[Hair growth with dupilumab in alopecia areata universalis and atopic dermatitis]. / Haarwachstum unter Dupilumab bei Alopecia areata universalis und atopischer Dermatitis.

We report the case of a 46-year-old woman who has suffered from severe atopic dermatitis since early childhood and from alopecia areata totalis since she was 18 years old, which has now developed into alopecia areata universalis. After the introduction of therapy with the monoclonal antibody dupilumab, renewed hair growth of the scalp, face and lower legs was observed. Dupilumab blocks the α­subunit of interleukin (IL)-4 receptor and prevents the signaling cascade of IL­4 and IL-13. This leads to a reduction of Th2 immune response. The severe eczema and itching with difficulties falling and staying asleep decreased after just 14 days. The patient tolerates the drug without significant side effects and has a significantly improved quality of life. Patients with severe atopic dermatitis and alopecia areata could benefit twice from the use of dupilumab in the future.

Induction of coiling in tendrils by auxin and carbon dioxide.

Symmetric application of indole-3-acetic acid, CO(2), or, to a lesser extent, ethylene can substitute for the contact stimulus in inducing coiling in the tendrils of Marah fabaceus. In the case of auxin, treatment of the apical few millimeters results in strong, permanent coiling throughout the length of the tendril. The speed of the response to CO(2) is comparable to that to tactile stimuli. A possible mechanism for thigmotropism is outlined.

Sustained net CO2 evolution during photosynthesis by marine microorganisms.

BACKGROUND: Many aquatic photosynthetic microorganisms possess an inorganic-carbon-concentrating mechanism that raises the CO2 concentration at the intracellular carboxylation sites, thus compensating for the relatively low affinity of the carboxylating enzyme for its substrate. In cyanobacteria, the concentrating mechanism involves the energy-dependent influx of inorganic carbon, the accumulation of this carbon--largely in the form of HCO3(-)-in the cytoplasm, and the generation of CO2 at carbonic anhydrase sites in close proximity to the carboxylation sites. RESULTS: During measurements of inorganic carbon fluxes associated with the inorganic-carbon-concentrating mechanism, we observed the surprising fact that several marine photosynthetic microorganisms, including significant contributors to oceanic primary productivity, can serve as a source of CO2 rather than a sink during CO2 fixation. The phycoerythrin-possessing cyanobacterium Synechococcus sp. WH7803 evolved CO2 at a rate that increased with light intensity and attained a value approximately five-fold that for photosynthesis. The external CO2 concentration reached was significantly higher than that predicted for chemical equilibrium between HCO3- and CO2, as confirmed by the rapid decline in the CO2 concentration upon the addition of carbonic anhydrase. Measurements of oxygen exchange between water and CO2, by means of stable isotopes, demonstrated that the evolved CO2 originated from HCO3- taken up and converted intracellularly to CO2 in a light-dependent process. CONCLUSIONS: We report net, sustained CO2 evolution during photosynthesis. The results have implications for energy balance and pH regulation of the cells, for carbon cycling between the cells and the marine environment, and for the observed fractionation of stable carbon isotopes.

Low Activation State of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase in Carboxysome-Defective Synechococcus Mutants.

The high-CO2-requiring mutant of Synechococcus sp. PCC 7942, EK6, was obtained after extension of the C terminus of the small subunit of ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (Rubisco). The carboxysomes in EK6 were much larger than in the wild type, but the cellular distribution of the large and small sub-units of Rubisco was not affected. The kinetic parameters of in vitro-activated Rubisco were similar in EK6 and in the wild type. On the other hand, Rubisco appeared to be in a low state of activation in situ in EK6 cells pretreated with an air level of CO2. This was deduced from the appearance of a lag phase when carboxylation was followed with time in cells permeabilized by detergent and subsequently supplied with saturating CO2 and RuBP. Pretreatment of the cells with high CO2 virtually abolished the lag. After low-CO2 treatment, the internal RuBP pool was much higher in mutant cells than in the wild-type cells; pretreatment with high CO2 reduced the pool in mutant cells. We suggest that the high-CO2-requiring phenotype in mutants that possess aberrant carboxysomes arises from the inactivated state of Rubisco when the cells are exposed to low CO2.

Quantitative evaluation of the role of a putative CO2-scavenging entity in the cyanobacterial CO2-concentrating mechanism.

This paper assesses the contribution of a postulated CO2-scavenging system to the efficient operation of the CO2-concentrating mechanism (CCM) in cyanobacteria. A quantitative model for the CCM is presented which incorporates an energy-dependent carbonic anhydrase-like entity located at or near the inner surface of the plasma membrane. This entity, which converts CO2 to HCO3- against the thermodynamic potential, scavenges CO2 leaking outward from the carboxysomes, and, further, converts CO2 entering from the medium to HCO3-, thus maintaining an inward diffusion gradient along which CO2 enters passively. The model resembles our earlier models in postulating that CO2 and HCO3- are not at equilibrium throughout the greater part of the cell, and that CO2 is generated in high concentration at carbonic anhydrase sites within the carboxysomes. The model further takes into account the concentric thylakoid membranes which surround the carboxysomes, and events in the periplasmic space and the unstirred layer surrounding the cell. Implications of the predicted steady state fluxes of CO2 and HCO3-, and of their steady state concentrations in various cellular compartments, are discussed. The plasma membrane carbonic anhydrase-like activity lowers the photosynthetic Km for external Ci, as well as decreasing the inorganic C 'leak', but it may not save on energy expenditure.

[Persistent chylothorax after fracture of the 12th thoracic vertebrae]. / Persistierender Chylothorax nach Fraktur des 12. Brustwirbelkörpers.

We report on a patient who suffered chylothorax 2 months after she had undergone internal fixation of a fracture of her 12th thoracic vertebral body. The pleural effusion was treated by insertion of a chest tube. The chylothorax was managed conservatively. The patient received protein-rich nutrition supplemented with medium-chain triglycerides. As the volume of chylous fluid drained from the pleura had not decreased after 2 weeks, the patient received total parenteral nutrition without any oral intake of calories. Chest X-rays documented the disappearance of the chylothorax. Reexpansion of the lungs was noted, and the costophrenic sinuses could be clearly visualised.

Mechanism of effect of aging on membrane transport in leaf strips of Centranthus ruber: Possible ethylene involvement in cutting shock.

Cerulenin has been used to investigate the mechanism by which leaf strips of Centranthus ruber (L.) Lam et D.C. increase their capacity for solute uptake during a period of incubation in CaSO4 ("aging"). α-Aminoisobutyric acid was used to assess uptake capability. The leaf strips developed their uptake capacity for at least 8-10 h after excision. Cerulenin, if added to the aging medium immediately after cutting or at any time during the aging process, almost completely halted this development, but did not bring about loss of the uptake capacity already achieved. That cerulenin was specifically interfering with fatty-acid biosynthesis was indicated by the fact that it drastically depressed incorporation of labelled acetate into the lipid fraction but did not affect the incorporation of labelled alanine. Cycloheximide strongly inhibited the development of uptake capacity, but sensitivity to actinomycin D was not evident for at least 2 h. The results are consistent with the concept that slicing leads to immediate damage to tissue membranes and that "aging" is a process of membrane repair, involving renewed synthesis of membrane lipids and membrane proteins.The damage to membranes associated with cutting may involve wound ethylene. This is indicated by the following findings: Treatment of aged leaf strips with Ethrel (2-chloroethylphosphonic acid) resulted in drastic loss of their acquired uptake capacity. The strips recovered from such Ethrel-induced loss of uptake capacity while aging in CaSO4 as they can after cutting. Cerulenin halted recovery of uptake capacity after ethrel treatment just as it did after cutting. Treatment of leaves before cutting with amino-ethoxyvinylglycine somewhat improved the uptake performance of leaf strips immediately after excision.

Membrane transport of sugars and amino acids in isolated protoplasts.

A method has been developed for observing membrane transport in isolated protoplasts. Transport of sugars and amino acids has been studied in protoplasts isolated from the mesophyll of Pisum sativum L. That uptake was not due to passive diffusion through damaged membranes was demonstrated by supplying simultaneously two sugar stereoisomers, the one (3)H-labeled and the other (14)C-labeled. The protoplast membranes were sufficiently functional to discriminate strongly between these stereoisomers.To characterize transport the nonmetabolized glucose analogue 3-O-methyl glucose (MeG) and amino acid analogue alpha-aminoisobutyric acid (AIB) were employed. When uptake was compared per unit of protein as between leaf strips and protoplasts prepared from the same tissue, it was estimated that the protoplasts had retained approximately 40 to 50% of the uptake ability of the whole cells. Uptake of neither MeG nor AIB by protoplasts was linear with time, but the tendency to flatten was more marked for AIB. Addition of Mg-ATP to buffered medium significantly promoted AIB uptake, an effect not ascribable to either chelation or pH. Transport of both MeG and AIB was markedly pH-dependent, uptake falling with rise in pH.The stimulatory effect of Mg-ATP and the pH dependence confirm that uptake was not due to a diffusional inward "leak" but involved membrane function.This work demonstrates the feasibility of using isolated protoplasts for membrane transport studies. The potential advantages of using protoplasts for such studies are pointed out.

Reduction in Turgor Pressure as a Result of Extremely Brief Exposure to CO(2).

CO(2) depresses water influx into sunflower hypocotyl segments of low water potential; by contrast, it stimulates flux into segments of high water potential. When segments of high potential were placed in a series of mannitol concentrations and allowed to achieve steady rates of water uptake, influx into CO(2)-treated tissue in a solution of 3 atm equalled that into control tissue in water. Reasons are given for deducing that a change in internal osmotic concentration (pi(i)) of the order of 40% would be necessary to account for this result on the basis of pi(i). Direct measurements (by cryoscopy and by the minimum volume method) detected no difference in the steady state value for pi(i) as between CO(2)-treated and control tissue. It was therefore concluded that CO(2) had caused some reduction in turgor pressure.Water uptake into tissue treated with CO(2) for only the first 2 minutes of a 30-minute period was equal to that into tissue treated continuously with CO(2), i.e. 3 times the control value. Ten seconds' CO(2) treatment produced a significant stimulation. When the cycles of treatment were repeated the samples receiving flashes of CO(2) maintained a rate of water uptake superior to that of the control, whereas influx into continuously treated tissue fell below the control value after 1 hour.CO(2) treatment applied in a moist air chamber stimulated subsequent water influx when the tissue was transferred to water. Fifteen seconds' treatment was sufficient to produce a marked effect. Even when a transition period of 30 minutes in the moist chamber was interposed between CO(2) treatment (5 minutes) and transfer to water, a stimulation was observed. The CO(2) effect could be achieved at zero degrees; 5 minutes' treatment in the moist chamber at zero degrees, followed by a 15-minute transition period at the same temperature, substantially increased subsequent water uptake at 25 degrees .

Transport of 3-o-Methylglucose Into and Out of Storage Cells of Daucus carota.

The movement of labeled 3-o-methylglucose (MeG) into and out of thin carrot discs has been followed in order to gain information on sugar entry and exit mechanisms. Little or no metabolism of this derivative appears to occur in the tissue, since no products were detected either by chromatography or by analysis of respiratory CO(2).The curve relating entry to external concentration deviated somewhat from a rectangular hyperbola but suggested a carrier mechanism. Glucose and MeG each competitively inhibited the uptake of the other. K(i) for MeG was estimated to be 3 times the K(m) for its uptake.When discs incubated in MeG were transferred to H(2)O, MeG lost to the solution from the Free Space was re-absorbed against a 7-fold concentration gradient.The addition of unlabeled MeG or glucose to the medium surrounding discs which had been maintaining a ratio of internal to external MeG of 75:1 brought about release of stored isotope. This was probably not due to exchange diffusion stricto sensu.Efflux of previously absorbed isotopic MeG into a medium containing unlabeled MeG or glucose was temperature-sensitive. The kinetics of efflux were complex and did not suggest a simple diffusion process related to overall MeG content. However there is evidence (including the falling rate of exit with time) that slow diffusion (or slow release from adsorption) contributed substantially to efflux. The source of this flow appeared to be neither the readily accessible Free Space nor the main storage compartment. Calculation indicated that the volume of this "slow diffusion compartment" might be about 1% of the total volume of the discs.

The "acid growth effect" and geotropism.

The curvature developed by segments of sunflower hypocotyl exposed to gravitational stimulus was enhanced in buffer solutions between pH 3.4 and 4.0 in the absence of added auxin. This effect was observed both when the segments were submerged during the stimulus and when they floated near the surface of the solution. 5-10 min in a horizontal position was sufficient to induce subsequent curvature.Straight growth of the segments was also promoted in buffers of this pH range.The acid effect on curvature was insensitive to KAsO2, HgCl2 and cycloheximide, inhibitors which drastically reduced auxin-induced curvature. Furthermore, acid buffer, but not auxin, restored the ability of segments taken from etiolated and "starved" plants to respond to gravity. These results suggest that the polarisation following gravistimulus may not be resticted to the asymmetric distribution of auxin and auxin co-factors but may involve a general physiological asymmetry.

Loss of membrane transport ability in leaf cells and release of protein as a result of osmotic shock.

Osmotic shock severely reduces the ability of aged strips of Phaseolus vulgaris leaves to take up alpha-aminoisobutyric acid, an amino acid analogue which is known to be transported by a specific mechanism. Cold osmotic shock, i.e., transfer from 0.5 m sucrose at 25 C to H(2)O at 2 C, decreases alpha-aminoisobutyric acid uptake almost to zero. Substitution of 10(-3)m ethylenediaminetetraacetate for the sucrose, i.e., treatment which does not involve plasmolysis, produces a similar, but less severe, effect.About 3.5% of the total cell protein is released as a result of cold osmotic shock, by far the greater proportion being liberated into the water during the second stage of the shock treatment. Ethylenediaminetetraacetate and other shock treatments also bring about protein release, and the amount released is correlated with degree of depression of subsequent alpha-aminoisobutyric acid uptake.Shock tissue is capable of recovering a large proportion of its uptake capacity during subsequent immersion in 10(-4)m CaSO(4).Separate estimation of alpha-aminoisobutyric acid influx and efflux showed that the marked effect of shock on net flux is largely attributable to a reduction in influx, and not to an increase in efflux. This and other results indicate that the shock effect on net flux is not due to nonspecific damage to membranes bringing about "leakiness."The fact that alpha-aminoisobutyric acid uptake is reduced to near zero by treatment which allows the cells to retain over 95% of their protein suggests that the shock phenomenon is analogous to that in bacteria, and that the small fraction of protein lost may be closely involved in the transport mechanism.

Energization of the sugar transport mechanism in the plasmalemma of isolated mesophyll protoplasts.

The mechanism of 3-O-methyl-d-glucose transport through the plasmalemma has been investigated in protoplasts isolated from the mesophyll of Pisum sativum L. var. Dan.Analysis of the fluxes after 50 minutes of uptake showed that the gradual decrease in slope of the net uptake curve with time was not due to any decline in uptake capacity; it represented the approach to flux equilibrium of a small compartment of the protoplast, probably the cytoplasm.The energy of activation for initial flux into this compartment was 20 kilocalories per mole between 17 and 27 C. Very high discrimination was shown with regard to sugar isomers. Light strongly promoted flux (by a factor of 2.5 in the case of methyl glucose). Initial flux showed sharply contrasting inhibitor sensitivity in the light and the dark. Light uptake was sensitive to the proton conductor carbonyl cyanide m-chlorophenylhydrazone (CCCP), but stable for at least the first 10 minutes to the ATPase inhibitors quercetin, rutin, and diethylstilbestrol, as well as to arsenate. Dark uptake, on the other hand, was stable to CCCP but was immediately depressed by quercetin, rutin, diethylstilbestrol, and arsenate.Protoplasts which received a light pretreatment before incubation in the dark took up methyl glucose at the accelerated light rate for the first 7 minutes. Moreover, the light pretreatment sensitized subsequent initial dark uptake to CCCP, and conferred on it the stability to ATPase inhibitors and arsenate characteristic of light uptake. After about 7 minutes the characteristic inhibitor responses of dark uptake were resumed.It is proposed that more than one mode of energy-coupling for sugar transport may operate in these protoplasts.

Evidence for Mediated HCO(3) Transport in Isolated Pea Mesophyll Protoplasts.

The kinetics of (14)C fixation, and inorganic C (C(inorg)) accumulation, have been followed in isolated pea mesophyll protoplasts. NaH(14)CO(3) was supplied to the protoplasts in media the pH of which was varied between 7 and 8.When (14)CO(2) fixation was plotted against the calculated concentration of free CO(2) in the media, the apparent K(m) for CO(2) was observed to rise as external pH increased. The V(max) did not alter significantly. Similarly, when C(inorg) uptake, either in the light or in the dark, was plotted against external CO(2) concentration the slope of the curves was steeper at higher external pH.Investigation of the time course of uptake showed that internal C(inorg) concentration rose throughout the experimental period, and that in the light it surpassed the external C(inorg) concentration after about 3 minutes. Irradiation of protoplasts previously taking up (14)C(inorg) in the dark brought about a sharp increase in the rate of (14)C(inorg) accumulation which was sustained for at least 20 minutes.Estimates of internal pH based on the distribution of labeled 5,5-dimethyloxazoladine-2,4-dione (DMO) between protoplast and medium suggested that internal pH altered relatively little with change in external pH. The values for internal pH as calculated from C(inorg) distribution were always higher than those calculated from DMO distribution, i.e. the internal C(inorg) concentration was higher than would be predicted on the assumption of passive distribution in accordance with pH.Addition of carbonic anhydrase to the external solution was without effect either on rate of (14)CO(2) fixation or C(inorg) accumulation.Various possible interpretations of the results are considered. It is concluded that the most reasonable explanation, consistent with all the data, is that HCO(3) (-) ions can cross the protoplast membranes, and that their passage is mediated by a transfer mechanism.

Nature of the rate-limiting step in the supply of inorganic carbon for photosynthesis in isolated asparagus mesophyll cells.

Accumulation of acid-stable and acid-labile C has been studied in cells isolated from cladophylls of Asparagus sprengeri regel, as a function of the concentrations of the various inorganic C (C(i)) species in the external medium.The rate of CO(2) fixation was higher when C(i) was supplied as CO(2) as opposed to HCO(3) (-), at the same concentration. Participation of HCO(3) (-) was indicated when the external CO(2) and HCO(3) (-) concentrations were chosen such that, owing to interconversion between C(i) species, the same CO(2) concentrations would be reached at a certain point in time, regardless of which species was supplied initially; at this point, a higher fixation rate was observed in the case of HCO(3) (-) supply.In the presence of carbonic anhydrase, the apparent affinity for C(i) was raised. This enzyme raised fixation rate even under steady-state conditions, but only at limiting external C(i) concentrations. The decrease in external CO(2) concentration was correlated with a decreasing internal C(i) level when CO(2) was the species supplied.When 10 mum CO(2) was supplied initially fixation rate was almost independent of pH. However, when HCO(3) (-) was supplied at concentrations calculated to yield 10 mum CO(2) at equilibrium, fixation rate rose with pH. Carbonic anhydrase raised the fixation rate over the entire pH range when HCO(3) (-) was the species supplied.It is concluded that CO(2) was the major C(i) species permeating from the medium to the carboxylating site. Further, our results bring clear evidence that formation of CO(2) from HCO(3) (-) in the unstirred layer, and the diffusion of both species in this layer, rate limit CO(2) fixation by these isolated cells.

Hysteresis in the responses of membrane potential, membrane resistance, and growth rate to cyclic temperature change.

Measurements of electrical potential, membrane resistance, and elongation rate have been carried out on the developing pollen tube of Oenothera drummondii.The plasmalemma potential was observed to be -138 millivolts +/- 19 (sd). Approximately 70% of this potential was apparently due to the operation of an electrogenic pump(s). KCN rapidly and reversibly depolarized the potential to about -40 millivolts. Lowering the temperature from 20 to 4 C brought about similar rapid depolarization. The effects of KCN and of temperature were in no degree additive. KCN had only a small effect on membrane resistance. In contrast, the latter was markedly increased by lowering the temperature.When the pollen tubes were submitted to cyclic temperature changes striking hysteresis effects were observed in the response of all three parameters, membrane potential, resistance, and growth rate. The hysteresis pattern for potential differed from that for resistance but resembled that for growth rate (measured simultaneously on the same pollen tube). The correlation coefficient between potential and growth rate was very high.The probable relevance to our results of the hysteresis phenomena associated with "clustering" and phase transition in lipids is pointed out. Attention is also drawn to the possible significance of the large difference between the electric potentials at the start of the cooling and heating paths, respectively.

Direct evidence for a sugar transport mechanism in isolated vacuoles.

Sugar transport has been directly observed in isolated higher plant vacuoles for the first time. The latter were released from protoplasts isolated from the mesophyll of Pisum sativum L.Uptake of l-glucose by the vacuoles was very slight in comparison with that of the d-glucose analog 3-O-methyl glucose (MeG), indicating, first, that a highly selective sugar uptake mechanism is seated in the tonoplast; and, second, that the mechanism was functioning in the isolated vacuoles.MeG uptake was markedly sensitive to the pH of the medium, falling as the external pH rose. Addition of MgATP to buffered medium strongly promoted MeG uptake by vacuoles, but not by the protoplasts from which they were released. Treatment with the proton ionophore SF(6847) drastically reduced uptake by the vacuoles, but had a lesser effect on uptake by the protoplasts. The inhibitory effect of SF(6847) on uptake by the vacuoles was countered to a substantial degree by the addition of MgATP.The influence of pH, the stimulatory effect of ATP, and the ATP-reversible inhibition by SF(6847) all strengthen the conclusion that the observed sugar uptake reflected membrane function and was not due to a diffusional inward leak through damaged membranes.The results are discussed in the light of currently held concepts regarding the driving force for sugar transport.

Is modulation of the rate of proton pumping a key event in osmoregulation?

The net uptake of 3-O-methylglucose into leaf segments obtained from Senecio mikanioides Otto, and net proton efflux from the segments, were both promoted when the osmotic potential of the medium was decreased by addition of mannitol, sorbitol, or polyethylene glycol (optimal osmolarity, 0.3 Osmolar for mannitol and sorbitol). The effect was not due to promotion of ;aging', since the antibiotic cerulenin suppressed aging without reducing the size of the mannitol stimulation; further, mannitol did not accelerate aging. Neither was the effect ascribable to diminished efflux (i.e. reduced ;leak' because: first, visualization of the unidirectional sugar fluxes by double labeling indicated that the effect of added osmoticum was to promote influx rather than to reduce efflux; second, compartment analysis did not suggest any effect of mannitol on the rate constants for efflux from either the slowly equilibrating or more rapidly equilibrating compartment. The effect was not specific to poly-ols since it was also obtained with betaine and choline chloride. Since methyl glucose is not taken up into the phloem it could not be ascribed to a turgor effect on phloem loading. We conclude that the effect may reflect osmoregulation. As the sugar flux is probably driven by protonmotive force, it is likely that the effects on proton flux and on sugar flux are related. We suggest that the plasmalemma-sited proton pump is sensitive to the hydrostatic pressure gradient across the plasmalemma-cell wall complex, and functions both as detector and as effector in osmoregulation.

[Differential diagnosis of left-sided thoracic venous catheters: case report of a persistent left superior vena cava]. / Differenzialdiagnose linksthorakaler Venenkatheter am Beispiel einer persistierenden linken oberen Hohlvene.

The differential diagnosis of left-sided thoracic central venous catheters is discussed in context with the cannulation of a persistent left superior vena cava. In this case the catheter tip was seen lying to the left of the spine on frontal chest X-ray. In addition to the descending aorta, differential diagnoses are a persistent left-sided superior vena cava as well as other smaller veins such as the left internal thoracic vein, the left superior intercostal vein, or the pericardiophrenic vein. The misplacement of a venous catheter in a pericardiophrenic vein may result in a fatal pericardial tamponade.