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Biomedical subjects

M L Jones

Publications and source records attributed to M L Jones.

At least 19 recordsLinked to original sources
PubMed2002

Phospholipase C isoforms in mammalian spermatozoa: potential components of the sperm factor that causes Ca2+ release in eggs.

Injection of a soluble protein factor from mammalian spermatozoa triggers Ca2+ oscillations in mammalian eggs similar to those seen at fertilization. This sperm factor also generates inositol 1,4,5-trisphosphate and causes Ca2+ release in sea urchin egg homogenates and frog eggs. Recent studies have indicated that the sperm factor may be an inositol-specific phospholipase C (PLC) activity. This study investigated whether any of the commonly known PLC isoforms are components of the sperm factor. PLCbeta, PLCgamma and PLCdelta isoforms were shown to be present in boar sperm extracts. However, upon column fractionation of sperm extracts, none of the PLC isoforms detected correlated with the ability to cause Ca2+ release in eggs. In addition to our previous work on recombinant PLCs, it was also shown that PLCdelta3, PLCdelta4 and its splice variant PLCdelta4 Alt1 fail to cause Ca2+ release. The recently discovered 255 kDa PLCepsilon isoform also appears unlikely to be a component of the sperm factor, as fractionation of sperm extracts on a gel filtration column demonstrated that the peak of Ca2+-releasing activity was associated with fractions of 30-70 kDa. These findings indicate that the sperm factor that triggers Ca2+ release in eggs does not appear to have a known PLC isoform as one of its components.

Animals↗
PubMed2001

Induction of abnormal Chlamydia trachomatis by exposure to interferon-gamma or amino acid deprivation and comparative antigenic analysis.

Abnormal forms of Chlamydia trachomatis have been induced in vitro by a variety of methods including nutrient deprivation, addition of cytokines and addition of antibiotics. These forms have been shown to have altered morphology and infectivity and have been implicated in persistent infections in vivo although there is little direct evidence for their presence. Likely sites for abnormal forms in vivo are the genital tract and the synovial tissue of reactive arthritis patients, and T cells isolated from the synovial tissue have been shown to be specific for chlamydial antigens, in particular the Hsp60. Since T cell specificity is so important in reactive arthritis disease the antigenic composition of abnormal forms induced by Interferon-gamma and amino acid deprivation has been examined by western blotting in two strains of C. trachomatis belonging to different biovars. The degree of abnormality of the organisms was found to increase as the treatments became more severe. No simple patterns of antigenic changes were found and differences in the antigenic composition were seen in abnormal forms induced by the different treatments and also in the different strains.

Amino Acids↗
PubMed2001

A systematic review of the clinical effectiveness of pioglitazone in the treatment of type 2 diabetes mellitus.

BACKGROUND: Pioglitazone is a member of a recently developed class of glucose-lowering agents, the thiazolidinediones, used in the treatment of type 2 diabetes mellitus. In the United States, it is approved for use both as monotherapy and in combination with metformin, a sulfonylurea, or insulin; in Europe, it is approved for use in combination with metformin or a sulfonylurea but not insulin. OBJECTIVE: This article presents a systematic review of the published literature on the effectiveness of pioglitazone in the treatment of type 2 diabetes, both as monotherapy and in combination with other antidiabetic agents. METHODS: The peer-reviewed English- and foreign-language literature was searched using MEDLINE, PubMED, EMBASE, Science Citation Index, the Cochrane Database of Systematic Reviews, the Cochrane Controlled Trials Register, the UK National Health Service Centre for Reviews and Dissemination databases, and the Office of Health Economics Health Economic Evaluations Database. Searches were not limited to specific publication types, study designs, dates, or languages. The latest search was performed in March 2001. For a trial to be included in the review, at least 1 outcome measure had to involve the effects of pioglitazone on glycemic control or cardiovascular risk factors, or its side effects. Because of the heterogeneity of studies, no formal meta-analysis was performed. RESULTS: Eleven studies met the inclusion criteria, 6 involving pioglitazone monotherapy and 5 involving combination therapy. Full reports were available for only 6 of the 11 studies. No studies directly compared pioglitazone with other antidiabetic drugs. Both as monotherapy and in combination therapy, pioglitazone produced decreases in blood glucose levels (up to 95 mg/dL) and glycosylated hemoglobin (up to 2.6%). At doses of > or = 30 mg/d, pioglitazone was associated with reductions in triglyceride levels (-30-70 mg/dL) and increases in high-density lipoprotein cholesterol (HDL-C) levels (-4-5 mg/dL). Pioglitazone treatment was associated with significant weight gain (up to 4 kg over 16 weeks). Adverse effects included mild edema (in up to 11.7% of patients) and a clinically nonsignificant decrease in hemoglobin concentrations. Abnormal results on liver function testing were no more common in treated patients than in control groups. CONCLUSIONS: Pioglitazone has been shown to reduce blood glucose levels in patients with type 2 diabetes. Although the observed decreases in triglyceride levels and increases in HDL-C levels could be expected to lead to a reduction in cardiovascular risk, the effects of weight gain may counteract this benefit. The evidence suggests that the preferred role for pioglitazone may be as an adjunct to metformin or a sulfonylurea in patients whose condition is not well controlled with monotherapy and for whom a metformin-sulfonylurea combination is contraindicated. There is a need for large-scale, long-term studies comparing the effectiveness of combination therapy that includes pioglitazone with that of other combinations of antidiabetic drugs.

Adult↗
PubMed2001

An evaluation of the quality of orthodontic attachment offered by single- and double-mesh bracket bases using the finite element method of stress analysis.

The objective of this study was to evaluate the influence of bracket base mesh geometry on the stresses generated in the bracket-cement-tooth continuum by a shear/peel load case. A validated three-dimensional finite element model of the bracket-cement-tooth system was constructed consisting of 15,324 nodes and 2971 finite elements. Cement geometric and physical properties were held constant and bracket base geometry was varied, representing a variety of single-mesh configurations and 1 double-mesh design. For the single-mesh designs, increasing wire diameter (100-400 microm) resulted in a decrease in enamel and cement stresses. Increases in wire mesh spacing (200-750 microm) increased the major principal stress recorded in the enamel and adhesive at all wire diameters. Within the bracket, the major principal stress increased significantly at wire spacing above 400-500 microm. However, within the impregnated wire mesh (IWM), the major principal stress decreased as wire space increased. When the double-mesh bracket base was considered, the combined mesh layers resulted in a decrease in the stresses recorded in the most superficial (coarse) mesh layer and an increase in the stresses recorded in the deepest (fine mesh) layer when compared with the single-layer designs in isolation. Modification of single-mesh spacing and wire diameter influences the magnitude and distribution of stresses within the bracket-cement-tooth continuum. The use of a double-mesh design results in a reduction in the stresses recorded in the most superficial mesh. Mesh design influenced stress distribution in this study, primarily by determining the flexibility of the bracket base.

Bicuspid↗
PubMed2001

An evaluation of the influence of orthodontic adhesive on the stresses generated in a bonded bracket finite element model.

The objective of this study was to evaluate the stresses generated in the bracket-cement-tooth continuum by a tensile load case when the physical and geometric properties of cement are varied. A 2-stage approach was used. In the first stage, a validated 3-dimensional finite element model of the bracket-cement-tooth system was constructed that consisted of 15,324 nodes and 2971 finite elements. Bracket base geometry was held constant; the physical properties (elastic modulus; Poisson's ratio) and geometry (lute thickness) of the cement varied. A simplified 2-dimensional model was then developed to investigate the localized effects of the cement lute thickness and the shape of the lute periphery on the stress distribution in the system. Small increases in stress were recorded under load within the cement as the rigidity of the cement increased. Similarly, Poisson's ratio values above 0.4 appeared to have a small influence on the major principal stresses in the impregnated wire mesh layer when a tensile force was applied. Variation in lute thickness was shown to have an influence on the distribution of major principal stresses within the cement lute. Increased stresses were recorded at the lute periphery as the lute dimensions increased. The morphologic features of the lute periphery also appeared to have had a significant effect on the performance of an orthodontic adhesive. Acute cement-enamel angles resulted in an increased chance of singularity development and attachment failure. The physical properties and thickness of the cement lute and the shape of the cement lute periphery contribute to the stress distribution within the bracket-cement-tooth continuum and, therefore, the quality of orthodontic attachment provided.

Adhesives↗
PubMed2001

A validated finite element method study of orthodontic tooth movement in the human subject.

The aim of the study was to develop a 3D computer model of the movement of a maxillary incisor tooth when subjected to an orthodontic load. A novel method was to be developed to directly and accurately measure orthodontic tooth movement in a group of human volunteers. This was to be used to validate the finite element-based computer model. The design took the form of a prospective experiment at a laboratory at the University of Wales in 1996/7. A laser apparatus was used to sample tooth movement every 0.01 seconds over a 1-minute cycle for 10 healthy volunteers, whilst a constant 0.39 N load was applied. This process was repeated on eight separate occasions and the most consistent five readings taken for each subject. Data were used to calculate the physical properties of the periodontal ligament (PDL). The data gleaned by this method were used to validate the 3D FEM model. This was formed of 15,000 four-noded tetrahedral elements. Tooth displacements ranged from 0.012 to 0.133 mm. An appropriate elastic modulus of 1 N/mm(2) and Poisson's Ratio of 0.45 was derived for the PDL. Strain analysis, using the model, suggested that a maximum PDL strain of 4.77 x 10(-3) was recorded at the alveolar crest, while the largest apical strain recorded was 1.55 x 10(-3). The maximum strains recorded in the surrounding alveolar bone were 35 times less than for the PDL. A novel method for direct measurement of PDL physical properties in the human subject has been developed. The validated FEM model lends further evidence that the PDL is the main mediator of orthodontic tooth movement.

Adult↗
PubMed2000

Contextual control over conditioned responding in a latent inhibition paradigm.

We used 1-, 2-, and 3-context designs to study the control exerted by contexts over freezing in rats exposed to a conditioned stimulus (CS) in advance of its pairing with a shock unconditioned stimulus. The latent inhibition observed when preexposure, conditioning, and testing occurred in the same context was attenuated if preexposure occurred in a different context to conditioning and testing. Latent inhibition (i.e., attenuated performance) was restored in a CS-specific manner if preexposure and testing occurred in the same context and conditioning in a different one. Latent inhibition was also reduced by a long retention interval but remained specific for a particular context-CS relation. Finally, CS preexposure resulted in contextual control over the expression of excitatory conditioned performance. The results are discussed in terms of memory, associative, and associative-performance models of CS-preexposure effects.

Animals↗
PubMed2000

Contextual control over conditioned responding in an extinction paradigm.

Four experiments studied contextual control over rats' freezing to conditioned stimuli (CSs) that had been paired with shock and were then extinguished. In Experiment 1, rats were exposed to a CS A-shock and a CS B-shock pairing in Context C. CS A was then extinguished in Context A, and CS B in Context B. Freezing was renewed when each CS was presented in the context where the other CS had been extinguished. In Experiments 2-4, rats were exposed to a CS A-shock pairing in A and a CS B-shock pairing in B. They were then exposed to Context C where one, both, or neither of the CSs were extinguished, or where both CSs continued to be reinforced. On test, the rats froze more to CS A than to CS B in Context A, and more to CS B than to CS A in Context B, but only if the CSs had been extinguished. Thus, after extinction, rats use contexts to regulate retrieval not only of their memory for extinction, but also of their memory for the original conditioning episode.

Aged↗
PubMed2000

The influence of orthodontic adhesive properties on the quality of orthodontic attachment.

The objective of this study was to determine the resilience, glass transition temperature (Tg), ultimate flexural strength (UFS), and penetration coefficient of 3 composite adhesives (Concise, Transbond, and Right On) and a glass ionomer cement (Fuji Ortho LC). For 25 minutes after initial set, the composite materials were significantly more resilient than Fuji Ortho LC (P = .000). Resilience values for all materials increased for up to 90 minutes after initial set, reflecting a continuation of their setting reaction. Right On remained the most resilient material at 90 minutes after initial set (P < or = .01). At 120 minutes, there was no significant difference in the resilience of Concise, Right On, and Fuji Ortho LC. However, Transbond was significantly less resilient than these materials (P < or = .01). The composite materials recorded significantly higher glass transition values (89-123 degrees C) than Fuji Ortho LC (54 degrees C). The composite materials were also significantly stronger (61-68 MPa) than Fuji Ortho LC (35 MPa) in flexion. The penetration coefficients of Concise and Transbond were significantly higher (P < or = .001) than Right On and Fuji Ortho LC. However, the relative penetration coefficients of the materials studied did not appear to influence the degree of bracket base penetration achieved by the cements. In conclusion, Fuji Ortho LC offered a reduced energy-absorbing capacity immediately after bracket placement and reduced cohesive and mechanical adhesive strength. In addition, the glass transition temperature of Fuji Ortho LC was low; this may result in compromised attachment at temperatures above 60 degrees C. Significant differences in the penetration coefficient of the materials studied have been recorded. However, the penetration of the 4 cements into a range of bracket base morphologies was uniformly good. Therefore, the differences in penetration coefficient recorded should not influence the quality of the bracket cement interface provided.

Acrylic Resins↗
PubMed2000

Endotoxin and nanobacteria in polycystic kidney disease.

BACKGROUND: Microbes have been suspected as provocateurs of polycystic kidney disease (PKD), but attempts to isolate viable organisms have failed. Bacterial endotoxin is the most often reported microbial product found in PKD fluids. We assessed potential microbial origins of endotoxin in cyst fluids from 13 PKD patients and urines of PKD and control individuals. METHODS: Fluids were probed for endotoxin and nanobacteria, a new bacterium, by the differential Limulus Amebocyte Lysate assay (dLAL), genus-specific antilipopolysaccharide (LPS) antibodies, monoclonal antibodies to nanobacteria, and hyperimmune serum to Bartonella henselae (HS-Bh). Selected specimens were also assessed by transmission electron microscopy (TEM) and nanobacterial culture methods. RESULTS: LPS or its antigenic metabolites were found in more than 75% of cyst fluids tested. Nanobacteria were cultured from 11 of 13 PKD kidneys, visualized in 8 of 8 kidneys by TEM, and immunodetected in all 13 PKD kidneys. By immunodetection, nanobacterial antigens were found in urine from 7 of 7 PKD males, 1 of 7 PKD females, 3 of 10 normal males, and 1 of 10 normal females. "Nanobacterium sanguineum" was dLAL positive and cross-reactive with antichlamydial LPS and HS-Bh. Some cyst fluids were also positive for LPS antigens from Escherichia coli, Bacteroides fragilis and/or Chlamydia, and HS-Bh, as were liver cyst fluids from one patient. Tetracycline and citrate inhibited nanobacterial growth in vitro. CONCLUSION: Nanobacteria or its antigens were present in PKD kidney, liver, and urine. The identification of candidate microbial pathogens is the first step in ascertaining their contribution, if any, to human disease.

Adult↗
PubMed2000

Initial experiences with telerehabilitation and contingency management programs for the prevention and management of pressure ulceration in patients with spinal cord injuries.

Two alternative treatment methods for preventive interventions for pressure ulcers, tele-rehabilitation and contingency management, are discussed. Telerehabilitation uses a videophone that transmits both audio and still images over a telephone line. Using this technology, the WOC nurse can interview a patient who cannot be present at a clinic because of physical condition or distance. Telerehabilitation allows the nurse to assess a patient's pressure ulcer, consult with appropriate caregivers, and make recommendations for treatment. Contingency management procedures are designed for patients with high rates of noncompliance in skin care. The patients are seen as outpatients and are compensated systematically for appropriate skin care (ie, the lack of pressure ulcers). Examples of each of these patient interventions is described, discussed, and contrasted.

Ambulatory Care↗
PubMed2000

An evaluation of the stresses generated in a bonded orthodontic attachment by three different load cases using the Finite Element Method of stress analysis.

The objective of the investigation was to develop a clinically valid three-dimensional computer model of the orthodontic bracket-cement-tooth continuum, and determine the magnitude and distribution of stresses generated by three different load cases. A three-dimensional finite element model of the bracket-cement-tooth system was constructed consisting of 15,324 nodes and 2,971 finite elements. The stresses induced in the bracket-tooth interface by a masticatory load, a peel force and a twisting couple were recorded. The maximum principal stresses resulting from occlusal and 'twisting' forces are distributed toward the lute periphery. Peel forces, applied to the bracket tie wing, are concentrated beneath the bracket stem. Twisting forces result in the highest enamel stresses. The quality of orthodontic attachment can be explained by the magnitude and distribution of major principal stresses within the cement and impregnated bracket base. Shear and shear/peel forces are most likely to induce crack propagation within the adhesive layer. However, when a twisting action is used to remove orthodontic brackets, enamel failure is most likely. A clearer insight into the complexity of the bracket-cement-tooth system has been provided by numerical and finite element investigations. Further investigations, evaluating the influence of bracket base designs and orthodontic cement physical and geometric properties are indicated. Refereed Scientific Paper

Compressive Strength↗
PubMed2000

The Balanced Scorecard: a strategic management system for multi-sector collaboration and strategy implementation.

This article illustrates the application of the Balanced Scorecard, a method more commonly associated with the business world, to a nonprofit multisector National Women's Health Quality Initiative (NWHQI). The article delineates the following multiple uses of the Balanced Scorecard for the NWHQI effort: Set NWHQI strategy and structure. Provide the framework and principles to implement NWHQI's strategy. Develop a measurement system to assess the progress and success of NWHQI's strategy. Serve as a collaboration mechanism for multisector stakeholders. Advance women's health knowledge base. This article concludes by sharing key insights regarding the utility of the Balanced Scorecard to promote the success of this nationwide women's health quality initiative.

Cooperative Behavior↗
PubMed2000

Implementation and outcomes of a balanced scorecard model in women's services in an academic health care institution.

In the current, chaotic health care climate an important success determinant for health care administrators and clinicians is the support of timely, collaborative decisions for delivery of patient care. The purpose of this article is to describe implementation and outcomes of the application of the Balanced Scorecard (BSC) model, a strategic management system, for a Women's Services Clinical Business Unit (CBU) in an academic health care institution, a complex adaptive system. Emphasis is focused on crucial process and outcome indicators that demonstrate how the work of all team members makes a difference at the point of clinical services across the continuum. Finally, implications for leadership development are revealed from the principles underlying complexity science.

Academic Medical Centers↗