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PubMed1996

Molecular analysis of glomerular diseases in renal biopsies: initial results of a collaborative international study. The International Study Group for Molecular Study of Kidney Biopsies.

An accurate assessment of which patient with glomerular disease will progress to end-stage renal failure would be an important addition to establishing prognosis and evaluating therapeutic strategies. We previously found the development of glomerular scarring in animal models was preceded by an increase in glomerular type IV collagen mRNAs and that the level of scarring predicted the rate of progression. The purpose of this study was to determine whether these findings apply to human glomerular diseases using microdissected glomeruli and assessment of mRNA by competitive PCR. After showing that the levels of type IV collagen mRNAs were elevated in sclerotic glomeruli isolated from nephrectomies, we undertook this preliminary cross-sectional study of type IV collagen subchain mRNAs in renal biopsies in two of the leading causes of glomerulosclerosis, diabetic nephropathy, and membranous glomerulopathy. We found that glomerular type IV collagen mRNA levels were altered in disease-specific ways. The relative levels of the individual alpha-chains of type IV collagen depended on the anatomic site of the glomerular lesions. The alpha 2 type IV/alpha 3 type IV collagen mRNA ratio was high in diabetes mellitus, but not in membranous glomerulopathy. These data, coupled with those obtained from experimental animals, suggest that a dysregulation of basement collagen synthesis underlies progressive glomerular scarring. If these conclusions are verified in prospective studies it will be feasible to assess the risk of developing progressive glomerulosclerosis in the individual patient and to quantitatively assess therapeutic responses in a timely manner.

Aged↗
PubMed1988

International consultation and the homogenization of psychiatry in Southeast Asia.

The nature of psychiatric care varies little among the capital cities of Southeast Asia. Differences that may exist are of degrees along a common dimension. Colonial forces from the past and contemporary diffusion of modern psychiatry have produced this remarkably uniform pattern of thought and treatment across divergent national and cultural boundaries. Our paper analyzes the homogenization of psychiatry in Southeast Asia in three ways. First, we examine international mental health education, consultation and collaboration as interlocking mechanisms for the transfer of psychiatric technology. Second, the indirect and undesirable consequences of the diffusion of psychiatric knowledge and practice are analyzed. Third, we pose recommendations for countering these unanticipated consequences through evaluation research, ethical guidelines, and educational and intervention practices that strengthen indigenous healing resources.

Asia, Southeastern↗
PubMed2001

Collaborative quality improvement for neonatal intensive care. NIC/Q Project Investigators of the Vermont Oxford Network.

OBJECTIVE: To make measurable improvements in the quality and cost of neonatal intensive care using a multidisciplinary collaborative quality improvement model. DESIGN: Interventional study. Patient demographic and clinical information for infants with birth weight 501 to 1500 g was collected using the Vermont Oxford Network Database for January 1, 1994 to December 31, 1997. SETTING: Ten self-selected neonatal intensive care units (NICUs) received the intervention. They formed 2 subgroups (6 NICUs working on infection, 4 NICUs working on chronic lung disease). Sixty-six other NICUs served as a contemporaneous comparison group. PATIENTS: Infants with birth weight 501 to 1500 g born at or admitted within 28 days of birth between 1994 and 1997 to the 6 study NICUs in the infection group (n = 3063) and the 66 comparison NICUs (n = 21 509); infants with birth weight 501 to 1000 g at the 4 study NICUs in the chronic lung disease group (n = 738). INTERVENTIONS: NICUs formed multidisciplinary teams that worked together under the direction of a trained facilitator over a 3-year period beginning in January 1995. They received instruction in quality improvement, reviewed performance data, identified common improvement goals, and implemented "potentially better practices" developed through analysis of the processes of care, literature review, and site visits. MAIN OUTCOME MEASURES: The rates of infection after the third day of life with coagulase-negative staphylococcal or other bacterial pathogens for infants with birth weight 501 to 1500 g, and the rates of oxygen supplementation or death at 36 weeks' adjusted gestational age for infants with birth weight 501 to 1000 g. RESULTS: Between 1994 and 1996, the rate of infection with coagulase-negative staphylococcus decreased from 22.0% to 16.6% at the 6 project NICUs in the infection group; the rate of supplemental oxygen at 36 weeks' adjusted gestational age decreased from 43.5% to 31.5% at the 4 NICUs in the chronic lung disease group. There was heterogeneity in the effects among the NICUs in both project groups. The changes observed at the project NICUs for these outcomes were significantly larger than those observed at the 66 comparison NICUs over the 4-year period from 1994 to 1997. CONCLUSION: We conclude that multidisciplinary collaborative quality improvement has the potential to improve the outcomes of neonatal intensive care.

Chronic Disease↗
PubMed2003

The Zuni kidney project: a collaborative approach to an epidemic of kidney disease.

There is an epidemic of renal disease among the Zuni Indians. In contrast to most other American-Indian communities, the epidemic of renal disease among the Zuni Indians reflects high rates of diabetic and nondiabetic renal disease. Almost every Zuni Indian has a relative with end-stage renal disease. This epidemic offers a unique opportunity to advance our understanding of the risk factors for the susceptibility and/or progression of renal disease. Thus, Zuni Tribal leaders formed a research partnership with the University of New Mexico Health Sciences Center, Indian Health Service, Southwest Foundation for Biomedical Research and Dialysis Clinic Inc., to establish the Zuni Kidney Project (ZKP). The ZKP conducted a population-based, cross-sectional survey of the Zuni Pueblo. Age and gender distributions among survey participants were similar to those of the eligible Zuni population. Among diabetics the prevalence (95% confidence interval) of incipient albuminuria (IA) was 32.3% (25.1, 39.5) in women and 36.1% (24.7, 47.5) in men. The prevalence of IA among nondiabetics was 9.3% (6.9, 11.7) in women and 12.2% (9.7, 14.7) in men. Among diabetics, the prevalence of overt albuminuria (OA) was 17.7% (11.9, 23.5) in women and 20.8% (11.4, 30.2) in men. Among nondiabetics, OA was present in 1.2% (0.3, 2.1) of women and 2.3% (1.1, 3.5) of men. Although IA and OA were each more common among diabetics, the majority of participants with albuminuria were nondiabetics. Hematuria was common among both diabetics and nondiabetics. Among diabetics, the crude prevalence of hematuria was similar among men and women. Among nondiabetics, however, hematuria was more common among women. Diabetes and obesity were more common among women than men. In contrast, hypertension and hypercholesterolemia were more common among men than women. The ZKP is incorporating these preliminary data into planning for the development and implementation of primary and secondary prevention programs.

Adolescent↗
PubMed2000

Prophylactic nasal continuous positive airways pressure for preventing morbidity and mortality in very preterm infants.

BACKGROUND: This section is under preparation and will be included in the next issue. OBJECTIVES: To determine if prophylactic nasal continuous positive airways pressure (CPAP) commenced soon after birth regardless of respiratory status in the very preterm or very low birth weight infant reduces the use of IPPV and the incidence of chronic lung disease (CLD) without adverse effects. SEARCH STRATEGY: The standard search strategy of the Neonatal Review Group was used. This included searches of the Oxford Database of Perinatal Trials, Cochrane Controlled Trials Register, MEDLINE, previous reviews including cross references, abstracts, conferences, symposia, proceedings, expert informants, journal hand searching mainly in the English language. SELECTION CRITERIA: All trials using random or quasi-random patient allocation of very preterm infants < 32weeks gestation and / or < 1500 gms at birth were eligible. Comparison had to be between prophylactic nasal CPAP commencing soon after birth regardless of the respiratory status of the infant compared with "standard" methods of treatment where CPAP or IPPV is used for a defined respiratory condition. DATA COLLECTION AND ANALYSIS: Standard methods of the Cochrane Collaboration and its Neonatal Review Group, including independent assessment of trial quality and extraction of data by each author, were used. Data were analysed using relative risk (RR). MAIN RESULTS: There are no statistically significant differences in any of the outcomes reported in the single eligible study of 82 very low birth weight infants. More infants in the prophylactic nasal CPAP group received IPPV; however, this difference is not statistically significant. There are trends towards increases in the incidence of CLD (undefined) [RR 2.27 (0.77, 6.65)], of death [RR 3.63 (0.42, 31.08)] and of intraventricular hemorrhage [RR 2.18 (0.84, 5.62)] in the treatment group. The study also found a trend towards a reduction in the incidence of necrotizing enterocolitis in the treatment group [RR 0.40 (0.13, 1.21)]. REVIEWER'S CONCLUSIONS: There is currently insufficient information to make recommendations for clinical practice. The single study reviewed showed no strong evidence of benefit in reducing the incidence of IPPV. The tendency for some adverse outcomes to be increased is of concern and more data are needed to clarify this. A multicentre randomized controlled trial comparing prophylactic nasal CPAP with "standard" methods of treatment is needed to clarify its clinical role.

Chronic Disease↗
PubMedDate not supplied

What do family physicians believe and value in their work?

BACKGROUND: Family practice has always valued physician self-awareness. Whereas self-awareness has traditionally focused on problem relationships with patients, generally unexplored are the physicians' personal beliefs and values that strongly influence their routine clinical work and collegial relationships. Thus we know little about the nature and scope of these beliefs and values. The following study was undertaken to foster a better understanding of beliefs and values that residents bring to their clinical practice. METHODS: Applying 13 years of experience with one method of structured reflection and conversation, I was able to perform a cross-set analysis of findings from interactions with 143 family practice residents. Such dimensions as views of life and death, role of physician, and process of healing served as avenues to elicit beliefs and values. RESULTS: The residents' responses yielded the following six themes: philosophy and spirituality, the nature of suffering, the strains of helping, the healing relationship, the coherence of models, and clashes with the models of patients and colleagues. CONCLUSION: These conversations with family physicians-in-training suggest that they bring to their clinical and collaborative relationships complex, highly personal models of medicine that emphasize meaning and human relationship and serve as a source of strength. To better understand these models, future work should investigate the general beliefs and values of experienced family physicians in various practice settings, how their models of medicine interact and perhaps clash with those of their patients and colleagues, and effective methods for helping family physicians articulate their views so they can function effectively in their clinical practice.

Attitude of Health Personnel↗
PubMed2004

Risk factors for dental caries in young children: a systematic review of the literature.

OBJECTIVE: To conduct a systematic review of the literature on risk factors for dental caries in deciduous teeth of children aged six years and under, to give a scientific framework for the international collaborative studies on inequalities in childhood caries. METHOD: Accepted guidelines were followed. Studies were identified by electronic searching and reviewed on the basis of key words, title and abstract by two reviewers to assess whether inclusion criteria were met. Copies of all articles were obtained and assessed for quality according to the study design. RESULTS: 1029 papers were identified from the electronic search, 260 met the prima facie inclusion criteria. 183 were excluded once full copies of these papers were obtained. Of the 77 studies included, 43 were cross sectional, 19 cohort studies, 8 case control studies and 7 interventional studies. Few obtained the highest quality scores. 106 risk factors were significantly related to the prevalence or incidence of caries. CONCLUSION: There is a shortage of high quality studies using the optimum study design, i.e. a longitudinal study. The evidence suggests that children are most likely to develop caries if Streptococcus Muttans is acquired at an early age, although this may be partly compensated by other factors such as good oral hygiene and a non-cariogenic diet. Diet and oral hygiene may interact so that if there is a balance of 'good' habits by way of maintaining good plaque control and 'bad' habits by way of having a cariogenic diet, the development of caries may be controlled.

Child↗
PubMed2006

Multidisciplinary team working: collaboration and conflict.

The aim of this paper is to report on findings identifying some of the difficulties encountered by the multidisciplinary team in the development and implementation of a care pathway for patients diagnosed with schizophrenia. Policy direction has shifted towards greater team working and blurring of professional boundaries. Moreover, there is greater need to deliver care according to set standards and for patients to reach particular outcomes of care. Care pathways are relatively new for psychiatry and will potentially uncover tensions within the team. Data were collected by participant observation and semistructured interviews over a period of 12 months on an acute psychiatric unit. The care team developed the care pathway and the process of development and implementation was observed through action research. Cross-sectional indexing was used to analyse the data, and themes were developed using interview and observational data collection methods. Clinicians argued strongly for clear role boundaries but also defended their perceived control over health care from other professions. The findings indicate that designing a care pathway for people with schizophrenia may produce conflicting perceptions from the team. Conflict may arise through professions being unwilling to accept plurality over roles, which may hinder progress in meeting the needs of patients. The findings also counter the impression that care pathways can be implemented with little impact on the team.

Conflict, Psychological↗
PubMed1998

Organizational factors related to AIDS/HIV education in outpatient substance abuse treatment units.

The association of HIV and AIDS with intravenous drug use is well documented. Given this, substance abuse treatment providers must figure prominently in any effective national response to HIV/AIDS. The strategies employed by human service managers to address AIDS may be important in explaining how substance abuse treatment units implement policies and programs concerning AIDS-related prevention services. This paper utilizes data from the National Drug Abuse Treatment System Survey to examine how strategic activities concerning AIDS/HIV undertaken by outpatient substance abuse treatment unit managers impacted the provision of preventive AIDS-related services to clients. Results of multiple regression analysis indicate collaboration with other human service organizations and environmental scanning activities are important variables in explaining variation among substance abuse treatment units in the provision of AIDS prevention education to clients. Based on these findings, implications for future research and policy concerning AIDS prevention within the context of substance abuse treatment are made.

Acquired Immunodeficiency Syndrome↗
PubMed1992

A collaborative study of differences in the survival rates of black patients and white patients with cancer.

In 1983, the National Cancer Institute began a social-epidemiologic study of possible behavioral and biologic determinants of black/white racial disparities in cancer survival. The design, methodology, underlying hypotheses, and patient accrual of this study are discussed. Survival differences in four organ sites are investigated: cancers of the uterine corpus, breast, bladder, and colon. The first three sites were chosen because of significant observed black/white differentials in survival. Although racial disparities in survival from colon cancer are less prominent, this site was included because it is a leading cause of deaths attributable to cancer, because regional variations have been observed in black/white survival disparities, and because colon data permit cross-gender comparisons. Data collection centers for the study included the Georgia Center for Cancer Statistics, the Louisiana Tumor Registry, and the California Tumor Registry. Probability samples of patients newly diagnosed with these cancers were drawn from the areas served by these registries. Diagnostic years of eligibility were 1985 to 1986 for breast and colon cancer, and 1985 to 1987 for bladder and uterine corpus cancer. Data were collected by personal interview, medical records abstract, physician records, and pathology review. Analyses focus on seven main explanatory hypotheses.

Adult↗
PubMed1985

Collaborative WHO xylitol field studies in Hungary. IV. Saliva levels of Streptococcus mutans.

Salivary Streptococcus mutans was quantified to detect possible age-, sex-, and group-dependent differences at the end of a 3-year field study assessing the value of partial substitution of sucrose with xylitol (X group) in comparison with systemic administration of fluoride (F group) and restorative treatment solely (C group). The material of this substudy consisted of 390 institutionalized children aged 9-14 years. S. mutans was determined through the spatula technique and grouped into categories 0, less than 10(5), 10(5)-10(6), and and greater than 10(6) CFU/ml saliva. Zero to less than 10(5) values included more than 80% of the subjects of the X group. The cross-sectional comparison between groups showed lower S. mutans values in the X group than in the F and C groups. These differences between groups were highly significant. S. mutans was not dependent on age or sex.

Adolescent↗
PubMed2005

Prophylactic nasal continuous positive airways pressure for preventing morbidity and mortality in very preterm infants.

BACKGROUND: Cohort studies (Avery 1987; Jonsson 1997) have suggested that early post-natal nasal continuous positive airways pressure (CPAP) may be beneficial in reducing the need for intubation and intermittent positive pressure ventilation, and in preventing chronic lung disease in preterm or low birth weight infants. OBJECTIVES: To determine if prophylactic nasal CPAP commenced soon after birth regardless of respiratory status in the very preterm or very low birth weight infant reduces the use of IPPV and the incidence of chronic lung disease (CLD) without adverse effects. SEARCH STRATEGY: The search was updated in April 2005. The standard search strategy of the Neonatal Review Group was used. This included searches of the Oxford Database of Perinatal Trials, Cochrane Library Issue 1 2005, MEDLINE 1966-April 2005, previous reviews including cross references, abstracts, conferences, symposia, proceedings, expert informants, journal hand searching mainly in the English language. SELECTION CRITERIA: All trials using random or quasi-random patient allocation of very preterm infants < 32 weeks gestation and / or < 1500 gms at birth were eligible. Comparison had to be between prophylactic nasal CPAP commencing soon after birth regardless of the respiratory status of the infant compared with "standard" methods of treatment where CPAP or IPPV is used for a defined respiratory condition. DATA COLLECTION AND ANALYSIS: Standard methods of the Cochrane Collaboration and its Neonatal Review Group, including independent assessment of trial quality and extraction of data by each author, were used. Data were analysed using relative risk (RR). Meta-analysis was performed using a fixed effects model. MAIN RESULTS: There are no statistically significant differences in any of the outcomes studied in either of the eligible trials (Han 1987; Sandri 2004) reporting on 82 and 230 infants respectively. In Han 1987 there are trends towards increases in the incidence of BPD at 28 days [RR 2.27 (0.77, 6.65)], death [RR 3.63 (0.42, 31.08)] and any IVH [RR 2.18 (0.84, 5.62)] in the CPAP group. In Sandri 2004 there is a trend towards an increase in IVH grade 3 or 4 [RR 3.0 (0.96, 28.42)] in the CPAP group. No outcome was significantly different in any of the meta-analyses. AUTHORS' CONCLUSIONS: There is currently insufficient information to evaluate the effectiveness of prophylactic nasal CPAP in very preterm infants. Neither of the included studies reviewed showed evidence of benefit in reducing the use of IPPV. The tendency for some adverse outcomes to be increased is of concern and further multicentre randomized controlled trials are needed to clarify this.

Chronic Disease↗
PubMed2002

Language-based intervention for phonological disorders.

Children with phonological disorders often display difficulty in other domains of language. Language-based approaches focus on all aspects of language; therefore, little attention may be drawn to sound errors and these may not be specific targets of intervention. These approaches involve a variety of naturalistic, conversationally based techniques such as focused stimulation in the form of expansions and recasts, scaffolding narratives, and elicited production devices such as forced choice questions, cloze tasks, and preparatory sets. Results from well-controlled group studies are inconclusive regarding the cross-domain effects of morphosyntax approaches on phonology. There are, however, individual children whose phonology improves with a language-based approach. Preliminary evidence suggests that such an approach may be an appropriate choice for children with both speech and language impairments whose phonological systems are highly inconsistent. One advantage of a language-based approach is that it may lead to simultaneous improvements in both speech and language for children with difficulty in both these domains. It is also a viable option when service delivery dictates classroom and collaborative settings. When a language-based approach is chosen for children with phonological disorders, it is imperative that the practitioner monitor phonological progress closely to ensure its effectiveness.

Child↗
PubMed2005

Social environments and the genetics of aging: advancing knowledge of protective health mechanisms.

We selectively review the literature in behavioral and molecular genetics, including both laboratory and epidemiologic studies, with emphasis on how social environments, particularly emotion in significant social relationships, influence gene expression. Attention is given to cross-talk between human and animal studies. Environments are pivotal in understanding phenotypic outcomes, and this demands research on gene-environment interactions. Illustrative interactions, involving both behavioral and molecular genetics, are provided. Many people with susceptibility genes for diverse diseases never proceed to disease status. Substantial associational evidence implicates social environmental factors as protective agents. Mechanistic understanding of these linkages is quite advanced in some animal populations and suggests new lines of inquiry in human studies. Developing the interface between genetics, social environments, and health will require close collaboration between those well versed in molecular biology and biochemistry and persons with expertise in genetic epidemiology and social psychology. Particularly important is the identification of environmental influences that protect susceptible persons from disease incidence.

Aged↗
PubMed2005

Overview of epidemiology of bile duct and gallbladder cancer focusing on the JACC Study.

BACKGROUND: This review discusses the epidemiologic features of bile duct and gallbladder cancer in Japan, mainly focusing on results of Japan Collaborative Cohort Study (JACC Study) for Evaluation of Cancer Risk Sponsored by the Ministry of Education, Science, Sports and Culture of Japan (Monbusho) in comparison with results of other studies. METHODS: The theses and papers derived from JACC Study on bile duct and gallbladder cancer were all collected for this review. Hirayama's cohort study, which is a representative epidemiologic study, and a large scale case-control study on bile duct and gallbladder cancer in Japan by Kato et al. were also taken into consideration. Small scale cross-sectional studies or ecological studies and the studies conducted outside Japan were collected by the literature reference services on the web net such as Pub Med or Japan Centra Revuo Medicina (Igaku- Chuo- Zasshi) limited to the published after 1980 and use key words bile duct cancer, gallbladder cancer and epidemiology. RESULTS: In the JACC Study, high intake of fried food was regarded as a factor that significantly elevated the risk of the diseases (hazard ratio [HR]=2.58, 95% confidence interval [CI]: 1.08-6.16 in males; HR=2.98, 95% CI: 1.28-6.86 in females). The JACC Study indicated that a high intake of boiled beans had a significant preventive relation to the diseases in females (relative risk [RR]=0.50, 95% CI: 0.26-0.98). High consumption of fish also had a significant preventive relationship to bile duct cancer in males (RR=0.53, 95% CI: 0.26-0.98) and gallbladder cancer in females (RR=0.43, 95% CI: 0.24- 0.79). A history of blood transfusion also had a significant relationship (HR=2.27, 95% CI: 1.29-3.98) as which elevated the risk. The JACC Study determined bowel movement as a risk factor. The group with bowel movements less than once per six days had a significantly elevated hazard ratio (HR=5.21, 95% CI: 1.25-21.68). CONCLUSION: As to recent epidemiologic features of bile duct and gallbladder cancer revealed by the JACC Study, its outline became obvious in comparison with the results of other studies. Evidence for the contribution of the JACC Study is strong because it provides some important findings on the epidemiology of bile duct and gallbladder cancer.

Adult↗
PubMed1990

Relationship between attitudes, behaviour and levels of dental caries among 15-year-old Saudi Arabian and Irish children.

In 1987, the first major dental epidemiological study was carried out in the Kingdom of Saudi Arabia, with the help and cooperation of the WHO Collaborating Centre for Oral Health Services Research, University Dental School, Cork, Ireland. As part of the project, the 15-year-old age group underwent an interview survey in order to ascertain if oral health attitudes and behaviour were related to oral health outcomes, as measured by the mean DMFT for the group. In common with the findings of similar studies in other countries, including Ireland, little or no correlation between the sociological variables and oral health outcomes was apparent. Such findings, however, simply highlight the unreliability of cross-sectional designs when attempting to isolate a relationship between a cumulative condition, such as dental caries, and parameters which clearly change with time. The differences found in the oral health behaviour of the Saudi Arabian and Irish 15-year-old children is particularly noticeable in respect of the frequency of intake of sweet foods and drinks.

Adolescent↗
PubMed1998

Molecular genetic studies in lymphocyte apoptosis and human autoimmunity.

Using a genetic approach, we have studied the molecular basis of human autoimmunity with special emphasis on a disease that is due to defective lymphocyte apoptosis. Recently, we and our collaborators have found that the autoimmune/lymphoproliferative syndrome (ALPS), an inherited disease of children comprising marked lymphoid hyperplasia and autoimmune manifestations, is due to abnormalities in the CD95 gene that cause defective lymphocyte apoptosis. Our recent investigations have shown that the mutations in most families with ALPS cause either global or local changes in the structure of a cytoplasmic portion of the molecule called the 'death domain'. These death domain alterations impair binding of the adapter protein FADD/MORT1 and result in a failure to activate apoptotic caspases after CD95 (Fas/APO-1) cross-linking. Mutations in apoptotic caspases may also contribute to the pathogenesis of ALPS in individuals that have no CD95 gene mutations.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Morphological and topographic effects on calcification tendency of pHEMA hydrogels.

Poly(2-hydroxyethyl methacrylate) hydrogels were prepared in the presence of varying concentrations of water, or a co-monomer ethoxyethyl methacrylate at different strengths of crosslinking agent ethylene glycol dimethacrylate. Calcification tendency and its correlation with monomer mixture composition, topography and porosity of these materials were investigated. Scanning (SEM) and transmission electron microscopy (TEM) was used to study topography and porosity respectively. Calcification and calcium diffusion ability in to the hydrogels were investigated by light microscopy, SEM and energy dispersive analysis of X-rays (EDAX) after incubation of the materials in a metastable calcifying solution for 48 days. Polymer and solvent volume fractions were also studied to determine if a correlation existed between porosity and calcification. Most of the series of hydrogels showed surface irregularities. Internal structure showed evidence of a porous structure in one of the series. Calcification studies indicated diffusion of calcium ions in some of the series. The diffusion of calcium is limited to 30-40 microm in most calcified specimens. For hydrogels that exhibited substantial surface irregularities and micro channels, the infiltration of calcium up to 200 microm was observed. Attempts to detect porosity by electron microscopy failed in some of the hydrogels due to difficulty in sample processing and sectioning. However, collaboration of the results with different techniques used, indicated that surface defects are the major contributors to calcium deposition. Decrease in porosity reduces the amount of calcium deposits and infiltration with decreasing solvent volume fraction which is associated with crosslinking concentration and initial water content of the polymer.

Biocompatible Materials↗