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Biomedical subjects

L Cohen

Publications and source records attributed to L Cohen.

At least 55 records · Page 3Linked to original sources
PubMed2000

Sentinel lymph node biopsy is accurate after neoadjuvant chemotherapy for breast cancer.

PURPOSE: Sentinel lymph node (SLN) biopsy has proved to be an accurate method for detecting nodal micrometastases in previously untreated patients with early-stage breast cancer. We investigated the accuracy of this technique for patients with more advanced breast cancer after neoadjuvant chemotherapy. PATIENTS AND METHODS: Patients with stage II or III breast cancer who had undergone doxorubicin-based neoadjuvant chemotherapy before breast surgery were eligible. Intraoperative lymphatic mapping was performed with peritumoral injections of blue dye alone or in combination with technetium-labeled sulfur colloid. All patients were offered axillary lymph node dissection. Negative sentinel and axillary nodes were subjected to additional processing with serial step sectioning and immunohistochemical staining with an anticytokeratin antibody to detect micrometastases. RESULTS: Fifty-one patients underwent SLN biopsy after neoadjuvant chemotherapy from 1994 to 1999. The SLN identification rate improved from 64.7% to 94.1%. Twenty-two (51.2%) of the 43 successfully mapped patients had positive SLNs, and in 10 of those 22 patients (45.5%), the SLN was the only positive node. Three patients had false-negative SLN biopsy; that is, the sentinel node was negative, but at least one nonsentinel node contained metastases. Additional processing revealed occult micrometastases in four patients (three in sentinel nodes and one in a nonsentinel node). CONCLUSION: SLN biopsy is accurate after neoadjuvant chemotherapy. The SLN identification improved with experience. False-negative findings occurred at a low rate throughout the series. This technique is a potential way to guide the axillary treatment of patients who are clinically node negative after neoadjuvant chemotherapy.

Adult↗
PubMed2000

NADP(+)-isocitrate dehydrogenase gene expression and isozyme activity during citrus fruit development.

The accumulation of citric acid and its decline toward fruit maturation is typical of citrus fruit. We studied NADP(+)-isocitrate dehydrogenase (NADP-IDH), an enzyme involved in citrate metabolism. A cDNA encoding the enzyme was cloned from lemon (Citrus limon) juice sac cells, and is the first-reported NADP-IDH from fruits. Sequence comparisons and phylogenetic analysis indicate that it most probably belongs to a monophyletic clade of plant cytosolic enzymes. The mRNA level in the juice sac cells was induced during lemon fruit growth, and increased by about 15-fold to a peak as the fruit neared maturation. Spectrophotometric assay of the NADP-IDH activity in the pulp during fruit development showed that in young fruit, most of the activity was associated with the mitochondrial preparation and that, as the fruit grew, the activity shifted to the soluble fraction. The two activities could also be distinguished by isozyme gel electrophoresis: while one isozyme was detected in the mitochondrial preparation of young fruit and declined later, the other was induced in the soluble fraction of older fruit and increased as the fruit grew. The increasing activity of NADP-IDH in the soluble fraction throughout fruit development correlated well with the increase in gene expression, which suggests that the soluble activity is regulated by the expression of the cytosolic NADP-IDH gene. The possible role of this form of the enzyme in citric acid catabolism in the pulp is discussed.

Journal Article↗
PubMed2000

T-cells specific for soluble recombinant oligodendrocyte-specific protein induce severe clinical experimental autoimmune encephalomyelitis in H-2(b) and H-2(s) mice.

To investigate the immunogenicity and encephalitogenicity of oligodendrocyte-specific protein (OSP), recombinant soluble mouse OSP (smOSP) was produced from a synthetic gene engineered to lack the sequences coding for the hydrophobic transmembrane domains of the native molecule. SmOSP was immunogenic and encephalitogenic for SJL/J, C3H.SW and C57BL/6J mice, but not PL/J or BALB/c mice. SmOSP-specific T-cells from SJL/J, C3H.SW and C57BL/6J mice induced severe chronic clinical experimental autoimmune encephalomyelitis upon transfer. These findings indicate that autoimmune T-cell responses to OSP should be investigated in the context of multiple sclerosis.

Amino Acid Sequence↗
PubMed2000

Functional MR evaluation of temporal and frontal language dominance compared with the Wada test.

OBJECTIVE: To evaluate the reliability of temporal and frontal functional MRI (fMRI) activation for the assessment of language dominance, as compared with the Wada test. PATIENTS AND METHODS: Ten patients with temporal lobe epilepsy were studied using blood oxygen level dependent fMRI and echoplanar imaging (1.5-T). Three tasks were used: semantic verbal fluency, covert sentence repetition, and story listening. Data were analyzed using pixel by pixel autocorrelation and cross-correlation. fMRI laterality indices were defined for several regions of interest as the ratio (L - R)/(L + R), L being the number of activated voxels in the left hemisphere and R in the right hemisphere. Wada laterality indices were defined as the difference in the percentages of errors in language tests between left and right carotid injections. RESULTS: Semantic verbal fluency: The asymmetry of frontal activation was correlated with Wada laterality indices. The strongest correlation was observed in the precentral/middle frontal gyrus/inferior frontal sulcus area. Story listening: The asymmetry of frontal, but not temporal, activation was correlated with Wada laterality indices. Covert sentence repetition: No correlation was observed. CONCLUSIONS: There was a good congruence between hemispheric dominance for language as assessed with the Wada test and fMRI laterality indices in the frontal but not in the temporal lobes. The story listening and the covert sentence repetition tasks increased the sensitivity of detection of posterior language sites that may be useful for brain lesion surgery.

Adolescent↗
PubMed2000

Transcatheter closure of apical ventricular muscular septal defect combined with arterial switch operation in a newborn infant.

This report describes a case of transposition of the great arteries and apical muscular ventricular septal defect in a newborn infant successfully treated by transcatheter closure of the septal defect with the Amplatzer duct occluder device followed by an arterial-switch operation within the first 2 weeks of life. Cathet. Cardiovasc. Intervent. 49:173-176, 2000.

Angiography↗
PubMed2000

Distinct cortical areas for names of numbers and body parts independent of language and input modality.

Some models of word comprehension postulate that the processing of words presented in different modalities and languages ultimately converges toward common cerebral systems associated with semantic-level processing and that the localization of these systems may vary with the category of semantic knowledge being accessed. We used functional magnetic resonance imaging to investigate this hypothesis with two categories of words, numerals, and body parts, for which the existence of distinct category-specific areas is debated in neuropsychology. Across two experiments, one with a blocked design and the other with an event-related design, a reproducible set of left-hemispheric parietal and prefrontal areas showed greater activation during the manipulation of topographical knowledge about body parts and a right-hemispheric parietal network during the manipulation of numerical quantities. These results complement the existing neuropsychological and brain-imaging literature by suggesting that within the extensive network of bilateral parietal regions active during both number and body-part processing, a subset shows category-specific responses independent of the language and modality of presentation.

Adult↗
PubMed2000

The effects of type of surgery and time on psychological adjustment in women after breast cancer treatment.

BACKGROUND: The aim of the present study was to examine whether type of surgery, age, and time since surgery influenced psychological distress and quality of life (QOL) in women treated for breast cancer. METHODS: We surveyed 183 women who had undergone surgery for breast cancer. Psychological distress was measured with the Mental Health Inventory and QOL was measured with the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire. RESULTS: After controlling for stage of disease, radiation treatment, and age, there was a statistically significant interaction between type of surgery and time since surgery for the Mental Health Inventory total score, and a marginal interaction between type of surgery and time since surgery for the Global health status/QOL score. Women who had breast conservation surgery experienced significantly greater levels of psychological distress and marginally worse QOL from 40 months after surgery onward than did women who received a mastectomy. CONCLUSIONS: The effects of different surgical treatments for breast cancer on psychological distress and QOL become apparent only after a period of several years. Women, therefore, need counseling on the potentially positive and negative psychological implications of different surgical treatments for breast cancer.

Adult↗
PubMed2000

Language and calculation within the parietal lobe: a combined cognitive, anatomical and fMRI study.

We report the case of a patient (ATH) who suffered from aphasia, deep dyslexia, and acalculia, following a lesion in her left perisylvian area. She showed a severe impairment in all tasks involving numbers in a verbal format, such as reading aloud, writing to dictation, or responding verbally to questions of numerical knowledge. In contrast, her ability to manipulate non-verbal representations of numbers, i.e., Arabic numerals and quantities, was comparatively well preserved, as evidenced for instance in number comparison or number bisection tasks. This dissociated impairment of verbal and non-verbal numerical abilities entailed a differential impairment of the four arithmetic operations. ATH performed much better with subtraction and addition, that can be solved on the basis of quantity manipulation, than with multiplication and division problems, that are commonly solved by retrieving stored verbal sequences. The brain lesion affected the classical language areas, but spared a subset of the left inferior parietal lobule that was active during calculation tasks, as demonstrated with functional MRI. Finally, the relative preservation of subtraction versus multiplication may be related to the fact that subtraction activated the intact right parietal lobe, while multiplication activated predominantly left-sided areas.

Aphasia↗
PubMed2000

DNA repair capacity in healthy medical students during and after exam stress.

There has been extensive research into the effects of stress on immune function but little on the effects of stress on DNA repair capacity (DRC), a process central to maintaining a normal cell cycle. Defective DRC is one of the factors responsible for carcinogenesis. In the present study we assessed DRC in healthy medical students during times of high and low stress. Sixteen medical students were evaluated during the third day of a 5-day exam period and then again 3 weeks later, after vacation. At both time points, participants underwent a brief physical examination, had venous blood drawn, and completed questionnaires to identify subjective stress levels. The DRC was assessed by the host-cell reaction assay, which measures nucleotide excision repair capacity. Participants reported significantly higher levels of subjective stress during the exam period than after vacation. DRC was also significantly higher during the exam period than after vacation, suggesting a positive association between subject stress levels and DRC. The results are discussed in relation to previous findings and implications for cancer research.

Adult↗
PubMed2000

Understanding dissociations in dyscalculia: a brain imaging study of the impact of number size on the cerebral networks for exact and approximate calculation.

Neuropsychological studies have revealed different subtypes of dyscalculia, including dissociations between exact calculation and approximation abilities, and an impact of number size on performance. To understand the origins of these effects, we measured cerebral activity with functional MRI at 3 Tesla and event-related potentials while healthy volunteers performed exact and approximate calculation tasks with small and large numbers. Bilateral intraparietal, precentral, dorsolateral and superior prefrontal regions showed greater activation during approximation, while the left inferior prefrontal cortex and the bilateral angular regions were more activated during exact calculation. Increasing number size during exact calculation led to increased activation in the same bilateral intraparietal regions as during approximation, as well the left inferior and superior frontal gyri. Event-related potentials gave access to the temporal dynamics of calculation processes, showing that effects of task and of number size could be found as early as 200-300 ms following problem presentation. Altogether, the results reveal two cerebral networks for number processing. Rote arithmetic operations with small numbers have a greater reliance on left-lateralized regions, presumably encoding numbers in verbal format. Approximation and exact calculation with large numbers, however, put heavier emphasis on the left and right parietal cortices, which may encode numbers in a non-verbal quantity format. Subtypes of dyscalculia can be explained by lesions disproportionately affecting only one of these networks.

Adult↗
PubMed2000

The visual word form area: spatial and temporal characterization of an initial stage of reading in normal subjects and posterior split-brain patients.

A standard model of word reading postulates that visual information is initially processed by occipitotemporal areas contralateral to the stimulated hemifield, from whence it is subsequently transferred to the visual word form (VWF) system, a left inferior temporal region specifically devoted to the processing of letter strings. For stimuli displayed in the left visual field, this transfer proceeds from the right to the left hemisphere through the posterior portion of the corpus callosum. In order to characterize the spatial and temporal organization of these processes, reading tasks with split-field presentation were performed by five control subjects and by two patients suffering from left hemialexia following posterior callosal lesions. The subjects' responses were studied using behavioural measures and functional brain imaging techniques, providing both high spatial resolution (functional MRI, fMRI) and high temporal resolution (high-density event-related potentials, ERPs). Early visual processing was revealed as activations contralateral to stimulation, located by fMRI in the inferior occipitotemporal region and presumably coincident with area V4. A negative wave occurring 150-160 ms post-stimulus, also strictly contralateral to stimulation, was recorded over posterior electrodes. In contrast with these hemifield-dependent effects, the VWF system was revealed as a strictly left-hemispheric activation which, in control subjects, was identical for stimuli presented in the left or in the right hemifield and was located in the middle portion of the left fusiform gyrus. The electrical signature of the VWF system consisted of a unilateral sharp negativity, recorded 180-200 ms post-stimulus over left inferior temporal electrodes. In callosal patients, due to the inability of visual information to pass across the posterior part of the corpus callosum, the VWF system was activated only by stimuli presented in the right visual field. Similarly, a significant influence of the word/non-word status on ERPs recorded over the left hemisphere was discernible for either hemifield in controls, while it affected only right-hemifield stimuli in callosal patients. These findings provide direct support for the main components of the classical model of reading and help specify their timing and cerebral substrates.

Adult↗
PubMed2000

Bed availability report: facilitating patient placement.

As hospital census rises, optimal bed utilization becomes increasingly important. The bed availability report was developed to provide relevant information about hospital-wide inpatient activity by arranging units into clinical groupings that reflect areas of high and low census. In addition to being used on a daily basis, the bed availability reports have been compiled to produce monthly graphs. These graphs help to identify trends and provide useful data when bed reallocations are being considered.

Adult↗
PubMed2000

[Study of hemispheric lateralization of language regions by functional MRI. Validation with the Wada test].

Language hemispheric dominance can be assessed by the Wada test before temporal lobectomy, in patients with refractory epilepsy of the mesial temporal lobe. Functional MR is a less invasive technique which recently demonstrated the ability to localize some language areas. The aim of this study was to determine if functional MR can be substituted to the Wada test in the determination of language dominance. Seven patients with a refractory epilepsy of the mesial temporal lobe were included. The MR protocol was carried out using a 1.5 T system including 12 axial gradient echo BOLD EPI images. A semantic fluency task, interspersed with rest periods, was used as activation paradigm. An activation of middle and inferior frontal region was found in all patients. It predominated in the left hemisphere in 6 cases and in the right hemisphere in 1 case. The hemispheric and frontal lobe lateralization of the functional MR activation was correlated with the hemispheric language dominance as assessed by the Wada test. In conclusion, functional MR is a promising technique in the determination of language dominance.

Adolescent↗