Biomedical subjects

E Tan

Publications and source records attributed to E Tan.

150 records · Page 9Linked to original sources

PubMedDate not supplied

Cardiovascular effects of stimulation of neurones within the 'defence area' of the hypothalamus and midbrain of the rabbit.

In anesthetized rabbits, electrical stimulation applied at many sites within the medial hypothalamus and dorsal midbrain elicited a skeletal muscle vasodilatation. Vasodilator responses were only elicited by microinjections of glutamate ions (which excite only cell bodies) into a much more restricted region: the periaqueductal grey (PAG) in the midbrain, and the ventromedial nucleus in the hypothalamus. The results suggest that cell groups within the PAG and ventromedial nucleus are capable of generating skeletal muscle vasodilatation, which is characteristic of the 'defence reaction'. At other sites within the 'defence area', the cardiovascular response to electrical stimulation arises from axons of passage.

Animals↗

PubMedDate not supplied

Intense vasoconstriction and bradycardia evoked by stimulation of neurones within the midbrain ventral tegmentum of the rabbit.

Electrical stimulation of sites in the midbrain ventral tegmental area (VTA) and the lateral hypothalamic area of the anaesthetized rabbit elicited intense vasoconstriction and profound bradycardia. The same effects were elicited by microinjections of glutamate ions into the VTA but not the lateral hypothalamic area. Following baroreceptor denervation, the bradycardic component of the response was greatly reduced, but the vasoconstrictor component was unaffected. It is concluded that the cardiovascular response is generated by excitation of a cell group within the VTA, but within the hypothalamus the response arises from excitation of axons of passage.

Animals↗

PubMedDate not supplied

Experience as a factor in the efficacy of the surgical scrub.

The efficacy of the preoperative surgical scrub has been studied extensively throughout the years. However, to the best of the authors' knowledge, this is the first comparative study between surgeons, residents, operating room personnel, and medical students. This paper demonstrates the efficacy of the surgical scrub and the differences between these groups, as well as presents a simple method of monitoring the effectiveness of the surgical scrub in vivo.

Asepsis↗

PubMedDate not supplied

A study of the surface hardness and dimensional stability of several intermaxillary registration materials.

This study compared the surface hardness, the effect of time on surface hardness, and the dimensional stability of various intermaxillary relationship registration materials. The Shore hardness values of one zinc oxide-eugenol material, one polyether, and seven poly(vinyl siloxane) materials were obtained at 30 minutes and 24 hours after the start of mixing. The dimensional stability of one polyether and seven poly(vinyl siloxane) materials was measured using a standard mold as described in American Dental Association (ADA) Specification No. 19. All materials exhibited relatively high surface hardness despite some statistical differences among them. Four materials possessed higher surface hardness at 24 hours than at 30 minutes. Although the polyether showed significantly lower dimensional stability than the other materials, all materials satisfied the minimum requirement for Type I elastomeric impression material.

Analysis of Variance↗

PubMedDate not supplied

Working times of elastomeric impression materials according to dimensional stability and detail reproduction.

This study was conducted to evaluate the working times of seven elastomeric impression materials according to their detail reproduction and dimensional accuracy. Impressions were made of a standard ADA Specification No. 19 die at 30-second intervals until they were no longer workable. The detail reproduction and dimensional stability of these impressions were evaluated according to the ADA Specification No. 19 criteria and the dimensional stability was analyzed. It was found that the working times of the impression materials according to detail reproduction generally agreed with those estimated according to dimensional stability but not with the manufacturers' suggested working times.

American Dental Association↗

PubMedDate not supplied

Working times of elastomeric impression materials determined by dimensional accuracy.

The working times of five poly(vinyl siloxane) impression materials were estimated by evaluating the dimensional accuracy of stone dies of impressions of a standard model made at successive time intervals. The stainless steel standard model was represented by two abutments having known distances between landmarks in three dimensions. Three dimensions in the x-, y-, and z-axes of the stone dies were measured with a traveling microscope. A time interval was rejected as being within the working time if the percentage change of the resultant dies, in any dimension, was statistically different from those measured from stone dies from previous time intervals. The absolute dimensions of those dies from the rejected time interval also must have exceeded all those from previous time intervals. Results showed that the working times estimated with this method generally were about 30 seconds longer than those recommended by the manufacturers.

Analysis of Variance↗