Outcome of Investigation of Patients with Presenile Dementia

Of 106 patients admitted for investigation to a neurological hospital with a presumptive diagnosis of dementia, 84 were confirmed to have intellectual impairment or loss of learning and memory function or both. A possible aetiology for the dementia was found in 36 of these 84 patients; the commonest causes discovered were intracranial mass lesions, arterial disease, and alcoholism. Fifteen of the 106 patients were found not to be demented but to have some other illness, most commonly depression. Of the whole series some 15% of the patients suffered from conditions that were amenable to treatment.     

Histamine receptors in the human heart

Histamine receptor subtypes in $\text{in vitro}$ isolated human coronary arteries and in $\text{in vitro}$ human atrial and ventricular myocardium were studied. The H₁ receptor mediates contraction of coronary vascular smooth muscle but has no effect on atrial or ventricular tissue. The H₂ receptor mediates relaxation of human coronary artery vascular smooth muscle and mediates a positive inotropic response in atrial and ventricular myocardium.     

Recurrence after surgical treatment of hidradenitis suppurativa.

From six to 89 months after surgery 82 patients who had been treated by radical surgery (118 excisions) for intractable hidradenitis suppurativa were reviewed. Local recurrence rates varied greatly with the disease site, being low after axillary (3%) and perianal surgery (0%) and high after inguinoperineal (37%) and submammary (50%) excision. Recurrence results from inadequate excision or an unusually wide distribution of apocrine glands, but physical factors such as obesity, local pressure, and skin maceration played a part in a few patients. Recurrence due to inadequate surgery tended to be the most troublesome. At follow up 75 (91%) of the patients were pleased with the results of their operation. A quarter of the patients developed disease at a new anatomical site after operation. Radical surgery gives good symptomatic control of severe hidradenitis suppurativa of the axilla, inguinoperineal, and perianal regions but is less satisfactory for submammary disease.     

Human fibroblast stromelysin catalytic domain: expression, purification, and characterization of a C-terminally truncated form.

Stromelysin-1 is a member of a tissue metalloproteinase family whose members are all capable of degrading extracellular matrix components. A truncated form of human fibroblast prostromelysin 1 lacking the C-terminal, hemopexin-like domain has been expressed in Escherichia coli and purified to homogeneity. Treatment of this short form of prostromelysin with (aminophenyl)mercuric acetate resulted in activation and loss of the propeptide in a manner identical with the wild-type, full-length protein. Kinetic comparisons using Nle11-substance P as a substrate showed that the wild-type stromelysin and the truncated form of the enzyme had similar kcat and Km values. Likewise, both enzymes displayed similar Ki values for a hydroxamate-containing peptide inhibitor. Taken together, these results indicate that the C-terminal portion of stromelysin is not required for proper folding of the catalytic domain, maintenance of the enzyme in a latent form, activation with an organomercurial, cleavage of a peptide substrate, or interaction with an inhibitor. Moreover, the active short form of stromelysin displayed a reduction in the C-terminal heterogeneity, a characteristic degradation of the full-length stromelysin, and thereby provides a more suitable protein for future structural studies.     

Interrelationship of carbohydrate and the alpha-toxin binding site on the acetylcholine receptor from Torpedo marmorata

The relationship of the carbohydrate components of purified acetylcholine receptor (AChR) to its acetylcholine binding site was investigated by two approaches. In the first, the effect of periodate or glycosidase treatment of AChR on its ability to bind α-bungarotoxin was assessed. Although loss of binding capacity was observed, this could be attributed to increased temperature, acid pH or high salt concentrations of the incubation conditions rather than to the specific action of periodate or glycosidases, indicating that the α-toxin binding site does not directly involve carbohydrate.The second approach involved the use of concanavalin A to block the binding of α-toxin to AChR, when a maximum inhibition of approximately 40% was obtained. The results are interpreted in terms of heterogeneity of AChR molecules, of which some 40% have sterically interacting sites binding concanavalin A and α-toxin respectively.     

Influence of visual targets and landmarks on honey bee foraging and waggle dancing

Animals use diverse sensory stimuli to navigate their environment and to recognize rewarding food sources.Honey bees use visual atributes of the targeted food source,such as its color,shape,size,direction and distance from the hive,and the landmarks around it to navigate during foraging.They transmit the location information of the food source to other bees if it is highly rewarding.To investigate the relative importance of these attributes,we trained bees to feeders in two different experiments.In the first experiment,we asked whether bees prefer to land on(a)a similar feeder at a different distance on the same heading or on(b)a visually distinct feeder located at the exact same location.We found that,within a short foraging range,bees relied heavily on the color and the shape of the food source and to a lesser extent on its distance from the hive.In the second experiment,we asked if moving the main landmark or the feeder(visual target)influenced recruitment dancing for the feeder.We found that foragers took longer to land and danced fewer circuits when the location of the food source,or a major landmark associated with it,changed.These results demonstrate that prominent visual atributes of food sources and landmarks are evidently more reliable than distance information and that foraging bees heavily utilize these visual cues at the later stages of their journey.     

Multiple stable equilibria in a predator-prey system

Necessary and sufficient conditions are given for three equilibria to occur in a predatorprey model and conditions are given for two of these to be stable. The existence of two stable equilibria requires predator intraspecific competition for either space or food, and the lower the prey growth rate the stronger this predator self-regulation must be. A prey growth rate that is skewed to the right, the ability of a few predators to survive at low prey densities, and predators with high searching effectiveness, long handling times, and large maximum per capita rate of increase all make two stable equilibria more likely.