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Biomedical subjects

R P Clarke

Publications and source records attributed to R P Clarke.

16 recordsLinked to original sources
PubMed1998

Outline of a theory of manic-depressive illness.

Manic-depressive illness is characterized by locking into extreme states and alternation between those extremes. Locking into extreme states is also characteristic of a bistable, a basic electronic device of which the essential feature is a positive feedback loop with greater than unity gain. An argument is presented that under natural selection there has evolved a well-known and advantageous tendency for perceptions of successes to increase confidence, and that it is in the nature of confidence to increase perceptions of successes. Thus arises a positive feedback loop, in which perceptions of successes increase confidence, which further increases perceptions of successes, and so on, and the converse with failure and inconfidence. When the gain of the loop exceeds unity then locking into mania or depression will result. The feedback gain depends on both internal 'biological' factors and external situational factors. As a result of natural fluctuations the gain will occasionally fall temporarily below unity, releasing from the extreme state. Escape from mania will bias towards depression, whereas escape from depression will be elating. The physical embodiment of confidence may be serotonergic (or closely related) activity.

Biofeedback, Psychology↗
PubMed1997

Malicious referees.

Explore the source record for details and available documents.

Peer Review, Research↗
PubMed1989

Hyperextension spinal fracture.

Hyperextension thoracolumbar spinal fractures are unusual and occur primarily in patients with ankylosed spines. Early diagnosis to avoid neurologic deterioration requires a high index of suspicion, given the paucity of radiographic findings. The biomechanics of the fracture and its treatment differ from more typical spinal fractures in several important aspects.

Biomechanical Phenomena↗
PubMed1988

Symptomatic, lateral synovial fringe (plica) of the elbow joint.

A series of patients with elbow symptoms suggesting intraarticular loose body(s) is presented. The symptoms included aching, stiffness, intermittent loss of motion, and catching. The clinical picture was seen in individuals without significant antecedent trauma. Arthroscopy in each case failed to demonstrate the anticipated loose body but did demonstrate a fibrotic synovial fringe that impinged between the radial head and the capitellum on repetitious elbow flexion and extension, particularly with the forearm in pronation. Arthroscopic excision of the fringe led to prompt recovery.

Adolescent↗
PubMed1987

Unstable intertrochanteric fractures of the hip.

In spite of a host of operative techniques and fixation devices, no one method of treatment has gained universal acceptance for the treatment of unstable intertrochanteric hip fractures. Although it is important to determine if a fracture is stable or unstable, stability should be considered a relative term. Degree of stability should be assessed by a careful review of the preoperative radiographs as well as postreduction films and palpation of comminution at surgery. Those fractures with minimal to moderate posteromedial comminution are probably best managed by anatomic reduction and compression hip screw fixation. The collapsing device will allow the fracture to obtain its own stability (Figure 5). However, in severely comminuted fractures the screw may slide completely prior to the stable apposition of cortical surfaces of the proximal and distal fragments. Fixation failure will result in a significant percentage of these fractures unless a stable reduction is obtained surgically. Medial displacement osteotomy, valgus osteotomy, or augmentation with cement should be considered in these high-risk fractures. Regardless of the reduction technique the proximal fragment must be aligned properly with the femoral shaft. If the major fracture fragments are prevented from reaching a stable configuration, fixation failure will likely occur (Figure 6).

Bone Nails↗
PubMed1986

Chronic rotator cuff tears.

The treatment of chronic rotator cuff tears is a controversial topic. Proponents of conservative therapy cite cadaver studies and postulate that with time the inflammatory reaction will subside and that although the structural integrity of the cuff may not be completely intact, the patient will nevertheless have an excellent functional result. On the other hand, operative intervention proponents contend that better mechanical advantage to shoulder motion will be present with an intact rotator cuff and that excision of necrotic tissue will alleviate impingement and pain. This paper is an overview of the topic and discusses some of the treatment modalities.

Humans↗
PubMed1981

Nutrient intake, adiposity, plasma total cholesterol, and blood pressure of rural participants in the (Vermont) Nutrition Program for Older Americans (Title III).

The interrelationships of obesity, hypertension, elevated plasma cholesterol (risk factors), and intakes of selected nutrients were examined among elderly subjects attending a congregate meal program in Vermont. Mean nutrient intakes were significantly higher for 22 males compared to 69 females. Mean plasma cholesterol levels were higher in females. Age, systolic and diastolic blood pressure, and indices of adiposity showed no sex differences. Intakes of total fat and animal protein increased in males but plasma cholesterol decreased with age. Systolic blood pressure in females increased while body mass index decreased with age. A higher proportion of females had plasma cholesterol levels greater than or equal 260 mg/100 ml and a higher proportion of females than males greater than 73 yr of age had blood pressures at risk level. There was a greater proportion of females than males with both elevated plasma cholesterol levels and adiposity. Similarly the females had greater incidence of the combination of any two risks. No males, compared to 9% of females, were in the all three risk category.

Aged↗
PubMed1979

Trochanteric osteotomy: analysis of pattern of wire fixation failure and complications.

Problems and complications following trochanteric osteotomy in 277 total hip replacements demonstrated that while the value of trochanteric osteotomy is obvious, the incidence of problems and complications in 277 total hip replacements was about 15%. Analysis was made of the location and sequence of wire failure following different techniques of trochanteric wiring. The usual method of wire failure was by fatigue fracture, although early fracture in the post-operative phase may be secondary to tensile failure, The incidence of wire tensile failure can be increased by inadvertent kinking or scoring of the wire during trochanteric fixation. An ununited trochanter should be protected against wire failure and its sequelae.

Follow-Up Studies↗
PubMed1977

Comparison of the nutritional status of pregnant adolescents with adult pregnant women. III. Maternal protein and calorie intake and weight gain in relation to size of infant at birth.

Factors influencing the outcome of pregnancy were studied in 98 women, ages 12 to 32, divied into four age groups. A significantly higher weight gain was recorded for the youngest age group and the lowest gain for the oldest age group. The amount of weight gained was a function of length of gestation, but was not influenced by calorie intake of the mother. Neither was there significant correlation between protein and calorie intake of the mother and the infant's birth weight. Mean calorie intakes averaged below and mean protein intakes above the 1974 RDA. About 10% of the infants weighed less than 2,500 g and no single factor could be identified as the cause of low birth weight.

Adolescent↗
PubMed1975

Comparison of the nutritional status of pregnant adolescents with adult pregnant women. II. Anthropometric and dietary findings.

Weight, triceps and subscapular skinfold measurements, and mean intakes of 11 nutrients and calories were evaluated for 102 pregnant women in four age groups. The increase in weight during the antepartum period was the only significant finding for anthropometric measurements. Comparison of antepartum group means showed the two younger groups, 12-17 and 18-19 years, had higher intakes of calories, protein, fat, carbohydrate, calcium, phosphorus, and iron than the two older groups, 20-24 and 25-32. The two older groups had higher mean intakes of vitamin A, thiamin, niacin, and ascorbic acid, most of them significantly so. In the postpartum period, there were no significant differences among age groups for mean intakes of calories, protein, fat, carbohydrate, or phosphorus. The two older groups had the higher mean intakes of the remaining nutrients. There were no significant differences among age groups for any of the nutrients with respect to level of education. Regardless of age, the subjects attending the low-cost clinic had a mean intake of iron significantly higher than those having private physicians, while the latter had a mean ascorbic acid intake significantly higher than that of the clinic group.

Adolescent↗
PubMed1975

Comparison of the nutritional status of pregnant adolescents with adult pregnant women. I. Biochemical findings.

Biochemical findings on blood samples from 102 pregnant women in four age groups, 12-17, 18-19, 20-24, and 25-32, are reported. Samples represent 8 antepartum periods of 4 weeks each and 3 postpartum periods over 6 weeks. Blood analyses were carried out for hemoglobin, plasma iron, plasma total protein, glucose, plasma alkaline phosphatase, plasma ascorbic acid, plasma vitamin A and carotene, erythrocyte transketolase as a measure of thiamine status, plasma cholesterol, plasma lipid phosphorus, plasma total fatty acids, and triglyceride fatty acids. For the most part, means of these nutrients were in acceptable ranges for all age groups. Although adolescents had better levels than anticipated, the two younger groups on several occasions had means significantly lower than those of the two older groups, indicating that they needed greater nutritional support during pregnancy than older women.

Adolescent↗