Investigation of SPR and electrochemical detection of antigen with polypyrrole functionalized by biotinylated single-chain antibody: a review.

An electrochemical label-free immunosensor based on a biotinylated single-chain variable fragment (Sc-Fv) antibody immobilized on copolypyrrole film is described. An efficient immunosensor device formed by immobilization of a biotinylated single-chain antibody on an electropolymerized copolymer film of polypyrrole using biotin/streptavidin system has been demonstrated for the first time. The response of the biosensor toward antigen detection was monitored by surface plasmon resonance (SPR) and electrochemical analysis of the polypyrrole response by differential pulse voltammetry (DPV). The composition of the copolymer formed from a mixture of pyrrole (py) as spacer and a pyrrole bearing a N-hydroxyphthalimidyl ester group on its 3-position (pyNHP), acting as agent linker for biomolecule immobilization, was optimized for an efficient immunosensor device. The ratio of py:pyNHP for copolymer formation was studied with respect to the antibody immobilization and antigen detection. SPR was employed to monitor in real time the electropolymerization process as well as the step-by-step construction of the biosensor. FT-IR demonstrates the chemical copolymer composition and the efficiency of the covalent attachment of biomolecules. The film morphology was analyzed by electron scanning microscopy (SEM). Results show that a well organized layer is obtained after Sc-Fv antibody immobilization thanks to the copolymer composition defined with optimized pyrrole and functionalized pyrrole leading to high and intense redox signal of the polypyrrole layer obtained by the DPV method. Detection of specific antigen was demonstrated by both SPR and DPV, and a low concentration of 1 pg mL(-1) was detected by measuring the variation of the redox signal of polypyrrole.

Effect of the size of electrode on electrochemical properties of ferrocene-functionalized polypyrrole towards DNA sensing.

A simple and highly sensitive electrochemical DNA sensor based on a ferrocene-functionalized polypyrrole has been prepared on a microelectrode array substrate for a multi-DNA detection chip format. A copolymer formed with 1-(phthalimidylbutanoate)-1'-(N-(3-butylpyrrole)butanamide)ferrocene (Py-Fe-NHP) and pyrrole was electrocopolymerized on the gold surface of both macroelectrode and biochip formats. DNA probes bearing an amino group were covalently grafted by substitution of NHP groups and the hybridization reaction was followed by monitoring the redox signal of the ferrocenyl group acting as the probe. The integration of the polymers into chip format produces high-density arrays of individually addressable oligonucleotide microelectrodes. Results show that reducing the size of the electrodes from a macroelectrode to the chip format allows a variation of the nucleation and the growth process during electropolymerization of modified pyrrole monomers. These modifications enable an increase in the sensitivity and selectivity of DNA hybridization.

Exposure to a First World War blistering agent.

Sulfur mustards act as vesicants and alkylating agents. They have been used as chemical warfare since 1917 during the first world war. This brief report illustrates the progression of injury on a primary exposed patient to a first world war blistering agent. This case documents the rapid timeline and progression of symptoms. It emphasises the importance of appropriate personal protective equipment and immediate medical response plan with rapid decontamination and proper action from military and civilian medical treatment facilities. This case reports the first US active duty military exposure to a blistering agent in the age of global terrorism.

Preventing drug-resistant tuberculosis with a fixed dose combination of isoniazid and rifampin.

SETTING: Los Angeles County Department of Health Services. OBJECTIVE: To determine how well a self-administered fixed dose combination of isoniazid and rifampin (CombinedHR) prevents acquired drug resistance to Mycobacterium tuberculosis despite treatment interruptions. DESIGN: Self-administered CombinedHR was given to approximately 75% of patients and directly observed therapy or separate drugs to 25%. Three quarters of the patients completed the prescribed treatment. We determined 1) how many patients had two drug-susceptible cultures 3 or more months apart as a measure of drug-susceptible failure or relapse, 2) how many patients whose initial culture was drug-susceptible had a subsequent drug-resistant culture as a measure of acquired drug resistance, and 3) what treatment regimen was taken by each patient who developed acquired drug resistance. RESULTS: Among 5337 drug-susceptible tuberculosis patients who were known or presumed to be human immunodeficiency virus (HIV) negative, 152 (2.84%) treatment failures or relapses occurred, of which 25 (0.47%) developed acquired drug resistance. Among approximately 4000 cases taking CombinedHR and primarily CombinedHR, drug resistance occurred in only eight cases (0.2%), and a total of 12 cases (0.3%) when patients with indeterminate treatment histories were added. CONCLUSIONS: Treatment with self-administered CombinedHR results in minimal acquired drug resistance in HIV-seronegative tuberculosis cases despite modest rates of incomplete treatment.

Multi-wavelength mid-infrared micro-spectral imaging using semiconductor lasers.

Infrared (IR, 3-12-microm) microscopic spectral imaging is an important analytical technique. Many current instruments employ thermal IR light sources, which suffer the problem of low brightness and high noise. This paper evaluates the system engineering merit in using semiconductor lasers, which offer orders-of-magnitude-higher power, brightness, and lower noise. A microscopic spectral imaging system using semiconductor lasers (quantum cascade) as illuminators, and focal plane array detectors demonstrated a high signal-to-noise ratio (> 20 dB) at video frame rate for a large illuminated area. The comparative advantages of laser vs. thermal light source are analyzed and demonstrated. Microscopic spectral imaging with fixed-wavelength and tunable lasers of 4.6-, 5.1-, 6-, and 9.3-microm wavelength was applied to a number of representative samples that consist of biological tissues (plant and animal), solid material (a stack of laminated polymers), and liquid chemical (benzene). Transmission spectral images with approximately 30-dB dynamic range were obtained with clear evidence of spectral features for different samples. The potential of more advanced systems with a wide coverage of spectral bands is discussed.

Pathway across blood-brain barrier opened by the bradykinin agonist, RMP-7.

The route taken by lanthanum (MW 139) across cerebral endothelium was delineated when the blood-brain barrier was opened by RMP-7, a novel bradykinin agonist. Balb C mice were infused through a jugular vein with LaCl3 with or without RMP-7 (5 micrograms/kg). Ten minutes later, the brains were fixed with aldehydes and processed for electron microscopy. The patency of the junctions between endothelial cells was estimated by counting the number of junctions penetrated by LaCl3. Tracer penetrated the junctions in about 25% of microvessels in vehicle infused, control mice and about 58% in the RMP-7 group, where more junctions per vessel were also penetrated. The LaCl3 then penetrated the basal lamina in about 20% of all microvessels in the RMP-7 group, versus 0.50% in the control group. From the basal lamina, the tracer entered perivascular spaces in about 13% of all microvessels in the RMP-7 group and about 0.07% in the controls. Very few endocytic pits or vesicles in the RMP-7 group were labeled, so LaCl3 did not cross endothelium by transcytosis. The increased number of tight junctions penetrated by tracer and its spread into periendothelial basal lamina and interstitial clefts indicated, therefore, a paracellular route of exudation in the RMP-7 treated animals.

Tuberculosis in patients with HIV infection.

Tuberculosis is the most common opportunistic infection in patients with HIV infection worldwide and is the only one that is transmissible to others by the respiratory route. Tuberculosis is curable and preventable. Early detection of tuberculosis disease and infection in individuals with or at risk for HIV infection is paramount. This approach can minimize the devastating interaction between these two diseases.

Drug treatment of tuberculosis--1992.

The impact of the acquired immunodeficiency syndrome (AIDS) pandemic has made tuberculosis an increasing worldwide problem, and the effectiveness of modern chemotherapy has been blunted by the high incidence of primary drug resistance, especially in developing countries. The prospect of finding new and highly effective drugs similar to isoniazid or rifampicin is dim, yet the maximum benefits from the existing drugs which are highly effective have not been received. A 6-month regimen of isoniazid plus rifampicin, supplemented by pyrazinamide during the first 2 months, for treatment of uncomplicated tuberculosis is highly effective and the regimen of choice. Ethambutol should be added if the risk of isoniazid resistance is increased. A regimen of isoniazid, rifampicin, pyrazinamide and streptomycin for 4 months provides effective defence against smear-negative pulmonary tuberculosis. Re-treatment of multiple drug-resistant tuberculosis remains a difficult therapeutic problem. At least 3 drugs that the patient has never previously received, and that are effective according to laboratory susceptibility testing, must be used. Preventive therapy against tuberculosis is accomplished with isoniazid for 6 to 12 months, although rifampicin plus isoniazid for 3 months has been used in the United Kingdom with success. In a mouse model, rifampicin plus pyrazinamide for 2 months is more effective than isoniazid for 6 months as preventive treatment. Patient noncompliance with medication remains the biggest problem in tuberculosis control, and is a complex issue. It can only be resolved by multiple approaches. Intermittent directly observed short course chemotherapy is a major, but not the only, possible solution.

Ultrafast, room-temperature, resonance-enhanced third-order optical susceptibility tensor of an AlGaAs/GaAs quantum well.

The ultrafast, room-temperature, resonance-enhanced third-order nonlinear susceptibility tensor of an AlGaAs/ GaAs quantum well is determined. A single 6-nm GaAs quantum well embedded in a waveguide of 382-nm mode size increases the |chi((3))| from a bulk-material level of 8 x 10(-11) esu +/-20% to 6 x 10(-10) esu +/-20%. The anisotropy of the diagonal elements |chi((3))(1111), |chi((3))(2222)| and their correlation with the off-diagonal elements |chi((3))(1212)|, |chi((3))(2121)| are consistent with the one-photon resonance mechanism.

Measurement of third-order optical nonlinear susceptibility using four-wave mixing in a single-mode ridge waveguide.

Nondegenerate four-wave mixing in a single-mode ridge waveguide has been demonstrated as a technique for simultaneous measurement of the imaginary component and the absolute magnitude of the third-order nonlinear susceptibility chi((3)). In the same experimenal apparatus, Im chi((3))(omega(2) = omega(1) + omega(2) - omega(1)) was obtained by measuring the pump-induced probe power loss and |chi((3))(omega(3) = omega(1) + omega(1) - omega(2))| was derived from Stokes wave generation efficiency. The ratio of these quantities was obtained without significant system uncertainties. The technique has been applied to AlGaAs/GaAs quantum-well waveguides with picosecond laser pulses. For homega(1) approximately homega(2) approximately 1.43 eV, it was found that Im chi((3)) = (6.1 +/- 0.5) x 10(-11) esu, |chi((3))| = (7.6 +/- 1.7) x 10(-11) esu with a system uncertainty of 25%, and Im chi((3))/|chi((3))| = 0.8 +/- 31%, indicating the dominance of two-photon absorption.

Optical nonlinearities in Al(x)Ga(1-x)As/GaAs asymmetric coupled quantum wells.

Optical nonlinearities of Al(x)Ga(1-x)As/GaAs asymmetric coupled quantum wells within a p-i-n structure have been observed by using time-resolved spectroscopy. Under photoexcitation, exciton absorption lines exhibit spectral shifts of as much as approximately 1 meV. The recovery times of these spectral shifts are of the order of hundreds of picoseconds when the excitation photon is above the lowest exciton state but become less than 10 psec when excitation is below the lowest exciton state, indicating a virtual process. The behavior of these spectral shifts is consistent with the presence of a polarization induced by optical pumping. The polarization is believed to be due to the excitons that have nonvanishing electric dipole moments along the axis of the asymmetric coupled quantum wells.

Burns in patients under 2 and over 70 years of age.

A total of 246 consecutive burn patients younger than 2 years and older than 70 years of age admitted to a burn center were reviewed retrospectively to study morbidity and mortality specific to these two age groups. Of these patients, 165 were less than 2 years of age and 81 were over 70 years of age, representing 16% and 8% of the total patient population respectively. In patients under 2, scald burns occurred in 127 (77%) and flame burns in 18 (11%). In patients over 70, flame was the most common burn mechanism, occurring in 64 (79%) patients, while scalds occurred in 12 (15%). The mean total body surface area (TBSA) burned in the younger age group was 13.2% (2.4% full thickness, 10.8% partial thickness) and in the older age group was 25% (12.8% full thickness, 12.2% partial thickness). Only 1 death occurred in the younger age group (0.6% mortality), while 41 deaths occurred in the older age group (50.6% mortality). If the burn involved a total body surface area greater than 40%, all patients died (100% mortality). A total of 36 complications occurred in the younger age group (0.2 complications per patient) and 111 in the older age group (1.4 per patient). Burn wound sepsis was the most common complication in each group, occurring in 28 patients under 2 and 42 elderly patients, and was responsible for the 1 death in the younger age group. Although burn wound sepsis was the most common complication in those patients over 70, cardiovascular and pulmonary complications were the most deadly, accounting for 68% (28 patients) of total deaths in this group.

Changes in blood flow and metabolism in a neurovascular island skin flap after a burn.

In 8 male white Yorkshire pigs weighing approximately 42 kg each, 12 buttock neurovascular island skin flaps were dissected. Baseline recordings were made of blood flow and O2 consumption in the flap. Two series of experiments were carried out. In control animals (5), the flap was dissected and the "cold" aluminum plate was applied for 10 seconds. In the burned flaps (7) a contact burn of 2.68 calories/cm2 was created with a heated aluminium plate applied to the skin for 10 seconds. After this the flaps were studied for 4 hours. In the control flaps, blood flow and O2 consumption did not change. The burned flaps showed no change in blood flow, while O2 consumption increased significantly from .07 +/- .01 (SE) ml/100 g/min to .18 +/- .08 (SE) ml/100 g/min (p less than .05).