An investigation of sterile immunity against toxoplasmosis in rats

The non-persistent BK strain was examined for its ability to induce sterile immunity in Wistar rats. Groups of 2-9 Wistar rats were inoculated subcutaneously with 5 x 10(4) BK strain tachyzoites per rat. Two months later, 46 rats were dosed by gavage with 2 x 10(1) cysts of the C, ME-49, Prugniaud, C-56, Elg, M-7741 or M3 strains. Another 26 rats were inoculated with 10(3) oocysts of the ME49, M7741, Bear or Hopa-Hopa strains of Toxoplasma gondii. After 2 months, the rats were euthanized and their brains screened microscopically for toxoplasma tissue cysts and bioassayed in mice if negative. As judged by bioassay, the BK strain of Toxoplasma induced statistically significant protection against reinfection only when rats were challenged with cysts of the C and Prugniaud strains or with oocysts of the ME49 strain. Nonetheless, cysts were detected microscopically only in 23% of brains of immunized rats challenged with oocysts of the Bear and Hopa-Hopa strains of Toxoplasma and none of those challenged with tissue cysts of any strain. Tissue cysts were detected in 43 and 48% of non-immunized control rats infected with tissue cysts and oocysts, respectively. The overall infection in control rats (microscopy and bioassay) was 70 and 72% for rats inoculated with cysts and oocysts, respectively. These results are consistent with the divergent results obtained by other investigators with regard to protection after challenge with different complete strains (cyst and oocysts forming) of the parasite, of rats immunized with incomplete strains.

Treatment of Type II Endoleaks after Endovascular Repair of Abdominal Aortic Aneurysms: Translumbar Puncture and Injection of Thrombin into the Aneurysm Sac

OBJECTIVES

The aim of this article is to report our experience in the use of a new technique for the treatment of type II endoleaks which appear after the endovascular treatment of abdominal aortic aneurysms.

MATERIALS AND METHODS

In three patients with secondary type II endoleaks, we performed a translumbar puncture, introducing a 22-Gauge needle into the aneurysm sac under CT guidance. Once intrasac pressure had been registered, 1000U (2 ml) of human thrombin were slowly injected into the sac.

RESULTS

Complete sealing of the endoleak was achieved in all three patients, confirmed by the lack of contrast filling of the sac in the CT scans performed 5 min and 24 h after the procedure. Initial intrasac pressure was equal to systolic arterial pressure in the three patients. After the procedure, the pressure decreased by 30-40 mmHg. There were no complications during the procedure, which lasted 45-90 min. No endoleak recurrence has been observed in any of the three cases 6 months later.

CONCLUSIONS

We present an alternative method of treating type II endoleaks, which could become the treatment of choice if and when a wider experience confirms our initial good results.

Cyst burden in the brains of Wistar rats fed Toxoplasma oocysts

Six strains of Toxoplasma oocysts were used to infect groups of 4-24 Wistar rats, with each rat being fed 10(1)-10(4) oocysts from a single strain. After 2 months, the rats were killed, their brains screened for Toxoplasma cysts and then bioassayed in mice if negative. Toxoplasma was either observed in the form of brain cysts or was recovered using the bioassay, from 113 out of 138 (82%) rat brains. As few as ten oocysts were capable of initiating a brain infection that lasted for at least 2 months in eight of the nine rats inoculated. However, judging from bioassay 10(2)-10(4) oocysts did not give rise to progressively higher rates of infection. Brain cysts were seen in only 68 of 138 rats (49%). The number of Toxoplasma cysts formed in the brains of rats was generally in the order of tens to hundreds. The frequency of infection in the brains with Toxoplasma and the number of brain cysts formed appeared to be influenced by the individual resistance of the rats as well as by the doses of oocysts and the Toxoplasma strains used. The information gathered is considered to be a basis for a rat model of immunity against acquired toxoplasmosis.

Fetal Toxoplasma infection after oocyst inoculation of pregnant rats

Six groups totalling 53 Wistar rats were fed 10(4)oocysts from one of six different Toxoplasma strains at 15 days of pregnancy. The overall transplacental transmission rate was 51%. This varied between 10% and 80%, dependent on the strain used. The strains of Toxoplasma which are more pathogenic for mice were transmitted transplacentally more frequently than the strains of intermediate or low pathogenicity. There were no statistically significant differences in the rate of congenital transmission of Toxoplasmain rats fed oocysts (present work) or cysts (previous work).

Conservation of phage reference materials and water samples containing bacteriophages of enteric bacteria

The survival was determined in different conservation conditions of: somatic coliphages, F-specific RNA bacteriophages and phages infecting Bacteroides fragilis proposed as model micro-organisms for water quality control. Titres of phages of all groups either in pure culture phage suspensions or in naturally occurring phage suspensions were stable at (-70+/-10) degrees C and at (-20+/-5) degrees C when protected with glycerol. Moreover, phage analysis of stored suspensions demonstrated that their numbers were homogeneous, both between vials and within vials, and consequently they can be used as reference materials. Furthermore, changes in the storage temperature of the vials cause unpredictable changes in the numbers of bacteriophages. Consequently, phage reference materials and samples containing a quantitative number of phages must be maintained and dispatched at a constant temperature. Consequently, the results indicate that bacteriophages should be packed in dry ice during transport and storage. Finally, the number of phages in water samples stored at (5+/-3) degrees C in the dark does not decrease significantly during the first 72 h of storage. In addition, phage concentrates from natural samples obtained by adsorption-elution to cellulose nitrate filters and mixed with 10% glycerol were stable at least for 2 months at (-70+/-10) degrees C and at (-20+/-5) degrees C.

Biological activity of Guatteria cardoniana fractions

Methanolic extract of leaves and twigs of Guatteria cardoniana R.E. Fries (Annonaceae), a plant from the Venezuelan rain forest, was separated in alkaloid rich fractions and their biological effect on baby hamster kidney (BHK) cell line was studied. The initial plant extract (FA) induced cell proliferation, cytotoxicity as well as antiviral activity, depending on the concentration used. Further separation of this methanolic extract allowed us to separate these biological activities. The fraction with the highest antiviral activity (F7) was chromatographed and three of the nine alkaloid-rich fractions obtained, retained this activity. One of them (F(7)11) exhibited the highest inhibitory effect against a neurotropic Sindbis virus (NSV).

Residual infection of 15 toxoplasma strains in the brain of rats fed cysts

Thirty-seven groups of 4-32 Wistar rats were 2-10(3) cysts of 15 Toxoplasma strains. After 2 months, the rats were euthanized and their brains screened for Toxoplasma cysts and bioassayed in mice if negative. The brains of 323 of 411 rats (78.6%) were found to be infected 2 months after inoculation with Toxoplasma cysts. Two hundred cysts were necessary to infect nearly 90% of the rats. With lower doses, only 60% of the rats had residual brain infection. Brain cysts were formed only in 146 of 411 rats (35.5%). The numbers of cysts formed were in the order of tens to hundreds, only occasionally one or two thousands. The mean percentage of rats with brain cysts, and the number of cysts formed in rat brains by different inocula, increased with higher doses of cysts and then declined. This pattern is difficult to explain and similar results regarding the number of cysts formed have been published. In relation to the mean percentage of rats infected, there appears to be a plateau in infection with the higher inocula. Neither the number of rats with cysts in their brains nor the numbers of cysts formed were dependent on the Toxoplasma strain used, with the exception of one strain. Instead, individual variations were marked, and are presumably related to variations in the individual genetic resistance to Toxoplasma infection in the rat. The information gathered is considered a preliminary step for a rat model of immunity against acquired toxoplasmosis.

Some factors influencing transmission of toxoplasma in pregnant rats fed cysts

An overall 44% transplacental transmission rate was observed in 221 rats fed cysts of 12 Toxoplasma strains at 15 days of pregnancy, with a range of 0-90% transmission. Considerable variability in the transmission rate was seen among different groups of rats that received similar Toxoplasma inocula; this is attributed to genetically based susceptibility to Toxoplasma among individuals of the outbred Wistar strain of rats. Transplacental transmission was more frequent in Long Evans than in Wistar rats. Significant differences in the rate of transmission were not found between rats that were fed similar Toxoplasma inocula 6-8 days or 15 days after conception. The frequency of transmission was not affected by the strain or dose of Toxoplasma used.

Influence of the selection of the suture material on the mechanical behavior of a biomaterial to be employed in the construction of implants. Part 1: Calf pericardium

A hydraulic stress simulator was employed to study the mechanical behavior of the calf pericardium used in the construction of cardiac valve leaflets. One hundred eighty pairs of tissue samples were subjected to tensile testing to rupture. One of the two samples from each of 144 pairs (four series of 36 pairs each) was sutured with commercially available threads made of nylon, silk, Prolene or Gore-Tex, while the other sample in each of these pairs was left unsewn. The remaining 36 pairs were employed as controls in which neither of the two samples was subjected to suturing. The sutured tissue samples showed a significant decrease in tensile strength at rupture (range: 11.81 to 26.04 MPa) when compared with unsutured samples (range: 39.38 to 87.96 MPa; p < 0.01). The application of morphological and mechanical selection criteria to maximize the homogeneity of the samples provided excellent fit with respect to the stress/strain curves. This method made it possible to carry out a predictive study of the mechanical behavior of a sutured sample, based on that observed in the corresponding unsutured fragment. The interaction of the different suture materials with the pericardial tissue was also assessed by comparing the mechanical behavior of the sutured samples with that of the control samples. At stresses of less than 0.8 MPa, samples sewn with Gore-Tex were found to show the least difference with respect to the controls, indicating that this material presented the lowest degree of interaction with the pericardium. In conclusion, the degree of the loss of resistance to tearing of the sutured samples is of no value in the selection of the optimal suture material. The selection process applied makes it possible to predict the mechanical behavior in response to suturing of a given unsewn tissue specimen by determining that of its sutured mate. The similarity between the findings in samples sewn with Gore-Tex and in the unsutured controls indicates a lesser degree of interaction between the suture material and the pericardium employed in the construction of cardiac valve leaflets.

Influence of the selection of the suture material on the mechanical behavior of a biomaterial to be employed in the construction of implants. Part 2: Porcine pericardium

Using a hydraulic stress simulator, the mechanical behavior of the porcine pericardium used in the construction of cardiac valve leaflets was characterized following the same procedure employed with calf pericardium in Part 1 of this study. One hundred fifty pairs of tissue samples were subjected to tensile testing to rupture. One of the two samples from each of 120 pairs (four series of 30 pairs each) was saturated with commercially available threads made of nylon, silk, Prolene or Gore-Tex, while the other sample in each of these pairs was left unsewn. The remaining 30 pairs were employed as controls in which neither of the two samples was subjected to suturing. The sutured tissue samples showed a significant decrease in tensile strength at rupture (range: 11.61 to 21.22 MPa) when compared with unsutured samples (range: 50.80 to 89.45 MPa; p < 0.01). When these results were compared with their equivalent in calf pericardium, no significant differences were observed (the mean values at rupture in calf pericardium ranged between 211.61 MPa and 26.04 MPa). Again, the application of morphological and mechanical selection criteria to ensure the homogeneity of the samples provided excellent fit with respect to the stress/strain curves. The interaction of the different suture materials with the pericardial tissue was also assessed by comparing the mechanical behavior of the sutured samples with that of the control samples. At the working stress of a cardiac valve leaflet, 0.250 MPa, samples sewn with Gore-Tex were found to show the least difference in behavior with respect to the controls, indicating that this material presented the lowest degree of interaction with the pericardium. In conclusion, the suture clearly has deleterious effects on the resistance of both calf and porcine pericardium, which showed no statistically significant differences in terms of resistance to rupture when their respective sutured or unsutured samples were compared, except in the case of porcine pericardium sewn with silk, which presented lower resistance to rupture in all the zones studied. These findings suggest that the hypothesis that porcine pericardium is less resistant is erroneous. The Gore-Tex suture also presented a lower degree of interaction with the porcine pericardium, with values similar to the working stress of a cardiac valve leaflet. This methodology and the results should be evaluated in dynamic studies, such as fatigue testing, that not only confirm the resistance of the material but establish the durability of the samples being assayed.

Triterpenes from Licania licaniaeflora

Nine triterpenoids with lupane, oleanane, and ursane skeleton have been isolated and characterized from the leaves of Licania licaniaeflora. The structural identification was based on (1)H and (13)C-NMR spectral data.

Porcine pericardial membrane subjected to tensile testing: preliminary study of the process of selecting tissue for use in the construction of cardiac bioprostheses

The durability of cardiac bioprostheses is limited fundamentally by structural failure due to mechanical fatigue and calcification. In the present report, we analyze, using an in vitro hydraulic simulator to test tensile strength, the mechanical behavior of porcine pericardium for the purpose of establishing the criteria for selecting the biomaterial, taking into account both morphological criteria (thickness and homogeneity of the specimens) and mechanical criteria (stress at breaking point), using the epidemiological model of paired samples. The stress at breakage was found to range widely from 24.07 MPa to 100.29 MPa, although we observed no statistically significant differences when comparing the mean results in the different regions and zones of the pericardium being studies. The application of the selection criteria in the present series resulted in an excellent mathematical fit in terms of the stress/elongation (R2 > 0.95), making it possible to establish, by means of linear regression, the prediction of the tensile strength in one zone on the basis of the values observed in its paired specimen.

Myricetin glycosides from Licania densiflora

Dried leaves of Licania densiflora yielded five myricetin glycosides: myricetin 3'-methylether-3-O-glucoside (1), myricetin 3'-methylether-3-O-galactoside (2), myricetin 4'-methylether-3-O-rhamnoside (3), myricetin 3',5'-dimethylether-3-O-glucoside (4), and myricetin 3',5'-dimethylether-3-O-rhamnoside (5). Their structures were elucidated by spectroscopic methods including mono- and bi-dimensional NMR techniques.

Antimicrobial triterpenoids from Licania heteromorpha

Six triterpenoids having a lupane and oleane skeleton were isolated from the leaves and young branches of Licania heteromorpha Bentham var. heteromorpha and were identified as: betulinic acid 1, alphitolic acid 2, 3 beta-O-trans-p-coumaroyl alphitolic acid 3, 3 beta-O-cis-p-coumaroyl alphitolic acid 4, 3 beta-O-trans-p-coumaroyl maslinic acid 5, 3 beta-O-cis-p-coumaroyl maslinic acid 6. The antimicrobial activity of these compounds was evaluated in vitro on clinically isolated microorganisms employing a microdilution method. Compounds 2, 3, 5, and 6 showed antimicrobial activity on Gram-positive bacteria and yeasts, whereas none of the six triterpenoids were active against Gram-negative organisms.

Acute necrotizing Meckel diverticulitis due to biliary enterolithiasis

BACKGROUND

Acute abdominal pain due to complicated Meckel's diverticulum is an unusual event. Even the presence of biliary enterolithiasis at the onset of inflamed congenital diverticulum has rarely been reported previously.

RESULTS

Despite this unusual presentation, an episode of gallstone passage through the biliary tract has not yet been described.

CONCLUSIONS

Whether the stones were primarily formed in the diverticulum as enterolithiasis, or secondary to gallstone passage is discussed. The complications of Meckel's diverticulum requiring surgical treatment are reviewed, focusing on the unusual finding of biliary stones in Meckel's diverticulum and the etiogenic mechanism of enterolithiasis.

Mesigyna once-a-month combined injectable contraceptive: experience in Latin America

A phase III clinical study was carried out among 534 fertile Latin American women to evaluate cycle control, side effects, and contraceptive efficacy of a once-a-month combined injectable, Mesigyna, consisting of 50 mg norethisterone enanthate and 5 mg estradiol valerate. The pregnancy rate at 1 year was 0 per 100 woman-years for a total experience of 4688 woman-months. The overall discontinuation rate at one year was 17.9%. Discontinuation rate for bleeding problems was 5.1%. The Colombian women had a significant increase (p <0.001) in bleeding problems compared to other countries. The discontinuation rate for amenorrhea was 1.1%. There were no significant differences between the groups regarding discontinuation for other medical or non-medical reasons. Mean weight gain after one year of use was 1.02 kg. Mesigyna is an appropiate once-a-month injectable contraceptive for Latin American women since it is highly effective and its perception of normal menstrual bleeding is of importance in the Latin American population.

Molluscicidal and piscicidal activities of Venezuelan Chrysobalanaceae plants

Extracts of increasing polarity of 6 Venezuelan plants belonging to the Chrysobalanaceae family were tested for possible letal toxicity against Biomphalaria glabrata Say, a snail intermediate hosts of Schistosoma mansoni Sambon. The piscicidal toxicity of the active extracts was also evaluated with the aim of findings compounds without toxicity in nontarget organisms, principally fishes and humans.

Influence of dietary energy, supplemental fat and linoleic acid concentration on performance of laying hens at two ages

1. The aim of this study was to investigate the influence of metabolisable energy (ME), supplemental fat (SFAT) and linoleic acid (LIN) content of the diet on the productive performance and weight of eggs and egg components of Isabrown hens of 22 or 74 weeks of age. 2. Six diets were formulated to contain the following concentrations of ME (MJ/kg), SFAT (g/kg) and LIN (g/kg), respectively: A) 11.8, 0 and 11.5; B) 11.8, 40 and 11.5; C) 11.8, 40 and 16.5; D) 11.2, 40 and 16.5; E) 11.2, 40 and 11.5; and F) 11.2, 0 and 11.5. Data were collected for 28 d and analysed using linear contrasts to test the effect of SFAT, LIN, ME and their interactions. 3. When the LIN content of the diets was maintained constant at 11.5 g/kg, an increase in the SFAT from 0 to 40 g/kg increased egg weight (63.8 vs 64.5 g; P<0.05), food intake (119 vs 124 g; P<0.01) and energy intake (1.36 vs. 1.42 MJ/d; P<0.01) and body weight change of the hens (-85 vs. 27 g; P<0.001). Supplemental fat also increased yolk (15.8 vs. 16.3 g; P<0.001) and albumen weight (40.8 vs. 42.3 g; P<0.01) but yolk to albumen ratio was not modified. 4. Egg and albumen weights were improved by SFAT in early but not in late producing hens. As a result, yolk to albumen ratio decreased in the younger hens, from 0.371 to 0.357, but increased in the older hens, from 0.408 to 0.415; P<0.01) with fat addition. 5. An increase in the LIN content of the diets from 11.5 to 16.5 g/kg did not modify any of the traits studied. 6. It was concluded that the LIN requirement of the hens for maximal productivity and weight of eggs is 11.5 g/kg or less. Supplemental fat increased the weight of eggs and albumen in the younger but not in older hens and the beneficial effect was independent of its LIN content.

Laying hen productivity as affected by energy, supplemental fat, and linoleic acid concentration of the diet

A trial using 720 Isabrown hens was conducted to determine the influence of energy (AMEn), supplemental fat (SFAT), and linolenic acid (LIN) concentration of the diet on performance and weight of eggs and egg components throughout the laying cycle (22 to 65 wk of age). There were six treatments whose calculated AMEn, SFAT, and LIN content were, respectively: 1) 2,810 kcal/kg, 0%, 1.15%; 2) 2,810 kcal/kg, 4%, 1.15%; 3) 2,810 kcal/kg, 4%, 1.65%; 4) 2,680 kcal/kg, 0%, 1.15%; 5) 2,680 kcal/kg, 4%, 1.15%; and 6) 2,680 kcal/kg, 4%, and 1.65%. All diets were formulated to have the same crude protein, lysine, TSAA, calcium, and nonphytin phosphorus levels per kilocalorie of AMEn. The data were analyzed with SFAT constant (4%) and AMEn, and LIN variables (Diets 2, 3, 5, and 6) and with LIN constant (1.15%) and AMEn and SFAT variables (Diets 1, 2, 4, and 5). When LIN was maintained at a constant of 1.15%, an increase in the AMEn of the diets from 2,680 to 2,810 kcal/kg decreased feed intake by 4% (P < 0.001). Increasing AMEn also improved feed conversion per dozen eggs and per kilogram of eggs by 4.9 and 4.7% (P < 0.05), respectively, and increased BW gain by 55.7% (P < 0.05). Egg production rate, egg weight, egg mass output, and energy intake were not modified by treatments. An increase in SFAT within both energy levels from 0 to 4% improved all of the traits studied except feed conversion. Supplemental fat increased both yolk and albumen weight, but the effect was more pronounced on the latter. When SFAT was maintained constant at 4%, an increase in AMEn of the diets decreased feed intake and improved feed conversion per dozen and per kilogram of eggs by 5.7, 5.5, and 5.2%, respectively (P < 0.001). An increase in LIN content from 1.15 to 1.65% did not modify any of the parameters studied. The results indicate that SFAT consistently improves productivity of hens and egg weight and that the LIN requirement for maximal productivity is 1.15% or less. The beneficial effects of adding SFAT to diets containing more than 1.15% LIN are due to the fat itself rather than to an increase in LIN or AMEn of the diet.

Congenital transmission of experimental chronic toxoplasmosis in rats

A 10% transplacental transmission rate was observed in litters from 89 Wistar rats chronically infected with Toxoplasmosis gondii, as judging from bioassays. The rats had been fed T. gondii 2 mo prior to mating. Six of 7 isolates of T. gondii were transplacentally transmitted. The frequency of transmission did not appear to be affected by the strain of T. gondii or the size of the inoculum.

Differential coupling of serotonin 5-HT1A and 5-HT1B receptors to activation of ERK2 and inhibition of adenylyl cyclase in transfected CHO cells

Although the subtypes of serotonin 5-HT1 receptors have distinct structure and pharmacology, it has not been clear if they also exhibit differences in coupling to cellular signals. We have sought to compare directly the coupling of 5-HT1A and 5-HT1B receptors to adenylyl cyclase and to the mitogen-activated protein kinase ERK2 (extracellular signal-regulated kinase-2). We found that 5-HT1B receptors couple better to activation of ERK2 and inhibition of adenylyl cyclase than do 5-HT1A receptors. 5-HT stimulated a maximal fourfold increase in ERK2 activity in nontransfected cells that express endogenous 5-HT1B receptors at a very low density and a maximal 13-fold increase in transfected cells expressing 230 fmol of 5-HT1B receptor/mg of membrane protein. In contrast, activation of 5-HT1A receptors stimulated only a 2.8-fold maximal activation of ERK2 in transfected cells expressing receptors at 300 fmol/mg of membrane protein but did stimulate a 12-fold increase in activity in cells expressing receptors at 3,000 fmol/mg of membrane protein. Similarly, 5-HT1A, but not 5-HT1B, receptors were found to cause significant inhibition of forskolin-stimulated cyclic AMP accumulation only when expressed at high densities. These findings demonstrate that although both 5-HT1A and 5-HT1B receptors have been shown to couple to G proteins of the Gi class, they exhibit differences in coupling to ERK2 and adenylyl cyclase.

Plasmapheresis with intravenous immunoglobulin G is effective in patients with elevated panel reactive antibody prior to cardiac transplantation

BACKGROUND

Patients with a PRA >10% are considered to be at greater risk for the development of not only acute cellular and humoral rejection but also increased mortality when compared to nonsensitized patients following transplantation. All patients with a PRA >10% at our institution are treated with plasmapheresis and intravenous immunoglobulin G immediately prior to cardiac transplantation.

METHODS

Sixteen (Group 1) of 118 patients awaiting cardiac transplantation were found to be sensitized. These patients underwent plasmapheresis followed by 20 gm of intravenous immunoglobulin G (IVIG) immediately prior to cardiac transplantation. Group 1 was compared to the remaining 102 patients with a PRA <10% (Group 2).

RESULTS

Despite more patients in Group 1 having a positive crossmatch, pulmonary hypertension, and requiring mechanical circulatory support, there was no statistically significant difference in length of stay or mortality at a mean follow-up of 21.6+/-15.0 months. There was no difference in the occurrence of mild, moderate or severe cellular rejection or humoral rejection in these sensitized patients when compared to Group 2.

CONCLUSIONS

Pretransplant plasmapheresis followed by intravenous immunoglobulin G may be an effective therapy that obviates the need for a prospective crossmatch and allows sensitized patients to undergo cardiac transplantation. There is no increase in the post transplant length of stay, occurrence of rejection or short term mortality. Long term follow up is necessary to evaluate whether there is a difference in the development of late rejection, transplant vasculopathy and survival.