Hepatic protoporphyrin accumulation in a broiler chicken

Hepatocellular accumulation and biliary excretion of protoporphyrin in a 6-week-old chicken are described. The affected liver was grossly dark gray to black. Histologically, hepatocytes, bile canaliculi, and bile-duct lumina contained dark-brown granules. These protoporphyrin pigment accumulations were brightly birefringent under polarized light. The ultrastructural appearance of granules revealed hair-like crystals in a radial arrangement. Extracted levels of protoporphyrin in the affected liver were determined to be 630 micrograms per gram of wet (frozen) liver. Spectrofluorometric scans of liver extracts and sedimented crystals were characteristic of protoporphyrin.

Avian keratoacanthoma (dermal squamous cell carcinoma) in broiler chicken carcasses

Multiple lesions of dermal squamous cell carcinoma are found at a low frequency (0.04%) in the carcasses of young meat-type chickens at slaughter. For this study, affected carcasses (n = 308) were removed from the processing line, and lesions were characterized by size, distribution, and morphology. Carcasses were also sexed and examined for evidence of metastasis. Nodular (n = 297) and ulcerative (n = 1,707) lesions were counted and examined. Most lesions were present in the pectoral, dorsopelvic, and femoral feather tracts. Few lesions (n = 11) were found in wing tracts. Mean diameter was 5.4 mm for ulcerative lesions and 3.1 mm for nodular lesions. Histologic sections of ulcerative (n = 579) and nodular (n = 113) lesions were examined. Small nodular lesions originated from hyperplastic feather follicle epithelium. Nodules contained keratin-filled cysts lined by squamous epithelium that were associated with isolated islands and infiltrating cords of dermal keratinocytes. Loss of surface epithelium resulted in noduloulcerative and ulcerative lesions. Invasion of underlying skeletal muscle and evidence of visceral metastasis were not present, but invasion through elastic laminae and into the subcutis was present in 20.5% (134/654) of the lesions examined. The nodular lesions in these carcasses were morphologically similar to early nodular lesions previously described in live chickens as avian keratoacanthomas. A retrospective study compared selected production parameters and disease condemnations to the prevalence of squamous cell carcinoma in 665 flocks of broiler chickens. There was a positive correlation (P < 0.0001) with the occurrence of airsacculitis but a negative correlation with increased age and condemnations for leukosis (P < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Spontaneous regression of "dermal squamous cell carcinoma" in young chickens

Eight young chickens with lesions characteristic of those described as dermal squamous cell carcinoma were obtained before slaughter. Lesions were measured; representative lesions were biopsied and examined microscopically; and gross changes were monitored. Lesions appeared to originate as cystic, keratin-filled proliferations of the feather-follicle epithelium. These cysts progressed into raised, keratin-filled, and eventually ulcerated, nodules. Loss of the keratin core resulted in a shallow ulcer that became progressively flattened and regressed into a fibrous dermal scar. All lesions in the broilers regressed in 4 to 16 days (mean 14 days). Twenty roaster lesions completely regressed. For roasters, the mean time to regression was 20 days, with a range of 6 to 93 days. Although there was limited invasion of the dermis by atypical keratinocytes, the overall architecture and biological behavior were more consistent with a benign lesion.

[The antagonism of ketamine/xylazine anesthesia ("Hellabrunn mixture") in wild zoo ruminants]

The ability of the antagonists tolazoline, yohimbine and the combination of yohimbine with 4-aminopyridine to reverse the effects of the xylazine-component of the "Hellabrunn mixture" (125 mg/ml xylazine and 100 mg/ml ketamine) on nondomestic zoo ruminants is discussed. Arousal time, recovery time and changes in the parameter of circulatory and respiratory functions after antagonization are shown. Tolazoline is able to antagonize the xylazine effect completely within a short time. Using a dosage of 3-5 mg/kg there is a marked negative effect on the cardio-vascular system. Yohimbine in the used dosage of 0.25-0.3 mg/kg in non-domestic ruminants did not approve in its effects. Combining yohimbine (0.25-0.3 mg) with 4-aminopyridine (0.5 mg/kg) recovery time is about 30 minutes. The negative effect on the cardio-vascular system is less pronounced compared with tolazoline.

Quantitative assessment of Fc receptor expression and function during in vitro differentiation of human monocytes to macrophages

The expression and function of IgG Fc receptors on peripheral blood monocytes and monocytes differentiating in vitro, within hydrophobic membranes, to macrophages have been determined. Three characteristic functional stages could be discerned, and these were reflected in the surface expression of specific IgG binding sites. Stage 1, represented by fresh monocytes, is characterized by efficient binding and phagocytosis of IgG-coated particles, although uptake was limited by the cell size. Within 1 day of culture, monocytes transform into Stage 2 cells. These bind and ingest particles with high IgG surface density only and these functions are exquisitely sensitive to inhibition by IgG in solution. The functional loss is paralleled by a decrease of the number of specific IgG binding sites, despite a gradual increase in cell size. Between Day 4 and Day 8, macrophages acquired the capacity to bind and ingest particles opsonized to a low degree, their phagocytic capacity is strongly enhanced, the number of IgG binding sites increases by a factor greater than 10, despite a moderate increase in cell size only. Mature human macrophages have about six times the Fc receptor number of blood monocytes, but the average binding affinity is decreased. It appears that the phagocytic capacity is related to the number of IgG binding sites, and the susceptibility to inhibition by IgG in solution is related to their surface density.

Long-term potentiation phenomena in the rat limbic forebrain

Long-term potentiation (LTP) phenomena were investigated in several limbic forebrain pathways. With the possible exception of the lateral olfactory tract, LTP could be produced in all pathways tested. LTP effects tended to increase as the stimulation site moved caudally along the pyriform lobe. The largest effects were produced by stimulation of pathways into and out of the hippocampus. Target sites also differed, with the hippocampal sites showing the strongest and longest lasting LTP effects. The time course of LTP appeared to be best fitted by the sum of two exponential curves with time constants of about 1.5 h and 5 days respectively. We also looked at the potentiation effects produced by repeated epileptogenic (kindling) stimulations, and the effect of this potentiation on subsequent tests of short-term and long-term potentiation. In most cases, the short-term effects, and the first component of the LTP effect, were still intact after kindling. The longest lasting component, however, could no longer be produced with either amygdala or perforant path stimulation. This result indicates that the potentiation produced by kindling may be based upon the same mechanism as the LTP effect.