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Biomedical subjects

D J Vaughan

Publications and source records attributed to D J Vaughan.

At least 19 recordsLinked to original sources
PubMed2005

Oxygen therapy for cystic fibrosis.

BACKGROUND: The most serious complications of cystic fibrosis (CF) relate to respiratory insufficiency. Oxygen supplementation therapy has been a standard of care for individuals with chronic lung diseases associated with hypoxemia for decades. It is common for physicians to prescribe oxygen therapy for people with CF when hypoxemia occurs. However, it is unclear if empiric evidence is available to provide indications for this therapy with its financial costs and often profound impact on lifestyle. OBJECTIVES: To assess whether oxygen therapy improves the longevity or quality of life of individuals with CF. SEARCH STRATEGY: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Most recent search of Group's Trials Register: April 2005. SELECTION CRITERIA: Randomized or quasi-randomized controlled trials comparing oxygen, administered at any concentration, by any route, in people with documented CF for any time period. DATA COLLECTION AND ANALYSIS: Two authors independently assessed study quality and extracted data. MAIN RESULTS: Nine published studies (149 participants) are included in this review, of which only one examined long-term oxygen therapy (28 participants). There was no statistically significant improvement in survival, lung, or cardiac health. Four studies examined the effect of oxygen supplementation during sleep by polysomnography. Although oxygenation improved, there were no demonstrable improvements in qualitative sleep parameters and modest hypoventilation was noted. In three studies, oxygen supplementation was evaluated during exercise. Hypoxemia was prevented, but mild hypercapnia resulted. Work performance was not improved, as measured in one study, but was improved in a second study. Furthermore, in two studies, exercise duration was enhanced by oxygen supplementation. In the study examining the impact of oxygen supplementation after exercise, recovery time was enhanced. AUTHORS' CONCLUSIONS: There are no published data to guide the prescription of chronic oxygen supplementation to people with advanced lung disease due to CF. Short-term oxygen therapy during sleep and exercise improves oxygenation but is associated with modest and probably clinically inconsequential hypercapnia. During exercise, there are improvements in exercise duration and peak performance. There is a need for larger, well-designed clinical trials to assess the benefits of long-term oxygen therapy in people with CF administered continuously or during exercise or sleep or both.

Cystic Fibrosis↗
PubMed2001

Choice of opioid for initiation of combined spinal epidural analgesia in labour--fentanyl or diamorphine.

Sixty-two women requesting regional analgesia in labour were allocated to receive a 1.5 ml intrathecal injection as part of a combined spinal-epidural (CSE) analgesic technique. This contained either bupivacaine 2.5 mg plus fentanyl 25 microg (group F) or bupivacaine 2.5 mg plus diamorphine 250 microg (group D). Times of analgesic onset and offset were recorded, motor and proprioceptive assessments made and side-effects noted. Analgesic onset was not significantly different between the groups (group F, 8.0 min; group D, 9.5 min; P = 0.3) but time to first top-up request was significantly longer in the diamorphine group (group F, 73 min; group D, 101 min; P = 0.003). Motor loss, assessed by the modified Bromage score, was statistically but not clinically greater in the fentanyl group (P = 0.01). Maternal hypotension, pruritus, proprioceptive loss, nausea and fetal bradycardia were rare and not severe, and their incidences did not differ between groups. No respiratory depression was observed after CSE. This use of diamorphine was not associated with increased side-effects compared with fentanyl/bupivacaine, and it has a longer duration of action.

Analgesia, Epidural↗
PubMed2001

Retained wooden foreign body in a child's thigh complicated by severe necrotizing fasciitis: a case report and discussion of imaging modalities for early diagnosis.

Soft tissue foreign bodies (FB) represent a common cause for emergency department visits. Diagnosis may be difficult especially with non-radiopaque FB. The clinical course may be complicated by superficial or deep tissue infection. Use of imaging modalities such as ultrasound may be important for early diagnosis. We report a case of retained foreign body with a complicated clinical course and discuss imaging modalities that may have aided in the early diagnosis.

Child↗
PubMed2000

Speed of onset of regional analgesia in labour: a comparison of the epidural and spinal routes.

This study compares the speed of onset of effective analgesia in two randomly assigned groups of patients requesting analgesia in labour. Patients in the combined spinal-epidural group (n = 69) were given a subarachnoid injection of 1.5 ml containing bupivacaine 2.5 mg and fentanyl 25 microg for initiation of analgesia. Patients in the epidural group (n = 73) were given an epidural injection of 10 ml containing bupivacaine 12.5 mg and fentanyl 50 microg. Mean (SD) onset times to the first pain-free contraction were 10.0 (5.7) min in the combined spinal-epidural group and 12.1 (6.5) min in the epidural group (p = 0.054). Patients in the combined spinal-epidural group suffered a higher incidence of motor weakness and proprioceptive deficit than those in the epidural group (p = 0.01). The incidence of technique failure and side-effects was similar in the two groups. It is our contention that the statistically nonsignificant difference in onset times does not justify the additional potential for side-effects and the extra cost of the equipment involved in the combined spinal-epidural technique.

Adult↗
PubMed2000

Effect of tramadol on electroencephalographic and auditory-evoked response variables during light anaesthesia.

Tramadol is a centrally acting opioid-like analgesic commonly used for analgesia during surgery. It has been stated that the use of tramadol increases the risk of awareness during anaesthesia. We studied 29 patients under steady state anaesthesia, ventilated via a laryngeal mask airway with 0.6 MAC isoflurane in 50% nitrous oxide, and with no surgical stimulus. The electroencephalogram (EEG) and auditory-evoked response (AER) were recorded throughout the study period, as were pulse and arterial pressure. Patients were given randomly a bolus of either saline (S), tramadol 100 mg (T1), or tramadol 200 mg (T2). Significant increases in systolic arterial pressure and decreases in heart rate were seen in the tramadol groups compared to the saline group. Significant, dose-related activation in all EEG variables (median power frequency, spectral edge, Delta Power and Alpha/Delta ratio) but no significant change in Pa or Nb amplitudes or latencies were noted. The EEG changes were not at levels thought to be associated with awareness. This study indicates that tramadol, whilst causing EEG activation, has no effect on depth of anaesthesia as measured by the AER.

Adolescent↗
PubMed2000

Cranial subdural haematoma associated with dural puncture in labour.

A 23-yr-old primagravida sustained a dural puncture during epidural catheter insertion and developed a headache that settled with oral diclofenac and codydramol. On the third day after delivery, she convulsed twice without warning. As plasma urate was increased, the putative diagnosis of an eclamptic fit was made, and magnesium therapy was started. A contrast CT scan revealed that the cause of the patient's symptoms was a subdural haematoma with raised intracranial pressure. A coincidental arteriovenous malformation was noted. This case emphasises the need to consider the differential diagnoses of post-partum headache. The management of acute intracranial haematoma is described.

Adult↗
PubMed1997

Anesthesia for patients with carcinoid syndrome.

Carcinoid syndrome, although rare, can create serious problems to the anesthetist, both by the nature and variability of clinical manifestations and by the complications that can occur peroperatively. Recent research has led to a better understanding of the pathophysiology of the disease process. However, modern medicine is far from unraveling the precise nature and physiological effects of all the peptide mediators produced by these tumors. The severity of symptoms does not predict the severity of perioperative complications, so that patients with minor preoperative symptoms may have significant intraoperative complications. While urinary 5-HIAA levels provide a good indicator of disease progression, they cannot predict the degree or type of physiological response to intraoperative tumor manipulation. Indeed, urinary 5-HIAA may be normal both in the presence of a clinical diagnosis of carcinoid syndrome and in the face of a peroperative carcinoid crisis. The keys to successful anesthetic management of patients with carcinoid syndrome are good communication between endocrinologist, anesthetist, and surgeon and preoperative optimization of the patient. This includes appropriate investigation and treatment of the effects of carcinoid peptides and the prevention of their release from tumors. If possible, advice should be sought from centers with experience at managing this group of patients. Octreotide has largely replaced the use of other drugs both for symptomatic control and acute treatment of the symptoms associated with carcinoid syndrome. However, other drugs, such as aprotinin, still have a significant place in the symptomatic control and treatment of peroperative complications, as serotonin is only one of a large variety of peptides responsible for the clinical effects of this disease. Anesthetic technique should be aimed at minimizing carcinoid mediator release, in response to stress it induction of anesthesia and tracheal intubation and during tumor manipulation. It is equally important to prepare for carcinoid crisis by, for example, ordering drugs, which are otherwise uncommonly used in the theater setting, ahead of time. Cardiovascular instability, particularly hypotension, is common, so that full monitoring and vigilance is vital to predict its onset. The current surgical view of management is that, while curative resection of carcinoid tumors less than 2 cm in diameter with no evidence of invasion or metastatic spread is appropriate, patients with disseminated disease should be medically managed unless symptom control is poor. The exceptions to this are those patients with early and correctable carcinoid cardiac disease and those who require palliative procedures such as defunctioning obstructed bowel. Survival rates in patients following excision of gastric and appendical carcinoid tumors approach those of the general population as a whole and the chance of metastasis is extremely low. Only two series have been published in the anesthetic literature on anesthesia for patients with carcinoid syndrome, although there are many single-case reports. Despite the rarity of this syndrome, further formal studies into the anesthetic management of this condition should be encouraged.

Anesthesia↗
PubMed1989

The involvement of dimethyl sulfoxide in a bacteriotoxic response of the Ames assay tester strains TA98 and TA100.

Dimethyl sulfoxide is a widely accepted and recommended solvent in which to dissolve compounds to be tested for mutagenicity via the Ames Salmonella/mammalian microsome assay. Using tester strains TA98 and TA100, we observed a bacteriotoxic response with various fractions isolated from beer when dissolved in DMSO but not when dissolved in water. Further characterization of the role of solvent in simple model systems consisting of butanol, DMSO and bacteria strongly suggests a chemical reaction occurs between dimethyl sulfoxide and specific chemical constituents of the test substance, nutrient broth, or the Ames bacterial strains. The result of such an interaction could be misinterpreted as a toxic response to the test substance when, in fact, the bacteriotoxicity could be due to another compound, chemically distinct from the test substance.

1-Butanol↗
PubMed1987

The effect of fecapentaenes on nuclear aberrations in murine colonic epithelial cells.

Fecapentaenes, human fecal mutagens of bacterial origin, were intrarectally administered to mice in suppository form. Despite the strong, positive mutagenic response of fecanpentaenes using Ames tester strains TA 98 and TA 100, no increase in nuclear aberrations, taken as a measure of genotoxicity in colonic epithelial cells, was observed over control levels. In fecapentaene treated animals, however, the incidence of mitotic figures was increased above control levels to values comparable to those observed in mice treated with the known colon carcinogen, N-ethyl-N-nitrosourea. Thus, it would appear that fecapentaenes are not cytotoxic to murine colonic epithelia as judged by the nuclear aberration assay.

Animals↗
PubMed1987

The Kock pouch: initial experience and complications.

The modified Kock continent internal reservoir procedure has been performed on 15 patients at our medical center since December 1984: 13 underwent simultaneous anterior exenteration for pelvic malignancy, 1 had conversion from an ileal conduit and 1 underwent cystectomy for refractory interstitial cystitis. There was no operative mortality. There were 3 early complications: a urinary leak from the pouch in 2 patients that required re-exploration to close the defect, and an enteric-Kock pouch fistula in 1 that required resection of the small bowel fistula and repair of the pouch defect. All 3 patients are doing well. The late complication in 3 cases was urinary incontinence of the efferent nipple valve with difficulty in catheterization of the stoma. Two patients have undergone revision with a new efferent nipple valve added on to the pouch and creation of a new stoma. One patient is completely dry and continent, 1 has tolerable intermittent leakage and refuses a further operation, and 1 is awaiting revision. Although the initial experience is small, we are encouraged by these results and believe that this procedure is an alternative form of urinary diversion for the properly selected patient.

Adult↗
PubMed1986

Characterization of cytotoxic steroids in human faeces and their putative role in the etiology of human colonic cancer.

It has been shown previously that chemically induced nuclear abeerrations in the murine colon are correlated with the carcinogenicity of the respective chemicals. Consequently, the nuclear aberration assay was utilized for the identification of putatife carcinogens in human faeces. Human fecal samples were fractionated by several chromatographic methods, and the assay led to the isolation of two substances. A combination of spectroscopic (mass, nuclear magnetic resonance, ultraviolet, and infrared) and chromatographic (HPLC and GLC) methods showed that they are 5-alpha- cholestan-3-one (I) and cholest-4-en-3-one (II). A number of C-27-C-30 steroids isolated from closely related fractions of feces were inactive in this assay. Thus I and II could play a role in etiology of large bowel cancer in humans.

Animals↗
PubMed1980

Synthesis of spin-labelled 2-(16'-(N-oxyl-4'',4''-dimethyloxazolidine)stearoyl)-phosphatidylcholine.

Chemical synthesis of spin-labelled lecithin 2-(16'-(N-oxyl-4'',4''-dimethyloxazolidine)stearoyl)-phosphatidylcholine was achieved by reaction of equimolar amounts of purified egg yolk lyso-lecithin with commercially available 16-(N-oxyl-4',4'-dimethyloxazolidine)stearic acid activated with N,N-carbonyldiimidazole. After purification by silicic acid column chromatography, spin-labelled lecithin was obtained in 52.2% yield and had an ester: phosphorus:spin molar ratio of 2.0:1.1:1.0. When dimyristoyl-phosphatidylcholine and dimyristoyl-phosphatidylcholine:cholesterol (10:1) liposomes, containing 2-(16'-(N-oxyl-4'',4''-dimethyloxazolidine)stearoyl)-phosphatidylcholine as a probe were examined for thermotropic changes monitored by electron spin resonance spectroscopy, transition temperatures of 24.0 and 24.2 degrees C, respectively, were obtained in a very good agreement with previously reported values obtained with different probes and by different techniques, and with our own differential scanning calorimetry measurements. The potential usefulness of synthetic 2-(16'-(N-oxyl-4'',4''-dimethyloxazolidine)stearoyl)-phosphatidylcholine as a spin-label probe in studies of lipid-protein interactions in biological membranes was discussed.

Calorimetry, Differential Scanning↗
PubMed1980

Reconstitution of lipoproteins. II. Lipid-protein interaction between dimyristoyl-lecithin and dimyristoyl-lecithin:cholesterol vesicles and purified apolipoprotein C-I and C-III2 studied by isomeric spin-labelled lecithins.

The reconstitution of purified apolipoprotein C-I and C-III2 with sn-3-dimyristoyl-lecithin and sn-3-dimyristoyl-lecithin:cholesterol (10:1) vesicles was studied by electron spin resonance spectroscopy using isomeric 5'-, 12'-, and 16'-(N-oxyl-4",4"-dimethyloxazolidine)stearoyl spin-labelled lecithin probes. Results obtained from the temperature-induced changes of lipoprotein recombinants showed the hydrophilic nature of the lipid-protein interactions. The temperature-induced phospholipid phase transition, as measured by 5'-(N-oxyl-4",4"-dimethyloxazolidine)stearoyl spin-labelled lecithin probe in recombinants containing apoprotein C-1 or apoprotein C-iii2, is very broad and has a small cooperative unit indicative of extensive lipid-protein interactions occurring at the head group region of the phospholipid bilayer. When 12"- and 16'-(N-oxyl-4",4"-dimethyloxazolidine)stearoyl spin-labelled lecithins are used as probes in the same system, similar sharper and more cooperative lipid phase changes are detected. These results indicate a surface location for both apoprotein C-I and apoprotein C-III2 with respect to the phospholipid bilayer in lipoprotein recombinants with and without cholesterol.

Amino Acids↗