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Biomedical subjects

E O'Brien

Publications and source records attributed to E O'Brien.

At least 73 records · Page 4Linked to original sources
PubMed1995

The ambulatory blood pressure in normotensive and hypertensive subjects: results from an international database.

OBJECTIVE: To delineate more precisely an operational threshold for making clinical decisions based on ambulatory blood pressure (ABP) measurement by studying the ABP in subjects who were diagnosed as either normotensive or hypertensive by conventional blood pressure (CBP) measurement. SUBJECTS: Twenty-four research groups recruited 7069 subjects. Of these, 4577 were normotensive (systolic CBP < or = 140 mmHg and diastolic CBP < or = 90 mmHg) and 1773 were hypertensive (systolic CBP > or = 160 mmHg and/or diastolic CBP > or = 90 mmHg). Of the latter, 1324 had systolic and 1310 had diastolic hypertension. RESULTS: Ninety-five percent of the normotensive subjects had a 24-h ABP below (systolic and diastolic, respectively) 133 and 82 mmHg. Of the patients with systolic hypertension, 24% had a 24-h systolic ABP of < 133 mmHg. Similarly, 30% of those with diastolic hypertension had a 24-h diastolic ABP of < 82 mmHg. The probability that hypertensive patients had a 24-h ABP below these thresholds was higher in women than in men, increased with age and was 2- to 4-fold greater if the CBP of the patient had been measured at only one visit and if fewer than 3 CBP measurements had been averaged to establish the diagnosis of hypertension. By contrast, for each 10-mmHg increment in systolic CBP, this probability decreased by 54% for the 24-h systolic ABP and by 25% for the 24-h diastolic ABP, and for each 5 mmHg increment in diastolic CBP it increased by 6 and 9%, respectively. CONCLUSION: The ABP distributions of the normotensive subjects included in the present international database were not materially different from those in previous reports in the literature. One-fifth to more than one-third of the hypertensive patients had an ABP which was below the 95th centile of the ABP in normotensive subjects, but this proportion decreased if the hypertensive patients had shown a higher CBP upon repeated measurement. The prognostic implications of elevated CBP in the presence of normal ABP remain to be determined.

Adolescent↗
PubMed1995

Ambulatory blood pressure measurement and the occurrence of hypertensive organ involvement.

Target organ involvement in hypertensive patients carries a poor prognosis, especially echocardiographically demonstrated left ventricular hypertrophy. Conventional blood pressure measurement correlates with target organ damage and mortality. 24-Hour ambulatory blood pressure measurement (ABPM) is a better predictor of target organ involvement than conventional blood pressure measurement, but there is as yet only scant evidence that 24-hour ABPM predicts mortality. The techniques for assessing target organ involvement and the superiority of ABPM over conventional measurement in predicting target organ damage are reviewed. It is argued that if 24-hour ABPM predicts target organ damage better than conventional measurement, then the likelihood is that it will also be a better predictor of mortality than conventional measurement. The studies underway to determine this important issue are reviewed.

Arteries↗
PubMed1995

Mechanism research of cryoanalgesia.

The sciatic nerves of rabbits were frozen at different temperatures (-20 degrees C, -60 degrees C, -100 degrees C, -140 degrees C, and -180 degrees C). The morphology and function of the frozen nerves were examined with light microscopy (hematoxylin and eosinophilin stain and a histochemical thiocholine method) and electron microscopy. The function of the nerve after freezing was assessed using short latency somatosensory evoked potentials, sensory conduction velocity, and electromyogram at various intervals after freezing. There were no changes in morphology or function of nerves cryolesioned at -20 degrees C. The nerve fibers cryolesioned at -60 degrees C showed signs of freezing degeneration and lost their conductive function although, these nerves all recovered. Approximately half of nerve fibers cryolesioned at -100 degrees C showed Wallerian degeneration, and although the time to remyelination was delayed, nerve regeneration was still complete. At -140 degrees C and -180 degrees C the nerve fibers showed immediate necrosis, with destruction of basal membranes and proliferation of collagen fibers. The results explained the mechanism of cryoanalgesia. Our study demonstrates that cryo-temperatures lower than -140 degrees C will cause permanent alterations in nerve morphology and function, whereas warmer temperatures do not result in permanent nerve damage and are therefore not likely to provide long-term analgesia to patients.

Analgesia↗
PubMed1995

Disease heterogeneity: does it impact our ability to detect dietary associations with breast cancer?

It is generally believed that breast cancer is a multistage process and that multiple and varying genetic events occur on the pathway to disease. We hypothesize that disease heterogeneity has an impact on our ability to identify risk factors. If a genetic alteration occurred in 50% of cases and a risk factor was associated only with that specific alteration, a risk estimate of 1.6 would be detected rather than the true risk estimate of 2.5 if analyses had been limited to those cases with the genetic alteration. Based on the literature we know that many genetic alterations occur in less than 50% of breast tumors. Thus, if environmental factors are related to some, but not all genetic alterations, we are decreasing our ability to identify potentially important risk factors. We therefore hypothesize that identification of dietary factors associated with breast cancer has been hampered by our inability to identify and capture the unique disease pathways which exist and contribute to the heterogeneity of common cancers such as breast cancer.

Breast Neoplasms↗
PubMed1995

State of the market. A review of ambulatory blood pressure monitoring devices.

The introduction of 24-hour ambulatory blood pressure measurement into clinical practice created a large market for ambulatory blood pressure measurement devices. Forty-three such devices from 31 manufacturers or suppliers are now available to satisfy a market demand that is likely to increase. The aim of this article is to identify the devices available and then to examine critically any validation studies assessing accuracy and performance. Of the 43 devices available 18 have been validated according to the protocols of the Association for the Advancement of Medical Instrumentation (AAMI) or the British Hypertension Society (BHS) in 25 reported studies. In 9 of these studies the protocol was not adhered to, and the results, which are therefore questionable, are noted but not considered further. Fourteen devices were evaluated according to the accuracy criteria of both protocols, and of these 9 fulfilled the requirements. From this review of 43 devices on the market it may be concluded that, at the time of writing, there is published evidence for only 9 devices meeting the generally accepted AAMI and BHS criteria for accuracy and performance; these are the A&D TM-2420 models 6 and 7 and TM-2421, CH-Druck, Nissei ABPM DS-240, Profilomat, QuietTrak, and SpaceLabs SL-90202 and SL-90207.

Blood Pressure Monitoring, Ambulatory↗