Novelty and Familiarity Activations in PET Studies of Memory Encoding and Retrieval

Nine young right-handed men viewed colored pictures of people,scenes, and landscapes. Then, 24 hr later while undergoing PETscanning, they viewed previously studied (OLD) pictures in onetype of scan, and previously not seen (NEW) pictures in another.The OLD-NEW subtraction of PET images indicates familiarity,and the NEW-OLD indicates novelty. Familiarity activations,signalling aspects of retrieval, were observed in the left andright frontal areas, and posterior regions bilaterally. Noveltyactivations were in the right limbic regions, and bilaterallyin temporal and parietal regions, including area 37. These latteractivations were located similarly to novelty activations inprevious PET studies using visual words and auditory sentences,suggesting the existence of brain regions specializing in transmodalnovelty assessment The effects of novelty are seen both be haviorallyand in replicable patterns of cortical and subcortical activation.We propose a "novelty/encoding hypothesis": (1) novelty assessmentrepresents an early stage of long-term memory encoding; (2)elaborate, meaning-based encoding processes operate on the incoming information to the extent of its novelty, and therefore(3) the probability of long-term storage of information vanesdirectly with the novelty of the information.     

Upper parietal pleurectomy with resection of bullae by thoracoscopy in spontaneous pneumothorax. New perspectives from preliminary results in 20 cases]

In view of the increasing development of laparoscopic surgery and hoping to minimize thoracotomy's risks, we had the idea to perform pleurectomy as a treatment of Spontaneous Pneumothorax (S.P.) through video thoracoscopy. The operation was performed under general endobronchial anesthesia, the patient placed in the posterolateral thoracotomy position. Three trocars inserted through the 5th, 7th and 9th intercostal space, allowed the introduction of non specific thoracoscopic instruments similar to those used in laparoscopic surgery. The apical pleurectomy was delimited by the 6th rib, the internal thoracic vessels, the costovertebral sulcus and the first rib. Blebs and small bullae are now transected with application of the "EndoGIA 30". Pleural cavity was drained by F28 ans F32 tubes through the lower orifices. This procedure was performed in 18 patients presenting 20.S.P.. Operative indications were: persistent air link (7 cases), recurrence (9 cases), bullae with bridle and or anterior thoracotomy for S.P. (4 cases). One bleeding of 200 ml from a wounded intercostal vessel ligated with a clip was the sole operative hitch. Operative duration decreased from two to one hour. Average drainage duration was 3.5 dys and hospital stay 4.5 days. There was no death nor immediate complications. Post-operative pain was judged in all cases less intensive than that experienced after pleurectomy with thoracotomy. This original procedure is the first described as entirely performed through thoracoscopy with non specific instruments and hence economic impact.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hepatolithiasis associated with anomalous biliary anatomy and a vascular compression. Hepatolithiasis and anomalous anatomy

Biliary tract abnormalities occur in about one of every three people, usually being minor and of no clinical significance. Major abnormalities, however, may present in an unusual manner and provide a major hazard to the unsuspecting surgeon. A patient presenting with cholangitis without jaundice or abnormal liver function tests is reported. Endoscopic retrograde cholangiography failed to demonstrate any bile ducts in the right postero-lateral segments of the liver, the "naked segment sign". A percutaneous transhepatic cholangiogram demonstrated a stricture obstructing the right posterior segmental hepatic duct with hepatolithiasis above the stricture. At operation an anomalous vessel was found at the site of the stricture. This case highlights the unusual way in which biliary tract anomalies may present and the importance of adequate pre-operative investigation.     

Rectal cancer in the Kingdom of Saudi Arabia: the King Faisal Specialist Hospital experience

BACKGROUND: No survival data have yet been published from the Kingdom of Saudi Arabia for patients with rectal cancer. The present paper reports experience with these patients over an 8-year period. METHODS: All patients referred to the King Faisal Specialist Hospital (KFSH) between March 1990 and February 1998 for the primary management of rectal cancer were entered into a computerized database. Prior to 1993 patients did not receive adjuvant therapy. Kaplan-Meier survival curves and the log-rank test were used to compare outcome data. RESULTS: There were 70 men (average age: 55.6 years) and 75 women (average age: 52.8 years). Twelve per cent of patients admitted a family history of colorectal carcinoma (CRC). Twenty-seven per cent of tumours were circumferential. Most tumours were larger than 4 cm and the lowest edge of the majority of tumours was less than 6 cm from the anal verge. Fifty-four per cent of tumours were fixed; 69% of patients received either pre-operative or postoperative radiotherapy. A total of 106 patients underwent 'curative' surgery. Equal numbers of patients had abdomino-perineal resection (APR) and anterior resection (AR) of the rectum. Thirty-five patients received blood peri-operatively (APR, 34%; AR, 12%). Major anastomotic leakage following AR occurred in two patients. Two patients died within 30 days of surgery. Ten patients were lost to follow-up. Following curative AR, eight patients had a distal resection margin of < 2 cm and two patients (Dukes' C) developed local recurrence (25%); 37 patients had a margin > 2 cm and seven developed local recurrence (18.9%). A total of 48 patients underwent curative APR, and four patients developed local recurrence (8.3%). Overall local recurrence was tumour stage-dependent (Dukes' B, 8.8%; Dukes' C, 29.3%). Recurrence was local in 13 patients. Pre-operative radiotherapy seemed to reduce average tumour size (3.6 vs 4.3 cm). The crude overall 5-year survival rate was 39%. The 5-year survival rate for patients with Dukes' stage C cancers following 'curative' surgery was 25%. CONCLUSION: Curative surgery can be performed with a relatively low requirement for blood transfusion, a low mortality and morbidity, and comparable outcomes to Western studies in spite of the large, low and often advanced stage of the tumours managed. Local recurrence rates following curative resection and re-anastomosis for low rectal cancers may be reduced by resisting patient pressure to avoid stomata.     

Robust-Deep: A Method for Increasing Brain Imaging Datasets to Improve Deep Learning Models’ Performance and Robustness

A small dataset commonly affects generalization, robustness, and overall performance of deep neural networks (DNNs) in medical imaging research. Since gathering large clinical databases is always difficult, we proposed an analytical method for producing a large realistic/diverse dataset. Clinical brain PET/CT/MR images including full-dose (FD), low-dose (LD) corresponding to only 5 % of events acquired in the FD scan, non-attenuated correction (NAC) and CT-based measured attenuation correction (MAC) PET images, CT images and T1 and T2 MR sequences of 35 patients were included. All images were registered to the Montreal Neurological Institute (MNI) template. Laplacian blending was used to make a natural presentation using information in the frequency domain of images from two separate patients, as well as the blending mask. This classical technique from the computer vision and image processing communities is still widely used and unlike modern DNNs, does not require the availability of training data. A modified ResNet DNN was implemented to evaluate four image-to-image translation tasks, including LD to FD, LD+MR to FD, NAC to MAC, and MRI to CT, with and without using the synthesized images. Quantitative analysis using established metrics, including the peak signal-to-noise ratio (PSNR), structural similarity index metric (SSIM), and joint histogram analysis was performed for quantitative evaluation. The quantitative comparison between the registered small dataset containing 35 patients and the large dataset containing 350 synthesized plus 35 real dataset demonstrated improvement of the RMSE and SSIM by 29% and 8% for LD to FD, 40% and 7% for LD+MRI to FD, 16% and 8% for NAC to MAC, and 24% and 11% for MRI to CT mapping task, respectively. The qualitative/quantitative analysis demonstrated that the proposed model improved the performance of all four DNN models through producing images of higher quality and lower quantitative bias and variance compared to reference images.     

Inverse agonist activity of sarpogrelate, a selective 5-HT2A-receptor antagonist, at the constitutively active human 5-HT2A receptor

Mutations producing constitutively active G-protein coupled receptors have been found in the pathophysiology of several diseases, implying that inverse agonists at the constitutively active receptors may have preferred therapeutic applications. Because of the involvement of 5-HT(2A) receptors in mediating many cardiovascular diseases, constitutively active mutants of the 5-HT(2A) receptor may be responsible for the disease states. Thus, the purpose of the present study was to investigate the inverse agonist activity of sarpogrelate, a selective 5-HT(2A)-receptor antagonist, and its active metabolite, M-1; and we compared their activities with those of other 5-HT(2A)-receptor antagonists such as ritanserin, ketanserin, and cyproheptadine. Using a constitutively active mutant (C322K) of the human 5-HT(2A) receptor, we demonstrated that like other 5-HT(2A)-receptor antagonists, sarpogrelate acts as a potent inverse agonist by significantly reducing basal inositol phosphate levels. However, there were no significant differences between sarpogrelate and other 5-HT(2A)-receptor antagonists for their inverse agonist activity. Compared with the wild type receptor, mutant receptor displayed significantly higher affinity for 5-HT and lower affinity for sarpogrelate. These results indicate that stabilization of the inactive conformation of the 5-HT(2A) receptor may be a key component of the mechanism of action of sarpogrelate.     

First imaging results of an intraindividual comparison of 11C-acetate and 18F-fluorocholine PET/CT in patients with prostate cancer at early biochemical first or second relapse after prostatectomy or radiotherapy

Purpose

¹⁸F-Fluorocholine (FCH) and ¹¹C-acetate (ACE) PET are widely used for detection of recurrent prostate cancer (PC). We present the first results of a comparative, prospective PET/CT study of both tracers evaluated in the same patients presenting with recurrence and low PSA to compare the diagnostic information provided by the two tracers.

Methods

The study group comprised 23 patients studied for a rising PSA level after radical prostatectomy (RP, 7 patients, PSA ≤3 ng/ml), curative radiotherapy (RT, 7 patients, PSA ≤5 ng/ml) or RP and salvage RT (9 patients, PSA ≤5 ng/ml). Both FCH and ACE PET/CT scans were performed in a random sequence a median of 4 days (range 0 to 11 days) apart. FCH PET/CT was started at injection (307?±?16 MBq) with a 10-min dynamic acquisition of the prostate bed, followed by a whole-body PET scan and late (45 min) imaging of the pelvis. ACE PET/CT was performed as a double whole-body PET scan starting 5 and 22 min after injection (994?±?72 MBq), and a late view (45 min) of the prostate bed. PET/CT scans were blindly reviewed by two independent pairs of two experienced nuclear medicine physicians, discordant subgroup results being discussed to reach a consensus for positive, negative end equivocal results.

Results

PET results were concordant in 88 out of 92 local, regional and distant findings (Cohen’s kappa 0.929). In particular, results were concordant in all patients concerning local status, bone metastases and distant findings. Lymph-node results were concordant in 19 patients and different in 4 patients. On a per-patient basis results were concordant in 22 of 23 patients (14 positive, 5 negative and 3 equivocal). In only one patient was ACE PET/CT positive for nodal metastases while FCH PET/CT was overall negative; interestingly, the ACE-positive and FCH-negative lymph nodes became positive in a second FCH PET/CT scan performed a few months later.

Conclusion

Overall, ACE and FCH PET/CT showed excellent concordance, on both a per-lesion and a per-patient basis, suggesting that both tracers perform equally for recurrent prostate cancer staging.     

Spectrum of Skin Lesions of Post-Kala-Azar Dermal Leishmaniasis in Kala-azar Endemic Areas of Bangladesh

Post-kala-azar dermal leishmaniasis (PKDL) is a complication of visceral leishmaniasis (VL) and serves as a potential reservoir for Leishmania parasite. The study was aimed to evaluate the spectrum of skin lesions of PKDL in kala-azar endemic areas in Bangladesh. This cross sectional study was carried out to observe the characteristics of skin lesions among 250 PKDL cases. The suspected PKDL patients in highly endemic villages of Fulbaria Upazilla of Mymensingh district.were subjected to a dipstick test (rK39) for kala azar. The median time interval between diagnosing kala-azar and PKDL was 23 month (m-21, r- 0-60 months). The most common skin lesions were multiple symmetrical hypopigmented macules with irregular margins in 179(71.6%) cases followed by erythematous facial induration in 74(29.6%), papular in 33(13.2%), nodular in 28(11.2%) cases, combination of macules, papules, nodules and plaques in 88(35.2%) cases, annular in 7(2.8%) cases and Papillomatous mucosal growth in 2(0.8%) cases. Sites of involvement were mostly in face (92.4%), Trunk (84.8%), extremities (33.2%), oral mucosa and tongue (0.8%) and Genitalia (1.2%). Suspicion of PKDL on the basis of skin lesions will lead to early diagnosis and prompt treatment will impart an important role in prevention and eradication of Leishmaniasis in Bangladesh.