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Biomedical subjects

C L Murphy

Publications and source records attributed to C L Murphy.

At least 19 recordsLinked to original sources
PubMed2006

Topographical variation in glycosaminoglycan content in human articular cartilage.

The weight-bearing status of articular cartilage has been shown to affect its biochemical composition. We have investigated the topographical variation of sulphated glycosaminoglycan (GAG) relative to the DNA content of the chondrocyte in human distal femoral articular cartilage. Paired specimens of distal femoral articular cartilage, from weight-bearing and non-weight-bearing regions, were obtained from 13 patients undergoing above-knee amputation. After papain enzyme digestion, spectrophotometric GAG and fluorometric DNA assays assessed the biochemical composition of the samples. The results were analysed using a paired t-test. Although there were no significant differences in cell density between the regions, the weight-bearing areas showed a significantly higher concentration of GAG relative to DNA when compared with non-weight-bearing areas (p = 0.02). We conclude that chondrocytes are sensitive to their mechanical environment, and that local loading conditions influence the metabolism of the cells and hence the biochemical structure of the tissue.

Adolescent↗
PubMed2005

Systemic AA amyloidosis in the common marmoset.

The common marmoset (Callithrix jacchus) is a small New World primate native to Brazil that has been used extensively in biomedical research. A retrospective analysis of archived hematoxylin and eosin-stained tissue sections and clinical records was conducted at the New England Primate Research Center on 86 marmosets more than 1 year of age that were euthanized during the past decade because of morbidity and failure to thrive. Approximately 17% (15 of 86) were found to have amyloid deposits in one or more organs, including the liver, adrenal glands, kidneys, and intestine. This material was shown by amino acid sequence analysis to be composed of serum amyloid A (SAA)-related protein. This type of amyloidosis, designated AA or "secondary," is associated typically with an inflammatory process that induces elevated levels of the SAA amyloidogenic precursor molecule. Notably, there were no significant pathologic differences or other distinguishing features in animals with amyloid versus those without; furthermore, on the basis of the limited number of serum specimens available for analysis, the SAA concentrations in the two groups were comparable, thus suggesting the possible inheritable nature of the disorder. In this respect, the common marmoset provides a unique experimental model for study of the pathogenesis and treatment of AA and other forms of systemic amyloidosis.

Amino Acid Sequence↗
PubMed2003

Pathology of AA amyloidosis in domestic sheep and goats.

We describe the main pathologic changes in small ruminants affected by AA amyloidosis, together with the partial sequence of the protein involved. Twenty-one sheep and one goat were selected for presenting macroscopic kidney lesions compatible with systemic amyloidosis. Available tissue samples were studied by histologic, immunopathologic, and ultrastructural means. Renal lesions were characterized grossly by pale cortical surfaces with scattered, miliary, whitish-yellow foci and on cut cortical surfaces by straight, whitish-yellow striations. Gangrenous pneumonia was observed in 16 out of 21 affected sheep (76.2%), although other chronic inflammations were also observed. Amyloid was detected in all grossly affected kidneys using Congo red staining, lesions being most remarkable in glomeruli, affecting 95.5% of animals studied. Congophilic deposits were also observed in intertubular interstitium (68.2%) and medulla (57.1%). All amyloid-affected animals presented proximal convoluted tubule lesions, mostly characterized by an increase in diameter and by hyaline granular degeneration that were responsible for the macroscopic appearance of the kidney. Histologically, amyloid was also seen in blood vessels, spleen, liver, lymph nodes, gastrointestinal tract, and adrenal glands. All amyloid deposits demonstrated greenish-yellow birefringence with polarized light, and the antisera prepared against goat amyloid extracts specifically reacted with birefringent congophilic deposits of both sheep and goats. Ultrastructurally, these deposits were formed by masses of straight, nonbranching fibrils located predominantly in the basement membranes of glomerular capillaries and in the mesangium. Partial sequence of the protein in sheep and goats indicated a high degree of homology with the previously reported sequence of sheep Serum Amyloid A.

Amino Acid Sequence↗
PubMed2001

A placebo-controlled trial to evaluate immunomodulatory effects of paricalcitol.

Calcitriol has shown a benefit in various small uncontrolled studies of ex vivo immune function. We hypothesized that paricalcitol, a new vitamin D derivative, will have a positive effect on the immune system with minimal adverse effects on calcium homeostasis. Thirty-one hemodialysis patients not administered vitamin D because of low intact parathyroid hormone (PTH) levels were randomized to placebo or 4 microg of paricalcitol intravenously with the hemodialysis session three times weekly for 12 weeks. Effects on in vivo and ex vivo assessments of immune function were evaluated. All patients achieved the target dose of paricalcitol. Twenty patients were anergic at the start of the study; 4 of 11 patients in the paricalcitol group and 0 of 9 patients in the placebo group converted to reactive (P = 0.09). The in vivo response to standard hepatitis B booster vaccine and in vitro proliferation and release of interleukin-2 (IL-2), IL-6, tumor necrosis factor-alpha, and interferon-gamma from stimulated lymphocytes were not different between the groups. In contrast to clinical immune effects, paricalcitol increased serum calcium levels and decreased PTH and bone alkaline phosphatase levels (all P < 0.05). However, hypercalcemia was infrequent. In vitro experiments showed that paricalcitol led to greater dose-dependent thymidine uptake than calcitriol in lymphocytes isolated from either dialysis patients or control subjects. Paricalcitol has a tendency toward improving delayed hypersensitivity reactions, but did not have other proimmune effects. However, as expected, paricalcitol had significant effects on calcium homeostasis compared with placebo. Thus, patients with low PTH levels are unlikely to experience the proimmune effects of vitamin D therapy without more profound and potentially adverse oversuppression of PTH.

Adult↗
PubMed2001

Variation in administrators' and clinicians' attitudes toward critical elements of an infection control program and the role of the infection control practitioner in New South Wales, Australia.

BACKGROUND: Debate remains over the core activities of infection control (IC) programs. Differences in stakeholder opinions must be considered if consensus panel guidelines and recommendations are to be broadly applied. This article describes a survey of administrators and clinicians employed in hospitals in New South Wales, Australia. Respondents self-reported their levels of agreement with affirmative statements regarding the role of the infection control practitioner (ICP) and the essential requirements and infrastructure of IC programs. METHOD: The study population included administrators and clinicians in each public, private, and freestanding day hospital in New South Wales. Respondents reported the intensity of their agreement with 16 affirmative statements relating to IC program infrastructure and resources and the ICP's role and responsibilities. RESULTS: The overall response rate was 62.1% (587/945). Clinicians (349/587) and administrators (238/587) accounted for 59.5% and 40.5% of the response rate, respectively. Overall, administrators and clinicians reported greatest levels of agreement for those elements not requiring additional resources. CONCLUSION: The extent of divergence between administrators and clinicians is not so great that it can not be resolved. Our findings demonstrate the degree of administrator support that clinicians can expect for each element. We advocate better communication between clinicians and administrators in conjunction with objective strategic planning. Our findings provide a guide for ICPs to either establish or negotiate the core components of their IC program.

Attitude of Health Personnel↗
PubMed2001

Effect of oxygen tension and alginate encapsulation on restoration of the differentiated phenotype of passaged chondrocytes.

The implantation of laboratory-grown tissue offers a valuable alternative approach to the treatment of cartilage defects. Procuring sufficient cell numbers for such tissue-engineered cartilage is a major problem since amplification of chondrocytes in culture typically leads to loss of normal cell phenotype yielding cartilage of inferior quality. In an effort to overcome this problem, we endeavored to regain the differentiated phenotype of chondrocytes after extensive proliferation in monolayer culture by modulating cell morphology and oxygen tension towards the in vivo state. Passaged cells were encapsulated in alginate hydrogel in an effort to regain the more rounded shape characteristic of differentiated chondrocytes. These cultures were exposed to reduced (5%-i.e., physiological), or control (20%) oxygen tensions. Both alginate encapsulation and reduced oxygen tension significantly upregulated collagen II and aggrecan core protein expression (differentiation markers). In fact, after 4 weeks in alginate at 5% oxygen, differentiated gene expression was comparable to primary chondrocytes. Collagen I expression (dedifferentiation marker) decreased dramatically after alginate entrapment, while reduced oxygen tension had no effect. It is concluded that alginate encapsulation and reduced oxygen tension help restore key differentiated phenotypic markers of passaged chondrocytes. These findings have important implications for cartilage tissue engineering, since they enable the increase in differentiated cell numbers needed for the in vitro development of functional cartilaginous tissue suitable for implantation.

Alginates↗
PubMed2001

Chemical typing of amyloid protein contained in formalin-fixed paraffin-embedded biopsy specimens.

The human amyloidoses represent a heterogeneous group of disorders characterized by the deposition of fibrillar protein in vital organs. Given the fact that at least 20 different molecules can form fibrils, the unambiguous identification of the type of amyloid deposited is critical to the correct diagnosis and treatment of patients with these disorders. Heretofore, this information has been inferred from particular clinical features of the disease, ancillary laboratory tests, and results of immunohistochemical analyses. However, to establish unequivocally the kind of protein that is deposited as amyloid, it is necessary to determine its chemical composition through amino acid sequencing or mass spectroscopy of material extracted from fibrillar deposits. We have developed a micromethod whereby such studies can be performed readily using sections of formalin-fixed, paraffin-embedded biopsy specimens. The ability to identify precisely the nature of the tissue deposits has diagnostic, therapeutic, and prognostic implications for patients with amyloid-associated disorders.

Amino Acid Sequence↗
PubMed2001

Effect of oxygen tension on chondrocyte extracellular matrix accumulation.

Since cartilage is mainly an avascular tissue, chondrocytes exist in a low-level oxygen environment in vivo. In the present study, we investigated the effect of oxygen tension (20%, 5% and 1% gas phase oxygen concentrations) over a 20-day period on the extracellular matrix accumulation of bovine articular chondrocytes in confluent surface cultures. Matrix accumulation was assessed by the amount of glycosaminoglycan and collagen deposited in the matrix. From initially confluent monolayers, the chondrocytes became distributed throughout a thick layer of extracellular matrix, thus forming a multicell-layer of tissue. Cells maintained their normal rounded shape, indicative of the differentiated phenotype, throughout the 20-day culture period. On a per culture and a per cell basis, the amount of collagen and glycosaminoglycan accumulation in the matrix was lower at the reduced oxygen tensions. Specifically, in 1% oxygen, matrix GAG content reached a steady-state level, with no net increase in GAG levels after two weeks, whereas in 20% oxygen, matrix GAG increased with time. It is concluded that oxygen has a significant effect on the amount of macromolecules accumulated in the extracellular matrix. The implications of these findings in growing cartilage constructs in vitro are discussed.

Animals↗
PubMed2001

Micro-method to isolate and purify amyloid proteins for chemical characterization.

The amyloidoses represent a heterogeneous group of disorders characterized by the pathologic deposition as fibrils of at least 20 different precursor molecules. To establish definitively the specific type of amyloid protein contained in fibrillar deposits, such material must be extracted, purified, and subjected to amino acid sequence analysis. Heretofore, the chemical identification of amyloid components has required gram quantities of tissue. Given the often-limited amounts of sample available, e.g., that derived from diagnostic needle biopsies, we have developed a micro-method to isolate and purify amyloid from minute tissue specimens. The procedure involves micro-extraction of the amyloid with subsequent purification by SDS-PAGE, electroblotting onto PVDF membranes, excision and elution of amyloid protein-related bands, and reversed phase HPLC. Chemical and immunologic studies of isolated amyloid components have demonstrated the purity achieved with this technique and have provided information on the molecular mass, heterogeneity, and immunoreactivity of the amyloid. Further, using this methodology, it has been possible to obtain sufficient material for amino acid sequencing and thus to establish unequivocally the chemical and molecular composition of the fibrillar deposits. Our microtechnique has clinical import and also is applicable to analyses of the amyloid found in experimental small animal models of these disorders.

Amino Acid Sequence↗
PubMed2000

Antibody-mediated resolution of light chain-associated amyloid deposits.

Primary light-chain-associated (AL) amyloidosis is characterized by the deposition in tissue of monoclonal light chains as fibrils. With rare exception, this process is seemingly irreversible and results in progressive organ dysfunction and eventually death. To determine whether immune factors can effect amyloid removal, we developed an experimental model in which mice were injected with amyloid proteins extracted from the spleens or livers of patients with AL amyloidosis. Notably, the resultant amyloidomas were rapidly resolved, as compared to controls, when animals received injections of an anti-light-chain monoclonal antibody having specificity for an amyloid-related epitope. The reactivity of this monoclonal antibody was not dependent on the V(L) or C(L) isotype of the fibril, but rather seemed to be directed toward a beta-pleated sheet conformational epitope expressed by AL and other amyloid proteins. The amyloidolytic response was associated with a pronounced infiltration of the amyloidoma with neutrophils and putatively involved opsonization of fibrils by the antibody, leading to cellular activation and release of proteolytic factors. The demonstration that AL amyloid resolution can be induced by passive administration of an amyloid-reactive antibody has potential clinical benefit in the treatment of patients with primary amyloidosis and other acquired or inherited amyloid-associated disorders.

Amyloid↗
PubMed2000

Australian Infection Control Association members' use of skills and resources that promote evidence-based infection control.

BACKGROUND: To adopt an evidence-based approach, professionals must be able to access, identify, interpret, and critically appraise best evidence. Critical appraisal requires essential skills, such as computer literacy and an understanding of research principles. These skills also are required for professionals to contribute to evidence. METHODS: In 1996, members of the Australian Infection Control Association were surveyed to establish a profile including the extent to which they were reading infection control publications, using specific documents for policy and guideline development, developing and undertaking research, publishing research, and using computers. The relationships between demographics, computer use, and research activity were examined. RESULTS: The response rate was 63. 4% (630/993). The study group comprised mostly women (96.1%), and most (66.4%) were older than 40 years of age. Median infection control experience was 4 years (mean, 5.4 years; range, <12 months to 35 years). When developing guidelines and policies (92.7%; 584/630), infection control professionals reviewed State Health Department Infection Control Guidelines and Regulations. Research relating to infection control was undertaken by 21.5% (135/628) of the sample, and 27.6% (37/134) of this group published their research findings. Of the respondents (51.1%; 318/622) who used a computer to undertake infection control tasks, the majority (89.0%) used a personal computer for word processing. CONCLUSION: Regardless of infection control experience, Australian infection control professionals must be adequately prepared to contribute to, access, appraise, and where appropriate, apply best evidence to their practice. We suggest that computer literacy, an understanding of research principles, and familiarity with infection control literature are three essential skills that infection control professionals must possess and regularly exercise.

Adult↗
PubMed1999

Transgenic mouse model of AA amyloidosis.

AA amyloidosis can be induced in mice experimentally through injection of certain chemical or biological compounds. However, the usefulness of this approach is limited by its dependence on exogenous inflammatory agents that stimulate cytokines to increase the synthesis of precursor serum amyloid A (SAA) protein and the transitory nature of the pathological fibrillar deposits. We now report that transgenic mice carrying the human interleukin 6 gene under the control of the metallothionein-I promoter had markedly increased concentrations of SAA and developed amyloid in the spleen, liver, and kidneys by 3 months of age. At the time of death about 6 months later, organs obtained from these animals had extensive amyloid deposits. This disease process was apparent radiographically using small-animal computer axial tomography and magnetic resonance imaging equipment. The AA nature of the amyloid was evidenced immunohistochemically and was unequivocally established by sequence analysis of protein extracted from the fibrils. The availability of this unique in vivo experimental model of AA amyloidosis provides the means to assess the therapeutic efficacy of agents designed to reduce or prevent the fibrillar deposits found in AA and other types of amyloid-associated disease.

Amino Acid Sequence↗
PubMed1999

Microextraction and purification techniques applicable to chemical characterization of amyloid proteins in minute amounts of tissue.

This article described micromethods useful for the extraction, purification, and amino acid sequencing of amyloid proteins contained in minute specimens obtained from patients with systemic forms of amyloidosis. We posit that these procedures can also be applied to the biochemical characterization of cerebral amyloid deposits. The selection of the techniques is dependent on the type of sample to be extracted (fresh or formalin fixed) as well as the amount of congophilic material present. Although amyloid proteins are isolated and purified more easily from fresh tissue, it must be noted that formalin-fixed specimens are available more readily for analysis due to the common diagnostic use of fine needle tissue biopsies and are therefore, important for both current and retrospective studies. Remarkably, despite the expected difficulties associated with formalin treatment we were able to extract and sequence amyloid proteins from fixed tissues presumably due to the resistance of amyloid to formalin cross-linking. Through the continued development of techniques for small-scale protein separation and application of highly sensitive microsequencing and mass spectral methods, exact identification of the protein contained in fibrillar amyloid deposits can be determined. Such information has therapeutic and prognostic relevance and can increase our understanding of the pathogenesis of amyloidosis.

Alzheimer Disease↗
PubMed1999

In vitro immunoglobulin light chain fibrillogenesis.

These techniques permit the production of bulk quantities of fibrils and provide methods for monitoring the kinetics of fibrillogenesis. Experiments performed in the fluorimeter require low protein concentrations, sampling is not necessary (with ThT in situ), and the measured fluorescence signal is indicative of fibril content and is not complicated by the presence of amorphous aggregates. However, ASF using the orbital shaker is a simple, rapid, initial procedure, adequate for screening for fibrillogenic potential, in which multiple experiments can be performed simultaneously and over long periods of incubation. These methods may be used to investigate the fibrillogenesis of VL proteins and BJps as a means of predicting pathogenicity, as well as providing information on the basic biophysical principles underlying light chain aggregation.

Amino Acid Sequence↗
PubMed1999

Methodologies used in surveillance of surgical wound infections and bacteremia in Australian hospitals.

BACKGROUND: The prevalence of nosocomial infection in Australian hospitals is estimated to be between 5.5% and 6.3%. Since 1989, infection control professionals (ICPs) in hospitals accredited by the Australian Council on Health Care Standards (ACHS) have been encouraged to collect nosocomial infection data according to ACHS methodology. METHOD: In 1996, we surveyed members of the Australian Infection Control Association to examine the time spent on surveillance, the practice of surveillance of all hospital infections (hospital-wide surveillance), case-finding methods, case definitions, and reporting routinely used by ICPs in acute care hospitals. We also examined the ICPs' education and experience in infection control (IC). RESULTS: The survey was completed and returned by 65% (644 of 993) of Australian Infection Control Association members. Of the ICPs who completed the survey, 47.8% (308 of 644; 95% CI, 43.9%-51.7%) met the criteria for inclusion, because they coordinated an IC program in an acute care or surgical hospital and performed surveillance for either surgical wound infection, intravascular device-related bacteremia, or non-device-related bacteremia. Of the ICPs who reported their facility's accreditation status, 93.5% participated in ACHS system. Most (97.6%) ICPs had completed hospital-based general registered nurse training. Only 1.9% (6 of 308) of ICPs reported completion of continuing education relating to hospital epidemiology. The number of years of IC experience ranged from zero to 35 years, with a median of 4 years. ICPs spent a substantial proportion of their total weekly IC time on surveillance irrespective of ACHS accreditation; 19.5 hours in ACHS hospitals and 15.6 hours in non-ACHS hospitals (P =.33). More than three quarters (76.0%) of ICPs performed hospital-wide surveillance. The case-finding methods, definitions of infections, and reporting formats varied greatly. The definition most commonly applied by ICPs (6.8%; 95% CI, 4.1%-10.4%) to define surgical wound infection was infection within 30 days after the operative procedure, plus purulent drainage, plus isolation of organisms from a culture from the incision site, plus diagnosis by a medical officer. A 5-item definition of a patient being asymptomatic, plus afebrile on admission, plus infection occurring at least 48 hours after admission, plus the patient having a fever of >38 degrees C, plus a recognized culture from one or more bottles was used by 15.7% (95% CI, 11.3%-21.0%) of ICPs to define a case of bacteremia. CONCLUSION: Surveillance is the core business of Australian ICPs and consumes a substantial proportion of their time. The importance of surveillance, the epidemiologic limitations of the current ACHS system, and the nonstandard methods we report indicate that improved methodology is required for case finding and reporting of nosocomial infections. Australian ICPs should complete training in the principles of surveillance and epidemiology. With this training, ICPs can work collaboratively with other health care professionals to develop epidemiologically sound, local, nosocomial surveillance systems and lobby for a voluntary, national, standardized, risk-adjusted system of targeted nosocomial surveillance.

Australia↗
PubMed1999

Who coordinates infection control programs in Australia?

BACKGROUND: Australian infection control practitioners (ICPs) have not been previously profiled. Knowledge of their practice is limited, making support and evaluation of their programs difficult. To investigate the current role, function, and attributes of this group, we undertook a national survey of members of the Australian Infection Control Association. METHODS: In 1996 a questionnaire was sent to all 1078 nonmedical and nonindustry members of the Australian Infection Control Association. More than half (65%) of the membership responded to the questionnaire, which measured demographics, experience, infection control training and education, staffing levels, perceived deficits, and managerial support. RESULTS: Our results indicate that the typical Australian ICP works in a public acute-care facility with fewer than 251 beds, has 6 years experience in the field, and has completed hospital-based nursing training. Surveillance was the activity that consumed most of the ICPs' time. The majority of ICPs had responsibilities in addition to infection control, and although they considered management to be supportive, additional clerical support was identified as an area for program improvement. CONCLUSIONS: We have provided the first comprehensive profile of Australian ICPs and their practices. Our findings compel professional associations, such as the Australian Infection Control Association, to address the following: standardization in practice and surveillance, provision of appropriate training and ongoing education, and encouragement of research initiatives by infection control staff. These strategies are the key to future evidence-based infection control and will ensure survival of this specialty in Australia.

Adult↗
PubMed1999

Credentialing, diversity, and professional recognition-foundations for an Australian infection control career path.

BACKGROUND: There are no regulatory, legislative, or professional criteria stipulating minimum qualifications or experience that a health care worker must meet to be capable of coordinating an Australian infection control (IC) program. Measurement of IC competence is important to protect the public and for the ongoing credibility and growth of the profession. METHOD: Our study group was all 1078 nonmedical and nonindustry members of the Australian Infection Control Association in 1996. The survey examined perceived level of proficiency, level of education, and experience in health care and infection control. Almost three quarters (65%) of the members responded, and almost all (85%) of these respondents fulfilled the inclusion criterion of coordinating an IC program. RESULTS: Experience in IC ranged from less than 2 years (33.6%) to more than 20 years (10.0%). The majority (65.0%) of infection control professionals (ICPs) had between 8 years and 12 years IC experience. The respective proportions of respondents' self-ranked levels of proficiency on a 5-point scale were novice (3.6%), advanced beginner (21.2%), competent (33.8%), proficient (34.7%), and expert (6.8%). Almost half (47%) of the novices agreed that a registered nursing (RN) qualification was required, whereas a majority (41%) of advanced beginners considered both an RN and a basic IC course (BASIC) were required. Competent ICPs agreed less often than the other levels about their requirements. However, 27% of competents identified a BASIC and an undergraduate degree (UG) as the minimum requirements for a competent ICP. Proficient ICPs agreed that they required an RN, UG, BASIC, and a postbasic course in IC. Nearly all experts (80.0%) agreed that they required an RN, UG, BASIC, postbasic course, and a course in hospital epidemiology (EP). Two thirds of experts expected a master's degree as a requirement. CONCLUSION: The Australian IC profession is in an exciting period of development; however, the variation in ICP perception of the most appropriate qualifications and experience threatens the credibility and viability of the profession. This variation indicates the need for a clear-cut pathway that includes a system of credentialing, recognition of expertise, adoption of divergent roles, and improved networking. This pathway will lead to an increasingly credible and viable IC profession in Australia. Developing IC communities globally can benefit from the Australian experience.

Australia↗