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Lanes SF, Lanza LL, Radensky PW, Yood RA, Meenan RF, Walker AM, Dreyer NA. Resource utilization and cost of care for rheumatoid arthritis and osteoarthritis in a managed care setting: the importance of drug and surgery costs. ARTHRITIS AND RHEUMATISM 1997; 40:1475-81. [PMID: 9259428 DOI: 10.1002/art.1780400816] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVE To describe the frequency and costs of medical services for patients with osteoarthritis (OA) or rheumatoid arthritis (RA) in a managed care setting. METHODS Individual utilization records of medical and pharmacy services for OA and RA patients were obtained from a group-model health maintenance organization (HMO). Estimates were made for costs of drugs and medical services for arthritis from July 1, 1993 to June 30, 1994 using Medicare reimbursement schedules and average wholesale drug prices. Calculated rates for each population were expressed as counts of events or as dollars per person-year. RESULTS The average individual cost rate of arthritis-related care for 365 RA patients was $2,162 per year, and the total cost of RA care to the HMO was $703,053. Prescription medications accounted for 62% ($436,440) of the total cost of RA care, while ambulatory care accounted for 21% ($150,938), and hospital visits accounted for 16% ($115,674). With regard to 10,101 OA patients, the average individual cost rate was $543 per year, and total cost to the HMO was $4,728,425. Hospital care accounted for 46% ($2,170,890) of the total cost of OA care, medications accounted for 32% ($1,509,637), and ambulatory care accounted for 22% ($1,047,898). CONCLUSION RA care, in the setting of this study, was characterized by intensive treatment, especially frequent use of medications that were delivered to most patients. Although the cost of RA care per patient was high, cost to the managed care provider was relatively low, owing to the rarity of RA. OA care tended to be infrequent, and the largest component of cost was hospital care for a small proportion of patients (5%). Owing to the greater prevalence of OA, care of OA was nearly 7 times more costly to the managed care provider than was care of RA.
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Choo PW, Galil K, Donahue JG, Walker AM, Spiegelman D, Platt R. Risk factors for postherpetic neuralgia. ARCHIVES OF INTERNAL MEDICINE 1997; 157:1217-24. [PMID: 9183233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND The risk factors for postherpetic neuralgia (PHN), the most common complication of herpes zoster, have not been well established. OBJECTIVE To elucidate the risk factors for PHN. METHODS Automated medical, claims, and pharmacy records of a health maintenance organization were used to identify cases of PHN and obtain data on risk factors. A case-base design was used to assess the impact of various patient, disease, and treatment factors on the prevalence of PHN 1 and 2 months after developing zoster. RESULTS There were 821 cases of herpes zoster that met all eligibility criteria. The prevalence of PHN more than 30 days after onset of zoster was 8.0% (95% confidence interval [CI], 6.3%-10.1%) and 4.5% (95% CI, 3.2%-6.2%) after 60 days. Compared with patients younger than 50 years, individuals aged 50 years or older had a 14.7-fold higher prevalence (95% CI, 6.8-32.0) 30 days and a 27.4-fold higher prevalence (95% CI, 8.8-85.4) 60 days after developing zoster. Prodromal sensory symptoms and certain conditions associated with compromised immunity were also associated with PHN. Systemic corticosteroids before zoster and treatment of zoster with acyclovir or corticosteroids did not significantly affect the prevalence of PHN. CONCLUSIONS Increased age and prodromal symptoms are associated with higher prevalence of PHN 1 and 2 months after onset of zoster. Overall, systemic acyclovir appears not to confer any protection against PHN, although benefit among elderly patients cannot be excluded.
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Walker AM, Szneke P, Bianchi LA, Field LG, Sutherland LR, Dreyer NA. 5-Aminosalicylates, sulfasalazine, steroid use, and complications in patients with ulcerative colitis. Am J Gastroenterol 1997; 92:816-20. [PMID: 9149192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVES The choice between sulfasalazine and 5-aminosalicylate (5-ASA) drugs in the management of patients with ulcerative colitis often depends on idiosyncrasies of drug tolerance and control of the disease in individual patients. We sought to evaluate whether there were population differences in the effect of 5-ASA and sulfasalazine on the occurrence of clinically recognized adverse events. We also attempted to determine whether there were differences in the use of concomitant steroids and in the rates of hospitalization. METHODS We reviewed a large computerized database drawn from general practices in the United Kingdom. There we found records of 2894 patients in whom general practitioners had diagnosed ulcerative colitis, and who were receiving ongoing medical therapy specific to ulcerative colitis. The period of data availability ran from the beginning of 1990 to the latter part of 1993. The average duration of observation was 2.1 yr per patient. Patient histories were categorized into distinct periods according to the dose of 5-ASAs and sulfasalazine, steroids, and immunosuppressants, and were further separated according to the activity of ulcerative colitis. Within these categories, we examined the initiation and discontinuation of steroids, incidence of new hospitalizations for ulcerative colitis, and clinical mention of adverse events. RESULTS New clinical mentions of hepatic, pancreatic, renal, and hematological events other than anemia were similar among the 5-ASAs and were very infrequent overall. Hospitalizations for ulcerative colitis occurred with similar frequency (about 15 hospitalizations per 100 patients per year) among users of those drugs. Patients receiving sulfasalazine had lower rates of initiation of prednisolone than did patients receiving 5-ASA, but sulfasalazine was used proportionately less often in patients who had been recently hospitalized, and it may be that sulfasalazine patients were somewhat less sick, overall, than were 5-ASA-using patients. The choice of drug did not affect discontinuation rates for prednisolone among established users. CONCLUSIONS In the United Kingdom, during the period of this study, serious adverse reactions to drugs were not an important aspect of the management of patients with ulcerative colitis. Renal and pancreatic complications of sulfasalazine and 5-ASA therapy were extremely rare. Sulfasalazine and 5-ASA drugs have similar steroid-sparing properties. Disease-specific hospitalizations are approximately 100 times more common in ulcerative colitis patients than are serious adverse drug effects. Considerations of drug efficacy should therefore dominate the choice between therapeutic agents.
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Walker AM, Funch DP, Bianchi L, Blot WJ. Shop order fracture rate as a risk factor for strut fracture in Björk-Shiley CC60 degrees heart valves. THE JOURNAL OF HEART VALVE DISEASE 1997; 6:264-7; discussion 268. [PMID: 9183725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND AND AIMS OF THE STUDY Previous studies have implicated a number of characteristics that predict strut fracture in Björk-Shiley convexo-concave heart valves, including valve size and position, opening angle, and weld date. This study examines whether the specific batch (shop order) with which a valve is associated during manufacture is related to the risk of fracture. MATERIAL AND METHODS Our case-control study of CC60 degrees valves obtained detailed information on the manufacturing characteristics of 147 case and 1094 control valves used. Shop order fracture rate for each valve (percentage of other valves in the same shop order with a fracture) was obtained from the research database maintained by the valve manufacturer. RESULTS Shop order was associated with fracture risk. Valves originating from shop orders with the highest two categories of fracture rate were at approximately twice the risk of fracture as other valves, after accounting for the effect of known risk factors. CONCLUSIONS Shop order information may provide additional data for assessing the likelihood of valve fracture in individuals being considered for prophylactic explant of heart valves.
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Walker AM, Benson LN, Wilson GJ, Arbus GS. Cardiomyopathy: a late complication of hemolytic uremic syndrome. Pediatr Nephrol 1997; 11:221-2. [PMID: 9090671 DOI: 10.1007/s004670050267] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
This report describes a child who presented with classic hemolytic uremic syndrome (HUS) and 4 months later developed a life-threatening but reversible cardiomyopathy with global cardiac dysfunction and a left ventricular ejection fraction of 14%. There was no evidence of electrolyte abnormalities, anemia, hypertension, severe fluid overload, or viral infection. Endomyocardial biopsies were consistent with a dilated cardiomyopathy. This paper highlights the importance of considering the diagnosis of associated cardiomyopathy when presenting with late-onset edema following HUS.
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Liu JW, Dawson DD, Peters CE, Baker MA, Walker AM. Estrogen replacement in ovariectomized rats results in physiologically significant levels of circulating progesterone, and co-administration of progesterone markedly reduces the circulating estrogen. Endocrine 1997; 6:125-31. [PMID: 9225126 DOI: 10.1007/bf02738955] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Estrogen and progesterone replacement in ovariectomized rats in an often-used experimental system for determination of the specific effects of these hormones. In this study, two different delivery systems and two different dosage levels of estrogen, progesterone or a combination of the two have been used. Estrogen and progesterone in the circulation have been measured in response to each treatment. It is reported that estrogen treatment (237.2 +/- 49.2 pg/mL) results in physiologically significant levels of circulating progesterone (11.1 +/- 1.3 ng/mL). Also, co-administration of progesterone (23.7 +/- 2.0 ng/mL) with estrogen decreases the level of estrogen over that seen with estrogen alone (96.7 +/- 19.2 pg/mL with progesterone vs 237.2 +/- 49.2 pg/mL without progesterone). Thus, contrary to expectations, estrogen replacement therapy is not specific to estrogen and some of the antagonistic effects of progesterone are the result of a decrease in circulating estrogen, and not a specific effect on a target tissue. Whereas the mechanism of these effects has not been determined, obvious artifactitous phenomena have been excluded as being their cause. These results could have a major impact on the interpretation of past and future experiments of this kind.
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Rothman KJ, Cann CI, Walker AM. Epidemiology and the internet. Epidemiology 1997; 8:123-5. [PMID: 9229201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Lanes SF, Birmann B, Raiford D, Walker AM. International trends in sales of inhaled fenoterol, all inhaled beta-agonists, and asthma mortality, 1970-1992. J Clin Epidemiol 1997; 50:321-8. [PMID: 9120532 DOI: 10.1016/s0895-4356(96)00375-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
To evaluate the hypothesis that fenoterol or all inhaled beta-agonists caused an epidemic of asthma mortality in New Zealand from the late 1970s to the mid-1980s, we examined trends from 1970 to 1992 in per capita sales of inhaled fenoterol, inhaled beta-agonists, and asthma mortality in New Zealand and nine other countries that marketed fenoterol. During the last two decades, there has been a large and widespread increase in sales of inhaled beta-agonists, including fenoterol. Asthma mortality in most countries, however, has been relatively stable. Only New Zealand experienced an epidemic of asthma mortality. In addition, sales rates of fenoterol similar in magnitude to those in New Zealand near the peak of the epidemic also occurred in Belgium, Austria, and Germany, while asthma mortality in these countries remained low. Also, sales rates of all beta-agonists in Australia were similar to those in New Zealand, but no epidemic of asthma mortality occurred in Australia. Therefore, the difference between asthma mortality rates in New Zealand and other countries is not explained by differences in per capita sales of fenoterol or all beta-agonists. Within New Zealand, the beginning and end of the epidemic correlated with a rise and fall in sales of all beta-agonists, including fenoterol. From 1980 to 1989, however, sales of fenoterol and all beta-agonists doubled in New Zealand while asthma mortality declined by 40%. International data on medication sales and asthma mortality, therefore, do not point to a relation between asthma mortality and beta-agonists in general nor fenoterol in particular.
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Walker AM. Quantitative studies of the risk of serious hepatic injury in persons using nonsteroidal antiinflammatory drugs. ARTHRITIS AND RHEUMATISM 1997; 40:201-8. [PMID: 9041931 DOI: 10.1002/art.1780400204] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To quantify the risk of symptomatic hepatic injury associated with nonsteroidal antiinflammatory drugs (NSAIDs). METHODS Five population-based studies were summarized to evaluate information on more than 1,000,000 patients using NSAIDs. RESULTS The risk of clinically apparent liver injury was approximately 1 case per 10,000 patient-years of NSAID use. Only sulindac, associated with a 5-10-fold higher incidence of hepatic injury, differed significantly from other NSAIDs. Patients using diclofenac showed no higher incidence of serious liver disease than did patients using other NSAIDs. CONCLUSION Symptomatic hepatic effects attributable to most NSAIDs are extremely rare and usually mild.
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Fan WQ, Smolich JJ, Wild J, Yu VY, Walker AM. Nitric oxide modulates regional blood flow differences in the fetal gastrointestinal tract. THE AMERICAN JOURNAL OF PHYSIOLOGY 1996; 271:G598-604. [PMID: 8897878 DOI: 10.1152/ajpgi.1996.271.4.g598] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We studied the role of endogenous nitric oxide (NO) in the regulation of gastrointestinal (GI) circulation in 11 chronically instrumented and unanesthetized late-gestation fetal sheep. Systemic and GI blood flows were measured by the radiolabeled microsphere technique. Mean arterial pressure (MAP), heart rate, blood flows, oxygen delivery, and vascular resistance were determined before and after infusion of the specific NO synthase inhibitor, N omega-nitro-L-arginine (L-NNA), to cumulative doses of 10 and 25 mg/kg. At both L-NNA doses, MAP increased, and combined ventricular output and heart rate decreased. GI blood flow and oxygen delivery decreased and vascular resistance increased for the stomach, all segments of the small intestine, and proximal colon and cecum but were unchanged in the middle and distal colon and rectum. Because blood flow reduction in the small intestine was pronounced (from 176 to 107 ml.min-1.100 g-1, P < 0.001) and blood flow in the large intestine was unchanged, distribution of intestinal blood flow became more uniform. Overall, blood flow reduction was proportionally greater in GI circulation than in the remainder of fetal circulation. In three additional animals we established that L-NNA reduced blood flow to the mucosal-submucosal layer (P < 0.02) but not to the muscularis serosa of the small intestine. In the same animals, L-arginine (250 mg/kg) restored systemic hemodynamics and partially restored small intestinal blood flow. Our results suggest that NO is an important differential regulator of vascular tone in the developing GI circulation.
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Lanes SF, Birmann BM, Walker AM, Sheffer AL, Rosiello RA, Lewis BE, Dreyer NA. Characterisation of asthma management in the Fallon Community Health Plan from 1988 to 1991. PHARMACOECONOMICS 1996; 10:378-385. [PMID: 10163579 DOI: 10.2165/00019053-199610040-00006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In order to characterise asthma management in a managed care setting, we identified 10,301 patients who were diagnosed with asthma between 1 January 1988 and 31 December 1991 at a group model health maintenance organisation in central Massachusetts, US. We obtained for these patients automated utilisation files containing data on medications, hospitalisations, emergency room visits, office visits, and estimated costs of these services. The medication dispensed to the greatest proportion of patients was beta 2 agonists either by inhalation (56%) or orally (21%). Theophylline was dispensed to 23% of the patients. Maintenance therapy was inhaled anti-inflammatory medication was uncommon, as inhaled corticosteroids (17%) and sodium cromoglycate (cromolyn sodium) [8%] were dispensed to fewer patients than other asthma medications. Among patients who had been hospitalised in the previous year, 36% were presently receiving inhaled corticosteroids, and among patients who used at least one beta 2 agonist metered-dose inhaler per month, 49% were presently receiving inhaled corticosteroids. Economic analyses showed that only 8% of the patients had either a hospital admission or an emergency room visit, but hospital costs among these patients accounted for 25% of the total costs of asthma care. In addition, the top 10% most expensive patients accounted for 42% of the total cost of asthma care. We conclude that a substantial proportion of patients at increased risk of a severe attack, by virtue of having a recent hospitalisation, do not receive maintenance anti-inflammatory therapy, and that hospitalisations among a relatively small proportion of asthma patients contribute significantly to the cost of asthma care.
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Andrews EA, Avorn J, Bortnichak EA, Chen R, Dai WS, Dieck GS, Edlavitch S, Freiman J, Mitchell AA, Nelson RC, Neutel CI, Stergachis A, Strom BL, Walker AM. Guidelines for Good Epidemiology Practices for Drug, Device, and Vaccine Research in the United States. Pharmacoepidemiol Drug Saf 1996; 5:333-8. [PMID: 15073820 DOI: 10.1002/(sici)1099-1557(199609)5:5<333::aid-pds244>3.0.co;2-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Lanes SF, Sulsky S, Walker AM, Isen J, Grier CE, Lewis BE, Dreyer NA. A cost density analysis of benign prostatic hyperplasia. Clin Ther 1996; 18:993-1004. [PMID: 8930437 DOI: 10.1016/s0149-2918(96)80055-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We assessed the frequency and cost of care for benign prostatic hyperplasia (BPH) among approximately 165,000 subscribers to Fallon Community Health Plan (FCHP), a group model health maintenance organization located in central Massachusetts. We computed rates of episodes of medical services for BPH using automated utilization files, and we estimated costs using Medicare reimbursement schedules and medication average wholesale prices. We identified 3919 men who visited a physician for BPH from January 1, 1991, until December 31, 1994, during which time they contributed 8336 person-years to the analysis. This population comprises approximately 12% of men at least 40 years old at FCHP. From 1991 to 1994, 696 (18%) men received terazosin, 219 (6%) men underwent a prostatectomy, and 41 (1%) men received finasteride. Men averaged 1.66 office visits per year to a physician for BPH. Most office visits (61%) were to a primary care physician, with 39% of the visits to a urologist. Among patients who received terazosin, the frequency of office visits increased slightly after receiving terazosin, from 2.14 to 2.62 visits per year. Among surgery patients, the frequency of visits declined after prostatectomy, from 6.31 visits per year to 1.67 visits. The individual annual cost rate for BPH care ranged from $25.00 to $25,352.00, with an average of $364.00 per person and a median cost of $126.00. The major components of the overall costs were hospital admissions (35%), terazosin dispensings (29%), and physician office visits (19%), with outpatient hospital care and ambulatory procedures accounting for the remaining 17%. Among men receiving terazosin, the average cost was $1190.00 per person-year, and among patients undergoing prostatectomy, the cost was $2630.00 per person-year. The prostatectomy rate declined by nearly 80% during the study period, while the dispensing rate for terazosin doubled, resulting in an overall decline in the total cost of care for BPH from 1991 to 1994.
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Boyle P, Maisonneuve P, Bueno de Mesquita B, Ghadirian P, Howe GR, Zatonski W, Baghurst P, Moerman CJ, Simard A, Miller AB, Przewoniak K, McMichael AJ, Hsieh CC, Walker AM. Cigarette smoking and pancreas cancer: a case control study of the search programme of the IARC. Int J Cancer 1996. [PMID: 8690527 DOI: 10.1002/(sici)1097-0215(19960703)67] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A multi-centre case-control study of pancreas cancer, designed to be population-based, to use a random sample of local populations as controls and to use a common protocol and core questionnaire, was conducted as the first study of the SEARCH programme of the International Agency for Research on Cancer. "Ever-smokers" were found to be at increased risk for pancreas cancer compared with "never-smokers" consistently in all strata of gender, response status and centre. Risk of pancreas cancer was found to increase with increasing lifetime consumption of cigarettes, the relative risk rising to 2.70 (95% C.I. 1.95 to 3.74) in the highest intake category. The overall trend in risk was highly significant and the association was found consistently in each stratum of gender, response status and centre. Fifteen years had to pass from quitting cigarette smoking until the risk fell to a level compatible with that in never-smokers among the heaviest group of smokers; among the 2 lowest tertiles this happened within 5 years. Further, reported smoking habits more than 15 years before diagnosis appeared to have no influence on pancreas-cancer risk, irrespective of amount smoked. The results are consistent with a causal role for cigarette smoking in the aetiology of pancreas cancer and illustrate that ceasing to smoke cigarettes can lead to reductions in the elevated risk of pancreas cancer produced by this habit.
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Kawaminami M, Okazaki K, Uchida S, Marumoto N, Takehara K, Kurusu S, Hashimoto I, Walker AM. Intrapituitary distribution and effects of annexin 5 on prolactin release. Endocrine 1996; 5:9-14. [PMID: 21153088 DOI: 10.1007/bf02738650] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/1996] [Revised: 04/04/1996] [Accepted: 04/18/1996] [Indexed: 10/22/2022]
Abstract
Annexin 5 is expressed by rat anterior pituitary cells and a depolarizing stimulus results in increased extracellular display and, depending on local calcium concentrations, potential release into the extracellular environment. In order to further investigate the role of annexin 5 in anterior pituitary function, we have examined the intracellular distribution by immunocytochemistry and the effects of annexin 5 on the release of a major secretory product, prolactin. Prolactin was chosen because we could easily monitor effects on basal release and effects on the immediate and sustained phases of thyroid stimulating hormone releasing hormone (TRH)-stimulated release. Immunocytochemical localization of annexin 5 showed staining of the majority of anterior pituitary cells. Labeling was predominantly on the nuclear envelope and plasma membrane. For the chosen secretory product, prolactin, annexin 5 was found in most, but not all prolactin positive cells. When recombinant annexin 5 (50 ng/mL) was added to a 3 h static culture incubation of rat anterior pituitary cells, prolactin release was inhibited by about 30% (p<0.05). A lower dose had a reduced effect and higher doses had no further inhibitory effect, indicating that the effect was specific to annexin 5 and not a nonspecific toxic effect of some contaminant in the preparation. This interpretation was further strengthened in a time-course experiment demonstrating that when TRH and annexin 5 were added together, there was no effect of annexin 5 on the amount of prolactin released. After a 3 h preincubation in annexin 5, however, prolactin release, in response to TRH, was suppressed by about 30% in both the acute and sustained phases. These data suggest that annexin 5 may be a local regulator of release in the anterior pituitary, but a slow onset effect on both phases of TRH-stimulated release suggests that this is not an effect at the plasma membrane such as local extracellular calcium depletion by plasma membrane-bound annexin 5.
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Walker AM, Johnson ES. Bias in case-control studies of calcium antagonists. Am J Cardiol 1996; 78:380. [PMID: 8759830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Abstract
BACKGROUND The chest wall, lungs, and pericardium limit diastolic filling of the left ventricle in the fetus, neonate, and adult. To determine the effect that these tissues have on the fetal right ventricle (RV), we studied six fetal lambs (142 days of gestation) METHODS AND RESULTS Pregnant ewes were anesthetized (ketamine and alpha-chloralose), and the fetuses were partially delivered by cesarean section. Fetuses were instrumented to record RV stroke volume, RV end-diastolic pressure (Prved), intrapericardial pressure (Pip), and pleural pressure. Prved was varied between 2 and 20 mm Hg under three conditions: initially with a closed chest and a closed pericardium (CCCP); subsequently with an open chest (chest wall and lungs retracted) and a closed pericardium (OCCP); and finally after the chest wall, lungs, and pericardium were retracted (OCOP). At equal Prved, stroke volume increased substantially when the chest wall and lungs were retracted from the heart and increased further on subsequent retraction of the pericardium (eg, at Prved of 9 mm Hg, stroke volume increased from 1.2 +/- 0.2 mL [mean +/- SEM] in the CCCP condition to 2.9 +/- 0.4 and 4.2 +/- 0.3 mL in the OCCP and OCOP conditions, respectively, P < or = .05). The limitation of stroke volume in the CCCP and OCCP conditions occurred because Pip increased in an almost one-to-one fashion as Prved increased; as a consequence, RV preload (RV end-diastolic transmural pressure, Prved minus Pip) was relatively unchanged. CONCLUSIONS The chest wall-lung combination and the pericardium each significantly constrain the fetal RV and together limit RV stroke volume.
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Boyle P, Maisonneuve P, Bueno de Mesquita B, Ghadirian P, Howe GR, Zatonski W, Baghurst P, Moerman CJ, Simard A, Miller AB, Przewoniak K, McMichael AJ, Hsieh CC, Walker AM. Cigarette smoking and pancreas cancer: a case control study of the search programme of the IARC. Int J Cancer 1996; 67:63-71. [PMID: 8690527 DOI: 10.1002/(sici)1097-0215(19960703)67:1<63::aid-ijc12>3.0.co;2-d] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A multi-centre case-control study of pancreas cancer, designed to be population-based, to use a random sample of local populations as controls and to use a common protocol and core questionnaire, was conducted as the first study of the SEARCH programme of the International Agency for Research on Cancer. "Ever-smokers" were found to be at increased risk for pancreas cancer compared with "never-smokers" consistently in all strata of gender, response status and centre. Risk of pancreas cancer was found to increase with increasing lifetime consumption of cigarettes, the relative risk rising to 2.70 (95% C.I. 1.95 to 3.74) in the highest intake category. The overall trend in risk was highly significant and the association was found consistently in each stratum of gender, response status and centre. Fifteen years had to pass from quitting cigarette smoking until the risk fell to a level compatible with that in never-smokers among the heaviest group of smokers; among the 2 lowest tertiles this happened within 5 years. Further, reported smoking habits more than 15 years before diagnosis appeared to have no influence on pancreas-cancer risk, irrespective of amount smoked. The results are consistent with a causal role for cigarette smoking in the aetiology of pancreas cancer and illustrate that ceasing to smoke cigarettes can lead to reductions in the elevated risk of pancreas cancer produced by this habit.
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Oliveria SA, Felson DT, Klein RA, Reed JI, Walker AM. Estrogen replacement therapy and the development of osteoarthritis. Epidemiology 1996; 7:415-9. [PMID: 8793369 DOI: 10.1097/00001648-199607000-00013] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Recent studies have indicated that estrogen users have a lower than expected rate of concurrent osteoarthritis. We assessed the association between estrogen replacement therapy and incident symptomatic osteoarthritis, using a nested case-control design. We identified all incident cases of hand, hip, and knee osteoarthritis in women members of the Fallon Community Health Plan, age 20-89 years, from January 1, 1990, to December 31, 1993. For each case, we selected a control woman matched by closest date of birth. We used pharmacy records to classify women as new users, past users, ongoing users (past and new users), and never-users of estrogen replacement therapy. There were 60 informative case-control pairs. After controlling for obesity and health care utilization, we found that new use of estrogen replacement therapy was a predictor of new osteoarthritis diagnosis. Past use was inversely associated with risk of osteoarthritis [adjusted odds ratio = 0.7; 95% confidence interval (CI) = 0.3-1.9]. For ongoing use of estrogen replacement therapy and osteoarthritis, the adjusted odds ratio was 1.4 (95% CI = 0.6-3.3). The associations between osteoarthritis and both new use of estrogen replacement therapy and utilization of services suggest that frequent medical care increases the likelihood of diagnosis of osteoarthritis.
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Walker AM. Confounding by indication. Epidemiology 1996; 7:335-6. [PMID: 8793355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Lorenson MY, Liu JW, Patel T, Walker AM. Intragranular prolactin phosphorylation and kallikrein cleavage are regulated by zinc and other divalent cations. Endocrine 1996; 4:249-57. [PMID: 21153281 DOI: 10.1007/bf02738691] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/1996] [Revised: 03/01/1996] [Accepted: 03/01/1996] [Indexed: 10/22/2022]
Abstract
Rat prolactin (PRL) secretory granules contain enzymes for proteolytic cleavage and serial phosphorylation, but hormone cleavage products and phosphorylated PRL are not detected until just prior to exocytosis. Similarly, although PRL is stored in granules, in part, as high-mol-wt oligomers, PRL is primarily monomeric in the circulation. PRL secretory granules contain zinc, calcium, and magnesium, which inhibit depolymerization and dissolution of granules. Divalent cations also protect cysteine free thiol residues in the carboxy-terminal region of the intragranular hormone. The present studies examined the effect of removal and replacement of divalent cations on kallikrein cleavage and phosphorylation of secretory granule PRL.Kallikrein cleavage was assessed utilizing two experimental protocols. First, granules were treated with or without 3 mM EDTA, free hormone thiols were alkylated, the PRL was cleaved by kallikrein, and the small kallikrein-cleavage peptides were assessed by reversephase HPLC. No differences in hormone cleavage owing to removal of divalent cations were observed at this concentration of EDTA. Second, divalent cations in granules were reduced/removed by 10 mM EDTA/ 3 mM o-phenanthroline (OP), followed by addition of either 5 mM zinc, magnesium, calcium, or additional EDTA. Kallikrein cleavage was then initiated. In this instance, the extent of proteolysis was analyzed by two-dimensional polyacrylamide gel electrophoresis (PAGE) of the larger remnant PRL pieces. After treatment with 10 mM EDTA/3 mM OP, results indicated that cleavage between R174 and R175 (site 1) was unaffected by added cations or additional EDTA. Recovery of site 2 cleaved PRL (L1-K185) and site 3 cleaved PRL (L1-R188) was∼40% reduced by zinc, but unaffected by calcium or magnesium. Additional EDTA resulted in increased recovery of site 2 cleaved PRL, but no change in site 3 recovery, suggesting the presence of tightly bound intragranular zinc around site 2, even after the initial EDTA/OP treatment.Phosphorylation of PRL at S177 was studied using the same protocols. Phosphorylation was increased by added EDTA, even at 3 mM, and decreased by divalent cations, with no marked specificity for zinc observed. An additional experiment studied phosphorylation without exposure to kallikrein. Comparisons between the plus and minus kallikrein experiments showed kallikrein to have no apparent preference for unmodified or phosphorylated PRL.From the kallikrein cleavage and phosphorylation studies and modeling of PRL, we suggest D181 as a likely site for intragranular zinc coordination. When C189 and C197 are present as free thiols in intragranular PRL, these may also contribute to binding. Zinc coordination in this region of the molecule apparently regulates proteolytic processing by kallikrein, as well as contributing to the stability of the hormone storage forms.
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Berger PJ, Smolich JJ, Ramsden CA, Walker AM. Effect of lung liquid volume on respiratory performance after caesarean delivery in the lamb. J Physiol 1996; 492 ( Pt 3):905-12. [PMID: 8735000 PMCID: PMC1158910 DOI: 10.1113/jphysiol.1996.sp021356] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
1. The volume of liquid in the lungs of the fetal lamb is reported to fall in the final days of gestation and during labour itself. We aimed to test the hypothesis that this fall in liquid volume adapts the lungs for air breathing and pulmonary gas exchange. 2. In twelve chronically catheterized fetal lambs we measured lung liquid volume at 140 days gestation (term is 147 days) and then delivered the fetuses by Caesarean section under maternal spinal anaesthesia. In five fetuses we removed approximately half the liquid contained in the lungs just before delivery (experimental group) while the remaining seven fetuses were delivered without change to their lung liquid (control group). 3. Lambs born with reduced lung liquid volume improved their arterial blood gas and acid-base status more quickly than lambs born without alteration to lung liquid. 4. Carotid arterial blood gas values in the first 60 min of postnatal life were significantly related to the volume of liquid present in the lungs at birth, with higher arterial partial pressure of oxygen (Pa,02) and arterial oxygen saturation (Sa,02) and lower arterial partial pressure of carbon dioxide (Pa,CO2) levels being associated with lower lung liquid volumes. 5. We conclude that postnatal gas exchange is enhanced by a reduction in the volume of liquid remaining in the lungs when breathing starts.
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Hayashi K, Walker AM. Japanese and American reports of randomized trials: differences in the reporting of adverse effects. CONTROLLED CLINICAL TRIALS 1996; 17:99-110. [PMID: 8860062 DOI: 10.1016/s0197-2456(96)80001-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We sought to identify differences in the description of adverse drug experiences in reports of randomized clinical trials (RCTs) from the United States and Japan, using diclofenac and simvastatin as test drugs. Reports were identified in Medline (Index Medicus 1966-1990), EMBASE (Excerpta Medica 1974-1990), JAPICDOC (1979-1990), and JOIS-III (JMEDICINE 1980-1990). In each search keywords describing study design were paired with the drugs' generic names, chemical names, and development numbers. Twenty-seven U.S. reports (18 for diclofenac and 9 for simvastatin) and 22 Japanese reports (17 for diclofenac and 5 for simvastatin) identified in these four databases were selected for review. For each paper we identified the relation of the article to the data (preliminary, primary, and secondary reports, reviews), the means of identifying adverse reactions, the principal outcomes of the trials, and a variety of descriptive measures relating to study design, authorship, and elements of presentation. With few exceptions, Japanese reports were not indexed in English-language databases, and studies from the United States were not carried out in the Japanese databases. The Japanese literature consisted exclusively of primary reports of clinical trials, whereas the U.S. literature was dominated by review articles and secondary reports of data from trials not fully published elsewhere. Japanese reports contained more detail on adverse experiences but reported principally those attributed to the drugs by attending clinicians. U.S. reports by contrast offered little detail but tended to include all adverse experiences, whether or not clinically attributed to drugs. A preponderance of U.S. articles reported significant differences between drugs in safety or treatment efficacy, whereas only one third of the Japanese articles did so for the same agents. Reports from both countries offered few details of the methods used to gather information on adverse drug experiences, and as a result the reported absolute frequencies of such events are difficult to compare between trials or to generalize to other settings. In conclusion, the reporting of adverse reactions in clinical trials is inadequate in both the United States and Japanese literature. The shortcomings are complementary in that reports of U.S. trials contain insufficient detail and Japanese reports do not interpret or synthesize experience. Clinical research into drug safety in both countries could be improved through the adoption of simple standards of clarity and consistency in the monitoring and reporting of drug adverse effects.
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