Strengthening cancer biology research, prevention, and control while reducing cancer disparities: student perceptions of a collaborative master's degree program in cancer biology, preventions, and control.

This article provides the findings of a survey of previous and current students in the UDC/GU-LCCC master's degree program. This master's degree program, Cancer Biology, Prevention, and Control is administered and taught jointly by faculty of a Minority Serving Institution, the University of the District of Columbia, and the Lombardi Comprehensive Cancer Center to incorporate the strengths of a community-based school with a research intensive medical center. The program was initiated in 2008 through agreements with both University administrations and funding from the National Cancer Institute. The master's degree program is 36 credits with a focus on coursework in biostatistics, epidemiology, tumor biology, cancer prevention, medical ethics, and cancer outreach program design. For two semesters during the second year, students work full-time with a faculty person on a laboratory or outreach project that is a requirement for graduation. Students are supported and encouraged to transition to a doctoral degree after they obtain the master's and many of them are currently in doctorate programs. Since the inception of the program, 45 students have initiated the course of study, 28 have completed the program, and 13 are currently enrolled in the program. The survey was designed to track the students in their current activities, as well as determine which courses, program enhancements, and research experiences were the least and most useful, and to discern students' perceptions of knowledge acquired on various aspects of Cancer Biology Prevention, and Control Master's Program. Thirty of the 35 individuals to whom email requests were sent responded to the survey, for a response rate of 85.7%. The results of this study will inform the strengthening of the Cancer Biology program by the Education Advisory Committee. They can also be used in the development of comparable collaborative master's degree programs designed to address the significant disparities in prevalence of cancer, low screening awareness, and access to and outcomes of cancer prevention and treatment services. This, in turn, will contribute to the elimination of the dearth of underrepresented minority scientists who address these disparities. By far, the students were satisfied with the program and believe that it has had significant impact on their ability to contribute to cancer prevention and control. They provided both general and specific recommendations to strengthen the program.

Use of RAPD-PCR to differentiate genetically defined lines of an intermediate host of Schistosoma mansoni, Biomphalaria glabrata.

The genetic differentiation among several laboratory-maintained pedigree snail lines of Biomphalaria glabrata (with different susceptibility phenotypes to Schistosoma mansoni infection) was assessed with the random amplified polymorphic DNA method. Out of the 20 primers tested, 2 (OPA-01 and OPA-06) gave reproducible markers with either individual or bulked DNA samples from resistant (BS-90, 10-R2, LAC-line) and susceptible (M-line) snails. Arbitrary primer, OPA-01, amplification of BS-90 DNA identified a 180-bp strain-specific fragment and a 400-bp marker in the susceptible M-line stock. In the 10-R2 and LAC snail lines, OPA-01 specific markers of 200 bp and 550 bp were identified. Amplification with primer OPA-06 identified several major strain-specific markers in the BS-90 (150 bp, 400 bp, 800 bp) and M-line (1,100 bp) snails. The heritability of the RAPD markers was evaluated in progeny snails derived from a cross between the BS-90 and M-line stocks. Results showed that markers were inherited in a dominant or codominant fashion. The 1,100-bp M-line marker was inherited in all susceptible progeny snails analyzed.

Nervous system of Schistosoma mansoni cercaria: organization and fine structure.

As observed by transmission electron microscopy of serially sectioned Schistosoma mansoni cercaria, the nervous system is distributed throughout the three anatomic segments of the larva-i.e., the anterior organ (oral sucker), the body (midsegment), and the tail. The central ganglion, a neuropile surrounded by cell bodies, is located in the anterior area of the body segment. It tapers anteriorly into two lobes from which a pair of anterior central nerve trunks extend longitudinally. The posterior region of the central ganglion tapers into a pair of nerve trunks (posterior central nerve trunks). Twelve peripheral nerve trunks are evenly distributed around the ganglion. Six trunks course anteriad (anterior peripheral nerve trunks) and six course posteriad (posterior peripheral nerve trunks). A pair of dorsal and ventral nerve trunks, positioned opposite each other, extend the length of the tail. All nerve trunks are unsheathed. The nervous system contains three types of vesicles. Type I vesicles average 47.66 +/- 2.57 nm in diameter, vary in electron density, and have electron-lucent peripheries. Type II vesicles have a mean diameter of 18.41 +/- 2.57 nm, are electron-lucent and are concentrated mostly in the presynaptic area of the synaptic and neuromuscular junctions. The mean diameter of Type III vesicles is 57.47 +/- 16.08 nm. They are electron-dense and are concentrated mostly in the tegumental ciliated papillae and their accompanying dendrites. Two types of synaptic junctions are present.(ABSTRACT TRUNCATED AT 250 WORDS)

Schistosoma mansoni: a new parenchymal cell in cercariae.

A new type of cell has been identified in cercariae of Schistosoma mansoni. The perikarya (cell bodies) of these cells were located in the body (midsegment), in an area oral to the acetabulum (ventral sucker). Cytoplasmic processes extending from the perikarya ramified throughout the parenchyma of the anterior organ (oral sucker), body, and tail segments by following the path of the nerve processes from the neuropile. The perikarya of these cells had heterochromatic nuclei and a predominance of particulate material and granules (240-360 nm) in their cytoplasm. Aggregates of granules (240-360 nm) and associated vesicles (34 nm) were scattered throughout the cytoplasmic processes of the cells and formed distinct varicosed areas. These processes often connected to the tegument in the midsegment (body) of the cercariae. The granules and associated vesicles reacted (became electron dense) with fixatives reported to be detectors of biogenic amines: The glutaraldehyde/osmium tetroxide fixation procedure rendered the granules electron dense while the glutaraldehyde/chromate/osmium tetroxide fixation procedure rendered the granules and the associated vesicles electron dense. The chromate solution of the latter procedure was responsible for the electron density of the associated vesicles. The morphology of these cells (their long ramifying cytoplasmic processes) and their reaction to chromium suggests that they are probably biogenic aminergic sensory cells.

Cryopreservation of schistosomules of Schistosoma mansoni in quantity.

Large quantities of Schistosoma mansoni schistosomules were cryopreserved in 35% ethanediol, and attempts were made to improve their morphology and infectivity after thawing. Several variables affected the appearance of the thawed organisms. These included: 1) the particular in vitro method used to transform cercariae to schistosomules; 2) addition of serotonin to the thawing medium; 3) changing the thawing temperature; and 4) culturing schistosomules for extended post-thaw times before assessing their condition. Varying either the postemergence age of the cercariae before transformation or the concentration of organisms in the freezing suspension had no effect on their survival. Although damage to many of the thawed schistosomules became apparent only upon extended in vitro cultivation, the addition of fetal calf serum to the thawing medium usually retarded this deterioration. When injected into mice, approximately 5% of cryopreserved schistosomules matured to adult worms, representing 71% of the value for maturation of unfrozen schistosomules. These studies define conditions of importance for the successful preservation of very large quantities of schistosomules (up to 500,000 in 1 ml volume) in liquid nitrogen.

Schistosoma mansoni: stimulus and transformation of cercariae into schistosomules.

Schistosoma mansoni schistosomules prepared from cercariae by seven in vitro techniques had not all reached the same state of development at the end of the incubation period as scored by seven parameters: water tolerance; Cercarienhüllen Reaktion; presence of the glycocalyx; condition of the surface membrane; nuclear state; granule migration; and cryopreservability. At the end of the specific incubation period for each technique, the level of development was judged with respect to schistosomules which had developed in situ for 1 hr after penetration of the ear skin of mice. In descending order of their correspondence to in vivo schistosomules, those derived in vitro (by the procedures listed) ranked as follows: first, penetration of dried rat skin; second, centrifuging and vortexing, or incubation in serum-supplemented medium; and third, syringe passage, omnimixing, centrifuging, and incubating, or incubating alone. The only treatment common to all techniques was incubation in 37 C culture medium for 2 hr or more. This is suggested as the stimulus for the cercaria-to-schistosomule transformation.