R1 hepatectomy with exposure of tumor surface for centrally located hepatocellular carcinoma

BACKGROUND

Hepatectomy with exposure of tumor surface (a special type of R1 resection) provides a chance of cure for selected patients with centrally located hepatocellular carcinoma (HCC) that is adherent to or compresses major vessels. However, the operative indications, safety, and patient outcomes are not well defined.

METHODS

We performed hepatectomy for removal of complex centrally located HCC using a selective and dynamic region-specific vascular occlusion technique. Between May 2006 and March 2012, a total of 118 patients underwent resection with exposure of tumor surface (exposure group) and 169 underwent conventional hepatectomy (without exposure of the tumor and vascular surface). The short- and long-term outcomes of patients were evaluated and compared.

RESULTS

The postoperative recovery of liver function was comparable between the two groups. Bile leakage occurred in five patients, all in the exposure group. The 1-, 3-, and 5-year recurrence-free survival rates were 74.4, 45.6, and 30.1 % in the exposure group and 80.9, 57.2, and 31.7 % in the control group (p = 0.041). Corresponding overall survival rates were 92.3, 70.3, and 44.9 % in the exposure group and 97.8, 81.4, and 53.1 % in the control group (p = 0.094).

CONCLUSIONS

Hepatectomy with exposure of tumor surface is technically demanding, but can be performed safely. It is also associated with a risk of tumor recurrence. Multidisciplinary combined therapy would be the solution and can contribute to improve overall survival.

[Analysis of risk factors of recurrence in patients with BCLC 0-A hepatocellular carcinoma after surgical resection]

OBJECTIVE

To analyze the risk factors of recurrence in patients with Barcelona Clinic Liver Cancer (BCLC) 0-A hepatocellular carcinoma (HCC) after surgical resection.

METHODS

Retrospective analyses were conducted for 218 patients undergoing surgical resection for BCLC 0-A HCC. A total of 17 clinicopathologic factors possibly influencing the recurrence and survival were selected. And multivariate analysis of these parameters was performed with Cox proportional hazard model. Survival analysis was performed with the Kaplan-Meier method.

RESULTS

The overall 1, 3, 5-year survival rates were 95.9%, 85.3% and 67.6% respectively. The median survival from time of primary resection was 35 months. The overall 1, 3 and 5-year disease-free survival (DFS) rates were 84.4%, 56.5% and 47.0% respectively. Univariate analysis showed that cirrhosis, positive alpha-fetoprotein (AFP), satellite nodules, involvement of hepatic capsule, tumor differentiation and microvascular invasion were associated with recurrence. And Cox multivariate analysis showed that satellite nodules, involvement of hepatic capsule and microvascular invasion were the independent risk factors for recurrence.

CONCLUSION

Surgical resection is a first option for BCLC 0-A HCC. Satellite nodules, involvement of hepatic capsule and microvascular invasion are independent risk factors for recurrence. Postoperative transarterial chemoembolization does not benefit the survival of patients with risk factors of recurrence.

[Initial comparison of regional ischemic preconditioning and hemi-hepatic vascular inflow occlusion in resection of hepatocellular carcinoma]

OBJECTIVE

To evaluate preliminarily the clinical efficacy of two types of hepatic inflow occlusion in hepatectomy for hepatocellular carcinoma (HCC).

METHODS

A total of 54 patients with HCC who underwent hepatectomy were divided into two groups: RIP group (regional ischemic preconditioning with continuous clamping, n=15) and HHV group (hemi-hepatic vascular inflow occlusion, n=39). HHV was performed by placing a clamp on the right hepatic artery and right portal vein, and was maintained until the liver resection was completed. In the RIP group, HHV was preceded by a 5-min period of ischemia followed by 5 min of reperfusion. The clinical indicators of the two groups were compared.

RESULTS

The volume of intraoperative blood loss had significant difference between the two groups (P=0.039). One case (6.7%) in the RIP group and 17 cases (43.6%) in the HHV group received postoperative blood transfusion, showing a significant difference (P=0.010). No postoperative 30-day mortality happened in all patients. No significant differences were found between the two groups in hospital stay or postoperative morbidity, including hepatic insufficiency, infection, ascites, pleural effusion, cardiopulmonary complications and intestinal ventilation time (P>0.05 for all).The RIP group had a significantly higher PTA level at postoperative days 3 and 5 (P<0.001). Although no significant differences were found between the two groups regarding total bilirubin, albumin, prealbumin and aminotransferase (P>0.05) during any postoperative stage, the ALT recovered to normal level in 5 patients (33.3%) of the RIP group and only in one case (2.7%) of the HHV group, with a significant difference between the two groups (P=0.006).

CONCLUSION

The results of this study indicate that regional ischemic preconditioning may have better hemostatic effect on hepatectomy, can reduce postoperative blood transfusion and promote early recovery of liver function than hemi-hepatic vascular inflow occlusion.

[Relationship between CCL20/CCR6/Th17 axis and vascular invasion and metastasis in patients with primary hepatocellular carcinoma]

OBJECTIVE

To investigate the role of CCL20/CCR6/Th17 axis in vascular invasion and metastasis of primary hepatocellular carcinoma (HCC).

METHODS

Expression levels of CCL20 mRNA in the normal human liver cell line L-02, and human hepatocellular carcinoma cell lines Hep3B, Huh7 and HepG2 were quantified by using SYBR green real time PCR. CCL20 secretions from these cell lines were quantified by using ELISA. The chemotactic effect of HCC cell line Hep3B on human peripheral blood mononuclear cells was determined by using transwell chemotaxis assay. Pre-therapy serum levels of IL-1α, IL-1β, IL-6, IL-8, IL-10, IL-17, IL-23, IFN-γ, TNF-α and CCL20 in 93 patients with HCC were measured by using 9-plex array and ELISA. All the patients were chronic hepatitis B virus associated HCC, and 51 cases were those with vascular invasion and metastasis (metastasis group) and 42 cases were not (non-metastasis group). CCL20 and CCR6 mRNA expressions in the HCC and tumor-adjacent tissues were determined by using SYBR Green real time PCR in 41 patients, among them, 20 cases were from the group of patients with metastasis and 21 cases were from the group of patients without metastasis. The CCL20 expression was further determined by immunohistochemistry.

RESULTS

The HCC cell lines expressed and secreted higher amount of CCL20, which effectively recruited CCR6(+) T cells. Pre-therapy serum levels of CCL20 in 93 HCC patients were (38.2 ± 28.4)pg/ml, significantly increased than those with benign hepatic hemangiomas [(7.8 ± 17.8)pg/ml, P < 0.01]. In addition, the serum levels of CCL20 were positively correlated with the tumor diameters in HCC patients (r = 0.32, P = 0.0018). CCL20 was dominantly expressed in the cytoplasm in HCC cells, and it was also expressed by some infiltrating immune cells. The mRNA expression levels of CCL20 of the tumor tissues were significantly higher than that in the tumor-adjacent tissues (P < 0.05). Multivariate logistic regression analysis showed that serum levels of IL-17 and CCL20 were independent risk factors of metastasis in HCC patients (P < 0.05 for both). CCL20 mRNA showed no statistically significant differences between patients with metastasis and without metastasis in both tumor tissues and tumor-adjacent tissues (P > 0.05 for both). But the patients with metastasis showed significantly higher expressions of CCR6 both in their tumor [5.75 (1.79, 19.13)]and tumor-adjacent tissues [7.99 (4.49, 19.54)] than those with non-metastasis [1.69 (0.76, 2.87) and 3.58 (1.84, 4.32), P < 0.05 for both].

CONCLUSION

CCL20/CCR6/Th17 axis may promote vascular invasion and metastasis hepatocellular carcinoma.

The plasma osteoprotegerin level and osteoprotegerin expression in renal biopsy tissue are increased in type 2 diabetes with nephropathy

OBJECTIVE

To investigate the plasma osteoprotegerin level and osteoprotegerin expression in renal biopsy tissue in type 2 diabetes with nephropathy.

METHODS

Plasma osteoprotegerin level was measured by enzyme-linked immunoassay in 48 type 2 diabetes with normoalbuminuria, 48 patients with microalbuminuria, 44 patients with macroalbuminuria and 40 healthy persons. Part of diabetes patients with nephropathy were performed kidney biopsy by ultrasound guide. The osteoprotegerin expression in kidney biopsy tissue is examined by immunohistochemistry.

RESULTS

The plasma osteoprotegerin levels were significantly elevated in patients with microalbuminuria (3.73±0.75 ng/l) and macroalbuminuria (4.68±0.82 ng/l) as compared with patients with normoalbuminuria (2.71±0.69 ng/l) and control subjects (2.11±0.42 ng/l). And the plasma osteoprotegerin level in macroalbuminuric group was also higher than that in microalbuminuria group. The plasma osteoprotegerin level had a positive correlation with the fasting plasma glucose (FPG), 2-h plasma glucose (2hPG), glycohemoglobinA1c (HbA1C), high sensitive C-reactive protein (hsCRP) and log(UAER). Multivariate regression analysis revealed that plasma osteoprotegerin level was an independent factor associated with albuminuria in type 2 diabetes. The immunohistochemistry results showed that positive immunostaining for osteoprotegerin was observed in the renal tubule cells of biopsy and not in glomerulus, and the osteoprotegerin expression was higher in macroalbuminuria group than that in microalbuminuria group.

CONCLUSIONS

The plasma osteoprotegerin level and the osteoprotegerin expression in renal tubule cells of biopsy tissue were increased in nephropathy of type 2 diabetes. This finding supports the growing concept that osteoprotegerin may act as an important regulatory molecule in the angiopathy, and particularly, that it may be involved in the occurrence and development of nephropathy in type 2 diabetes.

[Analysis of risk factors of recurrence of hepatocellular carcinoma after control of surgical-risk-factors]

OBJECTIVE

R0 resection, Pringle maneuver, intraoperative massive blood loss and perioperative blood transfusion have been definitely recognized to be surgery-related risk factors of recurrence of hepatocellular carcinoma (HCC) in recent years. The aim of this study was to investigate the post-operative risk factors of recurrence of HCC after control of the above mentioned risk factors.

METHODS

288 consecutive HCC patients underwent hepatectomy with selective regional vascular occlusion by the same surgical team. All patients had R0 resection, less than 800 ml blood loss and had no perioperative blood transfusion. The clinical and pathological factors were retrospectively analyzed.

RESULTS

The total 1-year, 3-year and 5-year disease-free survival rate (DFS) was 74.9%, 49.3% and 34.3%, respectively. Univariate analysis showed that serum gamma-glutamyl-transferase rise >55 U/L, AFP > 400 ng/ml, tumor diameter >5 cm, multi-focal lesions, satellite nodules, poor differentiation, microvascular invasion, envelope invasion, postoperative liver insufficiency, preoperative TACE and postoperative TACE were significantly associated with poor DFS. Multivariate Cox analyses revealed that tumor size, satellite nodules, poor differentiation, microvascular invasion and postoperative liver insufficiency were independent prognostic predictors associated with shorter DFS. According to the results of multivariate Cox analysis of 158 cases with at least one risk factor selected from the whole group, further analysis demonstrated that perioperative TACE was not significantly associated with the median DFS (P > 0.05 for all).

CONCLUSIONS

Selective regional vascular occlusion may effectively control the surgiury-related risk factors of recurrence of HCC. Tumor features are the main affecting factors of DFS. Preoperative or postoperative TACE do not benefit patients who received curative resection.

[Comparison of the prognosis between male and female patients with hepatocellular carcinoma after hepatectomy]

OBJECTIVE

Hepatocellular carcinoma (HCC) is sexually dimorphic, with a significantly higher incidence in male. But it is not clear whether the women have a better prognosis than the men. The present study aimed to compare the short and long-term outcomes, postoperative recurrence and survival in female and male patients with HCC after hepatectomy.

METHODS

Clinicopathological data of retrospective analysis was performed on 40 female and matched 40 male HCC patients treated by hepatectomy in Cancer Hospital of Chinese Academy of Medical Sciences between May 2006 and May 2012 were retrospectively reviewed in this study. Patients were paired in terms of age, chronic hepatitis, Child-Pugh class, tumor size, histological differentiation, presence of satellite nodules and resection margin.

RESULTS

Hepatectomy was successfully performed in all 80 cases. There was no significant difference in intraoperative variables and postoperative outcomes between the female and male groups except the level of total bilirubin. The 1-, 3- and 5-year recurrence-free survival rates were 76.7%, 47.4% and 29.7% in the female group and 63.8%, 30.0% and 25.0% in the male group (P = 0.12). Corresponding overall survival rates were 92.2%, 81.5% and 55.4% in the female group and 97.4%, 55.2% and 39.0% in the male group (P = 0.04).

CONCLUSION

Certain gender differences might exist in HCC patients after hepatecomy, favoring females in the overall survival and the tolerance for liver injury.

Loss of cell adhesion molecule CHL1 improves homeostatic adaptation and survival in hypoxic stress

Close homologue of L1 (CHL1) is a transmembrane cell adhesion molecule that is critical for brain development and for the maintenance of neural circuits in adults. Recent studies revealed that CHL1 has diverse roles and is involved in the regulation of recovery after spinal cord injury. CHL1 expression was downregulated in the cerebral cortex, hypothalamus, and brain stem after the induction of acute hypoxia (AH). In the current study, we sought to address the role of CHL1 in regulating homeostasis responses to hypoxia using CHL1-knockout (CHL1^−/−) mice. We found that, compared with wild-type littermates, CHL1^−/− mice showed a dramatically lower mortality rate and an augmented ventilatory response after they were subjected to AH. Immunofluorescence staining revealed that CHL1 was expressed in the carotid body (CB), the key oxygen sensor in rodents, and CHL1 expression level in the CB as assayed by western blot was decreased after hypoxic exposure. The number of glomus cells and the expression of tyrosine hydroxylase (a marker for glomus cells) in the CB of CHL1^−/− mice appeared to be increased compared with CHL1^+/+ mice. In addition, in the ex vivo CB preparation, hypoxia induced a significantly greater afferent nerve discharge in CHL1^−/− mice compared with CHL1^+/+ mice. Furthermore, the arterial blood pressure and plasma catecholamine levels of CHL1^−/− mice were also significantly higher than those of CHL1^+/+ mice. Our findings first demonstrate that CHL1 is a novel intrinsic factor that is involved in CB function and in the ventilatory response to AH.

The effects of post-stroke upper-limb training with an electromyography (EMG)-driven hand robot

Loss of hand function and finger dexterity are main disabilities in the upper limb after stroke. An electromyography (EMG)-driven hand robot had been developed for post-stroke rehabilitation training. The effectiveness of the hand robot assisted whole upper limb training was investigated on persons with chronic stroke (n=10) in this work. All subjects attended a 20-session training (3-5times/week) by using the hand robot to practice object grasp/release and arm transportation tasks. Significant motor improvements were observed in the Fugl-Meyer hand/wrist and shoulder/elbow scores (p<0.05), and also in the Action Research Arm Test and Wolf Motor Function Test (p<0.05). Significant reduction in spasticity of the fingers as was measured by the Modified Ashworth Score (p<0.05). The training improved the muscle co-ordination between the antagonist muscle pair (flexor digitorum (FD) and extensor digitorum (ED)), associated with a significant reduction in the ED EMG level (p<0.05) and a significant decrease of ED and FD co-contraction during the training (p<0.05); the excessive muscle activities in the biceps brachii were also reduced significantly after the training (p<0.05).

Secretory/releasing proteome-based identification of plasma biomarkers in HBV-associated hepatocellular carcinoma

For successful therapy, hepatocellular carcinoma (HCC) must be detected at an early stage. Herein, we used a proteomic approach to analyze the secretory/releasing proteome of HCC tissues to identify plasma biomarkers. Serum-free conditioned media (CM) were collected from primary cultures of cancerous tissues and surrounding noncancerous tissues. Proteomic analysis of the CM proteins permitted the identification of 1365 proteins. The enriched molecular functions and biological processes of the CM proteins, such as hydrolase activity and catabolic processes, were consistent with the liver being the most important metabolic organ. Moreover, 19% of the proteins were characterized as extracellular or membrane-bound. For validation, secretory proteins involved in transforming growth factor-β signaling pathways were validated in plasma samples. Alphafetoprotein (AFP), metalloproteinase (MMP)1, osteopontin (OPN), and pregnancy-specific beta-1-glycoprotein (PSG)9 were significantly increased in HCC patients. The overall performance of MMP1 and OPN in the diagnosis of HCC remained greater than that of AFP. In addition, this study represents the first report of MMP1 as a biomarker with a higher sensitivity and specificity than AFP. Thus, this study provides a valuable resource of the HCC secretome with the potential to investigate serological biomarkers. MMP1 and OPN could be used as novel biomarkers for the early detection of HCC and to improve the sensitivity of biomarkers compared with AFP.

Curcumin acts via transient receptor potential vanilloid-1 receptors to inhibit gut nociception and reverses visceral hyperalgesia

BACKGROUND

An antinociceptive effect has been reported for curcumin in animal models and in humans, but the molecular mechanisms of curcumin's effect remain undefined. In this study, we explored the possibility that curcumin inhibit visceral nociception via antagonizing the transient receptor potential vanilloid-1 (TRPV1) receptor.

METHODS

The effects of curcumin were explored using two experimental models: viscero-motor response (VMR) to colorectal distension (CRD) in rats and jejunal afferent firing in the ex vivo mouse jejunum preparations [TRPV1 knockout (KO) and wild-type mice, naive and trinitrobenzene sulfonic acid (TNBS)-treated Kunming mice]. In addition, capsaicin-induced calcium transients and whole-cell currents were examined in acutely dissociated dorsal root ganglia (DRG) neurons.

KEY RESULTS

In the anesthetized rat, curcumin (4 mg kg(-1)  min(-1) for 3 min) caused a marked and rapidly reversible inhibition of CRD-induced VMRs. In the mouse jejunum, the mesenteric afferent nerve response to ramp distension was attenuated by curcumin (3, 10 μmol L(-1) ), an effect that was significantly reduced in TRPV1 KO mice compared with wild-type (WT) controls. Moreover, in WT mice, curcumin (1-30 μmol L(-1) ) was found to inhibit the afferent responses to capsaicin in a concentration-dependent manner. Trinitrobenzene sulfonic acid-induced hypersensitivity of jejunal afferents was also attenuated by curcumin. Curcumin potently inhibited capsaicin-induced rise in intracellular calcium and inward currents in mouse or rat DRG neurons.

CONCLUSIONS & INFERENCES

Our results provide strong evidence that curcumin inhibit visceral nociception via antagonizing TRPV1 and may be a promising lead for the treatment of functional gastrointestinal diseases.

Coordinated upper limb training assisted with an electromyography (EMG)-driven hand robot after stroke

An electromyography (EMG)-driven hand robot had been developed for post-stroke rehabilitation training. The effectiveness of the hand robot assisted whole upper limb training on muscular coordination was investigated on persons with chronic stroke (n=10) in this work. All subjects attended a 20-session training (3-5 times/week) by using the hand robot to practice object grasp/release and arm transportation tasks. Improvements were found in the muscle co-ordination between the antagonist muscle pair (flexor digitorum and extensor digitorum) as measured by muscle co-contractions in EMG signals; and also in the reduction of excessive muscle activities in the biceps brachii. Reduced spasticity in the fingers was also observed as measured by the Modified Ashworth Score.

Elevated pretherapy serum IL17 in primary hepatocellular carcinoma patients correlate to increased risk of early recurrence after curative hepatectomy

Background and Aims

Primary hepatocellular carcinoma (HCC) is usually presented in inflamed fibrotic/cirrhotic liver with extensive lymphocyte infiltration. We examined the associations between the HCC early recurrence and alterations in serum levels of inflammatory cytokines.

Methods

A cohort of 105 HCC patients with chronic hepatitis B virus infection were included. Pre-therapy, we quantified their serum concentrations of Th1-, Th2-, Th17-, Treg-related, and other cytokines that have been reported to be associated with poor prognosis in human cancers. IL17-producing T-cells were generated in vitro from HCC patients and co-cultured with HCC cell lines separated by a 0.4 µM transwell.

Results

All the 105 cases of HCC patients had liver cirrhosis. The patients who suffered from HCC early recurrence had higher pre-therapy serum levels of IL17 and lower levels of IL10 than those who did not suffer from recurrence after curative hepatectomy. After adjustment for general tumor clinicopathological factors, elevated serum levels of IL17 (≥0.9 pg/ml) was found to be an independent risk factor for HCC early recurrence with a hazard ratio of 2.46 (95%CI 1.34–4.51). Patients with bigger tumors (>5 cm in diameter) and elevated serum levels of IL17 had the highest risk of early recurrence as compared to those with only one of these factors (P = 0.009) or without any (P<0.001). These factors showed similar effects on the HCC patient overall survival. Intrahepatic infiltrated T-cells in HCC patients were identified as the major IL17-producing cells. Proliferation of HCC cells, QGY-7703, was augmented QGY-7703, was augmented in the presence of IL17-producing T-cells. This effect diminished after neutralizing antibody against human IL17A or TNFα was included.

Conclusion

Both tumors and IL17 from liver infiltrated T-cells contributed to HCC early recurrence and progression after curative resection. Pre-therapy serum IL17 levels may serve as an additional indicator for predicting high-risk patients.

An EMG-driven exoskeleton hand robotic training device on chronic stroke subjects: task training system for stroke rehabilitation

An exoskeleton hand robotic training device is specially designed for persons after stroke to provide training on their impaired hand by using an exoskeleton robotic hand which is actively driven by their own muscle signals. It detects the stroke person's intention using his/her surface electromyography (EMG) signals from the hemiplegic side and assists in hand opening or hand closing functional tasks. The robotic system is made up of an embedded controller and a robotic hand module which can be adjusted to fit for different finger length. Eight chronic stroke subjects had been recruited to evaluate the effects of this device. The preliminary results showed significant improvement in hand functions (ARAT) and upper limb functions (FMA) after 20 sessions of robot-assisted hand functions task training. With the use of this light and portable robotic device, stroke patients can now practice more easily for the opening and closing of their hands at their own will, and handle functional daily living tasks at ease. A video is included together with this paper to give a demonstration of the hand robotic system on chronic stroke subjects and it will be presented in the conference.

Hyaluronan tetrasaccharide in the cerebrospinal fluid is associated with self-repair of rats after chronic spinal cord compression

The objective of this study was to explore changes in hyaluronan levels in the cerebrospinal fluid (CSF) in a spinal cord compression model, to investigate whether hyaluronan tetrasaccharide was involved in this process, and to test the effects of hyaluronan tetrasaccharide on neuron and oligodendrocyte repair. We developed a chronic spinal cord compression model with various sizes of polymer sheets (1.5×0.7×0.3 mm(3); 5×1.5×0.7 mm(3)) that were implanted microsurgically underneath the C(5-6) laminae. The rats were divided into three groups: a sham group, a mildly compressed (MC) group, and a widely compressed (WC) group. Locomotor functional evaluations revealed that the behavioral function of the MC and WC groups dropped to their lowest level from the fourth to fifth week and gradually recovered thereafter. The hyaluronan levels in the CSF gradually increased after spinal cord compression. Furthermore, hyaluronan tetrasaccharide was involved in the hyaluronan change. In addition, we found that nuclear factor kappa B (NF-κB) and cellular inhibitor-of-apoptosis protein 2 (c-IAP(2)) were co-expressed in neurons and oligodendrocytes, and caspase-3 expression gradually decreased in the compression model. The brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) expression was upregulated in astrocytes at the fourth week post-compression. Hyaluronan tetrasaccharide (HA(4)) induced NF-κB and c-IAP(2) to suppress the H(2)O(2)-induced apoptosis in primary neuronal cultures and increased BDNF and VEGF expression in astrocytic cultures in vitro. These findings suggest that HA(4) in the CSF may associate with behavioral recovery by increasing the levels of NF-κB, c-IAP(2), and neurotrophic factors after chronic spinal cord compression.

Purinergic contribution to small intestinal afferent hypersensitivity in a murine model of postinfectious bowel disease

Increased sensitivity of the afferent innervation of the gastrointestinal tract reportedly underlies symptoms of discomfort and pain in functional bowel disorders. The present investigation aimed to examine whether the purinergic P2X(2) and P2X(3) receptor subunits contribute to the mechanosensitivity of small intestinal afferents in normal mice and in a murine model of postinfectious gut dysfunction. Mesenteric afferent nerve activity was recorded in a mouse jejunum preparation maintained in vitro. As has been shown previously, ramp distension of the jejunal segment evoked biphasic afferent discharge, reflecting activation of low and high threshold fibres. The average pressure-afferent response curve in mice deficient in both P2X(2) and P2X(3) subunits (n = 14) was not significantly different from that of the wild-type control preparations (n = 13). Application of pyridoxal 5-phosphate 6-azophenyl-2 ,4-disulphonic acid (PPADS) (30 micromol L(-1)), a P2X and P2Y antagonist, or 2,4,6-trinitrophenol-adenosine 5'-triphosphate (10 micromol L(-1)), an antagonist selective for homomeric P2X(3) and heteromeric P2X(2/3) receptors, had no effect on the averaged pressure-afferent response curve in wild-type animals. In Trichinella spiralis-infected mice, the magnitude of mesenteric afferent responses to jejunal distension was greater at day 21 and day 56 postinfection compared with the sham control preparations demonstrating the development of afferent hypersensitivity. PPADS had no significant effect upon mechanically evoked afferent discharge rates in sham treated preparations (n = 5), but significantly inhibited afferent sensitivity to jejunal distension in preparations from mice at day 21 (n = 6) and day 56 (n = 7) postinfection. These results suggest that purinergic mechanisms play no role in mechanosensory transduction in the normal small intestine but contribute significantly to postinfectious mechano-hypersensitivity.

Bladder afferent sensitivity in wild-type and TRPV1 knockout mice

Understanding bladder afferent pathways may reveal novel targets for therapy of lower urinary tract disorders such as overactive bladder syndrome and cystitis. Several potential candidate molecules have been postulated as playing a significant role in bladder function. One such candidate is the transient receptor potential vanilloid 1 (TRPV1) ion channel. Mice lacking the TRPV1 channel have altered micturition thresholds suggesting that TRPV1 channels may play a role in the detection of bladder filling. The aim of this study was therefore to investigate the role of TRPV1 receptors in controlling bladder afferent sensitivity in the mouse using pharmacological receptor blockade and genetic deletion of the channel. Multiunit afferent activity was recorded in vitro from bladder afferents taken from wild-type (TRPV+/+) mice and knockout (TRPV1-/-) mice. In wild-type preparations, ramp distension of the bladder to a maximal pressure of 40 mmHg produced a graded increase in afferent activity. Bath application of the TRPV1 antagonist capsazepine (10 mum) caused a significant attenuation of afferent discharge in TRPV1+/+ mice. Afferent responses to distension were significantly attenuated in TRPV1-/- mice in which sensitivity to intravesical hydrochloric acid (50 mm) and capsaicin (10 microm) were also blunted. Altered mechanosensitivity occurred in the absence of any changes in the pressure-volume relationship during filling indicating that this was not secondary to a change in bladder compliance. Single-unit analysis was used to classify individual afferents into low-threshold and high-threshold fibres. Low threshold afferent responses were attenuated in TRPV1-/- mice compared to the TRPV1+/+ littermates while surprisingly high threshold afferent sensitivity was unchanged. While TRPV1 channels are not considered to be mechanically gated, the present study demonstrates a clear role for TRPV1 in the excitability of particularly low threshold bladder afferents. This suggests that TRPV1 may play an important role in normal bladder function.

Survivin expression in ovarian cancer

AIM

To examine the expression of survivin in benign ovarian tumors, ovarian carcinomas of different stages.

METHODS

We screened the expression of survivin mRNA by reverse transcription polymerase chain reaction in 114 ovarian tissue samples. Quantitative real-time PCR was used to estimate survivin mRNA levels in the samples with positive survivin expression.

RESULTS

No survivin mRNA was expressed in all normal ovarian specimens, while it appeared in 73% of ovarian carcinomas, 47% of borderline ovarian carcinomas and 19% of benign ovarian tumors. The survivin mRNA expression rate was positively associated with clinical stage (P = 0.026) and differentiation grade (P = 0.049). There was notably statistically significant difference in the survivin mRNA expression rate dependent on different histological types (serous, mucinous, endometrioid, P = 0.008), but not - dependent on lymph node metastasis (P = 0.921) and ascites (P = 0.87). In tissues with positive expression of survivin, we also found that mean survivin mRNA expression levels were higher in ovarian carcinomas than that in benign ovarian tumors and borderline ovarian carcinoma tissues (P < 0.001). Among ovarian carcinomas, the high survivin mRNA expression levels correlated with the clinical stages, differentiation grade, lymph node metastasis, but not - with ascites and histological type.

CONCLUSION

Our study suggest that survivin is associated with progression of ovarian carcinoma.

[Hand-assisted laparoscopic surgery in colorectal carcinoma resection: a report of 14 cases]

OBJECTIVE

To study the application of hand-assisted laparoscopic surgery (HALS) in colorectal carcinoma resection.

METHODS

Fourteen patients with colorectal carcinoma underwent resection by HALS.

RESULTS

Hand-assisted laparoscopic right hemicolectomy was performed in 6 of 8 ascending colon cancer patients, spending an average of 160 minutes (110 to 220 minutes) for the procedure. The amount of bleeding was 40 approximately 100 ml. Bowel sounds resumed in 36 approximately 72 hours after the operation. The average interval between the operation and patients' discharge was 8 days (7 to 12 days). For 2 patients the surgeons had to resort to laparotomy. All patients received postoperative chemotherapy. Hand-assisted laparoscopic abdominoperineal resection was performed in 5 of 6 patients with lower rectal cancer, with the average duration of 180 minutes (120 to 270 minutes), with bleeding of 40 to 80 ml. Bowel sounds resumed within 24 to 72 hours and the average discharge interval was 14 days (12 to 18 days). The urinary catheter in 6 patients was removed in 7 to 8 days after the operation. All patients with rectal carcinoma received postoperative chemotherapy and radiotherapy. One patient was shifted to laparotomy because of extensive adhesion in the pelvic cavity. Four of 11 patients treated by HALS experienced slight pain in the incision. No other complications were observed in any of the patients. Remote results await further follow-up.

CONCLUSION

Hand-assisted laparoscopic surgery in the treatment of colorectal carcinoma, a safe and simple procedure, not only ensures the clearance of tumor, but also reduces operative trauma and hastens recovery.

[Diagnosis and treatment of 178 patients with carcinoma of the head of pancreas]

OBJECTIVE

To improve the diagnosis and treatment of carcinoma of head of pancreas.

METHODS

A retrospective study was carried out to evaluate 178 patients suffering from carcinoma of head of pancreas.

RESULTS

Pain in the epigastrium and obstructive jaundice were observed in 70% and 74.2% of these 178 patients, both of which were of significance (P < 0.001) between stage I, II and stage III, IV disease. Only 18% of patients had pain in the back, 81.3% of whom belonged to the stage IV category. The detection rate of the tumor by B-ultrasound, CT and MRI were 74.2%, 87.3% and 85.5%, respectively. The success rate of pancreatoduodenectomy was 10.1%. The postoperative 1-, 3- and 5-year survival rates were 67.5%, 36% and 5.6%. Internal drainage was performed in 115 patients. The median survival time was 7 months in patients with unresectable tumor who received radiotherapy and/or chemotherapy.

CONCLUSION

Pain in the epigastrium and obstructive jaundice are the most common symptoms. Hyperglycemia is the most common complication. Pain in the back implies an advanced lesion. CT is the most important way of diagnosis and the combination of B-ultrasound, CT and MRI may improve the rate of diagnosis up to 96.6%. By now, pancreaticoduodenectomy is still the only effective treatment for the carcinoma of head of pancreas and internal drainage is an important palliative measure.

Neurophysiological evidence of spared upper motor conduction fibers in clinically complete spinal cord injury: discomplete SCI in rats

Motor evoked potentials (MEP) were recorded and characterized by epidural electrodes (scMEP) and extracellular microelectrodes (exMEP) on T(13) level from 10 normal rats and 40 rats with chronic spinal cord injury (SCI). The spinal cord of 40 anesthetized rats were injured with various severity (sham, 35, 70, and 100 g/cm impact injury) at T(8)-T(9) cord using Allen's drop model. The incline plane and Tarlov techniques were investigated to assess clinical neurological function. MEPs in the normal rats elicited by applying transcortical suprathreshold stimulation consisted of 3-4 early negative peaks (N(1), N(2), N(3), N(4)) followed by several late waves. The N(1) and N(2) peaks had their maximal amplitudes in the anterior and ventrolateral funiculus, respectively, irrespective of the polarity of stimulation, which indicated that these impulses were conducted mostly through the extrapyramidal pathways. The 100 g/cm impact injury or transection of the cord caused abolishment of the MEP signals distal to the lesion, whereas the 35 g/cm injury resulted in a latency shift and amplitude decrement of the MEP peaks. Out of 20 rats with 70 g/cm injuries, 18 showed clinically paraplegia. Among them, seven had neurophysiological evidence of residual conduction pathways through the injured cord segment, such as the presence of N(1) and N(2) peaks in scMEP or exMEP. After 4-aminopyridine (4-AP) administration (1 mg/kg), the amplitude of spared exMEP increased significantly and spread more widely. These results suggest that MEPs evoked by transcortical stimulation travel mostly in the extrapyramid tract. The present study provides further direct and objective electrophysiological evidences of spared functional axons after discomplete SCI, since many other studies on this field have achieved similar results previously. Furthermore, pharmaceutical treatment with 4-AP or other K(+) channel blocking agents proved to be a potential therapeutic strategy for patient with chronic SCI.

P2X3 knock-out mice reveal a major sensory role for urothelially released ATP

The present study explores the possible involvement of a purinergic mechanism in mechanosensory transduction in the bladder using P2X(3) receptor knock-out (P2X(3)-/-) and wild-type control (P2X(3)+/+) mice. Immunohistochemistry revealed abundant nerve fibers in a suburothelial plexus in the mouse bladder that are immunoreactive to anti-P2X(3). P2X(3)-positive staining was completely absent in the subepithelial plexus of the P2X(3)-/- mice, whereas staining for calcitonin gene-related peptide and vanilloid receptor 1 receptors remained. Using a novel superfused mouse bladder-pelvic nerve preparation, we detected a release of ATP proportional to the extent of bladder distension in both P2X(3)+/+ and P2X(3)-/- mice, although P2X(3)-/- bladder had an increased capacity compared with that of the P2X(3)+/+ bladder. The activity of multifiber pelvic nerve afferents increased progressively during gradual bladder distension (at a rate of 0.1 ml/min). However, the bladder afferents from P2X(3)-/- mice showed an attenuated response to bladder distension. Mouse bladder afferents of P2X(3)+/+, but not P2X(3)-/-, were rapidly activated by intravesical injections of P2X agonists (ATP or alpha,beta-methylene ATP) and subsequently showed an augmented response to bladder distension. By contrast, P2X antagonists [2',3'-O-(2,4,6-trinitrophenyl)-ATP and pyridoxal 5-phosphate 6-azophenyl-2',4'-disulfonic acid] and capsaicin attenuated distension-induced discharges in bladder afferents. These data strongly suggest a major sensory role for urothelially released ATP acting via P2X(3) receptors on a subpopulation of pelvic afferent fibers.

Coexpression of P2X(3) and P2X(2) receptor subunits in varying amounts generates heterogeneous populations of P2X receptors that evoke a spectrum of agonist responses comparable to that seen in sensory neurons

Using voltage-clamp procedures on Xenopus oocytes, agonist-evoked ionic currents by P2X receptors resulting from the coexpression of P2X(2) and P2X(3) subunits were compared against the agonist responses of homomeric P2X(2) and P2X(3) receptors. With the quantity of P2X(3) mRNA kept constant and quantity of P2X(2) mRNA progressively increased, expressed P2X receptors changed from a P2X(3)-like receptor to a P2X(2)-like receptor. In all cases, however, agonist-evoked responses comprised biphasic (fast and slow) currents-the former showing the properties of P2X(3) receptors and latter consistent with the presence of P2X(2) and P2X(2/3) receptors. Using desensitization procedures, the P2X(3)-like fast current was selectively removed to allow the slow current to be studied in isolation. P2X(2/3) receptors were then characterized by slowly inactivating inward currents that were reproducible within 30 s of washout and whose pharmacological profile [selective agonists, Ap(5)A > alpha,beta-methylene ATP >> beta,gamma-methylene ATP > UTP; antagonists, TNP-ATP >> suramin > or = Reactive blue-2 (RB-2)] contrasted with the profile of P2X(2) receptors (Ap(5)A, alpha,beta-methylene ATP, beta,gamma-methylene ATP, and UTP inactive; antagonists, RB-2 > TNP-ATP > suramin). Thus, our experiments reveal that coexpression of two P2X subunits, which of themselves can generate functional homomeric receptors, results in a complex population of heterogeneous P2X receptors-in this case P2X(2), P2X(3), and P2X(2/3) receptors. Depending on the relative levels of P2X subunit coexpression, the operational profile of the resultant P2X receptors can change from one phenotype to another. This spectrum may explain the variability of agonist responses in small sensory neurons that also express P2X(2) and P2X(3) subunits in different amounts.

Recording of spared motor evoked potentials and its augmentation by 4-aminopyridine in chronic spinal cord-injured rats

OBJECTIVE

To research the direct electrophysiological evidence of discomplete spinal cord injury (SCI) and the effect of 4-aminopyridine on it.

METHODS

Motor evoked potentials (MEPs), both spinal cord recorded MEPs (scMEPs) and extracellularly recorded MEPs (exMEPs) were recorded and characterized on a T13 epidural electrode (scMEPs) and an extracellular microelectrode (exMEPs) for 10 normal rats and 40 rats with lesions of various severity (sham, 35 g.cm force (gcf), 70 gcf, 100 gcf impact injury) at the T8-T9 cord using the Allen's drop model. The incline plane and Tarlov techniques were used to assess clinical neurological function.

RESULTS

MEPs in the normal rats were elicited by applying transcortical suprathreshold stimulation consisting of 3-4 early negative peaks (N1, N2, N3 and N4) followed by several late waves. The N1 and N2 peaks were largest in the anterior and ventrolateral funiculus, respectively, which was indicative of extrapyramidal pathways. The 100 gcf impact injuries and the cord transection abolished the MEP distal to the lesion, whereas the 35 gcf injuries resulted in a latency shift and amplitude decrement of the MEP peaks. Eighteen of the 20 rats with 70 gcf-injuries showed clinical paraplegia. Among them, 7 rats had neurophysiological evidence of residual conduction pathways through the lesioned cord segment, such as the presence of N1 and N2 peaks in the scMEPs or exMEPs. After 4-aminopyridine (4-AP) administrations (1 mg/kg), the amplitude of the spared exMEP increased significantly and spread more widely.

CONCLUSIONS

MEPs evoked by transcortical stimulation travel mostly in the extrapyramidal tract. MEP monitoring could provide an excellent method of detecting the functional integrity of the motor tracts after SCI, and could even detect spared motor fibers after discomplete SCI. Furthermore, the use of 4-AP or other K+ channel blocking agents may be a potential treatment for patients with chronic moderate to severe SCI.

P2X purinoceptor-mediated excitation of trigeminal lingual nerve terminals in an in vitro intra-arterially perfused rat tongue preparation

A novel in vitro intra-arterially perfused adult rat tongue-nerve preparation was used to explore the possible actions of P2X purinoceptor agonists (ATP and alpha,beta-methylene ATP (alpha, beta-meATP)) on sensory nerve terminals innervating the rat tongue. We made whole-nerve recordings of the trigeminal branch of the lingual nerve (LN), which conducts general sensory information (pain, temperature, touch, etc.), and the chorda tympani (CT), which conducts taste information. Changes in LN and CT activity following intra-arterial application of P2X agonists were compared. In seven preparations, bolus close-arterial injection of ATP (30-3000 microM, 0.1 ml) or alpha,beta-meATP (10-300 microM, 0.1 ml) induced a rapid (< 1 s after injection), dose-related increase in LN activity that decayed within a few seconds. The minimal concentration of ATP (100 microM) required to elicit a response was about 10-fold higher than that of alpha,beta-meATP (10 microM). Bolus injection of ATP or alpha,beta-meATP induced a moderate decrease in firing frequency in three of seven CT preparations. LN responses to P2X agonists showed signs of rapid desensitisation with the peak frequency of discharge being smaller when the agonists were applied at short intervals. Suramin (200 microM) or PPADS (200 microM) applied by intra-arterial perfusion each antagonised the rapid increase in LN activity following application of alpha,beta-meATP (100 microM). Capsaicin (10 microM, 0.1 ml, n = 5 preparations) was injected intra-arterially to desensitise nociceptive fibres. This was found to block (n = 2) or greatly reduce (n = 3) the excitatory effects of alpha,beta-meATP (100 microM, 0.1 ml) on LN activity, implying that only capsaicin-sensitive nociceptive fibres in LN were responsive to P2X agonists. In contrast to the consistent excitatory responses in LN activity following fast application of P2X agonists as bolus, a variable and moderate change in discharge rate of LN and no change in CT activity (n = 5) was observed after applying ATP (100-300 microM, n = 21) or alpha,beta-meATP (100-300 microM, n = 14) by intra-arterial perfusion. The variable responses in LN activity to slow perfusion in contrast to close-arterial bolus injection are consistent with activation of the rapidly desensitising P2X3 receptors. In summary, ATP and alpha,beta-meATP preferentially activate general sensory afferent fibres (LN) but not taste fibres (CT). We suggest that the increase in whole-nerve activity of LN following application of P2X agonists represents activation of nociceptive fibres which possess P2X3 receptors. Our data indicate that ATP and P2X3 receptors may play a role in nociception, rather than taste sensation in the tongue.

Recruitment of the retinoblastoma protein to c-Jun enhances transcription activity mediated through the AP-1 binding site

The retinoblastoma susceptibility gene product (RB) is a transcriptional modulator. One of the targets for this modulator effect is the AP-1 binding site within the c-jun and collagenase promoters. The physical interactions between RB and c-Jun were demonstrated by co-immunoprecipitation of these two proteins using anti-c-Jun or anti-RB antisera, glutathione S-transferase affinity matrix binding assays in vitro, and electrophoretic mobility shift assays. The C-terminal site of the leucine zipper of c-Jun mediated the interaction with RB. Although the B-pocket domain of RB alone bound to c-Jun, a second c-Jun binding site in the RB was also suggested. Mammalian two-hybrid-based assay provided corroborative evidence that transactivation of gene expression by RB required the C-terminal region of c-Jun. We conclude that RB enhances transcription activity mediated through the AP-1 binding site. Adenovirus E1A or human papillomavirus E7 inhibits RB-mediated transcription activity. These data reveal that the interactions between these two distinct classes of oncoproteins RB and c-Jun may be involved in controlling cell growth and differentiation mediated by transcriptional regulation.

Rapid effects of corticosterone on cardiovascular neurons in the rostral ventrolateral medulla of rats

The present study has explored possible fast actions of corticosteroid hormones on activity of cardiovascular neurons of the rostral ventrolateral medulla. Experiments were conducted in 60 urethane-anesthetized, artificially ventilated adult rats. Extracellular recordings of unitary firings were made from the RVLM with multi- or single-barreled microelectrodes. Barosensitive cardiovascular neurons were identified through activation of the baroreceptor reflex by electrical stimulation of the aortic nerve and by intravenous injection of phenylephrine. In 52 barosensitive cardiovascular neurons, iontophoretically applied corticosterone sulfate increased the ongoing activity of 30 (57.7%) neurons, the other 22 (42.3%) neurons being unaffected. In 16 bulbospinal pre-sympathetic neurons, iontophorized corticosterone increased the firing rate of 12 neurons. Intravenously applied corticosterone (0.2 mg) increased the firing rates of 5 out of 12 bulbospinal pre-sympathetic neurons. The average baseline activity of cardiovascular neurons sensitive to corticosterone was found to be significantly less than that of the cardiovascular neurons insensitive to corticosterone. In 64 non-cardiovascular neurons, the firing rate of 13 (20.3%) neurons increased, 23 (36.0%) decreased and 28 (43.7%) remained unchanged following local application of corticosterone. The changes in firing rates of RVLM neurons following application of corticosterone occurred rapidly and were dependent on the doses of the agent. RU-38486 was able to reduce or block the rapid effects of corticosterone on cardiovascular and non-cardiovascular neurons. The results demonstrated that corticosterone may fast, non-genomically, modulate the activity of central regulators of the cardiovascular system and suggested that fast non-genomic actions of corticosteroid hormones may be an important mechanism in the integration of the autonomic nervous and the cardiovascular systems during some conditions such as stress.

Evidence that NMDA receptors mediate the responses of putative RVLM presympathetic neurons to vagal afferent stimulation in rats

Experiments were performed in 25 urethane-anaesthetized male Sprague-Dawley rats. Forty-six RVLM neurons were identified as putative presympathetic neurons according to their arterial baroreceptor reflex related properties, i.e. they were inhibited by stimulation of the aortic nerve; silenced by elevation of blood pressure and had a cardiac cycle related rhythm of spontaneous discharge. Responses of these neurons to tripled square wave stimulation of vagal afferents was tested by means of peristimulus time histograms. In addition to a long-lasting inhibition (I2), some neurons had one (P0) or two excitatory peaks (P1 and P2), and there was a short-lasting inhibition (I1) between P1 and P2. After microinjection of CPP (0.1 microl, 50 mM) into the NTS, the inhibitory responses were blocked, but the excitatory peaks were not affected; in the CVLM, CPP microinjection of the same dose had a similar effect on the responses elicited by vagal afferent stimulation in 15 of the 24 neurons tested. No detectable effects were observed in 9 neurons. However, intravenously administered ketamine attenuated or abolished these responses, either inhibitory or excitatory, in a dose dependent way. These results suggest: (1) an NMDA mechanism is involved in both the inhibitory and the excitatory responses. For the inhibitory responses, the involvement is both in the NTS and in the CVLM; for the excitatory responses, it is probably in the RVLM. (2) There may be a direct excitatory amino acid (EAA) pathway from the NTS to the RVLM.

Functional significance of the 10 Hz rhythmic discharges in sympathetic nerves

1. By measuring renal vascular conductance in anaesthetized and immobilized rabbits, the functional significance of the 10 Hz rhythmic discharges in the sympathetic nerves was assessed by electrical stimulation of the renal nerve. This stimulation mimicked the intermittently occurring 10 Hz rhythmic discharges. 2. Comparison of high-frequency (10-20 Hz) intermittent electrical stimulation with continuous low-frequency (5 Hz) stimulation showed that the intermittent high-frequency stimulation evoked faster (smaller time constant) and larger responses of the renal vascular conductance if the total number of stimulus pulses was the same. 3. Therefore, the intermittently occurring 10 Hz rhythmic discharges in the sympathetic nerve produces faster and larger effects on peripheral organs than effects produced by continuous discharges if the number of spikes is equal.

[Antagonistic effect of calcitonin gene related peptide on arrhythmia in rats]

Premature ventricular contraction (PVC), ventricular tachycardia (VT) and ventricular fibrillation (VF) were developed by endothelin-1 (ET-1) injected into the coronary ostia at the dose of 900 pmol/kg in anesthetized rats. No arrhythmia was elicited but blood pressure fell temporarily by calcitonin gene related peptide (CGRP), the injection into the coronary ostia. After pretreatment with CGRP incidence and severity of arrhythmia decreased at the same ET-1 dose. Arrhythmia score in CGRP 1200 pmol/kg + ET-1 group was lower than that in ET-1 group (P < 0.01). The results revealed that antiarrhythmic effect of CGRP may be partially brought about by its antagonistic effect against ET-1 induced arrhythmia.

Properties of presympathetic neurones in the rostral ventrolateral medulla in the rat: an intracellular study "in vivo'

1. Intracellular recordings were made in pentobarbitone-anaesthetized rats from sixty-eight neurones located in the rostral ventrolateral medulla (RVLM), which responded with inhibition (latency, 33.6 +/- 9.3 ms) after stimulation of the aortic depressor nerve with short bursts of pulses. This inhibition was due to chloride- and voltage-dependent IPSPs. 2. Seventeen neurones could be excited antidromically after stimulation in the T2 spinal segment (conduction velocity 1.9-8.5 m.s-1) and were classified as RVLM presympathetic vasomotor neurones. 3. "Spontaneously' active neurones (n = 29) displayed a largely irregular pattern of firing, with no clear relationship between the level of the membrane potential and cycles of phrenic nerve activity at end-tidal CO2 < 5.0%. Cardiac cycle-related shifts of the membrane potential were not considered indicative of baroreceptor input as they could be due to movement artifacts. 4. All neurones displayed large synaptic activity (EPSPs and IPSPs, peak-to-peak amplitude > 5.0 mV). The depolarizing IPSPs observed during injection of chloride and/or negative current consisted of a phasic and a tonic component. 5. The on-going activity of these neurones resulted from synaptic inputs, with individual action potentials usually preceded by identifiable fast EPSPs. 6. No evidence was found for the presence of gradual depolarizations (autodepolarizations) between individual action potentials, and therefore under these experimental conditions the activity of RVLM presympathetic neurones did not depend on intrinsic pacemaker properties. 7. These results are consistent with the "network' hypothesis for the generation of sympathetic vasomotor tone.

A comparative study of pre-sympathetic and Bötzinger neurons in the rostral ventrolateral medulla (RVLM) of the rat

The aim of this study was to investigate the degree of functional and anatomical overlap between two major neuronal subpopulations in the rostral ventrolateral medulla: pre-sympathetic (sympathoexcitatory) neurons, and expiratory neurons of the Bötzinger complex. Extracellular recordings were made with dye-filled microelectrodes in pentobarbital anesthetized, paralyzed and artificially ventilated adult Wistar rats. Tests applied included stimulation of baroreceptor afferents, activation of peripheral chemoreceptors and lung stretch receptors, changes in central respiratory drive with hyper- or hypoventilation, nociceptive stimulation, and antidromic stimulation from the T2 segment of the spinal cord or medulla oblongata at obex level. The two groups of neurons showed different patterns of spontaneous activity and generally different responses to these stimuli. The recording positions showed some overlap, but the majority of Bötzinger neurons were dorsolateral to pre-sympathetic neurons. There was a large overlap between the location of pre-sympathetic neurons and the lateral part of the C1 adrenergic group, but only a small overlap between these adrenergic neurons and Bötzinger neurons. These results indicate that the anatomically adjacent pre-sympathetic and Bötzinger expiratory neurons form two functionally distinct neuronal subpopulations.