Effects of steam autoclave treatment on Geobacillus stearothermophilus spores.

AIMS: To determine the mechanism of autoclave killing of Geobacillus stearothermophilus spores used in biological indicators (BIs) for steam autoclave sterilization, and rates of loss of spore viability and a spore enzyme used in BIs. METHODS AND RESULTS: Spore viability, dipicolinic acid (DPA) release, nucleic acid staining, α-glucosidase activity, protein structure and mutagenesis were measured during autoclaving of G. stearothermophilus spores. Loss of DPA and increases in spore core nucleic acid staining were slower than loss of spore viability. Spore core α-glucosidase was also lost more slowly than spore viability, although soluble α-glucosidase in spore preparations was lost more rapidly. However, spores exposed to an effective autoclave sterilization lost all viability and α-glucosidase activity. Apparently killed autoclaved spores were not recovered by artificial germination in supportive media, much spore protein was denatured during autoclaving, and partially killed autoclave-treated spore preparations did not acquire mutations. CONCLUSIONS: These results indicate that autoclave-killed spores cannot be revived, spore killing by autoclaving is likely by protein damage, and spore core α-glucosidase activity is lost more slowly than spore viability. SIGNIFICANCE AND IMPACT OF THE STUDY: This work provides insight into the mechanism of autoclave killing of spores of an organism used in BIs, and that a spore enzyme in a BI is more stable to autoclaving than spore viability.

Osteosarcoma condroblástico maxilar: Presentación de un caso / Chondroblastic osteosarcoma of the maxilla: A case report

Los osteosarcomas son neoplasmas caracterizados por la presencia de células mesenquimales que producen tejido osteoide. Las manifestaciones clínicas en la cavidad bucal comprenden dolor, inflamación, desplazamiento de los dientes, espasmos, parestesias y obstrucción nasal. Este artículo presenta un osteosarcoma condroblástico avanzado en el maxilar superior. El examen histológico evidenció proliferación neoplásica extensamente cartilaginosa, con áreas pequeñas en la que se identificó formación osteoide y hueso no laminar, rodeado por células neoplásicas. El tratamiento consistió en maxilectomía y vaciamiento bilateral de cuello. Además, se colocó férula quirúrgica obturadora con el fin de sellar el defecto de la comunicación oronasosinusal. Aun cuando el osteosarcoma de los maxilares presenta un mejor pronóstico que el osteosarcoma de los huesos largos, los pacientes con osteosarcoma maxilar pueden presentar tumores avanzados, principalmente cuando no se realiza el diagnóstico adecuado (AU)

Osteosarcomas are neoplasms characterized by the presence of mesenchymal cells that produce osteoid. The clinical manifestations in the oral cavity include pain, swelling, teeth displacement, twitching, paresthesia, and nasal obstruction. This paper presents an advanced chondroblastic osteosarcoma in the maxilla. Histological examination showed extensive cartilaginous neoplastic proliferation, with small areas in which osteoid formation was identified and non-lamellar bone, surrounded by neoplastic cells. The treatment consisted in maxillectomy and bilateral neck dissection. In addition, sealing stents were placed to seal the defect orosinonasal communication. Although osteosarcoma of the jaw has a better prognosis than osteosarcoma of long bones, jaw osteosarcoma patients with advanced tumors can occur, especially when the proper diagnosis is not appropriate (AU)

Spontaneous long-term remyelination after traumatic spinal cord injury in rats.

The capability of the central nervous system to remyelinate axons after a lesion has been well documented, even though it had been described as an abortive and incomplete process. At present there are no long-term morphometric studies to assess the spinal cord (S.C.) remyelinative capability. With the purpose to understand this phenomenon better, the S.C. of seven lesionless rats and the S.C. of 21 rats subjected to a severe weight-drop contusion injury were evaluated at 1, 2, 4, 6, and 12 months after injury. The axonal diameter and the myelination index (MI = axolemmal perimeter divided by myelinated fiber perimeter) were registered in the outer rim of the cord at T9 SC level using a transmission electron microscope and a digitizing computer system. The average myelinated fiber loss was 95.1%. One month after the SC, 64% of the surviving fibers were demyelinated while 12 months later, only 30% of the fibers had no myelin sheath. The MI in the control group was 0.72 +/- 0.07 (X +/- S.D.). In the experimental groups, the greatest demyelination was observed two months after the lesion (MI = 0.90 +/- 0.03), while the greatest myelination was observed 12 months after the injury (MI = 0.83 +/- 0.02). There was a statistical difference (p < 0.02) in MI between 2 and 12 months which means that remyelination had taken place. Remyelination was mainly achieved because of Schwann cells. The proportion of small fibers (diameter = 0.5 micron or less) considered as axon collaterals, increased from 18.45% at 1 month to 27.66% a year after the contusion. Results suggest that remyelination is not an abortive phenomenon but in fact a slow process occurring parallel to other tissue plastic phenomena, such as the emission of axon collaterals.