Diacylglycerol in the synergy of bradykinin and thrombin stimulation of prostaglandin synthesis

Simultaneous addition of bradykinin and thrombin to 3T3 fibroblasts for 5 min resulted in less than additive stimulation of prostaglandin E2 synthesis. However, if cells were stimulated with either agonist alone, then the other added 15 min later, prostaglandin E2 synthesis was synergistically enhanced. In contrast, if either agonist was added, then prostaglandin E2 synthesis in response to the same agonist assessed 15 min later, synthesis was markedly reduced. Bradykinin and thrombin caused increased diacylglycerol accumulation in the cells, and addition of the diacylglycerol kinase inhibitor R59022 dramatically increased the effects of sequential addition of the agonists. These results suggest that diacylglycerol generated in response to activation of one receptor amplifies the effects of activation of other receptors.     

Influence of cardiopulmonary bypass on water balance hormones in children.

OBJECTIVE--To determine the changes in the endocrine mechanisms of fluid balance after cardiopulmonary bypass in children. DESIGN--Prospective study; analysis of numbered plasma samples performed blind with respect to clinical data. SETTING--Regional paediatric cardiothoracic unit. PATIENTS--Nine patients, median age 4, range 2 to 9 years, five males. Patients under the age of 1 year were excluded because of the frequent blood sampling involved. MAIN OUTCOME MEASURES--Plasma concentrations of atrial natriuretic peptide (ANP), arginine vasopressin, plasma renin activity, aldosterone, noradrenaline and adrenaline, and urinary concentrations of cyclic guanosine monophosphate (cGMP) as measured by radioimmunoassay. RESULTS--After 30 minutes of cardiopulmonary bypass plasma atrial natriuretic peptide (ANP) decreased from (mean (SEM)) 151 (71) pg/ml to 52 (44) pg/ml (NS), and urinary production of its second messenger cyclic guanosine monophosphate (cGMP) decreased from 1286 (600) pmol/ml to 151 (414) pmol (p < 0.05). Other plasma concentrations of hormones studied did not change significantly although arginine vasopressin, adrenaline, and noradrenaline increased whereas aldosterone and plasma renin activity decreased. After cardiopulmonary bypass stopped there was an immediate and significant rise in plasma ANP, but within the next 24 hours plasma ANP declined significantly (p < 0.05), decreasing from 294 (49) pg/ml to 64 (29) pg/ml at 22 hours. In the postoperative period there was a significant correlation between plasma ANP and both mean fluid balance (r = 0.96, p < 0.001) and mean urine output (r = 0.97, p < 0.001). Plasma aldosterone peaked (p < 0.05) at 22 hours after operation, and argine vasopressin peaked (p < 0.05) at two hours and then declined (p < 0.05) to a trough at 24 hours. Plasma renin activity, adrenaline, noradrenaline, and urinary cGMP concentrations, and mean central venous pressure did not change significantly in the postoperative period. CONCLUSION--The changes documented show the differing pattern of release of water balance hormones invoked by cardiopulmonary bypass. The central role of ANP is shown by its strong correlation with urinary output and its similarly strong relation to fluid balance.     

Emergence and scattering of multiple neurofibromatosis (NF1)-related sequences during hominoid evolution suggest a process of pericentromeric interchromosomal transposition

Type 1 neurofibromatosis (NF1) gene encodes for a member of the GTPase activating protein family and is considered to be a tumor suppressor gene. Its very high rate of de novo mutation in humans led us to study a specific feature of this gene: the presence of numerous NF1-related sequences. According to our results, the human genome contains at least 11 NF1-related sequences, nine of which are scattered near centromeric sequences of seven different chromosomes. These NF1-related sequences, whose extent is quite varied according to loci, are unprocessed copies of the NF1 gene, and bear numerous mutations. A phylogenetic analysis of the six largest sequences indicates that they are all derived from a common ancestor, which would have appeared 22-33 million years ago, and was subsequently duplicated several times during hominoid evolution. The most recent duplication and interchromosomal transposition occurred in the last million years suggesting that the process could still be ongoing. Intriguing similarities between the evolution of alpha- satellite DNA and NF1-related sequences suggest the involvement of a common genetic mechanism for the generation and pericentric spreading of these NF1 partial copies.      

Toxicity of the blue-green alga (cyanobacterium) Microcystis aeruginosa in drinking water to growing pigs,as an animal model for human injury and risk assessment

Hepatotoxins from blue-green algae are increasingly recognized as a potential hazard in drinking water supplies. The clinical consequences of ingestion include acute or chronic liver injury, with the possibility of enhanced susceptibility to, and growth of, liver tumors. To establish guidelines for water safety requires the demonstration of dose-dependent effects of toxicity and experimental determination of maximum “no-adverse-effect levels.” This paper describes the use of growing pigs as a model for human injury resulting from Microcystis toxins in drinking water. Risk assessment calculations using a series of safety factors are carried out, resulting in a guideline level after incorporating an additional safety factor for tumor promotion of approximately 1.0 μg toxins/L. With the Microcystis used for this trial, that concentration corresponds to 5000 cells/mL. © 1994 by John Wiley & Sons, Inc..     

2,6-Diamino-N-([1-(1-oxotridecyl)-2-piperidinyl] methyl)hexanamide (NPC 15437): a novel inhibitor of protein kinase C interacting at the regulatory domain.

NPC 15437 is a prototype member of a new class of synthetically derived protein kinase C (PKC) inhibitors. PKC activity and binding of phorbol ester to the enzyme were inhibited by NPC 15437, with IC50 values of 19 +/- 2 microM and 23 +/- 4 microM, respectively. No inhibition of cAMP-dependent or calcium/calmodulin-dependent protein kinases was observed at concentrations of NPC 15437 up to 300 microM. To investigate the mechanism by which NPC 15437 exerts its effects, a kinetic analysis of the inhibition with respect to three activators of the enzyme, phosphatidylserine, calcium, and phorbol ester, was performed. NPC 15437 was a competitive inhibitor of the activation of PKC by phorbol ester (Ki = 5 +/- 3 microM). Stimulation of PKC alpha by phosphatidylserine was competitively inhibited by NPC 15437 (Ki = 12 +/- 4 microM). The inhibition was mixed with respect to activation by calcium. These results suggest that NPC 15437 is a selective inhibitor of PKC, interacting at the regulatory region of the enzyme. NPC 15437 inhibited PKC in intact cells, dose-dependently antagonizing the phorbol ester-induced phosphorylation of a 47-kDa protein in human platelets.     

Genomic analysis of the nuclear receptor family: new insights into structure, regulation, and evolution from the rat genome

Completion of the Rattus norvegicus genome sequence enabled a global inventory and analysis of the nuclear receptors (NRs) in three mammalian species. Forty-nine NR members were found in mouse, 48 in human. Forty-seven were found in the rat, with gaps at the locations expected for the other two. Pairwise comparisons of their distribution in rat, mouse, and human identified 11 syntenic NR gene blocks, including three small clusters of two or three closely related genes, each spanning 40 kb to 1700 kb. The exon structure of the ligand-binding domain suggests that exon shuffling has played a role in the evolution of this family. An invariant splice junction in all members of the NR family except LXRbeta suggests a functional role for the intron. The ligand-binding domains of PXR and CAR are among the most divergent in the family. Their higher nucleotide substitution rates may be related to the central role played by these two NRs in the metabolism of the foreign compounds and may have resulted from limited positive selection.     

Photodynamic therapy for the treatment of metastatic lesions in bone: studies in rat and porcine models

This study represents the first reported use of photodynamic therapy (PDT) for metastatic bone lesions and specifically, as a treatment for spinal metastases. A model of bone metastasis in rat confirmed the efficacy of benzoporphyrin derivative-monoacid-mediated PDT for treating lesions within the spine and appendicular bone. Fluorimetry confirmed the selective accumulation of drug into the tumor(s) at 3 h post-injection. 48 h post-light delivery into the vertebral body of the rat spine loss of bioluminescent signal and histological analyses of sectioned spine confirmed MT-1 tumor cell kill in vivo as previously confirmed in vitro using an established cell viability assay. Porcine vertebrae provided a model comparable to that of human for light propagation and PDT response. Histological examination of vertebrae 48 h post-PDT revealed a necrotic radius of 0.6 cm with an average fluence rate of 4.3 mW/cm2. Non-necrotic tissue damage was evident up to 2 cm out from the treatment fiber. Results support the application of PDT to the treatment of primary or metastatic lesions within bone.