Roberta M. Hagaman

Prospective comparison of noninvasive techniques for amputation level selection

This study prospectively compared the following tests for their accuracy in amputation level selection: transcutaneous oxygen, transcutaneous carbon dioxide, transcutaneous oxygen-to-transcutaneous carbon dioxide, foot-to-chest transcutaneous oxygen, intradermal xenon-133, ankle-brachial index, and absolute popliteal artery Doppler systolic pressure. All metabolic parameters had a high degree of statistical accuracy in predicting amputation healing whereas none of the other tests had statistical reliability. Amputation site healing was not affected by the presence of diabetes mellitus nor were the test results for any of the metabolic parameters.

Injury profiles in pedestrian motor vehicle trauma

One hundred fifteen consecutive pedestrians who were struck by motor vehicles were studied to determine the magnitude and patterns of the injuries sustained. The mortality rate was 22%, and 17 of 25 patients who died did so during the initial resuscitative efforts, primarily due to head, chest, and or abdominal injury. The average Injury Severity Score (ISS) among all patients was 20; however, it was significantly higher (46) in nonsurvivors. The majority of the victims were men (72%), and the average age of all patients was 35 years. As the patients age increased, so did the likelihood of mortality, fractures, and prolonged hospital stay. Blood alcohol levels were measured in 85 patients, 65% of whom had detectable levels (mean, 0.25 mg/dL). There was no correlation between the presence of alcohol and mortality, ISS, head injury, or number of fractures. The most frequently injured organ system was musculoskeletal (77%), followed by head (34%), abdomen (21%), and chest (15%). The most common fractures seen were tibia-fibular (39), pelvis (35), and femur (31). Hospital stay averaged 11 days, and patients charges averaged

Transcutaneous oxygen and carbon dioxide pressure monitoring to determine severity of limb ischemia and to predict surgical outcome

16,900.

Balanced reciprocal translocations: risk factors for aneuploid segregant viability

Transcutaneous oxygen and carbon dioxide pressure (PO2 and PCO2) foot monitoring was compared with ankle Doppler-derived systolic pressure regarding their respective abilities to discriminate the severity of limb ischemia before vascular reconstruction and to predict surgical outcome early in the postoperative period. Transcutaneous PO2 (tcPCO2), foot-chest tcPO2 index, transcutaneous PCO2 (tcPCO2), foot tcPO2/tcPCO2 index (tcPO2/tcPCO2), ankle Doppler systolic pressure (AP), and ankle-brachial pressure index (ABI) were determined in 89 revascularized limbs. The measurement of tcPO2 and foot-chest tcPO2 was found to be more sensitive to degrees of severity of limb ischemia and more closely associated with the outcome of revascularization than AP and ABI. TcPCO2 and tcPO2/tcPCO2 were not useful in assessment of the vascular patient undergoing reconstructive surgery. Before operation, tcPO2 less than or equal to 22 torr and foot-chest tcPO2 less than or equal to 0.46 indicate severe limb ischemia requiring urgent revascularization. After operation, tcPO2 less than or equal to 22 torr and foot-chest tcPO2 index less than or equal to 0.53 indicate that revascularization is likely to fail. We conclude that tcPO2 monitoring, as a metabolic test of actual tissue perfusion, is a more reliable indicator of preoperative limb ischemia and postoperative outcome of revascularization than hemodynamic, Doppler-derived pressure tests.

DNA ploidy, grade, and stage in prognosis of uterine cervical cancer

Reciprocal translocations were studied in two groups of balanced carrier couples: 202 had 210 translocation aneuploid liveborn (LB) infants, and 95 couples had repetitive abortions (AB) without liveborn ancuploids. The observed translocation aneuploidies in the LB group were compared to predicted potential aneuploidies in A B by frequency of chromosome involvement, meiotic segregation mode, and mean trisomic, monosomic and combined genomic imbalances. Qualitative and quantitative differences identified genomic regions and chromosomes possibly vital for in utero survivability. LB aneuploidies indicate non‐random chromosome involvement, selection of least detrimental segregants and segments, and predominant transmission from maternal balanced carriers (especially in 3:1 tertiary segregation, 93.5%). For an individual with a balanced reciprocal translocation and untested reproductive capability, an approach is given for predicting whether a translocation aneuploid conceptus will be liveborn or aborted.

Fragile sites are unrelated to reciprocal translocation breakpoints

A retrospective study of 56 cases of uterine cervical squamous carcinoma evaluated DNA content, histological grade, and clinical stage as indicators of prognosis. Minimum survivor follow-up was 24 months. Following standard radiation therapy, there were 40 cures and 16 treatment failures. DNA content was measured by flow cytometry of pretreatment biopsies removed from paraffin. There were 18 diploid cases and 38 aneuploid (67.9%). Aneuploid cases included 6 with very high G2-M peaks (greater than or equal to 15% of the cell sample). DNA ploidy correlation with prognosis was not statistically significant. However, both grading by a multiple parameter method (P less than 0.0133) and staging (P less than 0.0064) were significant prognostic factors. Higher grade and stage correlated with treatment failure.

An Asperity Model to Simulate Rupture along Heterogeneous Fault Surfaces

In 492 cases of reciprocal translocations in balanced carriers, the 984 breakpoints were studied for a possible relationship to the 45 fragile sites. Random coincidence was predicted at 14% and the observed coincidence was 14.3%, indicating that the two events are unrelated. However, chromosomes 1,11 and 14 were exceptions and did show a statistically significant relationship.

ANALYSIS OF ROCK FRAGMENTATION USING DIGITAL IMAGE PROCESSING

A model has been developed to simulate the statistical and mechanical nature of rupture on a heterogeneous strike-slip fault. The model is based on the progressive failure of circular asperities of varying sizes and strengths along a fault plane subjected to a constant far-field shear displacement rate. The basis of the model is a deformation and stress intensity factory solution for a single circular asperity under a unidirectional shear stress. The individual asperities are unified through the fault stiffness and the far-field stress and displacement. During fault deformation asperities can fail and reheal, resulting in changes in the local stresses in the asperities, stress drops, and changes in the stiffness of the fault. Depending on how the stress is redistributed following asperity failure and on the strenghts of the neighboring asperities an earthquake event can be the failure of one or more asperities. Following an earthquake event seismic source parameters such as the stress drop, energy change, and moment magnitude are calculated. Results from the model show a very realistic pattern of earthquake rupture, with reasonable source parameters, the proper magnitude-frequency behavior, and the development of characteristic earthquakes. Also the progression ofb-values in the model gives some insight into the phenomenon of ‘self-organized criticality.’