Oligomerization and topology of the Golgi membrane protein glucosylceramide synthase

Glucosylceramide synthase (GCS) catalyzes the transfer of glucose from UDP-glucose to ceramide to form glucosylceramide, the precursor of most higher order glycosphingolipids. Recently, we characterized GCS activity in highly enriched fractions from rat liver Golgi membranes (Paul, P., Kamisaka, Y., Marks, D. L., and Pagano, R. E. (1996) J. Biol. Chem. 271, 2287-2293), and human GCS was cloned by others (Ichikawa, S., Sakiyama, H., Suzuki, G., Hidari, K. I.-P. J., and Hirabayashi, Y. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 4638-4643). However, the polypeptide responsible for GCS activity has never been identified or characterized. In this study, we made polyclonal antibodies against peptides based on the predicted amino acid sequence of human GCS and used these antibodies to characterize the GCS polypeptide in rat liver Golgi membranes. Western blotting of rat liver Golgi membranes, human cells, and recombinant rat GCS expressed in bacteria showed that GCS migrates as an approximately 38-kDa protein on SDS-polyacrylamide gels. Trypsinization and immunoprecipitation studies with Golgi membranes showed that both the C terminus and a hydrophilic loop near the N terminus of GCS are accessible from the cytosolic face of the Golgi membrane. Treatment of Golgi membranes with N-hydroxysuccinimide ester-based cross-linking reagents yielded an approximately 50-kDa polypeptide recognized by anti-GCS antibodies; however, treatment of approximately 10,000-fold purified Golgi GCS with the same reagents did not yield cross-linked GCS forms. These results suggest that GCS forms a dimer or oligomer with another protein in the Golgi membrane. The migration of solubilized Golgi GCS in glycerol gradients was also consistent with a predominantly oligomeric organization of GCS.

Prognostic factors and rational approach in the treatment of submucosal cancer of the stomach

In early gastric cancer, lymph node metastasis is known to be a prognostic factor. A retrospective study of 134 patients with submucosal gastric cancer (SMGC) who had undergone gastrectomy with lymph node dissection was performed to evaluate the prognostic factors and indication of postoperative chemotherapy. Five-year disease-free survival rate for 121 patients without nodal metastasis was 100% with (n = 62) or without postoperative chemotherapy (n = 59). On the other hand, it was 72.9% for 13 patients with nodal metastases, although all patients had undergone D2 or D3 resection and received postoperative chemotherapy. Tumor recurrence occurred only in three patients (n = 3) with alpha-fetoprotein (AFP) producing cancer and lymph node metastasis. Multivariate analysis with the Cox's proportional hazard model revealed AFP positivity to be a new independent prognostic factor in addition to lymph node metastasis in the patients with SMGC. Our findings suggest that routine use of postoperative chemotherapy does not appear rational for the patients without nodal metastasis and that new modalities of operation and chemotherapy may be necessary for the patients with AFP producing SMGC with nodal metastasis. The necessity of chemotherapy in conventional-type SMGCs with nodal involvement remains to be studied in future.

Combined toxicity of methanol and formic acid: two cases of methanol poisoning

Two fatalities caused by methanol ingestion are presented. Quantitative analysis of methanol and formic acid using head-space gas chromatography showed concentrations of methanol and formic acid in the femoral blood of each subject of 2.19 mg/ml and 0.41 mg/ml, and 1.96 mg/ml and 0.38 mg/ml, respectively. We concluded that death was due to methanol ingestion and the mechanism causing death involved the combined effects of the anesthetic action of methanol itself and metabolic acidosis by formic acid. Forensic toxicokinetic analysis indicated that both victims had ingested about 100 g of methanol or more.

Tumor vascularity predicts recurrence in differentiated thyroid carcinoma

BACKGROUND

New prognosticators are necessary for optimizing the extent of thyroidectomy and adjuvant radiotherapy in differentiated thyroid carcinoma.

METHODS

Tumor microvessel density (MVD), expression of thymidine phosphorylase (dThdPase) and CD68 stained macrophages were evaluated in 71 differentiated thyroid carcinomas by an immunohistochemical method.

RESULTS

The recurrence-free survival was significantly (P <0.05) shorter in patients with hypervascular tumors but was not related to the dThdPase expression. Significant (R = 0.323, P <0.001) correlation between dThdPase expression score and increment in MVD was documented. Frequent high MVD and dThdPase expression were encountered in tumors >3 cm. Twenty-two of the 27 (82%) patients expressing high dThdPase were also evaluated positive for CD68 (P <0.001).

CONCLUSIONS

Tumor MVD might be a new prognostic indicator of differentiated thyroid carcinoma, whereas dThdpase expression with high MVD might serve to identify a subgroup of thyroid carcinoma patients as potential candidates for adjuvant radiotherapy.

Computer-Aided Diagnosis (CAD) for Mammography: Preliminary Results

PURPOSE: To evaluate the CAD system for screening mammograms. MATERIALS AND METHODS: Mammograms of patients with asymptomatic breast cancerwere examined retrospectively. A total of 260 screening mammograms from 65 patients (bilateral cranio-caudal and medio-lateral-oblique views from each) were tested by using the CAD system (ImageChecker M1000 system, R2 Technology, Los Altos, CA, USA). Results: With 0.58 microcalcifications marks/film and 0.20 mass marks/film set as the false positive rate, 100% of microcalcifications cases and 79% of mass cases were detected correctly. Conclusion: The CAD system has the potential to become a second reader. Further developments are expected to improve the accuracy of detection of mass lesions

Bovine lactoferrin and Lactoferricin inhibit tumor metastasis in mice

The effect of a bovine milk protein, lactoferrin (bLf), and a pepsin-generated peptide of bLf, lactoferricin (Lfcin-B), on inhibition of tumor metastasis produced by highly metastatic murine tumor cells, B16-BL6 melanoma and L5178Y-ML25 lymphoma cells, was examined in experimental and spontaneous metastasis models using syngeneic mice. The subcutaneous (s.c.) administration of bovine apo-lactoferrin (apo-bLf) and Lfcin-B 1 day after tumor inoculation significantly inhibited liver and spleen metastasis of L5178Y-ML25 cells and lung metastasis of B16-BL6 cells, whereas human apo-lactoferrin (apo-hLf) and bovine holo-lactoferrin (holo-Lf) at the dose of 1 mg/mouse did not. Furthermore, both apo-bLf and Lfcin-B, but not apo-hLf and holo-bLf, inhibited the number of tumor-induced blood vessels and suppressed tumor growth on day 8 after tumor inoculations in an in vivo model. However, in a long-term analysis of tumor growth for up to 21 days after tumor inoculation, single administration of apo-bLf significantly suppressed the growth of B16-BL6 cells throughout the examination period, but Lfcin-B showed inhibitory activity only during the early period (8 days). In spontaneous metastasis model, multiple administration of both apo-bLf and Lfcin-B significantly inhibited lung metastasis of B16-BL6 cells, however it was only apo-bLf that exhibited the inhibitory effect of tumor growth at the time of primary tumor amputation (on day 21) after tumor inoculation. The results suggest that apo-bLf and Lfcin-B inhibit tumor metastasis through different mechanisms, and that the inhibitory activity of bLf on tumor metastasis may be related to the property of iron (Fe3+)-saturation.

Osteoclast-like giant cell tumor of the pancreas with metastases to gallbladder and lymph nodes. A case report

Osteoclast-like giant cell tumor of the pancreas (OGTP) is a rare neoplasm, of which the histogenesis is still controversial. Here we report a case of OGTP involving the head of the pancreas in a 71-year-old woman with metastases to the gallbladder and lymph nodes. The primary and metastatic tumors had identical histopathological, immunohistochemical, ultrastructural and molecular biological features. Microscopically, the tumors were characterized by atypical, often pleomorphic mononuclear cells associated with the proliferation of benign-appearing osteoclast-like giant cells (OGCs). Electron microscopic observation provided ultrastructural evidence of epithelial differentiation of the mononuclear cells, including microvilli and desmosomes, which was not obtained for OGCs. On immunohistochemical study, OGCs stained for CD68 (KP-1), LCA and HAM56, whereas mononuclear cells only reacted with PCNA. These findings clearly suggest that mononuclear cells are capable of differentiation and proliferation and may have been the only true tumor cells in this neoplasm, and that OGCs may have been a paraneoplastic product of this rare tumor. On examination of DNA from dewaxed sections of the tumor, we found no p53 mutation in the tumor tissue, but found two K-ras mutations in codon 12; this pattern of mutation commonly occurs in pancreatic carcinoma, indicating a somewhat genetic relationship of OGTP to pancreatic carcinoma. Although OGTP often has a favorable prognosis, the outcome in the present case was poor due to early tumor spread, with less than two years postoperative survival.

Mucosal antibody expression following rapid SIV(Mne) dissemination in intrarectally infected Macaca nemestrina

The early kinetics of antibody expression following transmucosal infection by SIV(Mne) were examined in several mucosal compartments in Macaca nemestrina. Five male-female pairs of macaques were inoculated intrarectally with SIV(Mne) E11S, a biological clone, and serially euthanized at 1, 2, 4, 8, and 12 weeks postinoculation. Plasma, tears, saliva, rectal secretions, and vaginal washes were collected serially and just prior to euthanasia. Both total and SIV-specific IgG and IgA levels were measured by immunoglobulin isotype-specific quantitative enzyme-linked immunosorbent assays (ELISAs), and were further examined by conventional and enhanced chemiluminescence (ECL) immunoblots. Virus coculture, polymerase chain reaction, and in situ hybridization assays revealed the systemic spread of virus as early as 1 week postinoculation in 8 of 10 animals. ECL immunoblots detected SIV-specific antibodies in mucosal samples collected 1 week postinoculation. The most dramatic increases in both total and SIV-specific IgA levels were detected in rectal secretion samples. In contrast, plasma and nonrectal mucosal samples from the same time points increased only slightly, suggesting that the most robust antibody response occurred at the portal of infection. Our results show that the SIV-infected macaque is an excellent model for studies designed to assess mucosal immune responses to primate lentivirus infections. Additional studies will assess the correlation between the antiviral protection afforded by candidate vaccines and mucosal antibody responses.

DPM2 regulates biosynthesis of dolichol phosphate-mannose in mammalian cells: correct subcellular localization and stabilization of DPM1, and binding of dolichol phosphate

Biosynthesis of glycosylphosphatidylinositol and N-glycan precursor is dependent upon a mannosyl donor, dolichol phosphate-mannose (DPM). The Thy-1negative class E mutant of mouse lymphoma and Lec15 mutant Chinese hamster ovary (CHO) cells are incapable of DPM synthesis. The class E mutant is defective in the DPM1 gene which encodes a mammalian homologue of Saccharomyces cerevisiae Dpm1p that is a DPM synthase, whereas Lec15 is a different mutant, indicating that mammalian DPM1 is not sufficient for DPM synthesis. Here we report expression cloning of a new gene, DPM2, which is defective in Lec15 cells. DPM2, an 84 amino acid membrane protein expressed in the endoplasmic reticulum (ER), makes a complex with DPM1 that is essential for the ER localization and stable expression of DPM1. Moreover, DPM2 enhances binding of dolichol phosphate, a substrate of DPM synthase. Mammalian DPM1 is catalytic because a fusion protein of DPM1 that was stably expressed in the ER synthesized DPM without DPM2. Therefore, biosynthesis of DPM in mammalian cells is regulated by DPM2.

Venous response after lidocaine administration in arm veins

We previously reported that cubital venous pressure (Pv) tended to increase initially, but this was followed by a drop in a dose-dependent response after intravenous lidocaine administration in subjects with various diseases. In this study we examined whether Pv responses after small-dose intravenous lidocaine administrations are related to the stimulating effect of lidocaine on vascular smooth muscle (VSM). In 5 subjects free of cardiovascular disease, Pv increased slightly with decreased pulsations after a 10 mg dose (p<0.01) with no change in central venous pressure. In the cinephlebographic test performed on 2 healthy volunteers, Pv increased during recovery from proximal venoconstriction caused by an injection of contrast medium mixed with 10 mg lidocaine. In 9 subjects with cardiovascular disease, deltaPv spread in the same directions (+ or -) after 5 and 10 mg drug administrations. In 6 of those tested with both drug doses, deltaPv had positive means and no significant difference was observed. Thus, Pv responses after small-dose lidocaine administrations are consistent with neither the stimulating effect of lidocaine nor with a dose-dependent response. They could be attributed to the spasmolytic effect of lidocaine on the basal tone of VSM, which could be modulated by disease conditions.

High transepidermal water loss induces fatty acid synthesis and cutaneous fatty acid-binding protein expression in rat skin

Stratum corneum lipids (SCLs) are responsible for the water barrier function (WBF) of the skin in mammals. Recent studies have indicated that epidermal lipid synthesis might be regulated by WBF of stratum corneum and that cutaneous fatty acid-binding protein (C-FABP) plays an important role in fatty acid metabolism in epidermis. To clarify the regulatory mechanism of lipid synthesis, we assessed the effects of barrier disruption induced by either acetone treatment or linoleic acid deficiency on epidermal lipid synthesis in rat. Transepidermal water loss (TEWL) was measured with an evaporimeter before and after treatment. The time course of re-establishing SCLs was examined biochemically and histochemically and the expression of C-FABP in the epidermis was immunohistochemically examined. When the rat skin was covered with a vapor-impermeable membrane after the acetone treatment removing SCLs and inducing WBF disruption, the usual recovery of SCLs was blocked and TEWL was kept high by 24 h. In the uncovered area, rapid redeposition of SCLs within 24 h was found and associated with normal compositions of epidermal lipids including sphingolipids, free fatty acids and sterol and, immunohistochemically, C-FABP was very weakly expressed in epidermis at 0.5 and 2 h, and then strongly in the whole layers at 4 h, and returned to a normal pattern by 8 h. The epidermis of the covered rat skin was kept weak in C-FABP expression by 24 h. In the linoleic acid-deficient rats, TEWL did not increase and the expression pattern of C-FABP showed no notable change until 28 weeks after initiation of the diets, indicating that C-FABP expression may not be affected by altered essential fatty acid metabolism. These results suggest that increase of TEWL itself stimulates C-FABP expression, leading to activation of fatty acid metabolism.

Threonine requirements of laying hens

In order to determine the Thr requirement of laying hens, two experiments were conducted using laying performance and plasma Thr concentration as parameters. At 29 and 39 wk of age, 100 and 600 laying hens in Experiments 1 and 2, respectively, with average BW and high egg production rate, were randomized, housed in individual cages, and given free access to water and experimental diets with five graded levels of Thr: 0.31, 0.39, 0.46, 0.54, and 0.61% for 21 d in Experiment 1 and diets with 0.31, 0.36, 0.41, 0.46 and 0.51% Thr for 58 d in Experiment 2. On the last day of the experiment, blood samples were taken for determination of plasma amino acid concentration. Feed intake and daily egg mass increased and then decreased linearly as dietary Thr increased. Plasma Thr increased slowly, then sharply with increasing dietary Thr levels. Using the broken-line model, the Thr requirements were estimated to be 0.425, 0.428, and 0.430% or 453, 456, and 458 mg/hen per d in Experiment 1 and 0.395, 0.404, and 0.400%, or 457, 467, and 462 mg/hen per d, in Experiment 2, for egg mass, feed efficiency, and plasma Thr concentration, respectively. These results indicate that the Thr requirements expressed as milligrams per hen per day as determined by plasma Thr concentration agree with those of laying performance.

[A case of autosomal dominant, pure form spastic paraplegia with thinning of the corpus callosum]

Autosomal dominant hereditary spastic paraplegia (HSP) is genetically classified into three types, all of which are characterized by insidiously progressive spasticity of the lower extremities. Patients with a complicated form of autosomal recessive HSP associated with hypoplasia of the corpus callosum have been reported by Iwabuchi et al. Here we report a 64-year-old patient with a pure form of autosomal dominant HSP with thinning of the corpus callosum. He had been well until 12 years of age, when spasticity and weakness of the lower extremities began to develop. His symptoms gradually worsened and he had difficulty in walking at the age of 44. When he was 56 years old, he visited our hospital. Eleven family members over five generations have been affected, and anticipation, i.e., an apparent decrease in age of onset, has been observed. On admission, he had mild cataracts, equinovarus and pes cavus, and neurological examination revealed spastic paraplegia. However, the intelligence test was normal, and nystagmus, ataxia of the extremities, involuntary movement, orthostatic hypotension or urinary disturbance was not observed. Trinucleotide repeat diseases, such as Huntington's disease, spinocerebellar ataxia type 1, spinocerebellar ataxia type 2, Machado-Joseph disease and dentatorubral-pallidoluysian atrophy, were excluded by DNA analysis. Brain MRI at the age of 64 revealed marked thinning of the corpus callosum. We considered this patient had a pure form of HSP. However, thinning of the corpus callosum has never been reported in autosomal dominant HSP.

Up-regulation of glucosylceramide synthase expression and activity during human keratinocyte differentiation

During keratinocyte differentiation, the glycolipid, glucosylceramide (GlcCer), is thought to be synthesized, stored in intracellular lamellar granules and eventually extruded into the intercellular space where GlcCer is hydrolyzed to ceramide, a major component of the epidermal permeability barrier. Previous studies showed that GlcCer synthase (GCS) activity increases during keratinocyte differentiation; however, the mechanism by which GCS activity is regulated was not established. In the present study, we prepared anti-peptide antibodies and amplified cDNA probes based on the cDNA sequence for human GCS (Ichikawa, S., Sakiyama, H., Suzuki, G., Hidari, K. I.-P. J., and Hirabayashi, Y. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 4638-4643) in order to study GCS expression during keratinocyte differentiation. Confluent human keratinocytes in culture were induced to terminally differentiate by elevation of Ca+2 in the medium without exogenous hormones or growth factors. GlcCer synthesis assayed in situ using a fluorescent ceramide analog increased approximately 5-fold during keratinocyte differentiation, peaking at day 6. Fluorescence microscopy studies of living keratinocytes showed that fluorescent ceramide and/or its metabolites accumulated in the Golgi in undifferentiated cells but targeted to unique vesicular structures that may be derived from the trans-Golgi region. Expression of both GCS mRNA, a approximately 3. 8-kilobase transcript on Northern blots, and GCS protein, a approximately 38-kDa polypeptide detected by Western blotting, increased dramatically (approximately 5-fold) during differentiation, reaching a maximum at about day 8. These results suggest that GCS is up-regulated at the transcriptional level during keratinocyte differentiation and provide the first direct evidence for GCS up-regulation in any cell type.

The first step of glycosylphosphatidylinositol biosynthesis is mediated by a complex of PIG-A, PIG-H, PIG-C and GPI1

Biosynthesis of glycosylphosphatidylinositol (GPI) is initiated by transfer of N-acetylglucosamine (GlcNAc) from UDP-GlcNAc to phosphatidylinositol (PI). This chemically simple step is genetically complex because three genes are required in both mammals and yeast. Mammalian PIG-A and PIG-C are homologous to yeast GPI3 and GPI2, respectively; however, mammalian PIG-H is not homologous to yeast GPI1. Here, we report cloning of a human homolog of GPI1 (hGPI1) and demonstrate that four mammalian gene products form a protein complex in the endoplasmic reticulum membrane. PIG-L, which is involved in the second step in GPI synthesis, GlcNAc-PI de-N-acetylation, did not associate with the isolated complex. The protein complex had GPI-GlcNAc transferase (GPI-GnT) activity in vitro, but did not mediate the second reaction. Bovine PI was utilized approximately 100-fold more efficiently than soybean PI as a substrate, and lyso PI was a very inefficient substrate. These results suggest that GPI-GnT recognizes the fatty acyl chains of PI. The unusually complex organization of GPI-GnT may be relevant to selective usage of PI and/or regulation.

Familial hemiplegic migraine with irreversible brain damage

Familial hemiplegic migraine (FHM) is an autosomal dominant syndrome characterized by recurrent episodes of varying degrees of hemiparesis associated with migraine. The aura including hemiparesis may be prolonged and in severe attacks may often be associated with confusion or coma. We describe a case of FHM whose aura was atypically prolonged and resulted in irreversible brain deficit which on magnetic resonance imaging (MRI) was suggestive of cortical hyperperfusion. A subsequent MRI showed left brain atrophy.

[Severe hepatic veno-occlusive disease (VOD) which was successfully treated with supportive therapy, but subsequently developed late-recurrence]

A 40-year-old man with chronic myelogenous leukemia in chronic phase received an allogeneic marrow graft from his HLA identical brother. He was conditioned with busulfan (16 mg/kg) and cyclophosphamide (120 mg/kg). Graft-versus-host disease (GVHD) prophylaxis was attempted with cyclosporine A (CYA) and methotrexate. On day 30, weight gain, ascites and hepatomegaly developed in addition to an elevation of total bilirubin (TB). He was diagnosed as having veno-occlusive disease (VOD) and treated conservatively. The TB level increased up to 20.1 mg/dl on day 66, then reduced to 2.1 mg/dl on day 129. By that time ascites and hepatomegaly also had completely resolved. However, on day 134. The TB level started to increase again, when the lesions of chronic GVHD were observed in the eye, the mouth, and the skin. CYA was started on day 142, and FK506 was substituted for CYA on day 161. Despite the improvement of oral and skin lesions, TB level continued to rise, and he died of respiratory failure due to ARDS on day 186. Autopsy revealed both acute and old hepatic VOD lesions, suggesting the occurrence of late-onset VOD which probably contributed to the liver dysfunction observed after clinical resolution of the first episode of VOD.

CT analysis of the use of the electrical impedance technique to estimate local oedema in the extremities in patients with lymphatic obstruction

The aim of the study is to establish the validity of the use of the electrical impedance technique for estimating local oedema in extremities through comparison with computed-tomography (CT) analysis. Eight healthy women (group 1) and nine women with unilateral leg oedema following chronic lymphatic obstruction (group 2) are examined sequentially utilising both methods. 'Equivalent resistivities' of extra- and intracellular fluid (RE and RI) are measured in the leg's upper portion with a multi-frequency impedance meter, and seven CT slices are taken in the same leg segments. In each slice, the ratios of interstitial fluid to subcutaneous tissue and to muscle are calculated using the CT number of plasma for interstitial fluid, and CT numbers of subcutaneous tissue and muscle of group 1 for 'normal' tissues. A decrease in RE and an increase in RI/RE, indicating extracellular fluid increase, are observed in oedematous legs in group 2 when compared with the left legs in group 1. Correspondingly, an increase in the ratios of interstitial fluid to subcutaneous tissue area and to total cross-sectional area is observed in the oedematous legs when compared with those of normal legs in CT analysis. Thus the multi-frequency impedance technique is effective in detecting local oedema in extremities.

Quick responses of plasma amino acid concentration to changes in dietary amino acid levels in rats

In order to evaluate the availability of plasma amino acid (AA) concentration as a parameter to determine AA requirements of rats within a short period, the response of the plasma AA concentration to changes in dietary AA levels was studied. In Experiment 1, to clarify whether the plasma AA concentration responded to changes in dietary AA levels and how long the response of the plasma AA concentration was maintained, 10 male rats were fed a casein diet for a 7 day period, and then the food was changed to AA diets. The serine (Ser), glycine (Gly) and threonine (Thr) levels were decreased from 120, 90 to 60% of the casein diet at 7-day intervals successively. Blood samples were taken at 2, 4 and 7 days after changing the diet, from the vena caudalis by vein puncture. In all cases, the plasma AA concentration responded to changes in dietary AA within 2 days, and the response was maintained until the 7th day. Experiment 2 was conducted to confirm that the plasma concentration of each AA responded to the changes in dietary AA levels at the first day and the responses of the plasma concentration of AA were maintained until the 4th day after changing the dietary AA levels, when the combination of metabolically unrelated AA was added. Five rats in A groups were fed diets with added arginine + Thr, histidine + methionine, lysine or isoleucine + Ser, and five rats in B groups were fed diets with added Gly + valine, leucine + phenylalanine or Thr + tyrosine + valine for a 4-day period successively. Blood samples were taken at 1 and 4 days after changing diets. Although the plasma concentrations of histidine, leucine, methionine, phenylalanine and Ser did not respond to changes in dietary AA levels, those of other AA responded at 1 day and the responses were maintained until the 4th day.

Hepatitis B virus variants in patients with acute hepatitis in whom various clinical forms develop

Ten patients who suffered from acute hepatitis with various clinical forms due to hepatitis B virus (HBV) were studied. HBV variants with a mutation in the precore region were dominant in two patients with fulminant hepatitis and in a patient with the most severe acute hepatitis. However, these mutant viruses were not detected in a patient who had the fulminant form of acute HBV infection on chronic liver damage or in most patients who had severe acute hepatitis. Furthermore, mutant viruses were also not detected in a patient with complicating myopathy and in one who had an atypical clinical course with three transaminase peaks. These results suggest that precore mutants may be involved in the pathogenesis of some cases of severe acute hepatitis, the same as for fulminant hepatitis, but not in other clinical forms of acute hepatitis.

Immunohistochemical distribution of cutaneous fatty acid-binding protein in human skin

Cutaneous fatty acid-binding protein (C-FABP) has been newly discovered from rat skin. The immunohistochemical study revealed that C-FABP is strongly expressed in rat epidermis. Recently, a highly homologous protein to rat C-FABP was found in psoriatic epidermis, which is termed psoriasis-associated fatty acid-binding protein (PA-FABP). In the present study, we investigated the expression of PA-FABP in normal and pathological human skin using immunohistochemical techniques. In normal skin, PA-FABP was expressed in basal and prickle cell layers, and more strongly in the granular cell layer. The expression pattern of PA-FABP was similar to that of C-FABP in rat skin. In psoriatic skin, PA-FABP was expressed in suprabasal layers and more strongly in more differentiated keratinocytes. In squamous cell carcinoma, PA-FABP showed very strong expression in squamous nests. These results indicate that PA-FABP is a human homologue of C-FABP. Moreover, it is suggested that C-FABP has important roles in the transport and metabolism of fatty acids in epidermis and that altered lipid metabolism may affect the proliferation and/or differentiation of keratinocyte.

Efficiency of neural differentiation of mouse P19 embryonal carcinoma cells is dependent on the seeding density

Serum-free culture conditions for retinoic acid-induced neural differentiation of mouse P19 embryonal carcinoma cells were determined for future ex vivo retroviral gene transfer and brain transplantation studies. Neural differentiation of P19 cells was dependent on the seeding densities, and both neurons and astroglia differentiated efficiently at high seeding densities (2 x 10(4) and 5 x 10(4) cells/cm2) but not at low seeding density (1 x 10(4) cells/cm2). In addition, P19 cells cultured at 5 x 10(4) cells/cm2 showed neural differentiated whether or not they were infected with Friend leukemia virus FrC6-V, which inhibited neural differentiation at 2 x 10(4) cells/cm2. These results indicate that FrC6-V-infected P19 embryonal carcinoma cells should be seeded at high density to achieve efficient neural differentiation in vitro for ex vivo gene transfer with a FrC6-V-derived retroviral vector system.