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Biomedical subjects

R L Holloway

Publications and source records attributed to R L Holloway.

At least 19 recordsLinked to original sources
PubMed1992

Corpus callosum in sexually dimorphic and nondimorphic primates.

The midsagittal area and other morphological measures were taken on the corpus callosum of four different species of primate: Macaca mulatta, M. fascicularis, Callithrix jacchus, and Saguinus oedipus. The first two species are strongly dimorphic, whereas the New World forms show little dimorphism with regard to overall body size, canines, and brain weight. Neither total corpus callosal area (TOTALCC), or other parts of the corpus callosum (CC) showed any significant sexual dimorphism in any of the primate species sampled. Only in M. mulatta did a sexual dimorphism appear to be significant. In males of this species, the dorsoventral width of the splenium was larger than in females. In addition, the anterior commissure (ANTCOMM) evinced no sexual dimorphism in the different species. Brain weight was significantly dimorphic in only M. mulatta, and when ratio data were used to correct for brain weight, no significant differences were found in the corpus callosum. This is in contrast to Homo sapiens, where the relative size of the CC has been reported to be larger in females, and particularly so in the posterior, or splenial portion of the CC. Correlation coefficients were calculated for the various variables within each species. In general, most of the callosal measures are significantly inter-correlated, although the exact pattern varies for each species. Thus, unlike Homo sapiens, or pongids such as Gorilla and Pan, neither New nor Old World monkeys show any striking evidence for sexual dimorphism in the corpus callosum.

Animals↗
PubMed1992

Relationship of squamosal suture to asterion in pongids (Pan): relevance to early hominid brain evolution.

Based on 244 measurements of the relationship of the squamosal suture to the landmark asterion in 49 chimpanzee skulls, it is shown that in the normal lateral view the squamosal suture is very rarely inferior to asterion. In hominid crania, the squamosal suture is always well superior to asterion. Even in Pan, that part of the squamosal suture most homologous with the remnant found on the Hadar AL 162-28 Australopithecus afarensis hominid cranial fragment is very rarely inferior to asterion. Such variability suggests that Falk's (Nature 313:45-47, 1985) orientation of the Hadar specimen is incorrect; she places asterion superior to the position of the squamosal suture if projected endocranially. The implication for the brain endocast is that, however the fragment is oriented, the posterior aspect of the intraparietal (IP) sulcus is in a very posterior position relative to any chimpanzee brain. The distance from the posterior aspect of IP to occipital pole is twice as great in chimpanzee brain casts than on the Hadar AL 162-28 endocast, even though the chimpanzee brain casts are smaller in overall size. This suggests that brain reorganization, at least as exemplified as a reduction in primary visual striate cortex (area 17 of Brodmann), occurred early in hominid evolution, prior to any major brain expansion.

Animals↗
PubMed1992

Differences between patient and physician perceptions of predicted compliance.

One approach to improving patient compliance is for physicians to adapt their behaviour to fit patients' psychological characteristics. Previous university-based research has suggested that physician adaptation to patients' locus of control interferes with patient-physician congruence on expected compliance, but not with congruence on satisfaction with their relationship. This study was conducted in a community practice to clarify the relationship between the physician's adaptation to locus of control and likelihood of and commitment to compliance, and satisfaction with the doctor-patient match. One physician saw 148 patients with a variety of illnesses after they had completed the Health Locus of Control (HLC) questionnaire. The physician altered how he spoke with a patient based on whether the patient scored internally or externally on the HLC. After the encounter, both patient and physician rated the patient's likelihood of and commitment to complying with each of the three recommendations. The physician and each patient also rated their satisfaction with the match between them. Patients' ratings of commitment, likelihood, and satisfaction were significantly higher than those of the physician. Unlike earlier results, there were strong correlations between the patients' and physician's estimates of compliance (commitment and likelihood). Just as with the previous study, there was no correlation between the levels of physician and patient satisfaction with their match. This study indicates that physician adaptation to patients' locus of control does not interfere with compliance outcomes of doctor-patient encounters. Whether such adaptation will improve compliance outcomes is yet to be determined.

Adult↗
PubMed1990

Assessing threats to the validity of experimental and observational designs.

Experimental designs, particularly the randomized trial, are viewed as the most scientifically rigorous methods by which knowledge is attained. Most clinical disciplines, however, use observational study designs more frequently than experimental designs. Nevertheless, the scientific rigor of experimental designs can be approximated by observational designs if common internal validity threats are recognized and addressed during the development of the research protocol. This paper presents a model of threats that can be applied to both types of designs to compare their scientific merits.

Case-Control Studies↗
PubMed1989

Anatomical brain asymmetry in monkeys: frontal, temporoparietal, and limbic cortex in Macaca.

Measurements evaluating possible cerebral hemispheric asymmetries were taken by hand on frontal, parietal, and temporal cortex on 60 formalin-fixed Macaca mulatta and Macaca fascicularis brain specimens. No statistically significant (P less than 0.05) right/left side differences in the mean length of four sulci in visual-processing areas of the cortex were found. The sulcus adjacent to the region cytoarchitecturally homologous to the motor speech area in the human brain did not show pronounced asymmetry. In both species, however, a small parietal lobe sulcus showed greater development on the left hemisphere than in the right. In measurements made using digital planimetry, right/left side differences in the area of the dorsal cingulate gyrus were not found. Behavioral evidence suggests that monkeys do not exhibit a consistent pattern of cerebral dominance for functions associated with most of these regions of the brain.

Animals↗
PubMed1989

Academic promotion and tenure in U.S. family medicine units.

The authors interviewed by telephone the heads (or their representatives) of 101 of the 120 family practice units in U.S. medical schools in 1987. Each respondent was asked for his or her personal perceptions of the relative importances of research, teaching, patient care, and administrative activities in the academic promotion process. Respondents were also asked for their views of their units' and institutions' perceptions of the importances of the same four activities in the promotion process, as well as other related questions about promotion and tenure. The findings indicate that there is still a significant incongruence between the value structure of most family practice units and that of their institutions but that many family practice units are beginning to achieve parity of promotion and tenure with other departments in their institutions.

Career Mobility↗
PubMed1988

Anatomical brain asymmetries in New World and Old World monkeys: stages of temporal lobe development in primate evolution.

Relatively large (n = 20-30) samples of formalin-fixed brain specimens from five Old and New World monkey species were examined in a study measuring anatomical temporal-lobe asymmetries. Linear measurements of the length of the Sylvian fissure were taken on each cerebral hemisphere to evaluate lateral differences related to development of auditory association cortex. The results indicate significantly greater Sylvian fissure length on the left hemisphere than on the right hemisphere in four of these species. Measurements of a different parameter on Saimiri sciureus brain specimens (length of anterior portion of the Sylvian fissure) also suggested temporal-lobe asymmetry favoring the left hemisphere. Other measurements (length of the Sylvian fissure lying posterior to the central sulcus, and dorso-ventral position of the Sylvian point) in Macaca mulatta and M. fascicularis did not reveal significant right/left-hemisphere differences. Sylvian-fissure length determined from photographs of M. mulatta hemispheres in contrast to results of direct measurements did not yield significant right/left-hemisphere asymmetry. We mention possible reasons why previous anatomical studies of brains from monkeys did not discern temporal-lobe asymmetry, and we also discuss whether or not certain of these asymmetries in monkeys foreshadowed the evolution of language-processing areas of the cerebral cortex in hominids.

Animals↗
PubMed1988

Some additional morphological and metrical observations on Pan brain casts and their relevance to the Taung endocast.

Using an increased sample of chimpanzee brains and brain casts, 32 hemispheres were measured to determine the variability of OP-FP (occipital-pole) and OP-LS (occipital pole-lunate sulcus) arc dimensions and their ratios. The Taung endocast was remeasured to test Falk's assertions that the lunate sulcus is in a pongid position. The average ratio for the chimpanzee brains was 0.218, a value more than 2+ S.D.'s posterior to Falk's placement of the lunate sulcus on the Taung specimen. It is suggested that the chimpanzee and Taung occipital poles have a different morphometric pattern, the former being coincident with the caudal end of the LC (lateral calcarine) fissure. The Taung OP-LS arc consistently measured at least 42 mm, and not 40 mm as claimed by Falk.

Animals↗
PubMed1988

Aptitude X treatment interactions: implications for patient education research.

Aptitude x treatment interaction (ATI) has been used only rarely in patient education research. This research paradigm incorporates individual differences (aptitudes) into experimental studies exploring differences in information strategies (treatments). ATI has great potential for applications to patient education research. It identifies patient characteristics and optimal instructional treatments, it is compatible with psychological theories and clinical approaches alike, and it offers a specific methodology for approaching existing problems in a new way. This article presents studies in which ATI has illuminated specific patient needs and treatments, and suggested further applications. Three studies (in addition to those reviewed) are examined in depth. One study determined general guidelines for designing instructional literature to accompany medication (drug package inserts), that would satisfy the requirements of a group of patients with varied reading ability. Another study examined the effect of patients' "prior knowledge" on their participation in a health education program. A third study explored the interaction between patients' view of self-control over their health and the use of different media for health-care instruction. Guidelines and considerations for conducting further ATI-based research are presented and discussed.

Aptitude↗
PubMed1987

Assessment by patients of their health education needs.

One hundred ninety-two patients of three family practice clinics were surveyed about their health information needs. The largest gaps between present and desired knowledge were in cardiopulmonary resuscitation and immunizations. Other major differences concerned mind/body relationships, health risk reduction, coverage of health care costs and nonprescription medications. There was little knowledge discrepancy with regard to the problem for which the patients saw their physicians. This technique is recommended as a way for clinics to target their patient education efforts more effectively.

Ambulatory Care Facilities↗
PubMed1986

Sexual dimorphism in the human corpus callosum: an extension and replication study.

Using a new sample of 16 human brains (F = 8, M = 8), it was found that the splenial portion of the corpus callosum was larger and more bulbous in females than in males. In addition, the total area of the corpus callosum was both absolutely and relatively larger in females than in males, with the relative measurements (i.e., to brain weight) differing significantly. This was also true when using exponential values of brain weight commensurate with the areas and linear distances of the corpus callosum. These results, which replicate the findings of earlier work, were found by the two authors using different methods, and working independently of each other. We believe these findings provide a partial anatomical basis for purported gender differences in cognitive task behaviour, and are related to early gonadal steroidal influences during prenatal development.

Adult↗
PubMed1986

Sex differences in the fetal human corpus callosum.

Midsagittal sections of fetal cerebra from the Yakovlev collection ranging from 26-41 weeks gestational age were photographed. The photographs were used to obtain areal measurements of the cross-sectional surface of the corpora callosa; and linear measurements of the widths of genu, body and splenium. A significant sex difference, favoring females, was found in the splenial width of the corpus callosum by 26 weeks gestational age. Although other variables, including the overall cross-sectional area of the corpus callosum, were larger in females both absolutely and relative to brain weight, the differences were not statistically significant. These results suggest that the gonadal steroids and/or genetic sex have an important role in utero in the differentiation of neural structures not associated with reproductive functions. Elaboration of sex differences, however, may occur postnatally.

Corpus Callosum↗
PubMed1985

Brain shrinkage in chronic alcoholics: a pathological study.

A quantitative neuropathological necropsy study of 22 control and 22 chronic alcoholic subjects showed a statistically significant loss of brain tissue in the chronic alcoholic group. The loss of tissue appeared to be from the white matter of the cerebral hemispheres rather than the cerebral cortex. This may reflect a primary alteration in the composition or structure of the white matter or it may be secondary to loss of nerve cells from the cortex with subsequent degeneration of the axons in the white matter. Further morphometric analyses including cortical neuronal counts will be necessary to clarify this issue.

Adolescent↗