Monitoring hydroquinone-quinone redox cycling by single molecule fluorescence spectroscopy.

Current research in the field of single-molecule chemistry is increasingly focused on the development of reliable experimental approaches for investigating chemical processes on a molecular level using single-molecule fluorescence spectroscopy (SMFS). Herein, we report on single-molecule observations of the copper(II)/air mediated oxidation of fluorescently labeled hydroquinone-based probe molecules followed by their reduction with cysteine. The redox cycle is signaled by quenching/recovery of fluorescence emission after addition of the oxidant/reductant, respectively. The experiments were realized by immobilizing the probe on a glass cover slide to allow single-molecule observation by means of total-internal-reflection fluorescence microscopy. Besides detection of successful oxidation and reduction events on single probe molecules, individual molecular intensity trajectories revealed dynamic processes and formation of intermediate states upon reaction. For the experimental design presented, we envision further reaction studies of catalytic redox-processes of single hydroquinone-moieties by means of SMFS.

Statin treatment reduces matrix degradation capacity of proinflammatory polarized macrophages.

BACKGROUND AND AIMS: Macrophages are versatile immune cells involved in tissue degradation and remodeling. Proinflammatory macrophages have the highest capacity of matrix degradation and proteolysis. Within atherosclerotic lesions, proinflammatory macrophages are associated with unstable plaques. Statins have been demonstrated to increase plaque stability. Possible changes of polarized macrophage tissue degradation behavior under statin treatment are currently unknown. METHODS: Polarized macrophages were tested in vitro for matrix degradation capacity with or without statin treatment. RESULTS: Proinflammatory macrophages show high matrix degradation capacity, which is lost after statin treatment. Statin concentrations were within a physiological range and did not influence overall macrophage polarization. Proinflammatory macrophages showed however a loss of filopodia where activators of MMPs are located. Loss of matrix degradation in proinflammatory macrophages was associated with changes of MMP14 activation and loss of uPAR localization at filopodia. Supplementation of mevalonate restored localization of uPAR to cellular protrusions and matrix degradation capacity. CONCLUSION: Statins reduce the matrix degradation potential of proinflammatory macrophages by reducing uPAR localization to cellular filopodia and reducing intracellular MMP14 activation.

Differential in vivo activation of monocyte subsets during low-grade inflammation through experimental endotoxemia in humans.

Human monocytes are a heterogeneous cell population, which can be divided into a classical (CD14++CD16-), a non-classical (CD14+CD16+), and an intermediate (CD14++CD16+) subset. We hypothesized that low-grade inflammation may differentially affect monocyte subsets. We used a human lipopolysaccharide (LPS) infusion model to mimic low-grade inflammation to identify, which monocyte subsets are preferentially activated under these conditions. Monocyte subsets were identified by staining for CD14 and CD16, activation status of monocytes was analyzed by staining for CD11b and a novel in situ mRNA hybridization approach to detect IL-6 and IL-8 specific mRNA at the single-cell level by flow cytometry. After LPS challenge, cell numbers of monocyte subsets dropped after 2 h with cell numbers recovering after 6 h. Distribution of monocyte subsets was skewed dramatically towards the intermediate subset after 24 h. Furthermore, intermediate monocytes displayed the largest increase of CD11b expression after 2 h. Finally, IL-6 and IL-8 mRNA levels increased in intermediate and non-classical monocytes after 6 h whereas these mRNA levels in classical monocytes changed only marginally. In conclusion, our data indicates that the main responding subset of monocytes to standardized low-grade inflammation induced by LPS in humans is the CD14++CD16+ intermediate subset followed by the CD14+CD16+ non-classical monocyte subset. Circulating classical monocytes showed comparably less reaction to LPS challenge in vivo.

Obstetrical problems in patients with Ehlers-Danlos syndrome type IV; a case report.

The Ehlers-Danlos syndrome type IV is a heritable connective-tissue disorder characterized by thin translucent skin, pronounced bruising and scarring, and extreme tissue fragility. Obstetrical complications include premature rupture of membranes, rupture of blood vessels and gravid uterus, tearing of perineum, vagina, urethra and bladder, requesting specific prophylactic and therapeutic measurements. Hereditary transmission is usually autosomal dominant with variable expression. Histological examination of skin biopsy and biochemical analysis of collagen proteins from skin fibroblast cultures confirm the clinical diagnosis. DNA studies offer the possibility of prenatal diagnosis in suitable families. The consecutive severe obstetrical complications of a woman with Ehlers-Danlos syndrome type IV are reported here. The patient died at age 33 years from renal artery rupture.

A pilot study to test the feasibility of salt restriction in a community.

Index subjects were selected from the population of Milton studied in the May 1981 survey. Index subjects aged 64 or less with a systolic blood pressure 138-179 mmHg (18.35/23.8 kPa), including those on antihypertensive treatment, were invited to participate with their families. Index subjects were divided into two matched groups. One group was randomly assigned to be the control group and the other to be the salt-restriction group. Age, weight, height and 24-hour urinary excretion of sodium, potassium and creatinine at the start of the study in August 1981 were similar for the control and salt-restriction groups. When tested in November 1981, the salt-restriction group had achieved a reduction in 24-hour sodium excretion to a mean of 84 mmol for men and 70 mmol for women; corresponding values for the control groups were 150 and 120 mmol. A further test in March 1982 showed little further change. Potassium output changed very little. Attitudes to the low-salt diet varied, but 87 percent found it tolerable or actually preferable. There is no doubt that major reductions in sodium intake are feasible. However, if these are to be achieved on a large scale, food, manufacturers will need to offer a variety of low-sodium foods.

Iodide excretion in a salt-restriction trial.

Twenty-four hour urinary iodide excretion was measured twice, with a four month interval, in 133 individuals who were in a 12-month salt-restriction study in an area where iodine-deficiency goitre was once common and where most household salt is iodised. Half the subjects were salt restricted; their mean 24 h sodium excretion after eight months was 89 mmol for men and 73 mmol for women. Iodide excretion correlated with sodium excretion in the whole group on each occasion. After eight months mean 24 h iodide excretion in the salt-restricted group (men 1.3 SD 0.6 mumol, women 1.1 SD 0.4 mumol) was lower (p less than 0.01) than that in the control group (men 1.8 SD 0.8 mumol, women 1.7 SD 0.8 mumol), but was reasonable in terms of recommended dietary allowances (1.2 mumol, 150 mg). Mean iodide content of local milk was 1.3 mumol/l. Any salt that is used in the home should continue to be iodised. However, it has become unnecessary in this population to use salt (ie, iodised salt) simply in order to avoid iodine deficiency, so long as other foodstuffs continue to contain iodine as at present. As the other sources of iodine may be subject to change, the adequacy of intake of iodine from these sources should be monitored from time to time in samples of the population.

The effects of a companion animal on distress in children undergoing dental procedures.

The purpose of our pilot study was to evaluate the effects of a companion animal (dog) on physiologic arousal and behavioral distress among children undergoing a dental procedure. A repeated measures experimental design was used to study 40 children between the ages of 7 and 11 years who were undergoing procedures in a pediatric dental clinic. Half the children had the dog present during the procedure and half did not. Data were obtained before, during, and after the procedure. Behavioral distress was measured using the Observational Scale of Behavioral Distress; procedures were videotaped. Physiologic arousal was measured using a YSI telethermometer taped to the child's index finger. Student's t-test and repeated measures analysis of variance were used to answer the research question. No significant differences in behavioral distress or physiologic arousal were found between experimental and control groups. Further analysis revealed that for children who initially verbalized distress on arrival at the clinic, the presence of the dog decreased physiologic arousal during the time the child was on the dental table waiting for the dentist to arrive. Further research should be conducted to verify the effect of a companion animal on initial stress experienced by children for whom the visit to the dentist is most stressful.