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Biomedical subjects

L Cohen

Publications and source records attributed to L Cohen.

At least 109 records · Page 6Linked to original sources
PubMed1998

Management of twin pregnancies consisting of a complete hydatidiform mole and normal fetus.

OBJECTIVE: To report the clinical features, management, and outcome of twin pregnancies consisting of a complete hydatidiform mole and a coexisting normal fetus. METHODS: Between 1966 and 1997, seven women with complete hydatidiform mole and coexisting normal fetus were treated at the John I. Brewer Trophoblastic Disease Center of Northwestern University Medical School. Clinical features, including presenting symptoms, gestational dates, hCG levels, and complications, as well as route of delivery or evacuation, pregnancy outcome, genetic analysis, and need for chemotherapy were assessed. RESULTS: Four women required uterine evacuation before 20 weeks' gestation because of vaginal bleeding or medical complications, one woman required an emergency hysterotomy because of hemorrhage at 24 weeks, and two women delivered normal, viable infants at 26 and 34 weeks. The pathologic diagnosis of complete hydatidiform mole was confirmed in each case and the chromosome complement was 46,XX in all molar gestations. Four of seven women required chemotherapy for treatment of nonmetastatic gestational trophoblastic tumors, including both women who delivered viable infants and two of the five women whose pregnancies were evacuated before 24 weeks' gestation. All four patients were treated with five to seven cycles of a 5-day methotrexate regimen and achieved complete remission. CONCLUSION: Patients with a twin pregnancy consisting of a complete mole and a normal fetus are at increased risk for hemorrhage and medical complications, as well as the development of persistent gestational trophoblastic tumor.

Adult↗
PubMed1998

Abstract representations of numbers in the animal and human brain.

There is evidence to suggest that animals, young infants and adult humans possess a biologically determined, domain-specific representation of number and of elementary arithmetic operations. Behavioral studies in infants and animals reveal number perception, discrimination and elementary calculation abilities in non-verbal organisms. Lesion and brain-imaging studies in humans indicate that a specific neural substrate, located in the left and right intraparietal area, is associated with knowledge of numbers and their relations ('number sense'). The number domain is a prime example where strong evidence points to an evolutionary endowment of abstract domain-specific knowledge in the brain because there are parallels between number processing in animals and humans.The numerical distance effect, which refers to the finding that the ability to discriminate between two numbers improves as the numerical distance between them increases, has been demonstrated in humans and animals, as has the number size effect,which refers to the finding that for equal numerical distance,discrimination of two numbers worsens as their numerical size increases.

Animals↗
PubMed1998

Pre-ejectional left ventricular wall motions studied on conscious dogs using Doppler myocardial imaging: relationships with indices of left ventricular function.

Duration of the pre-ejection period is a sensitive index of myocardial function. Our purpose was to document normal pre-ejectional left ventricular (LV) wall motions at rest and under dobutamine using Doppler myocardial imaging (DMI), and to correlate posterior wall velocities with indices of LV systolic function. M-mode recordings of both walls were imaged on eight conscious dogs chronically instrumented. Subendocardial pre-ejectional velocities were digitized and measured every 3.8 ms. DMI analysis consisted of sign recognition, velocity measurement, duration and timing from the Q wave of the electrocardiogram. Isovolumic contraction time (Ict) was represented by the time interval from onset to peak of the first derivative of LV pressure. Conventional Doppler labelling of velocity signs, positive toward and negative away from the transducer, was applied to the direction of encoded wall motions. For physiological understanding, wall motions of both walls were also labelled inward and outward with respect to the left ventricular cavity center. In each wall, PEP was shown as several colored strips, each strip representing the period of time that the wall was moving in one direction. Changes in velocity sign corresponding to changes in direction of motion were opposed in each wall (p < 0.001), featuring successive inward and outward wall motions. There was a markedly sustained inward motion during Ict. Its velocity amplitude increased with dobutamine. There was a positive correlation between velocities of the inward motion contemporaneous of Ict and ejection fraction (r = 0.72, p < 0.003). Values of Ict respectively drawn from DMI and from hemodynamics were also significantly correlated (r = 0.85, p < 0.007). Thus, the inward motion evidenced by DMI during Ict appears promising to assess myocardial function and effect of drugs.

Animals↗
PubMed1998

Competition between past and present. Assessment and interpretation of verbal perseverations.

Perseveration consists of the inappropriate repetition of a preceding behaviour when a new adapted response is expected. We have developed statistical tools that make it possible to reveal such perseverations, assess their significance and study their finer characteristics, such as their temporal course and impaired processing level. This approach is illustrated and evaluated through analyses of naming errors produced by three patients with impairments affecting different stages of the processing chain leading from visual perception to speech production. These examples of perseverations include the intrusion not only of whole words (patient R.A.V.) but also of isolated phonemes (patient D.U.M.) or of visual features (patient Y.M.) from previous trials. In all cases, the probability that an error is a perseveration from a previous trial is an exponentially decreasing function of the lag between the two trials considered. This suggests that perseverations reflect a decaying internal variable, such as an internal level of activation of previous utterances. Based on these empirical results, we put forward a tentative mechanism for the generation of perseverations: whenever a given processing level is deprived of its normal input, persistent activity inherited from previous trials is no longer overcome by current input, and is revealed in the form of perseverations.

Adult↗
PubMed1998

Psychological functioning in primary progressive versus secondary progressive multiple sclerosis.

Psychological functioning in two types of multiple sclerosis (MS) patients is assessed: primary progressive (PP) and secondary progressive (SP) patients. On the basis of differences in clinical course and underlying pathology we hypothesized that primary progressive patients and secondary progressive patients might have different psychological functioning. Seventy patients treated in an MS centre were examined cross-sectionally. Forty had an SP course of MS and 30 a PP course. The 33 male and 37 female patients had a mean age of 48.4 years (SD 11.2) and mean age of onset of MS of 30.7 years (SD 11.1). Patients completed questionnaires measuring among others the following aspects of psychological functioning: depression (BDI, SCL-90), anxiety (STAI, SCL-90), agoraphobia (SCL-90), somatic complaints (SCL-90), hostility (SCL-90) and attitude towards handicap (GHAS). Patients with a PP-MS scored significantly better on 5 out of 14 subscales than patients with SP-MS (p < .05). On the basis of our operationalizations of psychological functioning, the findings support the conclusion that on average 18 years after diagnosis of MS, amongst patients attending an MS unit, primary progressive patients were found to have better psychological functioning.

Adaptation, Psychological↗
PubMed1998

Successful behavioral interventions to prevent cancer: the example of skin cancer.

Important behavioral sources of risk for cancer have been identified and programs to reduce this risk have been initiated. The most heavily studied behavioral risk is tobacco use, but considerable attention has also gone to prevention of skin cancer by modifying sun exposure. Research has shown a strong link between sun exposure and skin cancer, and opportunities to prevent this cancer by changing behavior should be effective. Unlike unmodifiable sources of risk, sun exposure should be modifiable through behavioral intervention. This review considers research in this expanding area, concentrating on predictors of sun protective behaviors, modification of sun exposure, and surveillance for early signs of cancer. The elements of behavior change programs that contribute to successful intervention as well as barriers to successful behavior change and future directions for this effort are considered.

Health Behavior↗
PubMed1998

Predictors of quality of life and adjustment after lung transplantation.

STUDY OBJECTIVE: Few studies have examined predictors of quality of life and adjustment after lung transplantation. This study determined whether pretransplant psychological measures predicted physical health, quality of life, and overall adjustment posttransplant. Cross-sectional analyses also examined differences in adjustment and quality of life for lung transplant candidates and recipients. DESIGN AND PARTICIPANTS: Seventeen transplant candidates and 60 transplant recipients completed questionnaires measuring adjustment and quality of life. In addition, we examined archival data on 107 transplant candidates who had received pretransplant psychological assessments, and posttransplant physical health status data were collected on these patients. Of the 107 patients who provided a pretransplant psychological assessment, 32 completed the questionnaires measuring posttransplant adjustment and quality of life. SETTING: University medical center transplant service. RESULTS: Cross-sectional analyses indicated significantly better adjustment and quality of life posttransplant. Pretransplant psychological variables were not associated with measures of posttransplant physical health. Hierarchical multiple regression analyses found that pretransplant anxiety and psychopathology predicted posttransplant adjustment (beta's ranging from 0.32 to 0.68) and greater pretransplant anxiety also predicted worse posttransplant quality of life (beta's ranging from 0.29 to 0.62). Subjective sleep disturbances were associated with poorer adjustment and quality of life (beta's ranging from 0.36 to 0.75), and were found to mediate the relationship between presurgical anxiety and posttransplant adjustment and quality of life. CONCLUSIONS: This study found that psychological status pretransplant predicted adjustment and quality of life posttransplant. Moreover, increased anxiety levels pretransplant predicted subsequent subjective sleep disturbances, which were, in turn, associated with poorer adjustment and quality of life. The benefits of pretransplant stress management interventions are discussed.

Adaptation, Psychological↗
PubMed1998

Reliability of two measures of health-related quality of life in patients with multiple sclerosis.

Multiple sclerosis is a chronic neurological disease which can cause a variety of symptoms (motor and sensory impairment, visual problems, bladder and bowel problems, sexual dysfunction, and decline in cognitive function). Both the Medical Outcome Study Short Form-36, a generic questionnaire regarding health-related quality of life, and the Disability and Impact Profile, a similar questionnaire developed for people with chronic diseases, are used regularly to assess patients with multiple sclerosis. Over a 6-mo. interval 187 patients with multiple sclerosis completed these questionnaires twice. Internal consistency of both questionnaires at Times 1 and 2 was .60 or above for all eight scales of the Medical Outcome Study Short Form-36 and five scales of the Disability and Impact Profile. Estimates of test-retest reliability for three scales of the Medical Outcome Study Short Form-36 were below .60, but for all scales of the Disability and Impact Profile were .60 or higher. The two questionnaires appeared to be reliable for our sample of patients with multiple sclerosis.

Adult↗
PubMed1998

[Doppler tissue imaging of pre-ejection left ventricular wall dynamics in normal subjects].

Pre-ejectional left ventricular wall motion has been demonstrated clinically by angiography. Intramyocardial wall velocities generated by cardiac contraction may be measured by Doppler tissue imaging. The aim of this study was to detect pre-ejectional wall motion and to analyse its sequencer. A long axis M Mode with simultaneous septal and posterior wall imaging was performed in 11 normal subjects (age 37 +/- 15 years) with velocity analysis between the electrocardiographic Q wave and the onset of ejection by digitised analysis between the electrocardiographic Q wave and the onset of ejection by digitised images with automatic velocity extraction (3.8 ms) along a horizontal subendocardial line. The total duration of the pre-ejectional periods in conventional and Doppler tissue imaging are compared. Oscillatory velocimetric appearances with alternate colours of adjacent bands in each wall and a mirror image between walls was observed. The mean and peak velocities of the first four bands were significantly different between the walls (p < 0.001) as were the absolute values between bands 2 (p < 0.02) and 3 (p < 0.006). The duration of band 2, related to motion mainly towards the center of the ventricular chamber exceeded that of the adjacent bands (septum p < 0.02, posterior wall p < 0.001). The correlation coefficient for total duration of the pre-ejectional period between Doppler tissue imaging and conventional Doppler was 0.83, p < 0.05 for the interventricular septum and 0.76, p < 0.04 for the posterior was. The authors conclude that regional pre-ejectional wall motion can be recorded. During isovolumic contraction, there is motion predominantly towards the center of the left ventricular chamber of the two walls, confirming previous angiographic findings. Its timing suggests that wall motion proceeds the increase in ventricular pressure.

Adult↗
PubMed1998

Evaluation of mental health and depression during pregnancy: position paper.

Women in their reproductive years constitute the population at greatest risk for major depression. Consequently, many women will experience depression during the course of conception and pregnancy. Rates of major depression among pregnant women appear to be equivalent to those of nongravid women. The evaluation of depression during pregnancy, however, is confounded by the somatic experiences normative at this time. A small number of rating instruments have been validated among pregnant women and should take precedence in research studies until new instruments are developed specifically for this group. Other issues that require further exploration are risk factors for depression during pregnancy and the course of depression during pregnancy.

Depression↗
PubMed1997

Anatomical variability in the cortical representation of first and second language.

Functional magnetic resonance imaging was used to assess inter-subject variability in the cortical representation of language comprehension processes. Moderately fluent French-English bilinguals were scanned while they listened to stories in their first language (L1 = French) or in a second language (L2 = English) acquired at school after the age of seven. In all subjects, listening to L1 always activated a similar set of areas in the left temporal lobe, clustered along the left superior temporal sulcus. Listening to L2, however, activated a highly variable network of left and right temporal and frontal areas, sometimes restricted only to right-hemispheric regions. These results support the hypothesis that first language acquisition relies on a dedicated left-hemispheric cerebral network, while late second language acquisition is not necessarily associated with a reproducible biological substrate. The postulated contribution of the right hemisphere to L2 comprehension is found to hold only on average, individual subjects varying from complete right lateralization to standard left lateralization for L2.

Adult↗
PubMed1997

Specific activation of the cysteine protease CPP32 during the negative selection of T cells in the thymus.

Cysteine proteases of the CED-3 and ICE family have been recently proposed as the ultimate executioners in several mammalian cell death pathways. Among them, the cysteine protease CPP32 has been shown to participate in programmed cell death (PCD), or apoptosis, affecting lymphoid cells in vitro. In the thymus, negative selection is a mechanism through which developing thymocytes expressing a TcR with high affinity for self peptide-MHC complexes are eliminated by PCD. In order to investigate the role of CPP32 in thymic apoptosis, isolated thymocytes were submitted to cell surface CD3 crosslinking by immobilized anti-CD3 mAb or to dexamethasone treatment. Although apoptosis occurred in the absence or after crosslinking with anti-CD3 mAb, specific activation of CPP32, as assessed by the extent of proteolytic cleavage of the p32 zymogen, was only detected in thymocytes cultured in the presence of the immobilized antibody or dexamethasone. This activation was a very early event during apoptosis as it occurred before the exposure of phosphatidyl serine to the upper side of the cell membrane. This was observed both in anti-CD3- and dexamethasone-induced apoptosis. Moreover, using mice transgenic for pigeon cytochrome C (PCC)-specific TcR, we were able to show that, after injection of PCC, the activation of CPP32 and cleavage of its substrate occurred in thymocytes obtained from mice expressing a permissive MHC haplotype for PCC presentation (H-2k). Moreover, PCC induced apoptosis was blocked by the caspase inhibitor zVAD. While spontaneous apoptosis was not accompanied by detectable levels of CPP32 processing, it was characterized by the proteolysis of poly(ADP-ribose) polymerase (PARP) and was blocked by the cysteine protease inhibitor, zVAD-CH2F. Taken together, these results support the concept that CPP32 is among the earliest effectors of the pathway leading to negative selection of autoreactive thymocytes. Our results also suggest the involvement of a distinct CPP32-like cysteine protease in spontaneous apoptosis of thymocytes.

Animals↗
PubMed1997

Preejectional left ventricular wall motion in normal subjects using Doppler tissue imaging and correlation with ejection fraction.

Relations have been demonstrated between the preejection period (PEP) and indexes of left ventricular (LV) systolic function. Doppler tissue M-mode imaging has the capability to measure wall velocities and to display as colored strips within the walls velocity reversals representing changes in direction of wall motion. To document LV preejectional wall motions, this procedure was performed on 16 normal subjects with a twofold purpose: to measure septal and posterior preejectional intramyocardial velocities and durations and to correlate preejectional parameters with LV ejection fraction (LVEF). Parasternal M-mode images of simultaneously recorded walls were digitized. Subendocardial wall velocities were measured every 3.8 ms from the Q wave to the onset of ejection. Total duration measured from Doppler tissue and flow traces was compared in 10 subjects. PEP total duration did not differ between both walls or techniques. Several adjacent velocity reversals with mirror signs in opposite walls were substantiated by 2 to 5 colored strips. Colored strips corresponding to the same sign in each wall had a progressively damped velocity amplitude (septum 19 +/- 8, -21 +/- 10, 15 +/- 7, -8 +/- 5, 4 +/- 2 mm/s; posterior wall -13 +/- 16, 11 +/- 7, -8 +/- 5, 9 +/- 6, -2 mm/s). Peak velocity values of opposite signs significantly differed between both walls (p <0.0001). Absolute values differed only for colored strips 2 and 3 (p <0.009). Strip 2 featured a simultaneous early inward motion of both walls toward the LV cavity with significantly prolonged duration (p <0.0001). The only positive correlation with LVEF was found for peak velocities of strip 2 in the posterior wall (r = 0.71, p <0.006). Thus, the posterior wall and its inward motion velocities have potential for future clinical implications.

Adolescent↗
PubMed1997

FPs have vital role in ensuring success of breast cancer screening programs.

SCREENING IS THE ONLY PROVEN STRATEGY for reducing breast cancer mortality in women older than 50. Over the last 9 years, 8 provinces and 2 (territories have established independent dedicated mammography programs. A recent workshop on screening programs was told that family physicians play a crucial role in the ultimate success of these programs because of their referral role.

Breast Neoplasms↗
PubMed1997

The human A33 antigen is a transmembrane glycoprotein and a novel member of the immunoglobulin superfamily.

The mAb A33 detects a membrane antigen that is expressed in normal human colonic and small bowel epithelium and > 95% of human colon cancers. It is absent from most other human tissues and tumor types. The murine A33 mAb has been shown to target colon cancer in clinical trials, and the therapeutic potential of a humanized antibody is currently being evaluated. Using detergent extracts of the human colon carcinoma cell lines LIM1215 and SW1222, in which the antigen is highly expressed, the molecule was purified, yielding a 43-kDa protein. The N-terminal sequence was determined and further internal peptide sequence obtained following enzymatic cleavage. Degenerate primers were used in PCRs to produce a probe to screen a LIM1215 cDNA library, yielding clones that enabled us to deduce the complete amino acid sequence of the A33 antigen and express the protein. The available data bases have been searched and reveal no overall sequence similarities with known proteins. Based on a hydrophilicity plot, the A33 protein has three distinct structural domains: an extracellular region of 213 amino acids (which, by sequence alignment of conserved residues, contains two putative immunoglobulin-like domains), a single hydrophobic transmembrane domain, and a highly polar intracellular tail containing four consecutive cysteine residues. These data indicate that the A33 antigen is a novel cell surface receptor or cell adhesion molecule in the immunoglobulin superfamily.

Amino Acid Sequence↗