Learning while multitasking: short and long-term benefits of brain stimulation

We employed a simulated production task that mimics the real-world skill acquisition required of operators working in control rooms of power plants to assess short and long-term effects of transcranial random noise stimulation (tRNS). tRNS has shown potential for enhancing learning and performance of cognitive skills. Forty subjects (24 female) learned how to execute the simulated production task during the training phase and were required to perform a secondary task during the skill acquisition phase while they received active (12 min) or sham tRNS on DLPFC. After 2 weeks they had to recall the task again without any stimulation. The results demonstrate that tRNS promoted better multitasking as reflected by better performance in a secondary task during and immediately after tRNS. However, 2 weeks later, beneficial effect of tRNS on retention was moderated by general mental ability. Particularly, tRNS benefited those with lower general mental ability. Practitioner summary: By using a simulated production task, we assessed the effects of tRNS on learning and skill retention. The study indicates that neurostimulation can enhance the learning of multiple complex tasks. Moreover, it shows that retention of those tasks can be supported by neurostimulation, especially for those with lower general mental ability.

The Influence of Prebiotics on Neurobiology and Behavior

Manipulating the intestinal microbiota for the benefit of the brain is a concept that has become widely acknowledged. Prebiotics are nondigestible nutrients (i.e., fibers, carbohydrates, or various saccharides) that proliferate intrinsic, beneficial gut bacteria, and so provide an alternative strategy for effectively altering the enteric ecosystem, and thence brain function. Rodent studies demonstrating neurobiological changes following prebiotic intake are slowly emerging, and have thus far revealed significant benefits in disease models, including antiinflammatory and neuroprotective actions. There are also compelling data showing the robust and favorable effects of prebiotics on several behavioral paradigms including, anxiety, learning, and memory. At present, studies in humans are limited, though there is strong evidence for prebiotics modulating emotional processes and the neuroendocrine stress response that may underlie the pathophysiology of anxiety. While the mechanistic details linking the enteric microbiota to the central nervous system remain to be elucidated, there are a number of considerations that can guide future studies. These include the modulation of intestinal endocrine systems and inflammatory cascades, as well as direct interaction with the enteric nervous system and gut mucosa. Our knowledge of gut microbiome-brain communication is steadily progressing, and thorough investigations validating the use of prebiotics in the treatment of neuropsychiatric disorders would be highly valued and are encouraged.

Sensory-motor polyneuropathy occurring in variant maple syrup urine disease

Maple syrup urine disease (MSUD; OMIM 248600) results from an inherited deficiency of the branched-chain ketoacid dehydrogenase (BCKD) complex. Approximately 20% of patients with BCKD deficiency are non-classic variants of MSUD with differing clinical severity. Outcomes for this cohort are generally favourable; episodes of metabolic decompensation do not appear to correlate with adverse events if acute management is promptly provided. A case of predominantly axonal sensory-motor neuropathy following metabolic decompensation which persisted for a number of months is presented in an adolescent girl with variant (intermediate type) MSUD. EMG and nerve conduction studies suggested a pre-existent asymptomatic chronic neuropathy, exacerbated by the acute decompensation. Peak leucine concentration at decompensation was 1083 μmol/L. The patient had laboratory signs of secondary mitochondrial respiratory chain dysfunction at presentation. She had been on a moderate dose of thiamine prior to decompensation; thiamine and pyridoxine blood concentrations were normal. This, to our knowledge, is the first report of a neuropathy presenting in a patient with a decompensation of variant MSUD. We propose that this presentation resembles the intermittent neuropathy observed in pyruvate dehydrogenase deficiency and may reflect secondary inhibition of pyruvate dehydrogenase activity by MSUD metabolites.

Focally enhanced gastritis in children with Crohn's disease and ulcerative colitis

OBJECTIVES

Focally enhanced gastritis (FEG) has been suggested as a specific diagnostic marker for patients with Crohn's disease. However, the utility of FEG for distinguishing Crohn's disease from ulcerative colitis is uncertain in adults, and the occurrence of this lesion in children has not been defined. The aim of this study was to evaluate the occurrence of FEG and other gastric histological abnormalities in children with inflammatory bowel disease (IBD) and to examine the utility of FEG in discriminating between ulcerative colitis and Crohn's disease.

METHODS

This is a retrospective, case-controlled study of upper GI histopathological findings in children with IBD. Gastric histopathology was defined and graded according to the Updated Sydney System.

RESULTS

FEG was present in 28 of 43 (65.1%) children with Crohn's disease and five of 24 (20.8%) children with ulcerative colitis, compared to three of 132 (2.3%) children without IBD or one of 39 (2.6%) children with Helicobacter pylori infection. There were no differences between those with and without FEG with regard to upper GI symptoms or previous anti-inflammatory drug ingestion (5-aminosalicylic acid compounds or steroids). All patients with H. pylori infection had chronic antral gastritis, but only one child with H. pylori had FEG. In addition, mild to moderate chronic gastritis was present in 15 of 43 (34.9%) children with Crohn's disease and in 12 of 24 (50%) patients with ulcerative colitis.

CONCLUSIONS

The presence of FEG suggests underlying IBD. Although FEG is particularly common in children with Crohn's disease, it does not reliably differentiate between Crohn's disease and ulcerative colitis.

Experience with twenty-eight cases of systolic anterior motion after mitral valve reconstruction by the Carpentier technique

Systolic anterior motion of the mitral valve with left ventricular outflow tract obstruction after Carpentier-type mitral reconstruction with ring annuloplasty has led some surgeons to abandon an otherwise successful repair or to avoid use of a rigid ring. To assess the long-term significance of such motion, we studied 439 patients undergoing Carpenter mitral reconstruction at our institution between March 1981 and June 1990. The hospital mortality rate was 4.8% (21/439) overall and 3.7% (9/243) for isolated mitral reconstruction. Systolic anterior motion was found in 6.4% (28/438) after the operation, and 2.3% (10/438) had a coexisting left ventricular outflow tract gradient (mean 53 mm Hg). Of the 28 patients with systolic anterior motion, 27 (96.4%) had leaflet prolapse, 17 (60.7%) had undergone more than a 3 cm resection of the posterior leaflet, and two (7.1%) had preexisting idiopathic hypertrophic subaortic stenosis. All patients were treated medically, 14 with negative inotropic agents. Follow-up echocardiograms at a mean of 32 months demonstrated the disappearance of systolic anterior motion in 13 of 28 patients (46.4%) and resolution of the outflow tract gradient in 10 of 10 (100%). At follow-up only one patient was in New York Heart Association class III or IV and required reoperation for rheumatic mitral insufficiency. These data demonstrate that systolic anterior motion after Carpentier mitral reconstruction with ring annuloplasty is not prevalent and should be managed medically in most cases. Associated left ventricular outflow tract obstruction resolves with medical treatment.

Clinical evaluation of high-frequency (ultrasonic) mechanical débridement in the surgical treatment of calcific aortic stenosis

Repair of aortic valve stenosis due to calcific degeneration may lead to hemodynamic and clinical improvement without the problems inherent with prosthetic valves. We have evaluated the use of a device capable of débriding calcium, the Cavitron ultrasonic aspirator (CUSA), as an adjunct to mechanical débridement in the repair of calcific aortic stenosis. Ten patients (five women), ages 63 to 83 years, were studied by M-mode, two-dimensional, and Doppler echocardiography before and an average of 26 (range 3 to 124) days after this procedure. The degree of calcification of the valve cusps was clearly reduced. The maximal cusp excursion increased from 0.7 +/- 0.1 cm preoperatively to 1.5 +/- 0.4 cm postoperatively (p = 0.006). The peak aortic gradient fell from 80 +/- 36 mm Hg to 28 +/- 10 mm Hg (p = 0.0007). The mean aortic gradient fell from 53 +/- 20 mm Hg to 16 +/- 5 mm Hg (p less than 0.0001). Aortic valve area calculated by the continuity equation increased from 0.6 + 0.2 cm2 to 1.6 +/- 0.6 cm2 (p = 0.0009). No patient had more than mild aortic insufficiency preoperatively. Postoperatively, color Doppler flow mapping revealed severe aortic insufficiency in two patients. Seven patients had further echocardiographic evaluation 99 (range 33 to 196) days after the procedure. These studies revealed the development of severe aortic insufficiency in an additional four patients. Four patients with severe symptomatic aortic insufficiency eventually underwent aortic valve replacement. Pathology revealed scarring and retraction of the aortic cusps. Widening of the commissures was responsible for the severe aortic insufficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of mitral valve reconstruction with mitral valve replacement: intermediate-term results

The continued good results after mitral valve reconstruction prompted this retrospective study to compare operative and late results from our institutional experience since 1976 with 975 porcine mitral valve replacements (MVRs) (1976 to December 1987), 169 mechanical MVRs (1976 to December 1987), and 280 Carpentier-type mitral valve reconstructions (CVRs) (1980 to mid-1988). The operative mortality was 2.0% for isolated CVR, 6.6% for isolated mechanical MVR, and 8.5% for isolated porcine MVR. The overall operative mortality was 5.0% for CVR, 16.6% for mechanical MVR, and 10.6% for porcine MVR. The overall 5-year survival including hospital deaths was 76% for CVR, 72% for mechanical MVR, and 69% for porcine MVR. By multivariate analysis, the predictors of increased operative risk and of decreased survival were age, New York Heart Association functional class IV status, previous cardiac operation, and performance of concomitant cardiac surgical procedures. The type of valvular procedure was not predictive of operative risk or overall survival. The 5-year freedom from reoperation was 94.4% for nonrheumatic patients having CVR, 77.4% for rheumatic patients having CVR, 96.4% for mechanical MVR, and 96.6% for porcine MVR (p less than 0.05, rheumatic patients with CVR versus both MVR groups). The 5-year freedom from all valve-related morbidity and mortality was significantly better for valve reconstruction compared with both types of valve replacement. Thus, the operative risk and late survival obtained after mitral valve reconstruction were at least equivalent to those obtained after MVR. In addition, patients receiving mitral valve reconstruction had less valve-related combined morbidity than patients receiving valve replacement, thus making mitral valve reconstruction preferable in some patients with mitral insufficiency.

Current concepts of mitral valve reconstruction for mitral insufficiency

In recent years, there has been a renewed interest in surgical reconstruction of the insufficient mitral valve because of reconfirmation of the limitations of existing prosthetic and bioprosthetic valves. A follow-up study, including late functional data, of 148 patients who underwent mitral valve reconstruction at our institution was combined with a review of the literature to assess the current status of mitral reconstruction. The results indicate that mitral reconstruction by Carpentier techniques is widely applicable, durable, and relatively free of complication. Freedom from late thromboembolic and anticoagulant complications is particularly notable. These factors could prove to justify earlier operative intervention in patients with mitral insufficiency before permanent myocardial damage evolves. As mitral valve reconstruction techniques become more familiar and widely used, mitral reconstruction may become the operative procedure of choice for mitral insufficiency, especially insufficiency due to degenerative disease.

Long-term results of mitral valve reconstruction with Carpentier techniques in 148 patients with mitral insufficiency

There have been few relatively complete follow-up studies of long-term mitral valve function after Carpentier-type surgical reconstruction. Between January 1980 and May 1986, 148 patients underwent Carpentier reconstruction for mitral valve disease (43% degenerative and 30% rheumatic). Operative mortality was 5.4% overall (1.2% for isolated mitral reconstruction), and follow-up (mean, 26 months) was completed for all survivors. Five-year survival from late cardiac death was 90.0%, as was 5-year freedom from postreconstruction mitral valve replacement. Postreconstruction mitral replacement was needed in eight patients, in only five for failure of repair. Follow-up echocardiographic studies on 83.2% (104 of 125) of eligible patients showed 92.3% were free of significant (3+ or 4+) mitral regurgitation. Freedom from mitral valve replacement or recurrent severe (4+) insufficiency was 84.4% at 5 years overall, but was lower for the rheumatic type of mitral disease than for the degenerative type (71.6% vs. 88.3%). At 5 years, 95.2% of patients were free from thromboembolism without the necessity for long-term warfarin (Coumadin) therapy. At follow-up, 95.3% of survivors had improved to New York Heart Association Class I or II. The functional durability of mitral reconstruction and consistently high level of freedom from late endocarditis and thromboembolic and anticoagulant complications support the value of the Carpentier method of mitral reconstruction for mitral insufficiency, especially insufficiency due to degenerative disease.