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Biomedical subjects

S Stephen

Publications and source records attributed to S Stephen.

At least 19 recordsLinked to original sources
PubMed1999

Poly(A) mRNA is attached to insect ovarian microtubules in vivo in a nucleotide-sensitive manner.

In ovarioles of hemipteran insects, RNA passes from anteriorly positioned nurse cells to the chain of developing oocytes via extended nutritive tubes. These intercellular connections may reach several millimeters in length. Each nutritive tube is comprised of many thousands of parallel microtubules. We have extracted microtubule bundles from isolated nutritive tubes of Notonecta glauca and, using hybridization techniques, provide evidence of poly(A) mRNA attachment to microtubules in vivo. We also show this attachment to be nucleotide-sensitive, which is typical of a motor protein-mediated interaction. The pattern of nucleotide sensistivity is indicative of a kinesin motor mechanism. We provide evidence that a kinesin is present in the nutritive tube translocation channels and is a component of the mRNA/microtubule bundles isolated and extracted from them. Our findings are consistent with kinesin-driven transport of mRNA along the nutritive tube microtubules.

Adenine Nucleotides↗
PubMed1998

Malaria acquired in the Torres Strait.

Two cases of Plasmodium vivax malaria acquired in the Torres Strait during 1997 are reported. The source of infection could not be firmly established but two possibilities are discussed. Anopheline mosquitoes are present in the Torres Strait, and malaria is frequently imported from Papua New Guinea (PNG), thus transmission by local mosquitoes poses an ongoing threat. However, in this particular location, Badu Island, no recent importation of malaria was identified and mosquito surveillance demonstrated low numbers of anopheline species at the time and for the preceding two years. These cases could also feasibly be explained by a variant of 'baggage malaria' in which mosquitoes already infected with the malaria parasite were imported from PNG in one of the small boats that regularly make this journey. These cases serve as a reminder to health care providers in northern Australia to consider the diagnosis of malaria in patients presenting with a febrile illness.

Adolescent↗
PubMed1998

Planning and conducting a multi-institutional project on fatigue.

PURPOSE/OBJECTIVES: To describe the process used in proposal development and study implementation for a complex multisite project on cancer treatment-related fatigue (CRF), identify strategies used to manage the project, and provide recommendations for teams planning multisite research. DATA SOURCES: Information derived from project team meeting records, correspondence, proposals, and personal recollection. DATA SYNTHESIS: The project was built on preexisting relationships among the three site investigators who then built a team including faculty, research coordinators, staff nurses, and students. Study sites had a range of organizational models, and the proposal was designed to capitalize on the organizational and resource strengths of each setting. Three team members drawn from outside oncology nursing provided expertise in measurement and experience with fatigue in other populations. Planning meetings were critical to the success of the project. Conference calls, fax technology, and electronic mail were used for communication. Flexibility was important in managing crises and shifting responsibility for specific components of the work. The team documented and evaluated the process used for multisite research, completed a major instrumentation study, and developed a cognitive-behavioral intervention for CRF. CONCLUSIONS: Accomplishments during the one-year planning grant exceeded initial expectations. The process of conducting multisite research is complex, especially when the starting point is a planning grant with specific research protocols to be developed and implemented over one year. Explicit planning for decision-making processes to be used throughout the project, acknowledging the differences among the study settings and planning the protocols to capitalize upon those differences, and recruiting a strong research team that included a member with planning grant and team-building expertise were essential elements for success. IMPLICATIONS FOR NURSING PRACTICE: Specific recommendations for others planning multisite research are related to team-building, team membership, communication, behavioral norms, role flexibility, resources, feedback, problem management, and shared recognition.

Communication↗
PubMed1995

Hypertrophy and hyperplasia of smooth muscle cells of small intramyocardial arteries in spontaneously hypertensive rats.

Hearts of stroke-prone spontaneously hypertensive rats (SHR) were investigated by means of stereology and were compared with those of normotensive. Wistar-Kyoto controls. At the age of 9 months, hypertensive rats showed cardiac hypertrophy, marked myocardial fibrosis, activation of nonvascular interstitium, focal myocytial degeneration, reduction of capillarization, and microarteriopathy of small intramyocardial arteries. Stereologically, a significant increase in the total left ventricular arterial wall volume (+180% versus controls) was found in SHR hearts. By using new stereological techniques, the orientator and the nucleator, we investigated whether this significant increase in total left ventricular arterial wall volume was due to hyperplasia of smooth muscle cells in addition to the process of vascular smooth muscle cell hypertrophy that is common in SHR. Additionally, the nuclear size and ratio of cell volume to nuclear volume were determined using another new stereological technique, the selector. The stereological data indicate a significant increase in mean cell and nuclear volumes as well as in the total number of left ventricular arterial smooth muscle cells of SHR. Additionally, the total length of intramyocardial arteries was also significantly increased in hypertensive rats. The volume and number of arterial smooth muscle cells per arterial length were significantly (P < .001 and P < .05, respectively) higher in SHR than in normotensive controls. Thus, we conclude that hypertrophy and hyperplasia of smooth muscle cells are involved in intramyocardial arterial growth processes in hypertensive heart remodeling.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗