Activities of New Macrolides and Fluoroquinolones against Mycobacterium ulcerans Infection in Mice

ABSTRACT Mice infected in the left hind footpad with 5 log10acid-fast bacilli of Mycobacterium ulcerans were divided into an untreated control group and 17 treatment groups that received one of the following regimens for 4 weeks (all doses in milligrams per kilogram): 100 mg of azithromycin (AZM), 100 mg of clarithromycin (CLR), or 50 mg of AZM for a duration of 5 days a week (daily), three times a week, or once weekly. In addition, the following regimens were administered daily: 100 mg of telithromycin (TLM), sparfloxacin (SPX), or moxifloxacin (MOX); 200 mg of levofloxacin (LVX); 100 mg of streptomycin (STR) or amikacin (AMK); 10 mg of rifampin (RIF); and the combination of 10 mg of RIF and 100 mg of AMK (RIF+AMK). After completion of treatment, mice were observed for 30 weeks. The effectiveness of treatment regimens was assessed in terms of the delay in median time to footpad swelling in treated mice compared with that in the untreated controls. Clear-cut bactericidal activity, i.e., an observed delay in footpad swelling that exceeded the period of treatment, was observed in the STR-, AMK-, and RIF+AMK-treated mice. However, all mice treated with either AMK or STR alone had swollen footpads before the end of the 30-week observation period, suggesting regrowth of M. ulcerans. In contrast, 50% of the mice treated with the RIF+AMK combination exhibited no lesion even after 30 weeks, suggesting cure. The remaining regimens could be assigned to one of three groups: (i) no activity (50 mg of AZM, 100 mg of AZM thrice weekly, TLM, and LVX); (ii) bacteriostatic activity, i.e., a delay in footpad swelling shorter than the 4-week treatment duration (100 mg of AZM daily or once weekly, CLR thrice or once weekly, and MOX); or (iii) weak bactericidal activity (CLR daily and SPX). The RIF+AMK combination and possibly RIF+STR warrant further study for the treatment of M. ulceransinfection in humans.

INFLUENCE OF MICROBIOTA IN EXPERIMENTAL CUTANEOUS LEISHMANIASIS IN SWISS MICE

Infection of Swiss/NIH mice with Leishmania major was compared with infection in isogenic resistant C57BL/6 and susceptible BALB/c mice. Swiss/NIH mice showed self-controlled lesions in the injected foot pad. The production of high levels of interferon-<FONT FACE="Symbol">g</font> (IFN-<FONT FACE="Symbol">g</font>) and low levels of interleukin-4 (IL-4) by cells from these animals suggests that they mount a Th1-type immune response. The importance of the indigenous microbiota on the development of murine leishmaniasis was investigated by infecting germfree Swiss/NIH in the hind footpad with L. major and conventionalizing after 3 weeks of infection. Lesions from conventionalized Swiss/NIH mice were significantly larger than conventional mice. Histopathological analysis of lesions from conventionalized animals showed abscesses of variable shapes and sizes and high numbers of parasitized macrophages. In the lesions from conventional mice, besides the absence of abscess formation, parasites were rarely observed. On the other hand, cells from conventional and conventionalized mice produced similar Th1-type response characterized by high levels of IFN-<FONT FACE="Symbol">g</font> and low levels of IL-4. In this study, we demonstrated that Swiss/NIH mice are resistant to L. major infection and that the absence of the normal microbiota at the beginning of infection significantly influenced the lesion size and the inflammatory response at the site of infection.

Construction of a weight-bearing surface on a dog's distal pelvic limb

A one-year-old, neutered female boxer presented with a self-inflicted pandigital amputation following complications of a left hind footpad laceration repair. A meshed skin graft was placed distally over the exposed granulation tissue of the affected limb. In two surgical procedures, a total of five 6 by 8-mm and three 8 by 10-mm digital pad grafts were transplanted into recessed sites in the granulation tissue over the distal aspect of the metatarsal bones. A newly designed pressure relief bandage/ splint was used to assist maturation of the grafts. The result was a weight-bearing surface over an area of maximum tissue stress.

Cardiovascular responses to noxious radiant heat in anesthetized cats

The responses of heart rate and blood pressure to noxious radiant heat were studied in seven pentobarbital-anesthetized cats. Afferent activity recorded from the tibial nerve, systemic blood pressure, and heart rate were monitored as skin temperature of the hind footpad was raised to 53 degrees C for 20 s using radiant heat. The averaged tibial afferent nerve activity increased markedly as skin temperature approached 52 degrees C. Within 2-3 s of the onset of increased tibial nerve activity, systolic blood pressure increased an average of 32 mmHg and heart rate increased an average of 16 beats/min in the seven animals that were studied. The results of this study provide evidence for a somatosympathetic reflex that is initiated by cutaneous nociceptors. Under pentobarbital anesthesia, an increase in heart rate and blood pressure appears to be a reliable indicator of nociceptor activation.

Mechanisms of anti-tumor action of Corynebacterium parvum. I. Potentiated tumor-specific immunity and its therapeutic limitations.

The anti-tumor mechanism in mice induced by a subcutaneous injection of syngeneic tumor cells admixed with Corynebacterium parvum was investigated. When mice were implanted in a hind footpad with x 2 1096) tumor cells admixed with 100 microgram C. parvum, the tumor that emerged grew progressively for about 9 d and then underwent progressive and complete regression. It was found that this C. parvum-induced regression was associated with the acquisition of a systemic, T cell-mediated mechanism of immunity to tumor-specific transplantation antigens, which enabled the host to cause the regression of an untreated test tumor growing simultaneously at a distant site. The generation of a C. parvum-potentiated anti-tumor response was dependent on the presence of tumor cells in close association with C. parvum, tumor immunogenicity, and the quantity of tumor antigen in the admixture. The anti-tumor immunity was specific for the tumor in the therapeutic admixture and could be adoptively transferred to normal recipients with Thy-1.2-positive lymphocytes, but not with serum. Complete regression of a distant test tumor by the C. parvum-tumor admixture was limited to tumors below a certain critical size.

Suppressive Effect Of Neoratal Thymectomy On Occlusive Arterial Thrombosis In Sensitized Rats

It has been found that lymphokines can induce thrombocyte aggregation and biood coagulation.The present study investigated the development of occlusive arterial thrombosis (OAT) in both male and female Wistar rats with altered immunologic background in order to elucidate the immunologic mechanisms in the pathogenesis of OAT.At the age of 10 weeks neonatally thymectomized rats and sham operated litter mate controls were sensitized with 500g of bovine serum albumin (BSA), injected with complete Freund’s adjuvant in a single hind footpad and a second control sham operated rats were injected only with saline. All animals were skin-tested with 30^g of BSA in saline at 7 and 14 days. Arthus reactions were read 3 to 4 hr. Both the average diameter in millimeters and thickness were recorded. Only reactions eaual and greater than 7 mm in diameter were regarded as positive.Experimental OAT was induced when rats reached 3 months of age using a polyethylene loop inserted in the abdominal aorta. The mortality rate (MR), dry thrombus weigt (TW) and loop obstruction time (OT) served as criteria for asessment of thrombosis. According to all the criteria used there was a statistical!v significant sun- nression of the development of occlusive arterial thrombosis in the the neonatally tbvmectomized rats of either sex. The oreviouslv observed sex diferense in OAT was more pronounced.The data presented suggested an involvement of immunologic mechanisms in the thrombogenesis in the arteries and that suitable inhibitors of the immune responses could prove to be of therapeutic value.

Influence of Route of Mycobacterium lepraemurium Injection on Susceptibility to Mouse Leprosy and on Lymphoblastic Transformation

Groups of female C57BL/6 and C3H/St mice were inoculated intraperitoneally (i.p.) with 10 9 , 10 7 , and 10 5 bacilli and into the right hind footpad with 10 7 and 10 5 bacilli of Mycobacterium lepraemurium . The incidence of death from leprosy and the mean survival time of leprous mice were recorded. In addition, the blastogenic responses to the T-cell mitogens phytohemagglutinin and concanavalin A and to the B-cell mitogens lipopolysaccharide and dextran sulfate were evaluated at various times during the course of infection in the spleen and peripheral lymph nodes of mice infected with 10 7 bacilli. When M. lepraemurium was administered i.p., the two strains of mice succumbed to the disease at about the same time, except for the C57BL/6 mice infected with 10 9 bacilli, which died earlier than the C3H/St mice. Moreover, in both strains of mice, a progressive depression of blastogenesis, first to the T-cell mitogens and then to the B-cell mitogens in the spleen, and to the T-cell mitogens in the peripheral lymph nodes, occurred during the course of the infection, whereas the response to the B-cell mitogens in the nodes increased slowly during the advanced stage of the disease. When 10 7 and 10 5 bacilli were injected into the footpad, the C3H/St mice succumbed to the disease at 298 and 344 days, respectively, and the modifications of blastogenesis were similar to those observed in i.p.-infected C3H/St mice. In contrast, the C57BL/6 mice appeared resistant to footpad inoculation of M. lepraemurium , since they lived until the end of the observation period (466 days postinfection) and the depression of blastogenesis was not detectable until 1 year after the infection. Thus, it is concluded that for the C57BL/6 mice (but not for the C3H/St mice), the route of administration of M. lepraemurium can markedly influence the susceptibility or resistance to leprosy.