Concern for toxicity following exposure to organophosphorus insecticides led us to investigate whether topical application of either malathion or malathion mixed in a protein bait as used for aerial spray applications could be toxic to the ocular/visual system. Adult male Long-Evans rats were either untreated or treated with malathion alone (two drops per day in each eye), bait alone (six drops per day in each eye) or malathion and bait (six drops per day in each eye). The dose levels of malathion alone and malathion and bait were chosen based on pilot work and provided approximately equivalent amounts of active ingredient. The rats were treated 5 days a week for 4 weeks. During the final week of treatment, the rats were implanted surgically with cranial recording electrodes overlying the visual projection area of the cerebral cortex. Visual pattern-evoked potentials (PEPs) were elicited with vertical sinusoidal gratings at three levels of stimulus spatial frequency (0. 08, 0.16 and 0.32 cycles per degree) and three levels of visual contrast (0.15, 0.30 and 0.60). After spectral analysis of the PEP waveforms, the amplitude and phase at the stimulus rate (F1) and the first harmonic (F2) were determined. Although F1 and F2 parameters were influenced significantly by manipulation of the stimulus parameters, no significant differences were observed that could be attributed to treatment with the test substances. In addition, an ophthalmological examination of the eyes and a light microscopic evaluation of ocular tissues, including retina and optic nerve, revealed no treatment-related lesions. The dose levels used in this study were high-approximately 84000 times the exposure per unit surface area expected from aerial spraying-and yet the visual function of the treated subjects was apparently normal. This study identified no significant toxicological concerns regarding direct ocular contact exposure to malathion.

Administration, Topical↗

PubMedDate not supplied

Production and purification of a recombinant elastomeric polypeptide, G-(VPGVG)19-VPGV, from Escherichia coli.

An elastomeric polypeptide was produced, with the sequence G-(VPGVG)19-VPGV, as a fusion to glutathione S-transferase using the vector pGEX-3X. The fusion protein was expressed to high levels in Escherichia coli as indicated by SDS-PAGE analysis of induced cells. The fusion protein was affinity purified and cleaved with protease factor Xa, and the elastomeric polypeptide was recovered to a high degree of purity as indicated by SDS-PAGE followed by staining with CuCl2. The physical characterizations of carbon-13 and proton nuclear magnetic resonance and of the temperature profile for turbidity formation for the inverse temperature transition of hydrophobic folding and assembly attest to the successful microbial synthesis of the polypentapeptide of elastin. The results of these studies provide the initial progress toward achieving a more economical and practical means of producing material for elastic protein-based polymer research and applications.

Amino Acid Sequence↗

PubMedDate not supplied

Visual imagery and depersonalisation.

Twenty-eight people diagnosed with depersonalisation disorder (DD) were assessed using self-report measures of imagery ability in relation to a range of symptoms and in comparison with age- and sex-matched controls. It was found that symptoms of depersonalisation as well as other dissociative symptoms and depressed mood correlated with impaired ability to generate visual images. This was particularly evident with images pertaining to the self and other people as opposed to objects. A subgroup of 10 patients was tested on a neuropsychological battery of visual perception tests and found to be unimpaired compared with normal controls and patients with obsessive compulsive disorder, despite subjective impairments in imagery and high symptom scores. The findings add further weight to the distinctions made between imagery and perceptual processes.

Adult↗

PubMedDate not supplied

Optimizing ACTH-stimulated steroid secretion by cultured adrenocortical tumor cells.

If 1 mM supplemental Ca++, or 1.6 mg hemoglobin (Hb)/ml medium (23.5 uM, a concentration comparable to that in 1 ml mouse blood), was added to Eagle's minimum essential medium (MEM) (which contains 1 mM Ca++), basal and maximally stimulated 20-dihydroprogesterone (20-DHP) secretion by cultured Y-1 mouse adrenal tumor cells [49-65th passages] could be measured by radioimmunoassay after a 0.5 hr incubation. ACTH-stimulated, but not basal, 20-DHP secretion increased after 1 mM Ca++ treatment. 5 mM EGTA significantly reduced basal and stimulated 20-DHP secretion, although significant ACTH stimulation still remained. Basal and stimulated secretion significantly increased when Hb was present. Although O2 involvement in the Hb effect was tested by bubbling medium with 100% O2 for 10 minutes, basal and stimulated secretion was unaffected. Since proteins, such as Hb, non-specifically bind free steroids, enhancing secretion, albumin (Al) was compared to Hb. Al enhanced unstimulated, but not ACTH-stimulated, 20-DHP secretion. The Hb effect may not be due to non-specific protein-steroid binding. Ca++ supplementation and chelation studies suggest the necessity to optimize co-factors in steroidogenic tissue incubation media to maximize basal and stimulated steroid synthesis and secretion. Since physiologically relevant Hb levels enhanced basal and stimulated Y-1 cell steroid secretion by mechanisms other than protein-steroid binding and soluble O2 had little effect, Hb may more efficiently transport O2 to cultured cells than soluble O2 diffusion through medium does.

20-alpha-Dihydroprogesterone↗

PubMedDate not supplied

Competing with heart.

Explore the source record for details and available documents.

Dental Prosthesis Design↗

PubMedDate not supplied

Influence of chronic cigarette smoke exposure on the uptake and efflux of imipramine in the isolated perfused rat lung.

The pulmonary uptake and efflux of imipramine was determined in lungs removed from cigarette smoke-exposed and nonexposed rats. Using an isolated perfused lung preparation, the lung was perfused for 220 sec with medium containing 2.5 X 10(-7) M imipramine, followed by a 28-min drug-free perfusion. There was no significant difference (p less than 0.05) between either the rate or the amount of imipramine accumulated in the smoke-exposed and nonexposed animals. During the drug-free perfusion, the previously accumulated imipramine was released from two distinct pools (E1 and E2). Calculation of the total amount of effluxable imipramine indicated that in the nonexposed animals approximately 30% of the amount taken up did not efflux at a measurable rate but formed a "noneffluxable" pool. In the smoke-exposed animals, however, all of the accumulated imipramine appeared to be effluxable. These data demonstrate that there may be components of cigarette smoke which are sequestered by lung tissue at the binding sites associated with the noneffluxable pool of imipramine. The presence in cigarette smoke of components possessing such high pulmonary affinity may be a factor in cigarette smoke-mediated lung damage; this possibility is discussed.

Animals↗