[In vitro decrease of the cytolytic effect of E. histolytica by inhibition of its phosphofructokinase]

The C14 radioactive label of PPi analogues was incorporated to E. histolytica after 24 hours of incubation at 37 degrees C; more than 90% of trophozoites remained viable. The PPi dependent phosphofructokinase was isolated in order to determine its kinetic parameters. With PPi, the Km was 18.06 +/- 0.91 micromol/mL-1. Using three different PPi analogues (tetrasodium salts) of (I) 1,1 hydroxy-methyl diphosphonate; (II) 1,1 hydroxy ethylene diphosphonate; (III) 1,1 hydroxy-nonano diphosphonate, KiI was 35.19 +/- 1.74; KiII was 42.65 +/- 0.65, and KiIII 2as 62.81 +/- 0.27 micromol/mL-1. The graphic expression of these results shows that the enzyme was competitively inhibited by the three analogues. When trophozoites were incubated with each one of the three inhibitors, a correlation was observed between the concentration and the cytolytic inhibition with an r = 0.98. Nevertheless, the slope obtained was different for each one of them. The smallest concentration of inhibitor to achieve a 50% lysis inhibition of trophozoites was that of inhibitor III. In addition, it was demonstrated that the incubation of the trophozoites with this inhibitor increased the time needed to destroy CHO cells. We conclude that enzymatic inhibition of the PPi dependent phosphofructokinase caused by the PPi analogues was responsible for the modification of the lytic capacity of trophozoites, possibly by altering the metabolic pathway of carbohydrates.

[Interaction of the cytoskeleton of E. histolytica with human erythrocytes]

The mechanism by which trophozoites of E histolytica destroy mammalian cells has been correlated with the polymerization of the actin contained in the amoeba's cytoskeleton. This is preceded by the attachment of the amoeba lectins with carbohydrates in the cell surface. Here we describe the events of the interaction of E histolytica cytoskeleton with human red blood cells using fluorescence microscopy of glutaraldehyde-fixed trophozoites membrane removed with triton X-100 and stained with rhodamine-phalloidin. The challenge with RBC revealed a maximum polymerization two minutes after the challenge. The most active phagocytosis was observed four minutes after challenge. The use of fluorescent phalloidin showed to be a fast method which specifically binds to the F form of actin; this method is easier than methods which use monoclonal antibodies to identify actin.

[Immune response induced by phosphofructokinase from E. histolytica in hamsters]

The enzymatic activity of inorganic pyrophosphate (PPi) dependent phosphofructokinase became manifest in the supernatant obtained by centrifugation in a homogenate of E. histolytica strain HMI-IMSS at 700,000 g. Partial purification of the enzyme was achieved by column chromatography with Ultrogel AcA-34. Ten protein elution spikes were obtained: five showed enzymatic activity. Elution spikes I and II attained the highest values of specific enzymatic activity 6.45 and 6.98 U/mg of protein, respectively. Next were spikes X and III with similar values 2.55 and 2.63 U/mg of protein, and spike IV presented the lowest value of 0.86 U/mg of protein. The five spikes were used to immunize hamsters which were challenged intrahepatically, four weeks later, with 3 x 10(5) trophozoites of E. histolytica. A control group of animals not immunized underwent intrahepatic challenge with the same number of amebae. The proteins with enzymatic activity contained in elution spikes I and II conferred immunologic protection in 100% of the animals, while elution spikes X and III were protective in 50 to 63%, and spike IV gave the lowest value of 37%. It can be assumed that there is an antienzyme antibody responsible for the absence of hepatic abscesses in the immunized hamsters.

[Induction of protective antiamebic immunity in hamsters with heterologous antigens]

Two hundred and twenty-five Syrian golden hamsters were used. Twenty five of them served as the control group. All other hamsters were intradermal immunized, once a week for four weeks, with a mixture of amebic proteins, mixed with complete Freund adjuvant, obtained from 5 x 10(5) homogenized dead amebic trophozoites from five different strains. Each group of hamsters (five groups of 40 animals each) were immunized with one of the following strains: E. histolytica HM-531, HJ-1, HM1-IMSS, E. chattoni PM-4 and PM-5. All hamsters, including those from the control group, were later inoculated with 0.2 mL equivalent to 1 x 10(5) live trophozoites from the different strains grown in axenic TYI-S-33 medium. Inoculation was performed by direct injection into the liver. The hamsters were sacrificed eight days later and their livers examined. All non-immunized animals showed extensive gross hepatic nodular abscesses. The liver of immunized hamsters showed mild to moderate lesions: the histopathological striking feature was non-specific granulomata. It is concluded that the immunized animals inoculated with homologous stock showed protective immunity to amebic infections. In other cases, immunity was seen though they were inoculated with a heterologous stock.

[Zollinger-Ellison syndrome. Report of a case]

A 61 years old male with Z-E syndrome is reported. He presented gastrointestinal bleeding, abdominal pain, slightly elevated gastrin and hypoglycemia. He underwent total gastrectomy, a non-resectable tumor of the tail of the pancreas with liver metastasis were found. A biopsy of the liver metastasis and the gastric mucosa were reviewed under the light and the transmission electronic microscopes. The gastric mucosa showed abundant parietal cells. The metastatic hepatic tissue was poorly differentiated under the light microscope and the electron micrographs revealed tissue resembling pancreatic islands of Langerhans with granules in the cytoplasm, this means that the neoplasm originated from APUD cells.

[Electron microscopy of the intestinal mucosa in a case of lymphangiectasis]

The morphology of the intestinal mucosa was reviewed using light microscopy and transmission electron microscopy from a two year-old male patient with protein losing primary intestinal lyphangiectasis. Diagnostic studies ruled out recognized forms of secondary intestinal lymphangiectasia (e.g cardiac, hepatic, renal diseases or lymphoreticular cancer). Furthermore, certain features distinguish this patient from the secondary type: decreased immunoglobulin and albumin levels, lymphocytopenia, chylous ascitis and delated lymphatics on small-bowel biopsy.

[Ultrastructure of the hepatocyte during hepatic regeneration after partial hepatectomy]

A batch of 45 male Wistar rats, weighing 180 to 325 grams, were used in the experiment. Partial hepatectomy was practiced to them and liver biopsies taken at different periods of times: 0 (control) 4, 8, 12, 24, 36, 48, and 72 hours and 45 days. The biopsies were examined at the electron microscope. During liver regeneration, a sequence of morphological changes was detected, having started with an important decrease of cytoplasmic particles, increase of lipids and laminar bodies like myelin. After 24 hours, preparatory changes for cellular regeneration were observed prior to full regeneration which was reached later.

[Gaucher's disease. Morphological study of lymph nodes by electron microscopy]

The morphological study of lymph node biopsies by light and electron microscopes is reported. The patient was a 7 months old infant with Gaucher's disease and infection symptoms of upper respiratory ducts. We believe this to be a case of lesser affection, since the patient was admitted complaining of complications that gave way to medical treatment. Lymphadenopathy and moderate liver and splenomegaly were occasional findings during examination. Through the light microscope, Gaucher's cells showed an eccentric nucleous, cytoplasmic striae which, at the electron microscope showed to be tubular bodies.

[Morphological study of the myocardium in children and adults under normal conditions and in hypoxia]

At the light and electronic microscopes, 32 myocardial biopsies from 16 patients were studied. The study was carried out in 8 children under 5 years of age and in 8 adults over 20 years during open-sky surgery of the chest done to correct some congenital or acquired heart anomaly. Control biopsies were taken before the application of extracorporeal circulation and a second biopsy, after an average of 30 minutes of hypoxia, which was the time taken to perform the surgical correction of the anomaly. Following extracorporeal circulation, all cases showed mitochondrial mutuations, such as disorganization of their crests, marked distension, from edema to emptiness due to hypoxia. The lack of glycogen, the disorganization of the myofibrillae, decreased neatness of the sarcoplasm and nuclei with marginated chromation, were all preceded by mitochondrial mutations due to oxidative phosphorylation deficiency.

[Morphological study of the hepatocyte in cirrhotic patients treated with phenobarbital]

The authors report on a comparative study of light and electron microscopy in the diagnosis of tissue obtained in 21 percutaneous liver biopsies in patients known to have cirrhosis. Using light microscopy twelve patients were ascertained to have post-necrotic cirrhosis and twelve had Laennec's cirrhosis. All of these patients were given phenobarbital, 65 mg. every twelve hours, during twenty-one days. A control group of five patients received placebos. With electron microscopic methods, in all of the cirrhotic patients both before and after treatment with phenobarbital, the authors observed bands of fibrous tissue made up of collagen fibers and fibroblasts which originate in the portal spaces and in the Kupffer cells. This makes up the mesenchymal reaction to the liver cell damage, which in the long run proves to be more important than liver cell regeneration. Phenobarbital treatment resulted in hyperplasia of the agranular endoplasmic reticulum in liver cells. The authors agree with other authors that this is related to metabolic activity of enzymes acting on extraneous drugs and chemical substances.