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Biomedical subjects

J B Morrison

Publications and source records attributed to J B Morrison.

At least 37 records · Page 2Linked to original sources
PubMed1990

Measurement of static and dynamic pulmonary work during pressure breathing.

Various environments alter static and flow-resistive pulmonary mechanics. Of interest to diving physiologists is the negative pressure breathing induced during upright immersions without appropriate modification of air supply pressure. This paper outlines methodologic considerations for determining static and flow-resistive pulmonary work under such exposures. Ten males performed inspiratory pressure-volume relaxation maneuvers and spontaneous breathing in air, and during upright immersion with mouth pressure air supply. The immersed lung centroid pressure (PLC) was +1.19 kPa relative to the hydrostatic pressure at the sternal notch. Immersion elevated inspiratory static work from 0.36 to 1.74 J.liter-1 (P less than 0.05). Pulmonary flow-resistive work was elevated from 0.20 to 0.75 J.liter-1 (P less than 0.05), whereas pulmonary resistance, determined at 0.5 liter.sec-1, increased from 0.18 to 0.44 kPa.liter-1.sec (P less than 0.05). No significant changes in the iso-volume compliance of the lung tissue, chest wall, or total respiratory system were observed (P greater than 0.05). Results indicate that increases in the work of breathing are due to a combination of hydrostatic pressure imbalance, increased pulmonary resistance, and reduced end-expiratory total respiratory compliance.

Adult↗
PubMed1989

Whole-body vibration in underground load-haul-dump vehicles.

Whole-body vibrations (WBV) were measured at the seatpan of load-haul-dump (LHD) vehicles of 3.5-, 5-, 6- and 8-yard capacity at two underground mines. Twenty-two sets of measurements were made involving 11 vehicles, 8 operators and 4 work locations. In each set frequency-weighted rms and peak accelerations were measured in the x, y and z directions, as defined by the ISO (1982), during mucking, driving full, dumping and driving empty. Significant differences in rms accelerations were found between vehicle sizes and between operational tasks (less than or equal to 0.05). The smallest (3.5 yd) vehicle produced the greatest accelerations in the x and z directions. Accelerations in the x and z directions were also greater when driving full and empty than when mucking and dumping. The highest frequency-weighted rms accelerations of 2.0 to 2.8 m/s-2 were recorded in the z (longitudinal) direction. Peak accelerations ranged from 1.2 to greater than or equal to 20 m/s2, resulting in crest-factor ratios in excess of six. The exposure periods for each task were used to calculate mean daily acceleration exposures (m/s2). Of the 22 sets of measurements, 20 exceeded the International Standards Organization (ISO) six-hour daily exposure limit in the z direction of acceleration, and 9 exceeded the six-hour daily exposure limits in all three directions. Acceleration exposure ratios calculated using resultant acceleration vectors as described in ISO (1982), were found to exceed the ISO exposure limit for health or safety in all 22 cases. One-third octave band frequency analysis of the weighted signals indicated that the dominant frequencies were usually 1.6 to 3.15 Hz, except when the vehicles were idling and higher frequencies predominated.

Acceleration↗
PubMed1989

A reference shape library for computer aided socket design in above-knee prostheses.

A Reference Library of socket shapes for an Above-Knee Computer Aided Socket Design (CASD) System has been created. This library forms part of a more general CASD System (Dean & Saunders, 1985; Novicov & Foort, 1982). It consists of a matrix of reference shapes representing above-knee socket characteristics and is based upon skeletal structure, residuum length and tissue mass. A set of 27 biomechanical reference shapes in the form of male plaster casts were produced by a combination of CNC milling and traditional artisan techniques. Each reference shape was digitized to obtain its cylindrical coordinates. Cross-sectional areas and tissue distributions within each shape and between the shapes were analyzed, modified and then stored numerically within the computer for further implementation of the CASD System for the above-knee amputees. The creation and the analysis of the reference shape data is described.

Artificial Limbs↗
PubMed1989

Lung centroid pressure in immersed man.

Upright immersion imposes a pressure imbalance between alveolar and mean external thoracic pressure. Lung centroid pressure (PLC) is defined as the breathing pressure required to remove this imbalance. Static transrespiratory pressure-volume relationships were determined in subjects immersed in upright (n = 17) and prone (n = 13) postures. Compliances measured during immersion (1.87 +/- 0.15 liter.kPa-1 upright, 1.87 +/- 0.17 liter.kPa-1) prone) were compared with compliances, obtained over the same volume range, while upright in air (1.84 +/- 0.17 liter.kPa-1). PLC was determined by the horizontal (pressure) displacement of immersed compliance curves. PLC was calculated to be +1.33 +/- 0.11 kPa (+13.6 cmH2O) relative to the sternal notch when upright and -0.69 +/- 0.12 kPa (-7.0 cmH2O) relative to the sternal plane when prone (mean +/- SEM). Upright PLC did not support the widely used value of +19 cmH2O (Jarrett AS. J Appl Physiol 1965;20:1261-1266). Analysis shows that when data from earlier investigations were adjusted for differences in reference pressure, the collective PLC supports the present results.

Adult↗
PubMed1988

Chronic asthma and improvement with relaxation induced by hypnotherapy.

Sixteen chronic asthmatic patients inadequately controlled by drugs had, after one year of hypnotherapy, a fall in admissions from 44 in the year before starting therapy to 13 in the year after. Duration of stay was reduced for 13 patients by 249 days; prednisolone was withdrawn in 6, reduced in 8 and increased in none. Side effects of drugs were reduced. Although 62% reported improvement on a visual analogue scale, observations of air flow gave variable results.

Adolescent↗
PubMed1986

Evaluation of predictive formulae for determining metabolic rate during cold water immersion.

Five models predicting shivering thermogenesis on the basis of steady state skin and core temperature were evaluated: Hayward et al., Stolwijk and Hardy,; Nadel et al.,; Timbal et al., and Brown and Brengelmann, using the empirical data derived from a cold water immersion study by Morrison et al. A residual analysis indicated that all models generated substantial errors of prediction. The best overall predictors were expressions suggested by Hayward et al., while the predictive equation of Nadel et al. ranked second. Derivation of personal coefficients significantly improved the prediction of all models and a subsequent modification of the standard models, adding temperature derivative terms, further reduced the magnitude of the error. An analysis of the residuals indicated that peripheral and core temperatures should be weighted according to the characteristics of thermosensitive neural structures in these regions.

Body Temperature Regulation↗
PubMed1984

N-Nitroso(2-hydroxyethyl)glycine, a urinary metabolite of N,N-dinitrosopiperazine with potential utility as a monitor for its formation in vivo from piperazine.

Urinary metabolites in the rat of the carcinogen N,N-dinitrosopiperazine were identified as N-nitroso(2-hydroxyethyl)-glycine (22% of the dose), N-nitrosodiethanolamine (3%), 3-hydroxy-N-nitrosopyrrolidine (3%), and unchanged N,N-dinitrosopiperazine (18%). N-Nitroso(2-hydroxyethyl)glycine (1.6 mumol) was detected by gas chromatography-nitrosamine specific detection in the urine of rats treated by gavage with 19 mumol of piperazine and 191 mumol of sodium nitrite. Since sensitive methods are available to quantify N-nitroso(2-hydroxyethyl)glycine in rat urine and human urine, it has potential utility as a monitor for in vivo formation of N,N-dinitrosopiperazine.

Animals↗
PubMed1984

Moderate to high dose cyclophosphamide and intercalated Corynebacterium parvum in patients with metastatic lung cancer.

Thirty-nine patients with histologically proven widely metastatic bronchogenic carcinoma were treated with cyclophosphamide and Corynebacterium parvum. The dosage of cyclophosphamide was higher than conventional as previous work had indicated better results with increased dosage. Experimental work had suggested that the addition of Corynebacterium parvum would increase the antitumour effect and possibly reduce the cyclophosphamide induced granulocytopenia. A short treatment programme using three i.v. injections of cyclophosphamide, 1.5 g/m2, 2.5 g/m2 then 3.5 g/m2, at 3 week intervals were given. Four days after each cyclophosphamide injection, C. parvum 2 mg/m2 i.v. was administered. An overall 38% tumour response rate was observed, 18% for patients with non-small-cell carcinoma and 65% for small-cell carcinoma patients. The median survival for the 39 patients was 5 months (range 1-16+ months). These results, particularly for the non-small-cell patient group are comparable to those obtained with intensive combination chemotherapy regimens administered intermittently over much longer periods. An important consideration, objectively assessed in the present study, was the effect of treatment on quality of life and breathlessness. Improvement was noted not only in those patients with tumour response but also in a proportion of those who did not fulfil the criteria of response. Toxicity was also carefully assessed and, although the cyclophosphamide dosages were higher than conventionally used, no undue problems were noted. The addition of C. parvum did not have any noticeable beneficial effect. Cyclophosphamide given at dosages higher than is usual but which do not require bone marrow rescue is worthy of further study.

Adult↗
PubMed1984

A sensitive new method for the detection of N-nitrosomorpholine formation in vivo.

A sensitive method was developed for quantitation of N-nitrosomorpholine (NMOR) formation in vivo in rats. A major metabolite of NMOR, N-nitroso(2-hydroxyethyl)glycine, was detected by gas chromatography-thermal energy analysis in the urine of rats treated with trace levels of NMOR or treated sequentially with morpholine and sodium nitrite. Since significant levels of 2-hydroxyethylglycine do not seem to occur in rat urine, even after treatment with morpholine, artefact formation was not a problem. Formation of 1 micrograms NMOR in vivo was readily detected. The formation of NMOR from morpholine and sodium nitrite in vivo in rats appeared to depend on the doses of morpholine and [sodium nitrite]2 and occurred in higher yield than reported for formation of N-nitrosoproline, as expected. The formation of NMOR from morpholine and sodium nitrite under the conditions of the carcinogenicity study of Shank and Newberne was quantified. The daily levels of NMOR formation were highly variable, but the mean level was consistent with the tumorigenicity data in that dose-response study.

Animals↗
PubMed1984

Kinematic symmetry of the lower limbs.

This study examined the extent of kinematic symmetry of lower limbs when walking. Twelve able-bodied subjects were measured with a device which recorded three-dimensional motion of hip and knee joints bilaterally. Comparisons of right and left sagittal, transverse, and coronal plane motions were conducted in the time and frequency domains, and indices were developed to express these symmetries in each domain. In both domains high levels of symmetry were observed for the sagittal plane motions of hips and knees. High symmetry was also observed for the hip transverse and coronal plane motions, but symmetry was lower for these planes at the knee. Low standard deviations for the group occurred where symmetry was high. Reduced symmetry in the transverse and coronal planes was attributed to the lower signal to noise ratio for these planes. While experimental technique could be improved by better data collection procedures and by different analytic procedures, the study concluded that the able-bodied individual walks with reasonable symmetry at the hips and knees. These data formed a suitable baseline for comparison with pathologic gait data.

Adult↗
PubMed1984

Prostheses alignment: effect on gait of persons with below-knee amputations.

This study investigated the effect on gait of changing prosthetic alignment for five people with amputations. Three-dimensional angular kinematic data were recorded by electrogoniometers positioned at their hips and knees. Indices of symmetry were developed in time and frequency domains for motion data of lower limbs when walking. These measures of symmetry were determined at different prostheses alignment settings and used to assess the possibility of aligning below-knee prostheses on the basis of symmetry of lower limb motion. Optimal or neutral alignment of below-knee prosthesis, as selected by clinically experienced personnel, tended to minimize asymmetry of gait at the hips and knees for persons with below-knee amputations. The indices of symmetry showed that alignment changes to the prosthetic foot disrupt gait to a greater extent than do other alignment changes. Asymmetries of hip flexion-extension motions were more sensitive to alignment changes than were other asymmetries. An index was selected that showed sensitivity to changes in gait caused by changes in prosthetic alignment for below-knee amputations. Refinements and other applications of this index in rehabilitation are suggested.

Artificial Limbs↗
PubMed1984

A sensitive method for detecting in vivo formation of N-nitrosomorpholine and its application to rats given low doses of morpholine and sodium nitrite.

A method was developed to monitor the in vivo formation of N-nitrosomorpholine. N-Nitroso(2-hydroxyethyl)glycine, a major urinary metabolite of N-nitrosomorpholine, was quantified as its methyl ester-trimethylsilyl ether derivative, using gas chromatography with nitrosamine-specific detection. When the method was applied to rats, the in vivo formation of, or exposure to, as little as 0.6 micrograms of N-nitrosomorpholine could be quantified. The method was also applicable to human urine, with a detection limit of approximately 0.5 micrograms of N-nitroso(2-hydroxyethyl)glycine per 100-ml urine sample. The formation of N-nitrosomorpholine was measured in rats treated by gavage with a wide range of doses of morpholine and NaNO2. Depending on the dose, 0.5 to 12% of the morpholine was nitrosated. N-Nitrosomorpholine formation showed a high degree of variability among rats treated with a given dose of morpholine and NaNO2, but the levels of N-nitrosomorpholine formed were generally in agreement with expectations based on in vitro studies in which dependence on morpholine concentration multiplied by nitrite concentration squared has been established. The formation of N-nitrosomorpholine was also measured in rats administered a diet containing 50 ppm of morpholine and 1000 ppm of NaNO2, a regimen which has been previously shown to induce liver cell tumors in 58% of the animals. The mean daily formation of N-nitrosomorpholine under these conditions was estimated to be 0.88 +/- 0.59 mumol/rat (S.D.), which is high enough to account for the observed tumor incidence. The results of this study provide quantitative support for the assumption that in vivo formation of N-nitrosomorpholine leads to tumor development.

Animals↗
PubMed1983

N-nitroso-N-methyloctadecylamine in hair-care products.

Fifty-three cosmetic products containing one or more of the ingredients N,N-dimethyloctadecylamine oxide, N,N-dimethyloctadecylamine and N-benzyl-N,N-dimethyloctadecylammonium chloride were analysed for N-nitroso-N-methyloctadecylamine by gas chromatography with detection by a Thermal Energy Analyzer. [1-14C]N-Nitroso-N-methyloctadecylamine was used as an internal standard. Eight of 11 products containing N,N-dimethyloctadecylamine oxide and three of 38 products containing N-benzyl-N,N-dimethyloctadecylammonium chloride were found to contain N-nitroso-N-methyloctadecylamine at levels ranging from 28 to 969 ppb. In photolysis experiments, all of these products exhibited a loss of Thermal Energy Analyzer response for N-nitroso-N-methyloctadecylamine following irradiation by ultraviolet light. In two cases, the presence of N-nitroso-N-methyloctadecylamine was confirmed by combined gas chromatography-mass spectrometry.

Chromatography, Gas↗