In search of new inhibitors of HIV-1 replication: synthesis and study of 1-(2'-Deoxy-beta-D-Ribofuranosyl)-1,2,4-triazole-3-carboxamide as a selective viral mutagenic agent

With the emergence of HIV strains resistant or cross-resistant to nearly all antiretroviral regimen, novel therapy approaches have to be considered. As a part of our current work on viral mutagenic compounds, we prepared 1-(2' -deoxy-beta-D-ribofuranosyl)-1,2,4-triazole-3-carboxamide (2' -deoxy-ribavirin) and its 5' -triphosphate derivative. The nucleoside mutagenic activity was evaluated on HIV-1 NL4-3 in CEMx174 cell culture. After 2.5 months, no reduction on HIV-1 viability was observed. On the other hand, in vitro experiments with purified HIV-1 RT demonstrated that the triphosphate analog can be incorporated opposite to several natural nucleosides.

Phase I trial of intravenous 17-allylaminogeldanamycin (A) and oral sorafenib (B) in pretreated advanced malignancy: Plasma Hsp90α induction correlates with clinical benefit

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Background: The combination of B with A was evaluated to recommend a phase II dose for using A in combination with B, since raf-kinase and VEGF inhibition by distinct pathways could result in synergy and prevent resistance to B. Patients and Methods: Eligibility included histologically confirmed advanced malignancy, at least 4 weeks since prior systemic cancer therapy and/or radiation, adequate organ function and performance status of 0–2. B was administered orally at fixed dose of 400 mg twice daily starting 2 weeks prior to A, which was added in escalating dose cohorts starting at 300mg/m2 intravenously over 3 hours on days 1, 8 and 15 in a 28 day cycle. Toxicity was assessed weekly and clinical response evaluated every 2 cycles. Results: 19 patients have been registered (6 clear cell renal, 1 papillary renal, 4 colorectal, 1 each with cervix, adrenal, oral, thyroid, pancreas cancer and 3 with melanoma). 16 have been treated for at least the first two cycles at 4 dose levels on this ongoing study. Dose limiting toxicity has not yet been reached at 400mg/m2 of A. Major toxicities were grade 3 fatigue in 1 patient and grade 2 nausea and diarrhea in 3 and 2 patients respectively. Grade 3 hand foot syndrome related to B was noted in 3 patients. Of 14 response evaluable patients, 1 demonstrated partial response (thyroid cancer) and 6 had stable disease;3 clear cell renal,1 each with papillary renal and cervix cancers, and 1 melanoma. Latter patient had stable disease for 10 cycles and was resected to render disease free. PK analysis reveals that steady-state was achieved after 1 week of B; addition of A did not alter PK of B. PK levels of A will be performed. Studies of Hsp90a in the plasma have been performed on 10 patients. Of the 10 patients evaluated for plasma Hsp90a (baseline values pre-A and at 4 and 18 days after A), 5 of the 6 clinically stable patients had 1.8 to 6.8- fold increase; 3 patients with clinical progression and 1 clinically inevaluable patient had induction of 0.8 to 1.7-fold. Conclusion: The combination of A and B is well tolerated and clinical benefit may correlate with induction of plasma Hsp90a. Supported by NIH# 5UO1CA062487- 14, 2MO1RR016500–006 and NCI CTEP.

No significant financial relationships to disclose.

Growth of aligned ZnO nanorods

Growth of high-density and aligned ZnO nanorods on ZnO film substrate has been demonstrated using vapor-transport of thermally evaporated Zn metal powders followed by condensation. Morphological studies show that the nanorods grow preferentially from a hexagonal ZnO base with a uniform hexagonal structure following three-dimensional island-like growth mechanism. Structural and spectroscopic properties clearly indicate that the nanorods are relatively good and defect-free in quality. These nanorods have potential for technological implications.

Surface-enhanced Raman spectroscopy using silver-coated porous glass-ceramic substrates

Surface-enhanced Raman scattering (SERS) has been studied using a silver-coated porous glass-ceramic material as a new type of substrate. The porous glass-ceramic is in the CaO-TiO2-P2O5 system prepared by controlled crystallization and subsequent chemical leaching of the dense glass-ceramic, leaving a solid skeleton with pores ranging in size from 50 nm to submicrometer. Silver was coated on the surface of the porous glass-ceramic by radio frequency (RF) sputtering or e-beam evaporation in vacuum. SERS spectra of excellent quality were obtained from several dyes and carboxylic acid molecules, including rhodamine 6G, crystal violet, isonicotinic acid, and benzoic acid, using this new substrate. This new substrate showed a good compatibility with these molecules. The porous glass ceramic with a nanometer-structured surface accommodated both test molecules and silver film. The absorbed molecules were therefore better interfaced with silver for surface-enhanced Raman scattering.

Bioinformatics integration and agent technology

Vast amounts of life sciences data are scattered around the world in the form of a variety of heterogeneous data sources. The need to be able to co-relate relevant information is fundamental to increase the overall knowledge and understanding of a specific subject. Bioinformaticians aspire to find ways to integrate biological data sources for this purpose and system integration is a very important research topic. The purpose of this paper is to provide an overview of important integration issues that should be considered when designing a bioinformatics integration system. The currently prevailing approach for integration is presented with examples of bioinformatics information systems together with their main characteristics. Here, we introduce agent technology and we argue why it provides an appropriate solution for designing bioinformatics integration systems.

In vivo deamination of cytosine-containing cyclobutane pyrimidine dimers in E. coli: a feasible part of UV-mutagenesis

We have estimated in vivo deamination rates for cytosines in cyclobutane pyrimidine dimers (CPD or PyPy) in UV-irradiated E. coli deficient in uracil DNA glycosylase. The protocol consisted of UV-irradiation, holding in buffer to allow for deamination of cytosines in CPDs and photoreversal (PR) to establish uracils where cytosines in CPD deaminated. The deamination rate at TC photoproducts targeting glutamine tRNA suppressor mutations was estimated from the increase in the mutation frequency after PR (MF(PR)) that developed as UV-irradiated cells were held before PR. Evidence suggested that an earlier study with this protocol under-estimated the deamination rate at sites producing the same mutations in an E. coli B/r strain. With a K12 strain, where the targeting apparently is principally by CPD and not (6-4) photoproducts, a larger rate of k = 0.0091 min(-1) at 42 degrees C resulted. The dark assay for MF also increased significantly with time for deamination consistent with a model for efficient mutation by translesion synthesis at uracil-containing CPD. In addition, we used a strain constructed by Cupples and Miller in which beta-galactosidase was inactive because -GGG- was at codon 461 and would revert to Lac(+) only when replaced by -GAG- or -GAA- for glutamate. CC photoproducts at this target site in the opposite DNA strand could reveal effects of first and second deaminations in the same CPD. MF(PR) for Lac(+) mutations increased and then decreased as a function of deamination time (at six temperatures 36-48 degrees C). Fitting an approximate model equation that distinguished two different deamination rates to these data suggested a first deamination producing Lac(+) at a rate about eight-fold less than a second deamination restoring the Lac(-) phenotype. We conclude that deamination, changing a cytosine-containing CPD to a uracil-containing CPD, could be an integral part of UV-induced C-to-T mutations.

Efficacy and safety of inhaled recombinant interleukin-2 in high-risk renal cell cancer patients compared with systemic interleukin-2: an outcome study

Systemic IL-2 is an effective treatment for low to intermediate risk mRCC patients, its efficacy is marginal in high-risk cases. Therefore, other treatment approaches are required for this population. Ninety-four high-risk patients with RCC and pulmonary metastases were treated with inhaled plus concomitant low-dose subcutaneous rhIL-2. Clinical response, survival and safety were compared with those from IL-2 given systemically at the registered dose and schedule in 103 comparable historical controls. In the rhIL-2 INH group, treatment consisted of 6.5 MIU rhIL-2 nebulized 5x/day and 3.3 MIU rhIL-2 SC once daily. The rhIL-2 SYS group received treatment which consisted of intravenous infusion of 18.0 MIU/m2/day rhIL-2 or SC injection of 3.6-18.0 MIU rhIL-2. Some patients in both groups also received IFNalpha. Mean treatment durations were 43 weeks rhIL-2 INH and 15 weeks rhIL-2 SYS. Significantly longer overall survival and progression-free survival durations were observed in the rhIL-2 INH group. The probability of survival at 5 years was 21% for the rhIL-2 INH group. No patients survived 5 years in the rhIL-2 SYS group. A multivariate analysis of overall survival adjusting for differences in baseline characteristics between the two treatment groups resulted in a risk ratio of 0.43 (95% CI 0.30-0.63; P < 0.0001). The data suggested an association between the response (SD or better) and survival, especially in the rhIL-2 INH group. The inhalation regimen was well tolerated. This outcome study suggests that administration of rhIL-2 by inhalation is efficacious and safe in high-risk mRCC patients with pulmonary metastases, who have no other treatment option available.

DNA damage-processing in E. coli: on-going protein synthesis is required for fixation of UV-induced lethality and mutation

UV irradiation of E. coli produces photoproducts in the DNA genome. In consequence, some bacteria lose viability (colony-forming ability) or remain viable as mutant cells. However, the end-points of viability inactivation (lethality) or mutation are determined by cellular processes that act on the UV-damaged DNA. We have investigated the in vivo time course for processes that deal with cyclobutane pyrimidine dimers (CPD) which can be specifically removed by photoreactivation (PR). At different times during post-UV incubation, samples were challenged with PR and assayed for viability or mutation. We used excision-defective E. coli B/r cells and worked under yellow light to avoid background PR. During post-UV incubation (0-100min) in fully supplemented defined medium, inactivation and mutation were initially significantly reversed by PR but the extent of this reversal decreased during continued incubation defining "fixation" of lethality or mutation, respectively. In contrast, if protein synthesis was restricted during the post-UV incubation, no fixation developed. When chloramphenicol was added to inhibit protein synthesis after 30min of supplemented post-UV incubation, at a time sufficient for expression of UV-induced protein(s), fixation of lethality or mutation was still annulled (no change in the effectiveness of PR developed). Lethality fixation did progress when protein synthesis was restricted and the cells were incubated in the presence of puromycin or were either clpP or clpX defective. We discuss these and related results to suggest (1) on-going protein synthesis is required in the fixation process for lethality and mutation to sustain an effective level of a hypothetical protein sensitive to ClpXP proteolysis and (2) this protein plays a critical role in the process leading to exchange between Pol III activity and alternative polymerase activities required as each cell deals with damage in template DNA.

Widespread distribution of a single drug rifampicin formulation of inferior bioavailability in South Africa

A pharmacokinetic study of rifampicin, isoniazid, pyrazinamide and ethambutol in 118 tuberculosis patients revealed low and variable concentrations of rifampicin after 2 months of treatment on standard daily doses. A group of 53 patients exposed to specific batches of formulations containing rifampicin alone showed particularly low and variable levels of the drug. The national drug regulatory authority subsequently withdrew the batches in question, as sufficient bioavailability data had not been submitted after what the manufacturer had considered to be a minor formulation change. The evidence supports initiatives to implement bioavailability testing of new formulations (and of established formulations subsequent to changes in the manufacturing process) prior to distribution. Concerns about the bioavailability of rifampicin-containing products, including those with adequate dissolution profiles, should not be confined to fixed-dose combination anti-tuberculosis drugs, but should also be applied to single drug formulations.

[Thyroid cancers: the Geneva experience]

AIM OF THE STUDY

To study the survival of patients with thyroid cancer operated in the same centre from 1978 to 1999.

PATIENTS AND METHOD

This retrospective study included 218 patients operated on for thyroid carcinoma from january 1978 to december 1999. Modified neck dissection was performed only in the presence of one or more suspected lymph nodes. The stage of the cancer was defined according to the last TNM classification (1997). Survival data were taken from the Geneva Tumour Registry (168 patients = 77% of the series, 109 papillary carcinomas, 37 follicular, 14 undifferentiated and 8 medullary carcinomas).

RESULTS

The overall 5, 10 and 15-year survival rates were respectively 88%, 84% and 80%. Papillary carcinoma was associated with the best survival at 5, 10 and 15 years (99%, 97% and 93%), despite a recurrence rate of 20% treated mainly by surgery often associated with radioiodine therapy. Follicular carcinoma had a survival rate of 83% at 5 years and 75% at 10 years. Undifferentiated carcinoma had a median survival rate of 56 days. None of the 8 patients with medullary carcinoma had died from that cancer in this series.

CONCLUSION

Thyroid carcinoma carries such a good prognosis (except for undifferentiated carcinoma) that invasive surgery at first operation, like radical neck dissection, is not justified, despite a high rate of recurrence.

A highly efficient transposon mutagenesis system for the tomato pathogen Clavibacter michiganensis subsp. michiganensis

A transposon mutagenesis system for Clavibacter michiganensis subsp. michiganensis was developed based on antibiotic resistance transposons that were derived from the insertion element IS1409 from Arthrobacter sp. strain TM1 NCIB12013. As a prerequisite, the electroporation efficiency was optimized by using unmethylated DNA and treatment of the cells with glycine such that about 5 x 10(6) transformants per microg of DNA were generally obtained. Electroporation of C. michiganensis subsp. michiganensis with a suicide vector carrying transposon Tn1409C resulted in approximately 1 x 10(3) transposon mutants per pg of DNA and thus is suitable for saturation mutagenesis. Analysis of Tn1409C insertion sites suggests a random mode of transposition. Transposition of Tn1409C was also demonstrated for other subspecies of C. michiganensis.

Preparation of 1-(3-C-(propa-1,2-dienyl)-D-ribo-pentofuranosyl)uracil, an allenic nucleoside

The Crabbé reaction was extended to the preparation of C-3'-allenyl-uridine. The effects of solvent and protecting group on the reaction were studied. The conversion in refluxing dioxan of disilyl either 3 proceeds to the corresponding allenic nucleoside 7; whereas, in refluxing THF the Mannich base 5 was obtained. Fully deprotected Mannich base and allenic uridines 6 and 9 were tested for their antitumor activity.

Polymorphism of racemic felodipine and the unusual series of solid solutions in the binary system of its enantiomers

The aim of this study was to investigate the binary phase diagram and the polymorphism and pseudopolymorphism of racemic and enantiomeric felodipine, including their spectroscopic and thermodynamic properties. Different crystal forms were obtained by crystallization from solvents or from the annealed melt and investigated by thermal analysis (hot stage microscopy, differential scanning calorimetry, thermogravimetric analysis), spectroscopic methods (Fourier transform infrared-and Fourier transform-Raman spectroscopy), and X-ray powder diffractometry. The binary melting phase diagram was constructed based on thermoanalytical investigations of quantitative mixtures of (+)- and (+/-)-felodipine. Two polymorphic forms of racemic felodipine, mod. I (mp, approximately 145 degrees C) and mod. II (mp, approximately 135 degrees C), as well as an acetone solvate (S(Ac )) were characterized. Melting equilibria of felodipine crystal forms decrease due to thermal decomposition. Enantiomeric felodipine was found to be dimorphic (En-mod. I: mp, approximately 144 degrees C; En-mod. II: mp, approximately 133 degrees C). Evaluation of the binary system of (+)- and (-)-felodipine results in the formation of a continuous series of mixed crystals between the thermodynamically stable and higher melting modifications, mod. I and En-mod. I. Their unusual curve course, termed as Roozeboom Type 2 b, passes through a maximum in the racemic mixture and is flanked by a minimum at 20% and at 80% (+)-felodipine. From the thermodynamic parameters, racemic mod. I and II are monotropically related. In contrast to S(Ac), the thermodynamically unstable mod. II shows a considerable kinetic stability. Because its crystallization is badly reproducible, the use of mod. II is not advisable for processing. However, desolvation of S(Ac) leads to a profitable crystal shape of mod. I, representing a pseudoracemate by definition.

Short- and long-term results of total vs subtotal thyroidectomies in the surgical treatment of Graves' disease

OBJECTIVE

Approximately one out of five patients with Graves' disease (GD) undergoes a thyroidectomy after a mean period of 18 months of medical treatment. This retrospective and non-randomized study from a teaching hospital compares short- and long-term results of total (TT) and subtotal thyroidectomies (ST) for this disease.

METHODS

From 1987 to 1997, 94 patients were operated for GD. Thirty-three patients underwent a TT (mostly since 1993) and 61 a ST (keeping 4 to 8 grams of thyroid tissue--mean 6 g). All patients had received propylthiouracil and/or neo-mercazole and were in a euthyroid state at the time of surgery; they also took potassium iodide (lugol) for ten days before surgery.

RESULTS

There were no deaths. Transient hypocalcemia (< 3 months) occurred in 32 patients (15 TT and 17 ST) and persistent hypocalcemia in 8 having had TT. Two patients developed transient recurrent laryngeal nerve palsy after ST (< 3 months). After a median follow-up period of seven years (1-15) with five patients lost to follow-up, 41 patients having had a ST are in a hypothyroid state (73%), thirteen are euthyroid (23%), and two suffered recurrent hyperthyroidism, requiring completion of thyroidectomy. All 33 patients having had TT--with follow-ups averaging two years (0.5-8)--are receiving thyroxin substitution.

CONCLUSIONS

There were no instances of persistent recurrent laryngeal nerve palsy in either group, but persistent hypoparathyroidism occurred more frequently after TT. Long after ST, hypothyroidism developed in nearly three of four cases, whereas euthyroidy was maintained in only one-fourth; recurrent hyperthyroidy was rare.

Di-tert-butyl diethylphosphoramidite as the phosphitylating reagent in the preparation of 3-deoxy-3-C-methylene-D-ribo-hexose-6-phosphate and 3-deoxy-3-C-methylene-D-erythro-pentose-5-phosphate

3-Deoxy-3-C-methylene-D-ribo-hexose-6-phosphate and 3-deoxy-3-C-methylene-D-erythro-pentose-5-phosphate were prepared from a common intermediate 3-deoxy-3-C-methylene-1,2-O-isopropylidene-alpha-D-ribo-hexofuranose. The preparation of the phosphorylated unsaturated sugars employed di-tert-butyl diethylphosphoramidite as the phosphitylating reagent. The removal of all the protecting groups was done under acidic conditions in the ultimate step. The unsaturated sugar phosphates were competitive inhibitors but neither substrates nor inactivators of glucose-6-phosphate and ribose-5-phosphate isomerases.