Observations on the lesions in the white matter of the spinal cord of swayback sheep

Summary Eleven sheep with swayback aged 2, 3 1/2, 6 1/2 and 8 months, and 10 normal sheep of similar age were examined. The histopathology and biochemistry of the spinal cord white matter was studied in detail. There was less myelin in the spinal cord white matter of the swayback animals and it had a lower content of cerebroside and ethanolamine phospholipid than that of the controls. Myelin breakdown products were only found in the older animals and there was a close correlation between the results obtained by the OTAN, Sudan II and Marchi techniques. These results are discussed in relation to the pathogenesis of the lesion.

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Zusammenfassung Elf Schafe mit Swayback im Alter von 2, 3 1/2, 6 1/2 und 8 Monaten sowie 10 Normaltiere gleichen Alters wurden untersucht. Die Histopathologie und Biochemie der weißen Substanz des Rückenmarks wurde ausführlich studiert. Im Rückenmark der kranken Tiere lag weniger Myelin und ein geringerer Gehalt an Cerebrosiden und Ethanolamin-Phospholipid als in den Kontrollen vor. Markscheidenzerfallsprodukte wurden nur bei älteren Tieren gefunden, wobei gute Übereinstimmung der Ergebnisse der OTAN-, Sudan II- und Marchi-Methoden bestand. Die Befunde werden hinsichtlich ihrer Beziehung zur Pathogenese der Läsion diskutiert.

     

Proceedings. The monitoring of chemical contaminants in food.

Two different smoking systems were tested by exposing Syrian golden hamsters to the smoke of cigarettes labelled with [¹⁴C]dotriacontane-16,17 (DOT). In 3 experiments, the activity of mainstream and sidestream Total Particulate Matter (TPM) and of butts and ash was determined. Comparing the results, the system involving individual exposure was shown to provide the animals with higher amounts of mainstream TPM than the system using simultaneous exposure of numerous animals.     

Bone quality of mandibles reconstructed with particulate cellular bone and marrow, and platelet-rich plasma

The purpose of this study was to evaluate the bone quality of mandibles reconstructed with particulate cellular bone and marrow (PCBM) and platelet-rich plasma (PRP). We compared the bone mineral density (BMD) and microstructure of PCBM and PRP-reconstructed bone and normal bone in patients.Bone biopsies were taken of 11 samples of PCBM and PRP reconstructed bone and 16 samples of normal bone using a trephine bur. BMD and microstructures were assessed using microcomputed tomography.The compact bone resulting from the PCBM and PRP reconstruction was extremely thin. Analysis of the microstructures, showed statistically significant differences only in trabecular bone number and trabecular bone spaces between PCBM and PRP-reconstructed bones and normal bones. In the case of BMD, no statistical differences were found between the two groups. Lamellar structures and osteocytes were observed histologically in the trabecular bone in both groups.In conclusion, the BMD and microstructures of the cancellous bone in the PCBM and PRP-reconstructed mandibles resembled those in the normal mandibles.     

Functional and histologic changes after repeated transcranial direct current stimulation in rat stroke model

Transcranial direct current stimulation (tDCS) is associated with enhancement or weakening of the NMDA receptor activity and change of the cortical blood flow. Therefore, repeated tDCS of the brain with cerebrovascular injury will induce the functional and histologic changes. Sixty-one Sprague-Dawley rats with cerebrovascular injury were used. Twenty rats died during the experimental course. The 41 rats that survived were allocated to the exercise group, the anodal stimulation group, the cathodal stimulation group, or the control group according to the initial motor function. Two-week treatment schedules started from 2 days postoperatively. Garcia, modified foot fault, and rota-rod performance scores were checked at 2, 9, and 16 days postoperatively. After the experiments, rats were sacrificed for the evaluation of histologic changes (changes of the white matter axon and infarct volume). The anodal stimulation and exercise groups showed improvement of Garcia's and modified foot fault scores at 16 days postoperatively. No significant change of the infarct volume happened after exercise and tDCS. Neuronal axons at the internal capsule of infarct hemispheres showed better preserved axons in the anodal stimulation group. From these results, repeated tDCS might have a neuroprotective effect on neuronal axons in rat stroke model.     

The in vitro cytotoxicity and genotoxicity of cigarette smoke particulate matter with reduced toxicant yields

Tobacco smoke contains more than 5600 constituents, of which approximately 150 are toxicants. This paper describes the activities in the Neutral Red uptake (NRU) assay, the Salmonella mutagenicity test (SAL), the mouse lymphoma mammalian cell mutation assay (MLA) and the in vitro micronucleus test (IVMNT) of Particulate Matter (PM) obtained from experimental cigarettes (ECs), designed to produce reduced levels of toxicants. The designs included tobacco substitute sheet (TSS) containing glycerol, which dilutes toxicants in smoke, or the incorporation of blend-treated (BT) tobacco to reduce the levels of nitrogenous toxicant precursors and some polyphenols. All samples were cytotoxic in the NRU, however TSS reduced PM cytotoxicity in this assay. All PMs were mutagenic in the SAL, MLA and IVMNT. Reductions in bacterial mutagenicity were observed in the SAL, for cigarettes with BT tobacco, compared with their respective controls. The quantitative changes in bacterial mutagenicity could be explained by analytical chemistry data on smoke generated from the ECs used in the study. These observations, and the absence of consistent qualitative differences in the activities of the experimental, control and reference cigarettes, suggest that reduced toxicity cigarettes, as measured by the tests described in this paper, may be developed without introducing any additional cytotoxic or genotoxic hazards, but the impact of this on human health risks remains unknown.     

111Indium-labeled ultrafine carbon particles; a novel aerosol for pulmonary deposition and retention studies

Continuous environmental or occupational exposure to airborne particulate pollution is believed to be a major hazard for human health. A technique to characterize their deposition and clearance from the lungs is fundamental to understand the underlying mechanisms behind their negative health effects. In this work, we describe a method for production and follow up of ultrafine carbon particles labeled with radioactive ¹¹¹Indium (¹¹¹In). The physicochemical and biological properties of the aerosol are described in terms of particle size and concentration, agglomeration rate, chemical bonding stability, and human lung deposition and retention. Preliminary in vivo data from a healthy human pilot exposure and 1-week follow up of the aerosol is presented. More than 98% of the generated aerosol was labeled with Indium and with particle sizes log normally distributed around 79?nm count median diameter. The aerosol showed good generation reproducibility and chemical stability, about 5% leaching 7 days after generation. During human inhalation, the particles were deposited in the alveolar space, with no central airways involvement. Seven days after exposure, the cumulative activity retention was 95.3%. Activity leaching tests from blood and urine samples confirmed that the observed clearance was explained by unbound activity, suggesting that there was no significant elimination of ultrafine particles. Compared to previously presented methods based on Technegas, ¹¹¹In-labelled ultrafine carbon particles allow for extended follow-up assessments of particulate pollution retention in healthy and diseased lungs.     

Nanoparticle-based immunopotentiation via tetanus toxoid-loaded gelatin and aminated gelatin nanoparticles

Gelatin nanoparticles (GNPs) and aminated gelatin nanoparticles (AGNPs) were prepared and used as an adjuvant to improve the delivery of tetanus toxoid (TT). Nanoparticles were characterized in vitro for their size, shape, entrapment, and release. TT-FITC conjugate was used to determine entrapment and release from nanoparticles. The immune-stimulating activity was studied by measuring anti-TT IgG, IgG1, and IgG2a isotype and cytokine responses following subcutaneous (s.c) injection of nanoparticles in BALB/c mice and was compared with alum-TT vaccine. Gelatin and aminated gelatin (AG) specific IgG response was also determined. Both GNPs and AGNPs demonstrated comparable IgG response and a significantly higher (p?<?0.05) cytokine response (IL-2 and IFN γ) as compared to alum-TT vaccine. Nanoparticulate formulations elicited both Th1 and Th2 responses and induced negligible undesirable immunogenicity against the carrier, as demonstrated by lower level of gelatin and AG-specific IgG response as compared to control.