Age effects on ectopic bone formation induced by purified bone morphogenetic protein

A mixture of heparin-Sepharose-purified bovine bone morphogenetic protein and type I atellocollagen was implanted in the subcutaneous tissues of 4-week, 10-month and 18-month-old rats. The implants were removed at 7, 14 and 21 days after implantation. The effects of rat age on ectopic bone formation were evaluated on the explants using haematoxylin-eosin staining, morphometric analysis, alkaline phosphatase activity and calcium content determination, as well as immunohistochemical staining of type IV collagen present in the basement membrane of blood vessels. On day 14 and 21, bone was observed in 4-week and 10-month-old rats, but the amount of bone formed in the latter was less than in the 4-week-old rats. In 18-month-old rats, bone was first found focally in very limited regions of the explants on day 21 and the amount of bone was much less than in 4-week-old rats. At all periods, alkaline phosphatase activity was higher in younger rats. On day 7, there were more blood vessels in the explants of 4-week-old rats than in those of 10-month or 18-month-old rats. On day 14 and 21, more blood vessels were found in the central regions of the explants in 4-week-old rats than in the same regions in 10-month or 18-month-old rats. The findings in the present study indicate that the rate and quantity of ectopic bone formation are reduced in aged rats, and suggest that the difference in blood vessel distribution is related to this reduction in ectopic bone formation.

Semiquantitative analysis of telomerase activity in cervical cancer and precancerous lesions

We investigated telomerase expression in cervical lesions and its diagnostic value for cervical cancer and the precancerous lesions. The subjects were 100 women who underwent cervical biopsy, comprising 16 normal cervix, 61 cervical intraepithelial neoplasia (CIN) and 23 invasive cervical cancer. Telomerase activity was detected by the telomerase repeat amplification protocol using a non-radioisotope system, and quantitated using a DNA image analyzing system. Telomerase was detected at 18.8% (3/16) in normal cervix, 32. 0% (8/25) in CIN I, 50.0% (3/6) in CIN II, 60.0% (18/30) in CIN III, and 91.3% (21/23) in invasive cervical cancer. Semiquantitation of telomerase activity was significantly higher in the subjects with invasive cancer than in those with CIN or a normal cervix (p<0.05). However, telomerase activity was not significantly different between the grades of CIN. Telomerase was detected in subjects with CIN, suggesting that telomerase expression is an early event in cervical carcinogenesis. Quantitation of telomerase activity may be helpful for the diagnosis of cervical cancer.

The human genome has only one functional hsp47 gene (CBP2) and a pseudogene (pshsp47)

Among all the species investigated to date, only in humans is hsp47 reported to exist as two separate genes. Here we examined whether hsp47 forms a gene family, and if so, how many genes constitute the family. Cloning and sequencing of human hsp47 cDNA revealed that only one gene, identical to CBP2, was transcribed. No transcript corresponding to colligin, which was reported to be a human homologue of hsp47, was found. Genomic southern hybridization using the exon III fragment of mouse hsp47 as a probe, however, showed two bands for several restriction enzyme digests. We cloned and sequenced the gene corresponding to the extra band and found that a pseudogene (pshsp47) existed in the human genome. We have mapped this pseudogene to chromosome 9p12-p13 by fluorescent in situ hybridization (FISH) using a 3.5kb genomic fragment containing the entire pshsp47 sequence as a probe. These results suggested that functional hsp47 exists as CBP2, not as colligin, and a highly conserved pseudogene is present in the human genome.

Neuronal degeneration and a decrease in laminin-like immunoreactivity is associated with elevated tissue-type plasminogen activator in the rat hippocampus after kainic acid injection

Tissue-type plasminogen activator (tPA) is a serine protease that converts the inactive precursor plasminogen to the active protease plasmin. In the central nervous system, tPA has been suggested to participate in plasticity, memory and the neuronal degeneration caused by excitotoxins, but its precise functions during these processes are still unclear. We show in this report that tPA antigen level and extracellular tPA activity increased in the hippocampus during the early stages of neuronal degeneration in the CA3 region following the injection of kainic acid (KA) into the lateral cerebral ventricles. The increase in tPA antigen level was transient and its peak was at 4 h after the injection. tPA activity was also increased 4 h after the injection, but it remained at a high level for more than 8 h. Histological zymography showed that the increase in tPA activity was mainly localized in the CA3 region. In the same region, the disappearance of interneuronal laminin-like immunoreactivity and atrophic changes in pyramidal neurons were observed 4 h after the injection of KA. These results suggested that such focal and transient increases in tPA synthesis and release, which result in the proteolysis of laminin through plasminogen activation, could be involved in the neuronal degeneration in the CA3 region after the injection of KA.

Dust concentration around the sites of demolition work after the Great Hanshin-Awaji Earthquake

The total dust concentration and the particle size distribution were determined around die sites of demolition associated with the Great Hanshin-Awaji Earthquake, which occurred on January 17, 1995. The total dust concentrations ranged from 0.20 to 0.23 mg/m(3), being about 1.2 to 2.2 times that in die non-demolition area, and intermediate particles (2.1-11.0μm) made up a large proportion of the dust. The dust concentrations were not influenced by the weather on the day preceding measurement around the sites of demolition of concrete buildings, whereas the values decreased to about half around die sites of demolition of wooden buildings, nearly the same concentration in the control areas, when it had rained on the previous day. The dust concentrations increased compared with that in an average year but to The degree of die upper limit of die environmental standard (1 hr-value<0.20 mg/m(3)) . The dust due to the smoke of Mt. Sakurajima in the surrounding areas accounted for a higher proportion of large particles (<11.0>m) than in the earthquake-devastated area. The concentration of respirable dust (<;7.07>m) in a worker engaged in demolition was 4.0 mg/m(3), being twice the recommended concentration (2 mg/m(3)) of the Japan Society for Occupational Health. It was thus considered that workers should use a respiratory protective device.

Proteolysis of neuronal cell adhesion molecule by the tissue plasminogen activator-plasmin system after kainate injection in the mouse hippocampus

Tissue plasminogen activator (tPA) is a serine protease that converts inactive plasminogen to the active protease plasmin and mediates extracellular metabolism. tPA is transcriptionally induced in the mouse hippocampus by pharmacological or electrical stimulation of neuronal activity and mediates excitotoxin-induced neuronal degeneration. Therefore, we hypothesized that tPA would be induced in the hippocampus after kainic acid (KA) injection into the lateral cerebral ventricle (LCV) and that the activated tPA-plasmin system would degrade the neuronal cell adhesion molecule (NCAM), which is a component of the extracellular matrix. In order to investigate this possibility, we first examined whether NCAM is a substrate for the tPA plasmin system by incubating mouse brain homogenates with tPA and plasminogen at 37 degrees C. Next, we examined the degradation of NCAM and the changes of tPA activity in the mouse hippocampus with immunohistochemical procedures and histological zymography after KA injection into both LCVs. As a result, we observed neuronal atrophy and a decrease of NCAM immunoreactivity along with an increase of tPA activity in the CA3 area of the hippocampus. These results suggest that activation of the tPA plasmin system after KA injection into the LCVs results in the degradation of NCAM in the CA3 area.

Effect of bilateral lesions of the suprachiasmatic nucleus on hyperglycemia caused by 2-deoxy-D-glucose and vasoactive intestinal peptide in rats

In mammals, the brain usually uses glucose as a sole energy source. Thus, under a central glucopenic condition after intracranial injection of 2-deoxy-D-glucose (2DG), an inhibitor of glucose utilization, it has been shown that rats elevate their blood glucose level through excitation of the sympathetic nerves. Experiments were conducted with rats to examine the role of the hypothalamic suprachiasmatic nucleus (SCN) in the hyperglycemic response to intracerebroventricular injection of either 2DG or vasoactive intestinal peptide (VIP). It was observed that, (1) intracerebroventricular injection of a VIP-antagonist inhibited the hyperglycemic and hyperglucagonemic responses to the intracranial injection of 2DG; (2) bilateral electrolytic lesioning of the SCN suppressed the hyperglycemic and hyperglucagonemic responses to intracranial injection of 2DG, and intracerebroventricular injection of VIP restored these responses to 2DG; and (3) bilateral electrolytic lesioning of the SCN also suppressed the hyperglycemic and hyperglucagonemic responses to the VIP injection, and additional intracerebroventricular injection of 2DG caused hyperglycemia. These findings indicate that in rats with bilateral lesions of the SCN intracranial injection of 2DG is able to elicit hyperglycemia when VIP was administered intracranially, and suggest that neurons containing VIP-like immunoreactive substance (VIP-neurons) in the SCN have an important role in the mechanism of hyperglycemia elicitation following intracranial injection of 2DG. Moreover, these findings show that 2DG and VIP are able to realize their functions through acting on the brain sites outside the SCN.

[Histopathological examination of transurethral electrovaporization of the prostate]

Transurethral electrovaporization of the prostate (TVP) has been devised to eliminate prostatic tissue by electric vaporization and to create a dry coagulation layer beneath to minimize bleeding from the site of TVP. However, vaporization induces degeneration due to thermal coagulation deep in the tissue beneath the vaporized layer, and local tissue damage is thus greater than that caused by the standard transurethral resection of prostate (TURP) loop. Since this results in difficulty with histopathological examination, the percentages of tissue-diagnosable area were determined in sections resected using various vaporization electrodes (Roller Loop, Band & Wedge Loop). The percentage of tissue-diagnosable area was 92.0 +/- 3.3% with the standard TUR loop, 2.4 +/- 0.9% with the Roller Loop, 42.7 +/- 21.1% with the Band Loop, and 39.7 +/- 24.4% with the Wedge Loop. Concerning speed of resection, the best vaporization effect was obtained when the speed of operation was 1/2 or 1/3 that with the standard TUR loop. Since the region in which tissue diagnosis was smaller with the vaporization electrode than with standard TURP, more careful examination was required for diagnosis of incidental cancers. Therefore, postoperative observation by PSA measurement appeared to be important.

Population pharmacokinetics and pharmacodynamics of cisplatin in patients with cancer: analysis with the NONMEM program

The population pharmacokinetics and pharmacodynamics of cisplatin (CDDP) were evaluated based on a mixed-effect model using the NONMEM program. Unchanged CDDP in plasma was measured as a biologically active platinum species during CDDP chemotherapy, using high-performance liquid chromatography. Plasma concentration measurements (157) of unchanged CDDP from 26 patients with cancer receiving 80 mg/m2 CDDP by infusion over 2 hours, 3.5 hours, or 4 hours were analyzed according to a one-compartment model. The influences of individual characteristics such as body weight, dose schedule, course, and clinical laboratory values (renal function markers, albumin) on total body clearance (Cl) and volume of distribution (Vd) were examined. In the final pharmacokinetic model, body surface area and dose schedule affected Cl of unchanged CDDP. The Cl of CDDP was increased by 27.3% after the 2-hour infusion schedule compared with Cl after the longer infusions. The Vd was estimated as 13.4 L/m2. The interindividual variability for Cl and Vd and residual variability were 22.9%, 30.9%, and 35.5%, respectively. The relationships between maximum concentration (Cmax) of unchanged CDDP and maximum blood urea nitrogen (BUNmax), or minimum creatinine clearance (ClCr,min) over a 1-month period after CDDP administration were evaluated according to linear, exponential, or maximum response (Emax) models. The linear or Emax model described pharmacodynamics most successfully, with relatively large interindividual variability for both slope and EC50 (more than 25%). Residual variability was 15.3% and 17.1% in BUNmax and Clcrmin, respectively. The population means and interindividual and residual variability of pharmacokinetics and pharmacodynamics of CDDP were evaluated using the NONMEM program. The results of this study show that the population pharmacokinetic and pharmacodynamic approach could be useful to manage CDDP nephrotoxicity using sparse data in a clinical setting.

Plasma levels of 5-HT and 5-HIAA increased after intestinal ischemia/reperfusion in rats

Intestinal ischemia/reperfusion (I/R) causes serious systemic injury, mainly from a variety of bioactive substances released from the injured intestine. To assess the possible roles of serotonin (5-hydroxytryptamine, 5-HT), a bioactive amine mainly stored in the intestine, in I/R injury, we assayed the levels of tryptophan, 5-HT, and 5-hydroxyindole acetic acid (5-HIAA) in the blood and intestine in a rat I/R model. Plasma 5-HT increased significantly over time after reperfusion; the plateau level was obtained 4 h after reperfusion and was associated with an increase in 5-HIAA. Plasma tryptophan levels declined gradually after reperfusion. The ratio of 5-HIAA/5-HT was significantly higher in I/R rats than in control rats, suggesting that elevated 5-HT was quickly metabolized in the systemic circulation. In the intestine, 5-HT decreased dramatically, whereas tryptophan increased. This phenomenon was prominent in the severely damaged intestine. These findings suggest that the injured intestine released large amounts of 5-HT, whereas its synthesis in the injured intestine was suppressed. An increase in 5-HT in the circulation may be related to various circulatory disturbances observed in humans after intestinal ischemia.

Progressive expansion of hypertensive intracerebral hemorrhage by coagulopathy

To test the hypothesis that an impaired coagulation system facilitates rapid expansion of hypertensive intracerebral hemorrhage (HICH), coagulation markers were assayed in plasma and their relations to both the hemorrhage size and its progressive expansion were analyzed. Ninety patients with HICH were studied. On admission, plasma samples were taken for the coagulation assay. Hematoma volume was calculated from a computed tomography (CT) scan and its enlargement was estimated by comparison to the volume of the hematoma calculated from a second CT scan taken later within 24 hr. Nine out of 90 patients showed enlargement in their hematoma size (enlarged hematoma group). Four of the enlarged hematoma group fell into acute fatal deterioration and died. Plasma levels of both fibrino peptide A (17.2+/-7.8 vs. 4.0+/-0.6 ng/ml, P < 0.05) and thrombin-antithrombin complex (21.9+/-3.1 vs. 7.4+/-2.8 ng/ml, not significant) were higher in the unchanged group than those in the enlarged hematoma group. In the hematoma-enlarged group fibrino-peptide A level did not exceed 10 ng/ml. In the hematoma unchanged group thrombin-AT-III complex values were positively correlated to hematoma volume. Thus, the coagulation system seemed to be highly activated depending on the hemorrhage volume within three hr after ictus in hypertensive intracerebral hemorrhage patients. When thrombin generation was not sufficient after bleeding, the hematoma seemed to be progressively enlarged. In conclusion, plasma levels of the coagulation markers on admission could be useful predictors of the possible enlargement of hematoma which leads to a poor outcome.

Carrier-dependency of cellular differentiation induced by bone morphogenetic protein in ectopic sites

Partially purified bone morphogenetic protein (BMP) was delivered into two different types of carriers, porous particles of hydroxyapatite (PPHAP) and particles of insoluble bone matrix (IBM), and the ossification process was examined after subcutaneous implantation of the BMP/PPHAP and BMP/IBM in rats. The ossification in the BMP/PPHAP system was predominantly direct through bone formation similar to intramembranous ossification, whereas in the BMP/IBM system it was predominantly endochondral. The differences observed between the BMP/PPHAP and the BMP/IBM indicate the importance of the structure and nature of the carrier in the process of bone induction. The findings suggest that bone and cartilage differentiation is controlled not only by the regulation factor (BMP), but also by its interaction with the carrier, and that the BMP-induced cell differentiation is dependent upon the microenvironment derived from the carrier.

[Postoperative complications after Mainz pouch construction--with emphasis on measures to deal with narrowing of the duct aperture]

Thirty patients underwent Mainz pouch construction between December 1992 and January 1998. The post-operative observation period varied from 6 to 57 months (average, 38.5 months). A mechanism to ensure urinary continence was provided in 24 cases, while formation of a nipple valve by intussusception of the ileum with seromuscular stripping and submucosally embedded in situ appendix was performed in 6 cases. An umbilical stoma was adopted in all cases. Late-phase complications included 3 cases of hydronephrosis requiring treatment. Efferent limb of the stoma was observed in 8 cases, 6 of which were attributable to mild constriction of the stoma at the site of anastomosis of the navel cavity. In those cases in which stomal stricture occurred, difficulty in withdrawing urine was eliminated by providing a fistula stopper. Although few clinical methods to deal with stomal stricture have been reported, we found the fistula stopper to be useful providing good external appearance and patients' quality of life.

[Bellini duct carcinoma of the kidney: a case report]

A case of Bellini duct carcinoma is reported. A 71-year-old woman visited our hospital with a chief complaint of lower abdominal pain. Computerized tomography, ultrasonography showed a mass lesion measuring about 5 cm in the right kidney. Angiography showed an avascular mass lesion in the right kidney. Right radical nephrectomy was performed under the diagnosis of renal cell carcinoma. Histological examinations showed Bellini duct carcinoma of the papillary type. We performed M-VAC (methotrexate, vinblastine, doxorubicin, icisplatin) therapy as is used for transitional cell carcinoma. She is alive with no evidence of disease 5 months after her surgical treatment. To our knowledge, only 32 cases of Bellini duct carcinoma have been reported in the Japanese literature.

LPS-stimulated SJL macrophages produce IL-12 and IL-18 that inhibit IgE production in vitro by induction of IFN-gamma production from CD3intIL-2R beta+ T cells

SJL mice are known for their poor IgE production upon helminth infection. In this study, we have demonstrated that SJL standard B cells (85% IgM+ or B220+), prepared by complement-mediated T cell lysis, failed to proliferate and to produce IgE and IgG1 in response to LPS plus IL-4 in vitro. This diminished IgE production was restored by anti-IL-12 and enhanced by additional treatment with anti-IL-18, suggesting active suppression by the cells that produce IL-12 and IL-18. Indeed, SJL standard B cells were contaminated with Mac-1+ cells. Therefore, we removed macrophages by passing standard B cells through a Sephadex G-10 column (G10). Resultant cells (95% IgM+), designated as G10-B cells, responded to LPS and IL-4 by their proliferation and differentiation. G-10 treatment markedly diminished the proportion of B220- cells and Mac-1+ cells in SJL standard B cells. Furthermore, addition of SJL B220- cells dose dependently and MHC independently inhibited LPS plus IL-4-induced B cell growth and IgE production in SJL and BALB/c B cells. B220- cells in SJL standard B cells contained Mac-1+ cells (51%) and Fas ligand+ CD4-CD8- double-negative CD3intIL-2R beta+ T cells (26%). Thus, IL-12 and IL-18 produced by LPS-stimulated Mac-1+ cells stimulate this unique subpopulation of T cells to produce IFN-gamma, which in combination with Fas ligand, inhibits IgE production from the B cells. Our present results indicate that Mac-1+ cells and double-negative CD3intIL-2R beta+ T cells, uniquely abundant in the spleens of SJL mice, inhibit IgE production, indicating their new role in IgE response.

Human thrombin and calcium bound factor Xa significantly shorten tPA-induced fibrin clot lysis time via neutralization of plasminogen activator inhibitor type 1 activity

Employing a fibrin clot lysis assay, we reassessed the significance of the neutralization of plasminogen activator inhibitor type 1 (PAI-1) activity by thrombin and factor-Xa in fibrinolysis. When PAI-1 enriched fibrin clots were formed using increasing concentrations of thrombin (0.1, 0.5, 1.0 IU/ml), their lysis times became shorter (43.8 +/- 4.9, 25.7 +/- 3.7, 13.9 +/- 0.8 h respectively). Times were shortened further by either heparin (43.9 +/- 11.0, 12.1 +/- 2.6, 3.6 +/- 0.2 h respectively) or vitronectin (17.0 +/- 1.6, 1.9 +/- 0.7, 0.9 +/- 0.0 h respectively). Factor-Xa together with Ca++ shortened the clot lysis time further. Fibrin autography revealed that both enzymes dose dependently interfered with complex formation between tPA and PAI-1, making large amounts of tPA remaining to be free form. The mechanism seems to play a role in the coagulation associated enhancement of fibrinolysis.

Vectorcardiographic evaluation of myocardial infarct size: departure parameters are superior to conventional spatial parameters

To determine whether the departure parameters derived from a "departure loop" of a vectorcardiogram are more accurate than conventional spatial parameters in evaluating myocardial infarct size, 74 patients with first-onset myocardial infarction (MI) were studied. The correlation between the departure parameters (amplitudes in scalar leads of the departure loop) and the percent defect volume of thallium myocardial scintigrams (%DV) was compared with that of the spatial parameters (magnitude, azimuth, and elevation of the original QRS loop). In anteroseptal MI, the amplitude of a 20-msec vector in the z-axis and the azimuth of a 30-msec vector (H30) were significantly correlated with %DV (r=0.783, p<0.001 and r=0.572, p<0.05). In anteroseptal MI with involvement of the lateral wall, the amplitude of a 30-msec vector in the x-axis and H30 showed significant correlation with %DV (r=0.802, p<0.001 and r=0.772, p<0.01). In inferior and inferoposterior MI, the amplitude of a 30-msec vector in the y-axis and the elevation of a 30-msec vector were significantly correlated with %DV (r=0.920, 0.891, p<0.001 and r=0.871, 0.678, p<0.01, respectively). In conclusion, the departure parameters are more accurate than the spatial parameters for evaluation of myocardial infarct size.

Telomerase activity in body cavity fluid and peritoneal washings in uterine and ovarian cancer

The telomeric repeat amplification protocol (TRAP) assay was used to measure telomerase activity in body cavity fluid from 10 ovarian cancer patients (ascites 9; pleural fluid, 1), ascites and peritoneal washings from eight uterine corpus cancer patients, and ascites from one with cancer of the uterine cervix. Telomerase activity was observed in five of six (83.3%) samples with positive cytology, one of four (25%) samples with suspicious cytology and one of nine (11.1%) samples with negative cytology. A high level of activity was observed in samples containing large numbers of blood-cell components, which could be removed without inactivating the telomerase by treating the samples with Nycodenz (N,N1-Bis (2,3-dihydroxypropyl)-5-[N-(2,3-dihydroxypropyl) acetamide] 2,4,6-triiodo-isophtalamide). In two patients with ovarian cancer treated with anticancer drugs, 5 and 7 days after treatment, intracellular vacuoles and multinucleation were observed in ascites tumour cells, and telomerase activity decreased. At 14 to 21 days after treatment, the ascites tumour cell morphology was the same as before treatment, and telomerase activity rose once again. The TRAP assay is a sensitive method of detecting telomerase in cytological material and may provide a useful adjunct to cytological diagnosis.

Improved high-performance liquid chromatographic analysis of teniposide in human plasma

A simple and practical high-performance liquid chromatographic analysis has been developed for measuring teniposide (VM26) in human plasma. The present analytical method has improved extraction efficiency from human plasma, therefore allowing determination of VM26 in a clinical setting using ultraviolet detection alone. Furthermore, sample preparation was simplified and shortened through use of a one-step extraction procedure. VM26 and internal standard (ibuprofen) were extracted from human plasma (0.5 ml) with ethyl acetate. A phenyl muBondapak column eluted with a mobile phase, consisting of acetonitrile-distilled water-acetic acid (30:68:2, v/v/v) was used for separation, and quantitation was achieved with a UV monitor set at 240 nm. Average extraction efficiency was 96.8+/-6.6% for VM26 between 1 and 25 microg/ml, and 91.4+/-4.3% for internal standard, with both intra- and inter-day coefficients of variation being less than 10%. The detection limit with a 100-microl injection was estimated at 0.2 microg/ml with a signal-to-noise ratio of 3 for VM26 in human plasma. The stability data of VM26 in plasma, standard and stock solutions were also obtained. The present method was found to be an alternative to the previously reported method with an electrochemical detection, and can be easily applied to routine clinical pharmacokinetic studies of VM26.

Pure clear cell papillary thyroid carcinoma with chronic thyroiditis: report of a case

We herein report a case of pure clear cell papillary thyroid carcinoma, which is the first reported case in Japan. The tumors measured 1.0 x 0.9 and 0.7 x 0.4 cm in size. An ultrasonographical examination revealed hypoechoic irregular-shaped lesions with fine internal calcifications. No lymph node metastasis was observed in any of the surgical specimens. Distant metastasis had not been observed as of 6 years after surgical treatment. The number of cases of pure clear cell papillary carcinoma reported so far are too few to clearly elucidate its characteristics; however, the ultrasonographical findings and biological behavior of this case were compatible with those of non-clear cell papillary thyroid carcinoma.

[Telomerase activity and telomere length as diagnostic tumor marker for ovarian tumors]

Telomerase activity was detected in germ cells, stem cells and cancer cells. In tumors of the ovary, an organ that contains germ cells, the authors examined availability to detect telomerase activity. Telomerase activity of malignant tumors was extremely high compared with that of normal ovaries and benign tumors. Strength and frequency of telomerase activity in malignant tumors was significant different from that in benign tumors. Telomere length tended to be smaller for malignant tumors of advanced stage, but no significant relationship between telomere length and telomerase activity and tumor stage could be recognized. Telomerase activity may be a useful marker for the diagnosis of ovarian tumors.

Proteolysis of highly polysialylated NCAM by the tissue plasminogen activator-plasmin system in rats

Tissue-type plasminogen activator (tPA), a serine protease which converts the zymogen plasminogen to the active protease plasmin, is believed to regulate neurite extension and neural cell migration by modulating extracellular metabolism. The highly polysialylated form of the neural cell adhesion molecule (NCAM-H) is strongly expressed in the developing brain and is believed to play a role in organizing the neural network. In this report, we incubated neonatal rat brain homogenates with human tPA and rat plasminogen in order to determine whether NCAM-H would be degraded. NCAM-H was degraded by plasmin which was formed from rat plasminogen by human tPA. The degradation was inhibited by the addition of plasminogen activator inhibitor type 1 (PAI-1) or aprotinin. These results suggest a possible contribution of the tPA-plasmin system to NCAM-H turnover in the developing brain.

Nicotine increases stress-induced serotonin release by stimulating nicotinic acetylcholine receptor in rat striatum

We used a microdialysis technique to analyze the effects of footshock stress on the release of serotonin (5-hydroxytryptamine: 5-HT) in the striatum or prefrontal cortex (PFC) in rats that were pretreated with nicotine. Neither nicotine administration alone nor stress application alone changed 5-HT release. During stress application, however, both chronic nicotine administration and local infusion of nicotine to the striatum significantly increased 5-HT release in the striatum, though not in the PFC. These increases in 5-HT release were eradicated by a local infusion of mecamylamine. Release of 5-HT increased in the striatum during stress application when nicotine was injected to the striatum, while nicotinic injection to the dorsal raphe nucleus did not increase 5-HT release in the striatum. The present study demonstrates that nicotine induced a release of 5-HT upon stress application by stimulating presynaptic nicotinic receptors in the striatum.

Extracellular serotonin in the striatum increased after immobilization stress only in the nighttime

The release of serotonin (5-HT) in the striatum and the motor activity of rats given the immobilization stress were measured using in vivo microdialysis techniques and locomotion counts. Serotonin release in the striatum did not change in the daytime and nighttime, but motor activity in the nighttime was significantly higher than in the daytime. Serotonin release was not significantly increased during immobilization stress in the daytime or nighttime. In the nighttime, however, after the end of stress, 5-HT release was significantly increased from 0.002 ng/dialysate to 0.47 ng/dialysate. The motor activities were also significantly increased after the stress in the nighttime. These results suggest that the effects of immobilization stress on serotonin release in the striatum were different in the daytime and nighttime. In the nighttime, serotonin release in the striatum and the motor activities increased not during but after immobilization stress.