Acyl-coenzyme A: cholesterol acyltransferase modulates the generation of the amyloid beta-peptide.

The pathogenic event common to all forms of Alzheimer's disease is the abnormal accumulation of the amyloid beta-peptide (Abeta). Here we provide strong evidence that intracellular cholesterol compartmentation modulates the generation of Abeta. Using genetic, biochemical and metabolic approaches, we found that cholesteryl-ester levels are directly correlated with Abeta production. Acyl-coenzyme A:cholesterol acyltransferase (ACAT), the enzyme that catalyses the formation of cholesteryl esters, modulates the generation of Abeta through the tight control of the equilibrium between free cholesterol and cholesteryl esters. We also show that pharmacological inhibitors of ACAT, developed for the treatment of atherosclerosis, are potent modulators of Abeta generation, indicating their potential for use in the treatment of Alzheimer's disease.

Woody plants: changes in survival in response to long-term (8 years) chronic gamma irradiation.

The number of plant deaths which occurred over 8 years of chronic gamma irradiation (20 hours/day) of 11 species of woody plants indicated a decline in the rate of death with increasing exposure time. This suggests that a highly effective repair system may develop, at least in the range of exposure which reduces survival by 50 percent. The inverse relationship previously found between interphase chromosome volume and radiosensitivity for single 16-hour exposures was confirmed for chronic exposures by construction of appropriate regressions. Radiosensitivity of a species can be predicted from these regressions if the interphase chromosome volume is known. The distributions of interphase chromosome volumes and predicted sensitivities are given for 215 species of woody plants.

Cholesterol crystallization-promoting activity of aminopeptidase-N isolated from the vesicular carrier of biliary lipids.

Different hydrophobic glycoproteins are associated to native biliary vesicles, which are the major carrier of biliary cholesterol. Some of these proteins promote cholesterol crystallization, a key step in cholesterol gallstone formation. This study was specifically conducted to identify the 130 kDa biliary vesicle-associated glycoprotein and to determine its in vitro effect on the cholesterol crystal formation time. The 130 kDa vesicular glycoprotein was identified as aminopeptidase-N by amino acid sequencing and specific enzymatic assay. Polyclonal antibodies raised against aminopeptidase-N allowed us to determine its concentration in human hepatic bile, which varied from 17.3 to 57.6 micrograms/ml. Aminopeptidase-N showed a concentration-dependent cholesterol crystallization activity when it was added to supersaturated model bile at a concentration range usually found in native bile. Because of this promoting effect on in vitro cholesterol crystal formation, we suggest that biliary aminopeptidase-N may play a critical role in the pathogenesis of cholesterol gallstone disease.

Uptake of dodecanedioic acid by isolated rat liver.

The uptake of dodecanedioic acid (C12); a dicarboxylic acid with 12 carbon atoms, was studied in the isolated perfused rat liver. Fifty mumol of C12 were injected as a bolus into the perfusing liver solution. The concentration of C12 in perfusate samples taken over 2 h from the beginning of the experiments were analyzed by high performance liquid chromatography. An in vitro experimental session was performed to determine the binding curve of C12 to defatted bovine serum albumin. These data were then used to compute the perfusate C12 free fraction. The number of binding sites on the albumin molecule was equal to 4.29 +/- 0.21 (S.E.), while the affinity constant was 6.33 +/- 0.87 x 10(3). M-1. Experimental values of perfusate C12 concentration versus time were individually plotted and fitted to a monoexponential decay for each liver perfused. The predicted C12 concentration at time zero averaged 0.354 +/- 0.0375 mumol/ml. Prom this value the apparent volume of distribution of C12 was obtained and corresponded to 153.02 +/- 14.56 ml. The disappearance rate constant from the perfusate was 0.0278 +/- 0.0030 min-1. The C12 half life was 26.6 +/- 2.3 min. The mean hepatic clearance from the perfusate was 4.08 +/- 0.38 ml/min. In conclusion, C12 is quickly taken up by the liver so that in about 100 min it was completely cleared from the perfusate.

[Diagnosis of thyroid nodules]. / Sulla diagnostica del nodulo tiroideo.

The basic features of the most common endocrine pathology, the thyroid nodule are analysed. After a brief assessment of the incidence of the condition the problem of clinical and instrumental diagnosis is tackled with the aim of demonstrating the value and possibility of sub-clinical diagnosis of micronodules. The present work aims to identify the fastest, most efficient and cheapest diagnostic procedure.

[Autonomous adenoma of the thyroid]. / L'adenoma autonomo della tiroide.

Toxic goitre often referred to in the literature as "autonomous" adenoma or nodule actually signifies a number of different pathologies that are characterised by autonomy and hyperfunction so that it is now thought more appropriate to call it an autonomous follicle. Clinical features and the hormone profile suggest the diagnosis which is confirmed by scintiscan with curve as well as dynamic inhibition and stimulation tests using TRH, procedures that reveal both latent hyperfunction and autonomy. The most common current therapeutic approach is surgical since this provides a complete cure while leaving the surrounding thyroid tissue undisturbed.

[Prognostic factors in gastric carcinoma]. / Fattori prognostici del carcinoma gastrico.

A personal experiment conducted on 80 gastric carcinoma patients requiring radical surgery at the Special Surgical Pathology Institute is reported. The aim of the study was to identify and assess the factors capable of influencing prognosis e.g. sex, age, TNM, type of operation, symptoms etc and to make a comparison with data from the international literature.

[Carcinoma of the male breast. Our experience]. / Il carcinoma della mammella maschile. Nostra esperienza.

A case series of 5 male patients afflicted with breast carcinoma is reported. The Authors describe symptomatology, diagnostic iter, principles of surgical treatment and results. Underlined is the wider surgical demolition in male breast cancer in comparison with females, even if natural history and biological conduct are comparable. This is because in male breast carcinoma the local and remote infiltration is more rapid than female for the less development of breast gland. Finally, indications for radiochemotherapy are comparable to female breast cancer.

[Goiter recurrences after surgical resection]. / Le recidive del gozzo dopo resezione chirurgica.

A personal experience about 135 pz. with non-toxic goitre treated by mono o bilateral thyroidectomy and followed during 5 years (2-8) to evaluate the incidence of recurrences is reported. The recurrences were 10.5%, especially after monolateral thyroidectomy (9 pz.). Therefore the authors stress the importance of a more accurate surgical indication, a wider resection of the gland and a careful follow-up to undertake opotherapy when hypofunction appears.

[Mucoid carcinoma of the anus and perianal fistula: a clinical case and review of the literature]. / Carcinoma mucoide dell'ano e fistola perianale: caso clinico e revisione della letteratura.

The Authors describe a case of mucoid anal carcinoma occurring in a perianal fistula. Surgical treatment was an abdomino-perineal resection (Miles' operation). On the basis of their experience and of the results reported in the literature, the Authors discuss the clinical and histological aspects of this association.

Midlife predictors of Alzheimer's disease.

Factors contributing to increased risk for Alzheimer's disease (AD) include age, sex, genes, and family history of AD. Several risk factors for AD are endogenous; however, accumulating evidence implicates modifiable risk factors in the pathogenesis of AD. Although the continued task of identifying new genes will be critical to learning more about the disease, several research findings suggest that potentially alterable environmental factors influence genetic contributions, providing targets for disease prevention and treatment. Here, we review midlife risk factors for AD, and address the potential for therapeutic intervention in midlife.

Alzheimer disease: 100 years later.

Almost 100 years since the first clinical report of a case of Alzheimer disease (AD), three early-onset and two late-onset AD genes have been identified. While rare mutations in the early-onset genes (amyloid precursor protein, and presenilins 1 and 2) lead to increased generation of specific forms of the amyloid beta protein (A,beta), common polymorphisms in the late-onset genes (apolipoprotein E and alpha 2-macroglobulin) are thought to alter the clearance and degradation of A,beta in brain. Although definite proof for a direct link between altered A beta generation/clearance and neurodegeneration has not yet been attained, mechanism-based approaches for the therapeutic treatment of AD based on lowering levels of the potentially pathogenic A beta are currently underway. The recent discovery of the enzymes (secretases) responsible for generating A beta have paved the way for the development of such drugs and increase the prospects for successful therapeutic intervention to arrest AD neuropathogenesis.

Reconstitution, identification, and purification of the rat liver golgi membrane GDP-fucose transporter.

Glycosylation of glycoproteins, proteoglycans, and glycolipids occurring in the Golgi apparatus requires the translocation of nucleotide sugars from the cytosol into the lumen of the Golgi. Translocation is mediated by specific nucleotide sugar transporters, integral Golgi membrane proteins that regulate the above glycosylation reactions. A defect in GDP-fucose transport into the lumen of the Golgi apparatus has been recently identified in a patient affected by leukocyte adhesion deficiency type II syndrome (Lubke, T., Marquardt, T., von Figura, K., and Korner, C. (1999) J. Biol. Chem. 274, 25986-25989). We have now identified and purified the rat liver Golgi membrane GDP-fucose transporter, a protein with an apparent molecular mass of 39 kDa, by a combination of column chromatography, native functional size determination on a glycerol gradient, and photoaffinity labeling with 8-azidoguanosine-5'-[alpha-(32)P] triphosphate, an analog of GDP-fucose. The purified transporter appears to exist as a homodimer within the Golgi membrane. When reconstituted into phosphatidylcholine liposomes, it was active in GDP-fucose transport and was specifically photolabeled with 8-azidoguanosine-5'-[alpha-(32)P]triphosphate. Transport was also stimulated 2-3-fold after preloading proteoliposomes with GMP, the putative antiporter.

Identification, purification, and characterization of the rat liver golgi membrane ATP transporter.

Phosphorylation of secretory and integral membrane proteins and of proteoglycans also occurs in the lumen of the Golgi apparatus. ATP, the phosphate donor in these reactions, must first cross the Golgi membrane before it can serve as substrate. The existence of a specific ATP transporter in the Golgi membrane has been previously demonstrated in vitro using intact Golgi membrane vesicles from rat liver and mammary gland. We have now identified and purified the rat liver Golgi membrane ATP transporter. The transporter was purified to apparent homogeneity by a combination of conventional ion exchange, dye color, and affinity chromatography. An approximately 70,000-fold purification (2% yield) was achieved starting from crude rat liver Golgi membranes. A protein with an apparent molecular mass of 60 kDa was identified as the putative transporter by a combination of column chromatography, photoaffinity labeling with an analog of ATP, and native functional size determination on a glycerol gradient. The purified transporter appears to exist as a homodimer within the Golgi membrane, and when reconstituted into phosphatidylcholine liposomes, was active in ATP but not nucleotide sugar or adenosine 3'-phosphate 5'-phosphosulfate transport. The transport activity was saturable with an apparent Km very similar to that of intact Golgi vesicles.

[Verification of the prognostic significance of a left-ventricular aneurysm after a first myocardial infarct]. / Verifica del significato prognostico dell'aneurisma del ventricolo sinistro dopo un primo infarto miocardico.

The prognostic implication of a left ventricular aneurysm after a first myocardial infarction has been assessed on a series of 64 patients (mean age 65 +/- 10 years; 55 males and 9 females) having a diagnosis of a left ventricular aneurysms made by the equilibrium gated radionuclide angiocardiography. The control group was composed by 80 patients (mean age 63 +/- 10 years; 65 males and 15 females) with first myocardial infarction and comparable clinical characteristics but without left ventricular aneurysm. Aneurysm was defined as a ventricular segment in phase with atria in the phase parametric imaging. A left ventricular ejection fraction less than 52% was diagnosed in 83% and in 49% of the patients with and without aneurysm respectively (p less than 0.0005). The study group also showed a higher use of digoxin (39% vs 21%; p less than 0.05) and a higher prevalence of ventricular arrhythmias (31% vs 12%; p less than 0.05). After 36 months, mortality was 34% and 17% in patients with and without left ventricular aneurysm, respectively (p less than 0.05). According to the logistic regression analysis, mortality was predicted by a left ventricular ejection fraction less than 52% (odd ratio = 1.91; confidence limits = 1.03-3.48) while neither left ventricular aneurysm nor any of the remaining variables (age, sex, site of the myocardial infarction, peak filling rate, congestive heart failure, ventricular arrhythmias and their Lown class) could affect survival. In conclusion, a left ventricular aneurysm has no prognostic implication after a first myocardial infarction provided that the patients are stratified for the left ventricular ejection fraction.

Right ventricular aneurysm: a new prognostic indicator after a first acute myocardial infarction.

The prognostic implication of a right ventricular aneurysm after a first acute myocardial infarction (AMI) was assessed on a series of 137 AMI patients 12 of whom had a right ventricular aneurysm detected at radionuclide angiocardiography. The follow-up lasted 36 months. Mortality was 50 and 18.4% in patients with and without right ventricular aneurysm, respectively (p less than 0.02). Groups did not differ in age, male-to-female ratio, AMI site, left ventricular ejection fraction (LVEF), peak filling rate (PFR), left ventricular size. A multivariate logistic analysis showed that only three out of ten clinical and functional variables qualified to be independent predictors of death: right ventricular aneurysm (odd ratio = 2.48, confidence limits = 1.21-4.98), LVEF less than 52% (odd ratio = 1.91, confidence limits = 1.03-3.48), abnormal terminal P wave forces (odd ratio = 1.72, confidence limits = 1.07-2.75). The analysis of single case histories did not provide a clue to clarify the reasons accounting for the negative prognostic implication of a right ventricular aneurysm. In conclusion, a significant positive relationship between right ventricular aneurysm and mortality after AMI has been demonstrated; further study is needed to clarify the relevant mechanisms.

Sterol carrier protein-2 is involved in cholesterol transfer from the endoplasmic reticulum to the plasma membrane in human fibroblasts.

The cellular mechanism of cholesterol transport from the endoplasmic reticulum to the plasma membrane is currently unknown. To assess the possibility that sterol carrier protein-2 (SCP-2) is involved in this transport, we studied the time course of newly synthesized cholesterol incorporation in the plasma membrane of normal and SCP-2-deficient (Zellweger syndrome) human fibroblasts. Cholesterol transfer was rapid, cytoskeleton-independent, and Golgi-independent in normal cells, but it was slower, cytoskeleton-dependent, and Golgi-dependent in SCP-2-deficient cells. After SCP-2 antisense oligonucleotides treatment of normal fibroblasts, the rapid transport was reduced by 81% with a simultaneous increase of the slower one. These results suggest that in normal fibroblasts the major fraction of newly synthesized cholesterol is transported to the plasma membrane by a SCP-2-dependent mechanism. In contrast, in SCP-2-deficient cells, newly synthesized cholesterol leaves the endoplasmic reticulum by a cytoskeleton/Golgi-dependent mechanism.