Decreased water permeability of erythrocyte membranes in patients with Duchenne muscular dystrophy

In-cell NMR: Why and how?

NMR spectroscopy has been applied to cells and tissues analysis since its beginnings, as early as 1950. We have attempted to gather here in a didactic fashion the broad diversity of data and ideas that emerged from NMR investigations on living cells. Covering a large proportion of the periodic table, NMR spectroscopy permits scrutiny of a great variety of atomic nuclei in all living organisms non-invasively. It has thus provided quantitative information on cellular atoms and their chemical environment, dynamics, or interactions. We will show that NMR studies have generated valuable knowledge on a vast array of cellular molecules and events, from water, salts, metabolites, cell walls, proteins, nucleic acids, drugs and drug targets, to pH, redox equilibria and chemical reactions. The characterization of such a multitude of objects at the atomic scale has thus shaped our mental representation of cellular life at multiple levels, together with major techniques like mass-spectrometry or microscopies. NMR studies on cells has accompanied the developments of MRI and metabolomics, and various subfields have flourished, coined with appealing names: fluxomics, foodomics, MRI and MRS (i.e. imaging and localized spectroscopy of living tissues, respectively), whole-cell NMR, on-cell ligand-based NMR, systems NMR, cellular structural biology, in-cell NMR… All these have not grown separately, but rather by reinforcing each other like a braided trunk. Hence, we try here to provide an analytical account of a large ensemble of intricately linked approaches, whose integration has been and will be key to their success. We present extensive overviews, firstly on the various types of information provided by NMR in a cellular environment (the "why", oriented towards a broad readership), and secondly on the employed NMR techniques and setups (the "how", where we discuss the past, current and future methods). Each subsection is constructed as a historical anthology, showing how the intrinsic properties of NMR spectroscopy and its developments structured the accessible knowledge on cellular phenomena. Using this systematic approach, we sought i) to make this review accessible to the broadest audience and ii) to highlight some early techniques that may find renewed interest. Finally, we present a brief discussion on what may be potential and desirable developments in the context of integrative studies in biology.

Alteration of phospholipids in the blood of patients with Duchenne muscular dystrophy (DMD): in vitro, high resolution 31P NMR-based study

In vitro, high-resolution ³¹P NMR (Nuclear Magnetic Resonance) spectroscopy-based analysis of phospholipids in serum is well recognized in leukemia, lymphoma, non-hematological cancers and renal cell carcinoma. In context of these studies, phospholipids were analyzed in blood of thirty-two (n = 32) patients with Duchenne muscular dystrophy (DMD) (Age, Mean ± SD; 8.0 ± 1.6 years) and sixteen (n = 16) healthy subjects (Age, Mean ± SD; 8.6 ± 2.3 years). Quantity of phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS) and lyso-phosphatidylcholine (Lys-PC) was significantly higher (p < 0.05) in DMD patients as compared to healthy subjects. There were no significant differences (p > 0.05) observed for the quantity of phospholipids in blood of gene deletion positive cases of DMD as compared to negative gene deletion cases of DMD. Quantity of phospholipids in negative gene deletion cases of DMD patients as well as DMD cases with positive gene deletion was significantly higher (p < 0.05) as compared to normal individuals. The present study distinguishes the patients with DMD from the healthy subjects on the basis of the quantity of phospholipids in blood. These observations may be useful in future for the development of new diagnostic method of DMD.

Comparative studies of water permeability of red blood cells from humans and over 30 animal species: an overview of 20 years of collaboration with Philip Kuchel

NMR measurements of the diffusional permeability of the human adult red blood cell (RBC) membrane to water (P(d)) and of the activation energy (E(a,d)) of the process furnished values of P(d) ~ 4 × 10(-3) cm/s at 25 °C and ~6.1 × 10(-3) cm/s at 37 °C, and E(a,d) ~ 26 kJ/mol. Comparative NMR measurements for other species showed: (1) monotremes (echidna and platypus), chicken, little penguin, and saltwater crocodile have the lowest P(d) values; (2) sheep, cow, and elephant have P(d) values lower than human P(d) values; (3) cat, horse, alpaca, and camel have P(d) values close to those of humans; (4) guinea pig, dog, dingo, agile wallaby, red-necked wallaby, Eastern grey kangaroo, and red kangaroo have P(d) values higher than those of humans; (5) mouse, rat, rabbit, and "small and medium size" marsupials have the highest values of P(d) (>8.0 × 10(-3) cm/s at 25 °C and >10.0 × 10(-3) cm/s at 37 °C). There are peculiarities of E(a,d) values for the RBCs from different species. The maximum inhibition of diffusional permeability of RBCs induced by incubation with p-chloromercuribenzene sulfonate varied between 0% (for the chicken and little penguin) to ~50% (for human, mouse, cat, sheep, horse, camel, and Indian elephant), and ~60-75% (for rat, guinea pig, rabbit, dog, alpaca, and all marsupials). These results indicate that no water channel proteins (WCPs) or aquaporins are present in the membrane of RBCs from monotremes (echidna, platypus), chicken, little penguin and saltwater crocodile whereas WCPs from the membranes of RBCs from marsupials have peculiarities.

Water channel proteins (later called aquaporins) and relatives: past, present, and future

Water channels or water channel proteins (WCPs) are transmembrane proteins that have a specific three-dimensional structure with a pore that can be permeated by water molecules. WCPs are large families (over 450 members) that are present in all kingdoms of life. The first WCP was discovered in the human red blood cell (RBC) membrane in 1980s. In 1990s other WCPs were discovered in plants, microorganisms, various animals, and humans; and it became obvious that the WCPs belong to the superfamily of major intrinsic proteins (MIPs, over 800 members). WCPs include three subfamilies: (a) aquaporins (AQPs), which are water specific (or selective water channels); (b) aquaglyceroporins (and glycerol facilitators), which are permeable to water and/or other small molecules; and (c) "superaquaporins" or subcellular AQPs. WCPs (and MIPs) have several structural characteristics which were better understood after the atomic structure of some MIPs was deciphered. The structure-function relationships of MIPs expressed in microorganisms (bacteria, archaea, yeast, and protozoa), plants, and some multicellular animal species [nematodes, insects, fishes, amphibians, mammals (and humans)] are described. A synthetic overview on the WCPs from RBCs from various species is provided. The physiological roles of WCPs in kidney, gastrointestinal system, respiratory apparatus, central nervous system, eye, adipose tissue, skin are described, and some implications of WCPs in various diseases are briefly presented. References of detailed reviews on each topic are given. This is the first review providing in a condensed form an overview of the whole WCP field that became in the last 20 years a very hot area of research in biochemistry and molecular cell biology, with wide and increasing implications.

Brain function in Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is the second most commonly occurring genetically inherited disease in humans. It is an X-linked condition that affects approximately one in 3300 live male births. It is caused by the absence or disruption of the protein dystrophin, which is found in a variety of tissues, most notably skeletal muscle and neurones in particular regions of the CNS. Clinically DMD is characterized by a severe pathology of the skeletal musculature that results in the premature death of the individual. An important aspect of DMD that has received less attention is the role played by the absence or disruption of dystrophin on CNS function. In this review we concentrate on insights into this role gained from investigation of boys with DMD and the genetically most relevant animal model of DMD, the dystrophin-deficient mdx mouse. Behavioural studies have shown that DMD boys have a cognitive impairment and a lower IQ (average 85), whilst the mdx mice display an impairment in passive avoidance reflex and in short-term memory. In DMD boys, there is evidence of disordered CNS architecture, abnormalities in dendrites and loss of neurones, all associated with neurones that normally express dystrophin. In the mdx mouse, there have been reports of a 50% decrease in neurone number and neural shrinkage in regions of the cerebral cortex and brainstem. Histological evidence shows that the density of GABA(A) channel clusters is reduced in mdx Purkinje cells and hippocampal CA1 neurones. At the biochemical level, in DMD boys the bioenergetics of the CNS is abnormal and there is an increase in the levels of choline-containing compounds, indicative of CNS pathology. The mdx mice also display abnormal bioenergetics, with an increased level of inorganic phosphate and increased levels of choline-containing compounds. Functionally, DMD boys have EEG abnormalities and there is some preliminary evidence that synaptic function is affected adversely by the absence of dystrophin. Electrophysiological studies of mdx mice have shown that hippocampal neurones have an increased susceptibility to hypoxia. These recent findings on the role of dystrophin in the CNS have implications for the clinical management of boys with DMD.

In vivo tritium contamination effects on water exchange across the erythrocyte membranes: a nuclear magnetic resonance study

The effects produced by chronic in vivo tritium contamination on the process of water diffusion across the rat erythrocyte membranes were investigated using an NMR relaxation method. As the level of tritium intake increased, an inhibition of the water permeability was observed, reaching values of 40% for corresponding absorbed doses of about 100 mGy. The activation energy of the transport process was also significantly increased, suggesting that the mechanism of the water diffusion across the membrane had changed.

Water transport in human red cells: effects of 'non-inhibitory' sulfhydryl reagents

The water diffusional permeability of human red blood cells following exposure to various sulfhydryl group (SH) reagents have been studied using a nuclear magnetic resonance technique. Exposure of red blood cells up to 12 mM N-ethylmaleimide (NEM) or 10 mM 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNE) alone does not affect water diffusion. In contrast, when DTNB treatment follows a preincubation of the cells with NEM, a small (18% at 37 degrees C) but significant inhibition of water permeability occurs. The NEM and DTNB treatment of the cells caused no change of the cell shape and volume or of the cell water volume. Consequently, the inhibition observed after NEM and DTNB treatment has a real significance.

Study on the erythrocytes from myotonic dystrophy with multi-nuclear NMR

We have studied the water permeability through membranes, the function of the Na pump, and glucose metabolism of erythrocytes of patients with myotonic muscular dystrophy (MyD) using 1H--, 23Na, and 13C-NMR techniques. A significant decrease in water permeability was recognized in the MyD erythrocyte membrane, and impaired Na pumping was suspected to be correlated with the former biochemical abnormalities in band III protein of MyD erythrocyte membrane. Significant acceleration of glycolysis in the erythrocyte for the first 160 minutes was also recognized in MyD; however, the production of lactate showed no difference between MyD and controls. The increased glucose uptake in MyD may be compensatory to the diminished pumping mechanism, but further information, such as inorganic phosphate permeability and the activity of the rate-limiting enzyme of erythrocyte glycolysis, is needed.

The effects of the extracellular manganese concentration and variation of the interpulse delay time in the CPMG sequence on water exchange time across erythrocyte membranes

There has been broad disagreement in the literature regarding the dependence of water exchange times (Te) across erythrocyte membranes studied by the 1H-NMR Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence on extracellular Mn2+ concentration. While some workers saw no change in Te with Mn2+, others reported a 35-50% decrease in Te with this extracellular paramagnetic relaxation agent. We present 1H-NMR evidence that a 30-50% change in Te can be produced by interdependence of the interpulse delay time of the CPMG pulse sequence and the external Mn2+ concentration. Such a large dependency is interpreted in terms of the diffusional effect as a major source. However, it is shown experimentally that if a large number of refocusing pi pulses are used, the observed transverse relaxation times are unaffected by Mn2+. Under these conditions excellent agreement of Te obtained in our study (13.0 +/- 0.64 ms (N = 36) at 21 degrees C) and that of 12.8 +/- 3.6 ms at 20-23 degrees C reported by the radiotracer method was found. Our findings suggest new and important implications for evaluating the previous reports of the 1H-NMR CPMG method concerning the [Mn2+] effect in the decrease of Te, and provide conditions where studies of water transport across erythrocyte membranes using this magnetic resonance method can be used with confidence.

On measuring the diffusional water permeability of human red blood cells and ghosts by nuclear magnetic resonance

The characteristics of water diffusional permeability (P) of human red blood cells were studied on isolated erythrocytes and ghosts by a doping nuclear magnetic resonance technique. In contrast to all previous investigations, systematic measurements were performed on blood samples obtained from a large group of donors. The mean values of P ranged from 2.2 X 10(-3) cm.s-1 at 5 degrees C to 8.1 X 10(-3) cm.s-1 at 42 degrees C. The reasons for some of the discrepancies in the permeability coefficients reported by various authors were found. In order to estimate the basal permeability, the maximal inhibition of water diffusion was induced by exposure of red blood cells to p-chloromercuribenzenesulfonate (PCMBS) under various conditions (concentration, duration, temperature). The lowest values of P were around 1.3 X 10(-3) cm.s-1 at 20 degrees C, 1.6 X 10(-3) cm.s-1 at 25 degrees C, 1.9 X 10(-3) cm.s-1 at 30 degrees C and 3.2 X 10(-3) cm.s-1 at 37 degrees C. The results reported here represent the largest series of determinations of water diffusional permeability of human red blood cells (without or with exposure to mercurials) available in the literature, and consequently the best estimates of the characteristics of this transport process. The values of P can be taken as references for the studies of water permeability in various cells or in pathological conditions.

The basal permeability to water of human red blood cells evaluated by a nuclear magnetic resonance technique

The characteristics of water diffusional permeability (P) of human red blood cells were studied on isolated erythrocytes by a doping nuclear magnetic resonance technique. In order to estimate the basal permeability the maximal inhibition of water diffusion was induced by exposure of red blood cells to p-chloromercuribenzene sulfonate (PCMBS) under various conditions (concentration, duration, temperature). The lowest values of P were around 0.7 X 10(-3) cm s-1 at 10 degrees C, 1.2 X 10(-3) cm s-1 at 15 degrees C, 1.4 X 10(-3) cm s-1 at 20 degrees C, 1.8 X 10(-3) cm s-1 at 25 degrees C, 2.1 X 10(-3) cm s-1 at 30 degrees C and 3.5 X 10(-3) cm s-1 at 37 degrees C. The mean value of the activation energy of water diffusion (Ea,d) was 25 kJ/mol for control and 43.7 kJ/mol for PCMBS--inhibited erythrocytes. The values of P and Ea,d obtained after induction of maximal inhibition of water diffusion by PCMBS can be taken as references for the basal permeability to water of the human red blood cell membrane.

Studies of water permeability and proteins of erythrocyte membranes in patients with Duchenne muscular dystrophy

The characteristics of water permeability of erythrocytes from 54 Duchenne muscular dystrophy (DMD) patients and age-matched controls have been determined by a pulse nuclear magnetic resonance (NMR) technique. A decreased permeability of erythrocyte membrane in DMD was definitely found at all temperatures between 15 and 42 degrees C, with normal values for the activation energy of water diffusion. No differences between DMD and control subjects in the pattern of erythrocyte membrane polypeptides separated by two-dimensional electrophoresis could be detected. The findings are discussed in relation to the molecular mechanisms of water diffusion across erythrocyte membrane and the problem of erythrocyte membrane abnormalities in DMD. A new interpretation of erythrocyte membrane alterations is proposed based on the recent findings regarding the molecular pathology of DMD.

Brain morphology in Duchenne muscular dystrophy: a Golgi study

Intellectual impairment associated with Duchenne muscular dystrophy is well recognized, although no consistent anatomic central nervous system lesions have been reported. The autopsy findings of 13 patients, ages 13-18 years, were reviewed. Intelligence quotients, ascertained in 5 patients, ranged from 46-79. Gross and microscopic examinations of brain and spinal cord revealed no consistent pattern of abnormalities. Neuropathology included neuronal loss and gliosis in spinal gray matter and tegmental brainstem, extensive Purkinje cell loss, mononuclear perivascular cuffing with cortical and subcortical gliosis, and cerebral heterotopia. Quantitative analysis of rapid Golgi impregnations of the visual cortex revealed significantly reduced dendritic length and branching of apical and basal dendrites from pyramidal neurons in 1 patient and less striking attenuation of dendritic arborization in 2 others. The literature suggests that the intellectual deficit in Duchenne muscular dystrophy is nonprogressive and unrelated to age or severity of muscle disease, although performance intelligence quotient may deteriorate with progressive muscle weakness. Golgi analysis suggested that abnormal dendritic development and arborization may underlie intellectual impairment. Although the pathogenesis of the cellular defect is not fully known, the coexistence of central nervous system and muscle pathology raises the possibility of a common molecular mechanism.

Effects of temperature on water diffusion in human erythrocytes and ghosts--nuclear magnetic resonance studies

The temperature-dependence of water diffusion across human erythrocyte membrane was studied on isolated erythrocytes and resealed ghosts by a doping nuclear magnetic resonance technique. The conclusions are the following: (1) The storage of suspended erythrocytes at 2 degrees C up to 24 h or at 37 degrees C for 30 min did not change the water exchange time significantly, even if Mn2+ was present in the medium. This indicates that no significant penetration of Mn2+ is taking place under such conditions. (2) In case of cells previously incubated at 37 degrees C for longer than 30 min with concentrations of p-chloromercuribenzene sulfonate (PCMBS) greater than 0.5 mM, the water-exchange time gradually decreased if the cells were stored in the presence of Mn2+ for more than 10 min at 37 degrees C. (3) When the Arrhenius plot of the water-exchange time was calculated on the basis of measurements performed in such a way as to avoid a prolonged exposure of erythrocytes to Mn2+ no discontinuity occurred, regardless of the treatment with PCMBS. (4) No significant differences between erythrocytes and resealed ghosts regarding their permeability and the activation energy of water diffusion (Ea,d) were noticed. The mean value of Ea,d obtained on erythrocytes from 35 donors was 24.5 kJ/mol. (5) The value of Ea,d increased after treatment with PCMBS, in parallel with the percentage inhibition of water diffusion. A mean value of 41.3 kJ/mol was obtained for Ea,d of erythrocytes incubated with 1 mM PCMBS for 60 min at 37 degrees C and 28.3 kJ/mol for ghosts incubated with 0.1 mM PCMBS for 15 min, the values of inhibition being 46% and 21% respectively.

Water exchange through erythrocyte membranes: nuclear magnetic resonance studies on resealed ghosts compared to human erythrocytes

The water diffusion across human erythrocyte membrane has been studied on intact cells and resealed ghosts by a doping NMR technique. Although the water exchange time of ghosts was longer than that of erythrocytes, no significant differences in their diffusional permeability were noticed for temperatures in the range 2-43 degrees C. Contrary to what was previously noticed in erythrocytes, no significant increase in the water exchange time of ghosts in the acid range of pH occurred.