Biomedical subjects

C Stanford

Publications and source records attributed to C Stanford.

At least 19 recordsLinked to original sources

PubMed2005

Apatite/amelogenin coating on titanium promotes osteogenic gene expression.

Osteoblast differentiation and extracellular matrix production are pivotal processes for implant osseointegration or bone tissue engineering. We hypothesized that a biomimetic coating on titanium surfaces, consisting of apatite and amelogenin, would promote such processes. Human Embryonic Palatal Mesenchymal pre-osteoblasts were used as a model for the evaluation of cell adhesion and spreading patterns, as well as mRNA expression of certain osteoblastic gene products. Real-time PCR showed significant (p < 0.05) increase in expression of type I collagen, alkaline phosphatase, and osteocalcin from cells grown on titanium with an apatite/amelogenin composite, as compared with that from cells grown on a pure titanium or apatite coating only. Osteocalcin expression was specifically stimulated by amelogenin added to the culture media. Enhanced attachment and cell spreading were also observed. The biomimetic coating promoting cell adhesion and osteoblast differentiation may have great potential for future dental and biomedical applications.

Alkaline Phosphatase↗

PubMed2005

Quantification of manual force control and tremor.

Isometric impulse frequencies associated with active tremor and force regulation were examined in 10 patients with idiopathic Parkinson's disease (PD) and in 10 older adults (OAs) who performed an isometric tracing task. The authors decoupled and analyzed the data to determine whether PD-related tremor in the thumb and in the index finger during isometric force control are related and whether PD impairs the performance of volitional force control beyond the errors contributed by tremor. After decoupling, there were clear and robust differences in PD patients' control of isometric force that could not be attributed to action-tremor error. Those errors, which occurred in the absence of movement, suggest impairment in coordinated recruitment and derecruitment of motor units during a fine-motor task.

Adult↗

PubMed2004

Altered Cbfa1 expression and biomineralization in an osteosarcoma cell line.

Osteoblast differentiation and expression are regulated by Cbfa1 transcription factors. Recent evidence suggests that Cbfa1 may also regulate bone mineralization. The purpose of this study was to characterize Cbfa1 expression in relation to mineralization in rat UMR106-01 osteoblastic cell cultures. UMR106-01 BSP cultures consistently form bone-like mineral, whereas the UI subclone mineralize gradually. BSP and UI cultures were grown for 48 h and then treated with beta-glycerophosphate. BSP cultures had alizarin red stained calcifications and mineral-like deposits within 24 h of phosphate. Atomic absorption spectroscopy measured significantly (P<0.0001) more calcium in the phosphate-treated BSP cultures than in the UI. Cbfa1 message was detected in the BSP and UI cultures, but the Cbfa1 N-terminal isoform was deficient in UI and appeared to be up-regulated in the phosphate-treated BSP cultures. Cbfa1 protein levels were also reduced in the UI. DNA sequence from the RT-PCR products was utilized to design Taqman Real-time RT-PCR reagents. Quantitative Real-time RT-PCR analysis showed that Cbfa1 mRNA levels relative to endogenous 18 s rRNA were lower in the slower mineralizing UI cultures. Furthermore, the Cbfa1 N-terminal isoform mRNA levels were significantly (P<0.001) lower in the slower mineralizing cultures. Transfection with Cbfa1 or isoform antisense caused a significant (P<0.001) reduction in mineralization. Therefore, Cbfa1 expression may be associated with bone-like mineral formation in rat UMR106-01 osteoblastic cell cultures.

Animals↗

PubMed2003

Implant surface roughness affects osteoblast gene expression.

The transcription factor Cbfa1 regulates osteoblast differentiation and expression of genes necessary for the development of a mineralized phenotype. The purpose of this study was to determine if Cbfa1 and BSPII gene expression are influenced by implant surface microtopography. Osteoblasts were cultured on 600-grit (grooved) or sandblasted (roughened) cpTi implant discs. Mineralization was evaluated by Alizarin-Red-S staining. Real Time PCR was used for quantitative analysis of Cbfa1 and BSPII gene expression. Enhanced mineralization was seen in osteoblasts grown on roughened implant surfaces relative to tissue culture plastic. Real Time PCR showed significant (P < 0.05) increases in Cbfa1 gene expression in cells grown on roughened, as compared with grooved, implant surfaces. BSPII gene expression was also increased on rough surfaces in the UMR cells, but was reduced in the rat calvarial osteoblast cultures. These results suggest that osteoblast gene expression and mineralization are affected by roughened implant surface microtopographies during osseointegration of dental implants.

Analysis of Variance↗

PubMed2001

The design and testing of a force feedback dental simulator.

The Iowa Dental Surgical Simulator is a haptic simulator to train dental students in the haptic skills of dentistry. The initial design emphasizes the detection of carious lesions. This work describes the software and implementation of the prototype system, the design tradeoffs' and the technical issues associated with haptic and graphics subsystems. The work also describes the current system performance, including a formal evaluation by practicing dentists and performance measures. A discussion of the limitations of the current system is followed by an analysis of opportunities to improve the quality of the simulator. The results should be of interest to designers of medical haptic simulation systems and other simulation designers.

Biophysical Phenomena↗

PubMed2001

Early cell adhesion events differ between osteoporotic and non-osteoporotic osteoblasts.

In osteoporosis, the regenerative capacity of bone is compromised, which may involve altered osteoblast (OB) activity. This could be attributed to an inappropriate synthesis and assembly of an extracellular matrix (ECM), altered cell adhesion to the ECM, or be due to inappropriate downstream activation of adhesion-mediated signaling cascades through proteins such as focal adhesion kinase (FAK). The purpose of our study was to compare early adhesion-mediated events using previously described and characterized clinically derived OBs obtained from human patients undergoing major joint arthroplasty for osteoporosis or osteoarthritis. The presence or absence of osteoporosis was established with a radiographic index. Using light microscopy and crystal violet staining, we show that OB cells derived from sites of osteoporosis do not attach and spread as well as non-osteoporotic (OP) OB cells. OP cells initially have a more rounded morphology, and show significantly less (P < 0.001) attachment to serum-coated tissue culture plastic over a 24 h time period. Immunofluorescent labeling after 24 h of attachment showed that OP OB focal adhesions (FAs) and stress fibers were less defined, and that the OP cells were smaller and had a more motile phenotype. When normalized protein lysates were Western blotted for phosphotyrosine (PY) a band corresponding to pp125FAK was identified. FAK tyrosine phosphorylation was evident at 6 h in both the OP and non-OP OBs, but decreased or was absent through 24 h in OP OBs. These results suggest early adhesion-mediated events, such as cell adhesion, attachment, and FAK signaling via PY may be altered in OP OBs.

Actins↗

PubMed2001

Osteoblast integrin adhesion and signaling regulate mineralization.

Integrin adhesion and signaling events may contribute to the progressive differentiation of the osteoblast and to the initiation of a mineralized matrix. The purpose of our study was to begin to analyze the role of integrin receptors, in particular alpha2beta1, alpha5beta1, and alphaVbeta3, regarding mediation of the initiation of a mineralized matrix. Integrin-perturbation assays were conducted in microdot cultures of UMR-106-01 Bone Sialoprotein (BSP) osteoblast cells. For phenotypic analysis, we performed bright-field microscopy and Aliziran Red S staining to analyze effects on mineralization initiation. Mineralization was reduced significantly (P < 0.001) following the addition of alpha5- or beta1-integrin subunit antibody by approximately 20% and 45%, respectively--alphaVbeta3 integrin by nearly 65%, and alpha2beta1 integrin by nearly 95%. This effect was reversible following the removal of the antiintegrin antibody. These results suggest that integrin adhesion and signaling events may contribute to the ability of this cell line to mediate the initiation of the mineralization phenotype biologically.

Analysis of Variance↗

PubMed2000

An initial evaluation of the Iowa Dental Surgical Simulator.

The University of Iowa colleges of dentistry and engineering are collaborating to build an effective but low-cost surgical simulator that uses force feedback to teach and assess the tactile skills of dentistry. A prototype simulator was built, and a formative evaluation examined the realism of the haptics and identified directions for future work. Using a cross-over design, twelve experienced practitioners probed two virtual teeth using two instruments attached to the force feedback device. The session was videotaped, the forces recorded, and a standardized questionnaire completed. Two analyses were conducted: an ANOVA examined practitioners' questionnaire responses, and a t-test analyzed the probing forces. Significant tooth order by instrument order interaction and instrument effects were found. Practitioners were generally satisfied. They preferred a standard joystick to an explorer, felt that two-dimensional graphics were sufficient, and emphasized that the existing vibration be eliminated. Random placement of caries should help teach generalized skills.

Analysis of Variance↗

PubMed1999

Clinical and serological studies of tuberculosis patients in Argentina receiving immunotherapy with Mycobacterium vaccae (SRL 172).

Two small, placebo-controlled studies of immunotherapy with heat killed Mycobacterium vaccae added to routine chemotherapy for pulmonary tuberculosis, together involving 40 HIV seronegative patients, were carried out in Argentina. The immunotherapy was associated with reduced sputum smear positivity of AFB at 1 month and a greater reduction in ESR at 2 months. In the first study radiological improvement was better (P < 0.05) among immunotherapy recipients. In the second study, weight regain and time to become apyrexial were measured and were found to be improved amongst immunotherapy recipients (P < 0.05). In the first month of treatment the levels of IgG to the 65 kDa and 70 kDa heat-shock proteins showed greater falls following immunotherapy (P < 0.05 and P < 0.001, respectively). On admission serum cytokine levels of interleukins 4 and 10 (IL-4, IL-10), interferon gamma (IFN-gamma) and tumour necrosis factor alpha (TNF-alpha) were grossly raised in comparison with a matched control group (P < 0.001). After 1 month. Levels of IL-4, IL-10 and TNF-alpha fell (P < 0.001, P < 0.01 and P < 0.01, respectively) and levels of IFN-gamma rose more (P = 0.005) in immunotherapy recipients than in those receiving chemotherapy alone. The results are in accord with a switch towards a TH1 immunological status and clinical benefit for immunotherapy recipients.

Adjuvants, Immunologic↗

PubMed1998

Studies of vaccination of persons in close contact with leprosy patients in Argentina.

A total of 670 adults living or working with leprosy patients, were examined for a BCG vaccination scar, and skin-tested with four new tuberculins. Based on the results 513 were vaccinated, 65 with Bacille de Calmette et Guérin (BCG) alone, 66 with BCG plus killed Mycobacterium vaccae and 382 with killed M. vaccae alone. Skin-testing was repeated 2-3 years later on 344 subjects, when all three vaccines were found to have been highly successful in increasing responses to Tuberculin and Leprosin A (p < 0.0005) with increased immune recognition of common and species-specific antigens. Mean diameters of induration to each skin-test were greatest in recipients of BCG alone (p < 0.05), which suggests that better immuno-regulation occurs after receiving vaccines that incorporate M. vaccae. The results suggest 10(8) M. vaccae alone might prove a valuable future vaccine, which would not require selective pre-vaccination procedures.

Adult↗

PubMed1998

Immunotherapy with Mycobacterium vaccae in the treatment of psoriasis.

A placebo-controlled study of immunotherapy with Mycobacterium vaccae for chronic plaque psoriasis showed improvement in the psoriasis area severity index in 19 of 21 immunotherapy recipients (P<0.005). Minor improvement, not reaching statistical significance for the group, occurred in nine of 14 placebo recipients. There were losses to follow-up and the placebo used, tetanus toxoid, was not ideal. Clinical improvement after immunotherapy persisted for 6 months and another injection of the immunotherapeutic given to a few volunteers from either group resulted in benefits lasting a year. Lymphoproliferative tests were carried out at each clinic visit, and on 50 matched controls. Starting with reduced responses to mycobacterial antigens and concanavalin A, both treatment groups showed a fall after 3 months, and diverged at 6 months with M. vaccae recipients rising to values similar to those of healthy controls, whereas placebo recipients continued to fall. Conclusions reached were that immunotherapy with M. vaccae gave long-lasting clinical benefit to most patients, with minimal side effects. This accompanied a return towards normal cellular immune responsiveness to mycobacterial antigens, which did not follow the use of the placebo.

Adult↗

PubMed1995

Anaerobic tissue-dissolving abilities of calcium hydroxide and sodium hypochlorite.

Closed root canals likely have an oxygen-free environment; most bacteria in canals are anaerobic. These bacteria and other debris are difficult to remove. Unknown is tissue dissolution with chemicals under these anaerobic conditions. This study evaluated and compared dissolving properties of calcium hydroxide (Ca(OH)2) and sodium hypochlorite (NaOCl) on bovine pulp tissue in aerobic and anaerobic environments. Sixty bovine pulp specimens were dried, then randomly divided into six groups. Groups A and B were immersed in Ca(OH)2 + water solution, whereas group C and D were in 2.5% NaOCl. Groups E and F (controls) specimens were placed in distilled water. Groups A, C, and E were incubated anaerobically, and groups B, D, and F were incubated under regular atmospheric conditions, all for 7 days. Percentages of weight loss were compared between groups. Results showed the following: (a) both chemicals partially dissolved pulp tissue, (b) anaerobic environment did not alter tissue-dissolving properties of Ca(OH)2 or NaOCl, and (c) Ca(OH)2 and NaOCl were equal and more effective than water.

Anaerobiosis↗

PubMed1990

Bone acidic glycoprotein-75 is a major synthetic product of osteoblastic cells and localized as 75- and/or 50-kDa forms in mineralized phases of bone and growth plate and in serum.

Anti-peptide and anti-protein antisera were produced which both recognize bone acidic glycoprotein-75 (Mr = 75,000) and an apparent fragment or biosynthetic intermediate (Mr = 50,000) in calcified tissues and/or serum. A fragment-precursor relationship is suggested from the fact that closely spaced doublet polypeptides of Mr = 50,000 could be produced by proteolysis of the purified protein upon long term storage. No reactivity was detected with osteopontin, bone sialoprotein, or small bone proteoglycans. Bone acidic glycoprotein-75 represents 0.5-1% of the total radiolabeled proteins synthesized by explant cultures of neonatal calvaria or growth plate, by calvarial outgrowth cultures, and by rat osteosarcoma cells. Amounts produced by explant cultures and calvarial outgrowth cultures were similar to that for osteopontin, a major product of osteoblasts. In osteosarcoma cultures, 80% of labeled antigens were associated with the cell layer fraction wherein specific immunoprecipitation pelleted Mr = 50,000 and 75,000 sized antigens. Bone acidic glycoprotein-75 (Mr = 75,000) is enriched in 4 M guanidine HCl/0.5 EDTA extracts of neonatal rat bone and growth plate tissues, whereas largely absent from heart, lung, spleen, liver, brain, and kidney. Explant cultures of these noncalcifying tissues also synthesized bone acidic glycoprotein-75 antigen, but the quantities produced were only 5% or less that obtained with calvaria. By immunohistochemistry, antigenicity is associated with the bony shaft and calcified cartilage of long bones, but is absent from associated soft tissues. These finding demonstrate that bone acidic glycoprotein-75 is antigenically distinct, predominantly localized to calcified tissues, represents a major product of normal osteoblastic cells and may undergo a characteristic fragmentation in vivo and in vitro.

Animals↗

PubMed1988

Peripheral noradrenaline depletion does not impair extinction of food-rewarded running in the rat.

To test whether the sympathetic nervous system influences the inhibition of non-rewarded running in the runway, we examined the effects of peripheral noradrenaline depletion, induced by 6-hydroxydopamine (6-OHDA HBr, 30 mg/kg, i.p.), on extinction of food-rewarded running in rats. This was done in two separate experiments. In the first, in which the inter-trial interval (ITI) was one day and rats were injected before acquisition, running times at the end of extinction did not differ. The 6-OHDA appeared to slow down running times at the end of acquisition and the start of extinction. In the second experiment (15 s ITI) therefore, rats were injected after stable running had been acquired; there was no effect on running in subsequent rewarded trials. In extinction, although the groups ran similarly at first, the 6-OHDA treated animals subsequently ran more slowly than the controls; that is they showed greater extinction. Taken together with other published evidence, the sympathetic nervous system does not appear to contribute to the extinction of continuously reinforced responses.

Animals↗

PubMed1986

An amperometric enzyme electrode for monitoring brain glucose in the freely moving rat.

Brain glucose concentration was measured with an amperometric enzyme electrode using glucose oxidase (EC 1.1.3.4) irreversibly adsorbed onto an organic conducting salt. The responses of the electrode and its stability both in vitro and in vivo are described. Parellel changes in brain glucose and blood glucose (measured in samples from an implanted intra-atrial cannula) following injections of insulin are reported.

Animals↗

PubMed1985

The effect of peripheral noradrenaline depletion on responding on a schedule of differential reinforcement of low rates of response (DRL).

First, it was confirmed that systemic injection of the neurotoxin 6-hydroxydopamine HBr (30 mg/kg IP) depleted noradrenaline levels in rat heart, but not centrally. Losses averaged 90% of control 1 day after injection, and 50% at 42 days. The same drug and dose was then administered to 50% of a group of rats which had been trained to lever-press for food reward on continuous reinforcement (CRF). After further CRF sessions, the rats were changed to a schedule of Differential Reinforcement of Low Rates of Response with a 20-s criterion (DRL 20). The drugged rats earned fewer reinforcements during DRL than did controls, and made fewer responses. Temporal discrimination (shown by the IRT/Opp distribution) was disrupted. It is concluded that peripheral noradrenergic systems may be involved in the control over responding by temporal cues associated with reward and non-reward.

Analysis of Variance↗

PubMed1984

The effect of repeated mild stress on cerebral cortical adrenoceptors and noradrenaline synthesis in the rat.

The effects of repeated mild stress on cortical alpha 2- and beta-adrenoceptor binding sites and on the rate of noradrenaline synthesis in cortical synaptosomes were measured. The stressful stimuli were either daily handling (1 min) or daily handling which included an i.p. saline injection. In both cases, rats killed 24 h after the last of 14 daily treatments showed an increase in noradrenaline synthesis rate and a decrease of alpha 2- and beta-adrenoceptor density. There were no changes in adrenoceptor density or the noradrenaline synthesis rate after either a single or 5 daily handlings plus saline injections. At no time was a change found in the Kd of either alpha 2- or beta-adrenoceptor binding sites. The results are discussed in relation to the effects on adrenoceptors of chronic antidepressant treatments.

Animals↗

PubMed1983

Comparison of the effects of chronic desmethylimipramine administration on alpha 2- and beta-adrenoceptors in different regions of rat brain.

The effects of ten once-daily injections of desmethylimipramine (10 mg/kg i.p.) on alpha 2- and beta-adrenoceptor binding were investigated in the rat cortex, hippocampus and hypothalamus. [3H]clonidine and [3H]dihydroalprenolol were used as ligands for alpha 2- and beta-adrenoceptors, respectively. Twenty-four hours after the last injection, the density of beta-adrenoceptors was reduced in all regions studied. In contrast, there was no change in alpha 2-adrenoceptor binding in the cortex, while increased binding was found in the hypothalamus. The effects of desmethylimipramine are discussed in relation to those of other antidepressant treatments.

Animals↗