Antigen density in ELISA; effect on avidity dependency

Two different densities of an antigen (bovine serum albumin, BSA) were used on paper disks is an enzyme-linked immunosorbent assay (ELISA) for chicken IgG anti-BSA antibodies. Disks of different antigen density but containing the same amount of the antigen showed a difference in immunoreactivity. Samples containing large amounts of low avidity antibodies gave higher absorbance when disks of lower antigen density were used. This phenomenon was not due to a competition between antibodies of various immunoglobulin classes. These findings may indicate that antigen density affects the sensitivity of ELISA to antibodies of various avidities.     

Early metastases in regional lymph nodes and prognosis of malignant melanoma. Histological and clinical examinations in 104 lymphadenectomized patients

In 104 malignant melanoma patients who underwent lymphadenectomy (67 females, 37 males), correlations were studied between histologically diagnosed lymph node metastasis, the type of malignant melanoma and the depth of invasion according to Clark, as well as other parameters. In 35.6% of the patients, metastases of the primary tumor were found in one or several regional lymph nodes. In about one third of the patients, the clinical and histological lymph node findings were proven to diverge. The female:male ratio of generally about 2:1 shifted to 1:1 in the group of patients with lymph node metastasis, i.e. cases with lymph node metastasis were found significantly increased in the male sex, and also, when primary tumors were localized on the trunk. A prognostic correlation between the two parameters, sex and localization, is suggested by the high incidence of histologicallly diagnosed metastases in 1 or 2 lymph node regions, when malignant melanomas were localized on the trunk in males. As to the types and the micro-stages of primary tumors, the number of cases collected until now does not permit establishing clear correlations with the incidence of lymph node involvement. Calculating the 5-year-survival rates for patients with and without lymph node metastasis according to the "actuarial method", we found the prognosis to depend largely on the presence or absence of lymph node involvement, even at a time as early as at primary tumor excision. Our results support the indication for prophylactic lymphadenectomy in malignant melanoma, provided the primary tumor has reached or surpassed the micro-stage 3.     

Psychotic experience and disordered thinking: a reappraisal from new perspectives

The reports of a person suffering from loose associations and disordered behavior serve as the basis for a phenomenology of some central components of psychotic experience. Especially salient are "the expansion of the horizon of meanings," "the emergence of explicit experiences from implicit ones," and "the reduction of complexity." The phenomenological concepts thus developed supplement recent discoveries in neuroscience and experimental psychopathology. Cognitive neuroscientists have depicted the surface of the brain as a repository of self-organizing cortical maps of mental life. Furthermore, experimental psychopathologists have characterized semantic associative networks in normal experience and in psychosis. The authors conclude by joining the phenomenology of psychotic consciousness with the findings of these neuroscientists and experimental psychopathologists.     

Characterisation of a pea hsp70 gene which is both developmentally and stress-regulated

OBJECTIVES: We sought to evaluate the immediate angiographic results and intermediate-term follow-up after percutaneous treatment of left main coronary stenoses in the new device era. BACKGROUND: Historically, balloon angioplasty of left main coronary stenoses has been associated with high procedural morbidity and poor long-term results. It is not clear whether new devices are more effective in this anatomic setting. METHODS: Between July 1993 and July 1995, we performed initial left main coronary interventions on 46 patients (mean age 67 +/- 12 years, 26% women). Quantitative angiography was available for 42 of 46 interventions, and clinical follow-up was obtained for all patients at 1 month, 6 months and 1 year after initial revascularization. RESULTS: Most interventions (42 of 46) were performed in patients with "protected" coronary stenoses to the left coronary system owing to the presence of one or more patent left main coronary grafts. Seventy-seven percent of screened patients were deemed unsuitable for repeat coronary artery bypass surgery. Procedures performed included stenting in 73% of patients (alone in 30% and after rotational atherectomy in 43%), rotational atherectomy in 58% (alone in 15% and before stenting in 43%), directional atherectomy in 4% and angioplasty alone in 7%. Initial procedural success was achieved in all interventions, with no deaths, myocardial infarctions (creatine kinase, MB fraction > 50 IU/liter) or emergent bypass surgery. Follow-up data to date (median duration 9 months, range 6 to 19) demonstrate a 98% overall survival rate and a 6-month event-free survival rate of 78% (six target vessel revascularizations [TVRs], four non-TVRs). CONCLUSIONS: Treatment of protected left main coronary artery stenoses can be accomplished safely and effectively with new device technology. Intermediate-term follow-up demonstrates an acceptably low rate of death, myocardial infarction or repeat revascularization at 6 months and 1 year.     

The neurophysiological aspects of the recurrent functioning of the "hidden" variables of the speech apparatus

The "hidden" recurrent structure is established of temporal organization of acoustic speech signal. Such "hidden" recurrence can be revealed only due to experimentally established existence of two qualitatively different modes in the temporal organization of stutterers' speech. A theoretical model of speech generation is developed with a logistical property of "hidden" parameters in order to explain this phenomenon. This model is stated in terms of chaotic dynamics and is based on the neurophysiological striopallidal mechanisms which are realized under conditions of polysensory afferent impulsation. The effects of speech memory and actualization of its traces are explained on the basis of our earlier concept of perception of the rhythmical speech sequence. This concept allowed us to discuss the experimentally observed phenomenon of inhibitory modulation under conditions of both ipsi- and contralateral global negative feedback.     

Comparative study of 2mol%Li-and Mn-substituted lead-free potassium sodium niobate ceramics

The effect of Li and Mn substitution on the dielectric, ferroelectric and piezoelectric properties of lead free K0.5Na0.5NbO3 （KNN） was investigated. Samples were prepared using a conventional solid state reaction method. The sintefing temperature for all the samples was 1050℃. The optimum doping concentration for the enhancement of different properties without the introduction of any other co-dopants such as Ti, Sb, and La was investigated. X-ray diffraction analysis confirmed that all the samples crystallize in a single phase perovskite structure. The dielectric properties were investigated as a function of temperature and applied electric field frequency. Compared with Li-substituted KNN （KLNN）, Mn-substituted KNN （KMNN） exhibited a higher dielectric constant εmax （i.e., 4840） at its critical transition temperature Tc （i.e., 421℃） along with a lower value of tangent loss at 10 kHz and greater values of saturation polarisation Ps （i.e., 20.14 μC/cm^2） and remnant polarisation Pr （i.e., 15.48 μC/cm^2）. The piezoelectric constant （d33） of KMNN was 178 pC/N, which is comparable to that of lead-based hard ceramics. The results presented herein suggest that B-site or Mn substitution at the optimum concentration results in good enhancement of different properties required for materials used in memory devices and other applications.     

Oxygen free radical generation during in-utero hypoxia in the fetal guinea pig brain: the effects of maturity and of magnesium sulfate administration

Previous studies have shown, employing direct measurements with electron spin resonance (ESR) spectroscopy, that hypoxia induces an increased production of oxygen free radicals (OFR) in the brain of the guinea pig fetus. The present study using the same approach, investigated the effects of maturity and Mg2+-pretreatment on hypoxia-induced OFR formation in the guinea pig fetal brain. The normoxic and the hypoxic groups were exposed for 60 min to 21% or 7% oxygen, respectively. The control group consisted of term fetuses exposed to normoxia (n=7) and hypoxia (n=7). The experimental groups consisted of the following: (a) for the investigation on maturity effect, preterm fetuses (40 days) exposed to normoxia (n=6) or hypoxia (n=6); and (b) for the Mg2+-pretreatment investigation, term fetuses (60 days) exposed to normoxia (n=6) or hypoxia (n=6) following maternal pretreatment with Mg2+ which consisted of an initial bolus of MgSO4 (600 mg/kg, i.p.) 1 h prior to hypoxia followed by a second dose (300 mg/kg, i.p.). Oxygen free radicals were measured by ESR spectroscopy in the fetal cerebral cortical tissue utilizing phenyl-N-tert-butylnitrone (PBN) spin trapping. Fetal brain tissue hypoxia was documented biochemically by decreased tissue levels of ATP and phosphocreatine. In the control group of term fetuses, the cortical tissue from hypoxic fetuses showed a significant increase in spin adducts (71% increase, p<0.01). In the preterm group, the cortical tissue from hypoxic fetuses showed a 33% increase in spin adducts (p<0.001). The baseline free radical generation during normoxia was 22.5% higher at preterm than at term (41.4+/-3.5 units/g issue vs. 33.8+/-9.3 units/g tissue, p<0.05). In Mg2+-treated groups, spin adduct levels in cortical tissue from hypoxic fetuses did not significantly differ from those of the normoxic group (30.2+/-9.9 units/g tissue, normoxic-Mg2+ vs. 30. 6+/-8.1 units/g tissue, hypoxic-Mg2+). The results indicate that the fetal brain at term may be more susceptible to hypoxia-induced free radical damage than at preterm and that Mg2+ administration significantly decreased the hypoxia-induced increase in oxygen free radical generation in the term fetal guinea pig brain in comparison with non-treated hypoxic group.