Change in patient doses from radiological examinations at the Vancouver General Hospital, 1991-2002.

OBJECTIVE: Much concern has been expressed over the radiation doses and potential harm from x-ray examinations. However, there have been few longitudinal studies in North America. A survey of doses from radiological examinations in Canada was last carried out in 1995. This study was undertaken to estimate the change in the number of patient examinations and patient dose since this last Canadian survey. METHODS: The number of radiological examinations and numbers of patients for the years 1991 to 2002 were obtained from workload statistics, which are reported to the Canadian government each year. Radiological examinations were of the following type: general, gastrointestinal or genitourinary, angiography, and computed tomography (CT). Average doses were calculated for each group of examinations. RESULTS: From 1991 to 2002 there was an increase of 28% in the total number of x-ray examinations performed. The proportion of most types of examination has stayed fairly constant, except for CT, which has increased fourfold in the last 8 years. The striking change is the increased contribution to patient effective dose from CT since 1996, these examinations now comprising nearly 60% of the total patient dose. The average annual effective dose per patient has nearly doubled-from 3.3 mSv in 1991 to 6.0 mSv in 2002. CONCLUSION: This paper provides a simple method for any Canadian hospital to estimate the radiation dose to its patients. At the Vancouver General Hospital (VGH), the number of patient examinations has increased by 28%, but the average annual patient effective dose has almost doubled. CT is now by far the largest contributor to patient dose in diagnostic radiology. Efforts need to be made to reduce patient dose by such methods as reduction in unnecessary exams, substitution of nonionizing techniques where possible, and optimization of dose.     

Inhibition of antagonist and agonist binding to the human brain muscarinic receptor by arachidonic acid

Arachidonic acid (AA) inhibits the binding of [³H]quinclidinyl benzilate ([³H]QNB) to the human brain muscarinic cholinergic receptor (mAChR). AA inhibits at lower concentrations in the absence of glutathione (I₅₀=15 µM) than in the presence of glutathione (I₅₀=42 µM). Inhibition of mAChR binding shows specificity for AA and is reduced with loss of one or more double bonds or with either a decrease or increase in the length of the fatty acid chain. Metabolism of AA by the lipoxygenase, epoxygenase, or fatty acid cyclooxygenase pathways is not required for the inhibitory activity of AA on mAChR binding. Inhibition of [³H]QNB binding by AA is reversible. While decreasing B_max, AA increased the apparent K_D for [³H]QNB and for the more polar antagonist [³H]NMS. In addition, AA inhibits binding of the agonist [³H]oxotremorine-M (I₅₀=60 µM) and is the first mediator of mAChR action to be shown to reversibly inhibit mAChR binding. The feedback inhibition of the mAChR by AA may serve a homeostatic function similar to the reuptake and hydrolysis of acetylcholine following cholinergic nerve transmission.     

A neurosciences internship and graduate nurse role conception

Registered nurse (RN) turnover is a severe problem many hospitals face in today's health care climate. A study was conducted of a graduate nurse (GN) neurosciences internship established in a large metropolitan teaching hospital located in southwestern Tennessee to determine the internship's effect upon role conception of GNs. Thirty-two GNs enrolled in the internship comprised the experimental group, and 22 GNs in traditional orientation were the control group. Data collection instruments consisted of Corwin's Role Conception tool and a demographic questionnaire designed to examine variables that could influence professional role conception. Both instruments were completed at the beginning of employment, and Corwin's Role Conception repeated after completion of the first six months of practice. At this time audiotaped interviews were conducted by a nurse counselor to collect qualitative data from ten randomly selected informants from each group. Results revealed no significant differences in the two groups regarding changes in role conception as measured by Corwin's instrument. Audiotaped interviews brought to light many concerns of new GNs with regard to inadequate staffing, the charge nurse role, coping with the stress of the professional nurse role and new attitudes toward the field of the neurosciences. Implications for nurse administrators include the need to: be aware of the stresses to which new GNs are exposed; examine traditional practices such as the charge nurse role and staffing patterns; determine whether nursing internships, such as the neurosciences internship can improve the attitudes of GNs toward their specialty.     

Gerota versus Zuckerkandl: the renal fascia revisited

In the medical literature, Gerota fascia is frequently used as a general term to describe both the anterior and posterior pararenal fascia. However, Zuckerkandl's name is also often used to describe either the anterior or posterior fascia. To resolve this confusion, the authors reviewed the original works by Gerota and Zuckerkandl. In 1883, Zuckerkandl described the posterior renal fascia but did not recognize the presence of the anterior renal fascia. In 1895, Gerota documented the presence of the anterior renal fascia and clearly assigned Zuckerkandl's name to the posterior renal fascia. Thus, the terms Zuckerkandl fascia and posterior renal fascia are synonymous, as are Gerota fascia and anterior renal fascia.     

The thermomechanical properties of gutta-percha. Part V. Volume changes in bulk gutta-percha as a function of temperature and its relationship to molecular phase transformation

A variety of gutta-percha materials was subjected to dilatometric analysis to measure volume changes which take place with heating and cooling. The volume changes were found to be related directly to the molecular transformation kinetics of the polymer material and to the temperature ranges within which they take place. If the gutta-percha in the apical segment is not elevated above 45 degrees C, molecular transformation is avoided and the ultimate volume changes which accompany temperature cycling are small, predictable, and controllable.     

Ictal Cortical Blindness with Permanent Visual Loss

Cortical blindness is rarely an ictal manifestation. We report the case of a man who developed transient cortical blindness followed by permanent visual deficits during repeated partial seizures. Intermittent visual impairment began at age 14 years. After he had the first generalized seizure at age 28 years, neurologic, ophthalmologic, angiographic, and brain computed tomographic (CT) examinations were normal. Several EEGs showed almost continuous biposterior spike-waves. Over the next several years, frequent partial seizures were associated with transient visual loss and left body twitching or paresthesias. When he was 32, transient blindness occurred during several days of repeated occipital seizures. Permanent left homonymous hemianopia, right homonymous central scotoma, dyschromatopsia, and altered stereopsis followed these seizures. Brain CT demonstrated a new right occipital lesion. Partial seizures arising posteriorly may cause transient cortical blindness and result in permanent visual deficits.