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Biomedical subjects

S A Alexander

Publications and source records attributed to S A Alexander.

16 recordsLinked to original sources
PubMed1992

Diagnosis and treatment planning in orthodontics.

Orthodontic diagnosis and treatment planning topics either reflect the new technology available in the health fields or reiterate the older material that reemerges from generation to generation. Issues that are presented still display the dissatisfaction of their examiners in terms of frustration and equivocal results. Well-controlled prospective and retrospective studies require documented long-term evaluations to be clinically useful as an aid in diagnosis or formulation of treatment planning principles.

Cephalometry↗
PubMed1992

Delayed retraction utilizing ceramic brackets.

The purpose of this study was to evaluate clinically the delay in retraction utilizing ceramic orthodontic brackets versus stainless steel brackets. Twelve patients with Class II division 1 malocclusions requiring the extraction of maxillary first premolars were employed in the study. The following observations were obtained: 1. Retraction of all cuspids bonded with ceramic brackets displayed delayed retraction when compared to their stainless steel counterparts. 2. Over a 36 week period, teeth bonded with stainless steel brackets travelled 2mm farther or 1.8 times faster than those bonded with ceramic brackets.

Adolescent↗
PubMed1991

Effects of pHi and pHe on membrane currents recorded with the perforated-patch method from cultured chemoreceptors of the rat carotid body.

In this study we investigated the effects of intracellular pH (pHi) and extracellular pH (pHe) on whole-cell currents in cultured glomus cells of the rat carotid body and small, intensely fluorescent (SIF) cells of sympathetic ganglia. The use of the perforated-patch recording technique along with established methods of cytoplasmic acidification allowed us to carry out this study without greatly disturbing the cell's endogenous pH regulatory mechanisms. A reversible decrease in the outward K+ current (20-30%) was observed during acid loading of glomus (and SIF cells) using the K+/H+ ionophore nigericin (3 microM) and acetate (20 mM). A reversible decrease in the inward Na+ current was also observed in both cell types during nigericin application. Application of amiloride (0.1 mM) to the bathing solution inhibited recovery of the K+ current from an acid load implicating the Na+/H+ antiporter as a mechanism involved in pH homeostasis in glomus cells. A reversible decrease in K+ and Na+ currents was also observed during changes in pHe from 7.4 to 6.5. The effects of pHi on membrane currents, Ca2+ levels, and neurotransmitter release are discussed in the context of the role of glomus cells as primary transducers of chemosensory stimuli in arterial blood.

Acetates↗
PubMed1991

Effects of orthodontic attachments on the gingival health of permanent second molars.

The aim of this study was to evaluate the effect of cemented bands and enamel bonded attachments on the gingival health of second molars. In 23 patients the right upper and lower second molars were banded, while the left upper and lower second molars were bonded. The plaque index, the gingival index, and pocket depths were greater and statistically significant on the right side, indicative of increased inflammatory activity where bands were cemented. Once the appliances were removed, both areas returned to pretreatment levels.

Adolescent↗
PubMed1975

Sex steroids and epidermal glands in two species of gekkonine lizards.

In vivo and in vitro experiments on the endocrine relationships of epidermal glands in the tokay Gekko gecko, and the common house gecko Hemidactylus bowringii are reported. The results show that certain aspects of beta-gland differentiation involve a synergistic action between androgens and those hormones responsible for controlling the normal shedding cycle, while other aspects are solely under androgenic control. Pre-anal organ activity appears to be solely under androgenic control.

Animals↗