Biomedical subjects
S Hafner
Publications and source records attributed to S Hafner.
Fast imaging in liquids and solids with the Back-projection Low Angle ShoT (BLAST) technique.
A simple fast imaging scheme is proposed, which is applicable to solid- and liquid-like materials. It is based on low angle pulse excitation in combination with back-projection reconstruction and proper data handling and is called Back-projection Low Angle ShoT (BLAST) technique. The sequence is applied to grape as a biological sample and to a jellibaby (2 kHz linewidth at half intensity) for demonstration of the applicability to solid objects.
NMR-imaging of water content in the polymer matrix of silicon chips.
The distribution of water in the polymer matrix of a silicon microchip was studied by NMR imaging. The chip was saturated with water in a water steam atmosphere and then dried in five steps. After every change of the water content a three-dimensional (3D) NMR image was acquired. A 3D back-projection spin-echo sequence was used to avoid fast gradient switching during the sequence. The experiments show that water invades the chip mainly through the gap between the metallic parts and the polymer body.
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)
Enterogenous cysts in chickens.
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[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.
Solid-state NMR spectroscopy under periodic modulation by fast magic-angle sample spinning and pulses: a review.
Fast magic-angle spinning (MAS) holds promise for new approaches to pulsed high-resolution NMR in solids where homogeneous interactions dominate. Prerequisite for developing new pulse methods is the understanding of signal encoding by spin interactions under MAS conditions and of interferences between MAS and pulses. This review discusses corresponding strategies and techniques in a coherent way with particular concentration on homonuclear decoupling techniques for line-narrowing in solids.
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.
Splenic granulomas in broiler chickens produced experimentally by inoculation with Eubacterium tortuosum.
Eubacterium tortuosum, a gram-positive anaerobic filamentous bacillus, was isolated from splenic and hepatic granulomas of a 56-day-old slaughtered chicken. This isolate was injected intravenously into two groups of 2-week-old broiler chickens, which were necropsied 19 days later. Five of 15 chickens injected with 5 x 10(6) colony-forming units of a 48-hour culture of E. tortuosum developed splenic granulomas typical of those seen in chickens at slaughter. No lesions were observed in chickens given 5 x 10(5) colony-forming units of E. tortuosum or in control chickens receiving phosphate-buffered saline solution. Attempts to reisolate E. tortuosum from experimentally infected chickens were unsuccessful; however, typical filamentous organisms were observed in splenic granulomas of all five affected chickens.
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.
Multicentric histiocytosis in young chickens. Gross and light microscopic pathology.
During 1991-94, tissue specimens from 262 young chicken carcasses condemned at slaughter contained novel multicentric proliferations of histiocytelike cells. These tissues had been submitted to the USDA FSIS Eastern Laboratory because of grossly enlarged spleens, livers, or kidneys. The spleens were two to three times normal diameter and contained miliary white or yellow 1-3-mm foci. Similar miliary foci were present throughout the enlarged livers and kidneys. Microscopic examination of these tissues revealed discrete circular nodules expanding splenic periarteriolar lymphoid sheaths, hepatic periportal nodules, and discrete perivascular and more diffuse interstitial nodules replacing renal tubules. Nodules also were present in the pancreas, bone marrow, proventriculus, and lung, with more diffuse infiltrates in intestinal lamina propria. The cells composing these nodules contained irregularly oval, folded, or pleomorphic nuclei and relatively abundant eosinophilic cytoplasm. Mitotic figures and pyknotic nuclei were common. These cells were interpreted to be histiocytes (tissue macrophages or dendritic cells) and did not resemble lymphocytes. These proliferating cells also did not resemble the cell population of commonly diagnosed lymphoid neoplasms of young chickens. No intralesional organisms were detected and polymerase chain reaction analysis failed to detect Marek's herpesvirus DNA or leukosis/sarcoma and reticuloendotheliosis proviral DNA.
Pulmonary sarcomas in a young chicken.
Both lungs of a 5-wk-old broiler chicken contained miliary, round, white tumors. Microscopically, these masses were composed of compactly arranged cells with round to oval nuclei and indistinct cytoplasmic borders. Immunohistochemically, tumor cells were positive for vimentin but negative for cytokeratin, S-100 protein, neuron-specific enolase, smooth muscle actin, and muscle-specific actin. Ultrastructurally, tumor cells were separated by collagen bands and some contained collagen fibrils. These results suggest that the primitive mesenchymal cells composing these sarcomas may have originated from precursors of interstitial cells or fibroblasts of the interparabronchial or interatrial septa. DNA was extracted from paraffin-embedded tissues and probed for sequences specific for Marek's disease virus, reticuloendotheliosis viruses, exogenous avian leukosis viruses, and subgroup J avian leukosis viruses. Only sequences specific for subgroup J avian leukosis viruses were identified in the DNA extracted from tumors and surrounding lung.