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Biomedical subjects

J B Gonzalez

Publications and source records attributed to J B Gonzalez.

16 recordsLinked to original sources
PubMed2000

Cortical reorganization in linear nevus sebaceous syndrome: a multimodality neuroimaging study.

The authors report the findings of multimodal structural, functional, and metabolic imaging in a patient with linear nevus sebaceous syndrome, intractable seizures, and right megalencephaly. Despite nearly continuous paroxysmal electrical activity from the megalencephalic region, imaging studies suggested nonfunctional tissue in this region with reorganization of cortical function to the unaffected ipsilateral hemisphere. Hemispherectomy has been successfully performed in previous patients; however, it could have led to marked left hemiparesis with significant functional morbidity in this patient because of ipsilateral reorganization of the primary motor cortex.

Adult↗
PubMed1999

Optimal position for the one-bone forearm. An analysis using a hinged brace in normal subjects.

The purpose of the present study was to determine whether there is an optimal position for fixation of the one-bone forearm. Eight normal individuals were fitted with a hinged brace which fixed the position of pronation and supination and underwent functional hand testing using the tests of Jebsen et al. Our results indicate that a one-bone forearm in a position of 30 degrees of pronation will provide the best function for writing and working with small objects using the dominant arm.

Adult↗
PubMed1993

A 7-year follow-up of newborns vaccinated against hepatitis B.

Of 79 children born to asymptomatic HBsAg chronic carrier mothers and vaccinated at birth against hepatitis B, a total of 71, 66 and 56 could be serologically assessed after 1, 5 and 7 years, respectively. Anti-HBs titres (geometric means) of responders decreased from 2475 to 143 IU l-1 between 1 and 5 years of age and dropped to 82 IU l-1 by 7 years. At this time, a booster dose given to 34 children who showed anti-HBs titres lower or slightly higher than 100 IU l-1 significantly increased titres from 34 to 2985 IU l-1 (p < 0.001). Children whose titres following perinatal vaccination reached 100 to 1000 IU l-1 or above 1000 IU l-1 maintained protective levels (> 10 IU l-1) for 3 and 5 years, respectively. As in adults, anti-HBs titres recorded after the initial vaccination indicate the time at which infants should receive booster vaccination.

Child↗
PubMed1980

Standardization of a polyurethane elastomer for facial prostheses.

This study has shown that the polyester urethane elastomers are soft and flexible, characteristics which are desirable for simulating soft facial tissue. In addition, this material was found to have a larger resistance-to-tear when compared with othe materials. The physical and mechanical properties are very sensitive to the composition and the amount of catalyst added. Less influence on the elastomer properties was noticed for the range of temperatures at which it was polymerized. The range of curing time used in this study shows no significant statistical difference on the elastomer properties. Future studies will be directed toward the polymerization of the material at a wider range of times and temperatures to determine the effects at the low and high ends of the range.

Chemical Phenomena↗
PubMed1978

Polyurethane elastomers for facial prostheses.

A review of the polyurethane elastomers used for facial prostheses has been presented. A description of the casting technique was given. The materials require accuracy and care in handling to insure the successful casting of a prosthesis. They seem to simulate the characteristics of the facial tissues and are more durable and comfortable than previously used materials. Over 300 patients have been exposed to or treated with these materials without evidencing significant adverse tissue reaction. In spite of the improvements that these materials present over previous ones (PVC and silicones), much work is still required to understand their behavior and their physical and mechanical characteristics and to compensate for the metameric phenomenon.

Biocompatible Materials↗
PubMed1978

Physical and mechanical behavior of polyurethane elastomer formulations used for facial prostheses.

The initial results of this study of the physical and mechanical behavior of polyurethanes used for facial prostheses are presented. The parameters studied were surface hardness, modulus of elasticity (M), strength (S), percentage of elongation, and S/M ratio. Results showed that the physical and mechanical behavior of the polyurethanes can be altered by variations in the basic composition of the material accomplished through changes in the ratio of Part A to Part B and by the addition of catalysts. Properties of compositions with low quantities of Part B (isocyanate) and no catalyst reached or approximated those parameters proposed as ideal goals to simulate living tissue. When preparing polyurethane material, proper mixing is essential to avoid entrapment of air and phase separation of the catalyst. These conditions, which may render the prostheses less durable, are masked by the addition of colorants in the prearation of a sample for clinical application.

Chemical Phenomena↗
PubMed1978

Recently developed elastomers for facial prostheses.

Ever since ancient times, man has been searching for the proper artificial substitute for living tissue. This has been a most frustrating and challenging task for the scientific community involved. Prosthetic restoration is the only alternative to reconstructive surgery for the facially deformed. This paper reviews the progress that has been made in recent years in developing a suitable material for the prosthetic restoration of facial defects. There is encouraging evidence that the development of an ideal material for facial prostheses is an attainable goal.

Acrylic Resins↗
PubMed1977

Use of tissue conditioners and resilient liners.

The application of elastomer polymers in the prevention and treatment of chronic tissue irritation from dentures is an excellent alternative to the use of hard polymer resins and it is useful for preserving the health of the remaining denture-supporting tissues. Wider applications will be found in the future once the present shortcomings of the available materials are overcome, whether by improving these materials or by developing new ones. Specific uses for these materials have been outlined with an awareness that the readers may be able to add other applications to the list. At the same time, it is not the intent of this article to imply that the use of elastomer polymers is the panacea for all prosthodontic problems or that fundamental principles can be neglected.

Acrylates↗
PubMedDate not supplied

Polyurethane elastomer as a possible resilient material for denture protheses: a microbiological evaluation.

A polyurethane elastomer was microbiologically evaluated in vitro for its potential use in resilient denture liners. Specimens were immersed in suspensions of ten selected oral microorganisms; this was followed by viable cell counts at intervals during a 16-week period. Results indicated that the polyurethane neither supported the growth of the organisms nor was it degraded.

Candida↗