Folate status among patients with non-small cell lung cancer: a case-control study

BACKGROUND AND OBJECTIVES

This case control study explored the purported inverse relationship between folate status and lung cancer development.

METHODS

Folate status of 46 postoperative non-small cell lung cancer (NSCLC) patients was compared to that of 44 non-cancer patients. Cancer patients had completed treatment > 3 months prior and had no evidence of cancer. Ineligibility criteria for all patients included (1) > 2 alcoholic drinks/day (2) ongoing tobacco use, or (3) folate supplementation > 400 microg/day.

RESULTS

No differences were found between groups in serum and RBC folate after adjustment for age and use of folate-interfering medications: geometric means (GM) x /geometric standard error (GSE): 7.9 ng/ml x /1.1 vs. 7.8 ng/ml x /1.1, respectively (P = 0.91) for serum folate; 264 ng/ml x /1.1 vs. 263 ng/ml x /1.1, respectively (P = 0.97) for RBC folate. Age- and creatinine-adjusted homocysteine was no different between groups: GM x /GSE: 9.4 micromol/L x /1.0 vs. 8.6 micromol/L x /1.0, respectively (P = 0.17). No difference were seen in folate intake. Frequencies of the homozygous genotype for the MTHFR polymorphism, an enzyme important in folate metabolism and associated with a reduced risk of other cancers, were no different.

CONCLUSIONS

This case control study does not support the hypothesis that low folate is an independent risk factor for NSCLC.

Local intratumoral tumor necrosis factor-alpha and systemic IFN-alpha 2b in patients with locally advanced prostate cancer

To examine tolerability and activity of local, intratumoral tumor necrosis factor-alpha (TNF-alpha) and systemic interferon-alpha2b (IFN-alpha2b) in locally advanced, hormone-resistant prostate cancer (LA-HRPC), 10 patients with LA-HRPC (T4N x M0, n = 3, T4N x M1, n = 5; T4N1M1, n = 2) were treated with recombinant TNF-alpha injected locally into prostate tumor tissue at 4-week intervals (maximum of four cycles) combined with intermittent subcutaneous (s.c.) administration of 5 x 10(6) IU IFN-alpha2b. Twenty-nine TNF-alpha cycles were administered. Despite significant TNF-alpha leakage into the systemic circulation 2 h after intraprostatic application (from a mean of 9 to a mean of 416 pg/ml; p = 0.0034), TNF-alpha (and IFN-alpha2b) was well tolerated (WHO grade 1-2 toxicity), possibly because of its rapid neutralization by increasing soluble 55-kDa and 75-kDa TNF receptor levels in the serum (mean increase 268% and 91%, respectively) at the same time. TNF-alpha induced prostate tumor cell necrosis in all patients, leading to a significant reduction of prostate volume in 9 of 10 cases (mean 38%; p = 0.0025). The significant short-term increase of prostate-specific antigen (PSA) (mean 65%; p < 0.001), tissue polypeptide-specific antigen (TPS) (mean 85%; p = 0.001), and possibly interleukin-8 (IL-8) (mean 2687%; p < 0.009) serum levels within 4 h after TNF-alpha confirmed the cytotoxic effect in vivo. In the long term, serum PSA levels dropped by 18%-87%, reaching the nadir value 7 weeks after baseline. Objective responses of metastases were not seen. Intraprostatic administration of TNF-alpha is feasible at a tolerable toxicity in patients with LA-HRPC and, thus, may be a new treatment option for these patients.

Cotranslational folding--omnia mea mecum porto?

Evidence for cotranslational folding on both prokaryotic and eukaryotic ribosomes is reviewed. Molecular chaperones appear to assist only a small fraction of newly synthesized proteins in folding into their native conformation. The recently published crystal structure of the large ribosomal subunit at 2.5 A resolution has provided the basis for understanding where and how peptide synthesis takes place on the ribosome. The nascent peptide is concluded to pass through a tunnel that extends about 100 A between the peptidyl transferase center and its exit site. The minimum diameter of the tunnel and the apparent physical and chemical properties of its walls appear to preclude complex folding of the nascent peptide within most of the length of the tunnel. However, results indicate that nascent peptides that are protected within the ribosomes vary in length from about 30 to 72 amino acid residues. This suggests that nascent peptides have different conformations. It is hypothesized that folding of the nascent polypeptide into its native conformation starts in the distal portion of the tunnel, and proceeds at the surface of the ribosomal subunit in a depression or bay near the exit opening of the tunnel.

Sequential administration of interferon-gamma, GM-CSF, and interleukin-2 in patients with metastatic renal cell carcinoma: results of a phase II trial

Various cytokine combinations have been tested for efficacy in the treatment of metastatic renal cell carcinoma (MRCC). Because several immunologic synergisms between granulocyte-macrophage colony-stimulating-factor (GM-CSF) and interleukin-2 (IL-2) have been demonstrated, this phase II trial was conducted on the efficacy and toxicity of subcutaneous, sequentially administered, interferon-gamma (IFNgamma), GM-CSF, and IL-2. Fifty-five consecutive patients with MRCC were treated with 100 microg recombinant IFNgamma1b administered thrice weekly during weeks 1 and 4, followed by 400 microg GM-CSF on 5 consecutive days during weeks 2 and 5. In weeks 3 and 6, patients received 4.5 MU recombinant IL-2 from days 1 to 4. The treatment was repeated every 8 weeks. Five (10%) of patients experienced an objective response (complete response [CR]: 2%, partial response [PR]: 8%). Fourteen (26%) patients had stable disease with a median duration of 19 months (6-47+). The median overall survival was 12 months (range: 0.3-44 months). No toxicity greater than World Health Organization grade II was observed, with fever (43%) and erythema (43%) being the most frequent side effects. Compared with other phase II trials with IFN-gamma and IL-2 alone, the addition of GM-CSF failed to improve response or survival in patients with MRCC.

High-grade prostate cancer is associated with low serum testosterone levels

BACKGROUND

The aim of this study was to assess whether low serum testosterone levels in men with newly diagnosed prostate cancer have an association to the endocrine status, prostate-specific antigen (PSA) levels, Gleason score, and androgen receptor expression.

METHODS

Besides a full clinical work-up, the following hormones were quantified in men with newly diagnosed prostate cancer by serum analysis: total testosterone, human luteinising hormone (hLH), human follicle stimulating hormone (hFSH), estradiol, and dehydroepiandrostendione (DHEA). In a subgroup of men, androgen receptor expression was determined immunohistochemically.

RESULTS

One hundred and fifty six patients (65.7 +/- 8.5 yrs) with a mean PSA of 29.8 ng/ml (median: 7.4 ng/ml) were analysed. Fifty-two patients (33%) had a partial androgen deficiency (serum testosterone < 3.0 ng/ml). These men had lower hLH (3.3 vs. 5.9 mIU/ml), hFSH (6.2 vs. 8.4 mIU/ml), and estradiol (18.8 vs. 29.1 pg/ml) serum levels. Mean Gleason score was higher (7.4 vs. 6.2) in men with a low serum testosterone, PSA-levels were lower (25.3 vs. 31.9 ng/ml). Mean testosterone levels decreased from 4.1 +/- 1.7 ng/ml in patients with Gleason scores < or = 5 to 2.8 +/- 2.7 ng/ml with Gleason scores > or = 8. Androgen receptor expression was higher in patients with low serum testosterone.

CONCLUSIONS

Patients with high Gleason score prostate cancer have lower testosterone and estradiol serum levels. The fact that gonadotropins were lower in parallel suggests a tumor-mediated suppression of the hypothalamic-pituitary-gonadal hormone axis particularly in men with high Gleason score tumours.

Folding of a nascent peptide on the ribosome

Even though very significant progress has been made recently in elucidating the structure of the bacterial ribosome and topological assignments of its functional parts, the molecular mechanism of how a peptide is formed and how the nascent peptides is folded on the ribosomes remains uncertain. Here, the current progress and remaining problems are considered from the standpoint of the authors. Topics considered include formation of peptide bonds and models that represent this process, the vicinity of RNA to the nascent peptide, the cotranslational folding hypothesis, evidence that some but not all nascent peptides pass through a region within the 50S ribosomal subunit, presumably the tunnel, in which they are folded and sheltered, pause-site peptides, and the involvement of chaperones in folding of nascent proteins on ribosomes. The chaperone-like activity of the large ribosomal subunit in renaturation of denatured proteins is reviewed. It is concluded that cotranslational folding of some but not all nascent peptides occurs in the large ribosomal subunit. It is suggested that this folding is facilitated by changes in the conformation of the ribosome that are related to the reaction cycle of peptide elongation.

An Additional Serine Residue at the C Terminus of Rhodanese Destabilizes the Enzyme

The rhodanese coding sequence was extended at its 3' end by three base pairs to generate mutants coding for a serine or arginine residue at the carboxyl terminus of the protein. Wild-type and mutant coding sequences were expressed in a cell-free Escherichia coli system by coupled transcription/translation. Predominantly full-length protein was formed in all cases. The amount of protein synthesized was quantified by incorporation of radioactive leucine into polypeptides. Enzymatic activity of in vitro synthesized rhodanese was determined at different temperatures. Specific enzymatic activity was calculated and is assumed to reflect the portion of the protein that is in its native three-dimensional conformation. It was observed that rhodanese extended by one serine at the C terminus lost enzymatic activity when incubated above 30 degrees C, in contrast to wild-type protein or variant rhodanese extended by an arginine residue. Similarly, variant rhodanese with an additional serine residue was more susceptible to urea denaturation than the other two rhodanese species. These results are surprising in light of the crystal structure of the protein.

Strong coupling constant from scaling violations in fragmentation functions

We present a new determination of the strong coupling constant alpha(s) through the scaling violations in the fragmentation functions for charged pions, charged kaons, and protons. In our fit we include the latest e+e- annihilation data from CERN LEP1 and SLAC SLC on the Z-boson resonance and older, yet very precise, data from SLAC PEP at center-of-mass energy sqaure root of s = 29 GeV. At next-to-leading order, we find alpha(s)(5)(M(Z)) = 0.1170+/-0.0073. A new world average of alpha(s) is given.

Feasibility study prior to the certification of trace elements in urban and industrial wastewater reference materials

Reliable results for the determination of trace elements in urban and industrial wastewaters are of paramount importance for both checking the performance of sewage treatment and for detecting possible urban or industrial contamination sources. The quality control of measurements should in principle rely on external tools such as certified reference materials (CRM), which should represent, as closely as possible, the matrix of samples currently analysed, e.g., in the frame of environmental monitoring. To date, however, no CRM representatives of wastewater composition are available, which limits the possibility for control laboratories to check their QC externally. To fill this gap, the European Commission's Standards, Measurements and Testing Programme (formerly BCR) has started a European collaborative project of which the aim is to test the feasibility of preparation of wastewater reference materials and the analytical state-of-the-art to enable the certification of trace elements in such matrices. This paper presents the results of the first phase of this project, namely the feasibility study and the results of an interlaboratory trial.

Expression of different coding sequences in cell-free bacterial and eukaryotic systems indicates translational pausing on Escherichia coli ribosomes

Five different coding sequences of bacterial or eukaryotic origin in plasmids under the T7 promoter were expressed in a cell-free system derived from Escherichia coli. Translation on E. coli ribosomes resulted in a full-length product only in four of the five coding sequences tested. A unique pattern of less than full-length polypeptides was generated in each case. Many of these polypeptides on E. coli ribosomes reacted with a puromycin derivative, cytidylic acid-puromycin, which was radioactively labeled. Thus these incomplete polypeptides can be defined as nascent peptides bound to the ribosomal P site. Certain nascent peptides could be shifted into full-length protein indicating that they resulted from translational pausing. In contrast to these results, expression of the same coding sequences in a wheat germ or reticulocyte cell-free system resulted in a 80-90% full-length product with no evidence for nascent polypeptides and translational pausing.

The impact of health status on waiting time for major joint arthroplasty

This study was conducted to determine the impact of health status on waiting time for major joint arthroplasty in a universal publicly funded health system. Data were collected prospectively from a cohort of 553 patients waiting for total hip or total knee arthroplasty. The WOMAC and SF-36 health status instruments were administered at the time the patient was placed on the waiting list. The outcome measure was length of waiting time. Multivariate analyses found increased body mass index and decreased social function as the only determinants of waiting time. This model explained only 4% of the variance in waiting time. The association between health status and waiting time for arthroplasties appears to be small. These findings suggest that major joint arthroplasty is not prioritized on the basis of burden of illness.

Botulinum-A toxin for treating detrusor hyperreflexia in spinal cord injured patients: a new alternative to anticholinergic drugs? Preliminary results

PURPOSE

We evaluated the efficacy of botulinum-A toxin injections into the detrusor muscle in patients with spinal cord injury, detrusor hyperreflexia and urge incontinence resistant to anticholinergic drugs. The purpose of treatment was to suppress incontinence episodes and increase functional bladder capacity.

MATERIALS AND METHODS

Included in our prospective nonrandomized study done at 2 clinics were 31 patients with traumatic spinal cord injury who emptied the bladder by intermittent self-catheterization. These patients had severe detrusor hyperreflexia and incontinence despite a high dose of anticholinergic medication. Pretreatment evaluation included a clinical examination and complete urodynamic investigation. Under cystoscopic control a total of 200 to 300 units of botulinum-A toxin were injected into the detrusor muscle at 20 to 30 sites (10 units per ml. per site), sparing the trigone. Clinical and urodynamic followup was planned for 6, 16 and 36 weeks after treatment. Patients were asked to decrease their intake of anticholinergic drugs during week 1 after treatment.

RESULTS

Of the 21 patients 19 underwent a complete examination 6 weeks after the botulinum-A toxin injections, and 11 at 16 and 36 weeks. At the 6-week followup complete continence was restored in 17 of 19 cases in which anticholinergic medication was markedly decreased or withdrawn. Less satisfactory results in 2 cases were associated with an insufficient dose of 200 units botulinum-A toxin. After the injections overall mean reflex volume and mean maximum cystometric bladder capacity plus or minus standard deviation significantly increased from 215.8 +/- 90.4 ml. to 415.7 +/- 211.1 (p <0.016) and 296.3 +/- 145.2 to 480.5 +/- 134.1 (p <0.016), respectively. There was also a significant decrease after treatment in mean maximum detrusor voiding pressure from 65.6 +/- 29.2 cm. water to 35 +/- 32. 1 (p <0.016). Mean post-void residual urine volume catheterized at the end of the urodynamic examination increased significantly from a mean of 261.8 +/- 241.3 ml. to 490.5 +/- 204.8 (p <0.016). Moreover, autonomic dysreflexia associated with bladder emptying that manifested as a hypertensive crisis during voiding disappeared after treatment in the 3 patients with tetraplegia. Satisfaction was high in all successfully treated patients and no side effects were observed. Ongoing improvement in urodynamic parameters and incontinence was already present in all patients reevaluated at 16 and 36 weeks.

CONCLUSIONS

Botulinum-A toxin injections into the detrusor seem to be a safe and valuable therapeutic option in spinal cord injured patients with incontinence resistant to anticholinergic medication who perform clean intermittent self-catheterization. Successfully treated patients become continent again and may withdraw from or markedly decrease anticholinergic drug intake. A dose of 300 units botulinum-A toxin seems to be needed to counteract an overactive detrusor. The duration of bladder paresis induced by the toxin is at least 9 months, when repeat injections are required.

Botulinum-A toxin for treating detrusor hyperreflexia in spinal cord injured patients: a new alternative to anticholinergic drugs? Preliminary results

PURPOSE

We evaluated the efficacy of botulinum-A toxin injections into the detrusor muscle in patients with spinal cord injury, detrusor hyperreflexia and urge incontinence resistant to anticholinergic drugs. The purpose of treatment was to suppress incontinence episodes and increase functional bladder capacity.

MATERIALS AND METHODS

Included in our prospective nonrandomized study done at 2 clinics were 31 patients with traumatic spinal cord injury who emptied the bladder by intermittent self-catheterization. These patients had severe detrusor hyperreflexia and incontinence despite a high dose of anticholinergic medication. Pretreatment evaluation included a clinical examination and complete urodynamic investigation. Under cystoscopic control a total of 200 to 300 units of botulinum-A toxin were injected into the detrusor muscle at 20 to 30 sites (10 units per ml. per site), sparing the trigone. Clinical and urodynamic followup was planned for 6, 16 and 36 weeks after treatment. Patients were asked to decrease their intake of anticholinergic drugs during week 1 after treatment.

RESULTS

Of the 21 patients 19 underwent a complete examination 6 weeks after the botulinum-A toxin injections, and 11 at 16 and 36 weeks. At the 6-week followup complete continence was restored in 17 of 19 cases in which anticholinergic medication was markedly decreased or withdrawn. Less satisfactory results in 2 cases were associated with an insufficient dose of 200 units botulinum-A toxin. After the injections overall mean reflex volume and mean maximum cystometric bladder capacity plus or minus standard deviation significantly increased from 215.8 +/- 90.4 ml. to 415.7 +/- 211.1 (p <0.016) and 296.3 +/- 145.2 to 480.5 +/- 134.1 (p <0.016), respectively. There was also a significant decrease after treatment in mean maximum detrusor voiding pressure from 65.6 +/- 29.2 cm. water to 35 +/- 32. 1 (p <0.016). Mean post-void residual urine volume catheterized at the end of the urodynamic examination increased significantly from a mean of 261.8 +/- 241.3 ml. to 490.5 +/- 204.8 (p <0.016). Moreover, autonomic dysreflexia associated with bladder emptying that manifested as a hypertensive crisis during voiding disappeared after treatment in the 3 patients with tetraplegia. Satisfaction was high in all successfully treated patients and no side effects were observed. Ongoing improvement in urodynamic parameters and incontinence was already present in all patients reevaluated at 16 and 36 weeks.

CONCLUSIONS

Botulinum-A toxin injections into the detrusor seem to be a safe and valuable therapeutic option in spinal cord injured patients with incontinence resistant to anticholinergic medication who perform clean intermittent self-catheterization. Successfully treated patients become continent again and may withdraw from or markedly decrease anticholinergic drug intake. A dose of 300 units botulinum-A toxin seems to be needed to counteract an overactive detrusor. The duration of bladder paresis induced by the toxin is at least 9 months, when repeat injections are required.

Is one set of sextant biopsies enough to rule out prostate Cancer? Influence of transition and total prostate volumes on prostate cancer yield

PURPOSE

Although the sextant biopsy technique has been widely used, concern has arisen that this method may not include an adequate sampling of the prostate, especially for large prostate volumes. We conducted a multicenter study in patients with PSA levels <10 ng/ml to determine the influence of the total and transition zone (TZ) volumes of the prostate for predicting whether one single set of biopsies was sufficient to rule out prostate cancer (PCa). These parameters were evaluated in patients in whom PCa was found after one set of systematic sextant biopsies and those in whom PCa was found after a repeat biopsy.

MATERIALS AND METHODS

A total of 1,018 patients were included in this study. All underwent transrectal ultrasound-guided needle sextant and two TZ biopsies of the prostate. Total and TZ volumes of the prostate were measured (prolate ellipsoid method). From this cohort, all patients in whom a benign disease was found after the first set of biopsies underwent a second similar set of biopsies within 6 weeks. Only patients with PCa were included in this study, whether diagnosed on first or repeat biopsy. Uni- and multivariate statistical analysis using the SAS system (Cary, N.C., USA) and ROC curves were used to compare patients in whom the diagnosis was performed after the first set of biopsies and those who required a second set.

RESULTS

Of the 1,018 patients, 344 (33.8%) had PCa diagnosed, 285 (28%) after the first set of biopsies, and 59 (8.1%) on repeat biopsy. As compared to patients diagnosed with PCa after the first set of biopsies, patients diagnosed after the second set had larger total prostate and TZ volumes (43.1+/-13.0 vs. 32.5+/-10.6 cm(3), p<0.0001 and 20.5+/-8.3 vs. 12.8+/-6.0 cm(3), p<0.0001). ROC curves showed that total and TZ volumes of 45 and 22. 5 cm(3), respectively, provided the best combination of sensitivity and specificity for discriminating between patients diagnosed with PCa after the first from those diagnosed after a second set.

CONCLUSION

In patients with total prostate volume >45 cm(3) and TZ >22.5 cm(3), a single set of sextant biopsies may not be sufficient to rule out PCa. In these patients, a repeat biopsy should be considered in case of a negative first biopsy.

Automated data acquisition by confocal laser scanning microscopy and image analysis of triple stained immunofluorescent leukocytes in tissue

The aim of the study was to develop a novel system permitting automated analysis of multicolor immunofluorescence-staining of cells in solid tissues which would be comparable to the analytical capacity of flow cytometry. In the user friendly automated data acquisition and image processing system which was established, the software includes a set of pre-defined processing steps for improved object identification and can be either interactive or fully automatic. As with multi color flow cytometry, stained cells can be analyzed in a fully automated manner regardless of tissue type. The software organizes computerized sample movement, autofocus, laser readjustment, data capture and storage as well as calculation. Data are presented as histograms indicating the staining intensity and frequency of each antigen, and in dotplots with each channel plotted against the other. The calculated statistics give information about how many of the cells are single-, double- or triple-reactive and how intensely they react with the respective antibodies. Comparison of data generated by this automated fluorescence confocal laser scanning microscopy (AF-CLSM) with flow cytometry using triple stained peripheral blood lymphocytes revealed a highly significant correlation between the methods (P<0.001). A correlation was also observed when sections triple stained for anti-CD45, -CD3 and -CD8 were analyzed by AF-CLSM and the data were compared to visual/manual cell counting (P<0.01). The AF-CLSM system permits for the first time, fast (online) and reproducible analysis of immunofluorescence staining of an unlimited number of cells in tissue sections. The software, including a manual, is available for a small fee to cover the costs of printing and postage.

Long term survival of a patient with malignant pleural mesothelioma as a late complication of radiotherapy for Hodgkin's disease treated with 90yttrium-silicate

A case of malignant pleural mesothelioma (PM) 24 years after thoracic radiotherapy for Hodgkin's disease is presented. As primary treatment and to relieve symptoms of dyspnea secondary to pleural effusion a thoracic drain was installed, followed by intracavitary radiation therapy with 90yttrium-silicate. Minor complaints of fever and a dry cough as a side-effect of this treatment were effectively treated with prednisone during 2 weeks. The patient remains in a good clinical condition now 6 years after diagnosis. Considering the few therapeutic options the use of 90yttrium-silicate intrapleural installation could be propagated as a safe and effective antitumour treatment for a selected group of patients with malignant PM.

Vinorelbine and interferon-alpha2c as second-line therapy in metastatic renal cell carcinoma

Second-line treatment of patients with metastatic renal cell carcinoma (MRCC) progressing under therapy with biological response modifiers (BRM) is an unresolved issue. Thirty-seven patients with MRCC progressing under treatment with BRM received vinorelbine i.v. at a dose of 30 mg/m2 q 22 days and 4,800,000 IU interferon (IFN)-alpha2c s.c. thrice weekly. Partial remission (PR) occurred in 8% of patients, stable disease (SD) (median duration 8, range 3-35+ months) was observed in 46% of patients. Median overall survival was 15 (range 1-49) months. No major toxicities occurred. Patients with MRCC who failed first-line treatment with BRM had a high chance to enter PR or SD under combined, low-toxic therapy with vinorelbine and IFN-alpha2c.

Initiation of protein synthesis with fluorophore-Met-tRNA(f) and the involvement of IF-2

The complicity of initiation factor 2 (IF-2) in causing the observed low incorporation of N-terminal fluorophore from fluorophore-methionyl-tRNA(f) during protein synthesis in an in vitro coupled transcription/translation system was investigated. The low incorporation in comparison to formyl-methionine was not due to the lack of interaction of fluorophore-Met-tRNA(f) with IF-2. Fluorescence measurements of cascade yellow-, eosin-, pyrene-, or coumarin-Met-tRNA(f) determined that all were capable of binding IF-2 at 4 mM Mg(2+) and 37 degrees C. Filter binding assays conducted in the absence of magnesium ions on fMet-tRNA(f), eosin-Met-tRNA(f), and cascade yellow-Met-tRNA(f) confirmed the previously reported value for the dissociation constant of fMet-tRNA(f) of about 1 microM and placed the binding constants for the two fluorophore derivatives about three-fold higher. Binding of the fluorophore-Met-tRNA(f) species to salt-washed ribosomes showed a more significant decrease compared to fMet-tRNA(f). Stimulation in the amount of tRNA bound to the ribosomes upon the addition of IF-2 was observed in each case. All ribosome-bound cascade yellow-Met-tRNA(f) and eosin-Met-tRNA(f) were as puromycin-reactive as fMet-tRNA(f). Cumulatively, the effects observed for the fluorophore-Met-tRNA species in partial reactions of initiation may account for the reduced incorporation of these probes at the N terminus of polypeptides.

Fluorophores at the N terminus of nascent chloramphenicol acetyltransferase peptides affect translation and movement through the ribosome

Structurally different fluorescent probes were covalently attached to methionyl-tRNA(f) and tested for their incorporation into nascent peptides and full-length protein using an Escherichia coli cell-free coupled transcription/translation system. Bovine rhodanese and bacterial chloramphenicol acetyltransferase (CAT) were synthesized using derivatives of cascade yellow, eosin, pyrene, or coumarin attached to [(35)S]Met-tRNA(f). All of the probes tested were incorporated into polypeptides, although less efficiently when compared with formyl-methionine. Eosin, the largest of the fluorophores used with estimated dimensions of 20 x 11 A, caused the largest reduction in product formed. The rate of initiation was reduced with the fluorophore-Met-tRNA(f) compared with fMet-tRNA(f) with pyrene having the least and eosin the biggest effect. Analysis of the nascent polypeptides showed that the modifications at the N terminus affected the rate at which nascent CAT peptides were elongated causing accumulation of peptides of about 4 kDa, possibly by steric hindrance inside the tunnel within the 50 S ribosomal subunit. Fluorescence measurements indicate that the probe at the N terminus of nascent pyrene-CAT peptides is in a relatively hydrophilic environment. This finding is in agreement with recent data showing cross-linking of the N terminus of nascent peptides to nucleotides of the 23 S ribosomal RNA.

Role of bacteria in the development of kidney stones

Currently, only struvite stones are regarded as deriving from bacteria. Recent work has suggested that calcium-based stones might also have an infectious origin. Nanobacteria, small intracellular bacteria found in human kidney stones, are capable of forming a calcium phosphate shell, and thus could serve as crystallization centres for renal calculi formation. Until now, however, all trials performed to confirm the presence of nanobacteria in human calculi, serum or urine have failed. In a hyperoxaluric rat model, tissue-residing macrophages were able to remove interstitial crystals and thus may not be primarily engaged in defending against micro-organisms, if present.