Relation of low diastolic blood pressure to coronary heart disease death in presence of myocardial infarction: the Framingham Study.

OBJECTIVE--To examine the hypothesis that a J curve relation between blood pressure and death from coronary heart disease is confined to high risk subjects with myocardial infarction. DESIGN--Cohort longitudinal epidemiological study with biennial examinations since 1950. SETTING--Framingham, Massachusetts, USA. SUBJECTS--5209 subjects in the Framingham study cohort followed up by a person examination approach. MAIN OUTCOME MEASURES--Coronary heart disease deaths and non-cardiovascular disease deaths in men and women with or without myocardial infarction relative to blood pressure. RESULTS--Among subjects without myocardial infarction non-cardiovascular disease deaths were twice to three times as common as coronary heart disease deaths. Furthermore, there was no significant relation between non-cardiovascular disease death and diastolic or systolic blood pressure. Also coronary heart disease deaths were linearly related to diastolic and systolic blood pressures. Among high risk patients (that is, people with myocardial infarction but free of congestive heart failure) death from coronary heart disease was more common than non-cardiovascular disease death. There was a significant U shaped relation between coronary heart disease death and diastolic blood pressure. Although there was an apparent U shaped relation between coronary heart disease death and systolic blood pressure, it did not attain statistical significance when controlling for age and change in systolic blood pressure from the pre-myocardial infarction level. None of the above conclusions changed when adjustments were made for risk factors such as serum cholesterol concentration, antihypertensive treatment, and left ventricular function. The U shaped relation between diastolic blood pressure and high risk subjects existed for both those given antihypertensive treatment and those not. CONCLUSIONS--These data suggest that an age and sex independent U curve relation exists for diastolic blood pressure and coronary heart disease deaths in patients with myocardial infarction but not for low risk subjects without myocardial infarction. The relation seems to be independent of left ventricular function and antihypertensive treatment.     

The Epidemiology of Dental Diseases in the Elderly1

This paper summarizes and evaluates epidemiologic evidence on adult dental conditions with a focus on older adults. Information is presented on coronal caries; root caries; loss of teeth, attrition, abrasion, and erosion; periodontal diseases; and oral cancer. The author concludes that the oral health status of the elderly in the United States is essentially unknown. There are no recent, representative population base studies of oral conditions in the elderly. Studies of prevalence or incidence of oral diseases typically include few elderly persons or describe a select group of elderly who are at high risk. Furthermore, it is not really known whether the incidence and prevalence of coronal caries or root caries is actually increasing or is part of a cohort effect. While oral cancers have been shown to increase with age, there is no information as to whether their incidence rates are increasing. While, clinically, there are indications that attrition, abrasion and erosion are characteristics that are more likely to be seen in older adults, there is no information about their distribution in the population. There is evidence that loss of teeth is decreasing but nothing is known about the patterning of that loss. As for periodontal diseases, much work is needed to identify various syndromes that may be distinguished by their distribution in the population as well as determining whether periodontitis is a condition responsible for a majority of tooth loss or just the majority of tooth loss in a small high risk group. In addition, some suggestions are presented for future directions of research in this area.     

Contrasting tactics in motor control by vertebrates and arthropods

Vertebrates and arthropods share the common problem of controllinga rigid, articulated skeleton using neurally-controlled, striatedmuscle. Since this condition has arisen independently in thetwo groups, there is no reason to assume, a priori, that thecontrol mechanisms used by the two groups will be the same.Indeed, there appear to be fundamental differences in the tacticsused by the two groups. Insects and crustaceans use small numbersof heterogeneous motoneurons, while vertebrates (mammals especially)use many, more homogeneous, motor axons. In particular, arthropodsmake extensive use of peripheral neuromodulation to alter theproperties of both neuromuscular junctions and muscle fibers.There has been little consideration of the functional consequencesof these differences. I suggest that, faced with a size constrainton the number of motor units available, arthropods use peripheralmodulation of muscle properties to achieve the flexibility anddynamic range that vertebrates achieve through recruitment ofmotor units.     

A colorimetric assay for 7-dehydrocholesterol with potential application to screening for Smith-Lemli-Opitz syndrome

Smith-Lemli-Opitz syndrome (SLOS; MIM 270400) is a genetic disorder characterized by hypocholesterolemia and elevated 7-dehydrocholesterol (7DHC) levels resulting from mutations affecting 7-dehydrocholesterol reductase. We describe a colorimetric assay for 7DHC with potential application to large-scale screening for SLOS. Reaction of 7DHC and its esters with the Liebermann-Burchard reagent resulted in a brief initial absorbance at 510 nm (pink color) followed by an absorbance at 620 nm (blue color) after 2 min, while cholesterol samples were essentially colorless. The assay could identify typical SLOS blood samples by their pink color and increased absorbance at 620 nm after 2 min. Colorimetric identification of mild SLOS cases requires monitoring of the transient absorbance at 510 nm, which must be detected immediately after rapid, consistent mixing of the reagents. The need for special mixing devices and rigorous validation precludes sporadic use of the assay for diagnosing suspected SLOS cases. We also studied the stability of 7DHC in dried SLOS blood spots on Guthrie cards, which are widely used for archiving neonatal blood. Decomposition of 7DHC was effectively retarded by storage at low temperature and by precoating of the cards with antioxidants. The combined results provide a foundation for development of a simple, automated test for SLOS screening.     

Combined kinematic and electromyographic analyses of proleg function during crawling by the caterpillar Manduca sexta

The planta retractor muscles in the prolegs of Manduca sexta caterpillars are a frequently-used model system for investigating a number of problems in neurobiology. We have combined kinematic and electromyogram analysis of proleg movements during crawling to examine the roles of these muscles during normal behavior. We found that retractor muscle activity is highly stereotyped, and that the primary function of these muscles is to disengage the crochets at the tip of the proleg for the swing phase of crawling. The duration of activity of the muscles was tightly coupled to the phasing of crawling behavior. The stepping patterns of animals changed to accommodate variations in the substrate, but the relative timing of retractor muscle activity was unaffected. There were no clear correlations between the various properties of motoneuronal input to the muscle (duration of activity, number of spikes, peak frequency of spikes) and the resulting muscle length change. Perhaps because it functions partially as a hydrostat, this may represent a neuromuscular system in which a significant part of the control algorithm is embedded in its morphology.     

Pitfalls in Portacath location using the landmark technique: case report

A 34 year old woman diagnosed with breast cancer and liver metastases underwent a left subclavian Portacath insertion. During the procedure, the clinical features and the findings of intra-operative investigations provided conflicting evidence of the catheter position. This report highlights the potential difficulties in establishing long-term central venous access, the limitations of common investigations and safety issues relating to the process of subclavian line insertion.     

Degree of neuromuscular facilitation is correlated with contribution to walking in leg muscles of two species of crab

Despite decades of work on the neuromuscular physiology of crustacean leg muscles, little is known about how physiological differences between these muscles relate to their behavioral usage. We studied a sideways walking shore crab, Carcinus maenas, and a forward walking spider crab, Libinia emarginata, as part of our work to understand the neural control of locomotion. The two species differed significantly in facilitation at neuromuscular junctions for every muscle studied. Further, these differences are correlated exactly with the walking use of the muscles. The forward walking spider crab showed more facilitation in muscles which operate joints having larger ranges of motion in forward walking. Likewise, greater facilitation was seen in muscles more active during sideways walking in the predominantly sideways walking shore crab. These differences even occur between muscles innervated by the same motor neuron, and become more evident with higher stimulus frequency. The increased presynaptic facilitation might allow selective recruitment of fibers innervated by the same motor neuron and aid in temporal filtering. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.