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Biomedical subjects

F Benson

Publications and source records attributed to F Benson.

14 recordsLinked to original sources
PubMed1996

Expression of the human RAD51 gene during the cell cycle in primary human peripheral blood lymphocytes.

The S. cerevisiae RAD51 gene product exerts important functions in meiotic and mitotic recombination, as well as in the repair of DNA double-strand breaks. We have studied the expression of the human RAD51 (HsRAD51) gene in primary human peripheral blood lymphocytes (PBLs). The HsRAD51 mRNA level increased three fold in mitogen stimulated PBLs, with a peak in the late S phase. A five fold increase of HsRAD51 protein levels was observed in late G2. Specific inhibition of DNA synthesis with aphidicolin did not block the induction of the HsRAD51 protein, indicating that HsRAD51 expression is independent of DNA replication. In contrast, after inhibition of RNA synthesis with actinomycin D and protein synthesis with cycloheximide, the HsRAD51 protein level decreased rapidly. Taken together, these results indicate that the HsRAD51 gene is transcriptionally regulated in human PBLs, and exerts its function during the late S and G2 phases of the cell cycle.

Actins↗
PubMed1994

Depression in complex partial seizures. Electroencephalography and cerebral metabolic correlates.

OBJECTIVE: We sought to determine whether the frequency of depressive disorders among patients with complex partial seizures is associated with the laterality of ictal onset or the laterality of interictal cerebral hypometabolism. DESIGN: Fifty-three patients with medically intractable complex partial seizures were assessed for history of interictal depressive disorders meeting strict Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition (DSM-III-R), criteria with use of a modification of the Structured Clinical Interview for DSM-III-R. All subjects underwent video-electroencephalographic telemetry and fludeoxyglucose F18 positron emission tomographic scanning. The main outcome measure was the frequency of a history of major depressive episodes (MDEs) in subjects with left-sided vs right-sided ictal onset and in subjects with left-sided vs right-sided temporal lobe hypometabolism. RESULTS: Thirty-three subjects (62%) had a history of interictal depressive disorders, 16 (30%) of whom met criteria for one or more MDEs. More of those with left-sided ictal onset had a history of depression. Thirty-six subjects had definite unilateral temporal lobe hypometabolism demonstrated by positron emission tomographic scanning. More of those with left temporal lobe hypometabolism had a history of MDEs, and the combination of left temporal lobe hypometabolism and high-degree hypometabolism was strongly associated with a history of MDEs. Furthermore, among those with right temporal lobe hypometabolism, more of those with high-degree hypometabolism had a history of MDEs. CONCLUSION: Laterality of ictal onset and degree of interictal temporal lobe hypometabolism may be interdependent factors that contribute to the risk of depressive disorder in patients with complex partial seizures.

Adult↗
PubMed1993

Callosal disconnection in multiple sclerosis.

A patient with MS demonstrated a striking callosal disconnection syndrome. MRI revealed callosal atrophy and extensive bilateral white matter changes. Of 15 comparison patients with clinically definite MS, only one had minimal callosal disconnection. Callosal disconnection in MS may be due to pathology of the corpus callosum as well as extensive white matter disease.

Adult↗
PubMed1991

Evidence of abortive recombination in ruv mutants of Escherichia coli K12.

Genetic recombination in Escherichia coli was investigated by measuring the effect of mutations in ruv and rec genes on F-prime transfer and mobilization of nonconjugative plasmids. Mutation of ruv was found to reduce the recovery of F-prime transconjugants in crosses with recB recC sbcA strains by about 30-fold and with recB recC sbcB sbcC strains by more than 300-fold. Conjugative plasmids lacking any significant homology with the chromosome were transferred normally to these ruv mutants. Mobilization of the plasmid cloning vectors pHSG415, pBR322, pACYC184 and pUC18 were reduced by 20- to 100-fold in crosses with ruv rec+ sbc+ strains, depending on the plasmid used. Recombinant plasmids carrying ruv+ were transferred efficiently. With both F-prime transfer and F-prime cointegrate mobilization, the effect of ruv was suppressed by inactivating recA. It is proposed that the failure to recover transconjugants in ruv recA+ strains is due to abortive recombination and that the ruv genes define activities which function late in recombination to help convert recombination intermediates into viable products.

Conjugation, Genetic↗
PubMed1985

Aphasia in dementia of the Alzheimer type.

Speech and language assessment in 30 patients with dementia of the Alzheimer type and in 70 normal controls revealed that all Alzheimer patients were aphasic. Throughout most of the course, the language disorder resembled transcortical sensory aphasia, and increasing language impairment correlated with increasing severity of dementia. Aphasia was present regardless of age of onset or family history of dementia. Aphasia is an important diagnostic criterion of dementia of the Alzheimer type.

Adult↗
PubMed1983

CNS toxoplasmosis in acquired immunodeficiency syndrome.

Several distinct patterns of neurological involvement occur in epidemic acquired immune deficiency syndrome (AIDS). Two patients with this disorder had Toxoplasma gondii encephalitis, one suspected and one proved. Computed tomographic (CT) scanning showed focal lesions in both patients. Spinal fluids were remarkable for elevated protein, hypoglycorrhachia, and absence of pleocytosis. In patients with AIDS, focal CT scan findings and serum indication of past T gondii infection should prompt strong consideration of the diagnosis of CNS toxoplasmosis. The absence of specific IgM antibody or rise in IgG antibody titer to T gondii does not exclude this condition in the immune compromised host. In the patient with AIDS, CNS lesions mimicking brain abscess warrant biopsy or empiric therapy for T gondii. Early recognition and initiation of a prolonged or indefinite course of pyrimethamine plus sulfonamide therapy could reduce the mortality associated with this infection in AIDS. Computed tomographic scans, repeated frequently, appear, at present, to be the best guide to monitor the status of CNS involvement.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Is "subcortical dementia" a recognizable clinical entity?

The concept of "subcortical dementia" is controversial, lacking clinical validation and having only a questionable pathological basis. Over 100 patients with Alzheimer's, Parkinson's or Huntington's disease, subdivided into three functional disability stages, were given a brief quantitative neuropsychological assessment. Patients with Huntington's or Parkinson's disease were less intellectually impaired than those with Alzheimer's disease at each functional stage. Criteria for dementia were present in all of the Alzheimer's patients but in only half of the Huntington's and Parkinson's disease groups. Patients with similar overall intellectual function scores had no distinct pattern of neuropsychological test performance. Depression, absent in patients with Alzheimer's disease, was present in half the patients with Huntington's and Parkinson's disease and was correlated with intellectual decline. The concept of subcortical dementia is misleading. The pattern of neuropsychological impairment is not distinct, and the neuropathological basis of dementia in these diseases may result from a combination of cortical and subcortical degeneration.

Adult↗
PubMed1981

Blood tests showing nonpaternity-conclusive or rebuttable evidence? The Chaplin case revisited.

A defendant accused of being the father of an illegitimate child denies responsibility. Blood samples from the child, mother, and alleged father are studied and the results reveal that the alleged father is excluded. What weight, if any, should the court (if a trial is held) or the jury give to the evidence of nonpaternity? Should the evidence be treated as conclusive proof of nonpaternity or should other evidence be admitted in the trial to overcome the nonpaternity evidence? A medical expert might conclude that a controversy exists because of the court's questioned trustworthiness of the paternity blood testing, while a legal expert might conclude that the controversy arises because of burdens of proof. Both conclusions are valid. The Berry v. Chaplin case held in California in 1946 illustrates this circumstance. In refreshing our memories on this case, we can review the problem in light of today's knowledge.

Blood Group Antigens↗
PubMed1979

Quantification of the human orienting response to another human: lesioned and psychiatric patients compared to normals.

A method for eliciting, controlling, and quantifying the alpha suppression response to a human "real-person" stimulus is presented. Improved control is achieved by a feedback from the EEG response to the presentation of the stimulus. Quantification is comprehensive in that initial response and subsequent habituation for both latency and duration are described. Patients who had suffered a focal lesion but who had recovered sufficiently to travel from one hospital to another by taxi were compared with hospitalized psychiatric patients and normal volunteers. Lesioned patients showed less EEG response to visual stimuli than did the other groups, even with an evocative, real-person stimulus. The differences among the three groups were most evident at the onset of stimulation and less so after habituation had occurred.

Adult↗
PubMed1977

Unilateral asterixis associated with a mesencephalic syndrome.

Unilateral asterixis due to a focal brain lesion is a rare occurrence. Acute asterixis restricted to the left upper extremity appeared in a patient in association with signs of acute midbrain dysfunction, without changes in mental status or in the EEG, and in the absence of metabolic or toxic disturbance. Electromyography disclosed features typical of asterixis due to metabolic causes.

Brain Diseases↗
PubMed1977

Diagnosis: schizophrenia versus posterior aphasia.

Schizophrenia and posterior aphasia are easily cross-diagnosed, primarily because of similarities in verbal output, i.e., vagueness, looseness of association, and apparent confusion. Tape-recorded interviews with 8 posterior aphasics and 10 "loose" schizophrenics were transcribed and analyzed to provide guidelines for the clinician to differentiate the two conditions by monitoring verbal expression. Six major differentiating characteristics were identified. The authors present hypotheses that emphasize differing neuroanatomical loci and neuropsychological mechanisms to explain the differences in verbal output in schizophrenia and posterior aphasia.

Aphasia↗
PubMed1976

Detection of EEG abnormalities with feedback stimulation.

A feedback method for testing the reactivity of the occipital-parietal EEG in selected brain-lesioned patients revealed abnormalities of (a) insufficient reactivity, (b) bilateral differences in reactivity, and (3) asynchrony. These abnormalities were more evident during feedback stimulation than in the baseline conditions. The utility of feedback method for detecting EEG abnormalities rests on the increased stability or decreased "noisy" variation in the EEG during feedback. The EEG becomes more predictable even to the "on-line" human observer. This makes it easier to detect aberrations or deviations from normal effects. Some effects can only be seen with feedback such as the bilateral differences which occur when the left side controls the feedback compared to when the right side controls it. The results show that feedback EEG is a useful tool in clinical research and indicate that a clinical diagnostic test could be developed with more research. However, the feedback EEG method is not yet a proven diagnostic technique.

Alpha Rhythm↗