The gluten-free basic food basket: a problem of availability, cost and nutritional composition

The basic food basket (BFB), formed by the more economical products available, is used by less-affluent countries to establish the minimum daily food consumption to satisfy nutritional requirements in less-privileged individuals. There is no information about groups that depend on the BFB and in addition follow gluten-free diet (GF/BFB). We measured availability, cost, main ingredients and nutritional composition of GF/BFB. Data were collected in the area that was first in the social priority list in the capital city, matching BFB components with gluten-free equivalents (GF/BFB). GF/BFB characterized by being 42% less available, three times more costly (>500% higher for bread), with up to 69% lower protein content and with no fortifications, leaving at nutritional risk celiac individuals that depend on GF/BFB. Results raise concerns on the capacity of the GF/BFB to encourage adherence, maintain adequate nutritional status and quality of life in celiac patients.

Regulation of glucose kinetics during exercise by the glucagon-like peptide-1 receptor

In response to oral glucose, glucagon-like peptide-1 receptor (Glp1r) knockout (Glp1r−/−) mice become hyperglycaemic due to impaired insulin secretion. Exercise also induces hyperglycaemia in Glp1r−/− mice. In contrast to oral glucose, exercise decreases insulin secretion. This implies that exercise-induced hyperglycaemia in Glp1r−/− mice results from the loss of a non-insulinotropic effect mediated by the Glp1r. Muscle glucose uptake (MGU) is normal in exercising Glp1r−/− mice. Thus, we hypothesize that exercise-induced hyperglycaemia in Glp1r−/− mice is due to excessive hepatic glucose production (HGP). Wild-type (Glp1r+/+) and Glp1r−/− mice implanted with venous and arterial catheters underwent treadmill exercise or remained sedentary for 30 min. [3-3H]glucose was used to estimate rates of glucose appearance (Ra), an index of HGP, and disappearance (Rd). 2[14C]deoxyglucose was used to assess MGU. Glp1r−/− mice displayed exercise-induced hyperglycaemia due to an excessive increase in Ra but normal Rd and MGU. Exercise-induced glucagon levels were ∼2-fold higher in Glp1r−/− mice, resulting in a ∼2-fold higher glucagon:insulin ratio. Since inhibition of the central Glp1r stimulates HGP, we tested whether intracerebroventricular (ICV) infusion of the Glp1r antagonist exendin(9–39) (Ex9) in Glp1r+/+ mice would result in exercise-induced hyperglycaemia. ICV Ex9 did not enhance glucose levels or HGP during exercise, suggesting that glucoregulatory effects of Glp1 during exercise are mediated via the pancreatic Glp1r. In conclusion, functional disruption of the Glp1r results in exercise-induced hyperglycaemia associated with an excessive increase in glucagon secretion and HGP. These results suggest an essential role for basal Glp1r signalling in the suppression of alpha cell secretion during exercise.

A high-yielding serum-free, suspension cell culture process to manufacture recombinant adenoviral vectors for gene therapy

We have developed an efficient, reproducible, and scaleable cell culture process for a recombinant adenoviral vector expressing therapeutic transgenes for clinical trials. HEK 293 cells - which support the propagation of E1 deficient adenovirus - were first adapted to serum free media and suspension growth. Subsequent studies focused on the infection, virus production and harvest from suspension culture bioreactors. Future studies are planned to address the kinetics of adenovirus production in HEK 293 as well as in other cell lines.

High-performance lithium-ion anodes using a hierarchical bottom-up approach

Si-based Li-ion battery anodes have recently received great attention, as they offer specific capacity an order of magnitude beyond that of conventional graphite. The applications of this transformative technology require synthesis routes capable of producing safe and easy-to-handle anode particles with low volume changes and stable performance during battery operation. Herein, we report a large-scale hierarchical bottom-up assembly route for the formation of Si on the nanoscale--containing rigid and robust spheres with irregular channels for rapid access of Li ions into the particle bulk. Large Si volume changes on Li insertion and extraction are accommodated by the particle's internal porosity. Reversible capacities over five times higher than that of the state-of-the-art anodes (1,950 mA h g(-1)) and stable performance are attained. The synthesis process is simple, low-cost, safe and broadly applicable, providing new avenues for the rational engineering of electrode materials with enhanced conductivity and power.

[Genetic environment of CTX-M-2 in Klebsiella pneumoniae isolates from hospitalized patients in Uruguay]

We studied two CTX-M-2-producing Klebsiella pneumoniae clinical strains, K96005 and K13, isolated from hospitalized patients in Uruguay, during 1996 and 2003, respectively. The genomic surroundings of bla(CTX-M-2) were characterized by PCR-mapping and DNA sequencing. Our results show that blaCTX-M-2 is included in a complex class-1 integron (InK13), associated with an orf513 in both isolates. The genetic array of the integron, aac(6')-lb, bla(OxA,2), orfD (gene cassette region), associated with an orf513-bla(CTX-M-2), seems to be widely disseminated over the Rio de la Plata region.

Individual somatic H1 subtypes are dispensable for mouse development even in mice lacking the H1(0) replacement subtype

H1 linker histones are involved in facilitating the folding of chromatin into a 30-nm fiber. Mice contain eight H1 subtypes that differ in amino acid sequence and expression during development. Previous work showed that mice lacking H1(0), the most divergent subtype, develop normally. Examination of chromatin in H1(0-/-) mice showed that other H1s, especially H1c, H1d, and H1e, compensate for the loss of H1(0) to maintain a normal H1-to-nucleosome stoichiometry, even in tissues that normally contain abundant amounts of H1(0) (A. M. Sirotkin et al., Proc. Natl. Acad. Sci. USA 92:6434-6438, 1995). To further investigate the in vivo role of individual mammalian H1s in development, we generated mice lacking H1c, H1d, or H1e by homologous recombination in mouse embryonic stem cells. Mice lacking any one of these H1 subtypes grew and reproduced normally and did not exhibit any obvious phenotype. To determine whether one of these H1s, in particular, was responsible for the compensation present in H1(0-/-) mice, each of the three H1 knockout mouse lines was bred with H1(0) knockout mice to generate H1c/H1(0), H1d/H1(0), or H1e/H1(0) double-knockout mice. Each of these doubly H1-deficient mice also was fertile and exhibited no anatomic or histological abnormalities. Chromatin from the three double-knockout strains showed no significant change in the ratio of total H1 to nucleosomes. These results suggest that any individual H1 subtype is dispensable for mouse development and that loss of even two subtypes is tolerated if a normal H1-to-nucleosome stoichiometry is maintained. Multiple compound H1 knockouts will probably be needed to disrupt the compensation within this multigene family.

Immunohistochemical localization of types 1 and 2 5alpha-reductase in human scalp

The predominant form of 5alpha-reductase (5aR) in human scalp is 5aR1. None the less, clinical studies have shown that finasteride, a selective inhibitor of 5aR2, decreases scalp dihydrotestosterone and promotes hair growth in men with androgenetic alopecia. Immunolocalization studies were thus carried out to examine 5aR isozyme distribution within scalp and, in particular, to determine whether 5aR2 might be associated with hair follicles. 5aR2 was localized using both a rabbit polyclonal and a mouse monoclonal antibody. 5aR1 was detected with a mouse monoclonal antibody. The specificity of these reagents was demonstrated both by immunofluorescence and Western blot analyses of COS cells overexpressing human 5aR1 or 5aR2. When cryosections of scalp from men with androgenetic alopecia were stained with antibody against 5aR2, using immunoperoxidase avidin-biotin complex methodology, immunostaining was observed in the inner layer of the outer root sheath and, in more proximal regions of the follicle, in the inner root sheath. Staining was also prominent in the infundibular region of the follicle, with less intense staining extending throughout the granular layer of the epidermis. Some staining was also seen in sebaceous ducts. Similar results were obtained with both the polyclonal and monoclonal 5aR2 antibodies. In contrast, in scalp cryosections stained with antibody to 5aR1, no immunostaining was observed within hair follicles. Intense staining for the type 1 isozyme was, however, detected within sebaceous glands. Our immunolocalization data suggest that the results seen in clinical trials of men with male pattern hair loss treated with finasteride may be due, at least in part, to local inhibition of 5aR2 within the hair follicle.

Endoscopic-assisted temporoparietal fascial flap dissection and harvesting: a feasibility preliminary cadaveric study

Endoscopic procedures in plastic surgery have been applied in various aesthetic and reconstructive surgical techniques. The authors describe, in this preliminary report, a new surgical technique of endoscopic dissection of the temporoparietal fascial flap. A series of 6 fresh human cadavers (12 flaps) were dissected endoscopically. The surgical incisions, flap anatomy applicable to endoscopy, endoscopic surgical technique, and type of endoscopic setup is standardized for all flaps, allowing direct identification of the temporoparietal fascial layers and the major vascular pedicle. This endoscopic manipulation of the flap, without the traditional large scalp incision, permits local and free transfer of the temporoparietal fascial flap. Exposure of the flap by means of the conventional T or Y temporal incisions has several possible disadvantages, including an increased risk of blood loss, alopecia, and facial nerve injury. Endoscopic dissection and mobilization of the temporoparietal fascial flap can obviate the direct flap incision and yield a flap accessible to dissection and mobilization for additional clinical applications. This new, innovative, and minimally invasive endoscopic procedure may prove particularly applicable to future clinical applications of this type of fascial flap.

Contribution of the Pmra promoter to expression of genes in the Escherichia coli mra cluster of cell envelope biosynthesis and cell division genes

Recently, a promoter for the essential gene ftsI, which encodes penicillin-binding protein 3 of Escherichia coli, was precisely localized 1.9 kb upstream from this gene, at the beginning of the mra cluster of cell division and cell envelope biosynthesis genes (H. Hara, S. Yasuda, K. Horiuchi, and J. T. Park, J. Bacteriol. 179:5802-5811, 1997). Disruption of this promoter (Pmra) on the chromosome and its replacement by the lac promoter (Pmra::Plac) led to isopropyl-beta-D-thiogalactopyranoside (IPTG)-dependent cells that lysed in the absence of inducer, a defect which was complemented only when the whole region from Pmra to ftsW, the fifth gene downstream from ftsI, was provided in trans on a plasmid. In the present work, the levels of various proteins involved in peptidoglycan synthesis and cell division were precisely determined in cells in which Pmra::Plac promoter expression was repressed or fully induced. It was confirmed that the Pmra promoter is required for expression of the first nine genes of the mra cluster: mraZ (orfC), mraW (orfB), ftsL (mraR), ftsI, murE, murF, mraY, murD, and ftsW. Interestingly, three- to sixfold-decreased levels of MurG and MurC enzymes were observed in uninduced Pmra::Plac cells. This was correlated with an accumulation of the nucleotide precursors UDP-N-acetylglucosamine and UDP-N-acetylmuramic acid, substrates of these enzymes, and with a depletion of the pool of UDP-N-acetylmuramyl pentapeptide, resulting in decreased cell wall peptidoglycan synthesis. Moreover, the expression of ftsZ, the penultimate gene from this cluster, was significantly reduced when Pmra expression was repressed. It was concluded that the transcription of the genes located downstream from ftsW in the mra cluster, from murG to ftsZ, is also mainly (but not exclusively) dependent on the Pmra promoter.

The non-penicillin-binding module of the tripartite penicillin-binding protein 3 of Escherichia coli is required for folding and/or stability of the penicillin-binding module and the membrane-anchoring module confers cell septation activity on the folded structure

The ftsI-encoded multimodular class B penicillin-binding protein 3 (PBP3) is a key element of the cell septation machinery of Escherichia coli. Altered ftsI genes were overexpressed, and the gene products were analyzed with respect to the level of production, stability, penicillin affinity, and cell septation activity. In contrast to the serine beta-lactamases and low-molecular-mass PBPs which are autonomous folding entities, the S-259-to-V-577 penicillin-binding module of M-1-to-V-577 PBP3 lacks the amino acid sequence information for correct folding. The missing piece of information is provided by the associated G-57-to-E-258 non-penicillin-binding module which functions as a noncleaved, pseudointramolecular chaperone. Key elements of the folding information reside within the motif 1-containing R-60-to-W-110 polypeptide segment and within G-188-to-D-197 motif 3 of the n-PB module. The intermodule interaction is discussed in the light of the known three-dimensional structure (at 3.5-A [0.35-nm] resolution) of the analogous class B PBP2x of Streptococcus pneumoniae (S. Pares, N. Mouz, Y. Pétillot, R. Hakenbeck, and O. Dideberg, Nature Struct. Biol. 3:284-289, 1996). Correct folding and adoption of a stable penicillin-binding conformation are necessary but not sufficient to confer cell septation activity to PBP3 in exponentially growing cells. The in vivo activity of PBP3 also depends on the M-1-to-E-56 amino-terminal module which encompasses the cytosol, the membrane, and the periplasm and which functions as a noncleaved pseudo-signal peptide.

Serum insulin in clomiphene responders and nonresponders with polycystic ovarian disease

OBJECTIVE

To investigate insulin levels in women with polycystic ovarian disease (PCOD) who are responders or nonresponders to clomiphene citrate (CC).

DESIGN

Open and prospective study.

SETTING

Outpatient infertility clinic of a third level medical institution.

PATIENTS

Ten healthy women (group 1) and 35 PCOD women classified as responders (group 2 n = 10) or nonresponders (group 3 n = 25) on the basis of serum progesterone > or = 19 nmol/L in response to CC repeatedly administered in doses up to 250 mg/day for five days; they were further subdivided if body mass index (BMI) was below (N) or above (H) mean + 3 SD of group 1.

INTERVENTIONS

Blood samples were obtained in a 100-g, 2-hours oral glucose tolerance test (OGTT).

MAIN OUTCOME MEASURES

Serum glucose, insulin, free testosterone (free-T), dehydroepiandrosterone sulphate (DHEA-S), and androstenedione (A) were determined in the samples OGTT and the areas under the curve (AUC) were calculated.

RESULTS

Group 3 had higher BMI, basal LH, and insulin and AUC insulin than groups 1 and 2; free-T was higher in groups 2 and 3 than in group 1, and basal PRL was higher in group 2 compared to groups 1 and 3. When BMI < or = 25.4 kg/m2 (mean + 1 SD of group 1) 77% of the PCOD cases responded (10 out of 13) whereas none with BMI > 25.4 responded to CC (n = 22) irrespectively of basal insulin concentration or AUC insulin.

CONCLUSION

Moderate to excessive overweight seems more frequently and closely associated to a negative CC response in women with PCOD than hyperinsulinemia.

Cell-mediated catabolism of aggrecan. Evidence that cleavage at the "aggrecanase" site (Glu373-Ala374) is a primary event in proteolysis of the interglobular domain

A rat chondrosarcoma cell line and primary bovine chondrocytes have been used to study cell-mediated aggrecan catabolism. Addition of 1 microM retinoic acid to chondrosarcoma cultures resulted in aggrecan proteolysis with the release of greater than 90% of the cell layer aggrecan into the medium within 4 days. NH2-terminal sequencing of chondroitin sulfate-substituted catabolic products gave a single major NH2-terminal sequence of ARGNVILTXK, initiating at Ala374. This showed that the proteinase, commonly referred to as "aggrecanase," which cleaves the Glu373-Ala374 bond of the interglobular domain of aggrecan (Sandy, J. D., Neame, P. J., Boynton, R. E., and Flannery, C. R. (1990) J. Biol. Chem. 266, 8683-8685), is active in this cell system. Aggrecan G1 domain, generated by cleavage of the interglobular domain, was also liberated during catabolism and this was characterized with three antipeptide antisera. Anti-CDAGWL was used as a general probe for G1 domain. Anti-FVDIPEN was used to specifically detect G1 domain with COOH terminus of Asn341, the form which is readily generated by cleavage of aggrecan by a wide range of matrix metalloproteinases. Anti-NITEGE antiserum was used to specifically detect G1 domain with COOH terminus of Gln373, the form which is the expected product of "aggrecanase"-mediated cleavage of aggrecan. Western blot analysis indicated that a single form of G1 domain of about 60 kDa was formed. G1 domain of this size reacted with both anti-CDAGWL and anti-NITEGE but not with anti-FVDIPEN. Similar experiments with primary bovine chondrocyte cultures, treated with either retinoic acid or interleukin 1, showed that two forms of catabolic G1 domain, of about 62 and 66 kDa, were formed. Both of these forms reacted on Western blots with anti-CDAGWL and also with anti-NITEGE. It is suggested that cell-mediated catabolism of the aggrecan interglobular domain in these culture systems, whether promoted by retinoic acid or interleukin 1, primarily involves cleavage of the Glu373-Ala374 bond by aggrecanase. The accumulation of G1 domain with a COOH-terminal of Glu373 shows that such aggrecanase-mediated cleavage can occur independent of the cleavage of the Asn341-Phe342 bond by matrix metalloproteinases.

Rab3A and Rab3B carboxy-terminal peptides are both potent and specific inhibitors of prolactin release by rat cultured anterior pituitary cells

Chimeric polypeptides composed of the homeodomain of Antennapedia and of the C-terminus of several low molecular weight GTP-binding proteins of the rab family have been found to translocate through the membrane of cells in culture and to accumulate in the cytoplasm and nucleus. We have used these chimeric peptides to study, in intact endocrine cells, a putative role for the C-terminal domain of rab proteins in the exocytotic process. We show that the internalization of 33- and 32-amino acid polypeptides corresponding to the C-terminal domains of rab3A and rab3B blocks calcium-triggered PRL release from adult rat anterior pituitary cells maintained in primary culture. This effect is specific to rab3 since it is not observed after internalization of either rab1 or rab2 C-terminal peptides. In addition, we demonstrate that this inhibition does not require the geranylgeranylation of the internalized C-termini. As rab3B normally shows a permissive effect on exocytosis in PRL-secreting cells, we suggest that the C-terminal domains of rab3A and rab3B contain structural elements that compete with endogenous rab3 necessary for calcium-induced exocytosis.

Gene sequence and biochemical characterization of FOX-1 from Klebsiella pneumoniae, a new AmpC-type plasmid-mediated beta-lactamase with two molecular variants

Klebsiella pneumoniae BA32, a clinical isolate from Buenos Aires, Argentina, was found to produce a plasmid-encoded beta-lactamase (FOX-1) which conferred resistance to broad-spectrum cephalosporins and cephamycins. Resistance could be transferred by conjugation or transformation into Escherichia coli K-12 via a 48.5-kb plasmid (pGLK1) that produced two FOX-1 molecular variants with isoelectric points of 6.8 and 7.2 and apparent molecular sizes of 37 and 35 kDa, respectively. The kinetic study revealed that the two variants had very similar substrate and inhibition profiles. These values resemble those of chromosomally mediated class C (group 1) cephalosporinases. The structural gene of FOX-1 (blaFOX-1) was cloned into a 2,270-bp PstI-PstI fragment and was expressed in E. coli TG1. The deduced 382-amino-acid sequence of FOX-1 exhibited a high degree of similarity with chromosomally encoded AmpC beta-lactamases of Pseudomonas aeruginosa, Serratia marcescens, Enterobacter cloacae, E. coli, and Citrobacter freundii. These findings suggest that FOX-1 is a plasmid-mediated AmpC-type beta-lactamase that is encoded by a single gene and that has two molecular variants.

Site-directed mutagenesis of penicillin-binding protein 3 of Escherichia coli: role of Val-545

Val545 of the Escherichia coli penicillin-binding protein 3 is essential to the acyl transfer mechanism through which the active-site serine 307 is acylated by benzylpenicillin and cephalexin and to the mechanism through which the protein allows rapidly growing cells to divide.

Transport and internal organization of membranes: vesicles, membrane networks and GTP-binding proteins

Eukaryotic cells contain a variety of membranous organelles such as the Golgi complex and endosomes, which are organized to allow the flow of molecules to specific regions within the cell. Well known examples of this targeted flow include the transport of specific molecules to the apical pole of epithelial cells, to the axon terminals of neurons, and the transcytosis of immunoglobulins. The generally accepted model of transport between the different intracellular compartments maintains that transport is mediated by carrier vesicles, but recent data show the participation of tubulovesicular structures in membrane transport, and the assumed discontinuity of some intracellular compartments has come under considerable scrutiny. It seems that for different intracellular pathways, eukaryotic cells use both the vesicular and the tubular (bolus) means of transport. In this article I will discuss the vesicular and the tubular models of transport as well as a hypothesis for the mechanism of action of small GTPases of the rab family in these movements.

Changes in hypothalamic met-enkephalin levels of rats induced by painful stimulation and morphine treatment

The possible influence of painful stimulation and morphine analgesia on hypothalamic met-enkephalin levels, and the possible correlation between this biochemical parameter and animal behaviour was studied. The results indicate that both painful stimulation and morphine treatment induce an increase in hypothalamic metenkephalin. On the other hand, naloxone did not cause any variation. In animals submitted to painful stimulus, morphine treatment induced a decrease in hypothalamic met-enkephalin levels. Finally, when both morphine and naloxone were administrated before nociceptive stimulation, much higher levels were measured. There was no correlation between the level of hypothalamic met-enkephalin and the pain rating.

Membrane intermediates in the peptidoglycan metabolism of Escherichia coli: possible roles of PBP 1b and PBP 3

The two membrane precursors (pentapeptide lipids I and II) of peptidoglycan are present in Escherichia coli at cell copy numbers no higher than 700 and 2,000 respectively. Conditions were determined for an optimal accumulation of pentapeptide lipid II from UDP-MurNAc-pentapeptide in a cell-free system and for its isolation and purification. When UDP-MurNAc-tripeptide was used in the accumulation reaction, tripeptide lipid II was formed, and it was isolated and purified. Both lipids II were compared as substrates in the in vitro polymerization by transglycosylation assayed with PBP 1b or PBP 3. With PBP 1b, tripeptide lipid II was used as efficiently as pentapeptide lipid II. It should be stressed that the in vitro PBP 1b activity accounts for at best to 2 to 3% of the in vivo synthesis. With PBP 3, no polymerization was observed with either substrate. Furthermore, tripeptide lipid II was detected in D-cycloserine-treated cells, and its possible in vivo use in peptidoglycan formation is discussed. In particular, it is speculated that the transglycosylase activity of PBP 1b could be coupled with the transpeptidase activity of PBP 3, using mainly tripeptide lipid II as precursor.

Modulation of interleukin-1 and tumor necrosis factor expression by beta-adrenergic agonists in mouse ameboid microglial cells

Brain macrophages (ameboid microglial cells) purified to homogeneity and cultured in vitro synthesize and release IL-1 and TNF upon stimulation with lipopolysaccharide (LPS). This induction can be measured at the levels of transcription and translation. In the present study we have analysed whether certain compounds normally present in the nervous tissue could regulate cytokine production by brain macrophages. We demonstrate that the beta-adrenergic agonist isoproterenol, at a concentration of 10(-7) M; inhibits the LPS-induced transcription and release of TNF alpha. At the same concentration, isoproterenol increases the accumulation of IL-1 alpha and IL-1 beta mRNAs. In spite of its strong effect on IL-1 mRNA accumulation, the adrenergic agonist did not enhance IL-1 activity produced by microglial cells. On the contrary, as is the case for TNF, the LPS-induced production of IL-1 was inhibited by isoproterenol. The effects of isoproterenol on cytokine production specifically involve the beta 2 and not the beta 1 adrenergic receptor. It thus appears (i) that the accumulation of mRNAs coding for TNF alpha on one hand and IL-1 alpha and beta on the other is regulated in two opposite ways by the stimulation of the beta 2-adrenergic receptor and (ii) that mRNA accumulation and cytokine production and secretion are not necessarily coupled.

[Colon and rectum ameboma. Clinico-pathological experience with 3 patients]

Amebas are an uncommon complication of amebic colitis. The specific medical treatment rely on the suspicion and a secure diagnosis that permits to the patient, a better clinical course.

Occurrence and evolution of T3 fibroblast nuclei in healing tendons from growing chicks

We applied immunocytochemical techniques including anti-triiodothyronine (T3) serum and microscopic analysis with colloid gold as the developer to identify the specific receptors of thyroid hormones located within the cell nucleus and between the heteroeuchromatin transition zone in 25 chicks. All chicks underwent tenotomy, followed by tenorrhaphy and immobilisation of the leg in plaster. There was a gradual decrease in the number of T3 receptors of collagen-forming fibroblasts as the tendons healed and their capacity to synthetize collagen diminished.

The product of rab2, a small GTP binding protein, increases neuronal adhesion, and neurite growth in vitro

The rab genes code for small GTP binding proteins that share with p21ras the ability to bind and hydrolyze GTP. They present significant sequence homologies with the products of YPT1 and SEC4, two small GTP binding proteins involved in the regulation of secretion in the yeast. Several rab genes are expressed in the developing and adult mouse brain. To test directly the possible involvement of these genes in neuronal differentiation, purified rab proteins produced in E. coli were introduced into neurons dissociated from E15 rat midbrain. The most striking effects were obtained with rab2 protein (rab2p). Compared with untreated cells, neurons loaded with rab2p presented an enhanced adhesion to the culture substratum. This phenomenon was visible 3 hr after seeding and was followed within 24 hr by a dramatic increase in neurite growth. Loading the same population of neurons with the products of four other rab genes either decreased neuronal adhesion and neurite growth or had no effect. These experiments suggest that the expression of rab2p plays an important role in neuronal differentiation.

Endopeptidase 24.15 from rat testes. Isolation of the enzyme and its specificity toward synthetic and natural peptides, including enkephalin-containing peptides

Endopeptidase 24.15, a metalloendopeptidase (EC 3.4.24.15) with an Mr of about 70,000, was purified to homogeneity from rat testes. The enzyme cleaves preferentially bonds on the carboxyl side of hydrophobic amino acids. Secondary enzyme-substrate interactions at sites removed from the scissile bond are indicated by the finding that a hydrophobic or bulky residue in the P3' position greatly contributes to substrate binding and catalytic efficiency. The isolated enzyme is inhibited by metal chelators and by thiols. Loss of enzymic activity after dialysis against EDTA can be restored by low concentrations of Zn2+ and Co2+ ions. The rate of reaction of the Co2+ enzyme with a synthetic substrate was higher than that of the Zn2+ enzyme. These results are consistent with the classification of the enzyme as a metalloendopeptidase. N-Carboxymethyl peptides that fulfil the binding requirements of the substrate recognition site of the enzyme act as potent competitive inhibitors. Biologically active peptides such as luteinizing hormone-releasing hormone, bradykinin and neurotensin are cleaved at sites consistent with the specificity of the enzyme deduced from studies with synthetic peptides. Dynorphin A (1-8)-peptide, beta-neoendorphin, metorphamide, and Metenkephalin-Arg6-Gly7-Leu8 are rapidly converted to the corresponding enkephalins. The testis enzyme is catalytically and immunologically closely related to the previously identified brain enzyme.

Developmental and regional expression of three new members of the ras-gene family in the mouse brain

We have examined the expression in the mouse nervous system of three new members of the ras protooncogene family: rab1, rab2, and rab3. Each of these genes was transcribed into messenger RNAs with different molecular weights. These transcripts has specific developmental and regional patterns of expression. In particular, for the three genes, the ratio between the heavy and light mRNAs depended strongly on developmental stage and brain region. The use of pure neuronal and glial cultures revealed that the high molecular weight transcripts were enriched in neurons and that, in the case of rab2 and rab3, their expression increased with neuronal differentiation. These results are discussed considering the sequence identities between these genes and the yeast YPTI and sec-4 genes, which are known to be implicated in post-Golgi vesicular transport and cytoskeletal stabilization. We propose that the rab genes might be of importance in the regulation of these two processes within the developing and adult nervous system.

Developmental and regional regulation of rab3: a new brain specific "ras-like" gene

Recently, the expression of rab3, a new ras-like gene, has been shown to be restricted to brain tissues (Olofsson et al., 1988). This finding has prompted us to study the expression of rab3 in different brain regions of the developing mouse. The two transcripts corresponding to rab3 (1.8 and 1.3 kb) were first detected in the brains of E13 mouse embryos and were not randomly distributed. Highest levels were found in the mesencephalon, followed by the cortex, striatum, cerebellum, and brain stem in that order. In vitro, the expression of the 1.8-kb transcript was neuron specific, whereas the small transcript was present in neurons and astrocytes. This is the first report showing developmental and regional regulation of a nervous system-restricted ras-like gene. Based on the homologies found between the rab genes and YPT1 or sec-4, we suggest that the physiological role of rab3 might be related to the stabilization of the neuronal cytoskeleton or to post-Golgi vesicle transport and fusion.

Substrate specificity and inhibitors of a capillary injury-related protease from sheep lung lymph

A serine protease (Mr 70,000 to 75,000) appearing in sheep lung lymph after capillary damage induced by Escherichia coli endotoxin, oleic acid, or air emboli, was studied for its specificity toward a series of synthetic peptide and thioester substrates containing an Arg residue in the P1 position. High specificity constants (kcat/Km) were generally obtained with substrates having two or more basic amino acid residues, and with those having a Gln residues in the P2 position. Secondary enzyme-substrate interactions at sites more removed from the scissile bond are of importance, since a few peptides with two basic residues were hydrolyzed slowly, and the site of cleavage of natural peptides was influenced by the amino acid sequence beyond the immediate vicinity of the hydrolyzed bond. The properties of the enzyme and its pattern of specificity distinguish it from enzymes of the clotting cascade, from components of the complement system, and from lung and skin tryptase. The enzyme was inactivated by p-amidinophenylmethanesulfonyl fluoride and by a series of mechanism-based isocoumarin derivatives, the most potent inhibitor being 4-chloro-7-guanidino-3-(2-phenylethoxy)isocoumarin. Enzyme solutions inactivated by reaction with isocoumarin inhibitors could be completely reactivated after 30 h by treatment with hydroxylamine at neutral pH. Formation of a stable sheep lymph acyl enzyme--in contrast to thrombin and other trypsin-like enzymes--is not followed by alkylation of an active site nucleophile that leads to irreversible enzyme inactivation. The high activity toward substrates with two basic residues suggests that the enzyme may potentially function in processing of precursors of bioactive peptides.

Brain macrophages synthesize interleukin-1 and interleukin-1 mRNAs in vitro

Amoeboid microglial cells (brain macrophages) were purified from early post-natal mouse brain cultures. The percentage of cells stained with an anti-Mac-1 antibody was greater than 95%. Stimulation of these brain macrophages by lipopolysaccharides induced the synthesis of interleukin-1 (IL-1), which, in part, remained associated with the cell surface and, in part, was released into the culture medium. In contrast, pure primary astrocyte cultures and cell lines of transformed or immortalised astrocytes did not synthesise significant amounts of IL-1, demonstrating that amoeboid microglia and not astrocytes synthesise IL-1 in vitro. These physiological data were confirmed by RNA hybridisation studies showing that, on LPS treatment, brain macrophages synthesise significant amounts of IL-1 alpha and IL-1 beta mRNAs.

Changes in protein synthesis and in RNA poly A+ population after treatment of Dictyostelium amoebae by 5-bromo-2'-deoxyuridine

Incorporation of 5-bromodeoxyuridine (5-BUdR) into nuclear DNA severely interrupts the life cycle of Dictyostelium discoideum after the first generation of growth. Loose cellular aggregates are then formed, but no spore or stalk cells are detectable and no other morphological transformations are observed. The perturbation of gene expression in the life cycle has been studied at the protein level by two-dimensional gel electrophoresis after pulse labelling with 35S-methionine and also by changes in the patterns of polysomal messenger RNA population. The latter was monitored by hybridisation studies using specific cDNA probes for "vegetative" and "18 hr" messenger RNAs. In the presence of 5-BUdR major anomalies in polypeptide synthesis were observed after the loose aggregation stage. Some vegetative polypeptides, including actin, which are normally abundant only during growth to the aggregation stage, are oversynthesised during the period 12-24 hr after starvation. In this same interval the normal decline in the abundance of vegetative mRNA species was not observed. In marked contrast virtually half the normal "18 hr-specific polypeptides" were poorly synthesised. Likewise, the normal increase in abundance of the corresponding "18 hr-specific" poly A + RNA species in the polysomes did not occur. No major alteration in the timing of the appearance of new macromolecules during the cell cycle was observed in spite of extensive modification of gene expression by the incorporation of 5-BUdR into genomic DNA.

[Gastric duplication with two cysts (author's transl)]

Gastric duplications are rare. The case of a two-year-old girl with double cystic tumors, and a wide connection with the stomach and duodenum, is described and commented upon. A partial resection with excision of the mucosa in the zone closely adhering to the duodenum, and "capitonage" of the raw surface was necessary. A year and a half later, the girl experiences no problems, and the radiological study is practically normal.

Activation parameters and molecular changes induced by substrate hydrolysis of the adenosine triphosphatase of Micrococcus lysodeikticus. A comparison of three different soluble forms of the enzyme

The Arrhenius plots for the active and low activity soluble forms of the ATPase purified from the membranes of Micrococcus lysodeikticus grown at 30 degrees C presented discontinuities at 30 and 33 degrees C, respectively. Their activation parameters differed, being highest for the low activity form of the enzyme. Both forms underwent changes in their molecular properties as a consequence of being enzymically active, i.e., upon incubation with substrates at an adequate temperature. These changes consisted of a decrease in the relative mobilities of some of their subunits in dodecyl sulphate polyacrylamide gel electrophoresis, and the temperature at which they occurred depended on the energy of activation of the particular form of the ATPase used. The low activity form required an incubation temperature of 50 degrees C, whereas for an active form 37 degrees C was sufficient.

Activation parameters of the adenosine triphosphatase of Micrococcus lysodeikticus. A comparison of the soluble and membrane-bound forms of the enzyme

The Arrhenius plots for the membrane-bound ATPase and its soluble form purified from Micrococcus lysodeikticus, presented discontinuities near 30 degrees C at pH 7.5. Glycerol-containing lipids were not responsible for these discontinuities. The values of the enthalpies of activation were 12 (soluble) and 22 (membrane-bound) kcal/mol (50.2 and 92.0 kJ/mol) above 30 degrees C and 42 (soluble) and 29 (membrane-bound) kcal/mol (175.7 and 121.3 kJ/mol) below that temperature. The results suggested that both molecular forms of the ATPase were able to adopt at least two different structures, above and below the critical temperature. Of the two, only the high-temperature structure seemed to be enzymically active. In the case of lipid-dependent ATPases, such as the Escherichia coli enzyme, the transition between both enzyme structures probably occurred with simultaneous "melting" of their lipid microenvironment.