Immunocytochemical localization of tyrosine hydroxylase in the visual cortex of the microbat, Rhinolophus ferrumequinum.

INTRODUCTION: In order to enhance our understanding of bat vision, we investigated tyrosine hydroxylase (TH)-immunoreactive (IR) fibers in the visual cortex of the microbat. MATERIAL AND METHODS: The study was conducted on 12 freshly-caught adult bats (Rhinolophus ferrumequinum, both sexes, weighing 15-20 g). We used standard immunocytochemistry and confocal microscopy. RESULTS: TH-IR fibers were distributed throughout all layers of the visual cortex, with the highest density in layer I. Two types of TH-IR fibers were observed: small and large varicose fibers. TH-IR cells were not found in the microbat visual cortex. The microbat substantia nigra and ventral tegmental areas, previously identified sources of TH-IR fibers in the mammalian visual cortex, all contained strongly labeled TH-IR cells. The average diameters of TH-IR cells in the substantia nigra and the ventral tegmental areas were 14.39 ± 0.13 µm (mean ± SEM) and 11.85 ± 0.13 µm, respectively. CONCLUSIONS: Our results suggest that the microbat has a well-constructed neurochemical organization of THIR fibers. This observation should provide fundamental insights into a better understanding of the nocturnal, echolocating bat visual system.

Identification of calretinin-expressing retinal ganglion cells projecting to the mouse superior colliculus.

In mice, retinal ganglion cells (RGCs), which consist of around 30 subtypes, exclusively transmit retinal information to the relevant brain systems through parallel visual pathways. The superior colliculus (SC) receives the vast majority of this information from several RGC subtypes. The objective of the current study is to identify the types of calretinin (CR)-expressing RGCs that project to the SC in mice. To label RGCs, we performed CR immunoreactivity in the mouse retina after injections of fluorescent dye, dextran into mouse SC. Subsequently, the neurons double-labeled for dextran and CR were iontophoretically injected with the lipophilic dye, DiI, to characterize the detailed morphological properties of these cells. The analysis of various morphological parameters, including dendritic arborization, dendritic field size and stratification, indicated that, of the ten different types of CR-expressing RGCs in the retina, the double-labeled cells consisted of at least eight types of RGCs that projected to the SC. These cells tended to have small-medium field sizes. However, except for dendritic field size, the cells did not exhibit consistent characteristics for the other morphometric parameters examined. The combination of a tracer and single-cell injections after immunohistochemistry for a particular molecule provided valuable data that confirmed the presence of distinct subtypes of RGCs within multiple-labeled RGCs that projected to specific brain regions.

Immunocytochemical Localization of Choline Acetyltransferase in the Microbat Visual Cortex.

The purpose of the present study was to investigate the organization of choline acetyltransferase (ChAT)-immunoreactive (IR) fibers in the visual cortex of the microbat, using standard immunocytochemistry and confocal microscopy. ChAT-IR fibers were distributed throughout all layers of the visual cortex, with the highest density in layer III and the lowest density in layer I. However, no ChAT-IR cells were found in the microbat visual cortex. ChAT-IR fibers were classified into two types: small and large varicose fibers. Previously identified sources of cholinergic fibers in the mammalian visual cortex, the nucleus of the diagonal band, the substantia innominata, and the nucleus basalis magnocellularis, all contained strongly labeled ChAT-IR cells in the microbat. The average diameter of ChAT-IR cells in the nucleus of the diagonal band, the substantia innominata, and the nucleus basalis magnocellularis was 16.12 µm, 13.37 µm, and 13.90 µm, respectively. Our double-labeling study with ChAT and gamma-aminobutyric acid (GABA), and triple labeling with ChAT, GABA, and post synaptic density 95 (PSD-95), suggest that some ChAT-IR fibers make contact with GABAergic cells in the microbat visual cortex. Our results should provide a better understanding of the nocturnal bat visual system.

[A comparative cross-sectional study of the development of hepatocellular carcinoma in patients with liver cirrhosis caused by hepatitis B virus, alcohol, or combination of hepatitis b virus and alcohol].

BACKGROUND/AIMS: Alcohol may be a cocarcinogen in patients with chronic viral hepatitis. We investigated the effect of alcohol on the development of hepatocellular carcinoma (HCC) in liver cirrhosis (LC) caused by hepatitis B virus (HBV). METHODS: All patients with LC or HCC associated with HBV or alcohol, admitted between March 2001 and June 2005, were included. Patients were divided into three groups according to the etiology of LC: Alcohol (AL), HBV, or HBV alcohol (HBV AL). Age and laboratory data at the enrollment of study were analyzed. The logistic regression coefficiency for the prevalence of HCC was calculated by using variables such as age, gender, serologic markers, and etiology of LC. RESULTS: In LC patients (n=342), the proportions of AL, HBV, and HBV AL groups were 44%, 39%, and 17%, respectively. The proportions of HCC in AL, HBV and HBV AL groups were 17%, 55%, and 76%, respectively. Age at the diagnosis of HCC was younger in HBV AL than in AL group (p=0.036). In logistic regression analysis for the risk factor of HCC, odds ratio of age was 1.056 (p0.001). Odds ratios of HBV and HBV AL group comparing AL were 8.449 (p0.001) and 17.609 (p0.001), respectively. Therefore, old age and chronic alcohol intake in patients with HBsAg were the risk factors of HCC. CONCLUSIONS: Chronic alcohol intake may be an additive factor for the development of HCC in patient with LC caused by HBV. However, a prospective cohort study is needed to confirm these findings.