Whole blood samples of known methylene tetrahydrofolate reductase (MTHFR) genotypes from 24 individuals were examined at site C677T. Their amplified DNA products were assessed by two-color fluorescence cross-correlation measurements and agarose gel electrophoresis/capillary gel electrophoresis. DNA subpopulations were identified which were not associated with the proper genotype by primer combinations and cycling conditions called multiplexes. We confirmed that DNA analysis by two-color fluorescence cross-correlation measurements allowed the detection of fluorescence signals specifically associated with the proper genotypes in a mixture of amplified nontarget DNA molecules without DNA sizing. The measurement approach does not require complex, follow-up mathematical analysis and is applicable to any single nucleotide polymorphisms. The simple immunogenetic model showed how the approach works to reveal specific DNA target by preventing detection of nontarget DNA. Under those experimental conditions, a new ultrasensitive, and specific method for clinical immunologists is born. 相似文献
Several studies have investigated the T1 and T2 relaxation time of choline, creatine and N-acetyl aspartate in cerebral white matter in normal human subjects. However, these studies demonstrate a large variation in T1 and T2 values. In the present study, relaxation times of choline, creatine and N-acetyl aspartate were determined in cerebral white matter in 15 control subjects (age 21 +/- 2 y, mean +/- SD) at 1.5 T. Using PRESS, seven or eight data points were obtained to fit the T1 and T2 relaxation curves to, respectively. The mean voxel size was 14 cm3. The T1 relaxation times of choline, creatine and N-acetyl aspartate were 1091 +/- 132 (mean +/- SD), 1363 +/- 137 and 1276 +/- 132 ms. The T2 relaxation times were 352 +/- 52, 219 +/- 29 and 336 +/- 46 ms, respectively. 相似文献
Summary: A new principle for the design of dendritic macromolecules – the ionic binding of linear chain polyelectrolyte with oppositely charged focal ionogenic groups of dendrons – has been developed. The majority of the dendritic ionic complexes (DICs) are prepared with poly(styrenesulfonic acid) (PSS) as a polymeric core and L ‐aspartic acid dendrons of different generations. Two series of DICs were prepared using PSS and aspartic dendrons bearing terminal (located at the external periphery) methoxycarbonyl and hexyloxycarbonyl groups (C1‐n and C6‐n respectively where n is the generation number). Ionic binding of about 100% was found for dendrons of Generation 1–3. The solubility of the DICs was examined and the DICs prepared were studied by IR spectroscopy, 1H NMR and viscometry.
Dendritic ionic complexes prepared using poly(styrenesulfonic acid) acid and aspartic dendrons bearing terminal methoxycarbonyl and hexyloxycarbonyl groups. 相似文献
BACKGROUND: Lead remains in high levels in the environment and is known to reduce fertility in animal models, but a direct link between lead exposures and human infertility has not yet been established. METHODS: In a prospective, double-blind study of the metal ion levels and sperm function, semen was obtained from partners of 140 consecutive women undergoing their first IVF cycle. Lead in seminal plasma was determined by atomic absorption spectroscopy. Motile sperm populations were assessed for surface receptors for mannose binding, and the ability to undergo premature ('spontaneous'), and free mannose-induced acrosome reactions. Fertile donor (n = 9) sperm were exposed to exogenous lead during capacitating incubations and then assessed for mannose receptor expression and acrosome loss. RESULTS: Lead levels were negatively correlated with IVF rates. Lead levels were negatively correlated to two of the three sperm function biomarkers (mannose receptors, mannose-induced acrosome reactions). Lead levels positively correlated with the spontaneous acrosome reaction. These findings were mimicked by in-vitro exposure of fertile donor sperm to lead. CONCLUSIONS: Multiple sperm parameters are affected as lead levels rise. Increased lead levels may contribute to the production of unexplained male infertility. 相似文献
The functional relationship between septal unit activity and hippocampal EEG was studied during the sleep-wakefulness cycle in chronically implanted unrestrained rats. Results were statistically analyzed in order to obtain the time interval and auto and crosscorrelation histograms. During REM sleep and restless wakefulness the hippocampal EEG showed a theta rhythm of 4–8 cps and the septal unit activity was characterized by the presence of rhythmic bursts with a frequency in every single instance similar to that of the hippocampus. The septal units showed a bimodal time interval histogram. Their autocorrelation histogram exhibited a sinusoidal pattern of decreasing amplitude. The crosscorrelation histogram of septal units and the hippocampal EEG also showed a sinusoidal pattern suggestive of the functional relationship between both neural structures. During slow wave sleep and quiet wakefulness there was a disappearance of the hippocampal theta rhythm and rhythmic septal unit bursts. The second mode was missing in the time interval histogram and the auto and crosscorrelation histograms showed an irregular pattern. It is concluded that medial septal nucleus and hippocampal temporal patterns of activity are similar during REM sleep and restless wakefulness. 相似文献
Long time-constant EEG recording during paired stimuli has led to the discovery of the contingent negative variation or expectancy wave (Walter, 1964). This effect is produced when a conditional stimulus signals that an imperative stimulus demanding action, decision, or attention will follow at a short, constant time interval. Symbolic and meaningful stimuli were presented to subjects tachistoscopically, and the evoked responses in the brain were electronically averaged. The cerebral evoked responses to such psychological stimuli are more complex than to flashes. A slow negative DC potential shift (CNV) was seen during the interval between an auditory ready signal and the visual exposure if recognition of the stimulus was required, or if it was interesting. Following the visual exposure, a slow positive DC shift occurred. The method has been developed to study the brain responses to psychological stimuli. The amplitude of the responses relates to the information content and subjective factors rather than to the physical strength of the stimulus. 相似文献