Milk yield residuals and their link with the metabolic status of dairy cows in the transition period.

The transition period is one of the most challenging periods in the lactation cycle of high-yielding dairy cows. It is commonly known to be associated with diminished animal welfare and economic performance of dairy farms. The development of data-driven health monitoring tools based on on-farm available milk yield development has shown potential in identifying health-perturbing events. As proof of principle, we explored the association of these milk yield residuals with the metabolic status of cows during the transition period. Over 2 yr, 117 transition periods from 99 multiparous Holstein-Friesian cows were monitored intensively. Pre- and postpartum dry matter intake was measured and blood samples were taken at regular intervals to determine ß-hydroxybutyrate, nonesterified fatty acids (NEFA), insulin, glucose, fructosamine, and IGF1 concentrations. The expected milk yield in the current transition period was predicted with 2 previously developed models (nextMILK and SLMYP) using low-frequency test-day (TD) data and high-frequency milk meter (MM) data from the animal's previous lactation, respectively. The expected milk yield was subtracted from the actual production to calculate the milk yield residuals in the transition period (MRT) for both TD and MM data, yielding MRTTD and MRTMM. When the MRT is negative, the realized milk yield is lower than the predicted milk yield, in contrast, when positive, the realized milk yield exceeded the predicted milk yield. First, blood plasma analytes, dry matter intake, and MRT were compared between clinically diseased and nonclinically diseased transitions. MRTTD and MRTMM, postpartum dry matter intake and IGF1 were significantly lower for clinically diseased versus nonclinically diseased transitions, whereas ß-hydroxybutyrate and NEFA concentrations were significantly higher. Next, linear models were used to link the MRTTD and MRTMM of the nonclinically diseased cows with the dry matter intake measurements and blood plasma analytes. After variable selection, a final model was constructed for MRTTD and MRTMM, resulting in an adjusted R2 of 0.47 and 0.73, respectively. While both final models were not identical the retained variables were similar and yielded comparable importance and direction. In summary, the most informative variables in these linear models were the dry matter intake postpartum and the lactation number. Moreover, in both models, lower and thus also more negative MRT were linked with lower dry matter intake and increasing lactation number. In the case of an increasing dry matter intake, MRTTD was positively associated with NEFA concentrations. Furthermore, IGF1, glucose, and insulin explained a significant part of the MRT. Results of the present study suggest that milk yield residuals at the start of a new lactation are indicative of the health and metabolic status of transitioning dairy cows in support of the development of a health monitoring tool. Future field studies including a higher number of cows from multiple herds are needed to validate these findings.

Prediction of first test day milk yield using historical records in dairy cows.

The transition between two lactations remains one of the most critical periods during the productive life of dairy cows. In this study, we aimed to develop a model that predicts the milk yield of dairy cows from test day milk yield data collected in the previous lactation. In the past, data routinely collected in the context of herd improvement programmes on dairy farms have been used to provide insights in the health status of animals or for genetic evaluations. Typically, only data from the current lactation is used, comparing expected (i.e., unperturbed) with realised milk yields. This approach cannot be used to monitor the transition period due to the lack of unperturbed milk yields at the start of a lactation. For multiparous cows, an opportunity lies in the use of data from the previous lactation to predict the expected production of the next one. We developed a methodology to predict the first test day milk yield after calving using information from the previous lactation. To this end, three random forest models (nextMILKFULL, nextMILKPH, and nextMILKP) were trained with three different feature sets to forecast the milk yield on the first test day of the next lactation. To evaluate the added value of using a machine-learning approach against simple models based on contemporary animals or production in the previous lactation, we compared the nextMILK models with four benchmark models. The nextMILK models had an RMSE ranging from 6.08 to 6.24 kg of milk. In conclusion, the nextMILK models had a better prediction performance compared to the benchmark models. Application-wise, the proposed methodology could be part of a monitoring tool tailored towards the transition period. Future research should focus on validation of the developed methodology within such tool.

Unaffected semen quality parameters in Neospora caninum seropositive Belgian Blue bulls.

Neospora caninum is a protozoan parasite that causes abortion, perinatal mortality, and subfertility in cattle worldwide. Despite the presence of the DNA of the parasite in semen of infected bulls, the effect on semen quality has not been extensively studied. This study aimed to investigate the effect of a natural Neospora caninum infection on fresh and frozen semen quality parameters in Belgian Blue bulls. Two hundred and fourteen bulls were serologically screened with an indirect ELISA-test specific for anti-Neospora caninum antibodies, every two months during one year. In addition to serological screening, semen was collected twice weekly using an artificial vagina. The following semen quality parameters were assessed: ejaculate volume, concentration, total motility of fresh semen samples, as well as morphology, total and progressive motility for frozen/thawed semen samples. Bulls were semen sampled throughout the whole year, but only semen samples of bulls that had six consecutive positive or negative ELISA-test results were included in our dataset (n = 98). Generalized linear and binomial mixed models were used for statistical analysis of each outcome variable. In these models the explanatory variables were defined as: age, barn location, mean Temperature Humidity Index (THI) during sperm production (14-42 days before sampling), maximum daily THI at collection, season of sperm production, season at collection and the Neospora caninum antibody test results. Initially, individual explanatory variables were tested in univariable models for each outcome variable. Akaike information criterion (AIC) values were used to select explanatory variables to build a multivariable model, where the Neospora caninum test result was forced in all models. The present study reveals an overall apparent seroprevalence of Neospora caninum of 9,2% in the study population. No significant associations were detected between natural neosporosis, substantiated by ELISA-antibody levels, and any of our tested outcome variables on fresh and frozen/thawed semen samples. Based on the results of the present study, we conclude that Neospora caninum seropositive bulls do not have lower semen quality parameters compared with seronegative bulls.

A new method to value efficiency of enzyme blends for pancreatic tissue digestion.

Islet transplantation, since the 1990s, has been an example of human cell therapy. Nevertheless, the islet isolation procedure is not completely standardized; in fact, >50% of islet procedures do not eventuate in transplantation due both to the variability of a donor's pancreas and to the unpredictable efficiency of an enzymatic blend. The enzymes used in pancreas isolation to digest several substrates are extracted from Clostridium histolyticum. In particular, they have strong collagenolytic activity compared with vertebrate collagenases. However, several impediments persist in human islet isolation success, probably owing to the variable composition and concentration of collagenases employed during the digestion phase. For islet isolation processes, neutral proteases play important roles. However, they should be considered to be double-edged swords, contributing to tissue dissociation but, sometimes, decreasing islet yield through fragmentation, breakdown, and inactivation. Protease activities cannot be preciously adjusted in a narrow range, there is no approach to determine the optimal dosage and composition of enzymes for extraction of human islets from the pancreas. At this time, available data on commercial enzymatic activity are not sufficient to predict their efficiency for pancreas digestion; consequently, it is difficult to select enzyme batches. For these reasons, we sought to generate an innovative evaluation assay to select enzymes useful for isolation procedures of pancreatic islets.

Membrane trafficking of CD1c on activated T cells.

We investigated the regulation of and the intracellular trafficking involved in the membrane expression of CD1c antigen on activated mature T cells. Membrane expression of this glycoprotein was highly regulated and dependent on the activation state of the cells. The presence of the CD1c antigen on activated peripheral blood mononuclear cells (PBMCs) was confirmed by flow cytometry, reverse transcriptase-PCR (RT-PCR), and immunoperoxidase staining. The RT-PCR analysis of the alpha3- and 3'-untranslated regions of CD1C showed that phytohemagglutinin (PHA) activation induced expression of transcripts that encode the three isoforms (soluble, membrane, and cytoplasmic/soluble). Immunocytochemical studies showed a specific association of CD1c with the cell membrane and a cytoplasmic, perinuclear distribution. Although flow-cytometric staining confirmed the intracellular presence of CD1c, membrane expression on PHA blast cells was not detected. We found that membrane detection of CD1c antigen was temperature dependent. Cell surface binding of the anti-CD1c monoclonal antibody (mAb) was consistently negative at 4 and 37 degrees C but was detected at room temperature (18-22 degrees C). At physiologic temperatures, activated PBMCs showed intracellular accumulation of the anti-CD1c mAbs, indicating that CD1c cycled between cell surface and intracellular compartments. The CD1c exocytosis pathway was sensitive to Brefeldin A, cytochalasin B, and chloroquine.

Structural effects on the OH-promoted fragmentation of methoxy-substituted 1-arylalkanol radical cations in aqueous solution: the role of oxygen acidity.

A kinetic and product study of the OH- -induced decay in H2O of the radical cations generated from some di-and tri-methoxy-substituted 1-arylalkanols (ArCH(OH)R*+) and 2- and 3-(3,4-dimethoxyphenyl)alkanols has been carried out by using pulse- and gamma-radiolysis techniques. In the 1-arylalkanol system, the radical cation 3,4-(MeO)2C6H3CH2-OH*+ decay at a rate more than two orders of magnitude higher than that of its methyl ether; this indicates the key role of the side-chain OH group in the decay process (oxygen acidity). However, quite a large deuterium kinetic isotope effect (3.7) is present for this radical cation compared with its a-dideuterated counterpart. A mechanism is suggested in which a fast OH deprotonation leads to a radical zwitterion which then undergoes a rate-determining 1,2-H shift, coupled to a side-chain-to-ring intramolecular electron transfer (ET) step. This concept also attributes an important role to the energy barrier for this ET, which should depend on the stability of the positive charge in the ring and, hence, on the number and position of methoxy groups. On a similar experimental basis, the same mechanism is suggested for 2,5-(MeO)2C6H3CH2OH*+ as for 3,4-(MeO)2C6H3CH2OH*+, in which some contribution from direct C-H deprotonation (carbon acidity) is possible. In fact, the latter process dominates the decay of the trimethoxylated system 2,4,5-(MeO)3C6H2CH2-OH*+, which, accordingly, reacts with OH- at the same rate as that of its methyl ether. Thus, a shift from oxygen to carbon acidity is observed as the positive charge is increasingly stabilized in the ring; this is attributed to a corresponding increase in the energy barrier for the intramolecular ET. When R=tBu, the OH- -promoted decay of the radical cation ArCH(OH)R*+ leads to products of C-C bond cleavage. With both Ar = 3,4- and 2,5-dimethoxyphenyl the reactivity is three orders of magnitude higher than that of the corresponding cumyl alcohol radical cations; this suggests a mechanism in which a key role is played by the oxygen acidity as well as by the strength of the scissile C-C bond: a radical zwitterion is formed which undergoes a rate-determining C-C bond cleavage, coupled with the intramolecular ET. Finally, oxygen acidity also determines the reactivity of the radical cations of 2-(3,4-dimethoxyphenyl)ethanol and 3-(3,4-dimethoxyphenyl)propanol. In the former the decay involves C-C bond cleavage, in the latter it leads to 3-(3,4-dimethoxyphenyl)propanal. In both cases no products of C-H deprotonation were observed. Possible mechanisms, again involving the initial formation of a radical zwitterion, are discussed.

Activation-induced expression of CD1d antigen on mature T cells.

In the present study, we investigated the expression of human CD1d antigen on activated mature T cells. Expression of this glycoprotein was found to be highly regulated and dependent on PHA stimulation. Flow cytometry studies using the NOR3.2 antibody, which recognized CD1d under denaturing conditions, showed a clear increase in its expression after PHA stimulation. Expression of this molecule after PHA activation was confirmed by analysis of its corresponding transcript by RT-PCR. A single band representing mRNA for CD1d membrane isoform was observed in activated PBMC as well as in ER3 CD1D-transfected and MOLT-4, pre-T cell lines, which were used as controls. Western blot analysis revealed an activation-dependent increase in CD1d protein expression when PBMC and enriched T cells were activated for different time periods. Activation-dependent expression of CD1d antigen was also confirmed in allogenic-activated T cells, suggesting that this event could have biological significance. Finally, immunocytochemical studies showed the presence of this protein at the plasma membrane accompanied by a cytoplasmic and perinuclear distribution. Results presented herein provide the first experimental evidence showing that CD1d antigen is present on circulating, activated T lymphocytes, suggesting that its expression is dependent on the activation state of the cells. Elucidation of the molecular mechanisms implicated in the activation-dependent expression of this nonclassical antigen will provide new insights into the understanding of antigen presentation and immune regulation.

Antibodies recognizing CD24 LAP epitope on human T cells enhance CD28 and IL-2 T cell proliferation.

Membrane expression of the CD24 molecule on activated T lymphocytes is not elucidated fully. We previously described the intracellular and cell-surface expression of the CD24 sialic acid-dependent epitope(s) on phytohemagglutinin-activated peripheral blood mononuclear cells. However, the CD24 core protein was not detected previously on human T cells. This study reinvestigated the expression and role of CD24 in T cell subsets. We analyzed binding of anti-CD24 monoclonal antibodies (mAbs) to sialic and leucine-alanine-proline (LAP) epitopes in resting and activated, normal T lymphocytes. CD24 LAP and CD24 sialic epitopes were detected on activated CD4- and CD8-positive cells. Although expression of CD24 sialic epitopes remained stably expressed in interleukin (IL)-2-dependent cultures, T cell expression of the LAP epitope was transient. Anti-LAP antibodies strongly enhanced the response of T cells to a combination of anti-CD3/CD28 mAbs and enhanced proliferative response induced by recombinant IL-2. We found similarities in the tissue distribution and function of the human CD24 LAP molecule and the murine, heat-stable antigen, which suggests that CD24 might function as a signaling molecule on human T cells.

Molecular cloning of seprase: a serine integral membrane protease from human melanoma.

Seprase is a homodimeric 170 kDa integral membrane gelatinase whose expression correlates with the invasiveness of the human melanoma cell line LOX. Here, we report the molecular cloning of a cDNA that encodes the 97 kDa subunit of seprase. Its deduced amino acid sequence predicts a type II integral membrane protein with a cytoplasmic tail of 6 amino acids, followed by a transmembrane domain of 20 amino acids and an extracellular domain of 734 amino acids. The carboxyl terminus contains a putative catalytic region (approximately 200 amino acids) which is homologous (68% identity) to that of the nonclassical serine protease dipeptidyl peptidase IV (DPPIV). The conserved serine protease motif G-X-S-X-G is present as G-W-S-Y-G. However, sequence analysis of seprase cDNA from LOX and other cell lines strongly suggests that seprase and human fibroblast activation protein alpha (FAP alpha) are products of the same gene. We propose that seprase/FAP alpha and DPPIV represent a new subfamily of serine integral membrane proteases (SIMP).

Improving chest pain evaluation within a multihospital network by the use of emergency department observation units.

BACKGROUND: Since 1993 the 13 VHA Southern New England (VHA-SNE) hospitals have been engaged in a regionally sponsored initiative to analyze and improve selected clinical processes. Nine of these hospitals have chosen to participate in an initiative in which observation units were postulated to offer a tool for improving the care of patients with chest pain-the VHA initiative to Implement Chest Pain Treatment in Observation Units. THE FIVE PHASES: In phase 1 of the initiative, the VHA-SNE's Clinical Benchmarking Work Group reviewed the medical literature, which confirmed longstanding systemic and pervasive problems in the evaluation of chest pain patients. The work group's preferred practice was the outpatient "rule out myocardial infarction [MI] evaluation" program during monitored observation; serial testing can accurately diagnose low- and moderate-probability patients with MI. In Phase 2 the study group surveyed the emergency departments in the nine hospitals, discovering significant variation in admission rates and practice patterns. During phase 3 the work group identified a health care organization demonstrating best-practice performance--one of the few hospitals in the nation with an operational outpatient "rule out MI evaluation" program. A team site-visited that organization and recorded information about its structure and processes. VHA-SNE then published a monograph that identified its current performance, described the best-practice approach, offered strategies to implement the model program, and analyzed the financial implications and return on investment. In phase 4 a pilot hospital implemented the model program, which in phase 5 is being extended to the other hospitals represented in the work group. Information regarding protocols, lessons learned, and barriers to implementation was freely provided.

Cell adhesion-dependent regulation of cell growth during sea urchin development.

In the sea urchin embryo there are at least two cell adhesion molecules related to mammalian cadherins, one of them, similar to E-cadherin, is expressed in embryos at very early developmental stages, the second appears at the blastula stage (G. Ghersi et al. Mech. Dev. 41, 47-55 (1993)). We show here that when sea urchin embryos are treated with monovalent fragments of antibodies directed against the extracellular domain of these molecules, the decompaction of the embryo is accompanied by a sharp reduction of the rate of cell division. Treatment of the embryos with Fab fragments inhibits thymidine incorporation, but does not affect thymidine uptake or amino acid incorporation. After the first day of development treated embryos have 10 times less blastomeres than normal; later, however, they resume development and give eventually rise to normal-looking plutei. Analysis of putative second messengers shows that treatment of the embryos with anti-cadherin Fabs leads to a decreased tyrosine phosphorylation of the two cadherins and of two cadherin-associated proteins and to a doubling of the intracellular concentration of cAMP. These results are discussed in view of the importance of cell adhesion signals for cell growth control.

Presence of different collagens and collagen mRNAs during embryogenesis and in adult tissues of the sea urchin Paracentrotus lividus.

The presence of four different collagen genes had been previously described in the sea urchin genome and four different cDNAs had been cloned and sequenced. Two of them code for 140 and 300 KDaltons proteins, belonging to the fibrillar collagens, and the other two families code for two type IV collagens with a molecular weight of about 210 KDaltons. In this paper immunological evidence is provided for the presence in the developing P. lividus sea urchin embryo of at least seven major collagen proteins. Western blot analyses, carried out by means of specific polyclonal antibodies, show a series of collagenase sensitive bands, with molecular weights ranging from 55 to 200 KDaltons, which are present from eggs to plutei. Northern blot analyses show the presence of the previously described 6 and 9 Kb RNA bands from oocytes till plutei; in the later stages two other collagen RNAs are detected. The presence of two sets of genes coding for the 6 Kb mRNAs, differentially expressed during development, is also discussed. Immunofluorescence histological analyses show the location of collagen in gonads, oocytes, eggs, embryos and adult tissues.

Comparative mutagenicity of chemicals selected for test in the International Program on Chemical Safety's collaborative study on plant systems for the detection of environmental mutagens.

A review has been made for the four compounds (maleic hydrazide, methyl nitrosourea, sodium azide, azidoglycerol) tested in the International Program on Chemical Safety's collaborative study on plant systems. Maleic hydrazide (MH) is a weak cytotoxic/mutagenic chemical in mammalian tissues and is classified as a class 4 chemical. In contrast, with few exceptions such as Arabidopsis, MH is a potent mutagen/clastogen in plant systems. The difference in its response between plant and animal tissue is likely due to differences in the way MH is metabolized. MH appears to be noncarcinogenic and has been given a negative NCI/NTP carcinogen rating. Methyl nitrosourea (MNU) is a toxic, mutagenic, radiomimetic, carcinogenic, and teratogenic chemical. It has been shown to be a mutagen in bacteria, fungi, Drosophila, higher plants, and animal cells both in vitro and in vivo. MNU is a clastogen in both animal and human cell cultures, plant root tips and cell cultures inducing both chromosome and chromatid aberrations as well as sister-chromatid exchanges. Carcinogenicity has been confirmed in numerous studies and involves the nervous system, intestine, kidney, stomach, bladder and uterus, in the rat, mouse, and hamster. MNU produces stage-specific teratogenic effects and also interferes with embryonic development. The experimental evidence that strongly indicates the mutagenic effects of MNU underlines the possible hazard of this compound to human beings. The experimental evidence for the stringent handling of this compound is clear. Sodium azide (NaN3) is cytotoxic in several animal and plant systems and functions by inhibiting protein synthesis and replicative DNA synthesis at low dosages. It is mutagenic in bacteria, higher plants and human cells and has been used as a positive control in some systems. In general, tests for clastogenicity have been negative or weakly positive. No evidence of carcinogenicity has been reported in a 2-year study seeking carcinogenic activity in male and female rats. Its advantages in comparison to other efficient mutagens are claimed to be a high production of gene mutations accompanied by a low frequency of chromosomal rearrangements and safer handling because of its nonclastogenic and noncarcinogenic action on humans. Azidoglycerol (AG) is a very potent mutagen in bacteria, yeast and higher plants including Arabidopsis and Tradescantia; however, it only slightly enhances the frequencies of recessive lethals in Drosophila. AG is at best a weak clastogen and is without effect in inducing chromosomal aberrations and SCEs in human peripheral lymphocytes in vitro. In microbial and plant systems, AG is considerably more potent than sodium azide in the maximal frequencies of mutation induced. In particular, in Saccharomyces cerevisae, AG is 3000-fold more mutagenic than sodium azide. Its carcinogenic and teratogenic properties are unknown.

Tradescantia stamen hair mutation bioassay.

The Tradescantia stamen hair mutation (Trad-SH) assay (clone 4430) was evaluated for its efficiency and reliability as a screen for mutagens in an IPCS collaborative study on plant systems. Four coded chemicals, i.e. azidoglycerol (AG, 3-azido-1,2-propanediol), N-methyl-N-nitrosourea (MNU), sodium azide (NaN3) and maleic hydrazide (MH) were distributed by the Radian Corporation to the five laboratories in five different countries for testing mutagenicity. Pink mutations were scored between the 7th and 14th day according to a standard protocol. Test results from the five individual laboratories were analyzed and compared after decoding. One out of the two laboratories that conducted tests on AG demonstrated that AG is a mutagen with genetically effective doses ranging from 50 to 100 micrograms/ml. MH yielded positive responses in all laboratories but no linear dose-response pattern was observed. The effective dose range for MH was between 1 and 45 micrograms/ml. The mutagenicity of MNU was reported by five laboratories in the dose range between 10 and 80 micrograms/ml. NaN3, which exhibited a relatively high degree of toxicity, elicited a positive mutagenic response in three of the five laboratories in which it was tested. As with MNU the effective dose for NaN3 ranged between 3 and 80 micrograms/ml. The results from the current study substantiate the Trad-SH assay as a reliable system for screening chemicals for their potential mutagenic effects. Although the study was carried out exclusively under laboratory conditions, a survey of the current literature would indicate that the Trad-SH assay could be an effective in situ monitor of gaseous, liquid, and radioactive pollutants as well.

Tradescantia micronucleus bioassay.

Four coded chemicals, azidoglycerol (AG), N-methyl-N-nitrosourea (MNU), sodium azide (NaN3), and maleic hydrazide (MH), were tested with the Tradescantia micronucleus (Trad-MCN) bioassay by five independent laboratories from five different countries. The purpose of this international collaborative study was to evaluate four plant bioassays, of which the Trad-MCN assay was one, for their sensitivity, efficiency and reliability. The study was carried out under the sponsorship of the International Programme on Chemical Safety. All laboratories adhered to a standard Trad-MCN protocol which suggested that three replicate tests be conducted with each chemical. The results reported by all laboratories, although not equal, showed good agreement among the laboratories. In fact, all five laboratories obtained positive results with MH and MNU, while four of the five laboratories achieved positive results with NaN3. AG was tested in only three laboratories. Two reported negative results, while one reported positive results but only at a single high dose. The data from this study suggest that under normal conditions, the Trad-MCN bioassay is an efficient and reliable short-term bioassay for clastogens. It is suitable for the rapid screening of chemicals, and also is specially qualified for in situ monitoring of ambient pollutants.

Bone marrow micronucleus assay: a review of the mouse stocks used and their published mean spontaneous micronucleus frequencies.

We have examined published negative control data from 581 papers on micronucleated bone marrow polychromatic erythrocytes (mnPCE) for differences in mean frequency and the frequency distribution profile among the mouse stocks used with the bone marrow micronucleus assay. For the 55 mouse stocks with published micronucleus assay data, the overall mean frequency is 1.95 mnPCE/1,000 PCE (1.95 mnPCE/1,000); for the 13 stocks most commonly used in the assay, it is 1.88 mnPCE/1,000. During the last 5 years, the mnPCE rate for these 13 major stocks has been 1.74 mnPCE/1,000. This current mean frequency is a substantial decrease from the mean of 3.07 mnPCE/1,000 observed for these 13 stocks for data published prior to 1981. Of the major stocks, the highest mean mnPCE negative control frequencies were observed for MS/Ae > BALB/c > C57Bl/6, and the lowest for CD-1 < Swiss Webster. We note that hybrid mouse stocks appear to have lower and less variable negative control frequencies than either of their parent strains and that the negative control frequency for some progeny stocks have diverged significantly from that of the parent stocks. Overall mean negative control frequencies appear to be correlated with breadth of the frequency distribution profile of published mean negative control values. Furthermore, a possible correlation between negative control frequency in the micronucleus assay and sensitivity to clastogens of different mouse strains may be indicated. The databases generated here allow us to define a range of norms for both the historical mean frequency and individual experimental mean frequencies for most stocks, but in particular, for the more commonly used mouse stocks. Our analysis, for the most part, bears out the recommendation of the first Gene-Tox Report on the micronucleus assay that the historical negative control frequency for a mouse stock should fall between 1 and 3 mnPCE/1,000. Eighty-six percent of the most commonly used mouse stocks have historical mean frequencies within this range. Though individual experimental mean values would not necessarily be expected to fall within the 1-3.00 mnPCE/1,000 range, 65.3% of the 2,327 published negative control values do, and 83.5% are < 3 mnPCE/1,000. The frequency with which an individual experimental mean value lies outside the 1.00 to 3.00 mnPCE/1,000 range differs among stocks and appears related to the mouse mean frequency. We suggest that the recommended range for historical mean frequency be extended slightly, to approximately 3.4 mnPCE/1,000, to accommodate some commonly used strains with overall mean negative control frequencies just above 3.00 mnPCE/1,000.(ABSTRACT TRUNCATED AT 400 WORDS)

Differential expression and function of cadherin-like proteins in the sea urchin embryo.

Cadherins are Ca(+2)-dependent cell surface proteins involved in the specification of the adhesive properties of cells. They are supposed to play a critical role in morphogenesis and pattern formation. In this paper we show that in the sea urchin embryo there are at least two different cadherins of relative molecular masses 140 and 125 kDa. The 140 kDa cadherin is already present in the fertilized egg and is the sea urchin equivalent of E-cadherin. The 125 kDa cadherin, which can be detected using a broad-spectrum anti-cadherin antibody, appears only at later stages of development. In later embryos these two molecules are distributed differently: E-cadherin is present predominantly in the invaginating endoderm of the gastrula while the 125 kDa protein is present on the cell surface of most epithelia. Consistently with the observed differences in expression and in distribution, antibodies directed against these two cadherins differently perturb sea urchin development. For example, when these antibodies are added to early gastrulas only the antibodies against the 125 kDa component can induce a complete disaggregation of the ectoderm, while anti E-cadherin antibodies induce an abnormal development of the endoderm while the embryo maintains its basic integrity. These results are discussed in view of the need for multiple adhesion receptors during pattern formation and embryogenesis.

The use of Tradescantia and Vicia faba bioassays for the in situ detection of mutagens in an aquatic environment.

Tests have shown plant bioassays to be excellent for mutagenicity studies. Most studies with plant bioassays, however, have been carried out either in the laboratory, or if, in situ, as monitors of atmospheric contaminants. The primary purpose of this study was to assess the utility of in situ plant mutagenicity bioassays in monitoring water contaminants. The assay systems tested were the Tradescantia stamen hair and micronucleus assays for the detection of gene mutations and chromosomal aberrations respectively, and the Vicia faba bioassay system which detects chromosomal aberrations in root tips. The assays were used to test the effluent from a pulp and paper mill located on the north shore of Lake Superior. Assays were performed in a creek containing raw effluent and in the bay of Lake Superior into which the creek emptied. All in situ treatments were carried out for 24 h. The effluent from the creek was heavy with pulp and debris which coated the plant cuttings and the Vicia faba seedlings and may have restricted the uptake from the effluent. In the creek, at test sites 11.5 km from the source, the effluent was toxic to the Vicia faba roots as evidenced by a reduction in the mitotic index. The data for the Tradescantia stamen hair assay in the creek were equivocal. The cuttings from the creek test sites and the air and water control sites appeared to have undergone a physiological delay. Within a day or two after the return to the laboratory, that is 6-8 days after testing, flowering almost ceased and did not fully resume until about day 35. This reduction in flowering was particularly severe with the cuttings from the effluent and air control sites, making it very difficult to interpret the results. In contrast, the Tradescantia micronucleus and Vicia faba chromosomal aberration data were unequivocal; each produced positive responses at both test sites relative to the air and water controls. The results obtained for the bay sites with all 3 assays were in agreement. In that section of the bay visibly contaminated by the creek effluent, increases in stamen hair mutants, micronuclei, and chromosome aberrations were measured. In general, there was a considerable reduction in the number of mutant events observed for the water samples brought back from the test sites and tested in the laboratory.(ABSTRACT TRUNCATED AT 400 WORDS)

Cytoplasmic expression of a CD24-related epitope in human PHA activated normal T lymphocytes.

In this study we have analysed by immunoperoxidase (IPx) and indirect immunofluorescence (IIF) the intracellular and cell surface reactivity of VIB-E3 mAb, previously clustered as anti-CD24 antigen, on resting and activated normal human T lymphocytes. By IPx assay VIB-E3 mAb did not show reactivity with normal resting T cells. In contrast, the analysis of 11 different samples of PHA activated normal mononuclear cells, showed an intracytoplasmic expression of CD24. Kinetic studies showed that CD24 appears 24 to 48 h after PHA stimulation. To our knowledge, this is the first evidence that a CD24-related epitope is expressed in normal activated T lymphocytes.