Distribution of CAG repeat size in the dentatorubral and pallidoluysian atrophy (DRPLA) gene in a normal population in Taiwan

Dentatorubral and pallidoluysian atrophy (DRPLA) is an autosomal dominant neurodegenerative disorder with expansion of trinucleotide CAG repeats in the coding region of the gene. Expansion of the repeat tract beyond the normal range produces gene products with extended polyglutamine tracts. In this study, we analyzed the distribution of the CAG repeats in the DRPLA alleles in a normal Taiwanese population. We observed 15 different alleles and found that the range of the CAG repeat number was from 7-21. The most frequent allele contained 15 CAG repeats that represented 20% of the total analyzed alleles, followed by the 17 repeats (15.8%). The heterozygosity rate of this locus was 88%. Twelve parents-to-children transmissions of the DRPLA alleles in a Machado-Joseph disease family appeared to be normal without any alteration of the CAG repeat numbers. Phenotypes of DRPLA overlapped those of autosomal dominant cerebellar ataxia (ADCA). In order to identify DRPLA patients in Taiwan, we screened six autosomal dominant cerebellar ataxia patients without expansion in known spinocerebellar ataxia genes. All six patients had the repeat numbers within the normal range; thus, the possibility of DRPLA could be excluded.

Filleted toe flap for chronic forefoot ulcer reconstruction

Chronic plantar and dorsal forefoot ulcer may result from injury, structural deformity, and abnormal sensation or circulation. It is not uncommon that the distal portion of the affected toes is deficient functionally in these patients. A filleted toe flap from the expendable functionless toe can provide a durable, stable, and sensate skin flap of 4 to 5.5 cm for coverage of the forefoot defect. In this report, five cases of dorsal forefoot defects and four cases of plantar forefoot defects due to ischemia (N = 3), trophic change (N = 2), and diabetes (N = 4) were treated with filleted toe flaps. One flap failed due to postoperative deep infection. The other eight filleted toe flaps survived but 2 patients underwent secondary amputations 7 months and 2 two years later because of secondary diabetic foot infections.

Subjective memory complaint in relation to cognitive performance and depression: a longitudinal study of a rural Chinese population

OBJECTIVES

To examine the associations of subjective memory complaint (SMC) in old age with (a) objective test performance, (b) past and subsequent cognitive decline, and (c) depression.

DESIGN

A group of community residents were examined twice during a 3-year period.

SETTING

Two townships on a rural Chinese islet.

PARTICIPANTS

A total of 543 men and women aged 65 years and older.

MEASUREMENTS

During each examination, neurologists interviewed and examined all participants for dementia and asked the question, "Do you have trouble with your memory?" In addition, research assistants administered (a) the Cognitive Abilities Screening Instrument (CASI) to assess cognitive abilities, including long-term memory (LTM) and short-term memory (STM), and (b) the Geriatric Depression Scale-Short Version (GDS-S) to assess symptoms of depression.

RESULTS

At each examination, almost half of the subjects acknowledged having trouble with their memory (the SMC+ group). At both examinations, the SMC+ group scored significantly lower on the CASI and significantly higher on the GDS-S than the SMC- group. However, the presence of SMC was not associated with faster cognitive decline over the past or subsequent 3 years. There were no consistent associations between SMC and the demographic variables of age, gender, and education at the two examinations. Logistic regression analysis showed that SMC was associated with poorer memory test scores after controlling for gender, age, education, and depression.

CONCLUSIONS

SMC was associated with poorer objective memory performance even after controlling the effect of depression and demographic data, but SMC did not predict faster cognitive decline or dementia over 3 years.

Autonomous induction of proliferation, JNK and NF-alphaB activation in primary resting T cells by mobilized CD28

Induction of proliferation in primary resting T cells requires engagement of both the antigen-specific TCR and the co-stimulatory receptor CD28. Here we report that CD28 functions as an autonomous mitogenic receptor which is mobilized by TCR signaling through cytoskeletal rearrangement. Shortcutting of TCR-dependent CD28 recruitment by stimulation with monoclonal antibodies specific for mobilized CD28 results in maximum proliferation and IL-2 secretion in primary resting T cells without activation of ZAP-70, a central component of the TCR's signal transduction machinery. Engagement of mobilized CD28 fully activates the c-Jun N-terminal kinase cascade and translocation of NF-alphaB, two key targets of signal integration in co-stimulation. We propose a two-step activation model for co-stimulation in primary resting T cells in which antigen recognition recruits co-stimulatory receptors which then autonomously transduce signals promoting T cell proliferation.

A novel cytotoxic C-methylated biflavone from the stem of Cephalotaxus wilsoniana

Bioassay-directed fractionation of an ethanolic extract of Cephalotaxus wilsoniana has resulted in the isolation of a novel C-methylated biflavone, taiwanhomoflavone-A (1). Its structure was elucidated on the basis of spectroscopic analysis. Taiwanhomoflavone-A is cytotoxic with ED50 values of 3.4, 1.0, 2.0 and 2.5 microg/ml, respectively, against KB epidermoid carcinoma of nasopharynx, COLO-205 colon carcinoma, Hepa-3B hepatoma, and Hela cervix tumor cells.

Substrate-induced exposure of an energy-coupling motif of a membrane transporter

BtuB is an outer membrane protein responsible for the uptake of vitamin B12 by Escherichia coli. It belongs to a family of bacterial transport proteins that derive energy for transport by coupling to the trans-periplasmic energy-coupling protein TonB. Using site-directed spin labeling and EPR we investigated the structure and substrate-induced changes in the TonB box, a highly conserved region in all TonB dependent transporters that may couple to TonB. In the absence of substrate, the line widths and collision parameters from EPR are consistent with this domain existing in a structured helical conformation that contacts the barrel of the transporter. Addition of substrate converts this segment into an extended structure that is highly dynamic, disordered and probably extended into the periplasm. This structural change demonstrates that the TonB box cycles between sequestered and accessible states in a substrate-dependent fashion. In a transport defective mutant of BtuB, this conformational cycle is disrupted and the TonB box appears to be extended even in the absence of substrate. These data suggest that the TonB box extends into the periplasm and interacts with TonB only in

Immediate Camitz opponensplasty in acute thenar muscle injury

Thenar function impairment or destruction is not uncommon in hand crush injury or thumb avulsion injury. Although complete evaluation of thenar muscle function is difficult during an emergency setting because of skeletal instability and pain, if left untreated the injured hand may result in deficiency of opposition and may require secondary reconstruction. When the palmaris longus tendon is available from the open wound, a Camitz opponensplasty can be performed in the emergency operation setting even as an augmentation procedure for opposition if there is any suspicion of thenar muscle impairment. Seven patients with such injuries who underwent immediate Camitz opponensplasty were assessed to have an 80% angle of separation, a 90% angle of circumduction, and an 88% Kapandji test of the normal opposite hand. An emergency Camitz procedure provided a reliable, immediate one-stage reconstruction of thenar function.

A prospective trial of lansoprazole triple therapy for pediatric Helicobacter pylori infection

BACKGROUND

Triple therapy with a proton-pump inhibitor and two antibiotics is widely used in the treatment of Helicobacter pylori infection in adults. Experience with such therapy in the pediatric population is limited. This was a prospective, nonrandomized, open-label trial to evaluate safety and efficacy of a combination of lansoprazole, clarithromycin, and amoxicillin in symptomatic children with H. pylori infection.

METHODS

Children with H. pylori gastritis diagnosed by endoscopy performed for persistent nausea, vomiting, recurrent abdominal pain, and diarrhea with consistent histology were treated with the regimen of 0.45 mg/kg per day lansoprazole divided into two doses (maximum dose, 15 mg twice daily), amoxicillin 40 mg/kg per day in two doses (maximum dose, 1.0 g twice daily), and 250 mg clarithromycin twice daily (<10 years old) or 500 mg twice daily (>10 years old) for 2 weeks. Pre- and posttreatment endoscopic biopsy specimens were graded for the severity of gastritis and H. pylori density by a blinded pathologist. A questionnaire for assessing the severity of symptoms at the time of initial and second endoscopy were completed by patient and/or parent.

RESULTS

Thirty-two children (age range, 1-25 years; mean age, 11 years; 19 females, 13 males) were treated with this regimen during an 18-month period. H. pylori organisms with varying grades of gastritis were present in tissue specimens of all patients. Only 28 children had follow-up endoscopy, which showed eradication of H. pylori in 15 (54%) children. Histologic symptoms of gastritis improved after therapy in the whole group. Overall, symptoms of vomiting, abdominal pain, diarrhea, anorexia, and halitosis significantly improved (P < 0.05). Minor adverse effects of therapy occurred in 25% of patients.

CONCLUSIONS

Symptoms, histologic, and endoscopic findings improved after triple therapy in children with H. pylori gastritis; however, eradication of bacteria was achieved in only 56% of children.

On-line identification of depurinating DNA adducts in human urine by capillary electrophoresis--fluorescence line narrowing spectroscopy

The benzo[a]pyrene (BP)-derived 7-(benzo[a]pyren-6-yl)guanine (BP-6-N7Gua) depurinating one-electron oxidation adduct was identified in the urine extracts of coal-smoke-exposed humans for the first time. Urine samples were prepared by solid-phase extraction and reversed-phase high-performance liquid chromatography. Subsequently, the BP-6-N7Gua adduct was identified on-line with capillary electrophoresis-- fluorescence line narrowing spectroscopy (CE-FLNS) at 4.2 K. The daily excretion of BP-6-N7Gua in human urine of individuals exposed to coal smoke was approximately 226 pmol per micromol of creatinine. Due to the high level of excretion we propose that BP-6-N7Gua adducts found in urine could serve as effective biomarkers for risk assessment of BP exposure. The results demonstrate that CE-FLNS allows for on-line separation and DNA adducts identification in complex fluid extracts.

Chromosomal damage in long-term residents of houses contaminated with cobalt-60

Chromosomal translocations in people who have lived in houses contaminated with radiation were substantially raised compared with controls. Retrospective biological dosimetry indicated cumulative exposures less than 1.0 Gy, which were lower than values derived from physical measurements.

Localization of unconventional myosins V and VI in neuronal growth cones

Class V and VI myosins, two of the six known classes of actin-based motor genes expressed in vertebrate brain (Class I, II, V, VI, IX, and XV), have been suggested to be organelle motors. In this report, the neuronal expression and subcellular localization of chicken brain myosin V and myosin VI is examined. Both myosins are expressed in brain during embryogenesis. In cultured dorsal root ganglion (DRG) neurons, immunolocalization of myosin V and myosin VI revealed a similar distribution for these two myosins. Both are present within cell bodies, neurites and growth cones. Both of these myosins exhibit punctate labeling patterns that are found in the same subcellular region as microtubules in growth cone central domains. In peripheral growth cone domains, where individual puncta are more readily resolved, we observe a similar number of myosin V and myosin VI puncta. However, less than 20% of myosin V and myosin VI puncta colocalize with each other in the peripheral domains. After live cell extraction, punctate staining of myosin V and myosin VI is reduced in peripheral domains. However, we do not detect such changes in the central domains, suggesting that these myosins are associated with cytoskeletal/organelle structures. In peripheral growth cone domains myosin VI exhibits a higher extractability than myosin V. This difference between myosin V and VI was also found in a biochemical growth cone particle preparation from brain, suggesting that a significant portion of these two motors has a distinct subcellular distribution.

Rapidly progressive fibrosing interstitial nephritis associated with Chinese herbal drugs

Rapidly progressive fibrosing interstitial nephritis after a slimming regimen containing aristolochic acid has been identified as Chinese herbs nephropathy (CHNP). From 1995 to 1998, we observed 12 Chinese people from different areas of Taiwan who underwent renal biopsy for unexplained renal failure. Medical history gave no clue to the causes of impaired renal function except for the ingestion of traditional Chinese herbs. Although these patients ingested herbal drugs from various sources for different purposes, their renal biopsy samples showed amazingly similar histological findings, with extensive hypocellular interstitial fibrosis and atrophy and loss of tubules in all cases. Glomeruli were apparently intact. They also had similar clinical features, such as normal or mildly elevated blood pressure, early and severe anemia, low-grade proteinuria, glycosuria, and insignificant urinary sediments. Renal function deteriorated rapidly in most patients despite discontinuation of the herbal medicines. Seven patients underwent dialysis, and the remainder experienced slowly progressive renal failure. Bladder carcinoma was found in one patient. Morphologically and clinically, the nephropathy in our patients was similar to CHNP, reported in Belgium. Because of the complexity and unknown types of herbs used in different clinical situations, unidentified phytotoxins other than aristolochic acid might be responsible for this unique disease entity. We conclude that the relation of this nephropathy to the consumption of Chinese herbs is striking. Using uncontrolled herbal remedies carries a high risk for developing interstitial renal fibrosis and urothelial malignancy.

Widely split latissimus dorsi muscle flaps for reconstruction of long soft-tissue defects in lower extremities

Although the latissimus dorsi is one of the largest and longest muscles in the human body, it is still sometimes inadequate for reconstruction of a soft-tissue defect of extensive length and dimension. Eight patients with such lower limb defects were treated with latissimus dorsi muscles split into two hemiflaps sequentially linked, one after the other like a chain. Six transfers were completely successful, one required reexploration for arterial occlusion, and two hemiflaps had a partial loss that could be managed by touching up the skin graft. The average split sequential-link muscle was 42 cm in length. Although two patients had a partial loss, we consider that the widely split single latissimus dorsi muscle can still be used reliably to reconstruct a long slender defect, or two separate, longitudinally located, medium-sized defects in the same leg.

Conventional versus endoscopic free gracilis muscle harvest

Compared with conventional techniques, the endoscopically assisted harvest of free tissue has advantages such as minimal interference with cosmesis and reduced donor-site morbidity. However, the procedure also requires training and has an extensive learning period. In this series of 22 patients, the initial gracilis muscle flaps were harvested using a conventional method; the subsequent flaps were harvested with the aid of endoscopic instrumentation. Endoscopically assisted gracilis muscle harvest in 16 patients was compared with open method harvest in six patients. The endoscopically assisted group had an average incision length of 6.5 cm; that of the conventional group was 15.5 cm. There was one reexploration in the endoscopically assisted group, but all flaps were transferred successfully. Using this minimally invasive technique of vascular and muscular dissection, assisted by endoscopic instruments designed for distal muscle dissection and transection, the gracilis muscles can be harvested within 40 minutes. We consider endoscopically assisted harvest of free gracilis muscle to be safe, relatively simple, and cost-effective.

Involvement of protein kinase C-gamma in IL-1beta-induced cyclooxygenase-2 expression in human pulmonary epithelial cells

The signaling pathway of protein kinase C (PKC) is known to play a role in mediating the action of various cytokines. Here we examined the signal transduction pathway of PKC activation and the role of PKC isoforms in interleukin-1beta (IL-1beta)-mediated cyclooxygenase-2 (COX-2) expression in human pulmonary epithelial cell line (A549). The tyrosine kinase inhibitors (genistein and tyrphostin AG126) and phosphatidylcholine-phospholipase C inhibitor (D-609) prevented IL-1beta-induced prostaglandin E(2) (PGE(2)) release and COX-2 expression, whereas U-73122 (a phosphatidylinositol-phospholipase C inhibitor) and propranolol (a phosphatidate phosphohydrolase inhibitor) had no effect. The PKC inhibitors (Go 6976 and Ro 31-8220) and NF-kappaB inhibitor, pyrrolidine dithiocarbamate, also attenuated IL-1beta-induced PGE(2) release and COX-2 expression. Western blot analysis using PKC isoenzyme-specific antibodies indicated that A549 cells expressed PKC-alpha, -gamma, -iota, -lambda, -zeta, and -micro. IL-1beta caused the translocation of PKC-gamma but not other isoforms from cytosol to the membrane fraction. Moreover, the translocation of PKC-gamma was inhibited by genistein or D-609, but not by U-73122. IL-1beta caused the translocation of p65 NF-kappaB from cytosol to the nucleus as well as the degradation of IkappaB-alpha in cytosol. Furthermore, the translocation of p65 NF-kappaB was inhibited by genistein, Go 6976, Ro 31-8220, or pyrrolidine dithiocarbamate. These results indicate that in human pulmonary epithelial cells, IL-1beta might activate phosphatidylcholine-phospholipase C through an upstream tyrosine phosphorylation to elicit PKC activation, which in turn initiates NF-kappaB activation, and finally induces COX-2 expression and PGE(2) release. Of the PKC isoforms present in A549 cells, only activation of PKC-gamma is involved in regulating IL-1beta-induced responses.

Spontaneous resolution of internal jugular vein thrombosis in a Salmonella neck abscess patient

This article describes a rare case of Salmonella neck abscess complicated by internal jugular vein thrombosis in a 51-year-old patient with previously undiagnosed diabetes. The patient was discharged without any complications after a combination of medical and surgical treatment. Also discussed here are the clinical manifestations, imaging findings, and spontaneous resolution of the internal jugular vein thrombosis. Being immunocompromised is a critical predisposing factor for Salmonella neck abscess. Patient recovery is largely determined by proper incision, drainage of pus and adequate intravenous antibiotics according to bacterial sensitivity tests. Detection of an internal jugular vein thrombosis does not signify a poor prognosis. Spontaneous resolution of thrombosis is encountered after treating the infection.

A randomized, prospective study to evaluate the efficacy and acceptance of three bowel preparations for colonoscopy in children

OBJECTIVE

We performed a prospective, randomized, single-blind study in children undergoing colonoscopy to evaluate the acceptance and efficacy of three different bowel preparations.

METHODS

Seventy patients (ages 3-20 yr, 38 males) were randomly assigned to one of the three study preparations: Magnesium citrate with X-prep and clear liquid diet for 2 days (group A); Dulcolax for 2 days and Fleet enema without dietary restriction (group B); and Golytely 20 ml/kg (up to 1 L) per hour for 4 h with clear liquid diet for 1 day (group C). Endoscopists blinded to bowel preparation graded the adequacy of colon cleansing. The preparations were rated by patients for tolerance, willingness to retake them, adverse effects, and compliance.

RESULTS

Data analysis using Fisher exact test and trend test showed that colon cleansing in groups A and C was superior to that in group B (p < 0.0001) and better in group C than A (p < 0.075). Overall tolerance and compliance were significantly better for groups A and B than group C (p < 0.003), but not different between A and B. More of group B patients were willing to retake the preparation than in group C (p < 0.002) and group A (p < 0.05), but this was not different between groups A and C. Adverse effects were reported more frequently by patients in group C than in groups A and B (p < 0.01).

CONCLUSIONS

Although the least well tolerated, Golytely provided the best cleansing. Dulcolax without dietary restriction provided unsatisfactory colon cleansing. Magnesium citrate with X-prep was acceptable and provided good cleansing.

Use of the hospital anxiety and depression scale as a screening tool for patients with headache

BACKGROUND

The Hospital Anxiety and Depression Scale (HADS) is becoming widely used in medical settings to screen for anxiety or depressive disorders. It has been shown to be a good screening instrument in different ethnic and disease populations. The objective of this study was to evaluate the validity and reliability of HADS in patients with headache at a headache clinic.

METHODS

Consecutive new patients to a headache clinic at the Taipei Veterans General Hospital from September to December, 1998, were recruited in the study. The participants completed the HADS questionnaire and underwent a psychiatric semistructured interview according to the Diagnostic and Statistical Manual (4th revision). The reliability and validity of the HADS were evaluated with respect to headache.

RESULTS

A total of 62 patients (21 men, 41 women) completed the study. The HADS had a good internal consistency when applied to patients suffering from headache, with a Cronbach's alpha coefficient of 0.84 and a split-half reliability of 0.84. Factor analysis in this sample revealed four factors: anxiety, depression, panic and somatic factors. A total of 48 patients (77%) had a psychiatric diagnosis. The frequency of depressive disorders was 57% and anxiety disorders 31%. A total HADS score of 10 or more was the optimal cut-off point for depressive disorders. The sensitivity was 85.7%, and the specificity 33.3%. A total score of at least 13 was the optimal cut-off point for anxiety disorder. The sensitivity was 84.2%, while the specificity was 41.9%.

CONCLUSIONS

Depression and anxiety were quite common among patients with headache in a headache clinic. The HADS can be used as a screening instrument for depressive and anxiety disorders. Because of the low specificity, the HADS should not be used solely as an indicator of psychiatric comorbidity among patients with headache in a headache clinic. This is the first study that verifies the use of the HADS as a psychiatric screening tool in patients with headache by comparing the scores of the HADS with psychiatric diagnoses.

Strategies in multiple toe transplantation for bilateral type II metacarpal hand reconstruction

Multiple toe transplantation has been established as an effective means of restoring prehensile function in the metacarpal hand. The attainable outcome, however, must be weighed against potential donor site morbidity. Restoration of prehensile function in bilateral type II metacarpal hands can be achieved by reconstructing three opposable digits in the dominant hand and two opposable digits in the nondominant hand. This article outlines the strategy for optimizing functional outcome and discusses the rationale behind toe selection to reduce donor morbidity.

Comparison of patient-controlled analgesia (PCA) with tramadol or morphine

PURPOSE

To compared the clinical efficacy of tramadol and morphine using a patient-controlled analgesia (PCA) delivery system.

METHODS

In a prospective, randomized, double blind study, we evaluated 80 adult patients scheduled for elective hip or knee arthroplasty with general inhalational anesthesia. When patients complained of pain in the recovery room, patients were randomized to receive either tramadol or morphine by titration in 30 min to achieve analgesia (VAS < or =4). Equivalent volumes containing either 30 mg x ml(-1) tramadol or 1 mg x ml(-1) morphine were used for PCA with a lockout interval of 10 min. The patients were followed six-hourly for 48 hr for VAS, satisfaction rate, analgesic dose, and side effects.

RESULTS

Patients obtained adequate analgesia with either drug. More patients had very good satisfaction scores in the morphine group in the recovery room (43% vs. 23%, P<0.05) and at 24 hr (40% vs. 20%, P<0.05) than those in the tramadol group. More nausea was evident in the tramadol group (48% vs. 11% in recovery room and 28% vs. 12% in 24 hr, P<0.05) than in the morphine group. Vomiting was also more (28% vs. 5% in recovery room, 15% vs. 3% in 24 hr, P<0.05). Morphine produced more sleepiness (45% vs. 23% in recovery room, P<0.05 and 35% vs. 15% in 24 hr, P<0.05).

CONCLUSION

Tramadol PCA can provide effective analgesia following major orthopedic surgery provided sufficiently high doses are given for loading and by patient demand. However, the incidence of nausea/vomiting is also higher causing decreased satisfaction.

Arginine methylation of a glycine and arginine rich peptide derived from sequences of human FMRP and fibrillarin

N-methylation at the arginine residues in RNA binding proteins with the arginine and glycine rich RGG box has been identified. We show that a synthetic peptide R9 (GGRGRGGGF) with the RGG sequence present in human fibrillarin and fragile X mental retardation protein (FMRP) can be specifically methylated by rat brain extract. A control peptide K9 with all arginines replaced by lysines could not be methylated under the same conditions, indicating that the arginines in the peptide were the methylation sites. A novel missense mutation, which changes an arginine to a histidine in the RGG box region of FMRP in a typical fragile X patient, has been identified. A synthetic peptide with this Arg-->His (GGRGHGGGF) substitution was methylated by our in vitro methylation system to a much less extent. Amino acid analysis of the methylated R9 peptide identified the methylated amino acid as monomethylarginine. The R9 peptide may be useful for further studies on arginine methylation in RGG proteins.

Targeting of aminopeptidase N to bile canaliculi correlates with secretory activities of the developing canalicular domain

We have used human hepatoma cell lines as an in vitro model to study the development of hepatic bile canaliculi (BC). Well-differentiated hepatoma cells cultured for 72 hours could develop characteristic spheroid structures at sites of cell-cell contact that contained tight junctions and various membrane protein markers, resembling BC found in vivo. Intact cytoskeleton was essential for this differentiation process. In the coculture experiments in which cells of different origins were populated together, BC only formed between hepatic cells and preferentially among well-differentiated cells. Poorly differentiated hepatoma cells never formed BC among themselves, but could be induced to undergo canalicular differentiation by interacting with well-differentiated cells. During BC morphogenesis, integral canalicular membrane proteins were gradually delivered and accumulated at the developing BC. Among them, targeting of aminopeptidase N (APN) seemed to correlate with activation of certain secretory functions. Specifically, only APN-positive BC supported excretion of fluorescein diacetate (FDA) and 70-kd dextran, but had no relationship with secretion of horseradish peroxidase (HRP). Targeting of another BC protein, dipeptidyl peptidase IV (DPPIV), on the other hand, bore no association with any secretory activity examined. In addition, inhibition of enzymatic activity of APN could perturb canalicular differentiation without affecting cell proliferation. Our results suggest that targeting of APN proteins may reflect or even play an important role in the development and functional maturation of the canalicular structures.

Structure elucidation of the adducts formed by fjord region Dibenzo[a,l]pyrene-11,12-dihydrodiol 13,14-epoxides with deoxyguanosine

(+/-)-anti-Dibenzo[a,l]pyrene-11,12-dihydrodiol 13,14-epoxide {(+/-)-anti-DB[a,l]PDE} was reacted with deoxyguanosine (dG) in dimethylformamide at 100 degrees C for 30 min, and two sets of adducts were isolated: a mixture of (+/-)-anti-cis- & -trans-N(2)dG (43%) and a mixture of (+/-)-anti-cis- & -trans-N7Gua (45%). Both are mixtures of four stereoisomers that cannot be separated by HPLC. Similarly, (+/-)-syn-DB[a,l]PDE was reacted with dG under the same conditions, and (+/-)-syn-cis- & -trans-N(2)dG (38%) and (+/-)-syn-cis- & -trans-N7Gua (59%) were obtained. The structures of the adducts were determined by a combination of NMR and fast atom bombardment mass spectrometry. By reacting (-)-anti-DB[a,l]PDE or (+)-syn-DB[a,l]PDE with dG under the same conditions, however, optically pure N(2)dG and N7Gua isomers were obtained: (-)-anti-cis-N(2)dG (12%), (-)-anti-trans-N(2)dG (17%), (-)-anti-trans-N7Gua (43%), (+)-syn-cis-N(2)dG (7%), (+)-syn-trans-N(2)dG (3%), (+)-syn-cis-N7Gua (36%), and (+)-syn-trans-N7Gua (22%). The structures of the optically pure adducts were assigned by NMR. syn- and anti-DB[a,l]PDE-N(2)dG adducts can be distinguished by fluorescence line-narrowing spectroscopy (FLNS). Moreover, distinction between cis- and trans-stereochemistry of the adducts is also straightforward by FLNS, because the FLN spectra for the four DB[a,l]PDE-N(2)dG adducts, anti-cis, anti-trans, syn-cis, and syn-trans, are spectroscopically unique.