[Determination of the contents of mineral elements in the soil where the jinin big-wild ginseng grows]

The element contents in the soil where the Jilin Big-Wild Ginseng grows were determined with plasma emission spectrometry. 23 elements in the soil were found, of which 12 are macro and trace elements indispensable to Ginseng growth. This study provides a scientific basis for selecting suitable soil for planting wild ginseng, or for creating optimum soil conditions for the bumper harvest and high quality of Ginseng.

DNA polymerases alpha and delta are immunologically and structurally distinct

The relationship between DNA polymerases alpha and delta are evaluated immunologically by monoclonal antibody specifically against DNA polymerase alpha and murine polyclonal antiserum against calf thymus DNA polymerase delta. DNA polymerases alpha and delta are found to be immunologically distinct. The structural relationship between the proliferating cell nuclear antigen (PCNA)-dependent calf DNA polymerase delta and DNA polymerase alpha from human and calf was analyzed by two-dimensional tryptic peptide mapping of the catalytic polypeptides. The results demonstrate that the catalytic polypeptides of the PCNA-dependent calf polymerase delta and DNA polymerase alpha are distinct, unrelated, and do not share any common structural determinants. The immunological and structural relationship between a recently identified PCNA-independent form of DNA polymerase delta from HeLa cells was also assessed. This PCNA-independent human polymerase delta was found to be immunologically unrelated to human polymerase alpha but to share some immunological and structural determinants with the PCNA-dependent calf thymus polymerase delta.

Human DNA polymerase alpha: predicted functional domains and relationships with viral DNA polymerases

The primary sequence of human DNA polymerase alpha deduced from the full-length cDNA contains regions of striking similarity to sequences in replicative DNA polymerases from Escherichia coli phages PRD1 and T4, Bacillus phage phi 19, yeast DNA polymerase I, yeast linear plasmid pGKL1, maize S1 mitochondrial DNA, herpes family viruses, vaccinia virus, and adenovirus. The conservation of these homologous regions across this vast phylogenetic expanse indicates that these prokaryotic and eukaryotic DNA polymerases may all have evolved from a common primordial gene. Based on the sequence analysis and genetic results from yeast and herpes simplex virus studies, these consensus sequences are suggested to define potential sites that subserve essential roles in the DNA polymerase reaction. Two of these conserved regions appear to participate directly in the active site required for substrate deoxynucleotide interaction. One region toward the carboxyl-terminus has the potential to be the DNA interacting domain, whereas a potential DNA primase interaction domain is predicted toward the amino-terminus. The provisional assignment of these domains can be used to identify unique or dissimilar features of functionally homologous catalytic sites in viral DNA polymerases of pathogenetic significance and thereby serve to guide more rational antiviral drug design.

Gene expression of human DNA polymerase alpha during cell proliferation and the cell cycle

We studied the expression of the human DNA polymerase alpha gene during cell proliferation, during cell progression through the cell cycle, and in transformed cells compared with normal cells. During the activation of quiescent cells (G0 phase) to proliferate (G1/S phases), the steady-state mRNA levels, rate of synthesis of nascent polymerase protein, and enzymatic activity in vitro exhibited a substantial and concordant increase prior to the peak of in vivo DNA synthesis. In transformed cells, the respective values were amplified greater than 10-fold. In actively growing cells separated into discrete stages of the cell cycle by counterflow elutriation or by mitotic shakeoff, levels of steady-state transcripts, translation rates, and enzymatic activities of polymerase alpha were constitutively and concordantly expressed at all stages of the cell cycle, with only a moderate elevation prior to the S phase and a slight decline in the G2 phase. These findings support the conclusion that the regulation of human DNA polymerase alpha gene expression is at the transcriptional level and strongly suggest that the regulatory mechanisms that are operative during the entrance of a cell into the mitotic cycle are fundamentally different from those that modulate polymerase alpha expression in continuously cycling cells.

Rapid monitoring of intraoperative cerebral blood flow using 133Xe

This study examined the feasibility of rapid rCBF monitoring using 133Xe as a tracer during operative procedures. We compared the initial slope index derived from two bicompartmental and one monocompartmental physiological models. The single-compartment model requires only 3 min of monitoring, whereas the bicompartmental models, thought to be more reliable, require 11 min of clearance. Data were collected from 26 patients undergoing carotid endarterectomy. Approximately 20 mCi of 133Xe in saline was injected i.v. for up to five measurements per patient, for a total of 117 measurements. The robustness of the regression for the three parameters (r = 0.781-0.99, p less than 0.0001) suggests that the three parameters are closely related. This is supported by similarity of the slopes of the regression lines (between 0.944 and 1.25) and the mean +/- SD of the three rCBF models (24.9-27.5 +/- 12.0-14.3 ml 100 g-1 min-1). Similar results were obtained for individual detectors, despite the expected higher variability. For intraoperative use in surgical procedures in which physiological conditions may change rapidly and i.v. injections of tracer must be used, a rCBF index that quickly and accurately reflects flow conditions is useful. Our data suggest that the single-compartmental Wyper index may be used to provide information about cerebral perfusion that is as accurate and robust as bicompartmental models, but requires only one-quarter of the data collection time.

The evolutionary conservation of DNA polymerase alpha

The evolutionary conservation of DNA polymerase alpha was assessed by immunological and molecular genetic approaches. Four anti-human KB cell DNA polymerase alpha monoclonal antibodies were tested for their ability to recognize a phylogenetically broad array of eukaryotic DNA polymerases. While the single non-neutralizing antibody used in this study recognizes higher mammalian (human, simian, canine, and bovine) polymerases only, three neutralizing antibodies exhibit greater, but variable, extents of cross-reactivity among vertebrate species. The most highly cross-reactive antibody recognizes a unique epitope on a 165-180 kDa catalytic polypeptide in cell lysates from several eukaryotic sources, as distant from man as the amphibians. Genomic Southern hybridization studies with the cDNA of the human DNA polymerase alpha catalytic polypeptide identify the existence of many consensus DNA sequences within the DNA polymerase genes of vertebrate, invertebrate, plant and unicellular organisms. These findings illustrate the differential evolutionary conservation of four unique epitopes on DNA polymerase alpha among vertebrates and the conservation of specific genetic sequences, presumably reflective of critical functional domains, in the DNA polymerase genes from a broad diversity of living forms.

Human DNA polymerase alpha gene expression is cell proliferation dependent and its primary structure is similar to both prokaryotic and eukaryotic replicative DNA polymerases

We have isolated cDNA clones encoding the human DNA polymerase alpha catalytic polypeptide. Studies of the human DNA polymerase alpha steady-state mRNA levels in quiescent cells stimulated to proliferate, or normal cells compared to transformed cells, demonstrate that the polymerase alpha mRNA, like its enzymatic activity and de novo protein synthesis, positively correlates with cell proliferation and transformation. Analysis of the deduced 1462-amino-acid sequence reveals six regions of striking similarity to yeast DNA polymerase I and DNA polymerases of bacteriophages T4 and phi 29, herpes family viruses, vaccinia virus and adenovirus. Three of these conserved regions appear to comprise the functional active site required for deoxynucleotide interaction. Two putative DNA interacting domains are also identified.

A method for direct quantification of the amount of DTPA in 111In monoclonal antibody preparations

The bicyclic anhydride of DTPA-1-14C (BADTPA-1-14C) was synthesized and reacted with an antibody to human melanoma associated antigen (MAA) and with one to human class II major histocompatibility complex antigen (HLA-DR). DTPA-1-C incorporation per mole of anti MAA at molar ratios of 1:1 to 200:1 ranged from 0.5 to 25, while immunoreactivity ranged from 49 to 9%. With antibody to HLA-DR, results were similar. Anti MAA, but not anti HLA-DR, demonstrated polymerization upon conjugation. BADTPA-1-14C provides a convenient and accurate method for measuring the amount of DTPA in monoclonal antibody preparations and its effect on immunoreactivity.

Structural and enzymological characterization of immunoaffinity-purified DNA polymerase alpha.DNA primase complex from KB cells

We describe the polypeptide structure and some of the catalytic properties of a DNA polymerase alpha.DNA primase complex that can be prepared from KB cells by immunoaffinity purification. The procedure is based on monoclonal antibodies that were raised against a biochemically purified, catalytically active core protomer of the polymerase. In all respects tested, the basic mechanism of substrate recognition and binding by the immunoaffinity-purified polymerase is qualitatively identical to that of the core protomer. The immunoaffinity-purified KB cell polymerase alpha X DNA primase is structurally complex. On the basis of extensive immunochemical analyses with five independent monoclonal antibodies, three of which are potent neutralizers of polymerase alpha activity, peptide mapping studies, and the application of a sensitive immunoassay that permits detection of polymerase alpha antigens in crude cell lysates, we have established that the principal form of catalytically active DNA polymerase alpha in KB cells is a phosphoprotein with a molecular mass of 180 kilodaltons. This protein is stable in vivo, with an estimated half-life of greater than or equal to 15 h. In contrast, the polypeptide is extremely fragile in vitro and generates partial degradation products of p165, p140, and p125 that explain the "microheterogeneity" typically exhibited by polymerase alpha peptides in denaturing polyacrylamide gels. In addition to the catalytically active polymerase alpha polypeptide(s), the immunopurified enzyme fraction typically contains three other proteins, p77, p55, and p49, the functions of which have not yet been established. These proteins do not display polymerase alpha epitopes and have been shown by peptide mapping to be independent species that are unrelated either to the large polymerase peptides or to one another. The polypeptide p77 is also a phosphoprotein, and in both p180 and p77 the phosphorylated amino acids are exclusively serine and threonine.

The use of radionuclides for tumor therapy

The successful use of radionuclides for tumor therapy depends to a major extent on the ability to achieve a high concentration of radioactivity in the tumor relative to other radiosensitive organs not involved by tumor, such as bone marrow, intestinal mucosa, liver, and kidneys. Techniques designed to achieve such differential localization of the radionuclides include the use of radiopharmaceuticals that enter specific metabolic pathways unique to certain tumor types; radiolabeled antibodies that attach to tumor-associated antigens present on tumor cell surfaces; heterologous antibodies that attach to tumor-associated antigens present on tumor cell surfaces and which are then identified by radiolabeled antibodies directed against the species in which the original, unlabeled antibody was made, and radiolabeled compounds injected regionally at the tumor site. Although both clinical and experimental evidence on the use of radionuclides for tumor therapy is encouraging in preliminary studies, extensive further research needs to be done in this area to insure the clinical efficacy of radionuclides for tumor therapy.

Immunoreactivity and biodistribution of indium-111-labeled monoclonal antibody to a human high molecular weight-melanoma associated antigen

The anti-human, high molecular weight-melanoma associated antigen (HMW-MAA) MoAb 225.28S was chelated with 111In and then tested for its in vitro reactivity with cultured human melanoma cells and for its biodistribution in human melanoma bearing nude mice. In vitro studies showed that the radiolabeled antibody reacted specifically with cultured melanoma cells. However, binding of DTPA to the monoclonal antibody reduced its titer with cultured melanoma cells from 1:1024 to 1:512. Further labeling of the DTPA-antibody conjugate with 111In caused an additional reduction of its titer to 1:128. Injection of the radiolabeled monoclonal antibody into nude mice resulted in the accumulation of significantly (p less than 0.001) higher radioactivity in melanoma tissue than in nude mice injected with either [111In] chloride or 111In-labeled antibody to human acid phosphatase. The specificity of the distribution of the radiolabeled antibody in nude mice also was indicated by its poor localization in lesions other than melanoma (e.g., human prostate carcinoma and chronic abscess). The localization of antibody in liver and kidney was also high, although lower than that achieved in tumor. These results indicate that 111In-labeled monoclonal antibodies to human tumor associated antigens may be useful for localizing malignant lesions. However, there is a need to improve labeling and/or purification of antibody in order to decrease renal and hepatic activity.

Biodistribution of radiolabeled lymphocytes

Factors that might affect the biodistribution and clinical utility of radiolabeled lymphocytes were evaluated in experimental animals. Indium-111 (In-111) labeled lymphocytes (10(7)-10(9) syngeneic or allogeneic cells; 1-10 microCi [.037-.37 MBq]/10(8) cells) obtained from peripheral blood, lymph node, or spleen were found in significant amounts in the lymphoid tissues of Lewis rats as early as 3 hours after infusion. A progressive increase in nodal activity with concomitant fall of activity in other organs followed, indicating active recirculation of the lymphocytes. However, In-111 labeled thymocytes or xenogeneic lymphocytes failed to accumulate in lymphoid tissue. In vitro irradiation of the In-111 labeled lymphocytes (100-400 rads [1-4 Gy]) before in vivo administration and increase of the In-111 to 40 microCi [1.48 MBq]/10(8) lymphocytes resulted in no detectable lymphocyte recirculation and/or reduced localization in lymphoid tissue. Splenectomized animals and those sensitized to an organ allograft before cell infusion showed increased activity in their bone marrow. These results suggest that the source of the injected cells, cell irradiation dose level, and host sensitization should be considered when radiolabeled lymphocytes are being prepared for use in clinical diagnosis and therapy.

Monoclonal antibodies against human DNA polymerase-alpha inhibit DNA replication in permeabilized human cells

Monoclonal neutralizing antibodies against DNA polymerase-alpha substantially inhibit nuclear DNA replication in lysolecithin-permeabilized cultured human fibroblasts. The degree of inhibition of DNA synthesis is proportional to antibody concentration, and the effect is specific in that RNA synthesis measured under the same experimental conditions is unperturbed. Autoradiographic data demonstrate that the magnitude of the inhibition measured in the mass culture reflects the uniform response of all the constituent cells in the target population. These observations confirm the participation of DNA polymerase-alpha in replicative DNA synthesis and identify a versatile, novel approach to the dissection of mammalian processes of DNA replication and repair.

Potential of 109Pd-labeled lymphocytes for selective lymphatic ablation

The biodistribution of lymphocytes labeled with 109Pd was investigated in Lewis rats to determine if they might be useful for selective lymphoid ablation. 109Pd-labeled lymphocytes demonstrated significant lymphoid localization. However, there was a fall in the accumulation of radiolabeled lymphocytes in lymphoid tissue when the 108Pd carrier dose or the 109Pd radioactive dose incorporated per 10(8) lymphocytes was increased from 0.12 mg to 0.20 mg and from 21.3 microCi to 54.6 microCi, respectively (P less than 0.001). 109Pd-labeled syngeneic and allogeneic lymphocytes demonstrated similar tissue distribution patterns. These results raise the possibility of using 109Pd-labeled lymphocytes for selective lymphoid ablation, but emphasize the need for using high specific activity 109Pd and large amounts of lymphocytes for labeling. This will minimize cell damage and allow maximum therapeutic results to be obtained. The use of large numbers of cells might best be accomplished by using donor lymphocytes.

A comparison of the cyclic anhydride and mixed anhydride methods for 111In-DTPA chelation to monoclonal antibodies

The cyclic anhydride (CA) and the mixed anhydride (MA) of DTPA were synthesized and used to chelate 111In to an antimelanoma monoclonal antibody. The CA and MA methods showed mean labeling efficiencies of 25.7 and 20.5%, respectively (p = NS). The binding efficiency of labeled antibody to human melanoma cells in tissue culture also was similar (means = 52 and 50%, respectively, p = NS), as was tumor uptake in nude mice at 96 hrs post-injection (16%-CA vs 12%-MA). The method required less complicated chemical syntheses, much less preparation time, and the product was stable over a much longer period. The results suggest that the CA method is preferable for bifunctional chelate labeling of monoclonal antibodies with 111In-DTPA.

Potential of palladium-109-labeled antimelanoma monoclonal antibody for tumor therapy

Palladium-109, a beta-emitting radionuclide, was chelated to the monoclonal antibody 225.28S to the high molecular weight antigen associated with human melanoma. The radiolabeled antibody maintained its specific in vitro reactivity with cultured human melanoma cells. Injection of the radiolabeled monoclonal antibody into nude mice bearing human melanoma resulted in significant accumulation of the radiolabel in the tumors: 19% injected dose/g; 38:1 and 61:1 tumor-to-blood ratios at 24 and 48 hr, respectively. The localization of the radiolabeled antibody in liver and kidney also was high, but appreciably lower than that achieved in tumor. These results suggest that Pd-109-labeled monoclonal antibody to tumor-associated antigens may have potential applications in tumor immunotherapy.

DNA primase from KB cells. Evidence for a novel model of primase catalysis by a highly purified primase/polymerase-alpha complex

The oligonucleotide primers synthesized by a highly purified KB fraction containing DNA primase and DNA polymerase-alpha activities display reproducible alterations of structure and composition in response to dNTPs. These observations are sufficiently explained by a novel model of primase catalysis that defines the primase as a complex enzyme with distinct catalytic properties that are regulated by mechanisms exquisitely sensitive to dNTP concentration. The enzyme performs the template-directed, de novo synthesis of 1 unit of oligoribonucleotide (canonical priming reaction) and then elongates that moiety to a limited extent by several cycles of addition of short tracts of homogeneous oligoribonucleotide or oligodeoxynucleotide. The oligomeric units have modal lengths of approximately 11- to 14- nucleotides that are postulated to reflect the inherent processivity of the catalytic mechanisms. Elongation is accomplished by two catalytic centers, or conformers of a single center, that are synchronously coupled, mutually exclusive, and extremely stringent for respective rNTP and dNTP substrates. Transitions between these two catalytic modes are regulated by dNTPs and demonstrable at dNTP:rNTP concentrations of less than or equal to 10(-4). In the absence of dNTPs, the primase produces a family of oligoribonucleotides, approximately 24- to 36- nucleotides long; at dNTP levels between 0.08 and 0.80 micron, the primase synthesizes mixed oligomers composed of strictly alternating tandem arrays of oligoribo- and oligodeoxynucleotide units; and at dNTP levels greater than or equal to 4.8 micron, the primase becomes stabilized in the deoxy mode after the initial oligoribo leads to oligodeoxy transition and products contain only a single 5' -terminal unit of oligoribonucleotide. The model predicts that the physiologically significant primer for DNA polymerase-alpha is a mixed 5' -oligoribo-3' -oligodeoxynucleotide and the signal which governs the switch from RNA leads to DNA synthesis is intrinsic in the primase mechanism and is generated by ambient dNTPs.

DNA primase from KB cells. Characterization of a primase activity tightly associated with immunoaffinity-purified DNA polymerase-alpha

A very highly purified fraction of KB cell DNA polymerase-alpha, prepared with a monoclonal antibody, contains DNA primase activity. The primase synthesizes oligonucleotide chains initiated with ATP in a reaction that is resistant to alpha-amanitin and strictly dependent on added template and ribonucleoside triphosphates (rNTPs). In the presence of added dNTPs and M13 DNA template, the primase produces a uniform population of oligoribonucleotides, predominantly hexamers to decamers, that are extended by polymerase-alpha into DNA chains up to 3000 nucleotides long. There is no evidence for nucleotide preferences at RNA/DNA junctions. In the absence of added dNTPs, the oligomeric products are heterogeneous in size and composition and susceptible to cleavage by pancreatic DNase I due to their content of short oligodeoxynucleotide tracts synthesized by primase from trace contaminant dNTPs in the rNTP substrates. The primase and polymerase-alpha activities are distinguishable by several physical and chemical criteria, and the primase reaction is only partially sensitive to two potent, independent monoclonal antibodies that neutralize polymerase-alpha. Although the presence of both primase and polymerase-alpha activities in a highly purified immune complex prepared with a monoclonal antibody argues for their tight physical association, the chemical, physical, and immunological discriminations indicate the two catalytic entities are functionally and structurally distinct.