Demonstration of McCune-Albright mutations in the liver of children with high gammaGT progressive cholestasis

Two patients presented with neonatal cholestasis and acholic stools as first manifestations of McCune-Albright syndrome. Both went through an extensive evaluation including an exploratory laparotomy with peroperative cholangiography which ruled out biliary atresia. One patient presented from the fourth month of life with the classical café-au-lait spots following Blaschko's lines, while less classical café-au-lait spots were seen in the second patient at the age of 4 years. Bone lesions were seen in one patient at the age of 2.5 years and in the other at the age of 4 years. Despite the severity of presentation, both patients cleared their jaundice within 6 months, but still had mild abnormalities of liver function tests. Both patients showed an activating mutation of codon 201 in the gene encoding the alpha-subunit of the G-protein that stimulates adenylcyclase in liver tissue, suggesting that this metabolic defect could be responsible for the cholestatic syndrome. Similar mutations have been found in other affected tissues in patients with the McCune-Albright syndrome. We propose that McCune-Albright syndrome be included in the list for differential diagnosis of neonatal cholestasis and chronic cholestasis of infancy, as a rare cause.

Stromal tumors of the stomach. Review of our experience and reclassification of a series of patients

OBJECTIVE

To retrospectively review a series of 12 patients operated on in our department for stromal tumor of the stomach. Clinical and morphological data, and the patients' postoperative course, were analyzed.

METHODS

Medical records for 12 patients (mean age 63.3 years) were retrospectively reviewed to obtain data on clinical presentation, diagnosis and treatment. Surgical morbidity and mortality were analyzed. A pathologist reviewed the resected specimens to determine the morphological factors of prognostic value. The biological nature of the tumor was reclassified based exclusively on mitotic index, and all tumors were staged according to the TGM system. Recurrence and survival rates were also calculated.

RESULTS

The most frequent clinical presentation was abdominal pain and gastrointestinal bleeding. The most sensitive diagnostic methods were computerized tomography and echographic endoscopy. Operability and resectability rates were 100% and 91.6% respectively. Local resection was done in 5 patients, partial gastrectomy in 5, and extended total gastrectomy in 1. Histologically, 6 cases were muscular tumors (2 leiomyomas, 3 low-grade leiomyosarcomas and 1 high-grade leiomyosarcoma), 2 were gastrointestinal autonomic nerve (GAN) tumors, and 4 were pure stomal tumors. The morbidity rate was 33.3% and the mortality rate was 8.3% (1 patient). All patients were followed up: 1 patient each died after 9 months and 4 years, 1 developed liver metastases after a disease-free interval of 14 months, and the other 9 patients were still alive and free of disease after intervals ranging from 4 months to 7 years.

CONCLUSIONS

Stromal tumors include a group of tumors which may present muscular differentiation (the most frequent type), neural differentiation (GAN tumors) or no differentiation at all (pure stromal tumors). The mitotic index is the most valid parameter to determine biological nature, considering that classification as a benign tumor requires the total absence of mitoses. Treatment was mostly surgical, and local resection with adequate safety margins was effective. Prognosis was relatively good, but long-term follow-up is needed to assess the malignant potential of these tumors.

Diversity among lactococci isolated from ewes' raw milk and cheese

The technological and genetic characteristics of lactococci present in ewes' raw milk and 1-d-old ewes' raw milk cheeses sampled over a 1-year period were investigated. The proportion of lactic acid bacteria isolates from milk samples able to decrease milk pH by more than 1.25 units after 6 h incubation at 30 degrees C reached 14.5% in spring vs 10.7% in summer, 8.3% in autumn and 3.0% in winter. In 1-d-old cheese samples, the proportion of lactic acid bacteria able to lower milk pH by more than 1.25 units increased up to 32.3% in spring vs 23.4% in summer, 8.0% in autumn and 10.3% in winter. Fast acid-producing lactic acid bacteria mainly belonged to the genus Lactococcus. Using polymerase chain reaction protocols, fast acid-producing lactococci were grouped as 61 Lactococcus lactis subsp. lactis, 13 L. lactis subsp. cremoris and 14 L. lactis subsp. lactis biovar diacetylactis. Randomly amplified polymorphic DNA (RAPD) fingerprinting of fast acid-producing lactococci, using two primers, resulted in 21 different RAPD patterns for L. lactis subsp. lactis isolates, nine RAPD patterns for L. lactis subsp. cremoris isolates and three RAPD patterns for L. lactis subsp. lactis biovar diacetylactis isolates. Up to 19 different RAPD patterns were found for L. lactis isolates from cheeses made in a particular month.

Refined X-ray structures of the oxidized, at 1.3 A, and reduced, at 1.17 A, [2Fe-2S] ferredoxin from the cyanobacterium Anabaena PCC7119 show redox-linked conformational changes

The chemical sequence of the [2Fe-2S] ferredoxin from the cyanobacterium AnabaenaPCC7119 (Fd7119) and its high-resolution X-ray structures in the oxidized and reduced states have been determined. The Fd7119 sequence is identical to that of the ferredoxin from the PCC7120 strain (Fd7120). X-ray diffraction data were collected at 100 K with an oxidized trigonal Fd7119 crystal, at 1.3 A resolution, and with an orthorhombic crystal, previously reduced with dithionite and flash frozen under anaerobic conditions, at 1.17 A resolution. The two molecular models were determined by molecular replacement with the [2Fe-2S] ferredoxin from the strain PCC7120 (Rypniewski, W. R., Breiter, D. R., Benning, M. M., Wesenberg, G., Oh, B.-H., Markley, J. L., Rayment, I., and Holden, H. M. (1991) Biochemistry 30, 4126-4131.) The final R-factors are 0. 140 (for the reduced crystal) and 0.138 (for the oxidized crystal). The [2Fe-2S] cluster appears as a significantly distorted lozenge in the reduced and oxidized redox states. The major conformational difference between the two redox forms concerns the peptide bond linking Cys46 and Ser47 which points its carbonyl oxygen away from the [2Fe-2S] cluster ("CO out") in the reduced molecule and toward it ("CO in") in the oxidized one. The "CO out" conformation could be the signature of the reduction of the iron atom Fe1, which is close to the molecular surface. Superposition of the three crystallographically independent molecules shows that the putative recognition site with the physiological partner (FNR) involves charged, hydrophobic residues and invariant water molecules.

PCR amplification of the gene acmA differentiates Lactococcus lactis subsp. lactis and L. lactis subsp. cremoris

The occurrence of the acmA gene, encoding the lactococcal N-acetylmuramidase in new lactococcal isolates from raw milk cheeses, has been determined. Isolates were genotypically identified to the subspecies level with a PCR technique. On the basis of PCR amplification of the acmA gene, the presence or absence of an additional amplicon of approximately 700 bp correlated with Lactococcus lactis subspecies. L. lactis subsp. lactis exhibits both the expected 1,131-bp product and the additional amplicon, whereas L. lactis subsp. cremoris exhibits a single 1,131-bp fragment.

Ferredoxin-NADP(+) reductase uses the same site for the interaction with ferredoxin and flavodoxin

The enzyme ferredoxin-NADP(+) reductase (FNR) forms a 1 : 1 complex with ferredoxin (Fd) or flavodoxin (Fld) that is stabilised by both electrostatic and hydrophobic interactions. The electrostatic interactions occur between acidic residues of the electron transfer (ET) protein and basic residues on the FNR surface. In the present study, several charge-reversal mutants of FNR have been prepared at the proposed site of interaction of the ET protein: R16E, K72E, K75E, K138E, R264E, K290E and K294E. All of these mutants have been assayed for reactivity with Fd and Fld using steady-state and stopped-flow kinetics. Their abilities for complex formation with the ET proteins have also been tested. The data presented here indicate that the mutated residues situated within the FNR FAD-binding domain are more important for achieving maximal ET rates, either with Fd or Fld, than those situated within the NADP(+)-binding domain, and that both ET proteins occupy the same region for the interaction with the reductase. In addition, each individual residue does not appear to participate to the same extent in the different processes with Fd and Fld.

Electron-nuclear double resonance and hyperfine sublevel correlation spectroscopic studies of flavodoxin mutants from Anabaena sp. PCC 7119

The influence of the amino acid residues surrounding the flavin ring in the flavodoxin of the cyanobacterium Anabaena PCC 7119 on the electron spin density distribution of the flavin semiquinone was examined in mutants of the key residues Trp(57) and Tyr(94) at the FMN binding site. Neutral semiquinone radicals of the proteins were obtained by photoreduction and examined by electron-nuclear double resonance (ENDOR) and hyperfine sublevel correlation (HYSCORE) spectroscopies. Significant differences in electron density distribution were observed in the flavodoxin mutants Trp(57) --> Ala and Tyr(94) --> Ala. The results indicate that the presence of a bulky residue (either aromatic or aliphatic) at position 57, as compared with an alanine, decreases the electron spin density in the nuclei of the benzene flavin ring, whereas an aromatic residue at position 94 increases the electron spin density at positions N(5) and C(6) of the flavin ring. The influence of the FMN ribityl and phosphate on the flavin semiquinone was determined by reconstituting apoflavodoxin samples with riboflavin and with lumiflavin. The coupling parameters of the different nuclei of the isoalloxazine group, as detected by ENDOR and HYSCORE, were very similar to those of the native flavodoxin. This indicates that the protein conformation around the flavin ring and the electron density distribution in the semiquinone form are not influenced by the phosphate and the ribityl of FMN.

Expression of presenilin 1 in nervous system during rat development

Alzheimer's disease (AD) is a polygenic disorder involving at least four different genes. Among them, missense mutations in the presenilins segregate with the vast majority of early onset cases of familial AD. To elucidate possible function(s) of presenilin 1 (PS1), we have studied its expression during the development of the rat nervous system. Analysis by in situ hybridization showed expression of PS1 in a variety of cell types and tissues during development, with prominent expression in the nervous system. During late embryogenesis, the ventricular zone presented the highest levels of expression, paralleling the pattern previously reported for Notch. Later, during postnatal development, we observed a peak of PS1 expression at postnatal day 10, particularly in the cerebellum and hippocampus, a time when proliferation and migration are still ongoing and synapse formation is being completed. We propose that presenilins participate in at least two different developmental processes: (1) one involved in neurogenesis and skeleton formation during embryonic development, probably involving coordinate expression with Notch, and (2) a second one in the postnatal central nervous system, perhaps involved in neuritogenic and/or synaptogenic stages, most likely playing a role in amyloid precursor protein processing and amyloid beta production.

Ultrastructural changes during nuclear maturation in Bufo arenarum oocytes

During progesterone-induced nuclear maturation the oocytes of Bufo arenarum undergo a series of nuclear and cytoplasmic changes. The breakdown of heterocellular communications between the follicular cell projections and the oocyte microvilli, and the consequent enlargement of the perivitelline space, were observed at the animal pole. The more evident cytoplasmic feature during nuclear maturation comprised the gathering of glycogen granules in clusters, some phagocytosed by empty vesicles. With respect to the location of these vesicles, some were observed in close proximity to the oolemma and others were freely suspended in the perivitelline space, extruded from the oocyte. Other visible events were the disruption of the annulate lamellae, the formation of an elaborate cortical endoplasmic reticulum and the rearrangement of the cortical granules in a monolayer immediately beneath the oolemma together with aggregates of endoplasmic reticulum cisternae. Our results show that during nuclear maturation the nuclear oocyte changes include a flattening of the spherical oocyte nucleus, its migration towards the surface of the animal pole, the disappearance of the nucleoli and the dissolution of the nuclear envelope.

Response of the aroma fraction in sherry wines subjected to accelerated biological aging

The effect of an acceleration assay, carried out with a periodic aeration and an increased surface/volume ratio, on various aroma compounds of "fino" Sherry wines aging under a veil of a pure culture of Saccharomyces cerevisiae race capensis G1 flor film yeast was studied. The results were subjected to multifactor analysis of variance, and the compounds simultaneously depending on acceleration conditions and aging time at p < 0.01 were subjected to principal component analysis. The first component, accounting for 86.14% of the overall variance, was mainly defined by acetaldehyde and its derivatives 1,1-diethoxyethane and acetoin. These compounds reached higher concentrations in accelerated aging wines in a shorter time than they did in control wines, and no browning problems were detected. Taking into account that these compounds can be used as indicators for biological aging of "fino" Sherry wines, the acceleration condition assayed can be applied to shorten the time of this process.

Electrostatic forces involved in orienting Anabaena ferredoxin during binding to Anabaena ferredoxin:NADP+ reductase: site-specific mutagenesis, transient kinetic measurements, and electrostatic surface potentials

Transient absorbance measurements following laser flash photolysis have been used to measure the rate constants for electron transfer (et) from reduced Anabaena ferredoxin (Fd) to wild-type and seven site-specific charge-reversal mutants of Anabaena ferredoxin:NADP+ reductase (FNR). These mutations have been designed to probe the importance of specific positively charged amino acid residues on the surface of the FNR molecule near the exposed edge of the FAD cofactor in the protein-protein interaction during et with Fd. The mutant proteins fall into two groups: overall, the K75E, R16E, and K72E mutants are most severely impaired in et, and the K138E, R264E, K290E, and K294E mutants are impaired to a lesser extent, although the degree of impairment varies with ionic strength. Binding constants for complex formation between the oxidized proteins and for the transient et complexes show that the severity of the alterations in et kinetics for the mutants correlate with decreased stabilities of the protein-protein complexes. Those mutated residues, which show the largest effects, are located in a region of the protein in which positive charge predominates, and charge reversals have large effects on the calculated local surface electrostatic potential. In contrast, K138, R264, K290, and K294 are located within or close to regions of intense negative potential, and therefore the introduction of additional negative charges have considerably smaller effects on the calculated surface potential. We attribute the relative changes in et kinetics and complex binding constants for these mutants to these characteristics of the surface charge distribution in FNR and conclude that the positively charged region of the FNR surface located in the vicinity of K75, R16, and K72 is especially important in the binding and orientation of Fd during electron transfer.

[Menkes disease: experience in copper salts therapy]

INTRODUCTION

Menkes disease is an X linked genetic disorder of copper intracellular transport. The clinical effects are explainable by impaired activity of various copper-dependent enzymes. The classic form of the disease is characterized by: low temperature, impairment of growth, characteristic hair abnormalities (thin, breakable and grey-haired) and seizures with severe developmental retardation from birth. Treatment with various forms of copper salts has been used, but none of them effective.

CLINICAL CASE

We report a patient diagnosed of Menkes disease at 12 months of age. Copper treatment was commenced at 14 months with 100 micrograms/kg daily intravenous infusion of copper sulphate. On the basis of copper and ceruloplasmin plasma levels, doses of treatment were controlled until a maintained dose of 1,000 micrograms intramuscular of copper sulphate every 17 days, until the age of 6 years. The effects of the treatment were marked by the normalization of the biochemical parameters, the growth development and the hair characteristics. However, no significant effect was shown on the seizures or the neurologic impairment. The patient died at the age of 7 years old.

CONCLUSION

Parenteral therapy for Menkes disease with various inorganic copper salts has been shown to get longer clinical course, but no successful effect on the devastating neurodegenerative progression of the disease.

Variation in Aggressiveness of Canadian Isolates of Phytophthora infestans as Indicated by Their Relative Abilities to Cause Potato Tuber Rot

Studies were conducted in 1995, 1996, and 1997 to determine the ability of Canadian isolates of Phytophthora infestans to cause tuber disease in a variety of potato cultivars. Most isolates of recently introduced multilocus genotypes (US-7, US-8, g11, g26, g29, and g40) were more aggressive on tuber tissue than isolates of the traditional US-1 genotype, based on surface necrosis (SN), lesion depth (LD), and compound aggressiveness index (CAI = SN × LD) components. Other multilocus genotypes (g30, g41, g42, and UN-3) were similar in aggressiveness to US-1. The g11 (US-11) genotype consistently displayed aggressiveness that was intermediate to that of the US-8 and US-1 genotypes. Variation also occurred within a multilocus genotype, and an isolate of the US-8 genotype from New Brunswick was consistently less aggressive than other US-8 isolates. Cvs. Dorita and Island Sunshine were consistently the most resistant to infection, regardless of isolate, relative to the more susceptible responses of Green Mountain, Russet Bur-bank, Kennebec, Superior, Shepody, Red Pontiac, Sebago, and Bintje. Even so, isolates of the newly introduced US-8 genotype were able to cause significantly more disease on these resistant cultivars than isolates of the US-1 genotype. The predominant genotypes currently found in potato production areas in Canada (US-8 and g11) have higher fitness on tuber tissue than displaced, preexisting strains (US-1).

Phase I clinical and pharmacologic study of 13-cis-retinoic acid, interferon alfa, and paclitaxel in patients with prostate cancer and other advanced malignancies

PURPOSE

Recent studies demonstrate that retinoids decrease expression of the anti-apoptotic protein bcl-2, enhance the effect of chemotherapy, and act synergistically with interferon alfa (IFNalpha) to inhibit tumor cell growth in vitro. A phase I trial of 13-cis-retinoic acid (CRA), IFNalpha, and paclitaxel (TAX) was conducted to determine the toxicity and recommended phase II dose of this combination. Pharmacodynamic studies were performed to determine whether CRA and IFNalpha could modulate bcl-2 expression in vitro and in patients.

PATIENTS AND METHODS

Twenty-two patients with prostate cancer or other advanced malignancies were treated with CRA/IFNalpha and escalating doses of TAX. The effect of CRA/IFNalpha on TAX pharmacokinetics was analyzed in both patients and human liver microsomes. The effect of CRA/IFNalpha on bcl-2 expression was assessed in vitro and in peripheral-blood mononuclear cells (PBMCs) by immunoblotting.

RESULTS

CRA 1 mg/kg on days 1 to 4, IFNalpha 6 MU/m(2) subcutaneously on days 1 to 4, and TAX 175 mg/m(2) on day 3 was well tolerated. Pharmacokinetic studies demonstrated that CRA/IFNalpha caused a 33% decrease in TAX clearance and a 23% decrease in the area under the concentration-time curve values of the TAX metabolite 6-alfa-hydroxytaxol (6-HT). CRA alone reduced conversion of TAX to 6-HT by 41% in human liver microsomes. CRA/IFNalpha decreased bcl-2 expression in vitro and in PBMCs.

CONCLUSION

CRA/IFNalpha and TAX is a well-tolerated regimen. CRA/IFNalpha increases TAX area under the concentration-time curve through an inhibitory effect of CRA on the metabolism of TAX to 6-HT. CRA/IFNalpha can modulate bcl-2 expression in vitro and demonstrates similar biologic activity in patients. Further studies will determine the activity of CRA/IFNalpha/TAX and validate the assessment of bcl-2 in PBMCs as a marker of tumor response.

Study of the possible mechanisms involved in the mucosal immune system activation by lactic acid bacteria

The induction of a mucosal immune response is not easy due to the development of oral tolerance, but under some conditions, bacteria can activate this immune system. Antigens administered orally can interact with M cells of Peyer's patches or bind to the epithelial cells. We have demonstrated that certain lactic acid bacteria are able to induce specific secretory immunity, and others will enhance the gut inflammatory immune response. The aim of this work was to establish the reason for these different behaviors and to define possible mechanisms involved in the interaction of lactic acid bacteria at the intestinal level. We studied IgA+ and IgM+ B cells comparatively in bronchus and intestine and CD4+ T cells and IgA anti-lactic acid bacteria antibodies in the intestinal fluid, induced by oral administration of Lactobacillus casei, Lb. delbrueckii ssp. bulgaricus, Lb. acidophilus, Lb. plantarum, Lb. rhamnosus, Lactococcus lactis, and Streptococcus salivarius ssp. thermophilus. The increase in the IgA+ B cells in the bronchus means that these lactic acid bacteria were able to induce the IgA cycle by interaction with M cells from Peyer's patches or intestinal epithelial cells. The IgM+ cells increased when the stimulus did not induce the switch from IgM+ to IgA+. The increase in the CD4+ cells suggests interaction of Peyer's patches and enhancement of the B- and T-cell migration. The anti-lactic acid bacteria antibody is related to the processing and presentation of the microorganisms to the immune cells. We demonstrated that Lb. casei and Lb. plantarum were able to interact with Peyer's patch cells and showed an increase in IgA-, CD4+ cells, and antibodies specific for the stimulating strain. Lactobacillus acidophilus induced gut mucosal activation by interaction with the epithelial cells without increase in the immune cells associated with the bronchus. Although Lb. rhamnosus and Strep. salivarius ssp. thermophilus interact with epithelial cells, they also induced an immune response against their epitopes. Lactococcus lactis and Lb. delbrueckii ssp. bulgaricus induced an increase of IgA+ cells entering the IgA cycle but not CD4+ cells; thus, these bacteria would have been bound to epithelial cells that activated B lymphocytes without processing and presenting of their epitopes. We did not determine specific antibodies against Lc. lactis or Lb. bulgaricus.

Purification and characterization of three extracellular proteinases produced by Pseudomonas fluorescens INIA 745, an isolate from ewe's milk

Three proteinases were isolated from culture medium of Pseudomonas fluorescens INIA 745 and purified to homogeneity by a combination of Phenyl-Sepharose, DEAE-Sepharose, and Sephadex G-100 chromatography. Optimal temperature for enzymatic activity was 45 degrees C for all three proteinases. The pH optimum of proteinases I and II was found to be 7.0, while that of proteinase III was 8.0. Divalent metal ions like Cu2+, Co2+, Zn2+, Fe2+, and Hg2+ were inhibitory to proteinase activity while Ca2+, Mg2+, and Mn2+ had little or no inhibitory effect. The three enzymes were strongly inhibited by EDTA and 1,10-phenantroline and partially by cysteine. The three enzymes are metalloproteinases since they were inhibited by chelators and reactivated by Co2+, Mn2+, Cu2+, and Zn2+. The Km values of proteinases I, II, and III for casein were calculated to be 3.2, 2.6, and 5.2 mg/ml, respectively. Proteinases II and III rapidly degraded beta-casein, with preference to alphas1-casein, whereas proteinase I hydrolyzed both casein fractions at a slow rate.

Influence of the oral administration of lactic acid bacteria on iga producing cells associated to bronchus

Intestinal, respiratory and genitourinary mucosal surfaces are the most important routes of entry for microbial pathogens. The stimulus of the mucosal immunity is not easy because the trigger keys for the activation do not follow the ones of the systemic immune response. In previous works we have demonstrated that some Lactic Acid Bacteria (LAB), when orally administered, can induce an enhance of the gut immune response. Taking into account the concept of a common mucosal response, we studied the effect of orally administered mice with Lactobacillus casei, L. acidophilus, L. rhamnosus, L. delbrueckii subsp. bulgaricus, Streptococcus salivarius subsp. thermophilus and Lactococcus lactis on the IgA secreting cells associated to bronchus. As shown before, oral immunostimulation with LAB induced an increase of the IgA* cells at intestinal level by a dose depending effect. In this study it is also showed that the LAB assayed, with exception of L. acidophilus, were able to enhance IgA+ cells at bronchial level, being also this effect dose dependent. The increment induced by some LAB in the number of IgA+ cells on the mucosa surface of the lower respiratory tract may be very important to prevent bronchus diseases.

Human colon adenocarcinomas express a MUC1-associated novel carbohydrate epitope on core mucin glycans defined by a monoclonal antibody (A10) raised against murine Ehrlich tumor cells

A monoclonal antibody (mAb; A10) raised against murine Ehrlich tumor cell surface carbohydrates was tested for reactivity with human normal and malignant tissues. A10 reacted strongly, with a high proportion of adenocarcinomas arising from colon and other tissues but not with breast carcinomas or other malignant tumors. Normal tissues were virtually A10 unreactive, except for the duct cells from breast and pancreas and some bronchial mucosae. Ultrastructural studies showed mAb A10 immunolabeling of both microvilli and mucin droplets in colon cancer cells but not in normal absorptive or globet cells. A10 reacted strongly with mucin-enriched fractions from colon cancer tissues and HT-29 xenografts but not from normal colon tissues. A10 epitope was carried on MUC1 derived from colon adenocarcinomas and probably on other mucin species, although not on MUC2 molecules. A10 epitope was resistant to exoglycosidases and periodate oxidation but sensitive to the Smith's degradation and beta-elimination, suggesting the involvement of O-linked carbohydrates in nonterminal reducing positions. A mucin-type glycosidic linkage was supported because of the lack of A10 reactivity with HT-29 cells grown with phenyl-N-acetyl-alpha-D-galactosaminide. Deglycosylation studies with trifluoromethanesulfonic acid pointed to the involvement of core mucin glycans in the A10 epitope. This epitope was resistant to protease, O- and N-glycanase treatments carried out on trifluoromethanesulfonic acid-deglycosylated mucins. Inhibition studies with core 1, core 2, core 3, and core 6 suggested the latter [GlcNAcbeta(1-6)GalNAc] as being involved in A10 epitope. Taken together, the present results point to A10 defining a core 6-related epitope on core mucin glycans expressed by colon cancer MUC1 not previously associated with human cancer.

delta-catenin, an adhesive junction-associated protein which promotes cell scattering

The classical adherens junction that holds epithelial cells together consists of a protein complex in which members of the cadherin family linked to various catenins are the principal components. delta-catenin is a mammalian brain protein in the Armadillo repeat superfamily with sequence similarity to the adherens junction protein p120(ctn). We found that delta-catenin can be immunoprecipitated as a complex with other components of the adherens junction, including cadherin and beta-catenin, from transfected cells and brain. The interaction with cadherin involves direct contact within the highly conserved juxtamembrane region of the COOH terminus, where p120(ctn) also binds. In developing mouse brain, staining with delta-catenin antibodies is prominent towards the apical boundary of the neuroepithelial cells in the ventricular zone. When transfected into Madin-Darby canine kidney (MDCK) epithelial cells delta-catenin colocalized with cadherin, p120(ctn), and beta-catenin. The Arm domain alone was sufficient for achieving localization and coimmunoprecipitation with cadherin. The ectopic expression of delta-catenin in MDCK cells altered their morphology, induced the elaboration of lamellipodia, interfered with monolayer formation, and increased scattering in response to hepatocyte growth factor treatment. We propose that delta-catenin can regulate adhesion molecules to implement the organization of large cellular arrays necessary for tissue morphogenesis.

The effect of homogenization of whole milk, skim milk and milk fat on nisin activity against Listeria innocua

Whole milk, skim milk and an emulsion of milk fat in water, inoculated with approx. 10(5) cfu/ml of Listeria innocua, were treated at 30 degrees C with 100 IU/ml of nisin, homogenization at 200 bar or both procedures. Nisin activity and survival of L. innocua after treatments were determined. Recovery of nisin activity from non-homogenized whole milk treated with 100 IU/ml of nisin was complete, whereas a loss of 18 to 28% of activity was detected in non-homogenized fat-in-water emulsion. Loss in nisin activity due to homogenization represented up to 64% in whole milk and 62% in fat-in-water emulsion. Nisin addition by itself achieved a reduction in L. innocua counts of 3.7-3.8 log units in whole milk and 3.6 log units in fat-in-water emulsion compared to numbers in untreated samples. When nisin-containing whole milk and fat-in-water emulsion were homogenized, L. innocua counts were only reduced by 2.6-2.9 log units and 2.5 log units, respectively, compared to numbers in untreated samples. Homogenization of nisin-containing skim milk resulted in a loss of nisin activity of 20% but achieved a reduction of 3.0 log units in L. innocua counts.