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Biomedical subjects

M Haas

Publications and source records attributed to M Haas.

At least 37 records · Page 2Linked to original sources
PubMed2003

The effect of three different periodontal pre-treatment procedures on the success of telescopic removable partial dentures.

In this prospective study, 120 teeth consisting of maxillary and mandibular canines and premolars were divided into three groups each containing 40 teeth. The teeth were assigned randomly in quadrants to three different periodontal treatment protocols. The first group was treated with professional prophylaxis only. The second group received additional deep scaling. With the third group, additional surgical periodontal flap surgery and scaling was performed. Both papillary bleeding index (PBI) and probing depth (PD) were evaluated before, during and after treatment. During the subsequent prosthetic treatment phase all teeth were then used as telescope abutments supporting a removable prosthesis. The documentation of the attachment level (AL) was then used as a clinical parameter. One year after the incorporation of telescopic removable partial dentures (RPDs), PD, PBI and AL were again evaluated. The resulting periodontal parameters were compared between the different groups using the general linear model (GLM) repeated measures and the Kruskal-Wallis test for non-parametric variables. Differences within the three treatment groups were determined using the t-test, e.g. the Wilcoxon test for dependent variables (P < 0.05). A significant decrease in inflammatory indices (PBI) was found for all types of periodontal treatment (P < 0.03 for all groups). Additionally, the reduction in PD was significant for all of the three groups (P < 0.001 for all groups). The greatest reduction in PD was observed in the group in which a surgical approach was used. Evaluation of the attachment level after the incorporation of the telescopic RPDs showed that tooth position did not influence the periodontal prognosis and that the use of telescopic RPDs exerted no ascertainable negative influence on the periodontium of the abutment teeth.

Adult↗
PubMed2003

Functional quality of molar crown occlusal surfaces in the different design modes of Cerec 2.

The goal of the present study was to objectify whether the design modes of "Correlation", "Function", and "Extrapolation" of the Cerec 2 system are suitable for generating a functionally perfect occlusal surface of a first mandibular molar crown. For this purpose, an occlusal surface was waxed up according to the biomechanical concept of MH Polz, and this served as the reference occlusal surface. Four different Cerec 2 comparison crowns (produced in the laboratory, Extrapolation mode, Correlation mode, Function mode) were produced and the positions of the cusps were measured. It was shown that the Correlation mode delivers the most accurate results, and the manually produced occlusal surface also showed good results. The occlusal surfaces of the crowns produced according to the Extrapolation and Function mode were clearly inferior.

Ceramics↗
PubMed2002

Dynamic structural disorder of the FeO2 moiety in oxymyoglobin studied by nuclear resonant forward scattering of synchrotron radiation.

Oxy- as well as deoxymyoglobin exhibit a pronounced temperature dependence of the quadrupole splitting of the heme iron as detected by conventional Mössbauer spectroscopy. With nuclear resonant forward scattering (NFS) of synchrotron radiation, which can be viewed as Mössbauer spectroscopy in the time domain, it is shown that this spectroscopic behavior, although it is phenomenologically similar in the two cases, is based on completely different physical mechanisms. It is demonstrated that stochastic fluctuations of the iron electric field gradient in MbO(2), which are due to the dynamic structural disorder of the FeO(2) moiety, are the reason for the temperature-dependent alterations of the coherent quantum beat pattern in the NFS spectra of MbO(2), in contrast to deoxyMb where transitions between orbital states of iron take place. This subtle spectroscopic difference cannot be inferred from conventional Mössbauer spectroscopy.

Electrochemistry↗
PubMed2002

The LDH ratio as a marker for response to plasma exchange in HUS/TTP of the adult.

BACKGROUND: Plasma exchange improved the outcome of thrombotic thrombocytopenic purpura (TTP)/hemolytic uremic syndrome (HUS) of the adult markedly, but a high number of non-responders remain. Identifying these patients at an early stage would help to optimize therapy. AIM: determine the value of serologic measures in predicting the response to plasma exchange. MATERIAL AND METHODS: We performed a retrospective chart review of 30 patients with HUS/TTP of the adult treated with plasma exchange. According to the treatment protocol, a mean of 42 +/- 8.2 ml plasma per kilogram of body weight was exchanged daily for 3 days and continued every second day thereafter. Prior to each session, clinical status and serologic markers for hemolysis and kidney function were obtained. To assess the early individual response to plasma exchange, the decline of LDH from the first to the third cycle was calculated as: LDH concentration before the third session/LDH concentration before the first session (LDH ratio). RESULTS: During the observation period (median 195, range 6-1500 days), 80% of the patients responded to therapy with plasmapheresis. None of the serologic measures or clinical signs obtained before initiation of plasma exchange showed a significant correlation with the outcome. After 2 sessions of plasma exchange, only LDH and platelet level had improved markedly in responding patients. The LDH ratio was the best predictive marker for the individual response. An LDH ratio < 0.6 predicted a favorable outcome with a sensitivity of 0.96 and a specificity of 0.83. CONCLUSION: The LDH ratio might be a useful marker for separating patients responding to plasma exchange from those not responding at an early stage.

Adult↗
PubMed2001

Strongly linked current flow in polycrystalline forms of the superconductor MgB2.

The discovery of superconductivity at 39 K in magnesium diboride, MgB2, raises many issues, a critical one being whether this material resembles a high-temperature copper oxide superconductor or a low-temperature metallic superconductor in terms of its behaviour in strong magnetic fields. Although the copper oxides exhibit very high transition temperatures, their in-field performance is compromized by their large anisotropy, the result of which is to restrict high bulk current densities to a region much less than the full magnetic-field-temperature (H-T) space over which superconductivity is found. Moreover, the weak coupling across grain boundaries makes transport current densities in untextured polycrystalline samples low and strongly sensitive to magnetic field. Here we report that, despite the multiphase, untextured, microscale, subdivided nature of our MgB2 samples, supercurrents flow throughout the material without exhibiting strong sensitivity to weak magnetic fields. Our combined magnetization, magneto-optical, microscopy and X-ray investigations show that the supercurrent density is mostly determined by flux pinning, rather than by the grain boundary connectivity. Our results therefore suggest that this new superconductor class is not compromized by weak-link problems, a conclusion of significance for practical applications if higher temperature analogues of this compound can be discovered.

Journal Article↗
PubMed2001

A distinctive pediatric renal neoplasm characterized by epithelioid morphology, basement membrane production, focal HMB45 immunoreactivity, and t(6;11)(p21.1;q12) chromosome translocation.

We report two cases of a hitherto undescribed pediatric renal neoplasm that is distinctive at the morphological, immunohistochemical, ultrastructural, and cytogenetic levels. On light microscopy, the tumors are composed of nests of polygonal, clear to eosinophilic cells associated with a subpopulation of smaller cells that surround hyaline material. Despite their epithelioid morphology, these tumors do not label immunohistochemically for epithelial markers but instead label focally for melanocytic markers HMB45 and Melan A. The hyaline material is positive with periodic acid-Schiff and methenamine-silver histochemical stains, and labels immunohistochemically for type 4 collagen. Ultrastructural examination confirms that it represents basement membrane material. Cytogenetic analysis reveals the identical t(6;11)(p21.1;q12) chromosome translocation as the sole abnormality in these two tumors, confirming their identity and distinctive nature.

Adolescent↗
PubMed2001

Using programme budgeting and marginal analysis to assist population based strategic planning for coronary heart disease.

OBJECTIVES: the objective of this project was to use programme budgeting and marginal analysis (PBMA), to inform the planning process of the South Western Sydney Area Health Service (SWSAHS) in respect of coronary heart disease (CHD). METHODS: a working party was established to carry out the project. The group set the parameters of the project and identified the programme, and associated the activity and resource use. Three sub-groups were established to undertake the marginal analysis. RESULTS: each sub-group (representing prevention, treatment, and rehabilitation for CHD) developed a list of potential strategies and provided estimates of resource use and consequences. These were prioritised and presented as recommendations to the SWSAHS. Some recommendations required enhancement funding for the SWSAHS. CONCLUSIOSN: while the use of PBMA presented some challenges, there were also some important outcomes. A comprehensive and detailed picture of resource use enabled the participants to form a view on how additional or reduced resources for CHD should be dealt with at the area level. The ultimate recommendations represent involvement by key stakeholders in the SWSAHS planning process, not just in identifying the 'vision' of CHD services, but also, how service delivery would be organised to achieve the overall objectives of reducing CHD morbidity and mortality.

Australia↗
PubMed2001

Developing better casemix education for rural New South Wales.

Casemix is now an important mechanism for the planning, evaluation and funding of health services in Australia. In New South Wales (NSW) it was believed that while staff from most hospitals in metropolitan Sydney had become both literate and vocal about casemix, staff from rural areas were less familiar and much less likely to participate in casemix initiatives. In conjunction with the NSW Casemix Clinical Committee (NCCC), NSW Health considered a special program of casemix education for rural NSW. Before an education program was attempted, NSW Health inquired into the specific needs for casemix education in rural NSW. Qualitative and quantitative methods of analysis were used. Results of the quantitative analysis indicate that the understanding of casemix classifications is highest among managers. Of concern were the relatively low proportion of Allied Health staff who had more than a vague understanding of the Sub- and Non-Acute Patient (SNAP) classification; the lack of any knowledge of the Mental Health Costing And Service Classification (MH-CASC) by nursing staff; and the lack of any knowledge of the emergency department classification: Urgency, Disposition and Age-related Groups (UDAG), either by clinical or nursing staff. The results of the qualitative analysis show that casemix education for rural areas needs to differ from metropolitan education programs. The analysis also highlights the perception of casemix in rural areas and the special circumstances in rural hospitals that place limits on the ability to use casemix more fully.

Attitude of Health Personnel↗
PubMed2001

The clinical and pathologic implications of plasmacytic infiltrates in percutaneous renal allograft biopsies.

Plasmacytic infiltrates in renal allograft biopsies are uncommon and morphologically distinctive lesions that may represent variants of acute rejection. This study sought significant clinical and pathologic determinants that might have influenced development of these lesions and assessed their prognostic significance. Renal allograft biopsies (n = 19), from 19 patients, with tubulointerstitial inflammatory infiltrates containing abundant plasma cells, composing 32 +/- 8% of the infiltrating mononuclear cells, were classified using Banff '97 criteria. Clonality of the infiltrates was determined by immunoperoxidase staining for kappa and lambda light chains and polymerase chain reaction for immunoglobulin heavy-chain gene rearrangements, using V(H) gene framework 3 and JH consensus primers. In situ hybridization for Epstein-Barr virus encoded RNA (EBER) was performed in 17 cases. The clinical features, histology, and outcome of these cases were compared with kidney allograft biopsies (n = 17) matched for time posttransplantation and type of rejection by Banff '97 criteria, with few plasma cells (7 +/- 5%). Sixteen of 19 biopsies (84%) with plasmacytic infiltrates had EBER-negative (in 14 cases tested) polyclonal plasma cell infiltrates that were classifiable as acute rejection (types 1A [4], 1B [10], and 2A [2]). These biopsies were obtained between 10 and 112 months posttransplantation. Graft loss from acute and/or chronic rejection was 50% at 1 year and 63% at 3 years, and the median time to graft failure was 4.5 months after biopsy. There was no significant difference in overall survival or time to graft failure compared with the controls. Three of 19 biopsies (16%) had EBER-negative polyclonal plasmacytic hyperplasia, mixed monoclonal and polyclonal polymorphous B cell hyperplasia, and monoclonal plasmacytoma-like posttransplantation lymphoproliferative disease (PTLD) and were obtained at 17 months, 12 weeks, and 7 years after transplantation, respectively. Graft nephrectomies were performed at 1, 19, and 5 months after biopsy, respectively. Plasmacytic infiltrates in renal allografts comprise a spectrum of lesions from acute rejection to PTLD, with a generally poor prognosis for long-term graft survival.

Adult↗
PubMed2001

Practice-based research: the Oregon experience.

BACKGROUND: Practice-based research links community-based physicians and their patients with investigators at academic institutions. In 1992, Western States Chiropractic College developed an infrastructure, the Center for Outcomes Studies, to support practice-based research. The Low Back Pain Study, undertaken in collaboration with Oregon Health Sciences University, 111 medical physicians, and 60 chiropractors, relied on the Center for Outcomes Studies infrastructure for support in project implementation and maintenance. RESULTS: Challenges, many of them critical, were a regular occurrence: dealing with unforeseen obstacles, establishing and maintaining physician buy-in, establishing and maintaining staff buy-in, implementing the protocol as directed and with minimal intrusiveness, maintaining enthusiasm for the project over time, and knowing where (and where not) to allocate the Study's time, energy, and money. Strategies were developed to overcome or minimize the impact of problems on a case-by-case basis. CONCLUSIONS: Successful practice-based research requires an awareness of study design issues and an appreciation of clinical practice logistics and priorities. Every effort must be made to include doctors and office staff in the implementation of the study in a manner that minimizes the study's intrusiveness and its economic impact on office organization, routine, and personnel. Investigators must understand and accept that there will be areas of the research environment over which they have no direct control. The challenges will be many, but they will be diminished by the rewards.

Algorithms↗
PubMed2001

Patient characteristics and physicians' practice activities for patients with chronic low back pain: a practice-based study of primary care and chiropractic physicians.

BACKGROUND: Chronic low back pain sufferers are among those who account for the greatest usage of health care resources. Primary care medical (MD) physicians and chiropractic (DC) physicians treat most of these patients. OBJECTIVES: To study patient characteristics and physician practice activities for patients with chronic low back pain treated by DC physicians and MD physicians. METHODS: A longitudinal, practice-based observational study was undertaken in 14 general practice and 51 DC community-based clinics. A total of 2945 consecutive patients with ambulatory low back pain of mechanical origin were enrolled; 835 patients were in the chronic subgroup. Patients were followed for 12 months. Data were obtained on all of the following: patient demographics, health status, and psychosocial characteristics; history, duration, and severity of low back pain and disability; physicians' practice activities; and low back complaint status at 1 year. RESULTS: Patients treated by MD physicians were younger and had lower incomes; their care was more often paid for by a third party; their baseline pain and disability were slightly greater. In addition, patients treated by MD physicians had one fourth as many visits as patients treated by DC physicians. Utilization of imaging procedures by enrolling physicians was equivalent for the two provider groups. Medications were prescribed for 80% of the patients enrolled by MD physicians; spinal manipulation was administered to 84% of patients enrolled by DC physicians. Physical modalities, self-care education, exercise, and postural advice characterized low back pain management in both provider groups. Patients' care-seeking was not exclusive to one provider type. Most patients experienced recurrences (patients treated by MD physicians, 59.3%; patients treated by DC physicians, 76.4%); 34.1% of patients treated by MD physicians and 12.7% of patients treated by DC physicians reported 12 months of continuous pain. Only 6.7% of patients treated by MD physicians and 10.9% of patients treated by DC physicians reported 1 resolved episode during the year. CONCLUSIONS: Differences in sociodemographics, present pain intensity, and functional disability may distinguish patients with chronic low back pain seeking care from primary care medical physicians from those seeking care from DC physicians. Although the primary treatment modality differs, the practice activities of MD physicians and DC physicians have much in common. Long-term evaluation suggests that chronic back pain is persistent and difficult to treat for both provider types.

Adult↗
PubMed2001

To HITH or not to HITH: making a decision about establishing hospital in the home.

Hospital in the home is increasingly being considered as an alternative for the provision of acute care. This article provides an overview of Hospital in the Home in Australia, discussing some of the issues that should be considered when determining whether to establish or fund hospital in the home programs such as whether efficiency is increased, care is improved and whether patients perceive more choice. These issues are discussed in the context of a transparent funding strategy that is aimed at achieving predefined goals and objectives.

Australia↗
PubMed2001

Interaction between the open reading frame III product and the coat protein is required for transmission of cauliflower mosaic virus by aphids.

Transmission of cauliflower mosaic virus (CaMV) by aphids requires two viral nonstructural proteins, the open reading frame (ORF) II and ORF III products (P2 and P3). An interaction between a C-terminal domain of P2 and an N-terminal domain of P3 is essential for transmission. Purified particles of CaMV are efficiently transmitted only if aphids, previously fed a P2-containing solution, are allowed to acquire a preincubated mixture of P3 and virions in a second feed, thus suggesting a direct interaction between P3 and coat protein. Herein we demonstrate that P3 directly interacts with purified viral particles and unassembled coat protein without the need for any other factor and that P3 mediates the association of P2 with purified virus particles. The interaction domain of P3 is located in its C-terminal half, downstream of the P3-P2 interaction domain but overlapping a region which binds nucleic acids. Mutagenesis of P3 which interferes with the interaction between P3 and virions is correlated with the loss of transmission by aphids. Taken together, our results demonstrate that P3 plays a crucial role in the formation of the CaMV transmissible complex by serving as a bridge between P2 and virus particles.

Animals↗
PubMed2001

Reduction in mean glomerular pore size coincides with the development of large shunt pores in patients with diabetic nephropathy.

The glomerular size selectivity was determined by neutral dextran clearance sieving technique and plasma cystatin C levels in two groups of patients with long-standing type I diabetes mellitus and different stages of albuminuria but normal glomerular filtration rate and in a group of healthy controls. The sieving characteristics of the glomerular filter were determined using a mathematical model of log normal pore size distribution. Patients with albuminuria above 200 microg/min exhibited a significant increase of cystatin c plasma concentrations and a significant reduction in mean glomerular filtration slit size. Only these patients exhibited large, unrestrictive pores in the glomerular filter (shunt). The plasma cystatin c levels correlated significantly with 26-angstrom neutral dextran plasma levels in microalbuminuric patients and in patients with albuminuria above 200 microg/min. We conclude that a reduction in average pore size of the glomerular filter does not occur earlier than the development of large shunt pores. The renal clearance of cystatin c in patients with proteinuric diabetic nephropathy but a normal glomerular filtration rate is reduced due to its molecular size.

Adult↗
PubMed2001

The news on health care funding: a study of reporting in the Australian print media for 1996.

OBJECTIVES: To review the coverage of health care funding and resourcing issues in the quality printed media in Australia. METHODS: Content analysis of all articles in six major print publications with detailed commentary on four major issues. RESULTS: One thousand one hundred and fifty articles were published over 12 months, most in the front three pages. Coverage of many issues was prompted by an event, such as an election, government budget or policy announcement. Although issues were rarely personalized, the use of an individual authoritative spokesperson was, with some individuals becoming well recognised as experts. In general, these experts represented vested interest or lobby groups. The media discussion rarely dealt with the system as a whole, and generally approached a topic or issue in isolation from its inter-relationships with other issues. CONCLUSION: Health care funding stories are newsworthy but more for their political interest than as reflection of a social debate about values. Media reports rarely deal with the complexity of health policy issues, or challenge the assumptions and positions put forward.

Australia↗
PubMed2001

Assessing the value of hospital-in-the-home: lessons from Australia.

OBJECTIVES: To identify factors that influence the cost-effectiveness of hospital-in-the-home (HITH) and to discuss the impact of funding arrangements in creating incentives or disincentives for the establishment of HITH services. METHODS: A review of HITH services in Australia was undertaken. Based on the review, factors affecting the relative costs of HITH and conventional care were identified, in particular, the effect of funding and organisational arrangements on the incentives for managers and providers to choose between HITH and conventional care. RESULTS: The review of HITH services identified a wide range of models of HITH in Australia. Factors identified as important to the success of HITH included demographic and location issues, referral mechanisms, the choice of staffing and the management of the programme. However, it was clear that the structure of the programme often related to funding arrangements. Issues such as 'incentive funding', establishment costs and opportunity for cost-shifting were identified as being relevant to incentives for the efficient provision of HITH. CONCLUSIONS: Evaluations are essential to inform decisions about whether HITH is likely to be a viable and cost-effective alternative to inpatient care. However, the relative costs of HITH and conventional care will depend on local factors. From the point of view of the decision-maker, these will be affected by funding and organisational arrangements. Funders must be aware that complex financial incentives may mask the true costs of HITH services relative to hospital services. They need to ensure that the incentives created by funding arrangements are transparent.

Australia↗