Projections of the cortical visual areas of the posterior gyrus sigmoid and the caudate nucleus in the cat

The complex performances of the visuo-motor system entail probably an intervention of circuits connecting, the primary visual areas, to other cortical regions, specially the sensory motor cortex, and certain sub-cortical formations. For testing this hypothesis, the unilateral resection of the areas 17, 18 and 19 has been undertaken on 19 cats, with delays ranging from 8 days to 3 months after intervention. The tracing of the pathways was carried out by combining different degenerating methods in particular the Marchi reaction. Based on this, it is possible to define a compact bundle of the axons originating from the primary visual cortex and dividing into two fascicles of unequal magnitude. The slender ends in the lower part of the posterior gyrus sigmo?d; the larger one penetrates into the caudale nucleus. An ultrastructural study specifies the modalities of distribution of the axons within this nucleus.     

Distribution of lithium in different CNS areas and other tissues of adult male and female vizcacha (Lagostomus maximus maximus).

In a previous study (1) we demonstrated that lithium administration (1.0 mmol/kg b.wt., per day for 4 weeks) in intact vizcacha (Lagostomus maximus maximus) leads to significant histological alterations in the kidneys, ovarie and testicles, while these three tissues were not damaged in rats. Male vizcachas died within 4 days when administered LiCl 3 mmol/kg b.wt., while females were not affected. The lithium renal clearance presented no changes in either males or females. The 1.0 mmol/kg b.wt. dose was used in the experiments (2). In this study we examined the distribution of lithium in various tissues of male and female vizcacha (Lagostomus maximus maximus) administered LiCl by injection (1 mmol/kg b.wt.) for one day (Group I) and thirty days (Group II). Blood sample was obtained after 24 hours (Group I) and 30 days (Group II). The tissues investigated were: pituitary, hypothalamus, cerebral cortex, cerebellum, corpus callous, small and large intestine, kidney and suprarenal. The concentration of lithium in tissues and serum was determined by atomic absortion spectrometry (3,4). In Group I a significant lithium concentration increment (mumol/g of tissue) was observed in all the tissues of male vizcachas as compared to female vizcacha. A similar distribution was obtained in animals treated for 30 days. In the pituitary, however this difference between males and females was not significant. The male lithium serum levels were significantly higher than those of female animals. In conclusion, we suggest that the particular structure of the cell membrane (e.g., number and characteristic of sodium channels) of each tissue and/or the intracellular mechanisms of transport, elimination and metabolism might explain the unequal lithium distribution and the difference recovery from the damage produced. The results suggest that the vizcacha could be a useful model for the study of lithium toxicity.     

Tristerix tetrandrus (Loranthaceae) and its host-plants in the Chilean matorral: patterns and mechanisms

Summary Interactions between a Chilean mistletoe, quintral (Tristerix tetrandrus, Loranthaceae) and its potential host plants were studied at a site with mediterranean type climate. The results show that the distribution of T. tetrandrus is related to the behavior of avian dispersers, which feed on its fruit, and evacuate the seeds at random in the field, but the distribution is also influenced bymicroenvironmental conditions, survival of seedlings is hampered at drier locations. The infection capacity of the seeds is increased after birds have eliminated the fruit coat.Survival of T. tetrandrus seeds differed depending on the species to which they were attached experimentally. Seeds germinated, and plants developed on Colliguaya odorifera and Kageneckia oblonga, previously reported as susceptible to infection. Survival was significantly higher on C. odorifera, although in the field it is infected less frequently than K. oblonga. In species on which no T. tetrandrus has been previously reported, resistance to infection might be ascribed to different mechanisms: in Quillaja saponaria, differentiation of cork layers apparently prevents penetration by haustoria; in Lithraea caustica haustoria enter the cortex and phloem, but no further development ensues. K. oblonga seldom bears more than one T. tetrandrus plant. Experimental inoculations showed that significantly more seeds developed into plants on K. oblonga individuals not previously infected with quintral, suggesting that they become resistant to infection.     

Medical and socio-demographic implications of abortion at Felix Bulnes Hospital in Santiago (author's transl)]

602 patients were admitted for treatment of incomplete abortion (including inevitable or threatened abortion) from May 1 to October 31, 1974, at Felix Bulnes Hospital in Santiago Chile. Routine treatment included dilation and curettage in 88.7% of the cases, with a mean hospitalization time of 2.5 nights. Complications in 14.6% included fever, pelvic infection, and blood loss requiring transfusion. 78.4% had used no form of contraception in the month previous to conception, but 68.9% of those who returned for a follow-up (only 37.7%) were using effective contraceptives. The study indicates: 1) the cost of abortion is high in terms of risk of complications and hospital time; 2) infection associated with abortions outside the hospital is high; and 3) acceptance of contraception after abortion is not high enough to deter repetition of abortion.     

Gap-phase dynamics and coexistence of a long-lived pioneer and shade-tolerant tree species in the canopy of an old-growth coastal temperate rain forest of Chiloé Island, Chile

Aim A major question with regard to the ecology of temperate rain forests in south‐central Chile is how pioneer and shade‐tolerant tree species coexist in old‐growth forests. We explored the correspondence between tree regeneration dynamics and life‐history traits to explain the coexistence of these two functional types in stands apparently representing a non‐equilibrium mixture. Location This study was conducted in northern Chiloé Island, Chile (41.6° S, 73.9° W) in a temperate coastal rain forest with no evidence of stand disruption by human impact. Methods We assessed stand structure by sampling all stems within two 50 × 20 m and four 5 × 100 m plots. A 600‐m long transect, with 20 uniformly spaced sampling points, was used to quantify seedling and sapling densities, obtain increment cores, and randomly select 10 tree‐fall gaps. We used tree‐ring analysis to assess establishment periods and to relate the influences of disturbances to the regeneration dynamics of the main canopy species. Results Canopy emergent tree species were the long‐lived pioneer Eucryphia cordifolia and the shade‐tolerant Aextoxicon punctatum. Shade‐tolerant species such as Laureliopsis philippiana and several species of Myrtaceae occupied the main canopy. The stem diameter distribution for E. cordifolia was distinctly unimodal, while for A. punctatum it was multi‐modal, with all age classes represented. Myrtaceae accounted for most of the small trees. Most tree seedlings and saplings occurred beneath canopy gaps. Based on tree‐ring counts, the largest individuals of A. punctatum and E. cordifolia had minimum ages estimated to be > 350 years and > 286 years, respectively. Shade‐tolerant Myrtaceae species and L. philippiana had shorter life spans (< 200 years). Most growth releases, regardless of tree species, were moderate and have occurred continuously since 1750. Main conclusions We suggest that this coastal forest has remained largely free of stand‐disrupting disturbances for at least 450 years, without substantial changes in canopy composition. Release patterns are consistent with this hypothesis and suggest that the disturbance regime is dominated by individual tree‐fall gaps, with sporadic multiple tree falls. Long life spans, maximum height and differences in shade tolerance provide a basis for understanding the long‐term coexistence of pioneer and shade‐tolerant tree species in this coastal, old‐growth rain forest, despite the rarity of major disturbances.