The influence of the Leydig cells on the leukocyte population of the testis was investigated. Leydig cells were destroyed by ethane dimethane sulfonate (EDS) treatment in adult male rats, with or without low-dose s.c. testosterone implants to prevent Leydig cell recovery. Leukocytes were counted in perfusion-fixed frozen testis sections, by use of cell-specific monoclonal antibodies (mAbs) with immunoperoxidase detection, or toluidine blue staining. The majority (81%) of testicular leukocytes (OX1+) were immunopositive for the resident macrophage-specific mAb, ED2, and/or the monocyte/macrophage/dendritic cell mAb, ED1. The remaining leukocytes were principally T lymphocytes (R73+). B lymphocytes (OX33+) and metachromatic mast cells were not observed in the normal testis. Treatment with EDS caused a transient increase in ED1+, ED2+, and R73+ cell numbers in the testis, although other evidence of an inflammatory reaction, such as increases in major histocompatibility complex class II antigen, interleukin-2 receptor expression, or capillary permeability, were not observed. At 21 days after EDS treatment, there was a significant decline in macrophage numbers (to approximately 50% of control testis), and T lymphocytes returned to pretreatment levels. After Leydig cell recovery (41 days after treatment), macrophages also returned to pretreatment levels in EDS-treated rats, but remained reduced in EDS-treated animals with testosterone implants. In addition, EDS treatment stimulated a progressive increase in intertubular mast cells, which was significantly inhibited in the testosterone-implanted rats. The data indicate that numbers of testicular macrophages and mast cells, but not of lymphocytes, within the adult rat testis are directly or indirectly regulated by the Leydig cells.

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Increasing incidence of multidrug-resistant bacteria presents an imminent risk to global health. Polymyxins are 'last-resort' antibiotics against Gram-negative 'superbugs'; however, nephrotoxicity remains a key impediment in their clinical use. Molecular mechanisms underlying this nephrotoxicity remain poorly defined. Here, we examined the pathways which led to polymyxin B induced cell death in vitro and in vivo. Human proximal tubular cells were treated with polymyxin B (12.5-100 μM) for up to 24 h and showed a significant increase in micronuclei frequency, as well as abnormal mitotic events (over 40% in treated cells, p < 0.05). Time-course studies were performed using a mouse nephrotoxicity model (cumulative 72 mg/kg). Kidneys were collected over 48 h and investigated for histopathology and DNA damage. Notable increases in γH2AX foci (indicative of double-stranded breaks) were observed in both cell culture (up to ~ 44% cells with 5+ foci at 24 h, p < 0.05) and mice treated with polymyxin B (up to ~ 25%, p < 0.05). Consistent with these results, in vitro assays showed high binding affinity of polymyxin B to DNA. Together, our results indicate that polymyxin B nephrotoxicity is associated with DNA damage, leading to chromosome missegregation and genome instability. This novel mechanistic information may lead to new strategies to overcome the nephrotoxicity of this important last-line class of antibiotics.

This paper describes research conducted on the design of a new automatic fish sorting system at Monash University, Australia. A concurrent mechatronics approach was implement to achieve the project's goals. Also, a technique based on digital imaging was developed for the task of identification of fish sizes. The system is being implemented in the local fish export industry, providing a low cost operation with improved productivity and reliability in the fish sorting process.A computer-based vision system is used for analysis of the fish. A new algorithm is developed to directly determine the length of fish with fast on-line real-time processing. The measurement technique is also applicable to various species. The design specifications of the vision system and the camera capture devices are also presented in this paper.

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In the original publication of the article, part of Fig. 6 is missing. The missing subpanels, Fig. 6c, d are given below.

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