Motoi Kudo

Immunohistochemical detection of L-DOPA-derived dopamine within serotonergic fibers in the striatum and the substantia nigra pars reticulata in Parkinsonian model rats.

On the basis of our previous studies in the normal rat [Arai, R., Karasawa, N., Geffard, M., Nagatsu, I., 1995. L-DOPA is converted to dopamine in serotonergic fibers of the striatum of the rat: a double-labeling immunofluorescence study. Neurosci. Lett. 195, 195-198; Arai, R., Karasawa, N., Nagatsu, I., 1996a. Aromatic L-amino acid decarboxylase is present in serotonergic fibers of the striatum of the rat. A double-labeling immunofluorescence study. Brain Res. 706, 177-179; Arai, R., Karasawa, N., Nagatsu, I., 1996b. Dopamine produced from L-DOPA is degraded by endogenous monoamine oxidase in neurons of the dorsal raphe nucleus of the rat: an immunohistochemical study. Brain Res. 722, 181-184] we have assumed that exogenously administered L-dihydroxyphenylalanine (L-DOPA) is converted into dopamine (DA) in serotonergic (5-HT) fibers within the striatum (ST) and the substantia nigra pars reticulata (SNR). In the present study, an attempt was made to confirm the assumptions in Parkinsonian rats, which were produced by unilateral injections of 6-hydroxydopamine (6-OHDA) into the substantia nigra pars compacta (SNC). The rats exhibiting more than 150 total controversial circles were regarded as satisfactory models of Parkinson disease (PD). Using a dual immunofluorescence histochemistry, we examined DA-immunoreactivity in the 5-HT fibers within the ST and the SNR of the PD model rats after L-DOPA was injected intraperitoneally. In experimental cases with the L-DOPA administration, DA-immunoreactivity was detected in 5-HT fibers in both the ST and the SNR on the 6-OHDA injection side; no DA-immunoreactivity was found in 5-HT fibers in the ST or the SNR in control cases without the L-DOPA administration. The results support the assumption that exogenously administered L-DOPA may be converted into DA within the 5-HT fibers in the ST and SNR of the PD model rats.

High Range Resolution Ultrasonographic Vascular Imaging Using Frequency Domain Interferometry With the Capon Method

For high range resolution ultrasonographic vascular imaging, we apply frequency domain interferometry with the Capon method to a single frame of in-phase and quadrature (IQ) data acquired using a commercial ultrasonographic device with a 7.5 MHz linear array probe. In order to tailor the adaptive beamforming algorithm for ultrasonography we employ four techniques: frequency averaging, whitening, radio-frequency data oversampling, and the moving average. The proposed method had a range resolution of 0.05 mm in an ideal condition, and experimentally detected the boundary couple 0.17 mm apart, where the boundary couple was indistinguishable from a single boundary utilizing a B-mode image. Further, this algorithm could depict a swine femoral artery with a range beam width of 0.054 mm and an estimation error for the vessel wall thickness of 0.009 mm, whereas using a conventional method the range beam width and estimation error were 0.182 and 0.021 mm, respectively. The proposed method requires 7.7 s on a mobile PC with a single CPU for a 1 × 3 cm region of interest. These findings indicate the potential of the proposed method for the improvement of range resolution in ultrasonography without deterioration in temporal resolution, resulting in enhanced detection of vessel stenosis.

Immunohistochemical distribution of the endothelin-converting enzyme-1 in the rat hypothalamo-pituitary axis.

We prepared a rabbit polyclonal antibody against an endothelin converting enzyme-1 (ECE-1) to examine the distribution of ECE-1 in the hypothalamus and the pituitary of the rat. By the Western blot analysis, the antibody specifically recognized ECE-1 proteins in membrane fractions of the rat hypothalamus. Immunohistochemical staining revealed ECE-1 immunoreactivity in both cell bodies and axons in some hypothalamic neurons. The immunopositive cell bodies were located in the paraventricullar and supraoptic nuclei; immunopositive axons were distributed in the suprachiasmatic, paraventricullar (PVN), and supraoptic (SON) nuclei. However no immunoreactivity was detected in the posterior pituitary gland. The present results indicate that ECE-1 converts the endothelin-1 (ET-1) from precursor big ET-1 to mature ET-1 in the PVN/SON. The big ET-1 existing in the posterior pituitary gland is thought to be escaped from the converting by ECE-1 in the hypothalamus.

Auditory projections from the IC to the SCN by way of the LG in the mole, Mogera

TO study morphological substrates for sensory specialization in subterranean mammals, we investigated both auditory and visual pathways in the mole. The inferior colliculus (IC), an auditory relay, projects not only to the medial geniculate, the major gateway to the auditory cortex, but also to the lateral geniculate (LG), the major gateway to visual cortex. Further evidence is that the LG does not send many fibers to the cortex in the mole. Instead, the auditory inputs to the LG are likely to be conveyed to the suprachiasmatic hypothalamic nucleus (SCN), which plays a role in photoperiodic functions in common mammals. Auditory inputs to the SCN may subserve periodic reproductive behaviors in the exclusively separated territorial domains of subterranean mammals.

Neurogenesis in the superior olivary complex in the rat

In a previous paper we provided evidence that crossed projection neurons are generated earlier than uncrossed projection neurons in the lateral superior olive. The aim of the present study was to determine if other major nuclei of the superior olivary complex (SOC), the medial superior olivary (MSO), the superior paraolivary (SPN) and the medial trapezoid (MTB) nuclei, are distinguished by their neuronal constitutions of birthdates. Pregnant rats were injected intraperitoneally with 5-bromodeoxyuridine (BrdU), the thymidine analogue, to label the neurons on one of the embryonic (E) days E11-E16. When the progeny rats reached adulthood, the brains were processed for BrdU immunohistochemistry. The MSO was mostly composed of neurons generated on E12 (95%). The remaining neurons in the MSO completed their neurogenesis by E13. The SPN neurons were generated from E12 to E14 with a peak on E13 (80%). Regardless of the morphological heterogeneity, the SPN consisted of a single population of neurons in terms of neurogenesis. The MTB neurons were generated from E13 to E16 with a peak on E14 (73%). In contrast to the previous assumption, no topographical relationship existed between neurogenesis and tonotopicity within each nucleus of the SOC.

Glycine-immunoreactive synapses in the central nucleus of the inferior colliculus. An electron microscopic study in the cat.

It has been known that the inferior colliculus contains many glycinergic fibers of both intrinsic and extrinsic nature. In the present study, glycine-immunoreactive (Gly-ir) synapses were examined in the central nucleus of the inferior colliculus in the cat. About half of 891 axondendritic synapses that were identified in the present study were Gly-ir. In 75% of these Gly-ir synapses, synaptic axon terminals contained pleomorphic or flattened synaptic vesicles and made symmetric synapses, while in 25% of Gly-ir synapses, synaptic axon terminals were filled with spherical synaptic vesicles and formed asymmetric synapses. Thus, Gly-immunoreactivity was detected in axodendritic synapses that formed both Grays type I and Grays type II synapses.

A possible role of transient AChE expression in the medial geniculate of developing rats.

ACETYLCHOLINESTERASE (AChE) and calbindin D-28K (CaBP) are transiently expressed in the rat auditory nuclei during the early postnatal period. In the ventral division of the medial geniculate body (MGV), the transient AChE expression in the neuropil is replaced by CaBP expression in the neurones. The time correlation between the up- and down-regulations in these neurochemicals suggests some switching over mechanism. A lesion of the inferior colliculus (IC) decreases the AChE reactivity in terminal field of the IC-MGV projections. We here demonstrate that the IC lesion results in CaBP expressions in neurones of the MGV before its normal onset. It is thus possible that the transiently expressed AChE plays an important role in the intercellular signal transduction for neurochemical phenotype expressions.

Right hepatic artery traveling anteriorly to the common bile duct

The topographic relationship between arteries and hepatobiliary ducts can be crucial during cholecystectomy. We observed the right hepatic artery traveling a rare route in a 91-year-old male. The common hepatic artery gave off the left hepatic, the right gastric, the gastroduodenal, and the right hepatic arteries consecutively without forming the proper hepatic artery. The right hepatic artery crossed the common bile duct anteriorly, ascended on the right side of the duct, passed the cystic duct posteriorly, and entered the right lobe of the liver. The so-called 9 o’clock artery running on the right side of the common hepatic and common biliary is reasonably speculated to be the aberrant right hepatic artery as presently shown. Developmental and clinical issues are discussed.

Adaptive-beamformer with accurate intensity-estimation technique for high-range-resolution vascular ultrasound imaging

For the early detection and for the treatment assessment of cardiovascular disease, improvement in range resolution of vascular ultrasound imaging is highly desirable. The employment of frequency domain interferometry with the Capon method largely improves the range resolution of ultrasound imaging; however, this methodology often underestimates the echo intensity. In this paper, we propose a compensation method to improve the estimation accuracy in echo intensity acquired by the high-range-resolution ultrasound imaging method based on frequency domain interferometry. The method requires 0.18 s/frame using a single CPU PC. The proposed method has the spatial resolution of 0.05 mm with the average estimation intensity error of 0.15 dB on the log scale, where we employ an ultrasound pulse of 7.5 MHz center frequency. We have applied the proposed method to a swine femoral artery in vitro and a human carotid artery in vivo, and verified its efficiency to improve the accuracy in echo intensity estimation.

High range resolution ultrasound imaging of a human carotid artery using frequency domain interferometry

In this study, we propose a high range resolution ultrasound imaging method using frequency domain interferometry with adaptive beamforming technique. We employ multiple reference signals to compensate the variation of the vessel wall slope. The proposed method succeeded to acquire a high range resolution carotid artery image of a normal living human subject, where the method was applied to a single frame IQ data obtained by a commercial ultrasonographic device. This result verified the capability of the proposed method to improve the range resolution in ultrasonography. We believe the proposed method will largely progress medical diagnostics in vascular ultrasound.