Biliary lipid secretion: immunolocalization and identification of a protein associated with lamellar cholesterol carriers in supersaturated rat and human bile

Feeding a 0.5% diosgenin plus 0.02% simvastatin diet to rats increases biliary cholesterol concentration and saturation to levels generally found in human native supersaturated bile. By using preparative ultracentrifugation, gel filtration chromatography, and electron microscopy, we isolated, purified, and identified lamellar structures (unilamellar vesicles and multilamellae) as a major biliary cholesterol transport in supersaturated human and rat bile. It was estimated that more than 60% of biliary cholesterol is transported in these lamellar carriers, which were identified by transmission electron microscopy as unilamellar vesicles and multilamellar bodies within bile canaliculi of rats with cholesterol supersaturated bile. By SDS-PAGE, a characteristic and constant protein profile was found associated to the purified lamellar carriers. One of these proteins, a 130-kDa protein, was isolated from human biliary lamellae and used for preparation of a rabbit polyclonal antibody, which cross-reacted with the homologous rat protein. By Western blotting, it was established that the purified low density fraction of bile-Metrizamide gradients, containing lamellae, was enriched with the 130-kDa protein. The 130-kDa protein was characteristically detected at the canalicular membrane by Western blotting of hepatic subcellular fractions and by immunohistochemistry of rat and human liver biopsies. Amino acid sequencing of the amino terminus of the 130-kDa protein demonstrated a complete identity with aminopeptidase N, a canalicular transmembrane hydrophobic glycoprotein. These studies show that biliary lipids may acquire an ordered multilamellar structure that is present in the canaliculi of rats with supersaturated bile. These biliary lamellae are similar to lamellar bodies and surfactant-like material frequently found in other epithelia, suggesting common biogenetic, structural, and functional properties. The identification of aminopeptidase N associated with biliary lamellae is consistent with the involvement of the canalicular membrane in the secretory mechanism of biliary lipids.

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.

Isolation and partial characterization of cholesterol pronucleating hydrophobic glycoproteins associated to native biliary vesicles

Cholesterol is transported both in unilamellar phosphatidylcholine vesicles and in bile salts-mixed micelles in native bile. The vesicular carrier of biliary lipids apparently has a well defined protein profile with a potent cholesterol crystallization-promoting activity. This study was conducted to identify and further characterize these vesicular proteins and to test the effect of isolated vesicular proteins on the cholesterol crystal formation in supersaturated model bile. The results confirmed that proteins are a constant component of highly purified biliary vesicles both in hepatic and gallbladder bile. Immunoglobulins (IgA, IgG and IgM) and albumin are associated to the purified hepatic biliary vesicles. Furthermore, four different hydrophobic glycoproteins with a molecular mass of 130, 114, 86, and 62-67 kDa were isolated. These glycoproteins showed no reactivity with anti-human whole serum or anti-immunoglobulin antibodies, suggesting that these proteins are biliary-specific. Isolated 130, 114 and 62-67 kDa vesicular glycoproteins significantly decreased the cholesterol nucleation time in artificial model bile. We concluded that some, but not all, vesicular-bound hydrophobic glycoproteins have cholesterol pronucleating activity and they may be involved in the pathogenesis of cholesterol gallstone disease.

[Seroprevalence of antibodies against Plasmodium falciparum in volunteer donors from various cities in Venezuela]

The prevalence of antibodies to Plasmodium falciparum was studied in 890 blood donors from different geographical areas of Venezuela. The overall prevalence, as established by ELISA, was (1.7%). Seropositivity was higher in those samples obtained in Sucre (2.5%) and Apure (1.7%) states both with foci of malaria transmission. It is proposed that medical history should be reinforced by screening antimalarial antibodies in donors at risk.

[Role of intraoperative echo-Doppler color echocardiography in cardiac surgery. Preliminary study]

Intraoperative echocardiography with Doppler color flow imaging technique can provide the surgeon with an immediate and direct assessment of cardiac anatomy and function. To determine the utility of this recent technique, we have examined 15 patients pre, per, and postoperatively with Doppler color flow imaging. The intraoperative study was performed before and after cardiopulmonary bypass. A sterile transducer was placed directly on the epicardial surface of the heart, and multiple views were recorded. Intraoperative echocardiography with Doppler color flow imaging technique demonstrated excellent correlation with preoperative and postoperative findings, allowing an immediate evaluation of the surgical results. These preliminary results suggest that intraoperative Doppler color flow imaging technique is a valuable adjunct in heart surgery. It is particularly useful in valve repair, and in surgical repair of congenital heart disease.

Antimicrobial activity of clove oil dispersed in a concentrated sugar solution

Essential oil of clove, dispersed (0.4% v/v) in a concentrated sugar solution, had a marked germicidal effect against various bacteria and Candida albicans. Staphylococcus aureus (five strains), Klebsiella pneumoniae, Pseudomonas aeruginosa, Clostridium perfringens, and Escherichia coli inoculated at a level of 10(7) cfu/ml, and C. albicans (inoculum 4.0 x 10(5) cfu/ml) were killed (greater than 99.999%) after 2-7 min in a laboratory broth supplemented with 63% (v/w) of sugar, and containing 0.4% (v/w) of essential oil of clove. Added organic matter (i.e. human or bovine serum) did not impair its antimicrobial activity. Sugar was not necessary for the antimicrobial activity of clove oil, but the concentrated sugar solution provided a good vehicle for obtaining an oil dispersion that is relatively stable for certain practical applications.

Extensive aneurysm of the aortic arch and descending aorta. Extra-anatomical reconstruction and exclusion of the aneurysmal sac

A new technique for repair of extensive aneurysm reaching from the ascending aorta to the diaphragm is presented. The operation consists of the reconstruction of the aortic arch and descending aorta and the exclusion of the aneurysmal sac in a single operation. Two successful cases are presented.

Commissurotomy and pregnancy. A study of 245 cases

We present a retrospective study of 245 pregnancies in 157 women who had undergone commissurotomy (closed surgery) and whose delivery was assisted at the Maternity La Paz (Madrid, Spain) between 1965 and 1981. There was a statistically significant increase in the rate of fetal complications (perinatal mortality, 44.3 per 1,000; pre-term 8.5%; intra-uterine growth retardation, 17.3%; low weight, 12.5%) and maternal mortality. The most frequent and severe maternal complication was congestive heart failure which was more common among primigravidas and was of statistical significance. In patients with atrial fibrillation or heart failure during pregnancy or puerperium, the results were even more remarkable. There were no complications in patients who underwent commissurotomy during pregnancy. Preterm delivery was three times more common in patients undergoing digitalis therapy.

Chagas' disease in pre-Columbian South America

The quest for the origin and dispersion of Chagas' disease, the second most important vector-borne disease in Latin America, has epidemiological, immunological, and genetical implications. Conjectures based on accounts of chroniclers, reviews of the archaeological literature and the present distribution of triatomine bugs, the vectors of the disease, held that the origin of the adaptation of Triatoma infestans (a species of the subfamily Triatominae) to human dwellings occurred in prehistoric times. The autopsy of 35 mummies exhumed in the Chilean desert, dated between 470 B.C. and 600 A.D., revealed the presence of clinical manifestations of Chagas' disease and put earlier speculations on a factual basis.

Comparative studies on glucose phosphorylating isoenzymes from vertebrates--VIII. Immunochemical studies on mammalian hexokinases A

An immune serum elicited in a rabbit by injection of homogeneous brain hexokinase A was shown to be specific for the antigen. Other rat hexokinase isoenzymes (hexokinases B, C or D) did not present cross-reaction when tested by immunoinhibition of enzyme activity, double immunodiffusion and immunoadsorbent columns. The enzyme activity of hexokinase A from several mammals (rodents, lagomorphs, artiodactyls) was partially inhibited by the immune serum. In the case of mouse enzyme, the amount of serum required to inhibit 50% of the activity was five-fold higher than in the case of the rat enzyme. Enzymes from cow or sheep brain were only marginally affected. Hexokinases A isolated from various mammals, tested against the rat enzyme, showed faint lines of precipitation and marked spurs in double immunodiffusion plates even when enzymes from closely related rodents were analyzed. Immunoadsorbent columns, on the other hand, were able to retain most of the activity of hexokinases A from the mammals studied. Micro-complement fixation tests showed that hexokinases A from mammals outside the Order Rodentia were only partially recognized by the anti-hexokinase Arat serum. The results suggest that amino acid substitutions on the hexokinase A molecule have occurred at a rather fast rate.

Prosthetic heart valve and pregnancy. A study of 59 cases

We studied 59 pregnancies in 48 female carriers of prosthetic heart valves. In 44 pregnancies the mother had a metal valve mostly with coumarin therapy and in 15 a bioprosthesis usually without hematologic treatment. In the patients with metal prostheses we had the following maternal complications: 1 maternal death, 3 valve thromboses, 2 heart failures and 1 puerperal hemorrhage. There was also a significantly increased rate of preterm, low birth weight infants and intrauterine growth retardation. Concerning malformations we found only 2 cases of mild nasal hypoplasia. Regarding the complications of bioprosthesis, we had only 1 case of paroxysmal tachycardia and no fetal complications. Comparing the results we came to the conclusion that pregnancy is much better tolerated in patients with bioprostheses and that in patients with metal prostheses the risk is increased if the mother is older than 30 years, if time of replacement is more than 5 years or if there is a history of previous thromboembolism or gravidic heart failure.