Biomedical subjects
S Brody
Publications and source records attributed to S Brody.
Differential beta- and alpha-adrenergic activation during psychological stress.
The responsivity of several cardiovascular indices to a computerized mental arithmetic stress and a cold pressor stress were investigated in 22 healthy adult subjects. The major findings were that the largely beta-adrenergically driven T-wave amplitude, pre-ejection period, R-wave to pulse interval, and left ventricular ejection time values responded only to mental arithmetic; a significant decrease in cardiac output and increase in peripheral resistance were elicited during the cold pressor test; inter-beat-interval and subjective stress ratings responded significantly to both stresses compared to baseline levels, but more intensely to mental arithmetic than the cold pressor test; blood pressure, stroke volume and the maximum of the first derivative of the raw impedance signal responded unspecifically to both stresses. These findings support the idea that cardiovascular responses to psychological challenge depend on the level of cognitive processing required for the task. In addition, the superfluity of multiple variable measurements to study cardiovascular reactivity in such situations is discussed.
Somatotosensory evoked potentials during baroreceptor stimulation in chronic low back pain patients and normal controls.
Nineteen chronic low back pain patients (aged 19-63) and 17 controls (aged 20-41) received electrical pain stimuli during manipulation of their carotid baroreceptors. The non-invasive mechanical manipulation of baroreceptors, using the PRES technique (Phase Related External Suction), simulates the end-effects of phasic blood pressure changes. This technique was developed to assess pain responses induced by changes in blood pressure without the typical shortcomings of pharmacological manipulation or lack of a control condition. During maximum baroreceptor activity, there was an unexpected increase in the amplitude of the somatosensory evoked potentials (SEPs) elicited by the electrical pain stimuli condition (N150-P260 peak-to-peak). In most other studies the opposite effect was found, with decreased pain responses during maximum baroreceptor activity. The chronic pain group reported greater pain during highest baroreceptor activation than did the controls. In addition, the chronic pain group showed lower diastolic blood pressure. To determine whether pain and baroreceptor responses observed in the chronic pain group depended on lower blood pressure levels, a second experiment with a non-clinical sample was performed. Results showed that lower tonic blood pressures are associated with greater baroreceptor activity amplifying pain, while higher blood pressure is associated with pain dampening during high baroreceptor activity. Data suggested that the differences in pain responses found in low back pain patients were associated with their lower tonic blood pressure levels. It is proposed that in general, lower blood pressures may be associated with greater pain during baroreceptor activation.
Four-year stability of cardiovascular reactivity to psychological stress.
The 4-year stability of cardiovascular responses to laboratory psychological stress (mental arithmetic) was examined in 75 adults. The stability coefficients were .76 for heart rate (HR) change and .81 for absolute HR, .66 for systolic blood pressure (SBP) change and .52 for absolute SBP, .16 for diastolic blood pressure (DBP) change and .27 for absolute DBP. Males had greater SBP and DBP reactivity than females in the first session, but this reactivity decreased by the 4-year follow-up session (which was not the case for women).
Temperature compensation and membrane composition in Neurospora crassa.
The link between temperature compensation of the circadian rhythm and temperature-induced adjustment of membrane composition in Neurospora crassa is briefly reviewed. In common with most organisms, Neurospora responds to changes in growth temperature by adjusting its lipid composition, primarily by increasing the degree of unsaturation of its fatty acids at low temperature. This may result in maintenance of either membrane fluidity or phase transition behavior over a range of temperatures. In Neurospora, there are three mutations (frq, cel, and chol-1) that affect temperature compensation of the circadian rhythm; cel and chol-1 are defective in lipid synthesis, and frq interacts with the other two in double-mutant strains. This suggests that lipid metabolism may play a role in temperature compensation of the rhythm, and that the FRQ gene product may also be involved in membrane function, either in regulating lipid composition or as a sensor responding to changes in lipid composition.
Marriage and mortality in prostate cancer.
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Decline in HIV infections in Thailand.
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Waveform reliability of the phase related external suction baroreceptor manipulation method.
The phase related external suction (PRES) method of controlled carotid baroreceptor manipulation (a neck cuff with cardiac cycle timed pressure variations) has been used to investigate not only the human baroreflex, but extrahomeostatic effects of baroreceptor activity (such as the modulation of cortical activity, peripheral reflexes, and pain) as well. The present study provides quantitative within subject test-retest reliability estimates of PRES effects on 6-s trial-length heart rate waveforms. Mean within subject test-retest reliability for each averaged heart rate response waveform was 0.77 for the baroreceptor stimulation (systolic negative/diastolic positive cuff pressure) condition, 0.56 for the control condition (diastolic negative/systolic positive cuff pressure), and 0.69 for the difference between conditions. The importance of analyzing time-intensity dynamics, rather than merely the mean or maximum effect of any treatment variable is emphasized, and recommended for investigations of a wide variety of short duration, induced physiological time series processes.
Incidence of HIV infection decreases because of nature of epidemics.
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Continued lack of evidence for transmission of human immunodeficiency virus through vaginal intercourse: a reply to Carey and Kalichman.
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Placenta increta occurring in a blighted ovum.
We present a rare case of placenta increta, confirmed postoperatively by pathologic analysis, occurring before 20 weeks' gestation in a blighted ovum. Hysterectomy was necessary for control of hemorrhage.
The evolution of character.
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Questioning the validity of self-reported heterosexual HIV transmission.
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Characterization of the different spectral forms of glutamate 1-semialdehyde aminotransferase by mass spectrometry.
Glutamate 1-semialdehyde aminotransferase produces delta-aminolevulinate for the synthesis of chlorophyll, heme, and other tetrapyrrole pigments. The native enzyme from Synechococcus is pale yellow and has absorption maxima at 338 and 418 nm from vitamin B6. Yellow, colorless, and pink forms of the protein are obtained by treatment with 4,5-dioxovalerate, 4,5-diaminovalerate, and acetylenic GABA, respectively. Compared to the native enzyme, the 418 nm absorption maximum in the yellow enzyme is enhanced and the 338 nm maximum reduced while the colorless enzyme has a heightened maximum at 338 nm and a barely detectable peak at 418 nm. The pink enzyme has an absorption maximum at 560 nm. When the native and colorless enzymes are repeatedly diluted in 0.5 M Na2HPO4, pH 7.0, and reconcentrated, pyridoxamine 5'-phosphate is released and the 338 nm maximum lost. Thus the 338 nm absorption maximum is associated with noncovalently bound pyridoxamine 5'-phosphate. NaBH4 reduction proved that the absorbance at 418 nm is from pyridoxal 5'-phosphate cofactor bound by a Schiff base to the protein. When the native, colorless, and yellow enzymes were subjected to electrospray ionization mass spectrometry, the B6 cofactor dissociated from the protein and gave a molecular weight of 46,401-46,418. Acetylenic GABA and NaBH4 were used for protein modification, and they reacted with the native and yellow enzymes but had no effect on the colorless enzyme. Pyridoxal 5'-phosphate bound covalently to the protein after NaBH4 reduction. Acetylenic GABA attached covalently to the enzyme produced an additional mass peak, 123-126 mass units higher, in the electrospray ionization spectrum.(ABSTRACT TRUNCATED AT 250 WORDS)
Impact factor as the best operational measure of medical journals.
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Lack of evidence for transmission of human immunodeficiency virus through vaginal intercourse.
Research in determining risks for human immunodeficiency virus (HIV) transmission is confounded by many issues. They include lack of clarity or specificity in terminology used, respondents misunderstanding of questions, and lying. The base rate of lying (or social desirability responding) by itself is sufficient to account for the small percentage of Americans and Europeans claiming "heterosexual" transmission from partners not known to be intravenous drug users. This study integrates the physiological and epidemiological data on risk factors for HIV transmission with the psychological literature on the frequency of anal intercourse and of lying (in this case to researchers and clinicians about risk factors). When these factors are considered, intravenous and anal activities remain the only clear vectors for HIV transmission. Research suggesting that spermicidals are more effective at inactivating HIV than condoms are at physically containing HIV is also noted.
The relationship between habitual anger coping style and serum lipid and lipoprotein concentrations.
The relationship between habitual anger coping styles, especially anger expression in a socially assertive manner and serum lipid concentrations was examined in 86 healthy subjects. Habitual anger expression was measured by the Müller Anger Coping Questionnaire (MAQ) on four scales: Aggression, Controlled Affect, Guilt, and Social Inhibition. A positive correlation between serum cholesterol and Aggression was found, as was a negative correlation between LDL/HDL ratio and Controlled Affect. These correlations remained significant after adjustments for age, Body Mass Index (BMI), athletic activity, alcohol, nicotine and coffee consumption. After these adjustments, significant negative partial correlations between Controlled Affect and both total cholesterol and LDL were also found. We found no significant gender differences on any lipid measure. This study demonstrated that unfavourable lipid profiles are linked to a predominantly aggressive anger coping style, whereas favourable lipid profiles are associated with more socially assertive anger coping (Controlled Affect). Thus the expression of anger in a socially assertive manner can be seen as health promoting. The MAQ scales were better predictors of total serum cholesterol concentrations than the health related behaviors and characteristics. Results are discussed in terms of a psychophysiological risk model of inadequate anger coping.
A phase 1 study, in cystic fibrosis patients, of the safety, toxicity, and biological efficacy of a single administration of a replication deficient, recombinant adenovirus carrying the cDNA of the normal cystic fibrosis transmembrane conductance regulator gene in the lung.
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