Release of enkephalins and enkephalin-containing polypeptides from perfused beef adrenal glands.

Enkephalins and enkephalin-containing polypeptides were released from perfused bovine adrenal glands by nicotine and Ba2+, agents that release catecholamines. All the enkephalin-containing polypeptides that are normally found in the adrenal medulla were released by the two secretagogues in approximately the same proportions as are present in adrenal chromaffin granules.     

Effects of procainamide on transmural ventricular repolarisation

To investigate the pharmacological effect of procainamide on transmural ventricular repolarisation in normal heart, the transmural activation-recovery intervals (ARI) and their responses to procainamide (20 mg/min i.v. for 20 min) were studied in 6 open-chest, pentobarbitone-anaesthetised sheep. ARI was measured from the unipolar ECGs acquired with 4 plunge needles inserted into the basal and apical parts of the left ventricular wall. During sinus rhythm (cycle length 500–700 ms), there was no significant difference in the pooled ARI between the epicardium (266.0 ± 30.5 ms), midmyocardium (265.0 ± 28.9 ms) and endocardium (265.7 ± 28.1 ms) (p > 0.05). Procainamide prolonged ARI in all myocardial layers. The pooled ARI prolongation from the epicardium, midmyocardium and endocardium of the 6 animals was 66.8 ± 18.3, 70.3 ± 14.7 and 65.3 ± 15.7 ms (p > 0.05), respectively. In conclusion, sodium channel blocker procainamide results in a similar repolarisation prolongation in the left ventricular epicardium, midmyocardium and endocardium of a healthy heart.     

Demyelination of vestibular nerve axons in unilateral Ménière's disease

We conducted a study to determine whether vestibular nerves in patients with unilateral Ménière's disease whose symptoms are refractory to medical management exhibit neuropathologic changes. We also endeavored to determine whether retrocochlear abnormalities are primary or secondary factors in the disease process. To these ends, we obtained vestibular nerve segments from five patients during retrosigmoid (posterior fossa) neurectomy, immediately fixed them, and processed them for light and electron microscopy. We found that all five segments exhibited moderate to severe demyelination with axonal sparing. Moreover, we noted that reactive astrocytes produced an extensive proliferation of fibrous processes and that the microglia assumed a phagocytic role. We conclude that the possible etiologies of demyelination include viral and/or immune-mediated factors similar to those seen in other demyelinating diseases, such as multiple sclerosis and Guillain-Barré syndrome. Our findings suggest that some forms of Ménière's disease that are refractory to traditional medical management might be the result of retrocochlear pathology that affects the neuroglial portion of the vestibular nerve.     

Animal model for evaluation of soft tissue ingrowth into various types of porous coating

Results from several studies have suggested that soft tissue ingrowth into porous coating can serve as a biologic containment mechanism to prevent particulate debris migration by sealing off the effective joint space. Therefore, a rabbit animal model was developed to investigate soft tissue ingrowth into various types of metallic rods. After implantation of several types of coated and smooth rods within the thigh musculature of rabbits, a thick encapsulation of soft tissue was observed around porous-coated rods whereas a nonadherent pseudosynovial-lined cavity was observed around smooth rods. Within 3 weeks, soft tissue had grown into the three different types of porous coating on the rods. Histologic evaluation verified that maturation of this ingrowth tissue occurred by 12 weeks. Incomplete soft tissue ingrowth occurred into the depths of large-bead (590-840 mm) porous-coated surfaces. Soft tissue separation from the bead surfaces was observed at 12 weeks in the porous-coated implants that also had been coated with a thin layer of tricalcium phosphate. These findings suggest that soft tissue ingrowth can be expected to occur into the porous coatings tested, but that tricalcium phosphate should not be used as an additional surface coating to obtain long-term adherence of circumferential soft tissue ingrowth.     

Health insurance knowledge among Medicare beneficiaries

OBJECTIVE: To assess the effect of new consumer information materials about the Medicare program on beneficiary knowledge of their health care coverage under the Medicare system. DATA SOURCE: A telephone survey of 2,107 Medicare beneficiaries in the 10-county Kansas City metropolitan statistical area. STUDY DESIGN: Beneficiaries were randomly assigned to a control group and three treatment groups each receiving a different set of Medicare informational materials. The "handbook-only" group received the Health Care Financing Administration's new Medicare & You 1999 handbook. The "bulletin" group received an abbreviated version of the handbook, and the "handbook + CAHPS" group received the Medicare & You handbook plus the Consumer Assessment of Health Plans (CAHPS) survey report comparing the quality of health care provided by Medicare HMOs. Beneficiaries interested in receiving information were oversampled. DATA COLLECTION METHODS: Data were collected during two separate telephone surveys of Medicare beneficiaries: one survey of new beneficiaries and another survey of experienced beneficiaries. The intervention materials were mailed to sample members in advance of the interviews. Knowledge for the treatment groups was measured shortly after beneficiaries received the intervention materials. PRINCIPAL FINDINGS: Respondents' knowledge was measured using a psychometrically valid and reliable 15-item measure. Beneficiaries who received the intervention materials answered significantly more questions correctly than control group members. The effect on beneficiary knowledge of providing the information was modest for all intervention groups but varied for experienced beneficiaries only, depending on the intervention they received. CONCLUSIONS: The findings suggest that all of the new materials had a positive effect on beneficiary knowledge about Medicare and the Medicare + Choice program. While the absolute gain in knowledge was modest, it was greater than increases in knowledge associated with traditional Medicare information sources.