Spatial hole burning in thin-disk lasers and twisted-mode operation.

Spatial hole burning prevents single-frequency operation of thin-disk lasers when the thin disk is used as a folding mirror. We present an evaluation of the saturation effects in the disk for disks acting as end mirrors and as folding mirrors, explaining one of the main obstacles toward single-frequency operation. It is shown that a twisted-mode scheme based on a multi-order quarter-wave plate combined with a polarizer provides an almost complete suppression of spatial hole burning and creates an additional wavelength selectivity that enforces efficient single-frequency operation.

Lipidomic profiling before and after Roux-en-Y gastric bypass in obese patients with diabetes.

Bariatric surgery is a well-established approach to improve metabolic disease in morbidly obese patients with high cardiovascular risk. The post-operative normalization of lipid metabolism has a central role in the prevention of future cardiovascular events. The aim of the present study therefore was to characterize changes of plasma lipidomic patterns, consisting of 229 lipid species of 13 lipid classes, 3 months after Roux-en-Y gastric bypass (RYGB) in morbidly obese patients with and without diabetes. RYGB resulted in a 15-32% decrease of body mass index, which was associated with a significant reduction of total cholesterol (TC, -28.3%; P=0.02), LDL-cholesterol (LDL-C, -26.8%; P=0.03) and triglycerides (TGs, -63.0%; P=0.05) measured by routine clinical chemistry. HDL-cholesterol remained unchanged. The effect of RYGB on the plasma lipidomic profile was characterized by significant decreases of 87 lipid species from triacylglycerides (TAGs), cholesterol esters (CholEs), lysophosphatidylcholines (LPCs), phosphatidylcholines (PCs), phosphatidylethanolamine ethers (PEOs), phosphatidylinositols (PIs) and ceramides (Cers). The total of plasma lipid components exhibited a substantial decline of 32.6% and 66 lipid species showed a decrease by over 50%. A direct correlation with HbA1C values could be demonstrated for 24 individual lipid species (10 TAG, three CholE, two LPC, one lysophosphatidylcholine ethers (LPCO) (LPC ether), one PC, two phosphatidylcholine ethers (PCO) and five Cer). Notably, two lipid species (TAG 58:5 and PEO 40:5) were inversely correlated with HbA1C. LPCO, as single whole lipid class, was directly related to HbA1C. These data indicate that RYGB-induced modulation of lipidomic profiles provides important information about post-operative metabolic adaptations and might substantially contribute to improvements of glycemic control. These striking changes in the human plasma lipidome may explain acute, weight independent and long-term effects of RYGB on the cardiovascular system, mental status and immune regulation.

Intracellular Ca2+ inhibits smooth muscle L-type Ca2+ channels by activation of protein phosphatase type 2B and by direct interaction with the channel.

Modulation of L-type Ca2+ channels by tonic elevation of cytoplasmic Ca2+ was investigated in intact cells and inside-out patches from human umbilical vein smooth muscle. Ba2+ was used as charge carrier, and run down of Ca2+ channel activity in inside-out patches was prevented with calpastatin plus ATP. Increasing cytoplasmic Ca2+ in intact cells by elevation of extracellular Ca2+ in the presence of the ionophore A23187 inhibited the activity of L-type Ca2+ channels in cell-attached patches. Measurement of the actual level of intracellular free Ca2+ with fura-2 revealed a 50% inhibitory concentration (IC50) of 260 nM and a Hill coefficient close to 4 for Ca2+- dependent inhibition. Ca2+-induced inhibition of Ca2+ channel activity in intact cells was due to a reduction of channel open probability and availability. Ca2+-induced inhibition was not affected by the protein kinase inhibitor H-7 (10 microM) or the cytoskeleton disruptive agent cytochalasin B (20 microM), but prevented by cyclosporin A (1 microg/ ml), an inhibitor of protein phosphatase 2B (calcineurin). Elevation of Ca2+ at the cytoplasmic side of inside-out patches inhibited Ca2+ channels with an IC50 of 2 microM and a Hill coefficient close to unity. Direct Ca2+-dependent inhibition in cell-free patches was due to a reduction of open probability, whereas availability was barely affected. Application of purified protein phosphatase 2B (12 U/ml) to the cytoplasmic side of inside-out patches at a free Ca2+ concentration of 1 microM inhibited Ca2+ channel open probability and availability. Elevation of cytoplasmic Ca2+ in the presence of PP2B, suppressed channel activity in inside-out patches with an IC50 of approximately 380 nM and a Hill coefficient of approximately 3; i.e., characteristics reminiscent of the Ca2+ sensitivity of Ca2+ channels in intact cells. Our results suggest that L-type Ca2+ channels of smooth muscle are controlled by two Ca2+-dependent negative feedback mechanisms. These mechanisms are based on (a) a protein phosphatase 2B-mediated dephosphorylation process, and (b) the interaction of intracellular Ca2+ with a single membrane-associated site that may reside on the channel protein itself.

Protein kinase-C mediates dual modulation of L-type Ca2+ channels in human vascular smooth muscle.

The role of protein kinase C (PKC) in cellular regulation of L-type Ca2+ channels was investigated in human umbilical vein smooth muscle. Activation of PKC, by low concentrations (< 30 nM) of 12-O-tetradecanoyl-phorbol-13-acetate (TPA) caused inhibition of Ca2+ channels, while higher concentrations of TPA (> 100 nM) elicited a transient rise, followed by sustained inhibition of Ca2+ channel activity in cell-attached patches. Low TPA concentrations predominantly reduced channel availability, while high concentrations of TPA (100 nM) transiently increased channel availability and, in addition, prolonged mean open time. The inactive 4-alpha-phorbol-12,13- didecanoate failed to affect channel activity, and pretreatment of the cells with PKC inhibitors (H-7, chelerythrine) antagonized inhibitory and stimulatory effects of TPA. Our results provide evidence for two distinct PKC-dependent mechanisms of L-type Ca2+ channel regulation in smooth muscle.

Basal dephosphorylation controls slow gating of L-type Ca2+ channels in human vascular smooth muscle.

The role of cellular phosphatase activity in regulation of smooth muscle L-type Ca2+ channels was investigated using tautomycin, a potent and specific inhibitor of serin/threonin phosphatases type 1 and 2A. Tautomycin (1-100 nM) inhibited Ca2+ channel activity in smooth muscle cells isolated from human umbilical vein. Tautomycin-induced inhibition of Ca2+ channel activity was due to a reduction of channel availability which originated mainly from prolongation of the lifetime of unavailable states of the channel. Pretreatment of smooth muscle cells with the protein kinase inhibitor H-7 (10 microM) prevented the inhibitory effect of tautomycin. Our results suggest modulation of slow gating between available and unavailable states as a mechanism of phosphorylation-dependent down-regulation of Ca2+ channels in vascular smooth muscle.

Essential role of the beta subunit in modulation of C-class L-type Ca2+ channels by intracellular pH.

Elevation of intracellular pH (pHi) enhances the activity of native L-type Ca2+ channels in cardiac and smooth muscle. We studied the modulation by pHi of expressed L-type Ca2+ channels comprised of either the alpha1c subunits alone or of alpha1c plus beta2a subunits. Ca2+ channels were expressed in human embryonic kidney cells (HEK 293) and pHi was increased from a basal level of 7.3 to 8.3 by exposure of cells to NH4Cl (20 mM) or by elevation of extracellular pH to 8.5. Elevation of pHi enhanced the activity of Ca2+ channels derived by coexpression of alpah1c and beta2a subunits. This alkalosis-induced stimulation of channel activity was mainly due to an increase in channel availability. Channels derived by expression of alpha1c alone were not affected by intracellular alkalosis. Our results demonstrate that the pHi sensitivity of L-type Ca2+ channels is conferred by the beta subunit of the channel complex.

Determination of glutamine in muscle protein facilitates accurate assessment of proteolysis and de novo synthesis-derived endogenous glutamine production.

BACKGROUND: Results of tracer studies indicate that skeletal muscle contributes to approximately 70% of overall glutamine production in healthy adults; the contribution of de novo synthesis being estimated at approximately 60%. However, measurement of the de novo synthesis rate in muscle tissue requires knowledge of the appearance rate of glutamine in plasma and the quantity of glutamine derived from intracellular proteolysis. Thus, the content of glutamine in muscle protein is a prerequisite for an accurate calculation. OBJECTIVE: The objective of the study was to measure glutamine in muscle protein. DESIGN: Muscle specimens (open biopsies) were obtained from humans (10 men and 4 women), rats (n = 4), cows (n = 4), and pigs (n = 4). Glutamine was assessed via prehydrolysis derivatization, rapid microwave-enhanced acid hydrolysis, and 5-dimethylaminonaphthalene-1-sulfonyl chloride (dansyl chloride) reversed-phase HPLC, and expressed per mg alkali-soluble protein (ASP) and DNA. RESULTS: Glutamine concentrations in muscle cell protein of various species ranged from 41 to 49 microg/mg ASP; the differences were not species related. The combined means (+/-SDs) for the 4 species were 43.6 +/- 4.9 microg/mg ASP and 11.9 +/- 2.0 mg/mg DNA, respectively. In humans, there was no apparent influence of age, sex, or BMI. CONCLUSIONS: Direct and specific measurements of glutamine in intact muscle protein were 50% lower than assumed previously. We used data compiled from earlier studies to recalculate the contributions of proteolysis and de novo synthesis to the endogenous production of glutamine in selected age groups of healthy humans; these contributions remained remarkably constant at approximately 13% and approximately 87%, respectively.

The influence of systemic growth hormone administration on the healing time of skin graft donor sites in a pig model.

A more rapid healing of skin graft donor sites has often been observed during ultimoratio therapies with growth hormone in adults who have suffered extremely severe burns. The purpose of this animal experimental study was to examine the influence of systemic growth hormone administration on the healing time of skin graft donor sites under standardized conditions in pigs. The animals were 14 (7 experimental and 7 control) male, sexually mature, German domestic pigs, in which 30 skin graft donor sites 8 cm x 4 cm and 0.6 mm deep were created. Fifteen each of the skin graft donor sites were bandaged with the same material [hydrocolloid bandage (Varihaesive E) and PVP-iodine gauze (Braunovidon Gaze)]. The test period was 15 days for each pig, whereby recombinant growth hormone (0.5 IU/kg body weight per day) was applied subcutaneously in the experimental group. The bandages were changed under brief narcosis every 2 days, during which one skin-punch biopsy was taken per skin graft donor site, and blood samples were drawn for determination of the serum IGF-1 values. Photographic documentation was also recorded. The biopsies were examined histologically (hematoxylin and eosin stain) and immunohistochemically (collagen IV and VII, and laminin), whereby histologically the start of keratinization was assessed as a healing criterion. The serum IGF-1 values in the growth hormone group were statistically significantly higher than in the control group. Immunohistochemically, a complete basal membrane was observed in both the experimental and the control group after the 7th or 8th day. A clearly elevated serum IGF-1 level correlated in the growth hormone group with the skin graft donor sites healing. It could thus be demonstrated both clinically and histologically that systemic application of growth hormone results in a statistically significantly more rapid healing of the skin graft donor sites by 2 days earlier than in the control group.

Impact of molecular analysis in the diagnosis of cutaneous lymphoid infiltrates.

The diagnosis and classification of cutaneous lymphomas is a challenge for the dermatopathologist. This is particularly true for determining the distinction between a malignant lymphoma and a benign reactive infiltrate (pseudolymphoma). Recent advances in molecular genetics, as the determination of clonality of lymphoid infiltrates, have emerged as an important tool to overcome these diagnostic dilemmas. In our experience, more than 90% of cutaneous T-cell lymphomas have a rearrangement of the T-cell receptor gamma chain gene, whereas clonal rearrangements in cutaneous T-cell pseudolymphomas could not be found. However, the demonstration of clonality does not necessarily indicate malignancy. There have been several reports that have identified clonal lymphoid proliferations in pityriasis lichenoides et varioliformis acuta, pseudolymphomas, and lichen planus. For this reason one must carefully evaluate the information that is provided by these techniques. The results should always correlate with clinical, histologic, and immunophenotypic data to achieve the correct diagnosis.

Differential effects of lipoprotein apheresis by lipidfiltration or dextran sulfate adsorption on lipidomic profile.

OBJECTIVE AND METHODS: Acute modification of plasma lipidomic profile was assessed by top-down shotgun profiling on a LTQ Orbitrap hybrid mass spectrometer in 14 patients treated with two different apheresis techniques: plasma lipidfiltration (LF) and whole blood dextran sulfate adsorption (DSA). RESULTS: Patients treated with DSA revealed a significantly more pronounced reduction of LDL-cholesterol (LDL-C), a diminished decrease of HDL-cholesterol (HDL-C) and triglycerides (TG), and a similar reduction in lipoprotein (a) (Lp(a)) level. Against the overall tendency of reduction of lipid metabolites of all lipid classes in post-apheresis plasma, independent of apheresis technology applied, a highly significant increase of phosphatidylethanolamines (PE) in response to DSA was observed. CONCLUSION: These data indicate that DSA technology may be associated with an activation or damage of blood cells at contact surface which subsequently leads to a massive liberation of cellular and membrane PE's. Pathophysiological consequences, especially with respect to coagulation system and oxidative stress, have to be further elucidated.

Is the proton radius a player in the redefinition of the International System of Units?

It is now recognized that the International System of Units (SI units) will be redefined in terms of fundamental constants, even if the date when this will occur is still under debate. Actually, the best estimate of fundamental constant values is given by a least-squares adjustment, carried out under the auspices of the Committee on Data for Science and Technology (CODATA) Task Group on Fundamental Constants. This adjustment provides a significant measure of the correctness and overall consistency of the basic theories and experimental methods of physics using the values of the constants obtained from widely differing experiments. The physical theories that underlie this adjustment are assumed to be valid, such as quantum electrodynamics (QED). Testing QED, one of the most precise theories is the aim of many accurate experiments. The calculations and the corresponding experiments can be carried out either on a boundless system, such as the electron magnetic moment anomaly, or on a bound system, such as atomic hydrogen. The value of fundamental constants can be deduced from the comparison of theory and experiment. For example, using QED calculations, the value of the fine structure constant given by the CODATA is mainly inferred from the measurement of the electron magnetic moment anomaly carried out by Gabrielse's group. (Hanneke et al. 2008 Phys. Rev. Lett. 100, 120801) The value of the Rydberg constant is known from two-photon spectroscopy of hydrogen combined with accurate theoretical quantities. The Rydberg constant, determined by the comparison of theory and experiment using atomic hydrogen, is known with a relative uncertainty of 6.6×10(-12). It is one of the most accurate fundamental constants to date. A careful analysis shows that knowledge of the electrical size of the proton is nowadays a limitation in this comparison. The aim of muonic hydrogen spectroscopy was to obtain an accurate value of the proton charge radius. However, the value deduced from this experiment contradicts other less accurate determinations. This problem is known as the proton radius puzzle. This new determination of the proton radius may affect the value of the Rydberg constant . This constant is related to many fundamental constants; in particular, links the two possible ways proposed for the redefinition of the kilogram, the Avogadro constant N(A) and the Planck constant h. However, the current relative uncertainty on the experimental determinations of N(A) or h is three orders of magnitude larger than the 'possible' shift of the Rydberg constant, which may be shown by the new value of the size of the proton radius determined from muonic hydrogen. The proton radius puzzle will not interfere in the redefinition of the kilogram. After a short introduction to the properties of the proton, we will describe the muonic hydrogen experiment. There is intense theoretical activity as a result of our observation. A brief summary of possible theoretical explanations at the date of writing of the paper will be given. The contribution of the proton radius puzzle to the redefinition of SI-based units will then be examined.

A type 2A phosphatase-sensitive phosphorylation site controls modal gating of L-type Ca2+ channels in human vascular smooth-muscle cells.

The patch-clamp technique was employed to investigate phosphorylation/dephosphorylation-dependent modulation of L-type Ca2+ channels in smooth-muscle cells isolated from human umbilical vein. Okadaic acid, an inhibitor of phosphoprotein phosphatases type 1 (PP1) and 2A (PP2A), increased the probability of channels being in the open state (Po) in intact cells. This increase in Po was due mainly to promotion of long-lasting channel openings, i.e. promotion of 'mode 2' gating behaviour. Exposure of the cytoplasmic side of excised patches of membrane to the purified catalytic subunit of PP2A (PP2Ac) resulted in the opposite modulation of channel function. PP2Ac (0.2 unit/ml) reduced the Po of Ca2+ channels mainly via suppression of 'mode 2' gating. This effect of PP2Ac was completely prevented by 1 microM okadaic acid. The catalytic subunit of PPI (0.2 unit/ml), however, barely affected channel activity. Our results provide evidence for a PP2A-sensitive regulatory site that controls modal gating of L-type Ca2+ channels in smooth muscle.

Follicular mycosis fungoides. A histopathologic analysis of nine cases.

BACKGROUND: The spectrum of mycosis fungoides is exceedingly broad. Many different variants have been described, based on both clinical appearance and histological pattern. A rare form which shows preferential infiltration of hair follicles by malignant lymphocytes is follicular mycosis fungoides. METHODS: We reviewed our experience with nine cases of follicular mycosis fungoides. RESULTS: The unifying feature was infiltration of the hair follicle epithelium by atypical lymphocytes causing varying degrees of damage to the hair follicles. In some specimens the lymphocytes displayed only minor atypia leading to a misinterpretation as pseudolymphoma. Gene rearrangement studies were particularly helpful for establishing a diagnosis of malignant lymphoma. Additionally, epidermotropism of lymphocytes, eosinophils and mucin deposition were present to varying degrees. Mucin makes the distinction from mycosis fungoides-associated follicular mucinosis difficult. We found both dermal mucin and a follicular mucinosis pattern present at different stages of disease in the same patient. CONCLUSIONS: We suggest the term mycosis fungoides-associated follicular mucinosis should be replaced by follicular mycosis fungoides in future lymphoma classification schemes.