Biomedical subjects

J Atkinson

Publications and source records attributed to J Atkinson.

At least 235 records · Page 13Linked to original sources

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New techniques for assessing vision in infants and young children.

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Age Factors↗

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Blood pressure overshoot under pentobarbitone anaesthesia following a single dose of clonidine in rats.

1. Withdrawal of chronic antihypertensive therapy with clonidine is known to produce a blood pressure overshoot. It has been reported that the same may occur after a single dose of clonidine. 2. A single, intramuscular dose of clonidine (0.05 mg/kg) produced an overshoot in blood pressure, on the day following administration, in normotensive rats anaesthetized with sodium pentobarbitone. 3. No rebound elevation of mean arterial pressure or of heart rate occurred in conscious, normotensive, spontaneously hypertensive or renal hypertensive rats following this dose of clonidine, nor did it occur in rats anaesthetized with ether. 4. It is suggested that the overshoot phenomenon in rats under barbiturate anaesthesia may involve an interaction between an effect of clonidine and the barbiturate.

Anesthesia, General↗

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Aortic calcification produced by vitamin D3 plus nicotine.

Calcification of the elastic arteries of the young rat by treatment with vitamin D and nicotine (VDN) has been proposed as an animal model of arterial calcification associated with age and age-related vascular pathology in man. The calcium-binding protein, S-100, which is found in human atherosclerotic lesions was associated with medial calcification of the aorta in VDN rats, especially in cases of severe calcification. Calcification (total calcium content: 366 +/- 87, n = 12 in VDN vs. 24 +/- 2 micromol g(-1) aortic dry weight in controls, n = 13) involved elastocalcinosis leading to elastolysis as revealed by a fall in the amount of desmosine and isodesmosine in the aortic wall (266 +/- 17 and 254 +/- 15 in VDN vs. 655 +/- 56 and 588 +/- 30 microg g(-1) aortic dry weight in controls). The decrease in elastin was associated with an increase in the stiffness of the aortic wall (elastic modulus: 15.1 +/- 1.8 in VDN vs. 6.7 +/- 0.5 10(6) dyn cm(-2) in controls), an increase in end-systolic stress (central systolic aortic pressure: 152 +/- 6 in VDN vs. 136 +/- 2 mm Hg in controls) (at a normotensive mean pressure level) and left ventricular hypertrophy (heart weight/body weight 2.51 +/- 0.10 in VDN vs. 2.24 +/- 0.07 g kg(-1) in controls). In conclusion, the mechanisms and consequences of aortic calcification in VDN show several similarities with calcification occurring in human athero- and arteriosclerosis.

Anesthesia↗

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Transnasal endoscopic approach to the sella turcica.

The transseptal/transsphenoidal approach to the pituitary gland has been the most commonly used approach for resection of pituitary adenomas for the last 50 years. This procedure has a low morbidity and provides direct midline access to the sella and pituitary gland. Recent advancements in endoscopic surgery, however, suggest that a lower morbidity approach to the sella would be possible via transnasal endoscopic route. Prior reports have confirmed effectiveness of this approach to the pituitary gland and we report here an early series of endoscopic transnasal pituitary surgery from our institution. We report seven cases of transnasal endoscopic pituitary surgery. Our technique consists of endoscopic exposure of the sphenoid ostium unilaterally, excision of the posterior septum anterior to the rostrum of the sphenoid sinus with resection of the sphenoid rostrum for bilateral exposure of the sphenoid sinus. A specially designed nasal speculum is positioned to displace the posterior septum and lateralize the middle turbinates, permitting direct midline exposure of the sphenoid sinus and sella. We have progressively modified the technique over the seven cases that we present and will discuss our specific instrumentation, indications, and technique for this procedure. We have encountered one cerebrospinal fluid leak in this series. Patient satisfaction has been high and hospitalization is less than with the conventional transseptal approach, averaging 1 day. Our impression is that the transnasal endoscopic approach to pituitary adenomas is a safe technique with reduced morbidity permitting shortened hospital stay.

Adenoma↗

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