Pulsed-field gel electrophoresis techniques were used to examine the chromosomes of Pneumocystis carinii isolated from laboratory rats and two human subjects. P. carinii organisms isolated from each of four rat colonies and from two patients each produced a distinct band pattern, but in all cases the bands ranged in size from 300 to 700 kilobase pairs. P. carinùi from three rat colonies produced patterns containing 15 prominent bands. Of these 15 bands, 2 stained more intensely than would be expected of bands of their size, suggesting that the P. carinii haploid genome contains 17 to 19 chromosomes. Summing the molecular sizes of the bands and accounting for staining intensities suggested that the haploid genome of rat-derived P. carinii contains on the order of 107 base pairs. Human-derived P. carinii produced patterns containing 10 to 12 bands which appeared to be similar to the 15-band patterns seen in rat-derived P. caring with respect to the size range of the bands. P. carinii from the fourth rat colony produced a more complex band pattern containing approximately 22 bands, most of which appeared to comigrate with the bands present in one of the 15-band P. carinii patterns, suggesting that these animals were simultaneously infected by two different varieties of P. carinii. Hybridization experiments using oligonucleotide probes specific for the P. carinu 18S rRNA gene supported this possibility. The band pattern of P. carinii derived from a given rat colony was generally stable over time. P. carinii band patterns were not strictly rat strain specific and appeared to be transferable between animals housed in the same room.

Over a 7-year period, we analyzed 261 dose regimens of antimicrobial drugs in the treatment and prevention of Pneumocystis carinii pneumonia in an immunosuppressed rat model. These compounds ranged from drugs in clinical use to newly synthesized agents. Drug efficacy was expressed as the magnitude of the reduction in median P. carinii cyst or nucleus counts on a scale ranging from inactive (<5-fold) to very markedly active (.1,000-fold). The classification system was reproducible and allowed drugs studied at different times to be compared with each other. The system demonstrated a hierarchy of anti-P. carinii activity not only among classes of compounds but also among individual members of a drug class. Sulfonamides, sulfones, and diamidines were the most active agents; some purine nucleosides and nitrofurans also showed promising activity; and most antiparasitic, antifungal, antibacterial, and antiviral drugs were inactive. We conclude that this classification system represents a simple, quantitative method of comparing the activities of antimicrobial drugs against P. carinii. Information gained from this system should be helpful in developing new anti-P. carinii compounds and establishing standard procedures for their evaluation.Over the past decade, there has been a major rise in the number of cases of Pneumocystis carinii pneumonia associated with AIDS. The well-publicized limitations of currently available anti-P. carinii drugs in AIDS patients have emphasized the need for new therapeutic approaches (37). Most drug testing has been performed in an immunosuppressed rat model of pneumocystosis, which accurately predicts activity against human P. carinii. Compounds which have exhibited anti-P. carinii activity in the rat model include antifolate drugs (alone or in combination) such as dihydrofolate reductase (DHFR) inhibitors, sulfonamides, sulfones, and sulfonylureas (7, 9, 12, 14, 16-20, 23, 24, 27, 35, 39, 42, 43); sulfonamides in combination with other drugs (e.g., macrolides) (13); diamidines and related cationic compounds (8,11,21,34,40); 8-aminoquinolones, alone or in combination with other agents (1, 28); purine nucleosides (la, 32, 36); polyamine inhibitors (3, 4); nitrofurans (38); 3-glucan inhibitors (26, 29, 30); hydroxynaphthoquinones (14); fluoroquinolones (2); iron chelators (4); and immunological agents (antibodies, cytokines) (10,31).Although the rat model has been very valuable, evaluation of anti-P. carinii drugs is time-consuming, expensive, and labor intensive; only a few compounds can be tested in a given experiment. Treatment studies have been performed by different experimental protocols and methods of evaluating drug efficacy; this lack of standardization has prevented the results of one investigator from being compared directly with those of another. Little attention has also been devoted to quantitating the reduction in organism burden which can be achieved with different doses of anti-P. carinii drugs. In addition, there have been few published sources of information of the compound...

Beckwith-Wiedemann syndrome (BWS) and isolated hemihyperplasia (IHH) are two well known overgrowth conditions that are associated with cancer predisposition. Multiple surveillance protocols have been proposed to detect the most commonly reported tumor types Wilms tumor and hepatoblastoma. We reviewed the history of our patients who were part of this monitoring protocol. Information from 63 cases was collected retrospectively while another 63 control samples for AFP measurement were obtained prospectively. Twenty-five (40%) patients had an ultrasound abnormality, the most frequent being nephromegaly/size discrepancy. Two patients had well documented cases of tumors/tumor precursor (2/63:3.2%) detected by ultrasound images. Three hundred thirty-six separate AFP values were available with values above 50,000 ng/ml seen in three patients older than 2 months, one with hepatoblastoma and two other with hemangiomas/hemangioendotheliomas. There was no clear difference in the range of AFP values between previously reported controls, our own normal population and affected patients. In conclusion, ultrasound surveillance detected renal and liver pathology including benign and malignant lesions. The known variability of AFP in normal neonates and patients with BWS makes interpretation difficult in early infancy. Very high AFP values did seem to be correlated with risk for identifiable liver lesions. Determination of the natural changes in AFP levels over time will allow more appropriate comparison.

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The efficacy of antifolate, antiviral, and other drugs was compared in an experimental model of pneumocystosis. Sulfamethoxazole (SMX) administered alone in doses of .60 mg/kg/day was highly effective in treatment and prophylaxis. Low (c15 mg/kg/day) doses of SMX showed limited, dose-related antiPneumocystis carinii activity in therapy but were more effective in prophylaxis. The dihydrofolate reductase (DHFR) inhibitors trimethoprim (TMP), pyrimethamine, and trimetrexate exhibited little anti-P. carinii activity when administered alone and did not enhance the efficacy of SMX; the effects of the DHFR inhibitors could not be related to the dose or the concentration in serum. These data suggested that the rat model is an excellent system for studying the anti-P. carinii activity of sulfonamides but is of limited value in studying DHFR inhibitors. The antiviral drugs azidothymidine, dideoxyinosine, inosine pranobex (Isoprinosine), amantadine, and acyclovir displayed little or no activity against P. carinii; however, azidothymidine did not impair the efficacy of SMX or TMP-SMX. These results supported the clinical practice of giving antiviral agents together with antifolate drugs to patients infected with human immunodeficiency virus and suggested that the beneficial effects of antiviral agents on the occurrence of pneumocystosis are due mainly to their effects on the virus or the host immune response. In contrast to the antiviral drugs, 9-deazainosine, a nucleoside analog with antiprotozoal properties, deinonstrated marked activity against P. carinii which was related to dose and route of administration. These data raised the possibility that anti-P. carinii activity is a general property of purine nucleosides Experimental studies of anti-P. carinii drugs have usually been performed in an immunosuppressed rat model of pneumocystosis, which is a reliable predictor of activity against the human form of the disease (10,13,20). In a previous study of antifolate drugs in this model (34), we found that anti-P. carinii activity was a general property of sulfonamides; these compounds were so effective that a doseresponse curve could not be established at the doses used. By contrast, DHFR inhibitors exhibited little anti-P. carinii activity and did not improve the efficacy of the sulfonamides * Corresponding author.or the sulfone dapsone. This lack of synergism differed from the results of previous workers (10,14,15) and raised questions about the value of using the rat model to screen antifolate drugs.In the present study, we have extended these observations by exploring the effect of lower doses of the sulfonamide sulfamethoxazole (SMX) in the therapy of experimental pneumocystosis. We