[Recurrence and spontaneous remission of nephrotic syndrome in secondary renal amyloidosis]

Secondary systemic amyloidosis (AA) occurs in association with chronic inflammatory disorders and chronic infections. Regression can occur after therapeutically induced remission of the underlying disease; spontaneous remissions has been reported infrequently. We report a 61 year-old woman, with antecedent pulmonary tuberculosis, who developed a nephrotic syndrome at the time of a respiratory infection. Renal biopsy showed secondary amyloidosis. Remission in the nephrotic syndrome appeared spontaneous, but it recurred in the course of pneumonia, and had a second spontaneous remission a maintained at present.

[Parotid tuberculosis following intravesical BCG instillation: a case report]

First case of parotid gland tuberculosis publicated to date is presented after intravesical instillation of BCG for a superficial bladder cancer. The diagnosis of the parotid gland tuberculosis is difficult because it is usually indistinguishable from a neoplasm. Combined fine-needle aspiration cytology with PCR or LCR amplification of mycobacterial DNA could be a good diagnostic tool avoiding an open biopsy.

Is thiopurine methyltransferase genetic polymorphism a major factor for withdrawal of azathioprine in rheumatoid arthritis patients?

OBJECTIVE

To determine whether the presence of thiopurine methyltransferase (TPMT) alleles associated with reduced or absent activity of thiopurine methyltransferase is a major factor for withdrawal of azathioprine (AZA) in rheumatoid arthritis (RA) patients.

METHODS

The TPMT genotype, including the variable number of tandem repeats (VNTR) pattern in the 5' untranslated region, was analysed in 111 patients with long-standing RA. Azathioprine (AZA) therapy was used in 40 patients (36%) as a disease-modifying anti-rheumatic drug.

RESULTS

Seven out of 111 RA patients (6.3%) were carriers of a mutant allele, TPMT3A (G(460)-->A, A(719)-->G) being the mutant allele observed most frequently. In the group of 40 AZA-treated patients, therapy was discontinued in six patients because of side-effects and in 26 patients because of lack of efficacy. Three patients presented moderate side-effects and were homozygous for the wild-type TPMT allele, whereas the remaining three patients, who developed gastrointestinal effects with severe nausea and vomiting, were TPMT3A carriers.

CONCLUSION

In this observational study, the absence of response, probably due to the low-dose scheme used, was the major cause of AZA withdrawal in our series of RA patients. TPMT genotyping may allow the use of high doses of AZA in patients with normal TPMT alleles to improve the efficacy of this immunosuppressive drug. Our data support the relationship between gastrointestinal intolerance and thiopurine metabolic imbalance.

[Surgical management of anterior communicating artery aneurysms based on computed tomographic angiography with three-dimensional reconstruction and without preoperative angiography]

OBJECTIVE

To demonstrate the usefulness of threedimensional computed tomographic angiography (CT- 3D-angiography) in the microsurgical management of aneurysms of the anterior communicating artery (AComA).

MATERIALS AND METHODS

A total of 28 consecutive patients with ruptured aneurysms of the AComA diagnosed by means of CT-3D-angiography and without preoperative angiography were operated on. The findings of the CT-3D-angiography, microsurgical exploration and clínical data were evaluated.

RESULTS

There were no false positive findings nor false negative findings in the diagnosis of the AComA aneurysms. The global sensibility of the examination was 87.9%. The CT-3D-angiography study shows a left A1 segment dominance in 53.6% of cases, a right A1 dominance in 14.3% of cases and both A1 segments of the same diameter in 32.1%. Aneurysms growing on the traject of the AComA were associated with both A1 segments of the similar diameter and an AComA traject pararell to the transverse plane. Aneurysms implanted on the A1-A2 junction were associated with a dominant homolateral A1 segment and an oblique AComA traject. Microsurgical management of the lesions was done a mean of 3.7 days after bleeding.

CONCLUSION

The study of patients with acute subarachnoid hemorrhage with CT-3D-angiography allows a reliable diagnosis of AComA aneurysms. The examination gives some anatomical data that allow the study of the hemodinamic changes involved in the development of the aneurysms. Moreover, provides usefull information for the microsurgical clipping. CT-3D-angiography allows to improve some health indicators but its impact in the final result of the patients needs more clinical data.

[Segmentary organisation of the efferents of the vestibular complex in chicken embryos: is this an example of the general case?]

INTRODUCTION

In this paper we present, from the perspective of the embryological segmentary layout of the hindbrain, the topographic layout of the vestibular projection neurons that sustain the vestibulospinal, vestibulo ocular and vestibulocerebellous efferents, in correlation with the classic vestibular nuclei.

AIMS

Four vestibular nuclei are usually described superior, lateral, medial and inferior. These originate in at least nine successive rhombomeric segments or pseudosegments, which suggests the possibility of a more precise analysis of their neuronal populations and of their respective connections and functions. It has recently been observed that the vestibular projection neurons identified for a particular target tend to appear aggregated in discrete accumulations, which have been proved to correlate either with rhombomeric units, where they apparently develop, or with internal subdivisions within them. Each projection has its own particular organisation. Comparing them with the resulting connective mosaic in different species shows that various aspects of this organisation are conserved throughout evolution in vertebrates. It is argued that certain genes that control the development of the rhombomeric units in the brain stem may determine, among other aspects, the specific properties of the different neuronal subpopulations related with their axonal navigation and synaptogenesis.

CONCLUSIONS

This type of analysis furthers our understanding of how the functional circuitry of a complex system, such as the vestibular system, is generated and is a line of reasoning that in principle can be applied to the whole neural tube.

Allelic polymorphism -491A/T in apo E gene modulates the lipid-lowering response in combined hyperlipidemia treatment

BACKGROUND

Combined hyperlipidemia (CHL) is one of the dyslipidemias more frequently found in clinical practice, and lipid-lowering drugs are often necessary in its management. Some genetic loci have been associated with CHL expression, and some studies have shown modulation of drugs efficiency in the treatment of dyslipidemias by genetic polymorphisms. We have investigated whether common polymorphisms and mutations in the apolipoprotein (apo) E, lipoprotein lipase (LPL), and apo CIII genes influence atorvastatin or bezafibrate responses in patients with CHL.

DESIGN

One hundred and sixteen subjects participating in the ATOMIX study (Atorvastatin in Mixed dyslipidemia) were randomized to treatment with either atorvastatin or bezafibrate. Apolipoprotein E genotype and common -491A/T and -219T/G polymorphisms in the apo E gene promoter region, Sst I polymorphism in the apo CIII gene (3238C/G), and D9N and N291S common mutations in the LPL gene were determined by polymerase chain reaction (PCR) and restriction enzyme digestion.

RESULTS

Statistical analysis showed the influence of the -491A/T polymorphism in atorvastatin and bezafibrate treatments. Subjects carrying the -491T allele showed an increased LDL-cholesterol-lowering effect with atorvastatin compared with -491T allele noncarriers (-35% vs. -27%, P = 0.037). Subjects carrying the -491T allele, when on bezafibrate treatment, showed a lower triglyceride reduction compared with -491T allele noncarriers (-23% vs. -39%, P = 0.05).

CONCLUSIONS

In our study, the -491A/T polymorphism in the apo E gene promoter region modulated the lipid-lowering efficiency of atorvastatin and bezafibrate in CHL patients. Such influence might explain some of the interindividual response variabilities observed for the two drugs, and could help in CHL management.

[Effects of simultaneous transplant of foetal mesencephalic cells in the striatum and the subthalamic nucleus of hemiparkinsonian rats]

INTRODUCTION

The main strategy followed in neural transplants as a method of treatment for Parkinson s disease, both experimental and clinical, has been to introduce foetal mesencephalic cells into the target area: the striatum. However, when the dopaminergic cells in the substantia nigra degenerate, not only is the dopaminergic innervation of the striatum affected but also other nuclei: globus pallidus, substantia nigra, substantia nigra pars reticulata and subthalamic nucleus. A series of data from pharmacological and physiological studies offer strong evidence that the dopamine released in these nuclei may play an important role in regulating the output nuclei of the basal ganglia.

AIM

To evaluate the effect of transplanting foetal mesencephalic cells on the behaviour of 6 OH DA rats when introduced into the striatum and the subthalamic nucleus.

MATERIALS AND METHODS

6 OH DA was used to induce lesions in the substantia nigra of rats, which were divided into several experimental groups. The rotating activity induced by D amphetamine (5 mg/kg, intraperitoneally) and apomorphine (0.05 mg/kg, subcutaneously) was evaluated before and three months after the transplant in all the experimental groups, except in the control group of healthy rats. The hemiparkinsonian rats received a total of 350,000 foetal ventral mesencephalic cells, which were implanted within small deposits in the striatum (8) and in the subthalamic nucleus (4).

RESULTS AND CONCLUSIONS

Rotation induced by both drugs was significantly lower (p= 0.05) in animals that had had dopaminergic cells transplanted into the striatum body. No significant improvement in this behaviour was to be found when transplants were limited to just the subthalamus or, simultaneously, also to the striatum. A significant increase in rotating behaviour induced by apomorphine was observed in the group which received a transplant in just the subthalamus.

[The value of waiting in spontaneous remission of recurrent tonsillitis without associated adenoid pathology]

In order to assess the rate of spontaneous remission in children with recurrent acute tonsillitis (RAT), we revised the pediatric patients who were seen between 1994 and 1999. For this purpose, 123 cases that were on the waiting list for tonsillectomy under the indication of RAT without associated adenoid disease were selected. Only 23 (18.7%) of the children who were included in the study were removed from the waiting list after a mean time of 9 months because of spontaneous remission of the disease. Thus, there is no justification for claiming that long waiting lists for tonsillectomy are frequently associated with spontaneous remission of RAT.

Group B Streptococcal sacroiliitis: case report and review

Streptococcus agalactiae, or group B Streptococcus (GBS), is the major cause of neonatal meningitis and sepsis but is an uncommon infection in adults. GBS arthritis is rare, and axial involvement with sacroiliitis is even more uncommon. Microbiological diagnosis frequently relies upon positive blood cultures as synovial fluid cultures are usually negative. Severe joint damage may result due to delay in the initiation of antibiotic treatment.

Effect of bicarbonate/lactate peritoneal dialysis solutions on human mesothelial cell proliferation ex vivo

Peritoneal membrane suffers structural and functional changes over time on peritoneal dialysis (PD)--in part, owing to the dialysis solutions currently used. Low pH seems to be an important element associated with solution bioincompatibility. Bicarbonate-containing fluids open new perspectives on this issue. The present study compared the effects of bicarbonate/lactate (Bic/Lac) solution (25 mmol/L bicarbonate, 15 mmol/L lactate) and lactate (Lac) solution (40 mmol/L lactate) on mesothelial cell (MC) growth in culture. Eight stable PD patients were asked to collect peritoneal effluent from an 8-hour dwell on two separate days, within an interval shorter than one week. For the first dwell, Lac solution was infused; for the second dwell, Bic/Lac solution was instilled. Human MCs were isolated from the effluent, seeded in 25-cm2 tissue culture flasks, and grown ex vivo. Morphology of the cells was also evaluated. In all effluents, MCs were present in mean amounts of 26,939 +/- 21,267 cells (Bic/Lac) and 25,986 +/- 15,286 cells [Lac, p = nonsignificant (NS)]. Morphology of the MCs was similar with both solutions (87.5% typical). After initial culture, MCs from 6 patients using Bic/Lac (75%) and 3 patients using Lac (37.5%) reached confluence. At this time, the number of MCs from the 3 patients who showed MC growth with both solutions was slightly higher with Bic/Lac-buffered fluid (Lac: 1,154,125 +/- 213,333 cells; Bic/Lac: 1,198,291 +/- 806,713 cells). To summarize: 3 patients showed MC growth under both solutions; 3 patients showed MC growth only under Bic/Lac solution; and 2 patients showed no MC growth at all. After cells were seeded in 24-well plates, the MC growth curve was performed in 4 cases of Bic/Lac solution use and in 3 cases of Lac solution use. Although no significant differences were observed between the solutions, the final number of MCs obtained was higher with Bic/Lac solution use. In conclusion, MCs released into peritoneal effluent under bicarbonate/lactate-buffered peritoneal dialysis solution are associated with a greater ex vivo proliferation capacity than those released under lactate solution in the same patient. This finding may demonstrate better biocompatibility for Bic/Lac solution.

Pancreatic panniculitis in a kidney transplant recipient

BACKGROUND

Pancreatic panniculitis is a rare complication of pancreatic disease. Histopathologic findings are pathognomonic and may be helpful for early diagnosis.

METHODS

We present a female kidney transplant recipient, with systemic lupus erythematosus on immunossuppresive therapy, who developed panniculitis.

RESULTS

Histological features strongly suggested pancreatic panniculitis and this was confirmed by clinical, laboratory and image findings.

CONCLUSION

The characteristic histologic features of pancreatic panniculitis may help to uncover undiagnosed pancreatic disease. Early therapy may avoid ensuing serious complications.

Validation of the preparation of individual doses of (131)I-sodium o-iodohippurate ((131)I-hippuran)

The preparation of low activity doses of (131)I-hippuran has a drawback due to its high radioactivity concentration. In this study we diluted the radiopharmaceutical with saline or phosphate buffered saline (PBS) in order to decrease the radioactivity concentration, facilitate the preparation of individual doses and validate these procedures. We prepared doses of approx. 1.85 MBq of (131)I-hippuran from 10 different batches the day before the calibration date: undiluted, and diluted 1:9 with saline or PBS. The radiochemical purity (RCP) was evaluated the day after the expiration date. The percentage of (131)I-hippuran retained on syringes was assessed in vitro, after emptying the syringe and washing it twice with water (n=3 x 27); and in vivo, after the endovenous administration of the dose and washing the syringe twice with the patient's blood (n=3 x 75). Sterility was assessed using fluid thyoglicolate medium (n=3 x 15). All RCP values were greater than those required by the European Pharmacopoeia (>96%) except one of the undiluted (131)I-hippuran (95.8%) doses. No statistical difference was observed among them. The mean undiluted (131)I-hippuran retained in vitro was 5.4% (SD=6.5%), statistically greater (P<0.01) than both saline diluted (mean=1.5%, SD=1.1%) and PBS diluted (mean=2.0%, SD=2.4%). The mean undiluted (131)I-hippuran retained in vivo was 6.4% (SD=5.4%), statistically greater (P<10-5) than both saline diluted (mean=3.1%, SD=2.3%) and PBS diluted (mean=3.1%, SD=3.1%). We concluded that: (1) the dilution of (131)I-hippuran with saline or PBS makes both the preparation of individual doses and its administration to the patient easier without decreasing its radiopharmaceutical quality; and (2) using saline or PBS diluted (131)I-hippuran the percentage of radiopharmaceutical retained on the syringes, after use, is minimized.

Characterization of binary solvent mixtures of DMSO with water and other cosolvents

Binary mixtures of DMSO with nine different cosolvents were characterized in light of the pure solvent scales, using suitable probe/homomorph couples. Various physical (vapor pressure, surface tension, viscosity, and enthalpy of mixing) and spectroscopic (IR and NMR) properties of the DMSO/water mixtures are described in terms of their polarity, acidity, and basicity, and the descriptions are examined with a view to establishing their potential physical significance.

Modulation of the susceptibility of human erythrocytes to snake venom myotoxic phospholipases A(2): role of negatively charged phospholipids as potential membrane binding sites

Cerrophidion (Bothrops) godmani myotoxins I (CGMT-I) and II (CGMT-II), Asp-49 and Lys-49 phospholipases A(2) (PLA2s), which drastically differ in enzymatic activity, were devoid of direct hemolytic effects on erythrocytes (RBC) from different species despite the fact that enzymatically active CGMT-I was able to hydrolyze RBC membrane phospholipids and disrupt liposomes prepared from RBC lipids. Human RBC did not become susceptible to the toxins after treatment with neuraminidase or after altering membrane fluidity with cholesterol or sublytic concentrations of detergent. Unlike normal RBC, significant hemolysis was induced by CGMT-II and another similar Lys-49 isoform, B. asper MT-II (BAMT-II), in RBC enriched with phosphatidylserine (PS). Hemolysis was greater in RBC preincubated with pyridyldithioethylamine (PDA), a potent inhibitor of aminophospholipid transport. RBC enriched with phosphatidic acid (PA) also became susceptible to the myotoxins but was unaffected by PDA. Cells enriched with phosphatidylcholine (PC) remained resistant to the action of the toxins. BAMT-II also induced damage in black lipid membranes prepared with PS but not PC alone. When RBC binding of BAMT-II was measured by enzyme-linked immunosorbent assay, it was observed that PS- and PA-enriched erythrocytes were always able to capture more toxin than normal and PC-enriched RBC. This effect was significantly improved by PDA (in the case of PS) and it was observed either in the presence or in the absence of calcium in the medium. These data suggest that negatively charged lipids in the outer leaflet of cell membranes constitute myotoxic PLA2 binding sites. The scarcity of anionic phospholipids in the outer leaflet of RBC could explain their resistance to the action of these PLA2s.

[Idiopathic membranous nephropathy in an elderly patient with type 2 diabetes mellitus]

We report an 85 years-old patient with type 2 diabetes mellitus and both clinical and biochemical nephrotic syndrome. The renal biopsy showed membranous nephropathy at stage I-II. There was no evidence of malignancy. The patient was treated with steroids, and two months later the proteinuria had not improved. The objects under discussion are the factors that should lead to suspect the existence of glomerulonephritis, other than diabetic glomerulosclerosis, suggesting the need for kidney biopsy. We also focus on the prognostic and therapeutic relevance, as well as on the common pathogenic aspects.

Atorvastatin prevents glomerulosclerosis and renal endothelial dysfunction in hypercholesterolaemic rabbits

BACKGROUND

Numerous studies have shown that elevated plasma cholesterol can exacerbate renal disease. However, the effect of lipids on renal structure and vascular function in normal kidneys is less well established. Therefore, the aim of this study was to evaluate the impact of hypercholesterolaemia on glomerular structure and vascular reactivity of segmental arteries in rabbits. In addition, we also studied whether or not atorvastatin can prevent these structural and vascular alterations in hypercholesterolaemic rabbits.

METHODS

Male New Zealand rabbits were fed either a normal rabbit chow or a diet containing 1% cholesterol and treated or not with atorvastatin (1 mg/kg/day) for 12 weeks. Dose-response curves to acetylcholine (10(-9)-10(-4) mol/l) and sodium nitroprusside (10(-9)-10(-4) mol/l) were studied in segmental arteries in the presence or absence of the thromboxane A2/PGH2 receptor antagonist ifetroban (10(-5) mol/l). Glomerular size and structure were also evaluated.

RESULTS

Compared with control animals, hypercholesterolaemic rabbits presented glomerular hypertrophy and several types of injuries (capillary collapse, hyalinosis and alterations of Bowman's capsule), suggesting diffuse glomerulosclerosis. Segmental arteries also showed relaxing responses to acetylcholine and sodium nitroprusside which were lower than and similar to, respectively, those of control animals. The presence of ifetroban improved the acetylcholine response only in hypercholesterolaemic rabbits. Atorvastatin treatment prevented vascular and most glomerular changes associated with hypercholesterolaemia even in the presence of very high cholesterol levels.

CONCLUSIONS

Atorvastatin exerts a protective effect on renal damage associated with hypercholesterolaemia even in the presence of deleterious levels of plasma cholesterol.

Serum manganese concentrations in a representative sample of the Canarian population

Serum manganese (Mn) concentrations of 368 individuals 6-75 yr of age (179 males and 189 females) living in the Canary Islands were determined by graphite furnace atomic absorption spectrometry. The mean manganese concentration was 1.06+/-0.62 microg/L, ranging between 0.19 and 3.33 microg/L. Most of the analyzed samples (63.3% of the samples) fall within the reference interval (0.54-1.76 microg/L) for apparently healthy people. Individuals from Fuerteventura presented with mean Mn concentrations significantly higher than individuals from the rest of the islands. This could be attributed to differences in the Mn content of soil and/or differences in dietary habits of the population. Serum Mn concentration did not vary with gender, and individuals younger than 18 yr old had the highest mean Mn concentration, compared to the rest of the age groups considered. No relation to socioeconomic status, educational level, and tobacco or alcohol consumption was found. However, the serum Mn concentration tended to decrease when increasing the consumption of wine or beer. Sportsmen presented significantly higher serum Mn concentrations than the rest.

Chitotriosidase genotype and serum activity in subjects with combined hyperlipidemia: effect of the lipid-lowering agents, atorvastatin and bezafibrate

Chitotriosidase, an enzyme involved in the degradation of chitin-containing pathogens with unclear function in humans, has been proposed as a marker of lipid accumulation in macrophages in different lipid-storage diseases, including atherosclerosis. To evaluate (1) if lipid-lowering treatment could modify serum chitotriosidase activity and (2) be useful in monitoring lipid-lowering treatment, we have analyzed this enzyme activity in the participants in the Atozvastatin Versus Bezafibrate in Mixed Hyperlipidemia (ATOMIX) study, a double-blind, comparative, and randomized study comparing the efficacy of atorvastatin and bezafibrate in mixed hyperlipidemia. Because a common genetic deficiency of chitotriosidase modifies serum quitotriosidase activity, this genetic variation was also studied. Seven subjects of 116 (6.03%) were homozygous, and 46 (39.6%) were heterozygous for the defective allele. Mean serum quitotriosidase activity correlated with allele dosage, as it was found to be of 0, 59.8 +/- 52.6 and 81.2 +/- 41.6 nmol/mL/h, in homozygotes for the defective allele, heterozygotes, and homozygotes for the wild-type allele, respectively (P =.0011 for the difference between the last 2 groups). However, this enzyme activity was not found to correlate with lipid levels before and after treatment with either atorvastatin or bezafibrate, and neither with the intensity of the lipid lowering. These results do not support the use of serum chitotriosidase activity as a biologic marker of atherosclerotic plaque modification related to hypolipidemic treatment.

Pneumonia in patients with severe burns : a classification according to the concept of the carrier state

OBJECTIVE

To establish baseline values of pneumonia incidence and mortality and to distinguish primary endogenous from secondary endogenous and exogenous pneumonias in a homogeneous patient population with severe burns.

DESIGN

Cohort study.

SETTING

A six-bed burn ICU.

PATIENTS

All patients of > or = 14 years admitted to the ICU between January 1995 and June 1996 with a total body surface area burn of > or = 20%.

INTERVENTION

Collection of data on surveillance samples from throat and rectum on admission and twice weekly afterward, and pneumonias during the ICU stay.

MEASUREMENTS AND RESULTS

Fifty-six patients fulfilled the criteria of the study. Mean age was 43 +/- 19.8 years; total body surface area burn, 41 +/- 18.2%; the area of full-thickness burn was 24 +/- 17.7%. Forty-one patients required mechanical ventilation. Twenty-seven patients (48%) experienced 37 episodes of pneumonia. Twenty-one pneumonias were of primary endogenous development, ie, caused by potential pathogens carried in the admission flora. There were 14 secondary endogenous and 2 exogenous infections caused by microorganisms acquired on the burn unit. Inhalation injury was identified in 26 patients. The pneumonia rate was two times higher in the subset of patients with inhalation injury compared with the group of patients without inhalation injury (p < 0.001). Overall mortality was 25%.

CONCLUSIONS

This study shows that pneumonia in burn patients is mainly an endogenous problem. Interventions that prevent the development of endogenous infections deserve prospective evaluation in patients with severe burns.

[Adaptation of microtitration plate methods for quantification of the activity of esterases and glutathione-s-transferase in Aedes aegypti]

The detection techniques for the activity of non-specific esterases and glutathione-s-transferase in Culex quinquefasciatus were modified to detect such enzymes in Aedes aegypti(L). The optimal concentration values of substrate (saturating concentration) and the optimum reading time for reaction were determined for each enzyme by using 4 Aedes aegypti strains: one from Cuba 2 from Venezuela and one susceptible reference strain. The frequency of non-specific esterases turned out to be 0.76 in MIRANDA 0.42 in ARAGUA and 1 in SANTIAGO DE CUBA in which the highest frequency value of this mechanisms was reached. The frequency of glutathione-s-transferase mechanism was 0.45 in ARAGUA 0.043 in MIRANDA and 1 in SANTIAGO DE CUBA. For the first time in Cuba a set of biochemical techniques was available for detecting the resistance mechanisms of Aedes aegypti which made it possible to create sound foundations for the easy rapid detection of the resistance of this species the main dengue vector in the Americas.

[High esterases as mechanism of resistance to organophosphate insecticides in Aedes aegypti strains]

Five strains of Aedes aegypti L. one from Cuba and 4 from Venezuela were evaluated to determine their resistance to organophosphate insecticides (temephos, chlorpiriphos and pirimiphos methyl). In the Venezuelan strains only APURE showed resistance to temephos. In TACHIRA and MIRANDA moderate resistance values were noted (FR50 5 to 10x) for chlorpiriphos and high levels of resistance (FR > 10x) to this insecticide were found in ARAGUA. All the Venezuelan strains showed high levels of resistance to pirimiphos methyl. The Cuban strain from Santiago de Cuba revealed moderate resistance to temephos and pirimiphos methyl, but high resistance to chlorpiriphos. The results of the biochemical tests proved the presence of esterase and glutathione-s-transferase at high frequency in almost every strain. By the polyacrilamide gel electrophoresis, a strongly stained band was observed in all the strains with a Rf value of 0.779; it was named esterase A4 and was not seen in the susceptible reference strain. The meaning of this esterase in the resistance to organophosphate insecticides is yet to be determined. Resistance to these insecticides in Aedes aegypti is a serious problem for the control of this species therefore integrated management strategies were proposed to prevent or delay the appearance of this species in Cuba and Venezuela.

Short- and long-term effects of atorvastatin, lovastatin and simvastatin on the cellular metabolism of cholesteryl esters and VLDL secretion in rat hepatocytes

The short- and long-term in vitro effects of the hydroxymethylglutaryl-CoA reductase inhibitor atorvastatin, compared with lovastatin and simvastatin on VLDL secretion, and on the formation and the neutral and acid lysosomal hydrolysis of cholesteryl esters was investigated in rat liver hepatocytes maintained in suspension (2 or 4 h) or cultured in monolayers (24 h). All statins time-dependently reduced [14C]oleate incorporation into cholesteryl esters, but when exogenous cholesterol was added only atorvastatin caused an immediate transient decrease in hepatocyte ACAT activity. Activity of the lysosomal, microsomal and cytosolic CEH isoforms was unaffected by the hepatocyte treatments. Statins reduced free and esterified cholesterol mass in hepatocyte microsomes after 2 h, and this was followed by a modest decline in VLDL cholesteryl esters, whilst secretion of VLDL apoB and triglycerides was unaltered. However, after 24 h of treatment, statins caused generalized 20-40% decreases in the secretion of VLDL apoB, cholesterol and triglycerides, with the reduction in apoB48 secretion being significantly superior to that caused in apoB100. The mean diameter of secreted VLDL was not modified by either duration or drug treatment. Additional studies with subcellular fractions demonstrated that statins have a direct selective effect on the enzymes governing the cholesterol-cholesteryl ester cycle, with the exception of the microsomal CEH. Atorvastatin, lovastatin and simvastatin inhibited ACAT activity in microsomes by 50% at doses of 250, 100 and 50 microM, respectively. The cytosolic CEH elicited a biphasic profile of activity with activations up to 100 microM statin and inhibitions above 250 microM, and the lysosomal CEH was only inhibited by atorvastatin at a dose of 100 microM or more. We conclude that a prolonged, but not a short, limited availability of hepatocyte cholesterol derived from the endogenous synthesis reduces VLDL secretion, and that reactivity of statins at the cellular level are more similar than reactivity at the subcellular level as regards the cholesterol-cholesteryl ester cycle.