Immunochemical demonstration of tropomyosin in the neurofibrillary pathology of Alzheimer's disease

The focus of research on the neurofibrillary pathology (NFP) of Alzheimer disease has been not only to determine the component forming the paired helical filaments but also to determine whether they result from abnormal processes affecting a single protein. Therefore, although these studies have lead to controversy concerning the respective contribution of components of microtubules and neurofilaments, there has been essentially no consideration of whether other cytoskeletal systems might also be involved and of what are the common features for the incorporated components. Particularly relevant to this issue is our finding that several antisera raised to either skeletal or smooth muscle tropomyosin, a microfilament component, intensely recognize NFP. These antibodies continue to recognize NFP after affinity purification to tropomyosin or paired helical filament fractions. We show that the antibodies do not recognize NFP due to cross-reactivity with the previously identified NFP components related to neurofilaments and microtubules, tau, and MAP2, or neurofilament proteins because the antisera did not recognize these proteins on immunoblots or were not adsorbable by the proteins. Ultrastructural analysis of the immunoreaction showed that tropomyosin-related epitopes were clustered rather than uniformly distributed along paired helical and straight filaments. Although the distribution suggests that tropomyosin is an NFP-associated protein, its retention by paired helical and straight filaments after detergent extraction indicates that it is an integral component strongly and specifically associated with the filaments characteristic of NFP. These findings indicate that NFP involves the three primary neuronal cytoskeletal filament systems, microtubules, neurofilaments, as well as microfilaments, and therefore that NFP probably results from the reorganization of these normal filaments that interact to comprise the cytomatrix and may continue this interaction under the pathologic condition of Alzheimer's disease to generate novel, abnormal polymers.

Molecular analysis of insertion/deletion mutations in protein 4.1 in elliptocytosis. II. Determination of molecular genetic origins of rearrangements

Protein 4.1 is an approximately 80-kD structural protein in the membrane skeleton which underlies and supports the erythrocyte plasma membrane. The preceding companion paper presents a biochemical study of two abnormal protein 4.1 species from individuals with the red blood cell disorder, hereditary elliptocytosis. These variants, "protein 4.1(68/65)" and "protein 4.1(95)," have altered molecular weights due to internal deletions and duplications apparently localized around the spectrin-actin binding domain. Here we use polymerase chain reaction (PCR) techniques to clone and sequence the corresponding mutant reticulocyte mRNAs, and correlate the deletion/duplication end points with exon boundaries of the gene. Protein 4.1(68/65) mRNA lacks sequences encoding the functionally important spectrin-actin binding domain due to a 240 nucleotide (nt) deletion spanning the codons for Lys407-Gly486. Protein 4.1(95) mRNA encodes a protein with two spectrin-actin binding domains by virtue of a 369 nt duplication of codons for Lys407-Gln529. These deletions and duplications correspond to gene rearrangements involving three exons encoding 21, 59, and 43 amino acids, respectively. The duplicated 21 amino acid exon in the 4.1(95) gene retains its proper tissue-specific expression pattern, being spliced into reticulocyte 4.1 mRNA and out of lymphocyte 4.1 mRNA.

Prediction of the resistance of human tumors to adriamycin by chemosensitivity tests and DNA analysis of the multidrug resistance gene

In order to predict natural resistance to Adriamycin (ADM), the amplification of multidrug resistance gene 1 (MDR1) was investigated in 50 human cancer specimens using Southern blot analysis. Genomic DNA was extracted from both human solid tumors and adjacent normal tissues for the analysis. MDR1 gene amplification was not observed in any of the patients tested, including 5 patients in whom ADM was not clinically effective. On the other hand, chemosensitivity tests performed on the tumor cells of these 5 patients indicated resistance to ADM. Our results therefore indicate that MDR1 gene amplification is rarely seen among clinical samples and that conventional chemosensitivity tests might be more useful for the prediction of ADM resistance in cancer patients than the analysis of MDR1 gene amplification.

Antitumor effect of KW2149, a new mitomycin derivative, administered by different modalities

The effectiveness of a new mitomycin derivative, KW2149, against human tumors was evaluated by the 4 days subrenal capsule assay (SRCA) and the nude mice screening assay (NMSA). Evaluation by the SRCA showed a 50% response rate at a maximum dose of 3.8 mg/kg for 3 consecutive days. When evaluated by NMSA, the response rate was 100, 75 and 25% after the intermittent administration of 7.5, 5.6 and 4.5 mg/kg (q4dx3) respectively. Although the efficacy was reduced when mice were administered a single dose equivalent to the intermittent one, the new analog was along more effective than MMC administered by either modality.

Redesigning a sweet protein: increased stability and renaturability

Monellin is one of two natural proteins from African berries with potent sweet taste. Monellin is the smaller of the two, and consists of two peptides. The protein loses sweetness when heated above 50 degrees C under acidic pH. Based on the crystal structure of monellin we have fused the two chains into a single chain using several different linkers copied and 'transplanted' from the same molecule. One of the newly designed proteins is as potently sweet as the natural one, is more stable upon temperature or pH changes, and renatures easily even after heating to 100 degrees C at low pH.

Genetic and pharmacological suppression of oncogenic mutations in ras genes of yeast and humans

The activity of an oncoprotein and the secretion of a pheromone can be affected by an unusual protein modification. Specifically, posttranslational modification of yeast a-factor and Ras protein requires an intermediate of the cholesterol biosynthetic pathway. This modification is apparently essential for biological activity. Studies of yeast mutants blocked in sterol biosynthesis demonstrated that the membrane association and biological activation of the yeast Ras2 protein require mevalonate, a precursor of sterols and other isoprenes such as farnesyl pyrophosphate. Furthermore, drugs that inhibit mevalonate biosynthesis blocked the in vivo action of oncogenic derivatives of human Ras protein in the Xenopus oocyte assay. The same drugs and mutations also prevented the posttranslational processing and secretion of yeast a-factor, a peptide that is farnesylated. Thus, the mevalonate requirement for Ras activation may indicate that attachment of a mevalonate-derived (isoprenoid) moiety to Ras proteins is necessary for membrane association and biological function. These observations establish a connection between the cholesterol biosynthetic pathway and transformation by the ras oncogene and offer a novel pharmacological approach to investigating, and possibly controlling, ras-mediated malignant transformations.

The histological assessment and evaluation of a 4 day subrenal capsule assay by the percentage inhibition of DNA/protein

A four day subrenal capsule assay was investigated in order to determine its ability to clinically predict tumor chemosensitivity. To establish more objective and accurate evaluation criteria, a histological assessment and measurement of the DNA and protein content of excised tumor implants was conducted in ddY mice. The histological studies provided qualitative results concerning the percentage of cancer cells in the xenograft, the number of mitoses, the amount of necrosis, and the extent of lymphocytic infiltration. The DNA content was measured by a modified version of the Schmidt-Thannhauser-Schneider method and the protein content was estimated using the Bio-Rad protein assay. The percentage of cancer cells in the xenograft correlated poorly with the relative increase in tumor size, weight and the percentage inhibition of DNA/protein (per cent DNA/protein), however, the per cent DNA/protein correlated well with the clinical effects in 85.7 per cent of the tumors studied. Moreover, the histological assessment information was only consistent with those results obtained for per cent DNA/protein in the control group.

Chemosensitivity tests in colorectal cancer patients

In order to assess the usefulness of chemosensitivity tests in the treatment of colorectal cancer, 71 tumor specimens were tested for chemosensitivity in the following assays: nude mouse isotope assay (NMIA), subrenal capsule assay (SRCA), human tumor clonogenic assay (HTCA) and adenosine triphosphate inhibition assay (ATPA). The agents examined were: mitomycin C (MMC), 5-fluorouracil (5-FU), cyclophosphamide (CPM), adriamycin (ADM) and cis-diamminedichloroplatinum (CDDP). The evaluability rates were 90.8, 93.9 and 92.3 per cent in NMIA, SRCA and ATPA, respectively, but only 42.9 per cent in HTCA. The tumor response rates were 50.8, 45.2, 16.7 and 33.3 per cent in NMIA, SRCA, HTCA and ATPA, respectively. Individual drug sensitivity rates differed among all 4 assays, ranging from 0 to 33.3 per cent. In the arbitrary judgment of the 4 assays, the most sensitive agent was CDDP, followed by CPM, ADM, 5-FU and MMC. In the prospective study, predictive accuracy rates of the clinical responses were 81.3, 66.7, 100, 100 and 76.5 per cent in NMIA, SRCA, HTCA, ATPA and the arbitrary judgment, respectively. A significant correlation between the survival time and the results of SRCA was detected retrospectively. These results suggested that colorectal cancer might not be completely resistant to anticancer agents, and that chemosensitivity tests might be useful in the individual therapy of colorectal cancer patients.

[Comparative study on the anticancer activities of KW2149 and mitomycin C against human tumor xenografts using subrenal capsule assay]

The anticancer activity of KW2149, a new derivative of mitomycin C (MMC), was investigated against 5 human tumor xenografts derived from digestive organs using 4-day subrenal capsule assay (SRCA). Normal immunocompetent mice were used in this assay. For the comparative study, KW 2149 and MMC were administered intraperitoneally for 3 days after implantation, and the anticancer activity and the weight loss of mice were evaluated. The total doses were determined as 1/2, 1/3 and 1/4 of LD50 value of each anticancer agent. The anticancer activities of the two drugs were almost the same with no significant difference in 3 xenografts. Thus, it may be suggested the difference of the anticancer spectrum between the two drugs. The anticancer activity of KW2149 indicated higher correlation with the administered doses as compared with MMC. The toxicity of KW2149 was almost the same as MMC according to the weight loss of mice.

[Comparison of succinic dehydrogenase inhibition test with adenosine triphosphate inhibition assay for human solid tumors as in vitro chemosensitivity tests]

In order to determine the most effective anticancer agents for individual human tumor, succinic dehydrogenase inhibition test (SDI-T) and adenosine triphosphate inhibition assay (ATP-A) as in vitro chemosensitivity tests were performed. Fifty tumors and 57 tumors derived from cancer patients surgically methods were examined by SDI-T and ATP-A respectively. As the results, the evaluable rate was 70% by SDI-T and 94.7% by ATP-A, respectively. With SDI-T, the positive rate against all tumors was 51.4% in mitomycin-C (MMC), 42.9% in adriamycin (ADM), 20.0% in 5-fluorouracil (5-FU), 54.3% in cis-diamminedichloroplatinum (CDDP). On the other hand, with ATP-A, that was 20.4% in MMC, 29.5% in ADM, 20.6% in 5-FU, 20.4% in CDDP, respectively. Retrospective and prospective clinical trials were also carried out to determine the usefulness of both assays. With SDI-T, overall predictive accuracy rate was 57.1% while with ATP-A that was 88.9%. Furthermore, the rates of sensitivity for the same tumors using SDI-T and ATP-A were compared. The rate of the same sensitive cases in both assays were 30% with MMC, 70% with 5-FU, 42.1% with ADM, 36.8% with CDDP, respectively. In conclusion, it is suggested that ATP-A was more useful than SDI-T as in vitro chemosensitivity test to determine the most adequate drug for cancer patients.

[Combination chemotherapy of CPM-MTX-5-FU in non-resectable and recurrent cancer patients]

Fifty-two non-resectable and recurrent cancer patients with prior treatment, were entered in this study; 1 esophageal, 33 gastric, 1 duodenal, 4 colorectal, 2 pancreatic, 2 bile duct, and 9 breast cancer. The protocol of this therapy was as follows: On day 1, 500 mg/body cyclophosphamide (CPM) was administered by drip infusion, and on day 2, 200 mg/m2 methotrexate (MTX) was infused intravenously for 30 min; immediately after, 500 mg/body 5-fluorouracil (5-FU) was injected by bolus infusion for 5-10 min. On day 3, 24 hours after MTX administration, leucovorin rescue was added. This combination chemotherapy was repeated every two weeks. As a result, 35 of 52 patients were evaluable and the response rate (CR + PR) was investigated; 2/21 (9.5%) for gastric, 2/7 (28.6%) for breast, and 0% for miscellaneous. As complications for side effect, general fatigue, anorexia, nausea, vomiting and stomatitis were observed symptomatically, and leukopenia and thrombocytopenia were recognized in laboratory data as dose limiting factors.

Induction of cytotoxicity from fresh splenocytes after in vivo administration of cyclophosphamide. Importance of long-term culture with high-dose recombinant interleukin-2

Cyclophosphamide, combined with lymphokine-activated killer (LAK) cells and recombinant interleukin-2 (rIL-2), is known to mediate regression of tumors, but the effects of cyclophosphamide on the subsequent generation of LAK cells are unclear. It was the aim of the experiments in this paper to determine whether fresh splenocytes cultured with rIL-2 would maintain or regain their cytotoxicity in vitro after being exposed to the cytotoxic agent cyclophosphamide in vivo. Functional monitoring of splenocytes after in vitro incubation with rIL-2 was performed at various times through chromium-release assays, thymidine assays and cell-cycle analysis. Chromium-release assays determined that the cytotoxicity of cultured splenocytes returned to normal after 12 days of in vitro culture with rIL-2. The thymidine assays indicated a normal rate of uptake of thymidine after 7 days in culture, while the cell cycle was still abnormal by day 12 of culture. The growth and expansion of rIL-2-activated splenocytes after different times of in vitro culture indicated a return to normal compared to control animals after 7 days of continuous in vitro exposure to rIL-2. It is concluded that murine splenocytes can demonstrate cytotoxicity after exposure to cyclophosphamide, through prolonged continuous in vitro culture with rIL-2. Since cyclophosphamide did not jeopardize the production of splenocyte cytotoxic effectors generated with rIL-2, it appears to be a strong contender for use in chemoimmunotherapy protocols.

Expression of the mouse metallothionein-I gene in Escherichia coli: increased tolerance to heavy metals

The cDNA of mouse metallothionein, a small metal-binding protein rich in cysteine, has been cloned downstream from a bacterial inducible promoter and expressed in Escherichia coli. Upon induction, E. coli harboring this cDNA clone contained a protein species readily labelled by [35S]cysteine in vivo and incorporated 10-times as much 109Cd from the medium than would otherwise be the case. We show that expression of metallothionein endows resistance in E. coli to heavy metal ions such as mercury, silver, copper, cadmium and zinc by sequestering rather than exclusion or conversion, common mechanisms of metal resistance in bacteria.

[Anticancer activities of a new mitomycin derivative KW 2149, against human tumors xenografted into nude mice]

Anticancer activity of KW 2149, a new derivative of mitomycin C (MMC), was investigated using 4 human tumors xenografted into nude mice. The basic methodology was essentially the same with NCI's therapeutic protocol. For the comparative study, KW 2149 or MMC was administered intraperitoneally at a schedule of q4d X 3. Daily doses were determined as a 1/3, 1/4 and 1/5 of LD50 value of each anticancer agent (7.5 mg/kg, 5.6 mg/kg and 4.5 mg/kg for KW 2149, and 2.7 mg/kg, 2.1 mg/kg and 1.7 mg/kg for MMC). Anticancer activity of KW 2149 seemed to be dependent on the doses. Comparing with MMC, KW 2149 produced higher response rates at the doses of 1/3 and 1/4 of LD50 and was less toxic judging from the decrease of the body weight. This study may indicate an utility of KW 2149, as a new anticancer agents, or suggest the difference of anticancer activities between these two agents.

[Inhibition of thymidylate synthetase and antiproliferative effect by 1-hexylcarbamoyl-5-fluorouracil]

In order to estimate tumor chemosensitivity of fluoropyrimidine derivative, inhibition of thymidylate synthetase (TS) was investigated using a nude mouse experimental system. Four human tumors xenografted in nude mice; H-111, SH-8 and SH-10, each established from gastric cancer, and EH-1 from esophageal cancer, were used. When the transplanted tumor volumes reached to approximately 200 mm3, 1-hexylcarbamoyl-5-fluorouracil (HCFU) was given for 5 days. Tumors was removed for the measurement of total and free TS at 0 hr, 6 hrs and 24 hrs after the last administrations. Simultaneously, the anti-proliferative effects were investigated according to the therapeutic protocol of NCI. No positive correlation between the inhibition rate of TS and the anti-proliferative effects was observed, although the absolute values of free TS were similar to the tumor inhibition rates. The measurement of total TS provided a highest concentration in SH-8, while extremely low in EH-1. On the analysis of free TS, a significant increase of the concentration was observed at 24 hrs after the last administration compared with at 6 hrs in SH-8. These results indicate that free TS had a potentiality as a new parameter for predicting tumor chemosensitivity of fluoropyrimidine derivative and the analysis of TS should be affected strongly by the characteristics of enzymic activity of examined tumor.

[Combined effects of interferon alpha-A/D with fluoropyrimidine derivatives in the subrenal capsule assay]

The combined effects of interferon alpha-A/D (IFN alpha-A/D) with 5-fluorouracil and fluoropyrimidine derivatives such as 1-(2-tetrahydrofuryl)-5-fluorouracil (tegafur), UFT, 1-hexylcarbamoyl-5-fluorouracil (HCFU) and 5'-deoxy-5-fluorouracil (5'-DFUR), were examined by 4-day subrenal capsule assay. Four human tumor xenografts serially transplanted in athymic mice, H-111, SH-10 established from gastric cancers, CH-4 and CH-5 from colon cancers, were used. In this experiment, the adequate dose of each agent was estimated as 50 mg/kg for 5-FU, 473 mg/kg for tegafur, 433 mg/kg for UFT, 50 mg/kg for HCFU, 185 mg/kg for 5'-DFUR and 1 x 10(5) IU for IFN alpha-A/D, respectively. When synergistic, additive and subadditive effects were defined as positive combined effects, all combinations produced positive combined effects against H-111 and CH-5, while negative ones were observed for all combinations against CH-4. The combinations of 5-FU, HCFU and 5'-DFUR with IFN alpha-A/D produced synergistic effects against SH-10. These results indicate that the combination therapy of 5-FU and fluoropyrimidine derivatives with IFN alpha-A/D would be useful.

One strand of ars189 from the maxicircle of Crithidia fasciculata transforms Saccharomyces cerevisiae more efficiently than its complementary strand as a single stranded DNA

An autonomously replicating element (ars189) has been isolated from the maxicircle DNA of an insect trypanosomatid Crithidia fasciculata. This 189-bp fragment contains two copies of the yeast consensus ARS sequence of (A/T)TTTATPuTTT(T/A), has an A + T composition of 79.4%, and shows a large asymmetry in the distribution of adenine and thymine residues between the two strands. The complementary strands of ars189 have been cloned into an M13 vector containing the URA3 gene of Saccharomyces cerevisiae. When these circular single-stranded (ss) DNAs were used to transform yeast spheroplasts, the M13 chimeric DNA carrying the strand of ars189 rich in adenine generated approximately four times more yeast Ura + transformants than the construct containing the thymine-rich strand. In contrast, both strands of yeast ARS1 cloned into an M13 vector transformed yeast at an equivalent level. The conversion of ARS-containing ss DNAs to duplex forms in vivo and their subsequent autonomous replication have been verified by Southern hybridization analysis of extracts from yeast transformants.

Conservation of a 29-base-pair sequence within maxicircle ARS fragments from six species of trypanosomes

The maxicircles from Trypanosoma brucei, Herpetomonas samuelpessoai, Leptomonas seymouri, and Phytomonas davidi were examined for the presence of a 29-bp sequence termed CF29 that has been found in the ars 189 sequence from the Crithidia fasciculata maxicircle and in Lt-ars 189 from the maxicircle of Leishmania tarentolae. The CF29 sequence also contains a yeast consensus ARS of (T/A)TTTATPuTTT(T/A). All of the maxicircles examined contained specific fragments that hybridized to the CF29 probe. The non-replicating yeast plasmid vector YIp5 was used to clone these CF29-containing maxicircle fragments. High-frequency transformation was observed when these chimeric plasmids were used to transform Saccharomyces cerevisiae. Autonomous replication of these transforming plasmids was verified by Southern analysis of yeast-cell extracts using pBR322 as a hybridization probe. Therefore it appears that the CF29 sequence is widely conserved in kinetoplastid protozoa and is associated with ARS sequences in the maxicircles. Hybridization of the CF29 probe to a population of P. davidi minicircles was also observed. However, the YIp5 chimeric plasmid containing this CF29-hybridizing minicircle fragment failed to transform yeast.

'Interactive' recognition in EcoRI restriction enzyme-DNA complex

A solution study of interaction between DNA and EcoRI restriction enzyme shows that there is a definite distortion of DNA in the specific recognition complexes but no measurable DNA distortion in the non-specific interaction.

Isolation of gram quantities of EcoRI restriction and modification enzymes from an overproducing strain

Structural genes for EcoRI restriction endonuclease and modification methylase have been inserted into the plasmid vector pKC30 (Shimatake, H., and Rosenberg, M. (1981) Nature (Lond.) 292, 128-132) downstream from the bacteriophage lambda pL promoter. Upon induction of pL expression in strains producing a thermolabile lambda cI857 repressor, synthesis of EcoRI polypeptides is enhanced to the extent that after 4 h they represent several per cent of the total cell protein. Purification of activities overproduced in this manner yields preparations of endonuclease and methylase which appear identical to those obtained from conventional sources, with overall yields corresponding to 0.5 to 0.9 g of each enzyme/kg of cell paste.

A 189-bp fragment of Crithidia fasciculata maxicircle DNA confers autonomous replication in Saccharomyces cerevisiae

A 189-bp fragment capable of promoting high-frequency transformation in Saccharomyces cerevisiae has been isolated from the maxicircle of the insect trypanosomatid Crithidia fasciculata. Chimeric plasmids containing this autonomously replicating sequence (ars) are maintained as extrachromosomal elements in S. cerevisiae. The nucleotide sequence of the maxicircle fragment, termed ars189, has been determined, and its position has been mapped in the maxicircle. The ars189 fragment has an A + T content of 79.4% and shows a large asymmetry in the distribution of adenine and thymine residues between the two strands. In one strand (the T strand) thymine accounts for 118 out of 189 nucleotides while adenine accounts for only 32 nucleotides. The ars189 DNA does not hybridize with minicircles, and its sequence appears to be unique in the C. fasciculata maxicircle genome. This sequence also shows extensive homology to a sequence within a 2.6-kb ars fragment of the Leishmania tarentolae maxicircle. In addition, ars189 contains two copies of a yeast consensus ars sequence (A/T)TTTATPuTTT(T/A).