[Apoptosis inductive effect of homoharringtonine and isoharringtonine on human acute promyelocytic leukemia HL-60 cells]

OBJECTIVE

To study the effects of homoharringtonine and isoharringtonine on the induction of apoptosis on human promyelocytic leukemia HL-60 cells.

METHODS

By using flow cytometry, DNA gel electrophoresis, microscopy and electron microscopy.

RESULTS

It was demonstrated that homoharringtonine and isoharringtonine can induce apoptosis of HL-60 cells significantly and rapidly. The activity of homoharringtonine was higher than that of isoharringtonine, and it was time and concentration dependent.

CONCLUSIONS

Both homoharringtonine and isoharringtonine could induce apoptosis of HL-60 cells in terms of morphology, and DNA ladder assay. The activity of homoharringtonine was much higher than that of isoharringtonine.

Mutated ras p21 as a target for cancer therapy in mouse transitional cell carcinoma

PURPOSE

To establish an experimental mouse model for bladder cancer immunotherapy using mutated ras as a target.

MATERIALS AND METHODS

A tumorigenic mouse bladder transitional cell carcinoma (TCC) line MB49 (C57BL/6 origin) was analyzed for its c-ras gene status by DNA cloning and sequencing. Aberrant expression of the ras gene was measured with Western blotting. 13-mer peptides corresponding to residues 5 to 17 of the ras protein were synthesized and tested for immunogenicity in syngeneic C57BL/6 mice. Induction of specific immune responses was evaluated by analyzing splenocyte activity in vitro and tumor suppression in vivo.

RESULTS

MB49 cells were found to contain a single amino acid substitution of serine for glycine at codon 12 in K-ras loci and an abundant amount of cellular mutated ras p21 protein. C57BL/6 mice immunized with the 13-mer serine-containing ras peptide exhibited mutation-specific immune responses in splenocyte proliferation, cytokine production and cytotoxicity. Specific antitumor immunity in the form of tumor growth delay in vivo was observed in mice immunized with the same mutant peptide followed by subcutaneous MB49 tumor challenge and was enhanced by the addition of low dose interleukin-12.

CONCLUSIONS

The mouse bladder TCC line MB49 contains a serine mutation at codon 12 of its K-ras gene that is sufficient to induce mutation-specific immune responses in vitro and specific protective immunity to MB49 tumor in vivo. Mutated oncoproteins may be ideal targets for the development of specific immunotherapy regimens for bladder cancer immunotherapy.

Reduction of UV-induced skin tumors in hairless mice by selective COX-2 inhibition

UV light is a complete carcinogen, inducing both basal and squamous cell skin cancers. The work described uses the selective COX-2 inhibitor celecoxib to examine the efficacy of COX-2 inhibition in the reduction of UV light-induced skin tumor formation in hairless mice. UVA-340 sun lamps were chosen as a light source that effectively mimics the solar UVA and UVB spectrum. Hairless mice were irradiated for 5 days a week for a total dose of 2.62 J/cm(2). When 90% of the animals had at least one tumor, the mice were divided into two groups so that the tumor number and multiplicity were the same (P < 0.31). Half of the mice were then fed a diet containing 1500 p.p.m. celecoxib. Tumor number, multiplicity and size were then observed for the next 10 weeks. Ninety-five percent of the tumors formed were histopathologically evaluated as squamous cell carcinoma. COX-2 expression and activity were increased in tumors. After 10 weeks, the difference in tumor number and multiplicity in the drug-treated group was 56% of UV controls (P < 0.001). The results show that the orally administered selective COX-2 inhibitor celecoxib prevents new tumor formation after the onset of photocarcinogenesis and suggest that treatment with celecoxib may be very useful in preventing UV-induced skin tumors in humans.

Effects of genistein on invasion and matrix metalloproteinase activities of HT1080 human fibrosarcoma cells

Effects of genistein on invasion and matrix metalloproteinase activities were investigated in HT1080 human sarcoma cells. Invasion of HT1080 cells through reconstituted basement membrane was inhibited when the cells were treated with 100 micromol/L and 200 micromol/L genistein. At the same concentrations, genistein not only suppressed latent forms of matrix metalloproteinase-2 and -9 (MMP-2 and MMP-9) to convert into active forms, but also increase dramatically the tissue inhibitor of metalloproteinase (TIMP-1) mRNA contents and reverse the imbalance of MMPs and TIMPs. However, expressions of MMP-2 and MMP-9 were not significantly affected. Suppression of MMP activation and increase of TIMP-1 expression will decrease matrix degradation by MMPs, and consequently inhibit invasions of the cells. These results emphasized the existence of the imbalance between MMPs and TIMPs in tumor invasion and metastasis formation. The value of genistein as a drug for antiinvasion and anti-metastasis chemotherapy was suggested.

Protection of rabbits from viral challenge by gene gun-based intracutaneous vaccination with a combination of cottontail rabbit papillomavirus E1, E2, E6, and E7 genes

In this study, cottontail rabbit papillomavirus infection of domestic rabbits was used as an animal model to develop papillomavirus early gene-based vaccines. Groups of rabbits were intracutaneously vaccinated with single papillomavirus early genes E1, E2, E6, and E7 or with a combination of these four genes. Only a fraction of rabbits were protected from subsequent viral challenge when vaccinated with the E1 or E6 gene. Viral tumor growth in those rabbits vaccinated with the E1 or E2 gene was suppressed compared to that in controls. In contrast, seven of nine rabbits vaccinated with the combination of the E1, E2, E6, and E7 genes were completely protected against viral challenge. These data indicated that intracutaneous genetic vaccination with the combination of the E1, E2, E6, and E7 genes can be an effective strategy for immunoprophylaxis of papillomavirus infection.

[Inhibition of tumor invasion by new retinoid, 5-4A, and its mechanism of the action]

OBJECTIVE

To investigate the effect of 5-4A on the invasion of B16BL6 and to explore its mechanisms of action.

METHODS

The invasion of B16BL6 was studied using the reconstituted basement membrane invasion assay.

RESULTS

The phenotype of B16BL6 cells was obviously suppressed by 5-4A at the concentration of 4 x 10(-5) mol/L, and the inhibitory rate was 33.9%.

CONCLUSION

5-4A can inhibit invasion of B16BL6 cells and its mechanisms of action might be associated with the suppression of movement of tumor cells, decrease in the expression of type IV collagenase, and reversion of the phenotype of B16BL6 cells.

Solution structure of the major alpha-amylase inhibitor of the crop plant amaranth

alpha-Amylase inhibitor (AAI), a 32-residue miniprotein from the Mexican crop plant amaranth (Amaranthus hypochondriacus), is the smallest known alpha-amylase inhibitor and is specific for insect alpha-amylases (Chagolla-Lopez, A., Blanco-Labra, A., Patthy, A., Sanchez, R., and Pongor, S. (1994) J. Biol. Chem. 269, 23675-23680). Its disulfide topology was confirmed by Edman degradation, and its three-dimensional solution structure was determined by two-dimensional 1H NMR spectroscopy at 500 MHz. Structural constraints (consisting of 348 nuclear Overhauser effect interproton distances, 8 backbone dihedral constraints, and 9 disulfide distance constraints) were used as an input to the X-PLOR program for simulated annealing and energy minimization calculations. The final set of 10 structures had a mean pairwise root mean square deviation of 0.32 A for the backbone atoms and 1.04 A for all heavy atoms. The structure of AAI consists of a short triple-stranded beta-sheet stabilized by three disulfide bonds, forming a typical knottin or inhibitor cystine knot fold found in miniproteins, which binds various macromolecular ligands. When the first intercystine segment of AAI (sequence IPKWNR) was inserted into a homologous position of the spider toxin Huwentoxin I, the resulting chimera showed a significant inhibitory activity, suggesting that this segment takes part in enzyme binding.

Development of keratoacanthomas and squamous cell carcinomas in transgenic rabbits with targeted expression of EJras oncogene in epidermis

Activated ras genes have been frequently identified in both benign and malignant human tumors, including keratoacanthoma and squamous cell carcinoma. In this study, we developed two lines of transgenic rabbits in which the expression of EJras has been specifically targeted to the rabbit epidermal keratinocytes, using the upstream regulatory region of cottontail rabbit papillomavirus. All of the F1 transgenic progenies developed multiple keratoacanthomas at about 3 days after birth. The rabbits developed an average of 20 tumors, which usually reached the size of approximately 1 cm in diameter and then spontaneously regressed in about 2 months, similar to keratoacanthoma regression in humans. In addition, up to 18% of the rabbits then developed squamous cell carcinoma at about 5 months of age. The expression of EJras was detectable in all of the keratoacanthomas and squamous cell carcinomas. These results strongly support the involvement of the ras oncogene in both the initiation and regression of keratoacanthoma, and in the development of squamous cell carcinomas. These novel transgenic rabbits, with their consistent tumorigenic phenotype at an early age, high similarity to the human lesions, and easy accessibility for examination, manipulation, biopsy, and treatment, should provide a unique model system for studying ras activation-related tumor initiation, regression, and progression, and for evaluating antitumor therapies.

[Formation of germline chimeras from murine embryonic stem cell lines]

Generation of germline chimeras is the crucial step in ES cell-mediated transgenesis. The prerequisite for germline chimerism is the maintenance of germline differentiating potency of ES cells, whereas production of germline chimeras is the only method to prove whether such potency is maintained. In order to investigate the germline differentiating potency of three newly established ES cell lines (MESPU21, MESPU22 and MESPU29), ES cells were introduced into host embryos from inbred C57BL/6J and outbred KMW or ICR through blastocyst injection or 8-cell stage morula injection. Totally 81 chimeras were obtained; among 42 test-bred ones, 19 were germline transmitters assessed by coat analysis, as is the first report of ES cell-embryo germline chimeras in China. MESPU21 and MESPU22 formed germline chimeras in high frequency and most of those chimeras produced ES cell-derived progeny in high proportion, which proved that both ES cell lines retained good germline differentiating potency and could be used as valuable cellular vehicles to introduce genetic modifications into mouse genome.

[Spectrophotometric assay of polyethyene glycol in urine using ammonium ferrothiocyanate aqueous-chloroform system]

A spectrophotometric method for the quantitative determination of polyethylene glycol-600 (PEG-600) in urine is based on partitioning a chromophore present in ammonium ferrothiocyanate reagent into an aqueous phase and a chloroform phase in the presence of PEG. The method is simple and reproducible, and can detect PEG in a concentration of 0.25 g/L. It gives a linear response over a range of 0.25-2.5 g/L. The recovery of PEG-600 in urine is 107% and relative standard deviation is less than 5%.

[Protein tyrosine kinase inhibitor genistein suppresses in vitro invasion of HT1080 human fibrosarcoma cells]

OBJECTIVE

To investigate the effects of genistein on cancer invasion and associated cellular characteristics and explore the possibility of developing protein tyrosine kinase inhibitors as anti-metastasis drugs.

METHODS

HT1080 human fibrosarcoma cells were exposed to 20 mumol/L or 40 mumol/L genistein for 3 days. The abilities of the genistein-treated cells to invade through reconstituted matrigel or migrate through polycarbonate filters in transwell chambers were then investigated. Northern blot and laser densitometry were used to estimate the relative mRNA amounts of MMP-2, MMP-9 and TIMP-1 in the cells.

RESULTS

The ability of the genistein-treated HT1080 cells to invade the reconstituted basement membrane was decreased significantly (P < 0.01). In consistent with the lowered invasive potential, migration rates of the drug-treated cells decreased dramatically. genistein did not, however, significantly affect attachment of HT1080 cells on fibronectin, laminin or Matrigel. Though exposure to genistein led to a small increase in MMP-2 and MMP-9 gene expression, a much greater increase in the amount of TIMP-1 mRNA was observed. Imbalanced enhancement of gene expression between matrix metalloproteinases and their inhibitors in favor of the latter may imply that matrix degradation is impaired in the genistein-treated cells.

CONCLUSION

Genistein suppresses invasion of HT1080 cells at relatively low concentrations. genistein and other protein tyrosine kinase inhibitors might be valuable candidate drugs for the treatment of invasion and metastasis of cancer.

[Study of selenite bio-transformation in nature water by hydride generation-atomic fluorescence]

This paper studied selenite bio-transformation in nature water by hydride generation-atomic fluorescence. Production was primarily element selenium, also with volatile selenium. The added C sources accelerated the transformation.

Intramuscular injection of plasmid DNA encoding cottontail rabbit papillomavirus E1, E2, E6 and E7 induces T cell-mediated but not humoral immune responses in rabbits

To test the efficacy of genetic vaccination against papillomavirus infection, plasmid DNA encoding cottontail rabbit papillomavirus (CRPV) E1, E2, E6, E7 or without insert were intramuscularly injected into five groups of rabbits. Peripheral blood mononuclear cells (PBMCs) showed specific proliferation upon in vitro stimulation with E1, E2, E6 or E7 proteins in a majority of vaccinated rabbits but Western blot analysis did not detect antibodies specific for these viral proteins in rabbit serum. All rabbits grew papillomas after virus challenge and none of the rabbits showed systemic papilloma regression. These observations showed that intramuscular injection of plasmid DNA encoding CRPV E1, E2, E6 or E7 induced CD4+ T cell-mediated but not humoral immune responses, and did not result in the protection of rabbits from virus infection.

Interobserver variability in 99mTc-DMSA renal scintigraphy reports: multicentric study

BACKGROUND

The aim of the study was to evaluate the interobserver variability and reproducibility of the renal scintigraphy reports.

METHODS

The study was prospective performed in 60 99mTc DMSA scintigraphies (116 kidneys), done in one centre, displayed on X ray films as analogue 300 kcounts images in 4 standard projections. Six observers from 4 different centres (group A), including three observers from one institution (group B), were asked to interpret original scans. Seven parameters of scintigraphy protocol were analysed with at least two responses: kidney size (1), uptake (2), outlines (3), scars (4), SOL (5), differential function (6) and conclusion (7).

RESULTS

Among 116 kidneys, concordant results in interpretation of seven points of report from 1 to 7, in the group A were found in 62%, 42.5%, 45%, 9%, 47%, 52% and 34%, and In the group B in 72%, 55%, 59%, 22%, 62%, 60% and 41% respectively. Some improvement in concordant reporting was noted in the group of 3 observers, in comparison of group of all, statistically significant in category of scar reports (p < 0.01).

CONCLUSIONS

Results suggest to use of standardised criteria and terminology in interpretations, to improve low interobserver reproducibility and objectivity of renal scintigraphy reports, particularly in evaluation of renal scars.

Effects of genistein, a soybean-derived isoflavone, on proliferation and differentiation of B16-BL6 mouse melanoma cells

Genistein, a soybean-derived isoflavone, may contribute to the lower cancer incidence in South Asian countries. In this study, the effects and molecular mechanisms of genistein on growth and differentiation of B16-BL6 mouse melanoma cells were investigated. Genistein suppressed the growth of these melanoma cells. The IC50 value is 15.5 microM. On the other hand, genistein induced the changes of cell shape and cytoskeletal network. The cytoskeletal filaments were induced to form a bundle along the direction of elongation of the cells. Moreover, tyrosine phosphorylation levels of cytoskeleton-associated proteins decreased after the cells were exposed to 20 or 30 microM of genistein for 3 days. All these morphological and molecular changes were accompanied by appearance of the differentiated phenotypes. Genistein induced the increase of cellular melanin content, enhancement of tyrosinase activity, and decrease of colonization potentials in soft agar in a time-dependent and dose-dependent manner. The effective concentration was no more than 10 microM after 3 days' exposure. The tumorigenic potentials of B16-BL6 cells in C57BL/6 mouse also decreased after exposure to 20 or 30 microM of genistein for 3 days. When expressions of tumor-related genes were investigated in the differentiation-induced cells, the content of P53 dramatically increased while that of c-Myc protein decreased. Therefore, due to its ability to induce cellular and molecular changes, genistein suppressed the growth and induced differentiated phenotypes in B16-BL6 melanoma cells.

Boswellic acid acetate induces differentiation and apoptosis in leukemia cell lines

Boswellic acid acetate (BC-4), a compound isolated from the herb Boswellia carterii Birdw., can induce differentiation and apoptosis of leukemia cells. Based on cell morphology and NBT reduction, BC-4 induced monocytic differentiation of myeloid leukemia HL-60, U937 and ML-1 cells at a dose under 12.5 microg/ml (24.2 microM). BC-4 was a potent inducer, with 90% of the cells showing morphologic changes and 80-90% of the cells showing NBT reduction. Specific and non-specific esterase were also increased by BC-4. Based on benzidine staining assay, BC-4 failed to induce erythroid leukemia DS-19 and K562 cells differentiation. In contrast to its selective differentiation effect, BC-4 strongly inhibited growth of all cell lines tested. The growth inhibition effect was dose- and time-dependent. In HL-60 cells, 20 microg/ml (38.8 microM) of BC-4 decreased viable cell number by 60% at 24 h, whereas at 3 days there was virtually no viable cells. Morphologic and DNA fragmentation analysis proved that BC-4 induced cell apoptosis. The dual apoptotic and differentiation effects of BC-4 suggest that it may be a powerful agent in the treatment of leukemia.

[In vitro study on the effects of the novel retinoids combined with IFN-gamma on the proliferation and differentiation of fresh acute monocytic leukemic cells]

OBJECTIVE

To investigate the prospect for clinical use of novel retinoids YS 904012 and R 9158 in combination with IFN-gamma in inducing differentiation of acute monocytic leukemia.

METHODS

The effects of novel retinoids with IFN-gamma on the differentiation and clonal proliferation of fresh leukemia cell from 6 monocytic leukemia patients were studied in vitro. Cell morphological examination, nitro tetrazolium blue reduction test and DCE, expression of CD14 and CD68 and CFU-L were used in the study.

RESULTS

The primary leukemia cell, cultured with the combination of YS 904012 and IFN-gamma, became more mature in morphology. The NBT reduction rate and DCE were increased from 23.4% and 25.0% to 61.5% and 52.0%, respectively. The expression of CD14 and CD68 was increased. The growth of the leukemic colony in semi-solid culture was markedly inhibited. The activity of YS 904012 combined with IFN-gamma in inhibiting proliferation and inducing differentiation of monoblast was greater than that of R9158 or all-trans retinoic acid in combination with IFN-gamma (P < 0.01).

CONCLUSION

The YS 904012 combined with IFN-gamma is worthy of further study for clinical differentiation therapy of acute monocytic leukemia.

[Differentiation of B16 melanoma cells induced by ginsenoside RH2]

The effect of ginsenoside Rh2, a constituent isolated from Panax ginseng C. A. Meyer, on the growth of tumor cells in vitro was investigated. The results showed that Rh2 inhibited the growth of B16 cells at the concentration of 10 micrograms.ml-1 (IC50: 4.1 micrograms.ml-1). Rh2 was found to significantly induce the activity of differentiation of B16 cells at the concentration of 10 micrograms.ml-1 in vitro. The melanin synthesis of Rh2 in treated B16 cells was increased. Morphologically, the Rh2 induced B16 cells turned to be epithelioid cells. B16 cells became dendrite shaped morphologically at higher concentration of Rh2. Flow cytometry demonstrated that the B16 cells treated with Rh2 were blocked at G1 phase.

[Induction differentiation by a new third generation retinoid R9158 on human acute promyelocytic leukemia cell line, NB4]

OBJECTIVE

In order to investigate the differentiation of 3',5'-ditertiary-butiary-4'-methoxy-carboxyl chalcone (R9158) on the acute promyelocytic leukemia NB4 cells.

METHODS

By inditifying the function, morphology and karyotype of NB4 cells induced by R9158.

RESULTS

Our results showed that R9158 or all-trans retinoic acid (RA) significantly inhibited the growth and colony formation of acute promyelocytic leukemia NB4 cells, while NBT-reduction (a functional differentiation marker of granulocytic) was dramatically increased when the cells were exposed to R9158 at 10(-9)-10(-6) mol/L, and the NBT positive cells reached about 97.5% at 10(-6) mol/L after 6 days expouse. The ED50 of NBT-reduction was achieved at concentration of 3.9 x 10(-9) mol/L and 2.8 x 10(-9) mol/L for R9158 and RA, respectively. Morphologically, most of the cells induced by R9158 and RA at 10(-6) mol/L were in the myelocytic or metamyelocytic stage and a few cells were in the banded or segmented stage. Cytogenetic analysis revealed that the karyotype of NB4 cells was subtetraploid and the chromosome numbers were in the range of 71-99, when NB4 cells were treated with R9158 or RA for 3-6 days, the abnormal polyploid chromosome numbers decreased to 72.9 +/- 6.9 (P < 0.01) or 68.5 +/- 7.0 (P < 0.01), but the t(15;17) translation did not disappear.

CONCLUSIONS

R9158 has significant effects on the differentiation of NB4 cells.

Characterization of transformation function of cottontail rabbit papillomavirus E5 and E8 genes

Cottontail rabbit papillomavirus (CRPV) induces rabbit skin papillomas, which progress to invasive carcinoma in some animals. Two early genes, E7 and E6, have been demonstrated previously to be oncogenes. In this study, we identified two additional transforming genes, E8 and E5. Both E8 and E5 stimulated C127 and BALB/c A31 (A31) cell proliferation and affected cell cycle transition. The E8 and E5 transfectants lost cell contact inhibition, reaching a high saturation density when cultured up to 2 weeks. E8-C127 transfectants formed colonies in soft agar in the presence of platelet-derived growth factor (PDGF) while E5-C127 transfectants formed colonies without the requirement for PDGF. E8-C127 transfectants were highly tumorigenic whereas E5-C127 transfectants showed a weak tumorigenicity in nude mice. Both E8 and E5 A31 transfectants failed to form colonies in soft agar even in the presence of platelet-derived growth factor (PDGF) and did not develop tumors in nude mice. These results clearly showed that CRPVE8 and E5 are oncogenes and that the PDGF beta-receptor signaling pathway may be involved in E8-mediated C127 cell transformation. The difference in colony formation in soft agar and tumorigenicity in nude mice between C127 and A31 cell lines indicates that additional alterations in cellular gene expression are needed for E5- and E8-transfected cells to acquire a malignant phenotype.

[Effect of d-limonene, Salvia miltiorrhiza and turmeric derivatives on membrane association of Ras gene product and gap junction intercellular communication]

Gap junction intercellular communication (GJIC), H-ras oncogene expression and Ras oncogene product(P21ras protein) expression were studied in four human solid tumor cell lines, W1-38, CACO2, A549 and PaCa (with the different Ras gene mutation rate), and the effects of four compounds, Salvia miltiorrhiza derivative (SMD), d-limonene, turmeric derivative I(TD-I) and turmeric derivative II(TD-II), on them. The abilities of the four solid tumor cell lines to transfer dye to adjacent cells were examined using the scrape-loading/dye transfer technique, and the H-ras oncogene expression by Northern blotting and P21ras protein expression by Western blotting. The results showed the loss of intercellular coupling in PaCa cells, slight GJIC in A549 and CACO2 cells, and good GJIC in W1-38 cells. The four compounds used was shown to improve the GJIC of PaCa to different extents. The amount of total and membrane associated P21ras in PaCa cells were decreased after treatment with SMD, d-limonene and TD-I(2.5 micrograms.ml-1) for 48 h. Concomitantly, the growth of PaCa cells decreased in soft agar and GJIC was enhanced. The relative potency was found to be: d-limonene > SMD > TD-I = TD-II. No significant effect of the four compounds on H-ras oncogene expression was observed. These results suggest that 1. there was an excellent correlation between loss of Lucifer Yellow dye transfer and ras gene mutation rate in the four solid tumor cell lines used (ras gene mutation rate inversely correlated with average cell number couplied, r = 0.98) i.e., showing that high ras gene mutation is closely correlated with loss of GJIC in these malignant human tumor cells; 2. the antitumor effect of the monoterpene d-limonene and the phenol compound, SMD, might be related to the inhibition of P21ras membrane association and enhancement of GJIC, whilst that of the others may be by a different mechanism; 3. the inhibition of P21ras membrane association is directly related to the enhancement of gap junction intercellular communication.

H+ISFET-based biosensor for determination of penicillin G

A biosensor based on an H+ ion sensitive field effect transistor (H+(-)ISFET) and penicillin G acylase has been developed. The response time of the sensor to different concentrations of penicillin G was 30 s. In a 20 mM phosphate buffer at pH 7.0, the linear range of the calibration curve was from 0.5 to 8 mM. The coefficients of variation for three samples with 20 repeated measurements were below 5%. Stability of the sensor could reach about 6 months and more than 1000 runs were performed without a significant decrease of the output value. The sensor was tested for measurement of the penicillin G content in penicillin fermentation both. Forty samples with low and high concentrations of penicillin G were chosen for the correlation test. The values assayed by the sensor method were compared with the values assayed by HPLC method, the correlation coefficient (r) was 0.9944 and the regression equation was y = 1.034X - 2083.7, respectively. The different measuring methods are discussed in the text.

[Simultaneous determination of phenol and resorcinol by bouble wavelength standard additions method]

In this paper, double wavelength standard additions method was first used in fluorescence analysis. The simultaneous determination of phenol and resorcinol could be carried out when the ratio of phenol to resorcinol concentrations was in the range of 15:1-1:15. The method gives satisfactory results.

Genistein suppresses adhesion-induced protein tyrosine phosphorylation and invasion of B16-BL6 melanoma cells

Protein tyrosine phosphorylation occurs as one of the earlier events in cancer cell-extracellular matrix (ECM) interaction. With immunoblot analysis and immunofluorescence microscopy, genistein was found to suppress the tyrosine phosphorylation of proteins located at the cell periphery, including a 125 kDa protein, when B16-BL6 melanoma cells attached to and interacted with ECM. When accompanied by the suppression of adhesion-induced protein tyrosine phosphorylation, the invasive potential of B16-BL6 cells through reconstituted basement membrane was decreased significantly. However, neither adhesive capability nor cell growth was significantly affected by genistein. Therefore, the interruption of cancer cell-ECM interaction by suppression of protein tyrosine phosphorylation may contribute to invasion prevention of genistein.

[Isoharringtonine induces apoptosis in human leukemia HL-60 cell]

Harringtonine (HT), homoharringtonine (HHT) and isoharringtonine (IHT) are cephalotaxine alkaloids with anticancer activities which were isolated from Cephalotaxus hainanensis indigenous to China. Since the 1970s, HT and HHT have been developed as effective anticancer drugs in China and have been used widely in the treatment of acute nonlymphoid leukemia and chronic granulocyte leukemia. Although IHT has the advantage of low toxicity, it has not been developed as an anticancer drug because of its very low content in the plant. The cell apoptosis induced by isoharringtonine was investigated in human acute promyelocytic leukemia HL-60 cells by agarose gel electrophoresis of DNA, flow cytometry and transmission electron microscopy. In these experiments IHT showed significant and rapid apoptotic inductive effect on HL-60 cells in both concentration- and time-dependent fashion. The characteristic apoptosis-related features could be seen in IHT treated HL-60 cells. Transmission electron microscopy of IHT treated HL-60 cells displayed chromatin condensation and aggregation under the nuclear membrane, nuclear fragmentation and apoptosis body formation. Typical DNA ladder in agarose gel electrophoresis and pre-G1 peak in flow cytometric analysis were also observed in the cells exposed to IHT. The apoptotic rate could reach 43.8% in the HL-60 cells treated for 120 minutes with IHT 10(-7) mol.L-1. The cytotoxicity of IHT paralleled with cell apoptosis indicating that the anticancer activity of IHT results from the induction of apoptosis. These results are important impetus for further research and development of IHT as an anticancer agent.

[Binding activity of retinoids with recombinant human retinoic acid receptor RAR alpha]

OBJECTIVE

To establish a model for the rapid screening of differentiation-inducing agents.

METHODS

Human RAR alpha cDNA was cloned into the PT7-7 plasmids and the human recombinant RAR alpha protein was expressed in Escherichia coli. The ligand-binding activity of the receptor with all-trans retinoic acid was studied by competitive binding assay. For comparison of the binding activity, five retinoids, with different activities and chemical structures, were chosen. The binding of these retinoids to RAR alpha was investigated and compared with the NBT reduction and acid phosphatase activity of HL-60 cells induced by these compounds.

RESULTS

The binding activity of these retinoids was well correlated to their ability to induce differentiation of HL-60 cell line.

CONCLUSION

This model could be used to screen differentiation-inducing agents.

[Anti-invasion activity of several plant-originated anticancer drugs with different mechanism of action]

The antitumor and anti-invasion activities of taxol, harringtonine, homoharringtonine and camptothecin on highly metastatic melanoma B16-BL6 and human fibrosarcoma HT-1080 cells were reported in this paper. Results demonstrated that taxol, harringtonine, homoharringtonine and camptothecin exhibited significant inhibition of cell growth of B16-BL6 and HT-1080 cells. Taxol, harringtonine and homoharringtonine were also found to be effective for the inhibition of cell invasion and migration of B16-BL6 cells, but camptothecin showed basically no effect at the indicated concentration.

[Studies on retinoids. IV. Design, synthesis and structure-activity relationships of di-t-butylphenyl compounds]

Retinoic acid and its analogues play important roles in modulating cell growth, differentiation, immunity and apoptosis. Clinically they are used for cancer chemoprevention and chemotherapy. Based upon the moiety of 3,5-di-t-butyl-4-hydroxy phenyl ring, a series of substituted aromatic amide, ester and chalcones were designed and synthesized, which mimic the molecular shape, size, and spacial disposition of functional groups of retinoic acid. The general structure is as follows: [formula: see text] where R stands for hydrogen atom or methyl group, Y is the linkage -CONH-, -NHCO-, -COO-, -COCH = CH-, or a member of a heterocycle, X represents various substituents at different positions. The SAR indicates that the presence of hydrophobic group(s) at one end of the molecule, and a carboxyl group at the other end, and a conjugative system of molecule are necessary and full prerequisite for exhibiting activity. Loss of any one factor of them will abolish the activity. Being obligatory for anti-oxidative effect, the phenolic hydroxy group does not convey biological activity, because after methylation of the hydroxy group the compound increases the differentiation-inducing activity and loses the anti-oxidative effect, indicating that there is no correlation between the two activities. With a stable conformation of two phenyl rings with cis-conformation N-methylated acyl amide (No. 30) features in bent shape of the molecule, instead of an extended conformer, which is taken by the non-N-methylated partner and all-trans retinoic acid. A bent conformer of No. 30 accounts for the inactivity. In this paper compounds No. 4f, 4g, 5a, 7, 13, 32, 37, and 38 exhibited significant activity among them 4-[3-(3, 5-di-t-4-methoxyphenyl)-3-oxo-1-propenyl] benzoic acid (No. 38) showed high activity comparable to that of retinoic acid. The pharmacological action of No. 38 is under investigation.

Platelet-derived growth factor (PDGF)-signaling mediates radiation-induced apoptosis in human prostate cancer cells with loss of p53 function

Platelet-derived growth factor (PDGF) signals a diversity of cellular responses in vitro, including cell proliferation, survival, transformation, and chemotaxis. PDGF functions as a "competence factor" to induce a set of early response genes expressed in G1 including p21WAF1/CIP1, a functional mediator of the tumor suppressor gene p53 in G1/S checkpoint. For PDGF-stimulated cells to progress beyond G1 and transit the cell cycle completely, progression factors in serum such as insulin and IGF-1 are required. We have recently shown a novel role of PDGF in inducing apoptosis in growth-arrested murine fibroblasts. The PDGF-induced apoptosis is rescued by insulin, suggesting that G1/S checkpoint is a critical determinant for PDGF-induced apoptosis. Because recent studies suggest that radiation-induced signal transduction pathways interact with growth factor-mediated signaling pathways, we have investigated whether activation of the PDGF-signaling facilitates the radiation-induced apoptosis in the absence of functional p53. For this study we have used the 125-IL cell line, a mutant p53-containing, highly metastatic, and hormone-unresponsive human prostate carcinoma cell line. PDGF signaling is constitutively activated by transfection with a p28v-sis expression vector, which was previously shown to activate PDGF alpha- and beta- receptors. Although the basal level of p21WAF1/CIP1 expression and radiation-induced apoptosis were not detectable in control 125-IL cells as would be predicted in mutant p53-containing cells, activation of PDGF-signaling induced expression of p21WAF1/CIP1 and radiation-induced apoptosis. Our study suggests that the level of "competence" growth factors including PDGF may be one of the critical determinants for radiation-induced apoptosis, especially in cells with loss of p53 function at the site of radiotherapy in vivo.

Impact of a truncated invariant chain on in vitro assembly of class II MHC molecules depends on the affinity of invariant chain for a given alpha beta dimer

The assembly of major histocompatibility complex (MHC) class II alpha and beta chains occurs in the endoplasmic reticulum (ER) with the involvement of MHC class II-associated invariant chain (Ii). The present study investigated the impact of Ii on the assembly of both I-A haplotype-matched and -mismatched alpha and beta chains using an in vitro translation system. The alpha and beta chains of I-Ab, I-Ad and I-Ak were cotranslated in vitro in different combinations with or without cotranslation of a truncated murine Ii (mIi 1-131). The translated products were sequentially immunoprecipitated, first with conformation-dependent monoclonal antibodies, then with conformation-independent antibodies. The results show: (1), Ii did not associate with free A alpha and free A beta chains; (2), mIi 1-131 significantly augmented the amount of properly assembled A alpha b A beta b, A alpha b A beta d, A alpha b A beta k and A alpha k A beta b dimers, but had little affect on the assembly of A alpha d A beta d, A alpha k A beta k, A alpha d A beta b, A alpha k A beta d and A alpha d A beta k; (3), All A alpha A beta dimers whose assembly could be significantly facilitated by mIi 1-131 could be coimmunoprecipitated along with substantial amounts of mIi 1-131. This finding is consistent with prior observations that the impact of Ii on class II molecule assembly is allele specific. Furthermore, these results suggest that the efficient assembly of alpha and beta chains is primarily determined by the affinity between alpha and beta chains and the the high affinity of mIi for A alpha A beta dimers is required for mIi 1-131 to assist proper A alpha A beta assembly, most probably through a mechanism in which Ii stabilizes properly assembled A alpha A beta dimers or promotes folding of associated alpha and beta chains to help achieve a stable dimer state.

[4-acetamidophenyl retinoate (4-APR) inhibits reconstituted basement membrane invasion by tumor cells and its mechanism]

OBJECTIVE

To study the inhibitory effect of new retinoid 4-acetamidophenyl retinoate (4-APR) on the reconstituted basement membrane invasion by B16-F10 mouse melanoma cells and its mechanism.

METHODS

Reconstituted basement membrane invasion assay was used to evaluate invasive ability of cancer cells. Type IV collagenase was assessed by PAGE substrate zymography. TIMP-1 mRNA expression of human nasopharyngeal carcinoma CNE-2Z cell line was measured by dot blot analysis. Cell growth curve assay was used to examine the growth inhibitory effect of 4-APR on B16-F10 cells.

RESULTS

4-APR, at the concentrations of 10(-5) mol/L and 10(-6) mol/L, suppressed the reconstituted basement membrane invasion of B16-F10 mouse melanoma cells by 54.2%, 41.9% and reduced type IV collagenase activities in the serum-free supernatant of CNE-2Z cells. In addition, 4-APR inhibited B16-F10 cell adherence to laminin, fibronectin and Matrigel, and induced CNE-2Z cell TIMP-1 mRNA expression.

CONCLUSION

Reconstituted basement membrane invasion of B16-F10 mouse melanoma cells was inhibited by 4-APR. The anti-invasion action of 4-APR might be associated with the suppression of tumor cell adhesion ability, the reduction of type IV collagenase activity in tumor cell culture supernatant and/or the induction of tumor cell TIMP-1 mRNA expression.

[In vitro study on the effects of the novel retinoids on the proliferation and differentiation of normal and leukemic cells]

OBJECTIVE

To evaluate the prospect for clinical use of four novel retinoid compounds (retinoid 1, retinoid 2, retinoid 3 and retinoid 4), which were different structurally from all-trans retinoic acid.

METHODS

The effects of the four retinoids on the differentiation and clonal proliferation of NB4 cells and fresh acute promyelocytic leukemia (APL) cells and on the proliferation of normal hematopoietic cells were studied. Cell morphological examination,nitro tetrazolium blue reduction test, cell cycle dynamics, and colony formation assay were used in the study.

RESULTS

Novel retinoids induced differentiation of NB4 and fresh APL cells, and markedly inhibited CFU-L growth of NB4 and fresh APL cells. The activity related to their chemical structures and retinoid 2 was more active. The novel retinoids enhanced the growth of CFU-GM, CFU-E and CFU--Meg of normal bone marrow cells.

CONCLUSION

These novel retinoids, especially retinoid 2, may regulate the proliferation and differentiation of normal hematopoiesis, induce APL cell differentiation and maturation, and are worthy of further study for clinical use.

Suppression of adhesion-induced protein tyrosine phosphorylation decreases invasive and metastatic potentials of B16-BL6 melanoma cells by protein tyrosine kinase inhibitor genistein

Protein tyrosine kinase (PTK) appears to be involved in the activation of signaling during cell attachment to and spreading on extracellular matrix (ECM) in the metastatic cascade. To verify the assumption that PTK inhibitors might impair ECM signaling and prevent cancer metastasis, the highly metastatic B16-BL6 mouse melanoma cells were exposed to the PTK inhibitor genistein for 3 days. The ability of the cells to invade through reconstituted basement membrane (Matrigel) and to establish experimental pulmonary metastatic foci in C57BL/6 mice decreased after genistein exposure. The genistein-treated cells were also prevented from attaching to Matrigel and spread extremely poorly on the ECM substratum. Immunoblot analysis showed that tyrosine phosphorylation of a 125-kD protein in response to cell spreading on Matrigel was suppressed in the genistein-treated cells. Adhesion-induced protein tyrosine phosphorylation represents the earlier and specific event in the activation of ECM signaling, so this result implied ECM signaling was impaired in the treated cells. With immunofluorescence microscopy, the adhesion-induced tyrosine phosphorylated proteins were located at the pericytoplasms of well-spread cells, but not at the periphery of poorly spread genistein-treated cells. Therefore, this paper suggests that genistein might impair ECM signaling and subsequently prevent cancer cells from spreading well and invading or establishing metastasis through the suppression of adhesion-induced protein tyrosine phosphorylation. PTKs and adhesion-induced protein tyrosine phosphorylation might play a role in the control of invasion and metastasis.

Bulk modulus calculations based on perturbation self-consistency

We propose a method for bulk modulus calculations of solids based on perturbation self-consistency within the local density functional. The essential assumption is that a finite scaling is applied to the one-electron wavefunction when the solid adjusts to a new distorted structure under pressure. Thus the one-electron potential of a deformed structure near equilibrium can be obtained by performing a scaling transformation to charge density directly. The method is formulated within the linear muffin-tin orbital method in the atomic sphere approximation and applied to the calculation of bulk moduli of [Formula: see text], FCC Al, BCC Li, [Formula: see text] and an ordered FCC [Formula: see text] superlattice. The bulk modulus calculated from a single self-consistency is in reasonably good agreement with that of a full self-consistent calculation. Our results for Al - Li systems confirm that the addition of lithium to FCC Al causes the bulk modulus to decrease.

Expression of LAR-PTP2 in rat lung is confined to proliferating epithelia lining the airways and air sacs

The LAR family tyrosine phosphatase LAR-PTP2B (RPTP sigma) was previously shown to be expressed in the central and peripheral nervous system. Here we show that LAR-PTP2, the larger alternatively spliced form of the gene, is expressed in proliferating undifferentiated lung epithelia in a developmentally regulated manner: Using in situ hybridization and parallel immunostaining with proliferating cell nuclear antigen to detect proliferating cells, we demonstrate that LAR-PTP2 is expressed exclusively in the undifferentiated epithelial cell layer lining the bronchi, bronchioles, and air sacs in late fetal development and in the neonatal lung. These cells correspond to Clara and fetal alveolar type II cells, as determined by parallel immunostaining with antibodies to surfactant proteins A and B. LAR-PTP2 expression declined progressively with postnatal development, and by adult stage there was no detectable expression in the airways or in the distal (type I and II) mature nonproliferating alveolar epithelial cells. These results suggest that LAR-PTP2 may be involved in the regulation of epithelial cell proliferation/differentiation during lung development.

[Effects of curcumin derivatives on the GJIC of normal and tumor cells]

Experiments were conducted by using scrape-loading and dye transfer (SLDT) method to study the gap junction intercellular communication (GJIC) of Chinese hamster lung cells (V79), mouse fibrous cells (Balb/c-3T3), rat liver cells (WB) and human embryonal lung cells (2BS). We also observed the inhibition of the GJIC by TPA and the antagonistic effect of Curcumin derivatives on TPA. The results indicated that V79, WB, 3T3 and 2BS normal cells showed medium level of GJIC, and TPA could inhibit the GJIC to some extents. Curcumin derivatives (91022, 91022-S) could counteract the inhibition of TPA-induced GJIC. It was also found that human lung adenocarcinoma cell (A549) and GLC lacked GJIC, and 91022 could improve the GJIC of A549 cell. It may be related to its anticancer activity.

Identification of receptors binding fibronectin and laminin on fetal rat lung cells

Fibronectin and laminin have been implicated in regulating lung morphogenesis. In the present study, the cell surface receptors involved in fetal lung cell binding to laminin and fibronectin were identified. Messages for alpha5- and beta1-integrin subunits were detected in both fetal lung epithelial cells and fibroblasts. The presence of alpha5 beta1 -integrin on both cell types was demonstrated by immunocytochemistry and confirmed by cell adhesion experiments with fibronectin and RGD-containing peptides. Epithelial cells adhered more readily to laminin than fibroblasts. The alpha4 beta1-integrin, and RGD-independent fibronectin receptor, was weakly expressed on either cell type. Both cell types expressed alpha6-integrin subunit mRNA and stained immunopositive for the alpha6-subunit. Although either cell type expressed nonintegrin 67-kDa laminin-elastin receptor mRNA, no positive immunoreactivity for this laminin-elastin binding protein was detected. None of these findings explain the enhanced attachment of distal fetal lung epithelial cells to laminin compared with fibroblasts. Previously, we have reported that epithelial cells were enriched in alpha3-integrin subunit mRNA and protein expression. Herein, we found that epithelial cell attachment to laminin was nearly completely inhibited by alpha3- but only partially by alpha6 -monoclonal antibodies. A peptide near the globular region at the long arm of the laminin A-chain, which contained the IKVAV sequence, and the laminin A-chain amino acid sequence representing the alpha3 beta1 -integrin binding site, inhibited the adherence of epithelial cells to laminin. Fetal lung epithelial cells attached to substrata coated with the alpha3 beta1-integrin binding site peptide and the peptide containing the IKVAV sequence. These data suggest that both fetal lung cell types bind to fibronectin via the fibronectin receptor, alpha5 beta1, and fetal lung epithelial cells interact with laminin via alpha3 beta1 and proteins that recognize the IKVAV-containing sequence on the laminin A-chain.

[Studies on biological characteristics of HL-60 and all-trans-retinoic acid resistant HL-60 cells--comparison of the basic biological and cytogenic features of the two cell lines of HL-60]

The biological features of HL-60 and all-trans-retinoic acid resistant HL-60 cells (HL-60/ RA) were studied in terms of cell proliferation, cytokinetics, chromosome distribution and G-band karyotypes. Results indicated that the two cell lines exhibited similar morphology and doubling time and similar cytokinetic features, but the cell population in S phase of HL-60/RA is smaller than that of HL-60 cells. Their chromosome number is around 45 +/- 3 for HL-60 and 45 +/- 1 for HL-60/RA cells. G-band karyotype analysis showed that they have a similar diploid karyotype and some abnormal chromosomes. These results demonstrated that HL-60 and HL-60/RA cell lines were originated from the same source.

Immunization with viruslike particles induces long-term protection of rabbits against challenge with cottontail rabbit papillomavirus

Rabbits were immunized with recombinant baculovirus-produced virus-like particles (VLPs) of cottontail rabbit papillomavirus (CRPV) to determine whether these antigens could induce long-term protection against experimental challenge with CRPV. Infectious CRPV and human papillomavirus type 11 L1 VLPs were used as positive and negative control immunogens, respectively. Three groups of immunized animals were challenged with 10-fold serial dilutions of infectious CRPV at 2 weeks, 6 months, and 12 months after immunizations. Antibody titers in serum reached 1:10,000 immediately after the final booster immunization and then decayed to 1:150 at 6 months and 1:100 at 12 months in unchallenged rabbits. Serum neutralization titers followed similar kinetics. Papillomas grew on control-immunized rabbits at sites challenged with 10(-1) (100% of sites), 10(-2) (96% of sites), 10(-3) (63% of sites), and 10(-4) (13% of sites) dilutions of virus. At 2 weeks after CRPV L1 VLP immunizations, the rabbits were completely protected against virus challenge. At both 6 and 12 months after CRPV L1 VLP immunizations, strong protection was also observed. In the last two groups, three of seven rabbits were completely protected and only 4 of 14 or 29% of sites challenged with 10(-1 dilution of virus grew papillomas. Papillomas growing at these four sites were also reduced in size (3.5 +/- 0.7 mm) at 50 days postchallenge compared with sites challenged with 10(-1) dilution on control-immunized rabbits (13.2 +/- 4.2 mm). The results demonstrate that strong and long-lasting protection against experimental challenge with papillomaviruses can be achieved with VLP immunogens.

[Quantitative indicators of renal function in scintigraphy with mercaptoacetyl-triglycine in patients with transplanted kidneys (99m TC MAG3 in the quantitative evaluation of the transplanted kidney)]

99mTc MAG3 is the radiopharmaceutical agent that provides simultaneous investigation of renal perfusion, functional parenchyma and collecting system. Clearance of MAG3 which is equal to its tubular extraction rate (TER) and other quantitative parameters of renal function can be determined at the same time. The aim of the study was to analyze importance of TER, clearance index (CI) and renal accumulation rate (RA) of MAG3 in the assessment of the functional status of renal transplants. 31 kidney transplant recipients and 14 healthy donors were investigated. Dynamic renal scintigraphy was carried out 20 min. after i.v. injection of 150-220 MBq MAG3. Clearance was determined by single sample volume distribution method. For the calculation of CI and RA counts from transplant region acquired during the second minute of study were used. Results of TER, CI and RA were correlated with blood urea (Pu), serum creatinine (Pcr) and creatinine clearance (Ccr). The sensitivity of TER, CI and RA in well functioning kidney graft as well as in chronic rejection were analyzed. We concluded that: TER, CI and RA are more sensitive in comparison with Pu, Pcr and Ccr in quantitative assessment of renal transplant function; sensitivity of TER is greater than the sensitivity of CI and RA.

[Study on pharmacokinetics of human granulocyte-macrophage colony stimulating factor (hGM-CSF) in rats using a sensitive immunoassay (ELISA)]

A sensitive and reliable sandwich enzyme linked immunosorbent assay (ELISA) has been developed for determination of concentration of recombinant human granulocyte-macrophage colony-stimulating factor (hGM-CSF). The assay is quantitative between 0.39-12.5 ng.ml-1 for bacterially synthesized hGM-CSF in rat serum and urine. The method was shown to be highly specific and did not significantly alter the determination when adding some potential interfering substances. After single sc injection of hGM-CSF 50, 100 or 200 micrograms.kg-1, a high hGM-CSF level was detected about 15 min in rat serum, the highest level of hGM-CSF was two apparent phases with half-lives T1/20 of 0.72, 0.70, 0.80 h and T1/28 of 8.77, 8.87 and 5.58 h. A detectable urinary excretion occured after sc injection of hGM-CSF 200 micrograms.kg-1, but the total urinary excretion of unchanged hGM-CSF was very low.

Meta-[131I]iodobenzylguanidine in the scintigraphic evaluation of neural crest tumors

Since February 1990, 74 patients (116 studies) underwent scintigraphy with meta-[131I]iodobenzylguanidine ([131I]MIBG). Eighteen patients had pheochromocytomas, 2 paragangliomas, 2 malignant insulinomas, 1 carcinoid, 2 medullary thyroid carcinoma and 49 children had neuroblastomas. Scintigraphy was performed following a thyroid blockade, at 24 and 48 hours after i.v. injection of 0.5 mCi/1.7 m2 [131I]MIBG. Grade of heart intensity (GHI) uptake and the intensity of salivary gland visualization (SGI) were estimated semiquantitatively, according to the method of Nakajo et al. Sensitivity in the primary pheochromocytomas was 93.9%; sensitivity and specificity in the primary neuroblastomas were 93.7% and 100% respectively; in the secondary neuroblastomas they were 100%, and 100%. Metastases in 2 malignant insulinomas and in 1 case of medullary thyroid carcinoma were also demonstrated. Only one false negative (in pheochromocytoma) and one false positive (Conn's syndrome) result was obtained. Mean values and range of MIBG uptake measured according to Shulkin's procedure were: for pheochromocytoma 3.95% (0.1-15), primary neuroblastoma 0.7% (0.05-1.92%), and neuroblastoma metastases 0.12% (0.002-0.83%). Assessment of [131I]MIBG uptake seems to be helpful in the follow-up of some neural crest tumors and is essential as a prelude to [131I]MIBG therapy.

Diagnostic approach to reflex sympathetic dystrophy after fracture: radiography or bone scintigraphy?

The aim of this paper was to compare the value of bone scintigraphy and radiography in the early diagnosis of post-fracture reflex sympathetic dystrophy (RSD). Thirty-seven adult patients with post-fracture RSD (28 in the first and nine in the second clinical stage of RSD), as well as seven patients with fracture but without RSD (control group), were investigated by radiography and bone scintigraphy. All of them were immobilized (duration of immobilization: 4-22 weeks). In 21 persons three phase bone scintigraphy was performed. The best distinction between the control group and the RSD patients was achieved by delayed bone scintigrams. The sensitivity (97%), positive predictive value (97%) and accuracy (95%) of delayed bone scintigraphy were very high compared to the values for radiography, which were 73%, 90% and 70% respectively. Bone scintigraphy also displayed higher specificity (86%) and negative predictive value (86%) than radiography (57% and 29% respectively). In the first clinical stage the difference between the accuracy of bone scintigraphy (97%) and radiography (63%) was greater than for the whole group. In the second stage of RSD the accuracy of bone scintigraphy (86%) and radiography (81%) was similar. Three-phase bone scintigraphy is not necessary for the diagnosis of post-fracture RSD: it is sufficient to perform delayed bone scintigraphy. It is concluded that bone scintigraphy is to be preferred to radiography for the early diagnosis of post-fracture RSD in the first clinical stage. In the second stage the diagnostic capabilities of bone scintigraphy and radiography are more comparable.

Dependence of the phosphorylation of alkaline phosphatase by phosphate monoesters on the pKa of the leaving group

The hydrolysis and transphosphorylation reactions of a series of phosphate monoesters, ROPO3(2)-(R = 2,4-dinitrophenyl, 4-nitrophenyl, phenyl, glucose-1, glycerol-1, methyl, ethyl, and dodecyl), catalyzed by Escherichia coli alkaline phosphatase and a mutant enzyme, Ser102Cys, have been studied at alkaline pH using the rates of change in the 31P NMR signals of substrate, the hydrolysis product (inorganic phosphate), and the transphosphorylation product (O-Tris phosphate) as the assay. The kcat at pH 8.0 for the wild-type enzyme is approximately 30 s-1 and is independent of the nature of the R group, when the pKa of the leaving group is < 10. Under these conditions the rate of phosphorylation is much faster than dissociation of inorganic phosphate, 15-60 s-1. If the pKa of the leaving group is between 10 and 15, phosphorylation and dissociation of the product phosphate both contribute to the rate limit. If the pKa of the leaving group is > 15, phosphorylation is rate limiting. A Bronsted plot of log kcat vs pKa of the leaving group for those substrates for which phosphorylation is rate limiting yields a beta lg of approximately -0.6. In contrast to the wild-type enzyme, the log kcat values for the S102C mutant enzyme catalyzing the hydrolysis of phosphate esters are linearly dependent on the pKa's of the leaving group throughout the range of pKa from 4 to 16. Phosphorylation of C102 is the rate controlling step, and kcat is independent of the Tris concentration as predicted for rate limiting phosphorylation.(ABSTRACT TRUNCATED AT 250 WORDS)