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PubMed1971

Control of mitochondrial turnover under the influence of thyroid hormone.

The effect of thyroid hormone on the turnover of mitochondrial DNA and protein was studied in rat heart and liver. Changes in turnover were observed in both thyroidectomized and normal rats following administration of thyroid hormone. In heart and liver the turnover of mitochondrial DNA and protein was slower in thyroidectomized rats than in normal rats. The turnover of mitochondrial DNA and protein was affected similarly following the administration of thyroid hormone, suggesting that mechanisms which control turnover of mitochondrial constituents may be predicated upon a major part of the mitochondrion. In heart a decreased rate of degradation contributes to the increase in total mitochondrial protein. Mitochondrial DNA, labeled before administration of thyroid hormone, turns over, after the start of thyroid hormone administration, at a different rate from that in newly synthesized DNA. The different turnover rates suggest that in liver the pre-existing population of mitochondria is being replaced by another population synthesized under new physiological conditions.

Animals↗
PubMed2001

Age-adjusted death rates: trend data based on the year 2000 standard population.

Age-adjusted death rates are routine mortality risk measures used to compare rates over time or between groups such as those living in different geographic areas. This type of measure eliminates differences that would be caused because one population is older than another. Beginning with mortality data for 1999, the standard population used by the Centers for Disease Control and Prevention's National Center for Health Statistics (NCHS) to calculate age-adjusted death rates based on the Year 2000 estimated population distribution replacing that of 1940 used previously. Comparisons of 1999 mortality data with that of 1998 and earlier years cannot be made unless age-adjusted death rates are based on the same standard population. Changing the standard population generally changes the magnitude of an age-adjusted death rate and may change the magnitude of the differential between two groups. Typically, the change in standard makes relatively little difference in the mortality trend but it can when age-specific rates have divergent patterns. This publication provides age-adjusted death rates by race and sex based on the year 2000 population standard and directs readers to the NCHS Web site for age-adjusted death rates by selected causes.

Age Distribution↗
PubMed1981

Neurogenesis in olfactory epithelium: loss and recovery of transepithelial voltage transients following olfactory nerve section.

1. Unilateral olfactory nerve section was performed on the salamander, Ambystoma tigrinum. Physiological recordings and macroscopic observations were made to investigate the physiological correlates of functional recovery in the olfactory epithelium. 2. Slow transepithelial voltage transients, Veog, evoked by several odorous stimuli systematically decreased in amplitude during the initial 7 days and were not recorded at 10 days following nerve section, suggesting retrograde degeneration of receptor neurons. This was true for negative Veog(-), and positive, Veog(+), response components. Responses obtained from the untreated contralateral side of each animal remained similar to nonaxotomized controls. 3. Progressive recovery of the voltage transients was studied at 24, 45, 80, and 100 days following nerve section. At all stages of recovery, the wave form and time course of the responses were characteristic for each stimulus. This suggested that the response properties of the newly differentiated neuronal population were similar to those of the mature population. 4. At 100 days, response amplitudes evoked by all stimuli were similar to control values at all recording sites on the epithelial surface. The simultaneous loss and recovery of positive and negative components of the Veog indicated that the sources of both are dependent on the presence of functionally mature olfactory receptor neurons. 5. Visual inspection indicated that the olfactory nerve was reconstituted and reconnected to the olfactory bulb between 30-60 days following transection. The fact that physiological activity was recorded in the epithelium prior to this event suggests that molecular recognition and sensory transduction are not dependent on connectivity with the olfactory bulb. 6. It is concluded that physiological recovery of the olfactory receptor cell population occurs following axotomy. The time course of recovery was consistent with morphological evidence (see Ref. 57), indicating that newly differentiated receptor neurons are derived from cells in the basal region of the epithelium and replace the population lost through retrograde degeneration.

Ambystoma↗
PubMed2005

Africanization in the United States: replacement of feral European honeybees (Apis mellifera L.) by an African hybrid swarm.

The expansion of Africanized honeybees from South America to the southwestern United States in <50 years is considered one of the most spectacular biological invasions yet documented. In the American tropics, it has been shown that during their expansion Africanized honeybees have low levels of introgressed alleles from resident European populations. In the United States, it has been speculated, but not shown, that Africanized honeybees would hybridize extensively with European honeybees. Here we report a continuous 11-year study investigating temporal changes in the genetic structure of a feral population from the southern United States undergoing Africanization. Our microsatellite data showed that (1) the process of Africanization involved both maternal and paternal bidirectional gene flow between European and Africanized honeybees and (2) the panmitic European population was replaced by panmitic mixtures of A. m. scutellata and European genes within 5 years after Africanization. The post-Africanization gene pool (1998-2001) was composed of a diverse array of recombinant classes with a substantial European genetic contribution (mean 25-37%). Therefore, the resulting feral honeybee population of south Texas was best viewed as a hybrid swarm.

Africa↗
PubMed2001

Smoking and quitting with the aid of nicotine replacement therapies in the English adult population. Results from the Health Education Monitoring Survey 1995.

BACKGROUND: Many clinical trials have shown the usefulness of nicotine replacement therapies, family physician advice and other cessation aids in enhancing smoking cessation. However, many trials have taken place amongst selected patients and doctors. This paper assesses cessation amongst a representative general adult population in England in order to see whether such aids are as successful amongst more typical smokers. METHODS: Descriptive information on the pattern of smoking cessation aids use in the English population is presented for the first time. This is followed by multivariate probit analysis of the 'Health in England 1995' survey data set in order to predict successful smoking cessation as a function of several variables including use of nicotine gum and patches, willpower, advice from family physicians, social class, education, gender, marital status and family composition. RESULTS: The results tend to confirm that lower social class and lower educational achievement are linked to continuing smoking status. However, users of nicotine gum and patches were found to be less likely to have given up smoking than non-users. This may be explained by the fact that only those who find it difficult to give up will go to the time and expense of considering such aids. These findings could also be explained by the fact that gum and patches have only been available recently in England. The pattern of results also suggests that 'willpower' is a marker for success in cessation as opposed to a determinant of giving up in its own right. CONCLUSION: This research confirms a lot of other research on the determinants of smoking cessation and has for the first time looked at the use and impact of nicotine replacement therapy on giving up in a representative English adult population. More research is needed on observational data sets in order to tease out the true impact of nicotine replacement on cessation rates in representative smoking populations.

Adolescent↗
PubMed1999

[Prevalence of Trypanosoma cruzi infection in opossum (Didelphis albiventris) in Santiago del Estero, Argentina].

The opossum of the genus Didelphis is one of the principal wild reservoirs of Trypanosoma cruzi and is widely distributed in the Western Hemisphere. Didelphis albiventris is the most common marsupial in Amamá and Trinidad, two communities in the province of Santiago del Estero, Argentina. The D. albiventris population is replaced every year, and the opossum normally has two reproductive periods, one at the beginning of the spring and another at the beginning of the summer. The two litters are weaned, and they leave the mother's marsupial pouch to join the population, the first (G1) at the beginning of the summer and the second (G2) at the beginning of the fall. Between 1988 and 1991 409 D. albiventris opossums were studied, and xenodiagnoses showed that 35% of them were infected with T. cruzi. Annual cycles of renewed infection were observed, with prevalences that ranged between 22% and 43%. The acquisition of the parasite occurred over the entire year, from the summer through the spring. The prevalence of infection increased with age. The G1 individuals tended to present higher prevalences than the G2 individuals, probably from being exposed to transmission for a longer period of time. In the first two (younger) age categories for the opossums, G2 individuals showed higher prevalences than did the G1 individuals. This indicates a significant increase in transmission intensity during the fall. Opossums should be regarded as a potential source of T. cruzi entry to the domestic transmission cycle.

Animals↗
PubMed1982

Valve replacement in children. A fifteen-year perspective.

Between 1965 and 1980, 64 children form 1 to 19 years of age have undergone replacement of the aortic, mitral, or tricuspid valve at The Johns Hopkins Hospital. Three of these patients have had successful second valve replacements 4 to 12 years after the initial operation. During the first 5 year period of this review, the hospital mortality was 31%, whereas only one of 33 children having valve replacement during the most recent 5 year period died early after operation (hospital mortality, 1976 to 1980, 3%). Thromboembolic complications have been seen in only two patients in this group, for an incidence of 0.8% per patient-year. Among patients receiving long-term warfarin anticoagulation, there has been only one major bleeding episode in 133 patient-years of follow-up. The type of valve prosthesis implanted during this 15 year period has changed greatly. Ninety-four percent of the prostheses placed during the initial 5 year period were the caged-poppet type of valve, whereas tilting disc, central flow, and tissue valve substitutes have been implanted more recently. Eight of the 10 patients most recently undergoing valve replacement have received St. Jude Medical prostheses, and postoperative catheterization studies have confirmed the excellent hemodynamic performance of these valves, even in patients with prostheses of very small annular diameter. Despite the disappointing occurrence of premature tissue valve failure in the young population, valve replacement in children currently is safer and there is a wider variety of technically satisfactory valve substitutes available for implantation today.

Age Factors↗
PubMed1996

The need and demand for renal replacement therapy in ethnic minorities in England.

STUDY OBJECTIVE: The study aimed to determine the relative risk of being accepted for renal replacement treatment of black and Asian populations compared with whites in relation to age, sex, and underlying cause. The implications for population need for renal replacement therapy in these populations and for the development of renal services were also considered. DESIGN/SETTING: This was a cross sectional retrospective survey of all patients accepted for renal replacement treatment in renal units in England in 1991 and 1992. PATIENTS: These comprised all 5901 patients resident in England with end-stage renal failure who had been accepted for renal replacement therapy in renal units in England and whose ethnic category was available from the units. Patients were categorised as white, Asian, black, or other. Population denominators for the ethnic populations were taken from the 1991 census. The census categories Indian, Pakistani, and Bangladeshi were aggregated to form the denominator for Asian patients, and black Caribbeans, black Africans, and black others were aggregated to form the denominator for black patients. MAIN RESULT: Altogether 7.7% of patients accepted were Asian and 4.7% were black; crude relative acceptance rates compared with whites were 3.5 and 3.2 respectively. Age sex specific relative acceptance ratios increased with age in both ethnic populations and were greater in females. Age standardised acceptance ratios were increased 4.2 and 3.7 times in Asian and black people respectively. The most common underlaying cause in both these populations was diabetes; relative rates of acceptance for diabetic end-stage renal failure were 5.8 and 6.5 respectively. The European Dialysis and Transplant Association coding system was inaccurate for disaggregating non-insulin and insulin dependent forms. "Unknown causes" were an important category in Asians with a relative acceptance of rate 5.7. The relative rates were reduced only slightly when the comparison was confined to the district health authorities with large ethnic minority populations, suggesting that geographical access was not a major factor in the high rates for ethnic minorities. CONCLUSION: Acceptance rates for renal replacement treatment are increased significantly in Asian and black populations. Although data inaccuracies and access factors may contribute to these findings, the main reason is probably the higher incidence of end-stage renal failure. This in turn is due to the greater prevalence of underlying diseases such as non-insulin dependent diabetes but possibly also increased susceptibility of developing nethropathy. The main implication is that these populations age demand for renal replacement treatment will increase. This will have an impact nationally but will be particularly apparent in areas with large ethnic minority populations. Future planning must take these factors into account and should include strategies for preventing chronic renal failure, especially that due to non-insulin dependent diabetes and hypertension. The data could not determine the extent to which population need was being met; further studies are required to estimate the incidence of end-stage renal failure in ethnic minority populations.

Adolescent↗
PubMed1991

Placement and replacement of restorations in a military population.

The purpose of this study was to investigate the reasons for placement and replacement of restorations provided to military personnel by all 34 dentists stationed in the four Atlantic provinces of Canada. All dentists who participated in this study are salaried. Over a period of 30 working days, each dentist recorded information on all restorations performed. Data were collected on dentists' year of graduation, patient age, treatment requirements, tooth number, restoration class, materials used and reasons for placement and replacement. All dentists used the same data collection form which was pilot tested. Information was collected on 2,280 restorations from 643 adults, 18 to 57 years of age. Of all restorations, 54.3% were placements and 45.7% were replacements. No difference in placement and replacement rates between amalgam and composites was reported. The major reason for placement was primary caries (90%). The major reasons for replacements were recurrent caries (40.0%), primary caries of interproximal surfaces (18.9%), and fractured restorations (12.3%). Of the 297 MOD restorations, 74.3% were replacements and of the 1,140 Class I + III + V restorations, 27.8% were replacements. This study showed that about half of the restorative work carried out were replacements. Caries is the primary reason for placement and replacement of restorations in adults.

Canada↗
PubMed1978

Persistent infection of L cells with vesicular stomatitis virus: evolution of virus populations.

A previous report (Youngner et al., J. Virol. 19:90-101, 1976) documented that noncytocidal persistent infection can be established with wild-type vesicular stomatitis virus (VSV) in mouse L cells at 37 degrees C and that a rapid selection of RNA(-), group I temperature-sensitive (ts) mutants consistently occurs in this system. To assess the selective advantage of the RNA(-)ts phenotype, evolution of the virus population was studied in persistent infections initiated in L cells by use of VSV ts 0 23 and ts 0 45, RNA(+) mutants belonging to complementation groups III and V. In L cells persistently infected with ts 0 23, the ts RNA(+) virus population was replaced gradually by viruses which had a ts RNA(-) phenotype. VSV ts 0 45 (V) has another marker in addition to reduced virus yield at 39.5 degrees C: a defective protein (G) which renders virion infectivity heat labile at 50 degrees C. Persistent infections initiated with this virus (ts, heat labile, RNA(+)) evolved into a virus population which was ts, heat resistant, and RNA(-). These findings suggest that the ts phenotype itself is not sufficient to stabilize the VSV population in persistently infected L cells and also indicate that the ts RNA(-) phenotype may have a unique selective advantage in this system. In addition to the selection of ts RNA(-) mutants, other mechanisms which also might operate in the maintenance of persistent VSV infections of L cells were explored. Whereas defective-interfering particles did not seem to mediate the carrier state, evidence was obtained that interferon may play a role in the regulation of persistent infections of L cells with VSV.

L Cells↗
PubMedDate not supplied

Hormone replacement therapy and glucose tolerance in EPIC-Norfolk: a population-based study.

BACKGROUND: Hormone replacement therapy (HRT) can affect glucose homeostasis in postmenopausal women but it is unclear whether long-term use is associated with changes in glucose tolerance. The objective was to examine the relationship of glycated haemoglobin (HbA(1C)) concentration with HRT use in non-diabetic postmenopausal women. METHODS: A cross-sectional analysis of baseline data on 2753 postmenopausal women, aged 45-74 years who were recruited to the EPIC-Norfolk study between 1995 and 1998 was performed. Women completed a health and lifestyle questionnaire from which information on HRT use was obtained and gave blood for HbA(1C) assay. RESULTS: Of the women, 23% were current HRT users and 14% were former users. Mean HbA(1C) was significantly lower in current users compared to former and never users. This difference was independent of age, body mass index (BMI), waist-to-hip ratio (WHR), family history of diabetes, educational status, employment status, smoking history, history of alcohol consumption, parity, known illness and hysterectomy status. Compared to never users of HRT, the unadjusted odds ratio (OR) for being in the highest quintile of HbA(1C) distribution as opposed to the lowest was 0.28 (95% CI 0.20-0.39) for current users and 0.41 (0.32-0.53) for ever users. After adjustment for confounders, the OR were 0.52 (0.34-0.79) and 0.72 (0. 51-1.03) for current and ever users, respectively. CONCLUSION: Women currently using HRT have lower HbA(1C) levels not explained by known confounders though we cannot completely exclude a healthy user effect. Nevertheless, this population study suggest that current use of HRT was not associated with impairment of glucose tolerance in postmenopausal women.

Aged↗
PubMed2001

Mitral valve replacement with chordal preservation in a rheumatic population.

BACKGROUND AND AIM OF THE STUDY: Mitral valve replacement (MVR) with preservation of the subvalvular apparatus may maintain postoperative left ventricular (LV) function better than conventional MVR. A prospective study was undertaken to assess the advantages of chordal preservation in rheumatic patients undergoing isolated MVR. METHODS: Between January 1996 and January 1999, 240 patients with rheumatic etiology and normal LV ejection fraction (>50%) underwent isolated MVR using a St. Jude Medical prosthesis. Patients were allocated to two groups: in group I (n = 168), both the anterior and posterior chordae were preserved; in group II (n = 72), the entire native mitral valve apparatus was excised. Patients from both groups were evaluated postoperatively (mean 12.5 months) by echocardiography and treadmill testing. RESULTS: Demographic and clinical profiles were comparable in both groups. There were three early deaths in group I, and one in group II. There were no late deaths. One patient in group I required reoperation for a stuck mitral prosthesis. LV function (ejection fraction >50%) was better in group I (94%) than in group II (82%) (p <0.05). No patient in either group had LV outflow tract obstruction on echocardiography. Patients in group I showed better exercise performance on treadmill (Bruce protocol): 92% of group I patients versus 88% of group II patients (p >0.05) completed stage I; 16% of group I patients, but no group II patients, were able to complete stage IV (p <0.05). CONCLUSION: Mitral valve replacement with preservation of the subvalvular apparatus maintains LV function, and does not cause LV outflow tract obstruction.

Adult↗
PubMed1996

The emergence of non-cytolytic NK1.1+ T cells in the long-term culture of murine tumour-infiltrating lymphocytes: a possible role of transforming growth factor-beta.

The mechanism by which murine tumour-infiltrating lymphocytes (TIL) decreased their anti-tumour activity during an in vitro culture with interleukin-2 (IL-2) was investigated. A phenotype analysis revealed that the TIL cultured for 7 days (TIL-d7) were exclusively NKI.1- CD4- CD8+ CD3+ cells and that this population was replaced by natural killer (NK)1.1+ CD4- CD8 CD3+ cells by day 27 (TIL-d27) during the culture of TIL. The TIL-d7 cells showed a cytolytic activity against B16 melanoma, whereas the TIL-d27 cells had lost this activity, suggesting that the decrease in the anti tumour effect of TIL during the culture with IL-2 was due to their populational change. Analysis on the characteristics of the TIL-d27 cells revealed that they expressed skewed T-cell receptor (TCR) V beta 5 and increased mRNA expression of V alpha 14. In addition, they expressed transforming growth factor beta (TGF-beta) mRNA. Interestingly, TGF-beta augmented the proliferation of TIL-d27 cells under the presence of IL-2, but suppressed that of TIL-d7 cells. Moreover, the proliferation of TIL-d27 cells was suppressed by anti-TGF-beta monoclonal antibody. Collectively, these results suggest that, in contrast to its suppressive effect on anti-tumour effector T cells. TGF-beta could be an autocrine growth factor for NKL1.1+ T cells and thereby induce non-cytolytic NK1.1+ T cells in the long-term culture of TIL.

Animals↗
PubMed2000

Interdisciplinary approach to a total knee replacement program.

An orthopedic clinical nurse specialist facilitated an interdisciplinary evaluation, design, and implementation of best practice initiatives for the total knee replacement patient population using the Center for Advanced Nursing Practice's Evidence-Based Practice Model. The interdisciplinary team approach enhanced the total joint program by achieving positive patient outcomes, demonstrating financial stewardship of resources, and facilitating inter- and intradisciplinary communication.

Anticoagulants↗
PubMed2006

Management of postmenopausal symptoms in breast cancer survivors.

With the increasing numbers of breast cancers survivors, menopause, its symptoms, and its physical complications are becoming more prevalent problems in this patient population. Hormonal replacement, which has been the cornerstone therapy of menopausal related symptoms for decades, recently has been shown to increase breast cancer incidence as well as risk of recurrence and no longer should be recommended. Menopausal symptoms and complications such as hot flashes, vaginal dryness, dyspareunia, and osteoporosis leading to fractures have a negative impact on the quality of life of both breast cancer survivors and the general postmenopausal population. The purpose of this review is to discuss the evidence for the use of alternative therapies for menopausal symptoms, thus providing guidance and recommendations that should facilitate therapeutic decisions in the daily practice of medical oncologists and primary care physicians.

Breast Neoplasms↗
PubMed2006

Determinants of cardiovascular risk in 2589 hypopituitary GH-deficient adults - a KIMS database analysis.

OBJECTIVE: The aim of the present study was to clarify the relationship between GH deficiency (GHD) and some cardiovascular risk factors and to analyse the effect of GH replacement therapy in a large number of patients over a prolonged period of time. DESIGN: Data for analysis were retrieved from KIMS (Pfizer International Metabolic Database). Serum concentrations of total cholesterol, high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol and triglycerides were obtained from 2589 patients at baseline and from 1206 patients after 1 and 2 years of GH replacement therapy. Body mass index (BMI), waist and hip, resting blood pressure and body composition were also measured. RESULTS: At baseline, the unfavourable effects of GHD were most obvious in the lipid profile demonstrating elevated mean total and LDL-cholesterol, in the increased waist circumference and the elevated BMI. The cholesterol concentration, BMI and body composition were significantly adversely affected by a number of factors, including age, sex and the use of anti-epileptic drugs. The therapeutic effect of GH was essentially uniform across the whole population. GH replacement reduced significantly the mean total and LDL-cholesterol, the waist circumference and the fat mass and was maintained during 2 years. CONCLUSIONS: This analysis of a large number of patients confirmed that GHD adults present with an increased cardiovascular risk. The sustained improvement of the adverse lipid profile and body composition suggests that GH replacement therapy may reduce the risk of cardiovascular disease and the premature mortality seen in hypopituitary patients with untreated GHD.

Adult↗