Search PubMed⌕ Search

Biomedical subjects

D Robinson

Publications and source records attributed to D Robinson.

At least 73 records · Page 4Linked to original sources
PubMed2001

Articular Cartilage Chondrocytes are more Advantageous for Generating Hyaline-like Cartilage than Mesenchymal Cells Isolated from Microfracture Repairs.

Articular cartilage lacks self-repair capacity. Currently, two methods employing autologous cells are used to stimulate repair of articular cartilage. Micro-fracture induced repair induces autologous mesenchymal cell migration from bone marrow. Autologous chondrocytes' transplantation involves in vitro expansion of chondrocytes, and later implantation. In 15 patients de-differentiated chondrocytes obtained by cartilage biopsy were compared to cells derived from repair tissue induced by micro-fracture. These patients all underwent micro-fracture during the cartilage biopsy procedure. Autologous chondrocytes' transplantation was performed at least two months later then the biopsy. Tissue bits from articular cartilage and micro-fracture repair tissue were incubated in-vitro and explant cell cultures established. The cell cultures were assessed by immunohistochemistry and induced to differentiate. Differentiation into bone tissue was stimulated by addition of basic fibroblast growth factor, ascorbate and dexamethasone. High density (micro-mass) culture was used to stimulate chondrogenesis. Both cell cultures consist of mesenchymal progenitors as indicated by fibroblast growth factor receptor 3 expression and anti-CD-34+ antibodies. However, the micro-fracture generated repair tissue consists of osteocalcin-expressing cells destined to become bone. Collagen type II expression does not occur in these cells compared to autologous chondrocytes. Inducible nitric oxide synthase expression by microfracture cells is likely to damage surrounding articular cartilage in vivo. In conclusion, cells recruited by micro-fracture are inferior for cartilage regeneration purposes to those from cartilage biopsies.

Journal Article↗
PubMed2001

Corona phenomenon as visual aura symptom in migraine.

The visual illusion of a typical corona phenomenon was represented as a visual migraine aura symptom in six of 562 Migraine Art pictures, whereas another five pictures illustrated atypical variants of the said illusion. The extra edges of the corona phenomenon are commonly seen around the perceptual images of objects, but in atypical cases they can similarly surround illusory images and both elementary and complex hallucinatory images. The corona phenomenon is strongly associated with visual loss and the presence of elementary geometric hallucinations.

Adolescent↗
PubMed2001

Ultrasound-assisted lipoplasty.

BACKGROUND: Ultrasound-assisted lipoplasty (UAL) has been associated with particular types of complications and uncertain long-term effects arising from interactions between ultrasonic energy and living tissue. The present review seeks to address these issues. METHODS: Search strategy Three search strategies were devised to retrieve literature from Medline, Current Contents, Embase and Cochrane Library databases up until April 2000. Study selection Inclusion of papers was largely determined using a predetermined protocol. English language papers were selected. Acceptable study designs included randomized controlled trials, controlled clinical trials, case series or case reports. Data collection and analysis Thirty-six papers met the inclusion criteria. They were tabulated and critically appraised in terms of methodology and design, outcomes, and the possible influence of bias, confounding and chance. Other papers were also included to provide background material. RESULTS: There was little high-level evidence available comparing UAL and suction-assisted lipoplasty (SAL), with no conclusive evidence that UAL has a safety benefit, although low-quality evidence suggests that UAL is associated with reduced surgeon fatigue as well as increased operating times, slower aspiration rates and an increased learning curve. There is inadequate evidence to determine whether the theoretical potential for DNA damage from ultrasound is realized in the clinical setting. CONCLUSIONS: The evidence base for UAL is inadequate to determine the procedure's safety and efficacy. The potential for DNA damage must be investigated with appropriate in vivo animal models. Recommendations for the safe use of UAL are discussed.

Adipose Tissue↗
PubMed2001

Recurrent Lilliputian hallucinations as visual aura symptom in migraine.

Since her early 30s a 72-year-old female migraine sufferer has experienced recurrent episodes of Lilliputian hallucinations occurring at the peak of her severe migraine attacks and lasting between 2 min and 5 min, suggesting that her miniature hallucinations represent a visual migraine aura symptom. The existence of Lilliputian hallucinations of a migrainous nature is confirmed by four similar case reports reviewed from the migraine literature. The occurrence of similar Lilliputian hallucinations in the syndrome of peduncular hallucinosis, due to mesencephalic and/or thalamic lesions, supports the notion that the patient's recurrent Lilliputian hallucinations might have been aura symptoms of basilar migraine.

Aged↗
PubMed2001

The relationship between structures and in vitro properties of a polyanhydride implant containing gentamicin sulfate.

Laboratory scale injection-molding equipment was utilized to fabricate an implant consisting of poly(FAD:SA 1:1) and 20% (w/w) gentamicin sulfate. Characterizations were performed to determine the molecular weight and glass transition temperature of poly(FAD:SA 1:1). A study was carried out to investigate the relationships between the in vitro performance, morphology, and micro-structures of the molded implants. It was found that implants produced with different structures exhibited different physical integrities in water, i.e., cracking or non-cracking. For the non-cracking implants, a skin-core structure formed by an oriented skin layer was observed under a polarized light microscope. The same morphology was not seen in the cracking implants. The crystal orientation in the skin layer of the non-cracking implants was further identified using a wide-angle x-ray diffraction method (WAXD). No crystal orientation could be found in the cracking implants by WAXD. Furthermore, studies were carried out to evaluate the in vitro drug release for implants showing different degrees of integrity in water. The in vitro drug release of the cracking implants was markedly faster than that of the non-cracking implants due to the pronounced initial drug-burst effect as a result of crack formation in the implants.

Absorbable Implants↗
PubMed2001

Alternative models for carcinogenicity testing.

The International Conference on Harmonisation Expert Working Group on Safety suggested that under certain circumstances, data from alternative assays could be used in safety evaluation in place of a second bioassay. Several alternatives were discussed. Six of these models were evaluated in a collaborative effort under the auspices of the Health and Environmental Sciences Institute (HESI) branch of the International Life Sciences Institute (ILSI). Standard protocols, pathology review, and statistical evaluations were developed. Twenty-one chemicals were evaluated, including genotoxic, nongenotoxic, carcinogenic, and noncarcinogenic chemicals. The models that were evaluated included the p53(+/-) heterozygous knockout mouse, the rasH2 transgenic mouse, the TgAC transgenic mouse (dermal and oral administration), the homozygous XPA knockout and the XPA/p53 knockout mouse models. Also evaluated were the neonatal mouse models and the Syrian Hamster Embryo (SHE) transformation assay. The results of this comprehensive study suggest that some of these models might be useful in hazard identification if used in conjunction with information from other sources in a weight of evidence, integrated analysis approach to risk assessment.

Animals↗
PubMed2001

Treatment of exercise-induced muscle injury via hyperbaric oxygen therapy.

PURPOSE: This study examined the role of hyperbaric oxygen therapy (HBO) in the treatment of exercise-induced muscle injury. METHODS: 21 college-aged male volunteers were assigned to three groups: control, immediate HBO (iHBO), and delayed HBO (dHBO). All subjects performed 6 sets (10 repetitions per set) of eccentric repetitions with a load equivalent to 120% of their concentric maximum. HBO treatments consisted of 100-min exposure to 2.5 ATA and 100% oxygen with intermittent breathing of ambient air (30 min at 100% O2, 5 min at 20.93% O2). HBO treatments began either 2 (iHBO) or 24 h (dHBO) postexercise and were administered daily through day 4 postexercise. Forearm flexor cross-sectional area (CSA) and T2 relaxation time via magnetic resonance imaging (MRI) were assessed at baseline, 2, 7, and 15 d postinjury. Isometric strength and rating of perceived soreness of the forearm flexors were assessed at baseline, 1, 2, 3, 4, 7, and 15 d postinjury. Serum creatine kinase (CK) was assessed on day 0 and on days 1, 2, 7, and 15 postinjury. RESULTS: Mean baseline CSA values were: 2016.3, 1888.5, and 1972.2 mm2 for control, iHBO, and dHBO, respectively. All groups showed significant increases in CSA in response to injury (21% at 2 d, 18% at 7 d) (P < 0.0001), but there were no significant differences between groups (P = 0.438). Mean baseline T2 relaxation times were: 26.18, 26.28, and 27.43 msec for control, iHBO, and dHBO, respectively. Significant increases in T2 relaxation time were observed for all groups (64% at 2 d, 66% at 7 d, and 28% at 15 d) (P < 0.0001), but there were no significant differences between groups (P = 0.692). Isometric strength (P < 0.0001), serum CK levels (P = 0.0007), and rating of perceived soreness (P < 0.0001) also indicated significant muscle injury for all groups, but there were no differences between groups (P = 0.459, P = 0.943, and P = 0.448, respectively). CONCLUSION: These results suggest that hyperbaric oxygen therapy was not effective in the treatment of exercise-induced muscle injury as indicated by the markers evaluated.

Adult↗
PubMed2001

Identification of protein kinases dysregulated in CD4(+) T cells in pathogenic versus apathogenic simian immunodeficiency virus infection.

Human immunodeficiency virus infection in humans and simian immunodeficiency virus (SIV) infection in rhesus macaques (RM) leads to a generalized loss of immune responses involving perturbations in T-cell receptor (TCR) signaling. In contrast, naturally SIV-infected sooty mangabeys (SM) remain asymptomatic and retain immune responses despite relatively high viral loads. However, SIV infection in both RM and SM led to similar decreases in TCR-induced Lck phosphorylation. In this study, a protein tyrosine kinase (PTK) differential display method was utilized to characterize the effects of in vivo SIV infection on key signaling molecules of the CD4(+) T-cell signaling pathways. The CD4(+) T cells from SIV-infected RM, but not SIV-infected SM, showed chronic downregulation of baseline expression of MLK3, PRK, and GSK3, and symptomatically SIV-infected RM showed similar downregulation of MKK3. In vitro TCR stimulation with or without CD28 costimulation of CD4(+) T cells did not lead to the enhancement of gene transcription of these PTKs. While the CD4(+) T cells from SIV-infected RM showed a significant increase of the baseline and anti-TCR-mediated ROR2 transcription, SIV infection in SM led to substantially decreased anti-TCR-stimulated ROR2 transcription. TCR stimulation of CD4(+) T cells from SIV-infected RM (but not SIV-infected SM) led to the repression of CaMKKbeta and the induction of gene transcription of MLK2. Studies of the function of these molecules in T-cell signaling may lead to the identification of potential targets for specific intervention, leading to the restoration of T-cell responses.

Animals↗
PubMed2001

Regulation of gastric epithelial cell development revealed in H(+)/K(+)-ATPase beta-subunit- and gastrin-deficient mice.

The gastric H(+)/K(+)-ATPase is essential for normal development of parietal cells. Here we have directly assessed the role of the H(+)/K(+)-ATPase beta-subunit (H/K-beta) on epithelial cell development by detailed quantitation of the epithelial cell types of the gastric mucosa of H/K-beta-deficient mice. H/K-beta-deficient mice had a 3.1-fold increase in the number of immature cells per gastric unit; however, the numbers of surface mucous and parietal cells were similar to those in the gastric units of wild-type mice. The effect of elevated gastrin levels in the H/K-beta-deficient mice was determined by producing mice that are also deficient in gastrin. We demonstrated that the increased production of immature cells and resulting hypertrophy is caused by the overproduction of gastrin. However, the depletion of zymogenic cells, which is another feature of H/K-beta-deficient mice, is independent of hypergastrinemia. Significantly, parietal cells of H/K-beta- and gastrin-deficient mice had abnormal secretory membranes and were devoid of resting tubulovesicular membranes. Together these data suggest a homeostatic mechanism limiting the number of immature cells that can develop into end-stage epithelial cells and indicate a direct role for H/K-beta in the development of mature parietal cells.

Animals↗
PubMed2001

Role of FGF9 and FGF receptor 3 in osteochondroma formation.

Osteochondromas are chondro-osseous protuberances that occur in metaphyses of long bones. The cartilaginous cap is assumed to be responsible for the growth of the lesions during childhood and adolescence, but mitotic figures are rarely seen in the cap. Therefore, another cell population, probably mesenchymal cells, is responsible for proliferation and growth. Residual mesenchymal cells capable of rapid proliferation are difficult to detect due to lack of specific histologic features. Two specific markers for mesenchymal cells, FGF receptor 3 (FGFR3) and collagen type IIa, have been described. Osteochondroma mesenchymal cells are found in the soft tissues overlying the cartilage cap. The surrounding areas of typical cartilage are negative for both mesenchymal cell associated antigens. The soft tissues overlying the cartilage do not have cartilaginous features. The undifferentiated cells overlying the exostosis yield in culture a rapidly proliferating homogenous population of fibroblast-like cells. Expression at the mRNA level of FGF9, FGFR3, and collagen type IIa is found in these cells, but not in skin fibroblasts from afflicted or healthy individuals. Exogenous administration of TGFbeta1 to cultures of hereditary multiple exostosis eliminates FGF9 expression. These results indicate fibrous regions contain the mesenchymal cells responsible for osteochondroma growth.

Bone Neoplasms↗
PubMed2001

Serum leptin concentration in a rural African population.

OBJECTIVE: To determine the serum leptin concentration in a cohort of healthy rural Africans, it's relation to the commonly used anthropometric measures of obesity and its relation to the patterns of distribution of fat in the body. DESIGN: A cross-sectional population survey. SETTING: Baziya area, Transkei region, South Africa. SUBJECTS: One hundred and thirty five (79 females and 56 males) healthy adults from the Baziya location, Transkei aged 17-70 years were selected by stratified random sampling. MEASUREMENTS: Anthropometric measurements of height, weight, and skinfold thickness at the biceps, triceps, subscapular and suprailiac sites and derived total body fat and ratios of fat distribution. Fasting serum leptin using the sandwich ELISA method. RESULTS: Skinfold measurement was significantly higher in the females than the males throughout the age range. Centralization of body fat to the trunk was significantly greater in the males than in the females. Serum leptin concentration was higher in the females (mean = 13.5 ng/ml; 95% confidence interval = 10.0-16.8) than in the males (mean = 5.2 ng/ml; 95% confidence interval = 2.8-7.6) (p < 0.001). The gender difference in leptin concentration persists when expressed as serum leptin per kilogram of fat mass (serum leptin (ng/ml)/FM). The mean value for the males was 5.1 ng/ml/kg (95% confidence interval = 2.9-7.3) compared to the mean value for females of 6.9 ng/ml/kg (95% confidence interval = 5.4-8.3) (p < 0.05). In the females BMI and body fat were significant contributors to the variance in serum leptin. In the males the upper-to-lower trunk skinfold thickness ratio and BMI were the significant contributors to the variance in serum leptin concentration. Deposition of fat in the abdomen did not have a significant contribution to the variance in circulating leptin in both sexes. CONCLUSION: Serum leptin concentration in rural Africans is similar to that observed in other communities with the exception that regional fat distribution has a significant influence on the leptin levels in the males.

Adolescent↗
PubMed2001

99mTc-MIBI scintigraphy in musculoskeletal tumors.

UNLABELLED: The aim of this study was to assess the value of 99mTc-hexakis2-methoxyisobutylisonitrile (MIBI) scintigraphy in patients with clinical and radiologic features of primary or metastatic musculoskeletal tumors. METHODS: The scintigraphic findings for 84 patients were compared with the surgical and histologic findings. Each patient underwent three-phase bone scanning with 99mTc-methylene diphosphonate (MDP) and dynamic and static MIBI scintigraphy. The MIBI scans were evaluated by visual and quantitative analysis. The count ratio of the lesion to the adjacent or contralateral normal area (L/N) was calculated from the region of interest drawn on the MIBI scan. The Mann-Whitney test was used to determine the differences between the uptake ratios of malignant and benign lesions. RESULTS: Although increased MDP uptake was not specific for bone malignancy, a significant difference was found between benign tumors (L/N = 1.22 +/- 0.43) and malignant tumors (L/N = 2.25 +/- 1.03) on MIBI scans. Sensitivity and specificity were 81% and 87%, respectively. Forty-six of 53 proven benign lesions did not show significant MIBI uptake. The negative predictive value was 88%. In all seven sites of pathologic fracture, significant uptake was seen. However, three malignant lesions were not detected by MIBI scintigraphy, whereas seven benign lesions showed false-positive results. CONCLUSION: The major diagnostic worth of MIBI scintigraphy is its high negative predictive value. Although not capable of replacing tissue biopsy as a definitive diagnostic modality for musculoskeletal neoplasms, MIBI scintigraphy does appear to have a role in better preoperative assessment and in distinguishing between pathologic and simple fractures.

Bone Neoplasms↗
PubMed2001

Hemarthrosis as initial presentation of scurvy.

Vitamin C deficiency or scurvy is a disease now rarely seen except for certain populations at risk. When it occurs, diagnosis can be difficult as it can mimic other disorders. Its manifestations are primarily due to an abnormality in collagen formation causing bleeding in the skin, joints, muscles, or gastrointestinal tract and dystrophic hair deformities. We describe a case of scurvy in a 43-year-old man who presented with new onset hemarthrosis with no history of bleeding disorder. He was found to have perifollicular hyperpigmentation and corkscrew hairs, highly suggestive of scurvy. He admitted to completely eliminating fruits and vegetables from his diet and his serum vitamin C level was markedly decreased. Treatment with daily vitamin C supplement led to relief of symptoms and resolution of skin changes.

Adult↗