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Biomedical subjects

M Emery

Publications and source records attributed to M Emery.

At least 19 recordsLinked to original sources
PubMed1999

Degree of arterial desaturation in normoxia influences VO2max decline in mild hypoxia.

PURPOSE: Elite endurance athletes display varying degrees of pulmonary gas exchange limitations during maximal normoxic exercise and many demonstrate reduced arterial O2 saturations (SaO2) at VO2max--a condition referred to as exercise induced arterial hypoxemia (EIH). We asked whether mild hypoxia would cause significant declines in SaO2 and VO2max in EIH athletes while non-EIH athletes would be unaffected. METHODS: Nineteen highly trained males were divided into EIH (N = 8) or Non-EIH (N = 6) groups based on SaO2 at VO2max (EIH <90%, Non-EIH >92%). Athletes with intermediate SaO2 values (N = 5) were only included in correlational analyses. Two randomized incremental treadmill tests to exhaustion were completed--one in normoxia, one in mild hypoxia (FIO2 = 0.187; approximately 1,000 m). RESULTS: EIH subjects demonstrated a significant decline in VO2max from normoxia to mild hypoxia (71.1+/-5.3 vs. 68.1+/-5.0 mL x kg(-1) min(-1), P<0.01), whereas the non-EIH group did not show a significant deltaVO2max (67.2+/-7.6 vs. 66.2+/-8.4 mL x kg(-1) x min(-1)). For all 19 athletes, SaO2 during maximal exercise in normoxia correlated with the change in VO2max from normoxia to mild hypoxia (r = -0.54, P<0.05). However, the change in SaO2 and arterial O2 content from normoxia to mild hypoxia was equal for both EIH and Non-EIH (deltaSaO2 = 5.2% for both groups), bringing into question the mechanism by which changes in SaO2 affect VO2max in mild hypoxia. CONCLUSIONS: We conclude that athletes who display reduced measures of SaO2 during maximal exercise in normoxia are more susceptible to declines in VO2max in mild hypoxia compared with normoxemic athletes.

Adult↗
PubMed1998

Hearing loss due to myringotomy and tube placement and the role of preoperative audiograms.

BACKGROUND: Postoperative complications of myringotomy and tube placement often include otorrhea, tympanosclerosis, and tympanic membrane perforation. However, the incidence of sensorineural or conductive hearing loss has not been documented. Recent efforts to curb the use of preoperative audiometric testing requires documentation of this incidence. OBJECTIVE: To define the incidence of conductive and sensorineural hearing loss associated with myringotomy and tube placement. MATERIALS AND METHODS: A retrospective chart review of 550 patients undergoing myringotomy and tube placement was performed. A total of 520 patients undergoing 602 procedures (1204 ears), including myringotomy and tube placement, were assessed for preoperative and postoperative sensorineural and conductive hearing loss. RESULTS: No patient developed a postoperative sensorineural or conductive hearing loss. All patients resolved their conductive hearing loss after myringotomy and tube placement. There was a 1.3% incidence of preexisting sensorineural hearing loss. CONCLUSIONS: The incidence of sensorineural or conductive hearing loss after myringotomy and tube placement is negligible and the use of preoperative audiometric evaluation may be unnecessary in selected patients, but further studies need to be done to corroborate this small data set.

Adolescent↗
PubMed1998

Extent of expiratory flow limitation influences the increase in maximal exercise ventilation in hypoxia.

Increasing ventilation (VE) during hypoxic exercise may help to defend arterial O2 saturation (SaO2) and VO2max however, many athletes experience limitations to ventilatory flow and are not able to increase VE at high workrates. Five of 19 highly trained endurance athletes screened had < 5% of their tidal flow volume loop during maximal exercise meet the boundary set by their maximal resting flow volume loop. These five athletes were grouped as non-flow limited and compared to the five athletes who demonstrated the greatest percent of tidal volume flow limitation (56 +/- 11%) during maximal exercise (flow limited). Each athlete completed two incremental treadmill tests to exhaustion: normoxia and hypoxia (FI(O2) = 0.187). Non-flow limited athletes increased VE at VO2max from normoxia to hypoxia (140.9 +/- 13.4 vs. 154.7 +/- 11.9 L/min, P < 0.05), while flow limited athletes did not (159.5 +/- 9.4 vs. 162.3 +/- 6.0 L/min). The decline in SaO2 at VO2max from normoxia to hypoxia was not significantly different between groups. We conclude that athletes with little or no expiratory flow limitation are able to increase VE during maximal exercise in mild hypoxia, compared to athletes with significantly higher degrees of mechanical limitation. However this 'mechanical ventilatory reserve' does not appear to influence the ability to defend SaO2 or VO2max during maximal exercise in mild hypoxia.

Adult↗
PubMed1994

Clinical application of infrared thermography in the diagnosis of appendicitis.

To determine the clinical usefulness of infrared skin temperatures in diagnosing appendicitis, the authors conducted a prospective study of 86 adult and pediatric emergency department (ED) patients presenting during a 4-month study period with acute right lower abdominal pain. Skin temperature readings (FirstTemp digital thermometer, Intelligent Medical Systems, Inc, Carlsbad, CA) were taken from the right lower abdominal quadrant and a corresponding position on the left. An unpaired t test was used to determine if there was a significant difference between the right and left lower quadrants in patients with appendicitis. Discharged patients were followed up by telephone to determine any subsequent morbidity. A total of 23 patients had appendicitis confirmed by surgery; 63 subjects had other medical diagnoses. There was no significant skin temperature differential between the lower abdominal quadrants in either patient group (0.0 degree C vs 0.1 degree C; P > .5). Three patients had a skin temperature on the right that was at least 1 degrees C warmer than on the left; none of these patients had appendicitis. The results suggest that infrared thermography is not a sensitive diagnostic test for acute appendicitis in the ED population.

Abdomen↗
PubMed1994

Genetics in art.

Explore the source record for details and available documents.

Dwarfism↗
PubMed1992

Gas exchange and regional redistribution of pulmonary blood flow during resuscitation of acute pulmonary bead embolization.

Acute pulmonary embolism (PE) was induced by injecting polystyrene beads into the right atrium of 18 anaesthetized dogs. The animals were resuscitated for 45 min with either Ringer's Lactate (RL), norepinephrine (NE) or isoproterenol (IP). The multiple inert gas elimination technique (MIGET) was used to estimate the distributions of ventilation (V) and blood flow (Q) to different V/Q regions. Measurements were made prior to embolism, 10 min after PE and during the resuscitative phase. Microspheres with three different radioactive labels were also used to mark blood flow distribution to different lung regions in these three phases. The data show that cardiac output decreases after PE, while perfusion to shunt and low V/Q regions increases. Pulmonary blood flow heterogeneity, estimated from the MIGET data, is also increased after PE. Resuscitation by RL or NE consistently increases cardiac output but IP does so inconsistently and is associated with systemic hypotension. All three methods of resuscitation cause increases in perfusion to the shunt and low V/Q regions but no change in perfusion heterogeneity in the remaining V/Q units. Increases in regional blood flow during resuscitation occur preferentially in the less embolized areas. The concomitant increase in perfusion to shunt and low V/Q units suggests that increased perfusion to these less embolized regions results in further hypoxemia despite improvement in cardiac output.

Animals↗
PubMed1991

Prospective randomized study of human menotropin versus a follicular and a luteal phase gonadotropin-releasing hormone analog-human menotropin stimulation protocols for in vitro fertilization.

OBJECTIVE: To determine whether gonadotropin-releasing hormone analogs (GnRH-a) initiated either in the luteal phase or in the early follicular phase immediately preceding menotropin will improve the fertilization, implantation, and pregnancy rates (PR) in all IVF patients, when compared with menotropins alone. DESIGN: In a prospective, controlled, randomized study we compared a pure follicle-stimulating hormone (FSH) human menopausal gonadotropin (hMG) protocol (group A = control) (n = 93 cycles) to two protocols in which GnRH-a pretreatment plus pure FSH and/or hMG was used in in vitro fertilization candidates. In group B (n = 64) GnRH-a was initiated during the luteal phase and in group C (n = 35) during the follicular phase. RESULTS: We found (1) no differences in fertilization and implantation rates between the three protocols; (2) similar pregnancy rates per transfer when similar number of conceptus were transferred (A = 30%, B = 22%, C = 21%); (3) an increase of the number of oocytes obtained; and (4) a reduction in the cancellation rate with both GnRH-a protocols. CONCLUSIONS: These findings suggest that there is no obvious superiority between the two GnRH-a protocols in the dosage schedule used and that the major advantage of GnRH-a over non-GnRH-a protocols is in decreasing the cancellation rate and increasing the number of oocytes and conceptus obtained. The follicular phase GnRH-a protocol required less hMG-pure FSH than the luteal phase GnRH-a protocol.

Adult↗
PubMed1991

Compromised zinc status in rats adversely affects calcium metabolism in platelets.

The effect of zinc status on external calcium uptake by rat platelets and the relation of uptake to aggregation malfunction were studied. For 11 d, immature male rats were fed either a low zinc diet (0.3 mg/kg) ad libitum, a zinc-adequate diet (100 mg/kg) ad libitum, or the adequate diet pair-fed. Washed platelets were loaded with fura-2 acetoxymethyl ester for measurement of cytosolic free calcium. The resting calcium concentration was higher in platelets from rats of low zinc status than in those from controls. When platelets were stimulated with a minimal level (0.12 mumol/L) of ADP, the free cytosolic calcium concentration increased to a greater extent when calcium was present in the external medium than in its absence. The difference was considered to be external uptake. Zinc status had no effect on internal release, but platelets from zinc-deficient rats took up significantly less external calcium. In conclusion, low zinc status in rats adversely affects calcium metabolism in platelets. Decreased uptake of external calcium by ADP-stimulated platelets is associated with defective aggregation.

Adenosine Diphosphate↗
PubMed1988

Regional creatine kinase, adenylate kinase, and lactate dehydrogenase in normal canine brain.

Following acute stroke, creatine kinase and other enzymes are released into the cerebrospinal fluid and blood from injured brain tissue. To determine whether regional differences in brain enzyme activity might exist and therefore affect the amount of enzyme released, we quantified the levels of creatine kinase, adenylate kinase, and lactate dehydrogenase in 12 regions of normal canine brain (n = 4). Adenylate kinase activity varied the least among regions (49 +/- 7 units/g), followed by lactate dehydrogenase activity (122 +/- 28 units/g). The pattern for both adenylate kinase and lactate dehydrogenase was higher activity in predominantly gray matter areas, lower activity in white matter, and intermediate activity in mixed regions. The distribution of creatine kinase brain isoenzyme and mitochondrial creatine kinase in canine brain was less predictable, showing wider variations among regions (isoenzyme, 462 +/- 116 units/g; mitochondrial, 42 +/- 20 units/g). Even cerebral gray matter demonstrated substantial regional variations in creatine kinase brain isoenzyme, ranging from 606 units/g in the parietal cortex to 329 units/g in the temporal cortex. We conclude that the content of creatine kinase brain isoenzyme varies more than twofold among areas of brain. This regional variation may be important in the interpretation of creatine kinase brain isoenzyme measurements in cerebrospinal fluid and serum used to assess neurologic injury following stroke.

Adenylate Kinase↗
PubMed1986

Considerations for improving survival from out-of-hospital cardiac arrest.

Since the implementation of a paramedic system in Seattle, yearly survival rates from out-of-hospital cardiac arrest due to ventricular fibrillation have averaged 25% without any significant increase over the years. Outcome for cardiac arrest associated with other rhythms has been poor: when asystole was the first rhythm recorded, only 1% of patients survived; when electromechanical dissociation was initially present, only 6% survived. For cases of electromechanical dissociation, neither the type of rhythm nor the rate appear to influence outcome. Survival from ventricular fibrillation can be improved by shortening the delay to initiation of CPR and to defibrillation. When outcome in 244 witnessed arrests was related to the times to beginning CPR and to initial defibrillation, mortality increased 3% each minute until CPR was begun and 4% a minute until the first shock was delivered. New strategies that minimize delays appear to have the greatest promise for improving survival after cardiac arrest.

Ambulances↗
PubMed1980

The theory and practice of behaviour change in the school context.

There is a large volume of teaching material on health education which provides factual information. Although facts are important, other factors are also involved in bringing about attitude and behaviour change. Taking the teaching of a difficult subject, that of "responsible sexual behaviour" to lower ability pupils aged 14-15 years, the author describes her approach which involves (a) the use of humour to remove defences; (b) the use of games to hold interest and promote involvement, the objective being to lead to serious discussion of sex before marriage, the use of contraception, abortion, adolescent-parent relationships, etc.; and (c) the use of self-assessment to determine individual contributions to the lesson and the impact of the teaching. The author then reviews current theories of attitude and behaviour change. "Health education", she says, "aims to immunize teenagers against pressures by exposure to them in small doses, as with measles. We need further to undermine harmful pressures and create new positive ones." This is no easy task for teachers, involving as it does individual motivation as well as the long-term modification of social norms. Hence the importance of adequate basic and in-service training to help teachers think in behavioural terms rather than in terms of imparting knowledge and to use tested methods of attitude and behaviour change.

Adolescent↗
PubMed1979

High-performance liquid chromatography of benzodiazepines I: Stability-indicating assay of diazepam tablets.

A high-performance liquid chromatographic procedure was developed for diazepam tablet analysis. This procedure separates the manufacturing intermediate, 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one, and the decomposition products, 3-amino-6-chloro-1-methyl-4-phenylcarbostyril and 2-methylamino-5-chlorobenzophenone, from diazepam. The liquid chromatographic procedure is superior to the USP UV assay because it is stability indicating. The method is simple, accurate, and fast, involving only one extraction step. A reversed-phase column and a methanol-water mobile phase were used. Under these conditions, 0.1% of the decomposition products was detectable. Typical samples of diazepam tablets showed no degradation.

Chromatography, High Pressure Liquid↗