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Biomedical subjects

J M Patrick

Publications and source records attributed to J M Patrick.

At least 55 records · Page 3Linked to original sources
PubMed1978

The breathing pattern after breath-holding: the influence of chest position and the drive to breathe.

The pattern of breathing following the breaking-point of sixty breath-holds has been studied in five healthy adults and compared with the pattern during recovery from CO2-rebreathing. The volume and direction of the first respiratory movement, and the VT, V relation for the first four complete breaths was measured. Only when breath-holds were terminated with an inspiration was the accumulated drive to breathe reflected in an increased volume of the first respiratory movement: terminating expirations simply returned the chest to the resting respiratory level. The volume of the first inspiration was not influenced by the intervention of a terminating expiration, suggesting that expiratory movements do not dissipate the non-chemical component of the drive to breathe. In three of the five subjects the tidal volumes for given levels of ventilation were greater following breath-holding than following rebreathing. This altered pattern of breathing has been interpreted in terms of an insiratory-augmenting reflex.

Adult↗
PubMed1977

Toxicity and bioconcentration of BHC and lindane in selected estuarine animals.

Flow-through, 96-hr bioassays were conducted to determine the acute toxicity of technical BHC and lindane to several estuarine animals. Test animals and their respective 96-hr lindane LC50 values were: mysid (Mysidopsis bahia), 6.3 microgram/L; pink shrimp (Penaeus duorarum), 0.17 microgram/L; grass shrimp (Palaemonetes pugio), 4.4 microgram/L; sheepshead minnow (Cyprinodon variegatus), 104 microgram/L; and pinfish (Lagodon rhomboides), 30.6 microgram/L. The 96-hr LC50 values for pink shrimp and pinfish exposed to BHC were 0.34 and 86.4 microgram/L, respectively. Two BHC bioconcentration studies were conducted with the oyster, Crassostrea virginica, and pinfish. After 28 days exposure, oysters bioconcentrated an average of 218 X the BHC measured in exposure water, while pinfish bioconcentrated 130 X in their edible tissues and 617 X in offal. After one week in BHC-free sea water, no detectable residues were measured in oysters or pinfish.

Animals↗
PubMed1977

A study of exercise performance and heart rate: the response to exercise of a small group of manual workers before and after retirement.

Measurements of walking pattern, exercise performance, heart rate response to exercise and body composition have been made in 13 male manual workers at retirement and again one and two years later. The exercise consisted of walking, in accordance with standard instructions; heart rate and footfall signals were recorded on magnetic tape during the test using body-borne tape recorders. After the first year highly significant reductions in walking speed were found but no significant changes in walking pattern, heart rate response or body composition. When the measurements made at the end of one year of retirement were compared with those made at the end of two years no significant changes were found.

Aged↗
PubMed1976

Thoracic and lumbar spinal curvatures in Nigerian adults.

The thoracic and lumbar curvatures of 105 Nigerian adults have been measured with a flexible rule (flexicurve). The lumbar curvature is relatively greater in women. Compared with a previous survey of Europeans, the curvatures in both men and women appear to be about 20 per cent greater in Nigerians. This is likely to be a genetic difference but the Nigerian practice of carrying heavy loads on the head may be a contributory factor.

Adult↗
PubMed1976

Chlordane: effects on several estuarine organisms.

Dynamic marine toxicity tests were performed with technical grade chlordan and eastern oysters (Crassostrea virginica), pink shrimp (Penaeus duorarum), grass shrimp (Palaemonetes pugio), sheepshead minnows (Cyprinodon variegatus), and pinfish (Lagodon rhomboides). The 96-hr LC20S (and 95% confidence limits) based on measured concentrations of chlordane (in mug/liter) are: ping shrimp 0.4 (0.3-0.6); grass shrimp, 4.8 (4.0-6.0); sheepshead minnows, 24.5 (19.9-28.6); and pinfish, 6.4 (5.0-7.3). The 96-hr EC50 for eastern oysters was 6.2 (4.8-7.9). In a flow-through test, embryos and fry of sheepshead minnows were exposed to average measured concentrations of chlordane from 1.3 to 36.0 mug/liter for 28 days. Neither fertilization success nor embryo survival was affected by the concentrations of chlordane to which these life stages were exposed. However, sheepshead minnow fry did not survive for more than 10 days in chlordane concentrations greater than 7.1 mug/liter.

Animals↗
PubMed1976

Heptachlor: toxicity to and uptake by several estuarine organisms.

Technical-grade heptachlor (65% heptachlor, 22% trans-chlordane, 2% cis-chlordane, and 2% nonachlor) was tested in 96-hr bioassays to determine its toxicity to estuarine animals. The test organisms and the 96-hr LC50 or EC50s based on measured concentrations in water) are as follows: American oyster (Crassostrea virginica), 1.5 mug/liter; pink shrimp (Penaeus duorarum), 0.11 mug/liter; grass shrimp (Palaemonetes vulgaris), 1.06 mug/liter; sheepshead minnow (Cyprinodon variegatus), 3.68 mug/liter; pinfish (Lagodon rhomboides), 3.77 mug/liter; and spot (Leiostomus xanthurus), 0.85 mug/liter. Analytical-grade heptachlor (99.8% heptachlor) and heptachlor epoxide (99%) were also studied. The analytical-grade heptachlor 96-hr LC50 for pink shrimp and spot was 0.03 mug/liter and 0.86 mug/liter, respectively, while that for pink shrimp exposed to heptachlor epoxide was 0.04 mug/liter. Heptachlor was accumulated and some metabolized to its epoxide by all animals tested. Fish and oysters accumulated heptachlor in their tissues 2,800-21,300 times the measured concentration in water; shrimp, only 200-700 times.

Animals↗
PubMed1976

Heptachlor: uptake, depuration, retention, and metabolism by spot, Leiostomus xanthurus.

The estuarine fish, spot (Leiostomus xanthurus), was exposed to 0.27, 0.52, 1.01, 1.99, and 3.87 mug/liter technical grade heptachlor (65% heptachlor, 22% trans-chlordane, 2% cis-chlordane, 2% nonachlor, and 9% unidentified compounds) for 24 days in a flowthrough bioassay, followed by 28 days in heptachlor-free seawater. Concentrations of heptachlor, heptachlor epoxide, and trans- and cis-chlordane in edible tissues were monitored at day 3 and weekly thereafter throughout the bioassay and at the end of the postexposure period. All four chemicals were accumulated by spot. Maximum concentrations of heptachlor were observed on day 3; maximum concentrations of the other three compounds were observed on day 17. The average bioconcentration factors for heptachlor and trans-chlordane were 3,600 and 4,600, respectively. Only 10% or less of the maximum concentrations of heptachlor, heptachlor epoxide, and trans-chlordane accumulated during the exposure period remained after 28 days in pesticide-free seawater; an average of 35% of the cis-chlordane remained. Relative total amounts of heptachlor and cis-chlordane changed during the exposure and post-exposure periods. Nearly all of the heptachlor was eliminated or metabolized to its epoxide. Cis-chlordane, which averaged 4-7% of the total residues (chlordanes and heptachlors) in edible tissues during the exposure, increased to 18-23% of the total residues by the end of the postexposure period.

Animals↗
PubMed1976

Respiratory responses to CO2-rebreathing in Nigerian men.

In 36 young Nigerian men, ventilatory capacity and the changes in ventilation, tidal volume and tidal P CO2 during oxic CO2-rebreathing have been measured. CO2 response lines and breathing rhythms have been determined and analysed in relation to the anthropometric and lung function data. Previous findings that Nigerian men have a substantially lower ventilatory capacity than Europeans at a standard height and age are confirmed. Breathing rhythms in Nigerians appear to be the same as in other ethnic groups studied. CO2-sensitivity varies with FVC, as found previously in Europeans and New Guineans. However, at a standard FVC of 41, Nigerian men have the same CO2-sensitivity as Europeans, and not a lower value like New Guineans.

Adolescent↗