Effects of dietary lysine levels on the concentrations of selected nutrient metabolites in blood plasma of late-stage finishing pigs.

Lysine is the first-limiting amino acid (AA) in typical swine diets and plays very important roles in promoting growth performance of pigs. This research was conducted to study the effects of dietary lysine on blood plasma concentrations of protein, carbohydrate, and lipid metabolites of pigs. Eighteen crossbred finishing pigs (nine barrows and nine gilts; initial BW 92.3 ± 6.9 kg) were individually penned in an environment controlled barn. Pigs were assigned to three dietary treatments according to a randomized complete block design with gender as block and pig as experimental unit (6 pigs/treatment). Three corn and soybean meal-based diets were formulated to contain total lysine at 0.43%, 0.71%, and 0.98% (as-fed basis) for Diets I (lysine deficient), II (lysine adequate), and III (lysine excess) respectively. After 4 weeks on trial, jugular vein blood was collected and plasma was separated. The plasma concentrations of total protein, albumin, urea nitrogen (UN), triglyceride, total cholesterol, and glucose were determined using an ACE Clinical Chemistry System (Alfa Wassermann, Inc., West Caldwell, NJ, USA). Data were analysed using the GLM Procedure with PDIFF (adjust = T) option of SAS. No differences (p > 0.10) were found between barrows and gilts for any of the metabolites measured. While there were no differences (p > 0.10) between pigs fed Diets II and III in plasma concentrations of UN, albumin, and total cholesterol, the concentration of albumin in these pigs was higher (p < .05) than that of pigs fed Diet I, and the concentrations of UN and total cholesterol in these pigs were lower (p < .05) than that of pigs fed Diet I. There were no differences (p > 0.10) among the three dietary treatments in plasma concentrations of total protein, triglycerides, and glucose. These findings indicated that the plasma metabolite profile can be affected by changing dietary lysine content only. Thorough understanding how the plasma metabolite profile is alternated by dietary lysine will facilitate nutrient management for more sustainable swine production.

The use of digital infrared thermal imaging to detect estrus in gilts.

Yorkshire/Landrace crossbred gilts (N = 32) were evaluated using digital infrared thermal imaging (DITI) to discriminate between estrus and diestrus phases of the porcine estrous cycle. Gilts (N = 32) were part of an ongoing reproductive efficiency study involving the use of raw soybean (RSB; N = 15) versus soybean meal (SBM; N = 17) as a source of dietary protein. Gilts were monitored daily for signs of estrus using a teaser boar. Thermal images of vulva surface temperatures (TEMP) were recorded at standing estrus and diestrus. Measurements for analysis included minimum (MIN), maximum (MAX), mean (AVG), and standard deviation (SD) of temperature gradients. At imaging, ambient (AMB) and rectal temperatures (RT) were recorded, and blood samples taken for serum progesterone (P(4)) concentration analysis (by RIA) to confirm stage of cycle. Mean serum progesterone values at estrus and diestrus were (mean ± SD) 1.0 ± 0.1 and 10.9 ± 0.8 ng/mL, respectively. Vulva MIN, MAX, and AVG thermal images were positively correlated with one another (P < 0.01), and were positively correlated with ambient temperature (P < 0.01). Vulva MAX and AVG thermal temperatures were greater (P < 0.05) at estrus than at diestrus (36.6 ± 0.2 °C and 33.4 ± 0.3 °C vs. 35.6 ± 0.3 °C and 31.8 ± 0.6 °C, respectively), whereas MIN and SD had no differences (P > 0.05) between stages of the cycle. No differences (P > 0.05) in RT were detected between stages and RT was not significantly correlated with vulva thermal images. Diet had no significant effect on RT or vulva temperature.

Spectroscopic imaging of mineral maturation in bovine dentin.

Dentin is a useful model for the study of mineral maturation. Using Fourier Transform Infrared Imaging (FTIRI), we characterized distinct regions in developing dentin at 7- micro m spatial resolution. Mineral-to-matrix ratio and crystallinity in bovine dentin from cervical and incisal parts of 3rd-trimester fetal compared with one-year-old incisor crowns showed that virtually all maturation stages in dentin could be spectroscopically isolated and analyzed. In the fetal incisors, mantle and circumpulpal dentin presented distinct patterns of mineral maturation. Gradients in both mineral properties examined were observed at the mineralization front and at the dentino-enamel junction.

Comparison of the hydrolytic stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate with VX in dilute solution.

The stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate--a V-type nerve agent developed by the former Soviet Union--in the environment is an important parameter in threat assessment analysis and for the determination of use, production, testing and storage of this chemical warfare agent. S-(N,N-Diethylaminoethyl) isobutyl methylphosphonothiolate is a structural isomer of the nerve agent VX developed by the USA and the UK and will be referred to as VXA (VX analog) in this presentation. Because VXA and VX differ structurally, even though they do have the same molecular formula, it is expected that their physical and chemical properties would be different. This preliminary investigation was undertaken to determine the relative hydrolysis rate of VXA compared with VX. The hydrolysis of each compound at approximately 1 mg x ml(-1) in unbuffered water at pH 7 was determined side-by-side. The half-lives for VXA and VX were determined to be 12.4 days and 4.78 days, respectively. Agent VXA hydrolyzed 2.6 times more slowly than VX, and each agent followed second-order hydrolysis kinetics. These results imply that VXA is more persistent in the environment and therefore poses a greater threat. These results also imply that VXA is more likely to be detected, if present, during an inspection in support of the Chemical Weapons Convention.

In vitro apatite induction by phosphophoryn immobilized on modified collagen fibrils.

Noncollagenous phosphoproteins that interact with type I collagen are thought to nucleate the mineral phase to collagen network of mineralized tissues. Previously, we found that phosphophoryn cross-linked to type I collagen was an effective nucleator of apatite. Here, we investigated the potential role of collagen telopeptide structure on this nucleation. We used pepsin and sodium borohydride (NaBH4) to modify the telopeptide region and reducible cross-links in the collagen fibrils and determined the effect on mineral induction by phosphophoryn cross-linked to it. The amount of phosphophoryn cross-linked to NaBH4-reduced collagen fibrils was higher than that to intact (unmodified) collagen fibrils. However, the amount of phosphophoryn cross-linked to collagen that lacked the telopeptides (atelocollagen) was 25% of that cross-linked to intact collagen fibrils. Each preparation was incubated at 37 degrees C in metastable calcium phosphate solutions that did not spontaneously precipitate. Apatite was induced by phosphophoryn cross-linked to intact collagen fibrils at 15.0 h whereas phosphophoryn cross-linked to reduced collagen fibrils induced apatite formation after 10.9 h. Enough phosphophoryn was cross-linked to atelocollagen to induce mineral formation, but it did not. The failure of the phosphophoryn-atelocollagen complex to nucleate mineral might have been caused by a cross-linking pattern in the helical portion of the collagen molecule that did not promote the growth of the calcium-phosphate clusters into nuclei. The present study indicates that the telopeptide domains of type I collagen play a role in the interaction with phosphophoryn, which is critical for the nucleation process.

Thomson Thick X-Ray Absorption in a Broad Absorption Line Quasar, PG 0946+301.

We present a deep ASCA observation of a broad absorption line quasar (BALQSO) PG 0946+301. The source was clearly detected in one of the gas imaging spectrometers, but not in any other detector. If BALQSOs have intrinsic X-ray spectra similar to normal radio-quiet quasars, our observations imply that there is Thomson thick X-ray absorption (NH greater, similar1024 cm-2) toward PG 0946+301. This is the largest column density estimated so far toward a BALQSO. The absorber must be at least partially ionized and may be responsible for attenuation in the optical and UV. If the Thomson optical depth toward BALQSOs is close to 1, as inferred here, then spectroscopy in hard X-rays with large telescopes like XMM would be feasible.

Slow-wave sleep and waking cognitive performance among older adults with and without insomnia complaints.

Previous research has shown that healthy young adults with relatively fast reaction times on daytime testing have significantly more nocturnal slow-wave sleep than do age-matched subjects with relatively slow reaction times on such testing. The current study was conducted to examine the relationship between slow-wave sleep and cognitive performance among older adults with and without insomnia complaints. A sample of 32 noncomplaining older (age > or = 60 years) normal sleepers and a like-aged sample of 32 insomniacs, recruited to participate in a larger study, served as subjects. All subjects underwent nocturnal sleep monitoring immediately prior to undergoing a battery of daytime tests that measured simple reaction time, vigilance/signal detection, and complex reaction time. Results from the normal sleepers showed no relationship between daytime cognitive performance measures and a variety of computer-derived nocturnal slow-wave sleep measures. In contrast, insomniac subjects with relatively slow reaction times showed relative deficits in a spectral analytically derived measure of slow-wave power in the 2 to 4 Hz bandwidth. These results suggest that relative performance deficits among some older insomniacs may be related to specific slow-wave sleep deficiencies. However, among older normal sleepers, intersubject differences in performance appear unrelated to slow-wave sleep measures. Additional research is needed to further explore the possible restorative role slow-wave sleep may serve for cognitive functions other than those examined herein.

Intrinsic mineralization defect in Hyp mouse osteoblasts.

X-linked hypophosphatemia (XLH) is caused by inactivating mutations of PEX, an endopeptidase of uncertain function. This defect is shared by Hyp mice, the murine homologue of the human disease, in which a 3' Pex deletion has been documented. In the present study, we report that immortalized osteoblasts derived from the simian virus 40 (SV40) transgenic Hyp mouse (TMOb-Hyp) have an impaired capacity to mineralize extracellular matrix in vitro. Compared with immortalized osteoblasts from the SV40 transgenic normal mouse (TMOb-Nl), osteoblast cultures from the SV40 Hyp mouse exhibit diminished 45Ca accumulation into extracellular matrix (37 +/- 6 vs. 1,484 +/- 68 counts . min-1 . microgram protein-1) and reduced formation of mineralization nodules. Moreover, in coculture experiments, we found evidence that osteoblasts from the SV40 Hyp mouse produce a diffusible factor that blocks mineralization of extracellular matrix in normal osteoblasts. Our findings indicate that abnormal PEX in osteoblasts is associated with the accumulation of a factor(s) that inhibits mineralization of extracellular matrix in vitro.

Apatite induction by insoluble dentin collagen.

Phosphoproteins are thought to play a role in mineral formation in dentin. A portion of this phosphoprotein is bound to collagen. We have investigated the requirement for bound phosphate in mineral induction by isolated dentin collagen. Insoluble bovine dentin collagen obtained by ethylene-diamino-tetra-acetic acid (EDTA) demineralization had 19.5 mol of P/mol of collagen that could not be extracted with 0.5 M EDTA in 4 M guanidine HCl. When this collagen was incubated in supersaturated solutions that did not spontaneously precipitate, apatite was induced. With progressive enzymatic dephosphorylation, induction times for mineral formation became progressively longer. The dentin did not induce mineral formation when 90% of the ester phosphate was removed. Insoluble bone collagen, which had even less phosphate, also did not induce mineral formation. Mineral induction times by dentin collagen increased with decreasing solution saturations. Using these data, the interfacial tension for mineral induction was determined to be 90 ergs/cm2. This value approximated that of phosphatidic acid liposomes and of phosvitin cross-linked to agarose beads, and it might reflect the energetics of heterogeneous nucleation on a highly phosphorylated surface. Sequestering of calcium-phosphate clusters on the phosphoprotein probably accounts for the observed calcium binding by dentin collagen in excess of that required to neutralize the phosphate esters of the collagen. Because the phosphoprotein is immobilized at a low density on the collagen, it cannot self-associate in calcium-phosphate solutions as it does when it is free in solution. This immobilized phosphoprotein allows the mineral clusters formed on its surface to grow into a crystalline order.

Mineral induction by immobilized phosphoproteins.

Dentin phosphoproteins are thought to have a primary role in the deposition of mineral on the collagen of dentin. In this study we determined the type of binding between collagen and phosphoproteins necessary for mineral formation onto collagen fibrils and whether the phosphate esters are required. Bovine dentin phosphophoryn or phosvitin from egg yolk were immobilized on reconstituted skin type I collagen fibrils by adsorption or by covalent cross-linking. In some samples the ester phosphate was removed from the covalently cross-linked phosphoproteins by treatment with acid phosphatase. All samples were incubated at 37 degrees C in metastable solutions that do not spontaneously precipitate. Reconstituted collagen fibrils alone did not induce mineral formation. The phosphoproteins adsorbed to the collagen fibrils desorbed when the mineralization medium was added, and mineral was not induced. The mineral induced by the cross-linked phosphoproteins was apatite, and the crystals were confined to the surface of the collagen fibrils. With decreasing medium saturation the time required for mineral induction increased. The interfacial tensions calculated for apatite formation by either phosphoprotein cross-linked to collagen were about the same as that for phosphatidic acid liposomes and hydroxyapatite. This similarity in values indicates that the nucleation potential of these highly phosphorylated surfaces is about the same. It is concluded that phosphoproteins must be irreversibly bound to collagen fibrils for the mineralization of the collagen network in solutions that do not spontaneously precipitate. The phosphate esters of phosphoproteins are required for mineral induction, and the carboxylate groups are not sufficient.

In-line respeciation: an ion-exchange ion chromatographic method applied to the separation of degradation products of chemical warfare nerve agents in soil.

The natural background of anions encountered when analyzing soil samples by ion chromatography (IC) present significant problems in the separation, detection and quantification of isopropyl methylphosphonic acid (IMPA) and methylphosphonic acid (MPA), the degradation products of sarin, a chemical warfare nerve agent. Using chemically-suppressed IC with conductivity detection, a commercially available ion-exchange column, and an isocratic binary eluent system, IMPA and MPA were determined in aqueous extracts of soil at sub-ppm (microgram/g) concentrations without the need for gradient elution or organic solvent eluent modifiers. Common soil anions such as chloride, nitrate, sulfate and phosphate do not interfere with the analysis method due to the composition of the binary eluent allowing for greater mobilization of multivalent anions (e.g., MPA, carbonate, and sulfate) while monovalent anions (e.g., IMPA and nitrate) are relatively unaffected. Carbonate is selectively removed by in-line respeciation to bicarbonate.

Local field effects in multicomponent media.

We investigate local-field effects in nonlinear optical materials composed of two species of atoms. One species of atom is assumed to be near resonance with an applied field and is modeled as a two-level system while the other species of atom is assumed to be in the linear regime. If the near dipole-dipole interaction between two-level atoms is negligible, the usual local-field enhancement of the field is obtained. For the case in which near-dipole-dipole interactions are significant due to a high density of two-level atoms, local-field effects associated with the presence of a optically linear material component lead to local-field enhancement of the near dipole-dipole interaction, intrinsic cooperative decays, and coherence exchange processes.

Three-dimensional analysis of mineralizing turkey leg tendon: matrix vesicle-collagen relationships.

The spatial and temporal relationships of mineral deposition between matrix vesicles and type I collagen fibrils have been studied in the turkey leg tendon by electron microscopy of cross sections and serial longitudinal thin sections and by electron tomography of longitudinal thick sections. Serial sectioning and electron tomography allow three-dimensional analysis of spatial relationships, overcoming the problems of missing depth information and over-projection of adjacent structures which exist for two-dimensional projections of isolated sections. These techniques reveal that while mineral deposits within matrix vesicles are found remote from calcifying collagen fibrils, the reverse relationship does not occur; all collagen-associated mineral can ultimately be linked to mineral-laden vesicles. These results suggest a temporal sequence of calcification beginning in matrix vesicles and spreading to adjacent collagen fibrils.

The fourth-year medical school curriculum: recommendations of the Association of Professors of Gynecology and Obstetrics and the Council on Resident Education in Obstetrics and Gynecology.

OBJECTIVES: The Association of Professors of Gynecology and Obstetrics and the Council on Resident Education in Obstetrics and Gynecology have proposed a fourth-year medical school curriculum for a student interested in pursuing a residency in obstetrics and gynecology. STUDY DESIGN: Faculty members and residents in North Carolina, Illinois, and Michigan were surveyed as to the ideal curriculum that they would recommend for fourth-year students. The committee members representing the Council on Resident Education in Obstetrics and Gynecology and the Association of Professors of Gynecology and Obstetrics then reviewed these surveys and proposed a final curriculum. RESULTS: A core curriculum of general medicine as an acting internship, an intensive care unit rotation, neonatology, and emergency medicine was recommended. Additional courses strongly considered were ambulatory obstetrics-gynecology, acting internship in obstetrics-gynecology, endocrinology, and general surgery. CONCLUSION: The committee recommends a curriculum that is broad and balanced in general medical education.

Calcium movement in vivo and in vitro in secretory-stage enamel of rat incisors.

The lower incisors of young rats were dissected, immersed in physiological saline containing 45Ca under various conditions, and processed for autoradiography. The data were compared with those from in vivo 45Ca autoradiography. In secretory-stage enamel, wiped free of the enamel organ and immediately immersed in radioactive saline, there was intense labelling in the surface layers. The labelled area expanded only gradually into the deeper layers at a rate similar to that observed in vivo. Labelling in the enamel was similar in pattern but much weaker in intensity when the incisor was identically treated in vitro with the enamel organ attached. Glutaraldehyde pretreatment of the exposed enamel abolished expansion of the labelled area, whereas a hypochlorite pretreatment allowed a rapid diffusion of the isotope into the deeper layers of the secretory-stage enamel. The findings confirm the role of the enamel organ as a diffusion barrier to the penetration of calcium from the extracellular fluid to the secretory-stage enamel, and suggest an intimate correlation between physicochemical properties of the organic enamel matrix and the rate of surface-to-interior diffusion of calcium within the secretory-stage enamel of rat incisors.

An antigen immunologically related to the external domain of gp185 is shed from nude mouse tumors overexpressing the c-erbB-2 (HER-2/neu) oncogene.

An antigen, immunologically related to the external domain of the c-erbB-2 (HER-2/neu) protein, was found shed into the serum of nude mice bearing tumors that overexpress the c-erbB-2 protein (gp185). Utilizing paired combinations from a panel of monoclonal antibodies (TAbs 250-265), with specificity for extracellular epitopes of gp185, an immunoradiometric assay was developed to quantitate this shed antigen. The immunoradiometric assay detected membrane-bound and soluble gp185 as well as a soluble derivative corresponding in sequence to the extracellular domain of gp185 (designated gp75). This recombinantly expressed gp75 was immunoaffinity purified and used to generate a standard curve from which serum samples were quantitated. Increases in antigen levels measured in the sera of tumor-bearing nude mice correlated with both overexpression of the c-erbB-2 protein and increased tumor volume. Positive sera were obtained from mice given implants of NIH3T3 cells transfected with c-erbB-2 complementary DNA (NIH3T3t), or ovarian (SK-OV-3) or breast (MDA-MB-361) tumor cell lines overexpressing the c-erbB-2 protein. In mice bearing NIH3T3t tumors, increases in tumor volume from 80 to 9000 mm3 resulted in levels of shed antigen from 8 to greater than 1000 ng/ml gp75 equivalents. Sera from mice with c-erbB-2-negative tumors or tumors overexpressing the epidermal growth factor receptor were negative in the assay. This assay, and the quantitation of shed antigen levels, may have diagnostic or monitoring utility in cancers, such as breast and ovarian, in which the c-erbB-2 protein is overexpressed.

Effects of time required for reperfusion (thrombolysis or angioplasty, or both) and location of acute myocardial infarction on left ventricular functional reserve capacity several months later.

The purpose of this study was to determine whether reperfusion of acute myocardial infarction (AMI) by recombinant tissue-type plasminogen activator (rt-PA) or percutaneous transluminal coronary angioplasty, or both, would improve left ventricular (LV) function when it is measured several months later at rest or maximal bicycle exercise, or both. Radionuclide angiography was performed in 44 patients 5 months (range 6 weeks to 9 months) after AMI to assess function, and tomographic myocardial thallium-201 imaging was performed at maximal exercise and delayed rest to determine whether there was any evidence of myocardial ischemia. As expected, no patient had chest pain or redistribution of a thallium defect during the exercise test, because patients had undergone angioplasty (n = 28) or coronary bypass graft surgery (n = 5) where clinically indicated for revascularization. The LV ejection fraction was plotted as a function of the time elapsed between the onset of chest pain and the time when coronary angiography confirmed patency of the infarct-related artery (achieved in 91% of 44 patients by rt-PA [n = 31] or percutaneous transluminal coronary angioplasty [n = 9] ). Functional responses differed markedly between patients with anterior (n = 20) versus inferior (n = 24) wall AMI. LV ejection fraction during exercise correlated with time to reperfusion in patients with an anterior wall AMI (r = -0.58; standard error of the estimate = 11.9%; p less than 0.02) but not in patients with an inferior AMI (r = 0.10; standard error of the estimate = 13.1%; difference not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Tocolysis in the management of third trimester bleeding.

Fifteen patients were identified in a retrospective analysis of one institution's experience with the use of tocolysis in selected patients with an admission diagnosis of placenta previa or abruptio placentae. There were no fetal deaths after admission, and the two neonatal deaths were related to prematurity. Eight of the 15 patients receiving tocolysis had their pregnancies prolonged by 2 weeks or more, and there were no fetal or neonatal deaths in this group. Both neonatal deaths occurred in patients who underwent tocolysis but who gave birth within 1 day of admission. These data suggest the safety of tocolysis in preterm patients with the diagnosis of placenta previa or abruption who are bleeding. A prospective, randomized trial is required to evaluate whether tocolysis is superior to expectant management or to immediate delivery. The clinical difficulty in differentiating between these two diagnoses, despite liberal use of ultrasonography, is discussed.

Mineral induction by immobilized polyanionic proteins.

The purpose of this study was to investigate the mineral induction capacity in vitro of polyanionic proteins covalently bound to a surface. Rat dentin gamma-carboxyglutamate-containing protein of the osteocalcin type (Gla-protein), proteoglycan (PG), and phosphoprotein (PP-H), as well as phosvitin (PhV) and bovine serum albumin (BSA), were covalently linked to agarose beads. There were incubated at 37 degrees C in solutions with a Ca/P molar ratio of 1.67, [Ca][P] molar products in the range 1.0-1.8 mM2, and an ionic strength of 0.165. The incubations were performed at constant pH and composition conditions; no spontaneous precipitation occurred under these conditions. Mineral formation, as monitored by scanning electron microscopy (SEM), was induced by all immobilized polyanions, including enzymatically dephosphorylated PP-H and PhV. No mineral was induced by BSA. The mineral inductive capacity of immobilized polyanionic proteins, as judged by the SEM after identical incubations, was found to differ between the different ligands. The mineral induced by PP-H and PG was shown by X-ray diffraction to be apatitic. It was concluded that, although polyanionic proteins in solution may inhibit mineral induction and growth, very minute quantities of such molecules, when immobilized on a surface, induce mineral at physiological concentrations of calcium and phosphate ions. The data presented may be taken to suggest that PP-H and PG, and perhaps other polyanions, may possibly be responsible for mineral nucleation in dentin and bone. The results, however, also point to the rather limited specificity in this type of reaction.