Pharmacokinetics of radiopharmaceuticals.

The pharmacokinetics of various radiopharmaceuticals following i.v. administration in mice and rats has been studied and compared. Before injection the radiochemical purity (RP) of the compounds were determined by HPLC and PAGE. In all cases RP-s were higher than 90%. The biodistribution of 99mTc labelled anti CEA IgG was studied in mice bearing human colon carcinoma xenografts. Animals with different tumour weights showed different blood kinetic and tumor uptake. The pilot clinical study of the 99mTc labelled anti melanoma Fab and 111-In-DTPA labelled anti melanoma F(ab')2 showed differences in the pharmacokinetic parameters. (99mTc labelled: comp.A. 84.6%; T1/2:0.6 h, 111-In-labelled: comp.A.: 46%, T1/2 1.5 h.) The various isonitrile derivatives synthetized in our laboratory were labelled with 99mTc and the biodistribution were tested in rats. The kinetic study showed that all the three molecules have different half lives in the heart and liver (T1/2 for heart ranged 5.1-18.6 h, for liver T1/2:1.2-2.5 h). Reversed phase HPLC study of the collected bile showed the 15-100% of injected compounds are metabolized during hepatic excretion. Literature data and our recent observations confirm that the knowledge of pharmacokinetics of radiolabelled compounds both in research, development and clinical practice is of basic importance.     

Simulation of marked root hair curling in Rhizobium-legume symbiosis

The soil bacterium Rhizobium infects its leguminous host plants in temperate regions of the world mostly by way of the growing root hairs. Root hair curling is a prerequisite for root hair infection, although sidelong root hair infections occasionally have been observed. The processes underlying Rhizobium -induced root hair curling are unknown.
Computer simulation of root hair growth indicates that one-sided tip growth inhibition by Rhizobium can result in root hair curling when three conditions are simultaneously fulfilled: 1) rhizobial growth inhibition is strong enough to prevent removal out of the tip growth range: 2) root hair surface growth between the attached Rhizobium and the root hair top is inhibited; 3) rhizobial growth inhibition is limited to one side of the root hair.
The results predict that root hair curling by stimulation of tip growth is improbable. This study accentuates the need for information about the growth processes contributing to tip growth in leguminous root hairs.     

Dissimilation curves as a simple method for the characterization of growth of plant cell suspension cultures

A simple non-invasive method for the characterization of growth of a plant cell suspension in a single culture flask is given. The dissimilation of sugars by a cell-culture causes a loss of weight of the contents of the culture flask, and can therefore be used to follow the growth in that single culture flask. Because a correction for water evaporation is necessary, accurate results can only be obtained when a stable closure is used (e.g. Silicosen T-type plugs). The dissimilation curves obtained in this way were correlated to the concentration of sugars in the medium, the dry weight and the fresh weight. From these correlations the amount of intracellularly stored carbohydrates could be estimated. Rate constants for CO₂-diffusion were determined for different types of closure. These values allowed the estimation of CO₂ levels inside the culture flasks from the dissimilation curves (CO₂ release curves). The dissimilation curves obtained using this method can easily be related to other types of growth curves. Different growth-phases can be clearly distinguished, e.g. lag-phase, exponential growth-phase and stationary-phase.     

Aquatic bird densities in two coastal lagoon systems in Chiapas State,Mexico, a preliminary assessment

Six bodies of water in two coastal lagoon systems were investigated in Chiapas State, Mexico between July, 1990 and February, 1991. The size of water bodies ranged from 102.5 to 847.5 ha. Salinity varied seasonally being the lowest in July during the rainy season (1.0) and highest in February (35.8). The waters are hypertrophic with total phosphorus concentrations as high 900 mg m^–3.The number of bird species was the highest in February (N = 9 to 23) and the lowest in July (N = 2 to 15). The majority of birds present are resident species of Mexico but several species of northern birds were present in February (e.g. Lesser Scoup, Osprey, Peregrin Falcon).The number of birds observed in the waterbodies varied during the study period being as high as 2800 Cormorants, 2300 White Pelicans and 681 Limpkins, at a particular time, or expressed in terms of units surface area of each lagoon 8.0, 2.7 and 1.9 individuals per hectare respectively. The daily food requirements of White Pelicans at such a high density is about 4.1 kg ha^–1 d^–1.The hypertrophic state of Cerritos Lagoon allows a sufficient level of production to support such a high food requirement. Considering the limited survey time spent on the lagoons the bird population numbers are probably underestimated.     

Sackville Waterfowl Park,Sackville, New Brunswick,Canada. Baseline characterization,towards long-term monitoring

The Sackville Waterfowl Park, contains a 19 hectare shallow freshwater wetland created by reflooding a saltwater marsh that was drained three centuries ago. Its primary purpose is to provide wetland habitat and wildlife viewing opportunities to tourists and residents. This newly created, eutrophic wetland supports high densities of waterfowl, 2.1 and 3.3 brood ha^–1 in 1991 and 1992 respectively. It is hoped that long term monitoring of the Park's waterfowl population and wetland habitat will contribute to a better understanding of factors controlling breeding waterfowl populations.     

Identification of a major T-cell epitope within VP3 amino acid residues 24 to 37 of Theiler's virus in demyelination-susceptible SJL/J mice.

Intracerebral inoculation of susceptible strains of mice with Theiler's murine encephalomyelitis virus (TMEV) results in a chronic, immunologically mediated demyelinating disease that shares many features with human multiple sclerosis. CD4+ T lymphocytes play a critical role in the pathogenesis of virus-induced demyelinating disease. We have identified a region within amino acid residues 24 to 37 of the VP3 capsid protein of TMEV (VP3(24-37)) that is recognized by T lymphocytes from the demyelination-susceptible SJL/J strain of mice. The T-cell response to VP3(24-37) represents a predominant Th-cell response against the virus from either TMEV-immunized or TMEV-infected SJL/J mice, and viral epitopes VP1(233-250), VP2(74-86), and VP3(24-37) account for most of the Th-cell response to TMEV.     

Temperament and Character in the Child and Adolescent Twin Study in Sweden (CATSS): Comparison to the General Population,and Genetic Structure Analysis

Background

The Child and Adolescent Twin Study in Sweden (CATSS) is an on-going, large population-based longitudinal twin study. We aimed (1) to investigate the reliability of two different versions (125-items and 238-items) of Cloninger''s Temperament and Character Inventory (TCI) used in the CATSS and the validity of extracting the short version from the long version, (2) to compare these personality dimensions between twins and adolescents from the general population, and (3) to investigate the genetic structure of Cloninger''s model.

Method

Reliability and correlation analyses were conducted for both TCI versions, 2,714 CATSS-twins were compared to 631 adolescents from the general population, and the genetic structure was investigated through univariate genetic analyses, using a model-fitting approach with structural equation-modeling techniques based on same-sex twin pairs from the CATSS (423 monozygotic and 408 dizygotic pairs).

Results

The TCI scores from the short and long versions showed comparable reliability coefficients and were strongly correlated. Twins scored about half a standard deviation higher in the character scales. Three of the four temperament dimensions (Novelty Seeking, Harm Avoidance, and Persistence) had strong genetic and non-shared environmental effects, while Reward Dependence and the three character dimensions had moderate genetic effects, and both shared and non-shared environmental effects.

Conclusions

Twins showed higher scores in character dimensions compared to adolescents from the general population. At least among adolescents there is a shared environmental influence for all of the character dimensions, but only for one of the temperament dimensions (i.e., Reward Dependence). This specific finding regarding the existence of shared environmental factors behind the character dimensions in adolescence, together with earlier findings showing a small shared environmental effects on character among young adults and no shared environmental effects on character among adults, suggest that there is a shift in type of environmental influence from adolescence to adulthood regarding character.