Sensitization of TRPV1 by protein kinase C in rats with mono-iodoacetate-induced joint pain

OBJECTIVE

To assess the functional changes of Transient receptor potential vanilloid 1 (TRPV1) receptor and to clarify its mechanism in a rat mono-iodoacetate (MIA)-induced joint pain model (MIA rats), which has joint degeneration with cartilage loss similar to osteoarthritis.

METHODS

Sensitization of TRPV1 in MIA rats was assessed by transient spontaneous pain behavior induced by capsaicin injection in knee joints and electrophysiological changes of dorsal root ganglion (DRG) neurons innervating knee joints in response to capsaicin. Mechanisms of TRPV1 sensitization were analyzed by a newly developed sandwich enzyme-linked immunosorbent assay that detects phosphorylated TRPV1, followed by functional and expression analyses of protein kinase C (PKC) in vivo and in vitro, which involves TRPV1 phosphorylation.

RESULTS

Pain-related behavior induced by intra-articular injection of capsaicin was significantly increased in MIA rats compared with sham rats. In addition, capsaicin sensitivity, evaluated by capsaicin-induced inward currents, was significantly increased in DRG neurons of MIA rats. Protein levels of TRPV1 remained unchanged, but phosphorylated TRPV1 at Ser800 increased in DRG neurons of MIA rats. Phosphorylated-PKCɛ (p-PKCɛ) increased and co-localized with TRPV1 in DRG neurons of MIA rats. Capsaicin-induced pain-related behavior in MIA rats was inhibited by intra-articular pretreatment of the PKC inhibitor bisindolylmaleimide I. In addition, intra-articular injection of the PKC activator phorbol 12-myristate 13-acetate increased capsaicin-induced pain-related behavior in normal rats.

CONCLUSION

TRPV1 was sensitized at the knee joint and at DRG neurons of MIA rats through PKC activation. Thus, TRPV1 sensitization might be involved in chronic pain caused by osteoarthritis.

A novel method for assessing bladder-related pain reveals the involvement of nerve growth factor in pain associated with cyclophosphamide-induced chronic cystitis in mice

BACKGROUND

Pain is a prominent feature of interstitial cystitis/painful bladder syndrome (IC/PBS), but the underlying mechanisms are not fully understood. There is a lack of well-characterized research tools, such as pain evaluation methods and experimental animal models, for investigating non-ulcerative cystitis. We developed a novel method for evaluating bladder pain in mice with cyclophosphamide (CYP)-induced cystitis.

METHODS

Cystitis was produced by a single intraperitoneal injection of CYP (300 mg/kg) or repeated injections of CYP (150 mg/kg once daily for 4 days). Blunt stimulation with a cotton probe was applied to the abdominal region, and the thresholds for withdrawal responses were measured quantitatively using an anaesthesiometer.

RESULTS

The single injection of CYP provoked acute cystitis with severe bladder inflammation in mice. In these mice, we could detect an increased sensitivity to blunt stimulation, which was abolished by intravesical lidocaine. The stimulation induced phosphorylation of extracellular signal-regulated kinases in bladder-projecting sensory neurons. Chronic treatment with CYP produced persistent pain responses to the blunt stimulus. Although there were few signs of bladder inflammation in these mice, the concentration of nerve growth factor (NGF) was elevated in bladder tissue, and NGF antiserum inhibited the hypersensitivity.

CONCLUSIONS

The blunt probe method is useful for evaluating bladder pain signalling in mice, and revealed the involvement of an NGF-sensitive pain pathway in chronic cystitis pain. This assessment method may be useful for studying the pathophysiology of bladder pain and for developing therapeutic strategies for non-ulcerative IC/PBS in patients.

Circular muscle contraction in the mice rectum plays a key role in morphine-induced constipation

BACKGROUND

Although opioids induce intestinal muscle contraction and provoke constipation, the intestinal region(s) that contribute to the constipation have remained unclear. We report here a region-specific response of intestinal muscle contraction to morphine and its correlation with in vivo constipation.

METHODS

Regions of mice small and large intestines were dissected histologically and circular muscle contractile responses were measured using isometric transducers. Bead expulsion assays were performed to assess in vivo constipation.

KEY RESULTS

The strongest contraction in response to morphine was detected in the rectum. The distal and transverse colon also showed strong contractions, whereas weak responses were detected in the proximal colon, jejunum, and ileum. Regarding the sustainability of muscle contractions during morphine exposure, prolonged waves were detected only in the rectum, while the waves diminished gradually in other regions. To identify the mechanism(s) underlying this difference, we focused on nitric oxide synthase (NOS). In the distal colon, decreased contraction during morphine exposure was recovered by application of a NOS inhibitor (L-NAME), while a NOS substrate (L-arginine) enhanced contractile degradation. In contrast L-NAME and L-arginine modestly affected the sustained contraction in the rectum. To confirm the correlation with constipation, beads were inserted into the transverse colon, distal colon, or rectum after morphine administration and expulsion times were examined. Beads tended to stop at the rectum even when inserted in the deeper colonic regions.

CONCLUSIONS & INFERENCES

The rectum showed the greatest response to morphine in both in vitro and in vivo analyses, therefore it may play a key role for opioid-induced constipation.

[Coronary malperfusion of left main trunk due to localized dissection of the ascending aorta]

Case 1. Forty nine years woman was given a diagnosis of acute myocardial infarction. Coronary angiography and trans-esophageal echocardiography showed left main trunk dissection due to local aortic root dissection. We operated surgical repair at left main trunk by pericardium after percutaneous coronary intervention. Case 2. Forty nine years man was given a diagnosis of acute myocardial infarction caused by left main trunk dissection due to traumatic local aortic root dissection. We operated coronary artery bypass grafting after insertion of perfusion catheter to left main trunk for maintain coronary perfusion. Although local dissection of aortic aorta is relatively rare, it is potentially complicated with coronary malperfusion. We describe 2 success a cases of surgical treatment for local acute type A aortic dissection complicated with coronary malperfusion.

S-2474, a novel nonsteroidal anti-inflammatory drug, rescues cortical neurons from human group IIA secretory phospholipase A-induced apoptosis

The elevated level of group IIA secretory phospholipase A(2) (sPLA(2)-IIA) activity contributes to neurodegeneration in the cerebral cortex after ischemia. The up-regulation of cyclooxygenase-2 (COX-2) is also relevant to cerebral ischemia in humans. Studies of ischemia with COX-2 inhibitors suggest a clinical benefit. In the present study, we investigated effects of S-2474 on sPLA(2)-IIA-induced cell death in primary cultures of rat cortical neurons, which was established as an in vitro model of brain ischemia. S-2474 is a novel nonsteroidal anti-inflammatory drug (NSAID), which inhibits COX-2 and contains the di-tert-butylphenol antioxidant moiety. S-2474 significantly prevented neurons from undergoing sPLA(2)-IIA-induced cell death. S-2474 completely ameliorated sPLA(2)-IIA-induced apoptotic features such as the condensation of chromatin and the fragmentation of DNA. sPLA(2) also generated neurotoxic prostaglandin D(2) (PGD(2)) and free radicals from neurons before cell death. S-2474 significantly inhibited the sPLA(2)-IIA-induced generation of PGD(2). The present cortical cultures contained few non-neuronal cells, indicating that S-2474 affected neuronal survival directly, but not indirectly via non-neuronal cells. The inhibitory effect of S-2474 on COX-2 might contribute to its neuroprotective effect. In conclusion, S-2474 exhibits neuroprotective effects against sPLA(2)-IIA. Furthermore, the present study suggests that S-2474 may possess therapeutic potential for stroke via ameliorating neurodegeneration.

Haptic reproduction and interactive visualization of a beating heart for cardiovascular surgery simulation

This paper aims to achieve haptic reproduction and real-time visualization of a beating heart for cardiac surgery simulation. Unlike most forgoing approaches, the authors focus on time series datasets and propose a new framework for interactive simulation of active tissues. The framework handles both detection and response of collisions between a manipulator and a beating virtual heart. Physics-based force feedback of autonomous cardiac motion is also produced based on a stress-pressure model, which is adapted to elastic objects filled with fluid. Time series datasets of an adult man were applied to an integrated simulation system with a force feedback device. The system displays multi-dimensional representation of a beating heart and provides a basic training environment for surgical palpation. Finally, results of measurement and medical assessment confirm the achieved quality and performance of the presented framework.

Gas6 rescues cortical neurons from amyloid beta protein-induced apoptosis

Gas6, a product of the growth-arrest-specific gene 6, protects neurons from serum deprivation-induced apoptosis. Neuronal apoptosis is also caused by amyloid beta protein (Abeta), whose accumulation in the brain is a characteristic feature of Alzheimer's disease. Abeta induces Ca(2+) influx via L-type voltage-dependent calcium channels (L-VSCCs), leading to its neurotoxicity. In the present study, we investigated effects of Gas6 on Abeta-induced cell death in primary cultures of rat cortical neurons. Abeta caused neuronal cell death in a concentration- and time-dependent manner. Gas6 significantly prevented neurons from Abeta-induced cell death. Gas6 ameliorated Abeta-induced apoptotic features such as the condensation of chromatin and the fragmentation of DNA. Prior to cell death, Abeta increased influx of Ca(2+) into neurons through L-VSCCs. Gas6 significantly inhibited the Abeta-induced Ca(2+) influx. The inhibitor of L-VSCCs also suppressed Abeta-induced neuronal cell death. The present cortical cultures contained few non-neuronal cells, indicating that Gas6 affected the survival of neurons directly, but not indirectly via non-neuronal cells. In conclusion, we demonstrate that Gas6 rescues cortical neurons from Abeta-induced apoptosis. Furthermore, the present study indicates that inhibition of L-VSCC contributes to the neuroprotective effect of Gas6.

Group IB secretory phospholipase A(2)induces cell death in the cultured cortical neurons: a possible involvement of its binding sites

In primary cultures of rat cortical neurons, group IB secretory phospholipase A(2) (sPLA(2)-IB) induced cell death. In rat cortical membranes, there were high affinity binding sites of [125I]sPLA(2)-IB. The high-affinity binding sites were decreased by sPLA(2)-IB and anti-sPLA(2) receptor immunoglobulin G (anti-sPLA(2)R IgG). Furthermore, anti-sPLA(2)R IgG caused neuronal cell death in a concentration-dependent manner. The present study suggests that sPLA(2)-IB induces neuronal cell death via its high-affinity binding sites.

Increased pericardial fluid concentrations of the mature form of adrenomedullin in patients with cardiac remodelling

BACKGROUND

There is evidence that adrenomedullin has autocrine or paracrine activities that oppose cardiac remodelling. However, it remains unclear whether it exerts those local functions in heart failure patients.

OBJECTIVE

To investigate the relation between plasma and pericardial fluid concentrations of adrenomedullin and left ventricular haemodynamic variables.

DESIGN

Samples of plasma and pericardial fluid were obtained from 50 patients undergoing cardiac surgery. They were classified into two groups: group N (n = 27) with a left ventricular end diastolic volume index (LVEDVI) < or = 90 ml/m(2); and group R (n = 23) with LVEDVI > 90 ml/m(2). Plasma and pericardial fluid concentrations of total adrenomedullin (tAM) and mature adrenomedullin (mAM) were measured and related to the preoperative haemodynamic variables.

RESULTS

Pericardial fluid concentrations of mAM were much higher than the plasma concentration in both group N and group R (mean (SEM), 10.6 (1.7) v 3.3 (0.2) fmol/ml, p = 0.0001; and 21.2 (2.8) v 3.9 (0.3) fmol/ml, p < 0.0001, respectively). The ratio mAM/tAM in pericardial fluid was significantly higher than in plasma (0.56 (0.02) v 0.28 (0.02), p < 0.0001). Pericardial fluid concentrations of mAM, but not plasma concentrations, were significantly correlated with LVEDVI, left ventricular end systolic volume index, left ventricular ejection fraction, and left ventricular mass index (r = 0.60, 0.63, -0.54, and 0.47, respectively).

CONCLUSIONS

Raised pericardial fluid concentrations of mAM may reflect the actions of adrenomedullin as a local mediator against cardiac remodelling in patients with left ventricular dysfunction.

Haptic reproduction and interactive visualization of a beating heart based on cardiac morphology

A goal of this work is proposal and construction of simulation methods of haptic reproduction and interactive visualization of a beating heart in cardiovascular surgical training and education. The data for the beating heart model was obtained from ECG-gated 3D MRI of a normal volunteer. The elastic information was assumed as a uniform value with clinically experienced elasticity. Using a real-time 3D graphics and a haptic device, a simulation environment of the beating heart was designed and implemented. After the construction, some cardiovascular surgeons evaluated the implemented system. Its visualization and haptic expression were scored excellent, but some details in haptic interface were remained to be improved. Finally, for more realistic cardiovascular surgical simulation, future development of the method is discussed.

Left ventricular aneurysm repair in rats: structural, functional, and molecular consequences

OBJECTIVES

This study examined the effects of aneurysm repair in a rat model of myocardial infarction on functional indices and on the spatiotemporal distribution of cardiac contractile protein and natriuretic peptide messenger RNA.

METHODS

In a rat infarct model, expanded left ventricular aneurysms were plicated 4 weeks after infarction. At 30 weeks, transverse heart sections were taken at 4 levels (apex [level 1] through base [level 4]) and assessed by in situ hybridization histochemistry to determine regional messenger RNA levels of pre-pro-atrial natriuretic peptide, cardiac alpha-actin, skeletal alpha-actin, myosin light chain-2v, and beta-myosin heavy chain.

RESULTS

Rats with plicated left ventricular aneurysms had reduced left ventricular endocardial circumference (19%, P <.005), lower heart weight ratio (31%, P <.05), left ventricular end-diastolic pressures (51%, P <.05), and increased +/-dP/dt (34%-38%, P <.05). Cardiac messenger RNA levels of pre-pro-atrial natriuretic peptide were reduced in the septum (levels 2 and 3), and skeletal alpha-actin levels were reduced in the septum and left ventricular free wall of plicated rats (level 3). beta-Myosin heavy chain levels were markedly reduced in peri-infarct regions of the left ventricular free wall, septum, and right ventricle in plicated rats at level 4, whereas myosin light chain-2v levels were reduced at levels 2 and 4 in the left ventricular free wall and at level 4 in the right ventricle.

CONCLUSIONS

Plication of left ventricular aneurysm after infarction in the rat significantly reduced cardiac hypertrophy, improved cardiac function, and reduced the upregulation of pre-pro-atrial natriuretic peptide and both fetal and adult contractile protein isoforms associated with cardiac hypertrophy.

Outcome of geometric endoventricular repair in impaired left ventricular function

BACKGROUND

Traditionally, repair of left ventricular aneurysms has been limited to patients with large localized ventricular aneurysms. Repair of dyskinetic segments in the setting of poor left ventricular function is still contentious.

METHODS

Forty patients underwent geometric endoventricular repair, a new technique of ventricular aneurysm repair, over a 2-year period. Two groups of patients undergoing coronary artery bypass grafting (CABG) for left ventricular dysfunction in the same time period were reviewed. Group 1 comprised 23 consecutive patients who underwent geometric endo-ventricular repair along with CABGs, whereas group II consisted of 22 patients who underwent CABG alone.

RESULTS

The early mortality was 9.1% in group I (1 cardiac, 1 noncardiac) and 0 in group II (NS). New York Heart Association class was remarkably improved from 3.4 to 1.4 (p < 0.05) in group I and to a lesser extent in group II (3.7+/-0.5 versus 2.3+/-0.5). Diastolic dimension of left ventricle was significantly reduced from 5.6 cm to 4.4 cm (p < 0.05) in group I and virtually unchanged in group II. There was one late death in each of the groups.

CONCLUSIONS

This technique of geometric left ventricular aneurysm repair is useful in patients with dyskinetic segments and may help in reducing cardiac size.

Doc2alpha is an activity-dependent modulator of excitatory synaptic transmission

Doc2alpha is a synaptic vesicle-associated Ca2 + -binding protein. To study the role of Doc2alpha in synaptic transmission and modulation, we generated homozygous null Doc2alpha mutant mice. In the CA1 region of hippocampal slices in the mutant mice, excitatory synaptic responses evoked with prolonged 5 Hz stimulation showed a significantly larger frequency facilitation followed by a steeper depression than those in wild-type mice, whereas there was no difference in synaptic transmission at lower frequencies or in paired-pulse facilitation. These results suggest that Doc2alpha regulates synaptic transmission when high Ca2 + concentrations in the presynaptic terminal are sustained. Furthermore, the mutant mice showed impairment in long-term potentiation and passive avoidance task. Thus, Doc2alpha may regulate transmitter release during repetitive synaptic activation, thereby contributing to memory formation.

Interaction of Doc2 with tctex-1, a light chain of cytoplasmic dynein. Implication in dynein-dependent vesicle transport

Doc2 has one Munc13-interacting domain at the N-terminal region and two C2-like domains interacting with Ca2+ and phospholipid at the C-terminal region. Doc2 consists of two isoforms, Doc2alpha and -beta. Doc2alpha is specifically expressed in neuronal cells and implicated in Ca2+-dependent neurotransmitter release, whereas Doc2beta is ubiquitously expressed and its function is unknown. We show here that both Doc2alpha and -beta interact with rat tctex-1, a light chain of cytoplasmic dynein, in both cell-free and intact cell systems. Overexpression of the N-terminal fragment of Doc2 containing the tctex-1-interacting domain induces changes in the intracellular localization of cation-independent mannose 6-phosphate receptor and its ligand, cathepsin D, which are transported from trans-Golgi network to late endosomes. Overexpression of the C-terminal fragment containing two C2-like domains shows the similar effect, but to a lesser extent, whereas overexpression of full-length Doc2 or the C-terminal fragment of rabphilin3 containing two C2-like domains does not show this effect. Because dynein is a minus-end-directed microtubule-based motor protein, these results suggest that Doc2, especially Doc2beta, plays a role in dynein-dependent intracellular vesicle transport.

Role of the Doc2 alpha-Munc13-1 interaction in the neurotransmitter release process

Doc2alpha and Munc13-1 proteins are highly concentrated on synaptic vesicles and the presynaptic plasma membrane, respectively, and have been implicated in Ca2+-dependent neurotransmitter release. Doc2alpha interacts with Munc13-1 through the N-terminal region of Doc2alpha (the Mid domain; amino acid residues 13-37). Here we examine whether the interaction between Doc2alpha and Munc13-1 is required for Ca2+-dependent neurotransmitter release from intact neuron. A synthetic Mid peptide (the Mid peptide), but not a control mutated Mid peptide or a scrambled Mid peptide, inhibited the interaction between Doc2alpha and Munc13-1 in vitro. Introduction of the Mid peptide into presynaptic neurons of cholinergic synapses, formed between rat superior cervical ganglion neurons, reversibly inhibited synaptic transmission evoked by action potentials. In contrast, the control peptides did not inhibit synaptic transmission. This inhibitory effect depended on the presynaptic activity and was affected by extracellular Ca2+ concentrations. The onset of the Mid peptide effect was shortened when the neuron was stimulated at a higher frequency, and the inhibition was more potent at 1 mM Ca2+ than at 5.1 mM Ca2+. These results suggest that the Doc2alpha-Munc13-1 interaction plays a role in a step before the final fusion step of synaptic vesicles with the presynaptic plasma membrane in the evoked neurotransmitter release process.

[A case report of gastric perforation after coronary artery bypass grafting with right gastroepiploic artery]

A 71-year-old man, who had received coronary angioplasty to right coronary artery 1 year before, was admitted because of unstable angina. An urgent CABG was performed using the left internal thoracic artery and the right gastroepiploic artery. Coronary anastomosis was performed under ventricular fibrillation due to porcelain aorta. Seven days after surgery, abdominal pain was suddenly experienced. A chest X-P showed subphrenic free air. So an emergent laparotomy was performed, and a 2 x 2 cm gastric perforation was found on the anterior wall of the greater gastric curvature. Partial gastrectomy was performed. However, he unfortunately died on the 58th postoperative day for multiple organ failure. Pathological examination of the excised gastric wall revealed ischemic change, not ulcer. This gastric perforation was possibly caused by ischemia after harvesting the right gastroepiploic artery.

A novel brain-specific isoform of beta spectrin: isolation and its interaction with Munc13

Munc13 is a component of the neurotransmitter release machinery which is specifically expressed in brain. Munc13 interacts with Doc2 and syntaxin which are also implicated in the neurotransmitter release process. Here we isolated another Munc13-interacting molecule from a rat brain cDNA library by use of the yeast two-hybrid system, identified it to be a novel type of beta spectrin, and named it beta SpIII sigma 1. beta SpIII sigma 1 was specifically expressed in brain, where it was enriched in the synaptic vesicle and plasma membrane fractions. Because spectrin has been shown to interact with the actin cytoskeleton which is involved in the exocytotic process, the present results suggest that the Munc13-beta SpIII sigma 1 interactions play a role in neurotransmitter release.

Aortic valve replacement after previous coronary artery bypass grafting in a patient with antiphospholipid syndrome

We report a 55-year-old female patient with antiphospholipid syndrome secondary to systemic lupus erythematosus. The patient had undergone coronary artery bypass grafting for myocardial infarction due to left main trunk stenosis at the age of 52. Subsequently, she developed aortic insufficiency and underwent aortic valve replacement without any hemodynamic or hemostatic problems. Both coronary and valve disease should be considered in patients with antiphospholipid syndrome secondary to systemic lupus erythematosus.

[A case report of aortoesophageal fistula due to thoracoabdominal aortic aneurysm]

Aortoesophageal fistulas due to thoracic aneurysms are usually fatal, with few reported survivors. A 57-year-old man with aortoesophageal fistula due to thoracoabdominal aortic aneurysm underwent the graft replacement of thoracoabdominal aorta. In the postoperative course, prosthetic graft infection had occurred in the result of residual esophageal fistula. On the 32nd postoperative day (POD), a subtotal esophagectomy was performed and the esophagus was reconstructed by gastrointestinal interposition technique via a retrosternal route. Following the second operative procedure, inflammatory reactions had been improved with systemic administration of antibiotics and continuous irrigation of the infected cavity. On 77th POD, he was discharged.

HUB1, a novel Krüppel type zinc finger protein, represses the human T cell leukemia virus type I long terminal repeat-mediated expression

We have shown that human T-cell leukemia virus type I (HTLV-I) gene expression is negatively regulated by the U5 repressive element (U5RE) of its long terminal repeat (LTR). To isolate factors binding to U5RE, we screened a cDNA expression library by south-western blotting with a U5RE probe. Screening 2 x10(6) clones gave a positive clone with a 3.8 kb insert encoding a novel 671 residue polypeptide, named HTLV-I U5RE binding protein 1 (HUB1), with five zinc finger domains and a Krüppel-associated box like domain; HUB1 may be related to a repressor belonging to the Krüppel type zinc finger protein. A 4.0 kb mRNA for HUB1 is ubiquitously expressed among all human tissues tested. HUB1 recognizes the TCCACCCC sequence as a core motif and exerts a strong repressive effect on HTLV-I LTR-mediated expression. A new repressive domain, named HUB1 repressive (HUR) domain, was identified, rather than the Krüppel-associated box like domain. The N-terminal region upstream of HUR domain seemed to be also indispensable to the repression. Thus, we propose that HUB1 is a new type repressor and plays an important role in the HTLV-I U5-mediated repression.

Physical and functional interactions of Doc2 and Munc13 in Ca2+-dependent exocytotic machinery

Doc2 has two C2 domains that interact with Ca2+ and phospholipid. Munc13 has two C2 domains and one C1 domain that interacts with phorbol ester or diacylglycerol (DAG) and phospholipid. Both Doc2 and Munc13 are implicated in Ca2+-dependent neurotransmitter release, but their modes of action still remain unclear. We show here that Doc2 interacts with Munc13 both in a cell-free system and in intact PC12 cells during the high K+-induced Ca2+-dependent exocytosis. The Doc2-Munc13 interactions are stimulated by phorbol ester through the C1 domain of Munc13. Overexpression of the Doc2-interacting domain of Munc13 reduces the Ca2+-dependent exocytosis from PC12 cells, and co-expression with Doc2 suppresses this reduction. These results, together with the earlier findings that secretagogues produce DAG and elevate cytoplasmic Ca2+, suggest that the DAG-induced Doc2-Munc13 interactions play an important role in Ca2+-dependent exocytotic machinery.

Molecular cloning of mouse Doc2alpha and distribution of its mRNA in adult mouse brain

We have previously isolated from a human brain cDNA library, a new protein having two C2-like domains which interact with Ca2+ and phospholipid, and named Doc2alpha. Doc2alpha is abundantly expressed in brain, where it is highly concentrated on the synaptic vesicle fraction, and is implicated in Ca2(+)-dependent exocytosis. We have isolated here a mouse Doc2alpha cDNA and determined the localization of its mRNA in adult mouse brain. The amino acid sequence of the mouse Doc2alpha cDNA is 92% identical with that of the human counterpart. Northern blot analysis and in situ hybridization on adult mouse brain sections have revealed that Doc2alpha is predominantly expressed in mouse brain, where it is expressed in neuronal cells, but not in non-neuronal cells. Doc2alpha is highly expressed in the olfactory bulb, cerebral cortex, hippocampus, amygdaloid complex, and ventromedial hypothalamus nucleus, but not in the cerebellum, caudate-putamen, or ventral thalamus. These results indicate that Doc2alpha is expressed heterogeneously in mouse brain, where it is predominantly expressed in neuronal cells, and suggest that Doc2alpha plays a specific role in the area where it is expressed.

The recombination mediated by double-strand breaks in extrachromosomal DNA substrate carrying mouse immunoglobulin switch regions S mu and S gamma 2b

Recombination in mouse cells was analyzed using extrachromosomal DNA substrates carrying the mouse immunoglobulin switch regions S mu and S gamma 2b. Recombination was detected at a frequency of 10(-2)-10(-3) in mouse fibroblasts and in pre-B cell lines, but at a low frequency in a scid fibroblast cell line. Restriction enzyme digestion profile revealed that most recombination occurred between the CMV promoter region, which neighbors the S mu upstream region, and the S gamma 2b region. However, frequency of direct recombination between the CMV promoter region and the S gamma 2b region was low as measured by the substrate-lacking S mu region. Nucleotide sequence analysis showed that recombination occurred between several homologous base-pairs, and extranucleotides were frequently found at the recombination junctions. These results indicate that recombination took the form of the recombination mediated by double-strand breaks. Double-strand breaks likely occurred in the S mu and/or S gamma 2b region, and the ends joined.

Sp1 family proteins recognize the U5 repressive element of the long terminal repeat of human T cell leukemia virus type I through binding to the CACCC core motif

We have identified several nuclear proteins binding to the U5 repressive element (U5RE) at the U5 region of the human T cell leukemia virus type I (HTLV-I) long terminal repeat (LTR). In gel mobility shift assays with the U5RE DNA probe, Jurkat T cell nuclear proteins generated five different complexes, named U5RE binding protein complexes (U5RP)-A1, -A2, -A3, -B, and -C. Only U5RP-C was affected by pretreatment with an excess of poly(dI-dC) and was immunodepressed by anti-Ku/p80 antibodies, suggesting that U5RP-C is a nonspecific complex involving Ku antigen. UV cross-linking showed at least six nuclear proteins involved in the other complexes, including U5RP-A1, -A2, -A3, and -B. The sequence of the binding core element of these specific complexes, determined by competition assays and gel mobility shift assays using a series of the U5RE mutants, is CACCC which is identical to that for the Sp1 transcription factor. LTR with a mutant U5RE, which has no ability to bind with the nuclear proteins, showed stronger promoter activity than LTR with the wild U5RE, suggesting that the specific interaction of these U5RE-binding proteins might result in the U5-mediated repression. U5RP-A1 was supershifted by anti-Sp1 antibodies and U5RP-A2 and -B were supershifted by anti-Sp3 antibodies, suggesting that Sp1 or Sp3 is involved in U5RP-A1 or U5RP-A2 and -B, respectively. Although the other nuclear proteins remain to be characterized, these findings suggest that U5RE-binding proteins in U5RP-A1, -A2, -A3, and -B are involved in HTLV-I gene repression.

Doc2 enhances Ca2+-dependent exocytosis from PC12 cells

We previously isolated a new protein having two C2-like domains which interacted with Ca2+ and phospholipid and named Doc2 (Double C2). Because Doc2 was abundantly expressed in brain where it was highly concentrated on the synaptic vesicle fraction, we have examined here whether Doc2 is involved in Ca2+-dependent exocytosis from cultured PC12 cells. For this purpose, we took advantage of the growth hormone (GH) co-expression assay system of PC12 cells in which GH is stored in dense core vesicles and released in response to high K+ in an extracellular Ca2+-dependent manner. Northern and Western blot analyses indicated that Doc2 is present in PC12 cells. Overexpression of hemagglutinin-tagged Doc2 stimulated the Ca2+-dependent, high K+-induced release of co-expressed GH without affecting the basal release. In the PC12 cells transfected with a plasmid with the coding sequence of Doc2 in the antisense orientation, the high K+-induced release of co-expressed GH was inversely inhibited. The Doc2 mutant expressing an N-terminal fragment or a C-terminal fragment containing two C2-like domains inhibited the high K+-induced release of co-expressed GH. These results indicate that Doc2 enhances Ca2+-dependent exocytosis of dense core vesicles from PC12 cells.

Molecular cloning of an isoform of Doc2 having two C2-like domains

We previously isolated a novel protein having two C2-like domains known to interact with Ca2+ and phospholipid, and named Doc2 (Double C2). Doc2 is predominantly expressed in brain and is implicated in Ca(2+)-dependent neurotransmitter release. We have isolated here an isoform of Doc2 and named the original one Doc2 alpha and the new one Doc2 beta. Doc2 beta alsp has two C2-like domains and is 61% identical to Doc2 alpha at the amino acid level. In contrast to Doc2 alpha, the Doc2 beta mRNA is expressed ubiquitously. These results indicate that there are at least two isoforms of Doc2, and suggest that Doc2 beta is involved in Ca(2+)-dependent intracellular vesicle trafficking in various types of cells.

Autoantigen Ku protein is involved in DNA binding proteins which recognize the U5 repressive element of human T-cell leukemia virus type I long terminal repeat

We have identified and analyzed a 27-nucleotide sequence (U5 repressive element, designated as U5RE) at the U5 region of the human T-cell leukemia virus type I (HTLV-I) long terminal repeat (LTR) which is required for HTLV-I basal transcriptional repression. The basal promoter strength of constructs that contained deletions in the U5 region of the LTR was analyzed by chloramphenicol acetyltransferase (CAT) assays following transfection of HeLa cells or Jurkat T-cells in the presence or absence of viral transactivator tax protein. We consistently observed a 2- to 5-fold increase in basal promoter activity when sequences between +277 to +306 were deleted. In vivo competition experiments suggested that the U5 DNA fragment from +269 to +295 contains a functional repressive element (U5RE). Using gel mobility shift assays, we have purified a highly enriched fraction that could specifically bind U5RE. This DNA affinity column fraction contained three major detectable proteins on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with silver staining: 110-, 80- and 70-kDa proteins. The 110-kDa protein appeared to be a novel DNA-binding protein whose characteristics are still obscure, while the 70- and 80-kDa proteins were shown to be related to the human autoantigen Ku, the Ku (p70/p80) complex, as demonstrated by amino acid sequencing and immunological analyses. As Ku is known to be involved in transcriptional regulation, the specific interaction of Ku with U5RE raises intriguing possibilities for its function in HTLV-I basal transcriptional repression.

Multiplication of Clostridium botulinum in dead honey-bees and bee pupae, a likely source of heavy contamination of honey

Multiplication of Clostridium botulinum in honey-bees was examined to explain the heavy contamination of honey which may occur with this pathogen. When dead bees were inoculated with C. botulinum spores at levels of 10(2)-10(3) and incubated aerobically for 10 days, the organisms increased to 10(4)-10(5). When botulinum spores were inoculated together with Bacillus alvei, the growth of most strains was significantly enhanced (10(5)-10(7)). Similar results were obtained in bee pupae, but not in bee larvae. The heavy contamination of honey with botulinum spores that we have sometimes encountered may have been caused by contamination from dead bees in which C. botulinum had proliferated.

Purification and characterization of the ganglioside-binding fragment of Clostridium botulinum type E neurotoxin

A way of fragmentation of Clostridium botulinum neurotoxin was carried out to elucidate the structure-function relationship of neurotoxin. The hitherto only plausible fragment was isolated from the trypsin-treated heavy chain of botulinum type E neurotoxin. In the presence of 4 M urea, one protein peak emerged from QAE-Sephadex column loaded with the heavy chain mildly treated with trypsin by elution with 0.1 M sodium chloride. Although many protein bands were detected in SDS-PAGE of the treated heavy chain, the eluted protein migrated in a single band to the position of 41,000 Da. The recovery of the 41,000-Da fragment was 28.6%, but with a 2 M urea-containing buffer as eluant, the recovery was less than 12%. The 41,000-Da fragment bound to gangliosides GD1a, GT1b, and GQ1b, to which neurotoxin and the heavy chain bound. The 41,000-Da fragment partially interfered with the binding of 125I-labeled neurotoxin to mouse brain synaptosomes. We have proposed a three-fragment structure (L.H-1.H-2) for botulinum type E neurotoxin. The characters of the 41,000-Da fragment described in this paper seem to substantiated our proposal that type E neurotoxin consists of three fragments, L.H-1.H-2, and that the ganglioside-binding fragment is H-2.

Detection of Clostridium botulinum in natural sweetening

Various sugar products were examined for contamination with C. botulinum spores. Type A, B and C spores were detected in three of 56 samples of sugar for apiculture, which may attest the significance of bee-feed as a source of contamination of honey. The heavy contamination of honey with C. botulinum spores sometimes encountered, however, can not be explained unless some other factors, e.g., that allowing germination and multiplication of the spores somewhere during honey production, are found. Type A spores were detected in some samples of raw sugar and molasses and also in two of 41 samples of brown sugar lump, but not in refined sugar or other various samples taken at a sugar factory or in sugar cane left on the field in Okinawa. The fact that some natural sweetenings are contaminated with C. botulinum spores, even in low concentrations, may be food-hygienically important.

An unusually heavy contamination of honey products by Clostridium botulinum type F and Bacillus alvei

Many spores (1-60/g) of Clostridium botulinum type F were detected in different containers of honey products of the same brand. Microbiological and physicochemical properties of the contaminated honey were compared with those of the negative one. No difference in pH, hydroxymethyl furfural contents or diastase activity was found between them. The total counts of anaerobes other than C. botulinum and of yeast were also similar, whereas the aerobe counts, which were proportionally related with the C. botulinum counts, were higher in the positive honey than in the negative one. Motile colony-forming Bacillus alvei was predominant among the aerobes. B. alvei stimulated the toxin production by C. botulinum type F in culture medium incubated under aerobic conditions. The high count of C. botulinum in the honey might have been due to the possible stimulation of growth by B. alvei or some other microorganisms at some stage of honey ripening.

Detection of neutral sugars in purified type G botulinum progenitor toxin and the effects of some glycolytic enzymes on its molecular dissociation and oral toxicity

Arabinose and galactose were detected in purified type G botulinum toxin (Mr about 500,000) of Clostridium argentinense. The i.p. LD50/mg N of type G progenitor toxin was one-tenth, but the oral LD50/mg N twice that of type A-L toxin. The lysozyme-, endo-beta-galactosidase-, and N-glucanase-treated toxins each had a molecular mass of about 300,000. The oral toxicity of the endo-beta-galactosidase or N-glucanase-treated toxin was one-fifth that of untreated progenitor toxin. On DEAE-Sephadex chromatography, the N-glucanase-treated toxin dissociated into two fractions, nontoxic and toxic. SDS-PAGE of the toxic fraction showed a single band with a Mr of about 150,000, and after dithiothreitol treatment, two bands with Mr of 100,000 and 50,000.

Difficulties of molecular dissociation of Clostridium botulinum type G progenitor toxin

Clostridium botulinum type G progenitor toxin was chromatographed on DEAE-Sephadex and Q-Sepharose equilibrated with 0.05 M Tris-HCl buffer, pH 8.0, containing 0.2 M urea. The toxin was eluted in a single protein peak from DEAE-Sephadex, but it was eluted in four protein peaks from Q-Sepharose; the third peak was toxic and the others were nontoxic. The third peak, appearing to be the toxic component, had a molecular mass of 150,000. In SDS-polyacrylamide gel electrophoresis, purified type G progenitor toxin migrated in six bands, with molecular masses of 150,000, 140,000, 58,000, 10,800, 10,600, and 10,400. Type G progenitor toxin may be composed of a toxin component with a molecular mass of 150,000 and a nontoxic component in a manner similar to progenitor toxins of other types. Type G toxic component, whether it was reduced or not, migrated in a single band to the same relative positions in SDS-PAGE; type A toxic component reduced with 2-mercaptoethanol migrated in two bands.

Properties of a protease-sensitive acceptor component in mouse brain synaptosomes for Clostridium botulinum type B neurotoxin

To characterize an acceptor for Clostridium botulinum type B neurotoxin, its binding kinetics were examined with mouse brain synaptosomes treated with various enzymes. The amount of 125I-labelled neurotoxin bound to synaptosomes decreased upon treatment with lysyl endopeptidase, neuraminidase, or phospholipase C. The binding of the neurotoxin was partially recovered by incubation of neuraminidase-treated synaptosomes with ganglioside GT1b or GD1a. Gangliosides incorporated into untreated, lysyl endopeptidase-treated, and phospholipase C-treated synaptosomes had no effect on the binding of the neurotoxin. These results may suggest that type B neurotoxin binds to gangliosides in cooperation with a certain protease-sensitive substance on the neural membranes.

Distinction between Clostridium botulinum type A strains associated with food-borne botulism and those with infant botulism in Japan in intraintestinal toxin production in infant mice and some other properties

Two strains of Clostridium botulinum type A associated with food-borne botulism and six strains associated with infant botulism in Japan were compared in intraintestinal toxin production in infant mice, in vitro toxin and hemagglutinin production, molecular sizes of the toxins, and some other properties. The infant botulism-associated strains, producing M toxin (Mr 300 kDa) but no hemagglutinin, showed significantly lower 50% infective doses in infant mouse intestines. The antigenicities of the toxin differed between the two groups, while the biochemical properties of the cultures did not. Besides infant botulism-associated strains, this set of properties were found only in a strain isolated from honey of South American origin.

Distinct characters of Clostridium botulinum type A strains and their toxin associated with infant botulism in Japan

Four strains of Clostridium botulinum type A having been associated with infant botulism in Japan, and another strain isolated from honey not associated with infant botulism, were found to be hemagglutinin (HA) negative. These strains do not produce L (Mr 500 kDa) nor LL toxin (Mr 900 kDa) but M toxin (Mr 300 kDa) only. No marked difference was found between the HA-positive and HA-negative strains in other biochemical properties, but the HA-negative strains tended to colonize more easily in the intestines of infant mice than did HA-positive strains. The toxin of HA-positive strains and that of HA-negative strains differed in the antigenicity of part of the toxic component and that of the nontoxic component, and in the molecular size of the toxic component.

Assay in mice for low levels of Clostridium botulinum toxin

When botulinum toxin at a low level such as 0.1 to 1.0 mouse intraperitoneal LD50 was injected subcutaneously into a mouse at the inguinocrual region, abdominal ptosis with local palsy developed. If this symptom is taken as a marker, 1.0 mouse intraperitoneal LD50 can be detected within 6 h and 0.1 LD50 within 24 h. The severity of symptoms and the time-to-death in days after injection of toxin were converted into scores to quantify the toxic activity. Over a wide range of dose, between 0.075 and 38.4 mouse intraperitoneal LD50, a linear relationship was obtained between the log dose and the score. By use of this method, low levels of toxin such as 0.1 mouse intraperitoneal LD50 can be titrated accurately and easily.

Attempts to quantity Clostridium botulinum type A toxin and antitoxin in serum of two cases of infant botulism in Japan

Serum samples taken from two infant botulism cases during hospitalization were titrated for botulinum toxin by both the intraperitoneal (ip) injection method and the score method in mice. By the ip method, in which death is the only parameter, such low levels of toxin as lower than 4 ip LD50/ml may not be titrated even though the surviving mice show abdominal palsy. By the score method based on the degree of abdominal palsy, such low levels of toxin as 1.1 and 0.8 ip LD50/ml were detected in specimens of one of the patient's serum. No antitoxin was demonstrated in either case of infant botulism by applying the score method. It is not known whether spontaneous recovery from infant botulism is due to the antitoxin production.

Comparative studies on Clostridium botulinum type A strains associated with infant botulism in Japan and in California, USA

Twenty strains of Clostridium botulinum type A associated with infant botulism cases, six in Japan and 14 in California, USA, were compared in their characters. All six Japanese strains produced medium-sized progenitor toxin (M toxin; Mr 300 k) but no hemagglutinin and showed lower 50% infective doses (ID50) in the infant mouse test; whereas most American strains produced large-sized progenitor toxin (L + LL toxins; Mr 500 k and 900 k) and hemagglutinin in addition to M toxin and showed higher ID50 in infant mice. No marked difference in the biochemical properties was found between the two groups except for two American strains.

Incidence of Clostridium botulinum in honey of various origins

By the dilution-centrifugation method, 270 honey samples, both domestic and imported, were examined and Clostridium botulinum was detected in 23 samples (8.5%); type A in 11 samples, type B in two, type C in 10, and type F in one. Of 58 domestic honey samples, six (10%) were positive; three gave type A and the other two type C. Among imported honey samples, Chinese honey gave 12% positives (types A, B, and C) and Argentina honey 20% positives (types A and F). The incidence was higher with samples taken from drums (18%) and from apiaries (23%) than marketing honey (5%). It was estimated that most positive samples contained spores in one per gram or lower concentrations. One sample contained 4 type A spores per gram and another 36-60 type F spores per gram. No distinct biochemical properties were found with the honey isolates.

Titration of botulinum antitoxin of low levels by the score method

Botulinum antitoxin is commonly titrated by injecting a mixture of toxin and antitoxin into mice and by utilizing deaths as a marker to measure the amount of unneutralized toxin. We attempted to titrate antitoxin by converting the severity of symptoms (notably palsy) and time-to-death in days into scores. In neutralization tests with toxin levels at 5.9 LD50 and 23.5 LD50, a linear relationship was obtained for antitoxin dose in a range between 0.03 to 0.003 IU/ml. Statistical analysis showed that homogeneity of variance or slope was not denied for the scores obtained on any day from the first to the fourth days after injection, demonstrating that this method can titrate accurately antitoxin of such a low level as 0.003 IU/ml within 4 days after injection.

Immunochemical identification of the ADP-ribosyltransferase in botulinum C1 neurotoxin as C3 exoenzyme-like molecule

Botulinum C1 neurotoxin and C3 exoenzyme were purified to apparent homogeneity from the culture filtrate of Clostridium botulinum type C strain 003-9. Both preparations catalyzed ADP-ribosylation of the same substrate, the Mr 22,000 rho gene product (Gb). When the light and heavy chains of C1 toxin were separated, ADP-ribosyltransferase activity in the toxin was quantitatively recovered in the light chain fraction. Anti-C1 toxin antiserum precipitated the ADP-ribosyltransferase activity and the neurotoxicity of C1 toxin in parallel, whereas it had no effect on C3 exoenzyme. On the other hand, anti-C3 exoenzyme antiserum precipitated the ADP-ribosyltransferase activities of both C3 exoenzyme and C1 toxin. This antibody, however, did not precipitate the neurotoxicity of C1 toxin. The ADP-ribosyltransferase in C1 toxin was quantitatively adsorbed onto the anti-C3 antibody column and separated from the majority of C1 toxin protein. The enzyme was then eluted with acidic urea and Western blotting analysis of this eluate revealed the appearance of a protein band positively stained with anti-C3 antibody at a position similar to that of C3 exoenzyme. Quantitative determination by enzyme-linked immunosorbent assay showed that the C3-like immunoreactivity is present in the C1 toxin molecules at the molecular ratio of 1 to 1,000. These results suggest that the ADP-ribosyltransferase activity in C1 toxin is expressed by a C3-like molecule which is present in a small amount in the toxin preparation and appears to bind to the toxin component(s). The above results also indicate that the ADP-ribosyltransferase in C1 toxin is not related to its neurotoxin action.