Differential roles of extracellular signal-regulated kinase-1/2 and p38(MAPK) in interleukin-1beta- and tumor necrosis factor-alpha-induced low density lipoprotein receptor expression in HepG2 cells

The inflammatory cytokines interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF), elevated in inflammatory, malignant, and infectious diseases, induce low density lipoprotein (LDL) receptor transcription in HepG2 cells, and such an induction can account for hypocholesterolemia associated with these states. However, the signaling mechanisms of cytokine-mediated LDL receptor induction are largely unexplored. In the present studies, we examined the potential involvement of different mitogen-activated protein kinase (MAPK) pathways. Northern analysis demonstrated that IL-1beta or TNF significantly increased LDL receptor transcript in HepG2 cells, whereas expression of another tightly regulated sterol-responsive squalene synthase gene was unaffected. IL-1beta treatment resulted in transient activation of three MAPK cascades, namely p46/54(JNK), p38(MAPK), and ERK-1/2, with maximal activation of 20-, 25-, and 3-fold, respectively, occurring 15-30 min after cytokine addition. PD98059, a specific inhibitor of MAPK kinase activity, inhibited IL-1beta-induced LDL receptor expression. In contrast, SB202190, a specific inhibitor of p38(MAPK), enhanced IL-1beta-induced LDL receptor expression, with a concomitant increase in ERK-1/2 activity. Similarly, TNF induced LDL receptor expression also required ERK-1/2 activation. Finally, sterols repressed IL-1beta induced receptor expression, without affecting ERK-1/2 activation. These results show that IL-1beta- or TNF-induced LDL receptor expression requires ERK-1/2 activation, that the p38(MAPK) pathway negatively regulates LDL receptor expression, and that sterols inhibit induction at a point downstream of ERK-1/2 in HepG2 cells.

Elevation of cyclic AMP by iloprost and prostaglandin E1 increases cholesterol efflux and the binding capacity for high-density lipoproteins in human fibroblasts

Elevation of cAMP concurrently enhances cholesterol efflux and binding of HDL3 in human skin fibroblasts. These effects were observed regardless of the route by which cAMP levels were increased. Cholesterol efflux and HDL3 binding were stimulated by the cAMP analogue CPT-cAMP, the adenylate cyclase activator forskolin, and by iloprost and prostaglandin E1 (PGE1) (which elevate cAMP via receptor-mediated processes). Dideoxyforskolin and PGF2alpha, which do not elevate cAMP, altered neither cholesterol efflux nor binding of HDL3. Inhibition of protein kinase A with H89 abolished the stimulatory effects of CPT-cAMP and iloprost, suggesting protein kinase A involvement in enhancing cholesterol efflux and HDL3 binding. Enhancement of HDL3 binding by iloprost was due to increased maximal capacity of the cells to bind HDL3, i.e., a greater number of HDL3 binding sites. A positive correlation was demonstrated between changes in HDL3 binding and changes in [3H]cholesterol efflux. The data are compatible with a model in which cholesterol efflux is partially dependent upon HDL binding to the cells. A short exposure to iloprost was sufficient to stimulate cAMP synthesis, triggering a chain of events leading to increased HDL3 binding and [3H]cholesterol efflux 20-24 h later. We conclude that both cholesterol efflux and the maximal capacity for HDL3 binding are enhanced by elevation of cellular cAMP. Cyclic AMP-elevating prostanoids could initiate these responses in vivo.

Prelingual deafness: high prevalence of a 30delG mutation in the connexin 26 gene

Prelingual non-syndromic (isolated) deafness is the most frequent hereditary sensory defect. In >80% of the cases, the mode of transmission is autosomal recessive. To date, 14 loci have been identified for the recessive forms (DFNB loci). For two of them, DFNB1 and DFNB2, the genes responsible have been characterized; they encode connexin 26 and myosin VIIA, respectively. In order to evaluate the extent to which the connexin 26 gene (Cx26) contributes to prelingual deafness, we searched for mutations in this gene in 65 affected Caucasian families originating from various countries, mainly tunisia, France, New Zealand and the UK. Six of these families are consanguineous, and deafness was shown to be linked to the DFNB1 locus, 10 are small non consanguineous families in which the segregation of the trait has been found to be compatible with the involvement of DFNB1, and in the remaining 49 families no linkage analysis has been performed. A total of 62 mutant alleles in 39 families were identified. Therefore, mutations in Cx26 represent a major cause of recessively inherited prelingual deafness since according to the present results they would underlie approximately half of the cases. In addition, one specific mutation, 30delG, accounts for the majority (approximately 70%) of the Cx26 mutant alleles. It is therefore one of the most frequent disease mutations so far identified. Several lines of evidence indicate that the high prevalence of the 30delG mutation arises from a mutation hot spot rather than from a founder effect. Genetic counseling for prelingual deafness has been so far considerably impaired by the difficulty in distinguishing genetic and non genetic deafness in families presenting with a single deaf child. Based on the results presented here, the development of a simple molecular test could be designed which should be of considerable help.

Elevation of cyclic AMP in human skin fibroblasts results in increased capacity for HDL binding

Pre-incubation of cultured human skin fibroblasts, lung fibroblasts and vascular smooth muscle cells, for 24 h with cAMP-elevating agents resulted in a significant increase (40-60%) of the cells' capacity to bind HDL. The increase was due to enhancement of the maximal binding capacity of a high affinity saturable site which binds HDL in preference to LDL. The effect was dependent upon the concentration of the cAMP-elevating agents and required more than 4 h to become evident. Cyclic AMP-mediated elevation of HDL binding occurred in cells with access to an exogenous source of cholesterol, which could be the physiological donor LDL or non-lipoprotein in origin. The observed effects were not subsequent to changes in cellular balance of cholesterol to cholesterol ester and were not due to inhibition of cellular proliferation.

Cyclic AMP stimulates the synthesis and function of the low-density lipoprotein receptor in human vascular smooth-muscle cells and fibroblasts

1. Cyclic AMP-elevating agents stimulate low-density lipoprotein (LDL) receptor activity in human vascular smooth-muscle cells by increasing the rate of receptor protein synthesis. The stimulation is not secondary to the decrease in the regulatory pool of free cholesterol, since it is unaffected, or even enhanced, by inhibition of cholesterol synthesis and esterification, or inhibition of the conversion of cholesterol into its repressor metabolites. The cyclic AMP-mediated up-regulation of the receptor is maintained at low concentrations of inhibitory sterols, but is eventually over-ridden at high concentrations of these sterols. 2. Cyclic AMP-elevating agents also stimulate the hydrolysis of lysosomal cholesterol esters, thus increasing the cellular cholesterol pool and repressing the expression of the LDL receptor. This cholesterol-mediated repressive effect of cyclic AMP can be prevented by chloroquine, which inhibits lysosomal actions, or by ketoconazole, which inhibits conversion of free cholesterol into its repressor metabolite. Thus the cyclic AMP stimulation of the LDL receptor can be masked by the rapid mobilization of free cholesterol from existing cholesterol esters within cultured cells. 3. We have observed that elevated cyclic AMP concentrations will up-regulate the LDL receptor in cholesterol-depleted human vascular smooth-muscle cells, skin fibroblasts and foetal-lung fibroblasts. We propose that our results are evidence for a cyclic AMP-stimulated, sterol-independent, control of LDL-receptor synthesis which is of widespread occurrence in human cells.

Agents which increase cyclic AMP have diverse effects on low-density-lipoprotein-receptor function in human vascular smooth-muscle cells and skin fibroblasts

Receptor-mediated binding and metabolism of low-density lipoproteins (LDL) in cultured human vascular smooth-muscle cells and skin fibroblasts are altered by increased cellular cyclic AMP concentrations. However, the LDL receptor does not respond to changes in cyclic AMP concentration in a simple manner. The activation of adenylate cyclase with forskolin, or the addition of membrane-permeant cyclic AMP analogues, initially decreases the expression of the LDL receptor, but is followed by a substantial increase in receptor expression after 24 h. This increase does not occur in the presence of inhibitors of RNA or protein synthesis, and is due to doubling of the Bmax. of the LDL receptor, without alteration of its affinity for LDL. By contrast, elevation of cyclic AMP concentration by inhibition of phosphodiesterases results in decreased receptor expression throughout the 24 h period. These two response patterns are reproducible phenomena, consistently observed in low-passaged cells derived from seven unrelated individuals.

Forensic dental training in Australia

To facilitate in the identification of victims of a major disaster a trained dental manpower reserve is required. In the state of New South Wales, Australia, an annual three-day training course has been designed to familiarize dentists from both the public and private sectors with identification techniques. The course is aimed to preserve the flexibility of personnel so that they can be utilized in a variety of roles rather than rigidly structuring the make up of a team. It is envisaged though, that in a mass disaster situation teams would be specialized into dental autopsy, antemortem or comparison roles.

Dietary cyclandelate decreases pre-established atherosclerosis in the rabbit

Rabbits were given a diet containing 1% (w/w) cholesterol for 7 weeks to initiate atherosclerosis and then transferred to a low-cholesterol diet (regression diet) with or without 0.5% (w/w) cyclandelate for 10 weeks. In those fed regression diet alone aortic atherosclerosis increased significantly. Cyclandelate treatment decreased the extent and severity of aortic atherosclerosis. Thus in rabbits receiving cyclandelate the total cholesterol and calcium content of aorta was decreased by 45% and 69% of control values, respectively. The effects of cyclandelate occurred without significant lowering of serum cholesterol or alteration of cholesterol content of liver or calcium content of serum, liver or muscle. The result suggests a specific action of cyclandelate on atheromatous accumulations of the aortic wall.

Philadelphia chromosome and terminal transferase-positive acute leukemia: similarity of terminal phase of chronic myelogenous leukemia and de novo acute presentation

Twenty-eight patients with Philadelphia chromosome (Ph1)--positive and terminal transferase (TdT)--positive acute leukemia (AL) were treated with intensive chemotherapy used for adult acute lymphoblastic leukemia (L-10 and L-10M protocols). Fifteen patients had a documented chronic phase of Ph1-positive chronic myelogenous leukemia preceding the acute transformation (TdT + BLCML) while the remaining 13 patients did not (TdT + Ph1 + AL). An overall complete remission (CR) rate of 71% was obtained with a median survival of 13 months in the responders. Clinical presentation, laboratory data, cytogenetics, response to treatment, and survivals of the two groups of patients are compared. These results appear to be similar, suggesting a common or closely related origin. Since the overall survival of those receiving chemotherapy maintenance is poor, three patients underwent allogeneic bone marrow transplantation (BMT) from histocompatibility leukocyte antigen--matched siblings after they achieved CR. One of them is a long-term survivor (35 + months) with a Ph1-negative bone marrow. New techniques such as BMT should be considered in young patients with a histocompatibility leukocyte antigen--compatible sibling once a CR has been achieved.

In vivo inhibition of hepatic lipogenesis in the rat by cyclandelate (3,3',5-trimethylcyclohexanylmandelate)

Rates of hepatic lipogenesis were measured in vivo in rats by incorporation into lipids of [3H] from injected [3H]H2O 17 hr after a single oral dose of cyclandelate (3,3',5-trimethylcyclohexanylmandelate, a vasoactive substance). Cyclandelate administration resulted in a significant inhibition (40-60%) of both sterol and fatty acid synthesis in the livers which was independent of the 3.2-fold diurnal variation in the rates of hepatic sterol and fatty acid synthesis. The inhibition of accumulation of newly synthesized fatty acid in intestine also reached statistical significance. The accumulation of newly synthesized sterol was significantly depressed in serum but did not result in any change in the concentration of serum total cholesterol. These results are interpreted in terms of the inhibitory effect of cyclandelate on hepatic 3-hydroxy-3-methylglutaryl-CoA reductase previously reported by us (Biochem. Pharmac. 32, 649, 1983).

Persistent pharyngeal pouch derivatives in the neonate

Internal branchial sinuses are rare compared to other branchial anomalies. A case is described in which such a sinus presented as an air-containing inflammatory lateral neck mass in a neonate and evidence is presented to support the theory that this originated from the fourth pharyngeal pouch. Review of six similar cases from the literature shows this to be a well-defined clinical entity.

The inhibition of hepatic S-3-hydroxy-3-methylglutaryl-CoA reductase by 3,3,5-trimethylcyclohexanol and its mandelic acid ester, cyclandelate

Rat hepatic HMGCoA reductase was found to be at least 50% inhibited 17 hr after administration of a single oral dose of 3,3,5-trimethylcyclohexanyl mandelate (cyclandelate), a vasoactive substance. This inhibition was also found in rats given the 3,3,5-trimethylcyclohexanol component but only slight inhibition was seen after an equimolar dose of mandelate. The inhibition of HMGCoA was observed both around the high point and near the low point of the diurnal activity cycle. The effect did not persist to 41 hr after treatment. There was no direct inhibition of HMGCoA reductase by trimethylcyclohexanol when added to the assay system in vitro. The in vivo effect of these inhibitors was specific for HMGCoA reductase. There was no change, neither elevation nor depression, of the amount of microsomal membrane components cytochromes b5 and P-450, not was the activity of another microsomal enzyme, arylesterase, affected by dosing with cyclandelate or trimethylcyclohexanol.

Elevation of serum high density lipoprotein cholesterol by rowachol, a proprietary mixture of six pure monoterpenes

Rowachol, a proprietary choleretic containing 6 pure monoterpenes markedly elevates serum HDL cholesterol (SHDL-C) concentrations in man. The concentration of SHDL-C showed a progressive increase in 16 patients treated with 6-9 capsules of Rowachol daily for periods of 2-28 weeks. There was no accompanying significant change in the concentrations of serum total cholesterol or triglyceride. In view of the significant inverse relationship between SHDL-C concentration and the risk of developing ischaemic heart disease, it is suggested that Rowachol and possibly other terpenes merit further investigation as possible therapeutic agents in the prevention and treatment of atheroma.

Beta-chain variants in Jamaican newborns

In an electrophoretic study of 15,661 Jamaican cord bloods, 8 rare beta-chain variants were found in 18 subjects in addition to the common beta-chain variants, Hb S and Hb C. The heterozygote frequencies for Hb S and Hb C were 10.1% and 3.7% respectively. The most frequent of the rare beta-chain variants were Hb Korle Bu (beta 73 Asp leads to Asn) (7 cases) and Hb O su-Christiansborg (beta 52 Asp leads to Asn) (3 cases). One new beta-chain variant, Hb Caribbean (beta 91 Leu leads to Arg) was found.