Use of multivariate statistical methods to identify immunochemical cross‐reactants

Quantitative competition immunoassays with appropriate combinations of antibodies give consistent dose‐response patterns which may be used to identify and estimate amounts of cross‐reacting compounds. Previously reported methods of analyzing cross‐reaction patterns include multiple regression, principal components analysis and minimum estimates of variance (MEV). Four other techniques which are preferable in theory have been surveyed: discriminant analysis (DA), maximum likelihood estimates (MLE), classification and regression trees (CART), and computational neural networks (NN). MLE and simple back‐propagation neural networks can estimate the concentration, as well as the identity, of individual compounds. These four methods worked well with unfitted, unscaled data from monoclonal assays of triazines, phenylureas and avermectins. Immunoassays must be properly designed to provide adequate data for pattern recognition. Cross‐reactivity pattern analysis will make multi‐analyte, multi‐antibody immunoassays feasible for many applications in toxicology and hazard assessment.     

Role of primary photoacceptors in low-power laser effects: action of He-Ne laser radiation on bacteriophage T4-Escherichia coli interaction

The effect of He-Ne laser radiation (lambda = 632.8 nm) on bacteriophage T4-Escherichia coli WP2 interactions was studied. Irradiation of bacteria having respiratory chain components as primary photoacceptors accelerated their division in a dose-dependent manner, but irradiation had no effect on the properties of the phage (measured as its ability to infect host cells). At the same time, exposure of bacteria to stimulating doses of He-Ne laser radiation (from 10(3) to 6 x 10(4) J/m2) increased their ability to promote the growth of unexposed phages. These results clearly indicate that low-power laser effects require primary photoacceptors (phage contains no chromophores for red light).     

Purification and Properties of the γ-Protein Specified by Bacteriophage λ: An Inhibitor of the Host RecBC Recombination Enzyme

Previous experiments have indicated that the gam gene of bacteriophage lambda is responsible for an inhibition of the RecBC DNase-an enzyme that is essential for the major host pathway of genetic recombination. We report here experiments that define the inhibitor as the protein product of the gam gene ("gamma-protein") and that characterize the inhibition reaction with highly purified preparations of gamma-protein and RecBC DNase. Genetic characterization was performed with partially purified fractions prepared from cells infected with various lambda mutants. An activity that inhibits RecBC DNase was absent in extracts prepared after infection by phage that carry nonsense or deletion mutations in the gam gene; this activity was highly thermolabile in an extract prepared after infection by phage that carry a temperature-sensitive mutation in the gam gene. For biochemical characterization, the gamma-protein has been purified more than 800-fold. This highly purified preparation inhibited all of the known catalytic activities associated with the RecBC enzyme, but exhibited no detectable DNase or ATPase activities by itself. These findings are discussed in terms of their implications for regulation of genetic recombination and bacteriophage lambda development.     

Prediction of the ability of clozapine to treat negative symptoms from plasma glycine and serine levels in schizophrenia

We previously reported that plasma levels of glycine, a co-agonist at N-methyl-D-asparate (NMDA)-type glutamate receptors, are decreased in patients with schizophrenia, and that glycine levels are negatively correlated with negative symptoms. The aim of the present study was to determine if glycine, or its ratio to serine, a precursor of glycine, predicts change in negative symptoms in subjects with schizophrenia during treatment with clozapine, an atypical antipsychotic drug with multiple effects on glutamatergic activity. Plasma levels of glycine, serine, and their ratio, were measured in 44 patients with schizophrenia who were subsequently treated with clozapine. Baseline glycine levels or glycine/serine ratios predicted the Scale for the Assessment of Negative Symptoms - Sum of the Global Scales and Avolition-Apathy after 6 wk of clozapine treatment. These results indicate the association of these amino acid measures with response to clozapine in terms of negative symptoms in patients with schizophrenia.     

Surgical repair of recurrent hiatal hernia

The surgical management results of recurrent hiatal hernia repair are unknown in the laparoscopic era. The experience of the senior authors (CJF) and (SKM) is reported herein. From 1993 to 2004, 52 patients underwent re-operative hiatal hernia surgery at our center. Preoperative symptoms were heartburn, chest pain, dysphagia, regurgitation and pulmonary manifestations of gastroesophageal reflux disease. Patients had preoperative evaluation by upper endoscopy, pH-monitoring, esophagogram and manometry to assess the mechanism of failure. Pre- and postoperative symptoms were assessed utilizing a standardized questionnaire. Patients underwent laparoscopic repair (n=18), open laparotomy (n=6) and transthoracic surgery (n=28). Ninety-five percent follow-up was achieved with a mean follow-up of 34 months. Thirty-seven percent of patients encountered para-operative complications one of them died due to respiratory insufficiency. Five patients experienced a re-recurrent hernia. The symptom resolution was 65% for dysphagia, 68% for heartburn, 95% for chest pain and 79% for regurgitation. The overall patient satisfaction was 6.94 on a scale of 1–10. There was no significant difference in patient outcome when comparing the operative approaches or disease process. Surgical repair of recurrent hiatal hernias is safe and effective. Laparoscopic surgery is an appropriate alternative approach for recurrent hiatal hernia repair in selected patients.     

He-Ne laser irradiation of single identified neurons.

Silent (LPa2 and LPa3) and spontaneously active (V3, V5, V17) neurons of subesophageal ganglia of Helix pomatia were irradiated via a 125-mm fiber probe with a 10-mW He-Ne laser (lambda = 632.8 nm), and the rate of membrane depolarization, duration of latent period, and probability of spike activity were measured as the functions of light intensity. It was found that silent neurons can not be activated by He-Ne laser irradiation. When the spontaneously active neurons generating spikes every 7-10 min were irradiated in between their spontaneous spikes, the depolarization of membrane and generation of action potentials occurred as a function of light intensity, I. The probability of spike generation increased until the intensity reached 1 W/cm2, and when I = 4 W/cm2 was equal to 1. The depolarization of the membrane had a threshold at I = 0.1 W/cm2, then increased with increasing the intensity, and reached a plateau at I = 0.7 W/cm2 (depolarization rate 0.18 mV/s). Duration of the latent period decreased from 28 s to 17 s when the intensity was increased from 0.05 to 0.3 W/cm2. Further increase of the light intensity, from 0.3 to 1.5 W/cm2, caused a less pronounced change in the duration of the latent period (e.g., latent period equal to 11 s at I = 1.5 W/cm2).     

Melatonin modulates the action of near infrared radiation on cell adhesion

The adhesion of human cervical cancer (HeLa) cells to a glass matrix is evaluated following their irradiation in a suspension with a pulsed near-infrared (IR) light-emitting diode (wavelength 820 nm, pulse repetition frequency 10 Hz, irradiation dose 16-120 J/m2) when melatonin (4 x 10(-11) to 4 x 10(-5) m) is added to cell suspension immediately before or after the irradiation. Also, the dependence of visible-to-near-IR radiation (600-840 nm, 52 J/m2) on cell adhesion (action spectrum) is recorded in absence and presence of melatonin (4 x 10(-6) m). It is found that melatonin in pharmacological concentrations (but not in physiological range) inhibited cell adherence. Irradiation of cells before or after melatonin treatment normalizes cell adhesion to control level. Melatonin in pharmacological concentrations eliminates stimulation of cell attachment induced by irradiation. Pre-treatment (but not post-treatment) with melatonin in the physiological concentration eliminates cell adhesion stimulation induced by irradiation. Melatonin modifies the light action spectrum significantly in near IR region (760-840 nm only). Thus, the peak at 820-830 nm characteristic for the light action spectrum is fully reduced.