Detection of Epstein-Barr virus and human papillomavirus in head and neck tumors

The presence of Epstein-Barr virus (EBV) DNA and human papillomavirus (HPV) DNA in 74 head and neck tumor tissues was examined by the polymerase chain reaction and DNA sequencing analysis. EBV DNA sequence was detected in all 30 nasopharyngeal-carcinoma tissue samples and in 30 of 44 other head and neck tumor samples. HPV DNA sequence was detected in 14 of 30 nasopharyngeal-carcinoma tissue samples and in 11 of 44 other tumor samples. Coinfection of both viruses was observed in 14 nasopharyngeal-carcinoma tissue samples but only in 5 other head and neck tumor samples including 3 hypopharyngeal-carcinoma tissue samples. Our data indicate that EBV is closely associated with nasopharyngeal- carcinoma and may also be related to hypopharyngeal-carcinoma. In addition, a relatively high percentage of EBV-positive nasopharyngeal- and hypopharyngeal-carcinoma tissue specimens contained HPV sequence. The significance of the coexistence of EBV and HPV in these tumor tissues requires further study.

[Primary amyloidoma of the spine]

Amyloidosis involving the musculoskeletal system is an uncommon occurrence. The primary form is rare and only six cases involving the spine have been reported in the literature. The following case is believed to be the first reported in Taiwan. A 65-year-old male was admitted due to chronic nonspecific pain in the lower back with progressive paralysis of the lower limbs. Amyloidoma involving both thoracic and lumbar spine, never reported in the literature, was proved by histologic and histochemical studies. Serial radiographic examinations were also presented. Anterior decompression of the thoracic spine with iliac crest strut bone graft and Kaneda device fixation achieved good functional results. The symptoms and signs of spinal amyloidoma are nonspecific and difficult to diagnose; hence a correct diagnosis requires the surgeon to be extremely suspicious. A special histochemical stain is essential for this purpose. Because of the rarity, we report this case with review of the literature.

Detection of point mutations in the chloroplast genome by single-stranded conformation polymorphism analysis

Single-stranded conformation polymorphism (SSCP) analysis was used to examine the mutations of the chloroplast 16S rRNA locus of streptomycin-resistant mutants in Nicotiana plumbaginifolia. DNA fragments of 121, 517, 968 and 1578 bp, each possessing a known point mutation, were generated by polymerase chain reaction (PCR). The resulting fragments were denatured and separated by nondenaturing polyacrylamide gel electrophoresis. Compared to the patterns of the wild-type DNA fragments, the bands of the single-stranded DNA fragments of 121 and 517 bp with base changes were shifted. However, no pattern variations were detected from the DNA fragments of 968 and 1578 bp generated from both wild-type and mutants.

Detection of mutations in the p53 gene in human head and neck carcinomas by single strand conformation polymorphism analysis

Using the polymerase chain reaction (PCR)-based single strand conformation polymorphism (SSCP) analysis, we have examined the highly conserved regions of the p53 gene in 58 biopsy samples of head and neck tumors. Mutations were found in 13/58 (23%) tumor specimens, but not in 6 normal tissues. Ten of 13 mutations were due to single base changes and the remaining 3 were 1- or 8-base deletion mutants. These mutations were clustered in exons 5 and 7 and resulted in amino acid changes. Our results seem to indicate that mutations in the p53 gene contribute to a significant number of cases of the head and neck tumors including 20% of nasopharyngeal carcinoma biopsies. The relationship of Epstein-Barr virus or human papillomavirus and p53 gene mutations in this group of cancers was also analyzed and discussed.

Comparison of the anatomic distribution of stomach cancer and precancerous gastric lesions

The anatomic distribution of precancerous gastric lesions among 3,400 residents in Linqu, Shandong Province of China, was compared with the anatomic distribution of stomach cancer (SC) among 959 patients in Tokyo, Japan. The incidence of SC is high in both areas, and locations within the stomach of the precancerous and malignant lesions were classified using similar criteria. Chronic atrophic gastritis (CAG) affected 98% of the population in Linqu, with intestinal metaplasia (IM) the most severe diagnosis in 33% and dysplasia (DYS) in 20%. Neither the SC nor precancerous lesions were uniformly distributed in the stomach. Among the DYS 3% were along the greater curvature of the body, 15% along the lesser curvature of the body, 25% in the angulus, 22% along the lesser curvature of the antrum, and 34% elsewhere in the antrum. Among the SC the corresponding percentages were 2, 16, 28, 25 and 29. The similarity to the SC distribution increased gradually from CAG to IM to DYS, providing further evidence for the multistage progression of precancerous gastric lesions.

Cloning and characterization of the latent membrane protein (LMP) of a specific Epstein-Barr virus variant derived from the nasopharyngeal carcinoma in the Taiwanese population

A DNA fragment containing Epstein-Barr virus (EBV) terminal fragment sequence was obtained from a genomic library of nasopharyngeal carcinoma (NPC). One of the clones (clone 1510) contained the gene encoding latent membrane protein (LMP). Sequence analysis revealed that this gene had 95% homology with the LMP sequence of the B95-8 strain. Among the sequence variations, there was a change from G to T at nucleotide position 169,426, resulting in the loss of an XhoI site in exon 1 of the LMP gene. A pair of primers bracketing the XhoI site were designed to synthesize the EBV DNA fragment from nucleotides 169,081-169,577 by using the polymerase chain reaction (PCR) method. The PCR products were then subject to XhoI digestion and to DNA sequencing analysis. This restriction enzyme site polymorphism along with the sequence variations were also observed in 50 biopsy tissues as well as in the throat washings of 6 out of 20 healthy individuals that we examined, indicating that the EBV strain predominantly existing in these biopsy tissues was different from strains of B95-8, Jijoye or nude mouse passaged cells (C15) with an African origin, but closely resembled other nude mouse passaged CAO cells which were originally derived from China. Balb/c 3T3 cells carrying this NPC-LMP gene showed a transformed cell morphology and were tumorigenic in nude mice. The relationship between this unique type of EBV and NPC has yet to be established.

Charge-remote fragmentation during FAB-CAD-B/E linked-scan mass spectrometry of aminoethyl-triphenylphosphonium derivatives of fatty acids

The carboxyl group of fatty acids is derivatized by aminoethyl triphenylphosphonium (AETPP) bromide. Fast atom bombardment (FAB) collision-activated dissociation (CAD) B/E linked-scan mass spectrometry of these fixed-charge derivatives shows typical charge-remote fragmentation (CRF). Locations of various structural modifications in fatty acids can be recognized easily from CAD spectra of the AETPP derivatives. Because the triphenylphosphonium group localizes positive charge in the molecule, and because a key requirement for CRF is a tightly localized charge site, these preionized molecules fragment under FAB-CAD conditions more effectively than other derivatives that involve ionic bonding with metal cations or protonation of basic sites. Thus, CAD of AETPP derivatives is likely to produce more structurally informative spectra and provide an opportunity to gain additional under-standing of the CRF process. The most profound difference between the AETPP derivatives and other cations in positive mode FAB-CAD-B/E-MS is reflected in the substantial improvement of detection limits for the AETPP derivatives over those for the metal cation adducts. For several fatty acids (C10-C22) tested, the detectability can be enhanced by one to two orders of magnitude when the analysis is performed on the AETPP derivative. In addition, for the analysis of fatty acid mixtures, the FAB mass spectrum of AETPP derivatives produces a relative intensity of the molecular ion peak for each component of the mixture that more closely represents its mole fraction than does that of metal ion adducts.

'Pauci-immune' rapidly progressive glomerulonephritis associated with systemic vasculitis

'Pauci-immune' glomerulonephritis has been recognized as an important cause of rapidly progressive glomerulonephritis. The paucity of immune deposits can be separated from the other two major immunohistologic variants of crescentic glomerulonephritis, ie, antiglomerular basement membrane (GBM) antibody-mediated and immune complex-mediated glomerulonephritis. Here we describe the case of a 42-year-old woman with pauci-immune' glomerulonephritis and vasculitis presenting as rapidly progressive renal failure with characteristic pathologic and immunohistologic findings. And in this case, despite oliguria and rapid deterioration of renal function, the renal function recovered partially and continued to be stabilized with a favourable response to hemodialysis and combined system immunosuppressive therapy.

The primary structures of growth hormones of three cyprinid species: bighead carp, silver carp, and grass carp

The primary structures of growth hormone (GH) of three cyprinid species, bighead carp, silver carp, and grass carp, were determined by a chemical method and/or by molecular cloning. The bighead carp GH was extracted from pituitary tissue by use of an alkaline medium, then successively purified by gel filtration, hydrophobic interaction column chromatography, and reverse-phase high-pressure liquid chromatography. The primary structure of bighead carp GH determined chemically is identical to that deduced from the cDNA nucleotide sequence. By molecular cloning, the primary structures of silver carp and grass carp GHs were also determined. The GHs of these three cyprinid species all contain 188 amino acid residues and their sequences are identical. When four of the five cysteines of cyprinid GHs were arranged to match the same positions of cysteines of other vertebrate GHs, a maximally matched alignment was achieved. Among fishes, GHs are relatively conserved within the same order (82 to 100% identity) but they are more diversified between orders (49 to 68% identity). In further comparison, fish GHs are even more different from tetrapod GHs (37 to 58% identity). Although the primary structures of vertebrate GHs are relatively variable, four homologous sequences, notably one located at the C-terminal, are found.

[The comparison of microleakage among three different dentin bonding agents in class V cavities]

The use of the etching technique and an enamel bonding agent may effectively reduce microleakage of the cavity wall. However, the reduction of marginal leakage relating to class V cavities, is still unsatisfactory according to the dental literature. Due to the structural difference between the dentin and the enamel, though many new dentin bonding agents have been developed lately, none of them work perfectly. In this experiment, the "silver staining technique" was used to investigate the degree of microleakage in class V resin restorations which were bonded with 3 different dentin bonding agents (Scotchbond, Scotchbond 2 and Denthesive). The sample consists of 21 caries free human molars which were divided into 3 groups: 1) Scotchbond v. s. Scotchbond 2, 2) Scotchbond v. s. Denthesive, 3) Scotchbond 2 v. s. Denthesive. Both buccal and lingual surfaces were prepared for class V cavities. The cavities were then filled with composite resin Silux, and immersed in 50% silver nitrate solution for 2 hours, and followed by washing with distilled water. After that these teeth were immersed in photodeveloping solution under the fluorescent light for 3 hours. On finishing, they were washed again, sectioned vertically into mesial and distal halves with a Isomet sectioner and put under a microscope and evaluated for the degree of microleakage with Dr. Going's method. On statistical analysis, the results of this study showed that the degree of microleakage was not significantly different among the 3 dentin bonding agents in class V resin restorations, either on the gingival wall or the occlusal wall.

Cloning of an Erwinia herbicola gene necessary for gluconic acid production and enhanced mineral phosphate solubilization in Escherichia coli HB101: nucleotide sequence and probable involvement in biosynthesis of the coenzyme pyrroloquinoline quinone

Escherichia coli is capable of synthesizing the apo-glucose dehydrogenase enzyme (GDH) but not the cofactor pyrroloquinoline quinone (PQQ), which is essential for formation of the holoenzyme. Therefore, in the absence of exogenous PQQ, E. coli does not produce gluconic acid. Evidence is presented to show that the expression of an Erwinia herbicola gene in E. coli HB101(pMCG898) resulted in the production of gluconic acid, which, in turn, implied PQQ biosynthesis. Transposon mutagenesis showed that the essential gene or locus was within a 1.8-kb region of a 4.5-kb insert of the plasmid pMCG898. This 1.8-kb region contained only one apparent open reading frame. In this paper, we present the nucleotide sequence of this open reading frame, a 1,134-bp DNA fragment coding for a protein with an M(r) of 42,160. The deduced sequence of this protein had a high degree of homology with that of gene III (M(r), 43,600) of a PQQ synthase gene complex from Acinetobacter calcoaceticus previously identified by Goosen et al. (J. Bacteriol. 171:447-455, 1989). In minicell analysis, pMCG898 encoded a protein with an M(r) of 41,000. These data indicate that E. coli HB101(pMCG898) produced the GDH-PQQ holoenzyme, which, in turn, catalyzed the oxidation of glucose to gluconic acid in the periplasmic space. As a result of the gluconic acid production, E. coli HB101(pMCG898) showed an enhanced mineral phosphate-solubilizing phenotype due to acid dissolution of the hydroxyapatite substrate.

Direct sequencing of tobacco chloroplast genome by the polymerase chain reaction

We have developed a polymerase chain reaction (PCR) method for sequencing of tobacco chloroplast genome. In a mixture containing chloroplast DNA, 5'-end-labeled oligonucleotide primer, Taq DNA polymerase and reaction buffer, we were able to sequence a segment of chloroplast 16S rRNA gene. The results showed that the 750 bp of DNA sequenced were identical to the sequence reported, indicating that direct sequencing method that we have developed is useful for the sequencing of chloroplast genome. To analyze the chloroplast genome more rapidly in those in vitro grown plantlets, we also developed a simple method which is applicable for the amplifications and sequencing of chloroplast 16S rRNA fragment from either 0.15 g of tobacco leaf or stem tissue. The readable sequences obtained from the presented methods were consistent with the published sequence.

Cigarette smoking and other risk factors for progression of precancerous stomach lesions

BACKGROUND

Stomach cancer is generally thought to evolve through a series of gastric mucosal changes, but the determinants of the precancerous lesions are not well understood.

PURPOSE

Our purpose was to assess risk factors for intestinal metaplasia and gastric dysplasia arising from chronic atrophic gastritis in a general population at high risk for stomach cancer.

METHODS

A population-based gastroscopic screening of more than 3000 residents was conducted in a county in China with one of the world's highest rates of stomach cancer. Information on the lifestyle and other characteristics of the participants was obtained by interview, and responses were compared between those in whom the most advanced gastric lesion was dysplasia or intestinal metaplasia versus those with chronic atrophic gastritis.

RESULTS

Cigarette smoking was found to nearly double the risk of transition to dysplasia and to be a mild risk factor for intestinal metaplasia. Smoking accounted almost entirely for the 55% higher prevalence of dysplasia among men than among women. Risk of transition to dysplasia had a weak association with several dietary factors and was increased among those participants with a family history of stomach cancer and with blood type A.

CONCLUSIONS

The findings provide strong evidence for a role of tobacco consumption and offer clues to other environmental and genetic factors involved in the process of gastric carcinogenesis.

Estimating the potential of sugarcane families to produce elite genotypes using univariate cross prediction methods

A quick, accurate method to determine the potential of a sugarcane (Saccharum spp.) cross to produce elite progeny is needed for maximizing genetic gain. Development of a practical cross appraisal method was initiated by evaluating 1,800 progeny from 15 crosses among 23 parents at two intrarow plant spacings (41 cm and 82 cm). Plant spacing was examined for its affect on stool weight variability. The goals were to identify the most reliable and/or easily obtained cross appraisal statistic and to determine the earliest breeding program stage and crop to collect these statistics. Three tests, on plant cane (PC) and first ratoon (FR) single stool seedlings and clonal plant cane plots, were conducted. Four statistics, the family mean, the estimated elite proportion (PROB), the observed elite proportion, and the best linear unbiased predictor (BLUP) were estimated and examined for each cross. These statistics were strongly correlated within each test (0.69≤r≤1.00). Family worth estimates based on single stool data were moderately correlated (ca. range 0.5≤r≤0.7) to the family worth estimates based on clonal plots.The research suggested that the potential of a cross to produce elite progeny for a trait could be accurately predicted by the cross mean of that trait. Data for the mean were the most easily obtained and, hence, would be the most practical family appraisal statistic to use in a breeding program. Correlations of statistics among the PC and FR seedlings and the clonal plots showed that the PC estimates of Brix, stalk weight, and its components, stalk length and stalk diameter, could be used for cross appraisal. Genotypic selection by the Louisiana Sugarcane Variety Development Program (LSVDP) occurs among the FR seedlings. FR stalk number and PC Brix and stalk weight data could be used to perform family selection prior to the currently practiced individual plant selection. The benefits of family selection to the LSVDP were demonstrated by the expected genetic gains for two selection scenarios. The gains were consistently larger for an initial 50% family selection and subsequent 20% individual selection than they were for simple individual selection at a 10% selection intensity. Our research also suggests that the use of a wider intrarow spacing may improve the ability to discern among seedlings due to its enhancement of stool weight variability.

Molecular cloning of silver carp and bighead carp prolactin

The cDNAs encoding the prolactin of silver carp (scPRL) and bighead carp (bcPRL) have been cloned. Deduced from the nucleotide sequences, both scPRL and bcPRL are composed of 187 amino acid residues. Only one residue is different between scPRL and bcPRL. Homology analysis indicates that scPRL and bcPRL are highly homologous to carp PRL (97%), relatively conserved in relation to PRLs of salmon, trout, and tilapia (64-69%), and diversified from avian and mammalian PRL (30-35%). Similar to PRLs of other species of fish, scPRL and bcPRL lack the first 12 N-terminal residues of avian and mammalian PRLs.

Estimating the potential of sugarcane families to produce elite genotypes using bivariate prediction methods

Three bivariate statistical methods to predict the family potential to produce elite progeny were studied to improve the efficiency of a sugarcane (Saccharum spp.) breeding program. Progeny from 15 piparental crosses were evaluated in plant cane and first ratoon seedlings, and in clonal plant cane plots during 1989 and 1990. The bivariate predictions of Brix combined with cane yield components (stalk number, stalk weight, stalk diameter, stalk length, and stool weight) were investigated. The best linear unbiased predictors (BLUPs) and the sum of ranks based on family mean values of two traits (RANK) were repeatable among tests in the estimation of family potential. Bivariate normal probabilities (PROB) estimated with family means, phenotypic standard deviations, and genetic correlations generally demonstrated poor repeatability among tests. The three statistical predictions were compared with the progeny selection rate within the crosses through three selection stages. Predictions were not correlated to the selection rates of eight crosses with smaller initial progeny populations (< 500 progeny). However, when the predictions were compared with the 7 of 15 families over which 1,000 progeny for each cross had been evaluated, the rankings based on BLUP and RANK bivariate predictions of Brix and stool weight identified the better crosses. PROB was inconsistent in this regard. Early selection work is highly subjective. We speculate that near-random selection occurs for stalk number at the initial selection stage and that the high selection rate at this stage (≈5%) generates a first clonal population (10 to 25) that is too small to accurately base selection rates for stalk number. Larger initial progeny populations produce sufficiently large clonal populations (>50) to appraise crosses using selection rates. The study suggested that family evaluations for breeding programs can use bivariate predictions. The comparative ease of calculating the RANK estimate versus the BLUP along with the absence of any apparent loss of predictive value suggests that the RANK method would be the most suitable statistic to use for bivariate predictions.

Chromosomal assignments of mouse connexin genes, coding for gap junctional proteins, by somatic cell hybridization

The connexin genes Cx31 and Cx45 coding for proteins of gap junctional subunits have been assigned to mouse chromosomes 4 and 11 by Southern blot hybridization of specific gene probes to DNA from mouse x Chinese hamster somatic cell hybrids. In addition, our results confirm the recent assignment of mouse connexin genes Cx26, Cx32, Cx37, Cx40, Cx43, and Cx46 to mouse chromosomes 14, X, 4, 3, 10, and 14, respectively, by analysis of interspecific backcrosses and by somatic cell hybridization. Our assignment of the Cx31 gene to mouse chromosome 4 locates the fourth connexin gene on this mouse chromosome to which the genes for Cx31.1, Cx37, and Cx30.3 have previously been assigned. Interestingly three of them (coding for Cx31, Cx31.1, and Cx30.3) are preferentially expressed in skin. Possibly some of the connexin genes clustered on mouse chromosome 4 may be regulated coordinately.

Distribution of type A and type B EBV in normal individuals and patients with head and neck carcinomas in Taiwan

The subtypes of Epstein-Barr virus (EBV) according to the EBNA 2 gene were investigated in Taiwan by the polymerase chain reaction (PCR) and by Southern blot hybridization. The materials included 53 nasopharyngeal carcinoma (NPC) biopsies, 49 other head and neck cancers and 32 throat washings of normal individuals. EBV DNA was found in all NPC biopsies, 27 of 49 other head and neck carcinomas and 81% of normal individuals. Type A EBV was the predominant type of EBV in both normal individuals and patients with head and neck carcinomas in Taiwan. Type B EBV or coexistence of the A and B types comprised a small number of samples in this study.

Peptidoglycan composition of a highly methicillin-resistant Staphylococcus aureus strain. The role of penicillin binding protein 2A

All clinical isolates of methicillin-resistant Staphylococcus aureus contain an extra penicillin binding protein (PBP) 2A in addition to four PBPs present in all staphylococcal strains. This extra PBP is thought to be a transpeptidase essential for the continued cell wall synthesis and growth in the presence of beta-lactam antibiotics. As an approach of testing this hypothesis we compared the muropeptide composition of cell walls of a highly methicillin-resistant S. aureus strain containing PBP2A and its isogenic Tn551 derivative with reduced methicillin resistance, which contained no PBP2A because of the insertional inactivation of the PBP2A gene. Purified cell walls were hydrolyzed into muropeptides which were subsequently resolved by reversed-phase high-performance liquid chromatography and identified by chemical and mass spectrometric analysis. The peptidoglycan composition of the two strains were identical. Both peptidoglycans were highly cross-linked mainly through pentaglycine cross-bridges, although other, chemically distinct peptide cross-bridges were also present including mono-, tri-, and tetraglycine; alanine; and alanyl-tetraglycine. Our experiments provided no experimental data for a unique transpeptidase activity associated with PBP2A.

Peptidoglycan composition in heterogeneous Tn551 mutants of a methicillin-resistant Staphylococcus aureus strain

It was shown that Tn551 inactivation of two chromosomal (so-called auxiliary) loci other than the mec gene result in a dramatic reduction of methicillin resistance and decreased cell wall turnover and autolytic capacity in a methicillin-resistant Staphylococcus aureus strain (de Jonge, B. L. M., de Lencastre, H., and Tomasz, A. (1990) J. Bacteriol. 173, 1105-1110). To understand the mechanistic basis of these phenomena we have examined the status of the autolytic enzymes and the muropeptide composition of peptidoglycan using reversed-phase high-performance liquid chromatography and mass spectral analyses. While no differences could be detected in the number of autolytic hydrolases, the mutants showed major changes in peptidoglycan composition. Nine prominent muropeptides of the parental strain each carrying a pentaglycyl substituent were missing from the cell wall of one group of mutants. The second mutant lacked four parental muropeptides which were composed of the unsubstituted disaccharide pentapeptide and its alanyl-tetraglycine derivative. The auxiliary genes are genetic determinants involved with the biosynthesis of peptidoglycan precursors, the presence of which in the cell wall may be needed for optimal cell wall turnover.

Increased expression of alpha IIb beta 3 integrin in subpopulations of murine melanoma cells with high lung-colonizing ability

Four subpopulations of B16 amelanotic melanoma cells, possessing different abilities to induce platelet aggregation (TCIPA) and to form lung colonies, were isolated by centrifugal elutriation. The expression of alpha IIb beta 3, alpha v beta 3 and alpha 5 beta 1 integrins was examined in the 4 subpopulations in order to determine the relationship between integrin receptor expression and tumor-cell metastatic potential. The mRNA of alpha IIb, alpha 5, beta 1 and beta 3 was detectable in the 4 subpopulations by Northern blotting. A gradual increase in mRNAs and cell-surface immunoreactivity of the alpha IIb beta 3 receptor, but not in their gene copies, was observed from the low to the high metastatic subpopulations. The ability of tumor cells to adhere to fibronectin and subendothelial matrix (SEM) increased in parallel. In the high metastatic cells, the alpha IIb beta 3 receptors, but not the alpha 5 beta 1 receptors, were localized to focal adhesion plaques. Incubation of the high metastatic cells with alpha IIb beta 3-specific antibodies reduced their matrix adhesion, TCIPA and lung-colonizing abilities. In contrast, in the low met- astatic cells, SEM adhesion and lung-colony formation were not affected by anti-alpha IIb beta 3 antibody treatment. Incubation of either the low or the high metastatic subpopulation with an alpha 5 beta 1-specific antibody had no effect in vitro and showed a slight inhibition of lung colonization in vivo. Our results suggest that several phenotypic characteristics of the enhanced metastatic potential of B16a subpopulations may be mediated by increased expression of alpha IIb beta 3 receptors and that expression of these receptors may be regulated at the transcriptional level.

Isolation and sequence analysis of carp gonadotropin beta-subunit gene

Using the cDNA encoding the beta subunit of carp gonadotropin (cGTH-beta) as a probe, 14 clones containing cGTH-beta gene have been isolated from a carp genomic library. Nucleotide sequence analysis indicated that the transcriptional unit of the cGTH-beta gene is 1.2 Kb. Similar to mammalian GTH-beta genes, cGTH-beta gene contains three exons and two introns. The locations of the exon/intron junctions also correspond to those of mammalian GTH-beta gene. Using the primer extension assay, the start site of transcription was determined to be 35 or 37 bp upstream from the translation initiation codon. The TATAA box is present in the 5' flanking region of the gene, 21 bp upstream from the start site of transcription. Three polyadenylation signals, AATAAA, are located in the 3' noncoding region, 111, 430, and 442 bp downstream from the stop codon of translation, respectively.

Thrombotic thrombocytopenic purpura-like syndrome associated with systemic lupus erythematosus--combined treatment with plasmapheresis and fresh frozen plasma infusion

We report on a patient with systemic lupus erythematosus, who, during the course of the illness, developed thrombotic thrombocytopenic purpura. In this case, the coexistence of these two conditions was confirmed by laboratory and pathologic findings. The infusion of fresh frozen plasma with plasmapheresis reversed the course of thrombotic thrombocytopenic purpura.

Organization and nucleotide sequence of carp gonadotropin α subunit genes

We have used PCR to amplify and align the sequence of two genes encoding cGTH alpha. Both genes comprise four exons and three introns. The organization of cGTH alpha genes is very similar to that of mammalian GTH alpha genes. However, the cGTH alpha genes only span a region of 1.2 kb which is much smaller than those mammalian GTH alpha genes.

Distribution of type A and type B EBV in patients with nasopharyngeal carcinoma

The subtypes of Epstein-Barr virus (EBV) according to EBNA 2 genes were investigated in 53 nasopharyngeal carcinoma (NPC) biopsies in Taiwan by polymerase chain reaction (PCR) and by Southern blot hybridization method. EBV DNA was found present in all NPC biopsies. Type A was the predominant type and comprised of 94.3% of the EBV of NPC. Type B or coinfection of type A and type B comprised of only 3.8% and 1.9% respectively.

Regioselective chloride ion loss from chlorine-37 enriched polychlorodibenzofurans by negative-ion mass spectrometry

Regiospecific chlorine-37 enriched dichloro-, trichloro-, tetrachloro-, and pentachlorodibenzofuran isomers were investigated under electron capture negative-ion mass spectrometry (ECNIMS) conditions. The relative chloride ion loss from the enriched positions was determined from the chloride-37 and chloride-35 ion abundances after correcting for the isotopic enrichment. Regioselective chloride anion losses were observed with the carbon 3-chlorine bond (beta-chlorine) generally found to be the most labile. The carbon-chlorine bond cleavages can be loosely associated with calculated carbon-chlorine bond residual charges.

Rapid detection of hog cholera virus in tissues by the polymerase chain reaction

A rapid method for the detection of hog cholera virus (HCV) in infected tissues, using polymerase chain reaction (PCR) was developed. Total RNA isolated from HCV-infected tissues was reverse transcribed with AMV reverse transcriptase and the resulting complementary DNA was amplified by Taq DNA polymerase in the presence of two HCV-specific primers. The amplified DNA fragment was detected by agarose gel electrophoresis. The sensitivity of this method was at 10(4) TCID50 of HCV. The sensitivity increased approximately 1000-fold when the DNA was reamplified with a set of nested primers. DNA sequencing analysis of the PCR products revealed that the HCV sequence amplified from a local field isolate was highly homologous to the HCV Alfort strain. This method may be useful for pathological and epidemiological studies of HCV in pigs.

Expression of perforin by natural killer cells within first trimester endometrium in humans

The lymphocyte pore-forming protein (PFP)--perforin, also named cytolysin--is a potent mediator of cytotoxicity found in the granules of cytotoxic T lymphocytes and natural killer (NK) cells. Granulated metrial gland (GMG) cells found in the pregnant mouse uterus express perforin and are thought to be highly activated cytolytic lymphocytes related to NK cells. Their role in pregnancy is unknown. Human endometrial granulocytes (EGs) are phenotypically similar to murine GMG cells and, like them, express NK cell markers. However, up to now it was not known whether EGs also express perforin. By means of immunohistochemical analysis, using antisera specific for perforin and monoclonal antibodies to CD56 (NKH-1), CD2 (T11), CD3 (Leu-4), CD4 (Leu-3a), and CD8 (OKT-8), we demonstrated that perforin is present in EGs in the decidualized endometrial stroma and decidual tissue of first-trimester gestational endometrium. In fact, double immunohistochemical labeling demonstrated the co-expression of perforin and NKH-1. This population also expressed some T-cell surface antigens (Leu-4 and T11), but not Leu-3a or OKT-8. Chorionic villi, in contrast, lack perforin+ cells. The presence of a potent cytolytic mediator in NK-like cells in both murine and human pregnant uterus raises the issue of the function of such cells in pregnancy.

Expression of two forms of carp gonadotropin alpha subunit in insect cells by recombinant baculovirus

There are two types of cDNA clones (designated alpha 1 and alpha 2) encoding the alpha subunit of carp gonadotropin. These two cDNAs are derived from different genes and encode proteins that differ by seven amino acid residues (three in the signal peptide and four in the mature polypeptide). Expression of these two cDNAs in insect cells by recombinant baculovirus revealed that the alpha 1 subunit, after noncovalent association with the beta subunit, has the same potency as the native alpha subunit purified from the pituitary. In contrast, the alpha 2 subunit can associate with the beta subunit, but only to form an inactive gonadotropin. Competition of the alpha 2 subunit with the alpha 1 subunit for association with the beta subunit decreases the gonadotropin activity of the alpha/beta complex. In addition, both alpha 1 and alpha 2 subunits are secreted into the culture medium by insect cells and have an apparent molecular mass approximately 5 kDa higher than that of the native alpha subunit. These results indicate that the insect cell-derived alpha 1 subunit is biologically active and that those four amino acid changes in the mature of alpha 2 protein affect the biological activity and thus provide valuable clues for the study of the structure-function relationship of the alpha subunit of glycoprotein hormones.

Human aortic proteoglycans of subjects from districts of high and low prevalence of atherosclerosis in China

The contents of three species of proteoglycans (PGs), heparan sulfate PG(HSPG), chondroitin sulfate PG(CSPG) and dermatan sulfate chondroitin sulfate PG(DSCSPG), in human thoracic aortas of subjects from districts of high (Beijin, in North China) and low (Nanning, in South China) prevalence of atherosclerosis in China were quantitated. Higher aortic HSPG and DSCSPG (but lower DS) in samples from Nanning than those from Beijing might be implicated in the lower prevalence of atherosclerosis in the former.

The efficacy of a combination administration of gonadotropin-releasing hormone agonist and gonadotropins for controlled ovarian hyperstimulation in IVF program

In 105 patients with the past history of poor response to the previous controlled ovarian hyperstimulation (COH) due to poor follicular growth or premature LH surge, the efficacy of pituitary suppression with gonadotropin-releasing hormone agonist (GnRHa) in IVF/GIFT program was evaluated in 112 cycles of COH using a combination regimen of leuprolide acetate (Lupron) and FSH/hMG or pure FSH from May to December, 1989. After suppression phase, serum E2 and progesterone levels decreased significantly, but there was no change in serum LH and FSH levels. There was no occurrence of premature LH surge during COH. Eleven cycles (9.8%) were cancelled, and 3 cycles (3.0%) failed in the transvaginal oocytes retrieval. The 7.00 +/- 3.32 follicles (FD greater than or equal to 12 mm) were observed, and 6.11 +/- 4.15 oocytes were retrieved. The 3.59 +/- 2.57 oocytes were fertilized and cleaved with the cleavage rate of 55.7%. In 83 IVF patients, 4.08 +/- 2.39 embryos were transferred, and 16 pregnancies were obtained with the pregnancy rate per ET of 19.3%. In 6 GIFT patients, 7.83 +/- 3.31 oocytes were available for transfer. When compared with the previous 108 cycles, the cancellation rate during COH was decreased and all the parameters of the outcome of COH including the pregnancy rate were increased. These data suggest that GnRHa therapy for pituitary suppression is an effective adjunct to the current gonadotropin regimens for COH in IVF/GIFT and can increase the probability of oocytes retrieval and pregnancy, especially in the previous poor responders.

Detection of Epstein-Barr virus DNA sequences in nasopharyngeal carcinoma cells by enzymatic DNA amplification

The presence of Epstein-Barr virus (EBV) DNA sequences was examined by the polymerase chain reaction in 50 nasopharyngeal carcinoma (NPC) biopsy specimens and in two primary epithelial tumor cell cultures derived from patients with NPC. The detection limit was a single EBV genome equivalent by agarose gel electrophoresis followed by Southern blot analysis of the amplified products. EBV DNA sequences were detected in all 41 undifferentiated NPC cell specimens, in 2 of 4 moderately differentiated NPC cell specimens, and in 3 of 5 keratinized NPC cell specimens. Undifferentiated NPC cells were also found to contain higher copy numbers of EBV than cells of the other two types of NPC. Our data suggest that EBV replication may be closely associated with the differentiation of NPC tumor cells. The results also demonstrated a sensitive and specific method for the detection of EBV DNA sequences in NPC tumor cells.

Cathepsin B to cysteine proteinase inhibitor balance in metastatic cell subpopulations isolated from murine tumors

Our laboratories have previously demonstrated that the malignancy of human and animal tumors is associated with increases in cathepsin B activity, due in part to increases in cathepsin B-specific RNA transcripts and in part to decreased regulation by the endogenous low molecular weight cysteine proteinase inhibitors (CPIs). In this study we have extended these observations to tumor cell subpopulations of B16 amelanotic melanoma (B16a) and Lewis lung carcinoma (3LL) isolated by centrifugal elutriation. B16a subpopulations exhibited a 10-fold differential in lung colonization potential, whereas 3LL subpopulations exhibited no differential. In the B16a subpopulations, cathepsin B activities, total cellular and plasma membrane-associated, corresponded positively (4- and 10-fold increase, respectively) with their lung colonization potentials. CPI activities, total cellular and plasma membrane-associated, corresponded inversely (2- and 5-fold decrease, respectively) with the lung colonization potential of the B16a subpopulations. In the 3LL subpopulations, neither cathepsin B nor CPI activities changed. In the plasma membrane fractions of all 3LL subpopulations the ratio of cathepsin B activity to CPI activity was less than 1, whereas in the plasma membrane fractions of all B16a subpopulations the ratio was 1 or greater. In the plasma membrane fractions of the B16a subpopulations of higher lung colonization potential the ratios were 2.5 and 7, indicating that the levels of endogenous CPIs in these fractions may not be sufficient to regulate cathepsin B activity. Cathepsin B mRNA levels were not increased in the B16a subpopulations expressing increased cathepsin B activity. Thus increased cathepsin B activity in these subpopulations was apparently due not to increased synthesis but to decreased regulation by the endogenous CPIs. These results suggest that membrane-associated cathepsin B and CPIs may both play a role in the expression of the experimental metastatic phenotype.

Oocyte donation program using a simplified hormonal regimen

It has been well recognized that both the synchronization of luteinizing hormone (LH) surge between the donor and the recipient for normally cycling women and the complex steroid replacement regimen given on a sequential and incremental basis for women with primary or secondary ovarian failure are two important aspects in oocyte donation. In oocyte donation program at SNUH, a simplified hormonal regimen applicable both to normally cycling women and to those with ovarian failure which consisted of administering 2 mg estradiol (E2) valerate orally 3 times a day augmented with 100 mg progesterone (P) in oil intramuscularly daily starting on the day preceding the oocyte retrieval from the donor was utilized. From July 1988 to December 1989 at SNUH, 11 cycles of oocyte donation program in 10 infertile patients were undertaken and 5 patients succeeded in pregnancy.

Purification, characterization, and molecular cloning of gonadotropin subunits of silver carp (Hypophthalmichthys molitrix)

The alpha and beta subunit of silver carp gonadotropin (scGTH-alpha and scGTH-beta) were isolated by high-performance liquid chromatography. Heterogeneity of N-terminal amino acid sequence was observed in scGTH-alpha but not in scGTH-beta. For determining the complete primary structures of scGTH-alpha and scGTH-beta, their cDNAs were cloned. Combining the data of N- and C-terminal sequences determined from proteins and the amino acid sequences deduced from cDNAs, we infer that scGTH-alpha consists of 95 and/or 93 residues and scGTH-beta consists of 115 residues. Both scGTH-alpha and scGTH-beta are glycoprotein. Their carbohydrate content is about 20 g per 100 g protein. The molecular weights of scGTH-alpha and scGTH-beta were calculated to be 12,700 and 15,700 Da, respectively. The amino acid sequences of scGTH-alpha and scGTH-beta are very similar to those of the corresponding subunit of carp GTH, different in only 2 and 4 residues, respectively. In addition, a high extent of homology (70%) was also observed between the alpha subunits of fish and mammalian GTHs. In the case of beta subunit, homology among various species of fish (75 to 98%) is much higher than that between fish and mammal (40%). These data suggest that the alpha subunit is conserved while the beta subunit is diversified during the molecular evolution of vertebrate GTH.

Multiple risk factors of nasopharyngeal carcinoma: Epstein-Barr virus, malarial infection, cigarette smoking and familial tendency

A community-based case-control study was carried out to assess multiple risk factors and familial aggregation of nasopharyngeal carcinoma (NPC). All of the 347 pathologically-confirmed NPC new cases were serially recruited from the National Taiwan University Hospital, and healthy community controls one-to-one matched with cases on age, sex and residence were selected from household registration offices. NPC risk factors were obtained from the study subjects through standardized interviews according to a structured questionnaire. Levels of antibody to EBV-specific DNase (anti-EBV DNase) and IgA antibody to EBV viral capsid antigen (anti-EBV VCA) were determined by standard methods blindly. Multiple logistic regression analysis for matched data showed significant associations of NPC with high levels of anti-EBV DNase and anti-EBV VCA independently. The effect of cigarette smoking on NPC was modified by age. The older the age, the more striking the dose-response relation between cigarette smoking and NPC. There was no significant association between alcohol consumption and NPC. Malarial infection history was associated with NPC with an odds ratio of 2.2, but the association was significant in males only. First-degree relatives of NPC cases had a greater NPC-affected rate than those of matched healthy controls with a relative risk of 19.2, and the heritability of NPC was estimated as 0.60 (95% confidence interval = 0.55-0.64) based on the multifactorial inheritance model. Familial NPC cases were younger than sporadic cases, but environmental risk factors were similar in the two groups.

Factors affecting penetration of zona-free hamster ova

The sperm penetration assay is an expensive, time-consuming test to assess male fertility in vitro. Although some investigators are enthusiastic in its application, others feel that it is not sensitive or specific enough to be used as part of the routine infertility evaluation. Indeed, this bioassay is not a faithful reproduction of in vivo conditions. However, if the SPA is abnormal, it is unlikely that sperm will fertilize a human ovum in vivo. Conversely, a normal SPA does not guarantee successful in vivo fertilization. No bioassay can be absolute in its predictive value, but false-negative results must be kept to a minimum for this bioassay to be of any clinical significance. Each laboratory performing the SPA should optimize the assay for sensitivity, reproducibility, and minimization of false-negative results and then establish normal and abnormal ranges of its own. If the limitations of the SPA are kept in mind, and if we employ it very selectively, it may still be useful.

Characterization of two newly established EBV-containing lymphoblastoid cell lines from patients with myeloid leukemias

Two spontaneous outgrowing Epstein-Barr virus (EBV)-carrying lymphoblastoid cell lines (LCLs), CG2 and CG3, have been established from bone marrow cells of myeloid leukemia patients. CG2 was derived from a patient with chronic myelomonocytic leukemia (CMMoL) and who has a 45 XO karyotype. CG3 was derived from a patient with juvenile chronic myeloid leukemia (CML) and who carries a hypotetraploid karyotype, 91XXYY. Both CG2 and CG3 cells carry the same type of translocation; t(1;19)(q23;p13). Both cell lines are of an early B cell lineage as shown by their reactivities with monoclonal antibodies OKIa, B1, B2 and B4. The combination of horizontal discontinuous agarose slab gel and Southern hybridization results show CG2 and CG3 cells are of monoclonal origin and harbor episomal EBV genomes. Approximately 50 EBV genome equivalents were contained in CG2 and CG3 cells. Immunofluorescence studies demonstrate the expression of EBV-encoded antigen (EBNA) in almost all cells of these two lines. The expression of EA and VCA is only observed in a small percentage of cells and cannot be induced by treatment with TPA and SB. Therefore, CG2 and CG3 cells are probably nonproducer cell lines for EBV. The serum samples from both patients have been shown to contain elevated IgG antibody titers to EBV antigens. Both cells are found to be nontumorigenic in nude mice. These cells may provide an important tool in analyzing molecular epidemiological aspects of EBV infections in diseases such as CMMoL and juvenile CML.

Pike eel (Muraenesox cinereus) gonadotropin. Amino acid sequences of both alpha and beta subunits

The amino acid sequences of pike eel gonadotropin alpha and beta subunits have been determined by standard sequencing analytical methods. The alpha subunit is composed of 93 amino acid residues while the beta subunit comprises 113 amino acid residues. All the invariant half-cystine residues are in the same positions as those found in other gonadotropins. It is noteworthy that the first, putative glycosylation site (Asn56) found in the alpha subunit of other gonadotropins was replaced by Asp56 in the alpha subunit of pike eel gonadotropin. Similarity analyses indicate that both subunits are structurally more similar to other known fish gonadotropin subunits than to those of the mammalian gonadotropins.

Establishment and characterization of a tumor cell line from human nasopharyngeal carcinoma tissue

An epithelial tumor cell line, CG1, was established from human nasopharyngeal carcinoma tissues. The CG1 cells are of an epithelial origin as shown by their reactivities with the epithelial-specific antikeratin antibodies and by the presence of the desmosome structure at cell-cell junctions. CG1 cells possess characteristics of tumor cells because these cells are tumorigenic in nude mice and also have reduced serum requirements for in vitro cultivation. The doubling time of CG1 cells is 20 h and these cells have been successfully cultured in vitro for more than 200 generations. The average chromosome number of these cells is 60. Slot and Southern blot hybridizations showed the presence of Epstein-Barr virus-DNA sequences in CG1 cells. This cell line provides us an in vitro system for the study of the role of Epstein-Barr virus in nasopharyngeal carcinoma.

Identification and characterization of the maltose permease in genetically defined Saccharomyces strain

Saccharomyces yeasts ferment several alpha-glucosides including maltose, maltotriose, turanose, alpha-methylglucoside, and melezitose. In the utilization of these sugars transport is the rate-limiting step. Several groups of investigators have described the characteristics of the maltose permease (D. E. Kroon and V. V. Koningsberger, Biochim. Biophys. Acta 204:590-609, 1970; R. Serrano, Eur. J. Biochem. 80:97-102, 1977). However, Saccharomyces contains multiple alpha-glucoside transport systems, and these studies have never been performed on a genetically defined strain shown to have only a single permease gene. In this study we isolated maltose-negative mutants in a MAL6 strain and, using a high-resolution mapping technique, we showed that one class of these mutants, the group A mutants, mapped to the MAL61 gene (a member of the MAL6 gene complex). An insertion into the N-terminal-coding region of MAL61 resulted in the constitutive production of MAL61 mRNA and rendered the maltose permease similarly constitutive. Transformation by high-copy-number plasmids containing the MAL61 gene also led to an increase in the maltose permease. A deletion-disruption of MAL61 completely abolished maltose transport activity. Taken together, these results prove that this strain has only a single maltose permease and that this permease is the product of the MAL61 gene. This permease is able to transport maltose and turanose but cannot transport maltotriose, alpha-methylglucoside, or melezitose. The construction of strains with only a single permease will allow us to identify other maltose-inducible transport systems by simple genetic tests and should lead to the identification and characterization of the multiple genes and gene products involved in alpha-glucoside transport in Saccharomyces yeasts.

Allium vegetables and reduced risk of stomach cancer

Interviews with 564 patients with stomach cancer and 1,131 controls in an area of China where gastric cancer rates are high revealed a significant reduction in gastric cancer risk with increasing consumption of allium vegetables. Persons in the highest quartile of intake experienced only 40% of the risk of those in the lowest. Protective effects were seen for garlic, onions, and other allium foods. Although additional research is needed before etiologic inferences can be made, the findings are consistent with recent reports of tumor inhibition following administration of allium compounds in experimental animals.

Erythrocyte sodium transport in dialyzed uremic patients

To investigate the status of the Na+ concentration and ionic fluxes in red cells of human subjects with dialyzed chronic uremia, the authors measured the Na(+)-K+ pump activity as well as Na(+)-K+ cotransport (CoT), Na(+)-Li+ countertransport (CTT) and Na+ passive permeability in erythrocytes from 37 normal subjects and 23 chronic uremic patients receiving maintenance hemodialysis. The mean intracellular Na+ concentration [Na+]i value in the pre-dialytic group was significantly lower than that in control subjects (p less than .0001), but tended to recover to the normal value of [Na+]i in the post-dialytic group. The mean intracellular K+ concentration value in the post-dialytic group was significantly higher than that of the control group (p less than .001), but not significantly different from that of the pre-dialytic group. It was found that the Na(+)-K+ pump activity of erythrocytes in the pre- and post-dialytic groups markedly decreased over that of the normal control group with statistical significance (p less than .0001, respectively). The Na(+)-K+ pump activity in the post-dialytic group, however, tended to recover, but not significantly. The rate constant for ouabain-sensitive Na+ efflux in the post-dialytic group was significantly decreased over that of the normal controls (p less than .05). The authors observed a significant decrease of the Na+ CoT value (p less than .001 respectively) and rate constant for Na+ CoT (p less than .05, respectively) in the patients with pre- and post-dialytic uremia vs. that of normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Primary structures of carp gonadotropin subunits deduced from cDNA nucleotide sequences

The alpha and beta subunits of carp gonadotropin (cGTH) were isolated by high performance liquid chromatography. They were identified to be the subunits of cGTH by bioassay and by partial N-terminal amino acid sequence analysis. To elucidate the complete primary structures of the alpha and beta subunits of cGTH, cDNA cloning technique was employed. The alpha and beta subunits consist of 95 and 115 amino acid residues, respectively. Homology of the alpha subunit of cGTH to those of mammalian GTH is around 70%. In comparison, the extent of homology of the beta subunit between carp and salmon GTH (75%) is higher than that between fish and mammalian GTH (39-47%). Such comparative data suggest that the alpha subunit is highly conserved while the beta subunit is diversified during the molecular evolution of vertebrate GTH.

MAL63 codes for a positive regulator of maltose fermentation in Saccharomyces cerevisiae

Genetic analysis of the MAL6 locus has previously yielded mal6 mutants which fall into a single complementation group and which are noninducible for maltase and maltose permease. However, the strains used in these studies contained additional partially functional copies of MAL1 (referred to as MAL1g) and MAL3 (referred to as MAL3g). Using a strain lacking MALg genes, we have isolated two classes of mutants and these classes correspond to mutations in MAL63 and MAL61, two genes of the MAL6 complex. Disruptions of MAL63 are noninducible for maltase and maltose permease and for their corresponding mRNAs. The mal6 mutants are shown to map to MAL63. Inducer exclusion as a cause of the noninducible phenotype of the mal63 mutations has been eliminated by constructing a mal63 mutant in a strain constitutive for maltose permease; the strain remains noninducible. These results rigorously demonstrate that MAL63 is a regulatory gene which plays a positive role in the regulation of maltose fermentation.

Role of tumor cytoskeleton and membrane glycoprotein IRGpIIb/IIIa in platelet adhesion to tumor cell membrane and tumor cell-induced platelet aggregation

Components of the tumor cell cytoskeleton (i.e., microtubules, microfilaments, and intermediate filaments) have been reported to affect metastatic ability, since disruption of these components leads to a decrease in metastasis. One mechanism of metastasis which has not been previously considered is the decreased interaction of tumor cells with platelets. We present evidence that disruption of the tumor cell cytoskeleton decreases the ability of tumor cells to aggregate homologous platelets. This effect is dependent upon the disruption of microfilaments/intermediate filaments but not disruption of microtubules. In addition, tumor cell platelet interactions require the lateral mobility of specific receptors (i.e., clustering) on the tumor cell plasma membrane. A membrane glycoprotein immunologically related to the platelet glycoprotein IIb/IIIa complex was identified on Walker 256 carcinosarcoma cells using specific polyclonal and monoclonal antibodies and Northern blot analysis using complementary DNA probes for IIb and IIIa. Mobility of this receptor is dependent upon tumor cell microfilaments/intermediate filaments, but not microtubules. Furthermore, treatment of tumor cells with specific antibodies to the platelet glycoprotein IIb/IIIa complex inhibits tumor cell-platelet interaction at the macroscopic level (i.e., aggregation) and at the ultrastructural level (i.e., platelet adhesion to the tumor cell surface). These results suggest that this immunologically related glycoprotein IIb/IIIa is a receptor for platelet binding to the tumor cell surface, an event which precedes overt platelet aggregation and is dependent upon an intact tumor cell microfilament and intermediate filament network. Therefore, the decreased metastasis observed by others following disruption of the tumor cell cytoskeleton may be due, in part, to a decreased tumor cell-platelet interaction.