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In galactosamine (GalN)-induced rat liver injury, hepatic stem/progenitor cells, small hepatocytes (SHs) and oval cells, transiently appear in the initial period of liver regeneration. To clarify the relationship between SHs and oval cells, CD44(+) and Thy1(+) cells were sorted from GalN-treated livers and used as candidates for SHs and oval cells, respectively. Some Thy1(+) cells isolated 3 days after GalN-treatment (GalN-D3) formed CD44(+) cell colonies, but those from GalN-D2 could form few. GeneChip (Affymetrix, Inc, Santa Clara, CA) analysis of the sorted cells and cultured Thy1(+) cells suggested that hepatocytic differentiation progressed in the order Thy1(+) (GalN-D3), Thy1(+) cell colony (Thy1-C), and CD44(+) (GalN-D4) cells. When Thy1(+), Thy1-C, and CD44(+) cells were transplanted into retrorsine/PH rat livers, they could proliferate to form hepatocytic foci. At 30 days after transplantation most cells forming the foci derived from CD44(+) cells possessed C/EBPalpha(+) nuclei, whereas only a few cells derived from Thy1-C showed this positivity. When Thy1(+) (GalN-D3) cells were cultured between collagen gels in medium with hepatocyte growth factor(+)/dexamethasone(-)/dimethyl sulfoxide(-), ducts/cysts consisting of biliary epithelial cells appeared, whereas with CD44(+) and Thy1(+) (GalN-D2) cells they did not. Taken together, these results indicate that the commitment of Thy1(+) cells to differentiate into hepatocytes or biliary epithelial cells may occur between Day 2 and Day 3. Furthermore, some Thy1(+) cells may differentiate into hepatocytes via CD44(+) SHs.

Background/aims: Small hepatocytes (SHs) are hepatic progenitor cells, but the phenotypical difference between SHs and mature hepatocytes (MHs) has never been demonstrated., Methods: The profile of gene expression was examined to clarify the difference between SHs and MHs by using a DNA microarray. Genes that were specifically expressed in SHs were identified and RT-PCR analysis of them was performed. Immunocytochemistry for CD44 standard form (CD44s) and variant form 6 (CD44v6) was performed using cultured SHs and the d-galactosamine (GalN)-injured rat liver. From the GalN-treated liver, CD44s+ cells were obtained by sorting and RT-PCR analysis was performed., Results: Analysis using the DNA microarray and RT-PCR of them revealed restricted expression of CD44s and CD44v6 in SHs. In culture, CD44s appeared at day 3 and increased with the proliferation of SHs. CD44v6 expression was delayed compared to that of CD44s. With GalN-administration, CD44+ hepatocytes appeared around periportal areas at days 3 and 4 and then decreased. Sorted CD44s+ cells could form colonies and possessed hepatic markers., Conclusions: CD44 is a specific marker of SHs. The expression of CD44 mRNA and protein is restricted to SHs, and is up-regulated at the time when SHs start to proliferate both in vitro and in vivo.

The diagnosis of obturator hernia is difficult, and delayed treatment is associated with serious complications. Recently, computed tomography (CT) has been used successfully for establishing a correct diagnosis. We encountered nine cases of obturator hernia from 1988 to 1997. All the patients were elderly women. In six of them, a correct diagnosis was established by emergent CT scan. In two of the remaining cases, diagnosis could not be established because of unavailability of CT, and the other patient was diagnosed correctly based on clinical features, including a positive Howship-Romberg sign. Surgical repair was performed successfully. One patient died postoperatively because of septicemia associated with anastomotic leakage. Our cases indicate that emergent CT scan is useful for the diagnosis of obturator hernia, particularly in elderly patients presenting with ileus of unknown origin.

Trigeminal neurosensory impairment is frequently observed following orthognathic surgery. The purpose of the present study is to visualize the degree of trigeminal nerve impairment following bilateral sagittal split osteotomy (BSSO). Twenty patients who underwent BSSO were in the present study. To record the modified somatosensory evoked potentials (SEP), two electrostimulation clips were applied. One clip was placed on the mucous surface of the lower lip and the other was placed on the skin surface. Each contact surface contained a separate 2 mm diameter silver anode and cathode attached to a 5 x 15 mm basement plate. The results obtained using this method revealed that complete recovery from neural impairment was observed in 7 cases (36.8%) on the right operative side and 4 (20.0%) on the left side at 6 months postoperatively. A definite delay in latency was observed on the left operative side at all the examination periods. The recovery period evaluated by the SEP method was longer than that of the objective two-point discrimination thresholds. Clinical records obtained showed considerable implications for trigeminal nerve function after BSSO.