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Treatment of the side-on tungsten alkyne complex of ethinylethyl ether [Tp*W(CO) 2 (η 2 - C , C '-HCCOCH 2 CH 3 )] + {Tp* = hydridotris(3,4,5-trimethylpyrazolyl)borate} (2a) with n -Bu 4 NI afforded the end-on ketenyl complex [Tp*W(CO) 2 (κ 1 -HCCO)] (4a). This formal 16 ve complex bearing the prototype of a ketenyl ligand is surprisingly stable and converts only under activation by UV light or heat to form a dinuclear complex [Tp* 2 W 2 (CO) 4 (μ-CCH 2 )] (6). The ketenyl ligand in complex 4a underwent a metal template controlled cyclization reaction upon addition of isocyanides. The oxametallacycles [Tp*W(CO) 2 {κ 2 - C , O -C(NHXy)C(H)C(Nu)O}] {Nu = OMe (7), OEt (8), N(i-Pr) 2 (9), OH (10), O 1/2 (11)} were formed by coordination of Xy-NC (Xy = 2,6-dimethylphenyl) at 4a and subsequent migratory insertion (MI) into the W-ketenyl bond. The resulting intermediate is susceptible to addition reactions with protic nucleophiles. Compounds 2a-PF 6 , 4a/b, and 7-11 were fully characterized including XRD analysis. The cyclization mechanism has been confirmed both experimentally and by DFT calculations. In cyclic voltammetry, complexes 7-9 are characterized by a reversible W(ii)/W(iii) redox process. The dinuclear complex 11 however shows two separated redox events. Based on cyclic voltammetry measurements with different conducting electrolytes and IR spectroelectrochemical (SEC) measurements the W(ii)/W(iii) mixed valent complex 11 + is assigned to class II in terms of the Robin-Day classification., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Background: In contrast to the hospital setting, today little work has been directed to the definition, measurement, and improvement of the quality of out-patient medical and therapeutic care. We developed a set of indicators to measure the quality of out-patient neuropsychological therapy after stroke., Methods: The indicators cover core and interdisciplinary aspects of out-patient neuropsychological work such as mediation of patients into social care in case of need. Selection of the quality-indicators was done together with a consensus group of out-patient therapists and supported by evidence, validity, reliability as well as estimated relevance and variability with the quality of care. The set of indicators was further tested in a retrospective cohort study. Anonymous data of 104 patients were collected from out-patient clinical records of five clinics between November 2017 and April 2018. Associations between process and outcome quality were estimated exploitatively., Results: Results allowed for the identification of areas with greater variability in the quality of process care and indicated that attention training as recommended by current guidelines had the lowest overall rate for meeting the quality-aim (met in 44% of the cases). This was followed by time < 1 month until the start of therapy (63% met) and mediation into social care in case of need (65% met). We further observed that overall quality and involving relatives in the therapy was associated with higher rates of professional reintegration (p-value = 0.03). However, the need for mediation into social care was associated with a reduced chance for successful professional reintegration (p-value = 0.009)., Conclusion: In conclusion, we describe a first set of quality indicators which cover different aspects of out-patient neuropsychological therapy and sufficient variability with care. First data further suggests that meeting the specified quality aims may indeed have relevant effects on outcomes.

Background: A large quantity of data is collected during the delivery of cancer care. However, once collected, these data are difficult for health professionals to access to support clinical decision making and performance review. There is a need for innovative tools that make clinical data more accessible to support health professionals in these activities. One approach for providing health professionals with access to clinical data is to create the infrastructure and interface for a clinical dashboard to make data accessible in a timely and relevant manner., Objective: This study aimed to develop and evaluate 2 prototype dashboards for displaying data on the identification and management of lymphedema., Methods: The study used a co-design framework to develop 2 prototype dashboards for use by health professionals delivering breast cancer care. The key feature of these dashboards was an approach for visualizing lymphedema patient cohort and individual patient data. This project began with 2 focus group sessions conducted with members of a breast cancer multidisciplinary team (n=33) and a breast cancer consumer (n=1) to establish clinically relevant and appropriate data for presentation and the visualization requirements for a dashboard. A series of fortnightly meetings over 6 months with an Advisory Committee (n=10) occurred to inform and refine the development of a static mock-up dashboard. This mock-up was then presented to representatives of the multidisciplinary team (n=3) to get preliminary feedback about the design and use of such dashboards. Feedback from these presentations was reviewed and used to inform the development of the interactive prototypes. A structured evaluation was conducted on the prototypes, using Think Aloud Protocol and semistructured interviews with representatives of the multidisciplinary team (n=5)., Results: Lymphedema was selected as a clinically relevant area for the prototype dashboards. A qualitative evaluation is reported for 5 health professionals. These participants were selected from 3 specialties: surgery (n=1), radiation oncology (n=2), and occupational therapy (n=2). Participants were able to complete the majority of tasks on the dashboard. Semistructured interview themes were categorized into engagement or enthusiasm for the dashboard, user experience, and data quality and completeness., Conclusions: Findings from this study constitute the first report of a co-design process for creating a lymphedema dashboard for breast cancer health professionals. Health professionals are interested in the use of data visualization tools to make routinely collected clinical data more accessible. To be used effectively, dashboards need to be reliable and sourced from accurate and comprehensive data sets. While the co-design process used to develop the visualization tool proved effective for designing an individual patient dashboard, the complexity and accessibility of the data required for a cohort dashboard remained a challenge., (©Anna Janssen, Candice Donnelly, Judy Kay, Peter Thiem, Aldo Saavedra, Nirmala Pathmanathan, Elisabeth Elder, Phuong Dinh, Masrura Kabir, Kirsten Jackson, Paul Harnett, Tim Shaw. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 21.04.2020.)

The behavior characterizing choice response decision-making was studied in monkeys to provide background information for ongoing neurophysiological studies of the neural mechanisms underlying saccadic choice decisions. Animals were trained to associate a specific color from a set of colored visual stimuli with a specific spatial location. The visual stimuli (colored disks) appeared briefly at equal eccentricity from a central fixation position and then were masked by gray disks. The correct target association was subsequently cued by the appearance of a colored stimulus at the fixation point. The animal indicated its choice by saccading to the remembered location of the eccentric stimulus, which had matched the color of the cue. The number of alternative associations (NA) varied from 1 to 4 and remained fixed within a block of trials. After the training period, performance (percent correct responses) declined modestly as NA increased (on average 96, 93 or 84% correct for 1, 2 or 4 NA, respectively). Response latency increased logarithmically as a function of NA, thus obeying Hick's law. The spatial extent of the learned association between color and location was investigated by rotating the array of colored stimuli that had remained fixed during the learning phase to various different angles. Error rates in choice saccades increased gradually as a function of the amount of rotation. The learned association biased the direction of the saccadic response toward the quadrant associated with the cue, but saccade direction was always toward one of the actual visual stimuli. This suggests that the learned associations between stimuli and responses were not spatially exact, but instead the association between color and location was distributed with declining strength from the trained locations. These results demonstrate that the saccade system in monkeys also displays the characteristic dependence on NA in choice response latencies, while more basic features of the eye movements are invariant from those in other tasks. The findings also provide behavioral evidence that spatially distributed regions are established for the sensory-to-motor associations during training which are later utilized for choice decisions.

Cognitive judgments about an object's location are distorted by the presence of a large frame offset left or right of an observer's midline. Sensorimotor responses, however, seem immune to this induced Roelofs illusion, with observers able to accurately point to the target's location. These findings have traditionally been used as evidence for a dissociation of the visual processing required for cognitive judgments and sensorimotor responses. However, a recent alternative hypothesis suggests that the behavioral dissociation is expected if the visual system uses a single frame of reference whose origin (the apparent midline) is biased toward the offset frame. The two theories make qualitatively distinct predictions in a paradigm in which observers are asked to indicate the direction symmetrically opposite the target's position. The collaborative findings of two laboratories clearly support the biased-midline hypothesis.

History and Clinical Findings: An 18-month-old infant was admitted for a suspected bacterial hand infection that had developed within 2 days. Examination demonstrated multiple vesicles with erythema involving the dorso-ulnar aspect of the thumb. The infant was in a good condition, had no constitutional symptoms and a history of gingivo-stomatitis 6 months ago., Examinations: The diagnosis of herpes simplex infection was based on the history and the clinical findings., Treatment and Course: Treatment consisted of dry dressings, and over the next 3 weeks, the lesion healed without scarring., Conclusion: Herpes simplex virus infection of the hand is uncommon, often misdiagnosed and therefore overtreated or inadequately treated. Usually the diagnosis can be made from history and clinical findings. In general, the infection is managed conservatively. Treatment by incision and drainage is contraindicated.

A 52-year-old man had small yellowish, striated or reticular papules since the age of 5 years. These appeared first on the large flexures, and later on the neck, abdomen, penis and the mucosa of the lips. He developed angina at the age of 47 years. A bypass operation, however, did not lead to complete regression of cardiac symptoms. Four years later, the vision in his right eye deteriorated because of arterial occlusion, and the patient was treated with laser coagulation; he was started on long-term treatment with acetylsalicylic acid (250 mg/d) and calcium dobesilate (1,500 mg/d). Despite this, the vision in his left eye also deteriorated progressively. Fundoscopy revealed bilateral pigmentary changes in the macular region, variations in the retinal arterial diameters and "angioid streaks". Pulses were absent in the right radial artery, the left posterior tibial artery and both dorsalis pedis arteries, but there were no trophic changes or symptoms. The serum total cholesterol (246 mg/dl), triglycerides (177 mg/dl) and LDL-cholesterol (193 mg/dl) were only slightly elevated. The diagnosis of pseudoxanthoma elasticum with typical changes in the elastic fibres was confirmed by elastin staining in a biopsy from one of the lesions.

SK&F 105.685 (N,N-dimethyl-8,8-dipropyl-2-azaspiro[4.5]decane-2-propanamine+ ++ dihydrochloride) is a novel azaspirane with beneficial activity in rat models of adjuvant-induced arthritis and experimental autoimmune encephalomyelitis as well as in the murine lupus model. The mechanism of action in these models appears to be the induction of non-specific suppressor cell activity which is measured by the ability of cells from treated animals to partially inhibit the proliferative response of lymphocytes from control animals to concanavalin A (ConA) in a co-culture assay. In this study we have shown that oral administration of 0.1-3 mg/kg/day of SK&F 105.685 to purebred beagle dogs induced suppressor cell activity in the spleen and bone marrow but not in the peripheral blood. In vitro, SK&F 105.685 partially suppressed the proliferative response of dog splenocytes to the mitogens phytohemagglutinin (PHA), ConA and, to a lesser extent, pokeweed mitogen (PWM). Peripheral blood lymphocytes (PBLs) differed from spleen cells in their susceptibility to suppression by SK&F 105.685. While the PWM and ConA responses of PBLs and spleen cells showed similar levels of inhibition, the PHA response of PBLs, in marked contrast to spleen cells, was resistant to suppression by the compound. Our results show that the immunoregulatory effects of SK&F 105,685 are not limited to rodents and that suppressor cell activity in dogs is induced quickly and by relatively low doses of the compound.

Recombinant soluble CD4 (sT4) has been shown to inhibit infectivity of HIV. Because of the role CD4 plays in the interaction of T-helper lymphocytes and cells bearing MHC Class II antigens, a potential adverse effect of therapy with sT4 is interference with lymphocyte function. To address this issue, we studied the effects of sT4 on mitogen-mediated blastogenesis, mixed lymphocyte reactions, and delayed type hypersensitivity reactions (DTH) in cynomolgus monkeys. We found no evidence of sT4-mediated suppression on the in vitro response to concanavalin A, phytohemagglutinin or pokeweed mitogen in 2-way mixed lymphocyte reactions, either when sT4 was added to the cultures or when cells were obtained 3 hr after drug administration from animals that received up to 100 mg/kg as an intravenous bolus. Furthermore, we also found no effect of sT4 on lymphocyte subsets or on the ability of monkeys to respond to dinitrochlorobenzene (DNCB)-mediated DTH. Because of the high degree of conservation of CD4 and MHC Class II antigens across the macaque-human barrier, these data suggest that soluble CD4-like molecules are unlikely to be immunosuppressive in humans.

The CD4 cell surface glycoprotein which is expressed primarily by a subset of T lymphocytes plays a key role in normal immune responses. In the immunopathogenesis of AIDS, it serves as the high-affinity receptor for HIV, facilitating viral attachment and entry into CD4+ cells. As such, the truncated soluble form of this molecule (sT4) has been proposed as a therapeutic drug for the treatment of AIDS whereby it would act as decoy for viral entry into cells or facilitate elimination of soluble viral envelope glycoprotein. In a study designed to look at the effect of sT4 on immune function, sT4 was administrated to experimentally naive primates. In this report, we show that administration of sT4 to cynomolgus macaque monkeys over a period of up to 3 weeks results in antibody responses with specificities for human CD4 molecules. Antisera thus generated bound sT4 and cell surface CD4 expressed on human T lymphocytes but failed to bind to cynomolgus lymphocytes. These antibodies caused no apparent adverse effects on normal immune functions of the cynomolgus macaques. We conclude from these data that the antibody response to soluble CD4 in cynomolgus monkeys is directed at determinants present on human CD4 but absent on monkey CD4. The restricted xenogeneic specificity of the antibody response indicates that soluble CD4 may not be highly immunogenic in syngeneic hosts. The present study also shows that these antibodies can block HIV-induced syncytium formation indicating that the antibodies bind to regions on the CD4 molecule close to the HIV-env gp120 binding site. The gp120 binding site, which resides within the N-terminal V1 domain of CD4, encompasses a region which corresponds to the complementarity determining regions (CDRs) of immunoglobulins. The CDR-like regions of CD4-V1 manifest the greatest species divergence, are tolerant to experimental in vitro mutagenesis, and generate the predominant antibody response in mice immunized with human CD4 indicating that differences in the V1 sequence between human and other non-human primates may localize to this regions.

Immunotoxicologic testing of drug candidates and environmental contaminants is of growing importance. Cutaneous delayed type hypersensitivity (DTH) is a convenient way of testing immune function in vivo. However, DTH testing must not interfere with interpretation of other relevant parameters. We have evaluated the effects of sensitization and challenge with dinitrochlorobenzene (DNCB) on clinical parameters routinely evaluated in toxicity testing and on lectin-mediated blastogenesis. Female cynomolgus monkeys were sensitized to DNCB with 4 daily applications of DNCB in acetone to the skin of the axilla. Fifteen days later, the monkeys were challenged for DTH by applying DNCB to the antecubital skin. Skin fold thickness was measured and the macroscopic appearance of the challenge site was scored 24 and 48 hr after challenge. All 5 monkeys were successfully sensitized to DNCB. There was a significant increase in the mean skin fold thickness (compared to pre-challenge thickness) of 2 mm at 24 hr and 1 mm at 48 hr (p less than 0.001). The clinical score of the challenge site was also increased. Histologic examination of the sensitization and challenge sites from a second group of monkeys exposed to DNCB in an identical manner showed the perivascular inflammatory cell infiltrate typical of DTH. Evaluation of hematologic parameters at days 7, 14, and 21 revealed no change in the erythron at any interval and a mild decrease in total WBC, neutrophil and lymphocyte counts on day 7 in 4/5 monkeys. The WBC parameters remained within the normal range and returned to pre-sensitization values at the later intervals.(ABSTRACT TRUNCATED AT 250 WORDS)

Owing to the large differences in reported values for beta-adrenergic receptor numbers and binding affinity in normal leukocytes, we undertook a systematic re-examination of the binding of two widely used beta antagonists, (-)-[3H]dihydroalprenolol (DHA) and (+/-)-[125I]iodohydroxybenzylpindolol (HYP), to intact normal mononuclear (MN) leukocytes and polymorphonuclear (PMN) leukocytes and membrane preparations. Assays were conducted in the presence and absence of chloroquine, which has been proposed recently to eliminate ligand uptake into a non-receptor cell compartment such as lysosomes. The binding curves relating radioligand concentration to specific sitesper intact cell were biphasic. At high (10-24 nM) (-)-DHA ligand concentration in the absence of chloroquine, a large number (20,000-60,000 sites/cell) of low affinity (Kd 12-15 nM) stereospecific binding sites were detected in both cell types. This class of binding sites was eliminated by 10 microM chloroquine not only in PMN cells but also in the lysome-poor MN cells (greater than or equal to 90% lymphocytes), leaving 2000-3000 specific high affinity (-)-DHA sites/cell. In the absence of chloroquine, comparably low numbers of specific high affinity binding sites/cell were also obtained by the use of appropriately low concentrations of (-)-DHA or (+/-)-HYP (800 pM or less). However, even at these low radioligand concentrations chosen to measure high affinity specific binding, the addition of 10 microM chloroquine produced a moderate reduction in the number of sites/cell, without a detectable change in the apparent Kd. Mean (+/- S.E.M.) site numbers obtained in the presence of chloroquine were: 1331 +/- 100 sites/MN cell and 1135 +/- 129 sites/PMN cell (Kd 143-153 pM) using (-)-DHA; and 1487 +/- 210 sites/MN cell and 1065 +/- 69 sites/PMN cell [avg. Kd(+/-) 224-274 pM] using (+/-)-HYP. Chloroquine had no effect on agonist-stimulated cAMP production but produced an apparent increase in the effectiveness of (-)-propranolol as an inhibitor of DHA binding. Competition studies on the binding of DHA and HYP with zinterol and practolol confirmed that the receptor was of the beta 2-subtype for both MN and PMN cells. The detection of a moderately larger number of high affinity binding sites at saturation (Scatchard analysis) by (+/-)-HYP than by (-)-DHA was a consistent finding with either intact cells or membranes, with or without chloroquine. The possible overestimation of receptor numbers by a racemic ligand such as (+/-)-HYP is discussed and leads us to favor the use of a pure stereoisomer such as (-)-DHA. A system employing 800 pM (-)-[3H]DHA, 1 microM (-)-propranolol and 10 microM chloroquine with intact MN and PMN cells yielded reproducible and plausible results. Our values for beta-adrenergic receptor numbers of intact MN and PMN cells and membranes are compared to others in the literature.

Although gold compounds are recognized as effective immunomodulatory agents in the treatment of rheumatoid arthritis (RA), their mechanism of action is controversial. We examined the effect of longterm treatment with 0.6-3.6 mg/kg auranofin (AF) per os q24h, or intramuscular injections of 0.5-2.0 mg/kg gold sodium thiomalate (GSTM) q3d, on 13 variables of immune function in normal dogs. None of the changes in these variables previously attributed to treatment with AF or GSTM could be demonstrated after 6-7 years' dosing. As gold compounds are effective in treating spontaneous RA in dogs, these proposed actions may not be responsible for the remittive effects of chrysotherapy in this disease.

Although the dog is used extensively as a model for toxicologic investigation, few practical techniques for assessing immunotoxicity in this species have been reported. We have adapted techniques for assessing peripheral blood monocyte (PBM) function in the dog. Methods for isolating PBM were compared; a technique employing hypertonic conditioning followed by density gradient centrifugation, which resulted in greater than 90% purity and a greater yield of PBM than that obtained with other previously reported methods is described, along with methods for measuring antibody-dependent cellular cytotoxicity (ADCC) and the production of prostaglandin E2 (PGE2) and superoxide anion (O2-). An assay for the measurement of interleukin-1 (IL-1), based on its ability to induce interleukin-2 (IL-2) production by the EL-4 mouse thymoma line in the presence of the calcium ionophore A23187, was examined. Together, these assays provide the tools to better define drug or chemical effects on the mononuclear phagocyte system (MPS) of this important animal model.

Although enhanced sensitivity of erythrocytes to complement-mediated lysis is a hallmark of paroxysmal nocturnal hemoglobinuria (PNH), subpopulations of erythrocytes in such patients vary significantly in this respect. One PNH erythrocyte subpopulation (termed type III) comprises exquisitely sensitive cells, whereas type II PNH erythrocytes are intermediate in complement sensitivity between PNH type III and normal human erythrocytes. Differences in the action of the terminal complement components that would account for the differing lytic behavior of types II and III PNH erythrocytes have been proposed but not directly demonstrated. The present studies, making use of carefully selected cases with pure populations of type II or type III erythrocytes, confirm a prior observation that antibody-coated PNH erythrocytes of both types II and III display comparably supranormal C3 binding in whole human serum. However, when lysis was induced by the isolated C5b-9 membrane attack mechanism, bypassing the requirement for C3 binding, only type III PNH cells exhibited greater than normal lysis. This finding suggests that type III PNH erythrocytes have an additional membrane abnormality not present in type II cells. Thus, the differing lytic behavior of these two cell types in whole serum may reflect the additive effects on type III cells of both exaggerated C3 binding and enhanced sensitivity to C5b-9, whereas the more moderate lysis of type II PNH cells may be determined mainly or entirely by the earlier-acting mechanism producing augmented C3 binding. The failure of guinea pig C8 and C9, as opposed to human C8 and C9, to reveal the true lytic sensitivity of PNH-III E in our earlier study is illustrated, and its implications briefly discussed.

Investigating the immunotoxic potential of candidate drugs as part of a preclinical safety evaluation poses several problems. These include the need for practical, validated tests, the difficulty in establishing the toxicologic significance of positive findings, and a poor understanding of the predictive value such findings hold for drug effects in man. A key component of this investigation is the toxicologic profile generated through preclinical toxicity and safety studies. As this "routine" assessment becomes increasingly comprehensive and sophisticated, most toxicologically significant drug-associated effects are revealed. Such findings may serve as "triggers" for investigating possible immune mechanisms. Decisions to test specifically for immunotoxicity may also be influenced by the molecular structure and pharmacologic profile of the compound, as well as the intended use of the drug. Examples of such indications and follow-up studies are discussed in this review. We are presently poorly equipped to effectively screen drugs indiscriminately for an immunotoxic potential. We are better prepared, however, to investigate whether a drug-associated change is due to an adverse effect on the immune system. This problem-oriented approach to immunotoxicology challenges us as diagnosticians and immunopathologists, and requires a close working relationship among the toxicologic pathologist, the basic immunologist, the immunopharmacologist, and the clinician.

A prototype of a cross-flow membrane plasmapheresis system was tested for its safety and efficacy in normal donors. 550 ml of plasma can be harvested in less than 1 h. The procedure appears to be safe for the donor. No significant alterations in donor hematological, coagulation, or biochemical values were obtained after the procedure compared to the predonation levels. Changes in the classical and alternate complement pathways were studied serially by analysis of functional hemolytic titers, C3 and C4 levels, and C3 and factor B cleavage products. No firm evidence of complement activation by the polysulfone filtration cell membrane was found.

A routine health screen of a 7 1/2-year-old female Beagle participating as a control in a long-term study revealed thrombocytopenia. Immune thrombocytopenia was diagnosed on the basis of regenerative bone marrow findings (high number of megakaryocytes) and evidence of antiplatelet antibodies. Treatment with prednisone at dosages up to 1 mg/kg of body weight every 12 hours resulted in limited improvement, with relapses of severe thrombocytopenia thwarting attempts to taper the corticosteroid, and was further complicated by side effects of the drug. Addition of danazol to the treatment regimen (5 mg/kg, q 12 h) resulted in remission of the thrombocytopenia within 2 weeks and permitted the dosage of prednisone to gradually be reduced and discontinued. Associated with this response was a decrease in platelet-associated IgG to values comparable with control samples.

Human lysosomes were isolated from normal peripheral blood leukoyctes and characterized by electron microscopy, enzyme analysis, and assays for DNA and RNA. Stored sera from 37 unselected patients with systemic lupus erythematosus (SLE), including active and inactive, treated and untreated cases, were tested in complement fixation (CF) reactions with these lysosome preparations. 23 SLE sera exhibited positive CR reactions, as did sera from two patients with "lupoid" hepatitis. The seven SLE sera with strongest CF reactivity also demonstrated gel precipitin reactions with lysosomes. Neither CF nor precipitin reactions with lysosomes were observed with normal sera or with sera of patients with drug-induced lupus syndrome, rheumatoid arthritis (RA), polymyositis, or autoimmune hemolytic anemia. By several criteria the antilysosome CF and precipitin reactions of SLE sera cound not be attributed to antibody to DNA, RNA, or other intracellular organelles. The lysosomal component reactive with SLE sera in CF assays was sedimentable at high speed and is presumably membrane associated. The CF activity of two representative SLE sera was associated with IgG globulins by Sephadex filtration. A search for lysosomal antigen in SLE and related disorders was also made. By employing rabbit antiserum to human lysosomes in immunodiffusion, a soluble lysosomal component, apparently distinct from the sedimentable (membrane-associated) antigen described above, was identified in serum, synovial fluid, or pleural fluid from patients with SLE, RA, ankylosing spondylitis, and leukemoid reaction. An antigenically identical soluble component reactive with the rabbit antiserum could be released in vitro from intact lysosomes by repeated freeze-thaw cycles..

Cephalosporin treatment in man has been associated with a low incidence of hemolytic anemia, thrombocytopenia, and neutropenia; some cases have been shown to be immune-mediated. This triad of blood dyscrasias was also demonstrated in our laboratory in a series of toxicity studies in dogs of two cephalosporin compounds, cefonicid and cefazedone; these studies provided evidence for drug-associated immune hemolytic anemia, based on conventional laboratory tests. To further investigate possible immune mechanisms of the cephalosporin-induced cytopenias, we measured erythrocyte-associated, platelet-associated (PAIgG), and serum antineutrophil IgG over the course of cephalosporin treatment, using highly sensitive 125I-staphylococcal protein A (SPA) assays, as well as the direct antiglobulin test; we compared these findings with the hematologic changes. Intravenous treatment with high doses of cefazedone (540 mg/kg/day, increased to a maximum of 840 mg/kg/day for 4 months or until hematologic effects were evident) resulted in a high incidence of anemia (7/14), thrombocytopenia (11/14), and neutropenia (7/14). Of the affected dogs examined, 6/7 with anemia, 9/9 with thrombocytopenia, and 7/7 with neutropenia showed increased levels of the respective cell-associated antibody, compared with untreated controls. Unaffected dosed animals generally did not show these changes. In 3/3 dogs examined following remission of thrombocytopenia, PAIgG returned to levels comparable with controls; as one of these dogs suffered a relapse, increased PAIgG was again observed. Animals sacrificed during cytopenic episodes showed cytologic and histologic evidence of increased hemophagocytosis. We conclude that antibody-mediated blood cell destruction contributes to all three cephalosporin-induced cytopenias in the dog.