Cembranoids from the cultured soft coral Sinularia gibberosa.

An EtOAc extract of the cultured soft coral Sinularia gibberosa yielded a new cembrane-based diterpenoid, cugibberosene A (1), together with the previously reported three cembranoids (2-4). The structure determination was based on extensive NMR studies. The cytotoxic and antibacterial activities of theseisolated metabolites 1-4 were evaluated in vitro.

Dichotic multiple-frequency auditory steady-state responses in evaluating the hearing thresholds of occupational noise-exposed workers.

An objective, fast, and reasonably accurate assessment test that allows for easy interpretation of the responses of the hearing thresholds at all frequencies of a conventional audiogram is needed to resolve the medicolegal aspects of an occupational hearing injury. This study evaluated the use of dichotic multiple-frequency auditory steady-state responses (Mf-ASSR) to predict the hearing thresholds in workers exposed to high levels of noise. The study sample included 34 workers with noise-induced hearing impairment. Thresholds of pure-tone audiometry (PTA) and Mf-ASSRs at four frequencies were assessed. The differences and correlations between the thresholds of Mf-ASSRs and PTA were determined. The results showed that, on average, Mf-ASSR curves corresponded well with the thresholds of the PTA contours averaged across subjects. The Mf-ASSRs were 20±8dB, 16±9dB, 12±9dB, and 11±12dB above the thresholds of the PTA for 500Hz, 1,000Hz, 2,000Hz, and 4,000Hz, respectively. The thresholds of the PTA and the Mf-ASSRs were significantly correlated (r=0.77-0.89). We found that the measurement of Mf-ASSRs is easy and potentially time saving, provides a response at all dichotic multiple frequencies of the conventional audiogram, reduces variability in the interpretation of the responses, and correlates well with the behavioral hearing thresholds in subjects with occupational noise-induced hearing impairment. Mf-ASSR can be a valuable aid in the adjustment of compensation cases.

Brain biochemical correlates of the plasma homocysteine level: a proton magnetic resonance spectroscopy study in the elderly subjects.

BACKGROUND: An elevated plasma homocysteine level has been reported to be associated with various neuropsychiatric diseases. However, little is known about the brain biochemical changes associated with the higher plasma homocysteine level. The main goal of this study was to examine the sex difference in brain biochemical concentrations using brain proton magnetic resonance spectroscopy (H MRS), and to elucidate the biochemical changes associated with plasma homocysteine levels by sex in healthy elderly subjects. METHODS: Seventy elderly subjects without any clinical psychiatric and neurological disease underwent 3-T brain H MRS. MRS spectra were acquired from voxels placed on the left side of the basal ganglia, frontal lobe, and hippocampus. Brain biochemical concentrations were compared between the elderly male and female participants. Correlations between these biochemical concentrations and plasma homocysteine levels by sex were analyzed. RESULTS: Female participants had significantly higher levels of choline in the left frontal lobe and hippocampus, and lower creatine and myo-inositol, in the left basal ganglia than did males. A higher homocysteine level was correlated with a lower N-acetylaspartate (NAA) concentration in the left hippocampus in elderly women (r = -0.44; p = 0.03) but not in elderly men. CONCLUSIONS: This study found that there was a sex difference in brain biochemical concentrations in the elderly participants. A higher plasma homocysteine level was associated with a lower NAA in the hippocampus of elderly women. The sex difference in association between brain biochemical concentrations and plasma homocysteine levels needs further investigation. We speculate that after menopause, women lose protection of estrogen from the neurotoxic effects of homocysteine in the hippocampus. Future studies are required to examine this speculation.

Brain proton magnetic resonance spectroscopic study of insight among elders with late-life depression in remission.

BACKGROUND: Insight refers to an awareness and attribution of disorders and attitude toward treatment. While neurocognitive studies indicate that lack of insight is associated with frontal lobe dysfunction, little is known about the neurobiochemical profile of insight. We investigated the neurobiochemical characteristics of insight within the frontal lobe using proton magnetic resonance spectroscopy ((1)H MRS) among elderly people with major depressive disorders in remission. METHODS: Seventy-five elderly patients with major depressive disorder in remission underwent assessment of insight using the Mood Disorders Insight Scale (MDIS), including awareness, attribution, and need for treatment. Brain (1)H MRS spectra were acquired from voxels located in the left frontal lobe. Ratios of N-acetylaspartate (NAA), choline, and myo-inositol reference to total creatine (tCr) were calculated. Correlations between these biochemical ratios and insight were examined. Secondary analyses included the association of biochemical ratios with each of the subscales of insight. RESULTS: Twenty (26.7%) study participants scored full points on the MDIS scale. Total scores of MDIS correlated with NAA/tCr (rho=0.31; p<0.006) in the left frontal lobe. Secondary analyses showed the depressive elders with inadequate attribution to their disease had lower levels of NAA/tCr than those with full insight regarding attribution. CONCLUSIONS: Biochemical changes on (1)H MRS support that the left frontal lobe may involve insight and relate more specifically to disease attribution. Lower levels of NAA/tCr suggest that the neuronal dysfunction in the left frontal lobe is associated with inadequate insight in late-life depression.

Proton magnetic resonance spectroscopy of late-life major depressive disorder.

The primary goal of this study was to examine the biochemical abnormalities of late-life major depression by using 3-tesla (3-T) proton magnetic resonance spectroscopy ((1)H-MRS). The antidepressant effects on the biochemical abnormalities were investigated as well. Study participants were 27 elderly patients with major depressive disorders (among which 9 were on antidepressant medication) and 19 comparison elderly subjects. (1)H-MRS spectra were acquired from voxels that were placed in the left frontal white matter, left periventricular white matter, and left basal ganglia. Ratios of N-acetylaspartate (NAA), choline (Cho) and myo-inositol to creatine were calculated. Patients with late-life major depressive disorder had a significantly lower NAA/creatine ratio in the left frontal white matter, and higher Cho/creatine and myo-inositol/creatine ratios in the left basal ganglia when compared with the control subjects. The myo-inositol correlated with global cognitive function among the patients. The biochemical abnormalities in late-life major depressive disorder were found on the left side of the frontal white matter and the basal ganglia. Neuron degeneration in the frontal white matter and second messenger system dysfunction or glial dysfunction in the basal ganglia are suggested to be associated with late-life depression.