The origin and evolution of geminivirus-related DNA sequences in Nicotiana.

A horizontal transmission of a geminiviral DNA sequence, into the germ line of an ancestral Nicotiana, gave rise to multiple repeats of geminivirus-related DNA, GRD, in the genome. We follow GRD evolution in Nicotiana tabacum (tobacco), an allotetraploid, and its diploid relatives, and show GRDs are derived from begomoviruses. GRDs occur in two families: the GRD5 family's ancestor integrated into the common ancestor of three diploid species, Nicotiana kawakamii, Nicotiana tomentosa and Nicotiana tomentosiformis, on homeologous group 4 chromosomes. The GRD3 family was acquired more recently on chromosome 2 in a lineage of N. tomentosiformis, the paternal ancestor of tobacco. Both GRD families include individual members that are methylated and diverged. Using relative rates of synonymous and nonsynonymous nucleotide substitutions, we tested for evidence of selection on GRD units and found none within the GRD3 and GRD5 families. However, the substitutions between GRD3 and GRD5 do show a significant excess of synonymous changes, suggesting purifying selection and hence a period of autonomous evolution between GRD3 and GRD5 integration. We observe in the GRD3 family, features of Helitrons, a major new class of putative rolling-circle replicating eukaryotic transposon, not found in the GRD5 family or geminiviruses. We speculate that the second integration event, resulting in the GRD3 family, involved a free-living geminivirus, a Helitron and perhaps also GRD5. Thus our data point towards recurrent dynamic interplay between geminivirus and plant DNA in evolution.

Achievements and challenges of formulating a strategic plan for nursing development at the national level in Bahrain.

BACKGROUND: In this paper (initially presented at a symposium during the ICN Centennial Conference, 27 June-1 July 1999, London), we describe nurses' experiences in formulating a strategic plan for nursing development at the national level in Bahrain. AIM: Specifically, we address the process undertaken to produce a comprehensive and integrated strategic plan directed at what nurses in Bahrain need to do in order to contribute to cost-effective and high-quality health service. CONCLUSIONS: The following strategies are addressed: regulation of nursing; reform of nursing education; development of nursing services; development of a nursing information system, and development of nursing leadership.

Ultrastructural and histochemical study of collagen fibres types I and III in the venom gland of Bothrops jararaca during secretory cycle.

Fragments of snake (Bothrops jararaca) venom gland were analysed by light and transmission electron microscopy in order to characterize the changes in collagen fibres types I and III in the intertubular gland septa during the secretory cycle. The snakes were sacrificed at 45 days (unmilked group), 6 h, 4 and 8 days after manual extraction of the venom. The fragments were fixed, processed according to standard histologic technique for embedding in paraffin, and stained with haematoxylin-eosin and Gomori's trichrome and submitted to Gomori's silver impregnation technique and picrosirius-polarization method. For transmission electron microscopy the fragments were fixed and processed for embedding in Spurr's medium. At the 45th day (the gland at rest), when the secretory activity was at a minimum, the septa were narrow and filled with densely packed collagen fibrils. At 6 h, the septa were enlarged and exhibited wide spaces filled with finely granular Alcian Blue-positive material. Until the 8th day, the septa were narrower and the histologic aspect resembled that of the gland at rest. The results demonstrated structural modifications in the glandular septa according to the different periods of the secretory cycle. These modifications can be associated with the transformation in the secretory epithelium during the venom synthesis cycle.

Recurrent hematuria in a patient with a history of anaphylactic reaction to radiographic contrast.

Hematuria is a relatively common problem, but its evaluation can be complicated. One must pay attention to the patient's symptoms and extrarenal manifestations of disease to identify the etiology efficiently. We present the case of a patient who narrated a fascinating past medical history and a dramatic presentation of hematuria that had been exhaustively evaluated at another hospital. During a prolonged and involved stay at our institution, the etiology of the hematuria remained enigmatic after extensive radiologic and invasive investigations that led to internally inconsistent findings, until an unusual diagnosis was entertained.

Alterações da ultra-estrutura miocárdica durante cirurgia cardíaca / Ultrastructural changes of the myocardium during cardiac surgery

Os autores fazem uma revisao da ultra-estrutura miocardica normal e alterada por isquemia cardiaca e circulacao extracorporea, analisando a quantificacao das alteracoes encontradas. Admiten que o estudo da ultra-estrutura miocardica e um bom metodo para estudar a protecao miocardica durante cirurgia cardiaca

Proteção miocárdica por cardiologia sanguínea durante circulação extracorpórea. Avaliação ultra-estrutural miocárdica no cão / Myocardial protection by blood cardioplegia during extracorporeal circulation. Ultrastructural myocardial evaluation in the dog

Os autores desenvolveram metodo simplificado para infusao de cardioplegia sanguinea durante circulacao extracorporea. Fizeram estudo experimental, em caes, para averiguar a eficiencia do metodo. Dois grupos de 5 caes foram submetidos a 60 min de esquemia cardiaca, seguidos de 60 min de reperfusao coronaria. A protecao miocardica, durante isquemia cardiaca, foi obtida com o metodo de cardioplegia sanguinea no grupo I e com cardioplegia acelular gelada no grupo II. Para comparar os dois metodos empregados, foram feitas quatro biopsias de ventriculo esquerdo, para estudo ultra-estrutural: antes da isquemia cardiaca; ao fim de 60 min de isquemia cardiaca; com 30 mim de reperfusao coronaria e com 60 min de reperfusao coronaria.Nas tres primeiras biopsias houve apenas alteracoes ultra-estruturais miocardicas discretas, sem diferencas entre os dois grupos. Nas ultimas, as alteracoes ultraestruturais foram mais severas no grupo II do que no grupo I. Conclui-se que o metodo de protecao miocardica com cardioplegia sanguinea e eficaz para 60 min de isquemia cardiaca, sendo inclusive superior a cardioplegia acelular gelada