Prevalence and disease association of hepatitis G virus infection in Japan

A reverse transcriptase-polymerase chain reaction procedure (RT-PCR) for the detection of hepatitis G virus (HGV) RNA was used to examine the prevalence of HGV infection and HGV-related disease in Japan. Among 48 patients with acute non-A, B, C, D, E (non-A-E) hepatitis (five transfusion-associated cases and 43 sporadic cases), only one patient (2%), a transfusion recipient, was HGV RNA positive. Similarly, among 50 patients with established chronic non-A-E hepatitis, only two (4%) were positive for HGV RNA. These frequencies were not significantly different from those in 129 voluntary blood donors (0.8%). By contrast, HGV infection was relatively common among patients who were also infected with other hepatitis viruses. HGV co-infection or superinfection was found in seven of 53 (13%) patients with acute hepatitis C, in 15 of 126 (12%) patients with chronic hepatitis C, in three of 21 (14%) patients with acute hepatitis B and in four of 81 (5%) patients with chronic hepatitis B. Among the 29 dually infected patients, 15 (52%) had a history of blood transfusion. HGV was also detected in seven (10%) of 69 haemodialysis patients, of whom only one had a dual infection with hepatitis C virus (HCV) and an elevated aminotransferase level.

IN CONCLUSION

HGV RNA was found in only a low percentage of patients with either acute or chronic non-A-E hepatitis: HGV appears to co-infect or superinfect in 10-15% of HCV infections and in 5-15% of HBV infections; the prevalence of HGV infection (0.8%) among voluntary blood donors in Japan is similar to that for HCV infection; a history of blood transfusion was obtained in 22 (55%) of the total 40 HGV-positive subjects; and isolated HGV infection appears to have a low disease burden.

Restricted expression and function of laminin 1-binding integrins in normal and malignant oral mucosal keratinocytes

Squamous cell carcinoma of the oral cavity spreads by initial invasion of the laminin-rich basement membrane. We examined the adhesion and motility of human oral SCC cells and normal mucosal keratinocytes and found that the SCC cells readily attached and migrated on laminin 1 substrates but migrated poorly on collagen type I and fibronectin. The normal keratinocytes, however, adhered poorly to and were non-motile on laminin 1 yet readily and preferentially attached and migrated on fibronectin and collagen type I. Analysis with blocking anti-integrin antibodies showed that the SCC cells used the alpha 6 beta 1 complex to attach and migrate on laminin 1 and that this activity was confined to the E8 long arm fragment of laminin. Affinity chromatography on laminin-Sepharose columns revealed that the SCC cells, but not normal keratinocytes, expressed high levels of the alpha 6 beta 1 laminin 1 receptor. Metabolic pulse-chase analysis indicated that in contrast to the SCC cells, keratinocytes did not have a stable pool of beta 1 subunit precursor. Preferential pairing of alpha 6 with beta 4 and the deficiency in pre-beta 1 levels appear to account for the failure of keratinocytes to form significant alpha 6 beta 1 complex. Additionally, the presence of laminin 1 in co-coating experiments blocked keratinocyte adhesion to other immobilized ligands, such as collagen type I or fibronectin. This anti-adhesive effect seemed to reflect a general paralysis of cell adhesive function, since laminin 1 also diminished the adhesion of keratinocytes to substrates coated with immobilized anti-integrin subunit antibody. The inhibitory activity of laminin 1 resided in the E1' and E8 fragments, and not in the E3, E4 or G domains. Collectively, our results indicate that laminin 1 is a restrictive ligand for normal keratinocytes, apparently because of their failure to assemble and express the alpha 6 beta 1 complex or other functional laminin receptors and their sensitivity to the anti-adhesive activity of laminin itself. The elevated expression of alpha 6 beta 1 following malignant conversion of muscosal keratinocytes promotes their migration on laminin, a process important during invasion and metastasis.

Sesquiterpene O-naphthoquinones from the root bark of Ulmus davidiana

Three new sesquiterpene ortho-naphthoquinones, davidianones A, B and C, together with four known compounds, mansonones E, F, H and I, were isolated from the root bark of Ulmus davidiana. On the basis of spectral data including pulse field gradient two-dimensional NMR spectroscopy, the structures of new compounds were established as 3-hydroxymethyl-6,9-dimethylnaphtho(1,8-b,c)pyran-7,8-dione, 6-methoxycarbonyl-3,9-dimethylnaphtho(1,8-b,c)pyran-7,8-dione, 6-dimethoxymethyl-3,9-dimethylnaphtho(1.8-b,c)pyran-7,8-d ion e, respectively. Their antioxidative activities were evaluated by a thiobarbituric acid method using rat liver microsomes, with mansonone F showing the greatest activity.

Molecular cloning and disease association of hepatitis G virus: a transfusion-transmissible agent

An RNA virus, designated hepatitis G virus (HGV), was identified from the plasma of a patient with chronic hepatitis. Extension from an immunoreactive complementary DNA clone yielded the entire genome (9392 nucleotides) encoding a polyprotein of 2873 amino acids. The virus is closely related to GB virus C (GBV-C) and distantly related to hepatitis C virus, GBV-A, and GBV-B. HGV was associated with acute and chronic hepatitis. Persistent viremia was detected for up to 9 years in patients with hepatitis. The virus is transfusion-transmissible. It has a global distribution and is present within the volunteer blood donor population in the United States.

Benzastatins A, B, C, and D: new free radical scavengers from Streptomyces nitrosporeus 30643. II. Structural determination

The structures of benzastatins A, B, C, and D, new free radical scavengers, were determined by spectroscopic studies. Benzastatins A and B incorporate the para-aminobenzamide unit which is rare in fungal metabolites. Benzastatins C and D are unique alkaloids related to virantmycin; they contain the tetrahydroquinoline unit in the molecules.

Benzastatins A, B, C, and D: new free radical scavengers from Streptomyces nitrosporeus 30643. I. Taxonomy, fermentation, isolation, physico-chemical properties and biological activities

In the course of screening for free radical scavengers, rare metabolites, benzastatins A and B having aminobenzamide skeleton and benzastatins C and D having tetrahydroquinoline skeleton, were isolated from the culture broth of streptomyces nitrosporeus 30643. They showed inhibitory activity against lipid peroxidation in rat liver microsomes. In the cell assay, benzastatins C and D inhibited glutamate toxicity in N18-RE-105 cells with EC50 values of 2.0 and 5.4 microM, respectively.

Tumor cell invasion of basement membrane in vitro is regulated by amino acids

Because most cancer deaths result from disseminated disease, understanding the regulation of tumor invasion and metastasis is a central theme in tumor cell biology. Interactions between extracellular matrices (ECM) and cellular microenvironment play a crucial role in this process. We have tested selected amino acids and polyamines for their ability to regulate RL95-2 cell invasion through both intact human amniotic basement membrane and a novel human ECM (Amgel). Three major systems for neutral amino acid transport, systems L, A, and ASC, are operational in these neoplastic cells. Amino acids entering the cell via transport system A or N, i.e., (methyl amino)-isobutyrate (MeAIB) or Asn, markedly enhanced invasiveness of these human adenocarcinoma cells as measured by a standard 72-hr amnion or Amgel invasion assay. Addition of 2-amino-2-norborane carboxylic acid (BCH; 1 mM), a model substrate of the L transport system, caused a significant decrease in invasive activity when tested in the Amgel assay. Interestingly, Val lowers steady-state levels of MeAIB uptake and blocks the increase in cell invasion elicited by MeAIB. At the same time, these amino acids do not influence cell proliferation activity. Neither the charged amino acid Lys or Asp (not transported by A/N/L systems) nor the polyamines putrescine, spermidine, or spermine modulate invasiveness under similar experimental conditions. Moreover, the observed time-dependent stimulation of system A activity (cellular influx of MeAIB) by substrate depletion is prevented by the addition of actinomycin D (5 microM) or cycloheximide (100 microM), suggesting the involvement of de novo RNA and protein synthesis events in these processes. MeAIB treatment of tumor cells selectively increased the activities of key invasion-associated type IV collagenases/gelatinases. These results indicate that in the absence of defined regulators (growth factors or hormones), certain amino acids may contribute to the epigenetic control of human tumor cell invasion and, by extension, metastasis. We propose that amino acids, acting via specific signaling pathways, modulate phenotypic cell behavior by modulating the levels of key regulatory enzymatic proteins.

Symptomatic duodenal diverticulum

To determine management guidelines for symptomatic duodenal diverticulum, we reviewed medical records of 26 patients. Complicated duodenal diverticulum was the only possible cause of symptoms-abdominal pain, fever and chills, melena, vomiting-in 18 patients. Ten patients improved with conservative management, and eight patients underwent diverticulectomy with or without various other procedures. Among the eight patients, one patient who had duodenal fistula died of respiratory complications on the second postoperative day. Symptoms recurred in two patients: One had a distal common bile duct (CBD) stricture and underwent choledochojejunostomy. In the other patient a CBD stone developed 3 years later, and choledocholithotomy and choledochojejunostomy were performed. Eight patients had associated gallstone disease as well as the diverticulum. Five of the eight had a history of operation for gallstone disease; four improved with conservative treatment, and one underwent choledochojejunostomy. Two patients were thought to have an innocent diverticulum and underwent cholecystectomy and choledocholithotomy only. One patient underwent diverticulectomy and sphincteroplasty for a CBD stone and pervaterian diverticulum. In conclusion, operations for duodenal diverticulum should be reserved for seriously complicated diverticula, and the surgeon should be aware that pervaterian diverticulum can be a cause of choledocholithiasis.

Lymph node metastasis as a significant prognostic factor in early gastric cancer: analysis of 1,136 early gastric cancers

BACKGROUND

Gastric cancer is the most frequent cancer and the leading cause of death from cancer in Korea. Early gastric cancer has been defined as a gastric carcinoma confined to mucosa or submucosa, regardless of lymph node status, and has an excellent prognosis with a > 90% 5-year survival rate. From 1974 to 1992, we encountered 7,606 cases of gastric cancer and performed 6,928 gastric resections. Among them, 1,136 cases were early gastric cancer (14.9% of all gastric cancer cases and 16.4% of resected gastric cancer cases).

METHODS

A retrospective analysis of 1,136 cases of early gastric cancer was performed to evaluate the prognostic significance of clinicopathologic features (sex, age, tumor location, gross type, histologic type, depth of invasion, status of lymph node metastasis, resection type). Lymph node metastasis was classified into three groups: N(n = 0) for no lymph node metastasis; N(n = 1-3) for one to three lymph node metastases; and N(n > 3) for more than three lymph node metastases. All patients received radical total or subtotal gastrectomy with lymph node dissection.

RESULTS

In univariate and multivariate analysis of these nine factors, the only statistically significant prognostic factor was regional lymph node metastasis (p < 0.001). The others had no statistically significant association with prognosis. Lymph node metastasis was present in 178 cases (15.7%). The factors associated with the lymph node metastasis were depth of invasion and gross type [protruding type (e.g., types I, IIa)]. One hundred twenty-five of these patients had one to three lymph node metastases, and 53 cases had more than three lymph node metastases. The difference in 5-year survival rates among these groups was statistically significant: 94.5% for N(n = 0), 88.3% for N(n = 1-3), and 77.3% for N(n > 3).

CONCLUSION

We propose that for early gastric cancer, lymph node dissection is necessary in addition to gastric resection, at least in patients with a high risk of lymph node metastasis.

1991 cancer incidence in Seoul, Korea: results of the Implementation Study of the Seoul Cancer Registry

This article presents the results of the Implementation Study of the Seoul Cancer Registry, which started in July, 1991 as a population based cancer registry in Seoul, Korea. The completeness and validity of the registered data were evaluated using Mortality/Incidence ratio (M/I ratio), Histologically Verified Cases (HV%), Primary Site Uncertain (PSU%), and Age Unknown (Age UNK%). Owing to the additional active surveillance, the completeness of the data turned out to be fairly acceptable, except for the aged over 75(Mortality/Incidence ratio was over 100%). Eventhough the Seoul cancer registry(SCR) has further way to go in the completeness especially among elderly persons, the validity of SCR data was also acceptable in terms of HV%, PSU%, and Age UNK%. However, PSU% and Age UNK% might need to be further reduced to be comparable with other well established cancer registries. The age standardized incidence rates(ASR) of all cancers between July 1, 1991 and June 30, 1992 were 232.4/100,000 in males and 147.9/100,000 in females. The top five major sites of cancers in Seoul were the stomach, liver, lung, colo-rectum, and bladder in order in males, and the uterine cervix, stomach, breast, colo-rectum, and liver in females. Those 5 cancer sites comprised 68.9% and 64.7% of the total cancer incidence in males and females, respectively.

Significant prognostic factors by multivariate analysis of 3926 gastric cancer patients

Univariate and multivariate analyses of 3926 selected gastric cancer patients collected between 1981 and 1991 were made to confirm several clinicopathologic prognostic factors and to evaluate the effectiveness of postoperative immunochemotherapy with OK-432, 5-FU, and mitomycin C in stage III gastric cancer. Five-year survival rates for each category of prognostic variables were obtained; and in the univariate analysis, most of the factors (including age, depth of invasion, lymph node metastasis, location of primary tumor, histologic differentiation, and gross type except for sex) showed some significance. Multivariate analysis was conducted and verified significant prognostic factors. Depth of invasion and lymph node metastasis were found to be the most powerful factors (p < 0.001); gross type, location, and histologic differentiation were additional significant factors (p < 0.05). For postoperative treatment, immunochemosurgery was most effective in stage III patients (p < 0.05). In conclusion, we may predict a prognosis for gastric cancer more precisely on the basis of these independent prognostic factors, and immunochemosurgery may be a valuable means to treat advanced gastric cancer.

Vitronectin-driven human keratinocyte locomotion is mediated by the alpha v beta 5 integrin receptor

Vitronectin is a soluble serum factor that is known to promote epiboly of keratinocytes in explant cultures and enhance cell spreading and attachment to matrix. Recently, vitronectin was demonstrated to promote human keratinocyte locomotion. The mechanism(s) by which vitronectin enhances keratinocyte migration is unknown. In this study, we quantitated the vitronectin-driven migration of human keratinocytes in the presence of antibodies to vitronectin receptors. We found that vitronectin's effect of promoting human keratinocyte migration was inhibited by antibody-directed against the alpha v beta 5 receptor. In addition, we surface-labeled human keratinocytes, chromatographed extracts of the cell membranes on a vitronectin column, and then immunoprecipitated the bound and eluted proteins with antibodies to specific vitronectin receptors. We identified the vitronectin receptors on human keratinocytes as bands of 150,000 and 100,000 daltons without reduction and as 125,000 and 110,000 daltons under reducing conditions. Immunoprecipitation with specific antibodies identified the major receptor to be the alpha v beta 5 integrin. In addition, we quantitated vitronectin-driven migration of human keratinocytes in the presence of Arg-Gly-Asp (RGD) and control peptides. We found that the presence of RGD, but not control peptide, inhibited vitronectin-driven migration of human keratinocytes. These studies demonstrate that human keratinocytes express vitronectin receptors and use the alpha v beta 5 receptor for cellular locomotion.

Human keratinocyte migration on type IV collagen. Roles of heparin-binding site and alpha 2 beta 1 integrin

BACKGROUND

The migration of human keratinocytes is an early and important event in the re-epithelialization of cutaneous wounds. Type IV collagen, a ubiquitous basement membrane component, promotes keratinocyte migration.

EXPERIMENTAL DESIGN

In this study, we sought to identify specific sites within the type IV collagen molecule that induce keratinocyte locomotion and to characterize the cell surface receptors involved. We first examined purified fragments of the type IV collagen molecule as substrates for keratinocytes in a phagokinetic migration assay. We then tested several synthetic peptides derived from the triple-helical region of type IV collagen, as well as antibodies against specific integrin subunits, for their ability to either support or inhibit keratinocyte migration on matrices of both type IV collagen and relevant peptide derivatives.

RESULTS

Keratinocytes migrated on the triple-helical fragment to the same extent as they did on the native type IV collagen. The amino-terminal 7S and the carboxy-terminal NC1 regions of type IV collagen failed to support keratinocyte migration. In addition, Hep III peptide was active both in inhibiting keratinocyte migration on type IV collagen and in serving as a substrate matrix for migration. Peptide containing the amino acid sequence RGD did not influence cell migration on type IV collagen. A specific monoclonal antibody against the alpha 2 beta 1 integrin receptor significantly inhibited keratinocyte migration on matrices of both type IV collagen and Hep III peptide.

CONCLUSIONS

Keratinocyte migration on type IV collagen involves the interaction of the alpha 2 beta 1 receptor with the Hep III region of the type IV collagen molecule.

Prognostic significance of signet ring cell carcinoma of the stomach

A retrospective analysis of 3,702 gastric cancer patients operated on between 1981 and 1991 was carried out to compare the clinicopathological features of signet ring cell (SRC) gastric cancer with other cell types. Four hundred and fifty patients (12.2%) had signet ring cell gastric carcinoma. There was a tendency for patients with the signet ring cell gastric cancer to be younger and female, and of the middle-third part of stomach to be involved. The proportion of early gastric cancers in signet ring cell gastric cancers was 43%, which was significantly higher than in the other histological types [33% in well differentiated (WD) type, 23% in moderately differentiated (MD) type, and 13% in poorly differentiated (PD) type]. Early stage signet ring cell gastric carcinomas were less invasive in depth and had less lymph node metastasis. However, signet ring cell gastric cancers in advanced stage were more invasive and had more lymph node metastasis than other cell types. There was no significant difference in five year survival rates (5YSR) among patients with different histological cell types in early stage gastric cancers. But, in advanced gastric cancers, the prognosis for patients with the signet ring cell type was significantly worse than for the other types (SRC, 31.9% 5YSR; WD, 45.1% 5YSR; MD, 38.4% 5YSR; PD, 34.5% 5YSR) (P < 0.05), which can be explained by the finding that advanced gastric cancers with signet ring cell type have a larger tumour size, more lymph node metastasis, a deeper invasive depth and more Borrmann type 4 lesions than other histological types. This study suggests that signet ring cell gastric cancer may have a different biological behaviour.

The expression of beta 1 integrin and intercellular adhesion molecule-1 on mesangial cells and its modulation in glomerulonephritis

OBJECTIVES

This study was performed to observe the effects of conditioned media (CM) of cultured mononuclear cells (MNC) on the expression of beta 1 integrin and intercellular adhesion molecule(ICAM)-1 on mesangial cells and the modulation by TGF-beta, TNF alpha, or hydroxyl radical Also these were examined in anti-Thy mesangial proliferative GN (MsPGN) or puromycin aminonucleoside nephrosis(PAN).

METHODS

The expression of beta 1 integrin and ICAM-1 on mesangial cells was examined by ELISA and the modulation by TGF-beta, TNF alpha, or hydroxyl radical was investigated by using neutralizing antibody and dimethylthiourea. [.OH] scavenger.

RESULTS

The CM of MNC from Control suppressed the beta 1 integrin expression and thymidine incorporation and increased ICAM-1 expression on mesangial cells, compared to media alone. Especially the significant increase in ICAM-1 expression was reversed by anti-TNF alpha antibody. beta 1 integrin expression on mesangial cells was higher by the addition of CM of MNC in MsPGN than in Control, which was prevented by anti-TGF beta antibody or dimethylthiourea. ICAM-1 expression was not different among groups. Thymidine incorporation by adding CM of MNC was lower in MsPGN and PAN, which was mitigated by anti-TGF beta and anti-TNF alpha. Thus the ratio of the expression of ICAM-1 to thymidine incorporation was higher in MsPGN and PAN.

CONCLUSION

The expression of beta 1 integrin and ICAM-1, and the thymidine incorporation on mesangial cells are directly regulated by MNC, maybe through factors such as TGF beta or TNF alpha. In MsPGN, the overexpression of beta 1 integrin induced by MNC through TGF beta or hydroxyl radical on day 3 may be related to the pathogenesis.

Dibutyryl cyclic AMP modulates keratinocyte migration without alteration of integrin expression

Cyclic adenosine monophosphate (cAMP) has long been regarded as a second messenger and a regulator of human keratinocyte proliferation. It has been demonstrated that cAMP inhibits keratinocyte proliferation when used at high concentrations. Nevertheless, new recent reports have demonstrated that cAMP may stimulate or inhibit keratinocyte growth depending upon the concentration used. Studies to examine the influence of cAMP upon the migration of other cell types have been contradictory. To determine the direct effect of dibutyryl cAMP (DBcAMP) upon human keratinocyte migration, we used a quantitative locomotion assay using a wide range of DBcAMP concentrations. We found a bi-phasic effect of DBcAMP on keratinocyte migration across connective tissue matrices. Keratinocyte locomotion on the matrices was promoted at 10(-5) M and 10(-6) M of DBcAMP, but not at higher or lower concentrations. Time-course experiments demonstrated that the effect of DBcAMP on keratinocyte locomotion and proliferation occurred independently. Fluorescence-activated cell sorter analysis demonstrated that the effect of DBcAMP on the migration of human keratinocytes was independent from the modulation of integrin receptors. Although the cellular mechanisms by which DBcAMP promotes keratinocyte migration is unclear, the addition of DBcAMP or TPA to keratinocyte cultures enhanced the synthesis of a 92-kDa metalloproteinase in association with enhanced cellular migration. These observations suggest a possible link between metalloproteinase expression and cellular migration.

The prognostic significance of c-erbB-2 and p53 protein expressions in gastric carcinoma--a multivariate analysis of prognostic factors

152 curative gastrectomy specimens from patients with gastric carcinoma were examined in an attempt to assess the prognostic value of c-erbB-2 and mutant p53 protein expressions. The labeled streptavidin-biotin method was applied to routinely fixed and paraffin-embedded tissue sections, using the polyclonal and monoclonal antibodies against the c-erbB-2 protein and the mutant form p53 protein, respectively. In this examination, staining of c-erbB-2 protein was found in 9.2% of these carcinomas. The c-erbB-2 stained tumors were significantly associated with the tumors whose diameters were smaller than 5cm, and were more likely to be associated with serosal invasion and nodal involvement than the unstained ones. However, there was little association between staining of c-erbB-2 protein and clinicopathologic findings such as age, sex, location, histology, gross type, lymph node status, depth of invasion, and stage. The survival analysis of 104 patients with stage III gastric carcinoma revealed no significant association between c-erbB-2 staining status and survival duration. The 5-year survival rates of the c-erbB-2 positive group and its negative group were 21% and 28%, respectively. Positive p53 protein expression was observed in 46% of 152 carcinomas. There was no significant association between p53 expression and parameters such as age, sex, location, histology, gross type, and size. The p53 stained tumors were more likely to be associated with lymph node metastasis, serosal invasion than p53 unstained ones; but this did not reach significance. The 5-year survival rates of the p53 positive group and counter part group were 27% and 31%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Human keratinocytes make uniquely linear phagokinetic tracks

The migration of human keratinocytes is dramatically influenced by the type of extracellular matrix in contact with the cells: collagen induces the cells to produce long, linear migration tracks. In this study, a migration assay and computer-assisted morphometry were used to quantitate the extent of migration and the linearity of the migration tracks for a variety of cell types. Only human keratinocytes and HT-1080 fibrosarcoma cells produced both high levels of migration (migration index > 30) and highly linear tracks (track linearity > 4.5). Human keratinocytes and HT-1080 cells share at least two other features: both synthesize copious amounts of extracellular matrix components, and both synthesize high levels of collagenase that degrades basement membrane (type IV) collagen. However, zymogram studies of collagenase production do not yield any characteristic collagenase profile which might distinguish these two types of cells from other normal and metastatic cells.

Epidermal growth factor (EGF) promotes human keratinocyte locomotion on collagen by increasing the alpha 2 integrin subunit

The migration of human keratinocytes across the would bed is an early and critical event in the reepithelialization of cutaneous wounds. Epidermal growth factor (EGF) has been shown to accelerate the healing of fresh, split-thickness cutaneous wounds when applied topically. The mechanism(s) by which this accelerated healing occurs remains unknown. Using an assay that directly evaluates human keratinocyte locomotion without confounding the possibility of cell proliferation, we examined the influence of EGF on human keratinocyte motility. Both recombinant epidermal growth factor (rEGF) and transforming growth factor-alpha (TGF-alpha) promoted human keratinocyte locomotion when the cells were apposed to connective tissue matrices of collagen or fibronectin, important components of the wound bed. Other growth factors studied did not enhance keratinocyte migration. Blocking the EGF/TGF-alpha receptor on the cell surface of keratinocytes with specific antibody inhibited the stimulation of keratinocyte locomotion by rEGF and TGF-alpha. Flow cytometry analysis of keratinocytes migrating on type I collagen in the presence of rEGF or TGF-alpha revealed increased expression of the alpha 2 integrin subunit on the keratinocyte surface. The alpha 2 beta 1 integrin mediates keratinocyte migration on collagens type I and IV, and inhibition of migration via antibody blockade of the alpha 2 beta 1 integrin can be partially overcome by increasing the concentration of rEGF present in the medium. Our study demonstrates that the growth-independent stimulation of keratinocyte locomotion via regulation of integrin expression may be one mechanism by which EGF accelerates the reepithelialization of human cutaneous wounds.

Re-epithelialization. Human keratinocyte locomotion

Keratinocyte migration and proliferation both play a role in covering skin wounds by the process of re-epithelialization. Connective tissue components are a powerful influence on keratinocyte locomotion. The mechanisms of keratinocyte locomotion and cellular division are independent. Both connective tissue components and soluble factors may serve to enhance keratinocyte migration. In addition to the field of growth factors, we would like to suggest that there should be the recognition of an entire new class of agents called migration factors.

Sweet potato beta-amylase. Primary structure and identification of the active-site glutamyl residue

The complete amino acid sequence of a subunit of sweet potato beta-amylase, a homotetramer, was established by sequence analysis of peptides obtained by digestions with Achromobacter protease I and Staphylococcus aureus V8 protease and by cyanogen bromide cleavage of the S-carboxymethylated subunit. The subunit of the enzyme is a single polypeptide consisting of 498 amino acid residues. It showed 50-60% identity in the amino acid sequence with those of beta-amylases from soybean and barley, while it about 25% with those of three bacterial beta-amylases deduced from the cDNA sequences. Sweet potato beta-amylase was completely inactivated with 2,3-epoxypropyl alpha-D-[U-14C]glucopyranoside. Sequence analysis of the inactivated enzyme revealed that Glu187 was specifically esterified by the affinity labeling with the above reagent, proposing that Glu187 is a potent candidate involved directly in the catalysis with this plant beta-amylase.