PubMed Health⌕ Search

Biomedical subjects

G Tobias

Publications and source records attributed to G Tobias.

10 recordsLinked to original sources
PubMed2002

Peripheral blood stem cell transplantation for POEMS syndrome.

In common with other plasma cell dyscrasias in which a small tumour burden is associated with severe clinical symptoms (notably systemic AL amyloidosis) the possible benefits of dose intensification are yet to be fully explored in POEMS syndrome. One important issue is whether the toxicity of the procedure is significantly increased in this group. We report two cases of POEMS syndrome with solitary asymptomatic bone lesions treated with high-dose melphalan (200 mg/m(2)) and peripheral blood stem cell (PBSC) rescue. In both cases there was minimal peri-transplant morbidity and a subsequent substantial and maintained improvement in the peripheral neuropathy.

Adult↗
PubMed2001

Injection molding of chondrocyte/alginate constructs in the shape of facial implants.

Over one million patients per year undergo some type of procedure involving cartilage reconstruction. Polymer hydrogels, such as alginate, have been shown to be effective carriers for chondrocytes in subcutaneous cartilage formation. The goal of our current study was to develop a method to create complex structures (nose bridge, chin, etc.) with good dimensional tolerance to form cartilage in specific shapes. Molds of facial implants were prepared using Silastic ERTV. Suspensions of chondrocytes in 2% alginate were gelled by mixing with CaSO(4) (0.2 g/mL) and injected into the molds. Constructs of various cell concentrations (10, 25, and 50 million/mL) were implanted in the dorsal aspect of nude mice and harvested at times up to 30 weeks. Analysis of implanted constructs indicated progressive cartilage formation with time. Proteoglycan and collagen constructs increased with time to approximately 60% that of native tissue. Equilibrium modulus likewise increased with time to 15% that of normal tissue, whereas hydraulic permeability decreased to 20 times that of native tissue. Implants seeded with greater concentrations of cells increased proteoglycan content and collagen content and equilibrium and decreased permeability. Production of shaped cartilage implants by this technique presents several advantages, including good dimensional tolerance, high sample-to-sample reproducibility, and high cell viability. This system may be useful in the large-scale production of precisely shaped cartilage implants.

Absorbable Implants↗
PubMed2001

Age dependence of cellular properties of human septal cartilage: implications for tissue engineering.

BACKGROUND: The persistent need for cartilage replacement material in head and neck surgery has led to novel cell culture methods developed to engineer cartilage. Currently, there is no consensus on an optimal source of cells for these endeavors. OBJECTIVES: To evaluate human nasal cartilage as a potential source of chondrocytes and to determine the effect of donor age on cellular and proliferation characteristics. SUBJECTS: Nasal cartilage specimens were obtained after reconstructive surgery from 46 patients ranging in age from 15 to 60 years. METHODS: Specimens were weighed and chondrocytes were isolated by digestion in 0.2% collagenase type II for 16 hours. Cells were maintained in primary cultures until confluency, then seeded onto polylactic acid-polyglycolic acid scaffolds. Seeding efficiency was determined by quantification of DNA content of seeded constructs by means of Hoechst dye 33258. Specimen weights, cell yields, cell content, and doubling time were also measured and correlated to donor age. RESULTS: Mean (+/-SD) cartilage mass obtained (648 +/- 229 mg) is higher than from typical biopsy specimens of auricular cartilage, and the cellular characteristics show a higher proliferation rate than auricular chondrocytes. Cell yield increased with age, while doubling time decreased with age in samples from patients ranging from 15 to 60 years old. CONCLUSIONS: The use of nasal septal cartilage as a source of cells for tissue engineering may be valid over a wide range of patient ages. The large tissue yield and consequent cell yield make this tissue a potential starting source of chondrocytes for large-volume tissue-engineered implants.

Adolescent↗
PubMed1998

Determination of age in dogs and cats by use of changes in lens reflections and transparency.

OBJECTIVE: To develop and test a noninvasive technique for determining age in dogs and cats on the basis of changes in lens reflections and transparency. ANIMALS: 85 dogs representing 5 breeds and 73 domestic shorthair cats. PROCEDURE: While examining dilated eyes in a darkened room, using a penlight, 2 experienced examiners who were blinded to actual age of animals individually measured the diameter of reflections from the anterior (La) and posterior (Lb) surfaces of the lens and scored lens transparency (Ltr) from 1 (clear) to 5 (severe opacity). Models were developed to predict age on the basis of these measurements. RESULTS: Aging models developed for dogs and cats were as follows: Age(dogs) = 2.197 - 0.070 x (La) + 1.361 x (Lb) + 1.193 x (Ltr) and Age(cats) = 1.988 + 1.024 x (La) + 2.220 x (Lb) + 1.019 x (Ltr), where age was expressed in years, and La and Lb were in millimeters. All variables, except La in dogs, contributed significantly to accuracy of the models. Correlation between predicted and actual ages, as measured by Pearson's product-moment correlation coefficient, was significant in both species (P < 0.0001). Significant differences were not found between examiners or between the first and second evaluations by the same examiner. CONCLUSIONS AND CLINICAL RELEVANCE: A noninvasive technique based on evaluation of lens reflections and transparency can provide clinically useful predictions of age in mature dogs and cats. This technique could be an important tool for veterinarians or humane shelters in determining differential diagnoses and assessing longevity and adoptability of mature animals of unknown age.

Aging↗
PubMed1989

[Effect of carteolol and timolol eyedrops on the pressure tolerance of the optic nerve head].

In a planned, randomized, double blind study ocular perfusion pressures were measured before and after a 3-day regimen of 2% carteolol hydrochloride or 0.5% timolol maleate. A pressure tolerance test was also carried out. The results of this test revealed the critical pressure: it is the artificially increased intraocular pressure at which the visual function (monitored by visually evoked cortical potentials) is reduced to 20% of its initial value. The ocular perfusion pressures are affected by both drugs. They are more clearly reduced by carteolol than by timolol. The critical pressure is affected by both drugs too. After application of carteolol, the critical pressure is clearly lower than after application of timolol. The difference is statistically significant (p less than 0.05).

Adaptation, Physiological↗