Dairy cattle with bovine leukaemia virus RNA show significantly increased leukocyte counts

Infection with bovine leukaemia virus (BLV), a retrovirus, causes dysfunction of the immune system and can have a marked economic impact on dairy industries due to decreased milk production and reduced lifespan in affected dairy cattle. The presence of proviral DNA has been the major diagnostic indicator of BLV infection. However in the course of BLV infection, the viral genome can be dormant, without detectable gene expression, resulting in limited impact on infected animals. At present, there is limited knowledge regarding haematological indices in dairy cattle that could indicate activation of the BLV genome and suggest reactivated BLV infection. In this study, BLV infection and BLV genome reactivation were evaluated based on the presence of BLV DNA and BLV env gene transcripts, respectively. BLV RNA transcription was confirmed. Among 93 whole blood samples obtained from asymptomatic dairy cattle, the prevalence of BLV proviral DNA and transcripts was 93.5% (n = 87/93) and 83.9% (n = 78/93), respectively. Between groups with and without BLV, the mean counts of white blood cells and lymphocytes in whole blood were significantly associated with the presence of BLV RNA (P < 0.05), but not with BLV proviral DNA. These results shed light on the activation status of the BLV genome and should be taken into account when evaluating the possible impact of BLV on cattle.

Correlation of expression of pro-apoptotic proteins bax and bak with lymph node metastasis in colonic adenocarcinoma

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Background: Colon cancer has been associated with disturbances in the regulation of apoptosis. Down regulation of Bax and Bak, members of the Bcl-2 family, are associated with tumor metastasis. Here we investigate how these two pro-apoptotic markers correlate with lymph node (LN) metastasis in colonic adenocarcinoma (CA). Methods: Paraffin-embedded sections from 100 cases of CA were constructed in tissue microarrays and subjected to immunohistochemistry (IHC) using the ABC method and antibodies for Bax and Bak. The IHC score is the product of intensity and percentage of positively stained cells, and ranged between 0 and 9. The total scores were divided into categories of “2 or less” and “3 or more.” These were than correlated with LN metastasis. Results: For Bax, 88 tumors were available while Bak was present in 100 tumors. In scoring Bax, 67 tumors had a score of ≤2 and 21 had a score of ≥3. Within the ≤2 category, 23 of 67 (34%) tumors had no LN metastases while 15 of 21 (71%) in the ≥3 category had no metastasis (p= 0.0029). For Bak staining, 23 had a score of ≤2 and 77 had a score of ≥3. Five of 23 (22%) tumors with a score ≤2 had no metastases and 35 of 77 (46%) with score ≥3 had no metastases (p= 0.0427). The LOGISTIC Procedure was used to show that a patient with a ≥3 Bax score has a 4.78 times odds ratio (95% C.I.: 1.64- 13.98) of having no metastases while a patient with a ≥3 Bak score has a 3 times odds ratio (95% C.I.: 1.01- 8.90) of having no metastases. Conclusions: We show correlation of the pro-apoptotic proteins Bax and Bak with decreased lymph node metastasis in CA. The findings suggest a role for these markers in predicting stage and patient survival in colonic adenocarcinoma.

No significant financial relationships to disclose.

cAMP generation inhibits inositol 1,4,5-trisphosphate binding in rabbit tracheal smooth muscle

Agonist-induced airway contraction involves the generation and subsequent binding of the phosphoinositide-derived second messenger, inositol 1,4,5-trisphosphate [Ins(1,4,5)P3], to its Ca(2+)-mobilizing intracellular receptor. To the extent that regulatory cross-talk is known to exist between different signal transduction pathways, the present study examined whether activation of the adenosine 3',5'-cyclic monophosphate (cAMP)/protein kinase A (PKA) pathway induces altered binding of Ins(1,4,5)P3 to its receptor in membrane homogenates of rabbit tracheal smooth muscle (TSM). In control TSM, monophasic binding curves provided mean +/- SE values for Ins(1,4,5)P3 receptor density (Bmax) and binding affinity (Kd) amounting to 940 +/- 43 fmol/mg protein and 10.7 +/- 1.2 nM, respectively. Relative to control, binding of [3H]Ins(1,4,5)P3 was significantly reduced in paired TSM separately treated with isoproterenol, forskolin, or dibutyryl-cAMP. Ins(1,4,5)P3 binding was inhibited to a level averaging 60% of control binding by maximal concentrations of each agonist, an effect attributed to a reduction in Ins(1,4,5)P3 binding sites rather than altered ligand affinity. Collectively, these findings demonstrate that activation of the cAMP-dependent signaling pathway is associated with inhibition of Ins(1,4,5)P3 receptor binding and implicate a novel mechanism of action of beta-adrenergic agents in preventing and/or reversing airway contraction.

Maturation of inositol 1,4,5-trisphosphate receptor binding in rabbit tracheal smooth muscle

The mechanisms underlying maturational changes in agonist-mediated airway contractility remain to be identified. Since the signal transduction process coupled to airway contraction involves the Ca(2+)-mobilizing action of the second messenger, inositol 1,4,5-trisphosphate [Ins(1,4,5)P3], the present study examined 1) whether Ins(1,4,5)P3 binding to its intracellular receptor varies with age in rabbit tracheal smooth muscle (TSM), and 2) whether Ca2+ exerts a modulatory effect on Ins(1,4,5)P3 receptor binding that is age dependent. [3H]Ins(1,4,5)P3 binding was assayed in crude TSM membrane preparations isolated from 2-week-old and adult rabbits. Monophasic Scatchard plots were obtained, reflecting a single binding site, with Hill coefficients of 0.988-0.996. The mean +/- SE values for receptor density (Bmax) and binding affinity [i.e., the dissociation constant (Kd)] were similar in the adult and immature tissues, wherein Bmax = 211 +/- 6 238 +/- 60 fmol/mg protein, respectively; and Kd = 14.1 +/- 0.2 and 11.6 +/- 1.2 nM, respectively. Addition of Ca2+ (10(-8)-10(-3) M) significantly modulated Ins(1,4,5)P3 binding, with opposing maturational effects. In adult tissues, Ca2+ produced dose-dependent inhibition of Ins(1,4,5)P3 binding to 59.5% control, whereas Ins(1,4,5)P3 binding in response to Ca2+ was significantly enhanced in the 2-week-old tissues to 183% control. Collectively, these observations demonstrate that the inherent basal binding characteristics of the Ins(1,4,5)P3 receptor are similar in maturing TSM, but that Ca2+ exerts opposite modulatory actions on Ins(1,4,5)P3 receptor binding in immature and adult tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of endothelin 1 in regulating rabbit airway contractility

Endothelin 1 (ET-1) is a potent vasoconstrictor peptide recently isolated from vascular endothelial cells. Because its role and mechanisms of action in regulating airway contractility remain to be identified, we examined the contractile effects of ET-1 in isolated rabbit tracheal smooth muscle (TSM) segments. In TSM under passive tension, ET-1 elicited dose-dependent contractions with a mean +/- SE -log 50% of maximal response value of 7.82 +/- 0.13 vs. a value of 5.61 +/- 0.07 -log M for acetylcholine (ACh). In TSM half-maximally contracted with ACh, however, ET-1 exerted dual and opposing contractile effects. Lower doses of ET-1 (less than or equal to 10(-9) M) produced a 74.2 +/- 16.6% decrease in active TSM tension. This relaxant response to ET-1 was associated with an accelerated accumulation of prostaglandin (PG) I2 and PGE2 and was attenuated by cyclooxygenase inhibition with indomethacin (10(-5) M). The combination of indomethacin and removal of the airway epithelium completely inhibited the TSM relaxant response to ET-1. In contrast, higher doses of ET-1 (greater than 10(-9) M) induced airway contractions that were attenuated by the Ca2+ channel blockers nifedipine (10(-5) M) and diltiazem (10(-5) M) and ablated in Ca2(+)-free buffer. Moreover, ET-1-induced TSM contractions were inhibited by the protein kinase C (PK-C) antagonists 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine, and staurosporine.(ABSTRACT TRUNCATED AT 250 WORDS)

Bilateral mesiodentes of identical twins--a case report

A pair of identical 10-year-old Chinese twins with bilateral mesiodentes of opposite orientation are presented. Three mesiodentes were conical and impacted, while the other one had erupted and was incisiform in shape. All roots of the mesiodentes were completely formed. Intrapair twin comparison showed a high degree of genetically determined concordance, with minor differences subject to environmental influences. The prevalence of mesiodens and rate of monozygotic twins in various ethnic groups are reviewed. Mirror image traits and verification of monozygocity in identical twins are also discussed.

[Marginal leakage of glass ionomer as filling material for proximal decay in endodontic treatment]

The primary purpose of sealing proximal tooth defects during endodontic treatment is to prevent fluid, organic or bacterial contamination of the root canal system. At times, glass ionomers are used to restore proximal tooth defects between appointments, and after the root canal therapy. The purpose of this study was to evaluate the sealing ability of glass ionomers in teeth having proximal defects during root canal therapy. Sixty lower molars were extracted and prepared with standard endodontic access procedures. The mesial wall was then removed to mimic a proximal defect, and the tooth was filled with a glass ionomer in various thicknesses--0.8, 1.2 and 1.5 mm, respectively. After thermocycline treatment, all of the teeth were partially immersed in a 1% methylene blue dye for two weeks. During this period, the glass ionomer was directly observed to determine if any marginal leakage occurred. The glass ionomer was unacceptable if the dye penetrated to the interior wall of the pulp chamber. If not, it was classified as acceptable. The results indicated that dye penetration or leakage was least likely to occur in a 1.5 mm glass ionomer group.

Effects of chronic treatment with various neuromuscular blocking agents on the number and distribution of acetylcholine receptors in the rat diaphragm

1. Acetylcholine receptors in the end-plate and non-end-plate areas of the rat diaphragm, after treating the animal with hemicholinium-3, alpha- or beta-bungarotoxin in vivo, were studied by their specific binding of labelled alpha-bungarotoxin. 2. Subcutaneous injection of maximum tolerable doses of hemicholinium-3 (50 mug/kg) twice daily for 7 days increased the number of extrajunctional receptors along the whole length of muscle fibre, the approximate density of receptor on muscle membrane being increased from 6/mum2 in normal diaphragm to 38/mum2. Junctional receptors were also increased in number from 2-2 x 10(7) to 2-8 x 10(7) per end-plate. 3. Five days after denervation, there were approximately 153/mum2 extrajunctional receptors and the number of receptors on the end-plate was increased by 220%. 4. Intrathoracic injection of beta-bungarotoxin (50 mug/kg) also increased the density of extrajunctional receptors to approximately 104/mum2, and the number of end-plate receptors by 140% in 5 days. The neuromuscular block was extensive and prolonged. 5. [3H]Diacetyl alpha-bungarotoxin (150 mug/kg) injected into thoracic cavity caused complete neuromuscular blockade for 12 hr. At 24 hr, the synaptic transmission was restored in 80% of the junctions with less than 10% end-plate receptors freed, whereas the safety factor for transmission in normal diaphragm was 3-5. Extrajunctional receptors appeared to increase within 24 hr. This increase continued despite the restoration of neuromuscular transmission, and the receptor density at 5 days was approximately 5l/mum2. The number of junctional receptors, however, was not increased. Repeated injection of the toxin gave the same result. 6. It is concluded that the numbers of junctional and extrajunctional acetylcholine receptors are regulated in different ways, and the possible role of acetylcholine is discussed.

Influence of chronic neostigmine treatment on the number of acetylcholine receptors and the release of acetylcholine from the rat diaphragm

1. Rats were treated twice daily for 7 days with neostigmine and the diaphragm was isolated for study of its acetylcholine content, release upon nerve stimulation and the number of receptors in the end-plate.2. While the content of total acetylcholine was unchanged, the release of acetylcholine on stimulation with trains of 500 pulses at 100 Hz every 20 sec was reduced by about 50%. Five days after the end of neostigmine treatment the release of acetylcholine recovered to normal.3. The total number of acetylcholine receptors in the end-plate as measured from the binding of N, O-di[(3)H]acetyl alpha-bungarotoxin was reduced from 2.1 x 10(7) to 1.2 x 10(7) per end-plate.4. The above-mentioned changes are not due to acute pharmacological effects of neostigmine, nor to an immediate effect of cholinesterase inhibition but presumably due to chronic accumulation of acetylcholine at the neuromuscular junction.

N,O-di and N,N,O-tri ( 3 H) acetyl -bungarotoxins as specific labelling agents of cholinergic receptors

1. alpha-Bungarotoxin isolated from the venom of Bungarus multicinctus was acetylated with [(3)H] acetic anhydride and N-[(3)H] acetyl imidazole. Tri-N-acetyl and hexa-N-acetyl derivatives were obtained from the former, and N,O-di, N,N,O-tri and N,N,N,O-tetraacetyl derivatives from the latter reaction, respectively.2. There were parallel decreases in both neuromuscular blocking action in the phrenic nerve-diaphragm preparation of rats and depression of acetylcholine response of the rectus abdominis muscle of frogs with increased acetylation. Also, a parallel but greater decrease of toxicity in mice was found.3. N,O-Di and N,N,O-triacetyl toxins were localized mostly in the motor endplate region of the rat diaphragm, whereas a slight nonspecific binding along the whole muscle fibre in addition to the peak in the endplate region was observed with N,N,N,O-tetraacetyl and tri-N-acetyl toxins. In contrast, there was a marked nonspecific binding with hexa-N-acetyl toxin and no peak was observed at the endplate zone.4. The specific binding was saturable and irreversible. The number of toxin-receptive sites in one endplate was 1.9-2.2 x 10(7) for all of the labelled toxins irrespective of their potency.5. (+)-Tubocurarine protected effectively against the binding as well as the irreversible neuromuscular blocking effect of the toxins.6. Denervation of the rat diaphragm caused an increase of toxin-receptive sites beginning from the endplate zone at 1-2 days and then along the whole muscle fibre, reaching the maximum at about 18 days. The total receptive sites increased by about 30-fold.7. The significance of the findings is discussed and it is concluded that N,O-di and N,N,O-tri-[(3)H] acetyl alpha-bungarotoxins are specific and irreversible labelling agents for the cholinergic receptors of skeletal muscle.

Role of cardiotoxin and phospholipase A in the blockade of nerve conduction and depolarization of skeletal muscle induced by cobra venom

1. The effects of phospholipase A (PhA), cardiotoxin (CTX) and neurotoxin (cobrotoxin) isolated from Formosan cobra (Naja naja atra) venom on conduction of the rat phrenic nerve and membrane potential of the rat diaphragm were studied.2. Phospholipase A, lysolecithin and cobrotoxin were without effect on the axonal conduction. Cardiotoxin was the only active agent in cobra venom, but it was less potent than the crude venom.3. The blocking action of cardiotoxin was markedly accelerated by the simultaneous administration of phospholipase A. However, the minimum effective concentration of cardiotoxin (100 mug/ml), was not decreased by phospholipase A. Pretreatment of the nerve with phospholipase A, followed by washout, did not alter the activity of cardiotoxin.4. Cardiotoxin (3 mug/ml) completely depolarized the membrane of superficial muscle fibres within 60 min, being 3 times more potent than the crude venom. Phospholipase A, on the other hand, needed a dose 30 times higher and a prolonged period of incubation to induce depolarization of similar extent. Cobrotoxin was without effect on membrane potentials.5. CaCl(2) (10 mM) effectively antagonized the nerve blocking as well as the depolarizing effect of the crude venom, cardiotoxin or cardiotoxin plus phospholipase A. By contrast, the slow depolarizing effect of phospholipase A was enhanced by high concentrations of calcium.6. Cardiotoxic fractions of Indian cobra venom affected both nerve conduction and diaphragm membrane potential in exactly the same way as cardiotoxin. Toxin A of the same venom was without effect.7. It is concluded that the active agent in cobra venoms either on axonal conduction or on muscle membrane is cardiotoxin. The synergistic effect of phospholipase A on cardiotoxin appears to be due to acceleration rather than potentiation of its action. The mechanism of action of cardiotoxin and its synergism by phospholipase A are discussed.