Neuropeptide Y inhibits potassium-stimulated glutamate release through Y2 receptors in rat hippocampal slices in vitro

1. We investigated the effects of neuropeptide Y (NPY), peptide YY (PYY), NPY13-36, NPY18-36, [Leu31][Pro34]NPY and of pancreatic polypeptide Y (PPY) on calcium-dependent, potassium-stimulated glutamate release in superfused rat hippocampal slices. 2. NPY, PYY and the Y2 receptor agonist NPY13-36 equipotently inhibited the release of glutamate. The half-maximal response was observed at about 10 nM in a dose-dependent manner (3 to 100 nM). Maximal inhibition of 50 to 60% was obtained at 100 nM. At higher concentrations of the peptides (300 nM and 1 microM) this inhibition was partially or entirely reversed. Porcine NPY13-36 and NPY18-36 inhibited glutamate release by about 44% at 100 nM. 3. The specific Y1 receptor agonist, [Leu31][Pro34]NPY, caused an insignificant increase in glutamate release at 100 to 300 nM concentrations. PPY had no effect on potassium-evoked glutamate release in hippocampal slices at concentrations of 30 nM to 1 microM. 4. The experiments support previous electrophysiological data. They suggest a potent inhibitory action of NPY through NPY-Y2 receptors on the release of the excitatory amino acid glutamate in rat hippocampus. Especially under conditions of increased NPY synthesis, such as in epilepsy, this mechanism may be of pathophysiological relevance.

An indirect bioluminescence method for the quantitative measurement of polymorphonuclear cell chemotaxis

A method is presented which allows the quantification of the effects of chemotactic factors on polymorphonuclear leukocytes on the basis of a sensitive ATP measurement using bioluminescence. The assay measures those cells which have migrated through a commercial 3 micron filter system (Transwell). The assay was tested under standardized conditions with different chemotactic agents (leukotriene B4 [LTB4], N-formyl-methionyl-leucyl-phenylalanine [FMLP], N-formyl-methionyl-leucyl-phenylalanine-methyl ester [M-FMLP]). Under appropriate conditions the migration of PMN-cells is time-dependent and linear for 60 minutes. Spontaneous migration of PMN cells is simultaneously quantified in a simple way, and the value obtained allows a determination of the actual chemotactic situation of the PMN cells. In healthy humans the spontaneous migration varied between 4.2% and 14.4% of the total number of PMN cells. An optimal chemotactic activity was detected at 10(-8)/mol/l for FMLP and 10(-7) mol/l for M-FMLP in PMN leukocytes, which correlates with literature values. It was also found that in contrast to EDTA blood, heparinized blood lowers the ATP level of PMN cells (by about 50%) and therefore heparinized blood is not recommended for chemotactic experiments. This assay is a simple tool for quantification of the spontaneous migration, and the chemotactic response to specific factors and their inhibitors in particular for pharmacological experiments. In contrast to the 'classical' chemotactic assays this method also permits the simultaneous testing of the influence of chemotactic substances on cellular ATP levels.

[Use of toltrazuril in pullet breeding flocks raised on floors with anticoccidial-free feed]

In 28 replacement pullet flocks with flock size of 4,000 to 25,000 birds Toltrazuril (experimental preparation, 2.5% solution, approx. 7 mg/kg body weight) was administered for a period of two days in the drinking water for metaphylactic purpose and therapeutic use, respectively. All flocks were reared without anticoccidial feed additives. Exposition to Eimeria spp. was recorded by examination of faecal samples and intestinal scrapings. Clinical flock control was achieved by vets at eight to ten day intervals. Toltrazuril was characterized by short application period, rapid mode of action, significant reduction of oocyst shedding, good compatibility and acceptance thus proving superior to conventional chemotherapy of coccidiosis. The results suggest that, even without administration of anticoccidial feed additives. Toltrazuril is an effective agent for therapeutic use in acute coccidiosis. Under insufficient management and rearing conditions repeated metaphylactic application has to be considered.

The effects of ibuprofen and diclofenac on the chemotaxis and adenosine triphosphate level of polymorphonuclear cells in vitro

Investigations were carried out to determine the effect of ibuprofen and diclofenac on the chemotaxis of human polymorphonuclear cells. The experiments were done with the drugs alone as well as in the presence of leukotriene B4 (LTB4). A modified quantitative bioluminescence assay was used to measure chemotaxis, which allowed the calculation of differences in the spontaneous migration in contrast to the effects of the drugs, and simultaneously, also, the evaluation of whether the inhibition or augmentation of the chemotaxis was due to influences on the adenosine triphosphate (ATP) level of the cells. It was found that high concentrations (10 mM) of either ibuprofen or diclofenac destroy the intracellular ATP of polymorphonuclear cells (PMN). Therefore, the reported inhibition of the chemotaxis by ibuprofen at a concentration of 10 mM cannot be understood as a part of the chemotactic process. In the range of 1 microM and 0.1 mM ibuprofen and diclofenac did not statistically affect the intracellular ATP level of PMN cells but at the same time a distinct inhibition of the chemotactic response of PMN cells was observed. This effect occurred even in the presence of a potent chemoattractant (leukotriene B4). Ibuprofen (0.1 mM) reduced chemotaxis to 67% and the same concentration of diclofenac reduced it to 56% of the values of LTB4 alone.

Modulation of the migration and chemotaxis of PMN cells by hyaluronic acid

Hyaluronic acid (HA) has a dose-related inhibiting effect on the migration and chemotaxis of polymorphonuclear leucocytes (PMN) in vitro. These effects were measured with a new indirect quantitative assay. On average 1 mg HA/ml causes an inhibition to about 80% of the control (spontaneous migration). This effect increased progressively with an increasing HA concentration, and with 4 mg HA/ml only about 19% of the PMN were able to migrate in the in vitro system. Similar results were obtained in the presence of a potent chemotactic factor (leukotriene B4 [LTB4]). In the mean 1 ng LTB4/ml alone stimulated the chemotaxis of PMN by a factor of 3 compared to the spontaneous migration. The highest HA concentration (4 mg/ml) reduced the number of migrating PMN cells to about 17%. From these experiments it may be concluded that the HA in the synovial fluid of the healthy joint has a protective effect against the invasion of PMN cells. This functions is disturbed in inflamed joints by the decrease in the HA concentration and possibly by its depolymerization. The intraarticular application of high molecular weight HA might be an important therapeutic regimen to restore the natural barrier against PMN migration, also in the presence of chemotactic factors and could therefore be helpful for interrupting the inflammatory cascade.

[Determination of growth hormone in plasma of psoriatic arthritis, psoriasis vulgaris and seronegative spondylarthritis]

By means of radio-immunoassay the concentration of human growth hormone (HGH) was measured in the blood plasma of 61 patients with psoriasis (21 suffering from psoriasis vulgaris and 40 with psoriatic arthritis), 30 patients with ankylosing spondylitis, 9 with atypical spondylarthritis and 34 patients with diseases of the soft tissue or degenerative joint and spinal column disease. No connection was found between the HGH concentration and the skin lesions in psoriasis. On the other hand a correlation between HGH and the sacroiliitis in psoriatic arthritis and seronegative spondyloarthropathies may be possible. In contrast to the plasma of psoriatics, the mean HGH concentration was higher in the plasma of patients with degenerative joint diseases. Therefore the results of this paper confirm those opinions in the literature which deny increased HGH concentrations in psoriatics. The beneficial effect of the therapeutic administration of somatostatin, an inhibitor of the release of HGH, in psoriasis vulgaris and psoriatic arthritis is - if indeed it occurs - attributable to other hitherto unidentified mechanisms.

Increased angiotensin-converting enzyme activities in diabetes mellitus: analysis of diabetes type, state of metabolic control and occurrence of diabetic vascular disease

Serum angiotensin-converting enzyme activities were measured in 41 type 1 diabetics (16.4 +/- 4.0 U/ml), in 40 type 2 diabetics (15.0 +/- 5.2 U/ml) and in 52 controls (13.0 +/- 2.7 U/ml, mean +/- SD). Twenty six (32%) of 81 patients presented with serum angiotensin-converting enzyme activities above the normal range. No relation between serum angiotensin-converting enzyme activities and the presence or lack of diabetic vascular diseases in type 1 and type 2 diabetics could be detected. No significant differences in serum angiotensin-converting enzyme activities were found when comparing various types of diabetic vascular disease (retinopathy, neuropathy, renal failure, arterial vascular disease, diabetic vascular disease, coronary artery disease). However, mean serum angiotensin-converting enzyme activities were significantly increased in diabetics with retinopathy when compared with controls (p less than 0.0005). Correlation between metabolic long term control as determined by measuring glycohaemoglobin (HbA1) concentrations and serum angiotensin-converting enzyme activities could not be established. Serum angiotensin-converting enzyme activities did not show any correlations with duration of diabetes, age or sex of patients. A representative number of diabetics (32%) showed elevated serum angiotensin-converting enzyme activities, but a correlation with diabetic vascular disease, metabolic control or type of disease could not be established.

Chronic hemodialysis: high risk patients for arrhythmias?

Patients with end-stage kidney disease undergoing chronic maintenance dialysis (HD) are a high risk group for sudden death due to cardiovascular complications. It was the aim of the study to investigate the quantity and quality of arrhythmias during HD and between two consecutive HD (interval, I) with regard to the reproducibility of the expected results. 15 patients (8 males, 7 females) underwent continuous Holter monitoring (LT-ECG) under ambulatory conditions over 96 h including two HD ( HD1 + HD2 ) and two intervals (I1 + I2). The LT-ECG recordings were analysed with the computer assisted ' Multipass -Scanning' system with regard to heart rate (HR), supraventricular premature beats (SPB), ventricular ectopics (PVC) and malignant ventricular arrhythmias.

RESULTS

The HR demonstrated a typical, well-known circadian pattern with remarkable increase of the HR during each HD. Except for rare, single SPB and/or PVC, no supraventricular or ventricular arrhythmias could be detected reproducibly. Single PVC occurred in patients with a lower potassium value. No malignant ventricular arrhythmias were found. In comparison to previously published studies, which demonstrated a high incidence of malignant ventricular arrhythmias, these conflicting results were due to differences in patients' recruitment (underlying disease, age, etc.), the performance of HD (duration, ion concentration of the dialysate etc.), serum potassium levels and drug medication (digitalis, quinidine). In summary, chronic HD per se did not enhance the risk of malignant arrhythmias in patients with end-stage kidney disease.

[Investigations on the plasm amino acids of old patients with rheumatoid arthritis (author's transl)]

The amino acids of blood plasma of 43 patients with rheumatoid arthritis (RA) and 19 controls were investigated by ion exchange chromatography. It was proofed simultaneously whether human more than 60 years old exhibit significantly different amino acid concentrations from younger individuals. It was found that RA patients more than 60 years differ significantly in 23 out of 30 amino acids. Only Asparagine was decreased, all other amino acids were increased. The controls did not show the same uniform direction of results. Older individuals exhibited differences in only 14 amino acids. Phosphoserine, Cystathionine and Arginine were increased to a great extent while Threonine, 1-Methylhistidine and Tryptophane were apparently diminished in this group of age.