Diffusion-weighted MRI as a potential imaging biomarker reflecting the metastatic potential of upper urinary tract cancer

OBJECTIVE

To evaluate the role of diffusion-weighted MRI (DW-MRI) as an imaging biomarker for upper urinary tract cancer (UUTC) that has already metastasized or will metastasize soon.

METHODS

61 patients clinically diagnosed with UUTC were prospectively enrolled in this study. All the patients underwent MRI, including DW-MRI, prior to any interventions. Correlations between apparent diffusion coefficient (ADC) and other clinicopathological variables, including metastasis-free survival, were analysed.

RESULTS

Median follow-up period was 938 days. Of the 61 patients, 12 had any metastases at the initial diagnosis. 11 patients developed metastases during the follow-up period. These 23 patients were categorized as "Metastatic". Of the remaining 38 patients, 35 with a follow-up period longer than 400 days were categorized as "Localized". ADC was significantly lower in the Metastatic category than in the Localized (p = 0.0002) category. Multivariate analysis of pre-operative variables identified ADC (cut-off value, 1.08 × 10(-3) mm(2) s(-1)) and clinical T stage based on T2 weighted MRI as an independent predictive factor of metastatic UUTC. 46 patients without any metastases during the initial diagnosis were stratified into a high-risk group (16 patients with low ADC and clinical T3-4) and a low-risk group (30 patients with high ADC or clinical Ta-2). The 3-year metastasis-free survivals were 45% and 93%, respectively.

CONCLUSION

In the current study, UUTC with lower ADC value is more likely to have metastatic potential. Incorporating ADC with clinical T stage helps to differentiate metastatic UUTC at the initial diagnosis.

ADVANCES IN KNOWLEDGE

DW-MRI is a potential imaging biomarker reflecting metastatic propensity of UUTC.

A novel repeat biopsy nomogram based on three-dimensional extended biopsy

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Background: There is no perfect cohort in which nomograms are developed because no biopsy method can detect all cancers. To minimize this inherent verification bias, having a cohort with fewer false negative cases is advantageous. Based on a cohort examined with three-dimensional (3D) extended biopsy protocol, we developed a novel nomogram for diagnosis of prostate cancer on repeat biopsy.

Methods: Of 4,074 consecutive male patients undergoing prostate biopsy at our institutions between 2000 and 2009, 775 men with at least one previous negative biopsy underwent repeat biopsy with 3D protocol. Men with previous atypical glands or atypical small acinar proliferation and/or without available prostate-specific antigen (PSA) kinetics information were excluded. The remaining 515 men constituted the study cohort. We developed a logistic regression-based nomogram with 70% of the cohort selected randomly; we validated it with the remaining 30%. Predictive accuracy and performance characteristics were assessed using the area under the receiver operating characteristic curve (AUC) and calibration plots, respectively. The threshold probability was evaluated with decision curve analysis.

Results: We developed a novel repeat biopsy nomogram incorporating age, free to total PSA ratio, prostate volume, history of previous extended biopsy, and PSA doubling time. Validation confirmed predictive accuracy with an AUC value of 0.791. Calibration plots showed good agreement. The decision curve of the nomogram was superior to the decision curve of biopsying all men in a range of threshold probability over 0.15. At the threshold of 0.2, the number of unnecessary biopsies could be reduced by 10 per 100, without missing PCa.

Conclusions: We developed a novel repeat biopsy nomogram based on a cohort examined with 3D extended biopsy. This repeat biopsy nomogram is clinically beneficial, saving a substantial number of unnecessary biopsies.

No significant financial relationships to disclose.

Maintenance of the suppressed level of serum testosterone by administration of three-monthly formulations of luteinizing hormone-releasing hormone agonists at six-month intervals in Japanese patients with prostate cancer: A prospective study

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Background: Treatment with an LH-RH agonist is a standard alternative to surgical castration for prostate cancer patients. The serum testosterone level is kept at castrate levels continuously during LH-RH agonist therapy in almost all patients (Fujii Y, BJU Int 2008). LH- RH agonists, however, are more expensive than surgical castration, with drugs costing between US $300 and $500 per month in Japan. Recent studies suggest that 3-monthly formulations of LH-RH agonists suppress the serum testosterone levels far longer than the 3-month dosing interval.

Methods: A total of 43 Japanese patients with prostate cancer who were treated with 3-monthly LH-RH agonists (23 with 11.25mg leuprolide, and 20 with 10.8 mg goserelin) for one year or longer and whose testosterone levels were kept at castrate level (defined as < 50 ng/dL) were entered into this prospective, longitudinal study. After entry, the 43 men received the same 3-monthly LH-RH agonists at 6-month intervals, and had serum LH and testosterone tests performed at 3-month intervals. Bicalutamide was combined with the LH-RH agonists in 12 of the patients.

Results: At entry, median patient age was 74 years (range 59 to 89), median duration of LH-RH agonists treatment was 26 months (12 to 125), and median LH and testosterone levels were <10 ng/dL (<10 to 60) and 5 ng/dL (<5 to 18), respectively. The 43 patients received a total of 162 administrations (median 5, range 1 to 6) of the LH-RH agonists at 6-month intervals, and had a total 335 hormonal tests (median 10, range 2 to12) performed during the median followup period of 30 months. Serum LH and testosterone levels were kept suppressed during the treatment. Of the 43 patients, two had serum testosterone just above the castrate level (54 and 56 ng/dL) once each among their 12 and 8 hormonal assays, respectively.

Conclusions: Administration of 3-monthly LH-RH agonists, either leuprolide or goserelin, at 6-month intervals could maintain the castrate level of serum testosterone at least in Japanese prostate cancer patients who have received LH-RH agonists treatment for one year or longer.

No significant financial relationships to disclose.

Use of C-reactive protein to predict perinephric or renal sinus fat invasion in patients with clinical T1N0M0 renal cell carcinoma

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Background: Indication of nephron sparing surgery (NSS) for renal cell carcinoma (RCC) has been extending, as NSS can be considered for not only cT1a but also cT1b tumors. However, some cT1 diseases have pathological perinephric or renal sinus fat invasion. It is useful to know the probability of the presence of fat invasion before surgery, but diagnostic ability of imaging studies such as CT for predicting pT3a disease is limited. Therefore, estimation of the risk for pT3a disease in cT1 RCC patients could be helpful. C-reactive protein (CRP) has been shown to be a strong prognostic factor in RCC patients, reflecting tumor aggressiveness. We evaluated the predictive ability of preoperative CRP for pT3a disease in cT1N0M0 RCC patients.

Methods: Of consecutive 386 patients treated with radical nephrectomy for cT1a-bN0M0 RCC, 82 were excluded due to hemodialysis, inflammatory disease, bilateral synchronous renal tumors, synchronous other malignant disease or loss of each data. The remaining 304 patients constituted the current study cohort. Cut off point of CRP was 3 mg/L. Associations were analyzed between pT3a and preoperative factors including age, sex, BMI, laterality, tumor size, CRP, hemoglobin, platelet, LDH, ALP, calcium and albumin. We developed a multivariate model for predicting pT3a disease in cT1 RCC.

Results: Of the 304 patients, 28 (9%) had pT3a disease. Of 43 patients with elevated CRP level, 10 (23%) had pT3a disease. In contrast, of the remaining 261 patients with non-elevated CRP level, 18 (7%) had (p=0.002). Univariate and then multivariate analyses identified age (p=0.021), tumor size (p=0.007), and CRP (p=0.024) as independent and significant predictors for pT3a disease. Incorporating these three factors, we developed a predictive model for pT3a disease with predictive accuracy of area under the ROC curve of 0.772.

Conclusions: Preoperative CRP is an independent predictor for pT3a disease in cT1 RCC along with age and tumor size. The model could be useful to estimate the risk of the probability of fat invasion before surgery, especially NSS.

No significant financial relationships to disclose.

Surgical outcomes of gasless single port retroperitoneal radical nephrectomy for dialysis patients: A comparative analysis with nondialysis patients

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Background: Gasless single port retroperitoneal radical nephrectomy is minimally invasive, curative and cost effective operation which we have developed since 1998 (Eur Urol Suppl 2009; 8: 392), and covered by the Japanese universal insurance system from April, 2008. Patients necessitating dialysis are considered high risk operative candidates because of their multiple comorbidities. We compared surgical outcomes of dialysis patients with non-dialysis patients to evaluate this operation as treatment for high risk group.

Methods: We reviewed 304 consecutive patients including 59 (19.4%) dialysis patients who underwent CO2 gasless single port retroperitoneal radical nephrectomy at our institute between 2000 and 2009. Complications within the first 30 days after the surgery were graded retrospectively according to the modified Clavien classification system. Patient demographics, operative outcomes, and complications were compared between dialysis and non-dialysis patients.

Results: In all patients, the median patient age and body mass index were 60 years and 23.0 kg/m2. The median length of surgical incision, operative time (OT) and estimated blood loss (EBL) were 6.5 cm, 189 minutes and 214 mL, respectively. The transfusion rate was 3.3%. The intra and postoperative complication rate were 3.9% and 10.1%. Two grade 3a (ureteral obstruction, 1; diverticulitis, 1), three grade 3b (occlusion of peripheral hemodialysis shunt, 3) and two grade 4 (pulmonary embolism, 1; acute heart failure, 1) surgical complications occurred. In dialysis patients, the mean BMI was lower (20.4 vs. 23.3, p<0.0001), the mean OT was shorter (170 vs. 201 minutes, p<0.0001) and the mean EBL was lower (216 vs. 311mL, p<0.0001) than non-dialysis patients. There was no Clavien grade 3 or 4 surgical complications except dialysis access occlusion in dialysis patients. The average time to oral feeding and walking were equivalent, but possible discharge were longer in dialysis patients (4.3 vs. 3.4 days, p<0.0037).

Conclusions: Our data supports the safety and feasibility of gasless single port retroperitoneal radical nephrectomy for dialysis patients.

No significant financial relationships to disclose.

Initial experience of focal therapy for prostate cancer using I-125 seed implantation: Unilateral ablation for patients selected by extended biopsy and MRI findings

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Background: Focal therapy for prostate cancer could be a minimally invasive therapeutic option with the preservation of genitourinary function to reduce treatment associated complication under the appropriate selection of patients. We have reported the good predict ability to unilateral prostate cancer by extended prostate biopsy combined with transperineal and transrectal approaches (Eur Urol supple, 2009). Among the candidate ablative, brachytherapy which has been proved as a definitive therapy and applied worldwide has been thought to have potential for focal ablation due to its ability of dose and location adjustment by seed implantation under real-time monitoring. Based on the findings, focal therapy with hemiablation using I-125 seed implantation has been started in our instituion. The aim of study is to describe the initial experience of focal therapy for patients selected by extended biopsy and MRI findings.

Methods: The eligible criteria for focal therapy to prostate cancer are as follows. Clinical stage is T2a or less. The positive cores of cancer are proven within unilateral lobe by extended prostate biopsy. There was no cancerous lesion in contralateral lobe by MRI. Gleason score in positive cores was 3 + 4 or less. Maximum cancer length was less than 5 mm. PSA value is less than 10 ng/mL. On the treatment, I-125 seeds were implanted to ablate the unilateral lobe with 160 Gy of the prescription dose. The protocol has been approved by the institutional ethics commit.

Results: At present, 3 patients were enrolled in this study and underwent focal therapy with written informed consents. In all three cases, I-125 seeds implanted (number od seeds: 43, 39, and 37) to unilateral lobe without severe acute complication such as acute urinary retention. In one case that has been followed over 3months among the initial three cases, PSA values decreased to 2.07 mg/ml at 3 months after the seed implantation.

Conclusions: To our knowledge, this is the first report about focal therapy by brachytherapy with hemiablative technique. In our initail experience, severe treatment associated complication has not been observed.

No significant financial relationships to disclose.

[A case of renal tuberculosis following bacillus Calmette-Guerin instillation therapy for bladder cancer]

A rare case of histopathologically revealed renal tuberculosis caused by intravesical bacillus Calmette-Guerin (BCG) therapy is reported. A 67-year-old man was admitted complaining of fever and micturition pain. He had been undergoing prophylactic BCG instillation therapy for recurrent superficial bladder tumor. Physical examination was unremarkable. The tuberculin skin test was negative. Mycobacterium tuberculosis (MT) was not demonstrated by acid-fast staining and culture of urine. However, MT was isolated by the polymerase chain reaction method. In the following 7 days, symptoms were dissolved with administration of isoniazid, rifampicin and piperacillin. Two months later, nephroureterectomy was performed because of left renal pelvic tumor. Tuberculomas were also found in the renal parenchyma which showed no MT by Ziehl-Neelsen's method. Anti-tuberculous medication was not given postoperatively. Two months after operation, he is free of disease with normal urine examination and positive tuberculin skin test measuring 12 x 10 mm.

Biological activities of 1,1,6-trisubstituted indanes: beyond magainin 2

MSI-78 is a peptide analog of naturally occurring magainin 2 isolated from the skin of Xenopus laevis. The peptide is known to have one of the strongest antibacterial activities in magainin 2 analogs against methicillin-resistant Staphylococcus aureus (MRSA). To find novel compounds superior to MSI-78, we have further designed, synthesizing 1,1-di(4-aminobutyl)-6-benzylindane (PM4) and 1,1-dibenzyl-6-(4-aminobutyl) indane (PM5), and tested their inhibitory ability of the growth of S. aureus. In an in vitro assay, PM4 showed the same antibacterial activity against the bacterium as MSI-78, and non-hemolytic activity against human red blood cells (RBCs) at the MIC (minimum inhibitory concentration) value, in contrast to the latter. On the other hand, PM5 showed stronger antibacterial activity than MSI-78, but being still accompanied with hemolysis at the MIC value. Otherwise, stronger decarboxylase activity for oxaloacetate was observed in PM5, rather than magainin 2 analogs or Oxaldie 1 as a control peptide, but not in PM4.

Antibacterial activity of (+/-) 6-benzyl-1-(3-carboxypropyl) indane; a possible way to identify leading novel anti-H. pylori agents

Magainin 2, isolated from the skin of the Xenopus laevis, is an antimicrobial peptide which reacts directly with the biological membrane to lyse various bacteria from negative and positive microorganisms. In a previous report, we showed that (+/-)1-(4-aminobutyl)-6-benzylindane (PM2), which mimicked the conformation of the side-chains of a complementary unit on the amino acid sequence of magainin 2 analogs, expressed the in vitro antibacterial activity not only against Helicobacter, pylori (ATCC43526, ATCC43579), but also against Escherichia coli (ATCC25922) and Staphylococcus aureus (ATCC25923). In addition, PM2 caused human blood red cells (RBCs) to lyse at the minimum inhibitory concentration (MIC) value. Based on the antibacterial activities of 9-phenylnonanoic acid (pC9c), we further synthesized (+/-)-6-benzyl-1-(3-carboxypropyl) indane (PM2c), which replaced a positive charge of PM2 with a negative one, and tested the biological activities. PM2c had the ability to inhibit the growth of H. pylori strains, but its activity to inhibit the growth of E. coli and S. aureus was not detected and weak, respectively. Moreover, PM2c showed non-hemolytic activity against RBCs at the MIC value. These results indicate the possibility that PM2c may be more useful than PM2 either alone or in combination with well-known therapeutic agents for the treatment of H. pylori infection.

On the antibacterial activity of normal and reversed magainin 2 analogs against Helicobacter pylori

Magainin 2 is an antimicrobial peptide isolated from the skin of Xenopus laevis. We have tested the antibacterial activities of normal and reversed magainin 2 analogs against two strains of Helicobacter pylori (ATCC 43526, ATCC 43579), compared with those against Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923). Among these analogs, MSI-78A showed the strongest activity against H. pylori. The MIC (minimum inhibitory concentration) values were almost the same as those against E. coli and S. aureus. No or lesser activity was observed in all the reversed peptides compared to the corresponding normal magainin 2 analogs. Based on the CD (circular dichroism) measurement, the more active peptide tends to show a higher alpha-content. The positively-charged five amino acids (KILKK) positioned at the C terminus on the amphipathical alpha-helical structure play important roles in exerting the strong activity against H. pylori. This indicates that the net charge of the cell surface in H. pylori may be more negative than that of E. coli, though both strains belong to the same genus.

Antibacterial activity of two alkylamines integrated an indane scaffold: mimicry of a complementary unit on magainin 2

Based on the antibacterial activity of 9-phenylnonylamine (pC9a) against Escherichia coli (ATCC29522) and Staphylococcus aureus (ATCC25923), we have further tested the inhibitory ability of the growth of the bacteria by (+/-)1-(4-aminobutyl)-6-benzylindane (PM2) and (+/-)1-benzyl-6-(4-aminobutyl) indane (PM3), that is, two kinds of 1,6-disubstituted indanes. In an in vitro assay, they showed almost the same antibacterial activities against the bacteria as pC9a, as well as that of magainin 2 analogs (i.e., the peptides MSI-78 and 87-ISM), except in the case of 87-ISM against S. aureus. At the MIC (minimum inhibitory concentration) values, however, their killing rate of E. coli is actually quicker than pC9a. This indicates that an indane scaffold, used as a template to mimic a part of the alpha-helical structure of magainin 2, can accelerate the killing rate. At present, however, it is unknown whether either the hydrophobicity or the alpha-helical structure, or both, of the indane scaffold is involved in accelerating the rate. Moreover, these two indanes also showed stronger antibacterial activity against two strains of Helicobacter pylori (ATCC43526, ATCC43579) than either pC9a or magainin 2 related peptides.

Synthesis of reversed magainin 2 analogs enhanced antibacterial activity

Magainin 2 is an antimicrobial peptide found in the skin of Xenopus laevis. To find a reversed peptide comparable to the antibacterial activity of magainin 2 analogs, we have synthesized three reversed analogs, the peptide 53D, 87-ISM and A87-ISM, corresponding to the normal peptide D35, MSI-78 and MSI-78A, respectively. We examined their ability to inhibit the growth of Escherichia coli and Staphylococcus aureus. Among the analogs, the A87-ISM, that is, the reverse of MSI-78A enhanced the amphiphilicity and the alpha-helical tendency of magainin 2, showed not only almost the same antibacterial activity against the bacteria as MSI-78A, but also stronger activity than other magainin 2 analogs. In addition, at the MIC (minimum inhibitory concentration) value, A87-ISM shows no hemolysis to human red blood cells, while both MSI-78 and MSI-78A cause strong hemolysis at the MIC value. This result indicates that a novel reversed peptide comparable or superior to normal magainin 2 analogs is available.

Synthesis and biological activity of four kinds of reversed peptides

We have synthesized four kinds of reversed peptides of various physiologically active peptides, which inhibit TNF (tumor necrosis factor) cytotoxicity, produce NGF (nerve growth factor), exert antimicrobial activity and inhibit cell attachment, respectively. They were examined for their biological activity in comparison with that of normal peptides, that is, naturally occurring peptides. The reversed peptides induce similar activities, but to a lesser extent than those of the normal peptides, respectively. These results indicate that there may be conformationally ambiguous binding in some of the naturally occurring ligand-protein interactions. This method may be useful as a tool to rapidly generate a novel lead peptide with the desired biological function from a naturally occurring active peptide.

Overexpression of Pseudomonas putida catechol 2,3-dioxygenase with high specific activity by genetically engineered Escherichia coli

The cloned xylE gene encoding catechol 2,3-dioxygenase (metapyrocatechase) from TOL plasmid in Pseudomonas putida mt-2 has been expressed in Escherichia coli W3110 to a level of approximately 15% of the total soluble protein. Of the total iron in the crude extract, 45% was on the enzyme. The crystallized enzyme from E. coli had higher iron content (3.7 mol/mol enzyme) and specific activity (536 U/mg) than the enzyme from P. putida mt-2. However, no differences were observed in physicochemical, protein-chemical, and kinetic properties between the two enzymes. The enzyme was a homotetramer, and no changes were observed in the values of M(r) (136,000 +/- 5,000) and Stokes radius (4.26 nm) in the concentration range from 0.36 nM to 2.8 microM, indicating that the native enzyme neither dissociated into subunits nor polymerized in this range. The catalytic center activity and the Km values for catechol and dioxygen were 278 s-1, 1.87 and 7.45 microM, respectively, at pH 7.5 and 25 degrees C. The enzyme showed a broad substrate specificity. Among substrates, 4-methylcatechol and 4-chlorocatechol showed specificity constants (approximately 200 microM-1.s-1) higher than that for catechol. Acetone and phenol derivatives competitively inhibited the activity against catechol. The relationship between specific activity and iron content was not linear, suggesting some conformational changes in the partially iron-depleted enzyme.

Prediction of the active sites of proteins from amino acid sequences

The discriminant analysis of complementary units and repeated sequences of amino acids in an initial sample of 48 different enzymes produces practically useful empirical-functions which allow catalytic sites to be distinguished from non-catalytic sites. The independent variables in the discriminant functions were almost all composed of complementary units of amino acids, that is amino acid sequences whose nucleotide coding sequences were complementary to each other. In order to evaluate the validity of the functions, we applied them to the amino acid sequences of 17 different kinds of enzymes as well as 30 non-enzymes such as receptors, oncoproteins, cytokines, hormones and so on. The functions proved to be effective in predicting not only the catalytic sites of enzymes but also the binding sites of the other proteins. The result suggests that complementary units are evolutionarily conserved as a signal around the active sites of various proteins.

Identification of the binding site of 55kDa tumor necrosis factor receptor by synthetic peptides

We have synthesized a series of peptides, which cover almost the whole range of the N-terminal extracellular domain of human 55kDa TNF receptor (55kDa TNF-R). The peptides were examined for the binding activity to TNF by solid phase binding assay and for the inhibition of TNF cytotoxicity to mouse L-M cells. The peptide 159-178 exhibited remarkably higher binding activity to TNF than other peptides did. The specificity of the TNF binding to the peptides was confirmed by their inability to bind other cytokines. The peptide 159-178 also inhibited TNF cytotoxicity. These results indicate that the specific binding site of 55kDa TNF-R to TNF might reside within the peptide segment of amino acid numbers 159 to 178 in the N-terminal extracellular domain.

Growth inhibition and morphological changes of LLC-PK1 induced by ultimobranchial calcitonins

Ultimobranchial calcitonins (CTs), known to stimulate cAMP production, inhibited the growth of a porcine kidney cell line LLC-PK1. This inhibition was accompanied by degenerative changes including vacuole formation and cell detachment. The electron microscopic study revealed marked swelling of rough endoplasmic reticulum (RER). Other cAMP-increasing agents such as human CT, arginine, vasopressin, and forskolin showed less growth inhibitory activities and no induction of the degenerative changes. These results indicate that the growth inhibition of LLC-PK1 by ultimobranchial CTs is mainly due to cellular death caused by the swelling of RER via a signalling pathway other than the cAMP-dependent event(s).

Characterization of thrombin- and plasmin-resistant mutants of recombinant human single chain urokinase-type plasminogen activator

Recombinant human single-chain urokinase-type plasminogen activator (suc-PA) (SM0: wild type) and its variants resistant to plasmin and/or thrombin (SM1: Lys135 to Gln; SM3: Phe157 to Asp; and SM4: Lys135 to Gln and Phe157 to Asp) have been constructed by site-directed mutagenesis with the aim of producing more efficient thrombolytic agents [Miyake, T. et al. (1988) J. Biochem. 104, 643-647]. In the present study, we characterized the recombinant variant scu-PAs expressed in Escherichia coli. They appeared to have structural integrity because their heat-stabilities, immunological reactivities, and circular dichroism spectra were essentially identical to those of each other and of native scu-PA (nscu-PA). In the presence of thrombin, SM3 and SM4 showed efficient clot lysis by all of the assays used, compared with SM0, SM1, and nscu-PA. While in the absence of thrombin, when measured by a fibrin plate method in a purified system, SM3 and SM4 had lower specific activities than SM0, SM1, and nscu-PA, because of their catalytic constants for conversion to the two-chain form (tcu-PA) by plasmin are lower. However, SM4 lysed clots as efficiently as SM0 in plasma by retaining the single-chain form, whereas SM0 was partly converted to the two-chain form.

Lymphotoxin cDNA clones from a HTLV-I-carrying T cell line HUT-102

The conditioned medium of a HTLV-I-carrying T cell line HUT-102 showed cytotoxic activity against a mouse fibroblast cell line L-M. We prepared the cDNA library from HUT-102 poly(A)+ RNA and screened it using oligonucleotide probes that correspond to the amino acid sequences conserved in tumor necrosis factor (TNF) and lymphotoxin (LT). As a result we obtained two kinds of cDNA clones encoding LT in which amino acid residue 26t of mature LT is different; one is Asn and another is Thr. The sequence of the genomic clones obtained using a polymerase chain reaction method showed that the HUT-102 genome also contains two types of LT genes. Recombinant LTs expressed in Escherichia coli exhibited the same level of cytolytic activity against L-M cells. These results indicate that the cytotoxin constitutively produced by HUT-102 cells include two kinds of LT.

Purification of enzymatically active poliovirus proteinase 3C produced in Escherichia coli

A viral protein 3C of the poliovirus (PV) Sabin 2 strain, a possible core region of the viral proteinase, was expressed in Escherichia coli using a recombinant DNA technology. The protein was recovered as a soluble protein from the insoluble protein fraction of the bacterial lysate, and was purified by a simple procedure with column chromatography. The viral capsid precursor P1 (1ABCD) of the PV Sabin 3 strain, which had been similarly produced in E. coli, was mixed with the purified or crude recombinant 3C. Immunoblotting assay with monoclonal antibodies specific to capsid proteins 1C (VP3) and 1D (VP1) of the PV Sabin 3 strain revealed that the in vitro reaction products contained 1C (VP3), 1D (VP1) and 1ABC (VP0-VP3). The data indicated that processing of the polyprotein P1 by the recombinant 3C proceeded properly in vitro, although an undigested product, 1ABC, is always detected in the reaction mixture. The results strongly suggest that, in addition to a protein 3CD, the 3C protein itself is also catalytically active in the processing of the viral capsid precursor polyprotein P1.

Cloning and nucleotide sequencing of phenylalanine dehydrogenase gene of Bacillus sphaericus

The gene coding for phenylalanine dehydrogenase [PDH; L-phenylalanine: NAD+ oxidoreductase (deaminating); EC 1.4.1.-] from Bacillus sphaericus SCRC-79a was cloned onto plasmid pUC9, and the nucleotide sequence of the 2-kb DNA region of the insert was determined. A 1143-bp open reading frame consisting of 381 codons was identified as a pdh gene coding for PDH.

Production of eicosapentaenoic acid by marine bacteria

About 5,000 strains of marine microorganisms were screened for eicosapentaenoic acid (EPA)-producing ability, which was detected in 88 of them. All of the latter were found to be obligate aerobic, Gram-negative, motile, short rod-shaped bacteria. One strain, designated as SCRC-8132, showed a doubling time of 30 min at 25 degrees C and produced 20 mg/liter (4 mg/g dry cells) when cultured in a P-Y-M-Glucose medium for 18 h. The EPA to total fatty acids ratio was 24%. The strain produced 26 mg EPA/liter (15 mg/g dry cells) when cultured at 4 degrees C for 5 days, the EPA ratio being increased to 40%.

Phenylalanine dehydrogenase of Bacillus badius. Purification, characterization and gene cloning

Phenylalanine dehydrogenase produced by Bacillus badius IAM 11059 was purified from the crude extract of B. badius to homogeneity, as judged by disc gel electrophoresis. The enzyme has an isoelectric point of 3.5 and a relative molecular mass, Mr, of 310,000-360,000. The enzyme is composed of identical subunits with an Mr 41,000-42,000. The substrate specificity of the enzyme in the oxidative deamination reaction was high for L-phenylalanine, but rather low in the reductive amination reaction, with phenylpyruvate, p-hydroxyphenylpyruvate, and 2-oxohexanoate. The gene for the enzyme was cloned into Escherichia coli with plasmid pBR322 as a vector. The enzyme was expressed in high level in E. coli. The enzyme produced by E. coli transformant was purified to homogeneity and shown to be identical to that of B. badius IAM 11,059 with respect to the specific activity, Mr, subunit structure and amino acid composition.

Showdomycin analogues: synthesis and antitumor evaluation

The synthesis of N-beta-D-ribofuranosyl derivatives of maleimide, 3-methylmaleimide, and 3-chloromaleimide was accomplished in three steps from ribosylamine. The synthetic ribosides can be considered N-nucleoside analogues of showdomycin, which is an antitumor antibiotic of the C-nucleoside type. Although the three analogues were cytotoxic to cultured L1210 cells, no in vivo antitumor activity was found with the murine P388 leukemia test system. Drug transport studies were done in an attempt to trace the biological fate of the analogues.