Inhibition of glioma growth in vivo by selective activation of the CB(2) cannabinoid receptor

The development of new therapeutic strategies is essential for the management of gliomas, one of the most malignant forms of cancer. We have shown previously that the growth of the rat glioma C6 cell line is inhibited by psychoactive cannabinoids (I. Galve-Roperh et al., Nat. Med., 6: 313-319, 2000). These compounds act on the brain and some other organs through the widely expressed CB(1) receptor. By contrast, the other cannabinoid receptor subtype, the CB(2) receptor, shows a much more restricted distribution and is absent from normal brain. Here we show that local administration of the selective CB(2) agonist JWH-133 at 50 microg/day to Rag-2(-/-) mice induced a considerable regression of malignant tumors generated by inoculation of C6 glioma cells. The selective involvement of the CB(2) receptor in this action was evidenced by: (a) the prevention by the CB(2) antagonist SR144528 but not the CB(1) antagonist SR141716; (b) the down-regulation of the CB(2) receptor but not the CB(1) receptor in the tumors; and (c) the absence of typical CB(1)-mediated psychotropic side effects. Cannabinoid receptor expression was subsequently examined in biopsies from human astrocytomas. A full 70% (26 of 37) of the human astrocytomas analyzed expressed significant levels of cannabinoid receptors. Of interest, the extent of CB(2) receptor expression was directly related with tumor malignancy. In addition, the growth of grade IV human astrocytoma cells in Rag-2(-/-) mice was completely blocked by JWH-133 administration at 50 microg/day. Experiments carried out with C6 glioma cells in culture evidenced the internalization of the CB(2) but not the CB(1) receptor upon JWH-133 challenge and showed that selective activation of the CB(2) receptor signaled apoptosis via enhanced ceramide synthesis de novo. These results support a therapeutic approach for the treatment of malignant gliomas devoid of psychotropic side effects.

Leptin induces mitochondrial superoxide production and monocyte chemoattractant protein-1 expression in aortic endothelial cells by increasing fatty acid oxidation via protein kinase A

Leptin, a circulating hormone secreted mainly from adipose tissues, is involved in the control of body weight. The plasma concentrations are correlated with body mass index, and are reported to be high in patients with insulin resistance, which is one of the major risk factors for cardiovascular disease. However, the direct effect of leptin on vascular wall cells is not fully understood. In this study, we investigated the effects of leptin on reactive oxygen species (ROS) generation and expression of monocyte chemoattractant protein-1 (MCP-1) in bovine aortic endothelial cells (BAEC). We found that leptin increases ROS generation in BAEC in a dose-dependent manner and that its effects are additive with those of glucose. Rotenone, thenoyltrifluoroacetone (TTFA), carbonyl cyanide m-chlorophenylhydrazone (CCCP), Mn(III)tetrakis (4-benzoic acid) porphyrin (MnTBAP), uncoupling protein-1 (UCP1) HVJ-liposomes, or manganese superoxide dismutase (MnSOD) HVJ-liposomes completely prevented the effect of leptin, suggesting that ROS arise from mitochondrial electron transport. Leptin increased fatty acid oxidation by stimulating the activity of carnitine palmitoyltransferase-1 (CPT-1) and inhibiting that of acetyl-CoA carboxylase (ACC), pace-setting enzymes for fatty acid oxidation and synthesis, respectively. Leptin-induced ROS generation, CPT-1 activation, ACC inhibition, and MCP-1 overproduction were found to be completely prevented by either genistein, a tyrosine kinase inhibitor, H-89, a protein kinase A (PKA) inhibitor, or tetradecylglycidate, a CPT-1 inhibitor. Leptin activated PKA, and the effects of leptin were inhibited by the cAMP antagonist Rp-cAMPS. These results suggest that leptin induces ROS generation by increasing fatty acid oxidation via PKA activation, which may play an important role in the progression of atherosclerosis in insulin-resistant obese diabetic patients.

Occurrence of Potyviruses on Yam (Dioscorea spp.) in Colombia and First Molecular Characterization of Yam mild mosaic virus

A survey to determine the prevalence of potyviruses on yams, Dioscorea alata and D. cayenensis-rotundata, was undertaken in Colombia. Two hundred fifty leaf samples showing mottling symptoms were collected on the Atlantic coast and analyzed by antigen-coated plate enzyme-linked immunosorbent assay with universal potyvirus monoclonal antibodies (Agdia, Elkhart, IN). Potyviruses were detected in 70% (165/235) of the D. alata and in 66% (10/15) of the D. cayenensis-rotundata samples. The presence of Yam mild mosaic virus (YMMV) was indicated in some of these samples by immunocapture reverse-transcriptase polymerase chain reaction performed as previously reported (1). A 600-bp fragment that included the core and C-terminal region of the coat protein gene (CP) and the 3' untranslated region (3'UTR) was amplified from a D. alata isolate using universal potyvirus primers (1), cloned, and sequenced (EMBL Acc. AJ311725). Comparison with the two previously published YMMV sequences revealed 96.1 and 97.4% identity for the deduced amino acid sequence in the CP region, 74.1 and 83.2% nucleotide identity in the 3'UTR for Papua New Guinea (AB022424 [2]) and Martinique (AJ250336) isolates, respectively. YMMV is known to be widespread on D. alata in Africa and the South Pacific and has been recently identified in the Caribbean (1). To our knowledge, this is the first report of its occurrence in Colombia. A study of its incidence and genetic diversity in South America has been undertaken. References: (1) M. Bousalem and S. Dallot. Plant Disease 84:200, 2000. (2) S. Fuji et al. Arch Virol. 144:1415, 1999.

Control of the cell survival/death decision by cannabinoids

Cannabinoids, the active components of Cannabis sativa (marijuana), and their derivatives produce a wide spectrum of central and peripheral effects, some of which may have clinical application. The discovery of specific cannabinoid receptors and a family of endogenous ligands of those receptors has attracted much attention to cannabinoids in recent years. One of the most exciting and promising areas of current cannabinoid research is the ability of these compounds to control the cell survival/death decision. Thus cannabinoids may induce proliferation, growth arrest, or apoptosis in a number of cells, including neurons, lymphocytes, and various transformed neural and nonneural cells. The variation in drug effects may depend on experimental factors such as drug concentration, timing of drug delivery, and type of cell examined. Regarding the central nervous system, most of the experimental evidence indicates that cannabinoids may protect neurons from toxic insults such as glutamaergic overstimulation, ischemia and oxidative damage. In contrast, cannabinoids induce apoptosis of glioma cells in culture and regression of malignant gliomas in vivo. Breast and prostate cancer cells are also sensitive to cannabinoid-induced antiproliferation. Regarding the immune system, low doses of cannabinoids may enhance cell proliferation, whereas high doses of cannabinoids usually induce growth arrest or apoptosis. The neuroprotective effect of cannabinoids may have potential clinical relevance for the treatment of neurodegenerative disorders such as multiple sclerosis, Parkinson's disease, and ischemia/stroke, whereas their growth-inhibiting action on transformed cells might be useful for the management of malignant brain tumors. Ongoing investigation is in search for cannabinoid-based therapeutic strategies devoid of nondesired psychotropic effects.

The CB(1) cannabinoid receptor of astrocytes is coupled to sphingomyelin hydrolysis through the adaptor protein fan

Cannabinoids exert most of their effects through the CB(1) receptor. This G protein-coupled receptor signals inhibition of adenylyl cyclase, modulation of ion channels, and stimulation of mitogen- and stress-activated protein kinases. In this article, we report that Delta(9)-tetrahydrocannabinol (THC), the major active component of marijuana, induces sphingomyelin hydrolysis in primary astrocytes but not in other cells expressing the CB(1) receptor, such as primary neurons, U373 MG astrocytoma cells, and Chinese hamster ovary cells transfected with the CB(1) receptor cDNA. THC-evoked sphingomyelin breakdown in astrocytes was also exerted by the endogenous cannabinoid anandamide and the synthetic cannabinoid HU-210 and was prevented by the selective CB(1) antagonist SR141716. By contrast, the effect of THC was not blocked by pertussis toxin, pointing to a lack of involvement of G(i/o) proteins. A role for the adaptor protein FAN in CB(1) receptor-coupled sphingomyelin breakdown is supported by two observations: 1) coimmunoprecipitation experiments show that the binding of FAN to the CB(1) receptor is enhanced by THC and prevented by SR141716; 2) cells expressing a dominant-negative form of FAN are refractory to THC-induced sphingomyelin breakdown. This is the first report showing that a G-protein-coupled receptor induces sphingomyelin hydrolysis through FAN and that the CB(1) cannabinoid receptor may signal independently of G(i/o) proteins.

Is there an astrocyte-neuron ketone body shuttle?

Ketone bodies can replace glucose as the major source of brain energy when glucose becomes scarce. Although it is generally assumed that the liver supplies extrahepatic tissues with ketone bodies, recent evidence shows that astrocytes are also ketogenic cells. Moreover, the partitioning of fatty acids between ketogenesis and ceramide synthesis de novo might control the survival/death decision of neural cells. These findings support the notion that astrocytes might supply neurons with ketone bodies in situ, and raise the possibility that astrocyte ketogenesis is a cytoprotective pathway.

The AMP-activated protein kinase prevents ceramide synthesis de novo and apoptosis in astrocytes

Fatty acids induce apoptosis in primary astrocytes by enhancing ceramide synthesis de novo. The possible role of the AMP-activated protein kinase (AMPK) in the control of apoptosis was studied in this model. Long-term stimulation of AMPK with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) prevented apoptosis. AICAR blunted fatty acid-mediated induction of serine palmitoyltransferase and ceramide synthesis de novo, without affecting fatty acid synthesis and oxidation. Prevention of ceramide accumulation by AICAR led to a concomitant blockade of the Raf-1/extracellular signal-regulated kinase cascade, which selectively mediates fatty acid-induced apoptosis. Data indicate that AMPK may protect cells from apoptosis induced by stress stimuli.

Cyclosporine-loaded polycaprolactone nanoparticles: immunosuppression and nephrotoxicity in rats

AIM

The nephrotoxicity and immunosuppressive ability of cyclosporine (CyA) incorporated into polycaprolactone nanoparticles (CyA-NP) was assessed in vitro and in vivo and compared to the effects caused by free drug (Sandimmun.

METHODS

The in vivo study included four groups (12 Wistar rats each) receiving oral CyA (10 mg/kg/day for 3 days) as an emulsion of Sandimmun in whole milk or CyA-NP and equivalent doses of empty NP or cremophor in milk as controls. CyA concentrations in blood, urine, liver, spleen and kidney at 24 h post-dosing were measured by fluorescence polarization immunoassay (FPIA). The nephrotoxicity induced by each drug treatment was determined by measuring creatinine plasma levels, malonyl dialdehyde production, and H(2)O(2) and reduced glutathione contents in glomeruli. On the other hand, the immunosuppressive effect was estimated in vivo by incubating lymphocyte suspensions obtained from CyA-, CyA-NP- and control-treated rats, as well as in vitro on lymphocyte suspensions from non-treated healthy animals.

RESULTS

Significantly higher blood, urine and tissue levels were achieved with CyA-NP compared to free CyA. However, no changes in creatinine plasma levels were detected due to either CyA or CyA-NP treatment. Only the production of H(2)O(2) in the glomeruli exhibited a significant increase as compared to control groups, but no differences could be ascribed to the different drug treatments. In vivo, the immunosuppressive activity was also comparable for both drug treatments. In contrast, CyA-NP showed a better drug uptake in vitro at concentrations above 25 microM. No immunosuppression was detected in control groups.

CONCLUSION

NP improve the oral bioavailability of CyA and its uptake by lymphocytes in vitro above 25 microM. On the contrary, specific immunosuppression and adverse effects were not simultaneously increased. Further studies are needed to clarify the results.

Ceramide: a new second messenger of cannabinoid action

Cannabinoids, the active components of Cannabis sativa (marijuana), and their endogenous counterparts exert their effects by binding to specific G(i/o)-protein-coupled receptors that modulate adenylyl cyclase, ion channels and extracellular signal-regulated kinases. Recent research has shown that the CB(1) cannabinoid receptor is coupled to the generation of the lipid second messenger ceramide via two different pathways: sphingomyelin hydrolysis, and ceramide synthesis de novo. Ceramide in turn mediates cannabinoid-induced apoptosis, as shown by in vitro and in vivo studies. These findings provide a new perspective on how cannabinoids act, and raise exciting physiological and therapeutic questions.

Effect of gonadectomy on cyclosporine pharmacokinetics in male and female rats

The present paper reports about the effect of gonadectomy on cyclosporine (CyA) pharmacokinetics in rats. The oral administration of CyA (10 mg/kg b.w.) to male rats caused two-fold higher drug blood levels than those reached by females at 24 h after the last dose (334.10 +/- 126.70 vs. 161.49 +/- 53.39 ng/ml, p < 0.05). These levels increased by about 25% in orchiectomized male rats (419.47 +/- 132.63 ng/ml) but they returned to control values after testosterone treatment (330.99 +/- 130.80 ng/ml). On the other hand, CyA blood levels (90.66 +/- 22.25 ng/ml) decreased after ovariectomy, even more in the case of gonadectomized female rats receiving estradiol replacement (67.83 +/- 24.15 ng/ml). With regards to drug distribution, the concentrations of CyA in the liver, the kidneys and the spleen at 24 h after the last dose were about 8, 5 and 6-fold higher than blood levels, respectively, regardless of animal gender. These partition coefficients were increased to 11, 7 and 9-fold by male castration suggesting a more extensive drug distribution. Contrariwise, drug tissue levels in ovariectomized rats decreased. The changes of drug blood and tissue levels among groups were not associated to the variations of metabolite concentrations in the liver or blood. Therefore, gonadectomy exerts a complex effect on CyA pharmacokinetics in rats and makes complementary studies necessary to clarify how differences in sexual hormone secretion alter CyA disposition.

Influence of atrial fibrillation on the morbido-mortality of patients on hemodialysis

BACKGROUND

The consequences of atrial fibrillation (AF) on morbido-mortality of patients on hemodialysis have not been fully explored. The objective of this study was to determine the prevalence of AF in patients on hemodialysis and to evaluate its influence on the development of thromboembolic phenomena (TEP).

METHODS

The incidence of AF in 190 patients in our hemodialysis program was assessed, and the patients were followed up for 1 year. Pertinent demographic and biochemical parameters were entered into univariate and multivariate statistical analyses to evaluate associations with overall mortality and TEP such as cerebrovascular accident, transitory ischemic accident, or peripheral embolism.

RESULTS

In 13.6% of patients, AF was found; 9.4% of these were of the permanent type. In the multivariate analysis, only increased age was associated with a higher probability of having arrhythmia (odds ratio, 1.10; 95% confidence interval, 1.03-1.17; P =.003). During follow-up, 23% of the patients with AF died compared with 6% of those in sinus rhythm (P <.05), although AF did not appear to be an independent predictive factor for death. Thirty-five percent of the patients with AF and 4% with sinus rhythm had TEP (P <.01). In the multivariate analysis, AF was identified as the only independent predictor for TEP (odds ratio, 8; 95% CI, 2.3-27; P =.0008).

CONCLUSIONS

AF is a frequent arrhythmia in patients on hemodialysis, and approximately 1 in 3 hemodialysis patients with AF had thromboembolic complications within 1 year of follow-up. These findings suggest that the consensus contraindication of prophylactic anticoagulation therapy for this group of patients may need to be redefined.

De novo-synthesized ceramide signals apoptosis in astrocytes via extracellular signal-regulated kinase

Recent observations support the importance of ceramide synthesis de novo in the induction of apoptosis. However, the downstream targets of de novo-synthesized ceramide are unknown. Here we show that palmitate incorporated into ceramide and induced apoptotic DNA fragmentation in astrocytes. These effects of palmitate were exacerbated when fatty acid breakdown was uncoupled and were not evident in neurons, which show a very low capacity to take up and metabolize palmitate. Palmitate-induced apoptosis of astrocytes was prevented by L-cycloserine and fumonisin B1, two inhibitors of ceramide synthesis de novo, and by PD098059, an inhibitor of the extracellular signal-regulated kinase (ERK) cascade. Accordingly, palmitate activated ERK by a process that was dependent on ceramide synthesis de novo and Raf-1, but independent of kinase suppressor of Ras. Other potential targets of ceramide in the control of cell fate, namely, c-Jun amino-terminal kinase, p38 mitogen-activated protein kinase, and protein kinase B, were not significantly affected in astrocytes exposed to palmitate. Results show that the Raf-1/ERK cascade is the selective downstream target of de novo-synthesized ceramide in the induction of apoptosis in astrocytes and also highlight the importance of ceramide synthesis de novo in apoptosis of astrocytes, which might have pathophysiological relevance.

Freeze-drying of polycaprolactone and poly(D,L-lactic-glycolic) nanoparticles induce minor particle size changes affecting the oral pharmacokinetics of loaded drugs

The present study was geared at identifying the conditions to stabilize poly (D,L-lactic-glycolic) (PLGA) and polycaprolactone (PCL) nanoparticles (NP) by freeze-drying with several cryoprotective agents. Differential scanning calorimetry and freeze-thawing studies were used to optimize the lyophilization process. These studies showed that all samples were totally frozen at -45 degrees C and evidenced the necessity of adding sucrose, glucose, trehalose or gelatine to preserve the properties of NP regardless of the freezing procedure. However, only 20% sucrose and 20% glucose exerted an acceptable lyoprotective effect on PLGA and PCL NP, respectively. Nonetheless, the final to initial size ratios ( approximately 1.5) indicated that particle size was slightly affected in both cases. In vivo studies with CyA-loaded PCL NP whose sizes matched those obtained after NP preparation (100 nm) and after being lyophilized (160 nm) showed that the changes of particle size might have some relevance on drug pharmacokinetics. The MRT was significantly (P<0.05) modified after an oral CyA dose of 5 mg/kg and the treatment with 160-nm sized CyA-loaded NP produced a higher drug partition into the liver of Wistar rats potentially affecting the toxic and immunosuppressive profile of the drug. Therefore, although the particle size changes induced by NP lyophilization were slight, they need to be carefully evaluated and cannot be neglected.

Skin and wound infection by rapidly growing mycobacteria: an unexpected complication of liposuction and liposculpture. The Venezuelan Collaborative Infectious and Tropical Diseases Study Group

OBJECTIVE

To describe 10 patients with skin and soft tissue infection caused by rapidly growing mycobacteria after cosmetic liposuction and liposculpture.

DESIGN

Case series.

SETTINGS

Eight private geographically separate surgical facilities from a single metropolitan area.

PATIENTS

Eight patients with definite and 2 with presumptive cases of skin and soft tissue infection caused by rapidly growing mycobacteria after cosmetic surgery procedures during a 24-month period. Microorganisms were isolated from the purulent drainage obtained from wounds or fistulas in 8 cases and were identified as Mycobacterium fortuitum (3 cases) and Mycobacterium abscessus (5 cases) by routine microbiologic techniques. Acid-fast bacilli were observed on Ziehl-Neelsen-stained smears in the 2 remaining cases, but these ultimately failed to grow. In 2 of the surgical units, no apparent environmental predisposing factors were identified after thorough microbiologic environmental investigation. Clinically, all patients exhibited signs of inflammation, microabscesses, and purulent wound drainage within 24 months of abdominal and/or thigh liposuction or homologous fat tissue injection.

INTERVENTION

A combined therapeutic approach including surgical drainage, debridment, and prolonged (>3 months) treatment with combined antimicrobial agents including clarithromycin was used in all cases.

RESULTS

Nine of 10 patients responded to the combined therapeutic approach, and no evidence of infection was present during at least 12 months of follow-up.

CONCLUSION

To our knowledge, this is the first series of patients with rapidly growing mycobacterial infections to be described after liposuction and liposculpture. Rapidly growing mycobacteria should be included in the differential diagnosis of skin and soft tissue infection after cosmetic surgery.

The CB(1) cannabinoid receptor is coupled to the activation of c-Jun N-terminal kinase

Cannabinoids exert most of their effects through the CB(1) receptor. This G-protein-coupled receptor has been shown to be functionally coupled to inhibition of adenylyl cyclase, modulation of ion channels, and activation of extracellular signal-regulated kinase. Using Chinese hamster ovary cells stably transfected with the CB(1) receptor cDNA, we show here that Delta(9)-tetrahydrocannabinol (THC), the major active component of marijuana, induces the activation of c-Jun N-terminal kinase (JNK). Western blot analysis showed that both JNK-1 and JNK-2 were stimulated by THC. The effect of THC was also exerted by endogenous cannabinoids (anandamide and 2-arachidonoylglycerol) and synthetic cannabinoids (CP-55,940, HU-210, and methanandamide), and was prevented by the selective CB(1) antagonist SR141716. Pertussis toxin, wortmannin, and a Ras farnesyltransferase inhibitor peptide blocked, whereas mastoparan mimicked, the CB(1) receptor-evoked activation of JNK, supporting the involvement of a G(i)/G(o)-protein, phosphoinositide 3'-kinase and Ras. THC-induced JNK stimulation was prevented by tyrphostin AG1296, pointing to the implication of platelet-derived growth factor receptor transactivation, and was independent of ceramide generation. Experiments performed with several types of neural cells that endogenously express the CB(1) receptor suggested that long-term JNK activation may be involved in THC-induced cell death. The CB(1) cannabinoid receptor was also shown to be coupled to the activation of p38 mitogen-activated protein kinase. Data indicate that activation of JNK and p38 mitogen-activated protein kinase may be responsible for some of the cellular responses elicited by the CB(1) cannabinoid receptor.

Effect of nanoparticles on digitoxin uptake and pharmacologic activity in rat glomerular mesangial cell cultures

Our experiments analyzed the uptake of free and nanoparticles (NP)-associated digitoxin (DGT) by rat glomerular mesangial cells. NP were prepared by the nanoprecipitation method using the biodegradable polyester, polycaprolactone (PCL). Prior to in vitro experiments, the systems were characterized by means of spectrofluorimetry, dynamic light scattering, and size exclusion chromatography (SEC). The loading efficiency was 80.30 +/- 1.03% of the initial DGT amount in the preparation, and the average particle size was 176 +/- 8 and 161 +/- 6 nm for DGT-NP and "empty" NP, respectively. SEC studies revealed noncovalent interactions among the different chemical compounds in the formulation. In vitro experiments were conducted at 37 degrees C and pH 7.5 by incubating "empty" NP, free DGT or DGT-NP (10 microg PCL/mL; 100 ng DGT/mL) with glomerular mesangial cells for 30 and 60 min. Uptake of DGT by the cells was favored by its incorporation into PCL-NP and showed time dependency. After 30 min of incubation, no significant differences of drug uptake were seen between free DGT (13.1 +/- 2.8%) or DGT-NP (17.4 +/- 4.9%); however, the uptake of DGT, when it was associated to the polymeric carrier, increased by approximately 2-fold (37.8 +/- 5.7%) at 60 min, whereas no significant changes were observed for free drug (20.0 +/- 6.8%). The pharmacologic activity of the drug was evaluated by measuring the planar cell surface area (PCSA). "Empty" NP, free drug, or DGT-NP did not produce significant variations on the PCSA as compared with control cells after a 30-min incubation. Nonetheless, DGT-NP reduced the PCSA to 82.51 +/- 8.42% of control values when the incubation lasted 60 min. The ability of cells to exclude the trypan blue dye and the leakage of lactate dehydrogenase into the medium revealed no signs of increased toxicity from incorporation of DGT into PCL-NP. Therefore, PCL-NP improved drug uptake by the cells without altering the pharmacologic activity and toxicity of the drug. Thus, they can be a useful approach to target drugs to the kidneys or the heart.

Perioperative outcomes in octogenarians undergoing cardiac surgery in Puerto Rico

With the advances in surgical techniques and the advent of an aging population, the application of cardiac surgeries has broadened to include those patients over the age of 80. In order to characterize the in-hospital morbidity and mortality of elderly patients undergoing cardiac surgery at our cardiovascular center, a retrospective review of all medical records of consecutive octogenarian patients was made. Between January 1998 and April 1999, 76 patients (mean age (SD), 82.5 (2.6)) underwent cardiac surgery, of which, 61.8% were males. Surgical procedures consisted of isolated coronary artery bypass grafting (CABG) in 64 patients, isolated aortic valve replacement (AVR) in 4 patients, combined CABG and left carotid endarterectomy in 4 patients, combined CABG and AVR in 2 patients, combined CABG and aortic aneurysm repair in 1 patient and combined AVR and aortic dissection repair in 1 patient. Surgery was elective in 51.3% of patients and seventy-one percent (54) experienced at least one postoperative complication. The most common complication was atrial arrhythmia (28) followed by low cardiac output (23) and pneumonia (16). Hospital mortality occurred in 11 (14.7%) patients, an estimate in agreement with previous published studies on octogenarians. Since the number of patients studied was small, these results require confirmation by other cardiovascular centers in the island. Further research to determine independent predictors of postoperative morbidity and mortality, to assess survival and quality of life after cardiac surgery and to evaluate cost-effectiveness considering new trends in managed health care is warranted.

The CB1 cannabinoid receptor is coupled to the activation of protein kinase B/Akt

Cannabinoids exert most of their effects in the central nervous system through the CB(1) cannabinoid receptor. This G-protein-coupled receptor has been shown to be functionally coupled to inhibition of adenylate cyclase, modulation of ion channels and activation of extracellular-signal-regulated kinase. Using Chinese hamster ovary cells stably transfected with the CB(1) receptor cDNA we show here that Delta(9)-tetrahydrocannabinol (THC), the major active component of marijuana, induces the activation of protein kinase B/Akt (PKB). This effect of THC was also exerted by the endogenous cannabinoid anandamide and the synthetic cannabinoids CP-55940 and HU-210, and was prevented by the selective CB(1) antagonist SR141716. Pertussis toxin and wortmannin blocked the CB(1) receptor-evoked activation of PKB, pointing to the sequential involvement of a G(i)/G(o) protein and phosphoinositide 3'-kinase. The functionality of the cannabinoid-induced stimulation of PKB was proved by the increased phosphorylation of glycogen synthase kinase-3 serine 21 observed in cannabinoid-treated cells and its prevention by SR141716 and wortmannin. Cannabinoids activated PKB in the human astrocytoma cell line U373 MG, which expresses the CB(1) receptor, but not in the human promyelocytic cell line HL-60, which expresses the CB(2) receptor. Data indicate that activation of PKB may be responsible for some of the effects of cannabinoids in cells expressing the CB(1) receptor.

Dependency of cyclosporine tissue distribution and metabolism on the age and gender of rats after a single intravenous dose

In a previous study we demonstrated the dependency of cyclosporine (CyA) pharmacokinetics on the age and gender of Wistar rats given 10 mg/kg intravenously. The present study has been conducted under the same experimental conditions (10 mg/kg as a single intravenous dose) to identify the mechanisms behind such differences. On the one hand, drug distribution was studied by measuring the CyA levels in blood, liver, kidney, spleen, adipose tissue, skin and muscle at 48 h post-treatment by using a specific fluorescence polarization immunoassay (m-FPIA, Abbott Laboratories). Drug blood and tissue levels in male rats were significantly higher than the female counterparts except for adipose tissue where the concentrations were 2-fold higher in females. In males, the highest CyA concentrations were observed in the liver, followed in rank order by kidney and spleen, fat, skin, muscle, then blood. On the contrary, females showed the highest drug levels in fat, followed by liver, kidney, spleen, skin, muscle and blood. Age exerted a significant influence on CyA tissue levels in males but no effect was observed in females. The potential differences in drug metabolism were established by measuring (HPLC) the amounts of CyA and its metabolites accumulated in faeces after hepatic biotransformation and biliary excretion. The amounts of circulating metabolites in blood as well as those accumulated and excreted in the liver and urine were also estimated by using specific (m-FPIA) and non-specific fluorescence polarization immunoassay (p-FPIA, Abbott Laboratories), respectively. The analysis of faeces revealed that AM9 was the major identified metabolite with females excreting lower amounts of unchanged CyA than males. In addition, the comparison of the AUC values corresponding to parent CyA and total CyA derivatives suggested that blood concentrations of CyA metabolites were higher in females indicating higher biotransformation rates. Therefore, both CyA distribution and metabolism are responsible for the sex-associated differences in drug pharmacokinetics previously found in rats.

Anti-tumoral action of cannabinoids: involvement of sustained ceramide accumulation and extracellular signal-regulated kinase activation

Delta9-Tetrahydrocannabinol, the main active component of marijuana, induces apoptosis of transformed neural cells in culture. Here, we show that intratumoral administration of Delta9-tetrahydrocannabinol and the synthetic cannabinoid agonist WIN-55,212-2 induced a considerable regression of malignant gliomas in Wistar rats and in mice deficient in recombination activating gene 2. Cannabinoid treatment did not produce any substantial neurotoxic effect in the conditions used. Experiments with two subclones of C6 glioma cells in culture showed that cannabinoids signal apoptosis by a pathway involving cannabinoid receptors, sustained ceramide accumulation and Raf1/extracellular signal-regulated kinase activation. These results may provide the basis for a new therapeutic approach for the treatment of malignant gliomas.

Do cytoskeletal components control fatty acid translocation into liver mitochondria?

For two decades it has been assumed that inhibition of carnitine palmitoyltransferase I (CPT-I) by malonyl-CoA represents the main regulatory mechanism of liver ketogenesis. However, recent evidence indicates that CPT-I activity is also controlled by interactions between mitochondria and cytoskeletal components. This newly recognized mechanism emphasizes the emerging role of the cytoskeleton in the regulation of metabolic pathways.

Increasing anther culture efficiency in rice (Oryza sativa L.) using anthers from ratooned plants

Anther culture response for the variety Taipei-309 was compared using anthers of ratooned and non-ratooned plants. Anthers were plated onto N6 liquid media with 0, 2, 5, and 10 mg l(-1) ABA, respectively. After 5 days in culture, the media were removed and N6 medium without ABA was added. A higher number of pre-mitotic P-pollen grains were observed in anthers from ratooned plants. A significant synergistic effect was found between anthers from ratooned plants/ABA concentrations and the increase in embryogenic-like structures (ELS) induction and green plant regeneration efficiency. The highest frequency of anthers producing ELS was found in N6 medium (6% Sucrose and 2 mg l(-1) 2,4-D) with 5 and 10 mg l(-1) ABA for anthers derived from ratooned plants. Mean green plant regeneration efficiencies were raised from 24.2 to 42% (non-ratooned), and from 30 to 70%, (ratooned donor plants) using a combination of 10 mg l(-1) ABA in induction media, and MS with 2 mg l(-1) BAP, 1 mg l(-1) NAA, 2 mg l(-1) kinetin and 0.45% agarose. The highest number of green shoots per ELS were obtained from ratooned-derived anthers (up to 82). The use of ratooned plants in anther culture, its importance and relative advantages are also discussed.

Involvement of the cAMP/protein kinase A pathway and of mitogen-activated protein kinase in the anti-proliferative effects of anandamide in human breast cancer cells

Anandamide (ANA) inhibits prolactin- and nerve growth factor (NGF)-induced proliferation of human breast cancer cells by decreasing the levels of the 100 kDa prolactin receptor (PRLr) and the high affinity trk NGF receptor, respectively, and by acting via CB(1)-like cannabinoid receptors. However, the intracellular signals that mediate these effects are not known. Here, we show that, in MCF-7 cells: (i) forskolin and the mitogen-activated protein kinase (MAPK) kinase inhibitor PD098059 prevent, and the protein kinase A inhibitor RpcAMPs mimics, the inhibitory effects of ANA on cell proliferation and PRLr/trk expression and (ii) ANA inhibits forskolin-induced cAMP formation and stimulates Raf-1 translocation and MAPK activity, in a fashion sensitive to the selective CB(1) antagonist SR141716A. ANA stimulation of MAPK was enhanced by inhibitors of ANA hydrolysis. Forskolin inhibited MAPK and ANA-induced Raf-1 translocation. These findings indicate that, in MCF-7 cells, ANA inhibits adenylyl cyclase and activates MAPK, thereby exerting a down-regulation on PRLr and trk levels and a suppression of cell proliferation.

The AMP-activated protein kinase is involved in the regulation of ketone body production by astrocytes

The possible role of the AMP-activated protein kinase (AMPK), a highly conserved stress-activated kinase, in the regulation of ketone body production by astrocytes was studied. AMPK activity in rat cortical astrocytes was three times higher than in rat cortical neurons. AMPK in astrocytes was shown to be functionally active. Thus, incubation of astrocytes with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), a cell-permeable activator of AMPK, stimulated both ketogenesis from palmitate and carnitine palmitoyltransferase I. This was concomitant to a decrease of intracellular malonyl-CoA levels and an inhibition of acetyl-CoA carboxylase/fatty acid synthesis and 3-hydroxy-3-methylglutaryl-CoA reductase/cholesterol synthesis. Moreover, in microdialysis experiments AICAR was shown to stimulate brain ketogenesis markedly. The effect of chemical hypoxia on AMPK and the ketogenic pathway was studied subsequently. Incubation of astrocytes with azide led to a remarkable drop of fatty acid beta-oxidation. However, activation of AMPK during hypoxia compensated the depression of beta-oxidation, thereby sustaining ketone body production. This effect seemed to rely on the cascade hypoxia --> increase of the AMP/ATP ratio --> AMPK stimulation --> acetyl-CoA carboxylase inhibition --> decrease of malonyl-CoA concentration --> carnitine palmitoyltransferase I deinhibition --> enhanced ketogenesis. Furthermore, incubation of neurons with azide blunted lactate oxidation, but not 3-hydroxybutyrate oxidation. Results show that (a) AMPK plays an active role in the regulation of ketone body production by astrocytes, and (b) ketone bodies produced by astrocytes during hypoxia might be a substrate for neuronal oxidative metabolism.

A polycaprolactone nanoparticle formulation of cyclosporin-A improves the prediction of area under the curve using a limited sampling strategy

Therapeutic monitoring of Cyclosporine (CyA) by using area under the curve (AUC) from abbreviated kinetic profiles is of recent trend in clinical practice due to the potential improvement in transplant and clinical outcome with costs reduction in mind. Several papers describe successful use of the limited sampling strategy to predict AUCs in different transplant populations when treated with Sandimmun or Sandimmun Neoral. However, the same predictive potential is achieved for the latter formulation with lesser effort. The present paper describes the application of the limited sampling strategies to demonstrate the advantages of using CyA incorporated in polymeric nanoparticles (CyA-NP) as compared to two reference Sandimmun formulations which consisted of an emulsion of the oily solution in milk (SIM-EM) and a microemulsion (SIM-Neoral) formerly tried on rats. Two independent data batches were used: group 1 which included 36, 31 and 10 animals receiving SIM-EM, CyA-NP and SIM-Neoral, respectively, and group 2 made of nine and eight rats treated with SIM-EM and CyA-NP. Several limited sampling equations were derived for each formulation from group 1 by stepwise multiple linear regression. Statistical analysis disclosed that CyA concentrations 8 and 32 h after dose administration vouched for 88 and 69% variability in AUC (0-48 h) for CyA-NP and SIM-EM, respectively. When summed up, these two concentrations revealed nearly 97% of AUC (0-48 h) variability. CyA concentrations 8 h post-treatment with SIM-Neoral explained 89% variability in AUC (0-48 h). This value raised to 98% when a second CyA concentration (24 h) was introduced. The equations derived from group 1 were then employed to predict AUCs in group 2. CyA blood levels at 8 h post-treatment confirmed AUC for CyA-NP (r(2)=0.98) to be very precise and unbiased (error=1. 46%, interval -16.2 to 21.33%), while the results for SIM-EM obtained with the CyA concentration at 32 h were r(2)=0.93 plus error=5.71%, interval -44.33 to 105.94%. Similar results were obtained when the study period was reduced to 24 h. The use of these limited sampling models manifested the coincidence between CyA-NP and SIM-Neoral as well as the advantages of both formulations over SIM-EM when it comes to CyA monitoring.

Effects of cannabinoids on energy metabolism

The present review summarizes the recent work carried out by our group on the link between signal transduction pathways and metabolic regulation systems as affected by cannabinoids. In cells such as astrocytes and lymphocytes, which express cannabinoid receptors, physiologically relevant doses of cannabinoids induce a remarkable metabolic stimulation as determined e.g. by enhanced glucose utilization. Studies performed in astrocytes show that the cannabinoid-evoked stimulation of glucose metabolism is independent of adenylyl cyclase inhibition, and seems to rely on the cascade CB1 cannabinoid receptor --> Sphingomyelin breakdown --> Ceramide --> Raf-1 --> Mitogen-activated protein kinase (MAPK) --> Glucose utilization. A role for phosphoinositide 3'-kinase in the stimulation of glucose utilization by cannabinoids is also put forward. In addition, ceramide generated upon CB1 cannabinoid receptor activation may enhance ketone body production by astrocytes independently of MAPK. Anandamide has also been shown to exert metabolic effects in hepatocytes, cells that do not express cannabinoid receptors. The biological role of cannabinoids as modulators of metabolism is as yet unclear.

Stability and freeze-drying of cyclosporine loaded poly(D,L lactide-glycolide) carriers

The present paper describes the stability of poly (D, L-lactide-glycolide) nanoparticles (PLGA NP) and microspheres (MS), either alone or loaded with cyclosporine (CyA), stored at 8 degrees C and room temperature (RT). Freeze-drying of these formulations was evaluated as an alternative method to achieve long term stability. A significant polymer rupture was detected during PLGA MS preparation by solvent evaporation, which correlated with the stirring rates used for the formation of the primary emulsion. On the other hand, the polymer remained unchanged during NP formation. After 6 months of storage, PLGA NP of a size below 80 nm aggregated when stored at RT whereas no changes of particle size were observed for the remaining formulations and experimental conditions. Drug entrapment significantly increased by about 9.5% only during PLGA NP storage at RT. The PLGA molecular weight of NP dropped at RT being these changes related to the initial particle size and amount of CyA incorporated. The same effect was observed at 8 degrees C but only the particle size showed a significant influence. The drop of PLGA molecular weight observed during storage of MS was not dependent on the storage temperature but it was directly related to the molecular weights obtained after MS preparation. Freeze-drying studies revealed that it was not feasible to maintain the initial PLGA NP characteristics after reconstitution. On the other hand, MS lyophilized in the absence of cryoprotectants retained the drug initially entrapped; however, the presence of at least 5% cryoprotectant was essential to keep the initial particle size. Therefore, PLGA NP and MS show a significant instability when stored as suspensions. Freeze-drying offers a good alternative to stabilize polymeric MS but the preservation of the PLGA NP characteristics by freeze-drying needs for further investigations.

The stimulation of ketogenesis by cannabinoids in cultured astrocytes defines carnitine palmitoyltransferase I as a new ceramide-activated enzyme

The effects of cannabinoids on ketogenesis in primary cultures of rat astrocytes were studied. Delta9-Tetrahydrocannabinol (THC), the major active component of marijuana, produced a malonyl-CoA-independent stimulation of carnitine palmitoyltransferase I (CPT-I) and ketogenesis from [14C]palmitate. The THC-induced stimulation of ketogenesis was mimicked by the synthetic cannabinoid HU-210 and was prevented by pertussis toxin and the CB1 cannabinoid receptor antagonist SR141716. Experiments performed with different cellular modulators indicated that the THC-induced stimulation of ketogenesis was independent of cyclic AMP, Ca2+, protein kinase C, and mitogen-activated protein kinase (MAPK). The possible involvement of ceramide in the activation of ketogenesis by cannabinoids was subsequently studied. THC produced a CB1 receptor-dependent stimulation of sphingomyelin breakdown that was concomitant to an elevation of intracellular ceramide levels. Addition of exogenous sphingomyelinase to the astrocyte culture medium led to a MAPK-independent activation of ketogenesis that was quantitatively similar and not additive to that exerted by THC. Furthermore, ceramide activated CPT-I in astrocyte mitochondria. Results thus indicate that cannabinoids stimulate ketogenesis in astrocytes by a mechanism that may rely on CB1 receptor activation, sphingomyelin hydrolysis, and ceramide-mediated activation of CPT-I.

Metabolism of trans fatty acids by hepatocytes

The present work was undertaken to study the metabolism of fatty acids with trans double bonds by rat hepatocytes. In liver mitochondria, elaidoyl-CoA was a poorer substrate for carnitine palmitoyltransferase I (CPT-I) than oleoyl-CoA. Likewise, incubation of hepatocytes with oleic acid produced a more pronounced stimulation of CPT-I than incubation with trans fatty acids. This was not due to a differential effect of cis and trans fatty acids on acetyl-CoA carboxylase (ACC) activity and malonyl-CoA levels. Elaidic acid was metabolized by hepatocytes at a higher rate than oleic acid. Surprisingly, compared to oleic acid, elaidic acid was a better substrate for mitochondrial and, especially, peroxisomal oxidation, but a poorer substrate for cellular and very low density lipoprotein triacylglycerol synthesis. Results thus show that trans fatty acids are preferentially oxidized by hepatic peroxisomes, and that the ACC/malonyl-CoA/CPT-I system for coordinate control of fatty acid metabolism is not responsible for the distinct hepatic utilization of cis and trans fatty acids.

Early postoperative complications after coronary artery bypass grafting at the Cardiovascular Center of Puerto Rico and the Caribbean

OBJECTIVES

This study describes the preoperative cardiovascular characteristics, intraoperative data, in-hospital complications and factors associated to procedural-related complications in patients undergoing coronary artery bypass grafting (CABG).

BACKGROUND

There is a growing body of evidence of CABG safety and efficacy; however, limited data is available regarding the value of this surgical procedure in the Puerto Rican population.

METHODS

We retrospectively reviewed the medical records of 200 consecutive patients submitted to CABG at the Cardiovascular Center of Puerto Rico and the Caribbean over a three-month period in 1997. Bivariate and multivariate analyses were performed to determine factors associated with the occurrence of complications.

RESULTS

The most frequent cardiac risk factor was hypertension (77%); stable angina (60.5%) was the predominant cardiac clinical diagnosis. Three vessel disease with proximal left anterior descending coronary artery stenosis (42.1%) was the most common anatomical lesion. The rate of major complications such as death (3%), perioperative myocardial infarction (2%), reoperation to control bleeding (1.5%), pulmonary embolism (1%), and stroke (1%) was low and similar to the rate reported elsewhere. Multivariate analysis showed that non-use of LIMA graft, extended hospital stay, prolonged cardiopulmonary bypass time, and left ventricular dysfunction were significantly associated with the occurrence of complications (p < 0.05); on the other hand, there was a trend for older age to be associated with the occurrence of complications (p = 0.057).

CONCLUSIONS

CABG is being performed with an acceptably low complication rate in this institution.

Loss of response of carnitine palmitoyltransferase I to okadaic acid in transformed hepatic cells

The specific activity of carnitine palmitoyltransferase I (CPT-I) was similar in mitochondria isolated from rat Fao and human HepG2 hepatoma cells and from rat hepatocytes, but almost twofold higher in permeabilized hepatoma cells than in permeabilized hepatocytes. Short-term exposure to okadaic acid induced a ca. 80% stimulation of CPT-I in hepatocytes, whereas no significant response of the enzyme from hepatoma cells was evident. Thus, the high CPT-I activity displayed by hepatoma cells may be reached by hepatocytes upon challenge to okadaic acid. Reconstitution experiments with purified mitochondrial and cytoskeletal fractions showed that the cytoskeleton of hepatocytes produced a more remarkable inhibition of CPT-I than the cytoskeleton of Fao cells. The present data may be explained by a disruption of interactions between CPT-I and cytoskeletal components in tumor cells that may be involved in the okadaic acid-induced activation of hepatic CPT-I as previously suggested.

Evidence that the AMP-activated protein kinase stimulates rat liver carnitine palmitoyltransferase I by phosphorylating cytoskeletal components

The activity of hepatic carnitine palmitoyltransferase I (CPT-I) may be modulated by interactions with cytoskeletal components [Velasco et al. (1998) J. Biol. Chem. 273, 21497-21504]. We have studied whether the AMP-activated protein kinase (AMPK) is involved in this process. AMPK stimulated CPT-I in permeabilized hepatocytes but not in isolated liver mitochondria. In addition, AMPK abrogated the inhibition of CPT-I of isolated mitochondria induced by a cytoskeletal fraction. These two effects of AMPK were not evident when the kinase was inactivated by pretreatment with protein phosphatase 2C. Cytokeratins 8 and 18 were phosphorylated by AMPK in vitro and by incubation of intact hepatocytes with 5-aminoimidazole-4-carboxamide ribonucleoside, a cell-permeable activator of AMPK. These results provide the first evidence that AMPK stimulates CPT-I by direct phosphorylation of cytoskeletal components.

Involvement of sphingomyelin hydrolysis and the mitogen-activated protein kinase cascade in the Delta9-tetrahydrocannabinol-induced stimulation of glucose metabolism in primary astrocytes

The effects of cannabinoids on metabolic pathways and signal transduction systems were studied in primary cultures of rat astrocytes. Delta9-Tetrahydrocannabinol (THC), the major active component of marijuana, increased the rate of glucose oxidation to CO2 as well as the rate of glucose incorporation into phospholipids and glycogen. These effects of THC were mimicked by the synthetic cannabinoid HU-210, and prevented by forskolin, pertussis toxin, and the CB1 receptor antagonist SR 141716. THC did not affect basal cAMP levels but partially antagonized the forskolin-induced elevation of intracellular cAMP concentration. THC stimulated p42/p44 mitogen-activated protein kinase (MAPK) activity, Raf-1 phosphorylation, and Raf-1 translocation to the particulate cell fraction. In addition, the MAPK inhibitor PD 098095 and the phosphoinositide 3-kinase inhibitors wortmannin and LY 294002 were able to antagonize the THC-induced stimulation of glucose oxidation to CO2, phospholipid synthesis and glycogen synthesis. The possible involvement of sphingomyelin breakdown in the metabolic effects of THC was studied subsequently. THC produced a rapid stimulation of sphingomyelin hydrolysis that was concomitant to an elevation of intracellular ceramide levels. This effect was prevented by SR 141716. Moreover, the cell-permeable ceramide analog D-erythro-N-octanoylsphingosine, as well as exogenous sphingomyelinase, were able in turn to stimulate MAPK activity, to increase the amount of Raf-1 bound to the particulate cell fraction, and to stimulate glucose metabolism. The latter effect was prevented by PD 098059 and was not additive to that exerted by THC. Results thus indicate that THC produces a cannabinoid receptor-mediated stimulation of astrocyte metabolism that seems to rely on sphingomyelin hydrolysis and MAPK stimulation.

Role of carnitine palmitoyltransferase I in the control of ketogenesis in primary cultures of rat astrocytes

The role of carnitine palmitoyltransferase I (CPT-I) in the control of ketogenesis was studied in primary cultures of rat astrocytes. Ketone bodies were the major product of [14C]palmitate oxidation by cultured astrocytes, whereas CO2 made a minor contribution to the total oxidation products. Using tetradecylglycidate as a specific, cell-permeable inhibitor of CPT-I, a flux control coefficient of 0.77 +/- 0.07 was calculated for CPT-I over the flux of [14C]palmitate to ketone bodies. CPT-I from astrocytes was sensitive to malonyl-CoA (IC50 = 3.4 +/- 0.8 microM) and cross-reacted on western blots with an antibody raised against liver CPT-I. On the other hand, astrocytes expressed significant acetyl-CoA carboxylase (ACC) activity, and consequently they contained considerable amounts of malonyl-CoA. Western blot analysis of ACC isoforms showed that ACC in astrocytes--like in neurons, liver, and white adipose tissue--mostly comprised the 265-kDa isoform, whereas the 280-kDa isoform--which was highly expressed in skeletal muscle--showed much lower abundance. Forskolin was used as a tool to study the modulation of the ketogenic pathway in astrocytes. Thus, forskolin decreased in parallel ACC activity and intracellular malonyl-CoA levels, whereas it stimulated CPT-I activity and [14C]palmitate oxidation to both ketone bodies and CO2. Results show that in cultured astrocytes (a) CPT-I exerts a very high degree of control over ketogenesis from palmitate, (b) the ACC/malonyl-CoA/CPT-I system is similar to that of liver, and (c) the ACC/malonyl-CoA/CPT-I system is subject to regulation by cyclic AMP.

Delta9-tetrahydrocannabinol induces apoptosis in C6 glioma cells

delta9-Tetrahydrocannabinol (THC), the major active component of marijuana, induced apoptosis in C6.9 glioma cells, as determined by DNA fragmentation and loss of plasma membrane asymmetry. THC stimulated sphingomyelin hydrolysis in C6.9 glioma cells. THC and N-acetylsphingosine, a cell-permeable ceramide analog, induced apoptosis in several transformed neural cells but not in primary astrocytes or neurons. Although glioma C6.9 cells expressed the CBI cannabinoid receptor, neither THC-induced apoptosis nor THC-induced sphingomyelin breakdown were prevented by SR141716, a specific antagonist of that receptor. Results thus show that THC-induced apoptosis in glioma C6.9 cells may rely on a CBI receptor-independent stimulation of sphingomyelin breakdown.

[Eradication of measles in Cuba]

The vaccine against measles came into use in Cuba in 1971. During the seventies, a new early strategy for measles control was established, and it was followed by further efforts in the early eighties. Despite improvements to the control program, disease outbreaks continued to occur. In 1986, after examining the experience acquired through the control initiatives that were already in place, a new measles vaccination strategy was adopted. In time, the new vaccination strategy against measles came to have three main components: first, a single vaccination "catching-up" campaign targeting children 1 to 14 years of age. Second, efforts were made to achieve and maintain high vaccine coverage through mandatory vaccination services for 12-month-old children ("maintenance vaccination"). Finally, periodic "follow-up" campaigns were carried out for children 2 to 6 years of age. Steps were taken, for the purpose of monitoring the progress made so far toward eliminating measles, to strengthen disease surveillance systems, including the screening of suspected cases. The "catching-up" and "follow-up" campaigns both achieved greater than 98% coverage within targeted age groups. The routine vaccination program has also maintained high coverage. The high population immunity against measles that has been attained through these vaccination strategies has resulted in a rapid decrease in the incidence of the disease. From 1989 to 1992, less than 20 laboratory-confirmed cases were reported annually. In Cuba, the last case confirmed through serologic screening was reported in July 1993. Cuba's strategy for measles elimination has interrupted disease transmission and kept the causal virus from circulating on the island. Cuba's experience with measles elimination suggests that if an appropriate vaccination strategy is applied, measles can be globally eradicated.

Malonyl-CoA-independent acute control of hepatic carnitine palmitoyltransferase I activity. Role of Ca2+/calmodulin-dependent protein kinase II and cytoskeletal components

The mechanism of malonyl-CoA-independent acute control of hepatic carnitine palmitoyltransferase I (CPT-I) activity was investigated. In a first series of experiments, the possible involvement of the cytoskeleton in the control of CPT-I activity was studied. The results of these investigations can be summarized as follows. (i) Very mild treatment of permeabilized hepatocytes with trypsin produced around 50% stimulation of CPT-I activity. This effect was absent in cells that had been pretreated with okadaic acid (OA) and seemed to be due to the action of trypsin on cell component(s) distinct from CPT-I. (ii) Incubation of intact hepatocytes with 3, 3'-iminodipropionitrile, a disruptor of intermediate filaments, increased CPT-I activity in a non-additive manner with respect to OA. Taxol, a stabilizer of the cytoskeleton, prevented the OA- and 3, 3'-iminodipropionitrile-induced stimulation of CPT-I. (iii) CPT-I activity in isolated mitochondria was depressed in a dose-dependent fashion by the addition of a total cytoskeleton fraction and a cytokeratin-enriched cytoskeletal fraction, the latter being 3 times more potent than the former. In a second series of experiments, the possible link between Ca2+/calmodulin-dependent protein kinase II (Ca2+/CM-PKII) and the cytoskeleton was studied in the context of CPT-I regulation. The data of these experiments indicate that (i) purified Ca2+/CM-PKII activated CPT-I in permeabilized hepatocytes but not in isolated mitochondria, (ii) purified Ca2+/CM-PKII abrogated the inhibition of CPT-I of isolated mitochondria induced by a cytokeratin-enriched fraction, and (iii) the Ca2+/CM-PKII inhibitor KN-62 prevented the OA-induced phosphorylation of cytokeratins in intact hepatocytes. Results thus support a novel mechanism of short-term control of hepatic CPT-I activity which may rely on the cascade Ca2+/CM-PKII activation --> cytokeratin phosphorylation --> CPT-I de-inhibition.

[Detection of IgM against the dengue++ virus in whole blood absorbed on filter paper]

This paper presents a standardized procedure for the detection of IgM antibodies to dengue virus in blood samples taken from filter paper. The samples were obtained from 118 patients, of whom 91 had been clinically diagnosed with dengue and 27 with a viral infection unrelated to that disease. The first group of patients came from Costa Rica and Nicaragua and the second group from Cuba. All the samples were tested for IgM antibody against dengue virus by means of a capture enzyme immunoassay (EIA). Analysis of the results for patients from all three countries together yielded a sensitivity of 98.1% and a specificity of 98.5% for the test done on whole blood on filter paper stored at 4 degrees C; agreement between the results of that test and those of the EIA using serum samples was 96%. In a comparison of the results obtained with three samples from the same patient--whole blood on filter paper stored at room temperature, the same type of sample stored at 4 degrees C, and serum--the agreement was 86%. This study demonstrates the high diagnostic sensitivity and specificity achieved when whole blood absorbed on filter paper is processed in the manner described in detail in the article. The authors recommend the use of this method in the dengue surveillance programs in the Region.

The role of priority programmes in the provision of health services in the state of Oaxaca, Mexico

An assessment of the performance of five priority health programmes (basic sanitation, tuberculosis, vaccination, acute respiratory infections and acute diarrheal diseases) was carried out using ethnographic techniques in the region of La Cañada in the state of Oaxaca, Mexico. The region presents a large percentage of Indian and peasant population living in extreme poverty and health care is mainly provided by the Ministry of Health. Both characteristics of the population and the health services are used to analyze the performance of the programmes. With access to abundant resources, vaccination and diarrheal disease programmes have been highly successful in involving the population and achieving their operative targets. Consequently this capacity to concentrate resources results in a lack of resources for other programmes. Despite partial successes, all programmes face serious operational difficulties demonstrating, in turn, the lack of capacity of health services to respond to the specific demands of local populations. The information presented is relevant for the discussion of selective versus comprehensive PHC.

Stability of cyclosporine-loaded poly-sigma-caprolactone nanoparticles

The aim was to evaluate the long-term stability of cyclosporin A-loaded nanoparticle suspensions, stored at 8 and 25 degrees C. The stability of freeze-dried samples was also investigated. Nanoparticles (NP) of poly-sigma-caprolactone (P sigma CL), a biodegradable polymer, were obtained by a modified nanoprecipitation method. A central composite experimental design was used to investigate the simultaneous effect of technological factors (temperature of the aqueous phase and needle gauge) and formulation variables (volume of acetone and the amount of polymer and surfactant). The effect of these variables on the stability of the 100-220 nm particles obtained was evaluated. The percentage of cyclosporin A (CyA) encapsulated in the NP suspensions stored at 8 and 25 degrees C for at least 3 months remained unaltered. Moreover, there was no change in the size of NP. After 4 months storage, the physical stability of the preparation was affected. NP aggregates could be observed by light microscopy. Reconstituted freeze-dried preparations showed a mean increase of 1% in the incorporated drug and also a considerable increase in mean size and size distribution. Additional experiments investigated the effect of freezing temperature (-70 and -196 degrees C) and of 5, 10 and 20% (w/v) cryoprotector (mannitol, sorbitol, glucose and threalose) on 100 nm particles. The addition of glucose and threalose at concentrations > 10% permitted adequate reconstitution of the freeze-dried product with conservation of the encapsulated CyA.

Delta9-tetrahydrocannabinol stimulates glucose utilization in C6 glioma cells

The present work was undertaken to study the metabolic response of C6 glioma cells to physiologically relevant doses of delta9-tetrahydrocannabinol (THC), the major active component of marijuana. At those concentrations (i.e. nanomolar range), THC produced a dose-dependent increase in the rates of glucose oxidation to CO2 and glucose incorporation into phospholipids and glycogen. The THC-induced stimulation of glucose utilization was (i) dose-dependent up to 100 nM THC, (ii) mimicked by the synthetic cannabinoid HU-210, and (iii) prevented by pertussis toxin and the CB1 receptor antagonist SR141716A. In contrast to THC, forskolin markedly depressed CO2 production, phospholipid synthesis and glycogen synthesis from glucose. The forskolin-induced inhibition of glucose utilization was (i) mimicked by dibutyryl-cAMP, and (ii) prevented by THC, HU-210 and H-7, an inhibitor of the cAMP-dependent protein kinase. Likewise, THC was able to antagonize in part the forskolin-induced elevation of intracellular cAMP concentration, and this antagonistic effect was prevented by SR141716A. However, THC per se did not affect basal cAMP concentration. Results thus indicate that physiologically relevant doses of THC stimulate glucose metabolism in C6 glioma cells through a cannabinoid receptor-mediated process. Although cannabinoid receptors may be coupled to inhibition of adenylyl cyclase in C6 glioma cells, this does not seem to be the mechanism involved in the THC-induced stimulation of glucose metabolism.

[Tonal dichotic listening: discriminatory value between left and right handedness and between sexes]

INTRODUCTION

The dichotic hearing test consists of simultaneous stimulation of right and left ears with different messages, allowing analysis of the better or worse selective integration of these messages.

MATERIAL AND METHODS

With the latest techniques, the tonal dichotic test is applied by listening to a sample of 90 persons, ages from between 20 and 50 years without antecedents of otologic, neurologic nor psiquiatric disorders, valuing their discriminative and dominant capacity for lateral hearing.

RESULTS

The test is chosen effectively arranging the persons by their stereophonic capacity, like something adding but is as not as their simple biaural hearing capacity is, it is found an average capacity of hearing of the 79.856% in the left ear while there is only in 74.856% of in the right ear, which represents a dominance or increased value for the left ear.

CONCLUSIONS

Separating within the general sample the right-handed (60 persons) from the left-handed (30 persons), there is not found any meaningful differences neither concerning capacity of discrimination nor of dominance. Separating them by sexes (58 women and 32 men) no meaningful differences are found either in discriminative capacity or in dominance.

Studies on the intracellular localization of acetyl-CoA carboxylase

The present work was performed to identify the subcellular localization of hepatic acetyl-CoA carboxylase (ACC). Cellular organelles involved in fatty acid oxidation that contain a malonyl-CoA sensitive carnitine palmitoyltransferase (CPT) activity or that are linked to the control of this activity were analysed for the presence of ACC. No significant amount of ACC was observed in the mitochondrial fraction prepared from isolated rat hepatocytes. Furthermore, no association of ACC activity and mass with isolated hepatic peroxisomes could be detected. Incubation of isolated hepatocytes with compounds known to affect the integrity of the cytoskeleton like okadaic acid or taxol indicates that ACC is associated with this subcellular structure of the hepatocyte. Such association may allow for efficient regulation of CPT activity and thus of fatty acid oxidation.

Control of hepatic fatty acid oxidation by 5'-AMP-activated protein kinase involves a malonyl-CoA-dependent and a malonyl-CoA-independent mechanism

Incubation of rat hepatocytes with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), an activator of the 5'-AMP-activated protein kinase (AMPK), produced a twofold stimulation of palmitate oxidation and of the activity of carnitine palmitoyltransferase I (CPT-I), together with a profound decrease of the activity of acetyl-CoA carboxylase and of the intracellular level of malonyl-CoA. AICAR-induced CPT-I stimulation progressively blunted with time after cell permeabilization, pointing to reversal of conformational constraints of the enzyme in control cells due to the permeabilization-triggered dilution of intracellular malonyl-CoA. The stimulation stabilized at a steady 20-25%. This 20-25% increase in CPT-I activity survived upon complete removal of malonyl-CoA from the permeabilized cells, indicating that it was not dependent on the malonyl-CoA concentration of the cell. This malonyl-CoA-independent activation of CPT-I was not evident when mitochondria were isolated for assay of enzyme activity or when cells were disrupted by vigorous sonication. In addition, the microtubule stabilizer taxol prevented the malonyl-CoA-independent stimulation of CPT-I induced by AICAR. Hence, stimulation of hepatic fatty acid oxidation by AMPK seems to rely on the activation of CPT-I by two different mechanisms: deinhibition of CPT-I induced by depletion of intracellular malonyl-CoA levels and malonyl-CoA-independent stimulation of CPT-I, which might involve modulation of interactions between CPT-I and cytoskeletal components.