The Salivary Mycobiome Contains 2 Ecologically Distinct Mycotypes.

A broad range of fungi has been detected in molecular surveys of the oral mycobiome. However, knowledge is still lacking on interindividual variability of these communities and the ecologic and clinical significance of oral fungal commensals. In this cross-sectional study, we use internal transcribed spacer 1 amplicon sequencing to evaluate the salivary mycobiome in 59 subjects, 36 of whom were scheduled to receive cancer chemotherapy. Analysis of the broad population structure of fungal communities in the whole cohort identified 2 well-demarcated genus-level community types (mycotypes), with Candida and Malassezia as the main taxa driving cluster partitioning. The Candida mycotype had lower diversity than the Malassezia mycotype and was positively correlated with cancer and steroid use in these subjects, smoking, caries, utilizing a removable prosthesis, and plaque index. Mycotypes were also associated with metabolically distinct bacteria indicative of divergent oral environments, with aciduric species enriched in the Candida mycotype and inflammophilic bacteria increased in the Malassezia mycotype. Similar to their fungal counterparts, coexisting bacterial communities associated with the Candida mycotype showed lower diversity than those associated with the Malassezia mycotype, suggesting that common environmental pressures affected bacteria and fungi. Mycotypes were also seen in an independent cohort of 24 subjects, in which cultivation revealed Malassezia as viable oral mycobiome members, although the low-abundance Malassezia sympodialis was the only Malassezia species recovered. There was a high degree of concordance between the molecular detection and cultivability of Candida, while cultivation showed low sensitivity for detection of the Malassezia mycotype. Overall, our work provides insights into the oral mycobiome landscape, revealing 2 community classes with apparently distinct ecologic constraints and specific associations with coexisting bacteria and clinical parameters. The utility of mycotypes as biomarkers for oral diseases warrants further study.

Meningioma: the role of a foreign body and irradiation in tumor formation.

A case of meningioma is reported. At the age of 18 years, the patient had undergone insertion of a Torkildsen shunt through a posteroparietal burr hole for obstructive hydrocephalus secondary to a tumor of the pineal region, of which no biopsy had been made. After the hydrocephalus was relieved, he underwent irradiation of the tumor. Thirty years later, he was treated for an intracranial meningioma wrapped around the shunt. The tumor followed the shunt in all of its intracranial course. Microscopy disclosed pieces of the shunt tube within the meningioma. The role of a foreign body and irradiation in the induction of meningiomas is discussed, and a comprehensive review of the literature is presented.

Differing stem cell self-renewal of lectin-separated murine bone marrow fractions.

The success of bone marrow transplantation depends not only on the engraftment of adequate numbers of hematopoietic stem cells but also on their self-renewal capacity, which must be sufficient to provide lifetime hematopoiesis. The lectin peanut agglutinin (PNA), when exposed to bone marrow, causes separation into two distinct fractions. The agglutinated fraction not only is enriched with colony-forming units--spleen but also is devoid of graft-versus-host (GVH) activity when injected into allogeneic lethally irradiated recipients, and therefore, it is considered to be an ideal source for bone marrow transplantation. The absence of GVH activity is presumably due to the separation of mature thymocytes into the nonagglutinated fraction and functionally immature thymocytes into the agglutinated fraction. Although there has been speculation that immature hematopoietic stem cells also selectively bind to PNA, other evidence suggests that the relationship of lectin binding specificity to level of maturity varies in different tissues. This study was performed to assess the self-renewal capacity of lectin-separated bone marrow stem cells. Results indicate that the self-renewal of the agglutinated fraction is significantly lower than that of the unfractionated bone marrow; such self-renewal of the nonagglutinated fraction is higher. This is further evidence for the heterogeneity of the stem cell pool. Stem cell enrichment should not be the goal in bone marrow transplantation; rather, the goal should be utilization of stem cells with the greatest self-renewal potential.

Reversible brachial plexopathy following primary radiation therapy for breast cancer.

Reversible brachial plexopathy has occurred in very low incidence in patients with breast carcinoma treated definitively with radiation therapy. Of 565 patients treated between January 1968 and December 1979 with moderate doses of supervoltage radiation therapy (average axillary dose of 5000 rad in 5 weeks), eight patients (1.4%) developed the characteristic symptoms at a median time of 4.5 months after radiation therapy. This syndrome consists of paresthesias in all patients, with weakness and pain less commonly seen. The symptom complex differs from other previously described brachial plexus syndromes, including paralytic brachial neuritis, radiation-induced injury, and carcinoma. A possible relationship to adjuvant chemotherapy exists, though the etiology is not well-understood. The cases described demonstrate temporal clustering. Resolution is always seen.