musculoskeletal disorder (MSD) among agricultural workers

Farming is a large and main industry in Bangladesh. Large numbers of people are directly involved in farming and have very unique exposure compare to other sectors. Musculoskeletal problems among farmer population are not infrequent. This study was carried out among 200 farmers in one selected district. The study revealed that musculoskeletal problems were common among the farmers working in a traditional way. All the respondents were male. The age of all respondents lie between 20-60 years. Among them 22.5% farmers were illiterate, about 45.5% below Class V. About half (42%) of the respondents had reported pain in different parts of the body at least one or more times during working in land. And about two third (65.5%) of the farmers had history of joint pain and stiffness in last 12 month. Most of the farmers who suffered from musculoskeletal symptoms were 41-60 years. Specially who worked more then 20 years (82.6%) and average 6 hours per day (66.7%). The occurrence of musculoskeletal problems in various part of the body included Knee pain - 48.1%, Back pain (back ache) - 22.9%, Waist pain (low back ache) - 13.3%, Neck pain - 18.3% and shoulder pain - 10.7%. Length of work in year and daily average working hours were found significant association with musculoskeletal pain. It was found that musculoskeletal pain were more common among the farmers when they worked in squatting position (52%) and specially during weeding of plants (31%). Among them only 22% also engaged in other business. Most of the farmers complained dull aching pain (40.6%), only 2.3% noticed severe acute pain, but about 86% farmers' temporary stop their work for pain and 80% get relief after discontinue of work. About 75% respondents visited doctors for their pain which was statistically significant (p=0.001). It was found that the rates of musculoskeletal complaints are more among those individuals who worked relatively bad ergonomic condition, such as body position probably play an important role.

Label-free biodetection using a smartphone

Utilizing its integrated camera as a spectrometer, we demonstrate the use of a smartphone as the detection instrument for a label-free photonic crystal biosensor. A custom-designed cradle holds the smartphone in fixed alignment with optical components, allowing for accurate and repeatable measurements of shifts in the resonant wavelength of the sensor. Externally provided broadband light incident upon an entrance pinhole is subsequently collimated and linearly polarized before passing through the biosensor, which resonantly reflects only a narrow band of wavelengths. A diffraction grating spreads the remaining wavelengths over the camera's pixels to display a high resolution transmission spectrum. The photonic crystal biosensor is fabricated on a plastic substrate and attached to a standard glass microscope slide that can easily be removed and replaced within the optical path. A custom software app was developed to convert the camera images into the photonic crystal transmission spectrum in the visible wavelength range, including curve-fitting analysis that computes the photonic crystal resonant wavelength with 0.009 nm accuracy. We demonstrate the functionality of the system through detection of an immobilized protein monolayer, and selective detection of concentration-dependent antibody binding to a functionalized photonic crystal. We envision the capability for an inexpensive, handheld biosensor instrument with web connectivity to enable point-of-care sensing in environments that have not been practical previously.

Status of blood pressure among individuals consuming saline water

Climate change is taking its toll in the form of saline water intrusion into the mainland of Bangladesh, which is one of the lowest-altitude countries in the world. The study was carried out with the objective to assess the blood pressure status associated with salinity in saline prone selected areas of Bagherhat and Tangail districts from March 2008 - June 2008 of rural Bangladesh. Two hundred and ninety subjects were selected purposively from both the districts. About 70% of the respondents were males and below forty years of age. More than two thirds of the respondents were illiterate; belong to 4-5 member family, with monthly family income of less than Tk. 4000 per month. Only one third of the respondents were smokers. More than two thirds of the respondents from salinity area had salinity level of 2-3%. Among them majority were drinking saline water for 6-10 years and 26% were drinking for more than ten years. About 20% of the non saline respondents' systolic blood pressure was 110-120 mm of Hg and 26% of saline area had systolic blood pressure >135-140 mm of Hg. Mean systolic BP among salinity area was more than that for non salinity area. About 19% of the non saline respondents' diastolic blood pressure was ≤ 85 mm of Hg. About one third had ≥ 90 mm of Hg, among them 31% were from saline area. Mean diastolic BP among salinity area was more than non salinity area. There was no history of heart disease, and less than 1% was diabetic among them. About two thirds had mean arterial pressure <70 mm of Hg, among them majority were from non saline area. About one third had >70 mm of Hg, among them majority were from saline area. The study concluded that systolic and diastolic blood pressures of saline group were significantly higher than that of the non saline group.

Cervical mediastinoscopy: re-evaluation of an old technique in era of new imaging technology

CONTEXT

With the advent of modern anatomical and functional imaging technologies, application of cervical mediastinoscopy has decreased in diagnosis and staging of mediastinal diseases.

AIM

To evaluate the usefulness of cervical mediastinoscopy in assessing the mediastinal disease when imaging modalities are non-diagnostic.

SETTINGS AND DESIGN

Retrospective analysis of records of a tertiary care hospital.

PATIENTS AND METHODS

Thirty-nine patients with mediastinal pathology of varied aetiologies underwent cervical mediastinoscopy. Pre- and post-operative diagnosis was compared.

RESULTS

In 34 out of 39 cases (87.5%), cervical mediastinoscopy provided a confirmatory final diagnosis. One case had a major complication in the form of recurrent laryngeal nerve palsy.

CONCLUSION

Cervical mediastinoscopy is useful, minimally invasive modality in a scenario where anatomical and functional imaging tools are non-diagnostic.

Fiber-optic liquid level sensor based on coupling optical path length variation

The concept for a new and simple fiber-optic liquid level sensor is presented and experimental results are shown to demonstrate the principle. The sensing principle is based on light intensity modulation when rising and falling mode of liquid level causes coupling optical path distance variation between two optical fibers. Near continuous mode of liquid level variation could be monitored with resolution as low as 1 mm can be measured in the length scale of 25 cm.

Magnetic Resonance Relaxometry at Low and Ultra low Fields

Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) are ubiquitous tools in science and medicine. NMR provides powerful probes of local and macromolecular chemical structure and dynamics. Recently it has become possible and practical to perform MR at very low fields (from 1 μT to 1 mT), the so-called ultra-low field (ULF) regime. Pulsed pre-polarizing fields greatly enhance the signal strength and allow flexibility in signal acquisition sequences. Improvements in SQUID sensor technology allow ultra-sensitive detection in a pulsed field environment.In this regime the proton Larmor frequencies (1 Hz - 100 kHz) of ULF MR overlap (on a time scale of 10 μs to 100 ms) with "slow" molecular dynamic processes such as diffusion, intra-molecular motion, chemical reactions, and biological processes such as protein folding, catalysis and ligand binding. The frequency dependence of relaxation at ultra-low fields may provide a probe for biomolecular dynamics on the millisecond timescale (protein folding and aggregation, conformational motions of enzymes, binding and structural fluctuations of coupled domains in allosteric mechanisms) relevant to host-pathogen interactions, biofuels, and biomediation. Also this resonance-enhanced coupling at ULF can greatly enhance contrast in medical applications of ULF-MRI resulting in better diagnostic techniques.We have developed a number of instruments and techniques to study relaxation vs. frequency at the ULF regime. Details of the techniques and results are presented.Ultra-low field methods are already being applied at LANL in brain imaging, and detection of liquid explosives at airports. However, the potential power of ultra-low field MR remains to be fully exploited.

Clinical heterogeneity and genotype-phenotype correlations in hereditary spastic paraplegia because of Spatacsin mutations (SPG11)

BACKGROUND

Autosomal recessive hereditary spastic paraplegia (ARHSP) with thin corpus callosum is a distinct and usually severe form of complex hereditary spastic paraplegia classified as SPG11. Recently mutations on SPG11 gene (KIAA1840), which is localized to chromosome 15q13-q15, were shown to cause the majority of SPG11 cases.

METHODS

We analysed the 40 coding exons of this gene in the probands from eight families with complex ARHSP, four of these families had a thin corpus callosum and two has mild thinning.

RESULTS

Three families were identified with novel mutations in the SPG11 gene. One family was of Asian origin with a homozygous nonsense mutation and had a very severe phenotype but only very mild thinning of the corpus callosum. In the other two English families the parents were unrelated and the mutations were compound heterozygotes. In these two families the phenotype was mild and both probands had a thin corpus callosum.

CONCLUSION

Given the probable mechanism of action of the mutations in the Spatacsin gene, we discuss the probable genotype phenotype correlations in these families. This study confirms the frequent occurrence of Spatacsin mutations in complex ARHSP with genotype phenotype effects and exposes the spectrum of clinical heterogeneity in SPG11.

Modulation of ozone-induced airway hyperresponsiveness and inflammation by interleukin-13

The present study aimed to determine whether the T-helper cell type 2-derived cytokines, interleukin (IL)-4 and -13, can modulate the lung response to ozone exposure. IL-13(-/-), IL-4/13(-/-) and IL-13-overexpressing transgenic (Tg) mice were exposed to ozone (3 ppm; 3 h) or air. Wild-type (Wt) Balb/c mice and transgenic-negative littermates (IL-13Wt) were used as controls for gene-deficient and IL-13Tg mice, respectively. IL-4/13(-/-) and IL-13(-/-) mice developed a lesser degree of ozone-induced airway hyperresponsiveness (AHR) while IL-13Tg mice developed a greater degree of AHR compared with ozone-exposed wild-type or IL-13Wt mice, respectively. Ozone caused a time-dependent increase of bronchoalveolar lavage (BAL) neutrophils and macrophages in wild-type mice, maximal at 20-24 h, which was attenuated in the IL-13(-/-) and IL-4/13(-/-) mice. In IL-13Tg mice, there was a greater increase in BAL neutrophils after ozone exposure compared with IL-13Wt mice. Using quantitative real-time PCR, ozone-induced mRNA expression for IL-6 and keratinocyte chemokine was further enhanced in IL-13(-/-) and IL-4/13(-/-) mice, and was inhibited in IL-13Tg mice. Macrophage inflammatory protein (MIP)-3alpha/CCL20 expression was enhanced after ozone exposure in wild-type mice, inhibited in IL-13(-/-) and IL-4/13(-/-) mice, while in IL-13Tg mice it was enhanced. A similar pattern of expression was observed with lipopolysaccharide-induced cytokine (LIX/CXCL5/ENA-78) expression. In conclusion, interleukin-13 augments ozone-induced airway hyperresponsiveness and neutrophilic inflammation, possibly through modulation of certain cytokines induced by ozone exposure.

Resolution of allergic airways inflammation but persistence of airway smooth muscle proliferation after repeated allergen exposures

BACKGROUND

Chronic inflammation in asthmatic airways can lead to characteristic airway smooth muscle (ASM) thickening and pathological changes within the airway wall.

OBJECTIVE

We investigated the long-term effects of repeated allergen exposure.

METHODS

Brown-Norway (BN) rats sensitized to ovalbumin (OVA) were exposed to OVA or saline aerosol every third day on six occasions and studied 24 h, 7 days and 35 days after the final exposure. We measured airway inflammation, ASM cell proliferation (by incorporation of bromodeoxyuridine; BrdU) and bronchial responsiveness to acetylcholine.

RESULTS

At 24 h, in OVA-exposed rats, we detected elevated OVA-specific serum IgE, increased numbers of macrophages, eosinophils, lymphocytes and neutrophils in the bronchoalveolar lavage (BAL) fluid and increased numbers of MBP+ (major basic protein) eosinophils and CD2+ T cells within the bronchial submucosa. This coincided with increased numbers of ASM cells expressing BrdU and with bronchial hyper-responsiveness (BHR). At 7 days, BHR was detected in OVA-exposed rats, coincident with increased numbers of macrophages and lymphocytes in BAL fluid together with increased numbers of CD2+ T cells within the bronchial submucosa. This coincided with increased numbers of ASM cells expressing BrdU. By day 35, the number of ASM cells expressing BrdU remained elevated in the absence of cellular infiltration and BHR.

CONCLUSION

Repeated OVA-challenge results in persistent ASM cell proliferation in the absence of bronchial inflammation and BHR, which lasts for at least 1 week following cessation of exposure.

A comprehensive system for protein purification and biochemical analysis based on antibodies to c-myc peptide

The genomics revolution has created a need for increased speed and generality for recombinant protein production systems as well as general methods for conducting biochemical assays with the purified protein products. 9E10 is a well-known high-affinity antibody that has found use in a wide variety of biochemical assays. Here we present a standardized system for purifying proteins with a simple epitope tag based on c-myc peptide using an antibody affinity column. Antibodies with binding parameters suitable for protein purification have been generated and characterized. To purify these antibodies from serum-containing medium without carrying through contaminating immunoglobulin G, a peptide-based purification process was developed. A fluorescence polarization binding assay was developed to characterize the antigen-antibody interaction. Protein purification protocols were optimized using a fluorescein-labeled peptide as a surrogate "protein." Binding and elution parameters were evaluated and optimized and basic operating conditions were defined. Several examples using this procedure for the purification of recombinant proteins are presented demonstrating the generality of the system. In all cases tested, highly pure final products are obtained in good yields. The combination of the antibodies described here and 9E10 allow for almost any biochemical application to be utilized with a single simple peptide tag.

Role of two plasma vitellogenins from Indian major carp (Cirrhinus mrigala) in catfish (Clarias batrachus) vitellogenesis

Complete vitellogenesis (synthesis and incorporation of vitellogenin, Vg) in the female catfish, Clarias batrachus, during different reproductive phases (preparatory, prespawning, and postspawning) of its annual ovarian cycle is induced by administering heterologous Vg (semipurified; ULT-I and purified; HA-I and HA-II) isolated from the Indian major carp, mrigal (Cirrhinus mrigala). During the prespawning period, ULT-I, which contains both HA-I and HA-II, showed a dose-dependent response in relation to the induction of complete vitellogenesis in female catfish. In the preparatory period, daily treatment with 1 mg of ULT-I for 12 days resulted in an increase in plasma Vg level, ovarian weight, and number of stage-II (vitellogenic) oocytes along with the appearance of stage III (fully formed) yolky oocytes. In the prespawning period, 12-day administration of HA-I at the dose level of 0.5 mg/fish/day enhanced complete vitellogenesis in intact female catfish and induced Vg synthesis in hypophysectomized female catfish, whereas HA-II, at the same dose level, could only stimulate Vg synthesis, indicating their different roles during vitellogenesis. The results so far obtained may be due to the estradiol-17beta contamination in the Vg fractions. Estimation of E(2) in ULT-I, HA-I, and HA-II by E(2) ELISA indicates that HA-II contains only a small amount (106 pg/mg protein). Therefore, daily treatment with 1 mg each of delipidated ULT-I and HA-I for 12 days could synthesize very little Vg, whereas intact ULT-I at the same dose level induced not only a high plasma Vg level but also increased GSI, indicating the importance of lipid in the native molecule for the induction of vitellogenesis. During postspawning period, administration of HA-I (0.5 mg/fish/day for 21 days) to reproductively regressed female catfish pretreated with HA-II (10 microg/fish/day for 7 days) and maintained at a long photoperiod (LD 14:10) and high temperature (30 degrees ), induced complete vitellogenesis.