Mutational analyses of yeast RNA triphosphatases highlight a common mechanism of metal-dependent NTP hydrolysis and a means of targeting enzymes to pre-mRNAs in vivo by fusion to the guanylyltransferase component of the capping apparatus

Saccharomyces cerevisiae Cet1p is the prototype of a family of metal-dependent RNA 5'-triphosphatases/NTPases encoded by fungi and DNA viruses; the family is defined by conserved sequence motifs A, B, and C. We tested the effects of 12 alanine substitutions and 16 conservative modifications at 18 positions of the motifs. Eight residues were identified as important for triphosphatase activity. These were Glu-305, Glu-307, and Phe-310 in motif A (IELEMKF); Arg-454 and Lys-456 in motif B (RTK); Glu-492, Glu-494, and Glu-496 in motif C (EVELE). Four acidic residues, Glu-305, Glu-307, Glu-494, and Glu-496, may comprise the metal-binding site(s), insofar as their replacement by glutamine inactivated Cet1p. E492Q retained triphosphatase activity. Basic residues Arg-454 and Lys-456 in motif B are implicated in binding to the 5'-triphosphate. Changing Arg-454 to alanine or glutamine resulted in a 30-fold increase in the K(m) for ATP, whereas substitution with lysine increased K(m) 6-fold. Changing Lys-456 to alanine or glutamine increased K(m) an order of magnitude; ATP binding was restored when arginine was introduced. Alanine in lieu of Phe-310 inactivated Cet1p, whereas Tyr or Leu restored function. Alanine mutations at aliphatic residues Leu-306, Val-493, and Leu-495 resulted in thermal instability in vivo and in vitro. A second S. cerevisiae RNA triphosphatase/NTPase (named Cth1p) containing motifs A, B, and C was identified and characterized. Cth1p activity was abolished by E87A and E89A mutations in motif A. Cth1p is nonessential for yeast growth and, by itself, cannot fulfill the essential role played by Cet1p in vivo. Yet, fusion of Cth1p in cis to the guanylyltransferase domain of mammalian capping enzyme allowed Cth1p to complement growth of cet1Delta yeast cells. This finding illustrates that mammalian guanylyltransferase can be used as a vehicle to deliver enzymes to nascent pre-mRNAs in vivo, most likely through its binding to the phosphorylated CTD of RNA polymerase II.

Screening plasma aluminum levels in relation to aluminum bone disease among asymptomatic dialysis patients

Aluminum accumulation in plasma and tissues is a well-described complication among persons undergoing peritoneal dialysis or hemodialysis. Excess bone aluminum is associated with low bone formation rates and increased risk for fractures. Current recommendations for care of patients with end-stage renal disease include screening for aluminum toxicity with plasma aluminum levels; patients with levels below 40 microg/L are considered to be at low risk for aluminum bone disease (ABD). We examined data from the Toronto Renal Osteodystrophy Study to evaluate the performance of plasma aluminum levels in screening for ABD. Two hundred fifty-eight unselected patients undergoing peritoneal dialysis (n = 143) or hemodialysis (n = 115) underwent diagnostic bone biopsy and measurement of plasma aluminum level. Sixty-nine patients (26.7%) were identified as having ABD, defined as low or normal bone formation rates with 25% or more bone surface aluminum staining. Plasma aluminum level was strongly associated with the presence of ABD; the odds ratio was 1.4 for each increase of 10 microg/L (95%CI, 1.2, 1.6). However, only 50.1% of patients with a plasma aluminum level of 40 microg/L or greater had ABD, whereas 14.2% of patients with a level below this threshold also had ABD. Using this cutoff level of 40 microg/L, the sensitivity and specificity were 65.2% and 76.7%, respectively. We conclude that although there is a correlation between high aluminum levels and ABD, a patient's plasma aluminum level does not predict well the presence of ABD in spite of a relatively high prevalence of disease.

Augmentation of ultraviolet B radiation-induced tumor necrosis factor production by the epidermal platelet-activating factor receptor

Ultraviolet B radiation (UVB) has been shown to damage human keratinocytes in part by inducing oxidative stress and cytokine production. Indeed, UVB-induced production of the pro-inflammatory and cytotoxic cytokine tumor necrosis factor alpha (TNF-alpha) has been implicated in the epidermal damage seen in response to acute solar radiation. Though the lipid mediator platelet-activating factor (PAF) is synthesized in response to oxidative stress, and keratinocytes express PAF receptors linked to cytokine biosynthesis, it is not known whether PAF is involved in UVB-induced epidermal cell cytokine production. These studies examined the role of the PAF system in UVB-induced epidermal cell TNF-alpha biosynthesis using a novel model system created by retroviral-mediated transduction of the PAF receptor-negative human epidermal cell line KB with the human PAF receptor (PAF-R). Treatment of PAF-R-expressing KB cells with the metabolically stable PAF-R agonist carbamoyl-PAF resulted in increased TNF-alpha mRNA and protein, indicating that activation of the epidermal PAF-R was linked to TNF-alpha production. UVB irradiation of PAF-R-expressing KB cells resulted in significant increases in both TNF-alpha mRNA and protein in comparison to UVB-treated control KB cells. However, UVB treatment up-regulated cyclooxygenase-2 mRNA levels to the same extent in both PAF-R-expressing and control KB cells. Pretreatment with the antioxidant vitamin E or the PAF-R antagonists WEB 2086 and A-85783 inhibited UVB-induced TNF-alpha production in the PAF-R-positive but not control KB cells. These studies suggest that the epidermal PAF-R may be a pharmacological target for UVB in skin.

[Purification and characterization of a novel antifungal peptide APS-1 produced by Bacillus cereus]

In previous study, we isolated an antagonist Bacillus cereus strain: S-1 from cotton plant. In field experiments, this bacterium was shown strong inhibition to several plant diseases. In this paper, we reported the purification of the antifungal substance produced by the bacterium and its properties. After the steps of acid precipitation, methanol and ethy lether extraction, Sephadex G100 and DEAE52 column chromatography, the antifungal material was purified. The purified material had absorption peak at 275 nm, and was exhibited negative in biuret color reaction. However after hydrolyzed with HCl, this substance shown positive in the same reaction. Amino acid analysis to the hydrolysate of APS-1 showed that APS-1 was composed of Glu, Asp, Tyr, Ser, Thr, Pro, Leu, Ile, Val and an unknown amino acid. Combining with its pratial resistance to proteinases, it was suggested that this antifungal material was a cyclic peptide. This peptide, named APS-1, with strong inhibition on the germination of spores of the phytopathogens tested, was shown high stability against ultraviolet radiation and heat. APS-1 may have potential role in plant diseases biological control.

Somatic PKD2 mutations in individual kidney and liver cysts support a "two-hit" model of cystogenesis in type 2 autosomal dominant polycystic kidney disease

An intriguing feature of autosomal dominant polycystic kidney disease (ADPKD) is the focal and sporadic formation of renal and extrarenal cysts. Recent documentation of somatic PKD1 mutations in cystic epithelia of patients with germ-line PKD1 mutations suggests a "two-hit" model for cystogenesis in type 1 ADPKD. This study tests whether the same mechanism for cystogenesis might also occur in type 2 ADPKD. Genomic DNA was obtained from 54 kidney and liver cysts from three patients with known germ-line PKD2 mutations, using procedures that minimize contamination of cells from noncystic tissue. Using intragenic and microsatellite markers, these cyst samples were screened for loss of heterozygosity. The same samples were also screened for somatic mutations in five of the 15 exons in PKD2 by single-stranded conformational polymorphism analysis. Loss of heterozygosity was found in five cysts, and unique intragenic mutations were found in seven other cysts. In 11 of these 12 cysts, it was also determined that the somatic mutation occurred nonrandomly in the copy of PKD2 inherited from the unaffected parent. These findings support the "two-hit" model as a unified mechanism for cystogenesis in ADPKD. In this model, the requirement of a somatic mutation as the rate-limiting step for individual cyst formation has potential therapeutic implications.

Coordinate expression of the autosomal dominant polycystic kidney disease proteins, polycystin-2 and polycystin-1, in normal and cystic tissue

A second gene for autosomal dominant polycystic kidney disease (ADPKD), PKD2, has been recently identified. Using antisera raised to the human PKD2 protein, polycystin-2, we describe for the first time its distribution in human fetal tissues, as well as its expression in adult kidney and polycystic PKD2 tissues. Its expression pattern is correlated with that of the PKD1 protein, polycystin-1. In normal kidney, expression of polycystin-2 strikingly parallels that of polycystin-1, with prominent expression by maturing proximal and distal tubules during development, but with a more pronounced distal pattern in adult life. In nonrenal tissues expression of both polycystin molecules is identical and especially notable in the developing epithelial structures of the pancreas, liver, lung, bowel, brain, reproductive organs, placenta, and thymus. Of interest, nonepithelial cell types such as vascular smooth muscle, skeletal muscle, myocardial cells, and neurons also express both proteins. In PKD2 cystic kidney and liver, we find polycystin-2 expression in the majority of cysts, although a significant minority are negative, a pattern mirrored by the PKD1 protein. The continued expression of polycystin-2 in PKD2 cysts is similar to that seen by polycystin-1 in PKD1 cysts, but contrasts with the reported absence of polycystin-2 expression in the renal cysts of Pkd2+/- mice. These results suggest that if a two-hit mechanism is required for cyst formation in PKD2 there is a high rate of somatic missense mutation. The coordinate presence or loss of both polycystin molecules in the same cysts supports previous experimental evidence that heterotypic interactions may stabilize these proteins.

[Isolation and identification of a saponine from Patrinia scabiosaefolia]

A saponine compound was isolated from the acetone extract of the roots and rhizomes of Patrinia scabiosaefolia Fish. ex Link. Its structure was identified by combination of chemical reaction and spectrum analysis as 3-O-alpha-L-rhamnopyranosyl-(1-2)-beta-D-xylopyranosyl oleanolic acid (giganteaside D), and part of its 13C-NMR data was revised by the 2D-NMR. The compound was found in the Patrinia for the first time.

[Influence of blood-activating drugs on adhesion and invasion of cells in lung cancer patients]

OBJECTIVE

To investigate the influence of some blood-activating drugs like Tetramethylpyrazine, Tanshinone II A, Hirudin and thrombin on adhesive and invasive behavior of PGCL3 and PAa cell lines.

METHODS

Using the above-mentioned blood-activating drugs in various concentration to treat PGCL3 and PAa cells, and the changes in adhesion to fibronectin and invasion in Boyden Chamber of these cells, alone or after interacted with human platelets, were observed.

RESULTS

Tetramethylpyrazine, Hirudin and thrombin could increase the adhesion of cells to fibronectin and Tanshinone II A decrease it. Tetramethylpyrazine, Tanshinone II A and Hirudin inhibited the invasion of PGCL3 cells in Boyden Chamber, and thrombin augmented the process.

CONCLUSION

The blood-activating drugs may either inhibit or promote the invasion and metastasis of PGCL3 and PAa cells in the light of various conditions.

LINE-1 elements at the sites of molecular rearrangements in Alport syndrome-diffuse leiomyomatosis

Deletions encompassing the 5' termini of the paired type IV collagen genes COL4A5 and COL4A6 on chromosome Xq22 give rise to Alport syndrome (AS) and associated diffuse leiomyomatosis (DL), a syndrome of disseminated smooth-muscle tumors involving the esophagus, large airways, and female reproductive tract. In this study, we report isolation and characterization of two deletion junctions. The first, in a patient described elsewhere, arose by a nonhomologous recombination event fusing a LINE-1 (L1) repetitive element in intron 1 of COL4A5 to intron 2 of COL4A6, resulting in a 13.4-kb deletion. The second, in a previously undescribed family, arose by unequal homologous recombination between the same L1 and a colinear L1 element in intron 2 of COL4A6, resulting in a>40-kb deletion. L1 elements have contributed to the emergence of this locus as a site of frequent recombinations by diverse mechanisms. These give rise to AS-DL by disruption of type IV collagen and perhaps other as yet unidentified genes, evidenced by deletions as small as 13.4 kb.

Yeast and viral RNA 5' triphosphatases comprise a new nucleoside triphosphatase family

Saccharomyces cerevisiae Cet1p catalyzes the first step of mRNA capping, the hydrolysis of the gamma phosphate of triphosphate-terminated RNA to form a 5' diphosphate end. The RNA triphosphatase activity of Cet1p is magnesium-dependent and has a turnover number of 1 s-1. Here we show that purified recombinant Cet1p possesses a robust ATPase activity (Km = 2.8 microM; Vmax = 25 s-1) in the presence of manganese. Cobalt is also an effective cofactor, but magnesium, calcium, copper, and zinc are not. Cet1p displays broad specificity in converting ribonucleoside triphosphates and deoxynucleoside triphosphates to their respective diphosphates. The manganese- and cobalt-dependent nucleoside triphosphatase of Cet1p resembles the nucleoside triphosphatase activities of the baculovirus LEF-4 and vaccinia virus D1 capping enzymes. Cet1p, LEF-4, and D1 share three collinear sequence motifs. Mutational analysis establishes that conserved glutamate and arginine side chains within these motifs are essential for the RNA triphosphatase and ATPase activities of Cet1p in vitro and for Cet1p function in vivo. These findings are in accord with the effects of single alanine mutations at analogous positions of vaccinia capping enzyme. We suggest that the metal-dependent RNA triphosphatases encoded by yeast and DNA viruses comprise a novel family of phosphohydrolase enzymes with a common active site.

[The chemical constituents of Epimedium koreanum Nakai]

Three new compounds were isolated from the aerial part of Epimedium koreanum Nakai. On the basis of spectroscopic and chemical evidences, they were elucidated as 3-O-beta-D-glucopyranosyl(1-->3)-alpha-L-(4-acetyl) rhamnopyranoside-anhydroicaritin-7-O-beta-D-glucopyranoside, 2-(p-hydroxyphenoxy)-5, 7-dihydroxy-6-prenylchromone, and 7-hydroxy-3, 4, 6-trimethoxy-9, 10-dihydrophenanthrene-2-O-beta-D-glucopyranoside.

Identification of PKDL, a novel polycystic kidney disease 2-like gene whose murine homologue is deleted in mice with kidney and retinal defects

Polycystin-1 and polycystin-2 are the products of PKD1 and PKD2, genes that are mutated in most cases of autosomal dominant polycystic kidney disease. Polycystin-2 shares approximately 46% homology with pore-forming domains of a number of cation channels. It has been suggested that polycystin-2 may function as a subunit of an ion channel whose activity is regulated by polycystin-1. Here we report the identification of a human gene, PKDL, which encodes a new member of the polycystin protein family designated polycystin-L. Polycystin-L has 50% amino acid sequence identity and 71% homology to polycystin-2 and has striking sequence and structural resemblance to the pore-forming alpha1 subunits of Ca2+ channels, suggesting that polycystin-L may function as a subunit of an ion channel. The full-length transcript of PKDL is expressed at high levels in fetal tissues, including kidney and liver, and down-regulated in adult tissues. PKDL was assigned to 10q24 by fluorescence in situ hybridization and is linked to D10S603 by radiation hybrid mapping. There is no evidence of linkage to PKDL in six ADPKD families that are unlinked to PKD1 or PKD2. The mouse homologue of PKDL is deleted in Krd mice, a deletion mutant with defects in the kidney and eye. We propose that PKDL is an excellent candidate for as yet unmapped cystic diseases in man and animals.

Patients treated by cardiologists have a lower in-hospital mortality for acute myocardial infarction

OBJECTIVES

We sought to determine the effect of specialty care on in-hospital mortality in patients with acute myocardial infarction.

BACKGROUND

There has been increasing pressure to limit access to specialists as a method to reduce the cost of health care. There is little known about the effect on outcome of this shift in the care of acutely ill patients.

METHODS

We analyzed the data from 30,715 direct hospital admissions for the treatment of acute myocardial infarction in Pennsylvania in 1993. A risk-adjusted in-hospital mortality model was developed in which 12 of 20 clinical variables were significant independent predictors of in-hospital mortality. To determine whether there were factors other than patient risk that significantly influenced in-hospital mortality, multiple logistic regression analysis was performed on physician, hospital and payer variables.

RESULTS

After adjustment for patient characteristics, a multiple logistic regression analysis identified treatment by a cardiologist (odds ratio=0.83 [confidence interval ¿CI¿=0.74 to 0.94] p < 0.003) and physicians treating a high volume of acute myocardial infarction patients (odds ratio=0.89 [CI=0.80 to 0.99] p < 0.03) as independent predictors of lower in-hospital mortality. Treatment by a cardiologist as compared to primary care physicians was also associated with a significantly lower length of stay for both medically treated patients (p < 0.01) and those undergoing revascularization (p < 0.01).

CONCLUSIONS

Treatment by a cardiologist is associated with approximately a 17% reduction in hospital mortality in acute myocardial infarction patients. In addition, patients of physicians treating a high volume of patients have approximately an 11% reduction in mortality. This has important implications for the optimal treatment of acute myocardial infarction in the current transformation of the health care delivery system.

A spectrum of mutations in the polycystic kidney disease-2 (PKD2) gene from eight Canadian kindreds

Autosomal dominant polycystic kidney disease (ADPKD) is a common Mendelian disorder that affects approximately 1 in 1000 live births. Linkage studies have shown that the majority (approximately 85%) of cases are due to mutations in PKD1 on chromosome 16p, while mutations in PKD2 on chromosome 4q account for most of the remaining cases. Locus heterogeneity in ADPKD is known to contribute to differences in disease severity, with PKD1-linked families having earlier onset of end-stage renal disease (ESRD) than PKD2-linked families (mean age at ESRD: 56 versus 70, respectively). In this study, 11 Canadian families with ADPKD were screened for PKD2 mutations. In four families, linkage to PKD2 was previously documented. In the remaining seven smaller families, one or more affected members had late-onset ESRD at age 70 or older. Using single-stranded conformational polymorphism analysis, one affected member from each family was screened for mutations in all 15 exons of PKD2, which were PCR-amplified from genomic templates. A spectrum of mutations was found in approximately 73% (8 of 11) of the families screened, with no difference in the detection rate between the PKD2-linked families and the families with late-onset ESRD. In three unrelated families, insertion or deletion of an adenosine in a polyadenosine tract (i.e., (A)8 at nt 2152-2159) was found on exon 11, suggesting that this mononucleotide repeat tract is prone to mutations from "slipped strand mispairing." All mutations, scattered between exons 1 and 11, are predicted to result in a truncated polycystin 2 that lacks both the calcium-binding EF-hand domain and the two cytoplasmic domains required for the interaction of polycystin 2 with polycystin 1 and with itself. Furthermore, no correlation was found between the location of the mutations in the PKD2 coding sequence and disease severity. Thus, these findings are consistent with other recently published reports and suggest that most PKD2 mutations are inactivating.

Antiinflammatory activity of the platelet-activating factor receptor antagonist A-85783

Accumulating evidence suggests an important role for the lipid mediator, platelet-activating factor (PAF), in cutaneous inflammation. In these studies the antiinflammatory effects of the potent and selective lipophilic PAF receptor antagonist A-85783 topically applied to the ventral ears of male Wistar rats were assessed. Intradermal injections of PAF into rat ears resulted in cutaneous inflammation as assessed by both ear thickness measurements and histological evaluation. Pretreatment of the ears with A-85783 resulted in an inhibition of subsequent PAF-induced inflammation. A-85783 treatment also inhibited phorbol myristic acetate-induced cutaneous inflammation, suggesting that the PAF receptor is involved in the etiology of this experimental dermatitis. These findings demonstrate that epicutaneous A-85783 is an appropriate tool to study the role of the PAF receptor in cutaneous inflammation, and suggest the possible clinical utility of this new class of antiinflammatory agents.

Activation of the epidermal platelet-activating factor receptor results in cytokine and cyclooxygenase-2 biosynthesis

Recent studies suggest that the lipid mediator platelet-activating factor (PAF) is involved in keratinocyte function and skin inflammation. Indeed, PAF is found in association with inflammatory skin diseases, intradermal injections of PAF induce inflammation, and keratinocytes express functional PAF receptors (PAF-R). One mechanism by which the keratinocyte PAF-R could contribute to epidermal functions and inflammatory states would be through the synthesis of inflammatory regulators, such as PAF, PGs, and cytokines. The ability of the epidermal PAF-R to induce the synthesis of these immunomodulators was tested using a model system created by transduction of the PAF-R-negative human epidermal cell line KB with the PAF-R. Activation of this epidermal PAF-R resulted in arachidonic acid release, and the biosynthesis of PAF and PGE2. In addition, the KB PAF-R triggered increased levels of mRNA and protein for the inducible isozyme of cyclooxygenase (COX-2) as well as IL-6 and IL-8, both of which have been implicated in skin inflammatory processes. Studies with the human keratinocyte-derived epidermal cell line HaCaT revealed that activation of the endogenous PAF-R led to the increased accumulation of COX-2, IL-6, and IL-8 mRNA similar to that seen with the KB PAF-R model system. Finally, treatment of HaCaT keratinocytes with IL-8 resulted in PAF biosynthesis, indicating the existence of a positive feedback loop between IL-8 and PAF in epidermal cells. These studies suggest involvement of PAF and the PAF-R in the epidermal cytokine network.

Identification and pharmacological characterization of platelet-activating factor and related 1-palmitoyl species in human inflammatory blistering diseases

Through its pro-inflammatory effects on leukocytes, endothelial cells, and keratinocytes, the lipid mediator platelet-activating factor (PAF) has been implicated in cutaneous inflammation. Although the 1-alkyl PAF species has been considered historically the most abundant and important ligand for the PAF receptor (PAF-R), other putative ligands for this receptor have been described including 1-acyl analogs of sn-2 acetyl glycerophosphocholines. Previous bioassays have demonstrated a PAF-like activity in lesions of the autoimmune blistering disease bullous pemphigoid. To assess the actual sn-2 acetyl glycerophosphocholine species that result in this PAF agonistic activity, we measured PAF and related sn-2 acetyl GPCs in fresh blister fluid samples from bullous pemphigoid and noninflammatory (suction-induced) bullae by mass spectrometry. We report the presence of 1-hexadecyl as well as the 1-acyl PAF analog 1-palmitoyl-2-acetyl glycerophosphocholine (PAPC) in inflammatory blister fluid samples. Because PAPC is the most abundant sn-2 acetyl glycerophosphocholine species found in all samples examined, the pharmacological effects of this species with respect to the PAF-R were determined using a model system created by transduction of a PAF-R-negative epidermoid cell line with the PAF-R. Radioligand binding and intracellular calcium mobilization studies indicated that PAPC is approximately 100x less potent than PAF. Though a weak agonist, PAPC could induce PAF biosynthesis and PAF-R desensitization. Finally, intradermal injections of PAF and PAPC into the ventral ears of rats demonstrated that PAPC was 100x less potent in vivo. These studies suggest possible involvement of PAF and related species in inflammatory bullous diseases.

Absence of association between Alzheimer disease and the -491 regulatory region polymorphism of APOE

A novel polymorphism (-491 A/T) within the regulatory region on the apolipoprotein E gene has recently been reported to be associated with risk for Alzheimer disease (AD). To test this association in an independent data set, we have examined this polymorphism in a sample of 88 well-characterized AD cases and compared the allele frequency and genotype frequencies for this polymorphism with those observed in 112 cognitively normal subjects drawn from the same ethnic group. These results suggest that in the current data set at least, the -491 A/T polymorphism is not associated with risk for AD, but may be in partial linkage disequilibrium with the APOE epsilon2/epsilon3/epsilon4 polymorphism.

[A case of report--interferon therapy is useful for chronic hepatitis C with human immunodeficiency virus infection]

A 42-year-old male type A hemophiliae who been using coagulates since 1971 was diagnosed Human Immunodeficiency Virus (HIV) positive in 1993. Medical history included liver disfunction in 1987, with chronic hepatitis C (CHC) diagnosed in 1989. He was admitted to the hospital in October, 1994 because of general fatigue. Serum transaminase was elevated, CD4 was 221/micro L, and CD8 was 990. CD4/CD8 ratio was 0.2. HCV was of genotype 2b and 10(6) copies/50 microL, 8 week-Interferon (IFN)-beta treatment was started. HCV RNA was eliminated by week 8 and was sustained for one year with no severe side effects. With careful patient screening, IFN therapy for CHC with HIV may be an effective treatment.

[Clinical observation on the adhesion molecule expression and functional study of platelets in cancer patients]

OBJECTIVE

To investigate adhesion molecule expression and functional status of platelets in cancer patients and their relation to cancer progression.

METHODS

Using flow cytometry to measure the expression of surface antigens and functional status of platelets in 50 healthy donors and 181 cancer patients.

RESULTS

Comparing with normal donors, the expression of CD42a in cancer patients decreased, and that of TSP and CD36 increased. The number of platelets with CD36+ TSP+, CD36+ TSP-, CD9+, CD31+, CD62+ CD63-, CD62+ CD63+, CD62- CD63+ phenotypes also increased. There was significant difference between patients in early stage and those in advanced stage, but there was no significant difference between the patients in early stage and healthy donors. The expression of CD41 did not change in cancer patients.

CONCLUSION

In cancer patients, especially in the advanced stage of the disease, the expression of the adhesion molecules on platelets and their released products increase, indicative of an activated state of the platelets.

A novel frameshift mutation induced by an adenosine insertion in the polycystic kidney disease 2 (PKD2) gene

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common Mendelian disorders and is genetically heterogeneous. Linkage studies have shown that the majority (approximately 85%) of ADPKD cases are due to mutations in PKD1 on chromosome 16p13.3, while mutations in PKD2 on chromosome 4q21-q23 are thought to account for most of the remaining cases. In this report, we describe the mutation in a large four-generation ADPKD family (TOR-PKD77) which we had mapped to the PKD2 locus by linkage analysis. In this family, we screened for mutations by directly sequencing two nested RT-PCR fragments (PKD2N1 and PKD2N2) that cover approximately 90% of the PKD2 open reading frame. In the affected members, we identified a novel single adenosine insertion (2160InsA) in the PKD2N2 fragment. This mutation occurred in the polyadenosine tract (nt2152-2159) of exon 11 and is predicted to result in a frameshift with premature translation termination of the PKD2 product, polycystin 22, immediately after codon 723. The truncated polycystin 2 is predicted to lack the calcium-binding EF-hand domain and two cytoplasmic domains required for the homodimerization of polycystin 2 with itself and for the heterodimerization of polycystin 2 with polycystin 1.

BMP-2 and OP-1 exert direct and opposite effects on renal branching morphogenesis

The bone morphogenetic proteins, BMP-2 and OP-1, are candidates for growth factors that control renal branching morphogenesis. We examined their effects in embryonic kidney explants and in the mIMCD-3 cell model of collecting duct morphogenesis (mIMCD-3 cells are derived from the terminal inner medullary collecting duct of the SV40 mouse). Osteogenic protein-1 (OP-1), at a dose of 0.25 nM, increased explant growth by 30% (P = 0.001). In contrast, 100-fold greater concentrations of OP-1 (28 nM) decreased explant growth by 10% (P < 0.001). BMP-2 was entirely inhibitory (maximum inhibition of 7% at 5 nM, P < 0.0004). In an in vitro model for branching morphogenesis utilizing the kidney epithelial cell line, mIMCD-3, low doses of OP-1 (< 0.5 nM) increased the number of tubular structures formed by 28 +/- 5% (P = 0.01), whereas concentrations > 0.5 nM decreased that number by 22 +/- 8% (P = 0.02). All concentrations of BMP-2 (0.05-10 nM) were inhibitory (maximum inhibition at 10 nM of 88 +/- 3%, P < 0.0001). Stimulatory doses of OP-1 increased tubular length (P = 0.003) and the number of branch points/structure (3.2-fold increase, P = 0.0005) compared with BMP-2. To determine the molecular basis for these effects, we demonstrated that BMP-2 is bound to mIMCD-3 cells by the type I serine/threonine kinase receptor, ALK-3, and that OP-1 bound to an approximately 80-kDa protein using ligand-receptor affinity assays. To demonstrate that OP-1 can exert both stimulatory and inhibitory effects within a developing kidney, embryonic explants were treated with agarose beads saturated with 2 microM OP-1. OP-1 decreased the number of ureteric bud/collecting duct branches adjacent to the beads by 58 +/- 1% (P < 0.0001). In contrast, the number of branches in tissue distal to the OP-1 beads was enhanced, suggesting a stimulatory effect at lower doses of OP-1. We conclude that OP-1 and BMP-2 directly control branching morphogenesis and that the effects of OP-1 are dependent on its local concentration within developing kidney tissue.

[Effect of beta-carotene on 60Co-gamma-induced mutation at T-lymphocyte hypoxanthine-guanine phosphoribosyl transferase locus in rats]

AIM

To study the effect of beta-carotene (beta-Car) on radiation-induced mutation.

METHODS

Mutant frequency at T-lymphocyte hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus in rats was measured using a T-lymphocyte cloning technique and malondialdehyde (MDA) was measured using a thiobarbituric acid (TBA).

RESULTS

Mutant frequency at the HGPRT locus was elevated by 60Co-gamma 3.75 Gy, and was reduced by ig beta-car 20 and 10 mg.kg-1 (P < 0.05), but not by beta-Car 5 mg.kg-1. It showed a dose-dependent relationship. MDA was signifcantly reduced in plasma of rats given beta-Car after 60 Co-gamma radiation. There was positive coherence between MDA and mutant frequency at the HGPRT locus (r = 0.9978, P < 0.05).

CONCLUSIONS

Radiation-induced mutation is inhibited by beta-Car, associated with antioxidant action of beta-Car.