Biomedical subjects

D B Sheffer

Publications and source records attributed to D B Sheffer.

11 recordsLinked to original sources

PubMed1999

Growth changes in measurements of upper facial positioning.

Growth changes in the position of the midline upper face are examined for samples of Pan troglodytes, Gorilla gorilla, and modern humans. Horizontal and vertical distances between nasion and the anterior end of the cribriform plate are plotted against stage of dental development. Kendall's nonparametric correlations between facial positioning and stage of dental development are tested for significance. In African apes, the upper face becomes more projecting and positioned higher relative to the anterior cranial base. The extent of this horizontal and vertical separation reflects primarily facial size. In modern humans, the upper face becomes more projecting but is relatively stable in its vertical position. Comparison of Pan and modern human crania in the youngest dental age category indicates that the upper face of modern humans is positioned lower early in postnatal life. The position of the upper face (glabella) relative to the anterior and posterior cranial base is presented for several fossil hominid crania. The fossil crania are similar to Pan and modern humans in facial projection relative to the anterior cranial base. However, glabella is positioned low in the fossil crania. Total facial projection (relative to hormion) for Sts 5 is similar to the mean for Gorilla. Fossil Homo and robust australopithecine crania display very projecting upper faces. We suggest that the upper face of Homo is projecting due to the length of the anterior cranial fossa, while robust australopithecines possess a thick frontal bone.

Animals↗

PubMed1999

Growth changes in internal and craniofacial flexion measurements.

Growth changes in both internal and craniofacial flexion angles are presented for Pan troglodytes, Gorilla gorilla, and modern humans. The internal flexion angle (IFA) was measured from lateral radiographs, and the craniofacial flexion angle (CFA) was calculated from coordinate data. Stage of dental development is used as a baseline for examination of growth changes and nonparametric correlations between flexion angles and dental development stage are tested for significance. In Gorilla, the IFA increases during growth. The IFA is relatively stable in Pan and modern humans. Pan and Gorilla display an increase in the CFA. However, this angle decreases during growth in modern humans. Flexion angles were derived from coordinate data collected for several early hominid crania. Measurements for two robust australopithecine crania indicate strong internal flexion. It has been suggested that cerebellar expansion in this group may relate to derived features of the posterior cranial base. In general, australopithecine crania exhibit craniofacial flexion intermediate between great apes and modern humans. The "archaic" Homo sapiens specimen from Kabwe is most similar to modern humans.

Animals↗

PubMed1991

Use of biostereometric analysis as a screen for breast cancer.

Biostereometric analysis, a photographic surface imaging technology that is noninvasive, was tested for its effectiveness in selecting breast pathology in a sample of 1000 female subjects, including 80 with cancers, 635 normals, and 285 with benign breast conditions. These individuals were recruited from the population of women undergoing routine mammographic examination. The project was designed specifically to determine whether biostereometric analysis could identify the individuals in the sample with malignant breast disease in the hope of providing information to aid in future development of a breast cancer screening protocol. The overall sensitivity of the method for cancers of all sizes was 76%. Biostereometric analysis was 85% sensitive for selection of cancers in the subjects over 50 years of age, and identified 80% (4 of 5) of the subjects with clinically confirmed breast cancers less than 1 cm in size. The method was 69% specific, but identified benign breast disease in only 51% of cases.

Adult↗

PubMed1989

Breast volume measurement of 598 women using biostereometric analysis.

A study of the volumes of the right and left breasts of 598 subjects was undertaken using biostereometric analysis. This measurement uses close-range stereophotogrammetry to characterize the shape of the breast, and is noncontact, noninvasive, accurate, and rapid with respect to the subject involvement time. Using chi-square tests, volumes and volumetric differences between breast pairs were compared with handedness, perception of breast size by each subject, age, and menstrual status. No significant relationship was found between the handedness, age, or menstrual status of the subject and the breast volume. Several groups of subjects were accurate in their perception of breast size difference. Analysis did confirm the generally accepted clinical impression of left-breast volume dominance. These results are shown to be consistent with those of a previous study using 248 women.

Adult↗

PubMed1988

Biostereometric analysis for breast cancer detection.

A measurement technique has been developed for noninvasive breast cancer detection. The process involves the use of close-range stereophotogrammetry as a data acquisition device for the determination of breast surface concavities. We report the methodology used to detect these surface depressions, the rationale for the study, and our preliminary findings.

Algorithms↗

PubMed1987

Breast volume measurement of 248 women using biostereometric analysis.

A study of volumes of the right and left breasts of 248 subjects was undertaken using biostereometric analysis. This measurement technique uses close-range stereophotogrammetry to characterize the shape of the breast and is noncontact, noninvasive, accurate, and rapid with respect to the subject involvement time. Volumes and volumetric differences between breast pairs were compared, using chi-square tests, with handedness, perception of breast size by each subject, age, and menstrual status. No significant relationship was found between the handedness of the subject and the larger breast volume. Several groups of subjects based on age and menstrual status were accurate in their perception of breast size difference. Analysis did not confirm the generally accepted clinical impression of left breast volume dominance. Although a size difference in breast pairs was documented, neither breast predominated.

Adult↗

PubMed1987

Right and left breast volume and volume distribution comparisons in normal and tumor-containing breasts.

A measurement technique involving the use of close-range stereophotogrammetry has been developed for the study of breast volume and volume distribution (shape) comparison. This biostereometric method has been shown to be able to measure volume to within 0.63% of that determined by water displacement. This study describes the rapid and non-invasive data acquisition methodology as well as the mathematical algorithms used to determine breast volume. Additionally, the paper discusses the application of this process to documenting the presence or absence of total volume and volume distribution differences existing in normal breasts and those containing benign and malignant tumors.

Adult↗

PubMed1986

Validity and reliability of biostereometric measurement of the human female breast.

A measurement technique has been developed for application in the area of noninvasive breast cancer detection. The measurement process involves the use of close-range stereophotogrammetry as a data acquisition device necessary for determination of breast volume and volume distribution. This report details the methodology used to acquire and analyze stereopair photographs necessary to document the validity and reliability of this application. The volume of a test object was determined by both water displacement and stereophotogrammetric analysis to estimate the precision of the proposed methodology. Additionally, the reliability component of the study was documented by analyzing variability of coordinates representing a series of locations marked on the surface of an irregularly shaped object. Both tests confirm that this stereometric analysis is a reliable and valid method of measurement and may be well suited for further development in the field of breast cancer detection.

Biomedical Engineering↗

PubMed1981

Breast cancer detection utilizing biostereometric analysis.

Twelve female patients participated in a study designed to employ computer-assisted biostereometric analysis for the detection of breast masses. All breast masses were previously documented by physical examination and followed by xeromammography, stereophotography, and histopathologic confirmation of tumor type. "Contour mammograms" were produced from the biostereometric photographs. These data were analyzed first for tumor detection and location by visual inspection. A second analysis employed a computed algorithm designed to locate and measure surface aberrations that suggest the possibility of underlying breast tumor. Visual analysis yielded the exact location of breast tumors in eight of the ten malignancies; computer analysis exactly located nine of the ten malignancies. In the computer analysis, one malignancy not exactly located by quadrant was, nevertheless, located in the correct breast. The results of the study suggest that the biostereometric process may have future use in screening or prescreening procedures for breast cancer detection. It is noninvasive, applicable to large numbers of women and with suitable refinements, and capable of being fully automated.

Aged↗

PubMedDate not supplied

Determination of the prime electrostatic endothelial cell transplantation procedure for e-PTFE vascular prostheses.

The purpose of this study was to evaluate the extent of cellular adhesion (density and morphological maturation), cellular membrane damage, and cellular viability after an electrostatic transplantation of human umbilical vein endothelial cells (HUVECs) onto 6-cm segments of 4-mm I.D. e-PTFE (GORE-TEX) vascular prostheses using a prototype electrostatic endothelial cell transplantation device (EECTD). The electrostatic transplantation parameters evaluated were the apparatus-applied voltage and transplantation time. By our definition, the combination of applied voltage and transplantation time that met the a priori criteria of: 1) maximum transplanted cellular viability, 2) maximum transplantation density, 3) maximum morphological maturation (degree of cellular flattening), and 4) minimal cellular membrane damage would be the prime transplantation procedure. The results of the experimentation indicated that the prime conditions for HUVEC transplantation were obtained when +1.0 V was applied for a transplantation time of 16 min. These conditions achieved an average viable graft surface coverage of 97.4+/-1.6% with an average transplantation density of 73,540+/-8.514 HUVECs/cm2. Furthermore, the transplanted HUVECs were morphologically mature (flattened) with minimal apparent cellular membrane damage (lysis or pitting). The overall clinical significance of this study is that viable endothelial cell transplantation to synthetic vascular grafts can be accomplished at high cellular densities and morphological maturation in 16 min using the EECTD. With the promising in vitro transplantation results, the next logical investigations will include additional in vitro evaluations (cellular retention upon shear stress exposure and biochemical assays) followed by in vivo evaluations to examine thromboresistance and influence on intimal/anastomotic hyperplasia.

Blood Vessel Prosthesis↗

PubMedDate not supplied

Understanding techniques for measuring cardiac output.

In summary, use of thermodilution as a method to measure cardiac output has attained universal appeal in the clinical environment. Other means of detecting cardiac output (impedance-cardiogram and ballistocardiogram, to name two) have been developed and are being used clinically, but the development of the flow-directed thermodilution catheter has profoundly affected the universal acceptance of the thermodilution method. Thermodilution techniques, when performed properly, are capable of obtaining accurate and reproducible results. Medical and nursing personnel who are educated in proper procedures will be able to make educated choices when faced with difficult decisions. It is likely that they will turn to the biomedical or clinical engineering department for help if those personnel are well informed regarding the techniques and procedures.

Cardiac Output↗