Radiofrequency ablation with a high-power generator: device efficacy in an in vivo porcine liver model.

PURPOSE: The purpose of this study was to test the feasibility and efficacy of using a high-power generator with nondeployable electrodes to create large zones of coagulation in an in vivo porcine liver model. METHODS: With approval from our institution's research animal care and use committee, 12 female swine (mean weight = 55 kg) were anesthetized and received RF ablation at laparotomy. Twenty-nine ablations were performed in four groups using: (i) a conventional 200-W generator and cluster electrode (n = 4), or an experimental prototype 250-W generator and (ii) a single, 17-gauge electrode (n = 9), (iii) a cluster electrode (n = 8) or (iv) three electrodes spaced 2.0 cm apart in a triangular configuration (n = 8). In the three-electrode group, power was applied by switching between electrodes using a prototype switching device. All electrodes were internally cooled. Ablation zone size, shape and generator data from each group were compared using a mixed-linear model with animals modeled as random effects. RESULTS: The high-power generator was able to increase significantly the zone of coagulation. Mean (+/-SD) ablation diameter was largest in the switched group (4.31 +/- 0.7 cm) followed by the cluster (3.98 +/- 0.5 cm) and single-electrode (3.26 +/- 0.5 cm) groups. Mean diameter in the high-power single-electrode group was no different than the low-power cluster group (3.25 +/- 0.4 cm, p = 0.98). Circularity measures were high (>0.75) in all groups. CONCLUSIONS: Coupling a high-power generator and switching device is feasible. At higher powers, the switching device creates larger zones of ablation than cluster or single electrodes. Single-electrode ablations created with the prototype high-power generator were equivalent to those produced with the cluster electrode at conventional lower powers.

Old World sources of the first New World human inhabitants: a comparative craniofacial view.

Human craniofacial data were used to assess the similarities and differences between recent and prehistoric Old World samples, and between these samples and a similar representation of samples from the New World. The data were analyzed by the neighbor-joining clustering procedure, assisted by bootstrapping and by canonical discriminant analysis score plots. The first entrants to the Western Hemisphere of maybe 15,000 years ago gave rise to the continuing native inhabitants south of the U.S.-Canadian border. These show no close association with any known mainland Asian population. Instead they show ties to the Ainu of Hokkaido and their Jomon predecessors in prehistoric Japan and to the Polynesians of remote Oceania. All of these also have ties to the Pleistocene and recent inhabitants of Europe and may represent an extension from a Late Pleistocene continuum of people across the northern fringe of the Old World. With roots in both the northwest and the northeast, these people can be described as Eurasian. The route of entry to the New World was at the northwestern edge. In contrast, the Inuit (Eskimo), the Aleut, and the Na-Dene speakers who had penetrated as far as the American Southwest within the last 1,000 years show more similarities to the mainland populations of East Asia. Although both the earlier and later arrivals in the New World show a mixture of traits characteristic of the northern edge of Old World occupation and the Chinese core of mainland Asia, the proportion of the latter is greater for the more recent entrants.

Richard Owen and the comparative anatomy of teeth.

One hundred fifty years ago, Richard Owen published the first detailed monograph on the comparative anatomy of teeth entitled Odontography; or, A Treatise on the Comparative Anatomy of the Teeth; their Physiological Relations, Mode of Development, and Microscopic Structure, in the Vertebrate Animals. The treatise is considered to be the first fundamental work of odontology. The 150th anniversary of its publication is an appropriate time to rediscover the roots and development of this scientific discipline, as well as the life and work of its author.

Comparative anatomy of teeth from past to present.

The comparative anatomy of teeth has a long tradition in research, starting more than two thousand years ago in antiquity. In the 19th century, Richard Owen's oeuvre Odontography (1840-45) contributed much to establish odontology as an independent scientific discipline. After a short outline of the historical development of the comparative anatomy of teeth, we describe the contents and importance of Owen's Odontography. Finally, we sketch the contemporary situation of dental morphology, which in the course of the last thirty years has developed into an important and internationally highly recognized multidisciplinary field.

Region does not mean "race"--reality versus convention in forensic anthropology.

Norman Sauer has posed the rhetorical question: if races do not exist, how come forensic anthropologists are so good at identifying them? The simple answer is that, as members of the society that poses the question, they are inculcated into the social conventions that determine the expected answer. They should also be aware of the biological inaccuracies contained in that "politically correct" answer. Skeletal analysis provides no direct assessment of skin color, but it does allow an accurate estimate of original geographical origins. African, eastern Asian, and European ancestry can be specified with a high degree of accuracy. Africa of course entails "black," but "black" does not entail African. The significant identifying features of a given region then are stochastically determined and are not the products of natural selection. If they are valuable for purposes of identification, they have no coherent adaptive, that is, biological, significance. Neither individual traits nor a configuration of them associated with a given region have any adaptive significance and thus have no comparative worth. Traits of adaptive value however are not constrained by region and cannot be used to identify "race."

Dimensions of face in Asia in the perspective of geography and prehistory.

Data from 24 craniofacial dimensions were compiled for samples representing all the human populations of the world. These were converted into C scores and used to construct Euclidean Distance dendrograms. The populations of the world are best depicted as 8 major regional clusters representing: Africa, Amerind, Asia-Mainland, Australo-Melanesia, Eskimo-Siberia, Europe, India, and Jomon-Pacific. The mainland Asian cluster divided into northern and southern components. The Neolithic in both areas is less clearly associated with the northern or southern components and may represent the form of their undifferentiated precursors. This needs to be tested by the addition of further specimens and an adequate sample from South China. Mongols are peripheral members of the Asia-Mainland cluster and should not be thought of as typifying the region as a whole. The use of the term "Mongoloid" is inappropriate in both theory and practice.

A nonracial craniofacial perspective on human variation: A(ustralia) to Z(uni).

Dental and craniofacial measurements were collected for 57 samples from Asia, the Pacific, the aboriginal western hemisphere, and Europe. The craniofacial dimensions include many that are not obviously under the control of specific selective forces. Similar configurations for these in different samples should yield indications of recency of common ancestry according to the logic expressed by Darwin and evident in the relationships indicated by nuclear DNA comparisons. Dental dimensions, however, vary according to the length of time that different intensities in selective forces have been in operation. The craniofacial measurements were transformed into C scores and used to generate Euclidean distance dendrograms. When all the material was used to generate a single dendrogram, the European and Amerindian samples sorted into two regionally identifiable clusters, and the Asian and Pacific material sorted into the three clusters identified in separate previous studies: a Mainland Asian cluster, a Jomon-Pacific cluster and an Australo-Melanesian cluster. Since these clusters are based on variation in traits that are basically nonadaptive in nature, no hierarchical ranking is possible. The clusters simply reflect degree of relationship. This technique holds forth the promise of producing a nonracial assessment of the relationships of all the peoples of the world, past and present.

Reflections on the face of Japan: a multivariate craniofacial and odontometric perspective.

Craniofacial variables for modern and prehistoric Japanese were subjected to multivariate analysis to test the relationships of the people of Japan with mainland Asian and Oceanic samples. The modern Japanese are tied to Koreans, Chinese, Southeast Asians, and the Yayoi rice agriculturalists who entered Japan in 300 B.C. Together they make up a Mainland-Asia cluster of related populations. The prehistoric Jomon foragers, the original inhabitants of the Japanese archipelago, are the direct ancestors of the modern Ainu, who made a recognizable contribution to the warrior class--the Samurai--of feudal Japan. Together, they are associated with Polynesians and Micronesians in a Jomon-Pacific cluster of related populations. Jomon-to-Ainu tooth size reduction proceeded at the same rate as that observable in the post-Pleistocene elsewhere in the Old World.

Japanese tooth size: past and present.

Mesial-distal and buccal-lingual crown measurements were made on male and female samples of recent Japanese teeth from three locations, Fukuoka, Kyoto, and Tokyo, and for Hokkaido Ainu and Koreans. Similar data were collected for prehistoric Middle-to-Late Jomon Japanese and from Yayoi specimens representing the first agriculturalists to appear in Japan. From a tooth-by-tooth comparison of cross-sectional areas, it was shown that the modern Japanese samples did not differ from one part of Japan to another. Korean tooth size also is not significantly different from Japanese, while Ainu have the smallest teeth recorded in Asia. The Yayoi who brought rice to Japan about 300 B.C. came in with teeth that were the same size as Chinese Neolithic teeth. They encountered a resident Jomon population whose teeth were 10% smaller. From tooth size measures alone, it is most economical to suggest that, if the rates of reduction observed elsewhere in the world applied in Japan, the recent Ainu would best be regarded as the direct descendants of the Jomon, while the modern Japanese are the results of in situ reduction from the incoming Yayoi. Other aspects of craniofacial morphology suggest that some Jomon was incorporated by the Yayoi. The modern Japanese, then, while predominantly derived from the Yayoi, would include a Jomon component.