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).     

Gay Community Involvement and Condomless Anal Sex Among Sexual Minority Men in the USA

Archives of Sexual Behavior - Sexual minority men (SMM) remain disproportionately burdened by sexually transmitted infections. Although gay community involvement has been theorized to be protective...     

Genotypic and phenotypic alterations of p53 in head and neck squamous-cell carcinoma

p53 is the most frequently altered suppressor gene in human cancers. The genotypic and corresponding phenotypic abnormalities of this gene in head and neck squamous cell carcinoma (HNSCC) remain undefined. We analyzed the loss of heterozygosity (LOH) by restriction fragment length polymorphism (RFLP) at three polymorphic loci in the p53 gene and performed immunohistochemistry (MC) for its protein on paraffin-embedded tumor tissue from 20 previously sequenced tumor specimens. LOH was noted at one or more of the three polymorphic sites within the p53 gene in 12 (67%) of the 18 informative samples. Concordance between LOH and mutations was observed in 14 (78%) cases. Twelve (60%) tumors with point mutations were immunohistochemically reactive to p53 antibody and two (10%) lacked both genetic and immunohistochemical alterations. In six tumors (30%) contradictory results between immunohistochemistry and molecular analysis were observed. Our data indicate that: (i) simultaneous deletion and mutation of both p53 alleles was observed in the majority of head and neck squamous carcinomas and implicate this gene in the oncogenesis of these neoplasms, (ii) p53 immunohistochemical analysis may not fully account for the different molecular alterations of this gene, and (iii) no correlation between p53 abnormalities and clinicopathologic or DNA content characteristics of HNSCC was found.     

Bilateral macular hemorrhage after laser in situ keratomileusis

· Background: This is the first report of a bilateral submacular hemorrhage after LASIK surgery in an extreme myo pic patient. A 31-year-old man underwent bilateral surgery for correction of –16.75+0.75×70° and –16.50+0.50×55°. · Methods: Case report. · Results: One day after surgery the patient’s uncorrected visual acuity was in the 20/50 range OU and by 17 days after surgery his visual acuity had declined to 20/200 range. Fundus examination showed multifocal subretinal macular and posterior pole hemorrhages. Fluorescein angiography showed some macular lesions compatible with lacquer cracks. · Conclusions: Preoperative and postoperative fundus examination is important to detect this phenomenon. Patients should be informed of this rare complication. Received: 2 June 1998 Revised version received: 16 November 1998 Accepted: 17 November 1998     

AZATHIOPRINE INDUCED BONE MARROW SUPPRESSION IN LIVE RELATED RENAL ALLOGRAFT RECIPIENTS

Over a follow-up period of 6 years, 4 out of 31 live related renal allograft recipients (12.9%) developed azathioprine induced bone marrow suppression. Presentation in 3 patients was with fever and 2 patients also had associated graft dysfunction. All patients had leucopenia, 2 patients in addition had anaemia and one patient had pancytopenia. Bone marrow suppression developed 9.6 months (3.5-16.0 months) following transplantation and recovery followed over a period of 30 (18-49 days) days after withdrawal of the drug. One patient succumbed during the phase of bicytopenia.KEY WORDS: Azathioprine, Bone marrow suppression, Kidney transplantation     

Morphological characterisation of BGM (Buffalo Green Monkey) cell line exposed to low doses of cadmium chloride.

Morphological changes in the Buffalo Green Monkey (BGM) cell line after exposure to a subcytotoxic dose (0.062 mM, equivalent to EC(10)-effective concentration 10%) of cadmium chloride have been evaluated. Cells were exposed for 24 h and the effects observed at the ultrastructural level by transmission and scanning microscopy. Using transmission electron microscopy, the most notable findings in treated cells were the presence of intranuclear inclusion bodies and thin intracytoplasmic granules associated to myelin figures and the presence of apoptotic bodies. Other morphological alterations included cell vacuolisation and a reduced cytoplasm volume, condensation of the mitochondria and a decreased number of cytoplasmic organelles, except lysosomes and autophagic vacuoles, which increased in number. Scanning electron microscopy pointed to a cell with a disrupted perinuclear region and a decrease in the number of surface microvilli. We conclude that the BGM cell line may be considered an useful tool for toxicological studies involving cadmium.