Conduction pattern of excitation in the amphibian atrium assessed by multiple-site optical recording of action potentials

Spontaneous action potentials were monitored from multiple sites in the bullfrog atrium using a voltage-sensitive merocyanine-rhodanine dye together with a 100-element photodiode matrix array, and we have assessed the spread of the excitation from the pacemaker. Isochrone curves of conduction were obtained by timing the initiation of the action potential-related optical signals: we constructed maps of the spread. Excitatory waves appeared to conduct radially from the pacemaking area over the atrium, and the conduction velocity in the left atrium exceeded that in the right atrium.     

Consistency behind trial-to-trial variation in intrinsic optical responses to single-whisker movement in the rat D1-barrel cortex

We examined consistent characteristics behind the trial-to-trial variati on in intrinsic optical imaging of single barrel cortical responses to D 1-whisker movement in 2-5-week postnatal (2-5 W) and adul t (>9-weeks) Wistar rats, and we identified the effective are a of the neural response. The extent/size, configuration and orientation of the intrinsic optical response area varied from trial-to-trial with the same whisker stimulation. We argue that the trial-to-trial variation was due to cortical blood circulation related to the barrel neural activity. Subsequently, interpolating a family of the traces of the optical response area imaged with repeated stimulation for each animal, we extracted a centered circular area from the trial-to-trial response for each animal. Although the trial-to-trial variation decreased gradually with age, the spatial extent of the interpolated response area was consistently about 660 microm in diameter, in agreement with that measured morphologically and/or histochemically. A possible interpretation is that the optically defined area appears to image the actual effective single-barrel response area, as a first approximation. Furthermore, the constancy of the extracted area independent of age suggests that the barrel cortex is, in fact, virtually mature by 2 weeks of age. The extracted area was also nearly independent of the frequency (>/=5 Hz) of whisker movement.     

Optical detection of embryogenetic expression of vagal excitability in the rat brain stem

We traced and identified the ontogenetic expression of neural excitability related to the vagus nerve in the embryonic rat brain stem. Multiple-site optical recordings of neural activities revealed two response areas in the E12 rat brain stem: one corresponding to the dorsal motor nucleus of the vagus nerve, and the other reflecting the activities of sensory nerve fibers. In embryos younger than E11, no optical response was identified, suggesting that excitability of the motoneurons and/or sensory nerve fibers is first generated no later than E12. A contour line map of the neural responses suggested that, in contrast to older embryos, the functional organization of the vagal nucleus is not orderly at the time of the initial expression of neural excitability.     

Hepatocellular Carcinoma Induction in LEC Rats by a Low Dose of 2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline

A food-borne heterocyclic amine, 2-amino-3,8-dimethylimidazo[4,5- f ]qninoxaline (MeIQx), induces hepatocellular carcinomas (HCCs) in F344 male rats at an incidence of 95%, when fed in the diet at 400 ppm for 61 weeks. In this study, the effect of a low dose of MeIQx was examined in Long-Evans with cinnamon-like coat color (LEC) rats, which have a mutation in Atp7b and suffer from hereditary hepatitis and HCCs, with high levels of copper accumulation in the liver. Rats of the LEC and Long-Evans with agouti coat color (LEA) sibling lines were given a diet containing 40 ppm MeIQx from the age of 23 weeks to 63 weeks, for a total administration period of 40 weeks. In LEC rats, HCCs were observed in 8/8 animals administered MeIQx, and 2/8 rats receiving a normal diet. The number of HCCs per rat (mean±SD) was 2.8±2.0 and 0.3±0.5, respectively. In the LEA rats, however, no tumors were induced by administration of MeIQx. These results indicate that damaged liver associated with compensatory cell proliferation is much more susceptible to chemical hepatocarcinogens, including MeIQx, than the normal liver.     

Visualization of the photodegradation of a therapeutic drug by chemometric-assisted fluorescence spectroscopy

The fluorescence spectral fingerprint, also known as the excitation-emission matrix (EEM), is used to assess and visualize therapeutic drug photodegradation in combination with chemometrics. Examination of EEM-parallel factor analysis (PARAFAC) data showed that an individual component was easily separated from a mixture of photogenerated products of a heterocyclic pharmacophore, in this case, phenothiazine drugs (PTZs). Detailed investigations of both structure–EEM relationships and kinetics revealed that the components extracted from EEM–PARAFAC could be quantitatively attributed to such photogenerated products as phenothiazine sulfoxide and carbazole derivatives. EEM in combination with principal component analysis (PCA) could be used as a mapping tool to visualize information of the photodegradation process of PTZs. We also assessed the photostability of various types of PTZs containing side chains by using validated EEM–PARAFAC methodology.

Drug quality and assurance changes with time under the influence of a variety of environmental factors, such as light, temperature, and moisture.     

Association study between a novel single nucleotide polymorphism of the promoter region of the prostacyclin synthase gene and essential hypertension.

The purpose of this study was to investigate whether an association exists between the promoter region of the prostacyclin synthase gene and essential hypertension (EH). Using the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) method, we discovered a novel single nucleotide polymorphism (SNP), T-192G, in the 5'-flanking region. We performed an association study using the SNP in 200 patients and 200 controls. The allele frequency distribution in the two groups was not significantly different. Thus, this SNP in the PGIS gene is not associated with EH.     

Isolation of Legionella spp. from cooling tower water in Kinki District, Japan]

Distribution of Legionella spp. were surveyed two different times in Kinki District, Japan. The first time, eighty six building cooling tower waters were collected from Osaka, Hyogo and Nara Prefecture between April and December, 1987. The second time, thirty five waters were studied from Nishinomiya City in Hyogo Prefecture on July, 1989. BMPA alpha agar plate was used as the isolation medium for the first eighty six samples and MWY agar plate for the second thirty five samples. Legionella were isolated from forty two samples (48.8%) of the first eighty six samples. Three different species of Legionella were isolated simultaneously from one sample and two species from eight samples. L. pneumophila serogroup 1 was the most predominant species. Twenty three samples (65.7%) were positive in culture from the second thirty five samples. Three different species of Legionella were isolated simultaneously from three samples and two species from eleven samples. Legionella anisa was more predominant than L. pneumophila serogroup 1 in this study.