Membrane function alterations in erythrocytes from mood disorder patients

Objectives: To examine erythrocyte membrane functions in mood disorder patients and to establish possible diagnostic marker parameter(s).Design: Collection of blood samples from mood disorder patients and age-matched control volunteers.Preparation of erythrocyte membranes for the proposed studies.Setting: Out patients / in patients, psychiatry ward, Civil Hospital, Ahmedabad, Gujarat, India, Department of Biochemistry, Faculty of Science, M.S.University of Baroda, Vadodara, Gujarat, India.Subjects: Unipolar and bipolar subjects. Control subjects (randomly selected volunteers).Results: The most significant results were a duration dependent decrease in the TPL/CHL ratio (mole:mole),changes in both the substrate and temperature kinetics properties of AChE and elevated plasma BChE activity in the mood disorder patients.Conclusion: The results suggest that the altered lipid profiles and the TPL/CHL (mole: mole) ratio and the altered temperature-dependent activity coefficients of erythrocyte membrane AChE and elevated plasma BChE activities could serve as useful diagnostic pointers for mood disorders.Keywords:Membrane function; Erythrocytes; Mood disorderSA Psych Rev 2003;6:11-2

Study of protein synthesis in rat liver mitochondria: use of cycloheximide

1. Effects of short-term and long-term administration of cycloheximide on rat liver mitochondrial protein synthesis have been examined and were found to be different. 2. Long-term administration of cycloheximide resulted in inhibition of total cellular protein synthesis including that of mitochondria while, at short-term intervals, 8–10% of mitochondrial protein synthesis was cycloheximide-resistant. 3. The inhibitory effect was also reflected in terms of protein synthesizing ability of mitochondria in vitro, the inhibition becoming apparent at 40 min and showing progressive increase with time. 4. The observed inhibition of mitochondrial protein synthesis by cycloheximide was not due to either inhibition of energy metabolism or alteration of amino-acid pool. 5. Cycloheximide did not enter mitochondria or sonic preparation under conditions in vitro. On the other hand, after administration of [3H]cycloheximide, significant quantities of the label were found to be associated with mitochondria and mitoribosomes. 6. These results indicated that cycloheximide reached the site of action in mitochondria under conditions in vivo but was unable to do so in vitro. 7. The results are discussed to elucidate the possible mechanisms involved in the inhibition of truly mitochondrial protein synthesis by cycloheximide

The significance of promitochondrial structures in rat liver for mitochondrial biogenesis

1. The heavy, light and fluffy mitochondrial fractions obtained by differential centrifugation were further characterized with respect to their protein synthesizing ability in vitro, their nucleic acid content, buoyant density of their DNA and ultrastructure. 2. The light mitochondrial fraction synthesized proteins in vitro at a rate 4-5 times as high as heavy and fluffy mitochondria. The incorporation ability of this fraction was also maximally affected by the thyroid status of the animal. The radioactivity in leucyl-tRNA of the light mitochondrial fraction was about 3-4 times as high as that of the other two fractions. 3. The heavy, light and fluffy mitochondrial fractions contained small but consistent amounts of RNA and DNA. Although the DNA content was the same in all mitochondria fractions, the light mitochondria contained relatively more RNA. The buoyant density of DNA from all the fractions was 1.701g/cm3. 4. Electron microscopy revealed that the heavy mitochondria have a typical mitochondrial architecture, with densely packed cristae and a well developed double membrane. Light mitochondria were also surrounded by double membranes, but were smaller in size and contained less cristae. The fluffy fraction consisted of a mixture of well formed mitochondria and those in the process of degradation. 5. The significance of these findings in relation to mammalian mitochondrial genesis is discussed

Effect of long-term aluminum feeding on lipid/phospholipid profiles of rat brain myelin

Effect of long-term (90–100 days) exposure of rats to soluble salt of aluminum (AlCl(3)) on myelin lipid profile was examined. The long-term exposure to AlCl(3 )resulted in a 60 % decrease in the total phospholipid (TPL) content while the cholesterol (CHL) content increased by 55 %. Consequently the TPL / CHL molar ratio decreased significantly by 62 %. The phospholipid composition of the myelin membrane changed drastically; the proportion of practically all the phospholipid classes decreased by 32 to 60 % except for phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Of the latter two, proportion of PC was unchanged while PE increased in proportion by 47 %. Quantitatively, all phospholipid classes decreased by from 42 to 76% with no change in the PE content. However the membrane fluidity was not altered in Al-treated rats. Many of the changes we observe here show striking similarities with the reported phospholipid profiles of Alzheimer brains

Compositional alterations in erythrocyte membranes in Type II diabetes

671-679Loss of erythrocyte membrane deformability is one of the most crucial factors in developing complications associated with Type II diabetes. The observed loss of erythrocyte membrane deformability could be related to structural changes in the membrane. In this context, here, we have made an attempt at gaining a better insight (quantitative as well as qualitative) into the protein and lipid contents in erythrocyte membranes and their interrelationships in Type II diabetes. Age matched control (n=12) and Type II diabetic subjects (n=22) were selected for this study. Morphological characteristics were studied by atomic force microscopy (AFM). AFM study confirmed remarkable alterations in morphology of the diabetic erythrocytes. In diabetic erythrocytes following changes were noted: (i) Significant increase in membrane as well as cytosolic proteins with a marginal increase in phospholipids content; (ii) The membrane total lipids:protein, phospholipids:protein, cholesterol:protein and phospholipids:cholesterol (mole:mole) ratios decreased significantly; (iii). A reproducible decrease in docosahexaenoic acid (DHA) and Omega-3 index with increase in Omega-6:Omega-3 ratio in membrane fatty acids; and (iv) The SDS-PAGE analysis indicated that all membrane proteins increased in almost equal proportion leading to increased membrane protein content. The observed compositional and stochiometric changes in lipids, proteins and their ratios may underlie morphological alterations and loss of deformability

Compositional alterations in erythrocyte membranes in Type II diabetes

Loss of erythrocyte membrane deformability is one of the most crucial factors in developing complications associated with Type II diabetes. The observed loss of erythrocyte membrane deformability could be related to structural changes in the membrane. In this context, here, we have made an attempt at gaining a better insight (quantitative as well as qualitative) into the protein and lipid contents in erythrocyte membranes and their interrelationships in Type II diabetes. Age matched control (n=12) and Type II diabetic subjects (n=22) were selected for this study. Morphological characteristics were studied by atomic force microscopy (AFM). AFM study confirmed remarkable alterations in morphology of the diabetic erythrocytes. In diabetic erythrocytes following changes were noted: (i) Significant increase in membrane as well as cytosolic proteins with a marginal increase in phospholipids content; (ii) The membrane total lipids:protein, phospholipids:protein, cholesterol:protein and phospholipids:cholesterol (mole:mole) ratios decreased significantly; (iii). A reproducible decrease in docosahexaenoic acid (DHA) and Omega-3 index with increase in Omega-6:Omega-3 ratio in membrane fatty acids; and (iv) The SDS-PAGE analysis indicated that all membrane proteins increased in almost equal proportion leading to increased membrane protein content. The observed compositional and stochiometric changes in lipids, proteins and their ratios may underlie morphological alterations and loss of deformability