Search PubMed⌕ Search

Biomedical subjects

A E Peterson

Publications and source records attributed to A E Peterson.

At least 19 recordsLinked to original sources
PubMed1998

Facial measurements in clinical genetics: How important are the instruments we use?

Prompted by our finding that a popular compendium of clinical measurements often suggests a transparent ruler as a suitable substitute for anthropometric calipers (which were typically used by the original researchers to collect the normative data), we compared facial measurements taken with a ruler and calipers. Our objectives were to compare facial measurement data taken with these instruments by two classes of observer: expert and inexperienced. Ten facial measurements were repeated on four medically normal women by one expert and one inexperienced observer. Both observers' data showed that the caliper-derived means were usually the larger, but, whereas the expert observer's caliper-derived data typically were the least variable, the novice observer had smaller standard deviations and ranges for the ruler-derived data. Statistically significant differences were found between the ruler- and caliper-derived data from both observers on all four subjects, except for subnasale-pogonion and stomion-pogonion. For the novice observer only, endocanthion-endocanthion, left exocanthion-endocanthion, and alare-alare were also nonsignificant. The calibrations of the sliding caliper and ruler were compared to determine if differences between them could explain the statistical results, but were the same. We concluded that the differences between the caliper- and ruler-derived measurements resulted because the ruler often could not be placed directly on the landmarks, as could the arms of the calipers. We recommend that clinicians interested in taking facial measurements to assess their patients consult the original publications for information on the techniques and instruments used so that reliable comparisons with the normative data can be made.

Craniofacial Abnormalities↗
PubMed1998

Technical note: Different techniques, different results--a comparison of photogrammetric and caliper-derived measurements.

The primary goal of our study was to compare photogrammetric measurements with caliper-derived measurements. We also looked at the difference between caliper-derived measurements that were taken with and without the landmarks marked. Thirteen facial measurements were repeated ten times on two adult subjects as follows: 1) Calipers were used to take the measurements before the landmarks were marked on each subject's face; 2) the landmarks were then marked with a black pencil, and the calipers were used to take the measurements again; and 3) images were taken of each subject with the markings left on the face, and the measurements were extracted from these images. Compared with the caliper-derived data taken with the landmarks marked, the photogrammetric means and standard deviations were typically larger, leading us to conclude that there was a systematic difference between the data. The generally greater variation in the photogrammetric measurements was ascribed to poor conditions, such as shadows, oblique markings, and unmarked landmarks. When the data gathered by caliper with and without the landmarks marked were compared, a systematic difference was suggested by the number of statistically significant t-test probabilities. Marking the landmarks reduced the standard deviations in some measurements by controlling two sources of variation: differing pressure on the skin and slippage of the calipers. Anthropologists, medical geneticists, and others who use measurements for diagnostic or classificatory purposes should be aware that data gathered by different techniques may yield different results.

Adult↗
PubMed1997

Multicenter study of the Lactational Amenorrhea Method (LAM): I. Efficacy, duration, and implications for clinical application.

A multicenter study of the Lactational Amenorrhea Method (LAM) was carried out to test the acceptability and efficacy of the method. Additionally, the data are used to test new constructs for improvement of method criteria. A protocol was designed at the Institute for Reproductive Health (IRH), Department of Obstetrics and Gynecology, Georgetown University Medical Center, a World Health Organization (WHO) Collaborating Center, and was reviewed and modified in collaboration with the co-sponsors, the World Health Organization and the South to South Cooperation for Reproductive Health, and the principal investigators from each site. Data were gathered prospectively on LAM acceptors at 11 sites. Data were entered and cleaned on-site and further cleaned and analyzed at IRH, using country-level and pooled data to produce descriptive statistics and life tables. The 98+% efficacy of LAM is confirmed in a wide variety of settings. In addition, the results yield insight on the possibility of continued use beyond 6 months. LAM is found to be highly effective as an introductory postpartum method when offered in a variety of cultures, health care settings, socio-economic strata, and industrial and developing country locales. In addition, LAM acceptance complements breastfeeding behaviors without ongoing breastfeeding support services. The parameters studied yield high efficacy and method continuation. Therefore, the basic tenets of the 1995 Bellagio consensus on LAM is reconfirmed and it is recommended that LAM be reconfirmed and it is recommended that LAM be incorporated into hospital, maternity, family planning, maternal and child health, and other primary health care settings.

Adult↗
PubMed1997

Multicenter study of the Lactational Amenorrhea Method (LAM): II. Acceptability, utility, and policy implications.

A multicenter study of the Lactational Amenorrhea Method (LAM) was carried out to determine acceptability, satisfaction, and utilization in 10 different populations, and to confirm the efficacy of the method. Efficacy data are presented in a companion paper. A protocol was designed at the Institute for Reproductive Health (IRH), Department of Obstetrics and Gynecology, Georgetown University Medical Center, and reviewed and modified in collaboration with the co-sponsors, the World Health Organization, the South-to-South Cooperation for Reproductive Health, and the principal investigators from each site. Data were gathered prospectively on LAM users at 11 sites. Data were entered and cleaned on-site, and further cleaned and analyzed at IRH, using country-level and pooled data to produce descriptive statistics. The overall satisfaction with LAM was 83.6%, and continuation with another method of family planning was shown to be 67.6% at 9 months postpartum, in most cases exceeding previous use of contraception prior to use of LAM. Knowledge and understanding of the method at discontinuation were high, ranging from 78.4 to 88.6% for the three criteria. LAM can be used with a high level of satisfaction and success by women in a variety of cultures, health care settings, socio-economic strata, and industrial and developing country settings. The results confirm that LAM is acceptable and ready for widespread use, and should be included in the range of services available in maternal and child health, family planning, and other primary health care settings.

Adult↗
PubMed1996

Event-related potentials in schizotypal personality disorder.

This study examined whether abnormalities in event-related potentials (ERPs), reported in schizophrenia, extend to patients with schizotypal personality disorder (SPD). Auditory ERPs in an oddball paradigm were obtained in 19 SPD patients, 17 schizophrenic patients, and 20 normal control subjects (NCs). Schizophrenic patients had lower P300 amplitude than NCs; the P300 amplitude of SPD patients was intermediate, showing a linear trend but not a significant group difference. P200 amplitudes showed a similar trend. SPD patients had N100 and N200 amplitudes intermediate to schizophrenic patients and NCs, without significant group differences. Results suggest diminished P300 amplitude may not be as prominent in SPD as in schizophrenia. Studies with larger sample sizes, multiple lead assessment strategies, and more demanding tasks may further characterize ERP deficits in schizophrenia-spectrum disorders such as SPD.

Adult↗
PubMed1996

The use of breast milk substitutes in developing countries: the impact of women's employment.

OBJECTIVES: This study quantified the influence of employment, specifically a mother's employment away from her infant, on the use of breast milk substitutes in developing countries. METHODS: Data from the Demographic and Health Surveys were used to calculate the population attributable risk percentage for use of breast milk substitutes among women employed away from their babies in 15 countries for which suitable data were available. RESULTS: The estimated proportion of breast milk substitute use attributable to employment away from the baby ranged from 0.74% to 20.9% in the various countries. CONCLUSIONS: Employment is not the main determinant of breast milk substitute use. Efforts to improve breast-feeding can be safely targeted at the majority of women who are not employed away from their babies while nevertheless giving appropriate attention to the minority of new mothers who are employed away from their babies.

Adult↗
PubMed1992

A video digitizer for analysis of trunk deformity in scoliosis.

Scoliosis is a deformity characterized by lateral curvature of the spine and accompanied by axial rotation of the vertebrae; it often causes varying degrees of trunk deformity. Research has indicated that topographic techniques can be used to describe the disorder and monitor its progression. A video image acquisition system has been designed which reduces the time required to quantify topographic details of the trunk and aids in the diagnosis, monitoring and research of scoliosis. This system integrates the capability of large, expensive grey-scale image acquisition equipment into a small, low-cost diagnostic imaging tool using current technologies and design techniques. The video digitizer accepts a standard NTSC monochromatic video signal as input and the unit is connected to a computer via an IEEE-488 bus from which the ditigizer is controlled. The digitizer samples the video signal in real time using a high-speed flash converter controlled by an application-specific integrated circuit; the digital samples are stored in memory until the host computer requests that the information be transferred.

Adolescent↗
PubMed1990

Eye tracking impairment in clinically identified patients with schizotypal personality disorder.

Eye tracking accuracy, which has been found to be impaired in schizophrenic patients and their relatives, was assessed in 26 patients with schizotypal personality disorder, 17 control subjects with other non-schizophrenia-related personality disorders, 29 normal control subjects, and 44 schizophrenic patients. Both schizotypal and schizophrenic patients, but not control subjects with other personality disorders, demonstrated significantly more impaired tracking than the normal control subjects. These results suggest that patients with clinically defined schizotypal personality disorder may be biologically related to schizophrenic patients as part of a spectrum of schizophrenia-related disorders.

Adult↗
PubMed1989

Eye tracking, schizophrenic symptoms, and schizotypal personality disorder.

Schizophrenic patients and patients with schizotypal personality disorder were significantly more likely than normal controls to demonstrate impaired eye tracking performance. Fifteen of 27 schizophrenics and 15 of 27 schizotypals had impaired eye tracking, compared with 11 of 39 normal controls. In the schizophrenic group, including 10 out-patients in a stable state of relative remission, impaired eye tracking was associated with more severe formal thought disorder and more time spent in psychiatric hospitals. Among stable schizophrenic out-patients, poor eye tracking was related to more severe formal thought disorder and greater overall psychopathology. This pattern of results suggests a possible relation between eye tracking impairment and more severe enduring symptoms across the spectrum of schizophrenic and schizophrenia-related disorders.

Adult↗
PubMed1989

Biochemical, biomechanical, and physical changes in the skin in an experimental animal model of therapeutic tissue expansion.

Biochemical, biomechanical, and physical changes occurring in the skin during tissue expansion have been studied using an animal model in which a Silastic expander was inserted into the peritoneal cavity. Forty-eight Sprague-Dawley rats were divided into four groups to be studied at 4, 8, 16 and 32 days after expansion. In the experimental animals (6 per group) the expander was inflated by a single injection of 120 ml of saline. Sixteen hours prior to sacrifice each animal received a single injection of tritiated proline. Sixteen days after expansion both the specific activity and the total content of hydroxyproline in the skin were significantly elevated in experimental animals. Intrinsic skin tension increased dramatically at the time of inflation but fell almost to control values at the end of 32 days. Skin thickness, initially decreased, returned to normal by the end of the experiment. There were no significant differences in breaking strengths between skin from experimental and control animals. Skin surface area, initially increased by stretching at the time of inflation, increased further between Days 0 and 8, possibly as a result of stress relaxation combined with enhanced remodelling of connective tissue macromolecules, and again from Days 24 to 32. We conclude that, during tissue expansion, there is a net accumulation of collagen in the skin and that this allows the local cellular environment to return to normal with respect to pressure and/or tension.

Animals↗
PubMed1981

Pharmacokinetics of captopril in dogs and monkeys.

[14C]Captopril was given as a priming dose, followed by constant intravenous infusion for 4 or 6 hr, to three anesthetized dogs and three anesthetized monkeys. Blood, urine, and bile samples were collected during and after drug infusion. Pharmacokinetic evaluations were carried out exclusively on data obtained for unchanged captopril. The average total body clearance (ClT) and the renal clearance (ClR) of captopril, in milliliters per kilogram per hour, were 605 and 341 in the dog and 1135 and 944 in the monkey. The biliary clearance of captopril was negligible in both species. The greater difference between the ClR and ClT values in the dog compared to that in the monkey was the result of more extensive metabolism of captopril by the dog. Since almost all of the radioactive dose was recovered in urine in both species, captopril and its metabolites were almost exclusively eliminated by the kidneys. One primary reason that body and renal clearance values of captopril were much greater in the monkey than in the dog was that the net tubular secretion fo captopril was about three times greater in the monkey (82%) than in the dog (28%). The volume of distribution of captopril was higher in the monkey (3.6 liters/kg) than in the dog (2.6 liters/kg); the volume of the central compartment was about the same (0.5 liter/kg) for both species. The terminal half-life value was slightly higher in the dog (2.8 hr) than in the monkey (2.2 hr).

Anesthesia↗