Fat digestibility in Equus caballus follows increasing first-order kinetics.

The digestibility of ether extract varies greatly from forages to grains and further to added fats consisting mainly of triglycerides. This variation has been attributed to two main factors, the presence of nonhydrolyzable substances in the ether extract, especially in leafy foods, and the dilution of endogenous fecal fat. A compilation of results from 188 equine digestion balance observations on five basal feeds and 18 test feeds with added fats demonstrated a true digestibility of fat approaching 100% and an endogenous fecal fat of 0.22 g x d(-1) x kg BW(-1). The results revealed that nonhydrolyzable ether extract and endogenous fecal fat were insufficient to account for the difference between true digestibility and apparent digestibilities of ether extract in basal feeds and partial digestibilities of added fats in test feeds. A third possible contributing factor was demonstrated: an increasing first-order relationship between observed digestibilities (D, %) and the fat content of the feed (F, g/kg): D = 92.0 - 92.0e(-F/342). r2 = 0.81, P < 0.001. This equation indicates that 46% digestibility (half maximum) occurs at an ether extract or fat content of 24 g/kg, which is common in forages. It is consistent with fat digestibility or efficiency of absorption being a function of the rate of lipolysis, especially when residence time in the small intestine is limited. Consequently, we suggest that the kinetics of lipases, which are difficult to measure, may contribute to low digestibility when substrate concentration in the small intestine is low due to a low fat content in food. The status of vitamins A and E might be affected by low dietary fat contents and might be improved by fat supplementation.

Colonic adenocarcinoma in a corn snake (Elaphe guttata guttata).

Colonic adenocarcinoma was diagnosed by surgical biopsy in a domestically raised 3-yr-old male corn snake (Elaphe guttata guttata). The snake presented with a history of constipation. Several masses were palpated in the distal coelomic cavity. On proctoscopy, a nodular firm white mass encircled the distal colon proximal to the cloaca. The histologic diagnosis was transmural mucinous colonic adenocarcinoma with scirrhous reaction. Resection of the affected region alleviated intestinal obstruction for at least 4 mo, after which the snake was lost to follow-up.

Use of an inactivated virus vaccine to control polyomavirus outbreaks in nine flocks of psittacine birds.

Nine flocks of psittacine birds were examined because of sudden death of neonates. In each flock, cause of death was determined to be polyomavirus infection, by means of DNA testing and in situ hybridization. Contaminated areas of aviaries were cleaned and disinfected, and vaccination programs, using a recently approved inactivated polyomavirus vaccine, were instituted. Use of the vaccine was found to be safe and efficacious.

Neutrophil activation and chemotaxis after in vitro treatment with perfluorocarbon.

The in vitro effects of perfluorocarbon (PFC) on human neutrophil activation and chemotaxis were examined. Neutrophils were incubated, with and without PFC, and were analyzed for chemotaxis through 5-microns and 8-microns pore filters. Neutrophil activation was quantitated by flow cytometry. Activation studies showed that PFC-treated neutrophil samples (n = 6) produced only 39.83% +/- 25.9% (mean +/- SD) of matched control (n = 6) fluorescence. Chemotaxis studies showed that PFC-treated neutrophil samples (n = 8) had migration of only 18.63% +/- 6.5% (of control values) of neutrophils to the outer boundary of the 5-microns filters (n = 8 controls). The 8-microns pore filter migration (n = 8) was similarly low, with a mean outer boundary migration count of only 26% +/- 19.8% of the control (n = 8) value. Thus, neutrophils exposed to perfluorocarbon produce significantly less detectable H2O2 (P < .001) and have a significantly lower chemotactic response (P < .001).

A method for isolating human lung macrophages and observations of fluorescent phagocytes from the lungs of habitual cigarette smokers.

We report the development of a simple, efficient, expedient, and inexpensive procedure for isolating a large and relatively pure population of macrophages (Mphi) from residual (i.e., non-tumor) lung tissue obtained from lung cancer patients undergoing either a lobectomy or pneumonectomy. The proposed technique was founded on observations by fluorescent microscopy of fresh, non-fixed, and non-stained human lung tissue. Examinations of 74 specimens from different patients revealed that most of the Mphi reside as non-adherent cells within the sponge-like lung stroma. Very few Mphi were observed in the lungs of nonsmokers. In contrast, many Mphi were visible in the lungs of habitual smokers. For most specimens from smokers, a few of the Mphi were present as randomly distributed single cells; the majority of the Mphi, however, were in clusters that ranged from a dozen to several hundred cells. The Mphi could be released readily by different mechanical techniques. In the procedure reported herein, pulmonary leukocytes (> 75% Mphi) were dislodged easily from lung tissue with the use of an inexpensive, hand-operated, tissue grinder. The grinder consisted of a glass mortar and Teflon pestle that provided sufficient clearance between the mortar and pestle so as to avert damaging the displaced leukocytes. The leukocytes were then segregated by centrifugation on a density gradient. Further purification was achieved by harvesting Mphi that had been allowed to adhere to serum-coated polystyrene culture dishes (> 90% Mphi). In most experiments, the Mphi yield (approximately 5 x 10(6) Mphi /gr of lung) and Mphi viability (> 85%) were good. A significant advantage of this technique is that it avoids jeopardizing the cells to the hazards associated with enzymes that have been used in techniques employed previously for isolating Mphi from the lung and other organs. Thus, the proposed method provides numerous lung Mphi for detailed studies of their morphology, phenotype, and function. Moreover, lung Mphi were cultured as non-adherent, single cells in a serum- and cytokine-free tissue culture medium for more than 6 weeks. Lung Mphi from habitual smokers displayed a high level of fluorescence that was readily apparent when viewed with a fluorescence microscope that had been configured with either a fluorescein or rhodamine filter. Serial sections of single, living Mphi obtained with the use of a confocal laser scanning microscope revealed that the fluorescence originated from cytoplasmic inclusions. Relative fluorescence intensity was measured by cytometry.(ABSTRACT TRUNCATED AT 400 WORDS)

Are thymus-derived lymphocytes (T cells) defective in the nasopharyngeal and palatine tonsils of children?

The present study was conducted to evaluate the response of adenoidal T cells and B cells in the production of immunoglobulins. There appears to be a consistent inability of adenoidal T cells to turn on B cells to mature into immunoglobulin-secreting plasma cells. This phenomenon did not appear to be due to suppressor activity of adenoidal T cells because T cells from other sources appeared to effectively result in adenoidal B cell maturation, even in the presence of adenoidal T cells. Both tonsils and adenoids appear to have defective IL-2 production, in response to both mitogens and specific antigens. It is hypothesized that a cytokine(s) may be released in adenoids that downregulate IL-2 production and result in immune suppression in the adenoids of children with recurrent otitis media and chronic sinusitis.

Mucosal T cell distribution during infection with respiratory syncytial virus.

Groups of 12-week-old Balb/c mice were inoculated intranasally with respiratory syncytial virus (RSV) and sacrificed at regular intervals after infection. T lymphocyte subset distribution was determined in lung tissue, bronchoalveolar lavage (BAL), peripheral blood, and spleen by means of flow cytometry employing monoclonal antibodies against the T cell membrane antigens Thy1.2 (pan-T), Ly2 (CD8), and L3T4 (CD4). Thy1.2+ cells increased in the lung from 35.4% of total lymphocytes before infection to 47.6% on day 7 after infection. This increase was largely accounted for by an increase in Ly2+ cells, which manifested a rise from 7.8% preinfection to 19.8% on day 7. The level of L3T4+ cells remained constant (27.9% preinfection vs. 25.2% on day 7). The L3T4+/Ly2+ ratio in the lungs reached a nadir 7 days post infection (1.5 vs. 3.5 before infection). The total cell count in BAL increased more than tenfold during the first week after infection. At the same time Thy1.2+ cells in the BAL increased from 41.1% of total lymphocytes on day 1 to 85.3% on day 7. Ly2+ influx was the most important (5.8% on day 1 vs. 41.1% on day 7). L3T4+ cell levels increased from 17.2% on day 1 to 40.1% on day 7. RSV-specific lymphocyte transformation was observed in BAL and blood but not in the lung tissue and spleen on day 7 postinfection. The disappearance of infectious virus in the lung correlated directly to the peak appearance of Ly2+ T cells in the lung tissue and BAL.

Basic history taking and the avian physical examination.

As one may readily see, the basic avian physical examination should be an extensive, thorough procedure. A wide array of diseases and conditions can be detected during the examination. A flow sheet or checklist should be instituted to maintain consistency and cover all aspects of the history and physical examination. I highly recommend as an adjunct to the basic physical examination Gram stains of the choanae, crop, and cloacae or feces. Owing to the fact that a great number of compromised avian patients either are ill because of gram-negative bacteria or have become more compromised by opportunistic organisms such as yeast or gram-negative bacteria, identification of these conditions greatly facilitates treatment and recovery of the avian patient. Other ancillary tests, such as fecal flotation, complete blood count, culture and sensitivity, Chlamydia test, chemistry profile, radiology, and laparotomy/laparoscopy, are available to the practitioner to aid in the diagnosis of various diseases involving the avian patient. [Editor's note: The editors suggest that the complete blood count be done before an extensive physical examination is undertaken to avoid a stress hemogram.]

Enhanced resection and improved survival in murine neuroblastoma (C1300-NB) after preoperative immunotherapy.

Advanced neuroblastoma treated with standard chemotherapy has a poor prognosis. Combination immunotherapy for murine neuroblastoma with retinyl palmitate, low-dose cyclophosphamide, and interleukin-2 resulted in increased survival, impaired tumor growth, easier surgical resection, and increased class I expression or tumor cells. Preoperative immunotherapy may be useful in treatment of advanced human neuroblastoma.

The relationship of class I MHC antigen expression to stage IV-S disease and survival in neuroblastoma.

Cultured human neuroblastoma cells express low levels of class I (MHC) surface antigen. In order to determine if this low expression is representative of the clinical tumor, this study investigates class I expression in archival human neuroblastoma. Whereas stages I to IV neuroblastoma expressed low levels of class I antigen, stage IV-S tumor cells expressed normal levels, similar to control tissues. Expression of class I antigen in tumors from survivors of stage III neuroblastoma was significantly greater than in tumors from nonsurvivors. Tumors comprised predominantly of ganglion cells expressed significantly more class I antigen than neuroblasts. These data suggest that class I MHC expression may play a role in the natural history of human neuroblastoma.

Lymphoid cell populations in splenectomized and nonsplenectomized SJL/J mice bearing Hodgkin's disease-like reticulum cell sarcoma.

Using the reticulum cell sarcoma (RCS) of the SJL/J mouse as a model for Hodgkin's disease, the effects of tumor growth and splenectomy on the T-cell and B-cell populations were evaluated. Although splenectomy improved survival and reduced gross observable tumor growth in secondary tumor sites, no effect on T-cell and B-cell populations was detected. We conclude that tumor growth appears to be undetected by the immune system; previously reported immunosuppression in RCS-bearing mice must be due to functional changes and not cell population changes; and splenectomy contributes to survival and suppression of tumor cell growth in secondary sites.