Placement and replacement of restorations in a military population.
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Dental Restoration, Permanent↗
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Medtronic Hall valve replacement in a third-world population group. A review of the performance of 1000 prostheses.
Between May 1980 and December 1984, 1000 Medtronic Hall prostheses (538 mitral and 462 aortic) were implanted in 852 patients (mean age 30 +/- 15 years) of a third-world type of population group. The most common valve lesions were aortic and mitral regurgitation, and 32% of the patients were in New York Heart Association class IV or greater. Double valve (aortic and mitral) operations were performed in 209 patients. The 782 operative survivors were followed up for 2 to 6.5 years (mean 3.5 years) for a cumulative 2676 patient-years. Valve performance was analyzed in each position separately for valve-related complications. Results for the whole group for the following events are expressed in both linearized (percent/patient-year) and actuarial (percent +/- standard error of the mean freedom at 5 years) terms, respectively: valve-related mortality, 2.9 and 92 +/- 2; reoperation, 1.9 and 90 +/- 2; systemic thromboembolism, 3.3 and 85 +/- 2; thrombotic obstruction, 1.2 and 95 +/- 1; prosthetic valve endocarditis, 0.7 and 97 +/- 1; anticoagulant-related hemorrhage, 0.7 and 98 +/- 1; and periprosthetic leak, 0.7 and 97 +/- 1. Corresponding composite figures for valve failure were 4.3 and 85 +/- 2, and for all valve-related morbidity and mortality were 6.7 and 75 +/- 3. Thrombotic obstruction (fatal in 71% of the cases), anticoagulant-related hemorrhage (61% fatal), and prosthetic endocarditis (44% fatal) were the most lethal complications. Although the differences did not reach statistical significance, aortic prostheses appeared to have a higher incidence of complications than the mitral prostheses. When analyzed against the background of an essentially noncompliant population group, the Medtronic Hall prosthesis proved to be reliable and remarkably free from structural failure. The high incidence of thromboembolism and thrombotic obstruction still mandates anticoagulation.
Adult↗
Ten years experience of renal replacement treatment in the elderly.
UNLABELLED: Elderly patients constitute an increasing segment of the end-stage renal disease population beginning renal replacement therapy (RRT) in the Western Countries. In this study we studied 2447 end-stage renal disease (ESRD) patients who started renal replacement treatment (RRT) in Lombardy between 1983 and 1992 at the age of 65 or older, with particular emphasis on survival and morbidity. In the last decade the number of elderly patients admitted yearly to RRT increased from 113 [102 per million population (pmp), 20% of all accepted patients] in 1983 to 375 (282 pmp, 42% of all accepted patients) in 1992. The most frequent primary nephropathies in 1992 were glomerulonephritis (21% vs 25% in 1983), vascular diseases (18% vs 13%) and diabetes (12% vs 7%). The use of acetate HD and IPD declined over the 10 years period from 49 to 11% and from 26 to 5%; that of bicarbonate HD and CAPD increased from 3 to 46% and from 26 to 32%. Hospitalization rate was related to age, sex, presence of systemic nephropathies or malignancy, but not to treatment modality. The main causes of death in 1992 were cardiovascular diseases (53 vs 42% in 1983) and cachexia (24 vs 18%). The survival rate of all elderly patients was 64, 39 and 13% at 2, 4 and 8 years. The covariates affecting patient survival (Cox model) were the presence at the start of RRT of systemic nephropathies (Hazard ratio 1.7), systemic atherosclerosis (1.6), other comorbidity conditions (1.38) and peritoneal dialysis (1.31). CONCLUSIONS: (1) The progressive increase in the number of patients admitted to RRT in the last decade is due to loose criteria of acceptance of elderly patients (increase in the acceptance rate of diabetics and patients with vascular disease), (2) patients' survival is affected by the presence of comorbid conditions at the start of RRT, (3) the worse survival rate in peritoneal dialysis could result from a hidden negative selection of patients, unmeasured by Cox analysis.
Adult↗
Replacement fertility, what has it been and what does it mean?
Replacement fertility is a term commonly used by demographers when referring to levels of childbearing and yet is rarely explained. It is normally presented as being around 2.1 children per woman. Continued below replacement fertility in developed countries and fertility falling in developing countries has given the concept of replacement fertility a higher profile. This article explains how replacement level is calculated and explores the concept further. Past replacement fertility levels are calculated for England and Wales. A possible alternative definition of replacement is also presented. Simple projection scenarios are used to show the effect on population of below replacement fertility, and also of postponement of fertility. The importance and implications of below replacement fertility are discussed.
Adolescent↗
A novel suppressive activity: complementation between a T cell induced with first-order T-suppressor factor and an I-J-restricted antigen-nonspecific T cell.
Previous studies demonstrated that the first-order T-suppressor factor (TsF1) requires the presence of antigen to induce idiotype-specific Ts cells which readily suppress phenyltrimethylamino (TMA) hapten-specific delayed-type hypersensitivity (DTH) responses when transferred into already immune recipients. In this study we show that TsF1 in the absence of antigen induces a splenic population which limits DTH in recipient mice only when an additional accessory lymphoid population was also cotransferred. Neither of these populations alone was sufficient to mediate suppression and depletion of T cells in either population's abrogated suppression, indicating the T-cell dependency of the complementing cell types. Moreover, suppression was seen only when TMA-TsF1-induced and not normal spleen cell lysate-induced cells were cotransferred with the antigen-induced population, suggesting the requirement for a specific signal to induce the factor-induced population. Further experiments showed that the antigen-induced lymphoid population could be replaced by either heterologous antigen-induced or adjuvant alone-induced splenic populations, indicating the lack of specificity of this secondary population. Further analysis showed that the cell complementation between TMA-TsF1-induced and the nonspecific accessory lymphoid population resulted in antigen-specific and genetically restricted immune suppression. The TsF1-induced lymphoid population was not responsible for the genetic restriction, and furthermore, there was no restriction observed between the two complementing populations. However, matching of the nonspecific accessory cell with the recipient host at the I-J subregion of the H-2 complex was essential for immune suppression. Finally, the activity of complementing cells was found to be independent of cyclophosphamide-sensitive Ts populations of the recipient mice. The ramifications of these findings with reference to the existing suppressor pathways are discussed.
Animals↗
Atrioventricular valve replacement in patients with a single ventricle.
BACKGROUND: Significant atrioventricular valve (AVV) insufficiency has been associated with increased mortality and morbidity in patients with single ventricle. Although many patients can be managed with valvuloplasty alone, some patients require AVV replacement. The optimal timing, outcome, and risk factors for AVV replacement in this population have not been described. METHODS: We retrospectively reviewed our experience with AVV replacement in patients with single ventricle from January 1984 to August 2000. Outcome variables included mortality and valve-related complications. RESULTS: Seventeen patients required AVV replacement. Prosthetic valve types included: St. Jude's valve in 14, Bjork-Shiley in 1, Hall-Kaster in 1, and Carpentier-Edwards in 1. Valve size ranged from 17 to 33 mm, Median age at valve replacement was 3.0 years (range 7 days to 17.3 years). Of the 16 subjects with normal atrioventricular conduction preoperatively, 7 (44%) developed postoperative complete heart block. Hospital mortality was 29%. Hospital mortality decreased significantly from 56% in 1984 to 1993 to no deaths from 1994 to 2000 (p = 0.03). Younger age (less than 2 years) at operation was also a risk factor for hospital mortality (p = 0.03). There were four late deaths in this series and 1 patient underwent heart transplantation. Of the surviving patients, none has required replacement of the prosthetic valve. No patients have had cerebrovascular accident subsequent to AVV replacement. Functional status is New York Heart Association functional class I in 5, class II in 1, and Class III in 1. CONCLUSIONS: Atrioventricular valve replacement can be performed in patients with single ventricle with acceptable morbidity and mortality. The development of postoperative complete heart block is common. Survival after AVV replacement has improved in recent years, and intervention before patients develop ventricular dysfunction and atrial arrhythmias may further improve outcome.
Adolescent↗
Evolution and replacement of Candida albicans strains during recurrent vaginitis demonstrated by DNA fingerprinting.
Southern blot hybridization with the Ca3 probe and the C fragment of the Ca3 probe was used to assess the genetic relatedness of Candida albicans strains from one patient with recurrent C. albicans infection in whom the same strain was maintained, one patient in whom the infecting strain was replaced, and their male sexual partners. In the patient in whom the infecting strain was maintained, the infecting strain exhibited a minor genetic change in each successive episode of Candida vaginitis. These genetic changes occurred in the C-fragment bands of the Ca3 hybridization pattern. In the patient in whom the infecting strain was replaced by another infecting strain, a transition infection involved a genetically mixed infecting population, and the replacement strain appeared to have originated from the oral cavity of the male partner. The results demonstrate that the infecting strains of recurrent Candida vaginitis are not genetically stable, that drug treatment can result in the selection of variants of the previously infecting strain or replacement by a genetically unrelated strain, and that the male partner can be the source of a replacement strain.
Adult↗
Does sex age you?
The evolution of aging and longevity has typically been considered to be a resolution of the conflicting demands on an organism to grow, reproduce, and survive. When social or environmental factors change the opportunities for reproduction in a way that affects differently aged individuals, there will be an evolutionary response in the schedule of senescence. This means that social dynamics can have an important effect on aging. A recent study by Berec and Boukal has shown that the dynamics of mating and divorce can also affect observed life spans through their effect on population dynamics. If females cannot find and maintain mating pairs for long enough to replace themselves, the population will become extinct. This puts a lower limit on the levels of longevity that will be observed in nature.
Aging↗
Emergence of neoplastic transformants spontaneously or after exposure to N-methyl-N'-nitro-N-nitrosoguanidine in populations of rat liver epithelial cells cultured under selective and nonselective conditions.
Many studies have shown that cultured rat liver epithelial cells can be neoplastically transformed by repeated or long-continued exposure to chemical carcinogens. These cells also may transform spontaneously in the absence of carcinogen treatment after long-term, continuous passage in culture or after chronic maintenance in a confluent state in vitro. In this study, we have compared the times of emergence and rates of accumulation of transformed cells in populations of rat hepatic epithelial cells exposed either to a single dose of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG, 3 micrograms/ml culture medium for 30 minutes) or to acetone vehicle alone (3 microliters/ml culture medium for 30 minutes). Transformation was compared in cell populations that were passaged continuously once a week as they attained a confluent density (nonselective growth conditions), or that were maintained at a confluent density for 3 weeks between passages once a month (selective growth conditions). Emergence of both spontaneous transformants and transformants induced by MNNG was facilitated by selective growth conditions, as compared with non-selective growth conditions. Transformants were detected both in cultures exposed to MNNG and in cultures exposed only to acetone (solvent controls), but they always emerged earlier in cultures exposed to MNNG (nine population doublings earlier when grown under selective growth conditions and 22 population doublings earlier when grown under nonselective growth conditions). Once transformants were detected, they replaced the nontransformed population more quickly under selective than under nonselective conditions of culture. Cells possessing the ability to grow in soft agar and to produce tumors in syngeneic rats were detected (at about 12 population doublings after treatment) under selective conditions much earlier than under nonselective growth conditions (at about 90 population doublings after treatment). Among MNNG-treated cultures, the fraction of aneuploid cells in the population was correlated significantly with tumorigenicity. In contrast, among acetone-treated control populations, aneuploidy and tumorigenicity were not correlated; populations of aneuploid acetone-treated cells often were not tumorigenic. These observations suggest that MNNG treatment produced a specific type of aneuploidy that was associated with tumorigenicity.
Animals↗
Clonal evolution of immunoglobulin heavy chain rearrangements in childhood B-precursor acute lymphoblastic leukemia after engraftment in SCID mice.
We grafted childhood B-precursor acute lymphoblastic leukemia (ALL) bone marrow (BM) cells into mice with severe combined immunodeficiency (SCID), in order to study the clonal evolution of immunoglobulin heavy chain (IgH) rearrangements in the absence of selective pressure by chemotherapy. BM cells from nine patients (six diagnosis samples and three relapse samples) were intravenously injected into SCID mice (three mice for each patient). All mice injected with cells from four patients developed a leukemia-like illness 12-40 weeks after injection. By PCR, new subclones that were the result of ongoing IgH rearrangement according to the mechanism operative in the injected cell populations (VH-replacement or VH to D-JH joining) were detected in the engrafted cell populations for all four patients. Subclones were mouse-specific, suggesting that subclone formation is a continuous process. Southern analysis after engraftment was unaltered as compared to the injected cells for one patient and revealed changes indicative of altered clonal composition for three patients. For two patients the observed changes possibly reflect the initial engraftment of a limited number of cells and occurred without changes in other parameters of the engrafted cell population, such as time needed for the development of leukemia, macroscopic organ involvement, immunophenotype and S-phase fraction. In one patient, we demonstrated the selective outgrowth of only a single cell type present at diagnosis, as characterized by IgH rearrangements. Our data show that evolution of clonal IgH rearrangements in B-precursor ALL may occur without the selective pressure of chemotherapy. Additionally, in some patients subclones present at diagnosis, as defined by IgH rearrangements, also possess different biological properties.
Animals↗
The drumbeat of renal failure: symbiosis of prevention and renal replacement therapy.
The global population of patients with end-stage renal disease is rising rapidly, especially in developing countries. The possibility and economic burden of renal replacement therapy will be greatly challenged in the next decade as the prevalence of diabetes and hypertension rises. The establishment of effective prevention and intervention measures creates a means by which the increasing burden of renal replacement therapy can be reduced.
Developing Countries↗
Fate of endogenous stem/progenitor cells following spinal cord injury.
The adult mammalian spinal cord contains neural stem and/or progenitor cells that slowly multiply throughout life and differentiate exclusively into glia. The contribution of adult progenitors to repair has been highlighted in recent studies, demonstrating extensive cell proliferation and gliogenesis following central nervous system (CNS) trauma. The present experiments aimed to determine the relative roles of endogenously dividing progenitor cells versus quiescent progenitor cells in posttraumatic gliogenesis. Using the mitotic indicator bromodeoxyuridine (BrdU) and a retroviral vector, we found that, in the adult female Fisher 344 rat, endogenously dividing neural progenitors are acutely vulnerable in response to T8 dorsal hemisection spinal cord injury. We then studied the population of cells that divide postinjury in the injury epicenter by delivering BrdU or retrovirus at 24 hours after spinal cord injury. Animals were euthanized at five timepoints postinjury, ranging from 6 hours to 9 weeks after BrdU delivery. At all timepoints, we observed extensive proliferation of ependymal and periependymal cells that immunohistochemically resembled stem/progenitor cells. BrdU+ incorporation was noted to be prominent in NG2-immunoreactive progenitors that matured into oligodendrocytes, and in a transient population of microglia. Using a green fluorescence protein (GFP) hematopoietic chimeric mouse, we determined that 90% of the dividing cells in this early proliferation event originate from the spinal cord, whereas only 10% originate from the bone marrow. Our results suggest that dividing, NG2-expressing progenitor cells are vulnerable to injury, but a separate, immature population of neural stem and/or progenitor cells is activated by injury and rapidly divides to replace this vulnerable population.
Animals↗
Population review: (4). Trends in fertility.
Fertility in the United Kingdom has now been at a level below that needed for natural replacement of the population (TPFR of 2.1) for more than twenty years. Whilst fertility in many parts of the world (eg most of Europe, and much of the developing world) has declined sharply in recent years, the overall rate in the United Kingdom has been fairly stable (TPFR about 1.8) since 1980. Women are having their children at older ages: fertility rates have been falling for women aged under 30 and rising for women above that age. The mean age at motherhood rose by 1.4 years to 28.4 in England and Wales between 1984 and 1994. The proportion of women in England and Wales who were still childless at age 45 rose to 13 per cent in 1994, and will increase further in the future. One third of births are now to women who are not married, but the recent rapid increase in this proportion may not continue. The percentage of all births which are both outside marriage and registered solely by the mother has been fairly stable (around 7 per cent) for several years. Fertility rates are higher in Northern Ireland than in the rest of the United Kingdom, and lowest in Scotland and in the North of England. Northern Ireland has the lowest proportion of births outside marriage.
Adolescent↗
Evaluation of left ventricular functions after aortic valve replacement in a specific young male patient population with pure aortic insufficiency or aortic stenosis: 5-years follow-up.
BACKGROUND: The aim of this study was to evaluate the left ventricular functions and the regression of left ventricular hypertrophy after aortic valve replacement (AVR) in young male patients with pure aortic stenosis or aortic insufficiency with no additional disease. METHODS: Young male patients who underwent AVR because of pure aortic stenosis (AS = 68) and insufficiency (AI = 70) were enrolled in the study. The mean age was 23.2 +/- 1.3 and 22.6 +/- 1.6 years, respectively. The follow-up time was 5 years. The parameters checked by transthoracic echocardiography were interventricular septum diastolic thickness, left ventricular posterior wall diastolic thickness, left ventricular end-diastolic diameter, left ventricle mass, left ventricle mass index, ejection fraction, and peak aortic gradient. Relative ventricle wall thickness was also calculated. Both groups values from the preoperative, postoperative sixth month, second year, and fifth year time intervals were compared. RESULTS: In the AS group, the preoperative left ventricular ejection fraction (%) value of 53.68 +/- 5.04 increased to 63.24 +/- 4.11 at the end of the fifth year. In the AI group, the preoperative left ventricular ejection fraction (%) value of 48.40 +/- 3.56 increased to 59.77 +/- 2.75 at the end of the fifth year. The other left ventricular geometric parameters were also compared within each group. At the end of the fifth year, there were significant and positive changes in each group. CONCLUSION: The regression of the left ventricular parameters is a process that occurs over many years following the correction of the primary hemodynamic abnormality. Although the results were similar in the AI and AS group, in the AS group the remodeling process had earlier results than in the AI group.
Adult↗
A patient pathway to renal replacement therapy: implementation in the progressive renal insufficiency population.
Care paths and patient pathways are collaborative interdisciplinary tools developed to provide quality care. One goal in progressive renal insufficiency (PRI) care is to provide patients and family members with relevant and timely information to help them cope with medical therapy and lifestyle changes required to slow the progression of renal insufficiency. At Halton Healthcare Services, clinical and patient pathways have been widely used with success. Recognizing the potential benefits of a patient pathway for the PRI population, our interdisciplinary team developed a pathway that outlines the journey to renal replacement therapy. The pathway provides the patient with some insight into the future, as their disease process continues to have impact on their life. Reviewed by a patient within our PRI program during the development process, we have tailored this pathway to meet the needs of this unique population. We predict this patient pathway will have positive impact on the patient's understanding of the role of the PRI clinic and the partnership between the team members, the patient, and the family.
Continuity of Patient Care↗
Use of low molecular weight heparin for prevention of deep vein thrombosis in total knee arthroplasty--a study of its efficacy in an Asian population.
INTRODUCTION: The aims of this paper were to study the incidence of deep vein thrombosis following total knee replacement in an Asian population and to evaluate the role of low molecular weight heparin for deep vein thrombosis in this setting. MATERIALS AND METHODS: We prospectively studied two groups of 100 consecutive patients undergoing total knee replacement separately. Group 1 did not receive any low molecular weight heparin and group 2 received low molecular weight heparin, nodraparin calcium (Fraxiparine) according to body weight. The sex distribution, age group, weight, preoperative knee and function scores, and postoperative rehabilitation were similar for both groups. A single ultrasound technician performed ultrasound duplex scan of both lower limbs on the seventh postoperative day. RESULTS: The incidence of deep vein thrombosis in group 1 was 14% (14 patients, 5 proximal vein thromboses and 9 distal vein thromboses) while in group 2, no patients developed deep vein thrombosis. There was no increased incidence, either local or systemic, of major bleeding complications with the use of low molecular weight heparin. CONCLUSION: While the incidence of deep vein thrombosis following total knee replacement in an Asian population appears lower compared to Western populations, the use of low molecular weight heparin for thromboprophylaxis appears to further reduce the incidence without major bleeding complications.
Activities of Daily Living↗
Changes in phenotypically distinct mucosal macrophage populations may be a prerequisite for the development of inflammatory bowel disease.
Previous studies have demonstrated the presence of much more marked macrophage heterogeneity in colonic mucosa affected by the idiopathic inflammatory bowel diseases (ulcerative colitis and Crohn's disease) than in normal mucosa. This study examines the morphology, distribution and phenotypic expression of mucosal macrophage-like cells in biopsies from patients with idiopathic inflammatory bowel disease in comparison with disease control samples from patients with colonic infection or ischaemia. Approximately 80% of macrophage-like cells in histologically normal mucosa co-express the antigens recognized by the monoclonal antibodies RFD1 (an interdigitating cell marker) and RFD7 (a marker for mature tissue macrophages). In idiopathic inflammatory bowel disease, the normal colonic macrophage population is partly replaced by cells staining positively with RFD7 alone, and, to a lesser extent, with RFD1+ dendritic cells. Sections from patients with infections and ischaemia exhibited epithelial HLA-DR positivity and infiltration of the lamina propria by a more heterogeneous population of macrophages than that seen in histologically normal mucosa. However, the displacement of the normal colonic macrophage phenotype by RFD7+ tissue macrophages occurred to a significantly greater extent in idiopathic inflammatory bowel disease than in disease control mucosa. A pathognomonic feature of the ulcerative colitis and Crohn's colitis sections was the clustering of RFD9+ epithelioid cells at the bases of disrupted crypts and adjacent to areas of mucosal damage. It is concluded that a degree of macrophage heterogeneity and macrophage infiltration can occur as a non-specific response to colonic mucosal damage. The distinctive feature of idiopathic inflammatory bowel disease mucosa is the almost complete replacement of the normal colonic mucosal macrophage population by tissue macrophages and epithelioid cells, and this phenomenon may be important in promoting the development of a chronic inflammatory state.
Adolescent↗
The therapeutic potential of human olfactory-derived stem cells.
Stem cells from fetal and adult central nervous system have been isolated and characterized, providing populations for potential replacement therapy for traumatic injury repair and neurodegenerative diseases. The regenerative capacity of the olfactory system has attracted scientific interest. Studies focusing on animal and human olfactory bulb ensheathing cells (OECs) have heightened the expectations that OECs can enhance axonal regeneration and repair demyelinating diseases. Harvest of OECs from the olfactory bulb requires highly invasive surgery, which is a major obstacle. In contrast, olfactory epithelium (OE) has a unique regenerative capacity and is readily accessible from its location in the nasal cavity, allowing for harvest without lasting damage to the donor. Adult OE contains progenitors responsible for the normal life-long continuous replacement of neurons and supporting cells. Culture techniques have been established for human OE that generate populations of mitotically active neural progenitors that form neurospheres (Roisen et al., 2001; Winstead et al., 2005). The potential application of this technology includes autologous transplantation where minimal donor material can be isolated, expanded ex vivo, and lineage restricted to a desired phenotype prior to/or after re-implantation. Furthermore, these strategies circumvent the ethical issues that arise with embryonic or fetal tissues. The long term goal is to develop procedures through which a victim of a spinal cord injury or neurodegenerative condition would serve as a source of progenitors for his/her own regenerative grafts, avoiding the need for immunosuppression and ethical controversy. In addition, these cells can provide populations for pharmacological and/or diagnostic evaluation.
Cells, Cultured↗