PVA-Based Films with Strontium Titanate Nanoparticles Dedicated to Wound Dressing Application.

Bioactive materials may be applied in tissue regeneration, and an example of such materials are wound dressings, which are used to accelerate skin healing, especially after trauma. Here, we proposed a novel dressing enriched by a bioactive component. The aim of our study was to prepare and characterize poly(vinyl alcohol) films modified with strontium titanate nanoparticles. The physicochemical properties of films were studied, such as surface free energy and surface roughness, as well as the mechanical properties of materials. Moreover, different biological studies were carried out, like in vitro hemo- and cyto-compatibility, biocidal activity, and anti-biofilm formation. Also, the degradation of the materials' utilization possibilities and enzymatic activity in compost were checked. The decrease of surface free energy, increase of roughness, and improvement of mechanical strength were found after the addition of nanoparticles. All developed films were cyto-compatible, and did not induce a hemolytic effect on the human erythrocytes. The PVA films containing the highest concentration of STO (20%) reduced the proliferation of Eschericha coli, Pseudomonas aeruginosa, and Staphylococcus aureus significantly. Also, all films were characterized by surface anti-biofilm activity, as they significantly lowered the bacterial biofilm abundance and its dehydrogenase activity. The films were degraded by the compost microorganism. However, PVA with the addition of 20%STO was more difficult to degrade. Based on our results, for wound dressing application, we suggest using bioactive films based on PVA + 20%STO, as they were characterized by high antibacterial properties, favorable physicochemical characteristics, and good biocompatibility with human cells.

Hyaluronic acid/tannic acid films for wound healing application.

In this study, thin films based on hyaluronic acid (HA) with tannic acid (TA) were investigated in three different weight ratios (80HA/20TA, 50HA/50TA, 20HA/80TA) for their application as materials for wound healing. Surface free energy, as well as their roughness, mechanical properties, water vapor permeability rate, and antioxidant activity were determined. Moreover, their compatibility with blood and osteoblast cells was investigated. The irritation effect caused by hyaluronic acid/tannic acid films was also considered with the use of are constructed human epidermis model. The irritation effect for hyaluronic acid/tannic acid films by the in vitro method was also studied. The low surface free energy, surface roughness, and antioxidant activity presented by the obtained films were examined. All the tested compositions of hyaluronic acid/tannic acid films were hemocompatible, but only films based on 50HA/50TA were fully cytocompatible. Regarding the potential implantation, all the films except 80HA/20TA showed appropriate mechanical properties. The specimens did not exert the irritation effect during the studies involving reconstructed human epidermis.

Cold plasma treatment of tannic acid as a green technology for the fabrication of advanced cross-linkers for bioactive collagen/gelatin hydrogels.

Tannic acid (TA) is a natural compound studied as the cross-linker for biopolymers due to its ability to form hydrogen bonds. There are different methods to improve its reactivity and effectiveness to be used as a modifier for biopolymeric materials. This work employed plasma to modify tannic acid TA, which was then used as a cross-linker for fabricating collagen/gelatin scaffolds. Plasma treatment did not cause any significant changes in the structure of TA, and the resulting oxidized TA showed a higher antioxidant activity than that without treatment. Adding TA to collagen/gelatin scaffolds improved their mechanical properties and stability. Moreover, the obtained plasma-treated TA-containing scaffolds showed antibacterial properties and were non-hemolytic, with improved cytocompatibility towards human dermal fibroblasts. These results suggest the suitability of plasma treatment as a green technology for the modification of TA towards the development of advanced TA-crosslinked hydrogels for various biomedical applications.

Evaluating Gelatin-Based Films with Graphene Nanoparticles for Wound Healing Applications.

In this study, gelatin-based films containing graphene nanoparticles were obtained. Nanoparticles were taken from four chosen commercial graphene nanoplatelets with different surface areas, such as 150 m2/g, 300 m2/g, 500 m2/g, and 750 m2/g, obtained in different conditions. Their morphology was observed using SEM with STEM mode; porosity, Raman spectra and elemental analysis were checked; and biological properties, such as hemolysis and cytotoxicity, were evaluated. Then, the selected biocompatible nanoparticles were used as the gelatin film modification with 10% concentration. As a result of solvent evaporation, homogeneous thin films were obtained. The surface's properties, mechanical strength, antioxidant activity, and water vapor permeation rate were examined to select the appropriate film for biomedical applications. We found that the addition of graphene nanoplatelets had a significant effect on the properties of materials, improving surface roughness, surface free energy, antioxidant activity, tensile strength, and Young's modulus. For the most favorable candidate for wound dressing applications, we chose a gelatin film containing nanoparticles with a surface area of 500 m2/g.

Gelatin and gelatin/starch-based films modified with sorbitol for wound healing.

Gelatin-based films modified with sorbitol were produced from gelatin solution or gelatin/starch blends using a simple and low-cost solvent casting method, and subsequently, their physicochemical, mechanical, and biocompatibility properties were characterized. This work focused on developing and optimizing a biopolymeric blend to improve the pure biopolymers' properties for potential biomedical applications such as wound dressing. The films were characterized in terms of morphology and transparency, mechanical, moisture and swelling properties, thermal stability, and degradation potential. Moreover, hemocompatibility, as well as cytocompatibility of prepared films, were examined. The addition of sorbitol contributed to improving mechanical properties, swelling reduction, and increasing biostability over time. The cytocompatibility of obtained films was confirmed in vitro with two different human cell lines, fibroblastic and osteoblastic, and a more favorable cellular response was received for fibroblasts. Further, in hemocompatibility studies, it was found that all films may be classified as non-hemolytic as they did not have a negative effect on the human erythrocytes. The obtained results indicate the great potential of the gelatin/starch blends modified with sorbitol as regenerative biomaterials intended for wound healing applications.

The characterization of collagen-based scaffolds modified with phenolic acids for tissue engineering application.

The aim of the experiment was to study the morphology of collagen-based scaffolds modified by caffeic acid, ferulic acid, and gallic acid, their swelling, and degradation rate, as well as the biological properties of scaffolds, such as antioxidant activity, hemo- and cytocompatibility, histological observation, and antibacterial properties. Scaffolds based on collagen with phenolic acid showed higher swelling rate and enzymatic stability compared to scaffolds based on pure collagen, and the radical scavenging activity was in the range 85-91%. All scaffolds were non-hemolytic and compatible with surrounding tissues. Collagen modified by ferulic acid showed potentially negative effects on hFOB cells as a significantly increased LDH release was found, but all of the studied materials had antimicrobial activity against Staphylococcus aureus and Escherichia coli. It may be assumed that phenolic acids, such as caffeic, ferulic, and gallic acid, are modifiers and provide novel biological properties of collagen-based scaffolds. This paper provides the summarization and comparison of the biological properties of scaffolds based on collagen modified with three different phenolic acids.

Effects of Marginal Zn Excess and Thiamine Deficiency on Microglial N9 Cell Metabolism and Their Interactions with Septal SN56 Cholinergic Cells.

Mild thiamine deficiency aggravates Zn accumulation in cholinergic neurons. It leads to the augmentation of Zn toxicity by its interaction with the enzymes of energy metabolism. Within this study, we tested the effect of Zn on microglial cells cultivated in a thiamine-deficient medium, containing 0.003 mmol/L of thiamine vs. 0.009 mmol/L in a control medium. In such conditions, a subtoxic 0.10 mmol/L Zn concentration caused non-significant alterations in the survival and energy metabolism of N9 microglial cells. Both activities of the tricarboxylic acid cycle and the acetyl-CoA level were not decreased in these culture conditions. Amprolium augmented thiamine pyrophosphate deficits in N9 cells. This led to an increase in the intracellular accumulation of free Zn and partially aggravated its toxicity. There was differential sensitivity of neuronal and glial cells to thiamine-deficiency-Zn-evoked toxicity. The co-culture of neuronal SN56 with microglial N9 cells reduced the thiamine-deficiency-Zn-evoked inhibition of acetyl-CoA metabolism and restored the viability of the former. The differential sensitivity of SN56 and N9 cells to borderline thiamine deficiency combined with marginal Zn excess may result from the strong inhibition of pyruvate dehydrogenase in neuronal cells and no inhibition of this enzyme in the glial ones. Therefore, ThDP supplementation can make any brain cell more resistant to Zn excess.

Resveratrol Inhibits Metabolism and Affects Blood Platelet Function in Type 2 Diabetes.

Chronic hyperglycemia contributes to vascular complications in diabetes. Resveratrol exerts anti-diabetic and anti-platelet action. This study aimed to evaluate the effects of resveratrol on metabolism and the function of blood platelets under static and in in vitro flow conditions in patients with type 2 diabetes. Blood obtained from 8 healthy volunteers and 10 patients with type 2 diabetes was incubated with resveratrol and perfused over collagen-coated capillaries. Isolated blood platelets were incubated with resveratrol and activated by collagen to assess platelet function, metabolism, ATP release, TXA2 production, lipid peroxidation, and gluthatione content. In the type 2 diabetes group, plasma glucose and fructosamine concentrations were significantly higher than in the healthy group. In in vitro studies, collagen-induced thrombi formation in the blood of diabetic patients was 33% higher than in the healthy group. Resveratrol reduced thrombi by over 50% in the blood of healthy and diabetic patients. TXA2 production was 47% higher in diabetic platelets than in the healthy group. Resveratrol reduced TXA2 release by 38% in healthy platelets and by 79% in diabetic platelets. Resveratrol also reduced the activities of enzymes responsible for glycolysis and oxidative metabolism in the platelets of both groups. These data indicate that the resveratrol-induced inhibition of platelet metabolism and TXA2 release may lead to a reduction of platelet function and thrombus formation in patients with type 2 diabetes. Therefore, resveratrol may be beneficial to prevent vascular complications as a future complementary treatment in aspirin-resistant diabetic patients.

Chronology and dynamics of fluvial style changes in the Younger Dryas and Early Holocene in Central Europe (lower San River, SE Poland).

Reconstruction of fluvial style changes in the San River in the Subcarpathian Basins is based on geomorphological and sedimentological analyses. The time control of alluvial fills and temporal changes in the river channel are derived from radiocarbon and optically stimulated luminescence dating combined with independent pollen-based biochronostratigraphy. The results showed that the alluvial plain of the braided (BR) or braided-meandering (BR-M?) river was abandoned before 12,800 cal BP. Large meanders (LM) were cut off in the older part of the Younger Dryas (YD; ca. 12,600 cal BP), and in the younger part of this period (ca. 12,450 cal BP). The small meanders (SM) developed at the end of the YD and were abandoned at the onset of the Preboreal (PB; ca.11,550 cal BP). The erosion phase at the YD-PB transition, reported from many valleys in Central Europe, was not confirmed in the study area. The full cycle of San River channel transformation (BR (BR-M?) → LM → SM); was estimated to be approximately 1200 years. According to the palynological data, open pine forests with birch that survived from the end of the Allerød dominated the landscape of the river valley during the YD cooling and did not undergo major changes during the warming in the early PB. Therefore, we assume that the influence of vegetation changes in the San River channel pattern transformation was nonsignificant. The location of the studied palaeochannels in the floodbasin filled with silty clayey deposits may have influenced the formation of relatively narrow and deep channels, than that of much the wider and shallower meanders from the YD, situated several kilometres downstream of the surveyed sites.

Protection of Cholinergic Neurons against Zinc Toxicity by Glial Cells in Thiamine-Deficient Media.

Brain pathologies evoked by thiamine deficiency can be aggravated by mild zinc excess. Cholinergic neurons are the most susceptible to such cytotoxic signals. Sub-toxic zinc excess aggravates the injury of neuronal SN56 cholinergic cells under mild thiamine deficiency. The excessive cell loss is caused by Zn interference with acetyl-CoA metabolism. The aim of this work was to investigate whether and how astroglial C6 cells alleviated the neurotoxicity of Zn to cultured SN56 cells in thiamine-deficient media. Low Zn concentrations did not affect astroglial C6 and primary glial cell viability in thiamine-deficient conditions. Additionally, parameters of energy metabolism were not significantly changed. Amprolium (a competitive inhibitor of thiamine uptake) augmented thiamine pyrophosphate deficits in cells, while co-treatment with Zn enhanced the toxic effect on acetyl-CoA metabolism. SN56 cholinergic neuronal cells were more susceptible to these combined insults than C6 and primary glial cells, which affected pyruvate dehydrogenase activity and the acetyl-CoA level. A co-culture of SN56 neurons with astroglial cells in thiamine-deficient medium eliminated Zn-evoked neuronal loss. These data indicate that astroglial cells protect neurons against Zn and thiamine deficiency neurotoxicity by preserving the acetyl-CoA level.

Pulsed Radiofrequency Neuromodulation Contributes to Activation of Platelet-Rich Plasma in In Vitro Conditions.

OBJECTIVES: Recent years have brought new developments in interventional chronic pain management, namely regenerative orthopedics utilizing platelet-rich plasma (PRP) as well as further evolution of pulsed radiofrequency neuromodulation (PRF). Both methods have been used separately. Here, we investigated whether PRF may potentiate the activation of platelets in PRP samples when both these techniques are combined together in in vitro conditions. MATERIALS AND METHODS: Studies were performed on concentrated PRP samples (PRPs) obtained from acid citrate dextrose-treated blood taken from 11 healthy volunteers. PRPs were divided into four groups: 1) nonactivated PRP; 2) thrombin-activated PRP as a positive control for maximal platelets activation; 3) PRF-treated PRP exposed for 20 min to PRF energy generated by neurotherm radio frequency generator at 500 kHz, with a voltage of 40 V and maximal temperature of 42°C; and 4) a combination of groups 2 and 3. RESULTS: PRF-induced platelet activation measured by platelet factor 4 (PF4) and ATP release from PRPs was significantly higher compared to nonactivated PRPs, and similar to PF4 and ATP release from thrombin-activated PRPs. Thrombin activation did not potentiate PF4 release in PRF samples and even reduced ATP level. Additionally, PRF neither induced any platelet membrane damage measured by lactic dehydrogenase release from PRP nor modified any platelets viability or metabolism measured by MTT. CONCLUSIONS: We confirmed that PRF may activate PRP without additional platelet activators. So, a combination of both methods PRF and PRP application may provide a more effective opportunity for tissue regeneration in dentistry, surgery, dermatology, or in orthopedics.

Aggravated effects of coexisting marginal thiamine deficits and zinc excess on SN56 neuronal cells.

Objectives: Zinc excitotoxicity and thiamine pyrophosphate deficiency (TD) are known pathogenic signals contributing to mechanism of different encephalopathies through inhibition of enzymes responsible for energy metabolism such as pyruvate dehydrogenase, aconitase or ketoglutarate dehydrogenase. The aim of this work was to investigate whether subclinical Zn excess and TD, frequent in aging brain, may combine yielding overt neuronal impairment.Results: Clonal SN56 cholinergic neuronal cells of septal origin were used as the model of brain cholinergic neurons, which are particularly susceptible to neurodegeneration in the course of Alzheimer's disease, hypoxia and other dementia-linked brain pathologies. Neither subtoxic concentration of Zn (0.10 mM) nor mild 20-25% TD deficits alone caused significant negative changes in cultured cholinergic neurons viability and their acetyl-CoA/acetylcholine metabolism. However, cells with mild TD accumulated Zn in excess, which impaired their energy metabolism causing a loss of neurons viability and their function as neurotransmitters. These negative effects of Zn were aggravated by amprolium which is an inhibitor of thiamine intracellular transport.Conclusion: Our data indicate that TD may amplify otherwise non-harmful border-line Zn excitotoxic signals yielding progress of neurodegeneration.

The Impact of Acetyl-CoA and Aspartate Shortages on the N-Acetylaspartate Level in Different Models of Cholinergic Neurons.

N-acetylaspartate is produced by neuronal aspartate N-acetyltransferase (NAT8L) from acetyl-CoA and aspartate. In cholinergic neurons, acetyl-CoA is also utilized in the mitochondrial tricarboxylic acid cycle and in acetylcholine production pathways. While aspartate has to be shared with the malate-aspartate shuttle, another mitochondrial machinery together with the tricarboxylic acid cycle supports the electron transport chain turnover. The main goal of this study was to establish the impact of toxic conditions on N-acetylaspartate production. SN56 cholinergic cells were exposed to either Zn2+ overload or Ca2+ homeostasis dysregulation and male adult Wistar rats' brains were studied after 2 weeks of challenge with streptozotocin-induced hyperglycemia or daily theophylline treatment. Our results allow us to hypothesize that the cholinergic neurons from brain septum prioritized the acetylcholine over N-acetylaspartate production. This report provides the first direct evidence for Zn2+-dependent suppression of N-acetylaspartate synthesis leading to mitochondrial acetyl-CoA and aspartate shortages. Furthermore, Zn2+ is a direct concentration-dependent inhibitor of NAT8L activity, while Zn2+-triggered oxidative stress is unlikely to be significant in such suppression.

Inhibition of pyruvate dehydrogenase complex activity by 3-bromopyruvate affects blood platelets responses in type 2 diabetes.

BACKGROUND: Hyperactivation of blood platelets is an essential factor in the pathomechanism of diabetes-evoked angiopathies. The aim of this work was to investigate whether blood platelets hyperactivation resulting from type 2 diabetic hyperglycaemia-increased pyruvate dehydrogenase complex activity and excessive acetyl-CoA accumulation may be brought to the normal range by the enzyme inhibitors. METHODS: Platelets were isolated from the blood of 9 type 2 diabetic patients and 10 healthy donors. Effects of 3-bromopyruvate and 3-nitropropionate on pyruvate dehydrogenase complex (PDHC) and succinate dehydrogenase activities, as well as levels of acetyl-CoA, ATP, thiobarbituric acid reactive species and aggregation were assessed in non-activated and thrombin-activated platelets. RESULTS: In type 2 diabetic patients fasting plasma glucose and fructosamine levels were 61 and 64% higher, respectively, than in the healthy group (p < 0.001). In non-activated diabetic platelets PDHC activity, PDHC-E2, acetyl-CoA and ATP levels were 66, 70, 68 and 60%, higher, respectively, than in platelets from healthy controls (p < 0.01). 3-bromopyruvate (0.1 mM) decreased pyruvate dehydrogenase activity in healthy and diabetic platelets by 42% and 59%, respectively. Similar inhibitory effects were observed for acetyl-CoA and ATP levels, aggregation and TBARS accumulation rates. Succinate dehydrogenase activity was inhibited by 3-nitropropionate (10 mM) to 38 and 41% of control values in healthy and diabetic platelets, respectively, but affected neither function nor acetyl-CoA metabolism in platelets of both groups. CONCLUSIONS: These data indicate that inhibition of pyruvate dehydrogenase excessive activity in diabetic platelets by 3-bromopyruvate may normalise their functional parameters through adjustment of acetyl-CoA/ATP levels to control values. Platelets from blood of diabetic patients display higher activities of pyruvate dehydrogenase complex (PDHC), higher levels of dihydrolipoate transacetylase (DLAT, E2 subunit of PDHC) as well as higher levels of acetyl-CoA yielding greater ATP/ADP accumulation than in platelets of normoglycemic subjects. Therefore, in diabetic platelets, thrombin caused higher release of ATP/ADP triggering excessive production of reactive oxygen species (ROS) and stronger aggregation compared to control platelets. In diabetic platelets, relative excess of DLAT in PDHC made them highly susceptible to 3-bromopyruvate (3BrP) inhibition. Resulting limitation of acetyl-CoA provision by 3-BrP normalised activity of diabetic platelets.

Antibacterial Activity and Cytocompatibility of Bone Cement Enriched with Antibiotic, Nanosilver, and Nanocopper for Bone Regeneration.

Bacterial infections due to bone replacement surgeries require modifications of bone cement with antibacterial components. This study aimed to investigate whether the incorporation of gentamicin or nanometals into bone cement may reduce and to what extent bacterial growth without the loss of overall cytocompatibility and adverse effects in vitro. The bone cement Cemex was used as the base material, modified either with gentamicin sulfate or nanometals: Silver or copper. The inhibition of bacterial adhesion and growth was examined against five different bacterial strains along with integrity of erythrocytes, viability of blood platelets, and dental pulp stem cells. Bone cement modified with nanoAg or nanoCu revealed greater bactericidal effects and prevented the biofilm formation better compared to antibiotic-loaded bone cement. The cement containing nanoAg displayed good cytocompatibility without noticeable hemolysis of erythrocytes or blood platelet disfunction and good viability of dental pulp stem cells (DPSC). On the contrary, the nanoCu cement enhanced hemolysis of erythrocytes, reduced the platelets aggregation, and decreased DPSC viability. Based on these studies, we suggest the modification of bone cement with nanoAg may be a good strategy to provide improved implant fixative for bone regeneration purposes.

Increased prevalence of tumour infiltrating immune cells in oropharyngeal tumours in comparison to other subsites: relationship to peripheral immunity.

BACKGROUND: The nature of the tumour microenvironment immune response in head and neck cancer patients has an important role in tumour development and metastasis, but it is unknown if this differs between cancer subsites or whether it is related to the peripheral immune response. METHODS: Immune cells (CD4, CD8, Foxp3) in head and neck squamous cell carcinoma tissue (HNSCC; n = 66), detected by immunohistochemistry, have been correlated with tumour subsite and immune cells in the peripheral circulation (CD4(+)CD25(High)Foxp3(+) Treg and CD4(+) T cells), identified using flow cytometry. RESULTS: Oropharyngeal tumours had a greater number of infiltrating immune cells in both tumour and stroma compared with other subsites, but no difference was observed in the circulating levels. Immune cells in the stroma were positively related to those in the tumour with consistently higher levels in stroma. A strong relationship was found between the number of CD4(+) and Foxp3(+) cells but not between the number of CD8(+) and Foxp3(+) cells in the tumour. The number of Foxp3(+) cells within the tumour was positively correlated with the percentage of circulating CD4(+)CD25(High) cells positive for Foxp3. Late stage laryngeal tumours showed a higher number of Foxp3(+) lymphocytes compared with early stage malignancies, and oropharyngeal tumours had more CD4(+) cells in node negative tumours compared with node positive ones. CONCLUSION: The level of immune cell infiltration in head and neck squamous cell carcinoma appears to be subsite dependent residing primarily in the stroma and is likely to be dependent on the peripheral immune response.

Effect of treatment on systemic cytokines in head and neck squamous cell carcinoma patients.

The aim of this study was to determine the effect of HNSCC tumour treatment on systemic Th1 and Th2 cytokine levels and investigate correlations with clinicopathological parameters. IL2, IL4, IL5, IL6, IL8, IL10, IL13, GMCSF, IFNγ and TNFα were measured in the serum of 101 newly-presenting HNSCC patients (9 oral cavity, 27 oropharynx, 57 laryngopharynx, 1 sinonasal, 1 parotid and 6 unknown), prior to and following treatment, using a Quantibody(®) array based multiplex sandwich ELISA (Raybiotech). Data were analysed with respect to T stage, nodal status, age and sex of the patient as well as time between collection of pre- and post-treatment serum. A significant decrease in the levels of the Th2 cytokines IL4, IL5, IL6 and IL10 and the Th1 cytokines IL2 and IL8 was observed between the pre- and post-treatment serum samples. IL13 and TNFα were significantly higher in early stage (T1/T2) tumours compared with late stage (T3/T4) and this trend was maintained for nodal involvement. IL4 was higher in node positive patients compared with node negative, whereas the converse was true for IL2; IL4 was also higher in younger patients compared with the older age group. These results suggest that removal of HNSCC tumours from patients results in reduced circulating Th2 cytokines without a concurrent increase in Th1 cytokines, indicative of a partial rebalance of the Th1/Th2 system following treatment. Furthermore the cytokine profile may be influenced by the size and nodal involvement of the tumour.

Alterations of adenine nucleotide metabolism and function of blood platelets in patients with diabetes.

Increased activity of blood platelets contributes to vascular complications in patients with diabetes. The aim of this work was to investigate whether persisting hyperglycemia in diabetic patients generates excessive accumulation of ATP/ADP, which may underlie platelet hyperactivity. Platelet ATP and ADP levels, thiobarbituric acid-reactive species synthesis, and aggregation of platelets from patients with diabetes were 18-82% higher than in platelets from healthy participants. In patients with diabetes, platelet stimulation with thrombin caused about two times greater release of ATP and ADP than in the healthy group while decreasing intraplatelet nucleotide content to similar levels in both groups. This indicates that the increased content of adenylate nucleotides in the releasable pool in the platelets of diabetic patients does not affect their level in metabolic cytoplasmic/mitochondrial compartments. Significant correlations between platelet ATP levels and plasma fructosamine, as well as between platelet ATP/ADP and platelet activities, have been found in diabetic patients. In conclusion, chronic hyperglycemia-evoked elevations of ATP/ADP levels and release from blood platelets of patients with diabetes may be important factors underlying platelet hyperactivity in the course of the disease.

Effect of L-carnitine on acetyl-CoA content and activity of blood platelets in healthy and diabetic persons.

BACKGROUND: Excessive blood platelet activity contributes to vascular complications in diabetic persons. Increased acetyl-CoA in platelets from diabetic persons has been suggested to be a cause of this hyperactivity. We therefore investigated whether L-carnitine, which up-regulates metabolism of acetyl-CoA in muscles and brain, may affect platelet function in healthy and diabetic individuals. METHODS: We obtained platelets from healthy and diabetic persons and measured acetyl-CoA concentrations, malonyl dialdehyde (MDA) synthesis, and platelet aggregation in the absence and presence of L-carnitine. Activities of selected enzymes involved in glucose and acetyl-CoA metabolism were also assessed. RESULTS: Fasting glucose, fructosamine, and hemoglobin A1c were present in significantly higher amounts in the blood of diabetic patients than in healthy individuals. Activities of carnitine acetyltransferase, glucose-6-phosphate dehydrogenase, oxoglutarate dehydrogenase, and fatty acid synthase were 17%-62% higher in platelets from diabetic patients. Mitochondrial acetyl-CoA was increased by 98% in platelets from diabetic patients, MDA synthesis was increased by 73%, and platelet aggregation by 60%. L-Carnitine had no or only a slight effect on these indices in platelets from healthy individuals, but in platelets from diabetic patients, L-carnitine caused a 99% increase in acetyl-CoA in the cytoplasmic compartment along with increases in MDA synthesis and platelet aggregation. CONCLUSIONS: Excessive platelet activity in persons with diabetes may result from increased acetyl-CoA, which apparently increases synthesis of lipid activators of platelet function. L-Carnitine may aggravate platelet hyperactivity in diabetic persons by increasing the provision of surplus acetyl-CoA to the cytoplasmic compartment.