Parathyroid hormone-receptor interactions.

Identification of sites within the antagonist peptide of parathyroid hormone (PTH) that are "tolerant" of a wide range of amino acid substitutions has led to the design of new PTH antagonists. These antagonists have increased potency because of substitution, at appropriate sites, of amino acids that increase the interaction of the ligand with its receptor but do not cause signal transduction. Similar modifications in the parathyroid hormone-related protein (PTHrP) antagonist led to antagonists with increased potency. Further, the partial agonism of this analog could be removed by exchange of residues between PTH and PTHrP.     

Frozen red blood cells in combat casualty care: clinical and logistical considerations

OBJECTIVE: To test the hypothesis that a supply of frozen red blood cells and a system for processing pyrogen-free crystalloid solution would meet the needs of an echelon 3 medical treatment facility in the U.S. military, caring for casualties during the initial phase of a military medical operation. DATA SOURCES: Blood requirements for potential combat casualties were estimated from transfusion data on: (1) patients admitted to Boston City Hospital following trauma, utilizing a computerized data base, (2) patients admitted to the Naval Support Hospital-Da Nang during the Vietnam War, from 1966 to 1970, from published and unpublished material, and (3) casualties estimated by Department of Defense expert panels for specific conflicts. The procedure for processing frozen red blood cells was evaluated at the Naval Blood Research Laboratory. Estimates of wounded in action were provided by the Department of Defense. DATA SYNTHESIS: Computer modeling using standard spreadsheet software on a personal computer. CONCLUSIONS: Under military conditions, a frozen red blood cell bank and a system for processing pyrogen-free resuscitative fluid could be used to prepare 96 units of red cells and 960 1 of crystalloid solution per day. This would be adequate to treat approximately 180 casualties, the number projected for a 5-day battle with heavy casualties (6 wounded in action/1,000 soldiers/day). It was concluded that a frozen blood bank system and system for processing pyrogen-free resuscitative fluid could successfully meet the needs of an echelon 3 medical facility in the initial phase of a military medical operation.     

Specificity of urinary excretion of cross-linked N-telopeptides of type I collagen as a marker of bone turnover

Urinary excretion of cross-linked N-telopeptide of type I collagen (NTX) has been reported to be a specific indicator of bone resorption. We studied the utility of a new immunoassay for NTX as an indicator of changes in bone resorption caused by treatment with pamidronate (APD) followed by T₃. Twenty-two male subjects received either placebo (Group 1) or APD on study days 1–2 (Group 2). One week later all subjects received T₃ 100 g/day (days 8–15). Urinary NTX, pyridinoline (PYD), hydroxyproline (HYP), and creatinine (cr) were measured on 2-hour fasting urine samples at baseline (day 1), after APD/placebo (day 8), after T₃ (day 16), and at days 30 and 58. NTX/cr excretion fell 85% after treatment with APD (P<0.001 versus baseline), but not after placebo. The fall in mean urinary NTX after receiving APD was greater than the fall in PYD (25%) or HYP (31%) (P<0.001 NTX versus PYD and HYP). After treatment with APD, NTX excretion remained suppressed below baseline until day 58, whereas PYD and HYP excretion returned to baseline by study day 16. Persistence of APD's effect on bone until day 58 was suggested by the fact that serum calcium and parathyroid hormone levels had not returned to baseline by day 58. On day 16, after all subjects were treated with T₃, urinary NTX/cr rose significantly (P<0.01) in Group 1 (-bisphosphonate) but not in Group 2 (+bisphosphonate). We conclude that urinary NTX is responsive to acute thyroid hormone-induced increases and bisphosphonate-induced decreases in bone resorption, and may reflect these changes more accurately than PYD or HYP.Portions of the data presented here were presented at the Fifteenth Annual Meeting of the American Society for Bone and Mineral Research, Tampa, Florida, September 18–22, 1993.     

Educational and geographic career pathways of rural vs. urban hospital administrators

Information on academic and geographic career patterns was obtained through a survey of 93 urban and rural hospital administrators in the State of Washington in 1990 (90 percent response rate). A greater proportion of urban than rural administrators had advanced degrees (93 versus 74 percent). While the most common career pathways were "always urban" (39 percent) and "always rural" (20 percent), there was little support for the presumption that hospital administrators use rural positions as stepping stones into urban careers.     

Rural Health Research: Rural and Urban Physicians: Does the Content of Their Medicare Practices Differ?

Rural and urban areas have significant differences in the availability of medical technology, medical practice structures and patient populations. This study uses 1994 Medicare claims data to examine whether these differences are associated with variation in the content of practice between physicians practicing in rural and urban areas. This study compared the number of patients, outpatient visits, and inpatient visits per physician in the different specialties, diagnosis clusters, patient age and sex, and procedure frequency and type for board-certified rural and urban physicians in 12 ambulatory medical specialties. Overall, 14.4 percent of physicians in the 12 specialties practiced exclusively in rural Washington, with great variation by specialty. Rural physicians were older and less likely to be female than urban physicians. Rural physicians saw larger numbers of elderly patients and had higher volumes of outpatient visits than their urban counterparts. For all specialty groups except general surgeons and obstetrician-gynecologists, the diagnostic scope of practice was specialty-specific and similar for rural and urban physicians. Rural general surgeons had more visits for gastrointestinal disorders, while rural obstetrician-gynecologists had more visits out of their specialty domain (e.g., hypertension, diabetes) than their urban counterparts. The scope of procedures for rural and urban physicians in most specialties showed more similarities than differences. While the fund of knowledge and outpatient procedural training needed by most rural and urban practitioners to care for the elderly is similar, rural general surgeons and obstetrician-gynecologists need training outside their traditional specialty areas to optimally care for their patients.     

Incidence of presumed cytomegalovirus retinitis in HIV-infected pediatric patients.

INTRODUCTION: Large population studies of adult patients suggest an incidence of cytomegalovirus (CMV) retinitis as high as 19% to 20% as a late complication of adult HIV infection. We conducted this prospective study of a large cohort of HIV-infected children to determine the incidence of CMV retinitis in HIV-infected children. METHODS: From January 1984 to August 1997, 173 HIV-infected children were followed up for an average of 55.3 months (13-164 months). The patients were seen in the Department of Pediatrics at least once every 6 months. Ophthalmologic examinations were initiated when a patient's CD4 count dropped below 50 or sooner if required for ophthalmologic or other indications. Ophthalmologic examination was then repeated every 6 months. RESULTS: A total of 116 (67%) of 173 patients underwent ophthalmologic examination. Four (3.4%) of 116 patients had CMV retinitis at a mean time of 17.3 months (8-38 months) after their CD4 counts dropped below 20. None of the 4 patients with CMV retinitis had subjective visual complaints despite advanced retinitis. Three patients had bilateral and 1 patient had unilateral CMV retinitis. CONCLUSIONS: CMV retinitis occurred infrequently in HIV-infected pediatric patients and was diagnosed only in patients with a CD4 count below 20. Routine ophthalmologic screening examinations may not be necessary in pediatric patients until the CD4 count is below 20. Because children may not complain of decreased vision, at-risk children should undergo frequent ophthalmologic examination.     

Home care cost-effectiveness for respiratory technology-dependent children

We evaluated home care costs and the cost-effectiveness of home care vs alternative institutional care for respiratory technology-dependent children in a Medicaid Model Waiver Program. "Cost-savings" was measured as the difference between the established Medicaid reimbursable charges to enact an individualized care plan at a long-term care institution and the actual Medicaid reimbursements for home care. Ten patients--six dependent on mechanical ventilation and four with a tracheostomy who were receiving oxygen--were included in the analysis. The mean (+/- SD) annual home care costs were $109,836 +/- $20,781 for ventilator-dependent children and $63,650 +/- $12,350 for oxygen-dependent patients with a tracheostomy, representing annual savings of approximately $79,000 per patient and $83,000 per patient, respectively. The largest portion of home care reimbursements was for nursing care, accounting for 69.0% and 59.0% of the two patient groups. The full program (50 patients) has the potential for a savings of $4 million per year.     

Serologic evidence of human papillomavirus 16 and 18 infections and risk of prostate cancer.

Human papillomavirus (HPV) subtypes 16 and 18 are sexually transmitted and have been associated with an increased incidence of several anogenital tumors. Although previous epidemiological studies have suggested that sexual behaviors such as an early age at first intercourse and larger numbers of sexual partners are also related to an increased risk of prostate cancer, seroepidemiological studies of these infectious agents in relation to prostate cancer have produced differing results. To further evaluate this potential relationship, we completed a population-based control study in King County, Washington. Middle-aged (40-64 years) men diagnosed with prostate cancer (n = 642) were ascertained through the Seattle-Puget Sound Surveillance, Epidemiology, and End Results cancer registry between January 1993 and December 1996. Controls (n = 570) of similar age were selected from the same population as the cases by random digit dialing. Overall, there was no association between serological evidence of prior HPV-16 (adjusted odds ratio, 1.06; 95% confidence interval, 0.71-1.57) or HPV-18 (adjusted odds ratio, 1.36; 95% confidence interval, 0.69-2.69) infection and the risk of prostate cancer. Analyses of clinical features demonstrated no relationship between HPV infection status and Gleason score, stage of disease, or a combined measure of disease aggressiveness. Our findings indicate that HPV-16 and HPV-18 are not associated with prostate cancer risk.     

The influence of reported paternal attitudes on the decision to breast-feed

Objective: To identify factors that influence a woman's decision to breast-feed.
Methodology: Five hundred and fifty-six women were recruited from the maternity wards of two Perth hospitals. Data were collected from a self-administered questionnaire completed by participants prior to discharge. Logistic regression analysis was used to determine factors influencing the initiation of breast-feeding.
Results: At discharge from hospital 83.8% of women were breast-feeding, including 6% who were giving complementary formula feeds. After controlling for potentially confounding demographic and biomedical factors, the father's reported preference for breast-feeding was found to be the most important factor influencing a woman's decision to breast-feed (OR 10.18).
Conclusion: Fathers participate in and influence the choice of infant feeding method and should be included in breast-feeding discussions.     

Margin of safety for discharge after apnea in preterm infants

OBJECTIVE: Most neonatologists include an apnea-free period in the criteria for the discharge of preterm infants. However, the length of time one should wait after the cessation of apnea before sending an infant home without a monitor is debated. We undertook this study in an attempt to define a minimal and safe observation period between the time of the last apnea episode and discharge. METHODS: We reasoned that in infants with idiopathic apnea of prematurity, the intervals between days on which apnea occurs gradually increase until some point at which clinically significant apnea ceases. Therefore, knowledge about the intervals between days on which apnea occurred just before the last apnea would provide a reasonable estimate of the minimal safe observation interval between the last apnea and discharge. We reviewed the charts of 266 infants born in 1993 and 1994 at 相似文献