The utilization of the Welfare Quality® assessment for determining laying hen condition across three housing systems.

The Welfare Quality(®) Assessment protocol for poultry ( WQA: ) provides animal-based measures allowing welfare comparisons across farms and housing systems. It was used to compare Lohmann LSL Classic White hens housed in an enriched colony ( EC: ), aviary ( AV: ), and conventional cage system ( CC: ) on a commercial farm over 2 flock cycles. Hens (n = 100/system) were scored on a variety of measures. A baseline measurement was made at placement at 19 wk of age for 1 flock, since AV hens had been reared in an aviary pullet facility ( AVP: while EC and CC hens were reared in a conventional pullet facility ( CCP: ). Hens in all systems were then assessed at 52 and 72 wk of age. Necropsies were performed on all mortalities 1 wk before and after the WQA sampling. WQAs were analyzed using Mann-Whitney U and Kruskal-Wallis tests for prevalence and Fisher's exact tests for severity. There was an effect of rearing, with AVP having shorter claws (P = 0.01), dirtier feathers (P = 0.03), and more keel abnormalities (P < 0.0001) than CCP at placement. For the hens, there were several significant housing system effects across flocks and age periods (all P ≤ 0.05). AV and EC hens had more keel abnormalities than CC hens. They also had fewer foot abnormalities than CC hens, although those in AV hens were more severe. AV hens had consistently dirtier feathers than EC and CC hens. While AV hens had the best overall feather cover, feather loss patterns suggested that loss was due to head pecking for AV, whereas in EC and CC it was due to cage abrasion. The necropsy findings and the WQA results were similar, except that the WQA failed to find enteritis at 19 wk, although it was detected in the necropsies during this sampling period. These results show that the WQA is a useful tool for detecting hen condition differences across housing systems.

Hen welfare in different housing systems.

Egg production systems have become subject to heightened levels of scrutiny. Multiple factors such as disease, skeletal and foot health, pest and parasite load, behavior, stress, affective states, nutrition, and genetics influence the level of welfare hens experience. Although the need to evaluate the influence of these factors on welfare is recognized, research is still in the early stages. We compared conventional cages, furnished cages, noncage systems, and outdoor systems. Specific attributes of each system are shown to affect welfare, and systems that have similar attributes are affected similarly. For instance, environments in which hens are exposed to litter and soil, such as noncage and outdoor systems, provide a greater opportunity for disease and parasites. The more complex the environment, the more difficult it is to clean, and the larger the group size, the more easily disease and parasites are able to spread. Environments such as conventional cages, which limit movement, can lead to osteoporosis, but environments that have increased complexity, such as noncage systems, expose hens to an increased incidence of bone fractures. More space allows for hens to perform a greater repertoire of behaviors, although some deleterious behaviors such as cannibalism and piling, which results in smothering, can occur in large groups. Less is understood about the stress that each system imposes on the hen, but it appears that each system has its unique challenges. Selective breeding for desired traits such as improved bone strength and decreased feather pecking and cannibalism may help to improve welfare. It appears that no single housing system is ideal from a hen welfare perspective. Although environmental complexity increases behavioral opportunities, it also introduces difficulties in terms of disease and pest control. In addition, environmental complexity can create opportunities for the hens to express behaviors that may be detrimental to their welfare. As a result, any attempt to evaluate the sustainability of a switch to an alternative housing system requires careful consideration of the merits and shortcomings of each housing system.

Common Diseases of Michigan Gamebirds: A Retrospective Study.

Michigan has abundant resources for outdoor activity including upland gamebird hunting in the wild and on licensed hunting preserves. Due to the popularity of hunting, Michigan had a thriving gamebird industry before the economic downturn of 2008/2009. After the economic downturn, the number of gamebird preserves decreased. To understand the health issues faced by captive gamebird raisers while the industry was thriving, a 25-year retrospective study of gamebird submissions to the Michigan State University Veterinary Diagnostic Laboratory from 1983 through 2008 was undertaken. Although pheasants, quail, partridges, grouse, and mallard ducks were raised, pheasants greatly outnumbered all other gamebird species, both in numbers and submissions, and quail were the next most predominant species. Causes for submission included parasitic, bacterial, viral, and miscellaneous causes. Parasitic diseases were predominant, with coccidiosis being the leading diagnosis in pheasants and partridges and Capillaria spp. infestation of the crop prevailing in quail. Bacterial diseases were the next most predominant affliction, with clostridial enteritis, both necrotic and ulcerative, in quail, and a variety of bacterial diseases were found in pheasants and partridges. Rotaviral enteritis and adenovirus were the most prevalent viral diseases in pheasants, with adenovirus being the predominant viral disease in quail and paramyxovirus the most prevalent in partridges. From these findings, we conclude that gamebird submissions should be closely screened for parasitic diseases and the diagnosis confirmed at necropsy through scraping and examination of affected tissues.

Reporte de caso­Enfermedades comunes de aves de caza en Michigan: Un estudio retrospectivo. Michigan tiene abundantes recursos para la actividad al aire libre, incluida la caza de aves silvestres en tierras altas silvestres y en cotos de caza autorizados. Debido a la popularidad de la caza, Michigan tenía una próspera industria de aves de caza antes de la recesión económica de los años 2008/2009. Después de la recesión económica, el número de reservas de aves de caza disminuyó. Para comprender los problemas de salud que enfrentan los criadores de aves de caza en cautiverio mientras la industria prosperaba, se realizó un estudio retrospectivo de 25 años de los casos de diagnóstico de aves de cacería remitidos al Laboratorio de Diagnóstico Veterinario de la Universidad Estatal de Michigan desde el año 1983 hasta el 2008. Aunque se criaron faisanes, codornices, perdices, urogallos y ánades reales, los faisanes superaron en gran medida a todas las demás especies de aves de caza, tanto en número como en casos clínicos y la codorniz fue la segunda especie más predominante. Las causas de envío de casos clínicos incluyeron infecciones parasitarias, bacterianas, virales y diversas. Predominaron las enfermedades parasitarias, siendo la coccidiosis el principal diagnóstico en faisanes y perdices y la infestación en el buche por Capillaria spp. fue predominante en codornices. Las enfermedades bacterianas fueron el segundo problema más predominante, con enteritis por clostridios, tanto necrótica como ulcerativa, en codornices, y una variedad de enfermedades bacterianas se encontraron en faisanes y perdices. La enteritis por rotavirus y los adenovirus fueron las enfermedades virales más prevalentes en los faisanes, siendo el adenovirus la enfermedad viral predominante en la codorniz y el paramixovirus la más prevalente en las perdices. A partir de estos hallazgos, concluimos que las presentaciones de aves de caza deben ser examinadas de cerca para detectar enfermedades parasitarias y el diagnóstico debe confirmarse en la necropsia mediante de raspados y examen de los tejidos afectados.

Epidemiologic investigation of Riemerella anatipestifer in a commercial duck company by serotyping and DNA fingerprinting.

A commercial duck company that raises approximately two million Pekin ducks per year experienced an outbreak of Riemerella anatipestifer (RA) on nine farms over a 1-yr period. Owing to concerns that the bacteria was being spread from farm to farm, an investigation using serotyping and DNA fingerprinting was performed. The results revealed that there were three different strains of RA involved in the outbreak. One strain was spread from one farm to six other farms, while another strain from the same farm was spread to two other farms. These findings add additional proof of the value of DNA fingerprinting in disease outbreak investigations and further support the importance of implementing biosecurity protocols to stop the spread of disease-causing organisms.

Development and application of an immunohistochemical staining technique to detect avian polyomaviral antigen in tissue sections.

An immunohistochemical staining technique was developed to detect polyomaviral antigens of budgerigar fledgling disease in formalin-fixed tissue sections. This technique used an indirect avidin-biotin, alkaline phosphatase labeling system with a mixture of monoclonal antibodies developed against the virus major capsid protein. The staining technique was applied retrospectively to 24 avian accessions which were originally diagnosed as budgerigar fledgling disease or avian polyomavirus infection based on microscopic findings including typical intranuclear inclusions. Immunohistochemical staining resulted in positive reactions in some tissues from 17 of 24 cases. The tissues most frequently containing typical intranuclear inclusions or positive immunohistochemical staining were the spleen, liver, and kidney. Neither of the 2 nonpsittacine cases was positive immunohistochemically. This technique may be used wither as a rapid test on routinely processed diagnostic samples to confirm the presence of avian polyomavirus or for pathogenesis research studies.

Effect of route of vaccination on the prevention of infectious laryngotracheitis in commercial egg-laying chickens.

Commercial egg-laying chickens were vaccinated for infectious laryngotracheitis (ILT) with one of five commercially available vaccines (designated A, B, C, D, and E) on five separate farms by either eyedrop (e), spray (s), or double dose in the water (w) method. Groups were identified by the vaccine designation and the method of vaccination. Birds from the test groups were transferred to an isolation facility and challenged intratracheally 3 wk after vaccination. The remaining birds were given a second vaccination with the original chicken embryo origin vaccine by spray or a chicken embryo origin vaccine if the first vaccine was of tissue culture origin. After challenge, birds were monitored for clinical signs. Those surviving were euthanatized on day 6 postchallenge, and tissues and blood were collected for histopathology, virus isolation, and serology. On the basis of histopathology and enzyme-linked immunosorbent assay (ELISA) results, after one vaccination, all chickens given vaccines by eyedrop were provided better protection than nonvaccinated controls (CTLs). Birds in groups Bs and Ds had lower microscopic lesion scores whereas only birds given Bs had higher ELISA titers than CTLs. Birds in groups As and Cs and groups Bw birds taken from the rear of the barn (r) had microscopic lesion scores that were no different from those of CTLs. These same birds in addition to vaccine Ds had ELISA titers no different from those of CTLs. Of all vaccines, only A given by eyedrop or spray produced higher virus isolation titers than those of CTLs. The remainder of the vaccines produced virus isolation titers that were no different from those of CTLs. After two vaccinations, all groups had lower microscopic lesion scores than CTLs. Only Bw birds from the middle of the barn Bs, EeDs, and AsAs had virus isolation results that were higher than those of CTLs. Only groups BwrBs, CsCs, and DsDs had ELISA titers no different from those of controls. These results suggest that a priming vaccination followed by a booster dose offers better protection against ILT than a single vaccination alone. Vaccine application by eyedrop provides more uniform protection if only one vaccination is given, whereas spray vaccination may serve as an alternative method of vaccination for birds receiving two doses of vaccine.

Cellular response of the respiratory tract of chickens to infection with Massachusetts 41 and Australian T infectious bronchitis viruses.

Cellular response of chickens to infection with infectious bronchitis virus (IBV) was investigated by lavage of the respiratory tract of five 2-week-old specific-pathogen-free (SPF) chickens at 2, 8, 24, 48, 72, and 96 hours postinfection (PI) with either Massachusetts 41 (IBV-M41) or Australian T (IBV-T) IBV. Tissue response was monitored by microscopic examination of trachea and lung from five non-lavaged infected chickens collected at the same intervals. The total number of cells recovered by lavage from IBV-M41-infected chickens was dramatically higher than the total number recovered from IBV-T-infected chickens and uninfected controls. By contrast, the total number of cells recovered from IBV-T-infected chickens was no higher than that of the uninfected chickens. Heterophils constituted the majority of inflammatory cells recovered from both IBV-M41-infected and IBV-T-infected chickens. Heterophil numbers in IBV-M41-infected chickens paralleled total cell-number recovery, whereas heterophil numbers in IBV-T-infected birds were no higher than those in uninfected chickens. The number of lymphocytes recovered from IBV-M41-infected chickens increased 72 hours PI and continued to increase for the duration of the study. Lymphocyte numbers in IBV-T-infected chickens exceeded those in uninfected chickens only at 96 hours PI. The number of lavage macrophages in IBV-M41-infected chickens increased earlier than the number of lymphocytes but later reached a plateau. IBV-T macrophage numbers did not exceed those of uninfected chickens. Tissue damage occurred most consistently in the trachea and occurred when lavage heterophil numbers were rising or at their peak. Lavage cell recovery and composition reflected tracheal mucosa inflammatory cell infiltrate.

Light microscopic and ultrastructural characterization of cells recovered by respiratory-tract lavage of 2- and 6-week-old chickens.

This study characterized the cell population recovered by respiratory-tract lavage of 57 two-week-old and 59 six-week-old specific-pathogen-free chickens as a prerequisite to study the response of the avian respiratory tract to infectious agents. The respiratory tract of each bird was lavaged through the trachea with a series of three lavages of 10 ml of room-temperature, neutral phosphate-buffered saline per lavage. The three lavages per bird were pooled for analysis. Total recovery volumes were measured, lavage fluid cellularity was determined, and a 200-cell differential count of non-erythrocyte cells was performed. Lavage fluid recovery was greater from 2-week-old birds (91.3 percent) than from 6-week-old birds (86.3 percent). Total cells recovered were greater for 6-week-old chickens (6.79 x 10(5)) than for 2-week-old chickens (5.03 x 10(5)). Cells of epithelial origin included squamous cells, goblet cells, and both ciliated and non-ciliated columnar epithelial cells. Cells of non-epithelial origin consisted of heterophils, lymphocytes, macrophages, eosinophils, basophils, and erythrocytes. Cells of epithelial origin were the predominant cell type recovered from the 2-week-old chickens, followed by heterophils. In 6-week-old chickens, heterophils were the predominant cell type recovered, followed by cells of epithelial origin. In descending order of prevalence, the remainder of cell types recovered from chickens of both ages were lymphocytes, macrophages, eosinophils, and basophils.

Diagnosis of eastern equine encephalitis by immunohistochemistry in two flocks of Michigan ring-neck pheasants.

The diagnosis of eastern equine encephalitis (EEE) virus infection in avian species is relatively difficult when compared with other species. There are no characteristic histologic lesions in the avian brain that would serve to distinguish EEE from infections with, for example, Newcastle disease or highly pathogenic avian influenza virus. Traditionally, virus isolation (VI) and/or hemagglutination inhibition (HI) has been used for a definitive diagnosis of EEE in birds. Recently, we developed an immunohistochemistry (IHC) technique for confirmatory diagnosis of EEE infection in equine brain. This test also detected EEE virus in formalin-fixed avian brain. VI confirmed IHC finding in two cases of EEE in ring-neck pheasants. IHC is a rapid, sensitive test for confirming and differentiating a histopathologic diagnosis of EEE in avian species and should be considered as an alternative test to VI or HI.

Furazolidone-associated cardiomyopathy in two Indiana flocks of ducklings.

Furazolidone (FZ)-induced congestive cardiomyopathy was diagnosed as the cause of high mortality and unthriftiness in two flocks of white pekin ducklings. Cumulative mortality at 7 weeks of age was 10.0-14.4%. Samples of FZ-supplemented feeds fed to flocks 1 and 2 from day 1 to day 14 had 140 and 150 mg FZ/kg, respectively. Both flocks had various degrees of water restriction. Clinically, the ducklings had dyspnea, incoordination, and abdominal distention. Necropsy findings included pulmonary edema and congestion, ascites, atrophic congested livers covered with sheets of fibrin, and cardiac enlargement with biventricular dilatation. Cardiac alterations were minimal by light microscopy. Ultrastructurally, scattered myocytes had myofibrillar lysis. These outbreaks occurred following intake of FZ at therapeutic dosages and emphasize the high susceptibility of young ducklings to FZ cardiotoxicity.

Effect of cytoxan-induced heteropenia on the response of specific-pathogen-free chickens to infectious bronchitis.

Epithelial damage in infectious bronchitis occurs early in the disease process. Heterophil infiltration into the tracheal mucosa is greatest at that time. To determine the contribution of heterophils to tracheal epithelial damage of infectious bronchitis, eight 3-wk-old specific-pathogen-free chickens were made heteropenic by four daily intramuscular injections of cyclophosphamide at 75 mg/kg body weight. Infection with Massachusetts 41 infectious bronchitis virus was timed to coordinate heteropenia with peak tracheal epithelial damage. Heteropenia was monitored by total leukocyte and differential cell counts of peripheral blood. Tissue damage and heterophil infiltrate were monitored by histopathology of tissues taken at termination of the study. Heteropenic birds had lower peripheral blood and tracheal heterophil numbers than nonheteropenic birds. No difference was found in epithelial damage of heteropenic and nonheteropenic birds. Epithelial damage in infectious bronchitis is most likely due to damage by the virus and not due to the infiltrated heterophils.

Cyclophosphamide (Cytoxan)-induced hematologic alterations in specific-pathogen-free chickens.

Cyclophosphamide (Cytoxan) was given at 75 mg/kg body weight via daily intramuscular injections for 4 days to 3-week-old specific-pathogen-free (SPF) chickens in an attempt to determine if heteropenia could be induced in chickens. Control birds were given a like quantity of phosphate-buffered saline, the diluent for Cytoxan. Peripheral blood heterophil numbers were determined and monitored by total leukocyte and differential cell counts. Birds were grouped in pairs on day 0 based on total leukocyte count. The number of heterophils each bird had on day 0 served as a baseline heterophil count for that bird. Thereafter heterophil numbers were determined on the last day of drug treatment and every other day until blood heterophil numbers were 20% of that bird's baseline heterophil count (heteropenia). The effects of Cytoxan on trachea, lung, liver, kidney, bursa of Fabricius, bone marrow, spleen, and thymus were determined by microscopic examination of those tissues collected the day following heteropenia. Cytoxan had no effect on trachea, lung, liver, kidney, and thymus. Bursa of Fabricius and spleen had decreased amounts of lymphoid aggregates. Bone marrow of Cytoxan-treated chickens was hypocellular. The study was then repeated to determine the reversibility of Cytoxan-induced heteropenia. Cytoxan-treated birds were allowed to recover until blood heterophil numbers equaled or exceeded those of control birds. Cytoxan, through bone marrow suppression, induced a reversible heteropenia that developed between treatment days 10 and 12. In addition, Cytoxan induced a reversible lymphocytopenia between days 4 and 10 and a regenerative anemia between days 8 and 10. The ability to produce heteropenia in SPF chickens will allow the use of a heteropenic model for further study of the heterophil's contribution to the inflammatory response.

Ocular and encephalic toxoplasmosis in canaries.

In this report we describe the lesions produced by the protozoal organism, Toxoplasma gondii, in the eyes and brain of the common yellow canary (Serinus canaria). Nine of 15 birds in a flock were affected with blindness, which developed over a 3-mo span, and two birds developed torticollis. Microscopic alterations within the eye consisted of a nonsuppurative chorioretinitis with large numbers of macrophages that contained the tachyzoite form of T. gondii in the subretinal space, and aggregates of tachyzoites were found in the nerve fiber layer of the retina with and without necrosis. Tissue cysts with bradyzoites were scattered throughout the meninges and neuropil of the cerebrum and cerebellum. Both forms were confirmed by transmission electron microscopy in the eye and brain. Frozen brain samples reacted with T. gondii-specific cat sera in indirect fluorescent antibody tests. The source of infection was hypothesized to be from a stray cat the owner kept that had access to some of the bird feed. Treatment (trimethoprim 0.08 g/ml H2O and sulfadiazine 0.04 g/ml in water for 2 wk) was instituted by the referring veterinarian on the remaining birds. A second treatment regime was given for 3 wk. The owner of the canaries did not return for further treatment.

Effect of antibiotics on in vitro and in vivo avian cartilage degradation.

Antibiotics are used in the livestock industry not only to treat disease but also to promote growth and increase feed efficiency in less than ideal sanitary conditions. However, certain antibiotic families utilized in the poultry industry have recently been found to adversely affect bone formation and cartilage metabolism in dogs, rats, and humans. Therefore, the first objective of this study was to determine if certain antibiotics used in the poultry industry would inhibit in vitro cartilage degradation. The second objective was to determine if the antibiotics found to inhibit in vitro cartilage degradation also induced tibial dyschondroplasia in growing broilers. Ten antibiotics were studied by an avian explant culture system that is designed to completely degrade tibiae over 16 days. Lincomycin, tylosin tartrate, gentamicin, erythromycin, and neomycin sulfate did not inhibit degradation at any concentration tested. Doxycycline (200 microg/ml), oxytetracycline (200 microg/ml), enrofloxacin (200 and 400 microg/ml), ceftiofur (400 microg/ml), and salinomycin (10 microg/ml) prevented complete cartilage degradation for up to 30 days in culture. Thus, some of the antibiotics did inhibit cartilage degradation in developing bone. Day-old chicks were then administered the five antibiotics at 25%, 100%, or 400% above their recommended dose levels and raised until 21 days of age. Thiram, a fungicide known to induce experimental tibial dyschondroplasia (TD), was given at 20 ppm. Birds were then killed by cervical dislocation, and each proximal tibiotarsus was visually examined for TD lesions. The results showed that none of these antibiotics significantly induced TD in growing boilers at any concentration tested, whereas birds given 20 ppm thiram had a 92% incidence rate.

Molecular characterization of Mycoplasma gallisepticum isolates from turkeys.

Mycoplasma gallisepticum was isolated from several turkey flocks at different locations in the United States that were clinically affected with respiratory disease. Five of these isolates from four series of outbreaks had patterns similar to the 6/85 vaccine strain of M. gallisepticum by random amplified polymorphic DNA (RAPD) analysis using three different primer sets, whereas with a fourth primer set (OPA13 and OPA14), only two of the isolates were similar to 6/85. Results obtained by sequencing portions of the pvpA, gapA, and mgc2 genes and an uncharacterized surface lipoprotein gene indicated that the field isolates had DNA sequences that ranged from 97.6% to 100%, similar to the 6/85 results. In some of the outbreaks there was an indirect association with the presence of commercial layers in the area that had been vaccinated with this vaccine strain, but there was no known close association with vaccinated birds in any of the outbreaks. Turkeys were challenged with two of the field isolates and with 6/85 vaccine strain. Turkeys challenged with the field isolates developed respiratory disease with airsacculitis and a typical M. gallisepticum antibody response, whereas birds challenged with 6/85 developed no respiratory signs or lesions and developed only a weak antibody response. Although these isolates were very similar to the 6/85 vaccine strain, it was not possible to prove that they originated from the vaccine strain-it is possible that they could be naturally occurring field isolates.

Clinical and pathologic features of West Nile virus infection in native North American owls (Family strigidae).

Since the initial report of West Nile virus in the northeastern United States in 1999, the virus has spread rapidly westward and southward across the country. In the summer of 2002, several midwestern states reported increased cases of neurologic disease and mortality associated with West Nile virus infection in various native North American owl species. This report summarizes the clinical and pathologic findings for 13 captive and free-ranging owls. Affected species were all in the family Strigidae and included seven snowy owls (Nyctea scandiaca), four great-horned owls (Bubo virginianus), a barred owl (Strix varia), and a short-eared owl (Asio flammeus). Neurologic signs identified included head tilt, uncoordinated flight, paralysis, tremors, and seizures. Owls that died were screened for flaviviral proteins by immunohistochemical staining of formalin-fixed tissues, followed by specific polymerase chain reaction assay to confirm West Nile virus with fresh tissues when available. Microscopic lesions were widespread, involving brain, heart, liver, kidney, and spleen, and were typically nonsuppurative with infiltration by predominantly lymphocytes and plasma cells. Lesions in owls were much more severe than those previously reported in corvids such as crows, which are considered highly susceptible to infection and are routinely used as sentinel species for monitoring for the presence and spread of West Nile virus. This report is the first detailed description of the pathology of West Nile virus infection in Strigiformes and indicates that this bird family is susceptible to natural infection with West Nile virus.

Prevention of Salmonella enteritidis infection in commercial ducklings by oral chicken egg-derived antibody alone or in combination with probiotics.

Ducklings were given egg-derived antibody against Salmonella enteritidis (Ab) in drinking water daily to determine if infection could be prevented. Pekin ducklings in all experimental groups were infected on Day 1 or 5 with 0.7 x 10(6) Salmonella enteritidis (SE). Spleen, liver, and intestine of each bird were collected and cultured on Days 7, 14, 21, and 28. Only livers and spleens were culture positive for SE. Ducklings infected on Day 1 had more SE infections than controls at each observation. Ducklings infected on Day 5 had fewer SE infections than controls on Days 7, 14, and 21. The same experiment was repeated to determine if SE infection could be prevented under production conditions. Only 10 ducks per group were infected with 1.02 x 10(7) SE. In addition to Ab, one group each, infected on Day 1 or 5, received a proprietary probiotic (Pro) daily to determine if Pro was synergistic to Ab. Groups receiving Ab and Pro and infected on Day 1 had fewer birds infected than Ab alone in Day 1-infected birds. Both Day 1-infected groups had more birds infected than controls. Birds infected on Day 5 had fewer ducks infected than controls on Days 7, 14, and 21. Except for Day 14, birds receiving both Ab and Pro and infected on Day 5 had fewer birds infected than Ab alone on Day 21 and 28. Probiotics act synergistically with oral Ab. Oral antibodies may serve as a tool to prevent salmonella infection in poultry.

Plasma-fibrinogen and thromboemboli after myocardial infarction.

In 120 patients with myocardial infarction subsequent non-fatal thromboemboli occurred only in patients in whom plasma-fibrinogen had exceeded 750 mg/dl. It is suggested that patients at risk from thromboembolism after infarction can be identified by monitoring plasma-fibrinogen and that appropriate anticoagulation might reduce morbidity.

Lymphocytotoxic strains of feline leukemia virus induce apoptosis in feline T4-thymic lymphoma cells.

Feline leukemia retrovirus (FeLV) strains with subgroup C env genes kill feline T4 lymphoma 3201 cells by 7 to 12 days after in vitro inoculation, whereas FeLV strains with subgroup A env genes do not. Neither FeLV-A nor FeLV-C kill feline fibroblasts. FeLV-C, but not FeLV-A, is replicated to higher titer by 3201 cells and productive infection precedes death by 3 to 7 days. Transcriptional activity of the FeLV-C long terminal repeat, as assessed by chloramphenicol acetyltransferase activity, is high in feline lymphoid cells but low in feline fibroblasts. Activity of the FeLV-A long terminal repeat is moderate in both cell types. FeLV-C-infected cells form aggregates 1 to 4 days before dying; ultrastructurally, virus particles can be seen approximating the clustered cells. Dying cells demonstrate nuclear condensation, surface blebbing, and fragmentation. DNA fragmentation and laddering compatible with apoptosis occur 1 to 2 days before massive cell death. In FeLV-C-infected 3201 cells, a shift from phospholipid to neutral lipid incorporation of [14C]oleic acid, increases in palmitic acid proportions and decreases in linoleic acid proportions occur 1 to 2 days before peak killing. Exposure of 3201 cells to ultraviolet-inactivated FeLV-KT (200-800 micrograms/10(6) cells) causes cytostasis within 2 days and death within 4 days. Blebbing and nuclear condensation occur but clusters do not form. The induction of programmed cell death in feline thymic lymphoma cells by subgroup C feline retroviruses may be relevant to the pathogenesis of FeLV-induced thymic atrophy, paracortical lymphoid depletion and acquired immunodeficiency in vivo.