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Fifty-nine performance objectives concerning the art of writing letters are presented in this Spanish instructional guide. Prescribed activities include oral presentation of historical topics, reading of selected letters and discussion and reading of short biographical data, punctuation exercises, review of grammar, and use of synonyms. (RL)

Previous work demonstrated that micropuncture aspirates from rat epiphysical plate cartilage contain a nucleating agent for Ca 3 (PO 4 ) 2 mineral growth, and that the nucleation is inhibited by proteoglycan aggregates. In this report data are described which show that mammalian lysozyme inactivates the inhibition. When micropuncture aspirates are incubated in vitro with mammalian lysozyme, a rapid, spontaneous initiation of mineral growth occurs. Incubation of proteoglycan aggregate preparations in the presence of cartilagea lysozyme, but not hen egg white lysozyme, causes a marked decrease of the sedimentation coefficients of the proteoglycans, usually to values close to those obtained with proteoglycan monomer preparations. The inhibition of this effect of mammalian lysozyme by a specific inhibitor of the enzyme tri( N -acetyl-D-glucosamine) suggests that it may be enzymatic in nature.

Cotton strings impregnated with beeswax and beeswax plus a carcinogen were fastened in the vagina of 137 rabbits. Ninety-three of these survived for 6 months and are here reported upon. Experimental groups were set up to test the effect of estrogens and of progesterone on the incidence and time of appearance of methyl-cholanthrene induced tumors. The differences in tumor incidence were not statistically significant. Hyperplasia of the mucosa also developed in about 90 per cent of the vaginas, in contact with the carcinogen impregnanted string, irrespective of treatment with hormones. An influence of hormones on tumor development or on hyperplasia of the vaginal mucosa could not be noted in these animals.

New ultramicro modifications of a hypertonic salt extraction and purification schemes for proteoglycans were applied to the study of proteoglycans in discolored marginal lesions cartilage of patients with osteoarthritis, and the results were compared to a control group of normal appearing cartilage samples from the same patients or from patients with relatively noninflammatory diseases involving the lower extremities. Histologic studies of portions of the same sample used for chemical analysis revealed only minor morphologic changes without leukocytic infiltration. Considerable aberrations from control bovine nasal cartilages were exhibited by normal human articular cartilage samples in respect to the proteoglycan fractionation. Additional abberations of behavior in respect to proteoglycan fractionation were observed in samples of osteoarthritic cartilage and samples from patients with vascular necrosis. Accelerated degradation of proteoglycans with probable alteration of synthetic pathways was postulated to explain these findings.

1. A series of preliminary experiments are conducted to determine the most convenient quantity of food mantids must receive in order to ensure a long life span and a high level of striking. 2. In other series of experiments the dynamic components of the strike are analysed. Preparatory movements tend to place the animal in an optimum position for striking and probably integrate a mechanism for estimating distances. Movements during the strike itself include the sudden displacement of the predatory legs and the lunge, i.e. a sudden thrust which takes place simultaneously with the movement of the predatory legs. An especial study of this latter component is presented. Computation previous to strike has to take this lunge into account in order to hit successfully. 3. The maximum motivation distance to strike lies between 70–80% of the foreleg length. Optimum hitting is achieved at a distance that represents 30–40% of foreleg extension. The gap between these two distances, i.e. 70–80% and 30–40%, is filled by the lunge. When the lunge is prevented by immobilizing the animal, a dramatic increase in the number of misses occurs. 4. There is a relationship between the maximum motivation distance to strike and optimum distance to hit, on the one hand, and the salient anatomical features of the grasping mechanism and the length of the forelegs, on the other hand.

A special experimental device was employed to study which zones of the eye, the praying mantis uses to “look at” the prey before striking.

An extracellular fluid phase (C(f1)), aspirated by micropuncture techniques from the hypertrophic cell zone of calcifying epiphyseal certilage, has been characterized in a calcifying system in vitro in respect to the behavior of sedimenting and supernatant fractions after high speed ultracentrifugation. To perform these tests on the starting samples of 20 nl of C(f1), macroscopic analytical methods were scaled down for the identification of relevant organic components, including hexuronic acid and proteinpolysaccharides (PPL). The mineral accretion system was designed to simulate physiologic conditions in the calcifying cartilage septa of normal rats, and the mineral used for seeding was an immature calcium phosphate similar to native cartilage mineral. Normal C(f1) or its dilutions in synthetic lymph up to 1:4 completely prevented mineral accretion in vitro. The inhibitory action was localized to the sedimented fractions after ultracentrifugation and could be destroyed by incubation with trypsin or hyaluronidase. The sediment of C(f1) contained 2 mg of hexuronic acid per ml of C(f1) and gave a strong reaction of identification for a light fraction of PPL by fluorescent antibodies to rat PPL. PPL fractions were tested in the same mineral accretion systems as C(f1) and exhibited responses similar to those of C(f1). Also, there was evidence of a mineral phase in C(f1) of normal rats, in C(f1) of rats with healing rickets, but not in C(f1) of untreated rachitic rats. These results are interpreted to indicate that certain PPLs function as an inhibitor of crystal growth at extracellular sites premonitory to calcification. Evidence for a low density inhibitor of mineral accretion was found in normal serum but not in C(f1).

A technique has been developed which is based on transport method equations and allows determination of sedimentation coefficients using less than 5 ng of a biological active principle. Glass capillaries of 0.30 mm inside diameter and 3.0 mm length are used as sedimentation cells. About 200 nl of pure or impure solutions with concentration as low as 0.05 mg/ml are ultracentrifuged in a swinging-bucket rotor with a conventional preparative ultracentrifuge. The capillary microcells are easily sectioned after centrifugation through a plane previously marked on the glass surface. The technique was successfully extended to the use of larger glass capillaries, up to 1.25 mm inside diameter, and plastic centrifuge tubes of 5.0 mm diameter and 0.40 ml capacity. The method has been experimentally verified with proteins and protein-polysaccharides of known sedimentation constants.

A new microassay method with precision of ±5% was developed to quantitate pyrophosphate in synovial fluid and plasma with starting volumes of 0.5 ml. A highly significant elevation of synovial fluid pyrophosphate concentration was found in some patients with osteoarthritis and gouty arthritis in addition to the well-established elevation in synovial fluid of subjects with pseudogout. No gradient of pyrophosphate between plasma and synovial fluid of patients with rheumatoid arthritis or in normal subjects was detectable. Studies of various parameters reflecting inflammation failed to show a correlation with the concentration of pyrophosphate in patients with pseudogout.

The effect of proteoglycans on growth of seeding minerals in synthetic lymph was studied with special reference to regulation of endochondral calcification. Proteoglycans were isolated from bovine nasal cartilage by three published methods. By each method two fractions were separated which differed in respect to presence or absence of fast-sedimenting components on analytical ultracentrifugation. Each fraction was tested for its capacity to inhibit mineral growth in a buffered synthetic lymphin vitro. At concentrations of proteoglycans estimated to occur in the interstitial fluid of endochondral plates from 6- to 7-week-old rats, the fractions containing fast-sedimenting components were inhibitory to mineral growth; whereas fractions containing the slow-sedimenting components and a glycoprotein (link protein) had no inhibitory activity demonstrable in these systems. Comparison of calcium-binding capacity of certain proteoglycan fractions as well as their computed effect upon reduction of calcium activity under conditions of equilibrium dialysis revealed no differences in the behavior of a proteoglycan fraction rich in fast—as opposed to fractions composed entirely of slow-sedimenting components. An increased degree of shielding of mineral embryos provided by adjacent protein cores of aggregated proteoglycans is hypothesized to explain the inhibitory action of fast-sedimenting proteoglycans on mineral growthin vitro.

The study of habituation is of great general interest, for it seems to represent the most elementary form of behavioural plasticity (Grossman 19 67). An adequate theory of this phenomenon may therefore provide a basis for increased understanding of other more complex forms of learning (Grossman 1967; Groves and Thomson 1970; Harris 1943; Thomson and Spencer 1966).

La traducción española del Homère de P. Carlier (1999) aparece en un momento muy oportuno, poco después de la recepción en este país de la polémica sobre Troya y cuando ella todavía mantiene su vigor en las más importantes revistas científicas.1 Mientras el debate sobre la realidad arqueológica de la colina de Hissarlik viene generando una intensa discusión en los últimos años, la cuestión homérica ha recuperado algunos de sus temas abiertos coincidiendo con la sucesiva aparición de obras destacadas, como las de Ballabriga o el propio Carlier.