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13, 2000 |
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Environmental and Inherited
Factors in the Development of Cancer
Which is more important in the development of cancer -- nature or nurture,
genes or environment? A study of almost 90,000 identical and nonidentical
twins found that genetic factors have a minor role in causing cancer of
the prostate, colon and rectum, and breast, but the environment is the major
contributor to cancer at all 28 anatomical sites studied. |
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Transplantation
of Autologous Limbal Epithelial Cells for Unilateral Corneal Disease
Corneal opacities may be treated by transplantation of autologous corneal
grafts, but sizable amounts of normal corneal tissue may be needed. In this
study of six patients with unilateral corneal disease, autografts were prepared
by culturing a small piece of normal corneal tissue from the contralateral
eye on amniotic membrane, during which the cells grew to form a sheet. These
sheets were then used to replace the damaged corneas. There was reepithelialization
in all six eyes, and vision improved substantially in five eyes. |
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Clinical
Criteria to Rule Out Cervical-Spine Injury
Clinicians order approximately 800,000 cervical-spine radiographs per year,
and the majority of the findings are normal. This study prospectively validated
the use of a set of clinical criteria in more than 34,000 patients who underwent
radiography after blunt trauma. The simple decision instrument, which consisted
of five clinical criteria, had a sensitivity of 99.0 percent; it identified
810 of 818 patients with cervical-spine injuries as requiring imaging. The
specificity of the decision instrument was 12.9 percent; it identified 4309
patients in whom cervical-spine radiography could safely have been avoided.
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Computed Tomography after
Minor Head Injury
This study evaluated 520 consecutive patients with minor head injury to
identify clinical findings that would predict the presence of any abnormality
on computed tomography (CT). All 36 patients with abnormal CT scans (6.9
percent) had at least one of the following findings: an age over 60 years,
headache, vomiting, drug or alcohol intoxication, deficits in short-term
memory, physical evidence of trauma above the clavicles, and seizure. In
a separate group of 909 patients, the presence of at least one of these
findings identified all 57 patients with abnormal CT scans (6.3 percent). |
