16 research outputs found
Solitary colon metastasis from renal cell carcinoma nine years after nephrectomy: A case report
AbstractIntroductionRenal cell carcinoma (RCC) is the most common renal malignancy in adults. Metastatic disease is relatively common at presentation and frequently involves the lung, bone, brain, liver and adrenal glands. After curative resection, there is a 30–40% risk of recurrence, and a 10% risk of developing metastatic disease after 5 years. The gastrointestinal tract, particularly the colon, represents a very uncommon site of late metastatic disease.Presentation of CaseWe present a case of a 67 year-old-male who underwent a left radical nephrectomy for RCC 9 years before presenting with a metastatic large bowel obstruction. He was later found to have a near-completely obstructing mass in the rectosigmoid colon and underwent a sigmoidectomy with anterior resection of the upper rectum. Histopathology confirmed metastatic RCC confined to the colonic wall with negative microscopic margins.DiscussionThe tendency of RCC to metastasize to unusual sites such as the pancreas or thyroid gland has been widely reported. However, cases of colon metastasis from RCC are extremely rare. Despite the absence of randomized prospective data, widespread consensus supports the surgical treatment of solitary and oligometastatic disease in light of the poor patient outcomes in non-surgically treated disease (Milovic et al., 2013) [3]. Multiple groups have reported favorable outcomes for surgically resected solitary metastatic disease with long disease-free intervals and good performance status.ConclusionThe colon is a potential, though uncommon, site for solitary metastasis from RCC. The clinical presentation is frequently several years after initial curative resection. Oncologic resection with negative margins may result in long-term survival in patients with isolated metastatic disease
A contribution to the leaf anatomy and taxonomy of Apocynaceae in Africa : the leaf anatomy of Apocynaceae in East Africa; a monograph of Pleiocarpinae (series of revisions of Apocynaceae 41)
This publication comprises two main parts.Part one (Chapter I) deals with the leaf anatomy of Apocynaceae in East Africa, where this family is represented by 77 species in 30 genera. Out of these, 37 species in 26 genera are examined and these exhibit a wide range of anatomical variations. Many species can be separated on the basis of their leaf anatomy and many genera are confirmed to be closely related. The most outstanding anatomical characters include the dorsiventral leaves, presence of laticifers, and bicollateral vascular bundles with intraxylary phloem.Part two (Chapter 2) is a monograph of the apocynaceous subtribe Pleiocarpinae- Plumeriodeae-Carisseae, which comprises of three genera, Hunteria (12 spp.); Pleiocarpa (5 spp.) and Picralima (1 sp.). The subtribe Pleiocarpinae is restricted to Africa, although one species, Hunteria zeylanica, extends to Asia. It is easily distinguished from the other members of the tribe Carisseae by the presence of completely apocarpous ovaries, with 2-5 carpels, which are a great exception in the family Apocynaceae.The genus Picralima was first described by Pierre in 1896 and has since remained monotypic. Its only species, Picralima nitida, is not only exploited for its wood, but also used medicinally in its present distribution area and employed as well as an arrow and a fish poison.In this publication, three new species are described in the genus Hunteria (Roxburgh, 1814, 1824) and one new combination is made.The genus Pleiocarpa (Bentham, 1876) has proved to be a very difficult subject due to insufficient collections and lack of sufficient information from the field. At present it has 5 species and one doubtful species of which the collections are all either sterile or only bearing fruits. One new species is described.Parallel to the investigations reported here a taxonomic treatment was prepared for the Flora of Tropical East Africa. This contribution, covering all the mentioned 30 genera and 77 species, will be submitted to the editors in Kew shortly
Cued and uncued terminal links in concurrent-chains schedules
Pigeons were trained on a concurrent-chains schedule. The initial links were concurrent variable-interval schedules arranged on two side keys. Each terminal link was a fixed-interval schedule arranged on the center key. In cued conditions, different center-key colors signaled the two terminal-link schedules. In uncued conditions, the same center-key color appeared for both terminal links. Experiment 1 arranged unequal initial links and equal terminal links. Preference for the shorter initial-link schedule was greater when the terminal links were uncued. Experiment 2 arranged equal initial links and unequal terminal links. Preference for the shorter terminal-link schedule was greater when the terminal links were cued. Although the results of Experiment 2 successfully replicated previous research, the results of Experiment 1 are not easily reconciled with conditioned-reinforcement or discriminative-stimulus accounts of the role of terminal-link cues. Rather, terminal-link cues appear to decrease sensitivity to initial-link contingencies
Evidence against a constant-difference effect in concurrent-chains schedules.
Savastano and Fantino (1996) reported that in concurrent-chains schedules, initial-link choice proportions remained constant as terminal-link durations increased as long as the subtractive difference between the two terminal-link schedules remained constant. Two experiments with pigeons were conducted to examine this constant-difference effect. Both experiments used equal variable-interval schedules as initial links. The terminal links were fixed delays to reinforcement in Experiment 1 and variable delays to reinforcement in Experiment 2. The durations of the terminal links were varied across conditions, but the difference between pairs of terminal links was always 10 s. In both experiments, preference for the shorter terminal link became less extreme as terminal-link durations increased, so a constant-difference effect was not found. It is argued, however, that this choice situation does not provide clear evidence for or against delay-reduction theory versus other theories of choice