Toll-like receptor 9 polymorphisms in brazilian patients with systemic lupus erythematosus: a pilot study / Polimorfismos do receptor toll-like 9 em pacientes brasileiros com lúpus eritematoso sistêmico: um estudo piloto

Abstract Toll-like receptor 9 (TLR9) is an important component of the innate immune system and have been associated with several autoimmune diseases, such as Systemic Lupus Erythematosus (SLE). The aim of this study was to investigate polymorphisms in TLR9 gene in a Brazilian SLE patients group and their association with clinical manifestation, particularly Jaccoud's arthropathy (JA). We analyzed DNA samples from 204 SLE patients, having a subgroup of them presenting JA (n=24). A control group (n=133) from the same city was also included. TLR9 single nucleotide polymorphisms (SNPs) (−1237 C>T and +2848 G>A) were identified by sequencing analysis. The TLR9 gene genotype frequency was similar both in SLE patients and the control group. In the whole SLE population, an association between the homozygosis of allele C at position −1237 with psychosis and anemia (p < 0.01) was found. Likewise, the homozygosis of allele G at position +2848 was associated with a discoid rash (p < 0.05). There was no association between JA and TLR9 polymorphisms. These data show that TLR9 polymorphisms do not seem to be a predisposing factor for SLE in the Brazilian population, and that SNPs are not associated with JA.

Resumo O receptor Toll-like 9 (TLR9) é um componente importante do sistema imunológico inato e tem sido associado a várias doenças autoimunes, como o Lúpus Eritematoso Sistêmico (LES). O objetivo deste estudo foi investigar polimorfismos no gene TLR9 em um grupo de pacientes brasileiros com LES e sua associação com a manifestação clínica, particularmente a artropatia de Jaccoud (JA). Foram analisadas amostras de DNA de 204 pacientes com LES, e um subgrupo com JA (n=24). Um grupo de controle (n=133) da mesma cidade também foi incluído. Os polimorfismos de nucleotídeos únicos TLR9 (SNPs) (−1237 C>T e +2848 G>A) foram identificados pela análise de sequenciamento. A frequência do genótipo genético TLR9 foi semelhante tanto em pacientes com LES quanto no grupo controle. Em toda a população de LES, foi encontrada associação entre a homozigose do alelo C na posição −1237 com psicose e anemia (p < 0,01). Da mesma forma, a homozigose do alelo G na posição +2848 foi associada a uma erupção cutânea discoide (p < 0,05). Não houve associação entre polimorfismos JA e TLR9. Esses dados mostram que os polimorfismos TLR9 não parecem ser um fator predisponível para o LES na população brasileira, e que os SNPs não estão associados ao JA.

Toll-like receptor 9 polymorphisms in brazilian patients with systemic lupus erythematosus: a pilot study / Polimorfismos do receptor toll-like 9 em pacientes brasileiros com lúpus eritematoso sistêmico: um estudo piloto

Toll-like receptor 9 (TLR9) is an important component of the innate immune system and have been associated with several autoimmune diseases, such as Systemic Lupus Erythematosus (SLE). The aim of this study was to investigate polymorphisms in TLR9 gene in a Brazilian SLE patients group and their association with clinical manifestation, particularly Jaccoud’s arthropathy (JA). We analyzed DNA samples from 204 SLE patients, having a subgroup of them presenting JA (n=24). A control group (n=133) from the same city was also included. TLR9 single nucleotide polymorphisms (SNPs) (−1237 C>T and +2848 G>A) were identified by sequencing analysis. The TLR9 gene genotype frequency was similar both in SLE patients and the control group. In the whole SLE population, an association between the homozygosis of allele C at position −1237 with psychosis and anemia (p < 0.01) was found. Likewise, the homozygosis of allele G at position +2848 was associated with a discoid rash (p < 0.05). There was no association between JA and TLR9 polymorphisms. These data show that TLR9 polymorphisms do not seem to be a predisposing factor for SLE in the Brazilian population, and that SNPs are not associated with JA.

O receptor Toll-like 9 (TLR9) é um componente importante do sistema imunológico inato e tem sido associado a várias doenças autoimunes, como o Lúpus Eritematoso Sistêmico (LES). O objetivo deste estudo foi investigar polimorfismos no gene TLR9 em um grupo de pacientes brasileiros com LES e sua associação com a manifestação clínica, particularmente a artropatia de Jaccoud (JA). Foram analisadas amostras de DNA de 204 pacientes com LES, e um subgrupo com JA (n=24). Um grupo de controle (n=133) da mesma cidade também foi incluído. Os polimorfismos de nucleotídeos únicos TLR9 (SNPs) (−1237 C>T e +2848 G>A) foram identificados pela análise de sequenciamento. A frequência do genótipo genético TLR9 foi semelhante tanto em pacientes com LES quanto no grupo controle. Em toda a população de LES, foi encontrada associação entre a homozigose do alelo C na posição −1237 com psicose e anemia (p < 0,01). Da mesma forma, a homozigose do alelo G na posição +2848 foi associada a uma erupção cutânea discoide (p < 0,05). Não houve associação entre polimorfismos JA e TLR9. Esses dados mostram que os polimorfismos TLR9 não parecem ser um fator predisponível para o LES na população brasileira, e que os SNPs não estão associados ao JA.

Toll-like receptor 9 polymorphisms in brazilian patients with systemic lupus erythematosus: a pilot study

Abstract Toll-like receptor 9 (TLR9) is an important component of the innate immune system and have been associated with several autoimmune diseases, such as Systemic Lupus Erythematosus (SLE). The aim of this study was to investigate polymorphisms in TLR9 gene in a Brazilian SLE patients group and their association with clinical manifestation, particularly Jaccouds arthropathy (JA). We analyzed DNA samples from 204 SLE patients, having a subgroup of them presenting JA (n=24). A control group (n=133) from the same city was also included. TLR9 single nucleotide polymorphisms (SNPs) (1237 C>T and +2848 G>A) were identified by sequencing analysis. The TLR9 gene genotype frequency was similar both in SLE patients and the control group. In the whole SLE population, an association between the homozygosis of allele C at position 1237 with psychosis and anemia (p 0.01) was found. Likewise, the homozygosis of allele G at position +2848 was associated with a discoid rash (p 0.05). There was no association between JA and TLR9 polymorphisms. These data show that TLR9 polymorphisms do not seem to be a predisposing factor for SLE in the Brazilian population, and that SNPs are not associated with JA.

Resumo O receptor Toll-like 9 (TLR9) é um componente importante do sistema imunológico inato e tem sido associado a várias doenças autoimunes, como o Lúpus Eritematoso Sistêmico (LES). O objetivo deste estudo foi investigar polimorfismos no gene TLR9 em um grupo de pacientes brasileiros com LES e sua associação com a manifestação clínica, particularmente a artropatia de Jaccoud (JA). Foram analisadas amostras de DNA de 204 pacientes com LES, e um subgrupo com JA (n=24). Um grupo de controle (n=133) da mesma cidade também foi incluído. Os polimorfismos de nucleotídeos únicos TLR9 (SNPs) (1237 C>T e +2848 G>A) foram identificados pela análise de sequenciamento. A frequência do genótipo genético TLR9 foi semelhante tanto em pacientes com LES quanto no grupo controle. Em toda a população de LES, foi encontrada associação entre a homozigose do alelo C na posição 1237 com psicose e anemia (p 0,01). Da mesma forma, a homozigose do alelo G na posição +2848 foi associada a uma erupção cutânea discoide (p 0,05). Não houve associação entre polimorfismos JA e TLR9. Esses dados mostram que os polimorfismos TLR9 não parecem ser um fator predisponível para o LES na população brasileira, e que os SNPs não estão associados ao JA.

Toll-like receptor 9 polymorphisms in brazilian patients with systemic lupus erythematosus: a pilot study.

Toll-like receptor 9 (TLR9) is an important component of the innate immune system and have been associated with several autoimmune diseases, such as Systemic Lupus Erythematosus (SLE). The aim of this study was to investigate polymorphisms in TLR9 gene in a Brazilian SLE patients group and their association with clinical manifestation, particularly Jaccoud's arthropathy (JA). We analyzed DNA samples from 204 SLE patients, having a subgroup of them presenting JA (n=24). A control group (n=133) from the same city was also included. TLR9 single nucleotide polymorphisms (SNPs) (-1237 C>T and +2848 G>A) were identified by sequencing analysis. The TLR9 gene genotype frequency was similar both in SLE patients and the control group. In the whole SLE population, an association between the homozygosis of allele C at position -1237 with psychosis and anemia (p < 0.01) was found. Likewise, the homozygosis of allele G at position +2848 was associated with a discoid rash (p < 0.05). There was no association between JA and TLR9 polymorphisms. These data show that TLR9 polymorphisms do not seem to be a predisposing factor for SLE in the Brazilian population, and that SNPs are not associated with JA.

n-3 polyunsaturated fatty acid supplementation reduces insulin resistance in hepatitis C virus infected patients: a randomised controlled trial.

BACKGROUND: Insulin resistance promotes liver disease progression and may be associated with a lower response rate in treated hepatitis C virus (HCV) infected patients. n-3 polyunsaturated fatty acid (PUFA) supplementation may reduce insulin resistance. The present study aimed to evaluate the effect of n-3 PUFA supplementation on insulin resistance in these patients. METHODS: In a randomised, double-blind clinical trial, 154 patients were screened. After applying inclusion criteria, 52 patients [homeostasis model assessment index of insulin resistance (HOMA-IR ≥2.5)] were randomly divided into two groups: n-3 PUFA (n = 25/6000 mg day(-1) of fish oil) or control (n = 27/6000 mg day(-1) of soybean oil). Both groups were supplemented for 12 weeks and underwent monthly nutritional consultation. Biochemical tests were performed at baseline and after intervention. Statistical analysis was performed using the Wilcoxon Mann-Whitney test for comparisons and the Wilcoxon test for paired data. Statistical package r, version 3.02 (The R Project for Statistical Computing) was used and P < 0.05 (two-tailed) was considered statistically significant. RESULTS: Comparisons between groups showed that n-3 PUFA supplementation was more effective than the control for reducing HOMA-IR (P = 0.015) and serum insulin (P = 0.016). The n-3 PUFA group not only showed a significant reduction in HOMA-IR 3.8 (3.2-5.0) versus 2.4 (1.8-3.3) (P = 0.002); serum insulin 17.1 (13.8-20.6) µIU mL(-1) versus 10.9 (8.6-14.6) µIU mL(-1) (P = 0.001); and glycated haemoglobin 5.4% (5.0-5.7%) versus 5.1% (4.8-5.6%) (P = 0.011), but also presented an increase in interleukin-1 97.5 (0.0-199.8) pg mL(-1) versus 192.4 (102.2-266.8) pg mL(-1) (P = 0.003) and tumour necrosis factor 121.2 (0.0-171.3) pg mL(-1) versus 185.7 (98.0-246.9) pg mL(-1) (P = 0.003). CONCLUSIONS: n-3 PUFA supplementation reduces insulin resistance in genotype 1 HCV infected patients.

The impact of nutritional supplementation on quality of life in patients infected with hepatitis C virus.

BACKGROUND: The present study aimed to evaluate the impact of animal and vegetable protein supplementation on health-related quality of life (HRQL) in patients with hepatitis C virus (HCV) and to investigate clinical and nutritional variables related to quality of life in these patients. METHODS: One hundred and forty patients infected with HCV were randomly assigned to one of two groups: the Soy Group (SG; n = 72), where patients received a soy supplement diet and the Casein Group (CG; n = 68), where patients received casein as a supplement. Anthropometric, biochemical and clinical assessments were performed in all patients, and the Short-Form Health Survey was applied at baseline and 12 weeks after study initiation. RESULTS: Before supplementation, poor HRQL scores were associated with female sex (P = 0.004) and advanced fibrosis (F3/F4; P = 0.04). Reduced HRQL scores were correlated with age (r = -0.263; P = 0.002), serum albumin levels (r = 0.245; P = 0.004), lean mass (r = 0.301; P < 0.0001) and body fat percentage (r = -0.262; P = 0.002). After 12 weeks of intervention, patients in both supplementation groups showed significantly increased HRQL scores, with no difference being observed between the SG and the CG. CONCLUSIONS: Nutritional therapy with either soybean or casein supplementation improved quality of life in patients infected with HCV. Quality of life was influenced by anthropometric, biochemical, clinical and sociodemographic factors in patients with HCV before nutritional supplementation.

Coping with genetic diversity: the contribution of pathogen and human genomics to modern vaccinology

Vaccine development faces major difficulties partly because of genetic variation in both infectious organisms and humans. This causes antigenic variation in infectious agents and a high interindividual variability in the human response to the vaccine. The exponential growth of genome sequence information has induced a shift from conventional culture-based to genome-based vaccinology, and allows the tackling of challenges in vaccine development due to pathogen genetic variability. Additionally, recent advances in immunogenetics and genomics should help in the understanding of the influence of genetic factors on the interindividual and interpopulation variations in immune responses to vaccines, and could be useful for developing new vaccine strategies. Accumulating results provide evidence for the existence of a number of genes involved in protective immune responses that are induced either by natural infections or vaccines. Variation in immune responses could be viewed as the result of a perturbation of gene networks; this should help in understanding how a particular polymorphism or a combination thereof could affect protective immune responses. Here we will present: i) the first genome-based vaccines that served as proof of concept, and that provided new critical insights into vaccine development strategies; ii) an overview of genetic predisposition in infectious diseases and genetic control in responses to vaccines; iii) population genetic differences that are a rationale behind group-targeted vaccines; iv) an outlook for genetic control in infectious diseases, with special emphasis on the concept of molecular networks that will provide a structure to the huge amount of genomic data.

Coping with genetic diversity: the contribution of pathogen and human genomics to modern vaccinology.

Vaccine development faces major difficulties partly because of genetic variation in both infectious organisms and humans. This causes antigenic variation in infectious agents and a high interindividual variability in the human response to the vaccine. The exponential growth of genome sequence information has induced a shift from conventional culture-based to genome-based vaccinology, and allows the tackling of challenges in vaccine development due to pathogen genetic variability. Additionally, recent advances in immunogenetics and genomics should help in the understanding of the influence of genetic factors on the interindividual and interpopulation variations in immune responses to vaccines, and could be useful for developing new vaccine strategies. Accumulating results provide evidence for the existence of a number of genes involved in protective immune responses that are induced either by natural infections or vaccines. Variation in immune responses could be viewed as the result of a perturbation of gene networks; this should help in understanding how a particular polymorphism or a combination thereof could affect protective immune responses. Here we will present: i) the first genome-based vaccines that served as proof of concept, and that provided new critical insights into vaccine development strategies; ii) an overview of genetic predisposition in infectious diseases and genetic control in responses to vaccines; iii) population genetic differences that are a rationale behind group-targeted vaccines; iv) an outlook for genetic control in infectious diseases, with special emphasis on the concept of molecular networks that will provide a structure to the huge amount of genomic data.

Vascular endothelial growth factor (VEGF) levels as a tool to discriminate between malignant and nonmalignant ascites.

Ascites formation is commonly associated with cancer, although it is also present in other diseases. The aim of this study was to evaluate the usefulness of vascular endothelial growth factor as a malignancy marker in ascites of different etiologies. The levels of VEGF in 32 malignant and in 31 non-malignant ascites were determined by enzyme immunoassay (ELISA). VEGF levels were significantly higher in malignant than in non-malignant ascites (median=1265.9 pg/ml x 114.6 pg/ml; p<0.0001). We observed 72% sensitivity and 90% specificity, using 662 pg/ml as a cut-off value. Therefore, this approach can be used as a marker for a first screening to discriminate between malignant and nonmalignant ascites.

Lessons from the year 2001 Mycosphaerella graminicola epidemic on winter wheat in Belgium.

Infection by Mycosphaerella graminicola (anamorph Septoria tritici) was monitored between April and July 2001 on F6 to flag leaf in 11 farmers' fields or fungicide trials. Data were analysed by mean of the decision support system "Proculture" which links an automatic weather station of the PAMESEB network to a particular field, simulates plant development with adjustment by one phenological observation during the stem elongation and analyses superposition of emerged leaves and infection events (http://www.fymy.ucl.ac.be/proculture). Several climatic events favourable for the infection and dissemination of M. graminicola occurred between October 2000 and March 2001 and allowed build up of a large amount of inoculum on the lower leaves at the end of the winter. The start of stem elongation was associated with frequent rainy periods during April, causing early infection of F5, F4 and up to F3 in some precocious fields. Dry weather with only a few local showers during most of May and June slowed down spread of infection to the upper leaves, leading to absence of M. graminicola infection of the flag leaf in 9 out of the 11 fields. Yield increase by a single fungicide spray ranged from 800 to 2200 kg/ha. A second treatment was cost effective in none of the fields. The interest and limitation of the decision support system for understanding M. graminicola epidemic and for guiding decision on spray timing are discussed.

Rheumatoid arthritis induced by alpha-interferon therapy.

Interferon (IFN) therapy has been used for the treatment of common diseases such as hepatitis C, myeloproliferative disorders, autoimmune diseases and various types of cancer. Given the biological properties of interferon, it is not surprising that there are a larger number of side effects due to its use. Although rheumatoid arthritis (RA) is one of the most common autoimmune diseases found in clinical practice, it does not seem to be frequently related to IFN therapy. We report a 40-year-old female patient who, after high doses of IFN-alpha therapy for malignant melanoma, developed symmetrical polyarthritis, with pain and oedema in small and large joints, associated with prolonged morning stiffness. She had positive rheumatoid factor and DR4 HLA phenotype. She was treated with deflazacort (6 mg/day), chloroquine and NSAIDs, with a partial response. In conclusion, although the development of RA after IFN therapy is a rare event, IFN may work as a 'trigger' for such complication, leading to deregulation in the immune cascade in a person genetically predisposed.

Stabilization of gas-phase noncovalent macromolecular complexes in electrospray mass spectrometry using aqueous triethylammonium bicarbonate buffer.

The use of triethylammonium bicarbonate (TEAB) solution in electrospray mass spectrometry proved to be a very efficient way for studying proteins or noncovalent protein complexes under "nondenaturing" conditions. The low charge states observed in the mass spectra improve the separation of ions arising from macromolecular species of close masses. Moreover, the multiply charged ions generated in a TEAB solution are significantly more stable than those formed under more conventional conditions (for example, with ammonium bicarbonate or acetate solution). The analytical interest of TEAB for the analysis of macromolecular species that can easily dissociate in the gas phase, such as hemoglobin or other macromolecular noncovalent complexes, is demonstrated.

Active glottal closure during anoxic gasping in lambs.

The present study was aimed at assessing laryngeal dynamics and their consequences during anoxic gasping in ketamine-sedated lambs. We first verified that the glottis was closed between gasps during anoxic gasping in seven chronically instrumented lambs, aged 11-15 days. Recording of glottal constrictor muscle electrical activity, subglottal pressure and lung volume, together with endoscopic observation, confirmed the presence of active glottal closure with maintenance of a high lung volume between gasps. Secondly, we tested whether maintenance of a high lung volume between gasps improved autoresuscitation efficiency. Six sedated lambs aged 8-11 days underwent two anoxic runs, including one with an open tracheostomy to prevent maintenance of a high lung volume. Access back to air was allowed for gasping. No significant difference was found in time to eupnea resumption, hemodynamic parameters or arterial blood gases. We conclude that a high lung volume is actively maintained by glottal closure between anoxic gasps in sedated lambs. Further studies are however needed to define the importance of laryngeal dynamics during gasping.

Microvascular anastomosis using histoacryl glue and an intravascular soluble stent.

OBJECTIVE: The purpose of this study was to assess a new technique for microvascular anastomosis on small arteries using Histoacryl glue and an intravascular soluble stent. METHODS: Sprague-Dawley rats were randomly assigned to either of two experimental groups or one control group. The first author (DL, a postgraduate year 4 resident) performed 12 end-to-end anastomoses on rat carotid arteries (1-mm vessel) (group A) using the experimental technique with Histoacryl glue and an intravascular stent. Thirteen microsuture carotid anastomoses performed by the senior author (DD), an experienced microsurgeon, served as control (group C). Permeability was assessed at 1 week for half of the animals and at 6 weeks for the others. Pathologic examination was done on both groups. To evaluate the influence of vessel size on the experimental technique, eight end-to-end anastomoses on rat abdominal aorta (2 mm) (group B) were also done by the first author. Permeability was assessed at 24 to 48 hours for this group. RESULT: In the experimental groups (A and B), two predictable failures (both in group A) were observed. Median anastomosis times were 11 minutes and 7 minutes, respectively. The control group had no failure and a median time of 17 minutes. Pathologic examination revealed more inflammation in group A than in group C. Coagulative necrosis of the arterial wall was observed exclusively in group A. CONCLUSION: This new technique is easy to learn and readily accessible to less experienced microsurgeons. The technique is fast and efficient. The calibre of the vessel has a great influence on ease and speed of the technique. However, histotoxicity of Histoacryl glue was observed. This technique can be valuable for free-tissue transfer in head and neck reconstruction. A less toxic glue would be useful.

An NMR and conformational investigation of the trans-syn cyclobutane photodimers of dUpdT.

Both trans-syn cyclobutane-type photodimers of 2'-deoxyuridylyl (3'-5') thymidine (dUpdT) were formed by deamination of the corresponding trans-syn cyclobutane photodimers of 2'-deoxycytidylyl (3'-5') thymidine (dCpdT) and were examined by 1H-, 13C-, and 31P-nmr spectroscopy. One- and two-dimensional nmr experiments provided a nearly complete assignment of the 1H, 13C, and 31P resonances. Scalar and nuclear Overhauser effect contacts were used to determine the conformation of the deoxyribose rings, exocyclic bonds, cyclobutane rings, and glycosidic linkages. Isomer I (S-type class; CB-; SYN-ANTI) and isomer II (N-type class; CB+; ANTI-SYN) exhibit markedly different conformational features. 31P chemical shifts show that the relative flexibility is dUpdT > isomer II > isomer I. The conformations of these species are very similar to those of other previously examined trans-syn photodimers. Among bipyrimidine photodimers of a given diastereomeric form (i.e., trans-syn I or II), the nmr-derived conformational parameters are nearly invariant, regardless of base substitution pattern. This contrasts with the substituent-dependent variation of cyclobutane ring conformation observed by Kim et al. (Biopolymers, 1993, Vol. 33, pp. 713-721) for an analogous series of cis-syn photodimers. Steric crowding of cyclobutane ring substituents is offered as an explanation for the difference in substituent effects between the families of cis-syn and trans-syn photodimers.

Complete glottic closure during central apnea in lambs.

OBJECTIVE: The objectives of this study were threefold: to document complete glottic closure during artificially induced central apnea in lambs; to unequivocally confirm that thyroarytenoid muscle electrical activity during central apneas in lambs reflects complete glottic closure; and to evaluate the physiologic significance of this phenomenon in artificially induced central apneas in lambs. METHODS: We recorded thyroarytenoid (TA) muscle EMG, subglottic pressure, and lung volume simultaneously with direct endoscopic vision of the glottis from beneath on nine 11- to 15-day-old lambs during artificially induced central apneas. RESULTS: Thirty-eight central apneas were induced. Complete glottic closure was present on 35/38 (92%) of these apneas. Complete glottic closure was always paralleled by thyroarytenoid muscle electromyogram (EMG) activity (35/38). In no instance was TA EMG recorded without complete glottic closure. Moreover, positive subglottic pressure and maintenance of lung volume above functional residual capacity were observed in 27/30 (90%) and 18/19 (95%), respectively, of these apneas where complete glottic closure was present. CONCLUSIONS: Complete glottic closure is present throughout most artificially induced central apneas in lambs. Complete glottic closure is paralleled by TA EMG in artificially induced central apneas. Thyroarytenoid muscle electromyographic activity is a reliable way to document complete glottic closure during apneas, especially in the presence of positive subglottic pressure. These observations suggest that complete glottic closure could be a physiologic mechanism aimed at maintaining higher lung volumes to improve gas exchange during central apneas.

Comparison between enzyme-linked immunosorbent assay, indirect fluorescent antibody and rapid conglutination tests in detecting antibodies against Babesia bovis.

The performance of an enzyme-linked immunosorbent assay (ELISA), an indirect fluorescent antibody test (IFAT) and a rapid conglutination test (RCT) for the detection of antibodies against Babesia bovis, was evaluated with 462 cattle sera from Bahia State; Brazil. The results showed a concordance of 96.6% between the ELISA and IFAT, 90.5% between the ELISA and RCT, and 91.8% between the IFAT and RCT. Although the prevalence rates determined by ELISA (97.2%) and IFAT (96.8%) were higher than that indicated by the RCT (92.9%), performances of the three serological tests were very similar and characterized the region studied as enzootically stable to B. bovis.

Patience is a virtue.

Family members learn a lot about intervention while caring for Alzheimer's patients. Nutrition and safety are two aspects of Alzheimer's care that family caregivers can influence on their own, day to day.

An NMR and conformational investigation of the trans-syn cyclobutane photodimers of dTpdU.

Two trans-syn cyclobutane photodimers of thymidylyl (3'-5') deoxyuridine were formed by deamination of the corresponding trans-syn cyclobutane photodimers of thymidylyl (3'-5') deoxycytidine and were examined by 1H-, 13C-, and 31P-nmr spectroscopy. Correlation spectroscopy, nuclear Overhauser enhancement spectroscopy, and one-dimensional heterodecoupling experiments allowed a more complete assignment of the 1H spectra, compared with previous reports by Koning et al. [(1991) European Journal of Biochemistry, Vol. 195, pp. 29-40] and Liu and Yang [(1978) Biochemistry, Vol. 17, pp. 4865-4876]. Deoxyribose ring conformations were calculated from 1H coupling constants by pseudorotational analysis, and rotamer distributions of exocyclic bonds were calculated from the observed homonuclear and heteronuclear coupling constants. The cyclobutane ring configuration (CB) of each isomer was identified, using arguments based upon observed scalar and dipolar couplings. Glycosidic bond conformation was ascertained from nuclear Overhauser enhancements observed between base and deoxyribose protons. Isomer I (S-type class; CB-; SYN-ANTI) and isomer II (N-type class; CB+; ANTI-SYN) exhibit markedly different conformational features. 31P chemical shifts and exocyclic bond rotamer distributions indicate diminished backbone flexibility for both photoproducts relative to parent thymidylyl (3'-5') deoxyuridine. Isomer I (SYN-ANTI) is particularly rigid, while isomer II (ANTI-SYN) maintains some flexibility. Also, 13C spectra were acquired and assigned unequivocally with the aid of short- and long-range two-dimensional heteronuclear shift correlation experiments.