Search

The clinical conditions of critically ill patients are highly heterogeneous; therefore, nutrient requirements should be personalized based on the patient's nutritional status. However, nutritional status is not always considered when evaluating a patient's nutritional therapy in the medical intensive care unit (ICU). We conducted a retrospective cross-sectional study to assess the effect of ICU patients' nutrition risk status on the association between energy intake and clinical outcomes (i.e., hospital, 14-day and 28-day mortality). The nutrition risk of critically ill patients was classified as either high- or low-nutrition risk using the modified Nutrition Risk in the Critically Ill score. There were 559 (75.3%) patients in the high nutrition risk group, while 183 patients were in the low nutrition risk group. Higher mean energy intake was associated with lower hospital, 14-day and 28-day mortality rates in patients with high nutrition risk; while there were no significant associations between mean energy intake and clinical outcomes in patients with low nutrition risk. Further examination of the association between amount of energy intake and clinical outcomes showed that patients with high nutrition risk who consumed at least 800 kcal/day had significantly lower hospital, 14-day and 28-day mortality rates. Although patients with low nutrition risk did not benefit from high energy intake, patients with high nutrition risk are suggested to consume at least 800 kcal/day in order to reduce their mortality rate in the medical ICU.

Background: Patients with polycystic kidney disease (PKD) might have a risk of cardiovascular diseases because several cardiovascular risk factors are occasionally associated with PKD patients. Data on the association between PKD and the risk of cardiovascular events, including acute coronary syndrome (ACS), stroke, and congestive heart failure (CHF), are scant. Methods: Patients aged ≥20 years who were newly diagnosed with PKD (International Classification of Diseases, Ninth Revision, Clinical Modification codes 753.12 and 753.13) between 2000 and 2011 were selected as a PKD cohort (N = 5157). The association between PKD and cardiovascular events was analyzed. Results: We randomly selected a comparison cohort of people without PKD, who were frequency-matched by sex, age, and index date of diagnosis. At the end of 2011, the PKD cohort had a 1.40-fold greater incidence of ACS compared with the comparison cohort (8.59 vs. 6.17 per 1000 person-years), in addition to a 1.40-fold greater incidence of stroke, a 1.49-fold greater incidence of CHF, and a 1.64-fold greater incidence of mortality. Conclusions: This retrospective cohort study shows that patients with PKD have an increased risk of cardiovascular events including ACS, stroke, and CHF as well as mortality, particularly in younger patients. Early identification is necessary to attenuate the risk of cardiovascular complications in patients with PKD.

Background: Claims data are currently widely used as source data in asthma studies. However, the insufficient information in claims data related to level of asthma severity may negatively impact study findings. The present study develops and validates an asthma severity classification model that uses medication utilization in Taiwan National Health Insurance claims data., Methods: The National Health Insurance Research Database was used for the years 2006-2012 and included a total of 7221 patients newly diagnosed with asthma in 2007 for model development and in 2008 for model validation. The medication utilization of patients during the first year after the index date was used to classify level of severity, and the acute exacerbation of asthma during the second through fourth years after the index date was used as the outcome variable. Three models were developed, with subjects classified into four, three, and two groups, respectively. The area under the receiver operating characteristic curve (AUC) and the Kaplan-Meier survival curve were used to compare the performances of the classification models., Results: In development data, the distribution of subjects and acute exacerbation rate among the stage 1 to stage 4 were: 62.71%, 5.54%, 22.79%, and 8.96%, and 8.17%, 9.55%, 11.97%, and 14.91%, respectively. The results also showed the higher severity groups to be more prone to being prescribed oral corticosteroids for asthma control, while lower severity groups were more likely to be prescribed short-acting medication and inhaled corticosteroid treatment. Furthermore, the results of survival analysis showed two-group classification was recommended and yield moderate performance (AUC = 0.671). In validation data, the distribution of subjects, acute exacerbation rates, and medication uses among stages were similar to those in development data, and the results of survival analysis were also the same., Conclusions: Understanding asthma severity is critical to conducting effective, scholarly research on asthma, which currently uses claims data as a primary data source. The model developed in the present study not only overcomes a gap in the current literature but also provides an opportunity to improve the validity and quality of claims-data-based asthma studies.

Paeonol is a key phenolic compound in the root bark of Moutan Cortex Radicis that has been used in traditional Chinese Medicine to ameliorate inflammation. A series of aminothiazole-paeonol derivatives (APDs) were synthesized in this work and subjected to preliminary evaluation in cells followed by verification in animals. Quantification of monocyte chemotactic protein-1 (MCP-1) and interleukin-6 (IL-6) in culture media of LPS-activated A549 cells, a lung epithelial adenocarcinoma cell line, were used to investigate the anti-inflammatory capability of APDs. ALI-bearing rats were employed to verify therapeutic efficacy of APDs according to observations of total cells, protein amounts, MCP-1 and IL-6 in bronchoalveolar lavage fluid (BALF). Histopathological examinations of lung tissues were consequently applied for validation of APDs. Among these compounds, 2-(2-aminothiazol-4-yl)-5-methoxyphenol ( 4 ) had the most potent activity, showing comparable inhibition of MCP-1/IL-6 and superior elimination of neutrophil infiltration and protein exudation in lungs compared to others as well as dexamethasone. This study demonstrated a comprehensive strategy to evaluate APDs through integration of cell-based screening and animal-based verification. In order to fulfill unmet needs of treating acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), APDs introduced in this work could be promising lead compounds to develop high potent anti-inflammation agents., Competing Interests: The authors declare no conflict of interest.

Objectives: Carthamus tinctorius L. (CT) or safflower is widely used in traditional Chinese medicine. This study investigated the effects of CT extract (CTE) on ischemia-reperfusion (I/R) brain injury and elucidated the underlying mechanism., Materials and Methods: The I/R model was conducted by occlusion of both common carotid arteries and right middle cerebral artery for 90 min followed by 24 hr reperfusion in Sprague-Dawley rats. CTE (0.2-0.6 g/kg) was administered intraperitoneally before and during ischemia, and during reperfusion period. The cerebral infarction area, neurological deficit scores, free radicals (lucigenin chemiluminescence counts) and pro-inflammatory cytokines expression were measured., Results: Pretreatment and treatment with CTE significantly reduced the cerebral infarction area and neurological deficits. CTE (0.4 g/kg) also reduced blood levels of free radicals and expression of tumor necrosis factor-α and interleukin-1β in the cerebral infarction area., Conclusion: The reduction in I/R cerebral infarction caused by CTE is possibly associated with its antioxidation and anti-inflammatory properties.

The bifunctional enzyme UDP-GlcNAc 2-epimerase/ManNAc kinase (GNE) plays a key role in sialic acid production. It is different from the non-hydrolyzing enzymes for bacterial cell wall biosynthesis, and it is feed-back inhibited by the downstream product CMP-Neu5Ac. Here the complex crystal structure of the N-terminal epimerase part of human GNE shows a tetramer in which UDP binds to the active site and CMP-Neu5Ac binds to the dimer-dimer interface. The enzyme is locked in a tightly closed conformation. By comparing the UDP-binding modes of the non-hydrolyzing and hydrolyzing UDP-GlcNAc epimerases, we propose a possible explanation for the mechanistic difference. While the epimerization reactions of both enzymes are similar, Arg113 and Ser302 of GNE are likely involved in product hydrolysis. On the other hand, the CMP-Neu5Ac binding mode clearly elucidates why mutations in Arg263 and Arg266 can cause sialuria. Moreover, full-length modelling suggests a channel for ManNAc trafficking within the bifunctional enzyme.

To evaluate whether the use of traditional Chinese medicine (TCM; zhōng yī) influences symptoms or functional outcomes in patients with osteoarthritis (OA) of the knee ( xī guān jié yán). A systematic review of randomized control trials was conducted. Searches for studies in PubMed that were performed between 1965 and August 2013, and retrieved studies were subjected to reference screening. The types of studies included in our review were 1) placebo-based or comparative studies; 2) open label, single-blinded or double-blinded studies; 3) studies evaluating the efficacy of TCM for treating OA of the knee; and 4) studies evaluating only TCM or combination preparations. Trials were conducted with participants over 18 years of age with knee pain and at least three of the following characteristics: 1) an age greater than 50 years; 2) morning stiffness lasting for fewer than 30 min; 3) a crackling or grating sensation; 4) bony tenderness of the knee; 5) bony enlargement of the knee; or 6) no detectable warmth of the joint to the touch. Studies were rated for risk of bias and graded for quality. After screening, 104 studies that satisfied the eligibility requirements were identified, and only 18 randomized control trials were included in the quantitative and qualitative synthesis. Upon review, we found "moderate-quality" evidence of effects from acupuncture ( zhēn jiǔ) on pain, which was measured using a visual analogue scale, and physical function, which was measured using qigong ( qì gōng) with motion. "Low-quality" evidence was found regarding the effects of acupuncture on physical function, and no evidence was found regarding the effects of herbal medicine on pain or physical function. Herbal patches ( yào bù) appeared to affect pain and physical and function, but these effects were not found to be significant. The initial findings included in this review suggest that acupuncture is a promising intervention according to the primary outcome measure, pain, and qigong with motion is an effective method for treating physical function. However, according to the Grades of Recommendation, Assessment, Development, and Evaluation criteria, only moderate-quality evidence was found in these studies. Further rigorous studies are warranted to investigate the application of TCM in treating OA of knee.

Streptosporangium sibiricum SibL catalyzes the methyl transfer from S-adenosylmethionine (SAM) to 3-hydroxykynurenine (3-HK) to produce S-adenosylhomocysteine (SAH) and 3-hydroxy-4-methyl-kynurenine for sibiromycin biosynthesis. Here, we present the crystal structures of apo-form Ss-SibL, Ss-SibL/SAH binary complex and Ss-SibL/SAH/3-HK ternary complex. Ss-SibL is a homodimer. Each subunit comprises a helical N-terminal domain and a Rossmann-fold C-terminal domain. SAM (or SAH) binding alone results in domain movements, suggesting a two-step catalytic cycle. Analyses of the enzyme-ligand interactions and further mutant studies support a mechanism in which Tyr134 serves as the principal base in the transferase reaction of methyl group from SAM to 3-HK.

Moutan cortex radicis (MCR) is a Chinese herbal medicine that was widely used over a long period as an analgesic, antipyretic, and anti-inflammatory agent in China. Lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rat models is considered similar to adult respiratory distress syndrome (ARDS) in humans. Therefore, the present study investigates the effect of MCR on ALI. The ALI model was developed through the intra-tracheal (IT) administration of LPS (16mg/kg) to Sprague-Dawley (SD) rats, which formed the LPS group. MCR was orally administered before and after LPS was introduced into rats (MCR-LPS group and LPS-MCR group, respectively). In the MCR-LPS group, rats received MCR 2g/kg/times 3 times before LPS challenge; the LPS-MCR group received MCR 2g/kg/times 3 times after LPS challenge. The results of this experiment indicate that the number of total cells and neutrophils and the concentration of protein exudation in bronchoalveolar lavage fluid (BALF) significantly decreased in the MCR-LPS group. Cytokine levels, including levels of interleukin (IL)-1β, macrophage-inflammatory peptide (MIP)-2, IL-6, and IL-10, in BALF were also significantly inhibited at 16h after LPS administration in the MCR-LPS group. Myeloperoxidase (MPO) activity in lung tissue was reduced in the MCR-LPS and LPS-MCR groups at 16h after LPS administration. Furthermore, leukocyte infiltration and protein exudation in the alveolar space were less severe in the MCR-LPS group than in the LPS group. Therefore, the findings of this study suggest that the administration of MCR prior to LPS improves ALI, possibly mediating ALI through anti-inflammation., (Crown Copyright © 2012. Published by Elsevier GmbH. All rights reserved.)

Toxic leukoencephalopathy is attributed to exposure to a wide variety of agents, including systemic chemotherapy, cranial irradiation, illicit drug abuse, and toxins from the environment. Diagnosis of this disease requires documented exposure to a toxin, neurobehavioral deficits, and typical neuroimaging abnormalities. Intoxication by compounds extracted from yam bean seeds may mimic cyanide poisoning but fail to respond to antidotal therapy. We report a 54-year-old Chinese woman who developed disturbed consciousness after eating 40 pieces of yam bean seeds. Head computed tomography obtained 24 hours after the episode was normal. However, magnetic resonance imaging obtained 20 days after the episode revealed symmetrical faint high signal over the bilateral periventricular white matter on T1-weighted image, which turned into diffuse and symmetrical bright high signal on FLAIR. The diagnosis of this patient was toxic leukoencephalopathy by yam bean seeds intoxication. The changes in brain images after yam bean seeds intoxication have not ever been reported. Physicians in Asia and the Pacific islands should have a high index of suspicion when they care for patients with acute confusion and a high anion gap metabolic acidosis but normal serum cyanide level.

Paeonol is an active component of Moutan Cortex Radicis and is widely used as an analgesic, antipyretic, and anti-inflammatory agent in traditional Chinese medicine. We wanted to determine the role of paeonol in treating adult respiratory distress syndrome (ARDS). We established an acute lung injury (ALI) model in Sprague-Dawley rats, which was similar to ARDS in humans, using intratracheal administration of lipopolysaccharide (LPS). The intraperitoneal administration of paeonol successfully reduced histopathological scores and attenuated myeloperoxidase-reactive cells as an index of polymorphonuclear neutrophils infiltration and also reduces inducible nitric oxide synthase expression in the lung tissue, at 16 h after LPS administration. In addition, paeonol reduced proinflammatory cytokines in bronchoalveolar lavage fluid, including tumor-necrosis factor-α, interleukin-1β, interleukin-6, and plasminogen-activated inhibition factor-1. These results indicated that paeonol successfully attenuates inflammatory and coagulation reactions to protect against ALI.

Background: It is reported that 30% to 80% schizophrenia patients suffered from hypersalivation when taking clozapine. Some investigations of the use of formulas of traditional Chinese medicine (TCM) to treat clozapine-induced hypersalivation suggested their potential treatment effects. In these formulas, Suoquan Pill (SQP) and Wuling Powder (WLP) were suggested to have therapeutic effects in improving clozapine-induced hypersalivation., Methods and Design: A prospective, double-blind, randomized, placebo-controlled study will be conducted to test the therapeutic effects of SQP and WLP in relieving hypersalivation in patients taking clozapine. A total of 45 patients will be enrolled into this study with 15 in each treatment group. Patients will receive medication according to their assigned group. Either SQP 10 g per oral dose twice daily, WLP 10 g per oral dose twice daily or placebo powder 10 g per oral dose twice daily will be prescribed to the patients for 8 weeks. The Drooling Severity Scale, Nocturnal Hypersalivation Rating Scale and sialoscintigraphy will be used as the primary outcome measures; the Clinical Global Impressions Severity, the Positive and Negative Syndrome Scale, the Abnormal Involuntary Movement Scale, the Simpson-Angus Scale and the TCM constitutional scale will be used as the secondary outcome measures, Discussion: It is hypothesized that SQP and WLP will have a beneficial effect in controlling clozapine-induced hypersalivation symptoms. It may also improve the life quality of psychotic patients by improving their mental status., Trial Registration: ClinicalTrials.gov (Identifier: NCT01045720).

Actinomycosis is an uncommon, chronic, granulomatous disease caused by several species of the genus Actinomyces, a Gram-positive, filamentous bacterium that normally colonizes mucosal areas. Actinomycosis can be mistaken for malignant tumors, and in most cases the diagnosis is delayed or missed entirely until surgery. Actinomycosis in the abdomen or pelvis mostly results from prolonged use of an intrauterine device. We report the case of a 40-year-old female who presented with decreased urine production, poor appetite, marked loss of body weight and intermittent lower abdominal pain for 3 months. Abdominal computed tomography indicated a large infiltrative pelvic mass that was complicated by bilateral hydronephrosis, bladder compression and small bowel adhesions. Despite the elevated levels of cancer antigen 125, we suspected pelvic actinomycosis because of a 15-year history of an intrauterine device. The diagnosis was confirmed by histopathological examination of soft tissue obtained from a laparotomy biopsy. We successfully treated the patient with prolonged antibiotics instead of surgical eradication. Abdominal computed tomography obtained 1 year later showed almost complete resolution of the pelvic inflammatory mass., (Copyright © 2010 Taiwan Society of Microbiology. Published by Elsevier B.V. All rights reserved.)

A series of dirhodium(II,II) complexes of the type cis-[Rh(2)(mu-O(2)CCH(3))(2)(dppn)(L)](2+), where dppn = benzo[i]dipyrido[3,2-a:2',3'-h]quinoxaline and L = 2,2'-bipyridine (bpy, 1), 1,10-phenanthroline (phen, 2), dipyrido[3,2-f:2'3'-h]quinoxaline (dpq, 3), dipyrido[3,2-a:2',3'-c]phenazine (dppz, 4), and dppn (5), were synthesized and their photophysical properties investigated to probe their potential usefulness as photodynamic therapy agents. The ability of the complexes to bind and photocleave DNA was also probed, along with their toxicity toward human skin cells in the dark and when irradiated with visible light. Nanosecond time-resolved absorption measurements established that the lowest energy excited state in 1-5 is dppn-localized (3)pipi* with lifetimes of 2.4-4.1 micros in DMSO, with spectral features similar to those of the free dppn ligand (tau = 13.0 micros in CHCl(3)). Complexes 1-4 photocleave DNA efficiently via a mechanism that is mostly mediated by reactive oxygen species, including (1)O(2) and O(2)(-). The DNA photocleavage by 5 is significantly lower than those measured for 1-4 in air, and the absence of O(2) in solution or the addition of azide, SOD (superoxide dismutase), or D(2)O does not affect the efficiency of the photocleavage reaction. The toxicity of 1-5 toward Hs-27 human skin fibroblasts is significantly greater upon irradiation with visible light than in the dark. In contrast to the DNA photocleavage results, 5 exhibits the largest increase in toxicity upon irradiation within the series. These results are explained in terms of the known ability of the complexes to transverse cellular membranes, the toxicity of the complexes in the dark, and their photophysical properties.

Background: Sibutramine (Meridia in the United States, Reductil in Europe) is approved for weight reduction and weight maintenance. Although amnesia and seizure is listed as a reported adverse event of sibutramine in the US product information, our literature search in the PubMed website database found no published reports of theses adverse events., Case Report: We report a 39-year-old healthy woman who had an episode of sudden memory loss lasting for several hours after taking sibutramine for 4 days. Cranial computed tomography scan, magnetic resonance imaging, and magnetic resonance angiography of the head all showed normal results. Electroencephalogram showed spike and wave complexes with phase reversal in the left mesial temporal area. Transient global amnesia was suspected clinically and transient epileptic amnesia provoked by sibutramine was also proposed. Three months after this episode, the follow-up electroencephalogram was normal. This patient did not take any anticonvulsant, and there were no more episodes of memory impairment., Discussion: This case serves to emphasize that sibutramine which was used for weight reduction might induce transient global amnesia or provoke transient epileptic amnesia. Physicians should be careful to monitor for this adverse effect when sibutramine is prescribed.

Electrical injury may cause central nervous system (CNS) complications and peripheral nerve disorders. Delayed neurologic complications are rarely reported. A case of delayed reversible motor neuronopathy caused by low-voltage electrical injury is reported due to its rarity. A 22-year-old female received an electric shock of 110 volts while pushing up a metal gate during a rainy morning on April 16, 2005. She initially suffered loss of consciousness for several hours, and then became quadriplegic, from which she completely recovered 10 days later. After return to work for 1 month, she developed weakness and numbness of bilateral upper limbs. Nerve conduction velocity study and bilateral median nerve somatosensory evoked potential were normal. Magnetic resonance imaging of the brain and cervical spine were also normal. Electromyography showed mild denervation, reduced interference and polyphasia over the upper arms, suggestive of anterior horn cell lesion. After rest and rehabilitation for 2 weeks, the patient completely recovered her muscle power over proximal upper limbs and partially over the distal upper limbs. Follow-up at the outpatient clinic 4 months later showed total recovery of muscle power. Low-voltage electrical current can cause acute transient quadriplegia and delayed motor neuronopathy. The mechanism of this patient's recovery from electric shock, followed by deterioration 1 month later, and then recovery after rest is unclear. We considered whether the mechanism of weakness after electric injury, with initial recovery followed later by the development of weakness, might be due to overuse, just like in post-poliomyelitis syndrome. This needs further investigation.

In the series Rh2(O2CR)4 (R=CH3, 1; R=CF3, 2), [Rh2(O2CR)2(phen)2]2+ (R=CH3, 3; R=CF3, 4), and [Rh2(O2CR)2(dppz)2]2+ (R=CH3, 5; R=CF3, 6), 2, 4, and 6 are twice as cytotoxic as 1, 3, and 5, respectively. The substitution reactions of 2 with 9-ethylguanine at various temperatures take place at faster rates than those of 1, and the activation energy Ea(1)=69+/-4 kJ/mol is twice Ea(2)=35+/-2 kJ/mol. The higher cytotoxicities of [Rh2(micro-O2CCH3)2(eta1-O2CCH3)L(MeOH)]+ (L=dppz, 7; L=dppn, 8) relative to [Rh2(micro-O2CCH3)2(bpy)L]2+ (L=dppz, 10; L=dppn, 11) are attributed to the labile equatorial groups in 7 and 8 not present in 10 and 11. The toxicities of complexes 1-8 are not related to their charge or the ease by which they transverse the cellular membrane but to the lability of the ligands on the dirhodium core.

The complex cis-[Rh2(mu-O2CCH3)2(CH3CN)6]2+ (1) exchanges the two axial CH3CN ligands for solvent molecules in water to yield cis-[Rh2(mu-O2CCH3)2(CH3CN)4(H2O)2]2+ (2). Photolysis of 2 in H2O results in the photoaquation of two equatorial acetonitrile ligands to yield [Rh2(mu-O2CCH3)2(CH3CN)2(H2O)4]2+ (3), which is able to covalently bind to free 2,2'-bipyridine (bpy) and 9-ethylguanine in solution, as well as double-stranded DNA (lambdairr >/= 455 nm). Complex 2 exhibits 20-fold lower cytotoxicity towards human skin cells than hematoporphyrin in the dark, and its toxicity increases by a factor of 34 when irradiated with visible light (400-700 nm, 30 min). This increase in cytotoxicity by 2 upon irradiation is approximately 7 times greater than that measured for hematoporphyrin. These properties make 2 a promising photo-cisplatin analog and a potential agent for photodynamic therapy. To our knowledge, 2 is the first metal-metal bonded complex to bind to DNA upon irradiation with visible light.

A new type of heteroleptic dirhodium complex cis-[Rh(2)(mu-O2CCH3)2-(bpy)(dppz)]2+ (3) was synthesized and its potential as a photodynamic therapy (PDT) agent was investigated. Although 27% hypochromicity of the absorption of 3 in the near-UV and visible regions is observed in the presence of duplex DNA, relative viscosity measurements reveal that the complex does not intercalate between the DNA bases. The DNA photocleavage with visible light by 3 proceeds via both oxygen dependent and independent mechanisms, and it is more efficient than that of related complexes. The increase in the cytotoxicity of 3 towards human skin cells is similar to that of hematoporphyrin, a key ingredient in a PDT drug currently in use. This feature makes this complex a useful candidate for further PDT studies.

Aromatic amines, such as o-phenylenediamine (OPD), have been used extensively in commercial hair dyes and in the synthesis of agricultural pesticides. Air oxidation of OPD results in the formation of 2,3-diaminophenazine (DAP). Although the mutagenic toxicity of DAP has been shown in both prokaryotic and eukaryotic systems, its phototoxicity remains largely unexplored. This study focuses on the pH-dependent photophysical properties of DAP and demonstrates its ability to photoinduce DNA damage to pUC19 plasmid in vitro. The photocytotoxicity of DAP toward human skin fibroblasts was also measured. DAP exhibits weak intercalative binding to double-stranded DNA with a binding constant K(b) = 3.5 x 10(3) M(-1). Furthermore, upon irradiation with visible light, DAP is able to nick plasmid DNA in the presence of oxygen. The concentration of DAP that resulted in 50% cell death was 172 +/- 9 microM in the dark and 13 +/- 1 microM after irradiation of the DAP-treated cell cultures with visible light (400-700 nm, 30 min, 5 J/cm(2)). The 13-fold increase in toxicity upon exposure to visible light shows the need for further study of the photocytotoxicity of contaminants such as DAP.

Two new dirhodium(II) complexes possessing the intercalating dppz ligand (dppz = dipyrido[3,2-a:2',3'-c]phenazine), cis-[Rh(2)(mu-O(2)CCH(3))(2)(dppz)(eta(1)-O(2)CCH(3))(CH(3)OH)](+) (1) and cis-[Rh(2)(mu-O(2)CCH(3))(2)(dppz)(2)](2+) (2), were synthesized and characterized as potential agents for photochemotherapy. Various techniques show that 1 binds to DNA through intercalation, although some aggregation of the complex on the DNA surface is also present. In contrast, 2 does not intercalate between the DNA bases; however, strong hypochromic behavior is observed in the presence of DNA, which can be attributed to intermolecular pi-stacking of 2 enhanced by the polyanion. The apparent DNA binding constants determined using optical titrations are compared to those from dialysis experiments. Both complexes photocleave pUC18 plasmid in vitro under irradiation with visible light (lambda(irr) >or= 395 nm, 15 min), resulting in the nicked, circular form. Greater photocleavage is observed for 1 relative to 2, which may be due to the ability of 1 to intercalate between the DNA bases. The cytotoxicity toward human skin cells (Hs-27) measured as the concentration at which 50% cell death is recorded, LC(50), was found to be 135 +/- 8 microM for 2 in the dark (30 min), which is significantly lower than those of 1 (LC(50) = 27 +/- 2 microM) and Rh(2)(O(2)CCH(3))(4) (LC(50) = 15 +/- 2 microM). Irradiation of cell cultures containing 1 and Rh(2)(O(2)CCH(3))(4) with visible light (400-700 nm, 30 min) has little effect on their cytotoxicity, with LC(50) values of 21 +/- 3 and 13 +/- 2 microM, respectively. Interestingly, a 3.4-fold increase in the toxicity of 2 is observed when the cell cultures are irradiated (400-700 nm, 30 min), resulting in LC(50) = 39 +/- 1 microM. The greater toxicity of 1 compared to 2 in the dark may be related to the ability of the former compound to intercalate between the DNA bases. The lower cytotoxicity of 2, together with its significantly greater photocytotoxicity, makes this complex a potential agent for photodynamic therapy (PDT). These results suggest that intercalation or strong DNA binding may not be a desirable property of a potential PDT agent.

The nature of the equatorial ligands spanning the dirhodium core was shown to affect the ability and mechanism of various lantern-type complexes to inhibit transcription in vitro. The inhibition of transcription by Rh(2)(mu-O(2)CCF(3))(4), Rh(2)(mu-HNCOCF(3))(4), and [Rh(2)(mu-O(2)CCH(3))(2)(CH(3)CN)(6)](2+) appears to proceed predominantly via binding of the complexes to T7-RNA polymerase (T7-RNAP) and is dependent on the concentration of enzyme and Mg(2+) ions in solution. The concentrations of the aforementioned complexes required to inhibit 50% of the transcription, C(inh)(50), are similar to that measured for activated cisplatin, whereas a significantly higher concentration of Rh(2)(mu-HNCOCH(3))(4) is required to effect similar inhibition; the inhibition induced by Rh(2)(mu-HNCOCH(3))(4) does not involve binding to T7-RNAP. The spectral changes observed for each complex upon addition of enzyme are consistent with Rh(2)(mu-O(2)CCF(3))(4), Rh(2)(mu-HNCOCF(3))(4), and [Rh(2)(mu-O(2)CCH(3))(2)(CH(3)CN)(6)](2+) binding to the enzyme and may involve partial displacement of the equatorial (eq) groups by the Lewis basic sites of T7-RNAP. In contrast, addition of enzyme to solutions of Rh(2)(mu-HNCOCH(3))(4) does not result in significant spectral changes, a finding consistent with lack of enzyme dependence in the transcription inhibition. These differences in reactivity and transcription inhibition mechanism among complexes with different bridging ligands are explained by variations of the Lewis acidity of the axial (ax) sites in the series of complexes Rh(2)(mu-O(2)CCF(3))(4), Rh(2)(mu-HNCOCF(3))(4), and Rh(2)(mu-HNCOCH(3))(4). The Lewis acidity of the ax sites is expected to affect the initial interaction of the complexes with the biomolecules, followed by their rearrangement to eq positions if the bridging ligands are labile.

The DNA binding and inhibition of transcription in vitro by neutral Rh(2)(mu-O(2)CCH(3))(4) and cationic cis-[Rh(2)(mu-O(2)CCH(3))(2)(phen)(2)](2+) complexes were investigated. The binding constants of the two complexes to calf-thymus DNA were estimated from absorption titrations to be 4.6 x 10(2) M(-)(1) and 1.7 x 10(4) M(-)(1) for Rh(2)(mu-O(2)CCH(3))(4) and cis-[Rh(2)(mu-O(2)CCH(3))(2)(phen)(2)](2+), respectively. The shift to higher energies of the low-energy absorption of the complexes upon addition of DNA is consistent with axial binding of the complexes to duplex DNA. The relative concentrations, [complex]/[DNA], of Rh(2)(mu-O(2)CCH(3))(4) and cis-[Rh(2)(mu-O(2)CCH(3))(2)(phen)(2)](2+) at which 50% of the transcription is inhibited (R(inh)(50)), are 0.0031 and 0.0011, respectively. These concentrations are significantly lower than that required for activated cisplatin, cis-[Pt(NH(3))(2)(H(2)O)(2)](2+), with R(inh)(50) = 0.0085 under similar experimental conditions. Upon incubation of cis-[Pt(NH(3))(2)(H(2)O)(2)](2+) with the template DNA prior to the addition of the enzyme and nucleobases necessary for the transcription reaction for 30 min at 37 degrees C, significantly lower concentrations of the complex were required to attain 50% inhibition. In contrast, similar incubation of the DNA with the dirhodium complexes did not result in better transcription inhibition. Experiments designed to elucidate the mechanism of the observed inhibition indicate that, unlike cis-[Pt(NH(3))(2)(H(2)O)(2)](2+), Rh(2)(mu-O(2)CCH(3))(4) and cis-[Rh(2)(mu-O(2)CCH(3))(2)(phen)(2)](2+) appear to interact directly with the enzyme T7-RNA polymerase as their mode of inhibition.

The ability of octahedral complexes possessing quinone diimine ligands to inhibit transcription by stabilization of the DNA duplex structure was investigated. Rh(III) and Ru(II) complexes possessing two quinone diimine ligands in their coordination sphere were found to significantly increase the melting temperature (DeltaT(m)) of a 15-mer duplex DNA. [Rh(phi)(2)phen](3+) and [Ru(phi)(2)phen](2+) (phi = 9,10-phenanthrenequinone diimine, phen = 1,10-phenanthroline) exhibit DeltaT(m) values of +21 and +15 degrees C relative to free 15-mer duplex (T(m) = 55 degrees C) at [complex]/[DNA bases] = 0.067 (two complexes/duplex). Similarly, a shift in the melting temperature of +14 degrees C was measured for [Rh(bqdi)(2)phen](3+) (bqdi = 1,2-benzoquinone diimine), which possesses the nonintercalating bqdi ligand. In contrast, [Ru(phen)(2)phi](2+) and [Rh(phen)(2)L](3+) (L = phi, bqdi), which possess a single quinone diimine ligand, the parent [Ru(phen)(3)](2+) and [Rh(phen)(3)](3+) complexes, and ethidium bromide result in small shifts in the melting temperature of the duplex oligonucleotide. A distinct correlation between DeltaT(m) and the relative concentration of each complex required to inhibit 50% of the transcription (R(inh)(50)) was observed, independent of the presence of an intercalative ligand. The duplex stabilization by bis(quinone diimine) complexes results in inhibition of transcription in vitro at significantly lower complex concentrations than for the corresponding [Ru(phen)(2)phi](2+) and [Rh(phen)(2)L](3+) (L = phi, bqdi) complexes. Possible explanations for these observations are discussed.

A novel Ru(II) complex possessing two sequentially linked viologen units, Ru-V(1)-V(2)(6+), was synthesized and characterized. Upon excitation of the Ru(II) unit (lambda(exc) = 532 nm, fwhm approximately 10 ns), a long-lived charge-separated (CS) state is observed (tau = 1.7 micros) by transient absorption spectroscopy. Unlike Ru(bpy)(3)(2+), which cleaves DNA upon photolysis through the formation of reactive oxygen species, such as (1)O(2) and O(2)(-), the photocleavage of plasmid DNA by Ru-V(1)-V(2)(6+) is observed both in air and under N(2) atmosphere (lambda(irr) > 395 nm).