Impact of kV-cone beam computed tomography dose on DNA repair mechanisms: A pilot study.

PURPOSE: In head and neck squamous cell carcinoma (HNSCC), early complications of the radiotherapy (RT) are observed from the beginning of the treatment to a few months after its end. During external radiotherapy treatment, several patient-dependent parameters can cause a modification of the dose distribution compared to the planned distribution due to variation in patient positioning, anatomy, or intra-fractional movements for example. To verify these parameters during treatment sessions, one of the most commonly used solutions is the cone-beam computed tomography (CBCT). Nowadays, the use of CBCT may constitutes a significant part of the total dose at the end of treatment (up to 10 cGy per session) and more often the volume irradiated by imaging is larger than the one irradiated by the treatment, leading to unintentional irradiation of nearby organs. In this study, we asked whether the imaging low dose added to a following fraction dose (2Gy) may affect the biological response in terms of DNA repair. MATERIAL AND METHODS: Using an IVInomad dosimeter and scintillating fiber probes specially designed for this exploratory study, we exposed fibroblasts cells from head and neck cancer (HNC) patients to a CBCT dose followed by a radiotherapy fraction dose. DNA double strand breaks and DNA repair were assessed by immunofluorescence using the biomarkers gamma H2AX (γH2AX) and pATM. RESULTS: The median dose of CBCT was measured between 17 to 21 mGy per session. The kinetics of both biomarkers were found to be strongly dependent on the individual factor in radiosensitive patients. For HNC patients, a prior CBCT dose applied few minutes before the 2Gy dose may have a sublinear effect on the DNA repair mechanisms and potentially on observed health tissue toxicity. CONCLUSION: The preliminary results obtained highlight the importance of individual and tissue factors for recognizing and repairing DSB during a treatment by radiotherapy using CBCT.

Dietary modulation of peroxisome proliferator-activated receptor gamma.

Peroxisome proliferator-activated receptor gamma (PPAR gamma) is a nuclear receptor that regulates intestinal inflammation. PPAR gamma is highly expressed in the colon and can be activated by various dietary ligands. A number of fatty acids such as polyunsaturated fatty acids or eicosanoids are considered as endogenous PPAR gamma activators. Nevertheless, other nutrients such as glutamine, spicy food or flavonoids are also able to activate PPAR gamma. As PPAR gamma plays a key role in bacterial induced inflammation, anti-inflammatory properties of probiotics may be mediated through PPAR gamma. The aims of the present review are to discuss of the potential roles of dietary compounds in modulating intestinal inflammation through PPAR gamma.

Temporary ex vivo inhibition of the expression of the human oncogene HER2 (NEU) by a triple helix-forming oligonucleotide.

A 28-base phosphodiester triple helix-forming oligonucleotide, mostly G and A containing, targeted to a polypurine tract interrupted by a purine-pyrimidine inversion, situated upstream from the TATA box of the promoter of the human HER2 gene, was conceived by computer modeling. The "energetically best choice" was oligo 28(C), which formed the triple helix in vitro, as proved by gel retardation and Fourier transform infrared spectroscopy. When administered as a complex with lipofectin, fluorescence confocal microscopy and electrophoresis confirmed the delivery and persistence of this unprotected oligonucleotide inside MCF7 (breast cancer) cells. At a concentration of 2 microM, the oligonucleotide reduced within 6 h the HER2 mRNA level to 42% (Northern blot) but did not interfere with the transcription of a housekeeping gene, glyceraldehyde-3-phosphate dehydrogenase. During the first day of administration at 0.22 microM, it lowered to 59% the HER2 protein in treated, as compared to nontreated, cells (ELISA). The effect was sequence specific when compared to that of five different negative controls, and it was target selective when compared to the expression of a related, nontargeted protein, the epidermal growth factor receptor. By day 2, the inhibitory effect was overcome by replenishment reactions.

Triple-helices targeted to the polypurine tract of a murine retrovirus.

The all-purine 13-mer oligodeoxyribonucleotide d(GGGGGGAAAAAGA), containing an unusually large block of contiguous guanines, was shown by electrophoresis and thermoelution to form a specific, 'antiparallel' complex with the duplex containing the polypurine tract of murine retroviruses. Fourier transform infra-red spectroscopy (FTIR) and molecular modeling indicated that the complex is based on reverse Hoogsteen G(GC) and A(AT) triplets, with anti orientations of the bases and with all the strands having S-type sugar conformations. This G + A-containing 13-mer and a G + T-containing 22-mer, d(TGTTTGTTTGGGGGGTTTTTGT), aimed at the same target, retarded in a sequence-specific manner the spreading of the Friend retrovirus in Dunni cells infected de novo, thus indicating that the polypurine tract of retroviruses may be a suitable target for anti-gene action.

Particular behavior of the adenine and guanine ring-breathing modes upon the DNA conformational transitions.

Harmonic dynamics calculations performed on the deoxyguanosine (dG) and deoxyadenosine (dA) residues, based on a reliable force field, show that the breathing motions of both guanine and adenine residues are involved in two different vibration modes (750-500 cm-1 spectral region). The calculated results reveal a strong coupling of these modes with the sugar pucker motions. This effect has been verified for the dG residue by the Raman spectra of polyd(G-C). As far as the dA residue is concerned, the particular behavior of the adenine residue breathing mode predicted by these calculations, has been confirmed by Raman spectra of polyd(A-T) undergoing a B----Z conformational transition.

Self-reported safety practices in child care facilities.

To determine the prevalence of safety hazards and current injury prevention practices in child care settings, we administered a structured telephone interview to a geographically stratified, randomly selected sample of licensed child care facilities. Representatives of 130 child care facilities responded to questions about current injury prevention practices. Specific hazards assessed were related to burns, falls, poisoning, playgrounds, and emergency telephone numbers. Results indicated that 26.8% of providers who knew the temperature of their tap water stated that it was over 130 degrees F.; 14.1% had space heaters accessible to children; 30.3% of those with stairs accessible to children lacked safety gates; 61.4% of those with playgrounds did not have an impact-absorbing surface under playground equipment; 16.9% of respondents had an unexpired bottle of syrup of ipecac; 55.8% demonstrated that a poison control center telephone number was available to them; and 80% of providers could demonstrate the availability of the telephone number of the local ambulance. We conclude that potential and remedial injury hazards exist in some licensed child care centers and that providers of child care within licensed facilities are a promising target for childhood injury prevention interventions.

Interpretation of DNA vibration modes: I--The guanosine and cytidine residues involved in poly(dG-dC).poly(dG-dC) and d(CG)3.d(CG)3.

A normal coordinate analysis has been carried out on guanosine and cytidine residues appearing in oligo and polynucleotides by using a simplified valence force field that allows the vibrational spectra of 5'-dGMP and 2'-deoxycytidine molecules to be reproduced. The role of both C2'-endo and C3'-endo conformations on sugar pucker, as well as that of glycosidic torsion angle (X), on several characteristic vibration modes of these residues have been studied. The present calculations based on a non-redundant set of internal coordinates preserving the harmonic approximation of the potential field, allows us to explain quite satisfactorily the modifications of the vibrational spectra in the 1550-1250 cm-1 and 785-500 cm-1 regions, when the right----left-handed conformational transition occurs.

Interpretation of DNA vibration modes. II--The adenosine and thymidine residues involved in oligonucleotides and polynucleotides.

Normal coordinate analysis of the adenosine and thymidine residues involved in the right- and left-handed conformations of oligonucleotides and polynucleotides has been performed. The valence force field, employed in this work, allowed recently to reproduce the vibrational spectra of 2'-deoxythymidine and 2'-deoxyadenosine. The calculated wavenumbers based on a non-redundant set of internal coordinates have been compared to the Raman and infrared peak positions arising from A, B, C, D and Z conformations, in the 1550-1250 cm-1 and 800-600 cm-1 spectral regions: i.e. characteristic of adenosine and thymidine residues. Moreover, a systematic study has been performed on the evolution of the vibrational wavenumbers as a function of the glycosidic angle (chi) and the sugar pucker conformation.

Interpretation of DNA vibration modes: IV--A single-helical approach to assign the phosphate-backbone contribution to the vibrational spectra in A and B conformations.

A calculated approach based on the Higgs method for assigning the vibration modes of an infinite helicoidal polymeric chain has been performed on the basis of a reliable valence force field. The calculated results allowed the phosphate-backbone marker modes of the A and B forms, to be interpreted. In the dynamic models used, the bases have been omitted and no interchain interaction was considered. The calculation can also interprete quite satisfactorily the characteristic Raman peaks and infrared bands in the 1250-700 cm-1 spectral region arising from the sugar or sugar-phosphate association and reproduce their evolution upon the B----A DNA conformational transition. They clearly show that the phosphate-backbone modes in the above mentioned spectral region constitute the optical branches of the phonon dispersion curves with no detectable variation in the first Brillouin-zone.

Molecular modelling of 9-aminoellipticine interactions with abasic oligonucleotides.

We have used molecular mechanics to study the insertion of the DNA intercalating agent 9-aminoellipticine (9AE) into single and double stranded abasic oligonucleotides containing abasic sites in the aldose or furanose conformations. 9AE-abasic oligonucleotide complexes have been considered with 9AE bound at abasic sites as a covalent complex, a reversible complex or a Schiff base. Results are in good agreement with experimental data available on abasic oligonucleotides (melting temperature measurement, NMR results) and allow an analysis of different possible structures for 9AE-abasic oligonucleotide complexes. Hypotheses concerning the role of 9AE-abasic site complexes in enzymatic inhibition are formulated from these data.

Normal coordinate analysis of 2'-deoxythymidine and 2'-deoxyadenosine.

The proposed valence force field allows us to reproduce the vibration modes of 2'-deoxythymidine and 2'-deoxyadenosine. The present calculations are based on the Wilson GF-method and a non-redundant set of symmetrical coordinates. The calculated wavenumbers have been compared to the available Raman and infrared peak positions observed in solid, amorphous or aqueous samples. Moreover, the results obtained with the present force field allow us to assign some of the characteristic vibration modes for the thymidine and adenosine residues involved in DNA double-helical chains.

Episiotomy repair: chromic versus polyglycolic acid suture.

The use of an episiotomy for vaginal delivery is a controversial topic in modern obstetrics. If one is done, however, correct technique and appropriate suture material are important. On the LSU Obstetrics Service, the usual midline episiotomy has traditionally been closed with 2-0 chromic suture. Theoretically, the use of a less reactive material, eg, polyglycolic acid (Dexon), may be beneficial in terms of acute postpartum discomfort and healing. As a comparison of healing and patient comfort parameters between 2-0 chromic and 2-0 polyglycolic acid suture used for episiotomy repair after delivery, two consecutive months' worth of parturients at Medical Center of Louisiana/Charity Hospital had episiotomy repair, with either chromic or polyglycolic acid suture, by junior house officers routinely attending delivery. Patients had follow-up during hospital stay, and when examined at 6 weeks for evidence of suture line healing, they were also asked about comfort and resumption of sexual activity. Of 48 patients who had repair with 2-0 chromic suture, 6 were lost to follow-up. Of 44 gravidas who had repair with 2-0 polyglycolic acid suture, 7 were lost to follow-up. At the 6-week postpartum examination, patients with polyglycolic acid sutures had significantly better healing. A noticeable scar was present in 42 of 42 patients with chromic sutures versus 21 of 37 in the polyglycolic acid group, a scar with granulation tissue in 16 of 42 versus 3 of 37, and a gaping scar in 9 of 42 and 0 of 37, respectively. Recovery of function, measured by resumption of sexual activity by 6 weeks, was demonstrated in 1 of 42 patients who had chromic sutures versus 19 of 37 patients who had polyglycolic acid sutures. Episiotomy repair with 2-0 polyglycolic acid (Dexon) offers significant advantages over traditional 2-0 chromic suture, both in terms of wound healing and resumption of normal patient activity, including sexual activity.

Phosphatidylglycerol and fetal lung maturity.

The lecithin/sphingomyelin (L/S) ratio has been reported to be inadequate as a predictor of fetal surfactant maturity in many complicated obstetric cases, particularly in patients with diabetes. L/S ratios are also unreliable when the sample contains blood or meconium. Phosphatidylglycerol (PG) is present only in amniotic fluid and respiratory tract effluent. PG may characterize surfactant maturity in samples of amniotic fluid contaminated with blood or meconium as well as specimens collected from the vagina in cases of premature rupture of membranes. Three hundred eleven samples of amniotic fluid collected from January, 1980, to June, 1981, were analyzed for L/S ratio and PG. This report analyses the ability of these tests to predict neonatal maturity in normal and complicated obstetric cases.

Interpretation of DNA vibrational spectra by normal coordinate analysis.

1. In the following article we undertake a brief review of the most prominent DNA vibrational markers as observed experimentally by Raman and i.r. spectroscopies on polynucleotides and explain how a simplified valence force field can account for the evolution of the DNA vibrational spectra. 2. Our discussion made as a review of our previous investigations on the interpretation of DNA vibration modes, is based on some of the most characteristic and structure dependent DNA vibrational markers.

Production of a phosphatidylglycerol-like substance by genital flora bacteria.

Bacteria contaminating amniotic fluid have anecdotally been shown to produce a phosphatidylglycerol-like substance, thus giving false positive tests for phosphatidylglycerol in vaginal pool fluid from patients with premature rupture of the membranes. Isolates of Escherichia coli, Proteus mirabilis, Acinetobacter calcoaceticus, Klebsiella pneumoniae, Staphylococcus aureus, coagulase-negative Staphylococcus, Streptococcus faecalis, and Streptococcus agalactiae (group B streptococcus) were grown in broth and analyzed for the presence of phosphatidylglycerol-like material by one-dimensional thin-layer chromatography and also by a polyclonal, immunologic slide agglutination test (Amniostat-FLM). All species demonstrated a positive test result for phosphatidylglycerol by either thin-layer chromatography, slide agglutination, or both. The material migrated separately from cardiolipin and phosphatidylethanolamine as determined by chromatography, but identically with the phosphatidylglycerol control. Gram-negative species were more strongly positive than gram-positive organisms. Colony counts on the order of 10(8) colony-forming units per milliliter were necessary to give positive test results for phosphatidylglycerol. The possible clinical implications of these findings are discussed.

Elective versus emergency cesarean hysterectomy on a teaching service--1981 to 1991.

We compared the differences in morbidity of elective and emergency cesarean hysterectomy (CH) in a training program. Records of patients who had elective or emergency CH were reviewed for information reflecting perioperative morbidity and fetal outcome. Eighty-eight CHs were elective and 18 were emergencies. Compared to emergency CHs, operative time for elective CHs was 30 minutes less, intraoperative blood loss was 700 mL lower, less postoperative blood replacement was needed, and hospital stay was 3.5 days shorter. Emergency CH had nearly twice the frequency of postoperative febrile morbidity and a three-times-higher rate of morbidity due to other causes. CHs were done at a gestational age of 36 or more weeks in 81.6% of elective cases, compared to only 50% of emergency cases. Mean birth weight of newborns delivered electively was 900 g higher, and Apgar scores were better. These data show that CHs done by house staff in training have a significantly lower complication rate when the operations are elective rather than emergent.

Comparison of morbidity in cesarean section hysterectomy versus cesarean section tubal ligation.

This study was undertaken to compare the morbidity of cesarean section hysterectomy (C-HYST) and cesarean section bilateral tubal ligation (C-BTL) in a nonemergency or elective environment. Charts were reviewed for patients who underwent elective C-HYST or elective C-BTL before the onset of labor, without the use of antibiotics. Demographics, maternal morbidity, operative difficulties and postoperative complications were compared. Statistically significant differences in patient demographics include a higher maternal age in the C-HYST group than for those in the C-BTL group (31.0 +/- 5.8 versus 27.7 +/- 5.4 years; p = 0.002). C-BTL patients had higher gestational ages (39.4 +/- 1.6 versus 38.7 +/- 1.3 years; p = 0.0017). The C-HYST group had a higher estimated blood loss (1,201 +/- 472 versus 718 +/- 364 milliliters; p = 0.001), change in hematocrit level (6.0 +/- 4.4 percent versus 4.5 +/- 3.4 percent; p = 0.013) and operating time (115 +/- 37 versus 74 +/- 26 minutes; p = 0.0001). Blood transfusion was similar in both groups. Febrile morbidity was higher in the C-BTL group (68.0 percent versus 50.0 percent; p = 0.01). Endometritis was the significant determinant of febrile morbidity for the C-BTL group (41.7%) and cuff cellulitis in the C-HYST group (25.6 percent). Intraoperative and postoperative complications between the two groups were rare and not statistically different. Clinical morbidity for C-HYST is not significantly different than C-BTL. Elective C-HYST may be used in place of C-BTL when indications for hysterectomy are present.

A possible family of B-like triple helix structures: comparison with the Arnott A-like triple helix.

Recent experimental studies of the structure of triple helices show that their conformation in solution differs from the A-like structure derived from diffraction data on triple helix fibers by Arnott and co-workers. Here we show by means of molecular modeling that a family of triple helix structures may exist with similar conformational energies, but with a variety of sugar puckers. The characteristics of these putative triple helices are analyzed for three different base sequences: (T.AxT)n, (C.GxC+)n, and alternating (C.GxC+/T.AxT)n. In the case of (C.GxC+)n triple helix, infrared and Raman spectra have been obtained and clearly reveal the existence of both N- and S-type sugars in solution. The molecular mechanics calculations allow us to propose a stereochemically reasonable model for this triple helix, in good agreement with the vibrational spectroscopy results.

Triple helix formation by alpha-oligodeoxynucleotides: a vibrational spectroscopy and molecular modeling study.

The structures of triple helices alpha dT6.beta dAn.beta dTn, alpha dT12.beta dAn.beta dTn, alpha dC12+.beta dGn.beta dCn, and alpha dC12+.beta rGn.beta rCn have been studied by Fourier transform infrared spectroscopy, Raman spectroscopy, and molecular mechanics calculations. The sugar conformations in these triplexes have been determined by vibrational spectroscopy. Our results show the existence of only S-type sugars in the alpha dT12.beta dAn.beta dTn triple helix. Both S- and N-type sugar infrared and Raman markers have been detected in the spectra of alpha dC12+.beta dGn.beta dCn. Molecular mechanics refinements taking into account vibrational spectroscopy data constraints allow us to propose third strand hydrogen-bonding schemes and third strand polarities in triple helix models. For alpha dT12.beta dA12.beta dT12 the third strand forms reverse Hoogsteen hydrogen bonds with the beta dA12 strand and therefore is parallel to the purine strand. In contrast, for alpha dC12+.beta dG12.beta dC12 calculations show that only a model in which the third strand is Hoogsteen base paired and antiparallel to the purine strand of the Watson-Crick duplex is compatible with spectroscopic data.

Parallel and antiparallel A*A-T intramolecular triple helices.

Intramolecular triple helices have been obtained by folding back twice oligonucleotides formed by decamers bound by non-nucleotide linkers: dA10-linker-dA10-linker-dT10 and dA10-linker-dT10-linker-dA10. We have thus prepared two triple helices with forced third strand orientation, respectively antiparallel (apA*A-T) and parallel (pA*A-T) with respect to the adenosine strand of the Watson-Crick duplex. The existence of the triple helices has been shown by FTIR, UV and fluorescence spectroscopies. Similar melting temperatures have been obtained in very different oligomer concentration conditions (micromolar solutions for thermal denaturation classically followed by UV spectroscopy, milimolar solutions in the case of melting monitored by FTIR spectroscopy) showing that the triple helices are intramolecular. The stability of the parallel triplex is found to be slightly lower than that of the antiparallel (deltaT(m) = 6 degrees C). The sugar conformations determined by FTIR are different for both triplexes. Only South-type sugars are found in the antiparallel triplex whereas both South- and North-type sugars are detected in the parallel triplex. In this case, thymidine sugars have a South-type geometry, and the adenosine strand of the Watson-Crick duplex has North-type sugars. For the antiparallel triplex the experimental results and molecular modeling data are consistent with a reverse-Hoogsteen like third-strand base pairing and South-type sugar conformation. An energetically optimized model of the parallel A*A-T triple helix with a non-uniform distribution of sugar conformations is discussed.