Prostaglandin E2 requirement for transforming growth factor beta 1 inhibition of elicited macrophage 14 kDa phospholipase A2 release.

1. Cultured elicited-peritoneal macrophages release a soluble type II 14 kDa phospholipase A2 (PLA2) over time, reaching a plateau by 20-24 h of incubation and maintaining these levels over 72 h. Prostaglandin E2 (PGE2) is also produced but does not plateau until 48-72 h. 2. Transforming growth factor beta 1 (TGF beta 1) reduces cellular 14 kDa PLA2 and its subsequent release by approximately half, but does not alter PGE2 production. Co-incubation of TGF beta 1 with indomethacin interfered, in a concentration-dependent manner, with the ability of TGF beta 1 to reduce cellular 14 kDa PLA2 and its subsequent release over 24 h. The regulation of TGF beta 1 was not specific to indomethacin since other non-steroidal anti-inflammatory drugs had the same effect. This suggested that cyclooxygenase activity was essential for TGF beta 1 to exert its effect and indeed, the addition of exogenous PGE2 restored the TGF beta 1 action. 3. PGE2 alone exerted a concentration-dependent negative feedback action on elicited-macrophage 14 kDa PLA2 release. The inhibitory concentration (IC50 = approximately 180 ng PGE2 ml-1) approximated the PGE2 levels measured in the 24 h macrophage conditioned media (85-140 ng PGE2 ml-1) where PLA2 release began to plateau. Further, incubation of cells with indomethacin over 48 h resulted in the enhancement of 14 kDa PLA2 activity compared to that released from untreated cells. Forskolin failed to inhibit 14 kDa PLA2 release, suggesting PGE2 was not acting through an increase in adenylate cyclase. 4. Taken together, the data are consistent with the immunosuppressive aspects reported for both mediators during inflammation and demonstrates the requirement of PGE2 for TGF beta 1 action on the elicited macrophage.     

Inactivation of human synovial fluid phospholipase A2 by the marine natural product, manoalide

The marine natural product, manoalide (MLD), was investigated to determine if this drug inhibited purified human synovial fluid phospholipase A2 (HSF-PLA2). Utilizing classical Michaelis-Menten kinetics, apparent Km and Vmax values for HSF-PLA2 of 1.34 mM and 0.47 mumol [3H]palmitic acid released/min/mg protein were obtained using dipalmitoylphosphatidylcholine (DPPC) as the substrate, and 38.0 microM and 18.8 mumol [3H]arachidonic acid released/min/mg protein with Escherichia coli as a natural substrate. These kinetic parameters were utilized subsequently to evaluate the inhibitory effects of manoalide on HSF-PLA2. Inhibition of HSF-PLA2 by MLD was concentration and time dependent with IC50 values of 0.2 and 0.02 microM for DPPC and E. coli respectively. Dialysis studies and examination of DPPC or E. coli hydrolysis versus enzyme concentration indicate that MLD is an irreversible inhibitor of HSF-PLA2. Substrate specificity was also examined in the absence and presence of MLD using dipalmitoylphosphatidylethanolamine (DPPE) as a substrate. MLD inhibited the hydrolysis of DPPE (greater than 90% inhibition at 2 microM), and preliminary results indicate that DPPC was more readily hydrolyzed than DPPE under the substrate conditions of the assay. While the cellular source of secreted HSF-PLA2 is unknown, these studies indicate that MLD can inactivate secreted phospholipase A2 isolated from patients with inflammatory joint disease.     

Management of hypertension in Mamre women

A follow-up study was conducted in December 1987 on all 136 women between the ages of 25 and 64 years who had been recorded as being on treatment for hypertension in the Mamre Community Health Project in December 1986. A further 136 women were randomly selected from the same age category to determine the overall prevalence of hypertension. The repeatability and validity of the 1986 project questionnaire were satisfactory. The overall prevalence of hypertension in Mamre women was 25.9% (16.1% for the age group 25-44 years and 38.4% for the age group 44-64 years). The extent of underdiagnosis of hypertension in the community on the basis of the 1986 survey was 56.8%. Despite a good reported compliance rate of 72.7%, 56.3% of hypertensives were not adequately controlled. The Mamre community presents an ideal setting for an interventive study in the management of hypertension.     

Integration of bilateral whisker stimuli in rats: role of the whisker barrel cortices.

Recently, we demonstrated that neural responses within the whisker region of the primary somatosensory cortex (SIw) of rats are profoundly influenced by the spatiotemporal attributes of ipsilateral, as well as contralateral, whisker stimuli. As inactivation of one SIw eliminates in the intact SIw both ipsilaterally evoked responses and the influence of ipsilateral stimulation on contralaterally evoked activity, we proposed that interhemispheric interactions between the SIws may be important for integrating bilateral whisker information. To test whether rats can recognize the bilateral nature of a whisker stimulus, we developed a tactile discrimination task that required rats to conjointly determine distances to a left and a right discriminandum as equidistant or non-equidistant using only their facial whiskers. All rats trained in this task achieved performance levels indicative of an ability to integrate bilateral whisker information. Testing during unilateral, as well as bilateral, inactivation of the SIws indicated that rats rely on both SIws for detecting the bilateral nature of a whisker stimulus. Rats were unable to perform the task without both sets of whiskers, a fact that indicates that the whiskers (and not other modalities) were used to perform this task. The findings presented here indicate that rats can solve a task that requires the conjoint detection of left and right whisker-mediated distance information and implicate the SIws as central to this ability.     

Endoscopic reconstruction of traumatic membranous urethral transection

Newer endoscopic techniques derived from percutaneous renal manipulations are well suited for endoscopic reconstruction of traumatic short total membranous urethral transections. Four men and 1 child underwent successful endoscopic membranous urethral reconstruction. All 4 men are voiding with good flow and normal control more than 1 year after any endoscopic manipulation.