Components of the Gut Microbiome That Influence Bone Tissue-Level Strength

Modifications to the constituents of the gut microbiome influence bone density and tissue-level strength, but the specific microbial components that influence tissue-level strength in bone are not known. Here, we selectively modify constituents of the gut microbiota using narrow-spectrum antibiotics to identify components of the microbiome associated with changes in bone mechanical and material properties. Male C57BL/6J mice (4 weeks) were divided into seven groups (n = 7-10/group) and had taxa within the gut microbiome removed through dosing with: (i) ampicillin; (ii) neomycin; (iii) vancomycin; (iv) metronidazole; (v) a cocktail of all four antibiotics together (with zero-calorie sweetener to ensure intake); (vi) zero-calorie sweetener only; or (vii) no additive (untreated) for 12 weeks. Individual antibiotics remove only some taxa from the gut, while the cocktail of all four removes almost all microbes. After accounting for differences in geometry, whole bone strength was reduced in animals with gut microbiome modified by neomycin (-28%, p = 0.002) and was increased in the group in which the gut microbiome was altered by sweetener alone (+39%, p < 0.001). Analysis of the fecal microbiota detected seven lower-ranked taxa differentially abundant in animals with impaired tissue-level strength and 14 differentially abundant taxa associated with increased tissue-level strength. Histological and serum markers of bone turnover and trabecular bone volume per tissue volume (BV/TV) did not differ among groups. These findings demonstrate that modifications to the taxonomic components of the gut microbiome have the potential to decrease or increase tissue-level strength of bone independent of bone quantity and without noticeable changes in bone turnover. © 2021 American Society for Bone and Mineral Research (ASBMR).

Plasma membrane glycoproteins during spermatogenesis and in spermatozoa of some fishes

Plasma membrane glycoproteins were analyzed during spermatogenesis and in the spermatozoa of the teleost fish Xiphophorus maculatus and of the Elasmobranch Schroederichthys chilensis. The analysis was undertaken using the fluoresceinated lectins concanavalin A (ConA) and wheat germ agglutinin (WGA) to detect glycoproteins in the plasma membrane using confocal laser microscopy. In Xiphophorus, a species with acrosomeless spermatozoa, primary spermatocytes and rounded shaped spermatids showed that the whole cell surface was labeled by both lectins. As spermiogenesis proceeded surface glycoproteins diminished and in mature spermatozoa a discrete and non-random localized fluorescence was observed exclusively on the surface of the spermatozoon head after the employ of ConA and WGA. In the elasmobranch Schroederichthys chilensis the spermatozoon displays an acrosome as a small vesicle. After ConA and WGA labeling, the region of the plasma membrane that covers the acrosome was the only fluorescent region in the gamete. The physiological significance of plasma membrane glycoproteins is discussed regarding spermatozoon physiology.

Klippel-Trenaunay-Weber syndrome presenting as massive lymphangiohemangioma of the thigh: prenatal diagnosis

We report a case of Klippel-Trenaunay-Weber syndrome presenting prenatally as a massive congenital lymphangiohemangioma of the thigh. Routine ultrasonographic examination revealed multiple distorted cystic areas extending from the right flank through the right lower extremity of a 30-week fetus. A diagnosis of cystic lymphangioma of the thigh was suspected prenatally. Neonatal evaluation confirmed the prenatal findings. Neonatal color Doppler imaging revealed blood vessels within the tumor. The differential diagnosis is discussed together with available therapeutic procedures.

Relationship between DNA methylation and cell proliferation in Trypanosoma cruzi

5-Azacytidine treatment of T. cruzi epimastigotes in culture induces active cell proliferation. This effect was detected as an increase in the cell number and [3H-methyl]thymidine incorporation into DNA. 5-Azacytidine does not alter other metabolic parameters. We have previously demonstrated that 5-azacytidine induces DNA hypomethylation in T. cruzi. Accordingly, we suggest that this chemical modification may be related to the control of T. cruzi cell division.

DNA methylation in Trypanosoma cruzi

DNA isolated from the protozoan Trypanosoma cruzi has been found to contain 5-methylcytosine. Analysis of T. cruzi DNA by both HpaII and MspI restriction endonucleases suggests that the sequence -CCGG- is not methylated. Probably T. cruzi DNA also contains N6-methyladenine. This report constitutes the first clear demonstration of the presence of methylated bases in the nuclear DNA from trypanosomes.