In calliphorid Diptera, motor neurons mediating visually evoked head movements can be excited or inhibited by visual stimuli, depending on the directionality of the stimulus and whether it is in the ipsi- or contralateral visual field. The level at which inhibition occurs is of special interest because binocular activation of homolateral tangential neurons in the lobula plate demonstrates that excitatory interaction must occur between the left and right optic lobes. Recordings and dye fillings demonstrate a variety of motion-sensitive heterolateral pathways between the lobula plates, or between them and contralateral deutocerebral neuropil, which provides descending pathways to neck motor centers. The profiles of heterolateral tangential cells correspond to neurons stained by an antibody against gamma-aminobutyric acid (GABA). Other GABA-immunoreactive interneurons linking each side of the brain correspond to uniquely identified motion-sensitive neurons linking the deutocerebral. Additional inhibitory pathways include heterolateral GABAergic descending and ascending neurons, as well as heterolateral GABAergic neurons in the thoracic ganglia. The functional significance of heterolateral GABAergic pathways was tested surgically by making selective microlesions and monitoring the oculomotor output. The results demonstrate an important new attribute of the insect visual system. Although lesions can initially abolish an excitatory or inhibitory response, this response is reestablished through alternative pathways that provide inhibitory and excitatory information to the same motor neurons.

The purpose of this paper by the Regulatory Affairs Committee (RAC) of the American Society for Veterinary Clinical Pathology (ASVCP) is to review the current regulatory guidances (eg, guidelines) and published recommendations for best practices in veterinary toxicologic clinical pathology, particularly in the pharmaceutical and biotechnology industries, and to utilize the combined experience of ASVCP RAC to provide updated recommendations. Discussion points include (1) instrumentation, validation, and sample collection, (2) routine laboratory variables, (3) cytologic laboratory variables, (4) data interpretation and reporting (including peer review, reference intervals and statistics), and (5) roles and responsibilities of clinical pathologists and laboratory personnel. Revision and improvement of current practices should be in alignment with evolving regulatory guidance documents, new technology, and expanding understanding and utility of clinical pathology. These recommendations provide a contemporary guide for the refinement of veterinary toxicologic clinical pathology best practices.

Here, we report latent infections with Bartonella quintana and a hemotropic Mycoplasma sp. in a research colony of cynomolgus monkeys (Macaca fascicularis). Sequence alignments, evolutionary analysis, and signature nucleotide sequence motifs of the hemotropic Mycoplasma 16S rRNA and RNase P genes indicate the presence of a novel organism. Hemotropic Mycoplasma spp. (hemoplasmas) are obligate epierythrocytic bacteria that infect numerous animal species, including Homo sapiens. Infections are often chronic and subclinical; however, some animals and humans develop hemolytic anemia, particularly when stressed or immunosuppressed (1, 2). Phylogenetic analyses of 16S rRNA gene sequences have defined two major subclusters of hemoplasmas, namely, the Mycoplasma haemosuis and Mycoplasma haemofelis groups (3-7).Historically, diagnosis of hemoplasma infections has relied on cytological examination of stained blood smears. In 1994, Dillberger and colleagues described Haemobartonella-like parasites in five wild-caught anemic cynomolgus monkeys (Macaca fascicularis) that originated from the Philippines; however, the organisms were not characterized phylogenetically (8). For some animal species, the diagnostic sensitivity of a blood smear examination is very poor and unspecific (3, 4, 9). The development of molecular assays, primarily targeting the 16S rRNA and the RNase P genes of these cell wall-deficient uncultivable microbes, has resulted in the recent recognition of several novel animal hemoplasmas (4, 5, 10-13).Bartonella spp. are facultative intracellular bacteria that also infect erythrocytes in numerous animal species, including Homo sapiens. Previously, Bartonella quintana DNA was amplified, cloned, and sequenced from lysed erythrocytes, and cultured colonies were grown from peripheral blood collected from a captivebred cynomolgus monkey (Macaca fascicularis) (14). Bartonella quintana was subsequently isolated from 2 of 36 captive rhesus macaques in China, of which 12 of 33 were B. quintana seroreactive (15).Hemotropic Mycoplasma and Bartonella organisms often cause persistent occult infection in immunocompetent hosts. The extent to which an infection with these bacteria in cynomolgus monkeys involved in a research study might influence assessments or outcomes associated with drug development studies is poorly characterized. This report describes PCR amplification and DNA sequence characterization of a novel hemotropic Mycoplasma sp. found in the blood of 44 of 52 cynomolgus research monkeys (Macaca fascicularis) and the isolation of Bartonella quintana from one monkey. These animals were in a chronic toxicity study, and data from the pretest phase of the study are presented. The animals were tested for Mycoplasma and Bartonella on the basis of the findings in a previous toxicity study that raised the possibility of latent infections. Based on the analysis of the 16S rRNA and RNase P gene sequences, we propose "Candidatus Mycoplasma haemomacaque" as the name for the novel hemotropic Mycoplasma sp. identified in this ...

| INTRODUC TI ONClinical pathologists working in the industry setting provide specialized expertise in the interpretation of clinical pathology results to support nonclinical animal studies for the purposes of pharmaceutical, agrochemical, food additive, and medical device safety assessment. As the number and complexity of clinical pathology and biomarker assays used in these studies has steadily grown over the last several decades, so has the specialized discipline of Toxicologic Clinical Pathology. Test article-related (TAR) clinical pathology findings must not only be accurately reflected in an interpretive report, but they must also be integrated with other relevant study data (eg, anatomic pathology, in-life, toxicokinetic). Although the task of interpretation of clinical pathology results is sometimes assigned to individuals with little to no formal clinical pathology training, we recommend that clinical pathology interpretive reports be authored by veterinary clinical pathologists with specialized training and experience in toxicologic clinical pathology, especially for pivotal (early and late stage) nonclinical studies. The purpose of this manuscript is to present an overview of current interpretive practices within the pharmaceutical industry and to propose guidelines that will help authors draft accurate, industry-standard clinical pathology interpretive reports. | ROLE AND QUALIFI C ATI ON S OF THE CONTRIBUTING SCIENTIS TClinical pathology evaluations are an integral part of most nonclinical pharmaceutical and agrochemical research projects ranging from proof of concept to general toxicology studies, target animal safety (in the development of animal health products), and medical Abstract The interpretation of clinical pathology results from nonclinical safety studies is a fundamental component in hazard identification of new drug candidates. The everincreasing complexity of nonclinical safety studies and sophistication of modern analytical methods have made the interpretation of clinical pathology information by a highly trained subject matter expert imperative. Certain interpretive techniques are particularly effective in the identification and characterization of clinical pathology effects. The purpose of this manuscript is to provide an overview of contemporary interpretive practices for clinical pathology results and to provide nonbinding recommendations aimed at improving consistency, quality, and overall value of clinical pathology interpretations generated in support of nonclinical toxicology studies.

In preclinical safety assessment, blood volume requirements for various endpoints pose a major challenge. The goal of this working group was to review current practices for clinical pathology (CP) testing in preclinical toxicologic studies, and to discuss advantages and disadvantages of methods for reducing blood volume requirements. An industry-wide survey was conducted to gather information on CP instrumentation and blood collection practices for hematology, clinical biochemistry, and coagulation evaluation in laboratory animals involved in preclinical studies. Based on the survey results and collective experience of the authors, the working group proposes the following "points to consider" for CP testing: (1) For most commercial analyzers, 0.5 mL and 0.8 mL of whole blood are sufficient for hematology and biochemistry evaluation, respectively. (2) Small analyzers with low volume requirements and low throughput have limited utility in preclinical studies. (3) Sample pooling or dilution is inappropriate for many CP methods. (4) Appropriate collection sites should be determined based on blood volume requirements and technical expertise. (5) Microsampling does not provide sufficient volume given current analyzer and quality assurance requirements. (6) Study design considerations include: the use of older/larger animals (rodents), collection of CP samples before toxicokinetic samples, use of separate subsets of mice for hematology and clinical biochemistry testing, use of a priority list for clinical biochemistry, and when possible, eliminating coagulation testing.

There is limited direction in the literature or regulatory guidance on determination of adversity for clinical pathology (CP) biomarkers in preclinical safety studies. Toxicologic clinical pathologists representing the American Society for Veterinary Clinical Pathology-Regulatory Affairs Committee and Society of Toxicologic Pathology-Clinical Pathology Interest Group identified principles, overall approach, and unique considerations for assessing adversity in CP data interpretation to provide a consensus opinion. Emphasized is the need for pathophysiologic context and a weight-of-evidence approach. Most CP biomarkers do not have the potential to be adverse in isolation, regardless of magnitude of change. Rather, they quantify or describe the impact of effects, provide adjunct or supportive information regarding a process or pathogenesis, and provide translational biomarkers of effect. Most often, CP changes are part of a constellation of findings that collectively are adverse. Thus, most CP changes must be interpreted in conjunction with other study findings and require contextual and integrative interpretation. Exceptions include critical CP changes without correlates that indicate a health risk in the tested species. Overall, CP changes should not be interpreted in isolation and their adversity is best addressed with an integrated approach.

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The phenomenon by which irradiated cells influence nonirradiated neighboring cells, referred to as the bystander effect (BSE), is not well understood in terms of the underlying pathways involved. We sought to enlighten connections between DNA damage repair and the BSE. Utilizing sister chromatid exchange (SCE) frequencies as a marker of the BSE, we performed cell transfer strategies that enabled us to distinguish between generation versus reception of a bystander signal. We find that DNAdependent Protein Kinase catalytic subunit (DNA-PKcs) and Ataxia Telangectasia Mutated (ATM) are necessary for the generation of such a bystander signal in normal human cells following gamma (c)-ray exposure, but are not required for its reception. Importantly, we also show that directly irradiated human cells do not respond to receipt of a bystander signal, helping to explain why the BSE is a low-dose phenomenon. These studies provide the first evidence for a role of the DNA damage response proteins DNA-PKcs and ATM specifically in the generation of a bystander signal and intercellular signaling.