Synergism between diacylglycerols and calcium ionophore in the induction of human B cell proliferation mimics the inositol lipid polyphosphate breakdown signals induced by crosslinking surface immunoglobulin

Resting human tonsillar B cells were stimulated to divide by heat killed Staphylococcus aureus Cowan strain 1 which was shown to induce hydrolysis of phosphatidylinositol 4, 5-bisphosphate known to give rise to diacylglycerol and an increase in cytosolic free calcium. Addition of the diacylglycerols, 1-oleoyl-2 acetyl glycerol or sn-1, 2-dioctanoylglycerol, together with the calcium ionophore ionomycin to B cell cultures induced marked cell proliferation whereas these agents were ineffective when used alone. Both diacylglycerols were shown to compete with [3H] phorbol 12,13 dibutyrate in binding to protein kinase C. These data support the hypothesis that synergism between cytosolic calcium and endogenous diacylglycerol, which activates protein kinase C, is involved in signal transduction in the proliferation of human B cells.     

Improved Working Memory but No Effect on Striatal Vesicular Monoamine Transporter Type 2 after Omega-3 Polyunsaturated Fatty Acid Supplementation

Studies in rodents indicate that diets deficient in omega-3 polyunsaturated fatty acids (n–3 PUFA) lower dopamine neurotransmission as measured by striatal vesicular monoamine transporter type 2 (VMAT2) density and amphetamine-induced dopamine release. This suggests that dietary supplementation with fish oil might increase VMAT2 availability, enhance dopamine storage and release, and improve dopamine-dependent cognitive functions such as working memory. To investigate this mechanism in humans, positron emission tomography (PET) was used to measure VMAT2 availability pre- and post-supplementation of n–3 PUFA in healthy individuals. Healthy young adult subjects were scanned with PET using [¹¹C]-(+)-α-dihydrotetrabenzine (DTBZ) before and after six months of n–3 PUFA supplementation (Lovaza, 2 g/day containing docosahexaenonic acid, DHA 750 mg/d and eicosapentaenoic acid, EPA 930 mg/d). In addition, subjects underwent a working memory task (n-back) and red blood cell membrane (RBC) fatty acid composition analysis pre- and post-supplementation. RBC analysis showed a significant increase in both DHA and EPA post-supplementation. In contrast, no significant change in [¹¹C]DTBZ binding potential (BP_ND) in striatum and its subdivisions were observed after supplementation with n–3 PUFA. No correlation was evident between n–3 PUFA induced change in RBC DHA or EPA levels and change in [¹¹C]DTBZ BP_ND in striatal subdivisions. However, pre-supplementation RBC DHA levels was predictive of baseline performance (i.e., adjusted hit rate, AHR on 3-back) on the n-back task (y = 0.19+0.07, r² = 0.55, p = 0.009). In addition, subjects AHR performance improved on 3-back post-supplementation (pre 0.65±0.27, post 0.80±0.15, p = 0.04). The correlation between n-back performance, and DHA levels are consistent with reports in which higher DHA levels is related to improved cognitive performance. However, the lack of change in [¹¹C]DBTZ BP_ND indicates that striatal VMAT2 regulation is not the mechanism of action by which n–3 PUFA improves cognitive performance.     

Biodegradation of 2,4,6-trinitrotoluene byPhanerochaete chrysosporium: Identification of initial degradation products and the discovery of a TNT metabolite that inhibits lignin peroxidases

Biodegradation of 2,4,6-trinitrotoluene (TNT) by the wood-rotting BasidiomycetePhanerochaete chrysosporium was studied in a fixed-film silicone membrane bioreactor and in agitated pellected cultures. The initial intermediate products of TNT biodegradation were shown to be 2-amino-4,6-dinitrotoluene (2amDNT) and 4-amino-2,6-dinitrotoluene (4amDNT). These intermediates were also degraded byP. chrysosporium. However, their rates of degradation were slow and appeared to represent rate-limiting steps in TNT degradation. The fact that 2amDNT and 4amDNT were further degraded is of importance. In most other microbial systems these compounds are typically not further degraded or are dimerized to even more persistent azo and azoxydimers. Similar to previous studies performed in stationary cultures, it was shown that substantial amounts of [¹⁴C]-TNT were degrade to [¹⁴C]-carbon dioxide in agitated pelleted cultures. Lignin peroxidase activity (assayed by veratryl alcohol oxidation) virtually disappeared upon addition of TNT to ligninolytic cultures ofP. chrysosporium. However, TNT, 2amDNT, and 4amDNT did not inhibit lignin peroxidase activity, nor were they substrates for this enzyme. Subsequent studies revealed that 4-hydroxylamino-2,6-dinitrotoluene, an intermediate in TNT reduction, was a potent lignin peroxidase inhibitor. Further studies revealed that this compound was also a substrate for lignin peroxidase H8.     

Cat heart acetylcholine: Unilateral vagotomy studies with pyrolysis-mass fragmentography

The distribution of acetylcholine (ACh) in the cat heart was investigated by pyrolysis-gas chromatography (PGC) and pyrolysis-mass fragmentography (PMF) techniques. The hearts were dissected into various regions and homogenized in the presence of butyrycholine (or propionylcholine) as internal standard. The choline esters were isolated and analyzed by PGC or by PMF (at m/e 58). A pattern of distribution for ACh was found to be the same as I have previously described (1,2). Some cats were subjected to either a right or a left unilateral cervical vagotomy 4 weeks before removal and analysis of heart tissue. Hearts from unilateral (right or left) vagotomized cats did not differ from controls in the ACh content of any heart area examined. These results are consistent with the idea that intact parasympathetic neurons may compensate for the denervation following unilateral vagotomy.