Acoustic reciprocity of spatial coherence in ultrasound imaging.

A conventional ultrasound image is formed by transmitting a focused wave into tissue, time-shifting the backscattered echoes received on an array transducer, and summing the resulting signals. The van Cittert-Zernike theorem predicts a particular similarity, or coherence, of these focused signals across the receiving array. Many groups have used an estimate of the coherence to augment or replace the B-mode image in an effort to suppress noise and stationary clutter echo signals, but this measurement requires access to individual receive channel data. Most clinical systems have efficient pipelines for producing focused and summed RF data without any direct way to individually address the receive channels. We describe a method for performing coherence measurements that is more accessible for a wide range of coherence-based imaging. The reciprocity of the transmit and receive apertures in the context of coherence is derived and equivalence of the coherence function is validated experimentally using a research scanner. The proposed method is implemented on a commercial ultrasound system and in vivo short-lag spatial coherence imaging is demonstrated using only summed RF data. The components beyond the acquisition hardware and beamformer necessary to produce a real-time ultrasound coherence imaging system are discussed.

Serum nitric oxide metabolites in patients with multiple sclerosis.

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system characterized by myelin breakdown. The free radical nitric oxide (NO), which is considered to be a major metabolite in immune function and in autoimmune disorders, is among the possible mediators causing the inflammatory reactions in MS. Consequently, NO has been implicated in the pathogenesis of MS and its animal model experimental allergic encephalomyelitis (EAE). In this study, stable metabolites of NO (NO(2-)+NO(3-)) levels were determined in sera of MS patients (n=23) and control subjects (n=16). NO(2-)+NO(3-) levels were higher in MS patients when compared to control subjects. However, there was not any correlation with serum NO(2-)+NO(3-) values and clinical features of the disease such as duration of sickness, the time elapsed from the last attack and EDSS values. Our results imply that nitric oxide may be involved in the pathogenesis of MS although further studies are required to elucidate underlying mechanisms.

The urinary excretion of glycosaminoglycans and heparan sulphate in lupus nephritis.

Renal involvement in systemic lupus erythematosus (SLE) affects the disease outcome. In order to advance the diagnosis and the initiation of therapy, non-invasive diagnostic techniques are required. In this study, urinary glycosaminoglycans (GAG) and heparan sulphate (HS) were measured in 26 patients with biopsy-proven lupus nephritis and compared to 16 healthy controls. Uronic acid as a representative of GAGs in urine was determined spectrophotometrically with the meta-hydroxydiphenyl, following acid treatment. HS was determined as hexosamine by the method of Smith and Gilkerson. The median values of GAG (3.99 mg/g crea./day) and HS (2.41 mg/g crea./day) in patients were significantly ( P = 0.001) higher than in the control group (1.98 and 0.87, respectively). There was a positive correlation between GAG and HS values ( P = 0.000, r = 0.924) in SLE patients. There were no differences in HS excretion, microalbuminuria and SLE-DAI scores between different classes of lupus nephritis. However, GAG values in class 3 nephritis were significantly ( P = 0.033) higher than from both class 2 and class 4 lupus nephritis. There were no differences in all the measured parameters between normoalbuminuric, microalbuminuric and macroproteinuric patients. Furthermore, there were no correlations between GAG, HS excretions and SLE-DAI scores or microalbuminuria. These results suggest that urinary GAG and HS may serve as useful, independent and non-invasive markers of lupus nephritis.

The effects of melatonin on the antioxidant systems in experimental spinal injury.

Melatonin has been recently shown by various in-vivo and in-vitro studies to exert potent neutralising effects on hydroxyl radicals, stimulate glutathione peroxidase (GSH-Px) activity, and protect catalase (CAT) from the destructive activity of hydroxyl radicals in neural tissue. We aimed to investigate the possible effects of pharmacological dose of melatonin on some of the antioxidant defence systems in an in-vivo study of experimental spinal injury. Seven groups of adult male Sprague Dawley rats were used in the following scheme: Group I: Naive (n = 6), Group II: Lesion (n = 8), Group III: Melatonin (n = 5), Group IV: Melatonin + Lesion (n = 8), Group V: Placebo + Lesion (n = 5), Group VI: Sham operation (n = 5), and Group VII: Placebo (n = 5). Experimental spinal injury was induced at level T7-T8 by 5 sec compression of the total cord with an aneurysm clip on anaesthetised and laminectomized animals. The total 10 mg/kg dose of melatonin (Sigma) dissolved in alcohol-water was administered i.p. four times in 2.5 mg/kg doses, at 20 min pre-, at the time of and at 1 h and 2h post-compression. At 24 +/- 2h post-injury, the rats were euthanized and the lesioned segments of cord were dissected and homogenised with special care taken to distribute equal amount of injured tissue in each sample for analysis of reduced glutathione (GSH), oxidised glutathione (GSSG), superoxide dismutase (SOD), and CAT activity. Compression injury decreased GSH/GSSG ratio significantly (p < .0001). Melatonin, by itself, significantly decreased GSSG content (p < .05) and increased CAT activity (p < .05) in the naïve rats. Melatonin treatment decreased GSSG activity, thus elevating GSH/GSSG ratio, and also increased SOD and CAT activity without reaching statistical significance in the lesioned animals. In conclusion, pharmacological dose of systemically applied melatonin seemed to support some features of the antioxidant defence systems in our hands.

The effects of chronic hepatitis C and B virus infections on liver reduced and oxidized glutathione concentrations.

The aim of this study was to evaluate the effects of hepatitis B and C virus infections on liver glutathione status. Reduced and oxidized glutathione levels were determined in liver biopsy specimens obtained from patients with chronic liver disease including chronic active hepatitis and cirrhosis. In patients with hepatitis B virus infections, GSH and GSH/GSSG levels were significantly low compared with those in controls (P<0.01). There was a significant negative correlation between histological activity indices (HAI) and hepatic GSSG levels only in patients with chronic HCV infection (P<0.01; r=-0.895). In addition to this, we also found a positive correlation between indices (HAI) and GSH/GSSG of the same group (r=0.915; P<0.05). These observations suggest that HBV and HCV infections have different effects on liver glutathione status based on diverse mechanisms.

Increased cerebrospinal fluid and serum nitrite and nitrate levels in amyotrophic lateral sclerosis.

Abnormal glutamate metabolism is implied in the pathogenesis of Amyotrophic Lateral Sclerosis (ALS) and cerebrospinal fluid (CSF) glutamate levels appear to be elevated. Since nitric oxide (NO) inhibits glutamate transport, excessive amounts of nitric oxide could underlie the glutamate induced neurotoxicity in ALS. Stable metabolites of NO (NO2- + NO3-) levels were determined in serum and CSF of sporadic ALS patients and control subjects. NO2- + NO3- levels were higher in ALS, in males and in serum samples compared to controls, females and CSF, respectively. Furthermore, while the difference between serum and CSF NO2- + NO3- levels was significant in males (higher in serum) no such difference was observed in females. Our results suggest that nitric oxide may be involved in the pathogenesis of ALS directly or indirectly and in a sexually dimorphic manner.

The effect of interferon therapy on erythrocyte membrane Na+,K+ ATP activity in patients with chronic hepatitis B and C virus infections.

In order to evaluate the effect of alpha interferon on erythrocyte membrane Na+,K+ ATPase (EC 3.6.1.37) activity, 10 patients with chronic hepatitis B virus (HBV) infection and 8 patients with chronic hepatitis C virus (HCV) infection were investigated. Erythrocyte membrane Na+,K+ ATPase activity was determined in controls and in patients with HBV and HCV infection. Na+,K+ ATPase activity was significantly less in untreated patients with (HBV) infection (n = 20; 0.134 +/- 0.073 mumol of phosphate produced per milligram of protein per hour) and (HCV) infection (n = 11; 0.144 +/- 0.049) when compared to the controls (n = 10; 0.219 +/- 0.055). Among these subjects patients were treated with interferon and following treatment, significant elevation of Na+,K+ ATPase activity was seen in patients with HCV (n = 8; 0.183 +/- 0.044; P = 0.049) and HBV (n = 10, 0.213 +/- 0.095, P = 0.0069) infections when compared with the pre-treatment values (n = 8; 0.152 +/- 0.050) and (n = 10, 0.131 +/- 0.083), respectively. Normalization of serum alanin amino transferase levels (ALT) at treatment cessation was seen in 8 of 10 (%80) HBV infected patients of whom 2 of 8 (%25) had sustained ALT responses within three months after the end of treatment. In HCV infected patients 1 of 8 (%12.5) had sustained response following treatment. At the end of treatment, although Na+,K+ ATPase was restored in both of the patients groups, relative changes in enzyme activity in relation to relative reduction in ALT levels as a response to IFN therapy were not correlated.

Possible role of glutathione in prevention of acetaminophen-induced hepatotoxicity enhanced by fish oil in male Wistar rats.

It has been reported that fish oil protects the rat liver against acetaminophen (APAP) induced toxicity; however, this finding is controversial. The present study was undertaken to investigate the effects of fish oil-enriched diet on APAP-induced liver injury in Wistar rats. Rats were fed a diet supplemented with either 8% fish oil or 8% corn oil, or standard rat feed for 6 wk. After an overnight fast, rats in each group were given either 2 g/kg APAP or saline orally. Our findings showed that APAP increased serum alanine aminotransferase (ALT) and that this rise was potentiated in the presence of dietary fat. Further fish oil ingestion increased the glutathione (GSH) content in rat liver; however, this was not effective in protecting liver from APAP-induced toxicity. Data suggest that GSH may be necessary to detoxify APAP metabolites, which are known to induce hepatotoxicity but are increased by dietary fat.

Possible supportive effects of co-dergocrine mesylate on antioxidant enzyme systems in aged rat brain.

Free radical damage is implicated in the course of many diseases, including age-related dementias. Oxidative deamination of primary monoamino oxidase (MAO) produces NH3 and H2O2 with established or potential toxicity. MAO activity is increased in aged rat brain and significantly lowered by chronic hydergine (codergocrine mesylate, Sandoz) treatment. The aim of this study was to investigate the effects of hydergine on enzymatic antioxidant defense systems. Hydergine or vehicle was administered systemically to young (3 months) and aged (18 months) Sprague-Dawley rats for 20 days and 24 h after the termination of the treatment, superoxide dismutase (SOD) and catalase (CAT) activities were determined in some brain regions. SOD and CAT activities were higher in the aged animals and were further increased with hydergine treatment. The increase in SOD levels caused by hydergine treatment in the aged animals were the most prominent in the hippocampus and in the corpus striatum. There was no region-specific effect of hydergine treatment on CAT levels in aged animals. The possible causal relationship between increased MAO activity, a generator of free radicals, and increased antioxidant defense in aging brain require further investigation. Decreasing MAO levels and supporting the antioxidant enzymes may underlie the efficacy of hydergine in the treatment of age related cognitive decline.

Sex differences in nitrite/nitrate levels and antioxidant defense in rat brain.

This study assessed sex differences in stable metabolites of nitric oxide and major enzymes involved in antioxidant defense in various regions of rat brain. Nitrite/nitrate levels and activities of superoxide dismutase and catalase were determined in cortex, hippocampus, corpus striatum, midbrain and cerebellum of adult male and female Sprague-Dawley rats. Nitrite/nitrate levels were significantly higher in the cortex and the hippocampus of male than female rats, while catalase activity was higher in the cortex of females than in males. These sex differences may have significant effects on brain function in health and disease.

Erythrocyte membrane Na+,K+ ATP ase activity can be a marker of liver histopathology.

Erythrocyte membrane Na+,K+: Ca2+ ATP ase activities, cholesterol (CH) phospholipid (PL) composition and erythrocyte glutathione (GSH) contents were determined in controls, in patients with chronic active hepatitis and liver cirrhosis. NA+,K+ ATP ase activities were significantly (P < 0.0001) less in patients with chronic active hepatitis and liver cirrhosis (n = 8, 0.102 +/- 0.02 mumol P/mg protein/hour; n = 8, 0.081 +/- 0.02 mumol P/mg protein/hour) than in controls (n = 10, 0.219 +/- 0.05). Histopathological analysis of liver sections obtained from patients with chronic active hepatitis (n = 3) and liver cirrhosis (n = 2) correlated well with erythrocyte biochemical findings. There was a significant negative correlation between Na+,K+ ATP ase activity and portal fibrosis (P < 0.05, r = -8680). However, further experiments performed on larger study populations are needed to better elucidate this correlation. Therefore, NA+K+ ATP ase activity measurement can be reliable assessment of liver fibrosis.

The endogenous scavengers in cerulein-induced acute pancreatitis.

Studies in animal models suggest that oxygen radicals are important in the pathogenesis of acute pancreatitis. Cerulein, a decapeptide isolated from the skin of the frog, Hyla caerula, is closely related to the C-terminus of cholecystokinin and it is a potent stimulant of pancreatic exocrine secretion. The aim of the present study was to measure the activity of endogenous scavengers, superoxide dismutase, catalase and glutathione levels in cerulein-induced acute pancreatitis in rats. We found that the plasma amylase and ribonuclease levels in the pancreatitis group were both significantly high (p < 0.01, p < 0.05, respectively) when compared with the control group. Although superoxide dismutase and glutathione levels of pancreatic tissue were decreased significantly (p < 0.01, p < 0.01 respectively), we observed a significant increase (p < 0.01) in catalase activity in the cerulein treated group compared to the control group. Therefore, we concluded that the profound alteration of the activities of endogenous scavengers (superoxide dismutase, catalase) and glutathione depletion occurring after cerulein-induced pancreatitis seemed to be important in tissue injury and may provide the basis for successful therapy of the disease.

Storage of rat liver for plasma membrane isolation.

We described a procedure for the preservation of rat liver which makes possible the isolation of plasma membranes after 10 days storage at -70 degrees C. The yield of plasma membranes obtained from the liver tissue kept at -70 degrees C for 10 days (3.43 +/- 0.08 mg protein/10 g wet liver) was not different statistically (P > 0.05) from the yield of freshly obtained plasma membranes (3.32 +/- 0.05 mg protein/10 g wet liver). However, a significantly low yield (2.65 +/- 0.08; P < 0.01) was obtained from 90 days stored rat liver when compared with the immediate isolation. Plasma membrane Na+, K+ ATPase and 5'nucleotidase activities of the stored liver for 10 days were not different statistically (P > 0.05) from the enzyme activities of the freshly isolated membrane fractions. In contrast there was a significant decrease (p < 0.0001) in the activities of both plasma membrane Na+, K+ ATPase and 5'nucleotidase activities of 90 days stored rat liver at -70 degrees C when compared with immediate isolation. Considering the electron microscopic findings; we observed that the preservation of the integrity of the plasma membrane fractions obtained from fresh and frozen livers for 10 and 90 days seemed to be parallel to the biochemical results. Therefore we suggest that, storage of rat liver tissue for 10 days make feasible to maintain the experimental design and give convenience for obtaining intact plasma membrane fractions.

Ethanol induced oxidative stress and membrane injury in rat erythrocytes.

The aim of this study was to observe membrane injury and to investigate the mechanism of antioxidant defence systems against acute ethanol toxicity. Erythrocyte superoxide dismutase and Na+, K(+)-ATPase activities were significantly decreased and catalase levels were significantly increased one hour after ethanol intoxication of male swiss albino rats. These data demonstrated that superoxide dismutase and catalase are susceptible to lipid peroxidation and that these enzymes protect tissues from free radicals. The possible mechanism involved in Na+, K(+)-ATPase and Ca(2+)-ATPase inhibition are discussed in relation to the development of ethanol toxicity and the role of lipid peroxidative processes.

Erythrocyte Na+,K(+)-ATPase activity does not predict therapeutic response to calcium antagonists in essential hypertension.

We investigated whether pre- and posttreatment analysis of erythrocyte membrane Na+,K(+)-ATPase (EC 3.6.1.37) activity would be a useful marker for screening hypertensive patients to determine who might benefit from treatment with calcium antagonists. Erythrocyte Na+,K(+)-ATPase activity and sodium and potassium (ENa, EK) contents were determined in controls and in patients with untreated essential hypertension before and after 4 weeks of treatment with nitrendipine. Na+,K(+)-ATPase activity was significantly (P < 0.0001) less in untreated hypertensive patients (n = 15; 104.60 +/- 29.37 nmol of phosphate produced per milligram of protein per hour) than in controls (n = 15, 171.87 +/- 34.42). After 4 weeks of nitrendipine treatment Na+,K(+)-ATPase activity was greater than in the pretreatment group: 158.13 +/- 26.80 (P < 0.001). Pretreatment ENa contents (22.34 +/- 4.77 mmol/L) were significantly (P < 0.0001) higher than in the normotensive group (13.14 +/- 3.32 mmol/L), but there was no significant difference between the controls and the posttreatment group (14.84 +/- 3.49 mmol/L). The control and pretreatment groups showed negative correlations between enzyme activity and systolic/diastolic blood pressure (P < 0.0001). The control and the posttreatment groups showed an inverse correlation between enzyme activity and ENa contents: r = -0.608 (P < 0.05) and r = -0.724 (P < 0.001), respectively. Although Na+,K(+)-ATPase is restored in hypertensive patients receiving nitrendipine treatment, relative changes in enzyme activity in relation to relative reduction in blood pressure response to treatment were not correlated.

Learning induces changes in the central cholinergic system of the rat in a sexually dimorphic pattern.

The involvement of the central cholinergic system in learning and the possible sexual dimorphism in related brain responses were investigated. Rats were exposed to different environmental conditions and to active avoidance learning. The resulting changes were studied using the following approaches: muscarinic receptor binding (MRB), acetylcholinesterase (AChE) and choline acetyltransferase (CAT) activities. The statistical evaluation of the data reveal that learning induces changes, especially in the postsynaptic component of the central cholinergic system, which shows some sexual dimorphism, and that males and females respond with different levels of increased cholinergic activity to informal and associative learning.

Naloxone binding in the frontal cortex of postmortem human brain.

1. The binding of 3H-Naloxone to opiate receptors was characterized in the frontal cortex of human post-mortem brain samples and age related changes in opiate receptors were investigated. 2. Our study revealed the presence of two binding sites with different affinities for naloxone. 3. With increasing age, the opiate receptors tend to show greater affinity for the agonistic conformation; this may imply a decline in endogenous opioid peptides with age.

Free amino acid level determinations in normal and schizophrenic brain.

1. Some disturbances in brain amino acids are reported with regard to pathological changes in schizophrenia: a reduction in GABA content and a reduced activity at some glutamatergic synapses. 2. Comparison of post-mortem brain tissue from control subjects and schizophrenic patients can provide evidence for amino acid alterations in disease. 3. The present study was undertaken to measure free amino acid concentrations in 20 brain regions obtained at autopsy, from normal persons and schizophrenics. Amino acids were extracted, esterified and separated by gas chromatography. 4. The distribution and levels of amino acids in normal persons is in accordance with similar values reported in human post-mortem brain samples by other investigators. 5. The differences in amino acids found in schizophrenic brain samples support the view of disturbed neurotransmission especially with regard to GABAergic and glutamatergic systems in schizophrenia and suggest the possible involvement of other amino acids as well.