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Biomedical subjects

L Parker

Publications and source records attributed to L Parker.

At least 181 records · Page 10Linked to original sources
PubMed1990

Fetal asphyxia stimulates an increase in fetal plasma catecholamines and [Met]-enkephalin-arg6-phe7 in the late-gestation sheep fetus.

We have investigated whether enkephalin-containing peptides and catecholamines are increased in fetal plasma during periods of reduced uterine blood flow which produce moderate fetal asphyxia (i.e. hypoxemia, hypercapnia and acidemia). Experiments (n = 16) were performed in 11 ewes between 121-139 days gestation. In 8 experiments a clamp placed around the common iliac artery of the ewe was adjusted to produce a 50% reduction in the partial pressure of arterial oxygen (PO2) in fetal plasma for 30 min between 121-125 days gestation (n = 4) and between 131-139 days gestation (n = 4). Control (n = 8) experiments were performed when the arterial clamp was not adjusted. There was no significant effect of asphyxia on fetal plasma noradrenaline concentrations before 126 days gestation. After 130 days gestation during asphyxia, fetal plasma noradrenaline concentrations increased significantly from 2.20 +/- 0.72 pmol/ml (-15 min) to 14.06 +/- 0.75 pmol/ml (+5 min). The fetal adrenaline response to asphyxia did not change with increasing gestational age and after 130 days gestation fetal plasma adrenaline increased significantly from 1.48 +/- 0.46 pmol/ml (-15 min) to 4.05 +/- 1.22 pmol/ml (+10 min). Met-enkephalin-arg6-phe7 immunoreactivity was measurable (25-117 pg/ml) in all pre-experimental fetal sheep plasma samples collected between 121-139 days gestation. There was no specific effect of asphyxia on fetal plasma [Met]-enkephalin-arg6-phe7-IR before 130 days gestation. However after 130 days gestation, there was a significant increase in fetal plasma (Met-enkephalin Arg-6-phe7-IR above baseline values, when compared to control experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

The differential diagnosis of nasal mucosal swelling and adenoidal hyperplasia using two- and three-parameter discriminant functions.

Elevated nasal resistance, as a result of nasal mucosal swelling and/or adenoidal hyperplasia, has been associated with an increased incidence of mouth breathing, which may lead to alterations in facial morphology. The classical approach to studying this problem clinically has been through the adoption of percentiles and various other norms. However, these techniques are only crude estimates and are subject to error. We have developed a novel approach to the assessment of nasal resistance measurements that provides the means for its differential diagnosis. Two- and three-parameter discriminant (or classification) functions were found to replicate an experienced orthodontist's clinical diagnosis very accurately. We also propose the adoption of "sensitivity" and "specificity" when discussing the evaluation and/or success of such models.

Adenoids↗
PubMed1989

Twenty-four-hour sleep-wake patterns in a nursing home population.

Sleep-activity patterns were objectively recorded over a 24-hr period in 19 elderly nursing home residents. On average, both sleep and wake times were observed during every hour of the 24 recorded hours; however, the sleep pattern of the residents was fragmented so that they rarely experienced even a single hour of consolidated time spent sleeping. It is hypothesized that several independent factors, including compensation for lost sleep, increased total time in bed, weakening of social constraints, and deterioration of the circadian sleep-wake rhythm, are interacting to produce this increase in sleep fragmentation.

Activities of Daily Living↗
PubMed1989

Sleep fragmentation in patients from a nursing home.

Institutionalized elderly persons are said to have very disturbed sleep, yet few studies have collected empirical data on the sleep of these patients. We recorded sleep in 200 patients (131 females and 69 males; mean age = 81.9 years, SD = 8.6) in a skilled nursing facility. A modified Respitrace-Medilog portable recording system was used. In recordings averaging 15.4 hours, the patients were asleep for 7 hours, 58 minutes and awake for 7 hours, 28 minutes. To obtain that amount of sleep, the patients spent an extended time in bed during the day, for they averaged no more than 39.5 minutes of sleep per hour in any hour of the night, and 50% woke up at least 2 to 3 times per hour. In summary, although nursing home patients slept on average only one hour longer than independently living elderly, they had to spend substantially more time in bed to obtain the same amount of sleep.

Activity Cycles↗
PubMed1989

Response to sodium lactate infusion in alcoholics with panic attacks.

The authors studied the response to sodium lactate infusion of 12 alcoholics with a history of panic attacks, 10 alcoholics without a history of panic attacks, and 16 nonalcoholic patients with panic disorder. The rate of lactate-induced panic was significantly higher in alcoholics with panic attacks than in alcoholics without panic attacks. Alcoholics with panic attacks were similar to nonalcoholic patients with panic disorder in their response to lactate. These findings support the specificity of lactate-induced panic for panic states and suggest that panic attacks in alcoholics resemble those in nonalcoholics. Lactate infusion may prove useful in the diagnosis of panic disorder in alcoholics.

Adult↗
PubMed1989

Prevalence, onset, and clinical recognition of panic states in hospitalized male alcoholics.

Alcoholism has been associated with a high prevalence of anxiety and phobic disorders. The authors ascertained the current prevalence of panic disorder and the lifetime prevalence of infrequent panic attacks in 154 male alcoholics in an inpatient alcohol treatment program. Thirteen percent (N = 20) gave a lifetime history of panic attacks and 45% (N = 9) of these had current panic disorder. Panic attacks preceded or coincided with the onset of problem drinking in 50% (N = 9) of the 18 patients with both diagnoses. Only two patients with histories of panic had been previously diagnosed, and none had been treated. Clinical implications of these findings are discussed.

Adult↗
PubMed1989

Generation of Met-enkephalin Arg6Phe7 immunoreactivity by proteolytic cleavage of mammalian plasma precursors by pepsin.

A region-specific antiserum raised against the C-terminal heptapeptide of proenkephalin A (Met-enk Arg6Phe7) was used in RIA studies to show that rat, human, and ovine plasma contain substrates (mol wt, 68K) that yield nanomolar amounts of Met-enk Arg6Phe7 (ME-RF) after treatment with pepsin under acid conditions. This ovine plasma-derived immunoreactivity diluted in parallel to the ME-RF standard in RIA and chromatographed as two low mol wt species (approximately 1K) which were less hydrophobic than the standard on size exclusion and reverse phase chromatography. The pepsin-generated material displaced [3H]naloxone from rat brain binding sites; its potency was about 1000-fold that of ME-RF, assuming near 100% cross-reactivity with the antiserum. Taken together these observations suggest that the pepsin-generated material is of similar mol wt and amino acid sequence to ME-RF, but differs with respect to opiate-binding efficacy, and that the plasma precursor is distinct from proenkephalin in both size and processing sites.

Animals↗
PubMed1989

Sleep apnea in female patients in a nursing home. Increased risk of mortality.

There has been much speculation on the risk of mortality associated with sleep apnea. We followed-up 233 elderly patients in nursing homes, 70 percent of whom had five or more respiratory disturbances per hour of sleep, to determine if sleep apnea is a predictor of mortality. Cox proportional hazards survival analyses indicated a gender effect, with women having a much better survival rate than men. In women, but not in men, there was a strong association between mortality and the RDI. In addition, patients with obstructive sleep apnea had a greater tendency to die in their sleep. These results show that respiratory disturbances in sleep are an extremely significant risk factor for mortality in elderly women who are in poor health.

Aged↗
PubMed1988

The epidemiology of malignant neoplasms of the nasal cavities, the paranasal sinuses and the middle ear in Canada.

Canadian patterns of morbidity and mortality from malignancies of the nasal cavities, the paranasal sinuses and the middle ear for the periods 1970-1980 and 1970-1984 have been examined. Age-standardized morbidity rates have not changed significantly during 1970-1980 for either males (P = 0.65) or females (P = 0.96). Analysis of age-specific morbidity rates revealed that rates of change for male rates have also remained stable during this period for all age groups studied (P greater than 0.29). For females, rates of change for seven of eight age groups examined also failed to achieve statistical significance (P greater than 0.30). However, rates for females aged 45-54 have shown an increase of 0.35 additional new cases per 1,000,000 population per year. This finding is of borderline significance (P = 0.051). In contrast, age-standardized mortality rates have declined significantly during 1970-1984 by, on average, 0.08 and 0.07 fewer deaths per 1,000,000 population per year in males and females respectively. Analysis of age-specific mortality rates reveals that the declines in mortality are attributable to significant reductions in age-specific rates for males aged 65-74 and 85+ and females aged 0-24, 55-64, and 85+. In these groups rates have declined by as much as 4.1 fewer deaths per 1,000,000 population per year (P less than 0.045).

Adolescent↗
PubMed1988

Indirect estimation of maximal oxygen uptake for study of working populations.

A total of 345 shipyard workers (aged 23 to 47) volunteered to perform progressive exercise on a cycle ergometer (15 W/min increments) up to the symptom limited maximum. The results were used to obtain maximal oxygen uptake (nO2 max), the oxygen uptake at a respiratory exchange ratio of unity (nO2 at R1.0), and cardiac frequency at an oxygen uptake of 45 mmol/min (fC45). In this group 156 men (45% of initial population) attained nO2 max as defined, 108 (31%) withdrew or did not exercise maximally, and 49 (14%) had transient electrocardiographic abnormalities. For the 156 men extrapolation of the relation of cardiac frequency on oxygen uptake to the predicted maximal cardiac frequency resulted in overestimation of nO2 max by 9.6%. nO2 Max per kg body mass was negatively correlated with body mass. nO2 Max (mean value 130.6 mmol/min) was described in terms of age, fat free mass, smoking (yes or no), and level of habitual activity (rated 1 to 4): the standard error of the estimate (SEE) was 17.3 mmol/min (R2 0.42); the equation was suitable for reference values. For estimating the nO2 max of individual men an empirical relation based on nO2 at R1.0, fC45, fat free mass, and % body fat had an SEE of 12.1 mmol/min (R2 0.67). Seventy six per cent of men (88% of those who exercised) attained nO2 at R1.0 (oxygen uptake approximately 73% of maximum). Thus the nO2 max could be estimated in a higher proportion of men than could achieve nO2 max. The estimate is appropriate for assessing exercise capacity in relation to employment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗