Expression and localization of annexin V and annexin VI during limb bud formation in the rat fetus

We have investigated the expression and the localization of annexin V and annexin VI during the development of rat fetal limb buds by immunoblot and immunocytochemical analysis. Neither annexin V nor annexin VI was detectable in undifferentiated mesenchymal cells in limb buds of the day-13-day-16 rat fetus. Skeletal muscles, whose progenitor cells migrate from the somites and appeared in the limb buds at day 14, dramatically expressed annexin VI on the cell surface after differentiation from mononucleated myogenic cells into multinucleated myotubes. At day 16 both annexin V and annexin VI were found to be expressed in differentiated chondrocytes as well as in the perichondrium, a precursor of chondrocytes, whereas the compact layer of mesenchymal cells surrounding a chondrification center (precartilage) did not show any immunoreactivity for either of these proteins. The results suggest a close relationship between the expression of these annexins and cell differentiation of chondrocytes and skeletal muscles during limb but development.

Immunohistochemical findings of arterial fibrinoid necrosis in major and lingual minor salivary glands of primary Sjögren's syndrome

Arterial fibrinoid lesions in major salivary glands and lingual minor salivary glands from four autopsied patients with primary Sjögren's syndrome were studied histologically and immunohistochemically. On a morphological basis, the preceding arterial fibrinoid necrosis was regarded as medial damage, particularly of smooth muscle cells. The medial smooth muscle cells underwent vacuolated degeneration and disappeared, and resulted in full-blown fibrinoid arteritis. By means of the immunoperoxidase method the distribution of the immunoglobulins, fibrin, complement (C3), transferrin, ferritin, vimentin and lysozyme was studied. The normal arterial wall reacted with the lambda light chain of immunoglobulin, transferrin and vimentin Vacuolated degeneration of medial smooth muscle cells, regarded as the initial change in cases of vascular fibrinoid lesion, was positive for IgG, C3 and vimentin. We suggest that IgG antibody is a useful marker to detect the initial phase of arterial fibrinoid necrosis. In the foci of fibrinoid necrosis, fibrin, C3 and vimentin were detected. Among these three antibodies, only fibrin was negative in the normal arterial wall and vacuolated degenerates of medial smooth muscle cells. Mononuclear cells surrounding areas of fibrinoid necrosis stained strongly with antisera to immunoglobulins, transferrin, ferritin and vimentin, and negatively with fibrin, C3 and lysozyme antibodies.

Isolation and preliminary characterization of the Streptococcus mutans rpsJ gene

We previously reported that four putative open reading frames were identified in the regions flanking the Streptococcus mutans GS-5 fructosyltransferase gene. For one of these, ORF 4, only a small region had been isolated and the first 30 nucleotides had been sequenced. In order to determine whether this open reading frame is part of an expressed gene, we isolated a DNA fragment containing intact ORF 4 and a portion of the downstream ORF 5 by inverse polymerase chain reaction. A comparison of the deduced amino acid sequences of ORF 4 and ORF 5 with other proteins revealed that the ORF 4 and ORF 5 gene products were highly homologous to ribosomal proteins S10 and L3, respectively, of several bacteria. To identify the precise transcriptional start site for the ORF 4 gene, primer extension analysis was carried out. The results indicated initiation at a G residue with corresponding -10 and -35 regions homologous to the Escherichia coli consensus promoter sequences. These results indicate that the sequences of ORF 4 and ORF 5 are consistent with the structures of ribosomal proteins S10 and L3, respectively, and are present in a ribosomal protein operon.

Stimulation of interleukin-1beta-independent interleukin-6 production in human dental pulp cells by lipopolysaccharide

Dental pulpal infection is most commonly caused by extensive dental caries. A principal driving force behind pulpal disease response appears to lie in the immune system's response to bacteria. However, the production of interleukin (IL)-1beta and IL-6 in human dental pulp (HDP) cells in response to lipopolysaccharide (LPS) has not been well characterized. We examined IL-1beta and IL-6 production in HDP cells by challenging with LPS from Porphyromonas endodontalis, which is a Gram-negative bacteria found in root canals. Our results presented here showed that when HDP cells were stimulated by LPS, the production of IL-6 always preceded that of IL-1beta. Since the IL-6 production was observed even in the presence of the IL-1beta receptor antagonist, we concluded IL-6 production was independent of the IL-1beta molecule in LPS-stimulated HDP cells. This idea was further supported by the results obtained from RT-PCR experiments, in which IL-6 mRNA, but not IL-1beta mRNA, was present in the RNA preparation isolated from the early stage of cells.

Content and characteristics of vitamin B12 in some seaweeds

The vitamin B12 (B12) content in seven species of seaweed that are consumed frequently in Hokkaido, Japan, was microbiologically measured using Escherichia coli 215. Asakusanori (Porphyra tenera), maruba-amanori (Porphyra suborbiculata) and akaba-gin-nansou (rhodo-glossum pulcherum) showed higher B12 content than the other species, although the content varied greatly among samples in the same species. A bioautography on a thin-layer plate holding a mixture of silica gel and cellulose, differentiation of B12 and its analogues using a binding specificity of intrinsic factor and haptocorrin, and comparison of the B12 concentration determined by the radioisotope dilution assay method using the intrinsic factor as the B12-binding protein with that by the bioassay method, predominantly showed B12 in maruba-amanori and B12 analogues in wakame (Undaria pinnatifida) and akaba-gin-nansou. The B12 uptake of akaba-gin-nansou from artificial seawater was similar to that of asakusanori that contained only B12.

[Successful induction of immune tolerance and novel hemostatic effects in a hemophilia A with high-responder inhibitor by regular infusions of factor VIII]

A hemophilia A patient with high responder inhibitor had been treated by (activated) prothrombin complex concentrates (A) PCC and activated factor VII until the occurrence of intracranial bleeding at the age of 6 years. Since the inhibitor titer was decreased less than 1 Bethesda Units/ml, high dose of factor VIII was given followed by the infusions of factor VIII concentrates (100 units/kg) three times a week. In spite of previous episodes of anamnestic responses by factor VIII products before, the inhibitor titer did not increase and disappeared completely 6 months after the FVIII infusion therapy. The specific anti-factor VIII IgG subclasses of the inhibitor were IgG2 and IgG4. The inhibitor recognized both light and heavy chains. He have no bleeding episode for 6 months since the beginning of the prophylactic with factor VIII concentrates.

Detection of circulating anti-p53 antibodies in patients with colorectal carcinoma and the antibody's relation to clinical factors

PURPOSE

Mutation of the p53 tumor suppressor gene is the most common genetic alternation in colorectal carcinoma and is assessed mainly by molecular analysis of the gene sequence or by immunohistochemical analysis of p53 protein accumulation. Purpose of this study was to detect circulating antibody against p53 proteins in serum of patients with colorectal carcinoma and to evaluate its clinical significance.

METHODS

We used immunoblotting techniques to detect circulating anti-p53 antibodies. Relationship among staging, immunohistochemical expression of p53 in the primary tumor, and serum carcinoembryonic antigen level was investigated.

RESULTS

Circulating anti-p53 antibodies were detected in 32 (68 percent) of 47 patients. Antibody was found in patients at all clinical stages of disease. In 33 patients whose sera and primary tumor tissues were available for testing, 16 (48 percent) were positive for both circulating anti-p53 antibody and p53 expression in the tumor. The anti-p53 antibody test was positive in 78 and 56 percent of patients with high and normal serum carcinoembryonic antigen levels, respectively.

CONCLUSION

Detection of anti-p53 antibodies may become a new diagnostic indicator of colorectal carcinomas.

Expression of heat shock protein 70 (HSP70) and EBV latent membrane protein 1 (LMP1) in Reed-Sternberg cells of Hodgkin's disease

Tissue sections embedded in paraffin and fixed in formalin from 65 patients with Hodgkin's disease (HD) were examined for the presence of heat shock protein 70 (HSP70) and Epstein-Barr virus (EBV)-encoded latent membrane protein 1 (LMP1) using avidin-biotin immunoperoxidase complex technique. The staining results in Reed-Sternberg (R-S) cells and their variants were evaluated independently. HSP70 expression was found in R-S cells in 55 cases (85%) of HD examined and the frequency of HSP70 positive cases was significantly higher than that of HSP70 negative cases (P < 0.01). This protein was present in pathogenic cells in 9/12 cases (75%) of lymphocyte predominant Hodgkin's disease (LPHD), 21/27 cases (78%) of mixed cellularity Hodgkin's disease (MCHD), 10/10 cases (100%) of lymphocyte depleted Hodgkin's disease (LDHD) and 15/16 cases (94%) of nodular sclerosing Hodgkin's disease (NSHD). The association between HSP70 expression and HD thus appeared to be more frequent in patients wish LDHD and NSHD subtypes, although examples of HSP70-positive tumors were found in all histological subtypes. Studies of non-neoplastic lymphoid tissues demonstrated that centroblasts (large lymphocytes in germinal centers) were constantly positive; occasional histiocytes revealed variable reactivity for.

Functional expression of CD11a on CD8+ cells is suppressed in regional lymph nodes with cancer involvement in patients with gastrointestinal carcinoma

BACKGROUND

To evaluate the immunologic activity of regional lymph nodes, the phenotype of lymphocytes and the functional expression of cell adhesion molecules (CAMs) on lymph node lymphocytes (LNL-: uninvolved, LNL+: involved) were investigated in patients with gastrointestinal carcinoma.

METHODS

The lymphocyte subpopulation and the expression of CD11a, CD44, and CD29 on CD4+ and CD8+ cells in peripheral blood lymphocytes (PBL), LNL- and LNL+ derived from 37 patients with gastrointestinal carcinoma were studied. In addition, the adherence of CD8+ cells to ICAM-1 which reflects the adhesive function of CD11a, was examined, and changes in this adherence were studied by experimental coculture with cancer cells (DLD-1).

RESULTS

Although there were no differences in the overall proportion of T cells between the groups, CD8+ cells and CD16+ cells were considerably diminished in LNL+. The expression of CD11a and CD29 on CD4+ and CD8+ cells was significantly lower in LNL than in PBL, whereas the expression of CD44 showed no significant differences. The expression levels of these CAMs were almost the same in LNL- and LNL+. Only CD11a expression on CD8+ cells in LNL+ was significantly lower than that in LNL- (P < 0.005). The adherence of CD8+ cells in LNL+ to ICAM-1 was lower than that in PBL and LNL-, and was extremely enhanced by experimental coculture with cancer cells (DLD-1).

CONCLUSIONS

These data indicate that the functional expression of CD11a (LFA-1) on CD8+ T cells is suppressed in cancer-involved regional lymph nodes in patients with gastrointestinal carcinoma.

Molecular and genetic analysis of multiple changes in the levels of production of virulence factors in a subcultured variant of Streptococcus mutans

We previously isolated a variant strain, Xc100L, which shows decreased production of a surface protein antigen with a molecular mass of 190 kDa (PAc), after repeated subculturing of Streptococcus mutans strain Xc [Koga, T. et al. (1989) J.Gen. Microbiol. 135, 3199-3202]. In the present study, the levels of expression of the gtfB, gtfC, gtfD and ftf genes coding for polysaccharide-synthesizing enzymes in strain Xc100L were compared with those in strain Xc. Western blot analysis revealed multiple differences in the levels of production of these enzymes between these two strains. The amounts of the gtfB and gtfC gene products responsible for water-insoluble glucan synthesis in strain Xc100L were lower than those in strain Xc, whereas the amounts of the gtfD and ftf gene products responsible for water soluble glucan synthesis and fructan synthesis, respectively, in strain Xc100L were higher than those in strain Xc. Northern blot analysis revealed that the amounts of the four enzymes and PAc produced by strain Xc100L reflected the relative amounts of mRNAs from the genes. The chloramphenicol acetyltransferase gene was fused with each of these five genes, and the transcriptional activity of each gene in strain Xc100L was quantitatively compared with that in strain Xc. The chloramphenicol acetyltransferase assay also indicated that the phenotypic differences between strain Xc and strain Xc100L were due to differences in the transcriptional activities of the virulence genes. No differences in the nucleotide sequences of the promoter regions of the gtfB, gtfC, gtfD, ftf and pac genes were found between strain Xc and strain Xc100L. It is possible that a factor(s) affecting the levels of transcription of the multiple virulence genes exists in S. mutans.

Surgical treatment of isolated secundum atrial septal defect in patients more than 50 years old

BACKGROUND

Arrhythmia-related thromboembolic accidents continue to occur in patients even after closure of secundum atrial septal defect. Older age is usually not a contraindication to the repair of an atrial septal defect. To assess the importance of the type of management in elderly patients with atrial septal defect our clinical experience is reviewed.

METHODS

Between 1974 and 1994, 49 patients 50 years of age or older (average, 57.4 years) underwent surgical closure of secundum atrial septal defect. All patients have been followed up for 2 to 21 years (mean, 9.7 years).

RESULTS

There were no operative deaths. Functional classes in most of the patients were improved after operation. There were two cerebrovascular thromboembolic accidents with one permanent neurologic dysfunction, hemiparesis, and one septal dehiscence in the early postoperative period. One patient (2%) died of renal failure 6 years after operation, late arrhythmias developed in 3 patients (6%), 3 patients had a late stroke (6%), and 1 patient was not available for follow-up.

CONCLUSIONS

Long-term operative results are satisfactory and beneficial to the quality of life in elderly patients. Because there is no safe and effective nonsurgical alternative to surgical closure, atrial septal defect repair in elderly patients without severe pulmonary vascular disease should not be delayed once the diagnosis had been made.

Large-scale DNA typing for human platelet alloantigens by PCR-PHFA (preferential homoduplex formation assay)

Alloimmunization against human platelet alloantigens (HPA) is known to be involved in disorders such as neonatal alloimmune thrombocytopenic purpura, posttransfusion purpura, and refractoriness to platelet transfusion therapy. HPA typing is essential in diagnosis and management of patients. Therefore a reliable and speedy method is necessary for HPA typing. We have successfully applied a new DNA typing method, PCR-preferential homoduplex formation assay (PHFA) method, to typing for the HPA-1, -2, -3, -4, -5 and -6 systems. This method is based on DNA strand competition during hybridization under a precisely controlled temperature gradient between a double-labelled amplicon (standard DNA), prepared from biotin- and DNP-labelled primers, and an unlabelled amplicon (sample DNA). The results obtained by PCR-PHFA typing were in good agreement with the allotypes determined by serological typing and by other DNA typing methods. The PCR-PHFA method can be easily automated, is suitable for typing both small and large numbers of samples, and thus is applicable to routine HPA typing.

[Nonrheumatic calcification of the mitral valve in patients with stenotic calcified bicuspid aortic valve]

The pathogenesis of nonrheumatic calcification of the mitral valve was investigated by analyzing the clinical and echocardiographic characteristics of patients with mitral valvular calcification without any findings suggestive of rheumatic heart disease or infective endocarditis. Calcification of the mitral valve was observed in nine patients, who all had calcified stenotic (aortic valve area < 1 cm2) bicuspid aortic valve. Calcification of the mitral valve was localized to the basal portion of ventricular aspect of the anterior mitral leaflet and contiguous to that of the aortic valve. Mobility and thickness of the mitral leaflet was normal except for the calcified portion. Calcification of the mitral valve was not contiguous to posterior mitral annular calcification nor was related to direction of aortic regurgitant flow. In patients with calcified stenotic bicuspid aortic valve, calcification of the mitral valve was not associated with location of the two aortic cusps, aortic valve area, aortic valvular peak pressure gradient, direction of the left ventricular outflow, end-diastolic left ventricular outflow tract dimension, end-diastolic dimension of the aortic annulus, incidence of aortic regurgitation, calcification of the aortic arch, or risk factors of atherosclerosis. Six patients with mitral valvular calcification had aortic valve replacement. Preoperative coronary angiogram of these patients was normal. Calcification of the aortic valve was on the ventricular and aortic aspects. The calcification of the aortic valve, anterior mitral ring, or anterior mitral leaflet was not rheumatic in these six patients. Rheumatic disease, risk factors of atherosclerosis, mechanical stress by left ventricular outflow or aortic regurgitant flow, or mitral annular calcification did not appear to be related to mitral valvular calcification. The distribution of aortic and mitral valvular calcification suggested that the calcification of the mitral valve was due to progression of calcification of the bicuspid aortic valve.

Composite graft replacement of the aortic root in patients with Marfan's syndrome

Between October, 1979 and September 1994, 18 consecutive patients with Marfan's syndrome underwent replacement of the ascending aorta and aortic valve with a composite graft. There were 11 men and seven women; the mean age was 38.7 years. All patients had annuloaortic ectasia with significant aortic regurgitation. Ten of the 18 patients had aortic dissection. Concomitant procedures were performed in three patients. The hospital mortality rate was 17%, and two patients with concomitant procedures died early after surgery. There were three late deaths, two of which were related to late aortic complications. The actuarial 8-year survival rates in patients with and without aortic dissection were 58.3% and 77.8%, respectively. Since aortic dilatation and its complications are progressive in patients with Marfan's syndrome, improved surgical results can be obtained early in the course of the disease before cardiac disturbances and aortic dissections emerge.

Association of TAP1 and TAP2 with systemic sclerosis in Japanese

OBJECTIVE

The contribution of polymorphism of transporter associated with antigen processing 1 and 2 (TAP1 and 2) alleles to the pathogenesis of Japanese SSc was studied.

METHODS

TAP1 and TAP2 typing was carried out in 55 Japanese SSc patients and 95 normal Japanese subjects by the PCR-RFLP (restriction fragment length polymorphism) method. HLA-DR typing and HLA DRB1*15, *16 and *08 genotyping were carried out by the PCR and the PCR-SSCP (single-stranded DNA conformation polymorphism) methods, respectively.

RESULTS

The frequencies of the TAP1A and TAP2A alleles were significantly increased in SSc with diffuse scleroderma (100%, p < 0.005; 80.0%, p < 0.001, respectively) and in SSc with antitopoisomerase 1 antibody (a-Scl-70), (93.2%, p = not significant (NS); 63.6%, p < 0.05). In contrast, the TAP1B allele was significantly decreased in diffuse scleroderma (0%, p < 0.005) and SSc with a-Scl-70 (4.5%, p < 0.05), and TAP2B was decreased in diffuse scleroderma (12.5%, p < 0.01).

CONCLUSION

Association analysis among TAP1A, TAP2A and DRB1*1502 indicated that increases in TAP1A and TAP2A were not primary, but were reflective of an increase in HLA DRB1*1502 in Japanese SSc patients with diffuse scleroderma and SSc with a-Scl-70.

Gene frequencies of human platelet antigens on glycoprotein IIIa in Japanese

BACKGROUND

Polymorphism of glycoprotein IIIa on human platelets is one of the factors in alloimmunization that causes neonatal alloimmune thrombocytopenia and refractoriness to platelet transfusion.

STUDY DESIGN AND METHODS

DNA typing methods were originally developed to determine the genotypes of five human platelet antigen (HPA) systems located on glycoprotein IIIa: HPA-1, HPA-4, HPA-6W, HPA-7W and HPA-8W. The gene frequencies of these platelet antigens were determined by DNA typing of 331 unrelated Japanese donors.

RESULTS

The gene frequencies of the low-frequency antigens were 0.002, 0.011, and 0.027 for HPA-1b, HPA-4b, and HPA-6W(b), respectively. All 331 Japanese donors tested were HPA-7W(a/a) and HPA-8W(a/a). Moreover, in the present study, none of the donors tested had two or more of these low-frequency antigens.

CONCLUSION

The risk of neonatal alloimmune thrombocytopenia and refractoriness to platelet transfusion induced by the antigens of the HPA-1, HPA-7W, and HPA-8W systems was extremely rare in Japanese. However, attention must be paid to the involvement of the HPA-4 and HPA-6W systems in these clinical disorders.

Ultrastructure of the cyst wall of Sarcocystis species with canine final host in Japan

The ultrastructural characteristics of cyst wall are a useful clue to the identification of Sarcocystis species. Among the eight species examined, S. cruzi, S. sp. 1 from sheep and S. hircicanis had the thin cyst wall with long, tapered hair-like villar protrusions. The protrusions arose from the dome-like bulges of cyst wall and ran parallel to the surface. No clear ramification was observed in the tip of protrusion of these three species. S. tenella, S. capracanis, S. miescheriana, S. fayeri, and S. sp. 2 from Japanese deer had the thick cyst wall. The villar protrusions of the former three species were palisade-like in shape, but those of S. tenella and S. Capracanis were slightly thinner than those of S. miescheriana. The villar protrusions of S. fayeri and S. sp. 2 were finger-like, but those of the former species were shorter and thicker than those of the latter species. S. fayeri had many minute depressions on the surface of protrusion in a reticular pattern. Microtubules in the core of protrusion were seen in S. miescheriana, S. fayeri and S. sp. 2 but not in the other species. Microdepressions were observed on the surface of cyst wall among the protrusions in all the Sarcocystis species examined, but their function was not made clear.

Connexin 43 and the glucose transporter, GLUT1, in the ciliary body of the rat

To investigate the relationship between the gap junction protein connexin 43 and the glucose transporter GLUT1, their localization was visualized by double-immunofluorescence microscopy using frozen sections as well as immunogold staining of ultrathin frozen sections. In pigmented epithelial cells, most of the GLUT1 was localized along the plasma membrane facing the blood vessels, whereas in non-pigmented epithelial cells, it was present along the plasma membrane facing the aqueous humor. Connexin 43 was abundant in the ciliary body and localized mainly in the gap junctions connecting the pigmented and non-pigmented epithelial cells. Localization of GLUT1 and connexin 43 in the blood-aqueous barrier suggests that GLUT1, connexin 43, and GLUT1 disposed in this order could be a machinery responsible for the transport of glucose across the blood-aqueous barrier.

Autoantibodies and immunoglobulins in atomic bomb survivors with human T-lymphotropic virus type I

The association of human T-lymphotropic virus type I (HTLV-I) with autoimmune disorders was investigated on the basis of prevalence of antinuclear antibody (ANA), rheumatoid factor and anti-thyroglobulin antibody as well as immunoglobulin (Ig) serum level (IgG, IgA, and IgM). The subjects, all atomic bomb survivors, were 59 HTLV-I-seropositive people without HTLV-I-associated myelopathy or adult T-cell leukemia and 149 HTLV-I-seronegative persons. The mean serum level of IgM was higher in HTLV-I-seropositive subjects than in HTLV-I-seronegative subjects, and a significant association with HTLV-I and sex was indicated in the IgM serum level. No association with HTLV-I was indicated in the prevalence of the autoantibodies except for ANA. These results suggest some clear humoral immunity differences between HTLV-I-infected and noninfected subjects, but whether HTLV-I infection can lead to autoimmune disorders remains uncertain.

Tumour necrosis factor receptor gene expression and shedding in human whole lung tissue and pulmonary epithelium

This study aimed to investigate the expression of tumour necrosis factor receptor (TNF-R) at the gene and surface level, and its shedding in human lung tissue and a pulmonary epithelial cell line, A549. Levels of gene expression of TNF-R were evaluated by Northern blot analysis. Human lung tissue expressed both type I and type II TNF-R gene, while A549 cells expressed only type I TNF-R gene. Phorbol ester upregulated and TNF-alpha down-regulated the TNF-R gene expression in A549 cells. Consistent with these modulations of TNF-R gene expression, 125I-TNF binding capacities were increased with phorbol ester stimulation and decreased with TNF stimulation after 24 h in A549 cells. The shedding of TNF-R from A549 cells was investigated using enzyme-linked immunosorbent assay (ELISA) for soluble type I TNF-R. Not only lung tissues but also A549 cells spontaneously released soluble type I TNF-R into the culture medium. Both phorbol ester and TNF stimulation accelerated the shedding of soluble TNF-R from A549 cells. These results suggest that type I TNF-R gene expression and shedding of soluble TNF-R are differentially regulated in A549 cells. We conclude that tumour necrosis factor receptor surface expression is regulated, at least in part, at the gene expression level and shedding of soluble tumour necrosis factor receptor is modulated by inflammatory mediators, such as tumour necrosis factor in A549 cells.

Immunolocalization of GLUT1 and connexin 26 in the rat placenta

Interhemal membrane in the rat placenta is composed of three trophoblastic layers and endothelial cells. GLUT1, an isoform of the facilitated-diffusion glucose transporter, is abundant in the cells of the placental barrier, i.e., syncytiotrophoblastic layers I and II. GLUT1 is localized at the plasma membranes of the maternal-blood side of syncytiotrophoblastic layer I, and of the fetal-blood side of syncytiotrophoblastic layer II. Double-immunofluorescence microscopy has shown that connexin 26 is present between these GLUT1-positive sites, i.e., between syncytiotrophoblastic layers I and II. Immunogold electron microscopy has revealed that connexin 26 is localized in the gap junctions connecting the two layers. Connexin 26 in these layers therefore makes them functionally a single syncytial layer for the transfer of small molecules such as glucose in the rat placental barrier. These results suggest that glucose transfer in the rat placental barrier is carried out as follows: GLUT1 is used for the entry of glucose into the cytoplasm of syncytiotrophoblastic layer I, connexin 26 for the transfer of glucose from syncytiotrophoblastic layer I to syncytiotrophoblastic layer II, and GLUT1 for the exit of glucose to the fetal circulation.

p53-independent induction of apoptosis by cyclin-dependent kinase inhibition

The G1 checkpoint and terminal differentiation may be associated with apoptosis, the induction of which is in large part dependent on the presence of active p53. However, cells lacking wild-type p53 can undergo apoptotic cell death during normal development and during terminal differentiation of malignant cells. Using the specific inhibitor for cyclin-dependent kinases (cdks), we show here that an inhibition of cdk activity per se can induce apoptotic cell death during G1-S transition of the cell cycle in a p53-independent manner. The apoptotic process triggered by cdk inhibition was associated with an overriding of the G1-S boundary and was inhibited by arresting the cells in G1. These results raise the possibility that aberrant cell cycle machinery may result in self-elimination, even in the absence of p53, and further indicate that cdk activity is not necessarily required during this process.

Augmentation by phthalimides of phorbol ester-induced expression of tumor necrosis factor alpha message

N(alpha)-Phthalimidoglutarimide (thalidomide), 2-(2,6-diisopropylphenyl)-1H-isoindole-1,3-dione (PP-33) and its 4,5,6,7-tetrafluoro derivative (FPP-33) augmented 12-O-tetradecanoylphorbol 13-acetate-induced production by human leukemia HL-60 cells of both tumor necrosis factor alpha (TNF-alpha) mRNA and secreted TNF-alpha protein. Intracellular TNF-alpha protein production was increased to a lesser extent.