FURTHER STUDIES ON IMMUNITY IN EXPERIMENTAL CRYPTOCOCCOSIS

Following infection with 10³ cells of Cryptococcus neoformans, progressive multiplication occurred in all tissues for 7 to 28 days. Thereafter, most mice gained control of the infection so that 3 to 6 months after inoculation, tissues were usually sterile or contained only small numbers of cryptococci. Survivors challenged 1 to 4 months after infection with 10³ cells lived longer than controls and had an increased survival rate. Pretreatment with bacterial endotoxin also resulted in protection against cryptococcal challenge. Endotoxin-protected animals showed no ability to limit the infection until circulating antibody could be demonstrated. Histologic studies revealed an increased cellular infiltration in the brains of specifically protected and endotoxin-protected mice 1 to 2 weeks after challenge. However, control of cryptococcal multiplication could be correlated with the presence of antibody but could not be correlated with the enhanced cellular response. Although protection against cryptococcal challenge appears to be antibody-dependent, it is unclear whether protective antibody is to be found in plasma or is tissue-bound.

Chondromalacia patellae: an in vitro study. Comparison of MR criteria with histologic and macroscopic findings

OBJECTIVE

To develop MR criteria for grades of chondromalacia patellae and to assess the accuracy of these grades.

DESIGN

Fat-suppressed T2-weighted double-echo, fat-suppressed T2-weighted fast spin echo, fat-suppressed T1-weighted, and gradient echo sequences were performed at 1.5 T for the evaluation of chondromalacia. A total of 1000 MR, 200 histologic, and 200 surface locations were graded for chondromalacia and statistically compared.

RESULTS

Compared with gross inspection as well as with histology the most accurate sequences were fat-suppressed T2-weighted conventional spin echo and fat suppressed T2-weighted fast spin echo, although the T1-weighted and proton density images also correlated well. The most accurate MR criteria applied to the severe grades of chondromalacia, with less accurate results for lesser grades.

CONCLUSIONS

This study demonstrates that fat-suppressed routine T2-weighted and fast spin echo T2-weighted sequences seem to be more accurate than proton density, T1-weighted, and gradient echo sequences in grading chondromalacia. Good histologic and macroscopic correlation was seen in more severe grades of chondromalacia, but problems remain for the early grades in all sequences studied.

Thickness of patellofemoral articular cartilage as measured on MR imaging: sequence comparison of accuracy, reproducibility, and interobserver variation

OBJECTIVE

Since the thickness of cartilage is an important indicator of the status, progression and response to therapy of articular disorders, assessment of it is desirable. This study was undertaken to assess the accuracy, precision, and reliability of magnetic resonance (MR) measurements of articular cartilage.

METHODS

Fifteen cadaveric patellas were imaged in the axial plane at 1.5 T. Gradient echo and fat-suppressed FSE, T2-weighted, proton density, and T1-weighted sequences were performed. We measured each 5-mm section separately at three standardized positions, giving a total of 900 measurements. These findings were correlated with independently performed measurements of the corresponding anatomic sections. A hundred random measurements were also evaluated for reproducibility and interobserver variation.

RESULTS

Although all sequences were highly accurate (range r = 0.78-0.82), the T1-weighted images were the most accurate, with a mean difference of 0.25 mm and a correlation coefficient of 0.85. All sequences were also highly reproducible (mean difference between -0.09 and 0.05 mm) with little inter-observer variation (mean difference -0.04 and 0.11 mm). In an attempt to improve the accuracy of the MR measurements further, we retrospectively evaluated all measurements with discrepancies greater than 1 mm from the specimen. All these differences were attributable to focal defects causing exaggeration of the thickness on MR imaging.

CONCLUSION

MR imaging is accurate, precise, and reliable as a basis for measuring articular cartilage and may potentially be usable to monitor progression of articular disorders. Care must be taken not to overestimate the thickness of areas with surface defects.

Periarticular hyperostosis and renal disease in six black lemurs of two family groups

Proliferative periosteal disease was identified in 6 black lemurs (Eulemur macaco macaco) of 2 family groups. Bilaterally symmetric formation of periosteal new bone at the metaphyseal regions of major long bones was first detected at the stifle and tarsal areas and was detected later at the carpal areas. Bony changes were accompanied by progressive renal disease. The syndrome progressed for 6 to 16 months before the lemurs were euthanatized because of debility. Necropsy revealed changes confined to the skeleton and kidneys. Formation of new bone was detected at all affected joints, and chronic renal disease was evident in each lemur. A specific cause was not identified. Although indistinguishable histologically from hypertrophic osteoarthropathy, several important differences were apparent. Distribution of the periosteal new bone was in the metaphyseal rather than diaphyseal areas. Thoracic or gastrointestinal lesions, typically seen with hypertrophic osteoarthropathy, were not detected, and substantial renal disease was evident. A genetic component may be involved in the development of this condition.

The histopathology of fibrodysplasia ossificans progressiva. An endochondral process

In order to better characterize the biological features of fibrodysplasia ossificans progressiva, we reviewed the histopathological specimens from eleven patients (twelve biopsies) who had a confirmed diagnosis of the disease. All of the biopsies had been performed in children, to exclude the diagnosis of a malignant lesion. In no instance was the diagnosis of fibrodysplasia ossificans progressiva considered before the biopsy. The results of a lesional biopsy in all eleven patients revealed normal endochondral osteogenesis at heterotopic sites. The results of biopsy of an early lesion in six children were misinterpreted as revealing a diagnosis of fibromatosis or sarcoma before the roentgenographic appearance of ossification. Immunohistochemical studies of sections of the earliest lesion demonstrated S-100 antigen positivity before the histological appearance of differentiated osteochondral tissue. The presence of congenital malformation of the great toes and of postnatal heterotopic endochondral osteogenesis strongly suggests that fibrodysplasia ossificans progressiva is a disorder of defective induction of endochondral osteogenesis. This study established the predominant histopathological findings associated with fibrodysplasia ossificans progressiva and can serve as a basis for postulation of a candidate gene in the pathogenesis of the disorder. A lesional biopsy is not needed to make the diagnosis; biopsy uniformly exacerbates the condition and should be avoided.

ras p21 expression in the progression of breast cancer

The differential expression of the ras oncogene product p21 in the primary tumor, regional nodes, and distant metastatic sites in patients with disseminated breast cancer was examined to define the biologic and clinical significance of the ras oncogene in the progression of breast cancer. The avidin-biotin peroxidase complex method was used on formalin-fixed, paraffin-embedded tissues from 16 patients with metastatic disease. The primary antibody used in this protocol was RAP-5, an anti-p21 murine monoclonal IgG2a. p21 antigen staining was similar in the primary tumor and regional nodes from the same patient (P less than 0.05), but the staining of distant metastases was more variable. Expression of ras p21 was consistently increased in invasive components of the primary tumor as compared with intraductal tumor. In addition, a high level of p21 expression was seen in tumor emboli in lymphatics and blood vessels as compared with contiguous tumor in parenchymal tissue. Although p21 staining is present in aggressive primary breast cancers and most metastatic sites, our findings indicate that markedly enhanced p21 expression is associated with the earlier stages (invasion and dissemination) of aggressive breast cancers.

Expression of ras oncogene p21 in prostate cancer

The major neoplastic transformation-inducing genes of human solid tumors are members of the ras oncogene family. We used an immunohistochemical assay to assess expression of both the unaltered and the mutated ras oncogene protein (p21) in normal and neoplastic prostatic cells. With the concentration of monoclonal antibody used in this study, epithelial and stromal cells from subjects with normal prostates and from 19 patients with benign prostatic hyperplasia were negative for p21 antigen. This antigen was detected in 2 of 6 prostates with Grade I carcinoma, 4 of 6 with Grade II, and all of 17 with higher grades. A semiquantitative immunohistochemical method demonstrated that expression of the p21 antigen in a carcinoma strongly correlated with nuclear anaplasia and was inversely related to the degree of glandular differentiation. However, markedly anaplastic tumors were often more heterogeneous in expression of p21 and contained areas of low staining for the antigen. Comparison of p21 antigen with tumor carcinoembryonic antigen and prostate-specific antigen demonstrated that ras p21 was the only phenotypic marker that correlated with histologic tumor grade. Thus, ras oncogene p21 may represent a new class of biologically relevant tumor markers and may be a useful adjunct to histopathologic examination in determining the prognosis of patients with prostate cancer.

Sertoli-Leydig cell tumor of the ovary producing alpha-fetoprotein

A 16-year-old girl with virilization and elevated serum alpha-fetoprotein (AFP) levels was found to have a Sertoli-Leydig cell tumor of the ovary. Immunoperoxidase studies using anti-AFP localized AFP in cells with the histologic appearance of Leydig cells. Serum AFP fell to undetectable levels after excision of the tumor. The patient is alive and well 1 year postexcision.

Granular cell variant of neurofibromatosis: ultrastructure of benign and malignant tumors

A case of neurofibromatosis with a metastasizing malignant tumor is presented. The benign lesions were identified by light microscopy as neurofibromas containing granular cells typical of granular cell tumors. The malignant tumor was classified as a malignant granular cell tumor. Ultrastructural studies demonstrated common histogenetic and subcellular features of the benign and malignant tissues. The case is the first reported in which granular cells are seen in the lesions. The typical granular cell morphologic features of the malignant lesion support the concept of Schwann cell derivation of this group of tumors.