Search PubMed⌕ Search

Biomedical subjects

H Seidler

Publications and source records attributed to H Seidler.

At least 19 recordsLinked to original sources
PubMed2002

Numerical description of selected endo- and ectocranial dimensions in Homo sapiens and the three Homo heidelbergensis: Kabwe, Atapuerca and Petralona.

Investigation of hominid cranial morphology is of particular importance for those dealing with questions concerning both ontogenetic and phylogenetic aspects in the genus Homo. The present study provides a numerical description of several regions of extant human crania and, in addition, mid-Pleistocene crania, given in distances and angles. This study is seen as a basic preparatory work that is most useful for further investigation on cranial development in hominids. The sample used consisted of 60 recent adult human crania as well as stereolithographic models of three H. heidelbergensis crania: Kabwe, Atapuerca and Petralona. 12 ecto- and 20 endocranial landmarks were selected and 3D-coordinates taken on each cranium using a 3D Polhemus 3Space FASTRAK tracking system. From the resulting data set, 21 ectocranial and 17 endocranial distances were calculated, in addition to 41 angles of the ectocranium and 21 angles of the endocranium; the measurements are presented in tables, serving as a reference database.

Adult↗
PubMed2001

Virtual anthropology: the digital evolution in anthropological sciences.

The discovery and explanation of differences among organisms is a major concern for evolutionary and systematic biologists. In physical anthropology, the discrimination of taxa and the qualitative and quantitative description of ontogenetic or evolutionary change require, of course, the analysis of morphological features. Since the 1960s, a remarkable amount of fossil material was excavated, some of it still awaiting a detailed first analysis, some of it requiring re-examination by more developed methods. While the fossil record grew continuously, a revolution in anthropological research took place with advances in computer technology in the 1980s: a handful of innovative researchers working in specialized anthropology laboratories or medical departments developed the methodological inventory needed to extract critical information from subjects in vivo and from fossilized remains. A considerable part of this information is preserved in the physically heretofore inaccessible interior of anatomical structures. Virtual Anthropology (VA) is a means of making them visible and measurable. Thus, VA also allows access to 'hidden' landmarks; in addition, the large number of semilandmarks accessible on the form enhances the power of Geometric Morphometrics analysis. Furthermore, the density information in volume data allows manipulations such as segmentation, impossible with the real, physical object. Moreover, metric body measurements generally, and cranial measurements specifically, are also an important source of information for the analysis of the ontogenetic development of the skeletal system, and--last but not least--for clinical use (e.g., operation planning, operation simulation, prosthetics). Thus, there developed a fruitful interdisciplinary cooperation between statistics, medicine, and physical anthropology.

Anthropology, Physical↗
PubMed2000

Endocranial capacity in Sts 71 (Australopithecus africanus) by three-dimensional computed tomography.

In a recent report on early hominid endocranial capacity, it was predicted that future studies would show that: (1) "several key early hominid endocranial estimates may be inflated"; (2) "current views on the tempo and mode of early hominid brain evolution may need reevaluation"; and (3) endocranial capacity in one of these, Sts 71, was "probably closer to 370 cm(3), very near the mean value for female chimpanzees, and not the currently accepted 428 cm(3)" (Conroy et al., Science, 1998; 280: 1730-1731; Falk, Science 1998; 20:1714). Subsequent studies tend to support the first two predictions, but not the third (Culotta, Science, 1999; 284: 1109; Falk, Am. J. Phys. Anthropol. Suppl., 1999; 28: 126; Falk et al., J. Hum. Evol. [in press]). Here we detail the reasons for thinking the currently accepted endocranial value for Sts 71 is probably correct by providing the first quantitative details of endocranial reconstruction in Sts 71 using three-dimensional computed tomography. Relative brain expansion in the hominid lineage started some half-million years before the earliest appearance of the genus Homo, possibly coincident with enhanced tool-making skills and carnivory.

Animals↗
PubMed2000

Endocranial capacity of the bodo cranium determined from three-dimensional computed tomography.

The 600,000-year-old cranium from Bodo, Ethiopia, is the oldest and most complete early Middle Pleistocene hominid skull from Africa. "Virtual endocast" models created by three-dimensional computed tomography (CT) techniques indicate an endocranial capacity of about 1,250 cc for this cranium (with a reasonable range between approximately 1,200-1,325 cc, depending on how missing portions of the basicranial region are reconstructed). From these determinations, several important implications emerge concerning current interpretations of "tempo and mode" in early hominid brain evolution: 1) already by the early Middle Pleistocene, at least one African hominid species, Homo heidelbergensis, had reached an endocranial capacity within the normal range of modern humans; 2) in spite of its large endocranial capacity, estimates of Bodo's encephalization quotient fall below those found in a large sample of Homo sapiens (both fossil and recent) and Neandertals; and 3) the greatest burst of brain expansion in the Homo lineage may not have been in the last several hundred thousand years, but rather much earlier in the Lower to early Middle Pleistocene.

Ethiopia↗
PubMed2000

Early hominid brain evolution: a new look at old endocasts.

Early hominid brain morphology is reassessed from endocasts of Australopithecus africanus and three species of Paranthropus, and new endocast reconstructions and cranial capacities are reported for four key specimens from the Paranthropus clade. The brain morphology of Australopithecus africanus appears more human like than that of Paranthropus in terms of overall frontal and temporal lobe shape. These new data do not support the proposal that increased encephalization is a shared feature between Paranthropus and early Homo. Our findings are consistent with the hypothesis that Australopithecus africanus could have been ancestral to Homo, and have implications for assessing the tempo and mode of early hominid neurological and cognitive evolution.

Animals↗
PubMed1999

Comparing frontal cranial profiles in archaic and modern homo by morphometric analysis.

Archaic and modern human frontal bones are known to be quite distinct externally, by both conventional visual and metric evaluation. Internally this area of the skull has been considerably less well-studied. Here we present results from a comparison of interior, as well as exterior, frontal bone profiles from CT scans of five mid-Pleistocene and Neanderthal crania and 16 modern humans. Analysis was by a new morphometric method, Procrustes analysis of semi-landmarks, that permits the statistical comparison of curves between landmarks. As expected, we found substantial external differences between archaic and modern samples, differences that are mainly confined to the region around the brow ridge. However, in the inner median-sagittal profile, the shape remained remarkably stable over all 21 specimens. This implies that no significant alteration in this region has taken place over a period of a half-million years or more of evolution, even as considerable external change occurred within the hominid clade spanning several species. This confirms that the forms of the inner and outer aspects of the human frontal bone are determined by entirely independent factors, and further indicates unexpected stability in anterior brain morphology over the period during which modern human cognitive capacities emerged. Anat Rec (New Anat): 257:217-224, 1999.

Biometry↗
PubMed1999

Virtual reality and anthropology.

Since the discovery of the Tyrolean Iceman in 1991 advanced imaging and post processing techniques were successfully applied in anthropology. Specific techniques include spiral computed tomography and 3-dimensional reconstructions including stereolithographic and fused deposition modeling of volume data sets. The Iceman's skull was the first to be reproduced using stereolithography, before this method was successfully applied in preoperative planning. With the advent of high-end graphics workstations and biomedical image processing software packages, 3-dimensional reconstructions were established as a routine tool for analyzing volume data sets. These techniques opened totally new insights in the field of physical anthropology. Computed tomography became the ideal research tool to access the internal structures of various precious fossils without damaging or even touching them. Many of the most precious specimens from the species Autralopithecus (1.8-3.5 Myears), Homo heidelbergensis (200-600 kyears) or Homo neanderthalensis (40-100 kyears) were scanned during the last 5 years. Often the fossils are filled with a stone matrix or other materials. During the postprocessing routines highly advanced algorithms were used to remove virtually these incrustations. Thus it was possible to visualize the morphological structures that lie beneath the matrix. Some specimen were partially destroyed, so the missing parts were reconstructed on computer screen in order to get estimations of the brain volume and endocranial morphology, both major fields of interest in physical anthropology. Moreover the computerized form of the data allows new descriptions of morphologic structures by the means of 'geometric morphometrics'. Some of the results may change aspects and interpretations in human evolution. The introduction of new imaging and post processing techniques created a new field of research: Virtual Anthropology.

Algorithms↗
PubMed1999

The iceman under pressure (Part I): A description of skull deformations due to 5100 years of glacial action.

Due to its long deposition in the glacier, the 'Iceman' (an ice-mummy from the Hauslabjoch) has been deformed, notably its skull. We introduce various comparative methods that describe these deformations, assuming they can be ascribed--to a large extent--to glacial action. While pressure is a scalar, the deformations must be described via a 2-tensor strain field (which can be represented by a matrix function value at every point throughout the skull). In this paper, we present the assumed deformations in numerous graphical forms and, furthermore, the limitations in interpretation--including an estimate of statistical variability--that can be revealed by this analysis. These methods, although describing the results of glacial action and implying a 2-tensor strain field (which will be presented in a subsequent paper), do not permit a straightforward reconstruction of the original, underformed skull. These methods have wider applications to the general problem of deformation.

Austria↗
PubMed1999

Re-evaluation of the endocranial volume of the Guattari 1 Neandertal specimen (Monte Circeo).

The endocranial capacity of Guattari 1 originally was estimated by Sergi as approximately 1.550 cm3. Using three different approaches, a physical endocast, a stereolithographic model, and a virtual endocast, we have estimated the endocranial capacity of Guattari 1 as approximately 1.350 cm3. This paper explains our revision of the estimated endocranial volume of Guattari 1, provides a cautionary case concerning other estimates of endocranial volume, and demonstrates and encourages the use of recent advances in imaging, modeling, and analysis of endocranial volume.

Animals↗
PubMed1999

New methods and techniques in anthropology.

Since the discovery of the Tyrolean Iceman in 1991, advanced imaging and post-processing techniques have been successfully applied to anthropological research. Among the specific techniques are spiral computed tomography and 3-dimensional reconstructions, which include stereolithographic and fused deposition modeling of volume data sets. The Iceman's skull was the first to be produced using stereolithography; subsequently, it has been successfully applied in preoperative planning. With the advent of high-end performance graphics workstations and biomedical image processing software packages, 3-dimensional reconstructions have become established as routine tools for analyzing volume data sets. These techniques enabled dramatically new insights to be gained in the field of physical anthropology. Computed tomography became the ideal research tool to access the internal structures of various precious fossils without even touching--let alone damaging--them. Among the most precious are specimens from the genus Australopithecus (1.8 Myr-3.5 Myr), as well as representatives of Homo heidelbergensis (200 kyr-600 kyr) and Homo neanderthalensis (40 kyr-100 kyr); such fossils have been CT-scanned during the last five years. The fossils often are filled with a stone matrix or other encrustations. During the post-processing routines, highly advanced algorithms were used to remove these encrustations virtually (the concrete fossils remain untouched). Thus it has been possible to visualize the morphological structures that are hidden by the matrix layer. Some specimens have been partially destroyed, but it has been possible for the missing parts were reconstructed on the computer screen in order to get estimations of brain volume and endocranial morphology, both major fields of interest in physical anthropology. Moreover, the data in computerized form allows new descriptions of morphological structures using geometric morphometrics. Some of the results may change aspects and interpretations in human evolution and approaches to long-standing questions in this field. We subsume the introduction of these new imaging and post-processing techniques into a new field of research: Virtual Anthropology.

Animals↗
PubMed1998

Endocranial capacity in an early hominid cranium from Sterkfontein, South Africa.

Two- and three-dimensional computer imaging shows that endocranial capacity in an approximately 2.8- to 2.6-million-year-old early hominid cranium (Stw 505) from Sterkfontein, South Africa, tentatively assigned to Australopithecus africanus, is approximately 515 cubic centimeters. Although this is the largest endocranial capacity recorded for this species, it is still markedly less than anecdotal reports of endocranial capacity exceeding 600 cubic centimeters. No australopithecine has an endocranial capacity approaching, let alone exceeding, 600 cubic centimeters. Some currently accepted estimates of early hominid endocranial capacity may be inflated, suggesting that the tempo and mode of early hominid brain evolution may need reevaluation.

Animals↗
PubMed1998

Virtual anthropology (VA): methodological aspects of linear and volume measurements--first results.

Virtual Anthropology (VA) is the three-dimensional analysis of anthropological objects within a computer environment. For the investigation of fossil hominid material the VA approach is a very powerful and essential technique to obtain quantitative and qualitative data. The permanent accessibility of the virtual objects and the possibility to study inner structures are striking advantages. The present study is an attempt to evaluate the usefulness and problems of VA and to provide data on accuracy and reproducibility. 10 Homo sapiens skulls were CT-scanned and were measured on the computer and with established methods (calipers and mustard seeds/water displacement). Different co-variables like sex, age, observer, and class and dimension of measurement were included. The results are very promising: The mean of absolute difference for linear measurements is 0.71 mm +/- 0.55 (0.58% +/- 0.49), and 31.59 ccm +/- 13.37 (2.26% +/- 0.86) for volume measurements. Reproducibility is 0.11 mm +/- 0.15 for located landmarks and 0.37 mm +/- 0.41 for relocating landmarks. Age and class of measurement are significant factors.

Anthropology, Physical↗
PubMed1997

A comparative study of stereolithographically modelled skulls of Petralona and Broken Hill: implications for future studies of middle Pleistocene hominid evolution.

Computer generated three-dimensional stereolithographic models of middle Pleistocene skulls from Petralona and Broken Hill are described and compared. The anterior cranial fossae of these models are also compared with that of another middle Pleistocene skull, Arago 21. Stereolithographic modelling reproduces not only the outer surfaces of skulls, but also features within the substance of the bones, and details of the internal braincase. The skulls of Petralona and, to a somewhat lesser degree, Broken Hill are extremely pneumatized. Previously undescribed features associated with pneumatization are detailed, along with their possible functional significance, polarity, and potential for understanding hominid cranial variation. Petralona and Broken Hill also exhibit a dramatic suite of cerebral features that is probably related to extensive pneumatization of the skull, namely frontal lobes that are tilted and located behind rather than over the orbits, laterally flared temporal lobes, marked occipital projection, and basal location of the cerebellum. Comparison of the anterior cranial fossae of Petralona, Broken Hill, and Arago 21 suggests that external resemblance of skulls may not always correlate with endocranial similarity. We believe that stereolithographic reconstructions have the potential for helping to resolve difficult questions about the origins of Neanderthal and anatomically modern people.

Animals↗
PubMed1994

Skull of a 5,300-year-old mummy: reproduction and investigation with CT-guided stereolithography.

PURPOSE: In September 1991, a mummified corpse was discovered soon after it was released by the receding ice of the Similaun glacier in the Tyrolean Alps. This body proved to be an astonishingly well-preserved man from the late Neolithic Age or early Bronze Age. To preserve the fragile mummy, scientific investigations were required to be as noninvasive and nondestructive as possible. MATERIALS AND METHODS: A radiologic investigation that included conventional radiography, digital radiography, and whole-body computed tomography (CT) was performed from the CT data, the skull was duplicated by means of stereolithography. RESULTS: The copy of the prehistoric skull was validated by means of comparison of measurements obtained from the original CT images and from external physical measurements of the intact head of the mummy. CONCLUSION: The CT images, radiologic findings, and duplicated skull are expected to provide anthropologists and other interested scientists relatively accurate information without the need to handle the mummy, to expose it to the considerable risks of repeated partial thawing, or to perform invasive exploratory studies such as autopsy.

Animals↗
PubMed1993

Iron status and iron supplementation in children with classical phenylketonuria.

Iron (Fe) status and Fe supplementation were assessed in 20 children with phenylketonuria (PKU) through dietary intake and through measurements of ferritin, hematocrit, hemoglobin, mean cellular hemoglobin, mean cellular volume, serum Fe, total iron binding capacity, unbounded iron binding capacity, transferrin saturation and transferrin. Findings were compared to reference values and to data from age-matched controls. The prescribed phenylalanine-restricted diet supplied all the recommended nutrients. Dietary Fe was present in the diets, but its bioavailability is questionable as several laboratory results were not within accepted reference values. A ferrous sulphate supplement (5 mg elemental Fe/kg daily) was given for 120 days to a group of PKU children with lower Fe parameters, thus changing some of the parameters studied. Serum ferritin (p < 0.1), transferrin saturation and serum Fe (p < 0.05) increased after the treatment. The need for improved diagnosis of Fe status and determination of whether PKU children can benefit from therapeutic Fe is discussed.

Child↗