Development of a variable-radius pinhole SPECT system with a portable gamma camera

OBJECTIVE

To develop a small-animal SPECT system using a low cost commercial portable gamma camera equipped with a pinhole collimator, a continuous scintillation crystal and a position-sensitive photomultiplier tube.

MATERIAL AND METHODS

The gamma camera was attached to a variable radius system, which enabled us to optimize sensitivity and resolution by adjusting the radius of rotation to the size of the object. To investigate the capability of the SPECT system for small animal imaging, the dependence of resolution and calibration parameters on radius was assessed and acquisitions of small phantoms and mice were carried out.

RESULTS

Resolution values, ranging from 1.0mm for a radius of 21.4mm and 1.4mm for a radius of 37.2mm were obtained, thereby justifying the interest of a variable radius SPECT system.

CONCLUSIONS

The image quality of phantoms and animals were satisfactory, thus confirming the usefulness of the system for small animal SPECT imaging.

The effects of aging on dopaminergic neurotransmission: a microPET study of [11C]-raclopride binding in the aged rodent brain

Rodent models are frequently used in aging research to investigate biochemical age effects and aid in the development of therapies for pathological and non-pathological age-related degenerative processes. In order to validate the use of animal models in aging research and pave the way for longitudinal intervention-based animal studies, the consistency of cerebral aging processes across species needs to be evaluated. The dopaminergic system seems particularly susceptible to the aging process, and one of the most consistent findings in human brain aging research is a decline in striatal D2-like receptor (D2R) availability, quantifiable by positron emission tomography (PET) imaging. In this study, we aimed to assess whether similar age effects can be discerned in rat brains, using in vivo molecular imaging with the radioactive compound [(11)C]-raclopride. We observed a robust decline in striatal [(11)C]-raclopride uptake in the aged rats in comparison to the young control group, comprising a 41% decrement in striatal binding potential. In accordance with human studies, these results indicate that substantial reductions in D2R availability can be measured in the aged striatal complex. Our findings suggest that rat and human brains exhibit similar biochemical alterations with age in the striatal dopaminergic system, providing support for the pertinence of rodent models in aging research.

Testosterone stimulates progesterone production and STAR, P450 cholesterol side-chain cleavage and LH receptor mRNAs expression in hen (Gallus domesticus) granulosa cells

The chicken ovary is organized into a hierarchy of yellow yolky follicles that ovulate on successive days. Active or passive immunization of laying hens against testosterone blocks ovulation without affecting follicle development. Testosterone may play a role in pre-ovulatory follicle maturation by stimulating granulosa progesterone production. We assessed whether this stimulus is dose-related and depends on the maturity of the donor follicle, and if it does so by stimulating granulosa cell STAR, P450 cholesterol side-chain cleavage (P450scc), and LH receptor (LHCGR) mRNAs expression. Progesterone production by granulosa cells from F1, F3, and F4 follicles, cultured for 3 h without testosterone was greater in cells collected 11-14 h than 1-4 h after ovulation. These differences in progesterone production were less pronounced after granulosa cells had been cultured for 24 h. Culture of granulosa cells for 3 or 24 h with testosterone (1-100 ng/ml) stimulated progesterone production in cells collected from F4, F3, or F1 follicles 1-4, or 11-14 h after ovulation. Testosterone (0-4000 ng/ml) alone or in combination with LH (0-100 ng/ml) increased progesterone production by F1 granulosa cells, collected 1-4 and 11-14 h after ovulation and cultured for 3 h. Finally, testosterone (10 or 100 ng/ml) increased STAR, P450scc, and LHCGR mRNAs, when added to 3 h cultures of F1 granulosa cells. In conclusion, testosterone stimulates granulosa cell progesterone production in hen pre-ovulatory hierarchical follicles irrespective of maturational state, acting alone or additively with LH. We propose that testosterone promotes granulosa cell maturation to facilitate the pre-ovulatory release of LH.

Evaluation of six pesticides leaching indexes using field data of herbicide application in Casablanca Valley, Chile

A field study was performed to evaluate the accuracy of six pesticide screening leaching indexes for herbicide movement. Adsorption, dissipation and soil movement were studied in a vineyard in a sandy loam soil during 2005 season. Simazine, diuron, pendimethalin, oxyfluorfen and flumioxazin were applied to bare soil at rates commonly used, and their soil concentrations throughout soil profile were determined at 0, 10, 20, 40 and 90 days after application (DAA). Herbicides were subjected to two pluviometric regimens, natural field condition and modified conditions (plus natural rainfall 180 mm). Leaching indexes utilized were: Briggs's Rf, Hamaker's Rf, LEACH, LPI, GUS and LIX. Simazine reached 120 cm, diuron 90 cm, flumioxazin 30 cm soil depth respectively. Pendimethalin and oxyfluorfen were retained up to 5 cm. None of the herbicides leaching was affected by rainfall regimen. Only flumioxazin field dissipation was clearly affected by pluviometric condition. The best representation of the herbicide soil depth movement and leaching below 15 cm soil depth were: Hamaker's Rf < Briggs's Rf < GUS < LPI, < LEACH < LIX. Field results showed a good correlation between herbicides K(d) and their soil depth movement and mass leached below 15 cm soil depth.

Relevance in the Fischer−Tropsch Synthesis of the Formation of Fe−O−Ce Interactions on Iron−Cerium Mixed Oxide Systems

A series of Fe-Ce mixed oxides (95 atom % Fe-5 atom % Ce) has been prepared by different methods: coprecipitation, impregnation, and physical mixture of Ce and Fe oxides. These solids have been tested in the Fischer-Tropsch synthesis. The characterization of the catalytic precursors was carried out by X-ray diffraction (XRD), Raman, Mössbauer, and X-ray photoelectron (XPS) spectroscopic techniques. When the preparation method ensures a microscopic contact between Fe and Ce cations in the solid, several types of Fe-Ce interactions are present in the calcined solids. The interactions take the shape of Fe-O-Ce bridges that can exist either in the hematite-like solid solution or in the interphase between the Fe oxide covered by microcrystals of Ce oxide. In the case of the hematite-like solid solution, Ce(IV) cations are dissolved in the alpha-Fe2O3 network. The promotion by Ce of the catalytic properties observed in the final catalysts can be directly related with the detection of these Fe-O-Ce bridges in the calcined solids. The Ce promotion results in a larger yield to hydrocarbons, a higher production of olefins, and a higher selectivity to medium and large chain hydrocarbons (larger than six carbon atoms). It is proposed that the Ce promotion is due to the presence of Fe0-Ce(III) ensembles in the final catalysts arising from the initial Fe-O-Ce bridges developed in the parent calcined samples.

Ovine serum and pituitary isoforms of luteinising hormone during the luteal phase

The relative abundance of the different isoforms of pituitary and circulating luteinising hormone (LH) in ewes, at different times after the administration of gonadotrophin-releasing hormone (GnRH), during the luteal phase of the oestrous cycle was investigated. Sixteen ewes on Day 9 of their cycle were divided into four groups (n = 4). The control group (T0) received saline solution; the remaining animals received 100 μg GnRH (i.m.) 30, 90 or 180 min (T30, T90 and T180, respectively) before serum and pituitary gland collection. Luteinising hormone polymorphism was analysed by chromatofocusing (pH 10.5–3.5). The LH eluted from each chromatofocusing was grouped on the basis of the following three criteria: (1) according to the pH of elution (pH ≥ 10–3.5); (2) as either a basic (pH ≥ 7.5), neutral (pH 7.4–6.5) and acidic (pH ≤ 6.4) elution of LH of serum and hypophyseal origin; and (3) on the basis of distinct isoforms, of which 10 (A–J) were identifiable in hypophyseal extracts and four (A–D) were found in the serum. In general, the most abundant forms of LH in both the pituitary and serum, at all times, were basic. However, that proportion was greater in hypophyseal extracts (84 ± 3%, 81 ± 4%, 82 ± 3% and 83 ± 2% at T0, T30, T90 and T180, respectively) than in serum (51 ± 5%, 48 ± 10% and 54 ± 6% at T30, T90 and T180, respectively). Neutral and acidic LH made up a larger proportion of the total LH in sera (neutral: 17 ± 4%, 20 ± 6% and 23 ± 3% at T30, T90 and T180, respectively; acidic: 32 ± 8%, 32 ± 11% and 23 ± 6% at T30, T90 and T180, respectively) than in the pituitary extracts (neutral: 4.0 ± 0.7%, 10 ± 4%, 7 ± 2% and 5.0 ± 0.5% at T0, T30, T90 and T180, respectively; acidic: 12 ± 3%, 11 ± 2%, 12 ± 2% and 12 ± 2% at T0, T30, T90 and T180, respectively) at all times. These data reveal that the relative composition of the LH present in the pituitary gland and the LH secreted into the circulation is different, with more neutral and acidic isoforms being secreted. The pattern of circulating LH isoforms changes between 30 and 180 min after GnRH peak induction, with a greater proportion of isoform C (eluting between pH 7.0 and 6.5) at T180 compared with T30 and T90.

Pattern of circulating luteinizing hormone isoforms during the estrous and luteal phases in Holstein heifers

The pattern of distribution of circulating luteinizing hormone (LH) isoforms in cattle during estrus and the luteal phase was investigated. In each stage, the stage of the estrous cycle was synchronized in seven Holstein heifers with a prostaglandin analogue. After estrus was detected, blood samples were taken at 2-h intervals for 24h. In the luteal phase, animals received 250 microg i.v. of GnRH and blood samples were collected every 15 min for 5h. LH concentration in the samples was determined. Samples with the greatest LH concentration in estrus (pre-ovulatory peak) and those collected 60 min after GnRH administration (luteal phase) were analyzed by chromatofocusing, eluted with a pH gradient from 10.5 to 3.5. Eluted LH was grouped into basic (pH > or = 7.5), neutral (pH 7.4-6.5) and acidic isoforms (pH < or = 6.4) as well as by pH unit. In both phases, basic forms were the most abundant, and these were greater (P < 0.05) during the luteal phase (78.4 +/- 4.2%) as compared with during estrus (57.1 +/- 6.2%); the proportion of neutral and acidic isoforms in estrus (13.7 +/- 2.6%; 28.5 +/- 2.8%) was greater (P < 0.05) as compared with the luteal phase (3.0 +/- 0.7; 18.7 +/- 3.4). These results indicate that the relative proportion of LH isoforms secreted by the adenohypophysis differ by stage of estrous cycle. The addition of excess of NaCl to the column modifies the antigen-antibody binding in the RIA, and the proteins eluted are erroneously quantified as LH; this is an artifact of the technique.

The monocyte locomotion inhibitory factor produced by Entamoeba histolytica inhibits induced nitric oxide production in human leukocytes

The monocyte locomotion inhibitory factor, an anti-inflammatory pentapeptide produced by Entamoeba histolytica, inhibits the in vitro production of nitric oxide induced by cytokines (INF-gamma, TNF-alpha) or PMA in human leukocytes. This can be added to the other previously reported functional effects of this factor, such as the inhibition of monocyte locomotion and the synthesis of reactive oxygen intermediates in both monocytes and neutrophils. The decreased nitric oxide production may interfere with the killing of amebas by neutrophils in the early invasive stages of amebiasis, when oxidative mechanisms are used [reactive oxygen and nitrogen intermediates either individually or synergistically via peroxynitrite (ONOO(-))], and in the advanced stages, when both non-oxidative and oxidative (including nitric oxide) mechanisms are employed by macrophages. Diminished nitric oxide production by leukocytes may also contribute to the paucity of late inflammatory components in amebic abscess of the liver and other amebic lesions.

Preparation of seven- and eight-membered boron heterocycles from different salen ligands and arylboronic acids

Arylboronic acids and different salen ligands have been brought to reaction in a 2:1 stoichiometry in ethanol, toluene, and acetonitrile. In all cases bimetallic boronates with chiral boron atoms could be isolated with the difference that in ethanol mostly open bimetallic boronic esters are obtained, while in toluene or acetonitrile closed bimetallic complexes with a central seven- or eight-membered heterocyclic ring are formed. Both structural types have been characterized by spectroscopic techniques and X-ray crystallography showing that the reactions are diastereoselective in the case of the bimetallic heterocyclic structures. The configurations and conformations of the seven- and eight-membered rings are different, and this may depend on steric effects and/or repulsive intramolecular pi-pi interactions between the two salicylidene moieties attached to the central ring.

Effect of pre- and post-partum feed supplementation on the productive and reproductive performance of grazing primiparous Brahman cows

This experiment studied the combined effect of pre- and post-calving feed supplementation on the productive and reproductive performance of primiparous Brahman cows. The animals were 4 years old (420 kg live weight) and pregnant, and grazed rotationally on Stargrass (Cynodon nlemfuensis) pastures. Supplementation was given before and after (T1, n = 15), only before (T2, n = 15) or only after (T3, n = 16) calving, and there was an unsupplemented control (T4, n = 16). The supplement (1.5 kg/animal per day, 13.4 MJ digestible energy/kg dry matter and 20% crude protein) was given for 45 days before and/or after calving. Changes in body weight and body condition score and the productive behaviour of the calves were similar (p > 0.05) among treatments. The concentration of urea in the plasma was low in the control group (T4) before and after calving. The animals in all the groups had a poor reproductive performance. The percentage of cows in oestrus was higher (p < 0.05) in T1 (73.3%) than in T3 (37.5%). The interval from calving to conception (148.7 +/- 53.7 days) and the pregnancy rate (48.5%) were similar (p > 0.05) among the treatments. The level of supplementation offered before and/or after calving did not improve the pregnancy rate.

Multinodular polymyositis in a patient with human immunodeficiency and hepatitis C virus coinfection

We report a patient who developed multiple inflammatory muscle masses and generalized polymyositis in the setting of combined human immunodeficiency virus (HIV) and hepatitis C virus (HCV) infection. Magnetic resonance imaging (MRI) of muscles showed patchy edema which was particularly intense within the nodular masses. Polymerase chain reaction (PCR) showed no evidence of either virus within muscle. This report reviews earlier literature on muscle nodules associated with myositis and discusses the differential diagnosis of muscle masses in HIV infection.