BMP1-related metalloproteinases promote the development of ventral mesoderm in early Xenopus embryos

Bone morphogenetic protein 1 (BMP1) is a metalloproteinase closely related to Drosophila Tolloid (Tld). Tld regulates dorsoventral patterning in early Drosophila embryos by enhancing the activity of Dpp, a member of the TGF-beta family most closely related to BMP2 and BMP4. In Xenopus BMP4 appears to play an essential role in dorsoventral patterning, promoting the development of ventral fates during gastrula stages. To determine if BMP1 has a role in regulating the activity of BMP4, we have isolated cDNAs for Xenopus BMP1 and a novel closely related gene that we have called xolloid (xld). Whereas xbmp1 is uniformly expressed at all stages tested, the initial uniform expression of xld becomes localized to two posterior ectodermal patches flanking the neural plate and later to the inner ectoderm of the developing tailbud. xld is also expressed in dorsal regions of the brain during tailbud stages and is especially abundant in the ventricular layer of the dorsal hindbrain caudal to the otic vesicle. Overexpression of either gene inhibits the development of dorsoanterior structures in whole embryos and ventralizes activin-induced dorsal mesoderm in animal caps. Since ventralization of activin-induced animal caps can be blocked by coinjecting a dominant-inhibitory receptor for BMP2 and BMP4, we suggest a role for BMP1 and Xld in regulating the ventralizing activity of these molecules.     

Kinetics and specificity of peptide uptake by the oligopeptide transport system of Lactococcus lactis

To obtain amino acids for growth, Lactococcus lactis uses a proteolytic system to degrade exogenous proteins such as caseins. The extracellular cell wall-attached proteinase PrtP and the oligopeptide transport system Opp mediate the first two steps in the utilization of caseins. beta-Casein is degraded by PrtP to fragments of 5-30 amino acid residues, and only a limited number of peptides are selected from this pool for uptake via Opp. To study the specificity of Opp and the kinetics of peptide uptake in L. lactis in detail, we used the following strategy: (i) the Opp system was overexpressed; (ii) a 4-fold peptidase mutant was used that is unable to degrade KYGK; (iii) iodinated KYGK was used as the reporter peptide; (iv) libraries of peptides, in which one amino acid position is systematically varied, were used as competitive peptides; and (v) peptides were synthesized on the basis of the beta-casein degradation products, their inhibition of KYGK uptake was determined, and the uptake of these peptides was followed by high-performance liquid chromatography (HPLC). These studies indicate that (i) the Opp system can transport a broad range of peptides from 4 up to at least 18 residues with very little preference for particular side chains and (ii) the kinetics of peptide uptake differ for different substrates tested. Whereas class I peptides such as KYGK exhibit normal Michaelis-Menten kinetics, the level of uptake of the majority of peptides (class II) increases sigmoidally with concentration. Different models for explaining the apparent cooperative effects that are observed for peptide uptake are discussed.     

Bacteremia and intraoral suture removal: can an antimicrobial rinse help?

Recent studies have shown that bacteremia can result from the removal of intraoral sutures. The authors found that preprocedural use of an antimicrobial oral rinse (0.12 percent chlorhexidine) did not significantly reduce the incidence of bacteremia when compared with no rinse at all. Similarly, a significant relationship between bleeding and bacteremia was not apparent. Most of the positive cultures yielded low colony counts. The results support the rationale for the American Heart Association's 1997 recommendations for use of antibiotic prophylaxis to prevent bacteremia, as well as the importance of good oral hygiene in prevention efforts.     

Novel cytokine release inhibitors. Part I: Triterpenes

Tripterine and closely related triterpenoid derivatives as IL-1 beta release inhibitors are discussed.     

Analysis of iodine incorporation in mbe grown CdTe and HgCdTe

A study is reported of the dynamics of dopant incorporation in iodine doped CdTe. Using a mathematical formulation, the iodine doping profiles in CdTe and HgCdTe have been fitted to experiment to obtain material parameters such as the bulk and surface diffusion and the segregation energy. Dopant profile fitting showed that iodine diffusion was insignificant and gave an iodine segregation energy of 0.6 eV and a surface diffusivity enhancement factor of 300 at a growth temperature of 230°C. The model was used to determine the effect of the growth rate and temperature for particular growth conditions.     

Aza and diaza bioisosteric anthracene-9,10-diones as antitumor agents

We compared 115 female and 115 male Brazilian alcoholics in terms of their social and demographic characteristics, as well as other characteristics associated with alcohol consumption. Women both began drinking and increased their consumption later than men. The incidence of attempted suicide was higher among women. Females used less illicit drugs. Male alcoholics were more frequently born in the city of S?o Paulo. As for adherence to treatment in an out-patient clinic, no significant differences were found between the sexes 3, 6, 9 and 12 months after initiation of treatment.     

Microcirculation of the islets of Langerhans. Long Beach Veterans Administration Regional Medical Education Center Symposium

The passing of the Prevention of Occupational Hazards Act, (Ley 31/1995), constituted a change in direction in the development of occupational safety and health in Spain. This article describes the most salient points of this new legislation, from the criteria and principles that have to govern preventive activities, to the obligations and rights of both employers and workers, together with the co-operation and co-ordination of the activities of the various Administrations which have jurisdiction and the participation of employers' and workers' organisations, as the backbone of policy in matters concerning the prevention of occupational hazards.