Transtympanic facial nerve paralysis

In order to ascertain the immediate histopathological changes of rat brain following experimental surgical injury, fragments of left parietal cortex were obtained through craniotomy and fixed by immersion. Next, the animals were killed by perfusion with the same fixative used for the respective biopsy. Five groups of rats were tested, each for one different fixative. Dark neurons were by far the most prominent feature in surgically traumatized tissue, following both immersion and perfusion with all five fluids. They were morphologically identical at both sites, and fixatives with widely different chemical composition, e.g. Bouin's fluid and buffered glutaraldehyde, had no influence on their aspect. It is suggested that shrunken neurons are not to be interpreted systematically as artefacts, but also represent a form of short-latency cellular reaction to injury.     

Placental diffusing capacities at varied carbon monoxide tensions

To test the hypothesis that carbon monoxide transfer across the placenta is, in part, a facilitated process, we have looked for evidence of saturation kinetics for carbon monoxide. In eight pregnant ewes, fetal to maternal carbon monoxide transfer was examined in a preparation in which the fetal side of the placenta was perfused with blood. The carboxyhemoglobin concentrations on the fetal side of the placenta were varied from 4.8 to 70% in 23 measurements. At increased carbon monoxide tensions, the transfer from fetus to mother always decreased. The slope of log rate of carbon monoxide transfer vs. log partial pressure gradient across the placenta was significantly different from 1. Placental membrane diffusing capacity was calculated separately from total placental diffusing capacity which includes hemoglobin reaction rates and erythrocyte membrane diffusion. Placental membrane diffusing capacity decreased at increased carbon monoxide tensions. Placental permeability for urea did not change with increasing carbon monoxide tensions. These results are consistent with the hypothesis that carbon monoxide diffusion in the placenta is, in part, carrier mediated.     

Amyloid in polypeptide hormone-producing tumors

The hormone content of 72 endocrine tumors was determined by immunofluorescence and their amyloid content was investigated. Seventeen of the 72 tumors contained amyloid. Amyloid was frequently found in tumors producing calcitonin, insulin, or growth hormone, but was rarely found in other tumors. Thus, there is a relationship between the occurrence of amyloid in an endocrine tumor and the type of hormone it produces. The reason for this is not known, but there is evidence that the amyloid fibrils contain proteins related to the hormone produced by the tumors.     

Detecting complications of direct arterial surgery: the role of intraoperative arteriography

Intraoperative arteriography was carried out using a specially constructed operating table and long x-ray film changer that permitted rapid serial exposure of the arterial reconstruction and the distal arteries. During a ten-year period, this method was applied in 1,810 arterial reconstructions, with technical problems being detected in 82 (4.6%) of these patients. The incidence of problems was highest in patients undergoing endarterectomy, where 16.7% of the patients were found to have either residual debris in the cleared segment or areas of stenosis. When bypass grafts were used, technical problems were found in 2.2% of patients and included embolism or thrombosis, graft torsion in vein grafts, stenosis of the distal anastomosis, and the creation of an intimal flap. In the entire series, five patients needed reoperation in the early postoperative period. In three of these, the operative arteriograms had been initially misread.     

Reversal of pretreatment hypotension and control of hemorrhage in trauma patients by a simple device

The injection of a suspension of Walker 256 carcinoma cells into the carotid artery of rats produced a model of hematogenously spread cerebral metastases. Most animals died from massive extracerebral tumors of the head and jaw; brain tumors were present in only one-quarter. External carotid artery ligation prior to tumor inoculation did not increase the incidence of fatal brain tumor. When cyclophosphamide, 15 mg/kg, was injected as a single dose on the fourteenth day after tumor inoculation, most of the extracerebral tumor disappeared. Fifty percent of the animals so treated were cured of tumor, but 90% of the remainder died of large intracerebral tumors. Severe cytopathic changes resulting from cyclophosphamide were present in extracerebral or choroid plexus tumors but were mild or nonexistent in intracerebral tumors. These selective effects of cyclophosphamide suggest that water-soluble agents are less effective against tumor in the brain than against extracerebral tumors despite the fact that metastatic tumor breaks down the blood-brain barrier.     

Optimal selection and preparation of fresh frozen corticocancellous allografts for cervical interbody spinal fusion

STUDY DESIGN: Iliac crest corticocancellous allografts for anterior interbody fusion were harvested from six cadavers. The grafts were cut sequentially from left and right crests and randomly assigned to tricortical or bicortical preparations. Their compression strengths then were determined and compared by matched pair analysis. OBJECTIVES: To quantify the failure strength of the grafts from different iliac locations and determine the optimal type of preparation of the grafts for anterior interbody fusion. SUMMARY OF BACKGROUND DATA: Iliac crest corticocancellous autografts and allografts commonly are used for interbody cervical fusions. However, graft strengths for specific sites have not been determined fully. METHODS: Six paired, fresh frozen, iliac crests were sectioned using a customized miter box into multiple 1-cm-thick grafts 1.5 cm in depth to simulate cervical interbody grafts. The left and right sides of each pair were randomly assigned to tricortical and bicortical preparations. The samples were tested by applying a compressive load to failure using a specialized fixture to simulate vertebral body loading. RESULTS: The grafts closer to the anterosuperior iliac spine had significantly higher failure loads and failure strengths than those closer to the posterosuperior iliac spine. The strengths of the bicortical grafts were 72 +/- 14% of the strengths of the tricortical grafts (P < 0.001). CONCLUSIONS: Anterior iliac crest grafts were stronger in compression, even after removal of one cortical surface, than posterior iliac crest grafts.     

A transgenic mouse model for mammary carcinogenesis

Missense mutations in the p53 tumor suppressor occur frequently in human breast cancer and influence both the prognosis and response to chemotherapy. Amino acid 175 (equivalent to murine 172) is the second most common site of missense mutations in p53 in human breast cancer. Over 95% of these mutations are arginine-to-histidine (R-H) substitutions resulting in a gain-of-function, and not merely a dominant-negative phenotype. Transgenic mice expressing a p53 172(R-H) construct targeted to the mammary gland by means of a whey acidic protein (WAP) promoter were characterized as a model system in order to determine the specific effects of this mutation on mammary tumorigenesis. Although transgene expression alone had no apparent effect on normal mammary development, transgenic mice treated with the chemical carcinogen dimethylbenz(a)anthracene developed tumors with much shorter latency than did control littermates and had a greater tumor burden. Tumors arising in transgenic mice did not exhibit either decreased apoptosis or increased cell proliferation relative to tumors arising in nontransgenic littermates, but did display increased genomic instability. Large pleiomorphic nuclei were visible in many tumors from transgenic mice, and DNA flow analysis confirmed the presence of significant aneuploid cell populations. Since these transgenic mice develop very few spontaneous tumors, while accelerating carcinogen-and oncogene-mediated tumorigenesis, this mouse model will, therefore, be useful in the investigation of early events in mammary tumorigenesis. It may also be used as a preclinical model to test newly developed chemotherapeutic strategies.