Mouse models of acute promyelocytic leukemia.

Translocations involving a variety of fusion partners, such as promyelocytic leukemia gene, promyelocytic leukemia zinc finger, nucleophosmin, nuclear matrix protein, and signal transducer and activator of transcription protein 5B, with the retinoic acid receptor alpha gene are commonly associated with development of acute promyelocytic leukemia. Through the development of transgenic mouse models, some retinoic acid receptor alpha translocation fusion proteins have been shown to be capable of initiating acute promyelocytic leukemia development, and dictate the leukemias' responsiveness to retinoic acid. Transgenic mouse models also have identified the influence of reciprocal translocation fusion proteins on acute promyelocytic leukemia development, and have demonstrated that additional mutations can contribute to the development of acute promyelocytic leukemia. In this review, the authors summarize current mouse models of acute promyelocytic leukemia and describe current knowledge about additional genetic alterations that occur during development of acute promyelocytic leukemia in the mouse.

Comparison of acute swelling and function in subjects with lateral ankle injury.

STUDY DESIGN: Prospective correlational study involving a convenience sample. OBJECTIVES: To investigate the relationships among figure-of-eight girth measurements and functional level in patients with acute lateral ankle sprains to determine the appropriate use of these clinical measures. BACKGROUND: Research has shown that subjective scales of perceived athletic ability and measurements of swelling are useful in assessing clinical improvement following an acute ankle sprain; however, the relationship between ankle swelling and level of function is not known. METHODS AND MEASURES: Twenty-nine subjects (20 men, 9 women) varying in age from 18-59 years of age (mean age, 30.8 +/- 11.37) with acute lateral ankle sprains were included in this study. Each subject was evaluated by 1 of 3 raters for ankle girth, weight-bearing status, and functional level as determined by a modified Ankle Osteoarthritis Scale (AOS) and the Foot and Ankle Ability Index (FAAI). This study also investigated the relationship between these measures and the sport subscale of the FAAI (FAAI sport). This is an 8-item subscale which includes questions on running, jumping, landing, quick starts and stops, cutting or lateral movements, low impact activities, ability to perform an activity with normal technique, and ability to participate in desired sports. RESULTS: No significant correlations were found between figure-of-eight girth measurements and functional level. However, we did find moderate to good correlations between the FAAI vs. weight-bearing (rho = 0.73), FAAI vs. AOS (rho = -0.79), FAAI sport vs. weight-bearing (rho = 0.68), FAAI vs. FAAI Sport (rho = 0.73), weight-bearing vs. AOS (rho = -0.57), and FAAI Sport vs. AOS (rho = -0.50). CONCLUSIONS: The figure-of-eight method is highly reliable and is appropriate for measuring ankle swelling; however, it does not correlate with functional level as determined by the modified AOS, FAAI, or observed weight-bearing status during gait. Therefore, clinicians should refrain from making assumptions about function based on ankle swelling.

Acquired, nonrandom chromosomal abnormalities associated with the development of acute promyelocytic leukemia in transgenic mice.

We previously generated a transgenic mouse model for acute promyelocytic leukemia (APL) by expressing the promyelocytic leukemia (PML)-retinoic acid receptor (RARalpha) cDNA in early myeloid cells. This fusion protein causes a myeloproliferative disease in 100% of animals, but only 15-20% of the animals develop acute leukemia after a long latency period (6-13 months). PML-RARalpha is therefore necessary, but not sufficient, for APL development. The coexpression of a reciprocal form of the fusion, RARalpha-PML, increased the likelihood of APL development (55-60%), but did not shorten latency. Together, these results suggested that additional genetic events are required for the development of APL. We therefore evaluated the splenic tumor cells from 18 transgenic mice with APL for evidence of secondary genetic events, by using spectral karyotyping analysis. Interstitial or terminal deletions of the distal region of one copy of chromosome 2 [del(2)] were found in 1/5 tumors expressing PML-RARalpha, but in 11/13 tumors expressing both PML-RARalpha and RARalpha-PML (P < 0.05). Leukemic cells that contained a deletion on chromosome 2 often contained additional chromosomal gains (especially of 15), chromosomal losses (especially of 11 or X/Y), or were tetraploid (P

A bcr-3 isoform of RARalpha-PML potentiates the development of PML-RARalpha-driven acute promyelocytic leukemia.

Acute promyelocytic leukemia (APML) most often is associated with the balanced reciprocal translocation t(15;17) (q22;q11.2) and the expression of both the PML-RARalpha and RARalpha-PML fusion cDNAs that are formed by this translocation. In this report, we investigated the biological role of a bcr-3 isoform of RARalpha-PML for the development of APML in a transgenic mouse model. Expression of RARalpha-PML alone in the early myeloid cells of transgenic mice did not alter myeloid development or cause APML, but its expression significantly increased the penetrance of APML in mice expressing a bcr-1 isoform of PML-RARalpha (15% of animals developed APML with PML-RARalpha alone vs. 57% with both transgenes, P < 0.001). The latency of APML development was not altered substantially by the expression of RARalpha-PML, suggesting that it does not behave as a classical "second hit" for development of the disease. Leukemias that arose from doubly transgenic mice were less mature than those from PML-RARalpha transgenic mice, but they both responded to all-trans retinoic acid in vitro. These findings suggest that PML-RARalpha drives the development of APML and defines its basic phenotype, whereas RARalpha-PML potentiates this phenotype via mechanisms that are not yet understood.

Interferon gamma regulates acute and latent murine cytomegalovirus infection and chronic disease of the great vessels.

To define immune mechanisms that regulate chronic and latent herpesvirus infection, we analyzed the role of interferon gamma (IFN-gamma) during murine cytomegalovirus (MCMV) infection. Lethality studies demonstrated a net protective role for IFN-gamma, independent of IFN-alpha/beta, during acute MCMV infection. Mice lacking the IFN-gamma receptor (IFN-gammaR-/-) developed and maintained striking chronic aortic inflammation. Arteritis was associated with inclusion bodies and MCMV antigen in the aortic media. To understand how lack of IFN-gamma responses could lead to chronic vascular disease, we evaluated the role of IFN-gamma in MCMV latency. MCMV-infected IFN-gammaR-/- mice shed preformed infectious MCMV in spleen, peritoneal exudate cells, and salivary gland for up to 6 mo after infection, whereas the majority of congenic control animals cleared chronic productive infection. However, the IFN-gammaR was not required for establishment of latency. Using an in vitro explant reactivation model, we showed that IFN-gamma reversibly inhibited MCMV reactivation from latency. This was at least partly explained by IFN-gamma- mediated blockade of growth of low levels of MCMV in tissue explants. These in vivo and in vitro data suggest that IFN-gamma regulation of reactivation from latency contributes to control of chronic vascular disease caused by MCMV. These studies are the first to demonstrate that a component of the immune system (IFN-gamma) is necessary to regulate MCMV-associated elastic arteritis and latency in vivo and reactivation of a herpesvirus from latency in vitro. This provides a new model for analysis of the interrelationships among herpesvirus latency, the immune system, and chronic disease of the great vessels.

Murine cytomegalovirus infection inhibits IFN gamma-induced MHC class II expression on macrophages: the role of type I interferon.

Macrophage (M phi) activation, as measured by cell surface expression of MHC class II, was examined during infection of immunocompetent and immunocompromised mice with murine cytomegalovirus (MCMV). Intraperitoneal infection of CB17 SCID mice with 10(6) PFU of MCMV elicited a large population of M phi which expressed low levels of MHC class II. This was surprising since infection of SCID mice with lower doses (e.g., 10(4) PFU) of MCMV elicits M phi expressing high levels of MHC class II (M. T. Heise and H. W. Virgin, J. Virol. (1995) 69, 904-909). In vivo administration of recombinant mouse IFN gamma resulted in high levels of MHC class II expression on M phi from control but not MCMV-infected SCID mice, suggesting that MCMV infection generates a state in which IFN gamma is not effective at activating M phi. The effect of MCMV infection was MHC class II specific, since MHC class I and ICAM-1 levels were increased on M phi expressing low levels of MHC class II. Interference with IFN gamma action was not due to productive or abortive infection of M phi. This suggested that MCMV infection induces a soluble factor that alters M phi responsiveness to IFN gamma. Infection of SCID mice with 10(6) PFU of MCMV induced higher levels of serum IFN alpha beta (one candidate for inhibition of IFN gamma induction of MHC class II expression) than infection with 10(4) PFU. We therefore evaluated the role of MCMV-induced IFN alpha beta on IFN gamma responses of bone marrow-derived (BMM phi) or thioglycollate-elicited M phi in vitro. Infection of normal M phi with MCMV at a low m.o.i. (0.1 to 0.2) impaired IFN gamma-mediated induction of M phi MHC class II expression, but not MHC class I expression. Inhibition of IFN gamma responses was not observed in M phi from mice with a null mutation in the IFN alpha beta receptor (IFN alpha beta R-/-). To test the in vivo relevance of virus-induced IFN alpha beta to IFN gamma-mediated responses, the kinetics of MHC class II induction during MCMV infection of IFN alpha beta R-/- mice was evaluated. MCMV-infected IFN alpha beta R-/- mice mounted an earlier M phi MHC class II response than normal mice. We conclude that MCMV infection specifically impairs IFN gamma-mediated MHC class II expression on M phi and that induction of IFN alpha beta is one mechanism by which this inhibition occurs.

Latent murine cytomegalovirus infection in macrophages.

In this study we show that macrophages (Mphi) are latently infected with murine cytomegalovirus (MCMV). After clearance of acute MCMV infection, the predominant form of chronic infection in Balb mice is latency rather than persistence. Peritoneal exudate cells (PECs) from latently infected Balb mice (3-9 months postinfection) contained MCMV genome and reactivatable virus. Adherent cells from both resident and thioglycollate-elicited PECs carried more MCMV DNA (measured by PCR) than nonadherent cells, and were selectively enriched for Mphi. FACS sorted F4/80(+) Mphi contained MCMV DNA, while other FACS sorted cell populations from PECs were never positive for MCMV DNA. MCMV reactivated from FACS sorted F4/80(+) Mphi in 32% of cocultures with murine embryonic fibroblasts (MEFs). Since Mphi carry MCMV genome and reactivatable virus, but not lytic virus, they are latently infected with MCMV. We determined the frequency of Mphi carrying MCMV genome in PECs (about 1/50,000) using a limiting dilution PCR assay. Using this frequency and estimates of the total amount of MCMV genome in populations, we estimate that latently infected Mphi carry 1-10 copies of MCMV genome. To evaluate the origin of latently infected Mphi, we compared the frequency of cells carrying MCMV genome in the resident and elicited PECs. The frequency of Mphi carrying MCMV DNA was the same in resident and thioglycollate-elicited PECs, despite the fact that there was a ninefold increase in the number of Mphi recovered after thioglycollate elicitation. This argued for recruitment of bone marrow-derived Mphi (BMMphi) carrying MCMV genome into the peritoneum during inflammatory responses. Consistent with this hypothesis, MCMV genome, but not persistent virus, was detected in bone marrow cells from latently infected mice.

Testosterone concentrations and oligomenorrhea in women with acne.

BACKGROUND: Androgen excess is frequently associated with oligomenorrhea as well as acne. Oligomenorrhea in hirsute women has been demonstrated to be associated with higher active testosterone levels than found in eumenorrheic hirsute women. This study was designed to evaluate whether similar findings are present in women with acne. Forty-four consecutive women with acne were evaluated by measuring their levels of total testosterone, biologically active testosterone, and free testosterone. The women with oligomenorrhea and acne had significantly higher levels of biologically active testosterone than those with eumenorrhea and acne. This implies that biological active testosterone should be measured in oligomenorrheic women with acne and, if elevated, consideration should be given to antiandrogen therapy. METHODS: Data were collected from 44 consecutive Caucasian women aged 14 to 38 years. The patients were separated into two groups based on menstrual history. Group 1 had regular menses, and group 2 had oligomenorrhea, defined as menstrual intervals of greater than 36 days. All patients had blood samples drawn on their initial office visit, regardless of the phase of the menstrual cycle, and the levels of total testosterone (TT), biologically active testosterone (BT), and free testosterone (FT) were obtained. RESULTS: The serum TT level was 87 +/- 41.3 ng/dL (range, 31-150 ng/dL) in oligomenorrheic women and 56 +/- 27.5 ng/dL (range 8-107 ng/dL) in eumenorrheic women. There was no statistically significant difference. The serum BT level in oligomenorrheic women was 33 +/- 16.9 ng/dL (range, 11-51 ng/dL) and in eumenorrheic women 19 +/- 13.6 ng/dL (range, 11-51 ng/dL). This difference was statistically significant (p < 0.05). The serum FT level in oligomenorrheic women was 18 +/- 9.4 pg/mL (range, 1-29 pg/mL) and in eumenorrheic women 10 +/- 7.1 pg/mL (range, 1-32 pg/mL). This difference was not statistically significant (Table 1). CONCLUSIONS: Women with acne and oligomenorrhea, similar to women with hirsutism and oligomenorrhea, have higher levels of biologically active testosterone than those with normal menses.

Latency, without persistence, of murine cytomegalovirus in the spleen and kidney.

It is not known if murine cytomegalovirus (MCMV) establishes a state of molecular latency independent of low-level persistent infection. The presence of low levels of infectious MCMV distinguishes persistence from molecular latency. Thus, the distinction between persistence and latency has depended on the sensitivity of plaque assays for detecting low levels of infectious virus in tissue of previously infected mice. To determine whether MCMV establishes molecular latency or remains persistent, we developed two assays for detecting low levels of MCMV in tissue. Using prolonged in vitro culture of virus with either mouse embryonic fibroblasts or the murine 3T12 fibroblast cell line, we reproducibly detected a single PFU of MCMV. Inclusion of undiluted sonicated tissue in this assay decreased sensitivity by up to 100-fold. However, sensitivity was improved to 1 PFU of MCMV when sonicated tissue was appropriately diluted. Severe combined immunodeficient (SCID) mice were also used to detect MCMV in sonicated tissue. Infection of SCID mice with a single PFU of MCMV killed two of eight SCID mice, and the 50% lethal dose of MCMV in SCID mice was 2 to 3 PFU. Applying these two methods, we detected infectious virus in 0 of 34 spleens, 1 of 34 kidneys, and 0 of 37 salivary glands from latently infected mice. Spleens and kidneys assessed for persistent virus contained MCMV DNA by PCR and reactivated after 10 to 50 days in explant cultures. Latently infected kidney cells reactivated after adoptive transfer to SCID mice. Quantitation of the MCMV genome by PCR showed that latently infected spleens without detectable infectious MCMV contained about 3,000,000 copies of the MCMV genome. These results demonstrate that MCMV latency in spleen and kidney exists in the absence of low-level persistent infection. Use of assays with defined sensitivity for detection of MCMV in tissue provides a basis for evaluation of cytomegalovirus gene expression in the spleen and kidney during molecular latency.

Metastatic ductal carcinoma of the parotid gland in a patient with sarcoidosis.

A 38-year-old man with a history of sarcoidosis and ductal carcinoma of the parotid had metastasis to the pleura and skin. This skin metastasis resembled carcinoma of the breast. There is a possibility of sarcoidosis with its depressed cellular immunity predisposing to malignancy.

Toxoplasmosis appearing to be dermatomyositis.

A case of toxoplasmosis occurred simultaneously with dermatomyositis in a 12-year-old boy. The patient was treated with sulfadiazine and pyrimethamine; within two weeks after initiating therapy, dramatic clinical improvement was noted. Several previous cases of toxoplasmosis occurring in association with polymyositis have been described in the literature. A serologic investigation for Toxoplasma infection might prove to be of value in establishing the cause of dermatomyositis and polymyositis. Moreover, in selected cases of dermatomyositis or polymyositis, treatment with sulfadiazine, pyrimethamine, and folinic acid may be a valuable alternative to the use of steroids and immunosuppressive agents.