Needleoscopic Placement of Tenckhoff Catheters

BACKGROUND: Minimally invasive techniques are being developed for the placement of peritoneal dialysis catheters. A needleoscopic technique that utilizes only two punctures is described. METHODS: Twelve patients underwent 13 needleoscopic Tenckhoff catheter placement procedures between November 1995 and May 1998. An additional six patients underwent the same procedure using a standard 10 mm laparoscope. The patients were followed prospectively for type of anesthesia and operative time for the procedure, whether the procedure was performed as an inpatient or an outpatient, and for any complications or leakage following the procedure. RESULTS: The needleoscopic procedure was able to be performed with an average operative time of 12 minutes. Twenty-three percent (23%) were performed under local anesthesia and thiry-eight (38%) were treated as outpatients. CONCLUSION: Needleoscopic Tenckhoff catheter placement is very simple to perform and can be performed under local anesthesia with minimal discomfort, secure catheter placement, and no leakage

Hand-Assisted Laparoscopic Transhiatal Esophagectomy Using the Dexterity Pneumo Sleeve

BACKGROUND: As the use of laparoscopic techniques have expanded to more complicated procedures, limitations of laparoscopy have begun to be realized. To help regain the ability to palpate and bluntly dissect tissues, and handle larger organs, surgeons have begun to utilize devices which allow the surgeon\u27s hand to be inserted into the abdomen during laparoscopic procedures. One such devices is the Dexterity Pneumo Sleeve, which was used here to perform transhiatal esophagectomy in two patients. METHODS: Two patients with adenocarcinoma of the esophagus underwent hand-assisted laparoscopic transhiatal esophagectomy. The stomach mobilization was carried out using laparoscopic technique facilitated by the use of the surgeon\u27s hand. Blunt dissection of the esophagus through the hiatus was then carried out. Dissection of the proximal esophagus and creation of a cervical esophagogastric anastomosis was then performed in the neck through a cervical incision. RESULTS: The Pneumo Sleeve proved useful for handling the stomach, as well as, blunt dissection of the esophagus while still maintaining the benefits of laparoscopy, including small incisions, and no postoperative ileus. CONCLUSION: Hand-assisted laparoscopic esophagectomy can be carried out with good, early, postoperative recovery

Evolutionary connectionism: algorithmic principles underlying the evolution of biological organisation in evo-devo, evo-eco and evolutionary transitions

The mechanisms of variation, selection and inheritance, on which evolution by natural selection depends, are not fixed over evolutionary time. Current evolutionary biology is increasingly focussed on understanding how the evolution of developmental organisations modifies the distribution of phenotypic variation, the evolution of ecological relationships modifies the selective environment, and the evolution of reproductive relationships modifies the heritability of the evolutionary unit. The major transitions in evolution, in particular, involve radical changes in developmental, ecological and reproductive organisations that instantiate variation, selection and inheritance at a higher level of biological organisation. However, current evolutionary theory is poorly equipped to describe how these organisations change over evolutionary time and especially how that results in adaptive complexes at successive scales of organisation (the key problem is that evolution is self-referential, i.e. the products of evolution change the parameters of the evolutionary process). Here we first reinterpret the central open questions in these domains from a perspective that emphasises the common underlying themes. We then synthesise the findings from a developing body of work that is building a new theoretical approach to these questions by converting well-understood theory and results from models of cognitive learning. Specifically, connectionist models of memory and learning demonstrate how simple incremental mechanisms, adjusting the relationships between individually-simple components, can produce organisations that exhibit complex system-level behaviours and improve the adaptive capabilities of the system. We use the term “evolutionary connectionism” to recognise that, by functionally equivalent processes, natural selection acting on the relationships within and between evolutionary entities can result in organisations that produce complex system-level behaviours in evolutionary systems and modify the adaptive capabilities of natural selection over time. We review the evidence supporting the functional equivalences between the domains of learning and of evolution, and discuss the potential for this to resolve conceptual problems in our understanding of the evolution of developmental, ecological and reproductive organisations and, in particular, the major evolutionary transitions

STAGES IN THE ORIGIN OF VERTEBRATES: ANALYSIS BY MEANS OF SCENARIOS

Vertebrates lack an epidermal nerve plexus. This feature is common to many invertebrates from which vertebrates differ by an extensive set of shared-derived characters (synapomorphies) derived from the neural crest and epidermal neurogenic placodes. Hence, the hypothesis that the developmental precursor of the epidermal nerve plexus may be homologous to the neural crest and epidermal neurogenic placodes. This account attempts to generate a nested set of scenarios for the prevertebrate-vertebrate transition, associating a presumed sequence of behavioural and environmental changes with the observed phenotypic ones. Toward this end, it integrates morphological, developmental, functional (physiological/behavioural) and some ecological data, as many phenotypic shifts apparently involved associated transitions in several aspects of the animals. The scenarios deal with the origin of embryonic and adult tissues and such major organs as the notochord, the CNS, gills and kidneys and propose a sequence of associated changes. Alternative scenarios are stated as the evidence often remains insufficient for decision. The analysis points to gaps in comprehension of the biology of the animals and therefore suggests further research.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72629/1/j.1469-185X.1989.tb00471.x.pd

Socioeconomic mobility and talent utilization of workers from poorer backgrounds: The overlooked importance of within-organization dynamics

Socioeconomic mobility, or the ability of individuals to improve their socioeconomic standing through merit-based contributions, is a fundamental ideal of modern societies. The key focus of societal efforts to ensure socioeconomic mobility has been on the provision of educational opportunities. We review evidence that even with the same education and job opportunities, being born into a poorer family undermines socioeconomic mobility due to processes occurring within organizations. The burden of poorer background might, ceteris paribus, be economically comparable to the gender gap. We argue that in the societal and scientific effort to promote socioeconomic mobility, the key context in which mobility is supposed to happen—organizations—as well as the key part of the life of people striving toward socioeconomic advancement—that as working adults—have been overlooked. We integrate the organizational literature pointing to key within-organizational processes impacting objective (socioeconomic) success with research, some emergent in organizational sciences and some disciplinary, on when, why, and how people from poorer backgrounds behave or are treated by others in the relevant situations. Integrating these literatures generates a novel and useful framework for identifying issues people born into poorer families face as employees, systematizes extant evidence and makes it more accessible to organizational scientists, and allows us to lay the agenda for future organizational scholarshi

The life and scientific work of William R. Evitt (1923-2009)

Occasionally (and fortunately), circumstances and timing combine to allow an individual, almost singlehandedly, to generate a paradigm shift in his or her chosen field of inquiry. William R. (‘Bill’) Evitt (1923-2009) was such a person. During his career as a palaeontologist, Bill Evitt made lasting and profound contributions to the study of both dinoflagellates and trilobites. He had a distinguished, long and varied career, researching first trilobites and techniques in palaeontology before moving on to marine palynomorphs. Bill is undoubtedly best known for his work on dinoflagellates, especially their resting cysts. He worked at three major US universities and spent a highly significant period in the oil industry. Bill's early profound interest in the natural sciences was actively encouraged both by his parents and at school. His alma mater was Johns Hopkins University where, commencing in 1940, he studied chemistry and geology as an undergraduate. He quickly developed a strong vocation in the earth sciences, and became fascinated by the fossiliferous Lower Palaeozoic strata of the northwestern United States. Bill commenced a PhD project on silicified Middle Ordovician trilobites from Virginia in 1943. His doctoral research was interrupted by military service during World War II; Bill served as an aerial photograph interpreter in China in 1944 and 1945, and received the Bronze Star for his excellent work. Upon demobilisation from the US Army Air Force, he resumed work on his PhD and was given significant teaching duties at Johns Hopkins, which he thoroughly enjoyed. He accepted his first professional position, as an instructor in sedimentary geology, at the University of Rochester in late 1948. Here Bill supervised his first two graduate students, and shared a great cameraderie with a highly motivated student body which largely comprised World War II veterans. At Rochester, Bill continued his trilobite research, and was the editor of the Journal of Paleontology between 1953 and 1956. Seeking a new challenge, he joined the Carter Oil Company in Tulsa, Oklahoma, during 1956. This brought about an irrevocable realignment of his research interests from trilobites to marine palynology. He undertook basic research on aquatic palynomorphs in a very well-resourced laboratory under the direction of one of his most influential mentors, William S. ‘Bill’ Hoffmeister. Bill Evitt visited the influential European palynologists Georges Deflandre and Alfred Eisenack during late 1959 and, while in Tulsa, first developed several groundbreaking hypotheses. He soon realised that the distinctive morphology of certain fossil dinoflagellates, notably the archaeopyle, meant that they represent the resting cyst stage of the life cycle. The archaeopyle clearly allows the excystment of the cell contents, and comprises one or more plate areas. Bill also concluded that spine-bearing palynomorphs, then called hystrichospheres, could be divided into two groups. The largely Palaeozoic spine-bearing palynomorphs are of uncertain biological affinity, and these were termed acritarchs. Moreover, he determined that unequivocal dinoflagellate cysts are all Mesozoic or younger, and that the fossil record of dinoflagellates is highly selective. Bill was always an academic at heart and he joined Stanford University in 1962, where he remained until retiring in 1988. Bill enjoyed getting back into teaching after his six years in industry. During his 26-year tenure at Stanford, Bill continued to revolutionise our understanding of dinoflagellate cysts. He produced many highly influential papers and two major textbooks. The highlights include defining the acritarchs and comprehensively documenting the archaeopyle, together with highly detailed work on the morphology of Nannoceratopsis and Palaeoperidinium pyrophorum using the scanning electron microscope. Bill supervised 11 graduate students while at Stanford University. He organised the Penrose Conference on Modern and Fossil Dinoflagellates in 1978, which was so successful that similar meetings have been held about every four years since that inaugural symposium. Bill also taught many short courses on dinoflagellate cysts aimed at the professional community. Unlike many eminent geologists, Bill actually retired from actively working in the earth sciences. His full retirement was in 1988; after this he worked on only a small number of dinoflagellate cyst projects, including an extensive paper on the genus Palaeoperidinium