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Biomedical subjects

A J Cronin

Publications and source records attributed to A J Cronin.

13 recordsLinked to original sources
PubMed2005

Postoperative elevated cortisol excretion is not associated with suppression of 6-sulfatoxymelatonin excretion.

This study tests the hypothesis that elevated postoperative excretion of cortisol is associated with suppression of the nocturnal excretion of 6-sulfatoxymelatonin, the chief metabolite of the circadian hormone, melatonin. Postoperative patients demonstrate circadian rhythm disturbances and suppression of nocturnal melatonin plasma concentration. Since the nocturnal surge in melatonin concentration in normal volunteers is time-locked to the circadian nadir of cortisol concentration, perhaps the attenuation of the nocturnal melatonin surge in postoperative patients results from prolonged elevation in the plasma cortisol concentration. In this observational study performed in 21 patients having unilateral hip or knee arthroplasty, urine was collected every 4 h for the first 48 h after surgery for measurement of urinary 6-sulfatoxymelatonin (EIA) and free cortisol (RIA) excretion. The total (P < 0.05) and peak (P < 0.02) nocturnal 6-sulfatoxymelatonin excretions were lower on the first than the second postoperative night. The nocturnal cortisol nadir preceded the 6-sulfatoxymelatonin surge in 20% of the subjects on night 1 and in 75% of the subjects on night 2. The lack of a consistent relationship between the magnitude or timing of cortisol excretion and 6-sulfatoxymelatonin excretion suggests that cortisol does not mediate postoperative 6-sulfatoxymelatonin suppression.

Adult↗
PubMed2003

Low-dose remifentanil infusion does not impair natural killer cell function in healthy volunteers.

BACKGROUND: Mu opioid agonists suppress natural killer (NK) cell activity in animal models. Studies in human volunteers, however, have yielded conflicting results, with morphine suppressing and fentanyl increasing NK cell activity. This study evaluated the effect of a constant 8-h infusion of remifentanil on NK cell number and function in human volunteers. METHODS: After IRB approval and informed consent was obtained, 10 healthy volunteers underwent an 11 pm to 7 am infusion of saline, and at least 1 week later an infusion of 0.02-0.04 microg x kg(-1) min(-1) remifentanil. Blood was collected at 7 am for measurement of NK cell cytotoxicity using a (51)Cr release assay and measurement of NK cell number using fluorescent flow cytometry. RESULTS: Median and range of the total NK cell cytotoxicity (KU ml(-1)) was 745.0 (498.3-1483.6) on the control morning and 818.6 (238.5-1454.5) on the morning following the remifentanil infusion. Neither the number of NK cells ml(-1) (2.5 x 10(5) (1.4 x 10(5)-4.2 x 10(5)) vs 2.7 x 10(5) (1.1 x 10(5)-4.4 x 10(5))) nor the cytotoxicity per 1000 NK cells (KU 1000 NK cells(-1)) (3.0 (1.8-5.2) vs 2.9 (0.9-6.7)) changed between the control and remifentanil conditions. CONCLUSIONS: An 8-h infusion of remifentanil did not affect NK cell activity in normal volunteers. This result differs from previous findings of morphine-induced NK cell activity suppression and fentanyl-induced NK cell activity enhancement in normal volunteers.

Adult↗
PubMed2001

Postoperative sleep disturbance: influences of opioids and pain in humans.

STUDY OBJECTIVES: To test the hypothesis that opioids and pain contribute independently to postoperative sleep disturbance, 10 women undergoing surgery requiring a low abdominal incision for treatment of benign gynecologic conditions were randomized to receive either epidural opioid (fentanyl) (n=6) or epidural local anesthetic (bupivacaine) (n=4) for intraoperative and postoperative analgesia. DESIGN: N/A. SETTING: N/A. PATIENTS OR PARTICIPANTS: N/A. INTERVENTIONS: N/A. MEASUREMENTS: Polysomnography was performed in a standard patient room on the preoperative and first three postoperative nights. Pain at rest and with coughing was evaluated using a visual-analogue pain scale each evening and morning. RESULTS: On the first postoperative night, rapid eye movement (REM) sleep was abolished in all patients. On the third postoperative night, the mean +/- SE REM sleep time increased significantly (p=.003) to 9.8% +/- 3.1% in the fentanyl group, and 12.9% +/- 3.8% in the bupivacaine group. Conversely, light non-REM (NREM) sleep (%stage 1 + %stage 2) was higher on the first postoperative night and significantly lower on the third postoperative night (p=0.011). Between group comparison revealed only that the mean % slow-wave sleep (SWS) in the fentanyl group (6.0%, 2.0%, and 14.7%) was different from the bupivacaine group (7.8%, 9.1%, and 10.6%) in the postoperative period after adjusting for the preoperative night % SWS (p=0.021). Pain was well controlled in all patients, but was slightly better controlled in the fentanyl group than in the bupivacaine group on postoperative night 2 (p=0.024). There was no statistically significant association between pain score and any polysomnographically defined stage. CONCLUSION: Postoperative patients suffer a profound sleep disturbance even when opioids are avoided and pain is well controlled.

Adult↗
PubMed2000

Melatonin secretion after surgery.

Sleep disturbance is common postoperatively. We examined whether melatonin concentrations were related to this disturbance in seven postoperative patients. Nocturnal concentrations of melatonin were significantly (p=0.005) lower on the first than on the second or third nights after surgery. This finding raises the possibility that melatonin suppression and associated sleep disturbance might be prevented by melatonin replacement.

Adult↗
PubMed1998

Office-based anaesthesia.

Office-based anaesthesia is a young but rapidly growing speciality practice. In patient selection, surgical procedures, and anaesthetic techniques this practice is similar to standard ambulatory surgery; however, the liability and risks of office-based anaesthesia are greater. The anaesthesiologist's major challenge is to insist on patient safety in this developing field.

Journal Article↗
PubMed1992

Complications of use of carbon fibre in the temporomandibular joint: a case report.

The aetiology of recurrent temporomandibular joint dislocation is numerous. A case is described of frequent dislocation which was finally treated using a carbon fibre sling. However this was removed 3 years later due to the presence of a radiolucency in the head of the condyle. Radiographic and photographic appearances of this carbon fibre induced radiolucency are shown.

Adolescent↗
PubMed1991

Skull base expansion: craniofacial effects.

In order to determine what effect the anterior cranial base has on the developing craniofacial skeleton, mechanical expansion of the growth of one segment of the anterior cranial base was performed. New Zealand white rabbits were used for this study. A sham-treated group (n = 16) underwent implantation of dental amalgam markers to either side of the frontonasal, coronal, and lambdoid sutures at 9 days of age to serve as markers of vault growth. The experimental group (n = 7) underwent the same marker placement at 9 days of age, but, in addition, at 30 days of age these animals underwent placement of a mechanical spring, unilaterally, at the frontosphenoid suture. A second control group (n = 8) underwent the same exposure of the frontosphenoid suture, but the spring was laid only on the surface of the bone. All animals were followed by radiographic cephalometry at 9, 30, 60, and 90 days of age. The experimental group demonstrated statistically significant expansion of the cranial base and ipsilateral coronal suture. The midface skeletal dimensions were unchanged by spring distraction of the cranial base. These findings indicate that cranial base sutural growth can be manipulated mechanically and that growth changes can be attained secondarily in the cranial vault skeleton.

Animals↗
PubMed1991

Eosinophilic granuloma of the oral region: a potential diagnostic problem.

Eosinophilic granuloma is a condition which may initially present with oral symptoms. Its variable oral clinical manifestations can result in a potential diagnostic problem for the dental surgeon. Two cases are presented which illustrate the difficulties in making a definitive diagnosis. The importance of a biopsy in diagnosis and the use of a whole-body skeletal scan in formulating a treatment plan are highlighted.

Adult↗
PubMed1991

Craniofacial suture stenosis: morphologic effects.

Craniofacial anomalies, such as Apert's and Crouzon's syndromes, are presumed to be related to premature growth arrest of cranial base growth sites. However, premature growth arrest at cranial vault sutures in animals appears to play a causative role in the development of cranial deformities characteristic of single-suture, or simple, craniosynostosis in humans. To study the possible causative role of cranial vault and other (interface) suture stenoses on the development of craniofacial deformity, a vault suture and an interface suture between the cranial vault and facial skeleton were simultaneously immobilized. Thirty-one New Zealand White rabbits at 9 days of age underwent implantation of dental amalgam growth markers adjacent to cranial vault and facial sutures. In the experimental group (n = 15), methylcyanoacrylate adhesive was applied over the coronal (vault) and frontonasal (interface suture between vault and facial skeleton) sutures to immobilize them. The remaining 16 animals served as sham-treated controls. All animals underwent serial radiographic cephalometry to document growth effects in the cranial vault, cranial base, and facial skeleton. Application of adhesive resulted in statistically significant (p less than 0.05) reduction in growth at the coronal and frontonasal sutures. This was accompanied by an overall significant reduction in neurocranial vault length during the first 30 days of development.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Late surgical treatment of unilateral coronal synostosis using methyl methacrylate.

Three techniques combining the shaping of calvarial and facial bone with onlay of methyl methacrylate are presented for use in the late treatment of unilateral coronal synostosis deformities. The procedures described are suggested as possible alternatives to extensive bone repositioning procedures. They have the advantage of being quicker and are therefore potentially safer operations. Acrylic is malleable and does not resorb; thus, permanent superior esthetic results may be achieved. The two most serious risks when using this technique are infection and limitation of growth. The risk of infection may be reduced by attaching the acrylic implant securely to surrounding bone, under sterile conditions, beneath well-vascularized skin. Growth limitation may be obviated by not placing acrylic across sutures in children with enlarging skulls.

Adult↗