[The effect of continuous intra-articular and intra-bursal infusion of lidocaine on postoperative pain following shoulder arthroscopic surgery]

We evaluated the effects of continuous intra-articular and intra-bursal infusion of lidocaine on postoperative pain following shoulder arthroscopic surgery. Forty-one ASA I-II patients scheduled for shoulder arthroscopic surgery, were allocated into following four groups. The patients, after intra-articular arthroscopic surgery, either received intra-articular lidocaine (Group I, n = 10) or did not (Group III, n = 10). The patients after extra-articular arthroscopic surgery either received intra-bursal lidocaine (Group II, n = 11) or did not (Group IV, n = 10). Group I and Group II received 8 ml of 1% lidocaine intra-articularly and intra-bursally, respectively, at the end of surgery, followed by continuous infusion of 1% lidocaine at the rate of 2 ml.hr-1 for 24 hours. The intensities of postoperative pain were evaluated by Visual Analogue Scale (VAS), 2, 5, 8, 12, 18 and 24 hours after surgery, and by the number of patients' request for supplemental analgesic for 24 hours. The VAS scores and the number of analgesic requests were significantly lower (P < 0.05) in Group I than Group III, and in Group II than Group IV throughout the postoperative observation period. No adverse effects were observed during this study. We conclude that continuous intra-articular and intra-bursal infusion of lidocaine provides effective postoperative pain relief for shoulder arthroscopic surgery.

Prodromal signs and clinical factors influencing outcome in patients with intraventricular rupture of purulent brain abscess

OBJECTIVE

To elucidate prodromal signs and clinical factors influencing the prognosis in patients with intraventricular rupture of brain abscess (IVROBA) to prevent and manage this catastrophic condition.

METHODS

In this study, 33 consecutive patients with IVROBA diagnosed by computed tomography (CT) were treated. Basic and therapeutic parameters were evaluated as independent predictive factors of a poor prognosis by using univariate analysis. The factors were statistically analyzed based on the interval between initial symptoms and IVROBA.

RESULTS

Patients with a good outcome were younger (<21 yr old) (P < 0.003) and had fewer complications after IVROBA (P < 0.03). For the most part, these patients had undergone aspiration for brain abscess with ventricular drainage combined with the immediate administration of appropriate intravenous and intrathecal antibiotics (P < 0.02). In just a short time, abscesses located in the parieto-occipital region ruptured into the ventricle (P < 0.004), and those with nonsterile cultures (P < 0.01) developed into IVROBA. Just before IVROBA, patients had severe headaches, signs of meningeal irritation, and a rapidly deteriorating clinical condition within 10 days after the signs of meningeal irritation developed. A CT scan obtained before IVROBA ascertained localized enhancement of the ventricular wall adjacent to the abscess.

CONCLUSION

Our findings suggest that signs of meningeal irritation and localized enhancement of the ventricular wall adjacent to the abscess, as observed on CT scans, preceded IVROBA. To decrease the mortality rate associated with purulent brain abscesses, signs forewarning of IVROBA should be recognized, and aggressive management of IVROBA should be initiated. Aggressive CT-guided aspiration of deep-seated abscesses, particularly in the parieto-occipital region, at the time forewarning signs of IVROBA are observed lead to the prevention of IVROBA and an improvement in outcome.

The effects of peripheral administration of a novel selective antagonist for prostaglandin E receptor subtype EP(1), ONO-8711, in a rat model of postoperative pain

Mechanically evoked pain, also known as incident pain, induced by coughing or deep breathing after surgery leads to potentially devastating consequences. It is generally thought that the prostaglandin receptor- (especially, the receptor for prostaglandin E(2), EP receptor) mediated sensitization of sensory nerve fibers is a key contributor to the generation of hyperalgesia. We examined whether a peripherally administered novel selective EP(1) antagonist, ONO-8711, would be a potential analgesic for incision-induced mechanical hyperalgesia. We used a rat model of postoperative pain introduced by Brennan et al. (1). Withdrawal thresholds to punctate stimulation and response frequencies to nonpunctate mechanical stimulation were determined by using von Frey filaments applied adjacent to the wound and directly to the incision site of the hind paw, respectively. Mechanical hyperalgesia to punctate and nonpunctate stimuli was observed 2 and 24 h after the incision. ONO-8711 (2, 10, or 50 microg) or saline was administered subcutaneously into the hind paw on the ipsilateral side to the incision. ONO-8711 significantly (P < 0.01) increased the withdrawal thresholds to punctate mechanical stimulation and significantly (P < 0.01) decreased the response frequencies to nonpunctate mechanical stimulation in a dose- and time-dependent manner 2 and 24 h after the incision. We conclude that EP(1) receptor-mediated sensitization of sensory nerve fibers may contribute to the generation of mechanical hyperalgesia produced by incisional surgery, and that the EP(1) receptor antagonist ONO-8711 may be an option for treatment of postoperative pain, especially incident pain.

IMPLICATIONS

The peripheral administration of an antagonist for EP(1) receptor that is a subtype of prostaglandin E receptors can inhibit the mechanical hyperalgesia induced by a surgical incision.

Clinical application of an ultrasonically activated scalpel in neurosurgery

Ultrasonically activated scalpel (UAS) is a surgical device utilizing ultrasonic energy to cut and coagulate tissues simultaneously. The actions and features of UAS are considerably different from those of conventional ultrasonic cavitational aspirators (UCA) that have been used frequently in the neurosurgical field. The UAS has been used routinely in a number of general surgeries, including laparoscopic surgeries and open surgeries of the lung and liver. However, neurosurgical application of UAS has not been reported. We used UAS in surgical resection of intracranial tumors consisting of five meningiomas, two gliomas, and one metastatic brain tumor, and monitored thermal changes in tissues using thermoencephaloscopy to investigate the possibility of heat injury by UAS. It was used to achieve both dissection of the attachment of meningiomas and internal decompression of the tumors and allowed efficient resection of various tumors with minimal bleeding by adjustment of the combination of coagulation and cutting powers at five different positions. The attachment of meningiomas was coagulated and cut easily and safely by UAS. Moreover, infrared thermographic study showed that the degree of temperature increase and the area of elevated temperature were extremely limited in UAS. The current study suggests that it is a promising device in neurosurgery.

[Primary central nervous system malignant lymphoma originating from the cerebellum and extending along the lower cranial nerves]

We report a case of primary central nervous system (CNS) malignant lymphoma of the central nervous system originating from the cerebellum and growing along the lower cranial nerves. A 67-year-old woman presented with hoarseness, vertigo, nausea, and vomiting. Gd-DTPA enhanced MRI showed a homogeneous enhanced mass lesion extending from the cerebellum to the medulla oblongata around the jugular foramen on the right side. Although pre- and intra-operative diagnosis had been schwannoma, histopathological examination revealed a B-cell, diffuse malignant lymphoma. The growth pattern of malignant lymphoma in the present case, which extended extra-axially, is considered to be rare. We discuss here the growth patterns and difficulties of diagnosis of primary CNS malignant lymphoma in this area.

[Anesthetic management of a patient with Freeman-Sheldon syndrome]

We describe a case of Freeman-Sheldon syndrome that presented some problems for anesthetic management. A 2-yr-old girl required orthopedic surgery for the bilateral lower extremities. Anesthesia was induced via a mask with oxygen (2 l.min-1), nitrous oxide (4 l.min-1) and sevoflurane (approximately 5%). Tracheal intubation by direct laryngoscopy was successfully achieved. Combined caudal epidural block was, however, avoided because spina bifida occulta was suspected. Spina bifida occulta was revealed postoperatively by X-ray. For anesthetic management of a patient with Freeman-Sheldon syndrome, the spine should be evaluated preoperatively when performing epidural/spinal anesthesia.

Analgesic mechanisms of ketamine in the presence and absence of peripheral inflammation

BACKGROUND

The studies on the mechanisms of ketamine antinociception have led to conflicting results. In this study, the authors investigated the contribution of supraspinal monoaminergic descending inhibitory system to ketamine analgesia for acute nociception and inflammation-induced hyperalgesia.

METHODS

Male Sprague-Dawley rats were used. The paw withdrawal latencies to radiant heat stimuli were measured to assess the thermal nociceptive threshold. The analgesic effects of intrathecal or intraperitoneal ketamine were examined in the rats that received unilateral intraplantar carrageenan and in those that were untreated. In addition, it was examined whether pretreatment with intrathecal yohimbine or methysergide inhibited the analgesic effects of ketamine. Using an intrathecal microdialysis method, noradrenaline and 5-hydroxytryptamine concentrations in lumbar cerebrospinal fluid were measured after intraperitoneal ketamine in both saline- and carrageenan-treated rats.

RESULTS

In the untreated rats, intraperitoneal but not intrathecal ketamine produced antinociceptive effects in a dose-dependent manner. Pretreatment with intrathecal yohimbine or methysergide inhibited these antinociceptive effects. Intraplantar carrageenan significantly reduced paw withdrawal latencies on the injected paw but not on the contralateral paw. Both intraperitoneal and intrathecal ketamine reversed the shortened paw withdrawal latencies on the injected side in a dose-dependent manner without any effects on the contralateral side. Neither yohimbine nor methysergide inhibited these antihyperalgesic effects. In analyses of monoamines, the magnitude of increase in monoamines after intraperitoneal ketamine was significantly smaller in the carrageenan-treated rats than in the saline-treated rats.

CONCLUSION

These results demonstrated that ketamine produced antinociceptive effects through an activation of the monoaminergic descending inhibitory system, whereas, in a unilateral peripheral inflammation-induced hyperalgesic state, the monoaminergic system did not contribute to the antihyperalgesic effects of ketamine. The mechanisms of the antinociceptive and antihyperalgesic properties of ketamine are different.

Rapamycin and FK506 induce long-term potentiation by pairing stimulation via an intracellular Ca(2+) signaling mechanism in rat hippocampal CA1 neurons

Immunophilin-CsA and -FK506 complexes bind to calcineurin (CaN) and inhibit its phosphatase activity leading to enhancement of neuronal activities. However, inhibition of CaN activity is not the mediator of modulatory activity for IP3 and ryanodine receptors and does not mediate the neurotrophic actions of FK506. FK506 binding protein (FKBP)-12 also binds rapamycin, another immunosuppressant which does not affect CaN activity. Using whole-cell patch clamp techniques, excitatory postsynaptic currents (EPSCs) were recorded and we analyzed the effect of immunosuppressants on the synaptic potentiation induced by pairing weak presynaptic stimulation with postsynaptic depolarization in CA1 neurons of rat hippocampal slices. We found that postsynaptic application of rapamycin or FK506, at low concentrations, but not cyclosporin A, in conjunction with weak pairing stimulation, induced NMDA-dependent long-term potentiation (LTP). The rapamycin-induced LTP was blocked by chelating intracellular Ca(2+) or by inhibiting the intracellular Ca(2+) release. Thus, Ca(2+) release from intracellular Ca(2+) stores is required for the induction of LTP by weak pairing stimulation in the presence of rapamycin or FK506 at postsynaptic sites. We propose that postsynaptic FKBP-12 regulates synaptic transmission by stabilizing the postsynaptic Ca(2+) signaling mechanism in rat hippocampal CA1 neurons.

Activation of peripheral NMDA-nitric oxide cascade in formalin test

BACKGROUND

It has been suggested that peripheral glutamate and nitric oxide (NO) released by tissue-damaging stimuli play an important role in peripheral nociceptive transmission. This study was conducted to determine whether NO was released in the periphery after subcutaneous injection of formalin and whether the peripheral N-methyl-d-aspartate (NMDA)-NO cascade was activated.

METHODS

During pentobarbital anesthesia, a microdialysis probe was implanted subcutaneously into the glabrous skin of both hind paws of Sprague-Dawley rats. After sample collection to obtain the basal level of NO metabolites (total amount of nitrite [NO2-] and nitrate [NO3-] [NO2--NO3-]), 5% formalin was injected into the plantar surface of the right hind paw during perfusion of the dialysis catheters with artificial cerebrospinal fluid (ACSF), the NO synthase inhibitor NG-monomethyl-L-arginine acetate, or the NMDA antagonist D,l-2-amino-5-phosphonovaleric acid through a microdialysis probe. Formalin also was injected in the animals that underwent sciatic nerve sectioning. In another series of experiments, NMDA was perfused through one probe. Samples for measurement of NO2--NO3- were collected and immediately analyzed using high-performance liquid chromatography.

RESULTS

Subcutaneous formalin significantly increased the dialysate concentrations of NO2--NO3- (maximum increase 144 +/- 12% of baseline value 30 min after formalin administration; P < 0.05) on the side ipsilateral to the injection. Both NG-monomethyl-l-arginine acetate and D, l-2-amino-5-phosphonovaleric acid significantly (P < 0.05) suppressed the formalin-induced increases in NO2--NO3- concentration. In the rats with denervation of the sensory nerves, formalin did not change the NO2--NO3- concentration. In addition, NMDA perfusion significantly (P < 0.05) increased the concentrations of NO2--NO3-.

CONCLUSION

The results of the current study show that subcutaneous formalin injection induces peripheral release of NO, the production of which is mediated by activation of NMDA receptors in the peripheral nervous system.

Dual effects of PKNalpha and protein kinase C on phosphorylation of tau protein by glycogen synthase kinase-3beta

We analyzed the effects of PKNalpha and protein kinase C (PKC) on phosphorylation of tau protein by glycogen synthase kinase (GSK)-3beta using monoclonal antibodies (AT8, AT180, and AT270). These antibodies are highly specific for phosphorylated tau in Alzheimer paired helical filaments, and recognize phosphorylated Ser202/Thr205, Thr231, and Thr181 of tau protein, respectively. Immunoblot analysis demonstrated that PKNalpha and PKC did not directly phosphorylate their sites, whereas GSK-3beta efficiently did so. Incubating GSK-3beta with PKNalpha or PKC subtypes inhibited subsequent GSK-3beta-induced AT8 and AT270 immunoreactivity. However, the constitutive active form of the GSK-3beta(S9A) mutant was almost totally inert to each enzyme. Incubating tau with PKNalpha increased the GSK-3beta-induced AT180 immunoreactivity, which was further enhanced when the S9A mutant was used instead of the wild type GSK-3beta. These results suggest that PKNalpha and PKC directly inhibit GSK-3beta activity at least in part by phosphorylating Ser9 of GSK-3beta, and that they indirectly suppress GSK-3beta-stimulated phosphorylation of tau at amino acids Ser202/Thr205 and Thr181, but enhanced phosphorylation at Thr231 through phosphorylation at other sites of tau.

A novel mutation at position +12 in the intron following exon 10 of the tau gene in familial frontotemporal dementia (FTD-Kumamoto)

Exonic and intronic mutations in the tau gene cause familial frontotemporal dementia and parkinsonism linked to chromosome 17. Here, we describe a new mutation, consisting of a C-to-T transition at position +12 of the intron following exon 10 of the tau gene in the Kumamoto pedigree, showing frontotemporal dementia. The mutation caused a marked reduction in melting temperature of the tau exon 10-splicing regulatory element RNA and a large increase in exon 10-containing transcripts. Brain tissue from affected individuals showed an abnormal preponderance of exon 10-containing transcripts that was reflected at the protein level by an overproduction of tau isoforms with four microtubule-binding repeats. Immunostaining revealed the presence of tau aggregates in degenerating neurons and glial cells. Isolated tau filaments had a twisted ribbon-like morphology and were made of hyperphosphorylated four-repeat tau isoforms. The additional mutation located dose to the splice-donor site of the intron following exon 10 of the tau gene supports the view that intronic mutations exercize their pathogenic effect by destabilizing RNA secondary structure.

[Brain abscess following thalamic hemorrhage: a case report]

Brain abscess following stroke is rare. We present a case of brain abscess which developed after hypertensive thalamic hemorrhage. A 51-year-old man had a left thalamic hemorrhage. Three months later, the patient was admitted to our hospital due to deterioration of right hemiparesis and motor aphasia. On admission, CT scan showed a ring-like high density area with peripheral edema in the left thalamus. T1-weighted magnetic resonance (MR) images revealed a large ring-enhanced lesion with surrounding edema in the same region. Laboratory examination demonstrated no signs of infectious disease. The patient's neurological state rapidly deteriorated 10 days after admission. Yellowish pus was aspirated during the emergent surgery. Bacteriological study of the pus revealed Staphylococcus Aureus. His symptoms improved after surgery followed by antibiotics therapy. The correct diagnosis prior to surgery was difficult in the present case because of lack of any signs of infection. Our case indicates that possibility of brain abscess should be taken into consideration as a rare differential diagnosis following intracerebral hemorrhage.

Intraoperative enzyme-amperometric monitoring of extracellular glutamate concentration with a dialysis electrode in ischemic human brain

Changes in the extracellular concentration of glutamate in the brain ([Glu]e) were monitored continuously by an enzyme-amperometric technique employing a dialysis electrode during ischemia caused by isolation of the brain tissue in rats and human patients. In the rat (n = 10), the dialysis electrode was placed in the frontal cortex and the frontal lobe was transected. A transient sharp increase in [Glu]e was frequently observed during the transection. A biphasic elevation (a rapid increase followed by a slowly continuing increase) subsequently occurred with a latent period of 1-3 min after the transection of the rat frontal lobe. In patients (n = 7), the dialysis electrode was placed in tumor-free cortical areas which were planned to be resected together with gliomas. Progressive increases in [Glu]e were observed in all of the patients as the isolation of the brain tissue progressed. A biphasic increase, similar to that seen in the rat, was identified in 2 patients in whom the cortical area surrounding the dialysis electrode was rapidly isolated. The present enzyme-amperometric technique employing a dialysis electrode appears to be useful for detecting the occurrence of potentially harmful ischemia and for securing minimal metabolic stress caused during various surgical manipulations.

Changes in cerebral blood oxygenation induced by deep brain stimulation: study by near-infrared spectroscopy (NIRS)

Previous studies have demonstrated that neural activation causes changes in cerebral blood oxygenation (CBO), i.e. increases in tissue levels of oxy-Hb and total-Hb with a decrease in deoxy-Hb concentration. It is unclear, however, whether neural activation always induces the same pattern of CBO changes or not. In the present study, employing a near-infrared spectroscopy (NIRS), we investigated the CBO changes in the frontal lobe induced by direct stimulation of the thalamus (Vim) or globus pallidus (GPi) in patients with Parkinson's disease or essential tremor. The results indicated that under conditions of neural activation in the frontal lobe, oxy-Hb and total-Hb increased in all 6 cases. Deoxy-Hb decreased in 2 cases during GPi stimulation, and increased in 4 cases during low frequency stimulation of the Vim. The above findings suggest that neural activation induces various patterns of CBO change, especially in deoxy-Hb. This implies that functional MRI based on the BOLD contrast may not consistently detect the area of neural activation.

Novel presenilin-1 mutation with widespread cortical amyloid deposition but limited cerebral amyloid angiopathy

OBJECTIVE

To clarify the phenotypic heterogeneity in deposition of amyloid beta (Abeta) in the parenchyma and in cerebral vessels of the brains of the patients having presenilin-1 (PS1) mutations. Mutations in PS1 induce increased production of Abeta42(43), resulting in an enhanced overall deposition of Abeta protein within the cerebral cortex.

METHODS

Sequence analysis of the PS1 gene of DNA from patients with early onset Alzheimer's disease, and immunostaining of brain tissues by end specific monoclonal antibodies against Abeta.

RESULTS

Sequence analysis disclosed a novel mutation (N405S) in the PS1 gene in a Japanese patient with early-onset Alzheimer's disease. Postmortem examination of one patient with N405S showed limited cerebral amyloid angiopathy, whereas postmortem examination of another Japanese patient with Alzheimer's disease with the E184D mutation disclosed severe cerebral amyloid angiopathy. The brains of both patients showed widespread neuritic plaques, neurofibrillary tangles, and neuronal loss. Immunostaining showed that Abeta42 was predominant over Abeta40 in neuritic plaques in both patients, whereas Abeta40 was found to be predominant over Abeta42 in cerebral amyloid angiopathy in the patient with E184D. However, most cortical vessels of the patient with N405S were not reactive with either of the antibodies.

CONCLUSION

The N405S mutation of PS1 is a major determinant of cortical Abeta deposition but not cerebral amyloid angiopathy in Alzheimer's disease.

[Clinical evaluation of accuracy of a new disposable pump (Syrinjector) for continuous epidural infusion]

We evaluated the accuracy of a new disposable pump (Coopdech Syrinjector), which employed the negative pressure made by injecting fluid into the pump for continuous epidural infusion. Thoracic epidural catheter was placed at the T6-T8 level prior to the lung surgery. The continuous epidural infusion of 0.25% bupivacaine at 2 or 3 ml.h-1 was started immediately after the surgery. The residual volume of bupivacaine was recorded. From our results, the injection speed of Syrinjector was satisfactory for clinical use of continuous epidural infusion of bupivacaine. However, when this pump is reused or the volume of the residual local anesthetics is less than 10 ml, the infusion accuracy will be potentially imprecise.

Improved efficiency of hypervolemic therapy with inhibition of natriuresis by fludrocortisone in patients with aneurysmal subarachnoid hemorrhage

OBJECT

To reduce the risk of ischemic complications in patients with subarachnoid hemorrhage (SAH), hypervolemic therapy is generally advocated. However, such conventional treatment cannot always ensure the maintenance of an effective intravascular volume expansion, because excessive natriuresis and osmotic diuresis occur after SAH. In this prospective study the authors examined the effects of inhibition of natriuresis with fludrocortisone acetate on intravascular volume expansion during hypervolemic therapy.

METHODS

Thirty patients with SAH were randomized and divided into two groups: controls (Group 1, 15 patients) and patients treated with 0.3 mg/day of fludrocortisone (Group 2, 15 patients). In all patients sodium and fluid intake levels were in excess of maintenance requirements in an attempt to maintain a positive water balance and a central venous pressure (CVP) of 8 to 12 cm H2O. The mean sodium and water intake levels for 14 days after SAH were significantly reduced by fludrocortisone in Group 2 (487+/-34.52 mEq/day and 5159.2+/-249.29 ml/day, respectively; p<0.01) compared with Group 1 (634.2+/-42.86 mEq/day and 6611.7+/-365.67 ml/day). Fludrocortisone significantly reduced the urinary sodium excretion (p<0.01) and urine volume (p<0.01) in parallel, and effectively prevented a negative shift in the sodium as well as water balance (p<0.01). The serum sodium level tended to decrease in Group 1, reaching 135 mEq/L on average, but not in Group 2 (p<0.01). Hyponatremia in Group 1 was always observed at the optimal range of CVP values. A decrease in serum potassium level within the range of 2.8 to 3.5 mEq/L was transiently noted in 11 patients (73.3%) of Group 2, but was easily corrected. Possible side effects of fludrocortisone, such as pulmonary edema, were not encountered.

CONCLUSIONS

Intravascular volume expansion in the presence of excessive natriuresis requires a large sodium and water intake and is often associated with hyponatremia. Inhibition of natriuresis with fludrocortisone can effectively reduce the sodium and water intake required for hypervolemia and prevent hyponatremia at the same time.

Activation of spinal N-methyl-D-aspartate receptors stimulates a nitric oxide/cyclic guanosine 3,5-monophosphate/glutamate release cascade in nociceptive signaling

BACKGROUND

Increasing evidence has suggested the possibility that the activation of N-methyl-D-aspartate (NMDA) receptors modulates spinal nociceptive transmission via a nitric oxide (NO)/cyclic guanosine 3',5'-monophosphate (cGMP) pathway. However, the existence and the role of an NO/cGMP pathway in the modulation of spinal nociceptive transmission has been unclear. The authors hypothesized that the activation of NMDA receptors stimulates an NO/cGMP pathway, and this pathway evokes glutamate release within the spinal cord, modulating spinal nociceptive transmission.

METHODS

The authors have examined the effects of an NO synthase inhibitor and a soluble guanylate cyclase inhibitor on the concentrations of NO metabolites (NO2-/NO3-) and glutamate in the cerebrospinal fluid after intrathecal perfusion of NMDA, concomitantly observing pain-related behavior (scratching, biting, and vocalization) in unanesthetized, free-moving rats using an intrathecal microdialysis method. The contents of cGMP in the dorsal horn were also measured using enzyme immunoassay method.

RESULTS

Intrathecal perfusion of NMDA produced pain-related behavior and increased glutamate and NO2-/NO3-concentrations in a dose-dependent manner. A competitive NMDA receptor antagonist, D,L-2-amino-5-phosphonovaleric acid, completely blocked the NMDA-induced responses. An NO synthase inhibitor, N(G)-monomethyl-L-arginine acetate, at a dose that completely blocked the increase in NO2-/NO3-, inhibited both the NMDA-induced pain-related behavior and the increase in glutamate concentration. In addition, a soluble guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazole[4,3-a]quinoxaline-1-one, also inhibited significantly NMDA-induced pain-related behavior and the increase in glutamate concentration. NMDA induced an increase in cGMP in the dorsal half of the spinal cord, which was blocked by N(G)-monomethyl-L-arginine acetate.

CONCLUSIONS

The results of this study support the hypothesis that the activation of NMDA receptors modulated pain-related behavior via an NO/cGMP/glutamate release cascade within the spinal cord.

A mutation in the microtubule-associated protein tau in pallido-nigro-luysian degeneration

We detected a missense mutation in exon 10 of tau that causes a substitution at codon 279 (N279K) in a Japanese patient with a familial background of parkinsonism and dementia originally described as pallido-nigro-luysian degeneration. This mutation is the same as one seen in a Caucasian family with pallido-ponto-nigral degeneration. The similarities between these two families suggest a common genetic mechanism that may account for the peculiar distribution of neuroglial degeneration with tauopathy.

Analgesic effect of intrathecal desipramine on carrageenan-induced thermal hyperalgesia in the rat

We examined if intrathecal desipramine, a selective norepinephrine reuptake inhibitor, would modulate peripheral inflammation-induced hyperalgesia. Rats were chronically implanted with a lumbar intrathecal catheter and paw withdrawal latency (PWL) to noxious heat stimuli was assessed. Unilateral hindpaw inflammation was induced by intraplantar carrageenan injection. Carrageenan injection significantly (P < 0.05) reduced PWL of the injected paw (from mean 11.4 (SEM 0.6) s to 3.5 (0.2) s, 3 h after carrageenan), but not of the contralateral side (from 11.6 (0.2) s to 11.2 (0.5) s). Intrathecal desipramine 10, 30, 60 and 100 micrograms, which did not produce analgesic effects in untreated rats, dose-dependently reversed the shortened PWL on the ipsilateral side (3.3 (0.2), 5.3 (0.4), 6.2 (0.3) and 9.6 (0.2) s, respectively) without affecting the contralateral side. Pretreatment with intrathecal yohimbine 10 micrograms did not antagonize the anti-hyperalgesic effects of desipramine (from 9.6 (0.2) to 9.8 (0.3) s). Our results suggest that the mechanism underlying the analgesic effect of desipramine on inflammation-induced hyperalgesia is unlikely to be inhibition of norepinephrine reuptake within the spinal cord.

c-Myc protein in the rabbit growth plate

Growth plates taken from five- to 20-week-old Japanese white rabbits were immunostained for c-Myc protein. This was localised both in the proliferating zone and upper hypertrophic zone at five weeks, whereas after ten weeks it was found mostly in the lower hypertrophic zone. The proliferating chondrocytes tended to show nuclear staining and the hypertrophic cells cytoplasmic staining, although the terminal hypertrophic chondrocytes sometimes expressed the protein in their nuclei. In the younger rabbits, c-Myc co-localised with proliferating cell nuclear antigen, whereas in the hypertrophic zone of older rabbits, it was present in some chondrocytes the nuclei of which also contained DNA breaks.

Our study suggests that, in the rabbit growth plate, c-Myc is associated with different cellular processes, depending on the age and the developmental stage of the chondrocytes.

c-Myc protein in the rabbit growth plate. Changes in immunolocalisation with age and possible roles from proliferation to apoptosis

Growth plates taken from five- to 20-week-old Japanese white rabbits were immunostained for c-Myc protein. This was localised both in the proliferating zone and upper hypertrophic zone at five weeks, whereas after ten weeks it was found mostly in the lower hypertrophic zone. The proliferating chondrocytes tended to show nuclear staining and the hypertrophic cells cytoplasmic staining, although the terminal hypertrophic chondrocytes sometimes expressed the protein in their nuclei. In the younger rabbits, c-Myc co-localised with proliferating cell nuclear antigen, whereas in the hypertrophic zone of older rabbits, it was present in some chondrocytes the nuclei of which also contained DNA breaks. Our study suggests that, in the rabbit growth plate, c-Myc is associated with different cellular processes, depending on the age and the developmental stage of the chondrocytes.

Intracisternal antisense oligonucleotide to growth associated protein-43 blocks the recovery-promoting effects of basic fibroblast growth factor after focal stroke

Focal infarction (stroke) of the lateral cerebral cortex of rats (including the sensorimotor cortex) produces deficits in sensorimotor function of the contralateral limbs that recover partially over time. In previous studies, we found that the intracisternal injection of basic fibroblast growth factor (bFGF), a potent neurotrophic growth factor, starting at 1 day after stroke, significantly enhanced recovery of sensorimotor function of the contralateral forelimb and hindlimb. Moreover, immunoreactivity (IR) for growth-associated protein-43 (GAP-43), a molecular marker of new axonal growth, was increased in the intact contralateral sensorimotor cortex following bFGF treatment. In the current study, we found that the intracisternal administration of antisense, but not missense, oligonucleotide to GAP-43 blocked the recovery-enhancing effects of bFGF and blocked the increase in GAP-43 IR in the contralateral cortex. These results suggest that upregulation of GAP-43 expression and consequent enhanced axonal sprouting in intact uninjured parts of the brain are likely mechanisms for the recovery-promoting effects of bFGF.