Does longer-term memory storage never become overloaded, and would such overload cause Alzheimer's disease and other dementia?

According to an uncritically accepted axiom, the human brain's capacity for longer-term memory storage is never overloaded. This viewpoint is shown to be contrary to all evidence and beyond reasonable credibility. The entire currently obtainable evidence for or against overload comes via the presence or absence of its manifestation in behaviour. This manifestation would be as an incurable, deteriorating, specific form of memory disorder, associated with old age and consequent to increased data-inputting and reductions of brain capacity. There is in fact such a disorder, namely Alzheimer's disease and other dementia. This relationship provides elegant explanations for various peculiar findings, without encountering any counter-evidence. The premorbid accumulation of tangles in the hippocampus is explained via an integration of existing hippocampus theories. Long-term low doses of drugs that reduce memory formation could prevent or delay dementia. TV-watching, videos, and some memory-enhancing nootropic drugs could increase risk.

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.

The seismic retrofitting of local clay block walls : Research in Progress

The Caribbean region is a high risk area with respect to earthquakes. However, the vast majority of buildings, especially the residential structural, have not been designed to withstand earthquakes. This paper discusses research in progress at The University of the West Indies, St. Augustine, on a retrofitting method using ferrocement overlays on the faces of walls built with clay blocks common to the region but particularly to Trinidad and Tobago. Variables include mesh type, number of layers, and vertical pressure. Datailed data on this retrofitting method is scarce and apparently non-existent for clay blocks with horizontal cores such as the local blocks. The approach is to develop a cyclic constitutive model for the walls and, using this information, conduct a study of common low-rise structures via dynamic analysis. The study will culminate in the preparation of design and construction guidelines.(AU)

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.

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.

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).

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.

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.

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.

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.

PIP: 98 pregnant women, aged 12-32, were studied to determine factors influencing the outcome of pregnancy. A comparison of the nutritional status of pregnant adolescents with adult pregnant women was made. Data on the age of the mother at conception, the week of delivery, her weight gain, her protein and calorie intakes, the size of infant at birth, and the Apgar Score of the infant were used. A significantly higher weight gain was recorded for the youngest group (12-17 years) and the lowest gain for the oldest group (25-32 years). The interaction between age and length of pregnancy was also significant (p less than .028). Calorie intake was unrelated to the amount of weight gained. Weight gain was, however, a function of length of gestation. Calorie and protein intake of the mother was an insignificant factor affecting the infant's birth weight. Low birth weight in about 10% of the infants was untraced to any single factor studied.

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.

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.