Detection and severity quantification of pulmonary embolism with 3D CT data using an automated deep learning-based artificial solution

PURPOSE

The purpose of this study was to propose a deep learning-based approach to detect pulmonary embolism and quantify its severity using the Qanadli score and the right-to-left ventricle diameter (RV/LV) ratio on three-dimensional (3D) computed tomography pulmonary angiography (CTPA) examinations with limited annotations.

MATERIALS AND METHODS

Using a database of 3D CTPA examinations of 1268 patients with image-level annotations, and two other public datasets of CTPA examinations from 91 (CAD-PE) and 35 (FUME-PE) patients with pixel-level annotations, a pipeline consisting of: (i), detecting blood clots; (ii), performing PE-positive versus negative classification; (iii), estimating the Qanadli score; and (iv), predicting RV/LV diameter ratio was followed. The method was evaluated on a test set including 378 patients. The performance of PE classification and severity quantification was quantitatively assessed using an area under the curve (AUC) analysis for PE classification and a coefficient of determination (R²) for the Qanadli score and the RV/LV diameter ratio.

RESULTS

Quantitative evaluation led to an overall AUC of 0.870 (95% confidence interval [CI]: 0.850-0.900) for PE classification task on the training set and an AUC of 0.852 (95% CI: 0.810-0.890) on the test set. Regression analysis yielded R² value of 0.717 (95% CI: 0.668-0.760) and of 0.723 (95% CI: 0.668-0.766) for the Qanadli score and the RV/LV diameter ratio estimation, respectively on the test set.

CONCLUSION

This study shows the feasibility of utilizing AI-based assistance tools in detecting blood clots and estimating PE severity scores with 3D CTPA examinations. This is achieved by leveraging blood clots and cardiac segmentations. Further studies are needed to assess the effectiveness of these tools in clinical practice.

Synthetic MR image generation of macrotrabecular-massive hepatocellular carcinoma using generative adversarial networks

PURPOSE

The purpose of this study was to develop a method for generating synthetic MR images of macrotrabecular-massive hepatocellular carcinoma (MTM-HCC).

MATERIALS AND METHODS

A set of abdominal MR images including fat-saturated T1-weighted images obtained during the arterial and portal venous phases of enhancement and T2-weighted images of 91 patients with MTM-HCC, and another set of MR abdominal images from 67 other patients were used. Synthetic images were obtained using a 3-step pipeline that consisted in: (i), generating a synthetic MTM-HCC tumor on a neutral background; (ii), randomly selecting a background among the 67 patients and a position inside the liver; and (iii), merging the generated tumor in the background at the specified location. Synthetic images were qualitatively evaluated by three radiologists and quantitatively assessed using a mix of 1-nearest neighbor classifier metric and Fréchet inception distance.

RESULTS

A set of 1000 triplets of synthetic MTM-HCC images with consistent contrasts were successfully generated. Evaluation of selected synthetic images by three radiologists showed that the method gave realistic, consistent and diversified images. Qualitative and quantitative evaluation led to an overall score of 0.64.

CONCLUSION

This study shows the feasibility of generating realistic synthetic MR images with very few training data, by leveraging the wide availability of liver backgrounds. Further studies are needed to assess the added value of those synthetic images for automatic diagnosis of MTM-HCC.

The PRO-ACTIVE trial protocol: a randomized study comparing the effectiveness of PROphylACTic swallow InterVEntion for patients receiving radiotherapy for head and neck cancer

BACKGROUND

Swallowing therapy is commonly provided as a treatment to lessen the risk or severity of dysphagia secondary to radiotherapy (RT) for head and neck cancer (HNC); however, best practice is not yet established. This trial will compare the effectiveness of prophylactic (high and low intensity) versus reactive interventions for swallowing in patients with HNC undergoing RT.

METHODS

This multi-site, international randomized clinical trial (RCT) will include 952 adult patients receiving radiotherapy for HNC and who are at high risk for post-RT dysphagia. Participants will be randomized to receive one of three interventions for swallowing during RT: RE-ACTIVE, started promptly if/when dysphagia is identified; PRO-ACTIVE EAT, low intensity prophylactic intervention started before RT commences; or, PRO-ACTIVE EAT+EXERCISE, high intensity prophylactic intervention also started before RT commences. We hypothesize that the PRO-ACTIVE therapies are more effective than late RE-ACTIVE therapy; and, that the more intensive PRO-ACTIVE (EAT + EXERCISE) is superior to the low intensive PRO-ACTIVE (EAT). The primary endpoint of effectiveness is duration of feeding tube dependency one year post radiation therapy, selected as a pragmatic outcome valued equally by diverse stakeholders (e.g., patients, caregivers and clinicians). Secondary outcomes will include objective measures of swallow physiology and function, pneumonia and weight loss, along with various patient-reported swallowing-related outcomes, such as quality of life, symptom burden, and self-efficacy.

DISCUSSION

Dysphagia is a common and potentially life-threatening chronic toxicity of radiotherapy, and a priority issue for HNC survivors. Yet, the optimal timing and intensity of swallowing therapy provided by a speech-language pathologist is not known. With no clearly preferred strategy, current practice is fraught with substantial variation. The pragmatic PRO-ACTIVE trial aims to specifically address the decisional dilemma of when swallowing therapy should begin (i.e., before or after a swallowing problem develops). The critical impact of this dilemma is heightened by the growing number of young HNC patients in healthcare systems that need to allocate resources most effectively. The results of the PRO-ACTIVE trial will address the global uncertainty regarding best practice for dysphagia management in HNC patients receiving radiotherapy.

TRIAL REGISTRATION

The protocol is registered with the US Patient Centered Outcomes Research Institute, and the PRO-ACTIVE trial was prospectively registered at ClinicalTrials.gov , under the identifier NCT03455608 ; First posted: Mar 6, 2018; Last verified: Jun 17, 2021. Protocol Version: 1.3 (January 27, 2020).

3D variable-density SPARKLING trajectories for high-resolution T2*-weighted magnetic resonance imaging

We have recently proposed a new optimization algorithm called SPARKLING (Spreading Projection Algorithm for Rapid K-space sampLING) to design efficient compressive sampling patterns for magnetic resonance imaging (MRI). This method has a few advantages over conventional non-Cartesian trajectories such as radial lines or spirals: i) it allows to sample the k-space along any arbitrary density while the other two are restricted to radial densities and ii) it optimizes the gradient waveforms for a given readout time. Here, we introduce an extension of the SPARKLING method for 3D imaging by considering both stacks-of-SPARKLING and fully 3D SPARKLING trajectories. Our method allowed to achieve an isotropic resolution of 600 μm in just 45 seconds for T2∗-weighted ex vivo brain imaging at 7 Tesla over a field-of-view of 200 × 200 × 140 mm³ . Preliminary in vivo human brain data shows that a stack-of-SPARKLING is less subject to off-resonance artifacts than a stack-of-spirals.

An empirical study of the maximum degree of undersampling in compressed sensing for T2*-weighted MRI

Magnetic Resonance Imaging (MRI) is one of the most dynamic and safe imaging modalities used in clinical routine today. Yet, one major limitation to this technique resides in its long acquisition times. Over the last decade, Compressed Sensing (CS) has been increasingly used to address this issue and offers to shorten MR scans by reconstructing images from undersampled Fourier data. Nevertheless, a quantitative guide on the degree of acceleration applicable to a given acquisition scenario is still lacking today, leading in practice to a trial-and-error approach in the selection of the appropriate undersampling factor. In this study, we shortly point out the existing theoretical sampling results in CS and their limitations which motivate the focus of this work: an empirical and quantitative analysis of the maximum degree of undersampling allowed by CS in the specific context of T₂^*-weighted MRI. We make use of a generic method based on retrospective undersampling to quantitatively deduce the maximum acceleration factor R_max which preserves a desired image quality as a function of the image resolution and the available signal-to-noise ratio (SNR). Our results quantify how larger acceleration factors can be applied to higher resolution images as long as a minimum SNR is guaranteed. In practice however, the maximum acceleration factor for a given resolution appears to be constrained by the available SNR inherent to the considered acquisition. Our analysis enables to take this a priori knowledge into account, allowing to derive a sequence-specific maximum acceleration factor adapted to the intrinsic SNR of any MR pipeline. These results obtained on an analytical T₂^*-weighted phantom image were corroborated by prospective experiments performed on MR data collected with radial trajectories on a 7 T scanner with the same contrast. The proposed framework allows to study other sequence weightings and therefore better optimize sequences when accelerated using CS.

Clustering dynamics of microbubbles exposed to low-pressure 1-MHz ultrasound

Ultrasound-driven microbubbles have been used in therapeutic applications to deliver drugs across capillaries and into cells or to dissolve blood clots. Yet the performance and safety of these applications have been difficult to control. Microbubbles exposed to ultrasound not only volumetrically oscillate, but also move due to acoustic radiation, or Bjerknes, forces. The purpose of this work was to understand the extent to which microbubbles moved and clustered due to secondary Bjerknes forces. A microbubble population was exposed to a 1-MHz ultrasound pulse with a peak-rarefactional pressure of 50-100 kPa and a pulse length of 20 ms. Microbubbles exposed to low-pressure therapeutic ultrasound were observed to cluster at clustering rates of 0.01-0.02 microbubbles per duration (in ms) per initial average inter-bubble distance (in μm), resulting in 1 to 3 clustered microbubbles per initial average inter-bubble distance (in μm). Higher pressures caused faster clustering rates and a larger number of clustered microbubbles. Experimental data revealed clustering time scales, cluster localizations, and cluster sizes that were in reasonable agreement with simulations using a time-averaged model at low pressures. This study demonstrates that clustering of microbubbles occurs within a few milliseconds and is likely to influence the distribution of stimuli produced in therapeutic applications.

Torsional behavior of axonal microtubule bundles

Axonal microtubule (MT) bundles crosslinked by microtubule-associated protein (MAP) tau are responsible for vital biological functions such as maintaining mechanical integrity and shape of the axon as well as facilitating axonal transport. Breaking and twisting of MTs have been previously observed in damaged undulated axons. Such breaking and twisting of MTs is suggested to cause axonal swellings that lead to axonal degeneration, which is known as "diffuse axonal injury". In particular, overstretching and torsion of axons can potentially damage the axonal cytoskeleton. Following our previous studies on mechanical response of axonal MT bundles under uniaxial tension and compression, this work seeks to characterize the mechanical behavior of MT bundles under pure torsion as well as a combination of torsional and tensile loads using a coarse-grained computational model. In the case of pure torsion, a competition between MAP tau tensile and MT bending energies is observed. After three turns, a transition occurs in the mechanical behavior of the bundle that is characterized by its diameter shrinkage. Furthermore, crosslink spacing is shown to considerably influence the mechanical response, with larger MAP tau spacing resulting in a higher rate of turns. Therefore, MAP tau crosslinking of MT filaments protects the bundle from excessive deformation. Simultaneous application of torsion and tension on MT bundles is shown to accelerate bundle failure, compared to pure tension experiments. MAP tau proteins fail in clusters of 10-100 elements located at the discontinuities or the ends of MT filaments. This failure occurs in a stepwise fashion, implying gradual accumulation of elastic tensile energy in crosslinks followed by rupture. Failure of large groups of interconnecting MAP tau proteins leads to detachment of MT filaments from the bundle near discontinuities. This study highlights the importance of torsional loading in axonal damage after traumatic brain injury.

Behavioral and neurochemical effects of dietary methyl donor deficiency combined with unpredictable chronic mild stress in rats

Methyl donor deficiencies and chronic stress cause depression independently, but their interaction has never been thoroughly evaluated. In our study, methyl donor deficient diet and chronic stress condition consisted respectively of a B2, B9, B12, and choline-free diet and a chronic mild stress procedure. Rats were randomly assigned to six groups with three "diet" conditions (free-feeding, pair-fed and methyl donor deficient diet) and two "stress" conditions (no-stress and stress) and were evaluated in the open-field, the elevated plus-maze and the forced swimming test. After the behavioral evaluation, corticosterone and homocysteine plasma levels were measured and dopamine, DOPAC, serotonin, 5HIAA concentrations were evaluated in several brain areas. Rats given a methyl donor deficient diet for 11 weeks causing elevated plasma homocysteine levels were compared to pair-fed and free-feeding rats with or without unpredictable chronic mild stress. Regardless of stress environmental conditions, the methyl donor deficient diet decreased plasma corticosterone levels and caused disinhibition in the elevated plus-maze condition relative to both control groups. However, stress potentiated the effects of the deficient regimen on rearing in the open-field and climbing in the forced swim test. The dietary changes involved in behavior and plasma corticosterone could be caused by homocysteine-induced decreases in dopamine and 5-hydroxytryptamine metabolites in selective brain regions and it can be noted that regardless of stress-conditions, methyl donor deficient diet decreases DOPAC/dopamine and 5HIAA/serotonin ratios in striatum and hypothalamus and selectively 5HIAA/serotonin ratio in the sensorimotor cortex. Our experimental data is particularly relevant in the context of neuropsychiatric disorders frequently associated with folate deficiency and hyperhomocysteinemia.

Toward a better understanding of brain lesions during metachromatic leukodystrophy evolution

BACKGROUND AND PURPOSE

The prospect of new therapies in MLD stresses the need to refine the indications for treatment. The aim of this study was, therefore, to perform a detailed analysis of MRI brain lesions at diagnosis and follow-up, to better understand the natural history of MLD.

MATERIAL AND METHODS

This retrospective case-control study (2005-2010) looked at 13 patients with MLD (2-5 years of age) with 28 MRIs (mean follow-up, 2 years), compared with 39 age- and sex-matched controls. All MRIs were evaluated qualitatively and semiquantitatively. The Student t test, Wilcoxon signed rank test, and Pearson correlation were used for statistical analysis (P < .05).

RESULTS

In addition to diffuse symmetric supratentorial WM T2 hyperintensities with a tigroid pattern (70%) and T2 hyperintensities in the CC (100%) and internal capsules (46%), we found significant GM abnormalities such as thalamic T2 hypointensity (92%), thalamic (23%, P < .05, EJ) and caudate nuclei (23%, P < .05, EJ) atrophy, and cerebellar atrophy without WM involvement (15%). The pattern of splenium involvement progression was misleading, with initially diffuse high signal intensity, which later became curvilinear before finally progressing to atrophy (23%, P < .05; EJ). This should not be mistaken for a disease regression. Spectroscopy confirmed a decrease in the NAA/Cr ratio, an increase in the Cho/Cr ratio and in myo-inositol, and a lactate resonance.

CONCLUSIONS

Thalamic changes may be a common finding in MLD, raising the prospect of primary GM lesions. This may prove important when evaluating the efficacy of new treatments.

Developing a disease prevention strategy in the Caribbean: the importance of assessing animal health-related risks at regional level

In 2009 CaribVET conducted a survey among Caribbean national Veterinary Services to assess perceptions of risk assessment and to identify the principal exotic diseases of concern in the region and their means of introduction. The results showed that the introduction of live animals was considered the most likely route of introduction of exotic animal pathogens, followed by the uncontrolled introduction of animal products by boat passengers. The results were used to define a regional strategy for assessing animal health risks that highlights the importance of within-region exchanges.

Laparoscopically inserted button colostomy as a venting stoma and access port for the administration of antegrade enemas in African degenerative leiomyopathy

African degenerative leiomyopathy (ADL) is a rare incurable disorder seen in African children, predominantly in southern and south-eastern Africa. ADL presents as chronic intestinal pseudo-obstruction. Management is traditionally conservative, with surgery restricted to the management of complications. We have placed Malone antegrade continence enema (MACE) stomas in the grossly dilated colon to vent accumulated gas and administer antegrade bowel enemas. This is done mainly for relief of gaseous distension and constipation in an attempt to provide symptomatic relief and improve quality of life. In this article, we present our preliminary results of laparoscopically assisted technique to insert a Mic-Key gastrostomy device as a 'button colostomy' in 8 patients over the past 6½ years.

Effects of ethanol and ecstasy on conditioned place preference in the rat

The club drug ecstasy (3,4-methylenedioxymethylamphetamine or MDMA) is often taken recreationally with ethanol (EtOH). We have shown previously that EtOH potentiates the psychomotor effects of MDMA in rats. More recently, we demonstrated in striatal slices that MDMA produced preferential release of serotonin, but when combined with EtOH, the preferential release shifted to dopamine, raising the possibility that administration of EtOH may increase the reward effect of MDMA. To address this possibility, adult male Long-Evans rats were tested for conditioned place preference following treatment with saline, EtOH (0.75 g/kg), MDMA (6.6 mg/kg) or the combination. The only condition that produced a preference for the compartment associated with the drug was that of the drug combination. The current data are in line with anecdotal reports and one study in humans, indicating that EtOH alters the pharmacological effects of MDMA including self reports of enhanced or prolonged euphoria. Thus, administration of EtOH might increase the risk for compulsive use of MDMA, an issue that warrants further study.

Electrolytic lesions of the ventral subiculum weakly alter spatial memory but potentiate amphetamine-induced locomotion

Adult Long-Evans male rats were subjected to electrolytic lesions of the ventral subiculum, and tested for locomotor activity in the home cage, reference and working memory in the water maze, working memory in the radial maze, and D-amphetamine-induced locomotion (1mg/kg, i.p.). When compared to their sham-operated counterparts, lesioned rats showed nocturnal hyperactivity, no reference memory deficit, but working memory was impaired in the water maze and during the initial stage of radial-maze testing. Their locomotor responsiveness to D-amphetamine was exaggerated. Histological verifications confirmed lesions in the ventral subiculum. Material stained for acetylcholinesterase activity indicated septohippocampal and commissural/associational sprouting, accounting for partial damage to the perforant paths. These results showed that ventral subiculum lesions (i) do not alter the capability of rats to learn repeatedly presented spatial information, and (ii) impair, but do not prevent, spatial working memory, suggesting that the ventral subiculum is preferentially involved in short-term memory for spatial locations. Given the electrolytic nature of the lesion, the lesion-induced potentiation of the locomotor response to amphetamine is probably easier explained by partial disruption of the perforant paths than by damage to neurons of the ventral subiculum.

Preoperative angioembolisation for life-threatening haemorrhage from Wilms' tumour: a case report

Wilms' tumour is one of the most common abdominal tumours of childhood. Severe perirenal bleeding resulting in consumptive coagulopathy and colonic obstruction are rare complications of Wilms' tumour. We present a case report of one patient with these two complications, their successful management with preoperative angioembolisation and emergency nephrectomy, and a review of the relevant literature.

Grafts of fetal septal cells after cholinergic immunotoxic denervation of the hippocampus: a functional dissociation between dorsal and ventral implantation sites

Three-month-old Long-Evans rats were subjected to intraseptal infusions of 0.8 microg of 192 IgG-saporin followed, 2 weeks later, by intrahippocampal suspension grafts containing fetal cells from the medial septum and the diagonal band of Broca. The suspensions were implanted in the dorsal or the ventral hippocampus. Sham-operated and lesion-only rats were used as controls. Between 18 and 32 weeks after grafting, all rats were tested in a water maze (using protocols placing emphasis on reference memory or on working memory) and an eight-arm radial maze. The lesion produced extensive cholinergic denervation of the hippocampus, as evidenced by reduced acetylcholinesterase-positivity and acetylcholine content. Depending upon their implantation site, the grafts restored an acetylcholinesterase-positive reinnervation pattern in either the dorsal or the ventral hippocampus. Nevertheless, the grafts failed to normalize the concentration of acetylcholine in either region. The cholinergic lesion impaired working memory performance in both the water maze and the radial maze. To a limited degree, reference memory was also altered. Grafts placed in the ventral hippocampus had no significant behavioral effect, whereas those placed in the dorsal hippocampus normalized working memory performance in the water maze. Our data show that infusion of 192 IgG-saporin into the septal region deprived the hippocampus of its cholinergic innervation and altered spatial working memory more consistently than spatial reference memory. Although the cholinergic nature of the graft-induced reinnervation remains to be established more clearly, these results further support the idea of a functional dissociation between the dorsal and the ventral hippocampus, the former being preferentially involved in spatial memory.

Application of the Malone antegrade continence enema principle in degenerative leiomyopathy

An 1-year-old boy with degenerative leiomyopathy (DL) presented with a volvulus of the transverse colon. After derotating the volvulus, we constructed a tube colostomy (TC) from the transverse colon. This TC has been used for the past 2 years by the patient for regular deflation of the colon and antegrade colonic enemas (ACE). We present this as a preliminary report of the use of the Malone ACE procedure in a patient with DL and review the relevant literature.

Cognitive performances and locomotor activity following dentate granule cell damage in rats: role of lesion extent and type of memory tested

Intradentate injection of colchicine is one of the techniques used to destroy granule cells. This study compared the behavioral effects of various amounts of colchicine (1.0, 3.0, and 6.0 microg; Col 1, Col 3, and Col 6, respectively) injected into the dentate gyrus of adult Long-Evans male rats. Starting 10 days after lesion surgery, behavioral testing assessed home-cage and open-field locomotion, alternation in a T-maze, water-maze, and radial-maze learning according to protocols placing emphasis on reference, and working memory. All of these tasks are sensitive to hippocampal disruption. Histological verifications showed that the extent of the lesions depends on the dose of colchicine (index of dentate gyrus shrinkage: -33% in Col 1, -54% in Col 3, and -67% in Col 6 rats). Colchicine dose-dependently increased nocturnal home cage activity (an effect found 10 days but not 5 months after surgery), but had no significant effect on open-field locomotion or T-maze alternation. A dose-dependent reference memory impairment was found during the acquisition of spatial navigation in the water maze; Col 3 and Col 6 rats were more impaired than Col 1 rats. During the probe trial (platform removed), control rats spent a longer distance swimming over the platform area than all rats with colchicine lesions. In the working memory version of the test, all rats with colchicine lesions showed significant deficits. The deficits were larger in Col 3 and Col 6 rats compared to Col 1 rats. The lesions had no effect on swimming speed. In the radial-maze test, there was also a dose-dependent working memory impairment. However, reference memory was disrupted in a manner that did not differ among the three groups of lesioned rats. Our data are in line with the view that the dentate gyrus plays an important role in the acquisition of new information and is an integral neural substrate for spatial reference and spatial working memory. They also suggest that damage to granule cells might have more pronounced effects on reference than on working memory in the radial maze. Finally, they demonstrate that part of the variability in the conclusions from previous experiments concerning the role of granule cells in cognitive processes, particularly in spatial learning and memory, may be due to the type of tests used and/or the extent of the damage produced.

Effects of MDL 73005 on water-maze performances and locomotor activity in scopolamine-treated rats

The stimulation of 5-HT1A receptors in the raphe or their blockade in the hippocampus can reduce cognitive deficits induced by blockade of muscarinic receptors in the hippocampus. We investigated the effects of MDL 73005 (8-[2-(2,3-dihydro-1,4-benzodioxin-2-ylmethylamino) ethyl]-8-azaspiro[4,5] decane-7,9-dione methyl sulphonate), an agonist at 5-HT1A somatodendritic autoreceptors and an antagonist at postsynaptic 5-HT1A receptors in rats treated systemically with scopolamine. Spatial memory was assessed in a water maze using protocols testing reference and working memory. Home cage locomotor activity was also determined. Working memory and locomotor activity were evaluated before and after para-chlorophenylalanine (pCPA) treatment. Scopolamine produced a weak impairment of reference memory at 0.5 mg/kg, and a more pronounced impairment of working memory at 0.25 and 0.5 mg/kg. MDL 73005 alone (2 mg/kg, i.p.) had no effect, but prevented the memory impairments induced by 0.25 mg/kg of scopolamine. Scopolamine induced hyperlocomotion. MDL 73005 alone did not affect locomotor activity, but exacerbated the hyperlocomotion induced by 0.5 mg/kg of scopolamine. pCPA did not abolish the effects of MDL 73005, suggesting that these effects were not due to an action at presynaptic receptors, or even that they involved receptors other than serotonergic ones (e.g., D2). In conclusion, MDL 73005 is able to antagonise moderate spatial memory dysfunctions induced by systemic muscarinic blockade.

Using standardized patients to teach end-of-life skills to clinical clerks

BACKGROUND

This study examines the use of standardized patients to teach end-of-life skills to clinical clerks.

METHODS

Forty-four third-year clinical medical students participated in a half-day standardized patient workshop that was precepted by faculty members. The students were asked to report on their perceived abilities prior to the workshop and these were compared with post-workshop responses. The students were also asked to provide an overall evaluation of the standardized patient workshop as a learning experience.

RESULTS

The students uniformly found the workshop to be realistic, found the faculty facilitators to be helpful, and found the workshop effective in enhancing their end-of-life skills. Following participation in the workshop, students reported significant improvements in their perceived abilities to deal with pain, to appreciate cultural differences in the dying process, to deliver bad news, and to understand the legalities of do-not-resuscitate orders.

CONCLUSIONS

Standardized patient workshops are useful for teaching end-of-life skills.

Cloning of a palmitoyl-acyl carrier protein thioesterase from oil palm

A palmitoyl-acyl carrier protein (ACP) thioesterase cDNA clone was isolated from an oil palm cDNA library. The cDNA was expressed in Escherichia coli as a glutathione S-transferase fusion protein and a crude bacterial extract was assayed for acyl-CoA-hydrolysing activity. The recombinant enzyme was able to hydrolyse medium- and long-chain acyl-CoAs. Northern-blot analysis showed a high level of gene expression in leaf, flower and 15-, 17- and 18-week mesocarp tissues. Low-level gene expression was detected in germinated seedlings and 8- and 12-week mesocarp tissues, but no transcript was detected in any kernel tissues. Southern-blot analysis indicated the presence of a single gene and we have also isolated a genomic clone using the cDNA as a probe. Two genomic fragments were subcloned and a 7 kb contiguous stretch of the oil palm genome was sequenced. Comparison of this sequence with the cDNA sequence identified a putative 93 amino acid transit peptide, most of which is missing from the cDNA. The coding region of the gene consisted of seven exons and six introns.

Central cholinergic depletion induced by 192 IgG-saporin alleviates the sedative effects of propofol in rats

We examined the effect of central cholinergic depletion on the sedative potency of propofol in rats. Depletion was produced by intracerebroventricular administration of an immunotoxin specific to cholinergic neurones (192 IgG-Saporin; 2 microg). As a result of this lesion, acetylcholine concentration was reduced by about 40% in the frontoparietal cortex and in the hippocampus but was essentially normal in the striatum and cerebellum. Sedation in rats was assessed as the decrease in locomotor activity. Sedative potency of propofol (30 mg kg(-1) i.p.) was reduced by about 50% in rats who received the injection of 192 IgG-Saporin as compared to controls. These results show that a central cholinergic depletion alleviates the sedative effect of propofol, and indicates that basal forebrain cholinergic neurones might mediate part of the sedative/hypnotic effects of propofol.

Crystallization and preliminary X-ray analysis of the auxin receptor ABP1

Auxin-binding protein (ABP1) is an important receptor for the plant hormone auxin that is involved with many growth and developmental responses in plants. The maize ABP1 gene has been expressed in insect cells, purified and crystallized. Type II crystals are monoclinic, with two glycosylated homodimers in the asymmetric unit, and diffract to 1.9 A using synchrotron radiation.

When injected into the fimbria-fornix/cingular bundle, not in the raphe, 5,7-dihydroxytryptamine prevents amphetamine-induced hyperlocomotion

The locomotor effects of acute amphetamine treatment (1 mg/kg, i.p.) were assessed in Long-Evans rats after 5,7-dihydroxytryptamine (5, 7-DHT) injections into the fimbria-fornix/cingular bundle (FiFx/CB; 4 microg/side), or the dorsal and median raphe (Raphe; 10 microg). In control rats, amphetamine induced a significant increase of home-cage activity for about 2 h. This effect was similar in Raphe rats, but was absent in FiFx/CB rats. The raphe lesions reduced serotonin concentrations by 50% in the dorsal hippocampus, 75% in the ventral hippocampus and 58% in the fronto-parietal cortex. After FiFx/CB lesions, the reduction amounted 50, 61 and only 25%, in each of these regions, respectively. In the fronto-partietal cortex, dopamine concentration was significantly decreased in Raphe (-27%) and FiFx/CB rats (-65%). The results suggest that a serotonergic denervation of the hippocampus by injections of 5,7-DHT into the FiFx/CB pathways hampers the stimulating effects of amphetamine on locomotor activity. This effect might be related to the reduced dopaminergic tone in the fronto-parietal cortex.

Immunohistochemical and neurochemical correlates of learning deficits in aged rats

This study examined whether cholinergic and monoaminergic dysfunctions in the brain could be related to spatial learning capabilities in 26-month-old, as compared to three-month-old, Long-Evans female rats. Performances were evaluated in the water maze task and used to constitute subgroups with a cluster analysis statistical procedure. In the first experiment (histological approach), the first cluster contained young rats and aged unimpaired rats, the second one aged rats with moderate impairment and the third one aged rats with severe impairment. Aged rats showed a reduced number of choline acetyltransferase- and p75(NTR)-positive neurons in the nucleus basalis magnocellularis, and choline acetyltransferase-positive neurons in the striatum. In the second experiment (neurochemical approach), the three clusters comprised young rats, aged rats with moderate impairment and aged rats with severe impairment. Alterations related to aging consisted of reduced concentration of acetylcholine, norepinephrine and serotonin in the striatum, serotonin in the occipital cortex, dopamine and norepinephrine in the dorsal hippocampus, and norepinephrine in the ventral hippocampus. In the first experiment, there were significant correlations between water maze performance and the number of; (i) choline acetyltransferase- and p75(NTR)-positive neurons in the nucleus basalis magnocellularis; (ii) choline acetyltransferase-positive neurons in the striatum and; (iii) p75(NTR)-positive neurons in the medial septum. In the second experiment, water maze performance was correlated with the concentration of; (i) acetylcholine and serotonin in the striatum; (ii) serotonin and norepinephrine in the dorsal hippocampus; (iii) norepinephrine in the frontoparietal cortex and; (iv) with other functional markers such as the 5-hydroxyindoleacetic acid/serotonin ratio in the striatum, 3,4-dihydroxyphenylacetic acid/dopamine ratio in the dorsal hippocampus, 5-hydroxyindoleacetic acid/serotonin and homovanillic acid/dopamine ratios in the frontoparietal cortex, and 3,4-dihydroxyphenylacetic acid/dopamine ratio in the occipital cortex. The results indicate that cognitive deficits related to aging might involve concomitant alterations of various neurochemical systems in several brain regions such as the striatum, the hippocampus or the cortex. It also seems that these alterations occur in a complex way which, in addition to the loss of cholinergic neurons in the basal forebrain, affects dopaminergic, noradrenergic and serotonergic processes.

Preserved olfactory short-term memory after combined cholinergic and serotonergic lesions using 192 IgG-saporin and 5,7-dihydroxytryptamine in rats

Young adult Long-Evans female rats were subjected to intracerebroventricular injections of 150 microg 5,7-dihydroxytryptamine (5,7-DHT), 2 microg 192 IgG-saporin, or a combination of both neurotoxins. All rats were tested for olfactory recognition (short-term memory) using a task based on spontaneous exploration of odor sources. Compared with animals undergoing sham operations, 5,7-DHT reduced the concentration of serotonin by 60-80% in the frontoparietal cortex, hippocampus, striatum and the olfactory bulbs. After 192 IgG-saporin treatment, acetylcholine concentrations were reduced by approximately 40% in all these structures, except the striatum. Neither lesion induced a significant deficit in olfactory recognition. These data suggest that combined lesions of cholinergic and serotonergic neurons in the rat brain do not alter olfactory perception or olfactory short-term memory.

Intraseptal infusions of 8-OH-DPAT in the rat impairs water-maze performances: effects on memory or anxiety?

In the rat, 5-HT1A receptors are found on medial septal cholinergic neurons. The effects of intraseptal infusions of the 5-HT1A receptor agonist 8-OH-DPAT (8-hydroxy-2-(di-n-propyl-amino)-tertralin) were assessed on reference memory performances in a water maze. Compared with vehicle infusions, 0.5 and 4 microg of 8-OH-DPAT significantly impaired (but did not prevent) acquisition of the task and probe-trial performances. The results suggest that activation of 5-TH1A receptors in the (medial) septal area impairs spatial learning, perhaps directly by reducing the hippocampal cholinergic tonus, or indirectly by an effect on anxiety.

Combined lesions of cholinergic and serotonergic neurons in the rat brain using 192 IgG-saporin and 5,7-dihydroxytryptamine: neurochemical and behavioural characterization

This study assessed behavioural and neurochemical effects of i.c.v. injections of both the cholinergic toxin 192 IgG-saporin (2 microgram) and the serotonergic toxin 5,7-dihydroxytryptamine (5,7-DHT; 150 microgram) in Long-Evans female rats. Dependent behavioural variables were locomotor activity, forced T-maze alternation, beam walking, Morris water-maze (working and reference memory) and radial-maze performances. After killing by microwave irradiation, the concentrations of acetylcholine, monoamines and 5-hydroxyindoleacetic acid (5-HIAA) were measured in the hippocampus, frontoparietal cortex and striatum. 192 IgG-saporin reduced the concentration of acetylcholine by approximately 40% in the frontoparietal cortex and hippocampus, but had no effect in the striatum. 5,7-DHT lesions reduced the concentration of serotonin by 60% in the frontoparietal cortex and 80% in the hippocampus and striatum. Noradrenaline was unchanged in all structures except the ventral hippocampus where it was slightly increased in rats given 192 IgG-saporin. Cholinergic lesions induced severe motor deficits but had no other effect. Serotonergic lesions produced diurnal and nocturnal hyperactivity but had no other effect. Rats with combined lesions were more active than those with only serotonergic lesions, showed motor dysfunctions similar to those found in rats with cholinergic lesions alone, and exhibited impaired performances in the T-maze alternation test, the water-maze working memory test and the radial-maze. Taken together and although cholinergic lesions were not maximal, these data show that 192 IgG-saporin and 5,7-DHT lesions can be combined to selectively damage cholinergic and serotonergic neurons, and confirm that cholinergic-serotonergic interactions play an important role in some aspects of memory, particularly in spatial working memory.

Intrahippocampal grafts containing cholinergic and serotonergic fetal neurons ameliorate spatial reference but not working memory in rats with fimbria-fornix/cingular bundle lesions

Three-month-old Long-Evans female rats sustained aspirative lesions of the dorsal septohippocampal pathways and, 2 weeks later, received intrahippocampal suspension grafts containing cells from the mesencephalic raphe, cells from the medial septum and the diagonal band of Broca, or a mixture of both. Lesion-only and sham-operated rats were used as controls. All rats were tested for locomotor activity 1 week, 3 and 5 months after lesion surgery, for spatial working memory in a radial maze from 5 to 9 months, and for reference and working memory in a water tank during the 9th month after lesioning. Determination of hippocampal concentration of acetylcholine, noradrenaline, and serotonin was made after completion of behavioral testing. Compared to sham-operated rats, all rats with lesions, whether grafted or not, exhibited increased levels of locomotor activity and made more errors in the radial maze. The lesioned rats were also impaired in the probe trial (30 first seconds) of the water-tank test made according to a protocol requiring intact reference memory capabilities. While rats with septal or raphe grafts were also impaired, the rats with co-grafts showed performances not significantly different from those of sham-operated rats. With a protocol requiring intact working memory capabilities, all lesioned rats, whether grafted or not, were impaired in the water-tank test. In the dorsal hippocampus of lesion-only rats, the concentration of acetylcholine and serotonin was significantly reduced. In rats with septal grafts or co-grafts, the concentration of acetylcholine was close to normal, as was that of serotonin in rats with raphe grafts or co-grafts. These results confirm previous findings showing that co-grafts enabled the neurochemical properties of single grafts to be combined. Data from the water-tank test suggest that cholinergic and serotonergic hippocampal reinnervations by fetal cell grafts may induce partial recovery of spatial reference, but not working memory capabilities in rats.

Modulation of 5-hydroxytryptamine release in hippocampal slices of rats: effects of fimbria-fornix lesions on 5-HT1B-autoreceptor and alpha2-heteroreceptor function

Fimbria-fornix lesions disrupt important parts of serotonergic and noradrenergic hippocampal afferents and elicit sprouting of sympathetic fibers from the superior cervical ganglion. Since 5-hydroxytryptamine (5-HT) release in the hippocampus is modulated by 5-HT1B auto- and alpha2-heteroreceptors, we investigated whether such lesions may alter these presynaptic mechanisms. Hippocampal slices of sham-operated (SHAM) and fimbria-fornix-lesioned (LES) rats (14 months after surgery) were preincubated with [3H]5-HT, superfused continuously, and stimulated electrically using two stimulation conditions: either (a) 360 pulses 3 Hz, or (b) 20 pulses 100 Hz (2 ms, 28 mA, 4 V/chamber). The amount of [3H]5-HT taken up by slices from LES rats was significantly reduced, whereas the evoked 5-HT release (in percent of tissue-3H) was unchanged compared to that of SHAM rats. The 5-HT1B agonist CP 93,129 or the alpha2-agonist UK 14,304 reduced the evoked 5-HT release more potently in slices from LES rats, but only using stimulation condition (a), which permits inhibition by endogenously released transmitters. In LES rats, the facilitatory effect of the 5-HT antagonist metitepine was weaker, whereas that of the alpha2-antagonist idazoxane was more pronounced than in SHAM rats. In LES rats, hippocampal 5-HT content was reduced to about 45% of SHAM levels, whereas that of noradrenaline was increased by about 30% (high-performance liquid chromatography). We conclude: (1) despite LES-induced changes in tissue levels of endogenous ligands, there is no down- or upregulation of 5-HT1B-autoreceptors or alpha2-heteroreceptors on serotonergic neurons in the denervated rat hippocampus. (2) The reduced endogenous autoinhibition (by 5-HT) seems to be compensated for by an increased heteroinhibition (by noradrenaline).

Hypothyroldism in a neonate following excision of a cervical teratoma

Hypothyroidism developed in a neonate following the excision of a large cervical teratoma. This finding supports the observation that cervical teratomas commonly arise from thyroid tissue. Thyroid function tests should be performed routinely in all patients in whom identifiable residual thyroid tissue is not demonstrated at the conclusion of the operation.

Biosynthesis of C18 polyunsaturated fatty acids in microsomal membrane preparations from the filamentous fungus Mucor circinelloides

The biosynthesis of C18 polyunsaturated fatty acids has been studied in the fungus Mucor circinelloides. Microsomal membrane preparations contained delta9, delta12 and delta6 desaturase activities. The delta9 desaturase exhibited characteristics similar to those of the animal and yeast delta9 desaturases in being membrane bound and utilising stearoyl-CoA as substrate. Cytochrome b5 (a soluble form lacking the 20-amino-acid hydrophobic C-terminus) stimulated desaturation and was identified as a major cytochrome component of the membranes. A high ferricyanide reductase activity (indicative of NADH:cytochrome b5 reductase activity) coupled to inhibition by cyanide further supported the similarity with the mammalian and yeast enzymes. Time-course studies with radiolabelled oleoyl-CoA showed that the oleate [18:1(9)] was transferred to position sn-2 of phosphatidylcholine (PtdCho) and was desaturated to linoleoyl-PtdCho. Removal of the excess oleoyl-CoA from the membranes prior to addition of reductant confirmed that oleoyl-PtdCho is a substrate for the delta12 desaturase. The entry of oleate at this position of the phospholipid was facilitated by the activity of lyso-PtdCho:acyl-CoA acyltransferase (LPCAT), which readily transferred oleate from oleoyl-CoA to lyso-PtdCho. Desaturation of oleate at the sn-1 position of PtdCho was also demonstrated after the entry of oleate in to the phospholipid by the enzymes of the Kennedy pathway. Thus oleate at sn-1 and sn-2 positions served as substrate for the delta12 desaturase and is consistent with observations in oil seed tissues. LPCAT activity was substantially higher than that observed with lysophosphatidylethanolamine:acyl-CoA acyltransferase (LPEAT) indicating that oleate is less effectively channelled to phosphatidylethanolamine for linoleate synthesis. No desaturation on phosphatidylinositol could be demonstrated. Delta6 desaturase utilised linoleate at the sn-2 position of exogenously supplied PtdCho presented to the membranes in the presence of reductant. Thus, the entry of substrates into PtdCho via LPCAT and the synthesis of linoleate [18:2(9,12)] and gamma-linolenate [18:3(6,9,12)] on this phospholipid is similar to that reported for oil seed membranes.

Acute appendicitis among black South Africans

Acute appendicitis has become the commonest nontrauma-related abdominal surgical emergency at Cecilia Makiwane Hospital. The records of 122 patients undergoing appendicectomy were reviewed. Attention is drawn to late presentation and the high complication rare encountered. Mortality rate (0.8%) and overall diagnostic accuracy (85%) were acceptable. The need for adequate patient education is stressed as a possible measure to reduce high morbidity associated with late presentation.

Effects of a sour bolus on oropharyngeal swallowing measures in patients with neurogenic dysphagia

This study examines the effects of a sour bolus (50% lemon juice, 50% barium liquid) on pharyngeal swallow measures in two groups of patients with neurogenic dysphagia. Group 1 consisted of 19 patients who had suffered at least one stroke. Group 2 consisted of 8 patients with dysphagia related to other neurogenic etiologies. All patients were selected because they exhibited delays in the onset of the oral swallow and delays in triggering the pharyngeal swallow on boluses of 1 ml and 3 ml liquid barium during videofluoroscopy. Results showed significant improvement in oral onset of the swallow in both groups of patients and a significant reduction in pharyngeal swallow delay in Group 1 patients and in frequency of aspiration in Group 2 patients with the sour as compared to the non-sour boluses. Other selected swallow measures in both subject groups also improved with the sour bolus. Volume effects were present but not as consistently as in prior studies. Implications for swallow therapy are discussed.

Hippocampal amino acid concentrations after raphe and/or septal cell suspension grafts in rats with fimbria-fornix lesions

Two weeks after infracallosal electrolytic fimbria-fornix lesions, Long-Evans female rats received intrahippocampal suspension grafts of either fetal septal or mesencephalic raphe tissue, or a mixture of both. Ten months after lesion surgery, the concentrations of alanine, aspartate, GABA, glutamate, glutamine, glycine, serine and taurine were determined in a dorsal, a "middle" and a ventral region of the hippocampus. We found neither the lesions nor the grafts to have significantly modified the concentration of these amino acids which, in all groups, presented a regional heterogeneity in their hippocampal distribution. GABA, glutamate and glutamine were highest in the ventral hippocampus, whereas the other amino acids were highest in the dorsal region. Our results (i) show that fimbria-fornix lesions do not result in lasting effects on hippocampal concentrations of the assessed amino acids, (ii) confirm the regional heterogeneity in the distribution of these amino acids in the hippocampus and (iii) demonstrate that cell suspension grafts of fetal septal or mesencephalic raphe tissue, as well as grafts of a mixture of both of these tissues, do not exert a non-specific effect on either of the amino acid concentrations measured. These data complete those of the preceeding paper [Kiss et al. (1990) Neuroscience 36, 61-72] concerning the effects of the same grafts on hippocampal cholinergic, serotonergic and noradrenergic markers, as well as on several behavioural variables.

The value of abrasive cytology in the early detection of oesophageal carcinoma. A pilot survey in Ciskei

The use of abrasive cytology as a screening procedure in the diagnosis of early cancer of the oesophagus among asymptomatic rural Ciskeians was assessed. An inexpensive, locally manufactured brush biopsy capsule was used to obtain cytological material from 1,336 subjects. The technique gives a high yield, has a high predictive value and identifies a high prevalence of sufferers at the detectable preclinical phase of the disease.

Effects of maneuvers on swallowing function in a dysphagic oral cancer patient

This study examined the effects of three swallow maneuvers: (1) the supraglottic swallow (voluntary closure of the vocal folds prior to the swallow); (2) the super-supraglottic swallow (airway closure at the level of the arytenoid to base of epiglottis); and (3) the Mendelsohn maneuver (voluntary prolongation of laryngeal elevation and cricopharyngeal opening during swallow) on swallow functioning in a 47-year-old patient who underwent right composite resection for a squamous cell carcinoma of the right retromolar trigone. All maneuvers were employed during the same videofluorographic (VFG) swallow study conducted 6 months after the patient's surgery. Biomechanical analysis of 3-mL swallows defined the extent and timing of tongue base retraction to the posterior pharyngeal wall, laryngeal elevation, laryngeal closure and cricopharyngeal opening during swallows with and without maneuvers. Airway closure duration was prolonged during supraglottic and super-supraglottic swallows, but aspiration was not eliminated. Use of the Mendelsohn maneuver improved coordination and timing of pharyngeal swallow events, including timing of posterior movement of the tongue base to the pharyngeal wall in relation to airway closure and cricopharyngeal opening, with elimination of aspiration. The Mendelsohn maneuver compensated for anatomic and physiologic changes in the oropharyngeal swallow and enabled reinstatement of safe oral intake in this surgically treated head and neck cancer patient who was previously unable to take nutrition orally.

Comparison of simultaneous 99mTc-HMPAO and 111In oxine labelled white cell scans in the assessment of inflammatory bowel disease

Forty-seven patients, 29 with chronic inflammatory bowel disease (IBD) and 18 with presumed irritable bowel syndrome, including one with uncomplicated diverticular disease, were studied with simultaneous technetium-99m hexamethylpropylene amine oxime and indium-111 oxine labelled leucocyte scans performed at 1, 3 and 24 h. Twenty-seven patients with IBD had active disease as judged by clinical and laboratory criteria and all of these had positive scans with both agents. No false positive studies were obtained. The 1-h 99mTc-HMPAO WBC scans showed the same distribution to disease as the 3-h 111-In WBC scans, with no difference in intensity (P < 0.92); they showed more extensive disease (P < 0.02) and more intense uptake (P < 0.001) than did the 1-h 111-In scans. The 3-h 99mTc-HMPAO WBC scans showed more extensive disease (P < 0.002), with greater intensity (P < 0.0005), than did the 3-h 111In WBC scans. Physiological bowel activity on 3-h 99mTc-HMPAO WBC scans was present in 12 patients but was faint and did not interfere with assessment of disease extent and activity. It is concluded that in terms of isotope availability, radiation dosimetry and image quality, 99mTc-HMPAO is the agent of choice in detecting active IBD, with localization of disease possible at 1-h after re-injection and optimal resolution and definition of disease extent at 3 h. A negative scan reliably excludes active disease.

Impact of the diagnostic procedure on outcome measures of swallowing rehabilitation in head and neck cancer patients

This study was designed to determine whether swallow rehabilitation outcomes were affected by the type of evaluation procedure utilized by the clinician. The two evaluation techniques compared were the bedside examination and videofluoroscopy (the modified barium swallow). Ten institutions participated in this study, enrolling a total of 103 partial laryngectomized patients, 21 in the bedside arm and 82 in the videofluoroscopy arm. Data on recovery of oral intake were collected weekly. All patients received an X-ray study of swallow at 3 months after the operation. Mean time to oral intake of food was significantly lower in patients assessed with bedside examination. Overall swallow measures of transit times and swallow efficiencies after 3 months revealed significantly better function in the videofluoroscopy group. Results are discussed in terms of the visibility of swallow physiology with the two assessment techniques, the accuracy of therapy planning with the bedside examination versus videofluoroscopy and the ability of head and neck cancer patients to tolerate some aspiration without developing aspiration pneumonia.

Brush cytology technique in the detection of oesophageal carcinoma in the asymptomatic, high risk subject; a pilot survey

This study assesses the reliability of abrasive brush cytology in the diagnosis of early cancer of the oesophagus among asymptomatic rural Ciskeians. An inexpensive locally manufactured brush biopsy capsule was used to obtain cytological material from 1336 subjects; 59% of them were brushed a second time. The technique appears to have a high sensitivity (90%) and specificity (99.9%). Three of five asymptomatic subjects diagnosed as having early oesophageal cancer refused further treatment, indicating the importance of health education as a prerequisite to the introduction of a screening programme for oesophageal cancer.