Vertical transmission and pathological findings in the mother, the placenta and the offspring, during first and last thirds of gestation in a mouse model of congenital toxoplasmosis.

We performed a study of congenital toxoplasmosis of the first and third gestation periods in mice, and determined its effects on the embryos/fetuses, the placentae and the maternal organs. We infected pregnant BALB/c mice by i.v. injection of 2.5--10.0 × 106 tachyzoites of the ME49 T. gondii strain and euthanized them 72 h later. The tissues were analyzed by histopathology, immunohistochemistry and parasite-specific qPCR. Infections with the lowest dose induced remarkably different changes in the two thirds: a) all doses diminished the number of products/litter, the lowest dose only by 14%; but most embryos still visible were degenerated in the case of the first period, while the fetuses of the last third were perfectly preserved; b) the transmission rate in the first third was relatively high, but with a very low parasite burden; c) with the lowest dose, strong vascular changes (congestion, thrombosis and hemorrhage) predominated in the placentas of the first period, while they were absent in the last third; d) necrosis caused by T. gondii to maternal organs was much stronger during the last gestation period than in the first. Our results suggest that the vascular alterations at the placenta of the first third of pregnancy prevent embryo from large parasite burden, but provoke its death by starvation. In the last gestation period, there was poor control of parasite dissemination to the placenta and the fetus, but there was greater capacity of the product to defend itself from T. gondii.

Influence of antimicrobial photodynamic therapy with different pre-irradiation times on children's dental biofilm: randomized clinical trial.

PURPOSE: Photodynamic therapy (PDT) is effective in reducing pathogenic microorganisms in the oral cavity and in preventing dental diseases. This study evaluated the pre-irradiation time using PDT (diode laser associated with 0.01% methylene blue) to decrease the number of microorganisms in the visible plaque in permanent teeth. METHODS: This randomized clinical trial included 108 homologous lower permanent first molars (36 and 46) with biofilm from 54 children aged six to 12 years. PDT was performed (0.01% methylene blue photosensitizer/therapeutic laser-InGaAIP), according to the following protocols: Group 1, biofilm collection of the distal area of the lingual surface of 36 µm before PDT; group 2, mesial area of the lingual surface of 36 µm 1 min after PDT; group 3, area of the lingual surface of 46 µm before PDT; and group 4, mesial area of the lingual surface of 46 µm 5 min after PDT. RESULTS: After statistical analysis, significant differences were observed between the groups (p = 0.000). In groups 2 and 4, the number of bacteria tended to decrease, with a more evident bacterial reduction in group 4. CONCLUSIONS: Pre-irradiation reduced the number of colony-forming units of mature bacterial biofilms in vivo. A time of 5 min resulted in a greater reduction in the number of colony-forming units. CLINICAL TRIAL REGISTRATION: ReBEC Identifier: RBR-6bqfp3; Date of Register: March 2nd, 2020. Retrospectively Registered.

Is Toxoplasma gondii type related to clinical outcome in human congenital infection? Systematic and critical review.

In human congenital toxoplasmosis the effects of parasite burden and pregnancy time at infection on clinical outcome are well known, but there is controversy regarding the role of Toxoplasma gondii type. Through a systematic review of the literature, we aimed to discern if T. gondii type has a role on clinical outcome in human congenital toxoplasmosis. We built up a database of congenital toxoplasmosis from reports of cases, case series and screening-based cohorts, which had information about parasite type, gestation time at maternal infection and/or clinical outcome in the product. Then, we obtained frequencies for loci used to genotype geographical origin of cases and types found. Also, odds ratios were calculated for association between time of maternal infection or parasite type on outcome. Type II parasites were the most common in Europe, Asia and Africa, while in America there were mainly atypical strains. More newborns with clinical problems were born from mothers infected during the first half of gestation than from those acquiring the parasite after week 24, regardless of parasite genotype (92.9 vs. 16.1 %, OR = 67.9, CI95 25.4-181.6). Type I and atypical parasites were associated with clinical problems as opposed to types II and III, regardless of pregnancy period at infection (86.9 vs. 72.9 %, OR = 2.47, CI95 1.1-5.4). A significant and remarkable tendency of type I parasites to be present during early pregnancy was also observed (94.4 vs. 5.6 %, P < 0.009). In addition to parasite burden and period of gestation, T. gondii genotype seems involved in CT clinical outcome.

Mouse model of congenital infection with a non-virulent Toxoplasma gondii strain: Vertical transmission, "sterile" fetal damage, or both?

Congenital transmission of Toxoplasma gondii may occur if the mother gets infected for the first time while pregnant. The risk of mother-to-child transmission depends on the gestation trimester at infection, being lowest in the first and highest in the last. Conversely, fetal damage is frequent and more severe at the beginning of pregnancy. The objective of this study was to evaluate congenital transmission and pathological aspects in the placenta and the fetus using a mouse model of congenital infection of the second gestation third. Forty-five female BALB/c mice were infected intravenously with 2.5-10.0 × 10(6) tachyzoites of the ME49 strain at middle gestation. Samples of maternal spleen and fetal/placental units were taken 72 h later. We determined parasite load and vertical transmission by qPCR, as well as damage macroscopically and by histopathology. With the lowest dose, 18% of the fetuses were infected. Also, 40% of fetuses/litter were altered, while this value was 10% in the control group (P < 0.05). These results are similar to those described in humans in terms of vertical transmission and fetal damage during the second third of gestation. The maternal spleen had 10-1000 times more tachyzoites than the placenta, and the later retained 90-99% of the parasites that could reach the fetus. Nevertheless, we found resorptions, abortions or fetal tissue damage in the presence but also in the absence of parasites. Our data indicate a strong protective effect of maternal organs and the placenta against fetal infection, but extensive damage of the later may led to resorption or abortion without vertical transmission.

Frequency of Toxoplasma gondii in pork meat in Ocotlán, Jalisco, Mexico.

Toxoplasmosis is an infection caused by Toxoplasma gondii, an intracellular obligate parasite. Its transmission has usually been attributed to ingestion of undercooked or raw meat. The frequency of T. gondii in pork, the most common meat for human consumption in Jalisco, Mexico, is unknown; in Guadalajara city high prevalence of human toxoplasmosis has been documented. Forty-eight samples of pork meat from butcher shops in Ocotlán city were analyzed. Through bioassay, 50 g of tissue was homogenized in an acidic pepsin solution and inoculated subcutaneously to previously immunosuppressed mice. Blood samples from the mice tail vein were obtained before inoculation and 7, 14, 28, and 45 days postinoculation to analyze anti-Toxoplasma immunoglobulin (Ig) M and IgG antibody kinetics by indirect enzyme-linked immunosorbent assay. For histopathology, small fragments of the brain, lungs, heart, and skeletal muscle were extracted on day 45 and were stained with hematoxylin and eosin. Also, DNA was extracted from the pork meat for PCR amplification of the B1 gene. Even though all pork samples were negative by histopathology and PCR, IgG and IgM antibodies against T. gondii were detected in 1 of the 48 inoculated mice, reflecting a frequency of 2.1% positive pork meat, which is lower than expected but similar to that found in other regions.

Congenital toxoplasmosis: candidate host immune genes relevant for vertical transmission and pathogenesis.

Toxoplasma gondii infects a variety of vertebrate hosts, including humans. Transplacental passage of the parasite leads to congenital toxoplasmosis. A primary infection during the first weeks of gestation causes vertical transmission at low rate, although it causes major damage to the embryo. Transmission frequency increases to near 80% by the end of pregnancy, but the proportion of ill newborns is low. For transmission and pathogenesis, the parasite genetics is certainly important. Several host innate and adaptative immune response genes are induced during infection in adults, which control the rapidly replicating tachyzoite. The T helper 1 (Th1) response is protective, although it has to be modulated to avoid inflammatory damage. Paradoxical observations on this response pattern in congenital toxoplasmosis have been reported, as it may be protective or deleterious, inducing sterile abortion or favoring parasite transplacental passage. Regarding pregnancy, an early Th1 microenvironment is important for control of infectious diseases and successful implantation, although it has to be regulated to support trophoblast survival. Polymorphism of genes involved in these parallel phenomena, such as Toll-like receptors (TLRs), adhesins, cytokines, chemokines or their receptors, immunoglobulins or Fc receptors (FcRs), might be important in susceptibility for T. gondii vertical transmission, abortion or fetal pathology. In this study some examples are presented and discussed.

Congenital and acquired toxoplasmosis: diversity and role of antibodies in different compartments of the host.

The apicomplexan parasite Toxoplasma gondii is remarkable in several aspects, since it is a protozoan that infects most nucleated cells in many warm-blooded animals, worldwide. Although the cellular immune response against T. gondii is critical for infection control, antibodies may either enhance or block protective mechanisms, and even mediate immunological damage, directly or indirectly. Since cytokines regulate the class/subclass switch, antibodies may also be the biomarkers of protective or pathological cellular immune events. There is a scientific and clinical interest in the presence of natural and autoreactive antibodies, as well as in the 'chronic' immunoglobulin M (IgM) response and the post-treatment 'rebound'. Another interesting aspect is compartmentalization; certain immunoglobulins may uniquely be found in specific host fluids. Local synthesis has been demonstrated, but antibodies may also traverse several cell layers, like the blood-brain and haemato-ocular barriers, and the placenta. In some instances, Fc receptors (FcRs) facilitate transport and may even have a concentrator effect, which can be related to resistance or pathology. These aspects of the humoral response against T. gondii are reviewed in the present paper.

Low-risk human papillomavirus types 6 and 11 associated with carcinomas of the genital and upper aero-digestive tract.

BACKGROUND: Human papillomavirus (HPVs) types 6 and 11, are frequently found in non-malignant anogenital condylomas and laryngeal papillomas. However, in an ongoing epidemiological study in Argentina in which 163 anogenital and aero-respiratory cancer biopsies were analyzed, several cases infected with low-risk HPVs could be detected. METHODS: Tumor samples were analyzed by Southern blot hybridization, using HPVs 6, 11, 16, 18, 30, 31, 33 and 35 as probes, and polymerase chain reaction (PCR) with type-specific primers and probes. RESULTS: Four invasive carcinomas containing HPV 6 or 11 could be detected (2.4%) by Southern blot technique. HPV 6 DNA was found in a penile carcinoma, a groin carcinoma, and in a tonsillar carcinoma. One cervical carcinoma harbored HPV 11 DNA. Using HPVs 6, 11, 16, 18 and 33 anticontamination primers and probes in PCR, no additional high-risk HPV types could be detected in these four cancers. CONCLUSION: This report shows the presence of low-risk HPVs (HPV 6 and 11) associated to malignant tumors in a frequency higher than usually observed. The data raise questions about which are the circumstances which may favor low-risk HPV related oncogenesis.

Using soft vinyl stents to facilitate augmentation of maxillary anterior atrophic ridges with hydroxyapatite.

A technique has been described for fabrication of a surgical template made of soft vinyl mouthguard material. Use of this stent at the time of surgery can be of great value to the oral surgeon and the prosthodontist. The risk of excessive augmentation and migration of the particulate hydroxyapatite to an undesired area will be minimized if the stent is used as a matrix. Uniform results in size and form of the ridge can be obtained from the surgical procedure when the stent is used. The denture-bearing area of the maxillary anterior ridge will improve significantly, enabling the dentist to make a maxillary complete denture.