C J Alexander | PubMed Health

PubMed1992

The threshold effect: consequence of change in the frequency of food intake in the presence of a functional threshold.

Studies on diseases thought to be diet-induced have so far assumed that the effect of a food depends solely on the amount ingested. When the metabolism of a food derivative is dependent on a threshold-dependent mechanism this single variable assumption is invalid, as the net effect of the derivative will also depend on intake frequency. In this paper the consequences of varying intake frequency in the presence of a notional threshold are analysed mathematically. It is shown that at the low frequency end of the scale relevant to human diet, if a metabolic threshold exists then the net effect of a food will be critically dependent on intake frequency, and that the effect of changing frequency may exceed that produced by even substantial changes in quantum. It is concluded that epidemiological studies which have not included data on frequency of intake involve a potential error and could be misleading.

Diet↗

PubMed1991

Psychological assessment and treatment of sexual dysfunctions following spinal cord injury.

Sexual dysfunction following SCI has received increased attention in recent years. Despite this attention, many physicians and allied health care workers respond to patients' sexual concerns with dismissal or reassurance. Moreover, physiological and medical aspects of sexual dysfunction tend to be emphasized at the exclusion of the emotional aspects of sexuality. A multidimensional, integrative approach to the assessment and treatment of sexual dysfunctions across the entire sexual response cycle following SCI is emphasized. The rationale and procedure of brief sexual counseling is discussed.

Humans↗

PubMed1990

Osteoarthritis: a review of old myths and current concepts.

Radiology is dependent on an accurate understanding of the pathological process. This review of primary osteoarthritis identifies eight areas in which widely held concepts are either demonstrably false or fall short of proof. In some, the concepts have been disproved by the gradual accumulation of evidence. In others, the error is due to radiological misinterpretation while in a third group, the evidence is not in dispute, but the logical framework used in its assessment is flawed. Awareness of these deficiencies simplifies radiological interpretation and clarifies research objectives.

Aging↗

PubMed1989

Relationship between the utilisation profile of individual joints and their susceptibility to primary osteoarthritis.

Two subjects were studied for 1 to 3 weeks during the course of their normal domestic activities. Utilisation profiles were derived for ten joints, using a systematic time-series sampling technique adapted from behavioural biology. At each joint the proportion of the available range utilised was noted. The results were compared with the known regional prevalence of primary osteoarthritis. There was a correlation between the degree to which a joint was incompletely utilised, and its susceptibility to osteoarthritis. The hypothesis is advanced that primary osteoarthritis may be due to incomplete joint utilisation.

Activities of Daily Living↗

PubMed1988

Prevention of steroid-induced osteoporosis with (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate (APD).

In a prospective, randomised, placebo-controlled trial comparing the effect of (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate (APD) (150 mg/day) plus calcium (1 g/day) with that of calcium alone on the bone mass of patients receiving long-term glucocorticoid therapy, the mean metacarpal cortical area in patients receiving APD increased by 1.2% between 0 and 6 months (p less than 0.06) and then remained stable between 6 and 12 months. In contrast, this index progressively declined in the placebo group (p less than 0.05 at 12 months). The two groups differed significantly in the changes at both 6 and 12 months (p less than 0.01). Mean vertebral mineral density, as measured by quantitative computed tomography, increased by 19.6% over 12 months in the APD group (p less than 0.02) but showed a non-significant decline of 8.8% in controls. The differences between the changes were again significant (p less than 0.005). Biochemical indices and bone histomorphometry indicated a reduction in bone resorption and bone formation but there was no evidence of osteomalacia. APD may thus prevent bone loss in glucocorticoid-treated patients over a year.

Calcium↗

PubMed1988

The threshold effect: consequences of change in the frequency of food intake in the presence of a functional threshold.

Studies on diseases thought to be diet-induced have so far assumed that the effect of a food depends solely on the amount ingested. When the metabolism of a food derivative is dependent on a threshold-dependent mechanism this single variable assumption is invalid, as the net effect of the derivative will also depend on intake frequency. In this paper the consequences of varying intake frequency in the presence of a notional threshold are analysed mathematically. It is shown that at the low frequency end of the scale relevant to human diet, if a metabolic threshold exists then the net effect of a food will be critically dependent on intake frequency, and that the effect of changing frequency may exceed that produced by even substantial changes in quantum. It is concluded that epidemiological studies which have not included data on frequency of intake involve a potential error and could be misleading.

Eating↗

PubMed1979