Involvement of cyclic nucleotide-dependent protein kinases in cyclic AMP-mediated vasorelaxation

1. The involvement of cyclic AMP-dependent protein kinase (PKA) and cyclic GMP-dependent protein kinase (PKG) in the effects of cyclic AMP-elevating agents on vascular smooth muscle relaxation, cyclic nucleotide dependent-protein kinase activities and ATP-induced calcium signalling ([Ca²⁺]_i) was studied in rat aorta. Cyclic AMP-elevating agents used were a β-adrenoceptor agonist (isoprenaline), a phosphodiesterase 3 (PDE3) inhibitor (SK&F 94120) and a PDE4 inhibitor (rolipram).
2. In rat intact aorta, the relaxant effect induced by isoprenaline (0.01–0.3 μM) was decreased by a specific inhibitor of PKA, H-89, whereas a specific inhibitor of PKG, Rp-8-Br-cyclic GMPS, was without effect. No significant difference in PKA and PKG activity ratios was detected in aortic rings when isoprenaline 10 μM was used. At the same concentration, isoprenaline did not modify ATP-induced changes in [Ca²⁺]_i in smooth muscle cells. Neither H-89 nor Rp-8-Br-cyclic GMPS modified this response. These findings suggest that PKA is only involved in the relaxant effect induced by low concentrations of isoprenaline (0.01–0.3 μM), whereas for higher concentrations, other mechanisms independent of PKA and PKG are involved.
3. The relaxant effects induced by SK&F 94120 and rolipram were inhibited by Rp-8-Br-cyclic GMPS with no significant effect of H-89. Neither SK&F 94120, nor rolipram at 30 μM significantly modified the activity ratios of PKA and PKG. Rolipram inhibited the ATP-induced transient increase in [Ca²⁺]_i. This decrease was abolished by Rp-8-Br-cyclic GMPS whereas H-89 had no significant effect. These results suggest that PKG is involved in the vascular effects induced by the inhibitors of PDE3 and PDE4. Moreover, since it was previously shown that PDE3 and PDE4 inhibitors only increased cyclic AMP levels with no change in cyclic GMP level, these data also suggest a cross-activation of PKG by cyclic AMP in rat aorta.
4. The combination of 5 μM SK&F 94120 with rolipram markedly potentiated the relaxant effect of rolipram. This relaxation was decreased by H-89 and not significantly modified by Rp-8-Br-cyclic GMPS. Moreover, the association of the two PDE inhibitors significantly increased the activity ratio of PKA without changing the PKG ratio. The present findings show that PKA rather than PKG is involved in this type of vasorelaxation. The differences in the participation of PKA vs PKG observed when inhibitors of PDE3 and PDE4 were used alone or together could be due to differences in the degree of accumulation of cyclic AMP, resulting in the activation of PKA or PKG which are differently localized in the cell.
5. These findings support a role for both PKA and PKG in cyclic AMP-mediated relaxation in rat aorta. Their involvement depends on the cellular pathway used to increase the cyclic AMP level.

     

Four-contrast defecography: Pelvic “floor-oscopy”

PURPOSE: This study was designed to determine the accuracy of physical examination (as judged by four-contrast defecography) for women with pelvic floor relaxation disorders. METHODS: Sixty-two women (mean age, 59 years) who had obstructed defecation or constipation, vaginal prolapse, urinary difficulty, or pelvic pain underwent four-contrast defecography. Oral, vaginal, bladder, and rectal contrast were administered selectively and fluoroscopy was performed. Radiographic findings were compared with physical examination diagnosis. RESULTS: Four-contrast defecography changed the diagnosis in 46 patients (75 percent); 26 percent of presumed cystoceles, 36 percent of enteroceles, and 25 percent of rectoceles were not present on defecography. Defecography also revealed unsuspected coexisting defects in addition to known abnormalities detected on physical examination. In contrast, when physical examination was negative for these defects, 63 percent of patients were found to have cystoceles, 46 percent to have enteroceles, and 73 percent to have rectoceles on four-contrast defecography. The discovery of Grade 2 or 3 unsuspected abnormalities was significant, especially so for enteroceles. For posterior vaginal eversions extending to or past the introitus, physical examination was accurate in only 61 percent. Physical examination of large anterior defects was more accurate, with 74 percent of patients being correctly diagnosed. CONCLUSIONS: Physical examination diagnosis of pelvic floor relaxation disorders is frequently inaccurate, especially for large vaginal eversions. Four-contrast defecography improves diagnostic accuracy, helps to identify all pelvic floor defects before surgery, and can assist with planning the correct operative approach.     

Internal derangements of the shoulder: decision tree and cost-effectiveness analysis of conventional arthrography, conventional MRI, and MR arthrography

Purpose. In a patient with internal derangement of the shoulder, the diagnostic method of choice is controversial. Conventional arthrography can diagnose most rotator cuff tears accurately; however, in many institutions MR arthrography is usually necessary to diagnose labral tears. We utilized decision tree methodology to compare the cost- effectiveness of conventional arthrography and conventional MRI with a hypothetical algorithm in which a patient underwent arthrography, performed with admixed gadolinium, which if negative, was followed by MRI. Design. The use of double-contrast arthrography alone, conventional MRI alone, and gadolinium-enhanced MRI used as an adjunct to conventional arthrography were modeled for the diagnosis of full-thickness rotator cuff tears (RCT), partial RCTs, labral tears, and the absence of cuff/labral tears using decision analysis methodology. English language medical publications were searched to determine the base probabilities for the accuracy of the diagnostic tests. The outcome utilities ranged from –1 to +1 to reflect the value of correct diagnostic evaluation. Charges for diagnostic tests and appropriate surgical treatments were based on 1997 Medicare reimbursement rates for professional fees and hospital charges in an outpatient setting. Sensitivity analyses were performed to evaluate the effects of uncertainty regarding the prevalence of each disease state and the accuracy of several diagnostic tests. Results. In the base-case analysis, the average effectiveness of double-contrast arthrography alone, MRI alone and arthrography selectively followed by MRI were 0.6610, 0.6715, and 0.7204, respectively. The average costs for each of these strategies were $1090, $2033, and $2339, respectively. Conclusion. Arthrography performed with admixed diluted gadolinium, which if negative is immediately followed by MRI, was somewhat more expensive than conventional MRI. However, because of much greater effectiveness, cost-effectiveness was significantly higher for our proposed algorithm. Conventional arthrography without gadolinium, although less expensive, had severely limited effectiveness. Received: 4 June 1999 Revision requested: 6 August 1999 Revision received: 30 August 1999 Accepted: 1 September 1999     

Informal caregiving for frail older people at home and in long-term care institutions: who are the key supporters?

This paper describes the extent of the informal caregiving unit for older people who are physically or mentally frail living in private households or resident in long-term care institutions using cross-sectional analysis of survey data. A total of 1444 people aged 65 years or more registered with a general practitioner (GP) in four areas in England and, consenting to the study, were screened for mental or physical frailty. Of 1127 older subjects living at home 7% reported receiving no informal support, 15% had a paid supporter only and 78% nominated a key informal supporter who helped with defined activities of daily living of whom 650 (74%) were interviewed. Only 13% nominated more than one informal supporter. Key supporters were spouses (38%), daughters (30%), sons (9%), daughters-in-law (4%), other relatives (11%) and friends and neighbours (8%). Of 317 frail older people resident in long-term care institutions 175 (55%) received a main visitor at least once a week of whom 132 (75%) were interviewed. Main visitors were spouses (11%), daughters (36%), sons (23%), daughters-in-law (2%), other relatives (24%) and friends (4%). Qureshi & Walker's (1989) hierarchical, decision-making model for selecting informal caregivers was applied to the data and correctly identified 85% of key informal supporters and 79% of main visitors interviewed. This large-scale comprehensive survey of informal care for frail older people supports earlier small-scale localized studies highlighting the key role of spouses and daughters in the provision of informal support. Families of frail older people provide the support to maintain people at home.     

Risk Factors for Bladder Tumors in Spinal Cord Injury Patients

Purpose

We evaluated risk factors for the development of bladder tumors in spinal cord injury patients.

Materials and Methods

A retrospective review was done of all bladder tumors at 1 institution with matched controls for 7 years.

Results

We identified 17 malignant and 2 benign tumors. Indwelling bladder catheters and a history of bladder stones were statistically significant risk factors. Four patients with negative biopsies underwent repeat biopsy due to suspicious cytology and cancer was found.

Conclusions

An indwelling urinary catheter and a history of bladder stones are statistically significant risk factors. Cytology and biopsy are complementary in the evaluation of urothelial malignancy in this population. A high index of suspicion and thorough evaluation are needed in spinal cord injury patients.     

Diffusion of information about genetic risk within families

Recent developments in genetics are likely to exacerbate the ethical issues in clinical practice, especially with regard to privacy and disclosure of genetic information. To evaluate the behaviour of patients with respect to transmitting carrier information, we undertook a survey of 283 families with a balanced chromosomal rearrangement as a model. In these families, 1816 relatives were considered at risk and 806 of them were karyotyped (44.4%). The percentage of karyotypes performed is significantly related to the number of living children of the index couple, the reason for referral, the nature of the anomaly, the training of the counsellor and the age of the index case. This study shows the limits of the screening of at risk individuals within families, based on the willingness of the patients, and addresses practical and ethical issues around family disclosure in medical genetics.     

A randomized trial comparing 35Gy in ten fractions with 60Gy in 30 fractions of cerebral irradiation for glioblastoma multiforme and older patients with anaplastic astrocytoma.

A randomized prospective clinical trial was conducted to compare conventional high dose radiotherapy with hypofractionated, short course radiotherapy in poor prognosis patients with high grade glioma. The primary endpoint was overall survival.