Survey of Dirofilaria immitis (Leidy, 1856) in random source cats in metropolitan Rio de Janeiro, Brazil, with descriptions of lesions

To evaluate the prevalence of heartworm disease in metropolitan Rio de Janeiro, RJ, Brazil, cats submitted for euthanasia were evaluated by laboratory tests and by necropsy for signs of heartworm infection. Of the 135 cats examined, one (0.8%)--a stray male from an urbanizing district--had one male worm (14.5 cm) in the left lung and showed severe muscular hypertrophy of small pulmonary arteries and arterioles with no right ventricle enlargement or passive congestion. Microfilariae were not detected in the blood of any cats. The prevalence of canine heartworm in the area from which this cat originated is estimated to be approximately 12%. The prevalence of canine heartworm in the urban area of Rio de Janeiro has been determined to be approximately 5%. It has been shown that the prevalence of feline heartworm disease parallels that in dogs, but at a lower rate. Results of this survey strongly suggest that heartworm prevention measures should be taken under consideration, especially among cats living in a high canine heartworm prevalence area.

Induction of neutralizing antibodies in mice immunized with scorpion toxins detoxified by liposomal entrapment

The possibility of producing neutralizing antibodies against the lethal effects of scorpion toxins was evaluated in the mouse model by immunization with an immunogen devoid of toxicity. A toxic fraction (5 mg) from the venom of the scorpion Tityus serrulatus was entrapped in sphingomyelin-cholesterol liposomes. The liposomes were treated for 1 h at 37 degrees C with a 1% (w/w) trypsin solution in 0.2 M sodium carbonate buffer, pH 8.3. This treatment led to a strong reduction in venom toxicity. Immunization was performed as follows: mice were injected s.c. with 20 micrograms of the liposome-entrapped toxic fraction on days 1 and 21 and a final injection (20 micrograms) was administered i.p. on day 36. After injection of the immunogen, all mice developed an IgG response which was shown to be specific for the toxic antigen. The antibodies were measured 10 days after the end of the immunization protocol. In an in vitro neutralization assay we observed that pre-incubation of a lethal dose of the toxic fraction with immune serum strongly reduced its toxicity. In vivo protection assays showed that mice with anti-toxin antibodies could resist the challenge with the toxic fraction, which killed, 30 min after injection, all non-immune control mice.

[Comparison of preschool children's performance using the Denver developmental test, before and after nutritional intervention]

Psychomotor and development analysis must be emphasized when studying institutionalized children. Many previous investigations have been showing deleterious effects of day care centers over developmental performance in children.

OBJECTIVE

This study is aimed at comparing the performance in the Development Screening Test (Denver) in children attending day care centers, before and after nutritional intervention with an energetic supplement enriched with iron.

METHOD

130 children from 2 to 6 years old, attending three municipal day care centers, were evaluated by means of the application of the Denver test; by trained psychologists, comparing the collected data according to sex and age group, before and after six months intervention with iron enriched protein energetic supplement.

RESULTS

Most of the children had normal performance, both in first application (70.80%), and in the second one (80.80%). When comparing these results, 76.92% of the children had not altered their performance and 18.46% improved it substantially. As to sex, no significant differences were found and as to age group, there was significant improvement among children aged 4 to 6 years of age.

CONCLUSIONS

Besides the nutritional aspects, factors such as learning readiness, family organization, and psychopedagogic orientation to the day care centers, must have fostered development, even if the low socioeconomic level of the studied population is considered.

Neutralizing capacity of antibodies elicited by a non-toxic protein purified from the venom of the scorpion Tityus serrulatus

Polyclonal rabbit antibodies raised against a non-toxic protein (TsNTxP) purified from the toxic fraction of the crude venom of Tityus serrulatus can neutralize the effects of the venom. The antigenic specificities of anti-TsNTxP were compared by an indirect enzyme-linked immunosorbent assay using TsNTxP, TstFG50 (toxic fraction of venom that represents most of the toxicity of the crude venom), and crude venoms from T. serrulatus, T. bahiensis, T. cambridgei, T. stigmurus, Androctonus australis Hector and Centruroides sculpturatus to coat microtitration plates. The anti-TsNTxP antibodies had a comparable high cross-reactivity with the toxic fraction and crude venom of T. serrulatus, moderate binding capacity for T. bahiensis, T. cambridgei, T. stigmurus and were unable to recognize the venoms of A. australis Hector and C. sculpturatus. Quantities of venom equivalent to 20 LD50 were effectively neutralized by 1 ml of the anti-TsNTxP serum. This result shows that this protein may be of interest in the production of antivenoms for clinical use.

Comparison of complement activation in vitro by different Echinococcus granulosus extracts

In the present study we have investigated and compared in vitro the specific complement (C) activating activity of three metacestode preparations of Echinococcus granulosus. Extracts from hydatid cyst fluid (HCF-ext), protoscoleces (PSC-ext) and hydatid cyst membrane (HCM-ext) activated human C producing C3 conversion and generating the C5b6 complex and the terminal C complex (TCC). HCM-ext showed much lower C activating activity than PSC-ext and HCF-ext. Moreover, its ability to generate C5b6 and TCC was lower than its ability to convert C3. On the other hand, PSC-ext and HCF-ext proved to be good C activators when their specific C activating activities were compared with that of inulin. However, PSC-ext produced lower levels of TCC than those produced by HCF-ext, in spite of the fact that both produced practically the same levels of C3d and C5b6. These results may be consistent with the existence of several mechanisms of C modulation involved in the defence of the parasite against host C damage.

The calcium sensor ruthenium red can act as a Fenton-type reagent

Ruthenium red (RR), an ammoniated form of tris-ruthenium(III,IV,III) oxychloride, has been widely used in the micromolar range as a strong and specific inhibitor of in vitro and in vivo Ca(2+)-mediated biochemical processes without regard for its redox properties. We show here that in the presence of tert-butyl hydroperoxide (TBHP) and an electron source, either succinate-energized rat liver mitochondria or ascorbate, RR amplifies the generation of methyl radicals. The EPR spin trapping signal of the 5,5-dimethyl-1-pyrroline-N-oxide/methyl radical (DMPO/.CH3) adduct obtained from incubations of TBHP (1.5 mM) and mitochondria (5 mg protein/ml) in an adequate medium increases upon addition of RR in a concentration-dependent fashion: sixfold at 10 microM RR. Respiring mitochondria can be replaced by ascorbate (1 mM), the characteristic EPR signal of the ascorbyl radical also being observed (aH = 0.18 mT). Spectrophotometric, cyclic voltammetric and spectroelectrochemical studies unequivocally show oxidation of RR(III,IV,III) (lambda max = 538 nm) to the ruthenium(IV,III,IV) species ("ruthenium brown," RB; lambda max = 464 nm) by TBHP, followed by its one-electron back reduction to RR by the respiratory chain or ascorbate. The calcium chelator EGTA (1 mM) strongly binds and stabilizes the RR form, slowing down its recycling by TBHP and either ascorbate or the mitochondrial electron chain. These data clearly show that Ru(III) in the RR complex can reduce TBHP via a Fenton-type reaction and thus must be considered when RR is used as a tool to study biological processes simultaneously involving Ca2+ ions and peroxides.

[Hepatic glycogenosis in childhood: clinical and laboratory findings in 20 patients]

We studied 20 children with a clinical picture and laboratory study suggestive of hepatic glycogenosis. The age of the beginning of symptoms varied from birth to 24 months and the age at the diagnosis varied from 2 to 81 months. Hepatomegaly was found in all patients, diarrhea in 65% (13/26), "doll-face" in 55% (11/20) and convulsions in 50% (10/20). Nutritional evaluation showed more height deficiency than weight deficiency. Laboratory tests showed elevation of hepatic transaminases (12/19), hypercolesterolemia (8/14), hyperuricemia (6/17) and hypoglycemia (6/20). Liver function was not compromised in most of the cases. The results of glucagon tolerance test were variable. The histoenzymology study performed in 15 patients revealed the following results: Type VI (liver phosphorylase deficiency) in seven, Type I (glucose-6-phosphatase deficiency) in two, Type IV (brancher enzyme) in one and no conclusion could be drawn in five patients. The finding of hypoglycemia in few cases of this study can be justified by the few number of glycogenosis Type I, probably due to the fact that this type is the most easily diagnosed, with less necessity of referring them to specialized centers.

Study of the in vitro activation of the complement alternative pathway by Echinococcus granulosus hydatid cyst fluid

In the present study we have investigated the fluid phase activation of the complement (C) alternative pathway by Echinococcus granulosus sheep hydatid cyst fluid (SHCF) and its higher molecular weight fraction (SHCF-I) by quantitating the formation of both the terminal C intermediary C5b6 complex and the terminal C complex (TCC). Our results show that in vitro C activation progresses beyond the C5 step suggesting that potentially lytic complexes may be generated in vivo. In addition, SHCF and SHCF-I glucidic moieties are probably involved in C activation since 80% and 86% of SHCF and SHCF-I activity respectively was destroyed by periodate oxidation. Furthermore, partial deglycosylation with Peptide N-Glycosidase F of SHCF-I which had been digested with Pronase E, released an active fraction (MW < 14 KDa) which bound to Soybean agglutinin, suggesting that N-linked oligosaccharides containing alpha- or beta-linked N-acetyl galactosamine play a role in C activation by SHCF.

Echinococcus granulosus: interactions with host complement in secondary infection in mice

Complement has been shown to lyse protoscoleces of Echinococcus granulosus, but products from this parasite are able to consume complement, and this has been proposed as an evasion mechanism. The murine secondary hydatidosis model, with intraperitoneal inoculation, is used in this work to assess the occurrence in vivo of complement consumption by the parasite as well as the role of complement during the establishment of infection. Although the measurement of systemic levels of C3 activation, total C3, and hemolytic complement in challenged mice yielded no evidence of complement consumption, the relevance of local consumption at the site of infection cannot be ruled out. The role of complement during establishment of infection was assessed by comparing parasite burdens in normal and complement-depleted mice. Complement depletion by treatment with cobra venom factor caused a 79% reduction in cyst numbers (P < 0.05). Possible explanations of this unexpected result are discussed. The results presented suggest that lysis or opsonization by host complement are not effective against the establishing parasite in this model. They also indicate the significance of complement activation by the parasite needs to be studied at a local level.

[The credit system. Post-graduate medical education and continuous medical education]

The author examines the objectives behind the possible adoption of a Credit System by the Portuguese Medical Association. Credits are units that allow physicians to keep a record of their educational and professional undertaking. The paper defines Postgraduate Medical Education and Continuing Medical Education and specifies to which group of physicians each term applies. It describes the types of activities and objectives of each form of medical education and explains the philosophy underlying both. The author also urges that the Portuguese Medical Association set up essential structures to ensure the efficient functioning of the system. The paper outlines the criteria to be used for awarding Credits and discusses the natures of credit-granting institutions. The Credits are grouped into pre-defined Categories of differing weight. The author also recommends a credit value for each activity and, taking into account the nature of each activity, assigns it to a specific Category. Several types of Forms for Applying for and Registering Credits are shown. The information on these Forms is to go on the physicians record, to be filed on a database with the Portuguese Medical Association at a place set aside for the purpose.

Copper(I) transfer into metallothionein mediated by glutathione

Rabbit liver metallothionein depleted of Cd(II) and Zn(II) was fully reconstituted using a Cu(I)-GSH complex under strictly anaerobic conditions. Anaerobic fluorescence titration, using an emission band at 625 nm which is diagnostic of the correct insertion of Cu(I) into the thiolate clusters of metallothionein, showed that the fluorescence maximum was obtained on addition of as many Cu(I) equivalents as the available Cu(I)-binding sites in the protein (i.e. 12). Binding was nearly complete within 1 min, and Cu(I)-GSH was much more efficient than Cu(I)-thiourea or Cu(I)-acetonitrile in metallothionein reconstitution. In air, full reconstitution was obtained with stoichiometric copper only when an excess of GSH was present in the reaction mixture. Cu(I)-GSH was also able to displace Zn(II) and Cd(II) from natural metallized thionein. It is concluded that: (a) Cu(I)-GSH is a potential physiological Cu(I) carrier, not only for Cu2+/Zn2+ superoxide dismutase [Ciriolo, Desideri, Paci and Rotilio (1990) J. Biol. Chem. 265, 11030-11034] but also for metallothionein; (b) in the case of metallothionein, physiological concentrations of GSH protect the protein from autoxidation in air and facilitate Cu(I)-thiolate exchange; (c) the natural metal composition of metallothionein may be related to metal bioavailability rather than to evolutionary changes in protein structure.

Echinococcus granulosus: study of the in vitro complement activation by protoscoleces by measuring the electric potential difference across the tegumental membrane

Complement activation by protoscoleces of Echinococcus granulosus was studied by analyzing the damage to their tegumental membrane produced by incubation in both normal and hydatid human sera. The state of the apical tegumental membrane was evaluated by measuring the electric potential difference with microelectrodes. Protoscoleces incubated in Ringer-Hepes or in heat-decomplemented normal human serum in the presence or absence of specific antibodies did not show significant variations in the electric potential difference throughout the experiment (P > 0.4 in all cases) and their mean values were -46 +/- 3, -43 +/- 4, and -56 +/- 5 mV, respectively. In contrast the potential difference of protoscoleces incubated in 1:2 diluted normal human serum showed a significant variation (P < 0.001), reaching -10 +/- 6 mV after 30 min, and the median depolarization time was estimated to be 21 +/- 3 min. The capacity of normal human serum to depolarize the tegumental membrane of protoscoleces was abolished by treatment at 50 degrees C during 20 min or by 10-fold dilution. In addition, protoscoleces incubated in 1:10 diluted hydatid human serum plus 1:10 diluted normal human serum or Factor B-inactivated normal human serum showed a significantly faster depolarization (0.01 < P < 0.02 and P < 0.001, respectively): the potential difference reached -13 +/- 5 mV after 15 min and the median depolarization times were 9 +/- 5 and 5 +/- 3 min, respectively. Our results suggest that following the time course of the potential difference is a useful tool for studying complement activation in the host-parasite interface and they show that the tegumental membrane of protoscoleces can activate the alternative pathway of human complement.

Iron(III) binding in DNA solutions: complex formation and catalytic activity in the oxidation of hydrazine derivatives

A strong interaction between iron(III) and calf thymus DNA at pH 7.4 was demonstrated in the present study by separation of the complex by column chromatography and by the slow kinetics of iron(III) removal from DNA by disodium-1,2-dihydroxybenzene-3,5-disulfonate (Tiron). An equilibrium constant of 2.1 x 10(14) was calculated by measurements of bound iron(III) by flame atomic absorption spectroscopy and assuming a one iron to two nucleotide stoichiometry. Graphic analysis of the interaction however, indicated that DNA has two binding sites for iron(III) characterized by a stoichiometry of one iron to 12 nucleotides and one iron to 2 nucleotides, and association constants of 4.8 x 10(12) and 2.3 x 10(11), respectively. The DNA-iron(III) complex isolated by column chromatography was shown to catalyze the oxidation of both 2-phenylethylhydrazine and methylhydrazine by spin-trapping experiments with alpha-(4-pyridyl 1-oxide)-N-tert-butylnitrone (POBN). By contrast, oxidation of 1,2-dimethylhydrazine was not catalyzed. Catalysis of 2-phenylethylhydrazine oxidation was confirmed by oxygen consumption studies. The results suggest that iron chelated to DNA may be significant in DNA damage induced by oxidizable chemicals.

Histological, morphometric and histochemical changes in the submandibular gland of the rat under experimental protein-calorie malnutrition

Submandibular salivary glands of rats, subjected to experimental protein-calorie malnutrition, were studied by histologic, morphometric and histochemical methods. Marked alterations were observed. Acinar atrophy, a severe decrease in the volumetric proportion of the granular duct, and a decrease in the protein content of the granular duct cells were all recorded. Neutral mucosubstances were reduced in both acinar and granular duct cells.

Fine-specificity of the immune response to oxazolone. I. Contact sensitivity and early antibodies

The specificity of the contact sensitivity induced by various chemically related oxazolones was studied. Mice were painted with 1 of them (immunogen). They were divided into several groups and challenged (ear painting on day 5) with various concentrations of either the immunogen or a related oxazolone. The degree of the contact sensitivity was estimated by ear weight or by incorporation of a DNA precursor. Higher concentrations of a challenge compound elicited a stronger DTH reaction than lower concentrations. The efficiency of each compound was defined by the concentration that caused a 30% increase of the ear weight or 150% increase of incorporation. Both represented ca. one-third of the maximal response (1/3 max), and both methods gave similar results. Two types of specificity patterns were observed. One is based on limited data, and was exhibited by the pair furyl Ox and propenyl Ox. Furyl Ox was a more efficient challenge compound than propenyl Ox when mice were primed with furyl Ox. The reverse was true when mice were primed with propenyl Ox. The other pattern was exhibited by the pair propenyl Ox and phenyl Ox. When mice had been primed with phenyl Ox, the 1/3 max response required either 3 mM phenyl Ox or 17 mM propenyl Ox (6-fold difference). The unexpected finding was that phenyl Ox was also a (2.5-fold) more efficient challenge compound for mice that had been primed with propenyl Ox (a heteroclitic contact sensitivity).

Fine-specificity of the immune response to oxazolones. II. Cytolytic T cells

Hapten-specific cytolytic T lymphocytes (CTL) were generated either by culturing live mouse spleen cells together with syngeneic haptenated mitomycin-treated spleen cells, or by painting cyclophosphamide-treated mice with the (chemically reactive) haptens. The specificity of the CTL was then tested by using lymphoblast targets coupled with the immunizing hapten or its analogs. Four haptens of the 5-oxazolone family were used. They couple to proteins via carbon atom 4 and had different substitutions at carbon atom 2. CTL originating from the in vivo or in vitro immunization gave identical results. They were specific for the genotype of the immunizing cell and for the hapten (oxazolone family). Syngeneic targets coupled with an unrelated hapten were not killed, nor were allogeneic (H-2-incompatible) targets coupled with any of the oxazolones. Oxazolone-specific CTL could be generated with all 4 oxazolones tested, but all 4 types of killer cells preferred targets coupled with 1 hapten, propenyl Ox. CTL generated with phenyl Ox, furyl Ox, or F-phenyl Ox were thus "heteroclitic" (preference for a chemical analog over the immunogen).