Effect of mercuric chloride on the digestive system of a teleost fish,Channa punctatus

Summary The effect of 1.8 mg /liter (LC₅₀) of mercuric chloride exposure on the activities of alkaline phosphatase, acid phosphatase, glucose-6-phosphatase, amylase, pepsin, trypsin, tripeptidase glycyl-glycine dipeptidase and carnosinase has been examined inChanna punctatus. The three phosphatases have been inhibited in the liver but showed an increase in activity in the intestine and pyloric caeca. Amylase, pepsin and trypsin have also shown a slight increase in activity. There has been no significant alteration in the activities of the peptidases. The results show that mercury inhibits the activities of phosphatases in the liver but has no significant effect on the digestive enzymes within the experimental period of 96 hours.     

Occurence of choline acetyltransferase and acetylcholine and other quaternary ammonium compounds in mammalian spermatozoa

These investigations were undertaken to show the presence of acetylcholine (ACh) and other quaternary ammonium compounds and choline acetyltransferase (ChA) activity in mammalian spermatozoa. The spermatozoa from the fresh ejaculates of the bull and man were washed with calcium-free Krebs-Ringer phosphate solution and extracted with acetonitrile. The quarternary ammonium compounds from the extracts were subjected to pyrolysis gas chromatography. In the gas chromatogram of the quaternary ammonium compounds of bull spermatozoa, two peaks were found which represented 2-dimethylaminoethyl acetate and 2-dimethylaminoethyl propionate. In the gas chromatogram of the quaternary ammonium compounds of the human spermatozoa, a peak for 2-dimethylaminoethyl acetate was found. These observations suggest that ACh and propionylcholine (PCh) occur in bull spermatozoa and that ACh occurs in human spermatozoa. Bull spermatozoa contained 4.27 ± 1.41 pmoles (mean ± S.E.M.) ACh/10⁶ cells and 1.47 ± 0.48 pmoles PCh/10⁶ cells, and human spermatozoa contained 28.57 ± 3.38 pmoles ACh/10⁶ cells. ChA activity was determined in the washed spermatozoa by a radiometric assay. Incubation of the homogenates of the sperm cells with [¹⁴C]acetylcoenzyme A and choline resulted in the synthesis of [¹⁴C]ACh, which was separated, using a column of an anion exchange resin, and assayed. ChA activity in bull spermatozoa was 200.19 ± 32.08 pmoles ACh synthesized/10⁶ cells/10 min, and ChA activity in human spermatozoa was 130.90 ± 14.19 pmoles ACh synthesized/10⁶ cells/10 min. The specific activity of ChA in the tails of bull spermatozoa was about five times higher than in the heads or midpieces.     

Identification and conditions for selective expression of megakaryocytic markers in Friend erythroleukemia cells

Friend murine erythroleukemia cells (MELCs) have been reevaluated in terms of their nature and potential pathways of differentiation. MELC induced with 5 mmol/L hexamethylene bisacetamide (HMBA), in addition to expression of known markers of the erythroid phenotype, were also found to exhibit traits of the megakaryocytic lineage. Erythroid differentiation was shown by the typical synthesis and accumulation of hemoglobin (Hb); megakaryoblastoid differentiation of MELCs upon induction was shown by increased specific activity of acetylcholinesterase (AChE). Incubation of MELCs with 5 mmol/L HMBA in RPMI supplemented with 1% fetal calf serum (FCS) (instead of the usual 5%), induced cells to selectively express high levels of AChE (up to approximately 170 mU/mg protein) with little activation of Hb synthesis (less than 5% B+ cells). The increase in AChE levels was a general phenomenon affecting the whole cell population and approached its maximum within 3 days of incubation with the inducer. Subsequently, MELCs become committed to terminal division, undergoing growth arrest and expression of the megakaryocytic phenotype even after the removal of HMBA. There were no appreciable changes of basal AChE levels in MELCs that were either made resistant to HMBA or treated with 0.1 mmol/L hemin that activated differentiated erythroid function without commitment. Phorbol 12-myristate 13-acetate (PMA), known to repress induced Hb synthesis in these cells, did not prevent the full increase in AChE when incubated with MELCs 2 days before HMBA addition. HMBA- induced MELCs always underwent AChE increase that was more or less pronounced depending on the low or high serum content in culture, respectively. Conversely, Hb expression was permitted only when MELCs were transferred in the late phase or at the end of commitment from low to high serum media. Variations of FCS content in culture media proved to be a simple and reliable approach to change the MELC response to inducers and to modulate expression of either megakaryocytic or mixed erythromegakaryocytic phenotype. These findings suggested that MELC might be considered, at least, as a bipotential model of differentiation to be used for studies on regulation of either megakaryocytic or erythroid markers and on competition between the two hematopoietic lineages. In this regard, it was intriguing that AChE levels attained under selective induction (low serum) were always higher than under conditions allowing coexpression of both AChE and Hb (high serum). Moreover, MELCs were also found to bind the specific rat- antimouse platelet monoclonal antibody 4A5.(ABSTRACT TRUNCATED AT 400 WORDS)     

Percutaneous transluminal angioplasty: delayed response in neurofibromatosis

Percutaneous transluminal angioplasty (PTA) was eventually successful in a patient with renal artery stenosis due to neurofibromatosis. Although the immediate postangioplasty appearance showed little improvement, the residual stenosis has completely resolved at 5 months. Delayed response to PTA has been previously documented in other types of vascular disease. Its occurrence in renal artery stenosis due to neurofibromatosis emphasizes the importance of long-term follow-up and may be a factor in the poor short-term results that some have reported for PTA in patients with this condition.     

Functional irregularities of short-term and long-term memory storage in patients with Parkinson's disease and Huntington's disease.

Memory performance of Parkinson's disease patients (PD patients). Huntington's disease patients (HD patients) and healthy subjects were compared by a single-trial free recall task following the presentation of a stimulus list consisting of 30 nouns. The patient groups were categorized according to the severity of the disease into mild, moderate, and severe. Healthy subjects reproduced significantly more words than PD and HD patients, while the two patient groups did not differ in the total number of words reproduced. The differences between healthy and demented subjects are attributed to the impaired functional capacity of long-term memory; there were significant differences between healthy subjects and patients as well as between PD and HD patients. When taking the severity of the disease into consideration, varied influence on the capacity of long-term memory for PD and HD patients was found. Concerning short-term memory, neither a difference between healthy subjects and patients nor between both patient groups could be established. An effect of the severity of the disease could not be proven.     

Substances released during tetanic stimulation of rabbit neocortex induce neurite growth in PC-12 cells and long-term potentiation in guinea pig hippocampus

Samples collected from rabbit neocortical surface during a tetanic stimulation of the neocortex induced neurite growth in PC-12 cells in culture and synaptic long-term potentiation (LTP) in guinea pig hippocampal slices. If these samples were preheated and cooled, or if they were collected in the absence of a tetanic stimulation of the rabbit neocrotex, they did not induce neurite growth in PC-12 cells or LTP in the guinea pig hippocampus. These results suggest that neurite-inducing factors are released during tetanic stimulations and that these substances are involved in LTP.