Fear conditioning is associated with synaptogenesis in the lateral amygdala

Fear conditioning in the rat typically involves pairing a conditioned stimulus (tone) with an aversive unconditioned stimulus (foot shock) which elicits a freeze response. Although the circuitry that underlies this form of learning is well defined, potential synaptic changes associated with this form of learning have not been fully investigated. This experiment examined synaptic structural plasticity in the lateral amygdala which is critical for the acquisition of the conditioned fear response. Adult male rats were randomly allocated to either a paired, unpaired or tone only condition. One day after the initial fear conditioning session and 1 h after a probe trial confirmation of a conditioned fear response, the rats were perfused and the relevant tissue was embedded for electron microscopic analysis. Synaptic changes were quantified in the lateral amygdala using a stereological approach. The results showed a significant increase in the number of synapses in the conditioned animals compared to controls. This finding suggests that an increase in synaptic compliment in the amygdala may underlie the acquisition of the conditioned fear response.

Electric acoustic stimulation of the auditory system: experience and results of ten patients using MED-EL's M and FlexEAS electrodes

OBJECTIVE

To evaluate the hearing preservation rate and speech perception scores in patients with profound high frequency hearing loss and acoustically aidable low frequency hearing, managed with the MED-EL electric acoustic stimulation system referenced to the insertion depth of the electrode array.

STUDY DESIGN

Retrospective data analysis.

PARTICIPANTS AND SETTING

Ten patients implanted at the Auditory Implant Centre, Guy's and St Thomas's Hospital, London, UK.

MAIN OUTCOME MEASURES

Pure tone audiometry, speech perception tests and electrode insertion depth angle.

RESULTS

Postoperatively, functional hearing preservation allowing electric acoustic stimulation was achieved in eight patients and total preservation of residual hearing in five patients with follow-up periods of more than 12 months. Three of four (75%) patients with an insertion depth of >360 degrees had a threshold shift of >25 dB, and all four patients had a threshold shift of >10 dB. All patients with total hearing preservation had the electrode inserted up to 360 degrees at maximum. Overall, speech perception outcomes increased significantly and hearing impairment was significantly reduced after electric acoustic stimulation or electric stimulation alone as compared with the preoperative scores.

CONCLUSION

Electric acoustic stimulation provides significant benefit to individuals with profound high frequency hearing loss. Studies with larger number of patients are needed to establish the optimal electrode insertion angle as well as to further analyse the benefit of electric acoustic stimulation.

Uncommon presentation of nasopharyngeal extramedullary plasmacytoma: a case report and literature review

OBJECTIVE

We report an exceptional presentation of extramedullary plasmacytoma of the nasopharynx without bone marrow involvement or other characteristics of multiple myeloma.

METHOD

Case report and a review of the world literature concerning the clinical presentation, histopathological features, optimal treatment and prognosis of nasopharyngeal extramedullary plasmacytoma.

RESULTS

Reports of patients with symptomatic extramedullary plasmacytomas of the nasopharynx eventually being documented with histopathological evidence are not uncommon; however, the converse appears to be an extremely rare event. The patient was completely asymptomatic and following a paroxysm of coughing, expectorated a polypoidal nodule, which on histopathological investigation had features suggestive of extramedullary plasmacytoma.

CONCLUSION

Although these tumours commonly present with significant nasal symptoms, this exceptional presentation in an asymptomatic patient has never been previously reported. Unusual presentations of rare tumours can pose considerable diagnostic dilemmas to both the surgeon and histopathologist. Awareness of these rarities is important to ensure the best patient care.

Eyeblink conditioning leads to fewer synapses in the rabbit cerebellar cortex

Eyeblink conditioning involves the pairing of a conditioned stimulus (tone) to an aversive unconditioned stimulus (air puff). Although the circuitry that underlies this form of learning is well defined, synaptic changes in these structures have not been fully investigated. This experiment examined synaptic structural plasticity in the cerebellar cortex, a structure that has been found to modulate the acquisition and timing of the conditioned response. Long-term depression of Purkinje cells (PCs) in the cerebellar cortex has been proposed as a mechanism for releasing inhibition of the interpositus nuclei, a structure critical for the formation of the CR. Adult albino rabbits were randomly allocated to either a paired, unpaired, or exposure-only condition. The results showed a significant decrease in the number of excitatory synapses in the outer layer of the cerebellar cortex in the conditioned rabbits compared with controls. This finding suggests that a reduction in the number of excitatory synapses may contribute to the lasting depression of PC activity that is associated with eyeblink conditioning.

Do you smell what I smell? Olfactory impairment in wild yellow perch from metal-contaminated waters

In this study, we sampled yellow perch from three lakes along a metal-contamination gradient and examined their olfactory ability in response to conspecific chemical alarm cues and metal-binding characteristics of their olfactory epithelium (OE). We measured the electrophysiological response at the OE, tested their antipredator behaviour and measured neuronal density at the olfactory rosette and bulb. Yellow perch from contaminated lakes exhibited significantly larger electrophysiological responses to alarm cues than clean lake fish, but showed no antipredator behaviour contrary to clean lake fish. Neuron density did not differ at either the olfactory rosette or bulb between clean and contaminated fish. Unlike fishes raised under laboratory or aquaculture settings, fish from contaminated lakes possessed a functional OE after metal exposure, but similar to laboratory/aquaculture fishes, yellow perch did not exhibit olfactory-mediated behaviours. Thus, wild fish from contaminated lakes can detect chemical stimuli but olfactory signal processing is disrupted which could alter ecological functioning.

Validation of a prognostic nomogram in patients undergoing resection for pancreatic ductal adenocarcinoma in a UK tertiary referral centre

INTRODUCTION

Survival following resection for pancreatic ductal adenocarcinoma (PDAC) remains poor. The aim of this study was to validate a survival nomogram designed at the Memorial Sloan-Kettering Cancer Centre (MSKCC) in a UK tertiary referral centre.

METHODS

Patients who underwent resection for PDAC between 1995 and 2005 were analysed retrospectively. Standard prognostic factors and nomogram-specific data were collected. Continuous data are presented as median (inter-quartile range).

RESULTS

Sixty-three patients were analysed. The median survival was 326 (209-680) days. On univariate analysis lymph node status (node +ve 297 (194-471) days versus node -ve 367 (308-1060) days, p=0.005) and posterior margin involvement (margin +ve 210 (146-443) days versus margin -ve 355 (265-835) days, p=0.024) were predictors of a poor survival. Only lymph node positivity was significant on multivariate analysis (p=0.006). The median nomogram score was 217 (198-236). A nomogram score of 113-217 predicted a median survival of 367 (295-847) days compared to 265 (157-443) days for a score of 218-269, p=0.012.

CONCLUSION

Increasing nomogram score was associated with poorer survival. However the accuracy demonstrated by MSKCC could not be replicated in the current cohort of patients and may reflect differences in patient demographics, accuracy of pathological staging and differences in treatment regimens between the two centres.

Carbohydrate antigen 19.9 accurately selects patients for laparoscopic assessment to determine resectability of pancreatic malignancy

BACKGROUND

Laparoscopy with laparoscopic ultrasonography (L-LUS) may be useful in the selection of patients for surgery to resect peripancreatic malignancy in addition to contrast-enhanced computed tomography (CE-CT). The present prospective study assessed the strategy of using carbohydrate antigen 19.9 (CA19.9) levels to select patients for L-LUS.

METHODS

Patients with suspected peripancreatic malignancy that appeared resectable on CE-CT were selected for immediate surgery if CA19.9 was low (up to 150 kU/l, or up to 300 kU/l if serum bilirubin was above 35 micromol/l), or to L-LUS if CA19.9 was high (over 150 kU/l, or over 300 kU/l if serum bilirubin was above 35 micromol/l). Data were assessed to determine the clinical utility of this strategy.

RESULTS

A total of 94 patients went straight to surgery, of whom 65 proved resectable: 63 of 80 with a low CA19.9 level but only two of 14 with a high CA19.9 level and gastric outlet obstruction. From 55 patients with high CA19.9 levels, L-LUS correctly identified 26 of 31 resectable tumours and eight of 24 unresectable tumours.

CONCLUSION

Using CA19.9 levels to help select patients with pancreatic malignancy for immediate surgery or L-LUS for further assessment of resectability effectively increased resection rates and reduced unnecessary laparotomies.

Staging laparoscopy for cholangiocarcinoma

The precise role of laparoscopic assessment of biliary tract malignancy is yet to be defined. The evidence for its use has been reviewed to establish the role of laparoscopy for preoperative staging of cholangiocarcinoma. Published papers were reviewed for the evidence relevant to intrahepatic, proximal intrahepatic and distal biliary carcinoma. There is no randomized trial evaluating staging laparoscopy or laparoscopic ultrasound in the assessment of cholangiocarcinoma and the quality of the available data is extremely variable. There is a need for further studies to determine the specific role of laparoscopic staging of cholangiocarcinoma. The current standard of management should be to perform laparoscopic staging prior to proceeding to resection for patients with cholangiocarcinoma as it may prevent unnecessary laparotomy in up to 30% of patients. However, a selective approach identifying high-risk patients who will not benefit from surgical palliation may be more cost effective and future studies should be performed to identify such patients.

Jugular foramen meningocoele in a patient with neurofibromatosis type 1

Objective:

We present a rare case of a jugular foramen meningocoele in a 48-year-old female, with neurofibromatosis type 1, presenting with positional vertigo. We also postulate possible underlying pathophysiological mechanisms.

Method:

We describe the imaging findings of this rare entity and review the literature on skull base meningocoeles, particularly in the context of neurofibromatosis type 1.

Results:

A computed tomography scan revealed smooth expansion of the jugular foramen. Magnetic resonance imaging showed a fluid filled lesion expanding the jugular foramen and communicating with cerebrospinal fluid of the cerebellomedullary cistern superiorly.

Conclusion:

Skull base meningocoeles are a rare entity and we believe that this is the first reported case of a meningocoele causing enlargement of the jugular foramen in a patient with neurofibromatosis type 1. The meningocoele may have resulted from a severe form of dural ectasia or from dysplastic, weakened bone at the skull base.

Palliation for suspected unresectable hilar cholangiocarcinoma

AIM

The aim of this study was to evaluate the outcome of different techniques of palliation for patients with hilar cholangiocarcinoma.

METHOD

All patients treated with palliative intent between 1988 and 2004 at the Royal Infirmary of Edinburgh were reviewed. Patients were analysed on an intention to treat basis. Demographics, procedure and outcome (including re-admissions) were recorded.

RESULTS

Two hundred and thirty-three patients underwent palliative treatment for suspected hilar cholangiocarcinoma. The diagnosis was confirmed histologically in 109 patients. The procedure related morbidity and mortality was 54/225 and 18/207 respectively. Seventy-one patients required re-admission. Twenty patients underwent surgical biliary bypass for jaundice. Those undergoing surgical palliation had a longer median (95% CI) time to re-admission (16 (0-36) vs.7 (2-12) weeks, p=0.001). Endoscopic retrograde cholangio-pancreatography (ERCP) and stenting was only successful in 28 patients and was associated with a significantly higher re-admission rate compared to patients in whom ERCP was not performed (60/179 vs. 4/27, p=0.050). The overall median (95% CI) survival was 145 (124-185) days.

CONCLUSION

Current options for palliation of hilar cholangiocarcinoma provide good short term success but are all associated with significant early and late morbidity. Due to its low success and association with an increased re-admission rate, ERCP for definitive palliation should not be used in the first line staging and management of these patients.

Follow-up and outcomes for resection of colorectal liver metastases in Edinburgh

AIM

The aim of this study was to assess the value of a defined follow-up protocol for patients undergoing potentially curative hepatic resection for colorectal hepatic metastases.

METHODS

A standard protocol for the duration of the study consisted of clinical assessment, serum carcinoembryonic antigen (CEA) and computed tomography. Patterns of recurrence, method and timing of diagnosis and outcome were recorded.

RESULTS

One hundred and ninety-one patients underwent potentially curative resection from 1989 to 2004 of whom 103 developed recurrence. The median (inter-quartile range) follow-up was 24.4 (6.5-42.3) months. The median (IQR) time to recurrence and overall survival was 25.0 (10 -not yet reached) and 45.2 (21-123) months, respectively. Seventeen patients (8.9%) underwent further surgery with curative intent. Fifty-five patients (57.9%) had recurrence diagnosed at routine follow-up with 71% (44/62) being diagnosed by CEA and CT. The CEA was elevated in 85.7% (72/84 patients) at the time of diagnosis of recurrence.

CONCLUSION

Although the detection of recurrent disease is common during follow-up after hepatic resection for colorectal metastases, few patients will be suitable for further intervention with curative intent. The exact nature of the follow-up protocol remains to be determined but if it is going to be performed it should be most intensive within the first 3 years.

Preoperative lymphocyte count as a prognostic factor in resected pancreatic ductal adenocarcinoma

BACKGROUND AND AIMS

Recognized prognostic factors for resected pancreatic ductal adenocarcinoma (PDAC) include tumour size, differentiation, resection margin involvement and lymph node metastases. A further prognostic factor of less certain significance is lymphocyte count. The aim of this study was to investigate whether preoperative lymphocyte count is a prognostic indicator in patients with PDAC.

MATERIAL AND METHODS

Patients who had undergone a potentially curative pancreaticoduodenectomy (PD) for PDAC between 1998 and 2005 were analysed. Standard prognostic factors, preoperative lymphocyte count, preoperative neutrophil count and survival data were collected.

RESULTS

Of the 44 patients studied, univariate analysis identified predictors of a poor survival as lymph node status (node positive (+ve) 10.3 [5.4-20.9] months versus node negative (-ve) 14.2 [10.9-31.4] months; p=0.038), posterior resection margin invasion (margin +ve 7.0 [5.1-15.0] months versus margin -ve 13.1 [10.0-28.3] months; p=0.025) and lymphocyte count below the reference range (<1.5 x 10(9)/litre 8.8 [7.0-13.1] months versus > or = 1.5 x 10(9)/litre 14.3 [7.0-28.3] months; p=0.029). Low preoperative lymphocyte count (p=0.027) and posterior margin invasion (p=0.023) retained significance on multivariate analysis. Preoperative neutrophil to lymphocyte ratio was not a significant prognostic factor.

CONCLUSION

Preoperative lymphocyte count is a significant prognostic factor in patients with PDAC.

Perioperative transfusion for pancreaticoduodenectomy and its impact on prognosis in resected pancreatic ductal adenocarcinoma

BACKGROUND AND AIMS

Pancreaticoduodenectomy (PD) is a major operative intervention performed most commonly for malignancy in the head of pancreas. The aim of this study was to evaluate the utilization of blood transfusion for PD and to determine whether this had prognostic significance in a subset of patients with pancreatic ductal adenocarcinoma (PDAC).

MATERIAL AND METHODS

Data on blood transfusion requirement were retrospectively collected for patients undergoing PD from 1998 to 2005. Standard prognostic factors and survival data were also collected in patients with PDAC.

RESULTS

One-hundred-and-seventy patients underwent PD. Seventy-six patients (45%) received transfusion. The median (interquartile range) number of units of red cell concentrate (RCC) transfused perioperatively (intraoperatively and within 24 h of surgery) was 1.5 (0.5-2.5). The median preoperative haemoglobin (Hb) was 126 g/dl. The median number of units of RCC transfused perioperatively in patients with Hb <126 g/dl was 2 (1-3); for those with Hb > or = 126 g/dl the median was 0 (0-1); p=0.003. Forty-nine patients who were resected for PDAC were subjected to survival analysis. Univariate and multivariate analyses showed that only posterior resection margin invasion was associated with an adverse outcome (margin positive 198 [143-470] days vs margin negative 398 [303-859] days; p=0.02). Perioperative RCC transfusion requirement was not a significant predictor of survival (transfusion 408 [214-769] days vs no transfusion 331 [217-391] days; p=0.18). Furthermore, RCC transfusion within 30 days of operation was not a significant predictor of poor survival (transfusion 331 [201-459] days vs no transfusion 317 [196-769] days; p=0.43).

CONCLUSIONS

PD can be performed with a moderately low requirement for RCC transfusion; however, low preoperative haemoglobin is a predictor for the requirement of RCC transfusion. Administration of RCC transfusion does not appear to be a significant adverse prognostic factor in patients with resected PDAC.

Meta-analysis of endoscopy and surgery versus surgery alone for common bile duct stones with the gallbladder in situ

BACKGROUND

There is no clear consensus on the better therapeutic approach (endoscopic versus surgical) to choledocholithiasis. This study is a meta-analysis of the available evidence.

METHODS

A search of the Medline and ISI databases identified 12 studies that met the inclusion criteria for data extraction. The analysis was performed using a random-effects model. The outcome was calculated as an odds ratio (OR) or relative risk (RR) with 95 per cent confidence intervals (c.i.).

RESULTS

Outcomes of 1357 patients were studied. There was no significant difference in successful duct clearance (OR 0.85 (95 per cent c.i. 0.64 to 1.12); P = 0.250), mortality (RR 1.79 (95 per cent c.i. 0.66 to 4.83); P = 0.250), total morbidity (RR 0.89 (95 per cent 0.71 c.i. to 1.13); P = 0.350), major morbidity (RR 1.34 (95 per cent c.i. 0.92 to 1.97); P = 0.130) or need for additional procedures (OR 1.37 (95 per cent c.i. 0.82 to 2.29); P = 0.230) between the endoscopic and surgical groups. There was also no significant difference between the endoscopic and laparoscopic surgery groups.

CONCLUSION

Both approaches have similar outcomes, and treatment should be determined by local resources and expertise.

Growing skull fracture in the absence of a dural tear

A case of growing skull fracture associated with unrecognized extradural haematoma is presented together with the relevant radiology. The pathophysiology of growing skull fracture is reviewed in light of this previously unreported case.

Bile duct injury in the era of laparoscopic cholecystectomy

BACKGROUND

Laparoscopic cholecystectomy is the standard of care for symptomatic cholelithiasis, but it is associated with a higher incidence of bile duct injury than the open approach.

METHODS

A review was performed of the English language literature on the management of bile duct injury listed on Medline databases.

RESULTS AND CONCLUSION

There is consensus that careful dissection and correct interpretation of the anatomy avoids the complication of bile duct injury during cholecystectomy. Routine intraoperative cholangiography is associated with a lower incidence and early recognition of bile duct injury. Early detection and repair is associated with an improved outcome, and the minimum standard of care after the recognition of a bile duct injury is immediate referral to a surgeon experienced in bile duct injury repair. Surgery provides the mainstay of treatment, with proximal hepaticojejunostomy Roux en Y being the operation of choice; a selective role for endoscopic or radiological treatment exists. The outcome after bile duct injury remains poor, especially in relation to the initial expectation of the cholecystectomy. Patients are often committed to a decade of follow-up.

Bile duct injury in the era of laparoscopic cholecystectomy

BACKGROUND

Laparoscopic cholecystectomy is the standard of care for symptomatic cholelithiasis, but it is associated with a higher incidence of bile duct injury than the open approach.

METHODS

A review was performed of the English language literature on the management of bile duct injury listed on Medline databases.

RESULTS AND CONCLUSION

There is consensus that careful dissection and correct interpretation of the anatomy avoids the complication of bile duct injury during cholecystectomy. Routine intraoperative cholangiography is associated with a lower incidence and early recognition of bile duct injury. Early detection and repair is associated with an improved outcome, and the minimum standard of care after the recognition of a bile duct injury is immediate referral to a surgeon experienced in bile duct injury repair. Surgery provides the mainstay of treatment, with proximal hepaticojejunostomy Roux en Y being the operation of choice; a selective role for endoscopic or radiological treatment exists. The outcome after bile duct injury remains poor, especially in relation to the initial expectation of the cholecystectomy. Patients are often committed to a decade of follow-up.

Long-term potentiation is associated with changes in synaptic ultrastructure in the rat neocortex

Long-term potentiation (LTP) in the sensorimotor cortex of freely moving rats has been associated with changes in dendritic morphology and dendritic spine density. The current research examined changes in synaptic number and ultrastructure associated with LTP in this cortical region. LTP was induced over a 1 h period and the animals were sacrificed 2 h after the initial stimulation of the LTP group. Synapses within the terminal area of the apical dendrites from layer III pyramidal neurons were quantified by determining the total number of synapses per neuron, the number of excitatory and inhibitory contacts, number of synapses with different curvature subtypes, number of perforated synapses, and synaptic length. Several changes in synaptic morphology of excitatory synapses were revealed but no overall increase in the number of synapses per neuron was evident. Specifically, the induction of LTP was associated with an increased number of excitatory perforated and concave shaped synapses. Increased numbers of perforated concave synapses were also found to be significantly correlated with the degree of potentiation in the LTP animals. These and previous results suggest similar synaptic changes in both the cortex and hippocampus during the early phases of LTP maintenance and distinct synaptic changes during later phases of LTP maintenance.