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M J Emery

Publications and source records attributed to M J Emery.

13 recordsLinked to original sources
PubMed2004

Increased ventilation and CO2 chemosensitivity in acetylcholinesterase knockout mice.

To investigate the effects of a permanent excess of acetylcholine (AChE) on respiration, breathing and chemosensitivity were analyzed from birth to adulthood in mice lacking the AChE gene (AChE-/-), in heterozygotes, and in control wild-type (AChE+/+) littermates. Breathing at rest and ventilatory responses to brief exposures to hypoxia (10% O2) and hypercapnia (3-5% CO2) were measured by whole-body plethysmography. At rest AChE-/- mice show larger tidal volumes (VT, + 96% in adults), overall ventilation (VE, + 70%), and mean inspiratory flow (+270%) than wild-type mice, with no change in breathing frequency (fR). AChE-/- mice have a slightly blunted response to hypoxia, but increased VE and fR responses to hypercapnia. Heterozygous animals present no consistent alterations of breathing at rest and chemosensitivity is normal. Adult AChE-/- mice have an increased VE/VO2 and a marginally higher normalized VO2. The results suggest that the hyperventilation and altered chemosensitivity in AChE-/- mice largely reflect alterations of central respiratory control.

Acetylcholinesterase↗
PubMed2000

Ventilation heterogeneity in excised lobes: effect of tidal volume.

Although several factors are known to influence nonuniformity of ventilation, including lung mechanical properties (regional structure and compliance), external factors (chest wall, pleural pressure, heart), and ventilatory parameters (tidal and preinspiratory volume, flow rate), their relative contributions are poorly understood. We studied five excised, unperfused, canine right-middle lobes under varied levels of tidal volume (VT), thus eliminating many factors affecting heterogeneity. Multiple-breath washouts of N(2) were analyzed for anatomic dead space volume (VD(anat)), nonuniformity of N(2) washout, and nonuniformity between joined acinar regions vs. that occurring between larger joined regions. Approximately 80% of ventilation heterogeneity was found among joined acinar regions at resting levels of VT, but increasing VT reduced intra-acinar heterogeneity to about 25% of that found at resting levels. Increasing VT had essentially no effect on VD(anat) and heterogeneity among larger joined regions. The results indicate that the magnitude of VT is a major influence on the dominant intra-acinar component of ventilation heterogeneity and that VT effects on VD(anat) are likely due to perfusion and/or influences normally external to the lobar structure.

Animals↗
PubMed1998

Ventilation heterogeneity is increased in hypocapnic dogs but not pigs.

Hypocapnia increases ventilation/perfusion (VA/Q) heterogeneity in dogs, possibly by adversely affecting distribution of ventilation through its effects on collateral ventilation. Because pigs lack collateral ventilation, we compared the effects of hypocapnia on ventilation heterogeneity in pentobarbital-anesthetized, mechanically-ventilated dogs and pigs. Simultaneous multiple breath washouts of helium and nitrogen were used to assess the uniformity of the ventilation distribution by the phase III (SnIII) method. Ventilation heterogeneity was partitioned into two components, e.g. convective-dependent inhomogeneity (cdi) and diffusive-convective-dependent inhomogeneity (dcdi). Pulmonary gas exchange was also measured in pigs by the multiple inert gas elimination technique. Ventilation heterogeneity was increased (P < 0.01) in hypocapnic dogs. Inspiration of CO2 decreased ventilation heterogeneity by decreasing dcdi (P < 0.01). In contrast, ventilation heterogeneity was not increased in hypocapnic pigs. However, hypocapnia increased VA/Q heterogeneity by 18% (P < 0.05) in pigs. We conclude that hypocapnia increases ventilation heterogeneity in dogs but not in pigs, most likely related to an interspecies difference in collateral ventilation.

Analysis of Variance↗
PubMed1998

Airway mucosal blood flow in bronchial asthma.

As an inflammatory airway disease, asthma is expected to be associated with an increase in airway blood flow. We therefore compared airway mucosal blood flow (Qaw) among normal subjects (n = 11) and patients with stable asthma receiving (n = 13) or not receiving (n = 10) long-term inhaled glucocorticosteroid (GS) therapy. Qaw was calculated from the uptake of dimethyl ether in the anatomic dead space minus the most proximal 50 ml (DS), and expressed as blood flow per ml DS. Mean (+/- SE) Qaw was 38.5 +/- 5. 3 microl . min-1 . ml-1 in normals, 68.2 +/- 7.9 microl . min-1 . ml-1 in GS-naive asthmatics (p < 0.01), and 55.4 +/- 5.3 microl . min-1 . ml-1 in GS-treated asthmatics (p < 0.05). Ten minutes after administration of 180 microg albuterol by metered dose inhaler, mean Qaw increased by 83 +/- 26% in normal subjects (p < 0.01), but did not change significantly in GS-naive (+5 +/- 8%) or GS-treated (+32 +/- 15%) asthmatics. These results demonstrate that Qaw is increased in stable asthmatics and resistant to further increase by a standard inhaled dose of a beta-adrenergic agonist.

Adolescent↗
PubMed1997

Ventilation inhomogeneity in oleic acid-induced pulmonary edema.

Oleic acid causes permeability pulmonary edema in the lung, resulting in impairment of gas-exchange and ventilation-perfusion heterogeneity and mismatch. Previous studies have shown that by using the multiple-breath helium washout (MBHW) technique, ventilation inhomogeneity (VI) can be quantitatively partitioned into two components, i.e., convective-dependent inhomogeneity (cdi) and diffusive-convective-dependent inhomogeneity (dcdi). Changes in VI, as represented by the normalized slope of the phase III alveolar plateau, were studied for 120 min in five anesthetized mongrel dogs that were ventilated under paralysis by a constant-flow linear motor ventilator. These animals received oleic acid (0.1 mg/kg) infusion into the right atrium at t = 0. MBHWs were done in duplicate for 18 breaths every 40 min afterward. Three other dogs that received only normal saline served as controls. The data show that, after oleic acid infusion, dcdi, which represents VI in peripheral airways, is responsible for the increasing total VI as lung water accumulates progressively over time. The cdi, which represents VI between larger conductive airways, remains relatively constant throughout. This observation can be explained by increases in the heterogeneity of tissue compliance in the periphery, distal airway closure, or by decreases in ventilation through collateral channels.

Animals↗
PubMed1996

Pulmonary blood flow distribution in standing horses is not dominated by gravity.

Recent studies using microspheres in dogs, pigs and goats have demonstrated considerable heterogeneity of pulmonary perfusion within isogravitational planes. These studies demonstrate a minimal role of gravity in determining pulmonary blood flow distribution. To test whether a gravitational gradient would be more apparent in an animal with large vertical lung height, we measured perfusion heterogeneity in horses (vertical lung height = approximately 55 cm). Four unanesthetized Thoroughbred geldings (422-500 kg) were studied awake in the standing position with fluorescent microspheres injected into a central vein. Between 1,621 and 2,503 pieces (1.3 cm3 in volume) were obtained from the lungs of each horse with spatial coordinates, and blood flow was determined for each piece. The coefficient of variation of blood flow throughout the lungs ranged between 22 and 57% among the horses. Considerable heterogeneity was seen in each isogravitational plane. The relationship between blood flow and vertical height up the lung was characterized by the slope and correlation coefficient of a least squares regression analysis. The slopes within each horse ranged from -0.052 to +0.021 relative flow units/cm height up the lung, and the correlation coefficients varied from 0.12 to 0.75. A positive slope, indicating that flow increased with vertical distance up the lung (opposite to gravity), was observed in three of the four horses. In addition, blood flow was uniformly low in three of the four horses in the most cranial portions of the lungs. We conclude that in lungs of resting unanesthetized horses, animals with a large lung height, there is no consistent vertical gradient to pulmonary blood flow and there is a considerable degree of perfusion heterogeneity, indicating that gravity alone does not play the major role in determining blood flow distribution.

Animals↗
PubMed1994

Depression of hypercapnic ventilatory drive by testosterone in the sleeping infant primate.

In postnatal infants, there is similarity between the time course of transient gonadal steroid secretion and the age-related incidence of sudden infant death syndrome (SIDS). The cause of death in SIDS is generally thought to be a ventilatory arrest, but the mechanism responsible for such an event remains unknown. Testosterone has been demonstrated to depress ventilatory drive and increase sleep apnea in adult men. We tested the hypothesis that the gonadal steroid testosterone depresses infant ventilatory drive during sleep. Three newborn male infant primates were gonadectomized after birth. Ventilation was observed and quantified for each animal during completely natural unencumbered sleep by plethysmography for an average of 16 wk. Ventilatory patterns were recorded, and ventilatory drive was challenged with hypercapnia and hypoxia during quiet sleep on the night before and the night after testosterone administration. Hypercapnic ventilatory drive during sleep was significantly depressed by an average of 33.6% on the night after compared with the night before testosterone administration. Depression of the response to hypercapnia after testosterone was not accompanied by any change in resting minute ventilation measured during quiet sleep. Hypoxic ventilatory drive, incidence of apneic events, and length of apnea were not different after testosterone. The effects of injecting a placebo on ventilatory patterns and drive were tested by giving the placebo to all animals on several test weeks. Placebo injections produced no significant change in any measured parameters. These results support the hypothesis that testosterone depresses hypercapnic ventilatory drive during sleep in the infant primate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

The impact of the prospective payment system: perceived changes in the nature of practice and clinical education.

BACKGROUND AND PURPOSE: Health care financing for teaching hospitals has undergone significant change in the past decade. This report describes changes in physical therapy practice and clinical education in three New England hospitals from 1984 to 1988. SUBJECTS: Hospital administrators, physical therapy managers, and clinical educators (N = 18) from the three teaching hospitals participated in this descriptive study. METHODS: Demographic, environmental, and participant interview data were gathered and examined to identify changes during this period. RESULTS: Perceived changes in practice include growth in specialized knowledge; increased emphasis on health care quality, efficiency, and accountability; new ethical dilemmas for practitioners; and a changing physical therapy role with new professional development opportunities. Perceived changes associated with clinical education were increased student performance expectations, unchanged resources for clinical education, greater emphasis on student self-directedness, and continued high valuing of this setting for physical therapy clinical education. CONCLUSION AND DISCUSSION: These results indicate significant change in the role of the physical therapist within these settings and suggest how these changes influence the clinical education of physical therapy students in these teaching hospitals.

Clinical Competence↗
PubMed1993

New partnerships.

Explore the source record for details and available documents.

History, 20th Century↗
PubMed1984

Effectiveness of the clinical instructor. Students' perspective.

I conducted a survey of 102 senior physical therapy students to identify, from the students' perspective, training needs for clinical instructors. The literature identified 43 clinical instructor behaviors in four categories (communication, interpersonal relations, professional skills, and teaching behaviors). Students scored these behaviors, for their importance and frequency. Results demonstrated all behaviors were perceived as somewhat significant and frequent. The students scored communication as most important followed by interpersonal relations, teaching, and professional skills behaviors. Frequency of the 43 behaviors was evenly distributed among the four categories. Correlational analysis of the perceived importance with the frequency of each behavior yielded 9 statistically significant positive correlations, no negative correlations, and 16 near random correlations. Positive correlations were 56 percent professional skills and 44 percent teaching behaviors. Near random correlations were 38 percent communication, 6 percent interpersonal relations, 6 percent professional skills behaviors, and 50 percent teaching. These 16 behaviors are identified as the target for clinical instructor training programs. This method in individual clinical settings is discussed briefly.

Attitude↗
PubMed1980

Ovarian arterial blood velocity measured with Doppler ultrasonic transducers in conscious ewes.

Changes in the mean velocity of ovarian arterial blood flow during the oestrous cycle were monitored in 5 ewes by the use of doppler ultrasonic transducers chronically implanted around the ovarian arteries. In arteries supplying ovaries with a corpus luteum (CL), the velocity was minimal from Day -1 to Day 2 inclusive (Day 0 = day of oestrus), increased steadily until Day 13 (-4) and then declined precipitously. In contralateral arteries supplying ovaries without a CL, the velocity remained at a consistently low level throughout the oestrous cycle. In each ewe, arterial blood velocity to the ovary with a CL and progesterone levels in peripheral plasma were highly correlated; within-individual correlations falling between r = 0.830 (P < 0.001, n = 15) and r = 0.936 (P < 0.001, n = 15). The changes in the velocity of the arterial supply to the ovulatory ovary and the pattern to that for weight of luteal tissue in similar ewes.

Animals↗
PubMedDate not supplied

Site-directed double fluorescent tagging of human renin and collagenase (MMP-1) substrate peptides using the periodate oxidation of N-terminal serine. An apparently general strategy for provision of energy-transfer substrates for proteases.

Periodate in neutral aqueous solution rapidly converts N-terminal Ser or Thr to an alpha-N-glyoxylyl moiety that can serve as the locus for incorporation of a modifying group [Geoghegan, K. F., and Stroh, J. G. (1992) Bioconjugate Chem. 3, 138-146. Gaertner, H. F. et al. (1992) Bioconjugate Chem. 3, 262-268]. The usefulness of this procedure has been further illuminated in a route to "energy-transfer" substrates for endoproteases. Each such substrate is an oligopeptide cleavable by a proteinase, but modified (usually at its termini) with two chromophores that form an energy donor-acceptor pair. Production of these substrates is an exercise in double site-directed peptide modification. The new route is composed of three steps, beginning from an unprotected peptide in which a sequence recognized by the pertinent enzyme is placed between N-terminal Ser and C-terminal Lys. Lys may not occur elsewhere in the peptide. Periodate oxidation converts the N-terminal Ser to an alpha-N-glyoxylyl group, which is then allowed to form a hydrazone with the carbohydrazide derivative Lucifer Yellow CH, a hydrophilic fluor with a large Stokes shift (excitation maximum, 425 nm; emission maximum, 525 nm). Finally, the modified peptide is allowed to react with 5-carboxytetramethylrhodamine succinimidyl ester. This reaction selectively modifies the epsilon-amino group of C-terminal Lys, the only amino group remaining in the peptide. 5-Carboxytetramethylrhodamine strongly (> 90%) quenches Lucifer Yellow fluorescence by resonance energy transfer in the intact substrate, but enzyme-catalyzed cleavage eliminates the quenching. The resulting increase in fluorescence may be used to follow the hydrolytic reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗