Spatially localized generation of nucleotide sequence-specific DNA damage

Psoralens linked to triplex-forming oligonucleotides (psoTFOs) have been used in conjunction with laser-induced two-photon excitation (TPE) to damage a specific DNA target sequence. To demonstrate that TPE can initiate photochemistry resulting in psoralen-DNA photoadducts, target DNA sequences were incubated with psoTFOs to form triple-helical complexes and then irradiated in liquid solution with pulsed 765-nm laser light, which is half the quantum energy required for conventional one-photon excitation, as used in psoralen + UV A radiation (320-400 nm) therapy. Target DNA acquired strand-specific psoralen monoadducts in a light dose-dependent fashion. To localize DNA damage in a model tissue-like medium, a DNA-psoTFO mixture was prepared in a polyacrylamide gel and then irradiated with a converging laser beam targeting the rear of the gel. The highest number of photoadducts formed at the rear while relatively sparing DNA at the front of the gel, demonstrating spatial localization of sequence-specific DNA damage by TPE. To assess whether TPE treatment could be extended to cells without significant toxicity, cultured monolayers of normal human dermal fibroblasts were incubated with tritium-labeled psoralen without TFO to maximize detectable damage and irradiated by TPE. DNA from irradiated cells treated with psoralen exhibited a 4- to 7-fold increase in tritium activity relative to untreated controls. Functional survival assays indicated that the psoralen-TPE treatment was not toxic to cells. These results demonstrate that DNA damage can be simultaneously manipulated at the nucleotide level and in three dimensions. This approach for targeting photochemical DNA damage may have photochemotherapeutic applications in skin and other optically accessible tissues.     

The mechanism of action of the antiinflammatory agents dexamethasone and Auranofin in human polymorphonuclear leukocytes

Human polymorphonuclear neutrophils (PMN) were treated with the antiinflammatory agents dexamethasone or Auranofin. PMN treated with dexamethasone in a dose range of 0.25-1 microM or Auranofin, 5-15 mM, were stimulated with 10(-7)M N-formyl-methionyl-leucyl-phenylalanine (FMLP). These agents were shown to inhibit the functional responses of degranulation and superoxide production in a dose-dependent manner. Similarly, the change in electrophoretic mobility, reflecting cell surface charge, was blocked. While both agents inhibited change in the fluorescence of the calcium chelate probe chlorotetracycline (CTC), the pattern of inhibition was significantly different. Dexamethasone appeared to inhibit the CTC response during its latter phases, while Auranofin inhibited all aspects of the CTC response. Auranofin was additionally shown to significantly decrease specific binding of FMLP, as well as the number of FMLP receptors. The two agents thus appear to act by different mechanisms. Dexamethasone is shown to have an effect on membrane-bound calcium release as measured by CTC, while Auranofin interferes with receptor binding.     

In vitro and in vivo effects of treatment by platelet-activating factor on N-formyl-met-leu-phe-mediated responses of polymorphonuclear leucocytes

Two chemoattractants, the peptide N-formyl-met-leu-phe (FMLP), and the ether phospholipid, platelet activating factor (PAF), each stimulate a variety of in vitro responses in polymorphonuclear leucocytes (PMN). Because often more than one inflammatory mediator is active during inflammation, we determined the effect on PMN of sequential stimulation with these two agents. Before FMLP stimulation, human PMN were exposed to PAF, at concentrations which gave little or no response when administered alone. PAF enhanced FMLP-elicited superoxide release in a dose-dependent fashion. Likewise, release of granular lysozyme from the cells was increased in PAF treated cells. Similar treatment with other phospholipids, including the lyso derivation of PAF, failed to produced these effects. Incubation with nordihydroguaiaretic acid, an inhibitor of arachidonic acid metabolism, had little effect on the enhancement of lysozyme release by PAF. To determine if enhancing effects by PAF might occur also in vivo, we studied rabbits receiving PAF and/or FMLP intravenously. When rabbits received 0.01 micrograms PAF (a dose which does not elicit the sustained neutropenia observed with higher doses of PAF) followed by 0.05 micrograms FMLP the absolute granulocyte count (AGC) dropped at 1 min (46 +/- 11% of original value), and continued to fall (24 +/- 12% at 10 min). Controls, treated with the suspending fluid for PAF, and then 0.05 micrograms FMLP, had a similar 1 min AGC value, but at 10 min AGC returned to 65 +/- 6.1% (P less than 0.001 for comparison of 10 min values). Thus PAF pretreatment enhanced FMLP-elicited granulocytopenia in vivo. Study of in vitro human PMN aggregation revealed that, at certain relative concentrations of PAF and FMLP, aggregation was enhanced. These studies show that both in vitro and in vivo responses of FMLP-stimulated PMN may be exaggerated by pre-exposure to PAF.     

Method for recording electrical activity of the sinoatrial node and automatic atrial foci during cardiac catheterization in human subjects

A method for recording electrical activity of the sinoatrial (S-A) node and automatic atrial foci in human subjects is described. To record S-A nodal electrograms, an electrode catheter was inserted percutaneously into the femoral vein and advanced under fluoroscopic control to the superior vena caval-right atrial junction. The distal terminal of the catheter was placed in the area of the S-A node and the proximal terminal on the free right atrial wall or in the right atrial lumen. Polarity was reversed from the conventional electrocardiographic recording; high amplification (about 100 μV/cm) and selective filters (0.1 to 20 hertz) were used.S-A nodal electrograms recorded with this method in human subjects were similar to electrograms obtained previously from the dog and rabbit and revealed negatively directed diastolic and upstroke slopes preceding the P wave of the electrocardiogram. Sinoatrial conduction time measured from the S-A nodal electrograms in 15 cases was 34.9 ± 2.1 ms (mean ± standard error of the mean) for a sinus cycle length of 736.4 ± 38.6 ms. The coronary sinus electrograms in a patient with coronary sinus rhythm were recorded by the same technique except that the distal terminal of the catheter was placed at the coronary sinus ostium. A negatively directed diastolic slope preceding the P wave was consistently recorded.This method for recording electrograms of the S-A node and ectopic automatic atrial foci should prove useful in (1) assessment of both normal and abnormal S-A nodal function, (2) direct determination of conduction time from the S-A nodal pacemaker to the atrium, and (3) localization of automatic atrial foci.     

Microbicidal/cytotoxic proteins of neutrophils are deficient in two disorders: Chediak-Higashi syndrome and "specific" granule deficiency

Although several genetic defects are known to impair oxidative microbicidal/cytotoxic mechanisms in human PMN, no deficiencies of PMN granule components that mediate oxygen-independent microbicidal activity have yet been reported. We analyzed PMN from patients with various granulocyte disorders for their content of two azurophil granule constituents, defensins and cathepsin G, that exert microbicidal/cytotoxic activity in vitro, and one component, elastase, that has ancillary microbicidal/cytotoxic activity. PMN from two (of two) patients with specific granule deficiency (SGD) displayed an almost complete deficiency of defensins, which in normal cells constitute greater than 30% of the protein content of azurophil granules. The SGD PMN contained normal or mildly decreased amounts of cathepsin G and elastase. Conversely, the PMN of three (of three) patients with Chediak-Higashi syndrome (CHS) substantially lacked cathepsin G and elastase, but their defensin content was normal or mildly decreased. Both CHS and SGD patients suffer from frequent and severe bacterial infections, and CHS patients frequently develop an atypical lymphoproliferative syndrome. The profound deficiency of PMN components with microbicidal/cytotoxic activity in SGD and CHS may contribute to the clinical manifestations of these disorders.     

Variations in breast cancer histology and treatment patterns between the major ethnic groups of South West Sydney

Studies in the United States and United Kingdom have demonstrated ethnic variations in breast cancer receptor status, histology, and treatment access. This study aimed to investigate whether ethnicity variation similarly exists in Australia. Patients diagnosed with breast cancer between 2006 and 2011 across all public hospitals in the South Western Sydney Local Health District were identified and patient data collected retrospectively. Logistic regression analysis was used to measure the association between various biologic and treatment parameters and ethnicity. Ethnicity was found to have an influence on age of diagnosis, histology, treatment utilization, and recurrence in breast cancer patients.     

Molecular analysis of the beta-thalassemia phenotype associated with inheritance of hemoglobin E (alpha 2 beta2(26)Glu leads to Lys).

Inheritance of the gene for betaE-globin is associated with hypochromia and microcytosis, reminiscent of typical heterozygous beta-thalassemia. Patients with hemoglobin (Hb)E-beta-thalassemia exhibit clinical phenotypes of severe beta-thalassemia, a circumstance not encountered in other compound heterozygous states for structural beta-chain mutations and beta-thalassemia. We have analyzed the kinetics of globin synthesis and the levels of globin messenger (m) RNA accumulation in patients with Hb E-beta-thalassemia and Hb E trait. The initial rate of beta-globin synthesis (betaE/alpha=0.20-0.34) was less than expected on the basis of gene dosage, or comparable studies of other compound heterozygous states for beta-thalassemia and structurally abnormal beta-chains. betaE-globin synthesis was not only reduced during short-term incubations (1-5 min), but also remained relatively unchanged during long-term pulse or chase incubations up to 5h. Analysis of globin mRNA by cell-free translation and molecular hybridization confirmed that the unexpectedly low levels of betaE-globin synthesis were associated with comparable reduction in the levels of beta-globin mRNA. In Hb E-beta-thalassemia the betaA + betaE (alpha globin nRNA ratio observed were substantially lower than those obtained from reticulocytes of patients with heterozygous beta-thalassemia, or Hb S-betaO-thalassemia, while in Hb E trait, the betaA + betaE/alpha mRNA ratio was in the ranged observed for beta-thalassemia trait. The betaE-globin gene specifies reduced accumulation of betaE-globin mRNA, a property characteristic of other forms of beta-thalassemia. The beta-thalassemia phenotype associated with inheritance of Hb E is thus determined at the level of beta-globin mRNA metabolism.     

The association between vitamin D and inflammation with the 6-minute walk and frailty in patients with heart failure

OBJECTIVES: To identify relationships between anabolic hormones, inflammatory markers, and physical function. DESIGN: Cross‐sectional. SETTING: Outpatient university heart failure program in Connecticut. PARTICIPANTS: Sixty patients with an ejection fraction of 40% or less. MEASUREMENTS: The 6‐minute walk distance and frailty phenotype were measured. The relationship between physical measures of hormones and inflammatory mediators were examined. Linear and ordinal logistic regression analyses were performed for the physical measures. RESULTS: Forty‐three men (mean age 77 ± 9) and 17 women (mean age 78 ± 12) participated. Longer 6‐minute walk distance was correlated with higher 25‐hydroxyvitamin D (25OHD) level, and a shorter walk was correlated with higher cortisol: dehydroepiandrosterone sulphate (DHEAS) ratio, high‐sensitivity C‐reactive protein (hsCRP), interleukin‐6 (IL6), and intact parathyroid hormone (PTH) (all P<.05). Percentage of free testosterone, DHEAS alone, and N‐terminal pro‐brain natriuretic peptide (NTpro‐BNP) did not correlate with 6‐minute walk distance. Higher frailty phenotype score (more frail) was correlated with higher high‐sensitivity CRP, higher IL6, and lower 25OHD levels (all P<.05). Linear regression with the 6‐minute walk distance as the dependent variable and independent variables of age, sex, percentage of free testosterone, DHEAS, 25OHD, intact PTH, hsCRP, IL6, cortisol/DHEAS ratio, and NTpro‐BNP, revealed age, sex, 25OHD and hsCRP to be significant (coefficient of determination=53.5%). Ordinal logistic regression with the frailty phenotype and hormonal levels revealed that age, 25OHD, and hsCRP also predicted frailty status. CONCLUSION: Twenty‐five‐hydroxyvitamin D and hsCRP levels may contribute to lower aerobic capacity and frailty in patients with heart failure. A longitudinal study will further define the role of 25OHD and hsCRP on muscle strength and functional decline.     

Recombinant human G-CSF and GM-CSF prime human neutrophils for superoxide production through different signal transduction mechanisms.

Recombinant human granulocyte-colony stimulating factor (G-CSF) and recombinant human granulocyte/macrophage-colony stimulating factor (GM-CSF) stimulate neutrophil production from precursors in the marrow and enhance granulocyte functions in vitro. We studied the effects of G-CSF and GM-CSF on neutrophil superoxide production and secretion. G-CSF and GM-CSF alone stimulated neither superoxide production nor secretion, but both agents primed neutrophils for superoxide production stimulated by either N-formylmethionyl-leucyl-phenylalanine (FMLP) or ionomycin. Optimal priming occurred with G-CSF at 5.3 ng/ml for 20 minutes and for GM-CSF at 1 ng/ml for 60 minutes. Priming by GM-CSF was more readily inhibited by the tyrosine kinase inhibitor ST638 but was unaffected by staurosporine. Conversely, G-CSF priming was inhibited by staurosporine but not by ST638. Neither protein kinase C translocation nor increased protein kinase C activity, however, were observed after G-CSF/GM-CSF treatment. Priming by G-CSF and GM-CSF was sensitive to pertussis toxin, suggesting the involvement of guanine nucleotide-binding proteins (G-proteins). Neutrophils from three siblings with cyclic neutropenia were studied to observe the effects of G-CSF treatment on neutrophil function in vivo; sibling 1 and sibling 2 were treated with G-CSF for 6 months, but sibling 3 was not in the treatment group. Compared with neutrophils from normal donors, neutrophils from sibling 1 and sibling 2 were primed in vivo for superoxide release stimulated by either ionomycin or FMLP. Superoxide released by neutrophils from sibling 3 was similar to control cells.(ABSTRACT TRUNCATED AT 250 WORDS)