The beta-receptors in the rat pancreas.
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Animals↗
Biomedical subjects
R E Hernandez
Publications and source records attributed to R E Hernandez.
Chronobiological aspects of blood glucose regulation: a new scope for the study of diabetes mellitus.
The levels of blood glucose undergo circadian variations in every species studied. Such rhythm is the consequence of the oscillation in the rate of provision and consumption of glucose. The liver plays an important role in this rhythm, retaining or releasing glucose from or to the circulation. The driving forces for this glucose flow come from outside (food intake) and inside (neural and hormonal control) the body. This blood glucose control might be referred as homeorheusis rather than homeostasis. The final regulatory adjustment of this precise and delicate mechanism is probably located around the suprachiasmatic and other hypothalamic nuclei. In diseases such as diabetes mellitus, where there is an alteration in the circadian rhythm of blood glucose, one of the main goals of treatment must be its restoration to normal levels.
Animals↗
Circadian susceptibility rhythm of the rat to alloxan.
The susceptibility of rats to alloxan undergoes a circadin rhythm. The toxicity rhythm, presumably involving injury to liver, kidney and other sites, pancreatic beta-cells in particular, is demonstrated in pooled data from 370 mature inbred Fischer or Minnesota Sprague-Dawley rats of both sexes kept in light from 06(00) to 18(00) alternating with darkness, some with free access to Purina laboratory chow with tap water at all times and some other rats subjected to one of three starvation schedules: 1) a 28-h fast before an intravenous alloxan injection; 2) a 28-h fast, except for a 4-h ad libitum feeding before injection; 3) a 28-h fast, except for a 4-h pre-injection tube-feeding of Nutrament (Mead and Johnson, Evansville, Indiana), 1.5 ml/100 g body weight. Survival time data on an additional 200 inbred Fischer rats reveal, next, that susceptibility to alloxan increases as the starvation span is lengthened from 24 to 84 h. The shortening in survival time indicative of this susceptibility increase is nonlinear; a circadian rhythmic change in susceptibility to alloxan is seen as a statistically significant wave-form indicative of the basic (persisting) rhythm, of applied interest as well to students of experimental diabetes.
Alloxan↗
The use of pterygomaxillary implants in the partially edentulous patient: a preliminary report.
One hundred eighty-seven implants were placed in the maxillary posterior areas of 44 partially edentulous patients (29 female; 15 male). The mean age was 62 years (range 36 to 82 years). Fifty-one of the 187 implants were placed in the pterygomaxillary area and further restored with fixed prostheses. The mean number of implants per prosthesis was 3.7 (range 1 to 6) for the maxillary posterior area. These 51 implants are the subject of this report. During stage II surgery and before loading, six implants were not osseointegrated and were removed. After a mean loading period of 12.6 months (range 1 to 63 months), one additional implant was lost. Seven of 51 implants were removed (13.7%). Failure rates according to implant size and bone quality were also analyzed. The average loss of marginal bone height was 1.3 mm on the mesial and 1.1 mm on the distal surfaces between 1 and 3 years of loading. This study demonstrates the possible and successful use of the pterygomaxillary site for implant placement.
Adult↗
A comparative study of one implant versus two replacing a single molar.
A comparative study between one and two Brånemark implants replacing a single molar was conducted. Forty-seven individuals comprised two groups of 22 patients treated with one implant and 25 with two implants. A total of 72 implants were placed, 66 (92%) in the mandible and six (8%) in the maxilla. After the first year of function, the success rate was 99%, with only one implant lost. Between the second- and third-year follow-ups, 100% of the implants continued to function in the remaining 46 patients, giving a 3-year cumulative success rate of 99%. The marginal bone loss between 1 and 3 years of function was 0.10 mm (SD 0.20) for the group with one implant and 0.24 mm (SD 0.20) for the group with two implants. No changes were observed in the Sulcus Bleeding Index during the 3-year follow-up. Prosthesis mobility or screw loosening was the most frequent complication and was predominant in the group using one implant (48%), but was substantially reduced in the group using two implants (8%). These mechanical problems, using one implant only, seem to be preventable using a stronger screw joint (CeraOne abutment). Precise centric occlusal contact was established and maintained over the study period, which was thought to contribute to the very high success rate for the single-implant-supported molars, despite their high degree of mechanical problems. This study suggests that implant-supported molars can be effective therapy, and the results confirm the biomechanical analysis that two implants provide more advantageous support than does one.
Adult↗