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T J Harrop

Publications and source records attributed to T J Harrop.

15 recordsLinked to original sources
PubMed1987

Electron microscopy of watery vacuole formation in rat parotid acinar cells during reflex stimulation.

Reflex stimulation from eating hard chow caused variable degrees of watery vacuolation, most conspicuously in animals that had eaten the most food; this was accentuated by eating in the cold. Some vacuolation occurred in the absence of sympathetic impulses but there was much more in glands receiving both parasympathetic and sympathetic impulses. Vacuole formation was often associated with, but not dependent upon, a degree of acinar degranulation. The vacuoles appeared to originate either from the inner side of the Golgi apparatus, near condensing vacuoles, or from ballooning within the rough endoplasmic reticulum; some vacuoles appeared to arise close to secretory granules. Certain cellular components, including secretory granules, entered the contents of vacuoles, which also often had connections with lumina. Many basally-located vacuoles were large and bounded only by a tenuous layer of cytoplasm which was contained by the basal lamina. Vacuole formation may be related to strong stimulation of susceptible cells, which occurs to a variable extent during natural reflex secretion, as well as during artificial stimulation. Thus, under normal conditions, certain macromolecular components might enter saliva via this route and not solely by exocytosis. Leakages from acinar vacuoles could also occur into the glandular interstices, accounting for some of the parotid amylase found in peripheral blood.

Animals↗
PubMed1986

A comparison of physical characteristics of six hard denture reline materials.

Six rigid autopolymerizing acrylic resins were examined to determine and compare the cost per reline, the curing temperatures, the setting times, and the porosity of each material. The cost per reline ranged from $0.63 to $1.55. Three product groups had significantly different mean setting times, and two groups had significantly different mean setting temperatures. SEM cross-sections of each product revealed an apparently porous-free solid mass of acrylic resin, which in two products was overlayed by a thin porous surface layer. The physical characteristics of any one product did not indicate clinical superiority.

Acrylic Resins↗
PubMed1985

Secretion of parotid acinar granules in rats during reflex stimulation after chronic sympathectomy.

After chronic post-ganglionic sympathectomy the ultrastructure of 'resting' parotid acinar cells in rats remains relatively normal, despite the loss of nerve impulses normally causing secretion of acinar granules from this gland. The question whether eating hard chow still induces some acinar degranulation weeks after superior cervical ganglionectomy, has now been tested. It was found that scattered pockets of parotid acinar degranulation did occur. Some of these changes after unilateral denervation may have been attributable to intact sympathetic nerves arising from the contralateral superior cervical ganglion (Alm, Asking, Emmelin & Gjörstrup, 1984), but this cannot explain similar changes that occurred in glands after bilateral ganglionectomy. The possibility that some degranulation may be induced by circulating catecholamines was tested, 9-16 weeks after unilateral sympathectomy, by placing animals in the cold (0-4 degrees C) for 2 h before removal of tissues. Animals not given food during that time showed no evidence of parotid acinar degranulation, but those given hard chow showed extensive acinar degranulation in both parotid glands. On the sympathectomized side the degranulation was, however, less uniform and more patchy than on the side with an intact innervation. These findings agree with he belief that circulating catecholamines can, at times, induce degranulation of parotid acinar cells made supersensitive by chronic sympathetic denervation but, for it to occur, the cells must also be receiving parasympathetic stimulation at the same time. This interaction probably permits a sufficient turnover of granules to maintain a relative homoeostasis of the parotid acinar cells in rats.

Animals↗
PubMedDate not supplied

An objective evaluation of clinical signs used to assess sedation with intravenous diazepam.

In the majority of dental schools there are insufficient numbers of clinical patients for all students to receive optimal experience in intravenous sedation. This investigation was carried out to assess whether the signs and symptoms for intravenous sedation taught to the undergraduates were sufficiently objective to ensure that this clinical deficiency was not detrimental to competency of the graduating student. The signs of ptosis, altered speech and blurred vision were used by both experienced dentists and novice students to assess the level of intravenous sedation. Blurred vision was found to be unreliable while altered speech was more accurate than ptosis. The more experienced the operator the earlier the signs were observed.The "Guidelines for the Teaching of Pain and Anxiety Control in Dentistry" were initially formulated by the American Dental Association in 1971 and revised in 1978(1) while similar guidelines were accepted by the House of Delegates of the Association of the Canadian Faculties of Dentistry in 1975(2) Both of these documents outlined the course of instructions necessary for the teaching of all modalities of pain and apprehension control at the undergraduate, postgraduate and continuing education level. Implementation of these guidelines at the undergraduate level has proven to be particularly difficult in the area of intravenous sedation because of the lack of suitable patients. This has resulted in many students graduating, having had little practical experience in sedating a patient with an intravenous drug. It is the hope of educators in this field that lectures, seminars, and demonstrations given to dental students are sufficient to overcome this deficiency.Since the most critical clinical aspect of intravenous sedation is titrating the amount of drug required without overdosing or underdosing the patient, it was decided to investigate this ability in students with no clinical experience with intravenous diazepam. Although many drugs and techniques are advocated(3,4,5) it was decided to limit the study to intravenous diazepam as it may be used alone and has a high therapeutic index.With the introduction of diazepam to clinical practice the symptomatology of the drug was established and described by clinicians.(6,7) Objective methods of measuring recovery from diazepam have been described by several authors(8,9,10) but the signs and symptoms used to assess the initial level of sedation have been subjective. This can be attributed to the fact that sedation is an ill-defined clinical effect and can, therefore, only be calibrated by individual arbitary signs. The most frequently used signs for intravenous diazepam sedation are ptosis, also referred to as "the Verrill sign,"(11) altered speech and blurred vision.(7) This investigation was designed to test the reliability of these signs and to examine the variability of observations between clinicians and students.

Adult↗