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PubMed1984

Adult testosterone levels influence the morphology of a sexually dimorphic area in the Mongolian gerbil brain.

This research shows that the medial preoptic area-anterior hypothalamus (MPOA-AH) of the gerbil contains a sexually dimorphic area (SDA) whose morphology is influenced by adult gonadal steroids. The characteristics of the SDA were studied initially in gonadally intact males and females and later in males and females that had been gonadectomized or gonadectomized and given testosterone. Coronal sections through the MPOA-AH were stained with thionin to visualize the SDA. In male gerbils, the SDA is a darkly staining, hook-shaped structure on either side of the third ventricle, above the suprachiasmatic nuclei and below the anterior commissure. Within the male SDA lies a small, dense cluster of cells, the SDA pars compacta (SDApc). In female gerbils, the SDA is more ovoid and diffuse and the SDApc is absent. Camera lucida tracings and planimeter measurements of the SDA showed that the total volume of the SDA is similar in the two sexes, but the proportion of the SDA that stains darkly and/or stands out clearly from the surround (dark volume) is larger in males. Gonadectomy decreases both total and dark volume of the SDA in both sexes and decreases the volume of the SDApc in males. Testosterone treatment prevents these changes. This is the first report of changes in the gross morphology of the mammalian brain after steroid hormone manipulations in adulthood. The changes in the SDA may be related to testosterone activation of scent marking behavior.

Animals↗
PubMed1992

Vasopressin innervation of sexually dimorphic structures of the gerbil forebrain under various hormonal conditions.

The distribution of vasopressin-immunoreactive fibers in the forebrain of male and female gerbils was studied, focusing on the lateral septum and the sexually dimorphic area (SDA) found at the border between the medial preoptic area and the anterior hypothalamus. To study hormonal influences on the densities of these fibers, some animals of each sex were gonadectomized or gonadectomized and given testosterone. Others were given sham operations. High densities of vasopressin-immunoreactive fibers were found in the lateral septum. In the SDA, the densities of these fibers varied considerably. Many were found in the medial half of the medial SDA, but few in the lateral SDA. Vasopressin-immunoreactive fibers were also sparse in the lateral half of the medial SDA, except for a dense cluster in the SDA pars compacta of males. Similar but smaller clusters were seen in the same location in females although the SDA pars compacta could not be detected in Nissl-stained sections from the female brains. Fiber densities in two areas, the lateral septum and the lateral SDA, were sensitive to gonadal steroids. In both cases, castration reduced fiber density and testosterone enhanced it. In addition, fiber densities in two areas, the lateral septum and the medial SDA, were sexually dimorphic. In each case, fiber density was greater in males. There was no hormonal effect, however, on the fiber densities in the medial SDA. The fact that the fiber plexuses in the lateral septum and the medial SDA respond differently to gonadal steroids suggests that they arise from different cells and possibly from different areas of the brain. The vasopressin-immunoreactive fibers in the lateral septum probably come from steroid-sensitive vasopressin neurons in the bed nucleus of the stria terminalis. Those in the medial SDA may originate in the dorsal aspect of the suprachiasmatic nucleus where vasopressin-immunoreactive cell bodies were seen.

Animals↗
PubMed1978

Mechanism of action of papain: aryldehydroalanines as spectroscopic probes of acyl enzyme formation.

The alpha,beta-unsaturated aromatic amino acids phenyldehydroalanine (PDA) and styryldehydroalanine (SDA) were synthesized and used as sensitive spectroscopic probes to study the acylation of papain by specific substrates and inhibitors. The spectral changes observed upon acylation of the enzyme with peptides containing these amino acids are large red shifts of the absorption maxima (lambda max) of the chromophores. The magnitudes of the absorption shifts were 49 nm (from 277 to 326 nm) for PDA peptide and 59 nm (from 318 to 377 nm) for SDA peptides. The following specific substrates were synthesized: Ac-Phe-Phe-PDA-OEt, Ac-Phe-PDA-NH2, Ala-Ala-Phe-SDA-OME, Ala-Ala-Phe-SDA-NH2, Lys-Ala-(o-benzyl)tyrosyl-SDA-OMe, and Lys-Ala-(o-benzyl)-tyrosyl-SDA-NH2. Similarly, the specific competitive inhibitors Ac-Phe-PDA (Ki = 5.3 X 10(-6) M), Z-Phe-SDA (Ki = 5.6 X 10(-5) M), Ala-Ala-Phe-SDA (Ki = 2.9 X 10(-5) M), and Lys-Ala-(o-benzyl)tyrosyl-SDA (Ki = 1.1 X 10(-5) M) were prepared. An additional chromophore was used to follow the noncovalent association of an inhibitor or substrate with papain, independently from the acylation or deacylation steps. This chromophore, which was introduced into the peptides at position P2, IS p-(p"-dimethylaminophenylazo) phenylalanine (DAP). The light absorption spectrum of DAP is dependent on its environment. The substrates Ala-Ala-DAP-SDA-OMe and Ala-Ala-DAP-SDA-NH2 and the competitive inhibitor Ala-Ala-DAP-SDA (Ki = 2.5 X 10(-6) M) were prepared. The noncovalent binding of these peptides to the active site of papain was followed either by the increase in the absorption at 480 nm or the decrease at 550 nm. With these petides the acylation and deacylation reactions could be followed simultaneously at 377 nm. The extent of acyl enzyme formation was found to decrease in a sigmoidal way with increasing pH, with a transition point around pH 5.5.

Alanine↗
PubMed2003

Radiation (gamma) resistance and postirradiation growth of Listeria monocytogenes suspended in beef bologna containing sodium diacetate and potassium lactate.

Listeria monocytogenes, a psychrotrophic foodborne pathogen, is a frequent postprocessing contaminant of ready-to-eat (RTE) meat products, including frankfurters and bologna. Ionizing radiation can eliminate L. monocytogenes from RTE meats. When they are incorporated into fine-emulsion sausages, sodium diacetate (SDA) and potassium lactate (PL) mixtures inhibit the growth of L. monocytogenes. The radiation resistance of L. monocytogenes, and its ability to proliferate during long-term refrigerated storage (9 degrees C), when inoculated into beef bologna that contained 0% SDA-0% PL, 0.07% SDA-1% PL, and 0.15% SDA-2% PL, were determined. The radiation doses required to eliminate 90% of the viable L. monocytogenes cells were 0.56 kGy for bologna containing 0% SDA-0% PL, 0.53 kGy for bologna containing 0.07% SDA-1% PL, and 0.46 kGy for bologna containing 0.15% SDA-2% PL. L. monocytogenes was able to proliferate on bologna containing 0% SDA-0% PL during refrigerated storage, but the onset of proliferation was delayed by the addition of the SDA-PL mixtures. An ionizing radiation dose of 3.0 kGy prevented the proliferation of L. monocytogenes and background microflora in bologna containing 0.07% SDA-1% PL and in bologna containing 0.15% SDA-2% PL over 8 weeks of storage at 9 degrees C. Little effect on lipid oxidation and color of the control bologna, or bologna containing SDA-PL mixtures, was observed upon irradiation at either 1.5 or 3.0 kGy.

Animals↗
PubMed1988

Afferent connections of the sexually dimorphic area of the hypothalamus of male and female gerbils.

We studied neural inputs to the sexually dimorphic area (SDA) of the gerbil hypothalamus by injecting wheat-germ agglutinin-horseradish peroxidase into its medial or lateral components in males and females. To confirm the topography of SDA afferents, we injected Phaseolus vulgaris-leucoagglutinin into areas where retrograde labeling from the medial and lateral SDA differed. Both methods indicated that the medial SDA received stronger inputs from the medial part of the bed nucleus of the stria terminalis, the ventral part of the lateral septal nucleus, the medial amygdaloid nucleus, and the amygdalohippocampal area, than the lateral SDA does. In contrast, the rostrodorsal part of the lateral septum, the lateral part of the bed nucleus of the stria terminalis, the anterior and posterior hypothalamic areas, and the dorsomedial hypothalamic nucleus project more heavily to the lateral than to the medial SDA. In addition, retrograde labeling suggested that the ventral part of the premammillary nucleus projects more strongly to the medial than to the lateral SDA, whereas the infralimbic area of the cortex and the lateral preoptic area project more strongly to the lateral than to the medial SDA. The densities of cells in the bed nucleus of the stria terminalis and medial amygdaloid nucleus that could be retrogradely labeled from the medial SDA were greater in males than in females. This was not true of labeling in the arcuate nucleus or in the ventral part of the lateral septal nucleus. Since the medial SDA receives strong inputs from areas with many steroid-accumulating cells, it could respond to steroids directly and via these afferents. In contrast, hormonal effects on the lateral SDA are more likely to occur locally.

Animals↗
PubMed2005

Comparison of stearidonic acid and alpha-linolenic acid on PGE2 production and COX-2 protein levels in MDA-MB-231 breast cancer cell cultures.

The bioactivity of stearidonic acid (SDA, 18:4n-3) and alpha-linolenic acid (LNA, 18:3n-3) on cyclooxygenase-2 (COX-2) enzyme expression and prostaglandin E2 (PGE2) production has not been evaluated. This investigation examined the effects of SDA and LNA on PGE2 biosynthesis and COX-2 protein and mRNA levels in MDA-MB-231 human breast cancer cells. Cells were supplemented with SDA, LNA, linoleic acid and arachidonic acid (AA) at concentrations ranging from 10 to 200 microM. At 50 and 200 microM, both SDA and LNA treatments and their combinations reduced PGE2 production as compared with AA. At 50 microM, SDA treatment also lowered the COX-2 protein level as compared with the vehicle, but this reduction was not observed with the LNA treatment. Gas chromatographic analysis of fatty acids in cellular lipids of breast cancer cells revealed that SDA led to significantly greater concentrations of 20:5n-3 and other long-chain (LC) n-3 polyunsaturated fatty acids (PUFAs) (20:4n-3, 22:4n-3 and 22:5n-3) as compared with the LNA treatment. Both SDA and LNA reduced the level of 20:4n-6; however, SDA was more effective than LNA in decreasing the ratio of n-6/n-3 PUFAs in cells. In addition, SDA was more potent than LNA in suppressing the expression of the COX-2 gene, which was associated with the reduction in the levels of nuclear factor kappa B and peroxisome proliferator-activated receptor gamma mRNA. This study showed that although PGE2 production in MDA-MB-231 breast cancer cells was not significantly different between the SDA and LNA treatments, SDA was more effective than LNA in converting into LC n-3 PUFAs and in reducing COX-2 protein and mRNA levels.

Blotting, Western↗
PubMed2000

Determination and quantification of sulfadiazine and trimethoprim in swine tissues using liquid chromatography with ultraviolet and mass spectrometric detection.

High-performance liquid chromatographic procedures with ultraviolet detection were developed for the quantitative determination of sulfadiazine (SDA) and trimethoprim (TMP) in swine tissues (kidney, liver, muscle, fat and fat + skin). In addition, high-performance liquid chromatography with atmospheric pressure chemical ionization mass spectrometry was used for the confirmation of the identity of the analytes of interest. Chromatographic separation was achieved on a Spherisorb ODS-2 column (250 x 4.6 mm id, dp 5 microns). The mobile phase for SDA analysis consisted of 1% acetic acid in water-acetonitrile (85 + 15, v/v). For TMP analysis a 80 + 15 + 5 (v/v/v) mixture of 0.25% triethylammonium acetate in water, acetonitrile and methanol was used as the eluent. Sulfamerazine and ormethoprim were used as the internal standards for SDA and TMP analysis, respectively. For the isolation of the compounds of interest from biological samples, a liquid-liquid extraction with acetone and ethyl acetate, followed by a clean-up using a solid-phase extraction column (aminopropyl and benzenesulfonic acid for SDA, benzenesulfonic acid for TMP) was performed. Calibration graphs were prepared for all tissues and linearity was achieved over the concentration ranges tested (50-1000 ng g-1 for SDA, r > or = 0.9979; 25-500 ng g-1 for TMP, r > or = 0.9994). The method was validated at the maximum residue level (MRL, 100 ng g-1 for SDA and 50 ng g-1 for TMP), at half the MRL and at double the MRL for both SDA and TMP. The accuracy and precision (expressed as the within-day repeatability) were found to be within the required ranges for each specific concentration. The quantification limits were 50 ng g-1 for SDA and 25 ng g-1 for TMP. The limits of detection were below one half the MRLs. Both methods were selective for the determination of SDA and TMP. Biological samples (kidney, liver, muscle, fat and fat + skin) from pigs that received a commercial SDA-TMP preparation with the feed for five consecutive days (dose rate: 25 mg SDA and 5 mg TMP kg body weight-1 day-1) were analyzed using the described methods. The quantitative results were used to calculate a withdrawal time (12 days) to reach residue levels below the respective MRLs. This calculation was performed according to the recommendations of the European Agency for the Evaluation of Medicinal Products (EMEA/CVMP/036/95).

Animals↗
PubMed2006

Specific dynamic action of ambystomatid salamanders and the effects of meal size, meal type, and body temperature.

The past decade has witnessed a dramatic increase in studies of amphibian and reptile specific dynamic action (SDA). These studies have demonstrated that SDA, the summed energy expended on meal digestion and assimilation, is affected significantly by meal size, meal type, and body size and to some extent by body temperature. While much of this attention has been directed at anuran and reptile SDA, we investigated the effects of meal size, meal type, and body temperature on the postprandial metabolic responses and the SDA of the tiger salamander (Ambystoma tigrinum tigrinum). We also compared the SDA responses among six species of Ambystoma salamanders representing the breadth of Ambystoma phylogeny. Postprandial peaks in VO(2) and VO(2), duration of elevated metabolism, and SDA of tiger salamanders increased with the size of cricket meals (2.5%-12.5% of body mass). For A. tigrinum, as for other ectotherms, a doubling of meal size results in an approximate doubling of SDA, a function of equal increases in peak VO(2) and duration. For nine meal types of equivalent size (5% of body mass), the digestion of hard-bodied prey (crickets, superworms, mealworms, beetles) generated larger SDA responses than the digestion of soft-bodied prey (redworms, beetle larvae). Body temperature affected the profile of postprandial metabolism, increasing the peak and shortening the duration of the profile as body temperature increased. SDA was equivalent among three body temperatures (20 degrees, 25 degrees, and 30 degrees C) but decreased significantly at 15 degrees C. Comparatively, the postprandial metabolic responses and SDA of Ambystoma jeffersonianum, Ambystoma maculatum, Ambystoma opacum, Ambystoma talpoideum, Ambystoma texanum, and the conspecific Ambystoma tigrinum mavortium digesting cricket meals that were 5% of their body mass were similar (independent of body mass) to those of A. t. tigrinum. Among the six species, standard metabolic rate, peak postprandial VO(2), and SDA scaled with body mass with mass exponents of 0.72, 0.78, and 1.05, respectively.

Animals↗
PubMed2001

Protein synthesis and specific dynamic action in crustaceans: effects of temperature.

Temperature influences the specific dynamic action (SDA), or rise in oxygen uptake rate after feeding, in eurythermal and stenothermal crustaceans by changing the timing and the magnitude of the response. Intra-specific studies on the eurythermal crab, Carcinus maenas, show that a reduction in acclimation temperature is associated with a decrease in SDA magnitude, resulting from an increase in SDA duration but a decrease in peak factorial scope (the factorial rise in peak SDA over prefeeding values). Inter-specific feeding studies on stenothermal polar isopods revealed marked differences in SDA response between the Antarctic species, Glyptonotus antarcticus and the Arctic species, Saduria entomon. Compared to S. entomon held at 4 and 13 degrees C, the SDA response in G. antarcticus held at 1 degrees C was characterised by a lower absolute oxygen uptake rate at peak SDA and an extended SDA duration. At peak SDA, whole animal rates of protein synthesis increased in proportion to the postprandial increase in oxygen uptake rate in the Antarctic and the Arctic species. Rates of oxygen uptake plotted against whole animal rates of protein synthesis gave similar relationships in both isopod species, indicating similar costs of protein synthesis after a meal, despite their differences in SDA response and thermal habitat.

Animals↗
PubMed1991

Shortened dental arches and periodontal support.

The periodontal support of subjects with shortened dental arches (SDA, n = 74), and of subjects with SDA and free-end removable partial dentures in the lower jaw (SDA and RPD, n = 25) was compared with that of subjects with complete dental arches (CDA, n = 72). The periodontal support was determined by tooth mobility and alveolar bone height, measured on a radiograph, of the distal alveolar bone of the premolars. Significant differences in tooth mobility were found between the three groups of subjects. The relative bone height showed a trend towards lower values for the SDA group and the SDA and RPD group. For some teeth these differences were significant. Premolars that are the most posteriorly located occluding teeth in the dental arch tend to have a lower relative alveolar bone height than premolars in an intermediate location. This effect is more marked in the upper jaw than in the lower jaw. Premolars in the lower jaw, that serve as abutment teeth for free-end RPDs, tend to show lower values for the relative bone height. It is concluded that the differences between the three groups with regard to the periodontal support are small. The large amount of crowns and bridges in both the SDA and SDA and RPD groups, and the dental history of these subjects, resulting in SDA, should be taken into account. However, as indicated by the periodontal breakdown of premolars in some subjects with SDA, the combination of an existing severe periodontal involvement and a SDA is considered to be an unfavourable situation.

Alveolar Bone Loss↗
PubMed1983

The relationship of blood pressure to diet and lifestyle in two religious populations.

The association between blood pressure and a vegetarian diet was studied in relation to obesity, sex, age and lifestyle in 98 Seventh-day Adventist (SDA) lacto-ovo vegetarians, 82 SDA omnivores and 113 Mormon omnivores aged 25 to 44 years. Mean blood pressures adjusted for age, height and weight were significantly lower in SDA vegetarians than in Mormon omnivores (115.6/68.7 and 121.2/72.2, respectively, in males and 109.1/66.7 and 114.9/72.6, respectively, in females) and were not related to past or current use of alcohol, tobacco, tea and coffee, physical activity, personality or religious observance. Mean blood pressures in SDA omnivore males (121.7/71.7) were similar to those in Mormon males, while those in SDA omnivore females (109.9/67.4) were similar to SDA vegetarian females. Quetelet's Index in these subgroups demonstrated the same pattern as blood pressure and may reflect, in part, the high level of physical activity in female SDA omnivores. The prevalence of mild hypertension (greater than or equal to 140 mmHg systolic or greater than or equal to 90 mmHg diastolic) was 10 and 8.5% in Mormon and SDA omnivores, respectively, compared with 1 to 2% in SDA vegetarians. Analysis of diet records showed that vegetarians ate significantly more dietary fibre, polyunsaturated fat, magnesium and potassium and significantly less total fat, saturated fat and cholesterol than did Mormon omnivores. SDA omnivores had a dietary pattern which was less homogeneous, and which lay between those of the other groups. Which, if any, of these dietary differences were responsible for the blood pressure differences could not be determined in this study.

Adult↗
PubMed1980

Mortality among California Seventh-Day Adventists for selected cancer sites.

In previous reports concerning cancer among Seventh-Day Adventists (SDA), comparisons were made only with the general population. This report compared California SDA to a sample of non-SDA who were demographically similar to SDA. The study consisted of 17 years of follow-up (1960--76) on 22,940 white California SDA and 13 years of follow-up (1960--72) on 112,725 white California non-SDA. Both groups completed the same base-line questionnaire in 1960. Deaths were ascertained by annual contacts with each study member and by computer-assisted record linkage with the California State death certificate file. Results indicated that, with the exception of colon-rectal cancer and smoking-related cancers, the difference in risk of fatal cancer between SDA and non-SDA was substantially reduced when SDA were compared with a more socioeconomically similar population. The persistence of the low risk for colon-rectal cancer can probably be attributed to some aspect of the diet or life-style of the SDA.

Adult↗
PubMed1984

Acetylcholinesterase activity in the sexually dimorphic area of the gerbil brain: sex differences and influences of adult gonadal steroids.

The morphology of the medial preoptic area-anterior hypothalamus (MPOA-AH) of gerbils is sexually dimorphic and influenced by adult gonadal hormones. This research shows that the distribution of (MPOA-AH) cells that synthesize acetylcholinesterase (AChE) and the activity of AChE within the MPOA-AH are also sexually dimorphic and hormone sensitive. Adult male and female gerbils were gonadectomized, gonadectomized and implanted subcutaneously with testosterone (T), or sham operated 4-8 weeks before sacrifice. Coronal sections through the sexually dimorphic area (SDA) of the MPOA-AH were stained for AChE. Planimeter measurements of camera lucida drawings showed that the total volume of the SDA is similar in the two sexes, but the proportion of the SDA that stains darkly and/or stands out clearly from the surround (dark volume) is larger in males. Optical density readings also indicated that AChE staining is darker in the male SDA. Gonadectomy decreases staining intensity in both sexes and reduces total SDA volume. Dark volume decreases more than 50%. Testosterone treatment reverses all effects of gonadectomy, although hormonal influences are smaller in females than in males. There were no sex differences or hormonal influences on AChE staining lateral to the SDA. The pars compacta of the male SDA was essentially devoid of AChE, indicating that this cell group is distinct from the rest of the SDA. It also shrinks after castration unless the males receive T. Histochemical changes in the SDA may be related to hormonal control of scent marking, a form of communication in this species.

Acetylcholine↗
PubMed2005

The effect of meal composition on specific dynamic action in burmese pythons (Python molurus).

We quantified the specific dynamic action (SDA) resulting from the ingestion of various meal types in Burmese pythons (Python molurus) at 30 degrees C. Each snake was fed a series of experimental meals consisting of amino acid mixtures, simple proteins, simple or complex carbohydrates, or lipids as well as meals of whole animal tissue (chicken breast, beef suet, and mouse). Rates of oxygen consumption were measured for approximately 4 d after feeding, and the increment above standard metabolic rate was determined and compared to energy content of the meals. While food type (protein, carbohydrate, and lipid) had a general influence, SDA was highly dependent on meal composition (i.e., amino acid composition and carbohydrate structure). For chicken breast and simple carbohydrates, the SDA coefficient was approximately one-third the energetic content of the meal. Lard, suet, cellulose, and starch were not digested and did not produce measurable SDA. We conclude that the cost of de novo protein synthesis is an important component of SDA after ingestion of protein meals because (1) simple proteins, such as gelatin and collagen, did not stimulate levels of SDA attained after consumption of complete protein, (2) incomplete mixtures of amino acids failed to elicit the SDA of a complete mixture, and (3) the inhibition of de novo protein synthesis with the drug cycloheximide caused a more than 70% decrease in SDA. Stomach distension and mechanical digestion of intact prey did not cause measurable SDA.

Amino Acids↗
PubMed1986

Subcellular distribution of OM cytochrome b-mediated NADH-semidehydroascorbate reductase activity in rat liver.

Tissue, cellular, and subcellular distributions of OM cytochrome b-mediated NADH-semidehydroascorbate (SDA) reductase activity were investigated in rat. NADH-SDA reductase activity was found in the post-nuclear particulate fractions of liver, kidney, adrenal gland, heart, brain, lung, and spleen of rat. Liver, kidney, and adrenal gland had higher NADH-SDA reductase activity than other tissues, and OM cytochrome b-dependent activity was 60-70% of the total activity. On the other hand, almost all of the reductase activity of heart and brain cells was mediated by OM cytochrome b. The ratio of the OM cytochrome b-mediated activities of NADH-SDA reductase to rotenone-insensitive NADH-cytochrome c reductase varied among these tissues. OM cytochrome b-mediated NADH-SDA reductase and rotenone-insensitive NADH-cytochrome c reductase activities were mainly present in the parenchymal cells of rat liver. The localization of the cytochrome-mediated reductase activities in the outer mitochondrial membrane was confirmed by subfractionation of liver mitochondria. Among the submicrosomal fractions, OM cytochrome b-mediated NADH-SDA reductase activity was highest in the cis-Golgi membrane fraction, in which monoamine oxidase activity was also highest. On the other hand, OM cytochrome b-mediated rotenone-insensitive NADH-cytochrome c reductase activity showed a slightly different distribution pattern from the NADH-SDA reductase activity. Thenoyltrifluoroacetone (TTFA), a metal chelator, effectively inhibited the NADH-SDA reductase activity, though other metal chelators did not affect the activity. TTFA failed to inhibit rotenone-insensitive NADH-cytochrome c reductase activity at the concentration which gave complete inhibition of NADH-SDA reductase activity.

Adrenal Glands↗
PubMed1990

Ex vivo spermine dialdehyde treatment prevents lethal GVHD in a murine bone marrow transplantation model.

Spermine dialdehyde (SDA), an oxidized product of spermine which irreversibly suppresses T cell and NK cell activities, was evaluated as an ex vivo purging agent in the prevention of graft-versus-host disease (GVHD) in mice transplanted with SDA-treated allogeneic bone marrow. In this model, lethally irradiated C3H (H-2k) mice received BALB/c (H-2d) bone marrow and spleen cell mixtures which had been treated ex vivo for 10 min with SDA. Mice receiving SDA-treated cells survived past 100 days whereas mice in the control group died between days 25-35 suffering from severe GVHD. Surviving mice from the SDA-treated groups exhibited full chimerism at day 120. In vitro assays indicated that SDA inhibited T cell and NK cell activities at concentrations that spared myeloid cell growth. When a minimum number of bone marrow cells were used for reconstitution, SDA-treated marrow reconstituted lethally irradiated mice as effectively as control marrow suggesting that SDA had little impact on early myeloid cells which are required for engraftment. SDA may have clinical application as a purging agent in allogeneic bone marrow transplantation.

Animals↗
PubMed1990

Duration of protection from reinfection following exposure to sialodacryoadenitis virus in Wistar rats.

Wistar rats [Cr1:(WI)BR] were inoculated intranasally with approximately 10(3) median mouse lethal infective doses of sialodacryoadenitis (SDA) virus. Animals were subsequently selected at random, removed to a separate isolation room, and reinfected with SDA virus at 3, 6, 9, 12 or 15 months. Pre- and postinoculation serum samples were collected from all animals during the course of the study and evaluated for antibody titers to SDA virus. All experimental, control and sentinel animals, following inoculation with SDA virus, were necropsied and examined for lesions consistent with SDA. Salivary gland lesions were minimal to absent in rats reinfected with SDA virus for up to 12 to 15 months after the initial exposure and minimal to moderate in the respiratory tract at 12 or 15 months. SDA-associated lesions were extensive in age matched control animals examined at each time period of reinfection with SDA virus. Thus, prior exposure to SDA virus did protect against the development of typical salivary gland lesions for up to 15 months. Recovered animals were evaluated for their ability to transmit the virus following reinfection. Rats reinfected at 6 or 9 months were infectious to their naive cage mates. The results indicate that reinfection with homologous rat coronavirus can occur as early as 6 months after the initial infection, and such rats can transmit the infection to contact controls.

Animals↗
PubMed2006

Effects of meal size, meal type, and body temperature on the specific dynamic action of anurans.

Specific dynamic action (SDA), the increase in metabolism stemming from meal digestion and assimilation, varies as a function of meal size, meal type, and body temperature. To test predictions of these three determinants of SDA, we quantified and compared the SDA responses of nine species of anurans, Bombina orientalis, Bufo cognatus, Ceratophrys ornata, Dyscophus antongilli, Hyla cinerea, Kassina maculata, Kassina senegalensis, Pyxicephalus adspersus, and Rana catesbeiana subjected to meal size, meal type, and body temperature treatments. Over a three to seven-fold increase in meal size, anurans experienced predicted increases in postprandial rates of oxygen consumption (VO(2)) the duration of elevated VO(2) and SDA. Meal type had a significant influence on the SDA response, as the digestion and assimilation of hard-bodied, chitinous crickets, mealworms, and superworms required 76% more energy than the digestion and assimilation of soft-bodied earthworms, waxworms, and neonate rodents. Body temperature largely effected the shape of the postprandial metabolic profile; peak VO(2) increased and the duration of the response decreased with an increase in body temperature. Variation in body temperature did not significantly alter SDA for four species, whereas both H. cinerea and R. catesbeiana experienced significant increases in SDA with body temperature. For 13 or 15 species of anurans ranging in mass from 2.4 to 270 g, SMR, postprandial peak VO(2) and SDA scaled with body mass (log-log) with mass exponents of 0.79, 0.93, and 1.05, respectively.

Animal Feed↗