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Biomedical subjects

Brian Freeman

Publications and source records attributed to Brian Freeman.

9 recordsLinked to original sources
PubMed2006

Integrating histology and histopathology teaching in practical classes using virtual slides.

The new medicine program at the University of New South Wales employs scenario-based learning with vertically integrated classes of year 1 and year 2 students, as well as horizontally integrated teaching with no discipline-specific courses. Coinciding with its introduction, we undertook comprehensive revision of the approach to teaching microscopic anatomy and pathology. We designed practical classes around virtual slides, which are high-magnification digital images of tissue sections stored in a multiresolution file format, viewable in a Web browser in a manner closely simulating conventional microscopy. In these classes, we integrated the teaching of histology and histopathology, introducing students to the microscopic features of tissues and organs, and giving them the opportunity to compare and contrast the normal with the abnormal in various disease states. Members of academic staff from both anatomy and pathology were present to promote discussion and respond to questions. Worksheets defined learning objectives and provided clinical cases as contexts for learning in each class. Evaluation revealed that students strongly supported the integrated approach. The efficiency of the teaching method meant that it was possible to work through 5-8 virtual slides per 2-hr class without difficulty. Students displayed considerable initiative in exploring the histological features of tissues, identifying the changes in various pathological states, and recognizing their relationship to clinical manifestations. We believe that the approach we have developed should help to minimize the potential adverse impact of curriculum reform on the teaching of morphology, while ensuring that learning remains both meaningful and interesting.

Computer Simulation↗
PubMed2005

Simple formula for the surface area of the body and a simple model for anthropometry.

The body surface area (BSA) of any adult, when derived from the arithmetic mean of the different values calculated from four independent accepted formulae, can be expressed accurately in Systeme International d'Unites (SI) units by the simple equation BSA = 1/6(WH)0.5, where W is body weight in kg, H is body height in m, and BSA is in m2. This formula, which is derived in part by modeling the body as a simple solid of revolution or a prolate spheroid (i.e., a stretched ellipsoid of revolution) gives students, teachers, and clinicians a simple rule for the rapid estimation of surface area using rational units. The formula was tested independently for human subjects by using it to predict body volume and then comparing this prediction against the actual volume measured by Archimedes' principle.

Adult↗
PubMed2005

An immunohistochemical study of human fetal liver in the Meckel-Gruber syndrome.

AIMS: The ductal plate abnormality of the liver in fetuses with the Meckel-Gruber syndrome has been well characterised, but its aetiology remains unknown. We have analysed liver structure in six fetuses with this syndrome, using routine histology, immunocytochemistry, and electron microscopy. METHODS: Liver tissue from six fetuses of 11-27 weeks gestational age was examined by immunoperoxidase staining with antigens to cyokeratin (AE1/3) and polyclonal CEA. We also examined the ultrastructure of the syndromic fetal liver. The findings were compared with livers of control fetuses obtained from miscarriages, of similar size and gestational age but without dysmorphic features or developmental anomalies. RESULTS: The ductal plate abnormality was present in all the fetuses with the Meckel-Gruber syndrome. There were abnormalities of biliary excretion in all syndromic fetuses. Ultrastructural studies of the portal tract revealed abnormal collagen bundles in the Meckel-Gruber syndrome. CONCLUSIONS: Our findings, in conjunction with other reports in the literature, suggest that the ductal plate abnormality may be caused by failure of anastomosis of the intra- and extrahepatic biliary systems, perhaps in association with abnormalities of the portal tract stroma and biliary excretion.

Abnormalities, Multiple↗
PubMed2004

The significance of cerebral mantle thickness in fetal ventriculomegaly at autopsy.

AIMS: To confirm the validity of the method of diagnosing fetal ventriculomegaly at autopsy by measuring cerebral mantle thickness at the frontal lobe and to further evaluate whether taking three measurements at three separate sites is even more reliable. METHODS: The thickness of the cerebral mantle was measured at three sites: the frontal lobe, posterior-frontal lobe and occipital lobe, in 10 human fetuses which were clinically diagnosed by ultrasound to have ventriculomegaly, and in 120 control fetuses. Most fetuses were obtained during the second trimester. The mantle thicknesses were charted against foot length and crown-rump length in each case. RESULTS: Fetal cerebral mantle thickness was reduced in the three sites examined in eight of ten fetuses with a pre-autopsy diagnosis of ventriculomegaly. The mantle thickness was in the normal range in a growth-restricted fetus of 19 weeks gestational age with trisomy 21, mild ventriculomegaly, hydrops and cerebral oedema, when correlated with crown-rump and foot lengths. In a 32-week growth-retarded fetus with a prenatal ultrasound diagnosis of ventriculomegaly, cerebral mantle thickness was also within the normal range relative to crown-rump and foot lengths. CONCLUSION: Measurement at autopsy of cerebral mantle thickness is a reproducible and reliable method of confirming the diagnosis of ventriculomegaly in second trimester fetuses. Fetal cerebral mantle thickness measurement taken at the three sites must be correlated with crown-rump and foot length. In most cases where ventriculomegaly was established, the mantle thickness was reduced in fetuses in all three sites examined. The relative thickness of the cerebral mantle in different areas was often abnormal in the presence of ventriculomegaly. Our study of small numbers of cases also suggested that the method of measurement may not be reliable in some cases where there is only mild ventriculomegaly, cerebral oedema or growth retardation.

Autopsy↗
PubMed2003

Enalaprilat improves systemic and mesenteric blood flow during resuscitation from hemorrhagic shock in dogs.

We investigated the systemic and mesenteric cardiovascular effects of administering enalaprilat during resuscitation from hemorrhage. Dogs were hemorrhaged (mean arterial pressure [MAP] 40-45 mmHg for 30 min, then 30-35 mmHg for 30 min) and were then resuscitated with intermittent lactated Ringer's solution (200 mL/kg/h during first 40 min, and 60 mL/kg/h during the following 130 min, MAP 75-80 mmHg). A constant-rate infusion of saline with or without enalaprilat (0.02 mg/kg/h) was initiated after 40 min of resuscitation. Blood flows declined with hemorrhage, increased with resuscitation, and then declined during the initial 40 min of resuscitation. Enalaprilat administration resulted in blood flow increases not seen in the controls (ending values for cardiac index: 2.8 +/- 0.4 L/min/m2 vs. 1.6 +/- 0.3 L/min/m2; celiac arterial flow 314 +/- 66 L/min/m2 vs. 139 +/- 13 mL/min/m2; and portal venous flow 596 +/- 172 L/min/m2 vs. 414 +/- 81 mL/min/m2 for enalaprilat versus controls, respectively). The greater flows with enalaprilat appeared to be due to prevention of the increases in afterload noted in the controls (ending arterial elastance values 3.73 +/- 0.97 mmHg/m2/mL vs. 7.74 +/- 1.80 mmHg/m2/mL for enalaprilat versus controls, respectively). We conclude that administration of a constant-rate infusion of enalaprilat during resuscitation can be used to improve systemic and mesenteric blood flow.

Animals↗
PubMed2003

The active migration of germ cells in the embryos of mice and men is a myth.

Much is written about the independent migration of cells during normal embryonic development. However, for any putative migration, few authors give a frame of reference for the movement or a velocity; both are necessary to prove active cell migration. As it is now known that (i) sclerotomal cells do not migrate to form the axial skeleton; (ii) cranial neural crest cells do not migrate to form facial mesectoderm; and (iii) mesodermal cells do not migrate from the primitive streak, it is essential to review the evidence for the active migration of germ cells. The use of a frame of reference in a re-examination of data in the seminal paper postulating amoeboid germ-cell migration in humans indicates that there is no active migration at all and that the displacement of germ cells can be explained by the global growth movements of the embryo. Such displacements are unrelated to the artefactual movements of explanted germ cells or the appearances of dead cells. The study of human embryos forces a re-examination of evidence for the active migration of germ cells in other species, such as the mouse, where the impact of growth movements appears to have been too casually dismissed.

Animals↗
PubMed2002

Airflow-based PCO2 monitoring delivers O2 and removes CO2 from the monitored environment.

Previous investigation has suggested that the use of airflow-based gastrointestinal intraluminal PCO2 (GI PiCO2) monitoring systems may affect the local tissue microenvironment, making it not representative of the organ system as a whole. Therefore, we investigated the effects of using an airflow-based PCO2 monitoring system in a sealed environment. A 250-mL Erlenmeyer flask was filled with 10% CO2/90% N2 and was sealed with probes in place. Using a fiber-optic (Neotrend, Diametrix Medical, St. Paul, MN) system, the PCO2 and PO2 were continuously monitored with and without the airflow-based (Tonocap, Tonometrics, Datex-Ingstrom, Helsinki, Finland) system operating. PCO2 and PO2 remained constant when the airflow-based system was not in operation. PCO2 decreased 25.3 mmHg and PO2 increased 30 mmHg from a starting value of 0 mmHg when the airflow-based system was in operation for 12 h. The use of airflow-based methods for determining GI PiCO2 may influence the values obtained. Nonsample removing techniques such as fiber-optic methods for monitoring GI PiCO2 are preferable because they neither deliver O2 to nor remove CO2 from the local microenvironment.

Carbon Dioxide↗
PubMed2002

The struggle for language: perspectives and practices of urban parents with children who are deaf or hard of hearing.

Research is scarce on young children with hearing impairments growing up in urban environments. A qualitative study was used to explore and describe the perspectives and practices of these children's parents. An ethnographic approach enabled documentation of parents' routines, daily activities, thoughts (perceptions), and behaviors (practices). In-depth interviews and observations were the primary data sources. Data collection occurred within a 6-month period. Research questions focused on efforts parents make independently and with others (e.g., educational staff, family members) to facilitate and support their child's efforts to communicate and acquire language. Nine parents, two grandparents, and six staff members disclosed their perspectives and practices. While similarities and differences arose, universal perspectives and practices emerged among the parents that are discussed as prevailing themes. Results suggest that the parents' struggle, systemic barriers, and the urban environment are the greatest challenges facing families. Addressing these challenges will contribute to establishment of truly equitable and effective interventions for urban children, whether deaf or hard of hearing, their parents, and other family members.

Child↗