Clonogenic analysis reveals reserve stem cells in postnatal mammals: I. Pluripotent mesenchymal stem cells

Clonal populations of lineage-uncommitted pluripotent mesenchymal stem cells have been identified in prenatal avians and rodents. These cells reside in the connective tissue matrices of many organs and tissues. They demonstrate extended capabilities for self-renewal and the ability to differentiate into multiple separate tissues within the mesodermal germ line. This study was designed to determine whether such cells are present in the connective tissues of postnatal mammals. This report describes a cell clone derived by isolation from postnatal rat connective tissues, cryopreservation, extended propagation, and serial dilution clonogenic analysis. In the undifferentiated state, this clone demonstrates a high nuclear-to-cytoplasmic ratio and extended capacity for self-renewal. Subsequent morphological, histochemical, and immunochemical analysis after the induction of differentiation revealed phenotypic markers characteristic of multiple cell types of mesodermal origin, such as skeletal muscle, smooth muscle, fat cells, cartilage, and bone. These results indicate that this clone consists of pluripotent mesenchymal stem cells. This report demonstrates that clonal populations of reserve stem cells are present in mammals after birth. Potential roles for such cells in the maintenance, repair, and regeneration of mesodermal tissues are discussed.

The response of symptomatic neurosyphilis to high-dose intravenous penicillin G in patients with human immunodeficiency virus infection

BACKGROUND

Infection with the human immunodeficiency virus (HIV) may affect both the natural course of syphilis and the response to treatment. We examined the response to treatment with high-dose penicillin G in HIV-infected patients with symptomatic neurosyphilis.

METHODS

Neurosyphilis was defined by reactivity in serum treponemal tests for syphilis, neurologic manifestations consistent with neurosyphilis, and a positive Venereal Disease Research Laboratory (VDRL) test on cerebrospinal fluid. We identified 11 HIV-infected patients with symptomatic neurosyphilis; 5 had been treated previously for early syphilis with penicillin G benzathine. Patients were treated with 18 million to 24 million units of penicillin G per day administered intravenously for 10 days. Cerebrospinal fluid was examined approximately 6 and 24 weeks after treatment, when the polymerase chain reaction and rabbit inoculation were used to detect Treponema pallidum.

RESULTS

In four of the seven patients studied 24 weeks after treatment, the serum titers on rapid plasma reagin (RPR) testing decreased by at least two doubling dilutions, and four patients had reductions in the cerebrospinal fluid titers on VDRL testing or reverted to nonreactive results. In two patients there was no normalization or improvement in serum titers on RPR testing or cerebrospinal fluid titers on VDRL testing, cell counts, or protein concentrations. One patient relapsed with meningovascular syphilis six months after therapy. T. pallidum was detected by the polymerase chain reaction in cerebrospinal fluid from 3 of 10 patients before treatment, but in none of the 10 post-treatment specimens.

CONCLUSIONS

In patients with early syphilis who are also infected with HIV, therapy with penicillin G benzathine may fail, and neurosyphilis may develop. The regimen of high-dose penicillin recommended for neurosyphilis is not consistently effective in patients infected with HIV.

Osteomyelitis of the sternum caused by Apophysomyces elegans

Apophysomyces elegans, a member of the family Mucoraceae, was found to infect the chest wall and sternum of an immunocompetent man following minor trauma. As in previous cases, amphotericin B therapy alone was inadequate. Extensive surgical debridement was required in order to eradicate the infection.