Nucleoside diphosphate kinase from Escherichia coli

Nucleoside diphosphate (NDP) kinase from Escherichia coli was purified to homogeneity and was crystallized. Gel filtration analysis of the purified enzyme indicated that it forms a tetramer. The enzyme was phosphorylated with [gamma-32P]ATP, and the pH stability profile of the phosphoenzyme indicated that two different amino acid residues were phosphorylated. Both a histidine residue and serine residues, including Ser-119 and Ser-121, appear to be phosphorylated. A Ser119Ala/Ser121Ala double mutant (i.e., with a Ser-to-Ala double mutation at positions 119 and 121), as well as Ser119Ala and Ser121Ala mutants, was isolated. All of these retained NDP kinase activity; also, both the Ser119Ala and Ser121Ala mutants could still be autophosphorylated. In the case of the double mutant, a slight autophosphorylation activity, which was resistant to acid treatment, was still detected, indicating that an additional minor autophosphorylation site besides His-117 exists. These results are discussed in light of the recent report of N. J. MacDonald et al. on the autophosphorylation of human NDP kinase (J. Biol. Chem. 268:25780-25789, 1993).

Elemental diet and IV-TPN-induced bacterial translocation is associated with loss of intestinal mucosal barrier function against bacteria

OBJECTIVE

The goal of the current study was to directly assess the role of loss of mucosal barrier function in nutritionally induced bacterial translocation.

BACKGROUND

Parenteral and certain elemental enteral diets have been shown to promote bacterial translocation. The mechanisms underlying this observation, especially the question of whether nutritionally induced bacterial translocation is primarily related to loss of intestinal barrier function, versus an impaired immune system, remain to be fully elucidated.

METHODS

Bacterial translocation was measured in vivo, ileal mucosal membranes were harvested, and their electrophysiologic properties and barrier function were measured ex vivo in the Ussing chamber system 7 days after receiving total parenteral nutrition solution parenterally (IV-TPN) or enterally (elemental diet). Chow-fed rats served as control subjects.

RESULTS

The incidence of bacterial translocation was significantly increased both to the mesenteric lymph nodes in vivo and across the in vitro Ussing chamber-mounted ileal mucosal membranes of the elemental diet-fed and IV-TPN-fed rats. The magnitude of Escherichia coli and phenol red transmucosal passage in the Ussing chamber was significantly higher in the IV-TPN-fed rats than in the elemental diet-fed or chow-fed animals. The potential differences across the ileal membrane were similar between the three groups at all time points. However, the specific resistances of the ileal membranes of the IV-TPN and elemental diet groups were significantly less than the chow-fed animals, indicating increased membrane permeability.

CONCLUSIONS

Loss of intestinal barrier function plays a major role in nutritionally induced bacterial translocation, and the loss of mucosal barrier function to both E. coli and phenol red appeared greater in the IV-TPN than the elemental diet-fed rats.

Calcium and phospholipase A2 appear to be involved in the pathogenesis of hemorrhagic shock-induced mucosal injury and bacterial translocation

OBJECTIVE

The mechanism by which hemorrhagic shock injures the gut and leads to the translocation of bacteria remains incompletely determined. Since increased free cellular calcium levels and phospholipase A2 activity can lead to cellular injury and both have been documented in certain shock states, the hypothesis that calcium or phospholipase A2 may play a role in hemorrhagic shock-induced gut mucosal injury and bacterial translocation was tested.

DESIGN

Prospective animal study with concurrent controls.

SETTING

Small animal laboratory.

SUBJECTS

Fifty-seven male Sprague-Dawley rats weighing 250 to 350 g.

INTERVENTIONS

Five groups of rats were tested utilizing a nonlethal hemorrhagic shock model (mean arterial pressure of 30 mm Hg for 30 mins). These groups included: a) sham-shock, b) shock, c) shock plus quinacrine (inhibitor of phospholipase A2), d) shock plus diltiazem (calcium-channel blocker) administered 5 mins before hemorrhage, and e) shock plus diltiazem administered at the end of shock period and before resuscitation. At 24 hrs postshock or sham-shock, the animals were killed, the mesenteric lymph node and cecum were cultured and the gut was examined histologically.

MEASUREMENTS AND MAIN RESULTS

The occurrence rate of shock-induced bacterial translocation (90%) was significantly reduced in rats receiving quinacrine (27%) or preshock diltiazem (21%) (p < .05), but not postshock diltiazem (63%). Bacterial translocation did not occur in sham-shocked rats. The same amount of blood withdrawal was needed between all groups of rats to induce and maintain shock. Quinacrine and diltiazem administration largely prevented shock-induced ileal and cecal mucosal injury.

CONCLUSIONS

The observation that quinacrine and preshock diltiazem limited the extent of shock-induced mucosal injury and bacterial translocation indicate that calcium and phospholipase A2 are involved in the pathogenesis of shock-induced mucosal injury and bacterial translocation. The fact that preshock but not postshock diltiazem was protective indicates that the process leading to shock-induced calcium-mediated tissue injury and bacterial translocation was initiated during the ischemic rather than the reperfusion period. However, since neither quinacrine nor diltiazem was fully protective, other factors, such as oxidants, are also likely to be involved in the pathogenesis of shock-induced mucosal injury and bacterial translocation.

Selective nuclear transport of mu-calpain

To study nuclear transport of purified calpains in an in vitro system, A431 cells were permeabilized with digitonin, and fluorescein-labeled calpains were introduced under conditions known to facilitate energy-dependent nuclear transport of proteins. Fluorescein-mu-calpain was transported into nuclei in an ATP-dependent fashion. The calpain-specific inhibitor protein, calpastatin, could not block mu-calpain translocation. Fluorescein-calpastatin and fluorescein-m-calpain were poorly transported at best. In the presence of rat liver cytosolic factors, accumulation of nuclear mu-calpain was maximum at approximately 1 microM Ca2+, and no transport was observed at 0.3 microM Ca2+. Rat erythrocyte and HeLa cell extracts supported transport in the absence of Ca2+.

The presence but not the sequence of the N-terminal peptide in cardiac TnC is important for function

The most diverged region of the primary amino acid sequence between cardiac (cTnC) and fast skeletal troponin C is the N-terminal ten amino acids. We report here that major changes in the primary sequence of this region in cTnC had a minimal effect on the ability of the mutant proteins to recover maximal activity in TnC-extracted cardiac and fast skeletal muscle myofibrils. However, deletion of the N-terminal nine amino acids resulted in a 60% decrease in maximal Ca(2+)-dependent ATPase activity with only a small change in the pCa50 of activation. Deletion of the N-terminal peptide did not appear to appreciably affect the Ca(2+)-binding properties of cTnC, but it did alter the interaction with hydrophobic fluorescent probes. Thus, the presence but not the sequence, of the N-terminal extension is important for the maximal activity of cTnC. The N-terminal helix may function in a relatively non-specific manner to prevent unfavorable interactions between domains in cTnC or between cTnC and other troponin subunits.

Insensitivity of the present hsp26 chromatin structure to a TATA box mutation in Drosophila

The role of the TATA element in establishing the chromatin structure and inducible transcription of the Drosophila melanogaster hsp26 gene has been analyzed. An hsp26/lacZ fusion gene with a mutant promoter, in which the TATA box sequence TATAAA was changed to CCCAAA, was introduced into Drosophila by P-element transformation. The mutation had little effect on formation of the preset chromatin structure observed prior to induction. However, the mutation dramatically reduced transcription levels following heat shock. Northern analysis indicated that weak, inducible expression of the mutant promoter occurred within the same period of heat shock as for the normal promoter, suggesting that TFIID was associated with the mutant promoter prior to heat shock. Biochemical analysis showed that the mutant promoter still bound TFIID in vitro, but with 3-5-fold less affinity than the normal promoter. DNase I footprinting revealed that the conformation of the TFIID-DNA complex differed significantly from that of the normal promoter. These results indicate that alterations in the conformation or the stability of the TFIID-DNA complex drastically reduce the level of induction, but do not dramatically affect chromatin structure formation. Formation of the requisite chromatin structure is either independent of, or highly tolerant of, changes in the TFIID-DNA complex.

Fusion with E2A converts the Pbx1 homeodomain protein into a constitutive transcriptional activator in human leukemias carrying the t(1;19) translocation

E2A-PBX1 is a chimeric gene formed by the t(1;19)(q23;p13.3) chromosomal translocation of pediatric pre-B-cell leukemia. The E2A-Pbx1 fusion protein contains sequences encoding the transactivation domain of E2A joined to a majority of the Pbx1 protein, which contains a novel homeodomain. Earlier, we found that expression of E2A-Pbx1 causes malignant transformation of NIH 3T3 fibroblasts and induces myeloid leukemia in mice. Here we demonstrate that the homeodomains encoded by PBX1, as well as by the highly related PBX2 and PBX3 genes, bind the DNA sequence ATCAATCAA. E2A-Pbx1 strongly activates transcription in vivo through this motif, while Pbx1 does not. This finding suggests that E2A-Pbx1 transforms cells by constitutively activating transcription of genes regulated by Pbx1 or by other members of the Pbx protein family.

Nucleosome positioning and gene regulation

Recent genetic and biochemical studies have revealed critical information concerning the role of nucleosomes in eukaryotic gene regulation. Nucleosomes package DNA into a dynamic chromatin structure, and by assuming defined positions in chromatin, influence gene regulation. Nucleosomes can serve as repressors, presumably by blocking access to regulatory elements; consequently, the positions of nucleosomes relative to the location of cis-acting elements are critical. Some genes have a chromatin structure that is "preset," ready for activation, while others require "remodeling" for activation. Nucleosome positioning may be determined by multiple factors, including histone-DNA interactions, boundaries defined by DNA structure or protein binding, and higher-order chromatin structure.

Bacterial translocation is bacterial species dependent: results using the human Caco-2 intestinal cell line

BACKGROUND

Because of in vivo limitations, the mechanisms underlying the process of bacterial translocation are poorly understood. Thus, an in vitro model system to study the translocation process was developed.

METHODS

Transformed human colonic carcinoma (Caco-2) intestinal cells were grown as a polarized monolayer on semi-permeable membranes contained in the upper compartment of a two-compartment system. Once the Caco-2 monolayer had reached confluence, the ability of six different species of bacteria to translocate across the monolayer was tested using a dose-response curve of bacteria (10(2), 10(4), or 10(6)) organisms.

RESULTS

At inocula of 10(4) or 10(6) but not 10(2) organisms, bacteria crossed the monolayer. Bacterial passage across the monolayer was bacterial species specific, with gram-negative enterics being the best, gram-positive aerobes being intermediate translocators, and strict anaerobes being the poorest translocators.

CONCLUSION

The results of this study indicate that bacteria translocate across the Caco-2 monolayer in a dose-dependent and species-related fashion and support the use of this in vitro epithelial cell culture system as a model for studying bacterial transport.

Abnormal phosphorylation of tau proteins associated with bovine brain microtubules: activation by excess ATP and tyrosine dephosphorylation

Phosphorylation of tau protein has been suggested as a major mechanism regulating its functions. In assembled brain microtubules, tau is phosphorylated, but additional phosphorylation can be induced in vitro. Supply of excess ATP alone was sufficient to reduce migration of tau on SDS gels, diminish Tau-1 immunostaining, and induce the expression of epitopes recognized by the PHF-1 antibody, suggesting that Alzheimer-type phosphorylation may have occurred. Okadaic acid had no further effect. However, treatment with tyrosine kinase inhibitors modifies the phosphorylation profiles of tau proteins. Most evidently, migration of the largest tau isoform was further retarded on SDS gels and PHF-1 immunostaining was enhanced. The profound effect of tyrosine kinase inhibitors on tau phosphorylation was also demonstrated in living cells following microinjection of cultured hippocampal neurons. Identification of proline-directed protein kinases and their regulatory factors associated with assembled microtubules indicated the presence of multiple phosphorylation pathways in microtubules. Our results are consistent with the hypothesis that sequential phosphorylation of tau proteins is at least partially mediated through tyrosine phosphorylation/dephosphorylation mechanisms.

Hirsutoid papillomas of vulvae: absences of human papilloma virus (HPV) DNA by the polymerase chain reaction

We have analyzed the specimens from 16 women with hirsutoid papillomas of the vulvae for the presence of HPV DNA using the polymerase chain reaction. The subjects' ages ranged from 27 to 43 years. In all cases, smooth or filiform papules were symmetrically located on the inner surface of both labia minora. Histologically, the lesions consist of acanthosis or papillomatosis without koilocytes and mitotic activity. Eight of 16 specimens were studied by transmission electron microscopy (TEM). No HPV granules were found in the nuclei of keratinocytes. HPV DNA could not be detected in all specimens. Positive controls were present in each assay. These results suggest that the papules of hirsutoid papillomas of the vulvae are unrelated to HPV. Chronic irritants and inflammation may play an important role in pathogenesis.

Characterization of the autophosphorylation of Era, an essential Escherichia coli GTPase

Era is an essential protein in Escherichia coli which binds both GTP and GDP and has an intrinsic GTPase activity. Studies on the role of GTP/GDP binding and GTPase activity in an attempt to understand its function lead to the observation that Era is autophosphorylated. The autophosphorylation reaction is specific for GTP and cannot use ATP as a phosphoryl group donor. The reaction velocity is of first order with respect to protein concentration, suggesting an intramolecular mechanism. Autophosphorylation occurs at serine and threonine residues. The major phosphorylated tryptic peptide isolated after autophosphorylation has been identified as ISITSR, from residue 33 to 38. The peptide contains the site of phosphorylation and two potential sites for serine and threonine phosphorylation. Subsequently, both the threonine residue at position 36 and the serine residue at position 37 were altered to alanine. The double mutant Era, but not individual single mutants, was unable to functionally complement the growth of an E. coli strain which cannot produce wild-type Era protein at high temperature. This suggests that either threonine 36 or serine 37 has to exist for the function of Era in vivo. In vivo phosphorylation of Era was also examined by two-dimensional gel electrophoresis. Era has been previously assigned two distinct positions having two different X-Y co-ordinates: one of the spots (H032.0) was identified as phosphorylated Era, indicating that a substantial portion of Era in the cell is indeed phosphorylated. Therefore, Era autophosphorylation is likely to play an important physiological role in the cell.(ABSTRACT TRUNCATED AT 250 WORDS)

The modulatory role of gut hormones in elemental diet and intravenous total parenteral nutrition-induced bacterial translocation in rats

We have previously shown that parenteral and certain elemental diets promote bacterial translocation and that this diet-induced bacterial translocation can be prevented by the provision of bulk-forming dietary fiber. The goal of the current study was to test the hypothesis that fiber's protective effect on diet-induced bacterial translocation was mediated by trophic gut hormones. This hypothesis was tested by using bombesin (which stimulates gut hormone release) or the somatostatin analog Sandostatin (which inhibits gut hormone release) to modulate gut hormone release in rats receiving rat food, intravenous total parenteral nutrition, or an elemental diet. Both bombesin and fiber were effective in preventing elemental diet-induced bacterial translocation, whereas octreotide acetate abrogated the protective effect of fiber. Bombesin was also effective in limiting bacterial translocation in parenterally fed rats. Although both enteral (elemental diet) and parenteral diet-induced bacterial translocation were associated with cecal bacterial overgrowth, loss of small-bowel weight, and loss of mucosal protein content, none of these factors seemed to be primarily responsible for bacterial translocation. Because bombesin decreased the incidence of villous injury in the elemental diet-fed rats and decreased the incidence of villous injury and prevented loss of intestinal barrier function to horseradish peroxidase in the parenterally fed rats, it is possible that bombesin exerted its protective effect by limiting mucosal injury and preserving barrier function.

Architectural variations of inducible eukaryotic promoters: preset and remodeling chromatin structures

The DNA in a eukaryotic nucleus is packaged into a nucleosome array, punctuated by variations in the regular pattern. The local chromatin structure of inducible genes appears to fall into two categories: preset and remodeling. Preset genes are those in which the binding sites for trans-acting factors are accessible (i.e. in a non-nucleosomal, DNase I hypersensitive configuration) prior to activation. In response to the activation signal, positive factors bind to cis-acting regulatory elements and trigger transcription with no major alterations in the chromatin structure of the promoter region. In contrast, remodeling genes are those in which some of the required cis-acting regulatory elements are packaged into nucleosomes. The nucleosomes must be perturbed in response to an activation signal in order for the trans-acting factors to gain access to cis-acting elements; a chromatin remodeling process which forms DNase I hypersensitive sites must occur. In both cases, precise positioning of nucleosomes along the promoter region of a gene appears to be critical for appropriate regulation of expression.

In vitro analysis of microtubule assembly of isotypically pure tubulin dimers. Intrinsic differences in the assembly properties of alpha beta II, alpha beta III, and alpha beta IV tubulin dimers in the absence of microtubule-associated proteins

Microtubule assembly of different beta tubulin isotypes in the presence of 4 M glycerol and 6 mM magnesium ion demonstrates significantly different characteristics. alpha beta II and alpha beta IV assembled faster and to a greater extent than did unfractionated phosphocellulose-purified tubulin (PC-tubulin). Microtubule assembly from alpha beta III showed a distinctive delay in nucleation, proceeded at a slower rate than those of the other beta tubulin isotypes, and had the highest critical concentration. However, treatment of beta tubulin isotypes with subtilisin to remove the C-terminal domain of the tubulin dimer abolished these differences in microtubule assembly pattern and enhanced self-assembly. The kinetic analysis of microtubule elongation of different beta tubulin isotypes also showed significant differences. Elongation of alpha beta III from microtubule seeds had a lower apparent K alpha and a lower apparent Kd than did alpha beta II and alpha beta IV. The dynamic behaviors of different beta tubulin isotypes were qualitatively similar to each other and fit the dynamic instability model. However, microtubules formed from alpha beta III appeared to be less dynamic than microtubules formed from other beta tubulin isotypes. Our results suggest that the beta III isotype might have a different conformation than do the other beta tubulin isotypes. The distinctive nucleation and elongation behaviors of the alpha beta III dimers demonstrated in vitro may have a significant influence on microtubule functions in vivo.

Bombesin protects against bacterial translocation induced by three commercially available liquid enteral diets: a prospective, randomized, multigroup trial

OBJECTIVE

To test the hypothesis that certain commercially available liquid diets would cause bacterial translocation and that this diet-induced translocation could be reduced with bombesin (an intestinal hormone stimulant).

DESIGN

Prospective, multigroup trial in which animals fed each test diet were randomized to receive either bombesin or saline for 7 days. On day 7, the mice were killed and their organs were cultured for translocating bacteria, their cecal bacterial population concentrations were measured, and ileal and jejunal mucosal protein content was determined.

SETTING

Small animal laboratory.

SUBJECTS

Outbred ICR mice weighing 25 to 35 g.

INTERVENTIONS

Mice received bombesin (10 micrograms/kg) or saline subcutaneously three times daily for 7 days before sacrifice.

MEASUREMENTS AND MAIN RESULTS

The incidence of bacterial translocation to the mesenteric lymph node was significantly increased (p < .05) in mice fed Vivonex (53%), Criticare (67%), or Ensure (60%) compared with chow-fed controls (0%). All three liquid diets were associated with the development of cecal bacterial overgrowth and loss of jejunal and ileal mucosal protein content. Bombesin reduced the incidence of bacterial translocation and loss of mucosal protein content in all three liquid diet groups (p < .05), but did not prevent diet-induced cecal bacterial overgrowth.

CONCLUSIONS

Three different liquid diets induced bacterial translocation to the mesenteric lymph node. Since bombesin was effective in reducing bacterial translocation, it appears that bacterial translocation induced by these liquid diets can be modulated hormonally.

Macrophage elimination increases bacterial translocation and gut-origin septicemia but attenuates symptoms and mortality rate in a model of systemic inflammation

OBJECTIVE

The central question tested in this study was whether dichloromethylene-diphosphonate (CL2MDP) liposome-mediated elimination of hepatic and splenic macrophages would influence zymosan-induced bacterial translocation and the zymosan-induced generalized inflammatory response.

SUMMARY BACKGROUND DATA

Both an uncontrolled activation of macrophages and the loss of intestinal barrier function have been implicated in the development of adult respiratory distress syndrome and multiple organ failure.

METHODS

Macrophage elimination was accomplished by intravenous injection of 200 microL of CL2MDP-liposome suspension. Control mice received an intravenous injection of 200 microL of phosphate-buffered saline. Two days later, the animals were challenged intraperitoneally with zymosan suspended in paraffin to determine a dose-response curve (0.1, 0.5, or 1.0 mg/g body weight). Twenty-four hours after zymosan challenge, signs of systemic stress were determined, and bacterial translocation to the mesenteric lymph node, liver, spleen, and blood was measured. A separate mortality study was performed with a dose of 1.0 mg/g of zymosan suspension.

RESULTS

The incidence of the systemic spread of bacteria was significantly increased in the macrophage-depleted mice. Although systemic bacterial translocation was promoted by macrophage elimination, the systemic toxic response was significantly decreased in all macrophage-depleted groups (p < or = 0.01). The 12-day mortality rate was 0% in the macrophage-depleted groups and 27% in the control group (p = 0.05).

CONCLUSIONS

The lethal and toxic effects of zymosan appear to be related more to the excessive activation of macrophages than to the systemic spread of bacteria.

[A preliminary study on serological differentiation between antibody against Brucella and that against Yersinia enterocolitica serotype O: 9]

Standard agglutination test (SAT), enzyme-linked immunosorbent assay (ELISA), dot immunobinding assay (DIBA) have been developed for the detection of antibodies against 6 strains of Brucella and that against Yersinia enterocolitica Serotype O: g. The results showed that differentiation could be made between Brucella and Yersinia O: 9 when 16M SPA, OMP and YO: 3 SPA. OMP were used by ELISA, but not when 104M and YO: 9 antigens were used by SAT. So, 16M and YO: 3 OMP antigens were better for detection of antibodies against Brucella and Yersinia O: 9 by ELISA.

Nerve growth factor synthesis by mouse submandibular gland cells in culture

Mouse submandibular gland (SMG) cells in culture rarely retain functional properties of SMG cells in vivo. We demonstrate that both primary SMG cells and the mouse SMG cell line SCA-9 secrete biologically active nerve growth factor (NGF). However, primary cells secrete 40-fold more NGF than SCA-9 cells, demonstrating that SCA-9 cells cannot substitute for primary SMG cells for the study of SMG NGF in vitro.

p44mpk MAP kinase induces Alzheimer type alterations in tau function and in primary hippocampal neurons

Abnormally phosphorylated tau protein is a major component of the cytoskeletal pathology of Alzheimer's disease (AD) found in the neurofibrillary tangle (NFT) and neuritic plaque (NP). Identification of the kinase responsible for this phosphorylation has been difficult. In the test tube, several proline-directed kinases, particularly mitogen-activated protein (MAP) and cdc2 kinase, phosphorylate tau on sites that appear to mimic the abnormally phosphorylated sites in AD. Important unanswered issues include: 1) whether this phosphorylation event occurs in the tightly regulated environment of a living cell; 2) whether this phosphorylation of tau affects its functional properties; and 3) what is the subcellular relationship of proline-directed kinases and tau. We show here that tau can be phosphorylated in cultured hippocampal neurons by the MAP kinase p44mpk, and phosphorylation of tau compromises its functional ability to assemble microtubules. We show further that MAP kinase copurifies with microtubule fractions where it is tyrosine phosphorylated and presumably active. These studies address and raise several important issues regarding the regulation of tau phosphorylation in normal and AD brain.

Proline-directed kinase systems in Alzheimer's disease pathology

Immunohistochemical analysis was used to assess the distribution of the proline-directed kinase, cdc2, in Alzheimer's disease (AD) pathology. A robust signal was most prominent in the neurofibrillary tangle (NFT) of affected neurons that also contained abnormally phosphorylated tau protein. Biochemical analysis identified a pool of cdc2 in bovine brain microtubules that contain normal tau. These results strongly support the hypothesis that cdc2 is involved in the abnormal phosphorylation of tau in AD pathology and they raise important issues regarding regulation of tau phosphorylation in normal and diseased neurons.

[The pathological changes of lip biopsies and dental caries on Sjogren's syndrome]

This paper showed that in 110 cases of Sjogren's syndrome(SS),the caries incidence was high and was related to the salivary gland lesions.In comparison with 90 matched no SS group,the incidence of caries in SS was 88.18%,and in no SS group 73.33%(P<0.01).The average of caries in cases with more than ten inflammatory foci were significantly increased than in those less than ten,no significant difference in the average of caries was observed between primary and secondary SS.The amounts of salivary excretion measured were significantly decreased in 30 cases with SS than in no SS group cases,and the more the inflammatory foci,the less the salivary excretion.

Removal of beta III isotype enhances taxol induced microtubule assembly

The interaction of beta III-depleted tubulin with taxol was investigated. A monoclonal antibody against the beta III tubulin isotype was immobilized on a sepharose 4B column and used to remove the beta III tubulin isotype from unfractionated tubulin. The assembly of beta III-depleted tubulin in the presence of taxol was enhanced compared to unfractionated tubulin. The critical concentration of unfractionated tubulin in the presence of 10 microM taxol is 0.4 mg/ml, while the critical concentration of beta III-depleted tubulin is 0.16 mg/ml. At different concentration of taxol, the assembly of beta III-depleted tubulin is increased relative to that of unfractionated tubulin and reaches the maximum at about a 1:1 ratio of tubulin and taxol. The assembly of unfractionated tubulin and beta III-depleted tubulin has also been studied by electron microscopy. After 2 minutes at 37 degrees C, unfractionated tubulin assembly in the presence of 10 microM taxol results only in ribbon-like and ring structures; there are no visible microtubules. By 5 minutes, microtubules appear and increase in length. The assembly of beta III-depleted tubulin in the presence of 10 microM taxol occurs more quickly. In contrast to the case with unfractionated tubulin, beta III-depleted tubulin assembles within 2 minutes into microtubules which increase in length with time. At 30 minutes, microtubules assembled from beta III-depleted tubulin are shorter than the microtubules assembled from unfractionated tubulin. There is no visible difference between the microtubules assembled from unfractionated tubulin and beta III-depleted tubulin. Taxol-induced beta III-depleted tubulin assembly is more resistant to the inhibiting effect of podophyllotoxin and colchicine. It is also less sensitive to the inhibiting effect of cold temperature.

[Study on degradation of phenols in water]

The degradation of phenols in water and the effects of microbiolism, pH and dissolved oxygen (DO) on the degradation were investigated. The results showed that the degradation of phenols in water was mainly that of biochemistry, which depends on the existence of microbiolism. The most suitable pH for the degradation was 6 to 9, and no effects of DO on it were found. The accustomization of microbiolism with phenols would accelerate the degradation.

Epstein-Barr virus (EBV) in enteropathy-associated T-cell lymphoma (EATL)

Using Southern hybridization analysis, we have detected the Epstein-Barr virus (EBV) genome in 36 per cent (4/11) of enteropathy-associated T-cell lymphoma (EATL), a frequency much higher than that seen in nodal T-cell lymphomas in which we were able to show EBV DNA in only 3 per cent (1/30) of the cases examined. Using a terminal fragment probe, monoclonal proliferation of EBV in infected cells was demonstrated in three of the four EBV-positive EATL cases (in one case, insufficient signal prevented the determination of EBV clonality). The EBV genome and an early transcript, EBER1, were identified in tumour cells by in situ hybridization. Expression of latent membrane protein (LMP) was detected in two EBV DNA/RNA-positive EATL cases. In view of the known oncogenic properties of EBV and the putative central role of LMP in EBV-induced cell immortalization, the results of this study suggest that the virus may play an aetiological role in the pathogenesis of EATL.

Elemental diet-induced bacterial translocation can be hormonally modulated

BACKGROUND

The authors have previously documented that feeding mice an elemental diet resulted in bacterial translocation (BT) that could be prevented by the provision of dietary fiber. To test whether the protective effect of fiber was related to the stimulation of trophic gut hormones, the effects of sandostatin and bombesin were tested.

METHODS

Mice fed either chow or the elemental diet were stratified into several groups and the ability of bombesin (10 micrograms/kg, tid) or sandostatin (100 micrograms/kg bid) to modulate BT was examined. After 14 days, mice were sacrificed and BT, cecal bacterial population levels, mucosal protein, and small bowel weight was measured. Segments of the ileum and jejunum were examined histologically.

RESULTS

Incidence of elemental diet-induced BT (75%) was reduced by fiber (9%) or the administration of bombesin (13%) (p < 0.01). Although sandostatin did not promote BT in chow-fed mice, it reversed the protective effect of fiber on BT (75%) (p < 0.01).

CONCLUSION

Elemental diet-induced bacterial translocation can be modulated hormonally and the beneficial effects of fiber on diet-induced BT appears to be hormonally mediated.

(CT)n (GA)n repeats and heat shock elements have distinct roles in chromatin structure and transcriptional activation of the Drosophila hsp26 gene

Previous analysis of the hsp26 gene of Drosophila melanogaster has shown that in addition to the TATA box and the proximal and distal heat shock elements (HSEs) (centered at -59 and -340, relative to the start site of transcription), a segment of (CT)n repeats at -135 to -85 is required for full heat shock inducibility (R.L. Glaser, G.H. Thomas, E.S. Siegfried, S.C.R. Elgin, and J.T. Lis, J. Mol. Biol. 211:751-761, 1990). This (CT)n element appears to contribute to formation of the wild-type chromatin structure of hsp26, an organized nucleosome array that leaves the HSEs in nucleosome-free, DNase I-hypersensitive (DH) sites (Q. Lu, L.L. Wallrath, B.D. Allan, R.L. Glaser, J.T. Lis, and S.C.R. Elgin, J. Mol. Biol. 225:985-998, 1992). Inspection of the sequences upstream of hsp26 has revealed an additional (CT)n element at -347 to -341, adjacent to the distal HSE. We have analyzed the contribution of this distal (CT)n element (-347 to -341), the proximal (CT)n element (-135 to -85), and the two HSEs both to the formation of the chromatin structure and to heat shock inducibility. hsp26 constructs containing site-directed mutations, deletions, substitutions, or rearrangements of these sequence elements have been fused in frame to the Escherichia coli lacZ gene and reintroduced into the D. melanogaster genome by P-element-mediated germ line transformation. Chromatin structure of the transgenes was analyzed (prior to gene activation) by DNase I or restriction enzyme treatment of isolated nuclei, and heat-inducible expression was monitored by measuring beta-galactosidase activity. The results indicate that mutations, deletions, or substitutions of either the distal or the proximal (CT)n element affect the chromatin structure and heat-inducible expression of the transgenes. These (CT)n repeats are associated with a nonhistone protein(s) in vivo and are bound by a purified Drosophila protein, the GAGA factor, in vitro. In contrast, the HSEs are required for heat-inducible expression but play only a minor role in establishing the chromatin structure of the transgenes. Previous analysis indicates that prior to heat shock, these HSEs appear to be free of protein. Our results suggest that GAGA factor, an abundant protein factor required for normal expression of many Drosophila genes, and heat shock factor, a specific transcription factor activated upon heat shock, play distinct roles in gene regulation: the GAGA factor establishes and/or maintains the DH sites prior to heat shock induction, while the activated heat shock factor recognizes and binds HSEs located within the DH sites to trigger transcription.

Functional studies of Alzheimer's disease tau protein

In vitro assays were used to monitor and compare the kinetic behavior of bovine tubulin polymerization enhanced by tau proteins isolated from Alzheimer's disease (AD) and nondemented (ND) age-matched control brains. Tau from AD cases induced slower polymerization and a steady state turbidity value approximately 50% of that stimulated by tau from control cases. Tau from the most severe AD case was least effective at promoting polymerization. Dark-field light microscopy of the control samples revealed abundant microtubule formation and many microtubule bundles. Microtubule assembly was observed in AD samples as well, but bundling was not obvious. These results were confirmed by negative-stain electron microscopy. Morphological analysis showed that AD tau-induced microtubules were longer than control microtubules. Furthermore, our initial results suggest that the reduction of AD tau activity is correlated with neurofibrillary pathology in AD brains. Earlier reports indicated that AD tau is modified by phosphorylation (Grundke-Iqbal et al., 1986; Wood et al., 1986; Iqbal et al., 1989; Brion et al., 1991a,b; Lee et al., 1991). Our results support the hypothesis that tau modification compromises its function by altering its ability to nucleate and bundle microtubules.

Characterization of fluorescently derivatized bovine tau protein and its localization and functions in cultured Chinese hamster ovary cells

Bovine brain tau protein was tagged with the fluorescent dye 5 (and 6)-carboxyx-rhodamine-succinimidyl ester and the functional properties of the fluorescent analog were tested in vitro by kinetic measurement and SDS gel electrophoresis. X-rhodamine tau was competent to bind to microtubules and promote microtubule assembly in vitro. Labeled tau was further characterized by microinjection of cultured Chinese hamster ovary (CHO) cells to study its intracellular distribution and potential new functions. X-rhodamine tau incorporated rapidly into centrosomes within seconds after microinjection. It distinctly labeled the microtubule network as early as 5 to 10 minutes following miroinjection. In addition, X-rhodamine tau was transported into the nucleus and labeled the nucleolus specifically. Double labeling of the injected cells with DiC6(3) indicated that in some cases, fluorescent tau may associate with the endoplasmic reticulum. The concentrations of injected X-rhodamine tau ranged from 1.7 to 5.0 mg/ml, yet distinct bundling of microtubules was not observed. Studies of nocodazole effects on the microtubules established that X-rhodamine tau stabilized microtubules against depolymerization conditions. We conclude that this fluorescent analog of tau is associated with microtubules, the nucleolus, and other microtubule-related structures in living cells, and is competent to stabilize microtubules against microtubule depolymerizing drug treatment. This approach provides a useful model system for the study of modified tau in neurodegenerative disease.

[A carboxylated latex agglutination test for the serological diagnosis of human and animal brucellosis]

A carboxylated latex agglutination test was developed for detecting antibodies in sera of human and animals with Brucellosis. The latex was chemico-linked with B. melitensis 16M extracted with 5% NaCl. Comparing with physico-sorbent latex antigens in detecting antibodies in sera of human and animals with Brucellosis, the chemico-linked latex is more stable, more specific and more sensitive. In addition, preparation of chemico-linked latex and some factors affecting the result of the test were also described in the paper.

Promoter sequence containing (CT)n.(GA)n repeats is critical for the formation of the DNase I hypersensitive sites in the Drosophila hsp26 gene

We have analyzed P-element-transformed lines carrying hsp26/lacZ transgenes with various deletions and substitutions within the Drosophila melanogaster hsp26 promoter region in order to identify the sequences required for the formation of the DNase I hypersensitive sites (DH sites). DH sites are generally found associated with promoters and enhancer elements of active and inducible eukaryotic genes, and are thought to be nucleosome-free regions of DNA that interact with regulatory proteins and the transcriptional machinery. There are two major DH sites located within the promoter region of the hsp26 gene, centered at -50 and at -350 (relative to the hsp26 transcription start site). The sequences from -135 to -85, which contain (CT)n.(GA)n repeats, contribute significantly to the formation of the DH sites in the hsp26 promoter region. Deletion or substitution of this (CT)n region drastically reduces the accessibility of the DNA at these sites to DNase I. This reduction in accessibility was quantified by measuring the susceptibility of the DNA within nuclei to cleavage at a restriction site within the DH site. In addition to the (CT)n region and the promoter at -85 to +11 (region P), one of two other regions must be present for effective creation of the DH sites: sequences between -351 and -135 (region A), or sequences between +11 and +632 (region D). Disruption of the wild-type chromatin structure, as assayed by the loss of accessibility to the DH sites, is correlated with a decrease in inducible transcriptional activity, even when the TATA box and heat shock regulatory elements are present in their normal positions.

Short chain collagens in sponges are encoded by a family of closely related genes

Two previously described sponge cDNAs, EmC4 and C23, respectively encoding a short chain collagen and a fibrillar collagen, were used to characterize collagen gene families in a freshwater sponge. EmC4 detected several clones when used to screen a cDNA library. Two overlapping clones, EmC13 1 and 2, were sequenced and appeared highly homologous to EmC4. Contrarily to C23, EmC4 hybridized with 10-12 fragments of genomic DNA digested with restriction endonucleases and detected 10 times more positive clones than C23 when used to screen a genomic library. The genomic clone G41 contained two closely related genes, COLNF13, corresponding to EmC13 and COLNF6. Partial characterization of COLNF13 revealed two partial exons and four complete exons of 153, 219, 207, and 144 base pairs, with split glycine codons at their boundaries. The deduced encoded protein is a short chain collagen containing two uninterrupted collagenous domains of 66 and 171 amino acids and non-collagenous domains. A characterized 207-base pair exon of COLNF6 is 77% identical with the comparable COLNF13 exon. In situ hybridization using EmC4 cDNA and electron microscopy suggested that the cells expressing these genes were secreting spongin, a non-fibrillar, surface collagen of these sponges.

Hormonal regulation of cytochrome oxidase subunit messenger RNAs in rat Sertoli cells

Using differential hybridization to screen a rat Sertoli cell cDNA library for hormonally regulated gene products, we isolated a clone, designated 13-10, which contained a 1.0-kilobase insert and hybridized to a 1.7-kilobase message in total testis, Sertoli cells, and peritubular cells. This mRNA was decreased relative to untreated control levels in total testicular RNA from hypophysectomized rats, but was increased by FSH treatment begun on the day of hypophysectomy. FSH caused a transient rise in 13-10 mRNA at 24 h in cultured Sertoli cells. There was no comparable rise in beta-actin RNA or the RNA/DNA ratio at this time, suggesting that the effect on 13-10 was specific. Testosterone had no effect at any time interval studied. The 13-10 mRNA was not increased in peritubular cells treated in vitro with FSH or testosterone. Sequence analysis of 13-10 revealed more than 99% homology with a portion of the sequence of rat liver cytochrome oxidase subunit I (COX I). The clone included 58% of the open reading frame of COX I as well as that for the adjacent Ser-tRNA. COX I is a mitochondrial gene, and Southern analysis confirmed 13-10 sequence in testicular mitochondrial DNA. In addition to FSH, forskolin and (Bu)2cAMP also increased COX I steady state mRNA in Sertoli cells (3.8-, 4.1-, and 9.2-fold, respectively). (Bu)2cAMP increased mRNA for other mitochondrial gene products, COX subunit II and 16S rRNA (6.9- and 5.4-fold, respectively), whereas the smaller effects elicited by forskolin and FSH were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Oral-TPN-induced bacterial translocation and impaired immune defenses are reversed by refeeding

Although certain defined diets have been shown to promote bacterial translocation (BT), the ability to reverse diet-induced BT has not previously been investigated. Furthermore, little is known about the effects of defined diets on host immune defenses. To address these questions, we measured BT and immune reactivity in rats fed a normal diet or enteral elemental (ORAL-TPN) diet. After 7 days on the elemental or normal diet, the rats were killed, and BT and mitogen responsiveness to concanavalin A and phytohemagglutinin were measured. In separate experiments, the effects of these diets on in vivo host defenses was measured with a Staphylococcus aureus abscess model. Additional experiments were performed to determine the time required to reverse ORAL-TPN-induced BT and impairment of host immune defenses by reinstituting normal feedings. Administration of the ORAL-TPN diet for 7 days was associated with BT to the mesenteric lymph node complex of all animals, decreased blastogenic response of blood and splenic lymphocytes to mitogens, and decreased ability to control an in vivo infectious challenge with S. aureus. Each of the derangements was reversed by the reinstitution of normal feedings. In summary, the enteral administration of an elemental diet for 7 days is associated with disruption of the gut microflora, BT, and the development of an immunocompromised state, all of which can be reversed by refeeding the animals a normal diet.

An Improved Synthesis, Molecular-Structure, and Properties of 1,4-Dihydro-Dicyclopropa[b,g]naphthalene

A marked improvement in the preparation of 1,4-dihydrodicyclopropa[ b,g ]naphthalene (4) from isotetralin (7) has been achieved by selecting conditions which avoid the unwanted olefin (12). The easily available dicycloproparene (4) has C2h symmetry in the crystal lattice with the space group P21/n. The geometry is readily rationalized by the concept of 'bent bonds' that are also suggested by X-X difference electron density maps. Cheletropic biaddition of dichlorocarbene to (4) provides the dicyclobutanaphthalenes (15) and (16). Attempted Petersen olefination to mono- and di-alkylidene derivatives, e.g. (21) and (22), is foiled by a reluctance of (4) to provide an easily interceptible anion.

[Comparative studies on antifertility mechanism and toxicology of Tripterygium wilfordii monomer T4 and gossypol]

Inhibition of spermatogenesis and turnover of basic nuclear protein in late elongated spermatids of rat testis by Tripterygium wilfordii monomer T4 was more obvious than that by gossypol. Clustered positive deposits of gamma-GT, ALP reaction were found in the inner edges of epididymal epithelium. Head and tail separation, mid-piece coiling and axial fiber dislocation of epididymal spermatozoa in T4 treated rats were more obvious than those of gossypol-treated rats. Mitochondrial LDH, LDH-X and MDH were also found to be inhibited by T4. T4 did not significantly affect enzyme activities in kidney and liver, though it did cause slight changes. Effects of T4 on the chief rat organs were milder than those of gossypol, except for a more obvious antifertility effect. The authors suggest that T4 may be developed into an ideal male contraceptive.