A graph theoretic approach to neurodegeneration: five data-driven neuropsychological subtypes in mild cognitive impairment.

Mild cognitive Impairment (MCI) is notoriously heterogenous in terms of clinical presentation, neuroimaging correlates, and subsequent progression. Predicting who will progress to dementia, which type of dementia, and over what timeframe is challenging. Previous work has attempted to identify MCI subtypes using neuropsychological measures in an effort to address this challenge; however, there is no consensus on approach, which may account for some of the variability. Using a hierarchical community detection approach, we examined cognitive subtypes within an MCI sample (from the Alzheimer's Disease Neuroimaging Initiative [ADNI] study). We then examined whether these subtypes were related to biomarkers (e.g., cortical volumes, fluorodeoxyglucose (FDG)-positron emission tomography (PET) hypometabolism) or clinical progression. We identified five communities (i.e., cognitive subtypes) within the MCI sample: 1) predominantly memory impairment, 2) predominantly language impairment, 3) cognitively normal, 4) multidomain, with notable executive dysfunction, 5) multidomain, with notable processing speed impairment. Community membership was significantly associated with 1) cortical volume in the hippocampus, entorhinal cortex, and fusiform cortex; 2) FDG PET hypometabolism in the posterior cingulate, angular gyrus, and inferior/middle temporal gyrus; and 3) conversion to dementia at follow up. Overall, community detection as an approach appears a viable method for identifying unique cognitive subtypes in a neurodegenerative sample that were linked to several meaningful biomarkers and modestly with progression at one year follow up.

Relationship between cognitive reserve, brain volume, and neuropsychological performance in amnestic and nonamnestic MCI.

Cognitive Reserve (CR) is a theoretical construct that influences the onset and course of cognitive and structural changes that occur with aging and mild cognitive impairment (MCI). There is a paucity of research that examines the relationship of CR and brain volumes in amnestic (aMCI) and nonamnestic (naMCI) separately. This study is a retrospective chart review of MCI patients who underwent neuropsychological evaluation and brain MRI with NeuroReader™ (NR). NR is an FDA-cleared software that standardizes MRI volumes to a control sample. Classifications of aMCI and naMCI were based on Petersen criteria. CR was measured as education, occupation, and word reading. Data analysis included bivariate correlations between CR, neuropsychological test scores, and NR-brain volumes by MCI subtype. The Benjamini-Hochberg method corrected for multiple comparisons. The sample included 91 participants with aMCI and 41 with naMCI. Within naMCI, positive correlations were observed between CR and whole brain volume, total gray matter, bifrontal, left parietal, left occipital, and bilateral cerebellum. Within aMCI, no significant correlations were observed between CR and brain volumes. Positive correlations with CR were observed in language, attention, and visual learning in both aMCI and naMCI groups. The current study adds to the minimal literature on CR and naMCI. Results revealed that CR is associated with volumetrics in naMCI only, though cognitive findings were similar in both MCI groups. Possible explanations include heterogeneous disease pathologies, disease stage, or a differential influence of CR on volumetrics in MCI. Additional longitudinal and biomarker studies will better elucidate this relationship.

Semantic memory activation in amnestic mild cognitive impairment.

Cognitively intact older individuals at risk for developing Alzheimer's disease frequently show increased functional magnetic resonance imaging (fMRI) brain activation presumably associated with compensatory recruitment, whereas mild cognitive impairment (MCI) patients tend not to show increased activation presumably due to reduced neural reserve. Previous studies, however, have typically used episodic memory activation tasks, placing MCI participants at a performance disadvantage relative to healthy elders. In this event-related fMRI study, we employed a low effort, high accuracy semantic memory task to determine if increased activation of memory circuits is preserved in amnestic MCI when task performance is controlled. Fifty-seven participants, aged 65-85 years, comprised three groups (n = 19 each): amnestic MCI patients; cognitively intact older participants at risk for developing Alzheimer's disease based on having at least one ApoE epsilon4 allele and a positive family history of Alzheimer's disease (At Risk); and cognitively intact participants without Alzheimer's disease risk factors (Control). fMRI was conducted on a 3T MR scanner while participants performed a famous name discrimination task. Participants also underwent neuropsychological testing outside the scanner; whole brain and hippocampal atrophy were assessed from anatomical MRI scans. The three groups did not differ on demographic variables or on fame discrimination performance (>87% correct for all groups). As expected, the amnestic MCI participants demonstrated reduced episodic memory performance. Spatial extent of activation (Fame--Unfamiliar subtraction) differentiated the three groups (Control = 0 ml, At Risk = 9.7 ml, MCI = 34.7 ml). The MCI and At Risk groups showed significantly greater per cent signal change than Control participants in 8 of 14 functionally defined regions, including the medial temporal lobe, temporoparietal junction, and posterior cingulate/precuneus. MCI participants also showed greater activation than Controls in two frontal regions. At Risk, but not MCI, participants showed increased activity in the left hippocampal complex; MCI participants, however, evidenced increased activity in this region when hippocampal atrophy was controlled. When performance is equated, MCI patients demonstrate functional compensation in brain regions subserving semantic memory systems that generally equals or exceeds that observed in cognitively intact individuals at risk for Alzheimer's disease. This hyperactivation profile in MCI is even observed in the left hippocampal complex, but only when the extent of hippocampal atrophy is taken into consideration.

Kidney transplant lymphocele: treatment with laparoscopic drainage and omental packing.

Lymph collections are not uncommon after kidney transplantation. These have been treated classically by laparotomy with internal drainage and omental packing. A technique is described that allows this to be done via the laparoscope. The patient was discharged on postoperative day 1 and has had no recurrence of the lymphocele.

Initial evaluation and management of upper airway injuries in trauma patients.

STUDY OBJECTIVE: To examine and compare the mechanism of injury, diagnostic findings, initial methods of airway management, and outcome of patients who had upper airway injuries. DESIGN: A retrospective review of hospital records. SETTING: A large metropolitan, university-affiliated trauma center. PATIENTS: Forty-six cases of upper airway injuries admitted between 1984 and 1988. INTERVENTIONS: Diagnostic methods included clinical examination, cervical and thoracic radiographs, bronchoscopy and computerized tomographic (CT) scan. Therapeutic interventions ranged from conservative management with or without endotracheal intubation to operative reconstruction. MEASUREMENTS AND MAIN RESULTS: Mechanism of injury was knife stab wound in 9 cases, gunshot wound in 17 cases, and blunt trauma in 20 cases. Location was the larynx in 13 cases, trachea in 24 cases, cricoid cartilage in 5 cases, and multiple sites in 4 cases. Diagnostic findings varied considerably according to the mechanism of injury, but radiographic evidence of soft tissue air and wounds opening into the airway were common findings. CT scan and bronchoscopy also were useful diagnostic tools. Overall mortality was 24%, which did not vary according to patient age or mechanism of injury. The airway injury itself was a primary or contributory cause of death in four cases, two of which were tracheal injuries and two injuries at the cricotracheal junction. CONCLUSIONS: In any patient with possible upper airway injury, plain radiographs of the chest and neck should be obtained to aid in the diagnosis. Elective intubation should be attempted only with a surgical team present and prepared for emergency tracheotomy. Fiber-optic bronchoscopy could be a valuable aid for both intubation and evaluation in such cases.

Effect of intraperitoneally injected cadmium on renal and hepatic gluconeogenic enzymes in rats.

Male Sprague-Dawley rats were injected intraperitoneally with 0, 0.25, 0.75 and 1.25 mg/kg/day for 14 days. At the end of 7 and 14 days treatment period, body weight gain, serum protein, serum glucose, serum glutamic oxaloacetic transaminase (SGOT) and serum glutamic pyruvic transaminase (SGPT) were measured. Glucose-6-phosphatase (G6-Pase), fructose-1, 6-di-phosphatase (FD-Pase), phosphoenol pyruvate carboxykinase (PEPCK) and pyruvate carboxylase (PC) in kidney and liver were determined. A significant decrease in body weight gain in rats treated with 1.25 mg cadmium for 7 and 14 days was observed. Serum glucose, serum protein, SGOT and SGPT were increased in cadmium treated rats. A significant increase in all four key gluconeogenic enzymes were observed in both kidney and liver tissues of rats treated with cadmium. The results of this study suggest that cadmium induces gluconeogenesis which is dose and time dependent.